Sodium ion intercalated NH4V4O10 with adjustable interlayer-spacing as an advanced cathode for aqueous zinc ion battery

Ammonium vanadate has increasingly been the focus of attention in the field of aqueous zinc ion battery due to its high theoretical specific capacity. However, they suffer from slow kinetics and loss of capacity due to irreversible deamidation. Herein, we fabricated a series of Na⁺-intercalating NH₄V₄O₁₀ (SNVO) with lamellar structure via a simple one-step hydrothermal method, in which SNVO30 exhibited high capacity and satisfactory rate performance in the storage process for Zn²⁺. Sodium alginate had a role in the modulation of microstructures during the synthesis, which improved the contact area between the cathode and the electrolyte. It was found that Na⁺ increased the interlayer spacing, and served as a “pillar” between the VO layers to reinforce the SNVO during the cycling process, thereby enhancing its stability and accelerating reaction kinetics. The generation of additional oxygen vacancies facilitated an alteration in the electronic structure and enhanced the Zn²⁺ diffusion capacity. Specifically, the SNVO30 exhibited high initial specific capacity of 447.2 mAh g⁻¹ at 2.0 A g⁻¹. And a specific capacity of 228.3 mAh g⁻¹ was maintained after 1500 cycles at 10 A g⁻¹. This work provides a reference for the development of high-performance aqueous zinc ion battery cathode materials.