Fabrication of New Quaternary Buffer Layer by Atomic Layer Deposition for All-Solid-State-Batteries

Abstract

The importance of eco-friendly technology has emerged as a result of resource depletion and environmental pollution, prompting active research on lithium secondary batteries. However, because lithium secondary batteries with liquid electrolytes have stability issues, such as the risk of explosion, all-solid-state batteries with solid electrolytes are being touted as next-generation batteries. One of the issues to be resolved for the commercialization of solid-state batteries is the problems at the interface between the cathode active material and the electrolyte. This is because secondary phase formation caused by a side reaction at an interface between an active material and a solid electrolyte, as well as high interface resistance caused by contact loss, have a negative impact on performance. As a result, research is conducted to suppress side reactions by coating a chemically stable buffer layer on a cathode active material. Ternary materials such as lithium zirconate, lithium titanate, and lithium phosphate have been widely studied. However, in this study, a never-before-studied quaternary material of Li-Ti-Zn-O was chosen as a new buffer layer material and its electrochemical properties were evaluated. Furthermore, a nano-scale thin film was obtained using the atomic layer deposition method rather than the non-vacuum method that has been primarily used to deposit the buffer layer.