Intercalation-Coupled Zn²⁺ Transfer Enables Reversible ZnS Conversion in Aqueous Zn-S Batteries.

Abstract

Aqueous Zn-S batteries offer high safety and low cost, but sluggish ZnS reoxidation and cathode passivation limit capacity and efficiency. Herein, we report an intercalation-coupled redox catalysis strategy using manganese hexacyanoferrate (MnHCF) confined in polypyrrole (PPy) nanoreactors to mediate ZnS reoxidation. The reversible iron redox center in MnHCF couples with prezincation/deintercalation, creating a chemical potential gradient that drives Zn²⁺ from ZnS to MnHCF. This mechanism removes Zn²⁺ from the reaction front, enhancing Zn²⁺ mobility, reducing charge-transfer resistance, lowering the reactivation barrier, preventing passivation, and ensuring uniform conversion to S₈. The cathode delivers 1245 mAh g^-1 at 0.4 A g^-1 and 928 mAh g^-1 at 1 A g^-1 with an initial Coulombic efficiency of 99.983%, retaining 734 mAh g^-1 and 99.941% after 400 cycles. Practical pouch cells deliver 86 Wh kg^-1, and wearable microbatteries reach 563 μWh cm^-2. This work offers an effective catalytic strategy for high-energy, long-life Zn-S batteries.