Oxygen Vacancies on NH 4 V 4 O 10 Accelerate Ion and Charge Transfer in Aqueous Zinc-Ion Batteries.

Vanadium-based compounds are identified as promising cathode materials for aqueous zinc ion batteries due to their high specific capacity. However, the low intrinsic conductivity and sluggish Zn 2+ diffusion kinetics seriously impede their further practical application. Here, oxygen vacancies on NH 4 V 4 O 10 is reported as a high-performing cathode material for aqueous zinc ion batteries via a facile hydrothermal strategy. The introduction of oxygen vacancy accelerates the ion and charge transfer kinetics, reduces the diffusion barrier of zinc ions, and establishes a stable crystal structure during zinc ion (de-intercalation). As a result, the oxygen vacancy enriched NH 4 V 4 O 10 exhibits a high specific capacity of ≈499 mA h g -1 at 0.2 A g -1 , an excellent rate capability of 296 mA h g -1 at 10 A g -1 and the specific capacity cycling stability with 95.1% retention at 5 A g -1 for 4000 cycles, superior to the NVO sample (186.4 mAh g -1 at 5 A g -1 , 66% capacity retention).