Fully Exploited Trimethylsulfoxonium Iodide for Simultaneous Resolution of Manganese‐based Oxide Cathode and Zn Anode Challenges in Zinc–Manganese Batteries

Abstract The lattice structure perturbation and localized Jahn‐Teller distortion for manganese‐based cathodes during the Zn 2+ intercalation process and low reversibility of Zn anodes result in many issues, including structural collapse and active material dissolution for cathodes and premature failure for Zn anodes, which seriously exacerbate the cycling stability of zinc‐manganese batteries. Herein, this work demonstrates that these issues can be simultaneously tackled by using trimethylsulfoxonium iodide additive. An in‐depth analysis demonstrates that ionized trimethylsulfoxonium cations enable an interfacial modification capability and trigger a chain effect (including electro‐reduction kinetics regulation, crystallographic optimization, and inorganic‐organic hybrid solid electrolyte interphase layer formation) after the electrostatic adsorption at the Zn anode surface for effectively solving the low reversibility of Zn anodes. Also, ionized I − anions with extended electroactive ability establish a redox pathway and raise a halogen‐involved electrochemically intensified cathode interface process, which enhances the electrochemical stability of manganese‐based cathode materials and is conducive to accelerating the multi‐electron transfer under high redox potential. Zn||Zn symmetric cells exhibit an ultra‐long cycle life of more than 3000 h. The optimized electrolyte enables the full cells to deliver a superior capacity of 448.0 mAh g −1 and an energy density of 608.7 Wh kg −1 with a long‐term stable life.