Conformal and Nanoscale Poly(pyrrole) Coating on Li3VO4 Surface Enabling High Performance Lithium-Ion Batteries

Abstract

Lithium vanadium oxide (Li₃VO₄) shows great promise as an anode for high-efficiency Li-ion batteries (LIBs). However, its application is hindered by poor electronic conductivity and high charge transfer resistance caused by a thick and unstable solid electrolyte interface layer. A two-step approach aimed at improving the electrochemical performance of the LVO anode for high-rate and long-cycle LIBs is reported. This involves the hydrothermal synthesis of crystalline LVO, followed by a conformal coating of polypyrrole (Ppy) via vapor-phase polymerization. The conductive Ppy layer facilitates electron transport and enhances lithium-ion diffusion, mitigating the limitations of pristine LVO. Among the tested samples, [email protected] (0.5 indicates coating time in hours) exhibited the highest reversible capacity of 605 mAh g⁻¹, nearly three times that of pristine LVO with an initial Coulombic efficiency of 87% upon chemical prelithiation. The rate capability studies revealed stable performance, with 78% capacity retention over 500 cycles at 10C. Electrochemical impedance spectroscopy reveals that the [email protected] electrode exhibits high Li-ion diffusivity, reduced interfacial layer resistance, and enhanced charge transfer kinetics. Ex situ surface chemical analysis confirms the formation of a stable solid–electrolyte interphase layer on [email protected]. Conformal Ppy coating on LVO is a promising strategy for developing high-performance LIB anode.