Construction of high-performance aqueous zinc-ion batteries by guest pre-intercalation MnO2-based cathodes

In recent years, aqueous zinc ion batteries (AZIBs) with the benefits of high safety, low cost, high capacity and environmental protection, have broad development prospects in the area of massive energy storage. Among them, MnO2 materials are seen to be the most prospective cathode materials because of their low manufacturing costs, high operating voltage, and multi-valence state. Nevertheless, issues with low intrinsic conductivity, quick structural collapse and poor stability of MnO2 cathode materials during the charge/discharge process severely impede the development of AZIBs. Numerous investigations have demonstrated that the guest pre-intercalation MnO2 cathode structures can effectively alleviate the above problems and improve their electrochemical performance. Thus, this review summarizes the research progress of the guest pre-intercalation strategy applied to different Mn-based oxide cathode materials, focusing on alpha-MnO2, (1-MnO2, e-MnO2, S-MnO2, and gamma-MnO2. Meanwhile, the mechanism of performance improvement and electronic structure alteration of guest preintercalation in MnO2 cathode materials with different crystal structures are analyzed in detail. Finally, the challenges faced by this strategy and its development are summarized, and the future development direction of Mn-based cathode materials for high-performance AZIBs is prospected. The review describes the guest preintercalation strategy that promotes the commercialization and practical application of AZIBs, providing strong support for the development of renewable energy storage.