Construction of nano-rod-like highly crystalline g-C3N4 in situ supported Ni0.85Se for asymmetric supercapacitors

Due to its special electron configuration, large number of electrochemical reactive sites, and a high theoretical specific capacitance, Ni0.85Se has great application potential for supercapacitor electrodes. However, the poor charge driving ability and easy aggregation of Ni0.85Se hinder the full utilization of its electrochemical reactive site, thus limit its practical application. Here, nano-rod-like highly crystalline graphitic carbon nitride (CCN) was synthesized via molten salt assisted method, and then CCN/Ni0.85Se composite nanomaterials were synthesized by hydrothermal induction. Through various characterization and electrochemical tests, nano-rod-like CCN not only improves the poor electrical conductivity and incomplete surface reactive site exposure of bulk g-C3N4 prepared by traditional thermal polymerization, but also improves the charge dynamics and enrich the electrochemical active sites of sheets Ni0.85Se, and improves the electrochemical activity of the composite. On the base of results, CCN/Ni0.85Se-7 has the best specific capacitance of 1234 F g- 1 at 1 A g-1, which is significantly higher than that of pure phase Ni0.85Se (841.2 F g-1) and CCN (34.4 F g-1). The CCN/Ni0.85Se-7//AC two- electrode device exhibited a maximum energy density of 29.11 Wh kg-1 , a maximum power density of 8499.86 W kg- 1 , and good capacitance retention ability of 81.46 % after 2000 cycles.