Preparation of NiCoLDH/rGO-SCC composites from aluminum electrolytic spent cathode carbon for hybrid supercapacitor

This study presents a valuable repurposing approach for spent cathode carbon, in which the aluminum electrolysis spent cathode carbon was successfully converted into graphene oxide by Hummer’s method of oxidative intercalation with synergistic ultrasonic exfoliation, and further constructed NiCoLDH/rGO-SCC composites to be used in the electrode materials of hybrid supercapacitor. The large specific surface area of graphene oxide serves as a conductive channel in the electrodes, facilitating charge transfer during the reaction process, in addition to providing NiCoLDH nanosheets with a large number of spatial sites. Electrochemical tests and density functional theory calculations confirmed that graphene oxide facilitated charge transfer during pseudocapacitive reactions. In the three-electrode system, the composite exhibited a specific capacity of 2818 F g −1 , ensuring outstanding electrochemical performance for the hybrid supercapacitor. The results showed that the assembled hybrid supercapacitor could reach an energy density of 35.93 Wh kg −1 at a power density of 375 W kg −1 , and still possesses a capacity retention rate of 85.25 % after 1000 charge/discharge cycles. Consequently, the results demonstrated the supercapacitor’s significant application prospects. This approach provides a sustainable way to recycle spent cathode carbon and develop new capacitor electrode applications.