Initiator quenching induced spatial regulation of in-situ gelation enables gradient gel-liquid electrolyte for durable Zn-metal batteries

Gel electrolytes represent a promising alternative to liquid counterparts for mitigating free water-induced parasitic reactions at Zn metal anodes. However, the intrinsically sluggish ion transport within homogeneous gel networks severely impedes electrochemical kinetics. Herein, a novel gradient gel-liquid electrolyte (G-PAM) is proposed to reconcile interfacial stability with rapid ion transport. By introducing a Mn²⁺-rich coating on the cathode-facing side of the separator to locally quench persulfate initiators and inhibit polymerization, precise spatial control over the in-situ gelation of acrylamide monomers is realized, enabling selective gel formation at the anode side while preserving a liquid phase near the cathode. This functional graded electrolyte exhibits high ionic conductivity (2.52 × 10⁻² S·cm⁻¹) comparable to liquid electrolyte, ensuring fast charge transfer kinetics. Moreover, the amide-induced solvation restructuring favors the formation of a thin, stable N-rich solid electrolyte interphase (SEI), which enhances anodic interfacial stability and facilitates uniform Zn deposition. Consequently, ultra-stable Zn plating/stripping over 11,000 h is achieved. Zn||MnO₂ full cells exhibit excellent rate performance and long-term cycling stability with minimal capacity decay of only 0.011% per cycle. This in-situ spatial regulation strategy establishes a new paradigm for designing functionally graded electrolytes, paving the way toward practical, high-performance Zn-based batteries.