Fast and efficient in-situ construction of low crystalline PEDOT-intercalated V2O5 nanosheets for high-performance zinc-ion battery

Abstract

Layered vanadium oxides have recently emerged as ideal cathode materials for aqueous zinc-ion batteries (ZIBs) due to their high theoretical capacity and low cost. However, their inherent shortages of narrow interlayer distance and poor electric conductivity cause sluggish reaction kinetics and low structure stability, leading to battery performance deterioration. Herein, we developed a novel strategy to simultaneously realize the intercalation of conductive polymer into V2O5 polyhedrons and exfoliation of the V2O5 into ultrathin nanosheets. The strategy is realized by in-situ polymerization of 3,4-ethylene-dioxythiophene (EDOT) monomers in the interlayer of the V2O5 polyhedrons that were derived from the annealing of vanadium-based metal–organic frameworks (MIL-100(V)) in air. The MIL-100-derived V2O5 polyhedrons assembled into porous microspheres (PVO) with abundant porosity and small particle size, which facilitates the penetration of EDOT molecules into the interior of the PVO during in-situ intercalation and polymerization processes, ultimately leading to the V2O5 polyhedrons exfoliating into ultrathin nanosheets. The uniform poly(3,4-ethylene-dioxythiophene) (PEDOT) layer and abundant oxygen vacancies in PVO@PEDOT nanosheets can accelerate the diffusion of electrons and zinc ions, which are evidenced by dynamic analysis, ex-situ characterizations, and density functional theory (DFT) calculations, revealing the synergetic effect of PEDOT and oxygen vacancies. Therefore, the PVO@PEDOT cathode exhibits high specific capacity (403.7 mAh g-1 at 0.2 A g-1), superior rate capability (312.8 mAh g-1 at 10 A g-1), and long-term stability (92.8% of the initial capacity remained after 3000 cycles), which is superior to the majority of ion intercalation improved V2O5.