Enabling Fast and Stable Zinc-Ion Storage in Vanadyl Phosphate Cathodes.

Liu, Xuelian; Zong, Quan; Chen, Keyi; Zhang, Qilong; Liu, Chaofeng; Zhu, Zejie; Cao, Guozhong · Nano Lett · 2025

basic_science · Level V

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Abstract

VOPO<sub>4</sub>·2H<sub>2</sub>O (VOP) has attracted significant attention as a cathode material for aqueous zinc-ion batteries owing to its layered structure and high-voltage plateau. However, its application is hindered by sluggish Zn<sup>2+</sup> transport kinetics and instability in aqueous electrolytes, leading to rapid capacity fading over cycling. In the present work, a diethylene glycol (DEG) pre-intercalated VOP (DEG-VOP) with flower-like morphology is prepared by a facile hydrothermal method. The DEG molecules enlarge the interplanar lattice of the (001) plane and introduce oxygen vacancies, accelerating the mass and charge transfer kinetics. In addition, the pre-intercalation induces the self-assembly of nanosheets into a flower-like structure, which exposes more (201) planes, providing additional ion channels. The pre-intercalation of DEG also enhances the hydrophobicity of VOP, effectively suppressing its decomposition and dissolution. These result in a significantly improved discharge capacity, with a capacity retention of 86% after 2000 cycles at 1 A g<sup>-1</sup>.