Coupling Water-Driven Amorphization With High Entropy Strategy in Vanadium Oxide Cathodes for High-Capacity and...

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 V₂O₅ 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.