Preparation of g-C3N4/NiCo layered double hydroxide and nitrogen-doped biomass carbon/Fe-Mn bimetallic oxide composite materials for high performance asymmetric supercapacitors

The rational design of electrode materials with unique morphological and structural characteristics is crucial for high-performance supercapacitors. This study synthesized flower-shaped graphite carbon nitride (g-C3N4)/ nickel-cobalt layered double hydroxide (NiCo-LDH) composite material via hydrothermal method. g-C3N4, acting as a growth template, induced the growth of nickel-cobalt-layered double hydroxide. Density functional theory (DFT) calculations revealed that the introduction of g-C3N4 adjusted the electronic structure of the composite material and enhanced the adsorption capacity of OH- ions, promoting redox reactions and resulting in excellent electrochemical performance of the electrode material (1078 F g- 1 at 1 A g- 1 ). Additionally, nitrogen-doped biomass carbon (NBC)-Fe2O3@Mn2O3-800 degrees C composite material was synthesized via pyrolysis carbonization. Bimetallic oxide nanospheres Fe2O3@Mn2O3 distributed on the surface of NBC formed a conductive network, improving the electron transfer rate of the electrode material. DFT calculations further confirmed the outstanding conductivity of the composite material. Asymmetric supercapacitors (ASC) assembled using CN-30/ NiCo-LDH and NBC-Fe2O3@Mn2O3-800 degrees C as positive and negative electrode materials, respectively, which exhibited a maximum energy density of 34.5 Wh kg- 1 at a power density of 801.3 W kg- 1 and excellent cyclic performance after 5000 cycles. The electrode materials composed of metal compounds and carbon offer novel insights for energy storage applications.