Doped micro-silicon and vanadium carbide MXene composite as anode for high stability and high capacity Li-ion batteries

Abstract

The demand for high-energy lithium-ion batteries (LIBs) has been rising exponentially. Silicon (Si) is gaining increased attention and popularity as an anode material due to its high theoretical capacity (4200 mAhg−1, Li4.4Si) and ample abundance, but the huge volume expansion of Si restricts its use in practical applications. Herein, we propose a composite consisting of nitrogen (N) and phosphorus (P) doped micron Si/graphite with vanadium carbide (V2C) MXene, which effectively helps to buffer the mechanical stresses initiated by the volume expansion of Si. The lithium storage specific capacity of the composite is 2003 mAhg−1 (based on the weight of Si) after a long-term cycling of 500 cycles (1C rate) along with a good high rate performance. The improved performance of the composite electrode can be attributed to V2C as well as N/P doping, which significantly enhance the electron/ion conduction pathways. Also, low-cost micron Si can provide high tap density in practical applications where volumetric performance is desired. Thus, this work provides an approach to develop high-performance micron Si-based materials for LIBs.

Keywords

• Silicon anode
• Vanadium carbide
• MXene
• Graphite
• Phosphorus doping
• Nitrogen doping