Cobalt selenide nanoparticles composited with carbon nanotube and reduced graphene oxide for high-performance lithium/sodium storage

Composites of cobalt selenide nanoparticles , carbon nanotubes and reduced graphene oxide (CoSe/CNTs/rGO) are successfully prepared by the hydrothermal method followed by ball milling . The CoSe nanoparticles are dispersed into the carbon matrix formed by rGO and CNTs. The composite can be used as the electrode material for lithium and solidum ion storage. As the anode material for lithium ion battery (LIB), the optimum composite exhibits the reversible specific capacity of 848 mAh g −1 , 745 mAh g −1 and 406 mAh g −1 at 0.2 A g −1 , 1 A g −1 , and 2 A g −1 , respectively. When used as the anode material for sodium ion battery (SIB), the optimum composite exhibits the reversible specific capacity of 448 mAh g −1 , 379 mAh g −1 and 279 mAh g −1 at 0.5 A g −1 , 1 A g −1 , and 2 A g −1 , respectively. Appropriate amounts of CNTs and rGO generate highly dispersed CoSe nanoparticles in the carbon matrix, which yield abundant electrochemically active sites, reduced charge transfer resistance, and accelerated ion diffusion. Evidences for conversion mechanism of charge storage is given in both LIB and SIB, and the contribution of capacitive-controlled process to the charge storage is higher in LIB than SIB.