CNT/Co3S4@NiCo LDH ternary nanocomposites as battery-type electrode materials for hybrid supercapacitors

Abstract

Hybrid supercapacitors with high energy density and power density have been greatly required for electronic devices. However, the development of the battery-type electrode materials with high performance is still a challenge. In this study, a ternary carbon nanotube (CNT)/Co3S4 @NiCo layered double hydroxides (NiCo LDH) nanocomposite has been prepared by first synthesis of hollow and core-shell Co3S4 @NiCo LDH nanocubes and then mixing them physically with commercial CNT. The electrochemical studies show that the specific capacity of Co3S4 @NiCo LDH is superior to that of individual Co3S4 or NiCo LDH due to their synergistic effect and CNT can remarkably improve the specific capacity of Co3S4 @NiCo LDH. At the optimum mass ratio of 3:10, the specific capacity of CNT/Co3S4 @NiCo LDH at 1 A g −1 can be up to 744 C g −1 (or 206.7 mAh g−1), about 1.8 times that of Co3S4 @NiCo LDH. In addition, a hybrid supercapacitor using Co3S4 @NiCo LDH or CNT/Co3S4 @NiCo LDH as the positive electrode and active carbon (AC) as the negative electrode was assembled. The performance of Co3S4 @NiCo LDH//AC, CNT/Co3S4 @NiCo LDH//AC and two CNT/Co3S4 @NiCo LDH//AC in series was investigated, displaying good practicability as the energy storage and supply devices. This work provides not only a highly efficient battery-type electrode material but also an easy and effective method to fabricate ternary electrode materials.