Development of a compact all-solid-state lithium secondary battery using single-crystal electrolyte

−29− Synthesiology English edition Vol.12 No.1 pp.29–40 (Aug. 2019) secondary battery. According to the NEDO roadmap for FY 2013 in Japan, an all-solid-state battery is positioned as a product that fully covers the potential of a next-generation battery, and is set for practical utilization in 2030. The conventional lithium secondary battery is roughly composed of four parts: a positive electrode, a negative electrode, an electrolyte, and a separator that separates the positive and negative electrodes. On the other hand, an all-solidstate lithium secondary battery is composed of three parts: a positive electrode, a negative electrode, and a lithium solid electrolyte (a lithium ion conductor), and the lithium solid electrolyte plays the roles of both an electrolyte and a separator. Figure 1 shows a schematic diagram of a conventional liquid-state lithium secondary battery and an all-solid-state lithium secondary battery. While the materials for positive and negative electrodes in conventional liquidstate lithium secondary batteries can be used in all-solid