Bi 2 O 3 @reduced graphene oxide and NiCo 2 @Ni 3 Co electrodes for all-electrodeposited high-performance supercapacitors

A novel alpha-Bi 2 O 3 @reduced graphene oxide (rGO) composite negative electrode is designed using an electrodeposition technique, exhibiting an activation process during the first 100 charge-discharge cycles. The bismuth compounds in an initial adsorbed state gradually transformed into a dissolved state, resulting in a distinctive morphological change and the formation of a porous nanosheet structure. At a current density of 1 A/g, the alpha-Bi 2 O 3 @rGO achieves a specific capacitance of 1144 F/g (317 mAh/g), representing 92.18 % of its theoretical value. Even when the current density is increased by 20 times, the capacitance still maintains at 91.71 %. Additionally, a multi-layered composite cathode of NiCo 2 @Ni 3 Co is prepared. Based on these two electrodes, an all-electrodeposited soft-packaged supercapacitor (AESPS) is assembled, reaching an energy density of 107.8 Wh/kg at a power density of 800 W/kg, and 73.8 Wh/kg at 16 kW/kg. These outstanding electrochemical performances strongly demonstrate their potential in novel energy storage devices.