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.

High-voltage high-nickel lithium layered oxide cathodes have garnered extensive research interest and commercial adoption owing to their exceptional energy density. Unfortunately, the deep oxidation–reduction reaction caused by high-voltage high-nickel will produce a quantity of highly active and unstable Ni⁴⁺, which will aggravate interface side reactions such as oxygen evolution, phase transition, and electrolyte decomposition, thereby increasing interface impedance and reducing battery performance. Here, an H₂/Ar reducing atmosphere is used to form a thin rock salt passivation layer on the surface of LiNi_0.6Co_0.2Mn_0.2O₂ (NCM622) high-nickel cathode materials. The time-of-flight secondary ion mass spectrometry (TOF-SIMS) results indicate that electrolyte decomposition and metal ions dissolution are restrained. The battery in-situ differential electrochemical mass spectrometry (DEMS) results display that the production of CO₂ and O₂ gases is repressed. The density functional theory (DFT) calculation results also confirm that the interface lattice oxygen loss is suppressed. These results fully demonstrate that the surface passivation strategy greatly improves the electrode–electrolyte interface stability. At a high voltage of 4.5 V, the surface passivated NCM622 exhibits superior cycling stability (capacity retention rate for 100 cycles: 92.2% vs. 85.0%) and rate performance (output specific capacity at 5 C high current density: 148 mAh·g⁻¹ vs. 127 mAh·g⁻¹) compared to the pristine NCM622. Consequently, the surface passivation strategy treated with reducing substances is recommended to improve the electrode–electrolyte interface stability and further enhance the lithium storage performance of high-voltage high-nickel layered oxide cathodes.