Positive Carbon Dots Induced Electrodeposition of NiCo-LDH Nanosheets for High-Performance Supercapacitors

Abstract

The electrodeposition process is a low-cost, high-efficiency, and binder-free route to synthesize layered double hydroxides (LDHs) for high-performance supercapacitors. However, the disordered growth of LDH nanosheets in direct electrodeposition would limit exposure of active sites and easily cause collapse during cycling. Here, we report a kind of positively charged carbon dots (p-CDs) that induce the ordered growth of ultrathin LDH hierarchical nanostructures in a one-step electrodeposition process. The precise regulation of the NiCo-LDH surface morphology was achieved by changing the concentration of p-CDs, which could adsorb NO3– in the electrolyte and induce electrodeposition. The as-prepared electrode delivers an enhanced specific capacitance of 1896 F g–1 at 1 A g–1 and an excellent rate performance (87.6% capacitance retention at 20 A g–1). A supercapacitor based on the composite LDH/CDs and active carbon exhibits a high energy density of 46.06 Wh kg–1 with a power density of 750 W kg–1 and a remarkable cycle stability (78.3% after 30,000 cycles at 5 A g–1). This research presents a successful example of CD application in electrochemical energy storage.