Superior Pseudocapacitive Storage of a Novel Ni(3)Si(2)/NiOOH/Graphene Nanostructure for an All-Solid-State Supercapacitor

Recent developments in the synthesis of graphene-based structures focus on continuous improvement of porous nanostructures, doping of thin films, and mechanisms for the construction of three-dimensional architectures. Herein, we synthesize creeper-like Ni(3)Si(2)/NiOOH/graphene nanostructures via low-pressure all-solid melting-reconstruction chemical vapor deposition. In a carbon-rich atmosphere, high-energy atoms bombard the Ni and Si surface, and reduce the free energy in the thermodynamic equilibrium of solid Ni–Si particles, considerably catalyzing the growth of Ni–Si nanocrystals. By controlling the carbon source content, a Ni(3)Si(2) single crystal with high crystallinity and good homogeneity is stably synthesized. Electrochemical measurements indicate that the nanostructures exhibit an ultrahigh specific capacity of 835.3 C g(−1) (1193.28 F g(−1)) at 1 A g(−1); when integrated as an all-solid-state supercapacitor, it provides a remarkable energy density as high as 25.9 Wh kg(−1) at 750 W kg(−1), which can be attributed to the free-standing Ni(3)Si(2)/graphene skeleton providing a large specific area and NiOOH inhibits insulation on the electrode surface in an alkaline solution, thereby accelerating the electron exchange rate. The growth of the high-performance composite nanostructure is simple and controllable, enabling the large-scale production and application of microenergy storage devices. [Image: see text] ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1007/s40820-020-00527-w) contains supplementary material, which is available to authorized users.