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Akitoshi Hayashi1 Atsushi Sakuda1 Masahiro Tatsumisago1

1, Osaka Prefecture University, Osaka, , Japan

All-solid-state rechargeable lithium batteries with inorganic solid electrolytes are expected as a next generation battery with high safety and high energy density. Sulfide and oxide glass-based electrolytes with both high conductivity and good ductility have been developed. Glass electrolytes are useful as a precursor for precipitating metastable crystalline phases, which are difficult to prepare by a conventional solid phase reaction. The conductivity enhancement is achieved by crystallization of Li7P3S11 metastable phases. These sulfide glass-based electrolytes also have favorable ductility for forming good solid-solid interfaces with electrode active materials. Oxide glass electrolytes in the system Li3BO3-Li2SO4-Li2CO3 also have a similar relative density to those sulfide systems. Li metal is the most attractive material as a negative electrode because of its extremely high theoretical capacity and the lowest negative electrochemical potential. Interface modification is needed for achieving stable Li dissolution/deposition cycling performance. It is noteworthy that inserting Au thin films into the Li/Li3PS4 interface improves Li reversibility. Good formability of active materials is important to form close solid-solid interfaces with solid electrolytes. Amorphous materials have a potential of an electrode active material because of their high capacity and good cyclability based on free volume in amorphous structure. Amorphous oxide electrodes in the system LiCoO2-Li2SO4 prepared via mechanochemistry have good formability and electrical conductivity, and thus a positive electrode layer with only amorphous Li1.2Co0.8S0.2O2.4 without any conductive additives functions in a solid-state cell. Amorphous electrolyte and electrode materials with high conductivity and good ductility are useful for forming favorable solid-solid interfaces.

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