Mesoporous NiCo2S4 nanoparticles as high-performance electrode materials for supercapacitors

Abstract

Mesoporous NiCo<inf>2</inf>S<inf>4</inf> nanoparticles prepared through solvothermal route are reported as remarkable supercapacitor electrode materials. The resulting samples are characterized by means of XRD, FSEM, TEM, HRTEM, SAED, EDS and BET. With large specific surface area, superior mesopore structure and high electronic conductivity, the as-obtained NiCo<inf>2</inf>S<inf>4</inf> nanoparticles manifest excellent electrochemical performances with ultrahigh specific capacitance (1440 F g^-1 at 3 A g^-1) after 250 cycles, exceptional rate capability (75.1% capacity retention from 2 to 50 A g^-1) and good cycling stability (107.9% of initial capacity retention for 1000 cycles). Additionally, an asymmetric supercapacitor utilising the mesoporous NiCo<inf>2</inf>S<inf>4</inf> nanoparticles as a positive electrode and activated carbon as a negative electrode is further fabricated, which exhibits a prominent energy density of 28.3 Wh kg^-1 at a power density of 245 W kg^-1 and superior cycling stability of 91.7% initial capacity retention over 5000 cycles. These results above demonstrate the great potential of mesoporous NiCo<inf>2</inf>S<inf>4</inf> nanoparticles in the development of high-performance electrode materials for supercapacitors.