Facile synthesis of monoclinic (NH4)2V4O9 nanosheets for zinc-ion batteries

Aqueous zinc-ion batteries (ZIBs) are increasingly popular due to their low cost and high safety. However, the quest for cathode materials with robust internal structures and efficient ion transport pathways remains critical. In this study, we introduce a simple hydrothermal method to synthesize monoclinic (NH₄)₂V₄O₉ nanosheets, serving as a advanced cathode for ZIBs. This material demonstrates outstanding electrochemical properties, with a high specific capacity of 389 mAh g⁻¹ at 0.1 A g⁻¹, and retains 78.9 % capacity after 3000 cycles at 1 A g⁻¹ and 77.3 % after 15,000 cycles at 5 A g⁻¹. Additionally, it achieves an energy density of 325 Wh kg⁻¹ at 101 W kg⁻¹. In-depth electrochemical analysis reveals the structural stability during reversible Zn²⁺ ion intercalation/de-intercalation, underscoring the potential of (NH₄)₂V₄O₉ as a high-performance material for ZIBs.