Mesoporous Mo2C/N-doped carbon heteronanowires as high-rate and long-life anode materials for Li-ion batteries

Abstract

Transition metal carbides are an emerging class of anode materials for Li-ion batteries (LIBs), which have recently drawn attention because of their good conductivity and high capacity after rational nano-engineering. In this work, we have developed Mo₂C/N-doped carbon mesoporous heteronanowires (Mo₂C/N–C MHNWs) with enhanced capacitive behaviour as high-performance anode materials for LIBs. With the heterostructure, the Mo₂C nanocrystallites offer short paths for Li⁺ diffusion, while the N-doped carbon matrix facilitates fast electron transportation and buffers the volume change of Mo₂C during the discharge/charge cycles. When evaluated as anodes for LIBs, the Mo₂C/N–C MHNWs exhibited high capacity and high rate capability, as well as a long-term cycle life. In particular, a reversible capacity of 744.6 mA h g⁻¹ was achieved in the first cycle, and 732.9 mA h g⁻¹ was preserved after 700 cycles at a current density of 2 A g⁻¹. The outstanding performance stems from fast kinetics enhanced by the pseudocapacitive effect, which was evidenced in the further analysis based on electrochemical impedance spectra and cyclic voltammetry. Our results elucidate the attractive Li⁺ storage performance of Mo₂C-based nanocomposites, which may shed some light on the development of high-performance materials for energy storage and utilization.