Facile fabrication of NiCo-LDH on activated rice husk carbon for high-performance all-solid-state asymmetric supercapacitors

Abstract

Biomass carbon materials, which are environmentally friendly, have received significant attention and rapidly developed in the field of electrochemical devices. In this study, rice husk carbon (RHC) was prepared using calcination and activation methods, and a layer of nickel–cobalt double hydroxide (NiCo-LDH) was grown on the surface of RHC using a hydrothermal method, resulting in the formation of the NiCo-LDH@RHC composite. The open nanoflower structure and the synergistic effect between RHC and NiCo-LDH increased the conductivity and stability of the electrode material, as well as its specific capacitance. The NiCo-LDH@RHC electrode delivered a high specific capacity of 8542.5 mF cm⁻² at a current density of 2 mA cm⁻² with a good cycling stability of 80.45% across 5000 cycles. Furthermore, a high-performance all-solid-state asymmetric supercapacitor (ASC) was assembled using Fe₂O₃/CC as the anode material and NiCo-LDH@RHC as the cathode material. It displayed a high energy density of 61.44 μW h cm⁻² at a power density of 3.99 mW cm⁻² and an excellent cycle retention rate of 86.54% after 10 000 cycles. This research demonstrates that NiCo-LDH@RHC is an environmentally friendly and high performance electrode material with great development potential.