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Shin-ichi Orimo - One of the best experts on this subject based on the ideXlab platform.
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Colossal barocaloric effects in the Complex Hydride Li$_{2}$B$_{12}$H$_{12}$
arXiv: Materials Science, 2020Co-Authors: Kartik Sau, Shin-ichi Orimo, Daniel Errandonea, Tamio Ikeshoji, Shigeyuki Takagi, Dewei Chu, Claudio CazorlaAbstract:Traditional refrigeration technologies based on compression cycles of greenhouse gases pose serious threats to the environment and cannot be downscaled to electronic device dimensions. Solid-state cooling exploits the thermal response of caloric materials to external fields and represents a promising alternative to current refrigeration methods. However, most of the caloric materials known to date present relatively small adiabatic temperature changes ($|\Delta T| \sim 1$ K) and/or limiting irreversibility issues resulting from significant phase-transition hysteresis. Here, we predict the existence of colossal barocaloric effects (isothermal entropy changes of $|\Delta S| \sim 100$ JK$^{-1}$kg$^{-1}$) in the energy material Li$_{2}$B$_{12}$H$_{12}$ by means of molecular dynamics simulations. Specifically, we estimate $|\Delta S| = 387$ JK$^{-1}$kg$^{-1}$ and $|\Delta T| = 26$ K for an applied pressure of $P = 0.4$ GPa at $T = 475$ K. The disclosed colossal barocaloric effects are originated by an order-disorder phase transformation that exhibits a fair degree of reversibility and involves coexisting Li$^{+}$ diffusion and (BH)$_{12}^{-2}$ reorientational motion at high temperatures.
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colossal barocaloric effects in the Complex Hydride li _ 2 b _ 12 h _ 12
arXiv: Materials Science, 2020Co-Authors: Kartik Sau, Shin-ichi Orimo, Daniel Errandonea, Tamio Ikeshoji, Shigeyuki Takagi, Dewei Chu, Claudio CazorlaAbstract:Traditional refrigeration technologies based on compression cycles of greenhouse gases pose serious threats to the environment and cannot be downscaled to electronic device dimensions. Solid-state cooling exploits the thermal response of caloric materials to external fields and represents a promising alternative to current refrigeration methods. However, most of the caloric materials known to date present relatively small adiabatic temperature changes ($|\Delta T| \sim 1$ K) and/or limiting irreversibility issues resulting from significant phase-transition hysteresis. Here, we predict the existence of colossal barocaloric effects (isothermal entropy changes of $|\Delta S| \sim 100$ JK$^{-1}$kg$^{-1}$) in the energy material Li$_{2}$B$_{12}$H$_{12}$ by means of molecular dynamics simulations. Specifically, we estimate $|\Delta S| = 387$ JK$^{-1}$kg$^{-1}$ and $|\Delta T| = 26$ K for an applied pressure of $P = 0.4$ GPa at $T = 475$ K. The disclosed colossal barocaloric effects are originated by an order-disorder phase transformation that exhibits a fair degree of reversibility and involves coexisting Li$^{+}$ diffusion and (BH)$_{12}^{-2}$ reorientational motion at high temperatures.
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Complex Hydride Solid Electrolytes of the Li(CB9H10)–Li(CB11H12) Quasi-Binary System: Relationship between the Solid Solution and Phase Transition, and the Electrochemical Properties
ACS Applied Energy Materials, 2020Co-Authors: Sangryun Kim, Hiroyuki Oguchi, Shigeyuki Takagi, Kazuaki Kisu, Shin-ichi OrimoAbstract:Closo-type Complex Hydrides have recently received much attention as promising solid electrolyte systems for all-solid-state batteries, because of the high lithium ion conductivity of their high-te...
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room temperature operation of all solid state battery using a closo type Complex Hydride solid electrolyte and a licoo2 cathode by interfacial modification
Journal of Energy Chemistry, 2020Co-Authors: Kentaro Harada, Hiroyuki Oguchi, Naoki Toyama, Kazuaki Kisu, Shin-ichi OrimoAbstract:Abstract We report on an all-solid-state battery that employs a closo-type Complex Hydride solid electrolyte and a LiCoO2 cathode. Interfacial modification between the solid electrolyte and cathode with a LiNbO3 buffer layer enables reversible charge-discharge cycling with a cell voltage of 3.9 V (vs. Li+/Li) at room temperature. Electrochemical analyses clarify that the given modification effectively suppresses side reactions at the cathode/solid electrolyte interface. The interfacial resistance is lowered by ca. 10 times with a 5 nm thick LiNbO3 buffer layer compared to that without a buffer layer, so that a discharge capacity of 109 mAh g−1 is achieved. These results suggest that interfacial modification can be a viable approach to the development of high-voltage all-solid-state batteries using closo-type Complex Hydride solid electrolytes and oxide cathodes.
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a Complex Hydride lithium superionic conductor for high energy density all solid state lithium metal batteries
Nature Communications, 2019Co-Authors: Hiroyuki Oguchi, Toyoto Sato, Shigeyuki Takagi, Naoki Toyama, Toshiya Otomo, Dorai Arunkumar, Naoaki Kuwata, Junichi Kawamura, Shin-ichi OrimoAbstract:All-solid-state batteries incorporating lithium metal anode have the potential to address the energy density issues of conventional lithium-ion batteries that use flammable organic liquid electrolytes and low-capacity carbonaceous anodes. However, they suffer from high lithium ion transfer resistance, mainly due to the instability of the solid electrolytes against lithium metal, limiting their use in practical cells. Here, we report a Complex Hydride lithium superionic conductor, 0.7Li(CB9H10)–0.3Li(CB11H12), with excellent stability against lithium metal and a high conductivity of 6.7 × 10−3 S cm−1 at 25 °C. This Complex Hydride exhibits stable lithium plating/stripping reaction with negligible interfacial resistance ( 2500 Wh kg−1) at a high current density of 5016 mA g−1. The present study opens up an unexplored research area in the field of solid electrolyte materials, contributing to the development of high-energy-density batteries. All-solid-state batteries could deliver high energy densities without using organic liquid electrolytes. Here the authors report a Complex Hydride Li-ion conductor 0.7Li(CB9H10)–0.3Li(CB11H12) that exhibits impressive ionic conductivity and other electrochemical characteristics in an all-solid-state cell.
Hiroyuki Oguchi - One of the best experts on this subject based on the ideXlab platform.
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Complex Hydride Solid Electrolytes of the Li(CB9H10)–Li(CB11H12) Quasi-Binary System: Relationship between the Solid Solution and Phase Transition, and the Electrochemical Properties
ACS Applied Energy Materials, 2020Co-Authors: Sangryun Kim, Hiroyuki Oguchi, Shigeyuki Takagi, Kazuaki Kisu, Shin-ichi OrimoAbstract:Closo-type Complex Hydrides have recently received much attention as promising solid electrolyte systems for all-solid-state batteries, because of the high lithium ion conductivity of their high-te...
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room temperature operation of all solid state battery using a closo type Complex Hydride solid electrolyte and a licoo2 cathode by interfacial modification
Journal of Energy Chemistry, 2020Co-Authors: Kentaro Harada, Hiroyuki Oguchi, Naoki Toyama, Kazuaki Kisu, Shin-ichi OrimoAbstract:Abstract We report on an all-solid-state battery that employs a closo-type Complex Hydride solid electrolyte and a LiCoO2 cathode. Interfacial modification between the solid electrolyte and cathode with a LiNbO3 buffer layer enables reversible charge-discharge cycling with a cell voltage of 3.9 V (vs. Li+/Li) at room temperature. Electrochemical analyses clarify that the given modification effectively suppresses side reactions at the cathode/solid electrolyte interface. The interfacial resistance is lowered by ca. 10 times with a 5 nm thick LiNbO3 buffer layer compared to that without a buffer layer, so that a discharge capacity of 109 mAh g−1 is achieved. These results suggest that interfacial modification can be a viable approach to the development of high-voltage all-solid-state batteries using closo-type Complex Hydride solid electrolytes and oxide cathodes.
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a Complex Hydride lithium superionic conductor for high energy density all solid state lithium metal batteries
Nature Communications, 2019Co-Authors: Hiroyuki Oguchi, Toyoto Sato, Shigeyuki Takagi, Naoki Toyama, Toshiya Otomo, Dorai Arunkumar, Naoaki Kuwata, Junichi Kawamura, Shin-ichi OrimoAbstract:All-solid-state batteries incorporating lithium metal anode have the potential to address the energy density issues of conventional lithium-ion batteries that use flammable organic liquid electrolytes and low-capacity carbonaceous anodes. However, they suffer from high lithium ion transfer resistance, mainly due to the instability of the solid electrolytes against lithium metal, limiting their use in practical cells. Here, we report a Complex Hydride lithium superionic conductor, 0.7Li(CB9H10)–0.3Li(CB11H12), with excellent stability against lithium metal and a high conductivity of 6.7 × 10−3 S cm−1 at 25 °C. This Complex Hydride exhibits stable lithium plating/stripping reaction with negligible interfacial resistance ( 2500 Wh kg−1) at a high current density of 5016 mA g−1. The present study opens up an unexplored research area in the field of solid electrolyte materials, contributing to the development of high-energy-density batteries. All-solid-state batteries could deliver high energy densities without using organic liquid electrolytes. Here the authors report a Complex Hydride Li-ion conductor 0.7Li(CB9H10)–0.3Li(CB11H12) that exhibits impressive ionic conductivity and other electrochemical characteristics in an all-solid-state cell.
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Interfacial stability between LiBH4-based Complex Hydride solid electrolytes and Li metal anode for all-solid-state Li batteries
Journal of Power Sources, 2019Co-Authors: Kazuaki Kisu, Hiroyuki Oguchi, Naoki Toyama, Sangryun Kim, Shin-ichi OrimoAbstract:Abstract LiBH 4 -based Complex Hydrides have attracted much attention as solid electrolytes that are highly compatible with Li metal anode, because of their reducing character and deformable nature. However, the compatibility of LiBH 4 -based Complex Hydrides following the formation of a stable interface with Li metal has not yet been fully verified. In this study, electrochemical and mechanical stabilities of LiBH 4 and Li 4 (BH 4 ) 3 I Complex Hydride solid electrolytes against Li metal were investigated. Li plating/stripping test performed for 100 cycles and cyclic voltammetry indicated their favorable electrochemical stabilities. Scanning electron microscopy and fast charge–discharge tests revealed the formation of a mechanically tight and durable interface between these solid electrolytes and the Li metal anode. To demonstrate the adequacy of the LiBH 4 -based Complex Hydride solid electrolyte for all-solid-state batteries with Li metal anode, an all-solid-state Li–S battery with a Li 4 (BH 4 ) 3 I solid electrolyte was assembled and electrochemically tested. The battery showed reversible discharge and charge abilities. This study provides useful insights into a strategy that can be applied to develop Complex Hydride solid electrolytes.
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Ionic conduction in Li3Na(NH2)4: Study of the material design for the enhancement of ion conductivity in double-cation Complex Hydrides
AIP Advances, 2019Co-Authors: Biswajit Paik, Toyoto Sato, Hiroyuki Oguchi, Shigeyuki Takagi, Naoaki Kuwata, Junichi Kawamura, Arunkumar Dorai, Shin-ichi OrimoAbstract:Complex Hydrides have collected recent attention as a new class of solid electrolytes with potential applications in all-solid-state batteries. To improve ionic conduction in the Complex Hydrides, multi-cation crystal structure can be attractive. It will allow tuning the cation dynamics via structure modification depending on types and number of additional cations. However, multi-cation crystal structure struggles with the inter-cation scattering among different cations. To address this issue, understanding the conduction mechanisms in the multi-cationic crystals is indispensable. Here, we study cationic conduction in a double-cation (Li and Na) Complex Hydride Li3Na(NH2)4, which is formed by replacing Li (with Na) from specific lattice site of LiNH2 without altering the crystal symmetry. The nuclear magnetic resonance (NMR) measurements found that Li3Na(NH2)4 is a Li-ion conductor with negligibly small Na-ion conduction. This finding is critically important to elucidate Li-ion conduction mechanism in Li3Na(NH2)4. Enhanced Li-ion conduction in Li3Na(NH2)4 is achieved by (a) suppressing diffusion of Na cation trapped at the strategically located 2c lattice sites under deep potential well; and (b) by increasing the Li defect concentration influenced by the larger volume of the Li metastable sites due to Na substitution into LiNH2. Our study will provide the design principle for multi-cation Complex Hydrides, and accelerate development of superior solid electrolytes for all-solid-state batteries.Complex Hydrides have collected recent attention as a new class of solid electrolytes with potential applications in all-solid-state batteries. To improve ionic conduction in the Complex Hydrides, multi-cation crystal structure can be attractive. It will allow tuning the cation dynamics via structure modification depending on types and number of additional cations. However, multi-cation crystal structure struggles with the inter-cation scattering among different cations. To address this issue, understanding the conduction mechanisms in the multi-cationic crystals is indispensable. Here, we study cationic conduction in a double-cation (Li and Na) Complex Hydride Li3Na(NH2)4, which is formed by replacing Li (with Na) from specific lattice site of LiNH2 without altering the crystal symmetry. The nuclear magnetic resonance (NMR) measurements found that Li3Na(NH2)4 is a Li-ion conductor with negligibly small Na-ion conduction. This finding is critically important to elucidate Li-ion conduction mechanism in Li3...
Naoki Toyama - One of the best experts on this subject based on the ideXlab platform.
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room temperature operation of all solid state battery using a closo type Complex Hydride solid electrolyte and a licoo2 cathode by interfacial modification
Journal of Energy Chemistry, 2020Co-Authors: Kentaro Harada, Hiroyuki Oguchi, Naoki Toyama, Kazuaki Kisu, Shin-ichi OrimoAbstract:Abstract We report on an all-solid-state battery that employs a closo-type Complex Hydride solid electrolyte and a LiCoO2 cathode. Interfacial modification between the solid electrolyte and cathode with a LiNbO3 buffer layer enables reversible charge-discharge cycling with a cell voltage of 3.9 V (vs. Li+/Li) at room temperature. Electrochemical analyses clarify that the given modification effectively suppresses side reactions at the cathode/solid electrolyte interface. The interfacial resistance is lowered by ca. 10 times with a 5 nm thick LiNbO3 buffer layer compared to that without a buffer layer, so that a discharge capacity of 109 mAh g−1 is achieved. These results suggest that interfacial modification can be a viable approach to the development of high-voltage all-solid-state batteries using closo-type Complex Hydride solid electrolytes and oxide cathodes.
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a Complex Hydride lithium superionic conductor for high energy density all solid state lithium metal batteries
Nature Communications, 2019Co-Authors: Hiroyuki Oguchi, Toyoto Sato, Shigeyuki Takagi, Naoki Toyama, Toshiya Otomo, Dorai Arunkumar, Naoaki Kuwata, Junichi Kawamura, Shin-ichi OrimoAbstract:All-solid-state batteries incorporating lithium metal anode have the potential to address the energy density issues of conventional lithium-ion batteries that use flammable organic liquid electrolytes and low-capacity carbonaceous anodes. However, they suffer from high lithium ion transfer resistance, mainly due to the instability of the solid electrolytes against lithium metal, limiting their use in practical cells. Here, we report a Complex Hydride lithium superionic conductor, 0.7Li(CB9H10)–0.3Li(CB11H12), with excellent stability against lithium metal and a high conductivity of 6.7 × 10−3 S cm−1 at 25 °C. This Complex Hydride exhibits stable lithium plating/stripping reaction with negligible interfacial resistance ( 2500 Wh kg−1) at a high current density of 5016 mA g−1. The present study opens up an unexplored research area in the field of solid electrolyte materials, contributing to the development of high-energy-density batteries. All-solid-state batteries could deliver high energy densities without using organic liquid electrolytes. Here the authors report a Complex Hydride Li-ion conductor 0.7Li(CB9H10)–0.3Li(CB11H12) that exhibits impressive ionic conductivity and other electrochemical characteristics in an all-solid-state cell.
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Interfacial stability between LiBH4-based Complex Hydride solid electrolytes and Li metal anode for all-solid-state Li batteries
Journal of Power Sources, 2019Co-Authors: Kazuaki Kisu, Hiroyuki Oguchi, Naoki Toyama, Sangryun Kim, Shin-ichi OrimoAbstract:Abstract LiBH 4 -based Complex Hydrides have attracted much attention as solid electrolytes that are highly compatible with Li metal anode, because of their reducing character and deformable nature. However, the compatibility of LiBH 4 -based Complex Hydrides following the formation of a stable interface with Li metal has not yet been fully verified. In this study, electrochemical and mechanical stabilities of LiBH 4 and Li 4 (BH 4 ) 3 I Complex Hydride solid electrolytes against Li metal were investigated. Li plating/stripping test performed for 100 cycles and cyclic voltammetry indicated their favorable electrochemical stabilities. Scanning electron microscopy and fast charge–discharge tests revealed the formation of a mechanically tight and durable interface between these solid electrolytes and the Li metal anode. To demonstrate the adequacy of the LiBH 4 -based Complex Hydride solid electrolyte for all-solid-state batteries with Li metal anode, an all-solid-state Li–S battery with a Li 4 (BH 4 ) 3 I solid electrolyte was assembled and electrochemically tested. The battery showed reversible discharge and charge abilities. This study provides useful insights into a strategy that can be applied to develop Complex Hydride solid electrolytes.
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Fast Lithium-ion Conduction in Atom-Deficient Closo-Type Complex Hydride Solid Electrolytes
Chemistry of Materials, 2018Co-Authors: Sangryun Kim, Toyoto Sato, Hiroyuki Oguchi, Tamio Ikeshoji, Shigeyuki Takagi, Naoki Toyama, Shin-ichi OrimoAbstract:closo-type Complex Hydrides contain large cage-type Complex polyanions in their crystal structures and thus can exhibit superior ion-conducting properties (e.g., Li and Na). However, the unique structures of Complex polyanions have made it challenging to modify crystal structures, making systematic control of ion conductivity difficult. Here, we report an atom deficiency approach to enhance lithium-ion conductivity of Complex Hydrides. We find that lithium and hydrogen could be simultaneously extracted from Li2B12H12 by applying a small external energy, enabling the formation of atom deficiencies. These atom deficiencies lead to an increase in carrier concentration, improving lithium-ion conductivity by 3 orders of magnitude compared to that of a pristine material. An all-solid-state TiS2/Li battery employing atom-deficient Li2B12H12 as a solid electrolyte exhibits superior battery performance during repeated discharge–charge cycles. The current study suggests that the atom deficiency can be a useful stra...
Shigeyuki Takagi - One of the best experts on this subject based on the ideXlab platform.
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Colossal barocaloric effects in the Complex Hydride Li$_{2}$B$_{12}$H$_{12}$
arXiv: Materials Science, 2020Co-Authors: Kartik Sau, Shin-ichi Orimo, Daniel Errandonea, Tamio Ikeshoji, Shigeyuki Takagi, Dewei Chu, Claudio CazorlaAbstract:Traditional refrigeration technologies based on compression cycles of greenhouse gases pose serious threats to the environment and cannot be downscaled to electronic device dimensions. Solid-state cooling exploits the thermal response of caloric materials to external fields and represents a promising alternative to current refrigeration methods. However, most of the caloric materials known to date present relatively small adiabatic temperature changes ($|\Delta T| \sim 1$ K) and/or limiting irreversibility issues resulting from significant phase-transition hysteresis. Here, we predict the existence of colossal barocaloric effects (isothermal entropy changes of $|\Delta S| \sim 100$ JK$^{-1}$kg$^{-1}$) in the energy material Li$_{2}$B$_{12}$H$_{12}$ by means of molecular dynamics simulations. Specifically, we estimate $|\Delta S| = 387$ JK$^{-1}$kg$^{-1}$ and $|\Delta T| = 26$ K for an applied pressure of $P = 0.4$ GPa at $T = 475$ K. The disclosed colossal barocaloric effects are originated by an order-disorder phase transformation that exhibits a fair degree of reversibility and involves coexisting Li$^{+}$ diffusion and (BH)$_{12}^{-2}$ reorientational motion at high temperatures.
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colossal barocaloric effects in the Complex Hydride li _ 2 b _ 12 h _ 12
arXiv: Materials Science, 2020Co-Authors: Kartik Sau, Shin-ichi Orimo, Daniel Errandonea, Tamio Ikeshoji, Shigeyuki Takagi, Dewei Chu, Claudio CazorlaAbstract:Traditional refrigeration technologies based on compression cycles of greenhouse gases pose serious threats to the environment and cannot be downscaled to electronic device dimensions. Solid-state cooling exploits the thermal response of caloric materials to external fields and represents a promising alternative to current refrigeration methods. However, most of the caloric materials known to date present relatively small adiabatic temperature changes ($|\Delta T| \sim 1$ K) and/or limiting irreversibility issues resulting from significant phase-transition hysteresis. Here, we predict the existence of colossal barocaloric effects (isothermal entropy changes of $|\Delta S| \sim 100$ JK$^{-1}$kg$^{-1}$) in the energy material Li$_{2}$B$_{12}$H$_{12}$ by means of molecular dynamics simulations. Specifically, we estimate $|\Delta S| = 387$ JK$^{-1}$kg$^{-1}$ and $|\Delta T| = 26$ K for an applied pressure of $P = 0.4$ GPa at $T = 475$ K. The disclosed colossal barocaloric effects are originated by an order-disorder phase transformation that exhibits a fair degree of reversibility and involves coexisting Li$^{+}$ diffusion and (BH)$_{12}^{-2}$ reorientational motion at high temperatures.
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Complex Hydride Solid Electrolytes of the Li(CB9H10)–Li(CB11H12) Quasi-Binary System: Relationship between the Solid Solution and Phase Transition, and the Electrochemical Properties
ACS Applied Energy Materials, 2020Co-Authors: Sangryun Kim, Hiroyuki Oguchi, Shigeyuki Takagi, Kazuaki Kisu, Shin-ichi OrimoAbstract:Closo-type Complex Hydrides have recently received much attention as promising solid electrolyte systems for all-solid-state batteries, because of the high lithium ion conductivity of their high-te...
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a Complex Hydride lithium superionic conductor for high energy density all solid state lithium metal batteries
Nature Communications, 2019Co-Authors: Hiroyuki Oguchi, Toyoto Sato, Shigeyuki Takagi, Naoki Toyama, Toshiya Otomo, Dorai Arunkumar, Naoaki Kuwata, Junichi Kawamura, Shin-ichi OrimoAbstract:All-solid-state batteries incorporating lithium metal anode have the potential to address the energy density issues of conventional lithium-ion batteries that use flammable organic liquid electrolytes and low-capacity carbonaceous anodes. However, they suffer from high lithium ion transfer resistance, mainly due to the instability of the solid electrolytes against lithium metal, limiting their use in practical cells. Here, we report a Complex Hydride lithium superionic conductor, 0.7Li(CB9H10)–0.3Li(CB11H12), with excellent stability against lithium metal and a high conductivity of 6.7 × 10−3 S cm−1 at 25 °C. This Complex Hydride exhibits stable lithium plating/stripping reaction with negligible interfacial resistance ( 2500 Wh kg−1) at a high current density of 5016 mA g−1. The present study opens up an unexplored research area in the field of solid electrolyte materials, contributing to the development of high-energy-density batteries. All-solid-state batteries could deliver high energy densities without using organic liquid electrolytes. Here the authors report a Complex Hydride Li-ion conductor 0.7Li(CB9H10)–0.3Li(CB11H12) that exhibits impressive ionic conductivity and other electrochemical characteristics in an all-solid-state cell.
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Ionic conduction in Li3Na(NH2)4: Study of the material design for the enhancement of ion conductivity in double-cation Complex Hydrides
AIP Advances, 2019Co-Authors: Biswajit Paik, Toyoto Sato, Hiroyuki Oguchi, Shigeyuki Takagi, Naoaki Kuwata, Junichi Kawamura, Arunkumar Dorai, Shin-ichi OrimoAbstract:Complex Hydrides have collected recent attention as a new class of solid electrolytes with potential applications in all-solid-state batteries. To improve ionic conduction in the Complex Hydrides, multi-cation crystal structure can be attractive. It will allow tuning the cation dynamics via structure modification depending on types and number of additional cations. However, multi-cation crystal structure struggles with the inter-cation scattering among different cations. To address this issue, understanding the conduction mechanisms in the multi-cationic crystals is indispensable. Here, we study cationic conduction in a double-cation (Li and Na) Complex Hydride Li3Na(NH2)4, which is formed by replacing Li (with Na) from specific lattice site of LiNH2 without altering the crystal symmetry. The nuclear magnetic resonance (NMR) measurements found that Li3Na(NH2)4 is a Li-ion conductor with negligibly small Na-ion conduction. This finding is critically important to elucidate Li-ion conduction mechanism in Li3Na(NH2)4. Enhanced Li-ion conduction in Li3Na(NH2)4 is achieved by (a) suppressing diffusion of Na cation trapped at the strategically located 2c lattice sites under deep potential well; and (b) by increasing the Li defect concentration influenced by the larger volume of the Li metastable sites due to Na substitution into LiNH2. Our study will provide the design principle for multi-cation Complex Hydrides, and accelerate development of superior solid electrolytes for all-solid-state batteries.Complex Hydrides have collected recent attention as a new class of solid electrolytes with potential applications in all-solid-state batteries. To improve ionic conduction in the Complex Hydrides, multi-cation crystal structure can be attractive. It will allow tuning the cation dynamics via structure modification depending on types and number of additional cations. However, multi-cation crystal structure struggles with the inter-cation scattering among different cations. To address this issue, understanding the conduction mechanisms in the multi-cationic crystals is indispensable. Here, we study cationic conduction in a double-cation (Li and Na) Complex Hydride Li3Na(NH2)4, which is formed by replacing Li (with Na) from specific lattice site of LiNH2 without altering the crystal symmetry. The nuclear magnetic resonance (NMR) measurements found that Li3Na(NH2)4 is a Li-ion conductor with negligibly small Na-ion conduction. This finding is critically important to elucidate Li-ion conduction mechanism in Li3...
Atsushi Unemoto - One of the best experts on this subject based on the ideXlab platform.
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development of Complex Hydride based all solid state lithium ion battery applying low melting point electrolyte
Journal of Power Sources, 2017Co-Authors: Shohei Suzuki, Jun Kawaji, Koji Yoshida, Atsushi Unemoto, Shin-ichi OrimoAbstract:Abstract A thermally durable all-solid-state lithium ion battery composed of a Complex Hydride, oxide electrolytes, and LiNi1/3Mn1/3Co1/3O2 active material is developed. This battery exhibits a discharge capacity of 56 mAh g−1, and the tenth capacity retention ratio is 29% at 150 °C owing to the large contact resistance between the electrolyte layer and the composite positive electrode layer. This large contact resistance is reduced by introducing an adhesive layer comprised of a mixture of LiBH4 and LiNH2 that is easily melted by thermal treatment and fills the voids and pores at the interface between the two layers. As a result, repeated charge-discharge cycles are successfully demonstrated at 150 °C with a high discharge capacity and discharge capacity retention ratio. The first discharge capacity is enhanced to 114 mAh g−1 and the capacity retention ratio at the tenth cycle is improved to 71%. These results demonstrate that using an adhesive layer is an effective measure to reduce the contact resistance and thereby enhance the performance of the battery.
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fast sodium ionic conduction in na2b10h10 na2b12h12 pseudo binary Complex Hydride and application to a bulk type all solid state battery
Applied Physics Letters, 2017Co-Authors: Koji Yoshida, Motoaki Matsuo, Toyoto Sato, Tamio Ikeshoji, Atsushi Unemoto, Terrence J Udovic, Shin-ichi OrimoAbstract:In the present work, we developed highly sodium-ion conductive Na2B10H10-Na2B12H12 pseudo-binary Complex Hydride via mechanically ball-milling admixtures of the pure Na2B10H10 and Na2B12H12 components. Both of these components show a monoclinic phase at room temperature, but ball-milled mixtures partially stabilized highly ion-conductive, disordered cubic phases, whose fraction and favored structural symmetry (body-centered cubic or face-centered cubic) depended on the conditions of mechanical ball-milling and molar ratio of the component compounds. First-principles molecular-dynamics simulations demonstrated that the total energy of the closo-borane mixtures and pure materials is quite close, helping to explain the observed stabilization of the mixed compounds. The ionic conductivity of the closo-borane mixtures appeared to be correlated with the fraction of the body-centered-cubic phase, exhibiting a maximum at a molar ratio of Na2B10H10:Na2B12H12 = 1:3. A conductivity as high as log(σ/S cm−1) = –3.5 wa...
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Complex Hydride for composite negative electrode applicable to bulk type all solid state li ion battery with wide temperature operation
Solid State Ionics, 2016Co-Authors: Koji Yoshida, Jun Kawaji, Shohei Suzuki, Atsushi Unemoto, Shin-ichi OrimoAbstract:Abstract A composite negative electrode for use in bulk-type all-solid-state batteries was developed by combining the solid electrolyte Li 4 (BH 4 ) 3 I (LiBH 4 doped with LiI), acetylene black (AB) (as a conductive additive), and lithium titanate (Li 4 Ti 5 O 12 , LTO). Because of the highly deformable nature of the Complex Hydride, hand milling and subsequent uniaxial pressing were sufficient to ensure tight interfacial contact. As a result, the composite negative electrode allowed successful operation of a bulk-type all-solid-state battery from room temperature (23 °C) to 150 °C. The composite negative electrode was characterized via microstructural observation and using electrochemical techniques. In the prepared composite negative electrode, LTO, Li 4 (BH 4 ) 3 I, and AB were homogeneously dispersed and formed tightly contacted interfaces. At 150 °C, the battery exhibited high discharging capacities of 170 and 158 mAh g − 1 for the 1st and 2nd cycles, respectively, which corresponded to LTO utilization ratios of 97% and 90%. Moreover, it retained 140 mAh g − 1 at the 100th cycle, which equates to a 90% capacity retention ratio from the 2nd cycle. Furthermore, the battery was successfully operated at room temperature (23 °C), exhibiting discharging capacities of 122 mAh g − 1 for the 1st cycle and 111 mAh g − 1 for the 5th cycle (capacity retention ratio of 91%). At both temperatures, the coulombic efficiency was nearly 100%, indicating that the charge/discharge reactions proceeded without any significant side-reactions. This good performance is due to the small charge-transfer resistance at the LTO interface resulting from the tight contact between the constituents of the composite electrode, and suggests that LiI-doped LiBH 4 is a promising solid electrolyte for practical composite electrodes.
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fast lithium ionic conduction in a new Complex Hydride sulphide crystalline phase
Chemical Communications, 2016Co-Authors: Atsushi Unemoto, Motoaki Matsuo, Tamio Ikeshoji, Hui Wu, Terrence J Udovic, Shin-ichi OrimoAbstract:A new crystalline phase derived from a 90LiBH4:10P2S5 mixture displays high lithium-ionic conductivity of log(σ/S cm−1) = −3.0 at 300 K. It is stable up to 473 K and has both a wide potential window of 0–5 V and favorable mechanical properties for battery assembly. Its incorporation into a bulk-type all-solid-state TiS2/InLi battery enabled repeated battery operation at 300 K.