CoS<sub>2</sub>/N‐Doped Hollow Spheres as an Anode Material for High‐Performance Sodium‐Ion Batteries
Jianyu Li, Jixian Wu, Siwei Fan, Guangda Li
Abstract
Abstract In this work, we first synthesized polyacrylic acid (PAA) spheres and then used PAA as a template to load Co(OH) 2 particles onto its surface. The product of CoS 2 nanoparticles dispersed in N‐doped hollow spheres (N‐HCS) was prepared through sulfurization treatment (CoS 2 /S@N‐HCS). During the sulfuration process, sulfur penetrates into the PAA, embedding into the graphite layer along with the carbonization process. It was found that during the charging and discharging process, the sulfur in the carbon layer will gradually dissolve out, thereby forming new ion diffusion channels in the carbon spheres and exposing more CoS 2 active sites. The CoS 2 /S@N‐HCS composite exhibits a specific capacity of 729.6 mAh g −1 after 500 cycles at a current density of 1 A g −1 . The sodium‐storage mechanism and reaction kinetics of the materials were further measured by in‐situ electrochemical impedance spectroscopy, ex‐situ X‐ray diffraction, capacitance performance evaluation, and galvanostatic intermittent titration technique. The excellent cycling performance and rate capability demonstrated that the CoS 2 /S@N‐HCS is a potential and prospective anode material for sodium‐ion batteries.