Coupling Water‐Driven Amorphization With High Entropy Strategy in Vanadium Oxide Cathodes for High‐Capacity and Durable Aqueous Potassium‐Ion Batteries

ABSTRACT

Aqueous potassium‐ion batteries (APIBs) have emerged as compelling candidates for large‐scale energy storage owing to their intrinsic safety, cost‐effectiveness, and rapid ion‐transport kinetics. However, developing viable cathodes remains critical bottlenecks due to the severe lattice strain induced by the large K ⁺ radius and the poorly understood erosive impact of water molecules on electrode stability. Herein, we systematically investigate the cycling mechanism of crystalline V ₂ O ₅ to reveal the role of active water, demonstrating that water acts as “chemical scissors” to drive a crystal‐to‐amorphous transition that enhances capacity but structural stability remains compromised. Utilizing a “mechanism‐guided design” strategy, we synthesize a high‐entropy doped amorphous vanadium oxide (HE‐AVO) cathode. The resulting HE‐AVO cathode achieves a high specific capacity of 110.4 mAh·g ⁻¹ and exceptional cycling life, maintaining 97.3% capacity retention over 30 000 cycles at 5 A·g ⁻¹ . In‐situ spectroscopic characterizations and ex‐situ time‐of‐flight secondary ion mass spectrometry confirm that high‐entropy strategy suppresses vanadium dissolution and preserves a robust disordered network. Theoretical calculations demonstrate that this strategy strengthens V─O bonds, enhances electrical conductivity, and lowers the K ⁺ diffusion barrier. This study clarifies the water‐mediated amorphization mechanism and establishes a viable pathway for utilizing high‐entropy strategies to design durable, high‐rate electrodes for advanced aqueous batteries.