Electrochemical Activation of Manganese‐Based Cathode in Aqueous Zinc‐Ion Electrolyte

Low‐cost and highly safe zinc‐manganese batteries are expected for practical energy storage and grid‐scale application. The electrolyte adjustment is further combined to boost their performance output; however, the mechanism behind the electrochemical contrast caused by electrolyte composition remains unclear, which has held back the development of these systems. Hence, new insight into the electrochemical activation of manganese‐based cathodes, which is induced by the aqueous zinc‐ion electrolyte, is provided. The relationship between the desolvation of Zn2+ from [Zn(OH2)6]2+‐solvation shell and the electrolyte/electrode interfacial reaction to form Zn4SO4(OH)6·4H2O phase or its analogues is established, which is the key for the electrochemical activation. Further electrolyte optimization promotes the cycling stability of Zn/LiMn2O4 battery with a long life span over 2000 cycles. This work illuminates the confused direction in exploring electrolyte for zinc‐manganese batteries. It is demonstrated that the electrochemical activation of manganese‐based cathodes can be induced only in the aqueous electrolyte but not in the waterless electrolyte. Both experimental and theoretical analyses indicate that the activated reaction is related to form a Zn4SO4(OH)6·4H2O phase or its analogues on the surface of the electrode in aqueous media.