Approach to Practical Application of All Solid-State Li-Ion Batteries at AIST

摘要

Energy storage devices like rechargeable batteries play an important role in our lives as the source of power for mobile phones, personal computers, electric vehicles, hybrid vehicles and other objects. In order to improve the convenience of mobile electronic information devices and clean energy vehicles, it will be necessary to create storage devices with a greater energy density than that of present Li-ion batteries. Both sulfide-type and oxide-type all-solid-state Li-ion battery (ASS-LIB) are promising next-generation battery with high energy density and safety. At this stage, a sulfide-type ASS-LIB would be close to practical use as batteries for clean energy vehicles than an oxide-type one. To improve energy and power density of the ASS-LIB, it is needed to develop the sheet-type battery in the sulfide system. On the other hand, the decrease of the interfacial resistance between electrode and solid-state electrolyte is required as well as the synthesis of solid-state electrolyte with high lithium ion conductivity in the oxide system. At AIST, several approaches have been done to realize practical application of ASS-LIB. For sulfide-type ASS-LIB, sheet-type batteries, which consist of electrode sheets with current collector sheets, are more practicable battery configuration than pellet-type one. However the reports on the sheet type ASS-LIB are still few in number although the research and development of the sheet-type ASS-LIB are as important as the materials characterization in the pellet-type batteries. In this paper, we will report the practical slurry coating process for the construction and charge-discharge performance of the sheet-type ASS-LIB. For oxide-type ASS-LIB, LISICON-type electrolyte is one of suitable candidates for assembling the ASS-LIB. However, the high temperature of sintering produces the ionic insulating interfacial phase under the battery preparation, which prevents to show the electrochemical activity of the ASS-LIB. In this paper, we will report the charge-discharge performance of the cell, assembled with an amorphous electrolyte prepared by ball-milling treatment for LISICON-type Li3.75Ge0.75P0.2504 and Li3B03, thanks to the low-temperature sinterability of this amorphous electrolyte. This work was financially supported by the Advanced Low Carbon Technology Research and Development Program of the Japan Science and Technology Agency for Specially Promoted Research for Innovative Next Generation Batteries (JST-ALCA SPRING).