Alternating electrodeposition fabrication of graphene-buffered nickel-cobalt layered double hydroxide supercapacitor electrodes with superior rate capability.

Combining pseudocapacitive materials with carbon materials, such as graphene, is a promising strategy to enhance their performance. In this study, we present a novel and feasible approach involving the alternating electrodeposition of reduced graphene oxide (rGO) and nickel-cobalt layered double hydroxide (NiCo-LDH) onto carbon cloth (CC) current collectors to fabricate binder-free supercapacitor electrodes with a layered LDH/rGO/LDH/rGO/CC architecture. The rGO layers are not only coated on CC substrate to regulate the electrodeposition of LDH nanosheets, but also interposed between the LDH layers to further enhance conductivity and provide buffering effects. The as-prepared electrode achieves a high specific capacitance of 2400 F g-1 at a current density of 1 A g-1, with an outstanding rate capacity retaining 83.1 % of the capacitance at 60 A g-1 and even a retention of 72.5 % at 100 A g-1. Furthermore, the asymmetric supercapacitor configured using the composite electrode and an activated-carbon electrode delivers an energy density of 38.7 Wh kg-1 at a power density of 825 W kg-1, accompanied by excellent cyclic stability with a capacitance retention of 74.4 % after undergoing 10,000 charge/discharge cycles. This work proposes an innovative methodology for fabricating LDH-based functional composites in supercapacitors and other related fields.