Homogenous sdiophilic MoS2/nitrogen-doped carbon nanofibers to stabilize sodium deposition for sodium metal batteries

Sodium metal is one of the most promising anode materials for next generation batteries due to its low cost and high capacity. However, uneven Na nucleation, subsequent dendrite growth and huge volume change impedes its further applications. Herein, a 3D framework consisted of N-doped carbon nanofibers (NCF) and MoS2 is designed to serves as the substrate for Na deposition. The 2H-MoS2 and N-functional groups with strong sodiophilicity contribute to the adsorption of Na+ and the reduction of Na nucleation energy. Due to the low nucleation barrier enabled by 2H-MoS2 and pyridinic N-functional groups, high-loading Na can deposit uniformly on the surface of the MoS2/NCF skeleton. After cycles, the Na diffusion will be controlled by Na migration on the surface of 1T-MoS2 with a much lower energy barrier (-0.291 eV). The cooperation of super sodiophilicity and eventual adsorption makes Na stripping/plating over 3000 cycles at 8 mA cm(-2) with coulombic efficiency of 99.6% (8000 cycles at 2 mA cm(-2)). The symmetric MoS2@NCF/Na cells exhibited excellent cycling stability and stable hysteresis voltage (30.0 mV after 3000 cycles at 6 mA cm(-2) with 3 mA h cm(-2)) and excellent rate performance (low overpotential of 120 mV at 20 mA cm(-2)). Owning to these virtues, the full cells of MoS2@NCF/ Na||NVP@C also display exceptional improvement in cycling and rate performance (75 mA h g(-1) at 30 C). This work develops a promising strategy based on stable Na deposition for advanced high-performance sodium-metal batteries.

Automated summary

A 3D framework consisting of N-doped carbon nanofibers (NCF) and MoS2 is designed as the substrate for Na deposition in order to address the issues in sodium-metal batteries. This framework enables efficient and stable sodium deposition, improving the cycling life and rate performance of sodium-metal batteries.