Integrating nickel foam@carbon nanotubes composite current collector with MnMoO4 for enhanced performance of supercapacitor electrode

Abstract

Nickel foam (NF) has been broadly adopted as the current collector for supercapacitors due to its high porosity, unique three-dimensional (3D) network structure and good electrical conductivity. However, its small specific surface area resulted in a low loading of active materials. Thus, it is of great significance to modify NF to obtain a current collector with high specific surface area. Herein, a 3D NF@CNTs composite current collector was fabricated through in-situ growth of carbon nanotubes (CNTs) on NF by chemical vapor deposition (CVD) method, followed by the combination of MnMoO₄ nanoflowers with CNTs via a hydrothermal method, and MnMoO₄/NF@CNTs composite electrode was successfully obtained. The results indicated that the distinct design of 3D NF@CNTs composite current collector could offer an efficient mesoporous network, a high specific surface area and rapid electron and ion transfer channels, and accommodate more active sites for MnMoO₄ nanoflowers. Accordingly, the optimized MnMoO₄–130/NF@CNTs electrode achieved a superior areal capacitance of up to 5300 mF/cm² (1886.1 F/g) at 2 mA/cm², and maintained an outstanding rate capability of 79.7 % at 25 mA/cm². After 2000 charge/discharge cycles, MnMoO₄–130/NF@CNTs possessed a capacitance retention rate of 81.0 %. Besides, a symmetric supercapacitor (SSC) was eventually fabricated based on MnMoO₄–130/NF@CNTs electrodes, and it delivered a favorable energy density of 0.0197 mWh/cm² at a power density of 0.3 mW/cm², along with a superb cycling performance with the capacitance retention rate of 94.7 % after 2000 cycles. The above results demonstrated that the 3D NF@CNTs composite current collector achieved by the CVD process would be a good route to improve the effective specific surface area of NF and the loading of active materials for high-performance supercapacitors.