In situ characterization of the electrolyte|electrode interface evolution in solid-state lithium batteries

The solid-state lithium battery (SSLB), in which the conventional liquid electrolyte is replaced by a solid-state electrolyte (SSE), is one of the most promising energy storage systems that may simultaneously exhibit high safety and high energy density. While significant progress in SSEs has led to ionic conductivity and electrochemical window close to or even better than those of liquid electrolytes, poor interfacial stability between SSEs and electrodes during charging and discharging tends to deteriorate the cycle life of SSLBs, which calls for a deep understanding of the interface evolution. Here, we review recent efforts in investigating the electrical, chemical and mechanical evolutions at SSE|electrode interfaces during cycling with various in situ microscopy and spectroscopy techniques. These in situ characterizations reveal a correlation between the dynamic evolution of the electrical-chemical-mechanical coupling and the failure mechanism in SSLBs. This survey emphasizes the importance of in situ techniques in understanding the mechanism of lithium battery failure and providing guidelines in interfacial design.