Rational Design of Ni Nanoparticles on N‐Rich Ultrathin Carbon Nanosheets for High‐Performance Supercapacitor Materials: Embedded‐ Versus Anchored‐Type Dispersion

Highly dispersed Ni nanoparticles (NPs) and abundant functional N-species were integrated into ultrathin carbon nanosheets by using a facile and economical sol-gel route. Embedded- and anchored-type configurations were achieved for the dispersion of Ni NPs in/on N-rich carbon nanosheets. The anchored-type composite exhibited outstanding pseudocapacitance of 2200 F g(-1) at 5 A g(-1) with unusual rate capability and extraordinary cyclic stability over 20 000 cycles with little capacitance decay. Aqueous asymmetric supercapacitors fabricated with this composite cathode demonstrated a high energy density of 51.3 Wh kg(-1) at a relatively large power density of 421.6 W kg(-1) , along with outstanding cyclic stability. This approach opens an attractive direction for enhancing the electrochemical performances of metal-based supercapacitors and can be generalized to design high-performance energy-storage devices.