Nickel silicate hydroxide on hierarchically porous carbon derived from rice husks as high-performance electrode material for supercapacitors

Nickel silicate hydroxide on hierarchically porous carbon derived from rice husks is prepared as electrode material for supercapacitors. AAEMs in rice husks and CO₂ promote the development of pores, which act as pore-forming agent and catalyst respectively. The rice husks carbon is used as the substrate and the SiO₂ in rice husks is converted into Ni–Si compound by loading Ni. The C/NiSi-600-1 shows remarkable electrochemical performance with 237.07 F/g at 0.5 A/g. The performance declines with crystalline SiO₂ formed above 900 °C. A high-performance asymmetric water-system supercapacitor device is fabricated by C/NiSi-600-1 and activated carbon. This device shows capacitance of 142 mF/cm² at 4 mA/cm², the energy density of 25.24 Wh/kg at 551.4 W/kg and great cycle stability with 90% after 10,000 cycles. This work provides new insights into the green application of rice husks and promotes the development of electrode materials for supercapacitors.