Stabilization of cathode electrolyte interphase for aqueous zinc-ion batteries

Aqueous zinc-ion battery systems are attractive for next-generation energy storage devices, however, the unstable electrode electrolyte interphase, especially cathode electrolyte interphase (CEI), has induced rapid capacity attenuation, insufficient cycle life, and severe safety issues. Evolving the researching of CEI formation, composition, dynamic structure, and reaction mechanisms would help in understanding the fundamental electrochemistry at CEI such as electron and ion transport processes, further strengthening the specific capacity, rate, and cycle performance of the cathode materials. In this review, we summarized the latest progress in understanding interfacial reaction mechanisms and ion dynamic behavior, emphasizing the impact of surface-specific adsorption and solvation behaviors on the interface's ultimate structure and chemical composition. Subsequently, the significant challenges that persist in CEI formation mechanisms, such as cathodic dissolution, by-product formation, electrostatic interactions, constrained electrochemical windows, oxygen evolution reaction, overpotentials, phase transitions, and additional factors, were discussed. These challenges are explored to identify triggers contributing to the depletion of active materials and alterations in the composition or state of the CEI. Ultimately, with a deep comprehension of interfacial behaviors, the review articulates innovative optimization strategies through a detailed categorization of approaches in electrolyte engineering, cathode engineering, and artificial CEI development. Furthermore, future challenges and development directions of CEI are presented. We hope to offer insights for constructing robust CEI films to achieve high performance aqueous zinc-ion batteries.