Nano-molybdenum oxide modified expanded graphite for high performance lithium-ion batteries

Abstract

Graphite anodes for lithium-ion batteries still face practical challenges, including the limitation of theoretical specific capacity and sluggish lithium-ion storage kinetics, which correspond to low energy density and unsatisfactory fast-charging performance. Nano-molybdenum oxide (nano-MoO₃), exhibiting a high theoretical specific capacity, high work function and excellent stability, represents a promising modification agent for graphite anodes to enhance electrochemical performance. Herein, this study developed nano-MoO₃ decorated within the bulk and surfaces of an expanded graphite anode material (nMO–EG). The reversible conversion reactions between nano-MoO₃ and lithium enhance the specific capacity of nMO–EG, achieving a high capacity of 701.9 mAh g⁻¹. A stable solid electrolyte interphase film, enriched with inorganic Li₂O and LiF, was formed on the surface of the nMO–EG anode, contributing to a reversible capacity of 613.8 mAh g⁻¹ and superior cycling stability over 600 cycles. The expanded layer of the nMO–EG anode exhibits a low lithium-ion diffusion energy barrier of 0.15 eV, which enhances its fast-charging capability that delivers a reversible specific capacity of 236.3 mAh g⁻¹ at 5 A g⁻¹. This study provides new insights into the stability of graphite modification and offers a promising alternative for high-energy-density and fast-charging graphite anode materials in lithium-ion batteries.