Metal–Organic Framework-Derived Hollow Carbon Nanosphere@Ni/Reduced Graphene Oxide Composites for Supercapacitor Electrodes with Enhanced Performance

The faradaic process of transition-metal-based oxides or/and hydroxides is widely utilized to increase the capacity of electrochemical energy storage significantly. However, poor electrical conductivity and low stability of these materials are two crucial factors hindering the maximization of their potential application. To address this issue, carbon–transition-metal oxide composites are strategized to combine the high electrical conductivity of carbon materials and the capacity of transition metals. Here, inspired by the self-assembly process of metal–organic frameworks, a hollow carbon nanosphere (HCNS)@Ni precursor/rGO is synthesized by a one-pot hydrothermal method. HCNS@Ni nanoparticles/rGO (HCNS@Ni NP/rGO) is derived in subsequent calcination. The synthesized HCNS@Ni NP/rGO was assembled as an electrode and evaluated with outstanding electrochemical properties and performances. A high specific capacity of 1589 F g^–1 at a current density of 0.3 A g^–1 and even 733.33 F g^–1 at 50 A g^–1 are obtained, with 46.2% of capacity remaining. After 1600 charge–discharge cycles at 10 A g^–1, the assembled electrode exhibits the desirable capacity retention of 77.9%.