Few-layer V2C/MWCNT with high ionic accessibility for lithium-ion storage

Abstract

A V₂C MXene has a high theoretical capacity and low diffusion barrier, showing tremendous potential in lithium-ion batteries. However, most reports on V₂C focus on a multilayered structure that is stacked, which diminishes the ionic accessibility and results in unsatisfactory cycling stability. Therefore, we synthesized a few-layer V₂C (f-V₂C) material and added multi-walled carbon nanotubes (MWCNTs). The formed f-V₂C/MWCNT provides abundant pores, which enhance ionic accessibility, so that Li⁺ can easily enter the layer space. The introduction of MWCNTs can further separate the f-V₂C, expand the specific surface area, reduce the charge transfer resistance, and heighten the structural stability. The experiments reveal that f-V₂C/MWCNT has a high specific capacity of 531 mA h g⁻¹ at 0.1 A g⁻¹ after 100 cycles. Even at a high current density of 5.0 A g⁻¹, the specific capacity can still reach 166 mA h g⁻¹. Moreover, the f-V₂C/MWCNT structure shows good cycling stability with a capacity retention rate of 95% after 1000 cycles at 5.0 A g⁻¹. The above findings indicate that f-V₂C/MWCNT has great application potential in the field of Li⁺ storage.