Methylsulfonylmethane-Regulated Hybrid Electrolyte for Stable Zn Anode and Suppressed Mn Dissolution

Aqueous Zn-LiMn₂O₄ hybrid-ion batteries are promising for large-scale energy storage due to their high energy density, environmental friendliness, and low cost. However, conventional aqueous electrolytes suffer from two critical challenges: zinc anode side reactions and manganese dissolution from the LiMn₂O₄ cathode. To address these issues, a novel hybrid electrolyte regulated by a methylsulfonylmethane (MSM) additive is introduced. This electrolyte effectively suppresses zinc dendrite growth by promoting uniform Zn²⁺ deposition. Additionally, the modified Zn²⁺ solvation structure, with reduced water coordination, mitigates hydrogen evolution, interfacial corrosion, and by-product formation. As a result, Zn||Zn symmetric cells exhibit stable zinc plating/stripping for over 1600 h. Furthermore, MSM disrupts the tight hydrogen bonding network of the hybrid electrolyte, lowering viscosity and enhancing ion mobility, which reduces voltage polarization and improves the rate capability of Zn-LiMn₂O₄ cells. Moreover, the hybrid electrolyte stabilizes the cathode structure by inhibiting manganese disproportionation at high voltages, attributed to an increased oxygen evolution reaction overpotential and the formation of an in situ cathode-electrolyte interphase. Consequently, Zn-LiMn₂O₄ full cells achieve exceptional cycling stability, retaining 71.1% of their capacity after 800 cycles at 0.15 A g^-1.