Dual‐Affinity Interphase Engineering Enables Stable Aqueous Zn–S Batteries

Abstract

ABSTRACT Aqueous Zn–S batteries have garnered significant attention for grid‐scale storage but suffer from rapid capacity fade and sluggish reaction kinetics. Although existing strategies can improve redox reversibility, they fail to fundamentally address capacity attenuation arising from oxidation‐driven ZnS decomposition loss. In this study, a nano‐copper‐based cathode/electrolyte interphase (Cu CEI) featuring a unique sulfur/ZnS dual‐affinity is rationally designed to accelerate both S─S and Zn─S bond dynamics, effectively preventing ZnS accumulation and suppressing its decomposition via preferential Cu‐ZnS binding. Specifically, the strong binding affinity of the Cu CEI stabilizes ZnS by reducing its direct contact with interfacial water. Meanwhile, the strong interaction between Cu nanoparticles and S 8 activates ring‐opening and facilitates S─S bond cleavage, elevating the discharge voltage to 0.75 V. Cu‐mediated weakening of Zn─S bonds in ZnS synergistically lowers the apparent activation energy from 69.4 to 29.5 kJ mol −1 , establishing a robust interfacial redox pathway with a low voltage hysteresis of 0.23 V. Consequently, the Cu CEI enables Zn–S system with excellent cycling stability over 1000 cycles at 5 A g −1 and a high areal capacity of ∼6.5 mAh cm −2 over 200 h in a pouch cell, underscoring the practical feasibility of this dual‐affinity interphase design for high‐performance Zn–S batteries.