Papers - TANIBATA Naoto
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Applying the HSAB design principle to the 3.5 V-class all-solid-state Li-ion batteries with a chloride electrolyte Reviewed
Naoto Tanibata, Shuta Takimoto, Shin Aizu, Hayami Takeda, Masanobu Nakayama
Journal of Materials Chemistry A 10 ( 39 ) 20756 - 20760 2022.09
Authorship：Lead author, Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：ROYAL SOC CHEMISTRY
All-solid-state Li-ion batteries are expected to be the next generation of batteries with a high energy density and safety. However, for Li-ion batteries to endure high-voltage operations, the decomposition of solid electrolytes must be suppressed first. A high potential at the cathode tends to promote battery degradation because of the oxidation of the cathode electrolyte. This study aims to achieve the high-potential operation of all-solid-state batteries using LiAlCl4 as a chloride electrolyte with a high oxidation resistance. However, batteries with commonly used oxide electrodes (e.g., LiFePO4) exhibit low capacity (∼0.5 mA h g−1), despite having working potentials less than the oxidation potential of LiAlCl4. First-principles calculations and 27Al MAS-NMR measurements suggest that acid–base reactions based on the hard and soft acid–base (HSAB) rule occur between the electrode and the electrolyte. In contrast, a high voltage of ∼3.65 V (vs. Li+/Li) and high-capacity utilisation (reversible capacity ∼100 mA h g−1) are observed at room temperature by combining the same chloride electrode (Li2FeCl4) without side reactions between these chlorides. These results indicate that material design based on the HSAB rule is also instructive when considering electrode/electrolyte material combinations, which realizes a 3.5 V-class all-solid-state Li-ion battery.
DOI： 10.1039/D2TA05152D
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Metastable Chloride Solid Electrolyte with High Formability for Rechargeable All-Solid-State Lithium Metal Batteries Reviewed
Naoto Tanibata, Shuta Takimoto, Koki Nakano, Hayami Takeda, Masanobu Nakayama, Hirofumi Sumi
ACS Materials Letters 2 ( 8 ) 880 - 886 2020.08
Authorship：Lead author, Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：American Chemical Society ({ACS})
Dense solid electrolytes in all-solid-state Li batteries are expected to suppress Li dendrite phenomena that prevent the application of high-energy-density Li metal electrodes. However, voids and cracks in sintered electrolytes still permit short-circuiting due to Li dendrites. This study aimed to investigate solid electrolytes with high formability in which green compacts can prevent Li dendrites. Li+ ion migration energies, bulk moduli, and energies above the hull were comprehensively investigated using first-principles and classical force field calculations as the indicators for ionic conductivity, formability, and thermodynamic stability. The 231 compounds containing Li and Cl listed in the Materials Project database were studied due to their high polarizability and weak Coulombic interaction with Li+ ions. Among them, monoclinic LiAlCl4 (LAC, S.G.: P121/c1) was focused on, owing to its low values of all three indicators. A mechanochemical synthesis was attempted to prepare the metastable phase, where Li ions occupy the interstitial sites, not just the original sites, because the computation for the migration energy suggested conductive pathways between the original Li sites. XRD and 7Li-MAS NMR measurements indicated that the mechanochemically synthesized LAC possessed a monoclinic host structure, while 2.5% Li occupied interstitial tetrahedral sites. Impedance measurements showed that the LAC green compacts exhibited an ionic conductivity of 2.1 × 10–5 S cm–1, 20 times higher than the conventional solid-state synthesized LAC at room temperature. The conductivity was more than one order of magnitude higher than that of garnet-type Li6.6La3Zr1.6Ta0.4O12 (LLZT), which has been attractive for the application of the sintered body for Li metal electrodes. The SEM observations and distribution of relaxation times analysis indicated that dense LAC green compacts with large necking between the particles contributed minimal grain-boundary resistance (7.5%) to the total resistance, while the LLZT green compacts contributed almost completely (99%). Li metal symmetric cells using the LAC pellet showed good cycle performance without short-circuiting and an overvoltage increase for 70 cycles at a current density of 0.1 mA cm–2, while short circuiting occurred at the 1st cycle in the LLZT cells.
File： Manuscript file.pdf
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Nanotube-structured Na2V3O7 as a Cathode Material for Sodium-Ion Batteries with High-rate and Stable Cycle Performances Reviewed International journal
Naoto Tanibata, Yuki Kondo, Shohei Yamada, Masaki Maeda, Hayami Takeda, Masanobu Nakayama, Toru Asaka, Ayuko Kitajou, Shigeto Okada
Scientific Reports 8 ( 1 ) 17199 - 17199 2018.11
Authorship：Lead author, Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：Springer Nature
© 2018, The Author(s). Sodium ion batteries meet the demand for large-scale energy storage, such as in electric vehicles, due to the material abundance of sodium. In this report, nanotube-type Na2V3O7 is proposed as a cathode material because of its fast sodium diffusivity, an important requirement for sodium ion batteries, through the investigation of ~4300 candidates via a high-throughput computation. High-rate performance was confirmed, showing ~65% capacity retention at a current density of 10C at room temperature, despite the large particle size of >5 μm. A good cycle performance of ca. 94% in capacity retention after 50 cycles was obtained owing to a small volumetric change of <0.4%.
File： s41598-018-35608-9.pdf
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Causal Analysis of Factors for Li Ionic Conductivity in Olivine-Type LiMXO<sub>4</sub> Materials Using LiNGAM Reviewed
Koichi Gocho, Masato Hamaie, Naoto Tanibata, Hayami Takeda, Masanobu Nakayama, Masayuki Karasuyama, Ryo Kobayashi
The Journal of Physical Chemistry C 2025.01
Language：English Publishing type：Research paper (scientific journal) Publisher：American Chemical Society (ACS)
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Fast Anion Redox by Amorphization in Sodium-Ion Batteries Reviewed
Naoto Tanibata, Sayaka Kondo, Suzuno Akatsuka, Hayami Takeda, Masanobu Nakayama
Chemistry of Materials 37 ( 1 ) 303 - 312 2024.12
Authorship：Lead author, Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：American Chemical Society (ACS)
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Deep learning based emulator for predicting voltage behaviour in lithium ion batteries Reviewed
Kanato Oka, Naoto Tanibata, Hayami Takeda, Masanobu Nakayama, Syuto Noguchi, Masayuki Karasuyama, Yoshiya Fujiwara, Takuhiro Miyuki
Scientific Reports 14 ( 1 ) 28905 2024.11
Language：English Publishing type：Research paper (scientific journal) Publisher：Springer Science and Business Media LLC
Abstract
This study presents a data-driven battery emulator using long short-term memory deep learning models to predict the charge–discharge behaviour of lithium-ion batteries (LIBs). This study aimed to reduce the economic costs and time associated with the fabrication of large-scale automotive prototype batteries by emulating their performance using smaller laboratory-produced batteries. Two types of datasets were targeted: simulation data from the Dualfoil model and experimental data from liquid-based LIBs. These datasets were used to accurately predict the voltage profiles from the arbitrary inputs of various galvanostatic charge–discharge schedules. The results demonstrated high prediction accuracy, with the coefficient of determination scores reaching 0.98 and 0.97 for test datasets obtained from the simulation and experiments, respectively. The study also confirmed the significance of state-of-charge descriptors and inferred that a robust model performance could be achieved with as few as five charge–discharge training datasets. This study concludes that data-driven emulation using machine learning can significantly accelerate the battery development process, providing a powerful tool for reducing the time and economic costs associated with the production of large-scale prototype batteries.DOI： 10.1038/s41598-024-80371-9
Other Link： https://www.nature.com/articles/s41598-024-80371-9
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Prediction of Li-ion conductivity in Ca and Si co-doped LiZr2(PO4)3 using a denoising autoencoder for experimental data Reviewed
Yumika Yokoyama, Shuto Noguchi, Kazuki Ishikawa, Naoto Tanibata, Hayami Takeda, Masanobu Nakayama, Ryo Kobayashi, Masayuki Karasuyama
APL Materials 2024.11
Language：English Publishing type：Research paper (scientific journal)
DOI： 10.1063/5.0231411
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Investigation of Effect of Heterovalent Element Doping on Ionic Conductivity in Li3InCl6 System Using Neural-network Potential Reviewed
Takeshi USAMI, Koichi GOCHO, Naoto TANIBATA, Hayami TAKEDA, Masanobu NAKAYAMA
Electrochemistry 92 ( 11 ) 117001 - 117001 2024.11
Language：English Publishing type：Research paper (scientific journal) Publisher：The Electrochemical Society of Japan
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Universal Neural Network Potential-Driven Molecular Dynamics Study of CO<sub>2</sub>/O<sub>2</sub> Evolution at the Ethylene Carbonate/Charged–Electrode Interface Reviewed
Motoki Horibe, Naoto Tanibata, Hayami Takeda, Masanobu Nakayama
ACS Applied Materials & Interfaces 16 ( 40 ) 53621 - 53630 2024.09
Language：English Publishing type：Research paper (scientific journal) Publisher：American Chemical Society (ACS)
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Universal-neural-network-potential molecular dynamics for lithium metal and garnet-type solid electrolyte interface Reviewed
Rinon Iwasaki, Naoto Tanibata, Hayami Takeda, Masanobu Nakayama
Communications Materials 5 ( 1 ) 148 2024.08
Language：English Publishing type：Research paper (scientific journal) Publisher：Springer Science and Business Media LLC
Abstract
All-solid-state Li-metal batteries can conceivably improve the safety and extend the driving ranges of electric vehicles. In this regard, the garnet-type solid electrolyte Li<sub>7</sub>La<sub>3</sub>Zr<sub>2</sub>O<sub>12</sub> (LLZ) has garnered considerable attention because of its high Li-ion conductivity and nonreactivity towards molten Li metal. Here, we perform molecular dynamics (MD) simulations using a universal neural network potential (UNNP) to analyse the Li-ion exchange at the LLZ/Li interface at the atomic scale. The UNNP-MD calculations show that Li ions traverse the LLZ/Li interface and that excess Li ions relative to the stoichiometric composition accumulate in an approximately 1 nm-thick zone near the LLZ phase interface, signifying the formation of a space-charge layer. Electronic structural analysis of the UNNP-MD-derived configuration, performed using density functional theory calculations, reveals band bending near the LLZ phase interface and the simultaneous suppression of Li metal reduction. These findings can help expedite the development of rationally designed all-solid-state Li-metal batteries.DOI： 10.1038/s43246-024-00595-0
Other Link： https://www.nature.com/articles/s43246-024-00595-0
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Effect of synthesis process on the Li-ion conductivity of LiTa<sub>2</sub>PO<sub>8</sub> solid electrolyte materials for all-solid-state batteries Reviewed
Hayami Takeda, Miki Shibasaki, Kento Murakami, Miki Tanaka, Keisuke Makino, Naoto Tanibata, Hirotaka Maeda, Masanobu Nakayama
Energy Advances 3 ( 9 ) 2238 - 2244 2024.07
Language：English Publishing type：Research paper (scientific journal) Publisher：Royal Society of Chemistry (RSC)
Tailoring grain boundary resistivity in LiTa<sub>2</sub>PO<sub>8</sub> for improved ionic conductivity, offering insights into enhancing the performance of oxide solid electrolytes for safer all-solid-state batteries.
DOI： 10.1039/d4ya00180j
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Guidelines for designing high-deformability materials for all-solid-state lithium-ion batteries Reviewed
Naoto Tanibata, Shin Aizu, Misato Koga, Hayami Takeda, Ryo Kobayashi, Masanobu Nakayama
Journal of Materials Chemistry A 12 15601 - 15607 2024.06
Authorship：Lead author, Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：Royal Society of Chemistry (RSC)
Shear modulus G is a useful screening index and design guideline for high deformability, including for dense pellets and/or negligible particle grain boundary in compressed pellets, which are especially required for all-solid-state batteries.
DOI： 10.1039/d4ta02328e
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Influence of atmospheric moisture on the gas evolution tolerance of halide solid electrolytes Reviewed
Takeshi Usami, Naoto Tanibata, Hayami Takeda, Masanobu Nakayama
Journal of Solid State Electrochemistry 2024.04
Language：English Publishing type：Research paper (scientific journal) Publisher：Springer Science and Business Media LLC
Abstract
Much attention has been paid on research and development on solid electrolytes for all-solid-state Li batteries. Although halide solid electrolytes such as Li<sub>3</sub>YCl<sub>6</sub> and Li<sub>3</sub>InCl<sub>6</sub> are promising due to fast Li ion conductivity and oxidation-resistant against positive electrode, a better understanding of their reactivity with atmospheric H<sub>2</sub>O is required for commercialization. In this study, the gas evolution tolerances of Li<sub>3</sub>YCl<sub>6</sub> and Li<sub>3</sub>InCl<sub>6</sub> were investigated. Temperature-programmed desorption mass spectrometry (TPD-MS) experiments at dew points below − 60 °C and gas detector tube experiments at dew points of − 30 °C both revealed significant differences in the H<sub>2</sub>O and HCl evolution behavior of Li<sub>3</sub>YCl<sub>6</sub> and Li<sub>3</sub>InCl<sub>6</sub>. In TPD-MS, the onset temperature of HCl evolution for Li<sub>3</sub>YCl<sub>6</sub> (~ 100 °C) was significantly lower than that for Li<sub>3</sub>InCl<sub>6</sub> (~ 220 °C), indicating that Li<sub>3</sub>InCl<sub>6</sub> solid electrolytes have superior gas evolution tolerance. This difference may be attributable to differences in the retention of H<sub>2</sub>O derived from the material synthesis stage and from contact with the atmosphere during the measurements. In particular, based on first-principles calculations, the low-temperature HCl evolution observed in Li<sub>3</sub>YCl<sub>6</sub> was ascribed to the partial replacement of Cl<sup>−</sup> ions by OH<sup>−</sup> ions upon contamination with trace H<sub>2</sub>O. Because the heating and drying of solid electrolytes (including slurries) are inevitable processes during battery manufacturing, these findings can aid in the rational design of halide solid electrolytes for all-solid-state batteries.DOI： 10.1007/s10008-024-05880-z
Other Link： https://link.springer.com/article/10.1007/s10008-024-05880-z/fulltext.html
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Computational studies on Mg ion conductivity in Mg2xHf1-x Nb(PO4)3 using neural network potential Reviewed
Keisuke Makino, Naoto Tanibata, Hayami Takeda, Masanobu Nakayama
Journal of Solid State Electrochemistry 2024.04
Language：English Publishing type：Research paper (scientific journal) Publisher：Springer Science and Business Media LLC
Abstract
Low Mg diffusivity in solid-state oxides is an obstacle for the development of materials for Mg ion batteries, which are expected to have high capacity. In this study, we focused on NASICON-type and β-iron sulfate-type Mg<sub>2x</sub>Hf<sub>1-x</sub>Nb(PO<sub>4</sub>)<sub>3</sub> that exhibit relatively high Mg ionic conductivity and investigated the Hf/Nb configuration and composition dependence of phase stability and ion conductivity by atomistic simulation using neural network potentials. The calculations show that the NASICON-type structure is slightly more stable and has higher Mg ionic conductivity than that of the β-iron sulfate-type. The effect of the Hf/Nb configuration was investigated and showed that the ordered stable structure had much lower ionic conductivity than the disordered structure. Furthermore, as the Mg ion concentration increased, the ionic conductivity increased monotonically at low concentrations but tended to converge to a constant value above a certain concentration. The saturation of the ionic conductivity despite increasing the Mg concentration may be due to the trapping effect of the Mg ions caused by the Hf vacancies as well as the Hf/Nb arrangement.
Graphical AbstractDOI： 10.1007/s10008-024-05862-1
Other Link： https://link.springer.com/article/10.1007/s10008-024-05862-1/fulltext.html
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Chloride electrode composed of ubiquitous elements for high-energy-density all-solid-state sodium-ion batteries Reviewed
Naoto Tanibata, Naoki Nonaka, Keisuke Makino, Hayami Takeda, Masanobu Nakayama
Scientific Reports 14 ( 1 ) 2703 2024.02
Authorship：Lead author, Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：Springer Science and Business Media LLC
Abstract
Inexpensive and safe energy-storage batteries with high energy densities are in high demand (e.g., for electric vehicles and grid-level renewable energy storage). This study focused on using NaFeCl<sub>4</sub>, comprising ubiquitous elements, as an electrode material for all-solid-state sodium-ion batteries. Monoclinic NaFeCl<sub>4</sub>, expected to be the most resource-attractive Fe redox material, is also thermodynamically stable. The Fe<sup>2+/3+</sup> redox reaction of the monoclinic NaFeCl<sub>4</sub> electrode has a higher potential (3.45 V vs. Na/Na<sup>+</sup>) than conventional oxide electrodes (e.g., Fe<sub>2</sub>O<sub>3</sub> with 1.5 V vs. Na/Na<sup>+</sup>) because of the noble properties of chlorine. Additionally, NaFeCl<sub>4</sub> exhibits unusually high deformability (99% of the relative density of the pellet) upon uniaxial pressing (382 MPa) at 298 K. NaFeCl<sub>4</sub> operates at 333 K in an electrode system containing no electrolyte, thereby realizing next-generation all-solid-state batteries with high safety. A high energy density per positive electrode of 281 Wh kg<sup>−1</sup> was achieved using only a simple powder press.DOI： 10.1038/s41598-024-53154-5
Other Link： https://www.nature.com/articles/s41598-024-53154-5
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Analysis of ion conduction behavior of Nb- and Zr-doped Li3InCl6-based materials via material simulation Reviewed
Takeshi Usami, Naoto Tanibata, Hayami Takeda, Masanobu Nakayama
APL Materials 11 ( 12 ) 2023.12
Language：English Publishing type：Research paper (scientific journal) Publisher：AIP Publishing
The Li-ion conductivities of Li3InCl6 (LIC), which is a promising chloride solid electrolyte, and its compositional derivatives, Nb5+- and Zr4+-doped LIC, i.e., Li3−2xIn1−xNbxCl6 and Li3−yIn1−yZryCl6, respectively, were experimentally and computationally investigated. An increase in the ionic conductivity caused by Nb5+ or Zr4+ doping, which was due to the increase in Li vacancies, was observed in both the experimental and computational results. Nb5+ doping yielded a larger increase in conductivity at 60 °C. First-principles molecular dynamics studies indicated two factors affecting the Li-ion conductivity under doping with higher-valent ions: (1) the vacancy trapping effect and (2) the reduction in the phase-transition temperature from a Li/vacancy ordered structure to a disordered structure. In particular, in factor (2), the effect of Nb5+ doping is larger than that of Zr4+ doping, which supports the improvement in ionic conductivity at 333 K in the experiment.
DOI： 10.1063/5.0167817
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Fast Na-diffusive tin alloy for all-solid-state Na-based batteries Reviewed
Naoto Tanibata, Koki Matsunoshita, Hirokazu Takeuchi, Suzuno Akatsuka, Misato Koga, Hayami Takeda, Masanobu Nakayama
Journal of Materials Chemistry A 11 ( 47 ) 25859 - 25864 2023.12
Authorship：Lead author, Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：Royal Society of Chemistry (RSC)
A metastable-phase Na–Sn binary alloy exhibiting exceptionally high Na diffusivity at room temperature (D<sub>25</sub> = 5.4 × 10<sup>−7</sup> cm<sup>2</sup> s<sup>−1</sup>) was applied to a next-generation all-solid-state sodium battery, achieving ultralow energy loss properties.
DOI： 10.1039/d3ta02787b
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Materials Informatics for Thermistor Properties of Mn–Co–Ni Oxides Reviewed
Shogo Hashimura, Yudai Yamaguchi, Hayami Takeda, Naoto Tanibata, Masanobu Nakayama, Naohiro Niizeki, Takayuki Nakaya
The Journal of Physical Chemistry C 2023.11
Language：English Publishing type：Research paper (scientific journal) Publisher：American Chemical Society (ACS)
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Drawing a materials map with an autoencoder for lithium ionic conductors Reviewed
Yudai Yamaguchi, Taruto Atsumi, Kenta Kanamori, Naoto Tanibata, Hayami Takeda, Masanobu Nakayama, Masayuki Karasuyama, Ichiro Takeuchi
Scientific Reports 13 ( 1 ) 2023.10
Language：English Publishing type：Research paper (scientific journal) Publisher：Springer Science and Business Media LLC
Abstract
Efforts to optimize known materials and enhance their performance are ongoing, driven by the advancements resulting from the discovery of novel functional materials. Traditionally, the search for and optimization of functional materials has relied on the experience and intuition of specialized researchers. However, materials informatics (MI), which integrates materials data and machine learning, has frequently been used to realize systematic and efficient materials exploration without depending on manual tasks. Nonetheless, the discovery of new materials using MI remains challenging. In this study, we propose a method for the discovery of materials outside the scope of existing databases by combining MI with the experience and intuition of researchers. Specifically, we designed a two-dimensional map that plots known materials data based on their composition and structure, facilitating researchers’ intuitive search for new materials. The materials map was implemented using an autoencoder-based neural network. We focused on the conductivity of 708 lithium oxide materials and considered the correlation with migration energy (ME), an index of lithium-ion conductivity. The distribution of existing data reflected in the materials map can contribute to the development of new lithium-ion conductive materials by enhancing the experience and intuition of material researchers.DOI： 10.1038/s41598-023-43921-1
Other Link： https://www.nature.com/articles/s41598-023-43921-1
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Characterization of a Novel Chloride Li-ion Conductor Li<sub>2</sub>LuCl<sub>5</sub> Reviewed
Shin AIZU, Naoto TANIBATA, Hayami TAKEDA, Masanobu NAKAYAMA
Electrochemistry 2023.10
Authorship：Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：The Electrochemical Society of Japan
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Optimization of force-field potential parameters using conditional variational autoencoder Reviewed
Koki Matsunoshita, Yudai Yamaguchi, Masato Hamaie, Motoki Horibe, Naoto Tanibata, Hayami Takeda, Masanobu Nakayama, Masayuki Karasuyama, Ryo Kobayashi
Science and Technology of Advanced Materials: Methods 3 ( 1 ) 2023.09
Language：English Publishing type：Research paper (scientific journal) Publisher：Informa UK Limited
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Increasing the Sodium Metal Electrode Compatibility with the Na<sub>3</sub>PS<sub>4</sub> Solid‐State Electrolyte through Heteroatom Substitution Reviewed
Lieven Bekaert, Suzuno Akatsuka, Naoto Tanibata, Frank De Proft, Annick Hubin, Mesfin Haile Mamme, Masanobu Nakayama
ChemSusChem 16 ( 20 ) 2023.08
Language：English Publishing type：Research paper (scientific journal) Publisher：Wiley
Abstract
Rechargeable batteries are essential to the global shift towards renewable energy sources and their storage. At present, improvements in their safety and sustainability are of great importance as part of global sustainable development goals. A major contender in this shift are rechargeable solid‐state sodium batteries, as a low‐cost, safe, and sustainable alternative to conventional lithium‐ion batteries. Recently, solid‐state electrolytes with a high ionic conductivity and low flammability have been developed. However, these still face challenges with the highly reactive sodium metal electrode. The study of these electrolyte‐electrode interfaces is challenging from a computational and experimental point of view, but recent advances in molecular dynamics neural‐network potentials are finally enabling access to these environments compared to more computationally expensive conventional ab‐initio techniques. In this study, heteroatom‐substituted Na<sub>3</sub>PS<sub>3</sub>X<sub>1</sub> analogues, where X is sulfur, oxygen, selenium, tellurium, nitrogen, chlorine, and fluorine, are investigated using total‐trajectory analysis and neural‐network molecular dynamics. It was found that inductive electron‐withdrawing and electron‐donating effects, alongside differences in heteroatom atomic radius, electronegativity, and valency, influenced the electrolyte reactivity. The Na<sub>3</sub>PS<sub>3</sub>O<sub>1</sub> oxygen analogue was found to have superior chemical stability against the sodium metal electrode, paving the way towards high‐performance, long lifetime and reliable rechargeable solid‐state sodium batteries. -
Assessing the Reactivity of the Na<sub>3</sub>PS<sub>4</sub> Solid-State Electrolyte with the Sodium Metal Negative Electrode Using Total Trajectory Analysis with Neural-Network Potential Molecular Dynamics Reviewed
Lieven Bekaert, Suzuno Akatsuka, Naoto Tanibata, Frank De Proft, Annick Hubin, Mesfin Haile Mamme, Masanobu Nakayama
The Journal of Physical Chemistry C 127 ( 18 ) 8503 - 8514 2023.05
Language：English Publishing type：Research paper (scientific journal) Publisher：American Chemical Society (ACS)
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Screening chloride Li-ion conductors using high-throughput force-field molecular dynamics Reviewed
Shin Aizu, Shuta Takimoto, Naoto Tanibata, Hayami Takeda, Masanobu Nakayama, Ryo Kobayashi
JOURNAL OF THE AMERICAN CERAMIC SOCIETY 106 ( 5 ) 3035 - 3044 2023.05
Authorship：Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：WILEY
The realization of high-energy-density all-solid-state Li-ion batteries requires materials exhibiting both high Li-ion conductivity and high deformability, as exemplified by Li3MCl6-type chlorides. Herein, we optimized the classical force-field (FF) parameters for 36 Li- and Cl-containing compounds to reproduce the results of high-precision first-principles calculations and performed rapid FF molecular dynamics (MD) calculations to determine their Li-ion conductivities. In addition, shear moduli were evaluated by first-principles calculations and used as a deformability index. Li4Mn3Cl10 was selected based on its Li-ion conductivity, stiffness, and thermodynamic stability. In accordance with the low calculated shear modulus (11.7 GPa), the cold-pressed compact had a high relative density of 98%, which indicated good deformability. The room-temperature conductivity (3.9 mS cm(-1)) was similar to that (1.6 mS cm(-1)) obtained by high-precision first-principles MD calculations. The Li-ion conductivity of synthesized Li4Mn3Cl10 (18 mu S cm(-1)) was relatively rather high compared to those of known chloride materials but much lower than the calculated value, which was ascribed to the fact that calculations were performed for the high-temperature phase, whereas synthesis yielded the low-temperature phase. The material screening method greatly increases the speed of material exploration and expands the application possibilities of chloride materials for all-solid-state batteries.
DOI： 10.1111/jace.18991
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Reaction Kinetics of Carbonation at the Surface of Garnet-Type Li<sub>7</sub>La<sub>3</sub>Zr<sub>2</sub>O<sub>12</sub> as Solid Electrolytes for All-Solid-State Li Ion Batteries Reviewed
Masanobu Nakayama, Takuya Horie, Ryosuke Natsume, Shogo Hashimura, Naoto Tanibata, Hayami Takeda, Hirotaka Maeda, Masashi Kotobuki
The Journal of Physical Chemistry C 127 ( 16 ) 7595 - 7601 2023.04
Language：English Publishing type：Research paper (scientific journal) Publisher：American Chemical Society (ACS)
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Computational studies on defect chemistry and Li-ion conductivity of spinel-type LiAl5O8 as coating material for Li-metal electrode. Reviewed International journal
Shuntaro Miyakawa, Shogo Matsuda, Naoto Tanibata, Hayami Takeda, Masanobu Nakayama, Takaya Saito, Svetlana Fukuchi
Scientific reports 12 ( 1 ) 16672 - 16672 2022.10
Language：English Publishing type：Research paper (scientific journal)
Li-metal rechargeable batteries are an attractive option for devices that require an extremely high specific energy density, high robustness, and long-term durability, such as high-altitude platform stations. However, Li dendrite growth during charge-discharge cycling causes short-circuit problems. One technical solution is to form an intermediate layer between the Li metal and electrolyte. This interfacial layer should possess mechanical strength, electrochemical stability in the presence of Li, and Li-ion conductivity. In this study, the Li-ion conductivity of spinel-type LiAl5O8 was investigated using first-principles density functional theory and force field molecular dynamics calculations. The calculation results confirmed that stoichiometric LiAl5O8 compounds do not exhibit Li-ion conductivity, whereas off-stoichiometric compounds with excess Li show long-range Li-ion diffusion. The evaluated activation energy was 0.28 eV, which is as low as that of well-known fast Li-ion conductors, such as garnet-type Li7La3Zr2O12. However, the extrapolated Li-ion conductivity at 298 K was relatively low (~ 10-6 S/cm) owing to the limited formation of migration pathways.
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Process optimisation for NASICON-type solid electrolyte synthesis using a combination of experiments and bayesian optimisation Reviewed
Hayami Takeda, Hiroko Fukuda, Koki Nakano, Syogo Hashimura, Naoto Tanibata, Masanobu Nakayama, Yasuharu Ono, Takaaki Natori
MATERIALS ADVANCES 2022.10
Language：English Publishing type：Research paper (scientific journal) Publisher：ROYAL SOC CHEMISTRY
Na superionic conductor (NASICON)-type LiZr2(PO4)(3) (LZP) is an oxide-based solid electrolyte candidate for use in all-solid-state Li-ion batteries. However, as the ionic conductivity is insufficient, doping with aliovalent cations has been carried out to improve the Li-ion conductivity by controlling the composition and crystal structure. Li-ion conductivity is also affected by the microstructural properties of a sintered body, such as density, morphology, and elemental distribution, and thus, controlling process parameters, such as heating conditions during the solid-state reaction, improves conductivity. Using an exhaustive experimental approach, Ca and Si co-doped Li-rich NASICON-type LZP was synthesised via solid-state reactions under various two-step heating conditions to yield the highest Li-ion conductivity by optimising the conditions. The highest total Li-ion conductivity of 3.3 x 10(-5) S cm(-1) was obtained when the sample was first heated at 1050 degrees C and then heated at 1250 degrees C. The crystal structures, relative densities, micromorphologies, and Li-ion conductivities of the materials were characterised, and their relationships were investigated. These relationships were complex, and intuitively determining the optimal conditions was challenging with only a few experiments. Instead, as a proof-of-concept study, the collected data were used to demonstrate that Bayesian optimisation (BO) efficiently improved the experimental determination of the optimal heating conditions. The BO-guided experimental investigation determined the optimal conditions more rapidly compared to conventional trial-and-error approaches employed in the materials industry. The efficiency factor was approximately double that of the exhaustive search.
DOI： 10.1039/d2ma00731b
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Bayesian optimisation with transfer learning for NASICON-type solid electrolytes for all-solid-state Li-metal batteries Reviewed
Hiroko Fukuda, Shunya Kusakawa, Koki Nakano, Naoto Tanibata, Hayami Takeda, Masanobu Nakayama, Masayuki Karasuyama, Ichiro Takeuchi, Takaaki Natori, Yasuharu Ono
RSC Advances 12 ( 47 ) 30696 - 30703 2022.10
Language：English Publishing type：Research paper (scientific journal) Publisher：Royal Society of Chemistry (RSC)
Demonstrate BO approaches to search for optimal composition with high ionic conductivity efficiently.
DOI： 10.1039/D2RA04539G
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Growth Mechanism of Spiky Nb2O5 Nanoparticles and their Electrochemical Property Reviewed
Teruaki Fuchigami, Hayato Yamamoto, Naoto Tanibata, Masanobu Nakayama, Ken-ichi Kakimoto
PHYSICA STATUS SOLIDI B-BASIC SOLID STATE PHYSICS 259 ( 9 ) 2022.09
Language：English Publishing type：Research paper (scientific journal) Publisher：WILEY-V C H VERLAG GMBH
Spiky nanoarchitecture composed of numerous nanorods and a spherical core has applications in various fields because of its high performance and durability. However, controlling the spiky structure is challenging because of an unclear formation mechanism. This study investigates the growth mechanism of spiky nanostructure by hydrothermally synthesizing Nb2O5 with various conditions and additives, and it is shown that adsorption and gradual decomposition of ligands promote the formation of the spiky shape. Using oxalic acid as an additive and synthesizing at 160 degrees C, which is below oxalic acid's decomposition temperature, spherical Nb2O5 with a rough surface that consists of a nanostructure with less than 5 nm size forms, and its surface is protected by oxalate ions. When the synthesis temperature increases to 180 degrees C, oxalate ions are decomposed, and nanorods grow on the spherical particles. The results show that oxalate ions suppress particle growth, promote self-assembly, and control subsequent particle growth, resulting in complex nanostructures. When used as anode material in lithium-ion batteries, the spiky Nb2O5 nanoparticles show a higher capacity (143 mAh g(-1)) than collapsed spiky particles (92 mAh g(-1)) and nanorods (37 mAh g(-1)) because of fast lithium-ion diffusion on the surface nanostructure and high dispersibility.
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Na superionic conductor-type LiZr2(PO4)3 as a promising solid electrolyte for use in all-solid-state Li metal batteries Reviewed International journal
Masanobu Nakayama, Koki Nakano, Maho Harada, Naoto Tanibata, Hayami Takeda, Yusuke Noda, Ryo Kobayashi, Masayuki Karasuyama, Ichiro Takeuchi, Masashi Kotobuki
Chemical Communications 58 ( 67 ) 9328 - 9340 2022.08
Language：English Publishing type：Research paper (scientific journal)
All-solid-state Li-ion batteries are of considerable interest as safer alternatives to Li-ion batteries containing flammable organic electrolytes. To date, however, achieving sufficient charging and discharging rates, in addition to capacity, at room temperature using these all-solid-state batteries has been challenging. To overcome these issues, material simulations and informatics investigations of a relatively new Na superionic conductor (NASICON)-type LiZr2(PO4)3 (LZP) electrolyte were conducted to elucidate its characteristics and material functions. The following thermodynamic and/or kinetic properties of NASICON-type Li-ion conductive oxides were investigated with respect to the crystal structure mainly using material simulation and informatics approaches: (1) the electrochemical stabilities of LZP materials with respect to Li metal and (2) Li-ion conductivities in the bulk and at the grain boundaries. An efficient materials informatics search method was employed to optimise the material functions of the LZP electrolyte via Bayesian optimisation. This study should promote the application of LZP in all-solid-state batteries for use in technologies such as mobile devices and electric vehicles and enable more complex composition and process control.
DOI： 10.1039/D2CC01526A
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Chemical Composition Data-Driven Machine-Learning Prediction for Phase Stability and Materials Properties of Inorganic Crystalline Solids Reviewed
Taruto Atsumi, Kosei Sato, Yudai Yamaguchi, Masato Hamaie, Risa Yasuda, Naoto Tanibata, Hayami Takeda, Masanobu Nakayama, Masayuki Karasuyama, Ichiro Takeuchi
PHYSICA STATUS SOLIDI B-BASIC SOLID STATE PHYSICS 2022.02
Language：English Publishing type：Research paper (scientific journal) Publisher：WILEY-V C H VERLAG GMBH
Materials informatics has attracted significant attention toward the efficient discovery and development of new functional materials. Machine-learning regression techniques have often been used to establish a link between properties. In this respect, precise and rational regression is contingent on the choice of descriptors used to represent both composition and structural information. The usage of structure-derived descriptors restricts the prediction range to the registered materials in the crystal structure database owing to the structural information requirements. Conversely, machine-learning regression based only on compositional descriptors is free from this restriction, despite the fact that the prediction performance may diminish. Herein, their prediction performance is improved using compositional descriptors with histograms, and detailed surveys are performed on their ability to extrapolate. The proposed model achieves a high prediction accuracy based on the area under the receiver operating characteristic (ROC) curve (specifically, AUC > 0.9).
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Octahedral Tilting and Modulation Structure in Perovskite‐Related Compound La 1/3 NbO 3 Reviewed
Yusuke Sakai, Daisuke Urushihara, Toru Asaka, Koichiro Fukuda, Zijian Yang, Naoto Tanibata, Hayami Takeda, Masanobu Nakayama
physica status solidi (b) 259 ( 9 ) 2022.01
Language：English Publishing type：Research paper (scientific journal) Publisher：Wiley
The crystal structure of the A-site-deficient perovskite La1/3NbO3 is investigated using X-ray powder diffraction, transmission electron microscopy (TEM), and computational methods. The NbO6 octahedral tilting is observed and confirmed to be in an a (-) b (0) c (0) manner in Glazer's notation. An incommensurate modulation structure in La1/3NbO3 is observed. Using scanning TEM (STEM) analyses and Monte Carlo simulations, the modulated structure is shown to originate from a striped arrangement of La and vacancies. The satellite reflections arising from the modulation structure are observed as a diffuse scatter in the electron diffraction patterns. By analyses with STEM and molecular dynamics calculations, it is concluded that the origin of diffuse scattering is the existence of nanoscale twin variants with different crystal orientations. The Nb ions in NbO6 octahedra represent an off-center shift like a pseudo-Jahn-Teller distortion. The shift of Nb ions is found to be cooperative with the concentration modulation of La ions.
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Density Functional Theory Studies on Li Metal Electrode/Garnet-Type Li7La3Zr2O12 Solid Electrolyte Interfaces for Application in All-Solid-State Batteries Reviewed
Ripon Iwasaki, Kunihiro Ishida, Risa Yasuda, Koki Nakano, Naoto Tanibata, Hayami Takeda, Masanobu Nakayama, Naoki Watanabe
PHYSICA STATUS SOLIDI B-BASIC SOLID STATE PHYSICS 2022.01
Language：English Publishing type：Research paper (scientific journal) Publisher：WILEY-V C H VERLAG GMBH
Garnet-type Li7La3Zr2O12 (LLZ) and its analogs are considered potential candidates as solid electrolytes for all-solid-state Li metal batteries because their fast Li-ion conductivity and chemical stability against Li metal anodes result in both safe and large energy densities. To date, several computational and experimental studies have been performed to obtain a more detailed understanding of the nonreactivity of garnet-type LLZ with Li metal and related phenomena. Herein, first-principles calculations based on the density functional theory approach are performed for Li metal/LLZ interfaces to elucidate the electronic and atomistic level aspects. It is confirmed that the valence band maximum and the conduction band minimum for the LLZ phase do not cross the Fermi level corresponding to the Li 2s band. In addition, it is found that the defect formation energies associated with both Li vacancy formation and interstitial Li formation are largely reduced. In particular, the formation energy associated with interstitial Li sites, i.e., Li+ insertion into the LLZ phase, is negative, indicating that spontaneous Li insertion is likely to proceed in the vicinity of the Li/LLZ interface. This new suggestion may help further elucidation of the reported interfacial behavior.
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Density Functional Theory and Machine Learning-Based Analyses for Improved Surface Stability of a BaTiO3-Coated LiCoO2 Positive Electrode Material Reviewed
Kunihiro Ishida, Naoto Tanibata, Hayami Takeda, Masanobu Nakayama, Takashi Teranishi, Naoki Watanabe
PHYSICA STATUS SOLIDI B-BASIC SOLID STATE PHYSICS 259 ( 9 ) 2021.12
Language：English Publishing type：Research paper (scientific journal) Publisher：WILEY-V C H VERLAG GMBH
The application of oxide coating on the surfaces of active cathode materials is an effective method for improving the electrochemical durability of lithium-ion batteries because it suppresses oxygen gas release from the surface of the cathode material. This report summarizes a study conducted on verifying the suppression of oxygen release from a LiCoO2 cathode material using BaTiO3 (BT), which has recently attracted attention as a new coating material. The use of first-principles calculations and machine learning as verification methods is described. In addition to the discussion of interfacial properties based on atomic- and electronic-level considerations, comprehensive verification of the interface with several junction patterns is described. The verification results suggest that the desorption of oxygen from the surface of the active material is hindered by the oxide coating, indicating the effectiveness of BT as a coating material.
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Molecular Dynamics Simulation of Li-Ion Conduction at Grain Boundaries in NASICON-Type LiZr2(PO4)3 Solid Electrolytes Reviewed
Koki Nakano, Naoto Tanibata, Hayami Takeda, Ryo Kobayashi, Masanobu Nakayama, Naoki Watanabe
The Journal of Physical Chemistry C 125 ( 43 ) 23604 - 23612 2021.11
Language：English Publishing type：Research paper (scientific journal) Publisher：American Chemical Society (ACS)
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Exploring the diffusion mechanism of Li ions in different modulated arrangements of La(1-X)/3LixNbO3 with fitted force fields obtained via a metaheuristic algorithm
Zijian Yang, Robyn E. Ward, Naoto Tanibata, Hayami Takeda, Masanobu Nakayama, Ryo Kobayashi
SOLID STATE IONICS 366 2021.08
Language：English Publishing type：Research paper (scientific journal) Publisher：ELSEVIER
As a potential solid-state electrolyte material, Li-containing A-site deficient perovskite oxides have attracted the attention of researchers because of their high Li-ion conductivity and the relationship between Li-ion conduction and structural characteristics, which has been intensively investigated. We have recently confirmed a quasiperiodic ordered arrangement of La and vacancies (Vac) at the perovskite A-sites of La(1-X)/3LixNbO3 (LLNO) using a combination of density functional theory (DFT), Monte Carlo simulations, and electron diffraction. Interestingly, two types of modulated arrangements, namely closed and striped structures, coexist in the La-rich layer, which affect Li-ion migration. In this study, DFT-derived force-field molecular dynamics (FFMD) simulations were performed to investigate the effect of a modulated structure on the migration behavior of Li ions in LLNO compounds. The results indicate that the type of modulated arrangements of La/Vac has a significant influence on the migration of Li ions. Moreover, the estimated diffusion coefficients of the modulated structures are higher by a factor of 10 than those of La/Vac disordered models at 800 K. The migration energy in the ab plane appeared to be much lower than along the c-axis, controlling the modulated arrangement of LLNO is beneficial to eliminate La-ion blockage during long-distance migration. Accordingly, the present study reveals that the controlling cation/Vac arrangement at perovskite A-sites is crucial for achieving high Li-ion conductivity. At the same time, the research scheme of this work is also applicable to other solid electrolyte materials, which provides research guidance for high-throughput material retrieval.
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First-principles study of the morphology and surface structure of LaCoO3 and La0.5Sr0.5Fe0.5Co0.5O3 perovskites as air electrodes for solid oxide fuel cells Reviewed
Masanobu Nakayama, Katsuya Nishii, Kentaro Watanabe, Naoto Tanibata, Hayami Takeda, Takanori Itoh, Toru Asaka
Science and Technology of Advanced Materials 1 ( 1 ) 24 - 33 2021.03
Language：English Publishing type：Research paper (scientific journal) Publisher：Informa UK Limited
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Efficient Experimental Search for Discovering a Fast Li-Ion Conductor from a Perovskite-Type LixLa(1-x)/3NbO3 (LLNO) Solid-State Electrolyte Using Bayesian Optimization
Zijian Yang, Shinya Suzuki, Naoto Tanibata, Hayami Takeda, Masanobu Nakayama, Masayuki Karasuyama, Ichiro Takeuchi
JOURNAL OF PHYSICAL CHEMISTRY C 125 ( 1 ) 152 - 160 2021.01
Language：English Publishing type：Research paper (scientific journal) Publisher：AMER CHEMICAL SOC
LixLa(l -x)/3NbO3 (LLNO) is an A-site-deficient perovskite material that has a larger unit cell volume, a lower La3+ concentration, and a higher intrinsic vacancy concentration than (LixLa(2-x)/3TiO3), which is known to be one of the fastest Li-ion conductive oxides. These advantages make LLNO a potential oxide-based solid electrolyte candidate for allsolid-state Li-ion batteries. The A-site and B-site elements in this perovskite-type material can be substituted by ions with various charges and radii in a wide range of ways to form complicated solid solutions; hence, this type of material can be adapted to a variety of application requirements. Doping with monovalent or divalent metal compounds is a promising method for improving the ionic conductance of this perovskite-type material. In this study, the (LiyLa(1-y/3)(1-x)Sr0.5xNbO3 (0 <= 0.5 x <= 0.15, 0 <= y <= 0.3) composition formed by co-doping with Li2CO3 and SrCO3 was optimized using an exhaustive experimental approach. Sixty-four samples with different compositions were structurally analyzed, and their electrochemical performance was experimentally characterized, which revealed that the co-doped samples have higher ionic conductivities and superior sintered morphologies compared to those prepared by single doping. Because Li+ and Sr2+ doping improves the ionic conductivity for different reasons, and many factors, such as higher carrier concentrations, enhancements through sintering, and changes in the microstructure, play important roles, it is difficult or inefficient to determine the best composition using only traditional trial-and-error or intuitive searching. Instead, as a proof-of-concept study, we show that the Bayesian optimization (BO) method efficiently searches for the best composition and that material retrieval during experimental exploration can benefit from BO because it significantly reduces the high workload associated with the trial-and-error approach employed by the materials industry.
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High Formability and Fast Lithium Diffusivity in Metastable Spinel Chloride for Rechargeable All‐Solid‐State Lithium‐Ion Batteries Reviewed
Naoto Tanibata, Masashi Kato, Shuta Takimoto, Hayami Takeda, Masanobu Nakayama, Hirofumi Sumi
Advanced Energy and Sustainability Research 1 ( 1 ) 2000025 - 2000025 2020.10
Authorship：Lead author Language：English Publishing type：Research paper (scientific journal) Publisher：Wiley
Materials with high formability and Li-ion diffusivity are desired to realize safe bulk-type all-solid-state Li-ion batteries with high energy density. Spinel-type Li2FeCl4, which is expected as a Li-ion-conductive electrode, adopts the high-temperature cubic phase (space group: Fd-3m) by a mechanochemical synthesis method. The powder-compressed pellet shows a high relative density of 92% and large neck formation between the particles. An analysis of the distribution of relaxation times from the AC impedance results indicates that the contribution of the grain boundary impedance is almost negligible (≈3%) in the powder-compressed pellet. Even the Li diffusion coefficient, which is underestimated by the Nernst–Einstein equation, is several orders of magnitude higher than those of conventional oxide and sulfide electrode materials. Analyzing the diffusion pathways using a classical force field calculation suggests that stabilizing the high-temperature phase at room temperature delocalizes Li ions in the diffusion pathway, thus realizing high Li-ion diffusivity. The Li2FeCl4 green compact containing 10 wt% carbon as an electron-conductive additive shows a one-electron charge reaction with a capacity of 126 mAh g−1, with no large overpotential at a high operating voltage of 3.6 V versus Li/Li+ at 30 °C.
Other Link： https://onlinelibrary.wiley.com/doi/full-xml/10.1002/aesr.202000025
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Bayesian-optimization-guided experimental search of NASICON-type solid electrolytes for all-solid-state Li-ion batteries Reviewed
Maho Harada, Hayami Takeda, Shinya Suzuki, Koki Nakano, Naoto Tanibata, Masanobu Nakayama, Masayuki Karasuyama, Ichiro Takeuchi
JOURNAL OF MATERIALS CHEMISTRY A 8 ( 30 ) 15103 - 15109 2020.08
Language：English Publishing type：Research paper (scientific journal) Publisher：ROYAL SOC CHEMISTRY
Divalent- or trivalent-metal-oxide-doped NASICON-type LiZr2(PO4)(3)(LZP) is an attractive oxide-based solid electrolyte for all-solid-state Li-ion batteries owing to its high Li-ion conductivity and stable charge-discharge cycling. Using an extensive experimental approach, the composition of CaO- and Y2O3-co-doped Li-rich NASICON-type LZP of the composition Li(1+x+2y)Z(r2-x-y)Y(x)Ca(y)(PO4)(3)(0 <= x <= 0.376, 0 <= y <= 0.376) was optimized. A number of 49 compositions were synthesized and their crystal structures, relative density of the sintered material, and Li-ion conductivity characterized. The co-doped compositions had a higher Li-ion conductivity than those doped with CaO or Y(2)O(3)alone. Furthermore, diffraction studies revealed that two phases and an impurity phase existed depending on the composition. Adding CaO significantly changed the relative density of the sintered material. Thus, to identify compositional dependencies among the Li-ion conductivity, phase stability, and relative density was complicated, and intuitively searching for the best composition was difficult. As a proof-of-concept, the collected data were used to demonstrate that the Bayesian optimization (BO) significantly improved the experimental search for the best oxide-based electrolyte composition. Multi-objective BO (MOBO), which considers more than two target performances, was also carried out. It was validated that the BO-guided experimental search determined more rapidly the best composition compared to conventional trial-and-error approaches employed in the materials industry.
DOI： 10.1039/d0ta04441e
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Arrangement in La1/3NbO3 Obtained by First-Principles Density Functional Theory with Cluster Expansion and Monte Carlo Simulation Reviewed
Zijian Yang, Robyn E. Ward, Naoto Tanibata, Hayami Takeda, Masanobu Nakayama, Toru Asaka
JOURNAL OF PHYSICAL CHEMISTRY C 124 ( 18 ) 9746 - 9754 2020.05
Language：English Publishing type：Research paper (scientific journal) Publisher：AMER CHEMICAL SOC
LixLa(1-x)/3NbO3 is an A-site-deficient perovskite material that exhibits structure-dependent ionic conductivity. La1/3NbO3 has a larger unit cell volume, lower concentration of La3+ ions, and higher concentration of intrinsic vacancies than La2/3TiO3. As such, it should exhibit higher Li ion conductivity and, therefore, be a good candidate for all ceramic Li secondary batteries or fast Li ion transport solid-state electrolyte batteries. However, experimental observations show otherwise. Information on the local atomic arrangements would facilitate the analysis of the gap between the theoretical and experimental results. Ab initio density functional theory calculations are useful for calculating the atomic arrangements and energies. However, because of cell size limitations, long-range ordering in La/Li/vacancy arrangements cannot be observed using ab initio calculations. In this study, cluster expansion and Monte Carlo simulations were utilized to bridge this gap. The computational results reproduce the stacking of alternate La-rich and La-poor layers along the c-axis, consistent with the experimental data. In addition, two possible modulated structures for the La-rich layers were discovered. These should help explain the lower-than-expected ionic conductivity and the possible Li ion migration pathways in the material. Based on the presented Monte Carlo simulations, we conclude that the two types of low-energy structures, the closed and striped arrangements, may coexist in the real system. The modulated structures in experimental studies are likely to be numberless nanodomains composed of these two arrangements. If the majority of the structure shows a closed arrangement at room temperature, most of the Li ions will be trapped at the center of the periodic units in the closed arrangement. This could explain the lower-than-expected Li ion conductivity in LixLa(1-x)/3NbO3.
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Exhaustive and informatics-aided search for fast Li-ion conductor with NASICON-type structure using material simulation and Bayesian optimization Reviewed
Koki Nakano, Yusuke Noda, Naoto Tanibata, Hayami Takeda, Masanobu Nakayama, Ryo Kobayashi, Ichiro Takeuchi
APL MATERIALS 8 ( 4 ) 2020.04
Language：English Publishing type：Research paper (scientific journal) Publisher：AMER INST PHYSICS
Currently, NASICON-type LiZr2(PO4)(3) (LZP)-related materials are attracting attention as solid electrolytes. There are experimental reports that Li-ion conductivity can be improved by doping a small amount of Ca or Y into stoichiometric LZP. In previous studies, doping with only one element having a narrow search space has been attempted, and thus, further improvement of the Li-ion conductivity is conceivable by using multi-element doping. When multi-element doping is attempted, because the search space becomes enormous, it is necessary to evaluate the Li-ion conductivity using a low-cost method. Here, force-field molecular dynamics using a bond valence force field (BVFF) approach was performed to evaluate the Li-ion conductivity. We confirmed that the Li-ion conductivity of stoichiometric LZP derived from BVFF (6.2 x 10(-6) S/cm) has good agreement with the first principle calculation result (5.0 x 10(-6) S/cm). Our results suggest that the Li-ion conductivity can be further improved by simultaneously doping LZP with Ca and Y [6.1 x 10(-5) S/cm, Li35/32Ca1/32Y1/32Zr31/16(PO4)(3)]. In addition, Bayesian optimization, which is an informatics approach, was performed using exhaustively computed conduction property datasets in order to validate efficient materials search. The averages for Bayesian optimization over 1000 trials show that the optimal composition can be found about seven times faster than by random search.
DOI： 10.1063/5.0007414
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First-Principles Density Functional Theory Calculations for Formic Acid Adsorption onto Hydro-Garnet Compounds Reviewed International journal
Masanobu Nakayama, Kunihiro Ishida, Kentaro Watanabe, Naoto Tanibata, Hayami Takeda, Hirotaka Maeda, Toshihiro Kasuga
ACS OMEGA 5 ( 8 ) 4083 - 4089 2020.03
Language：English Publishing type：Research paper (scientific journal) Publisher：AMER CHEMICAL SOC
Efficient and large-scale removal of humic acid (HA) from aqueous environments is required since HA causes human health and esthetic issues. Hydrogarnet compounds, Ca3Al2(SiO4)(3-x)(OH)(4x), have recently been suggested as HA adsorbents not only due to their superior adsorption behaviors but also because they are ubiquitous element-derived compounds. In this study, the adsorption behavior of formic acid to hydro-garnets was investigated by means of first-principles density functional theory (DFT) computations. Formic acid was chosen owing to its reasonable computational cost and inclusion of carboxylic acid as HA. Comparisons of adsorption energies for formic acid among various compounds (including platinum and kaolinite) indicate that hydro-garnet compounds are promising due to their lower more stable) adsorption energies. Also, the optimization of composition x enables selective adsorption of formic acid against solvent water molecules. Relationships between surface electronic/atomistic structures and adsorption properties are discussed.
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Asymmetry in the Solvation-Desolvation Resistance for Li Metal Batteries Reviewed International journal
Naoto Tanibata, Riku Morimoto, Kei Nishikawa, Hayami Takeda, Masanobu Nakayama
ANALYTICAL CHEMISTRY 92 ( 5 ) 3499 - 3502 2020.03
Authorship：Lead author, Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：AMER CHEMICAL SOC
Li metal electrode is the ultimate choice use in Li ion batteries as high-energy storage systems. An obstacle to its practical realization is Li dendrite formation. In this study, the desolvation resistance of the Li metal electrode, which is strongly related to the inhibition of Li dendrite formation, is investigated. By applying a Laplace transform impedance technique, the desolvation/solvation resistances were successfully separated and analyzed in cells using liquid electrolytes containing different lithium salts, revealing asymmetry in the desolvation/solvation resistances of Li metal electrodes. The desolvation resistances, which supposedly require large amounts of energy derived from the strong interaction between Li+ ion and solvents, were smaller than the solvation resistances. It has also been revealed that the larger resistance in the desolvation process is effective for suppressing Li dendrite formation further.
File： Manuscript File.pdf
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Novel Mg-ion conductive oxide of mu-cordierite Mg0.6Al1.2Si1.8O6 Reviewed International journal
Hayami Takeda, Koki Nakano, Naoto Tanibata, Masanobu Nakayama
SCIENCE AND TECHNOLOGY OF ADVANCED MATERIALS 21 ( 1 ) 131 - 138 2020.01
Language：English Publishing type：Research paper (scientific journal) Publisher：TAYLOR & FRANCIS LTD
Solid electrolytes with high Mg-ion conductivity are required to develop solid-state Mg-ion batteries. The migration energies of the Mg2+ ions of 5,576 Mg compounds tabulated from the inorganic crystal structure database (ICSD) were evaluated via high-throughput calculations. Among the computational results, we focused on the Mg2+ ion diffusion in Mg0.6Al1.2 Si1.8O6, as this material showed a relatively low migration energy for Mg2+ and was composed solely of ubiquitous elements. Furthermore, first-principles molecular dynamics calculations confirmed a single-phase Mg2+ ion conductor. The bulk material with a single Mg0.6Al1.2Si1.8O6 phase was successfully prepared using the sol-gel method. The relative density of the sample was 81%. AC impedance measurements indicated an electrical conductivity of 1.6 x 10(-6) Scm(-1) at 500 degrees C. The activation energy was 1.32 eV, which is comparable to that of monoclinic-type Mg0.5Zr2(PO4)(3).
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Computational investigation of the Mg-ion conductivity and phase stability of MgZr4(PO4)6 Reviewed International journal
K Nakano, Y Noda, N Tanibata, M Nakayama, K Kajihara, K Kanamura
RSC advances 9 ( 22 ) 12590 - 12595 2019.04
Language：English Publishing type：Research paper (scientific journal) Publisher：ROYAL SOC CHEMISTRY
Solid electrolyte materials exhibiting high Mg-ion conductivity are required to develop Mg-ion batteries. In this study, we focused on a Mg-ion-conducting solid phosphate based electrolyte, MgZr4(PO4)(6) (MZP), and evaluated the ionic conductivity of NASICON-type and -iron sulfate-type MgZr4(PO4)(6) structures via density functional theory calculations. The calculations suggest that the migration energy of Mg is 0.63 eV for the NASICON-type structure and 0.71 eV for the -iron sulfate-type one, and the NASICON-type structure has higher ion conductivity. Although the NASICON-type MZP structure has not been experimentally realised, there is only an energy difference of 14 meV per atom with respect to that of the -iron sulfate-type structure. Therefore, in order to develop a synthesis method for the NASICON-type structure, we investigated pressure- and temperature-dependent variations in the free energy of formation using density functional perturbation theory calculations. The results suggest that the formation of the NASICON-type structure is disfavoured under the 0-2000 K and 0-20 GPa conditions.
DOI： 10.1039/c9ra00513g
Other Link： https://pubs.rsc.org/en/content/articlehtml/2019/ra/c9ra00513g
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第一原理計算によるMgイオン伝導体MgZr4(PO4)6のイオン伝導度および相安定性評価
中野高毅, 野田祐輔, 谷端直人, 谷端直人, 中山将伸, 中山将伸, 中山将伸, 梶原浩一, 金村聖志
化学電池材料研究会ミーティング講演要旨集 21st 2019
Publishing type：Research paper (scientific journal)
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Preparation of Sodium Ion Conductive Na10GeP2S12 Glass-ceramic Electrolytes Reviewed International journal
Fumika Tsuji, Naoto Tanibata, Atsushi Sakuda, Akitoshi Hayashi, Masahiro Tatsumisago
Chemistry Letters 47 ( 1 ) 13 - 15 2018.10
Language：English Publishing type：Research paper (scientific journal) Publisher：CHEMICAL SOC JAPAN
Na10GeP2S12 glass and glass-ceramic were synthesized here for the first time via mechanical milling and subsequent heat treatment. The Na10GeP2S12 phase prepared in this study had a similar crystal structure to the Na10SnP2S12 phase reported previously. The ionic conductivity at room temperature and the activation energy of the Na10GeP2S12 glass-ceramic were 1.2 x 10(-5) Scm(-1) and 44 kJ mol(-1), respectively.
DOI： 10.1246/cl.170836
Other Link： http://www.journal.csj.jp/doi/10.1246/cl.170836
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Preparation and characterization of Na3PS4–Na4GeS4 glass and glass-ceramic electrolytes Reviewed International journal
Naoto Tanibata, Kousuke Noi, Akitoshi Hayashi, Masahiro Tatsumisago
Solid State Ionics 320 193 - 198 2018.03
Authorship：Lead author Language：English Publishing type：Research paper (scientific journal) Publisher：Elsevier B.V.
Li4GeS4-substituted Li3PS4 crystals have high Li+ ion conductivities comparable to that of commercial organic electrolytes [Kamaya et al., Nat. Mater. 10 (2011) 682]. In this study, (100 − x)Na3PS4·xNa4GeS4 glasses and glass-ceramics were prepared for novel Na+ ion conductors. These glasses, which have the highest Na content reported to date in the Na–P–Ge–S system, were prepared by a mechanical milling technique. These glasses are composed of PS4 3− and GeS4 4−. The crystallization temperatures gradually increased with increasing Na4GeS4 content. The glasses showed higher conductivities of ~10−5 S cm−1 than the Na–P–Ge–S glasses reported so far. The glass–ceramics with the compositions x = 50 and 75, where the crystal predicted by first principles calculations to have high conductivities exceeding 10−3 S cm−1 was precipitated, exhibited Na+ ion conductivities of ~10−5 S cm−1 at room temperature.
File： Manu..pdf
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材料シミュレーションによるNASICON型Liイオン伝導体の相安定性と導電性評価
中野高毅, 大竹将成, 宮路康裕, 谷端直人, 小林亮, 小林亮, 野田祐輔, 武田はやみ, 武田はやみ, 中山将伸, 中山将伸, 中山将伸
日本セラミックス協会秋季シンポジウム講演予稿集(CD-ROM) 31st 2018
Publishing type：Research paper (scientific journal)
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Crystal Structure and Sodium Disorder of High-temperature Polymorph β-Na3PS4 Reviewed International journal
Shin-ichi Nishimura, Naoto Tanibata, Akitoshi Hayashi, Masahiro Tatsumisago and Atsuo Yamada
Journal of Materials Chemistry A 5 ( 47 ) 25025 - 25030 2017.11
Language：English Publishing type：Research paper (scientific journal) Publisher：ROYAL SOC CHEMISTRY
Solid sodium conductors are of great interest as electrolytes for all-solid sodium batteries and also for sodium-sulphur batteries. Here we provide the dynamic structures of crystalline Na3PS4 by high-temperature powder X-ray diffraction (XRD) and molecular dynamics (MD) simulations. At room temperature, Na3PS4 adopts a tetragonal structure: alpha-Na3PS4. [Jansen and Henseler, J. Solid State Chem., 1992, 99(1), 110] alpha-Na3PS4 transforms to a cubic superionic phase beta-Na3PS4 at ca. 530 K, but its detailed structure has not been solved so far. The overall structure of beta-Na3PS4 is understood as Tl3VS4-type with characteristic spreading of Na distribution, reflecting the dynamic motion of Na. The a to beta structural transition involves expansion of bottlenecks of Na migration especially along the tetragonal c axis, and enables three-dimensional ionic transport.
DOI： 10.1039/c7ta08391b
Other Link： http://pubs.rsc.org/en/Content/ArticleLanding/2017/TA/C7TA08391B#!divAbstract
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Liquid-phase sintering of highly Na+ ion conducting Na3Zr2Si2PO12 ceramics using Na3BO3 additive Reviewed International journal
Kousuke Noi, Kenji Suzuki, Naoto Tanibata, Akitoshi Hayashi, Masahiro Tatsumisago
Journal of the American Ceramic Society 101 ( 3 ) 1 - 11 2017.10
Language：English Publishing type：Research paper (scientific journal) Publisher：Blackwell Publishing Inc.
Na3Zr2Si2PO12 (NASICON) is a promising material as a solid electrolyte for all-solid-state sodium batteries. Nevertheless, one challenge for the application of NASICON in batteries is their high sintering temperature above 1200°C, which can lead to volatilization of light elements and undesirable side reactions with electrode materials at such high temperatures. In this study, liquid-phase sintering of NASICON with a Na3BO3 (NBO) additive was performed for the first time to lower the NASICON sintering temperature. A dense NASICON-based ceramic was successfully obtained by sintering at 900°C with 4.8 wt% NBO. This liquid-phase sintered NASICON ceramic exhibited high total conductivity of ~1 × 10−3 S cm−1 at room temperature and low conduction activation energy of 28 kJ mol−1. Since the room-temperature conductivity is identical to that of conventional high-temperature-sintered NASICON, NBO was demonstrated as a good liquid-phase sintering additive for NASICON solid electrolyte. In the NASICON with 4.8 wt% NBO ceramic, most of the NASICON grains directly bonded with each other and some submicron sodium borates segregated in particulate form without full penetration to NASICON grain boundaries. This characteristic composite microstructure contributed to the high conductivity of the liquid-phase sintered NASICON.
DOI： 10.1111/jace.15288
Other Link： http://onlinelibrary.wiley.com/doi/10.1111/jace.15288/abstract
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Characterization of sulfur nanocomposite electrodes containing phosphorus sulfide for high-capacity all-solid-state Na/S batteries Reviewed International journal
Naoto Tanibata, Hirofumi Tsukasaki, Minako Deguchi, Shigeo Mori, Akitoshi Hayashi, Masahiro Tatsumisago
Solid State Ionics 311 ( 15 ) 6 - 13 2017.08
Authorship：Lead author Language：English Publishing type：Research paper (scientific journal) Publisher：ELSEVIER SCIENCE BV
All-solid-state Na/S cells with high safety, capacity, and low material costs are desirable for smart grid systems. We report sulfur composite electrodes prepared by the mechanical milling of sulfur, Ketjen black, and P2S5 or Na3PS4 for high-capacity cells. A cell using P2S5, which is not ion conductive, in the sulfur electrode exhibits a high reversible capacity of 340 mAh (g-sulfur electrode)(-1) at 0.04 C rate at 25 degrees C, which is much larger than that (37.3 mAh (g-sulfur electrode)(-1)) obtained in a conventional cell using a high ion-conductive Na3PS4 electrolyte. To investigate the reaction mechanism of the sulfur composite electrode containing P2S5, X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) measurements and scanning and transmission electron microscopy (SEM/TEM) observations of the electrodes were conducted. The results indicate that a crystalline Na3PS4 component is automatically produced by the electrochemical reaction with Na in the amorphous S-P2S5 electrode and it mixing with the sulfur redox parts at the nanoscale. The mixing degree is higher than that at microscale in the conventional S-Na3PS4 electrode, which results in the high capacity of the cells containing the S-P2S5 electrode. Partial substitution of P2S5 for SiS2 in the sulfur electrode suppresses the nanocrystallization and further increases the reversible capacity up to 390 mAh (g-sulfur electrode)(-1) under 0.04 C rate, which is the highest in reported all-solid-state Na batteries to date.
File： Manu..pdf
DOI： 10.1016/j.ssi.2017.08.022
Other Link： http://www.sciencedirect.com/science/article/pii/S0167273817303715
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All-Solid-State Na/S Batteries with a Na3PS4 Electrolyte Operating at Room Temperature Reviewed International journal
Naoto Tanibata, Minako Deguchi, Akitoshi Hayashi, Masahiro Tatsumisago
Chemistry of Materials 29 ( 12 ) 5232 - 5238 2017.06
Authorship：Lead author Language：English Publishing type：Research paper (scientific journal) Publisher：AMER CHEMICAL SOC
Bulk-type all-solid-state Na/S cells, which are expected to have high capacity, be highly safe, and have low material cost, were fabricated using a Na3PS4 glass-ceramic as a solid electrolyte. The sulfur composite electrodes were prepared by mechanical milling of sulfur active material, a conductive additive (acetylene black), and a Na3PS4 glass-ceramic electrolyte. The all solid -state Na/S cells used the reaction up to the final discharge product of sulfur active material, Na2S, and achieved a high capacity of similar to 1100 mAh (g of S)(-1) at room temperature. The rate of utilization of sulfur active material was similar to 2 times higher than that of high-temperature-operating NAS batteries (commercially available NAS batteries, Na/sintered beta ''-alumina/S), where Na2Sx melts with bridging sulfurs contribute to redox in the sulfur electrodes. The open circuit potential curve of the discharge process of the Na/S batteries operating at room temperature was similar to that of the NAS batteries operating at high temperatures; X-ray diffraction and Xray photoelectron spectroscopy measurement indicated that amorphous Na2Sx with a structure similar to the structure of these melts contributed to sulfur redox reaction in the all-solid-state Na/S cells. A galvanostatic intermittent titration technique and impedance measurement suggested that the overpotential during the discharge process in the all-solid-state Na/S cells was mainly derived from the sodium diffusion resistance in the solid sulfur active material. The finding would be an effective guide for achieving higher performance for all-solid-state Na/S cells.
File： Manu..pdf
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A novel discharge–charge mechanism of a S–P2S5 composite electrode without electrolytes in all-solid-state Li/S batteries Reviewed International journal
Naoto Tanibata, Hirofumi Tsukasaki, Minako Deguchi, Shigeo Mori, Akitoshi Hayashi, Masahiro Tatsumisago
Journal of Materials Chemistry A 5 ( 22 ) 11224 - 11228 2017.05
Authorship：Lead author Language：English Publishing type：Research paper (scientific journal) Publisher：Royal Society of Chemistry ({RSC})
All-solid-state Li/S cells with high safety and high capacity were fabricated using a sulfur composite electrode prepared by mechanically milling S, P2S5 and a conductive additive (Ketjen black). The cells with 50 wt% sulfur content in the composite electrode showed a high reversible capacity of 942 mA h (g-sulfur)(-1) at a constant current density of 0.64 mA cm(-2) (0.1C). The discharge-charge mechanism of the high-capacity sulfur composite electrode without electrolytes was investigated. XRD and NMR measurements showed that amorphous P2S5+x species, where sulfur chains bridged phosphorus atoms, were produced in the as-milled composite electrode. Mixing of the amorphous P2S5+x and Ketjen black in the submicron order was indicated from the FE-SEM observation and EDX mapping of the electrode. XRD and TEM measurements of the sulfur electrodes before and after the discharge-charge processes indicated that the compounds in the electrodes remained in the amorphous state during these processes. XPS measurement showed that cleavages and associations of the disulfide bonds occurred in the amorphous compounds during the discharge-charge processes. A novel discharge-charge mechanism with an atomic-level dispersion of a sulfur redox part in an ion conductive part was proposed for the high-capacity sulfur electrode.
File： Manu..pdf
DOI： 10.1039/C7TA01481C
Other Link： http://orcid.org/0000-0001-8521-9690
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Preparation and characterization of Na3BO3-Na2SO4 glass electrolytes with Na+ ion conductivity prepared by a mechanical milling technique Reviewed International journal
Kenji Suzuki, Yuta Nakamura, Naoto Tanibata, Akitoshi Hayashi, Masahiro Tatsumisago
Journal of the American Ceramic Society 4 ( 1 ) 6 - 10 2016.03
Language：English Publishing type：Research paper (scientific journal) Publisher：Elsevier B.V.
The (100 - x)Na3BO3·xNa2SO4 (0 ≤ x (mol%) ≤ 50) glasses were prepared by mechanical milling. Halo patterns were observed in the compositions 0 ≤ x ≤ 50 by XRD measurements. The Raman spectra indicated that all the glasses were composed of BO3 3- anions, SO4 2- anions and Na+ cations. The (100 - x)Na3BO3·xNa2SO4 glasses showed good deformation properties and a dense pellet was prepared by cold-press. The conductivities of the glasses increased with increasing Na2SO4 content, and the 50Na3BO3·50Na2SO4 glass showed the highest conductivity of 5.9 × 10-8 S cm-1 at 25 °C.
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All-solid-state sodium batteries using amorphous TiS3 electrode with high capacity Reviewed International journal
Naoto Tanibata, Takuya Matsuyama, Akitoshi Hayashi, Masahiro Tatsumisago
Journal of Power Sources 275 ( 1 ) 284 - 287 2015.02
Authorship：Lead author Language：English Publishing type：Research paper (scientific journal) Publisher：ELSEVIER SCIENCE BV
All-solid-state sodium cells (Na15Sn4/Na3PS4 glass-ceramic/a-TiS3) showed a high capacity of over 300 mAh per gram of TiS3 at the 1st dischargecharge cycle. The capacity was gradually decreased to 100 mAh g(-1) at the 10th cycle. Nyquist plots of the cell showed that the resistance of the alpha-TiS3 composite electrode became larger with the dischargecharge cycles. The XRD patterns of the alpha-TiS3 composite electrode before and after the 1st cycle indicated that the alpha-TiS3 was still amorphous during dischargecharge process. The Raman bands attributable to alpha-TiS3 were also observed after the 1st cycle. The SEM images and EDX mapping indicated that the alpha-TiS3 particles aggregated in the electrode after the 10th cycle. The all-solid-state sodium cell using alpha-TiS3 composite electrode with acetylene black as a conductive additive showed the high capacity of over 300 mAh g(-1) for 5 cycles. (C) 2014 Elsevier B.V. All rights reserved.
File： manuscript-141029fin.pdf
DOI： 10.1016/j.jpowsour.2014.10.193
Other Link： http://orcid.org/0000-0001-8521-9690
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Improvement of Rate Performance for All-Solid-State Na15Sn4/Amorphous TiS3 Cells Using 94Na3PS4-6Na4SiS4 Glass-Ceramic Electrolytes Reviewed International journal
Naoto Tanibata, Akitoshi Hayashi, Masahiro Tatsumisago
Journal of The Electrochemical Society 162 ( 6 ) 793 - 795 2015
Authorship：Lead author Language：English Publishing type：Research paper (scientific journal)
DOI： 10.1149/2.0011506jes
Other Link： http://orcid.org/0000-0001-8521-9690
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Preparation of sodium ion conducting Na3PS4-NaI glasses by a mechanochemical technique Reviewed International journal
Yoshiaki Hibi, Naoto Tanibata, Akitoshi Hayashi, Masahiro Tatsumisago
Solid State Ionics 270 6 - 9 2015
Language：English Publishing type：Research paper (scientific journal) Publisher：ELSEVIER SCIENCE BV
Structures and ionic conductivities of the (100 - x)Na3PS4 center dot xNaI(0 <= x (mol%) <= 33) glasses and glass-ceramics were investigated. In the XRD patterns, halo patterns were observed in the composition range of 0 <= x <= 29. The glass-ceramics were prepared by a heat treatment of the glasses. In the glass-ceramics with NaI, an unknown phase which has not been reported was mainly precipitated. The Raman spectra of the glasses and glass-ceramics indicated that all samples included the PS43- units. The conductivities of glasses increased with increasing the NaI content, and the 71Na(3)PS4 center dot 29NaI glass showed the highest conductivity of 1.4 x 10(-5) S cm(-1). The conductivities of the glass-ceramics at all composition were over 10(-4) S cm(-1). (C) 2014 Elsevier B.V. All rights reserved.
DOI： 10.1016/j.ssi.2014.11.024
Other Link： http://orcid.org/0000-0001-8521-9690
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High sodium ion conductivity of glass ceramic electrolytes with cubic Na3PS4 Reviewed International journal
Akitoshi Hayashi, Kousuke Noi, Naoto Tanibata, Motohiro Nagao, Masahiro Tatsumisago
Journal of Power Sources 258 420 - 423 2014.07
Language：English Publishing type：Research paper (scientific journal) Publisher：ELSEVIER SCIENCE BV
Sulfide solid electrolytes with cubic Na3PS4 phase has relatively high sodium ion conductivity of over 10(-4) S cm(-1) at room temperature, and all-solid-state sodium batteries Na-Sn/TiS2 with the electrolyte operated as a secondary battery at room temperature. To improve battery performance, conductivity enhancement of sulfide electrolytes is important. In this study, we have succeeded in enhancing conductivity by optimizing preparation conditions of Na3PS4 glass-ceramic electrolytes. By use of crystalline Na2S with high purity of 99.1%, cubic Na3PS4 crystals were directly precipitated by ball milling process at the composition of 75Na(2)S center dot 25P(2)S(5) (mol%). The glass-ceramic electrolyte prepared by milling for 1.5 h and consecutive heat treatment at 270 degrees C for 1 h showed the highest conductivity of 4.6 x 10(-4) S cm(-1), which is twice as high as the conductivity of the cubic Na3PS4 glass-ceramic prepared in a previous report. All-solid-state Na-Sn/NaCrO2 cells with the newly prepared electrolyte exhibited charge-discharge cycles at room temperature and kept about 60 mAh per gram of NaCrO2 for 15 cycles. (C) 2014 Elsevier B.V. All rights reserved.
DOI： 10.1016/j.jpowsour.2014.02.054
Other Link： http://orcid.org/0000-0001-8521-9690
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X-ray Crystal Structure Analysis of Sodium-Ion Conductivity in 94Na3PS4-6Na4SiS4 Glass-Ceramic Electrolytes Reviewed International journal
Naoto Tanibata, Akitoshi Hayashi, Naoto Kitamura, Yasushi Idemoto, Masahiro Tatsumisago
ChemElectroChem 1 ( 7 ) 1130 - 1132 2014.07
Authorship：Lead author Language：English Publishing type：Research paper (scientific journal) Publisher：WILEY-V C H VERLAG GMBH
Rietveld analysis of cubic Na3PS4 in the 94Na(3)PS(4)center dot 6Na(4)SiS(4) (mol%) glass ceramic indicates that two Na+ sites (Na1 and Na2) can be found in cubic Na3PS4 and that the phosphorus atoms in cubic Na3PS4 are partially replaced by silicon in the 94Na(3)PS(4)center dot 6Na(4)SiS(4) glass ceramic. The electron-density distribution of the cubic Na3PS4 structure, obtained by the maximumentropy method/Rietveld method, revealed that cubic Na3PS4 contains three-dimensional Na+ conduction pathways along the Na1 and Na2 sites. From the Rietveld analysis, the cubic Na3PS4 in the 94Na(3)PS(4)center dot 6Na(4)SiS(4) glass ceramic has a larger siteoccupancy of Na2 than that in the Na3PS4 glass ceramic, which may be responsible for the improvement in Na+ conductivity.
File： Manu..pdf
Other Link： http://orcid.org/0000-0001-8521-9690
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硫化物電解質を用いた全固体ナトリウム－硫黄系高容量電池の開発 Reviewed
林 晃敏, 谷端直人, 辰巳砂昌弘
Electrochemistry (電気化学および工業物理化学) 82 ( 3 ) 175 - 180 2014.05
Language：Japanese Publishing type：Research paper (scientific journal)
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Preparation and characterization of highly sodium ion conducting Na3PS4-Na4SiS4 solid electrolytes Reviewed International journal
Naoto Tanibata, Kousuke Noi, Akitoshi Hayashi, Masahiro Tatsumisago
RSC Advances 4 ( 33 ) 17120 - 17123 2014
Authorship：Lead author Language：English Publishing type：Research paper (scientific journal) Publisher：Royal Society of Chemistry (RSC)
<p>Glass–ceramic electrolyte in the system Na<sub>3</sub>PS<sub>4</sub>–Na<sub>4</sub>SiS<sub>4</sub> exhibits a high Na<sup>+</sup> ion conductivity of 7.4 × 10<sup>−4</sup> S cm<sup>−1</sup> at 25 °C.</p>
DOI： 10.1039/c4ra00996g
Other Link： http://orcid.org/0000-0001-8521-9690
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