Enhanced Reversible Zinc Ion Intercalation in Deficient Ammonium Vanadate for High-Performance Aqueous Zinc-Ion...

Ammonium vanadate with bronze structure (NH₄V₄O₁₀) is a promising cathode material for zinc-ion batteries due to its high specific capacity and low cost. However, the extraction of [Formula: see text] at a high voltage during charge/discharge processes leads to irreversible reaction and structure degradation. In this work, partial [Formula: see text] ions were pre-removed from NH₄V₄O₁₀ through heat treatment; NH₄V₄O₁₀ nanosheets were directly grown on carbon cloth through hydrothermal method. Deficient NH₄V₄O₁₀ (denoted as NVO), with enlarged interlayer spacing, facilitated fast zinc ions transport and high storage capacity and ensured the highly reversible electrochemical reaction and the good stability of layered structure. The NVO nanosheets delivered a high specific capacity of 457 mAh g^-1 at a current density of 100 mA g^-1 and a capacity retention of 81% over 1000 cycles at 2 A g^-1. The initial Coulombic efficiency of NVO could reach up to 97% compared to 85% of NH₄V₄O₁₀ and maintain almost 100% during cycling, indicating the high reaction reversibility in NVO electrode.