Stabilization of the K0.43V2O5 cathode by Ca ions substituted engineering strategy for high performance potassium ion batteries
Zhiwang Liu, Zhenxiang Wang, Hongyan Li
Abstract
Potassium ion batteries (PIBs) have emerged as a powerful energy stockage device because of their ample potassium resources and inexpensive. Layered potassium vanadate K 0.43 V 2 O 5 has superior electrochemical properties as cathode material for PIBs. However, the K 0.43 V 2 O 5 still faces problems such as poor structural stability and multiplication performance. In this study, Ca 2+ ions were introduced into K 0.43 V 2 O 5 (denoted as Ca-KVO) and vacancies were created at the K site, thereby improving its electrochemical performance. Ex-situ XRD and HRTEM indicated that the strong interaction between Ca 2+ ions and O 2– ions significantly improved the structural stability of Ca-KVO. And the presence of vacancies also increases the diffusion rate of potassium ions. Specifically, it provides a favorable reversible capacity of 96.61 mAh g −1 at 10 mA g −1 as well as holds 96.4 % of the specific capacity after 2000 cycles at 1 A g −1 . Furthermore, the Ca-KVO//Graphite full cell achieves a favorable discharge capacity of 94.46 mAh g −1 . Moreover, its energy density reaches 191.3 Wh kg −1 in 20.25 W kg −1 ，which shows that Ca-KVO can be applied well to PIBs. This study shows that calcium doping is an effective strategy, which is expected to provide new ideas for the exploration of high-performance PIBs.