Core-Shell Co2VO4/Carbon Composite Anode for Highly Stable and Fast-Charging Sodium-Ion Batteries

Sodium-ion batteries (SIBs) are promising candidates for largescale energy storage systems due to the abundance and wide distribution of sodium resources. Various solutions have been successfully applied to revolve the large-ion-size-induced battery issues at the mid-to-low current density range. However, the fast-charging properties of SIBs are still in high demand to accommodate the increasing energy needs at large to grid scales. Herein, a core-shell Co2VO4/ carbon composite anode is designed to tackle the fast-charging problem of SIBs. The synergetic effect from the stable spinel structure of Co2VO4, the size of the nanospheres, and the carbon shell provide enhanced Na+ ion diffusion and electron transfer rates and outstanding electrochemical performance. With an ultrahigh current density of 5 A g(-1), the Co2VO4@C anode achieved a capacity of 135.1 mAh g(-1) and a > 98% capacity retention after 2000 cycles through a pseudocapacitive dominant process. This study provides insights for SIB fastcharging material design and other battery systems such as lithium-ion batteries.