Manganese charge redistribution induced by high-entropy charge compensation mechanism for aqueous potassium-ion batteries

In aqueous batteries, Mn-based electrodes suffer from uncontrollable dissolution and Jahn-Teller distortion caused by the formation of Mn3+ during the charging process, resulting in poor cycling stability. Herein, the high-entropy charge compensation mechanism is applied to Mn-based cathode to induce manganese charge redistribution during charge/discharge process. Experimental characterization proves that Mn2+ in cathode has not been oxidized to the conventional Mn3+ upon charging but is in the valence state between +2 and +3 through the high-entropy charge compensation mechanism, while the suppressed Jahn-Teller distortion leads to a solid-solution reaction. Furthermore, the theoretical calculations reveal the robust and insoluble structure of the electrode and the fast K-ion diffusion in the crystal structure. With these advantages, the high-entropy cathode exhibits outstanding cycling performance over 2000 cycles in diluent electrolyte. This work provides a new strategy for Mn-based electrodes in aqueous batteries, which undergo dissolution and Jahn-Teller distortion.