Cathode/Electrolyte Interfacial Engineering by Pre‐Insertion Organic Guest for High‐Performance Vanadium‐Based Cathode

ABSTRACT Despite the high specific capacity of V‐based cathodes, their practical application in aqueous Zn‐ion batteries is often hindered by unstable electrode/electrolyte interfaces and irreversible cathode dissolution. Herein, we propose a facile strategy involving the pre‐insertion of propylene glycol (PG) into the V 2 O 5 framework (denoted as V‐PG) to construct an in situ ZnS‐rich cathode‐electrolyte interface (CEI), conceptually derived from the protective solid‐electrolyte interface (SEI) on anodes. Notably, the electrically neutral PG with reducing properties facilitates electrolyte decomposition; together with the localized weakly reductive environment in V‐PG, this promotes the reduction of SO 4 2− to S 2− and the formation of ZnS‐rich CEI. Experimental and theoretical calculations further demonstrate that the zincophilic nature of ZnS‐rich CEI, combined with PG insertion, not only accelerates ion transport kinetics but also inhibits cathode dissolution, as evidenced by rapid ion diffusion kinetics (10 −8 cm 2 s −1 ), and enhanced cycle stability (retaining 86.9% capacity after 300 cycles at 1 A g −1 ). This work not only reports a general strategy to construct the CEI layer for suppressing V‐based cathode dissolution but also provides new insights for designing stable/functional CEIs by adapting an effective SEI concept to cathode materials.