Interface evolution of lithium metal anodes in all-solid-state batteries via mechanical–electrochemical investigations

Abstract

All-solid-state Li metal batteries (ASSLMBs) have garnered attention owing to the high-energy density and low redox potential of Li metal anodes. However, the practical applications of ASSLMBs are hindered by issues such as the volume effect of Li anodes and Li dendrite growth. In this study, a combined method of stacking pressure analysis, interface morphology observation, and electrochemical impedance spectroscopy was used to investigate the electrochemical failure of Li symmetric batteries based on the Li6PS5Cl electrolyte at areal capacities of 0.5, 1, and 3 mAh cm−2. The results indicated that ASSLMBs with areal capacities >1 mAh cm−2 exhibited a continuous decrease in the stacking pressure. As Li dendrites/dead Li and pores/cracks increased, stacking pressure variations of >0.1 MPa per cycle and a stacking pressure change rate > 0.2 MPa h−1 were observed, indicating impending battery failure owing to interface detachment. These findings provide new insights into the interface evolution of Li anodes of ASSLMBs and emphasize the importance of electrochemical–mechanical measurements in studying Li anode interfaces of ASSLMBs.