Double Morphology of Co9S8 Coated by N, S Co-doped Carbon as Efficient Anode Materials for Sodium-Ion Batteries
Xuzi Zhang, Chaoqun Shang, Xin Wang, Guofu Zhou
Abstract
Abstract Co 9 S 8 is a potential anode material for its high sodium storage performance, easy accessibility, and thermostability. However, the volume expansion is a great hindrance to its development. Herein, a composite containing Co 9 S 8 nanofibers and hollow Co 9 S 8 nanospheres with N, S co-doped carbon layer (Co 9 S 8 @NSC) is successfully synthesized through a facile solvothermal process and a high-temperature carbonization. Ascribed to the carbon coating and the large specific surface area, severe volume stress can be effectively alleviated. In particular, with N and S heteroatoms introduced into the carbon layer, which is conducive to the Na + adsorption and diffusion on the carbon surface, Co 9 S 8 @NSC can perform more capacitive sodium storage mechanism. As a result, the electrode can exhibit a favorable reversible capacity of 226 mA h g −1 at 5 A g −1 and a favorable capacity retention of 83.1% at 1 A g −1 after 800 cycles. The unique design provides an innovative thought for enhancing the sodium storage performance.