High Voltage Charge/Discharge Performance of All Solid-State Battery Using Lithium Argyrodite Solid Electrolyte

摘要

Lithium ion batteries are being increasingly used in PHEVs and EVs in recent years. The energy density of these batteries are increasing, however the safety risks are increasing as well. One solution for addressing this problem is the use of all solid-state batteries that use nonflammable solids as the electrolyte. All solid-state batteries show promise as a next generation battery. As part of our efforts to explore the commercialization of all solid-state batteries for the future, we chose to focus on sulfide-based solid electrolytes, and are developing an Argyrodite solid electrolyte that has a high lithium ion conductivity (10-3 S/cm at room temperature) and is electrochemically stable. Argyrodite solid electrolytes are stable over a wide range of electric potentials and are not subject to decomposition of the electrolyte. These properties allow Argyrodite solid electrolytes to be used in batteries containing high-potential positive electrode material and Si negative electrode material, which facilitates the construction of batteries with higher energy densities. We are also working on the development of positive electrode materials and negative electrode materials that are suitable for all-solid state batteries that use sulfide-based solid electrolytes. In particular, we are working on establishing surface coating technology for positive electrode materials. This technology is necessary for the formation of optimal interfaces between positive electrode materials and solid electrolytes, which has a large impact on the battery properties of all solid-state batteries.