K0.23V2O5 as a promising cathode material for rechargeable aqueous zinc ion batteries with excellent performance

Aqueous zinc ion battery is a new type of rechargeable battery developed in recent years, which have received extra attention due to the lower cost, higher safety, and more environmentally friendly. However, developing the suitable cathode materials for the insertion/extraction of Zn 2+ is still major challenge for aqueous zinc ion batteries as the strong electrostatic interaction between multivalent metal ions and host cathodes. In this work, a potassium vanadium oxide (K 0.23 V 2 O 5 ) with tunnel structure has been prepared by hydrothermal synthesis and is firstly employed as cathode material for aqueous zinc ion batteries, which delivers an excellent structural stability and high capacity retention rate of 92.8% (103 mA h g −1 ) after 500 cycles at current density of 2.0 A g −1 . In addition, the ion diffusion rate is as high as 1.88 × 10 −9 −2.6 × 10 −8  cm 2  S −1 , which is much higher than most other cathode materials for aqueous zinc ion batteries. The outstanding performances demonstrate that K 0.23 V 2 O 5 is a promising cathode for aqueous zinc ion batteries.