Tailoring the Composition of Ternary NiCoFe Layered Double Hydroxide with Graphitic Carbon Nitride as a Positive Electrode Material for High-Performance Hybrid Supercapacitors

This work reports a simple hydrothermal-assisted method to prepare a high-performance nickel cobalt iron layered double hydroxide/graphitic carbon nitride (NiCoFe LDH/g-C₃N₄) composite for supercapacitor (SC) applications. Various spectral and analytical techniques were used to confirm the formation of NiCoFe LDH/g-C₃N₄ composite. The NiCoFe LDH/g-C₃N₄ composite demonstrates battery-like SC behavior in the three-electrode measurements. The NiCoFe LDH/g-C₃N₄ composite has a maximum specific capacity (366 C g⁻¹ at 1 A g⁻¹) compared to the individual NiCoFe LDH and g-C₃N₄ electrode materials. Further, the NiCoFe LDH/g-C₃N₄ composite electrode shows 89 % capacity retention even after 8000 galvanostatic charge-discharge (GCD) cycles at 6 A g⁻¹. In addition, a hybrid supercapacitor (HSC) is fabricated by using NiCoFe LDH/g-C₃N₄ composite as a positive electrode and activated carbon (AC) as a negative electrode. The as-fabricated NiCoFe LDH/g-C₃N₄//AC HSC demonstrates an impressive energy density of 76.44 Wh kg⁻¹ and a power density of 1279.9 W kg⁻¹, along with excellent long-term cycle stability of 83 % capacity retention even after 6000 GCD cycles at 6 A g⁻¹. Considering its simplicity of fabrication and exceptional energy storage capabilities, the as-fabricated NiCoFe LDH/g-C₃N₄//AC hybrid supercapacitor has significant promise for practical use in the near future.