Coupling Fast Zn2+ Kinetics With V-O Framework Stabilization via Nitrogen-Rich Interfacial Engineering of Spinel ZnV2O4.

Abstract

Aqueous zinc-ion batteries (AZIBs) offer intrinsic safety and cost advantages, yet spinel zinc vanadate cathodes remain limited by sluggish interfacial Zn2+ storage kinetics, polarization, and structural degradation. Herein, graphitic carbon nitride (GCN) is employed as a nitrogen-rich interfacial regulator (NIR) to construct NIR-integrated spinel ZnV2O4 (ZVO) cathodes (GZVO) through ultrasonication-assisted physical integration. The GCN-derived NIR provides polar N sites and regulated interfacial association with ZVO, promoting interfacial Zn2+ adsorption/migration and charge transfer while mitigating local framework distortion. The optimized GZVO-7 wt.% cathode delivers 405 mAh g-1 after 150 cycles at 0.5 A g-1, retains 258.93 mAh g-1 at 10 A g-1, and maintains 218.24 mAh g-1 after 3000 cycles at 5 A g-1. Cyclic voltammetry (CV), in situ electrochemical impedance spectroscopy-distribution of relaxation times (EIS-DRT), and galvanostatic intermittent titration technique (GITT) reveal enhanced pseudocapacitive contribution, reduced polarization, and reversible Zn2+ storage. Ex situ x-ray diffraction (XRD) and x-ray photoelectron spectroscopy (XPS) reveal persistence and partial recovery of ZVO-derived crystalline domains together with surface V5+/V4+ redox evolution, oxygen-environment modulation, and N-site-mediated Zn2+ interfacial regulation. Density functional theory (DFT) verifies favorable surface Zn-removal energetics and reinforced V─O bonding. This work establishes NIR as an effective strategy for durable, high-rate vanadate cathodes in AZIBs.

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