The rhombododecahedral CNT@CoS/ NiCo-LDH composite electrode material was prepared by mechanical stirring and etching precipitation method. The electrochemical test results show that the CNT@CoS/ NiCo-LDH-100 exhibits high specific capacitance of 2794.6 F g^-1 at 1 A g^-1, which is superior to other materials with the addition of nickel source. When the current density increases to 5 A g^-1, the capacitance retention is 60.1%. In the two-electrode system, the specific capacitance of CNT@CoS/ NiCo-LDH-100 is 114.1 F g^-1 (1 A g^-1) and excellent stability with 87% after 1000 cycles. The device exhibits a relatively high energy density of 35.64 Wh kg^-1 at a power density of 750 W kg^-1, and even at the high power density of 3750 W kg^-1, the energy density of CNT@CoS/ NiCo-LDH material can still maintain 26.38 Wh kg^-1. Hence, the superior pseudocapacitive performance of CNT@CoS/ NiCo-LDH can be ascribed to the synergy among three materials as well as the excellent three-dimensional structure obtained by changing amount of nickel source.
 

supercapacitor; composite material; electrochemical performance