Electrolyte exchange experiment in batteries: Failure analysis and prospect

Abstract

The solid electrolyte interphase (SEI) layer, formed on the electrode through electrolyte decomposition, has garnered significant attention over the past several decades. Numerous characterization studies have shown that the SEI enhances the stability of both the electrolyte and electrode, particularly by mitigating the well-known cation-solvent co-intercalation in graphite electrodes in lithium-ion batteries. However, recent electrolyte exchange experiments have revealed that variations in electrolyte solvation structure and the resulting desolvation behaviors play a more dominant role than the SEI in influencing electrolyte and electrode stability, which in turn critically impacts battery performance. In addition to contributing to the ongoing debate, electrolyte exchange experiments have proven to be a valuable tool for analyzing failures in electrolytes, electrodes, and batteries. This review highlights the application of electrolyte exchange experiments across various metal-ion batteries, incorporating diverse combinations of electrolytes and electrodes. It examines the influence of electrolyte solvation structures and desolvation behaviors on the stability of both electrolytes and electrodes. The aim is to enhance the methodology of electrolyte exchange experiments to deepen the understanding of the molecular interactions among metal ions, anions, and solvents within the electrolyte. This approach complements existing insights into SEI effects, providing a more thorough and accurate framework for battery failure analysis.