Inhibition of Vanadium Cathode Dissolution in Zinc Ion batteries Via Niobium Pillaring

Abstract

Vanadium (V)-based oxides are considered as promising cathodes for aqueous zinc ion batteries (AZIBs) due to their various oxidation states and crystal structures, whilst sluggish kinetics and severe V-dissolution lead to rapid capacity fading and unsatisfied cycle life. Herein, a niobium (Nb) pillaring coupling with polyethylene glycol assistance strategy (PNVO) that overcomes the limitation of inability of Nb-doped V-oxide separation, achieving Nb-pillaring effect and thus good structural stability, and enables abundant oxygen vacancy and enhanced kinetics, resulting in good rate performance, is described for the first time. This approach has resulted in high reversible capacity of 403 mAh g-1 and 244 mAh g-1 at 1 A g-1 and 10 A g-1, respectively, and remarkable cyclability with 68% capacity retention after 3000 cycles at 5 A g-1. Quantitative comparison of V-dissolution suggested PNVO-2 exhibited a low dissolution rate of 8.93%, while that for PVO and VO was 11.25% and 16.07%, respectively. These findings not only confirm the positive effect of Nb-pillaring on inhibition of V-dissolution, but also highlight the promising practical application of V-based cathodes for AZIBs.