Spatial Confinement Effect of Mineral-Based Colloid Electrolyte Enables Stable Interface Reaction for Aqueous Zinc-Manganese Batteries

The rational design of inorganic colloid electrolytes enables the manipulation of the solvation structure of Zn2+ ions and addresses zinc dendrite formation and manganese dissolution in aqueous zinc-manganese batteries. In this study, magnesium aluminosilicate (MAS) powder is used to fabricate a mineral-based colloid electrolyte for Zn//alpha-MnO2 batteries. According to theoretical calculations, MAS has a stronger binding energy with Zn2+/Mn2+ ions than with H2O molecules, suggesting the possibility of regulating the solvation structure of Zn2+/Mn2+ ions in a MAS-colloid electrolyte. Based on the experimental results, a high ionic conductivity, wide operating voltage, low activation energy barrier, and stable pH environment is achieved in the MAS-colloid electrolyte. As expected, long-term cyclic stability can be maintained for 3500 h at 0.2 mA cm-2 in Zn//Zn cells, and high capacities of 255.5 and 239.8 mAh g-1 are retained at 0.2 and 0.5 A g-1 after 100 cycles in Zn//alpha-MnO2 batteries, respectively. This performance is attributed to the spatial confinement effect of MAS on the active H2O molecules, which effectively reshapes the solvation structure of Zn2+ ions, guaranteeing reversible zinc deposition, suppressing active manganese dissolution, and ensuring stable interfacial reactions. This work will drive the development of mineral-based electrolytes in zinc-based batteries.