A facile synthesis about amorphous CoS2 combined with first principle analysis for supercapacitor materials

The structure and electrochemical properties of amorphous CoS2 and crystalline CoS2 have been studied with both experimental characterization and theoretical calculations. In the field of experimental characterization, a facile chemical precipitation method is used to synthesize amorphous and crystalline CoS2 samples with calcining temperatures of 200 and 280 A degrees C, respectively. Comparing with crystalline CoS2, amorphous structure of CoS2 manifests great electron conductivity, effective porous structure, and exhibit a high specific capacitance of 996.16 F g(-1) at current density of 0.5 A g(-1), excellent rate capability of 89.8% retention with the current density ranging from 0.5 to 5 A g(-1), and a great cycling stability of 97.6% retention after 10,000 cycles at 2 A g(-1) in 6 mol L-1 KOH aqueous electrolyte. In the area of theoretical calculation, we used the first principle and obtained the band structure with band gap of 0.00369 eV and DOSs with high locality of D-orbital from 69.88689 electrons/eV main peak, in the CoS2 amorphous. The result confirms that amorphous CoS2 have higher conductivity than crystalline CoS2 in theory. In addition, the as-assembled asymmetric supercapacitor of Co-S-200//AC also exhibits the maximum specific capacitance of 104 F g(-1) within a cell voltage from 0 to 1.5 V at current density of 0.5 A g(-1) and indicates a great cycling stability of 95.68% and excellent capacitance behavior. All results demonstrate a great potential of amorphous CoS2 active material for supercapacitors.