Cu‐N Synergism Regulation to Enhance Anionic Redox Reversibility and Activity of Li‐ and Mn‐Rich Layered Oxides Cathode

Abstract Anionic redox chemistry enables extraordinary capacity for Li‐ and Mn‐rich layered oxides (LMROs) cathodes. Unfortunately, irreversible surface oxygen evolution evokes the pernicious phase transition, structural deterioration, and severe electrode‐electrolyte interface side reaction with element dissolution, resulting in fast capacity and voltage fading of LMROs during cycling and hindering its commercialization. Herein, a redox couple strategy is proposed by utilizing copper phthalocyanine (CuPc) to address the irreversibility of anionic redox. The Cu‐N synergistic effect of CuPc could not only inhibit surface oxygen evolution by reducing the peroxide ion O₂²⁻ back to lattice oxygen O²⁻, but also enhance the reaction activity and reversibility of anionic redox in bulk to achieve a higher capacity and cycling stability. Moreover, the CuPc strategy suppresses the interface side reaction and induces the forming of a uniform and robust LiF‐rich cathode electrolyte, interphase (CEI) to significantly eliminate transition metal dissolution. As a result, the CuPc‐enhanced LMRO cathode shows superb cycling performance with a capacity retention of 95.0% after 500 long‐term cycles. This study sheds light on the great effect of N‐based redox couple to regulate anionic redox behavior and promote the development of high energy density and high stability LMROs cathode.