Ammonium fluoride regulated CoMoS4-derived Co9S8@MoS2 composite for high-performance hybrid supercapacitor

The high-performance Co9S8@MoS2 composite was firstly prepared though the ammonium fluoride regulated CoMoS4-derived process by a simple one-step hydrothermal method, without the previous complicated and tedious preparation procedures. Moreover, it can exhibit the ultrahigh specific capacity of 213 mAh/g at 1 A/g, owing to the multiple oxidation state of Co/Mo, conductivity superiority of metallic sulfides and suitable structure. In order to simulate the application indicators of Co9S8@MoS2 composite for commercial supercapacitors, the Co9S8@MoS2//AC hybrid supercapacitor device was well designed by the optimized Co9S8@MoS2 composite and commercial active carbon (AC) as positive/negative electrode respectively, and exhibits the good electrochemical properties: the high energy density of 42 Wh/kg at 375 W/kg, and even still maintain 25 Wh/kg at the high power density of 2250 W/kg; and excellent cycle stability with no significant reduction of capacity retention after 9000 cycles. This work can not only provide a simple one-step hydrothermal preparation method of Co9S8@MoS2 composite, but also confirm its promising application prospects in supercapacitor electrode materials.