Ultrafine Mo2C nanoparticles encapsulated in N-doped carbon nanofibers with enhanced lithium storage performance.

Abstract

Rechargeable lithium ion batteries (LIBs) have attracted extensive attention globally due to their good cycling stability, high energy density, and rapid-rate capability, while the rational design of electrode materials can significantly improve their electrochemical performance. In this work, ultrafine Mo2C nanoparticles (NPs) were successfully encapsulated in one dimensional (1D) N-doped porous carbon nanofibers to form a hybrid (Mo2C-NCNFs) through a single-nozzle electrospinning approach coupled with post-pyrolysis. The sizes of the Mo2C NPs were in the range of 2-4 nm and the ultrafine Mo2C NPs were uniformly encapsulated in the N-doped carbon nanofibers forming a highly conductive and interconnecting network, which can facilitate fast electronic transport. When evaluated as an anode material for LIBs, the resultant hybrid exhibits stable cycling performance and excellent rate behavior. More remarkably, the Mo2C-NCNFs hybrid is capable of delivering a specific capacity of 658.0 mA h g(-1) under 100 mA g(-1) after 50 cycles. Even under 2000 mA g(-1), a relatively high specific capacity of 411.9 mA h g(-1) can be achieved, which surpasses the theoretical capacity of graphite (372 mA h g(-1)). The excellent lithium storage performance can be attributed to its unique nanostructure with a strong interaction between the ultrafine Mo2C NPs and N-doped carbon that effectively tolerates the volume change, suppresses the agglomeration of Mo2C NPs, and provides conductive pathways for highly efficient charge transfer during lithium insertion and extraction.