Development of materials for all-solid-state lithium batteries

Development of all-solid-state lithium batteries is strongly desired to replace commercially available lithiumion batteries using conventional electrolyte solutions, because the all-solid- state batteries have some advantages, such as high reliability and high safety performance. For the development of the all-solid-state lithium batteries, non-flammable lithium-ion conducting solid electrolytes and also positive and negative electrode materials suitable for the all-solid-state batteries are indispensable materials. Phosphorus-sulfide based lithium-ion conducting materials have been prepared by a high-energy ball-milling process. The solid electrolytes in the system Li 2S-P2S3P2S5 show high lithium-ion conductivity over 6 × 10-4 Scm-1 at room temperature and have been prominent electrochemical stability. New Li-Si alloy has been also prepared by the high-energy ball-milling process and investigated as negative electrode materials for the all-solid-state batteries. The new alloy shows large specific capacity about 300 mAhg-1 and good charge-discharge reversibility.