Long-life vanadium oxide cathode for zinc battery enabled by polypyrrole intercalation and concentrated electrolyte

Vanadium based oxides have gained extensive attention for cathode of Zn2+ batteries because of their open framework and high theoretical capacity. However, their cycle life is still restricted by vanadium dissolution, structure collapse and interface side reaction. Herein, we rationally designed conductive polypyrrole (PPy) intercalated V2O5 (PPy-V2O5) cathode material and 5m NaClO4 + 1m Zn(CF3SO3)2 electrolyte to address above issues at the same time. The introduced PPy can prevent structure collapse, while the 5m NaClO4 + 1m Zn(CF3SO3)2 electrolyte can inhibit the dissolution and interface side reaction of PPy-V2O5. Therefore, the Zn//PPy-V2O5 battery exerts a high reversible capacity of 450.6 mAh g−1 at 0.5 A g−1, and excellent capacity retention of 90.0% at 10 A g−1 after 8500 cycles. Remarkably, the modifications on both cathode and electrolyte bring great high and low-temperature performance, maintaining 90.9% capacity after 200 cycles at 0.2 A g−1 under −40 °C, and working smoothly and safely up to 120 °C.