High specific energy supercapacitor electrode prepared from MnS/Ni3S2 composite grown on nickel foam

Herein, MnS was prepared in situ with Ni3S2 directly on nickel foam to obtain a novel binder-free highly conductive electrode with a superb echinocactus-like morphology. The novel electrode gives ultra-high results when examined as an electrode for supercapacitor applications, such as an areal capacity of 796.7 mA h cm−2 equivalent to an areal capacitance of 2390 F cm−2 at a current density of 3 mA cm−2, in addition to low resistance and a remarkable potential window. Furthermore, a hybrid device using this electrode as a positive electrode and commercial activated carbon as a negative electrode was fabricated to examine the practical aspects of the novel electrode, which conducted a specific energy of 77.5 W h kg−1 at a specific power of 18 000 W kg−1. Interestingly, it preserved a specific energy of 33.3 W h kg−1 at a specific power of 50 000 W kg−1 and a satisfactory capacity retention of 80% after 2000 cycles with a Coulombic efficiency reaching 99%. These results confirm the electrode's superior electrochemical performance as a promising electrode for energy storage applications.