High-performance asymmetric supercapacitor achieved by CoS2 nanoparticles decorated polyaniline functionalized SBA-15-derived mesoporous nitrogen-doped carbon with rod-like architectures

The promising candidates for high-performance electrode materials, transition metal species@N-doped mesoporous carbon composites (M/MO/M(OH) 2 @NDMCs), were synthesized by carbonization of metal ion-doped polyaniline (PANI) functionalized mesoporous silica SBA-15, followed by etching the mesoporous silica template. The yielded M/MO/M(OH) 2 @NDMC can be further converted into sulfide via a simple hydrothermal sulfidization treatment. The mesoporous structure, large amount of the accessible electrochemically active nitrogen species, partially graphitic structure, and transition metal compounds of transition metal species@NDMC composites will increase the electronic and ionic conductivity by reducing the internal and ion diffusion resistances resulting in fast diffusion of ions in the electrolyte to the electrode surface. These endowed them good electrochemical performance characteristics for use in supercapacitor electrodes. Correspondingly, NiO/Ni(OH) 2 @NDMC, Co/Co(OH) 2 @NDMC, and CoS 2 @NDMC as the electrodes in 2 M KOH showed specific capacitance of 337, 589, and 1178 F g –1 at 2.0 A g –1 , respectively. Furthermore, the assembled asymmetric supercapacitor device utilizing CoS 2 @NDMC as a cathode exhibited a satisfactory energy storage capability (50 Wh kg –1 at 750 W kg –1 ) with an admirable cyclic life (retaining ~99% initial capacitance over 6000 repeated cycles). This finding gives these transition metal species@NDMC composites, especially CoS 2 @NDMC, prospective applications as high-performance supercapacitor electrode materials, where a fast charge/discharge is required. Asymmetric supercapacitor composed of CoS 2 nanoparticles decorated N-doped mesoporous carbons as positive and acid-treated activated carbon as negative electrodes exhibited expanded voltage window of 1.5 V in 2 M KOH, high capacitance value (160.5 F g –1 at 1 A g –1 ), good energy density (~50 Wh kg –1 ), and long cycle life. • CoS 2 @N-doped mesoporous carbon (NDMC) possesses ultrahigh specific capacitance. • CoS 2 @NDMC possesses high stored energy from the diffusion-controlled process. • CoS 2 @NDMC//carbon ASC device exhibits large energy density and power capability.