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Highlights Low pH value of electrolyte suppresses the charge capabilities of electrolytic Zn–Mn batteries. Unique solid phase alkaline properties of zinc sulfate hydroxide hydrate endow the electrolytic Zn–Mn batteries with greatly enhanced charge capabilities. The highly active Zn2Mn3O8·H2O nanorods array deposited during the charge process improve the discharge efficiency and stability of electrolytic Zn–Mn batteries.

Highlights: Low pH value of electrolyte suppresses the charge capabilities of electrolytic Zn–Mn batteries. Unique solid phase alkaline properties of zinc sulfate hydroxide hydrate endow the electrolytic Zn–Mn batteries with greatly enhanced charge capabilities. The highly active Zn2Mn3O8·H2O nanorods array deposited during the charge process improve the discharge efficiency and stability of electrolytic Zn–Mn batteries. Electrolytic aqueous zinc-manganese (Zn–Mn) batteries have the advantage of high discharge voltage and high capacity due to two-electron reactions. However, the pitfall of electrolytic Zn–Mn batteries is the sluggish deposition reaction kinetics of manganese oxide during the charge process and short cycle life. We show that, incorporating ZnO electrolyte additive can form a neutral and highly viscous gel-like electrolyte and render a new form of electrolytic Zn–Mn batteries with significantly improved charging capabilities. Specifically, the ZnO gel-like electrolyte activates the zinc sulfate hydroxide hydrate assisted Mn2+ deposition reaction and induces phase and structure change of the deposited manganese oxide (Zn2Mn3O8·H2O nanorods array), resulting in a significant enhancement of the charge capability and discharge efficiency. The charge capacity increases to 2.5 mAh cm−2 after 1 h constant-voltage charging at 2.0 V vs. Zn/Zn2+, and the capacity can retain for up to 2000 cycles with negligible attenuation. This research lays the foundation for the advancement of electrolytic Zn–Mn batteries with enhanced charging capability. [ABSTRACT FROM AUTHOR]