Ammonium intercalation engineering regulated structural stability of V6O13 cathodes for durable zinc ion batteries

Aqueous Zn-VO batteries have attracted more and more attention owing to their advantages of high capacity, low cost and stability. Nevertheless, the complex interaction between the inserted ions and the main lattice leading to structural instability, coupled with the interference of highly active free water, these factors lead to vanadium-based zinc batteries usually suffer from severe capacity attenuation. This work reports the optimization strategy of ammonium intercalation engineering to construct a robust V6O13 cathode with ammonium (V6O13-NH4+) for the stability of vanadium-based zinc batteries. Experiments and density functional theory (DFT) calculations illustrate that the ammonium intercalation could reduce the formation energy of VO-NH to improve cycling stability. The V6O13-NH4+ demonstrates high specific capacity (426.5 mAh g−1 capacity at 0.1 A/g) and high capacity retention rate (80.2 %) after 10,000 cycles at 10 A/g. A soft-packed Zn//VO-NH battery maintains a desired capacity of 252.8 mAh g−1 after 2000 cycles at 5 A/g. This work proves that the ammonium intercalation is an effective way to achieve highly cycle stable of Aqueous Zn-ion batteries.