Detection and Analysis of SEI Film Decomposition Signal in Lithium-ion Batteries Based on DRT Method

This research aims to identify the characteristic signals of the SEI (Solid Electrolyte Interphase) membrane. The assembled button batteries were used for the experiments, with impedance testing and DRT (Distribution of Relaxation Times) fitting methods being employed. Through the identification of the impedance characteristics of both half-cells and symmetric cells, combined with literature review, an in-depth analysis of the DRT fitting results was conducted. Eventually, the kinetic processes corresponding to the five peaks in the DRT fitting results were successfully determined, thereby clarifying the characteristic signals of the SEI membrane. This achievement provides crucial evidence for understanding the properties of the SEI membrane in button batteries and the related electrochemical mechanisms, and holds certain reference significance for subsequent research such as battery performance optimization and battery thermal runaway.