Polyaniline-Intercalated Vanadium Dioxide Nanoflakes for High-Performance Aqueous Zinc Ion Batteries

Aqueous zinc ion batteries (ZIBs) are highly desired as potential alternatives for rechargeable batteries owning to their low cost, safety, and environmentally friendly features. However, cathode materials in ZIBs deliver poor electrochemical performance in power density, rate capability, and cycling stability, being major limitations for the grid-scale applications. Herein, vanadium dioxides with polyaniline (PANI) intercalation were fabricated for the first time. Layered PANI-intercalated VO2(L-PANI-VO2) cathode with an enlarged layer spacing of 10.2 Å delivered a specific capacity of 415 mA h g–1 and maintained 280 mA h g–1 after 50 cycles at a current density of 0.1 Ag–1. The L-PANI-VO2 cathode exhibited good rate capability and gained a remaining capacity of 173 mA h g–1 after 1000 cycles at a current density of 2.0 Ag–1. The dynamics of Zn2+ ions and phase structure evolution during the charge and discharge process were investigated by X-ray diffraction and X-ray photoelectron spectroscopy, respectively. Our study revealed that the intercalated PANI could provide strong charge screening effect to Zn2+ ion insertion/extraction and enhance the electrochemical performance of the L-PANI-VO2 cathode. In addition, the unexpected Zn3(OH)2V2O7(H2O)2 precipitates formed both in charge and discharge processes are found to induce the decay of the as-prepared ZIBs.