Fabrication of Nanoneedle and Nanograss Array of Ni-Mixed CuCo<sub>2</sub>S<sub>4</sub>@Ni-Foam as Binder-Free Electrode Materials for High-Performance Supercapacitor Applications
Perumal Naveenkumar, Munisamy Maniyazagan, Johnbosco Yesuraj, Ki‐Bum Kim, G. Paruthimal Kalaignan, Woo Seung Kang, Sun-Jae Kim
Abstract
The surface morphologies of the active electrode materials have a significant impact on the electrochemical performance of supercapacitors. The Ni-mixed CuCo2S4 materials were successfully prepared on Ni-Foam using the hydrothermal method followed by the sulfidation process. CuCo1.5Ni0.5S4 has a nanoneedle structure, whereas CuCo1.0Ni1.0S4 has a vertically aligned nanograss structure. Due to the high theoretical capacity and redox behavior of Ni, Co, and Cu elements, the low electronegativity of S atoms, favorable structural behavior, and low hydration sphere radius with high ionic mobility character of OH– ions, the resulting CuCo1.0Ni1.0S4 nanograss was used as a binder-free electrode for supercapacitor application. It has delivered outstanding specific capacity, rate capability, and cycle performance characteristics. The CuCo1.0Ni1.0S4 electrode produced a maximum specific capacity of 325.5 mA h/g at a current density of 1 A/g, while maintaining good rate capability. After 5000 cycles at 20 A/g, the CuCo1.0Ni1.0S4 electrode retains 86% of its initial capacity. Furthermore, the asymmetric supercapacitor device is made with CuCo1.0Ni1.0S4 as the positive electrode material and activated carbon as the negative electrode material. The fabricated ASC has a maximum energy density of 38.5 W h/kg at a power density of 356 W/kg. In summary, the CuCo1.0Ni1.0S4 electrode is a promising material for electrochemical energy storage and conversion applications.