Coral-like Composite Based on SnO₂@Rice Husk Nanoparticles Modified with Polyaniline Coated on Ni–Co Layered Double Hydroxide as an Innovative Electrode for Superior Supercapacitor Performance

Among different energy storage systems, supercapacitors (SCs) have many advantages including cost-effectiveness, long cycle life, stability, high specific capacity, high power density, environmental sustainability, safety, and fast charging/discharging capabilities. In supercapacitors, the materials used to fabricate the electrode have a crucial influence on the charge storage mechanism. Among different materials, layered double hydroxides (LDHs) with multiple redox-active centers as well as high specific capacity are widely used in SCs. However, the low conductivity and limited surface area of these electrode materials result in suboptimal electrochemical performance. To address these challenges in supercapacitors, a process was developed involving carbonization followed by oxidative polymerization to make an innovative composite material for electrodes. At a temperature of 500 °C, nanoparticles composed of rice husk char (RHC) core and SnO2 shell were deposited on the Ni–Co LDH nanoplates, resulting in the Ni–Co LDH@SnO2@RHC composite material. Then, the synthesized composite was uniformly coated with polyaniline (PANI) chains through aniline oxidative polymerization, resulting in the production of the final composite, named Ni–Co LDH@SnO2@RHC@PANI. Ni–Co LDH@SnO2@RHC@PANI composite was investigated by Fourier transform infrared (FT-IR), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDS), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), and elemental mapping analyses; also, the supercapacitive behavior of the electrodes was characterized using electrochemical impedance spectroscopy (EIS), galvanostatic charge–discharge (GCD) measurements, and cyclic voltammetry (CV). Ni–Co LDH@SnO2@RHC@PANI composite demonstrated a good specific capacity of 7684.2 F g–1 at a scan rate of 10 mV s–1. The asymmetrical configuration of the composite electrode offered a suitable stability of 99.5% in 2000 cycles. Supercapacitor devices provided energy and power densities at values of 51.3 Wh kg–1 and 148.7 W kg–1, respectively. As a result, the Ni–Co LDH@SnO2@RHC@PANI composite that is produced using this straightforward method is a promising component for pseudocapacitors based on the redox mechanism.