CNTs@NC@CuCo2S4 nanocomposites: An advanced electrode for high performance lithium-ion batteries and supercapacitors

The design and fabrication of the materials to improve their performance are crucial for energy storage of lithium-ion batteries and supercapacitors. Herein, the CuCo2S4 nanocrystallites grown on N-doped amorphous carbon coated CNTs are synthesized via a facile solvothermal method (CNTs@NC@CuCo2S4). The N-doped amorphous carbon layer with functional groups can effectively strengthen the adhesion between CNTs matrix and CuCo2S4 nanocrystallites. The combination of nanocrystallites and the CNTs not only shortens the diffusion path of the electrolyte, but also enhances the electrical conductivity of the electrode. As a result, the CNTs@NC@CuCo2S4 displays excellent electrochemical performance both in lithium-ion batteries and supercapacitors. The reversible capacity can be retained at 783 mAh g−1 after 100 cycles at the current density of 100 mA g−1. And the discharge capacity of 507 mAh g−1 is still maintained after 60 cycles even at high rate of 5000 mA g−1. As the electrode for supercapacitors, the CNTs@NC@CuCo2S4 delivers good capacitive performance with high capability (1604 F g-1 at 1 A g−1), good rate capability, and enhanced cycling stability, with 93.6% capacitance retention after 2000 cycles at the current density of 2 A g−1.