Continuous Particle Level Operando Observation of a Composite Graphite - SiOx Electrode in a Liquid Electrolyte Using Scanning Electron Microscopy

Abstract Among anode materials for next-generation lithium-ion batteries, silicon derivatives play a key role, but their main degradation mechanisms were not yet observed in real-time. In this work, the microstructural evolution of a composite graphite - SiO x electrode was examined operando using an ionic liquid electrolyte and scanning electron microscopy during tenfold constant current application. On the electrode level, significant particle movement with large local strains that may result from binder damage or particle - binder interface cracking was observed. Novel continuous operando observation on particle level of the composite electrode in a liquid electrolyte was realized. On the particle level, irreversible deformation occurred but no indication for cracking was found. The focus of this article lies on the detailed presentation and discussion of the operando method and the used sample holder as well as the reliability and the interpretation of the combined microscopic and electrochemical data.