Polyaniline-Intercalated\nVanadium Dioxide Nanoflakes\nfor High-Performance Aqueous Zinc Ion Batteries

Abstract

Aqueous\nzinc ion batteries (ZIBs) are highly desired as potential\nalternatives for rechargeable batteries owning to their low cost,\nsafety, and environmentally friendly features. However, cathode materials\nin ZIBs deliver poor electrochemical performance in power density,\nrate capability, and cycling stability, being major limitations for\nthe grid-scale applications. Herein, vanadium dioxides with polyaniline\n(PANI) intercalation were fabricated for the first time. Layered PANI-intercalated\nVO₂(L-PANI-VO₂) cathode with an enlarged layer\nspacing of 10.2 Å delivered a specific capacity of 415 mA h g^–1 and maintained 280 mA h g^–1 after\n50 cycles at a current density of 0.1 Ag^–1. The\nL-PANI-VO₂ cathode exhibited good rate capability and gained\na remaining capacity of 173 mA h g^–1 after 1000\ncycles at a current density of 2.0 Ag^–1. The dynamics\nof Zn²⁺ ions and phase structure evolution during the charge\nand discharge process were investigated by X-ray diffraction and X-ray\nphotoelectron spectroscopy, respectively. Our study revealed that\nthe intercalated PANI could provide strong charge screening effect\nto Zn²⁺ ion insertion/extraction and enhance the electrochemical\nperformance of the L-PANI-VO₂ cathode. In addition, the\nunexpected Zn₃(OH)₂V₂O₇(H₂O)₂ precipitates formed both in charge and\ndischarge processes are found to induce the decay of the as-prepared\nZIBs.