出版者・発行元：ACS Applied Polymer Materials  

Although high-voltage lithium (Li) metal batteries are promising next-generation energy storage devices, their practical use is hindered by their poor cycling stability owing to low electrolyte compatibility with both Li metal anodes and 5 V-class cathodes. In this study, we report that the gelation of salt-concentrated electrolytes with weakly coordinating poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) effectively improves the cycling stability of high-voltage Li metal batteries. The PVDF-HFP-based gel polymer electrolyte with a salt-concentrated electrolyte comprising lithium bis(fluorosulfonyl)amide (LiFSA) and sulfolane (SL) achieves a high Coulombic efficiency and dense deposition morphology of Li metal anodes, along with sufficient oxidation stability against 5 V-class cathodes. Experimental and computational analyses show that the solvation structures of SL-Li⁺-FSA^-, similar to those in the original concentrated electrolyte, are maintained in the PVDF-HFP matrix, which leads to the formation of a low-resistance solid electrolyte interphase (SEI) rich in lithium fluoride and sulfur compounds. These findings indicate that the low-resistance SEI in the gel polymer electrolyte promotes dense Li deposits, which suppresses electrolyte decomposition and inactive Li formation, improving the Coulombic efficiency of Li metal anodes. We demonstrate that the stable cycling of a Li metal battery with a 5 V-class LiNi<inf>0.5</inf>Mn<inf>1.5</inf>O<inf>4</inf> cathode is enabled by the gel electrolyte, which inhibits the deposition of transition metals dissolved from the cathode onto the anode. This electrolyte and interface design is an effective strategy for developing 5 V-class Li metal batteries and can be applied to other high-energy-density metal batteries with high-voltage cathodes.

DOI： 10.1021/acsapm.4c03396

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出版者・発行元：Advanced Energy and Sustainability Research  

A CsSnCl<inf>3</inf>-based solid electrolyte in which 5% of Sn sites are occupied by Y ions, CsSn<inf>0.95</inf>Y<inf>0.05</inf>Cl<inf>3.05</inf> (CSYC), is developed using a one-step mechanical ball-milling method. CSYC exhibits a stable cubic perovskite crystal structure and a high chloride ion conductivity of 4.9 mS cm⁻¹. The relative density of a CSYC pellet following cold pressing without heat treatment is 97.5%. The high relative density and ionic conductivity are considered to originate from the high mechanical plasticity of the pellets, as evidenced by a low Young's modulus of 8.2 GPa. An all-solid-state chloride ion battery cell using CSYC as the electrolyte, BiCl<inf>3</inf> as the active cathode material, and Sn as the anode is confirmed to operate at room temperature. The cell shows a large initial discharge capacity of 178 mAh g⁻¹, ≈70% utilization, and good capacity retention with a reversible capacity of 100 mAh g⁻¹ after 40 cycles. The mechanical plasticity of CSYC is considered to be a major contributor to its high ionic conductivity and good battery cycling performance.

DOI： 10.1002/aesr.202400198

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出版者・発行元：Journal of Magnesium and Alloys  

MgH2 and TiH2 have been extensively studied as potential anode materials due to their high theoretical specific capacities of 2036 and 1024 mAh/g, respectively. However, the large volume changes that these compounds undergo during cycling affects their performance and limits practical applications. The present work demonstrates a novel approach to limiting the volume changes of active materials. This effect is based on mechanical support from an intimate interface generated in situ via the reaction between MgH2 and Ti within the electrode prior to lithiation to form Mg and TiH2. The resulting Mg can be transformed back to MgH2 by reaction with LiH during delithiation. In addition, the TiH2 improves the reaction kinetics of MgH2 and enhances electrochemical performance. The intimate interface produced in this manner is found to improve the electrochemical properties of a MgH2-Ti-LiH electrode. An exceptional reversible capacity of 800 mAh/g is observed even after 200 cycles with a high current density of 1 mA/cm2 and a high proportion of active material (90 wt.%) at an operation temperature of 120 °C. This study therefore showcases a new means of improving the performance of electrodes by limiting the volume changes of active materials.

DOI： 10.1016/j.jma.2024.08.006

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出版者・発行元：Advanced Sustainable Systems  

Many chemical reactions are accompanied by concerted phenomena, such as variance transition, structural changes, and particle formation. Various measurement techniques are employed to understand the whole picture of such concerted phenomena. A combination of small-angle X-ray scattering (SAXS), X-ray diffraction (XRD), and X-ray absorption fine structure (XAFS) is useful for studying concerted phenomena that occur, for example, inside rechargeable batteries. This combination can cover large lengths from 1 Å to several hundred nm. Operando measurements using this combination of methods can follow reactions during the charging and discharging of a rechargeable battery in a single experimental run. Fixed-exit optics enable irradiation at the same point in a wide energy range. By employing 2D detectors for XRD and SAXS and using a quick XAFS technique, one can make the interval of each measurement sufficiently short to track various phenomena during charging and discharging. Here, an application of the system for alternating SAXS/XRD/XAFS measurements constructed in BL28XU, SPring-8, Japan to the study of rechargeable batteries, is presented.

DOI： 10.1002/adsu.202300571

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出版者・発行元：Journal of Energy Storage  

Herein, we report the fabrication of an electrode composite with an ultra-high active material content (90 wt%). This composite was possible because of the utilization of TiH2 as an anode active material that forms a solid electrolyte (LiH) in situ and functions as an electronic conductor, enabling a substantial reduction of the amount of conductor additive in the electrodes. The electrochemical performance of the TiH2-based electrodes with a high active material content was comparable to that of electrode composites that include a solid electrolyte because of sufficient Li+-ion conduction pathways provided by the LiH formed in situ. To further increase the capacity of the TiH2-based electrode, MgH2 (theoretical capacity: 2036 mAh/g) was mixed with TiH2 to function as an active material. TiH2, which is known to exhibit high electron conductivity and a high density, is expected to be used as a partial substitute for low-density carbon additives to increase the volumetric energy density of batteries and their active material content. Hence, the xMgH2-(1 − x)TiH2-AB (AB: acetylene black) electrode composite exhibited a high active material content (90 wt%) and improved volumetric energy density (1687 Wh/L, based on the anode) compared with a MgH2-AB (70:30 wt%) electrode composite (1157 Wh/L), even when the AB content of the xMgH2-(1 − x)TiH2-AB composite was 10 wt%. In addition, a MgH2-TiH2-VGCF (VGCF: vapor-grown carbon fiber) based electrode composite exhibited the highest volumetric and gravimetric energy density (2154 Wh/L, 1888 Wh/kg) among the investigated composites, facilitated by sufficient electron pathways provided by VGCF.

DOI： 10.1016/j.est.2024.111286

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出版者・発行元：Electrochimica Acta  

MgH2 conversion anodes are considered promising anode active materials for use in lithium batteries because of their high theoretical lithium storage capacity and suitable redox potential. In a previous study, MgH2 was clarified to function as an anode material that forms a solid electrolyte in situ and to work without an electrolyte added to the composite electrode because of the in situ formation of LiH with an ionic conductivity of 10−7 S cm−1 at 120 °C. In the present study, to improve the energy density, cells with thick MgH2 electrodes were prepared and the reaction mechanism was investigated. With increasing thickness of the MgH2 electrode from 84 to 420 μm, the capacity decreased from 1628 to 425 mAh g−1 and the initial lithiated areal capacity was constant among cells with electrodes thicker than 140 μm. In addition, the unreacted MgH2 was found to be mainly distributed near the current collector by ex situ XPS (X-Ray Photoelectron Spectroscopy) measurement. This result differs substantially from that observed for a thick Mg(BH4)2 anode, which can self-generate LiBH4 with a high ionic conductivity of 10−3 S cm−1. The results of the present study indicate that the ionic conductivity of the in-situ-formed electrolyte strongly influences the relationship between battery performance and electrode thickness of an anode that forms an electrolyte in situ.

DOI： 10.1016/j.electacta.2024.144083

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

出版者・発行元：Batteries and Supercaps  

All-solid-state batteries have gained considerable attention due to their high safety and energy density. However, solid state electrolytes which contribute to the ionic conductivity component of a composite electrode, are not utilized during the electrode reaction and cannot directly contribute to capacity. This study focuses on decreasing the amount of electrolyte in the electrode by utilizing Ca(BH<inf>4</inf>)<inf>2</inf> as an active electrode material. In this work, the charge-discharge properties of Ca(BH<inf>4</inf>)<inf>2</inf> as an electrode material were determined for the first time. The lithiation of the Ca(BH<inf>4</inf>)<inf>2</inf> anode creates LiBH<inf>4</inf> within the electrode mixture, providing new Li-ion conduction pathways within the composite electrode in situ. An electrode fabricated only from Ca(BH<inf>4</inf>)<inf>2</inf> and acetylene black (AB) showed an initial capacity of 473 mAh g⁻¹ at 120 °C, which is comparable to the performance obtained from a composite electrode additionally containing electrolyte. Evidently, Ca(BH<inf>4</inf>)<inf>2</inf> is a promising candidate negative electrode for increased energy density all-solid-state Li-ion batteries.

DOI： 10.1002/batt.202300550

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： DOI: 10.1002/adsu.202300571

記述言語：英語   出版者・発行元：Rsc Advances  

We successfully prepared an Fe- and Li-containing polysulfide positive electrode material (Li<inf>8</inf>FeS<inf>5</inf>-Li<inf>2</inf>FeS<inf>2</inf> composite) that shows a high specific capacity (>500 mA h g⁻¹) with improved rate capability in all-solid-state cells. High-resolution TEM analysis indicated the coexistence of small crystallites of high-conductivity Li<inf>2</inf>FeS<inf>2</inf> and FeS, as well as low-crystallinity Li<inf>2</inf>S, in the composite, and this microstructure is responsible for the improved battery performance.

DOI： 10.1039/d3ra08641k

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PubMed

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： https://doi.org/10.1039/D3RA08641K

記述言語：英語   出版者・発行元：Chemistry A European Journal  

All-solid-state sodium batteries are attracting intensive attention, and chloride-based solid electrolytes are promising candidates for use in such batteries because of their high chemical stability and low Young's modulus. Here, we report new superionic conductors based on polyanion-added chloride-based materials. Na<inf>0.67</inf>Zr(SO<inf>4</inf>)<inf>0.33</inf>Cl<inf>4</inf> showed a high ionic conductivity of 1.6 mS cm⁻¹ at room temperature. X-ray diffraction analysis indicated that the highly conducting materials are mainly a mixture of an amorphous phase and Na<inf>2</inf>ZrCl<inf>6</inf>. The conductivity might be dominated by the electronegativity of the central atom of the polyanion. Electrochemical measurements reveal that Na<inf>0.67</inf>Zr(SO<inf>4</inf>)<inf>0.33</inf>Cl<inf>4</inf> is a sodium ionic conductor and is suitable for use as a solid electrolyte in all-solid-state sodium batteries.

DOI： 10.1002/chem.202301586

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PubMed

記述言語：英語   掲載種別：研究論文（学術雑誌）  

記述言語：英語   掲載種別：研究論文（学術雑誌）  

All-solid-state sodium batteries are attracting intensive attention, and chloride-based solid electrolytes are promising candidates for use in such batteries because of their high chemical stability and low Young's modulus. Here, we report new superionic conductors based on polyanion-added chloride-based materials. Na0.67Zr(SO4)(0.33)Cl-4 showed a high ionic conductivity of 1.6 mS cm(-1) at room temperature. X-ray diffraction analysis indicated that the highly conducting materials are mainly a mixture of an amorphous phase and Na2ZrCl6. The conductivity might be dominated by the electronegativity of the central atom of the polyanion. Electrochemical measurements reveal that Na0.67Zr(SO4)(0.33)Cl-4 is a sodium ionic conductor and is suitable for use as a solid electrolyte in all-solid-state sodium batteries.

出版者・発行元：Batteries and Supercaps  

All-solid-state lithium batteries, which are free from the risk of liquid entanglement, are expected to have high energy densities and high safety. In this study, the omission of a solid electrolyte from the electrode and an increase in thickness of the electrode were investigated to improve the energy density of all-solid-state lithium batteries. We focused on MgCl<inf>2</inf>, which reversibly self-generates a solid electrolyte during the lithiation process, as an anode material that can operate without a solid electrolyte incorporated into the electrode mixture. Indeed, the electrochemical properties of the MgCl<inf>2</inf> electrode were approximately the same with or without a pre-contained solid electrolyte, LiBH<inf>4</inf>. X-ray diffraction and X-ray absorption spectroscopy analyses showed that lithiation produced Mg and LiCl, which were recovered to MgCl<inf>2</inf> by subsequent delithiation. The available electrode thickness was also investigated, and the thickness limit for the first lithiation was found to be ∼100 μm.

DOI： 10.1002/batt.202300187

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記述言語：英語   出版者・発行元：公益社団法人　電気化学会  

Perovskite-type CsSnCl<inf>3</inf> is an attractive candidate for use as a solid electrolyte in all-solid-state chloride-ion batteries because it exhibits high ionic conductivity. However, perovskite-type CsSnCl<inf>3</inf> is metastable at room temperature and easily undergoes a phase transition to a stable phase. Here, we prepared perovskite-type CsSn<inf>0.95</inf>Mn<inf>0.05</inf>Cl<inf>3</inf>, in which the Sn²⁺ in CsSnCl<inf>3</inf> is partly substituted with Mn²⁺, via a mechanical milling method. Differential scanning calorimetry showed that the perovskite-type CsSn<inf>0.95</inf>Mn<inf>0.05</inf>Cl<inf>3</inf> is stable to −15 °C. Moreover, it exhibits a high chloride ionic conductivity of 2.0 × 10⁻⁴ S cm⁻¹ at 25 °C. We demonstrated the room-temperature operation of an all-solid-state chloride-ion battery with a BiCl<inf>3</inf> cathode, an Sn anode, and CsSn<inf>0.95</inf>Mn<inf>0.05</inf>Cl<inf>3</inf> as the electrolyte. The first discharge capacity of the all-solid-state cell at room temperature was 169 mAh g⁻¹ based on the weight of BiCl<inf>3</inf>. X-ray diffraction and X-ray photoelectron spectroscopic analyses confirmed that the reaction mechanism of the cell is derived from the redox reaction of BiCl<inf>3</inf> and Sn.

DOI： 10.5796/electrochemistry.23-00041

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CiNii Research

記述言語：英語   掲載種別：研究論文（学術雑誌）  

出版者・発行元：Ecs Advances  

To enhance the energy density of all-solid-state batteries, polysulfide positive electrodes have a great advantage of their high capacity. In this study, we developed Li<inf>x</inf>VS<inf>y</inf> (x = 5-9, y = 4-6) comprised Li<inf>2</inf>S and LiVS<inf>2</inf>. Although Li<inf>2</inf>S is an insulator, Li<inf>x</inf>VS<inf>y</inf> shows a high electronic conductivity (∼10⁻¹-10⁻² S cm⁻¹) because it contains LiVS<inf>2</inf> with a high electronic conductivity. The theoretical capacity of Li<inf>x</inf>VS<inf>y</inf> is 626-789 mAh g⁻¹ when all the Li in Li<inf>x</inf>VS<inf>y</inf> reacts. Li<inf>x</inf>VS<inf>y</inf> positive electrodes achieve a high energy density because they show high capacity with no conductive additives and high loading of Li<inf>x</inf>VS<inf>y</inf>

DOI： 10.1149/2754-2734/acb224

Scopus

出版者・発行元：Advanced Energy and Sustainability Research  

Fluoride batteries are attracting intensive attention because they can provide a higher energy density than conventional lithium-ion batteries. Among various metal fluorides, FeF<inf>3</inf> is a promising candidate for the cathode material of fluoride batteries because of its high theoretical capacity. In this report, the reversibility of an FeF<inf>3</inf> cathode is investigated in conjunction with fluorite-type Ba<inf>0.6</inf>La<inf>0.4</inf>F<inf>2.4</inf> as the electrolyte and Pb as the counter-electrode material. For the first time, the discharge–charge performance of a fluoride battery using FeF<inf>3</inf> cathode is investigated. The initial discharge capacity is 579 mAh g⁻¹, and a capacity of 461 mAh g⁻¹ is retained at the 10th cycle. The reversible conversion reaction mechanism for FeF<inf>3</inf> is clarified by X-ray diffraction and X-ray adsorption spectroscopy. The results revealed that FeF<inf>3</inf> is reduced to FeF<inf>2</inf> at the first-stage plateau and then to Fe metal at the second-stage plateau; they also reveal that the reverse process proceeded during charging. Ex situ scanning electron microscopy observations show that the morphology of the cathode changed reversibly and that, when the battery is in the discharged state, voids are present because of shrinkage of the electrode.

DOI： 10.1002/aesr.202200131

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担当区分：最終著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Electrochemistry  

The lithium/vanadium tetra sulfide (Li|VS<inf>4</inf>) battery can be considered a promising next-generation battery because of its high theoretical energy density, and it is expected to overcome the problems inherent in Li-S batteries. However, the charge/discharge cycle degradation of the Li|VS<inf>4</inf> battery strongly depends on the choice of the organic solvent. We investigated the equilibrium potentials of the decomposition reactions involving the VS<inf>4</inf> electrode and organic solvent molecules using the density functional and classical solution theories. We first modelled the decomposition reactions between VS<inf>4</inf> and different organic solvent molecules, such as ethylene, dimethyl, and propylene carbonates (EC, DMC, and PC). Next, we calculated the change in the Gibbs free energy of the decomposition reaction by assuming a thermodynamic cycle and estimated the equilibrium potential vs. Li/Li⁺. From the equilibrium potential, the overpotential of the DMC against the potential plateau of the Li|VS<inf>4</inf> battery is negative and shows the lowest value in the considered solvents. This result suggests that the battery cycle with DMC deteriorates more quickly than that with EC and PC. This suggestion explains the experimental tendency of battery cycle degradation and will be a useful guide for improving the electrochemical performance of Li|VS<inf>4</inf> batteries.

DOI： 10.5796/ELECTROCHEMISTRY.22-00087

DOI： 10.5796/electrochemistry.22-00087

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記述言語：英語   出版者・発行元：Physical Chemistry Chemical Physics  

A single-phase all-solid-state battery was prepared from amorphous Na<inf>3</inf>V<inf>2</inf>(PO<inf>4</inf>)<inf>3</inf> (NVP) powder, which was synthesized by mechanical milling of the crystalline NVP. It was found that the structure of the amorphous NVP was much different from that of the crystalline NVP from the FT-IR measurement. The charge-discharge curves of the half-cell using organic electrolyte were also much different from those in the case of crystalline NVP. By using amorphous NVP, a much higher ionic conductivity of the sintered pellet was observed compared with the case using crystalline NVP because of the high density of the pellet. The single-phase all-solid-state battery prepared from the amorphous NVP showed reasonable charge-discharge properties at room temperature.

DOI： 10.1039/d2cp04328a

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PubMed

記述言語：英語   掲載種別：研究論文（学術雑誌）  

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Materials Advances  

In this research, an eldfellite-type material containing V as a transition metal, NaV(SO<inf>4</inf>)<inf>2</inf>, was investigated to achieve higher potentials and capacities through the use of a multi-redox pair. Average working potentials of 3.9 and 2.1 V vs. Na/Na⁺ were observed, and a large reversible capacity of 102 mA h g⁻¹ was obtained over a wide potential range. Moreover, X-ray absorption near-edge structure and near-edge X-ray absorption fine structure measurements revealed that only V contributes to the charge compensation in the sodiation/desodiation process at low potentials, whereas both V and O contribute to the desodiation/sodiation process at high potentials. This phenomenon was also supported by the density of states and Bader charge analysis based on the DFT calculations.

DOI： 10.1039/d2ma00031h

DOI： 10.1039/d2ma00031h

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出版者・発行元：Journal of Electroanalytical Chemistry  

Iron-based conversion-type materials, which are inexpensive and have low environmental impact, are promising as cathodes for large-scale Li-ion batteries. Among these materials, iron fluoride (FeF<inf>2</inf>) is notable for its relatively high operating voltage and large reversible capacity. Here, the effect of the electrolyte type on the FeF<inf>2</inf> conversion reaction was examined, revealing that the cyclabilities of FeF<inf>2</inf> were improved by changing the electrolyte solvent from chain carbonate to cyclic coronate. During the discharge process, lithium carbonate was generated on the surface of the electrode with EC:PC electrolyte. On the other hand, lithium phosphate was produced on the surface electrodes regardless of which electrolyte was used. In addition, the amount of iron elution in EC:DMC was larger than that in EC:PC. The primary factor in the deterioration of the cycle was the elution of iron into electrolyte rather than the side reactants generated during the discharge–charge reaction. In addition, Fe³⁺ formed on the electrode surface by repeating the discharge–charge reaction, and this is the cause of the plateau appearing at 3.0 V during the discharge process of FeF<inf>2</inf> after a few cycles.

DOI： 10.1016/j.jelechem.2022.116577

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

出版者・発行元：Physica Status Solidi B Basic Research  

A cell dedicated to the characterization of the electrolyte side of the Li/electrolyte interface is developed. The reflected X-rays from the electrolyte side of the Li/electrolyte interface are measured using the developed cell. The total reflection X-ray of the Li/electrolyte interface is successfully detected, and the critical angle is near the calculated value. In addition, the critical angle after the application of current is also in good agreement with the calculated value. Furthermore, grazing-incidence X-ray scattering measurements show characteristic signals that may reflect the structural change of the electrolyte, resulting from the redox reaction at the interface region. Small changes are captured in the scattering pattern of the electrolyte in the interfacial region caused by oxidation and reduction.

DOI： 10.1002/pssb.202100539

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

担当区分：最終著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Solid State Ionics  

Due to the high theoretical capacity, VS<inf>4</inf> is a promising electrode material for next-generation rechargeable batteries. In this study, the lithium insertion and conversion process of amorphous VS<inf>4</inf> was investigated using operando electrochemical nuclear magnetic resonance (NMR) spectroscopy. Amorphous VS<inf>4</inf> has a chain-like structure similar to that of crystalline VS<inf>4</inf>. The chain structure was drastically changed to the [VS<inf>4</inf>]³⁻ tetrahedral structure by lithium insertion up to the Li<inf>3</inf>VS<inf>4</inf> composition. The lithium insertion into the [VS<inf>4</inf>]³⁻-based structure proceeded further up to the Li<inf>6</inf>VS<inf>4</inf> composition, with charge compensation by the reduction of the V valency. Finally, the conversion reaction from amorphous Li<inf>6</inf>VS<inf>4</inf> to metallic V and 4Li<inf>2</inf>S was observed. The structural reversibility of amorphous VS<inf>4</inf> was confirmed after the delithiation. It is worth mentioning that the delithiation process from the conversion products was different from the lithiation, resulting in a relatively large voltage hysteresis. Broadly, this study demonstrates that the operando electrochemical NMR technique is a useful tool for investigating the complex reaction system of non-crystalline battery materials.

DOI： 10.1016/j.ssi.2022.115920

DOI： 10.1016/j.ssi.2022.115920

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出版者・発行元：Batteries and Supercaps  

Vanadium polysulfide (VS<inf>4</inf>) is a promising material of construction for positive electrodes of next-generation batteries due to its high theoretical capacity and electrical conductivity compared to those of elemental sulfur. In this study, we investigated the charge and discharge behavior of a low-crystalline VS<inf>4</inf> positive electrode using different electrolytes and under differing charge and discharge conditions. The electrolyte composed purely of cyclic carbonate exhibited higher cycle performance than the one containing linear carbonate. Furthermore, the addition of fluoroethylene carbonate (FEC) to the electrolyte was very effective to improve the cycle performance. The effects of FEC on the VS<inf>4</inf> positive electrode were investigated using electrochemical techniques, X-ray photoelectron spectroscopy, and electron microscopy, the results whereof indicated that LiF-containing components were formed on the VS<inf>4</inf> surface, and probably contributed to the improvement of the charge and discharge behavior of the VS<inf>4</inf> positive electrode.

DOI： 10.1002/batt.202200016

Scopus

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： https://doi.org/10.1039/D2RA01199A

記述言語：英語   出版者・発行元：Rsc Advances  

All-solid-state Li batteries have attracted significant attention because of their high energy density and high level of safety. In a solid-state Li-ion battery, the electrodes contain a solid electrolyte that does not contribute directly to the capacity. Therefore, a battery that does not require a solid electrolyte in its electrode mixture should exhibit a higher energy density. In this study, a MgH<inf>2</inf> electrode was used as the negative electrode material without a solid electrolyte in its mixture. The resultant battery demonstrated excellent performance because of the formation of an ionic conduction path based on LiH in the electrode mixture. LiH and Mg clearly formed upon lithiation and returned to MgH<inf>2</inf> upon delithiation as revealed by TEM-EELS analysis. This mechanism of in situ electrolyte formation enables the development of a solid-state battery with a high energy density.

DOI： 10.1039/d2ra01199a

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PubMed

担当区分：最終著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： https://doi.org/10.5796/electrochemistry.22-00014

出版者・発行元：Separations  

Most commercially available lithium ion battery systems and some of their possible successors, such as lithium (metal)-sulfur batteries, rely on liquid organic electrolytes. Since the electrolyte is in contact with both the negative and the positive electrode, its electrochemical stability window is of high interest. Monitoring the electrolyte decomposition occurring at these electrodes is key to understand the influence of chemical and electrochemical reactions on cell performance and to evaluate aging mechanisms. In the context of lithium-sulfur batteries, information about the analysis of soluble species in the electrolytes—besides the well-known lithium polysulfides—is scarcely available. Here, the irreversible decomposition reactions of typically ether-based electrolytes will be addressed. Gas chromatography in combination with mass spectrometric detection is able to deliver information about volatile organic compounds. Furthermore, it is already used to investigate similar samples, such as electrolytes from other battery types, including lithium ion batteries. The method transfer from these reports and from model experiments with non-target analyses are promising tools to generate knowledge about the system and to build up suitable strategies for lithium-sulfur cell analyses. In the presented work, the aim is to identify aging products emerging in electrolytes regained from cells with sulfur-based cathodes. Higher-molecular polymerization products of etherbased electrolytes used in lithium-sulfur batteries are identified. Furthermore, the reactivity of the lithium polysulfides with carbonate-based solvents is investigated in a worst-case scenario and carbonate sulfur cross-compounds identified for target analyses. None of the target molecules are found in carbonate-based electrolytes regained from operative lithium-titanium sulfide cells, thus hinting at a new aging mechanism in these systems.

DOI： 10.3390/separations9030057

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： https://doi.org/10.3390/separations9030057

担当区分：最終著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： https://doi.org/10.1002/batt.202200016

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：公益社団法人　電気化学会  

In a conversion-type electrode material of lithium-ion batteries, a phase separation SAXS instrumentation phenomenon is induced by charge-discharge reaction. In this study, the spatial periodicity of phase-separated nanostructures induced in the discharged ferrous fluoride (FeF2) electrodes were investigated using the small-angle X-ray scattering (SAXS) method. The SAXS results of discharged FeF2 resembled the scattering results of the bicontinuous structures via spinodal decomposition. Thus, the SAXS results showed that the discharged FeF2 electrodes were modulated nanostructures with a spatial periodicity. SAXS measurements also showed that the size of the discharged FeF2 nanostructures was dependent on the cycle number. These SAXS finding on the morphological evolution of the nanoscale structure of conversion electrodes should be useful to reveal the mechanism of conversion reactions.

DOI： 10.5796/electrochemistry.22-00040

DOI： 10.5796/electrochemistry.22-00040

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Scopus

CiNii Research

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： https://doi.org/10.1002/pssb.202100539

出版者・発行元：ACS Applied Materials and Interfaces  

Amorphous transition-metal polysulfides are promising positive electrode materials for next-generation rechargeable lithium-ion batteries because of their high theoretical capacities. In this study, sulfur anion redox during lithiation of amorphous TiS<inf>4</inf> (a-TiS<inf>4</inf>) was investigated by using experimental and theoretical methods. It was found that a-TiS<inf>4</inf> has a variety of sulfur valence states such as S²⁻, S⁻, and S^δ⁻. The S²⁻ species became the main component in the Li<inf>4</inf>TiS<inf>4</inf> composition, indicating that sulfur is a redox-active element up to this composition. The simulated a-TiS<inf>4</inf> structure changed gradually by lithium accommodation to form a-Li<inf>4</inf>TiS<inf>4</inf>: S−S bonds in the disulfide units and polysulfide chains were broken. Bader charge analysis suggested that the average S valency decreased drastically. Moreover, deep lithiation of a-TiS<inf>4</inf> provided a conversion reaction to metallic Ti and Li<inf>2</inf>S, with a high practical capacity of ∼1000 mAh g⁻¹ when a lower cutoff voltage was applied(Figure Presented).

DOI： 10.1021/acsami.2c07337

Scopus

出版者・発行元：Electrochemistry  

Li metal is the ultimate anode material for rechargeable Li batteries because of its high capacity and low electrochemical potential. However, Li metal anodes suffer from low Coulombic efficiency and poor cycling stability owing to the growth of Li dendrites. In this study, we report that a localized high-concentration electrolyte comprising lithium bis(fluorosulfonyl) imide (LiFSI), ethylene carbonate (EC), propylene carbonate (PC), and 1,1,2,2-tetrafluoroethyl 2,2,3,3-tetrafluoropropyl ether (HFE) achieves stable Li plating/stripping cycling with a Coulombic efficiency of >98 %. In contrast to LiFSI/EC : PC electrolytes, this electrolyte shows good wettability on a polypropylene separator. Li metal deposited in this electrolyte displays a large, granular, and dense morphology. Spectroscopic analyses confirm strong FSI-Li+ coordination in this electrolyte, leading to the formation of a solid electrolyte interphase (SEI) layer enriched with LiF and sulfurous compounds derived from FSI-. These results indicate that the SEI layer facilitates the deposition of compact Li and effectively prevents Li loss owing to electrolyte decomposition and dead Li formation, resulting in highly reversible Li plating/stripping cycling. This electrolyte design can be an effective strategy for developing high-energy-density Li metal batteries.

DOI： 10.5796/ELECTROCHEMISTRY.22-00014

Scopus

担当区分：最終著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： https://doi.org/10.1021/acsaem.1c02312

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： https://doi.org/10.5796/electrochemistry.21-00069

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： https://doi.org/10.5796/electrochemistry.21-00026

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： doi.org/10.5796/electrochemistry.21-00015

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： https://doi.org/10.1246/cl.210208

担当区分：最終著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： https://doi.org/10.1149/1945-7111/abfc9d

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： DOI: 10.1039/d0se01112f

担当区分：最終著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1063/5.0032094

開催年月日： 2023年11月

記述言語：日本語   会議種別：口頭発表（一般）  

開催地：大阪市   国名：日本国  

開催年月日： 2023年11月

記述言語：日本語   会議種別：口頭発表（一般）  

開催地：札幌   国名：日本国  

開催年月日： 2023年10月 - 2023年11月

記述言語：英語   会議種別：口頭発表（一般）  

開催地：ホーチミン市   国名：ベトナム社会主義共和国  

開催年月日： 2023年10月

記述言語：英語   会議種別：口頭発表（一般）  

開催地：台北市   国名：台湾  

開催年月日： 2023年10月

記述言語：英語   会議種別：口頭発表（一般）  

開催地：台北市   国名：台湾  

開催年月日： 2023年9月

記述言語：日本語   会議種別：口頭発表（一般）  

開催地：オンライン   国名：日本国  

開催年月日： 2023年9月

記述言語：日本語   会議種別：口頭発表（一般）  

開催地：九州大学   国名：日本国  

開催年月日： 2023年4月

記述言語：日本語   会議種別：口頭発表（一般）  

開催地：大阪市   国名：日本国  

開催年月日： 2023年3月

記述言語：日本語   会議種別：口頭発表（一般）  

開催地：仙台   国名：日本国  

開催年月日： 2022年12月

記述言語：英語   会議種別：口頭発表（一般）  

開催地：National University of Singapore   国名：シンガポール共和国  

開催年月日： 2022年11月

記述言語：日本語   会議種別：口頭発表（一般）  

開催地：福岡   国名：日本国  

開催年月日： 2022年11月

記述言語：日本語   会議種別：口頭発表（一般）  

開催地：福岡   国名：日本国  

開催年月日： 2022年10月

記述言語：英語   会議種別：口頭発表（一般）  

開催地：Bled   国名：スロベニア共和国  

開催年月日： 2022年9月

記述言語：日本語   会議種別：口頭発表（一般）  

開催地：横浜   国名：日本国  

開催年月日： 2021年11月 - 2021年12月

記述言語：日本語  

開催地：横浜   国名：日本国  

開催年月日： 2021年11月 - 2021年12月

記述言語：日本語  

開催地：横浜   国名：日本国  

MgH2は負極としての動作時にLi挿入によりLiHをその場形成することから、電解質を含まず導電助剤だけを混合した固体電池の電極合材で十分作動し、電極としてより大きなエネルギーを取り出せることを見出した。

開催年月日： 2021年11月 - 2021年12月

記述言語：日本語  

開催地：横浜   国名：日本国  

開催年月日： 2021年11月 - 2021年12月

記述言語：日本語  

開催地：横浜   国名：日本国  

開催年月日： 2021年11月 - 2021年12月

記述言語：日本語  

開催地：横浜   国名：日本国  

開催年月日： 2021年11月 - 2021年12月

記述言語：日本語  

開催地：横浜   国名：日本国  

記述言語：日本語  

開催地：大阪   国名：日本国  

種別：学会・研究会等 

種別：大会・シンポジウム等 

種別：大会・シンポジウム等 

種別：学会・研究会等 

種別：審査・学術的助言 

種別：学会・研究会等 

種別：審査・学術的助言 

種別：大会・シンポジウム等 

硫化物電池の開発の概要