In Situ Observation of Interface Evolution on a Graphite Anode by Scanning Electrochemical Microscopy

A well-formed solid electrolyte interface (SEI) is critical for achieving long-term cycling stability in lithium-ion batteries (LIBs). However, the SEI remains the poorly understood component in LIBs especially under dynamic conditions. Here, scanning electrochemical microscopy (SECM) was applied to study the spontaneous reaction on a graphite electrode, SEI formation in the first cycle, SEI evolution during 10 cycles, and the stability of the as-formed SEI in the electrolyte. The conversion, dissolution, stabilization, and growth behaviors of the SEI were determined. Moreover, the SECM results were analyzed in combination with ex situ material characterization to understand the SEI on the graphite electrode comprehensively.