Polar Organic Molecules Inserted in Vanadium Oxide with Enhanced Reaction Kinetics for Promoting Aqueous Zinc‐Ion Storage

Abstract

AbstractThe Zn2+ sluggish kinetics resulting from high desolvation barriers of Zn(H2O)62+ in the electrode/electrolyte interface restricts the practical application of Zn‐ion batteries (ZIBs). Herein, ethylene glycol (EG) molecules are inserted into V2O5·3H2O to form V‐EG nanoarray structures to improve the Zn2+ diffusion rate. Unlike most efforts focused on improving interlayer spacing and structural stability, the influence of EG on the Zn2+ desolvation and Zn2+ storage process are the main goals. Based on experimental and theoretical analysis, EG molecules are confirmed to participate in the reshaping of V2O5·3H2O morphology and Zn2+ solvation structure, which is beneficial to enhance the reaction kinetics and specific capacity. The polar group of the EG molecule leads it anchored in the VO skeleton and decreases the desolvation energy, while the steric hindrance of the low polarity group liberalizes Zn2+ transfer reversibly in the VO skeleton. Therefore, V‐EG delivers a higher ion diffusion coefficient and lower kinetic barrier. As expected, V‐EG exhibits a high specific capacity of 553 mA h g−1 at 0.3 A g−1 and a long cycle life of 10 000 cycles at 20 A g−1. This work provides a strategy to decrease the desolvation energy of Zn2+ in the interface of cathode materials toward advanced ZIBs.