Growth of nanostructured cobalt sulfide-based nanocomposite as faradaic binder-free electrode for supercapattery

The intermittent nature of renewable energy needs ideal storage device to balance the electricity demand and supply. Specific energy, specific power, and stability of electrode play a critical role to increase better performance of supercapattery. Here, we account a unique cobalt sulfide (CoS) binder-free electrode which was modified with different metals (i.e. manganese (Mn) and copper (Cu), fabricated by hydrothermal technique on the nickel foam (NF). The morphological features portray uniform distribution of flakes with different textures after the incorporation of Mn and Cu with the optimised cobalt sulfide system, respectively. Among all electrodes, Mn-CoS-3/NF exhibits a significant boost in the rate capability at 74% compared to CoS-3/NF (75%) and Cu-CoS-3/NF (59%) electrodes with maximum specific capacitance of 2379 F/g at 1 A/g. Mn-CoS-3/NF also shows capacitance retention about 65% after 5500 cycles compared to CoS-3/NF (48%) and Cu-CoS-3/NF (55%) when performed as three electrode system configurations. The outstanding performance of Mn-CoS-3/NF as compared to the other electrodes is contributed to its high surface area, flake-like nanostructure, valence state of metal, and low internal resistance. In order to evaluate the real time performance of Mn-CoS-3/NF, supercapattery device was fabricated in a configuration of Mn-CoS-3/NF//AC/NF. Mn-CoS-3/NF//AC/NF delivered a specific energy (17.94 Wh/kg at 806 W/kg) and specific power (6405 W/kg at 4.66 Wh/kg). The capacity decayed slowly to 92% after 9000 cycles together with a coulombic efficiency of 99%, indicating good stability of the device.

Automated summary

Renewable energy requires efficient storage devices for balancing electricity demand and supply. In this study, a cobalt sulfide electrode modified with different metals, such as manganese and copper, demonstrated enhanced performance in terms of specific capacitance and cycling stability. Among the electrodes tested, Mn-CoS-3/NF exhibited the best rate capability and capacitance retention, attributed to its unique nanostructure and low internal resistance.