Spontaneous Growth of Alkali Metal Ion-Preintercalated Vanadium Pentoxide for High-Performance Aqueous Zinc-Ion Batteries

Abstract

Rechargeable aqueous zinc-ion batteries (ZIBs) have drawn intense attention for large-scale energy storage because of their intrinsic safety, low cost, and high energy intensity. However, it is difficult to find suitable cathode materials with excellent Zn²⁺ storage cyclability due to the strong electrostatic interaction of divalent Zn²⁺ with cathode material frameworks. Herein, a series of preintercalated nanostructure vanadium-based oxides with alkali metal ions (Li⁺, Na⁺, and K⁺) are prepared via a simple spontaneous growth method under ambient conditions. In the synthesis process, the electronegativity of alkali metal ions plays a key role in the intercalated nanostructure evolution, preintercalated vanadium-based oxide synthesis rate, targeted product morphology, etc. Furthermore, the subsequent modification of the appropriate calcination temperature is favorable for tuning the amorphous structure of the electrode to achieve the outstanding Zn-storage performances. The alkali metal ions between the layers can not only ameliorate the stability of the vanadium oxide structure, but also achieve high ion diffusion ability by enlarging the interlayer spacing and enhancing the electrical conductivity. For instance, the Na⁺ preintercalated V₂O₅ cathode exhibits high capacity retention of 96.4% after 100 cycles at 0.5 A g–¹ and an excellent capacity of 153 mAh g–¹ at 20 A g–¹. Meanwhile, the cointercalation mechanism of Zn²⁺ and protons has also been proven using the trifluoromethanesulfonic acid as the electrolyte. Furthermore, for the flexible quasi-solid-state battery with preintercalated vanadium-based oxide as the cathode, significant electrochemical performance could be observed after 150 cycles. This cost-effective and green large-scale synthesis process sheds light on the development and applications of ZIBs’ stationary grid storage.