“Trunk-Leaf Vein” Structure Inspired Synthesis of Mesoporous Carbon@Nickel Oxide/Nickel Ternary Composite for Sustainable Supercapacitor Electrode

Abstract Supercapacitors are sustainable energy storage devices with the characteristics of high power density, long life span and ultrafast charge-discharge time. Herein, considering low conductivity of NiO and inspired by the “trunk-leaf vein” structure, mesoporous carbon and nickel dots are introduced into structure reacting as electron scaffold via facile hydrothermal and annealing procedures. Special hierarchical structure is obtained with oxygen modified mesoporous carbon (OMC) as core and NiO sheets as core accompanying with metallic nickel dots deposited on NiO sheets. Such “trunk-leaf vein” architecture can effectively ensure more active sites contacting with electrolyte, furthermore provide conductive scaffolds for electron transport. As expected, the OMC@NiO/Ni exhibits high specific capacitance of 651.3 F g−1 at 2 A g−1 and superior cycling life of 92.2% after 4000 cycles. Moreover, a novel negative electrode rGO/VOx is synthesized ascribe to the superior capacitance and life span. At last, an asymmetric device is assembled using OMC@NiO/Ni as positive electrode and rGO/VOx as negative electrode, which delivers maximum energy density of 44.3 Wh kg−1, high power density of 12000 W kg−1 and excellent cycling life of 94.5% after 5000 cycles. The high performance of OMC@NiO/Ni renders it a potential material for energy storage-conversion equipments.