Modified cathode-electrolyte interphase toward high-performance batteries

A stable and uniform cathode-electrolyte interphase (CEI) is extremely important for rechargeable batteries with high energy densities and long life cycles. The CEI greatly influences the electrochemical reactions at the interphase while stabilizing the cathode's structure. Because of the complexity of the interfacial reaction, an overall picture of CEI evolution and effective analysis methods is absent in the field. Herein, the formation and evolution mechanism of the CEI in rechargeable batteries are reviewed based on the CEI studies. Diverse advanced characterization methods for the interfacial reaction are also summarized. Subsequently, modified strategies to enhance the stability of the CEI are introduced, such as CEI-forming additives in electrolytes, localized high-concentration electrolytes, artificial CEIs, and solid-state electrolyte engineering. Finally, challenges and future directions for the CEI are proposed. We hope this review sheds light on future research on CEI layers.