In Situ Characterization of Competitive (De)Lithiation in Silicon/Graphite Composite Electrodes via Electrode Curvature Measurement

Abstract

In silicon/graphite (Si/Gr) composite electrodes for lithium-ion batteries, which have recently garnered significant attention, the competitive (de)lithiation between Si and Gr is recognized as crucial for understanding the internal electrochemical processes. In this work, an in-situ method to characterize this competitive behavior is proposed, utilizing a self-developed electrode curvature measurement system. After validating the parallel electrode configuration and the model battery, curvature measurements are simultaneously conducted on the parallel Si and Gr cantilevered electrodes throughout electrochemical cycling. Subsequently, by calibrating the correlation between capacity and curvature of the Gr electrode, the capacity evolution of Si and Gr within the Si/Gr electrode is determined, shedding light on the underlying competitive (de)lithiation behavior. During lithiation, the process transitions from “Si-dominant” to “Gr-dominant” and eventually reaching a “synchronous” stage. For delithiation, it moves from “Gr-dominant” to “Si-dominant”. The method proposed in this work, based on the measurement of macroscopic electrode deformation, offers a novel perspective for characterizing competitive (de)lithiation in electrodes with multiphase active materials.