Near-surface reconstruction at interface of composite cathode through flash lamp annealing for all-solid-state batteries

Abstract

All-solid-state batteries (ASSBs) have emerged as a next-generation battery system due to their high energy density and safety compared to conventional lithium-ion batteries (LIBs). However, interfacial incompatibility between cathode active materials (CAMs) and sulfide-based solid electrolytes (SEs) hinders fast Li-ion transport and stable cycle performance in ASSBs, forming a resistive cathode electrolyte interphase (CEI) layer. In this study, we demonstrate that an interface modification of composite cathodes using flash lamp annealing (FLA) in an energy- and time-efficient manner. FLA enables the formation of a stable CEI layer by reactions between residual Li compounds of CAMs and SEs. The stable CEI layer has Li-ion conducting and electronically insulating properties, increasing charge transfer kinetics and preventing interfacial side reactions at the cathode/solid electrolyte interface. With those synergetic advantages, the LiNi0.9Co0.05Mn0.05O2 (NCM) electrode with a stable CEI layer demonstrates a 28 % enhanced cycle performance with diminished interphase evolution over 300 cycles at a 0.2C rate, compared to the pristine NCM electrode. This study provides insights into the design of practical composite cathodes for achieving enhanced interfacial stability in ASSBs.