Potassium Inserted V2O5.xH2o Nanorods As a High-Performance Cathode Materials for Cost Effective Aqueous Rechargeable Zinc-Ion Batteries

Abstract

Research attention in aqueous rechargeable zinc-ion batteries (ARZIBs) is growing immensely because of their low-cost and eco-friendly cell components. However, its challenging to find new cathode materials towards practical application of ARZIBs. In this contribution, ground-breaking work on the potassium-pillared V2O5.nH2O (K0.5V2O5.nH2O) nanorod with exposed layer structure as high-performance cathode for ARZIB is presented. The storage mechanism of the K0.5V2O5.nH2O cathode in ARZIB is systematically elucidated using a combined of in situ synchrotron X-ray diffraction, ex situ synchrotron X-ray absorption spectroscopy, ex situ TEM analyses, and first-principle calculations. The K0.5V2O5. nH2O cathode displays a notable discharge capacity of 439 mAh g−1 at a current density of 50 mA g−1. Furthermore, it recovers 96% of the capacity after 1500 cycles at 8000 mA g−1. Impressively, the Zn/K0.5V2O5.nH2O battery offers a specific energy of 121 Wh kg−1 at a high specific power of 6480 W kg−1. The superior performance of the cathode is attributed to its unique exposed layer structure with high surface energy, high conductivity, and low migration barrier. The zinc (Zn) insertion pathway into K0.5V2O5.nH2O was studied using density function theory (DFT). This study provides an insight for designing high-performance cathode materials for ARZIBs and other electrochemical systems.