Coral-like\nComposite\nBased on SnO<sub>2</sub>@Rice\nHusk Nanoparticles Modified with Polyaniline Coated on Ni–Co\nLayered Double Hydroxide as an Innovative Electrode for Superior Supercapacitor\nPerformance

Among different energy storage systems,\nsupercapacitors\n(SCs) have\nmany advantages including cost-effectiveness, long cycle life, stability,\nhigh specific capacity, high power density, environmental sustainability,\nsafety, and fast charging/discharging capabilities. In supercapacitors,\nthe materials used to fabricate the electrode have a crucial influence\non the charge storage mechanism. Among different materials, layered\ndouble hydroxides (LDHs) with multiple redox-active centers as well\nas high specific capacity are widely used in SCs. However, the low\nconductivity and limited surface area of these electrode materials\nresult in suboptimal electrochemical performance. To address these\nchallenges in supercapacitors, a process was developed involving carbonization\nfollowed by oxidative polymerization to make an innovative composite\nmaterial for electrodes. At a temperature of 500 °C, nanoparticles\ncomposed of rice husk char (RHC) core and SnO<sub>2</sub> shell were\ndeposited on the Ni–Co LDH nanoplates, resulting in the Ni–Co\nLDH@SnO<sub>2</sub>@RHC composite material. Then, the synthesized\ncomposite was uniformly coated with polyaniline (PANI) chains through\naniline oxidative polymerization, resulting in the production of the\nfinal composite, named Ni–Co LDH@SnO<sub>2</sub>@RHC@PANI.\nNi–Co LDH@SnO<sub>2</sub>@RHC@PANI composite was investigated\nby Fourier transform infrared (FT-IR), X-ray diffraction (XRD), energy-dispersive\nX-ray spectroscopy (EDS), field emission scanning electron microscopy\n(FE-SEM), transmission electron microscopy (TEM), and elemental mapping\nanalyses; also, the supercapacitive behavior of the electrodes was\ncharacterized using electrochemical impedance spectroscopy (EIS),\ngalvanostatic charge–discharge (GCD) measurements, and cyclic\nvoltammetry (CV). Ni–Co LDH@SnO<sub>2</sub>@RHC@PANI composite\ndemonstrated a good specific capacity of 7684.2 F g<sup>–1</sup> at a scan rate of 10 mV s<sup>–1</sup>. The asymmetrical\nconfiguration of the composite electrode offered a suitable stability\nof 99.5% in 2000 cycles. Supercapacitor devices provided energy and\npower densities at values of 51.3 Wh kg<sup>–1</sup> and 148.7\nW kg<sup>–1</sup>, respectively. As a result, the Ni–Co\nLDH@SnO<sub>2</sub>@RHC@PANI composite that is produced using this\nstraightforward method is a promising component for pseudocapacitors\nbased on the redox mechanism.