Papers - TANIBATA Naoto
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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
