CoS2 nanoparticles grown in situ on rGO nanosheet as a potential anode material toward high-performance sodium-ion hybrid capacitors

Sodium-ion hybrid capacitors (SICs) as promising energy conversion and storage devices have exhibited excellent specific energy, high specific power, and good cycling life. Nevertheless, anode materials for SICs suffer from terrible volume expansion and sluggish reaction kinetics owing to the larger radius of sodium-ion. To find suitable anode materials, we design and prepare reduced graphene oxide-supported CoS 2 nanoparticles (CoS 2 /rGO) with high electrochemical performance through a facile hydrothermal method. When tested as anode materials, the specific capacity of CoS 2 /rGO delivers 529.3 and 1168.6 mA h g −1 in the process of the 1st charge and discharge, respectively. Moreover, the specific capacity retention is up to 214.8 mA h g −1 at 100 mA g −1 over 100 cycles. In order to explore the practical application of CoS 2 /rGO, SICs are assembled by biomass-derived porous carbon cathodes and CoS 2 /rGO anodes, which displays remarkable specific energy of 112.6, 103.75, 91.29, 70.34, 47.45 W h kg −1 under specific power 225, 449.82, 899.86, 1350, 2689.3 W kg −1 , respectively, benefiting from the high pseudocapacitive performance of CoS 2 /rGO anodes and outstanding specific capacity of biomass-derived porous carbon cathodes.