Aqueous ammonium ion-based (NH4 +) hybrid supercapacitors (AAHSCs) are attracting great attention because of their excellent electrochemical performance and environmental friendliness. Silicon nanowires have attracted extensive attention due to their unique physical/chemical properties that make them appealing in emerging energy conversion and storage applications. In this work, porous silicon nanowires (p-SiNWs) were used as scaffolds to coat RuO2 nanospheres by hydrothermal treatment. The as-prepared RuO2 nanospheres completely encapsulate the silicon nanowires, providing abundant active sites for NH4 + attachment. The O-atoms in RuO2 combine with NH4 + to form hydrogen bonds (H-bonds), which greatly improve the electrochemical performance by promoting the charges transport through H-bonds formation/breaking during charging/discharging. In comparison with pure p-SiNWs, RuO2@p-SiNWs electrode exhibits a higher areal capacitance of 128 mF/cm2 at 0.1 mA. The capacitor is prepared with RuO2@p-SiNWs as the cathode and activated carbon (AC) as the anode, separated by (NH4)2SO4 electrolyte, achieving an aerial capacitance of 35.9 mF/cm2 at the current of 0.2 mA. The proposed concept opens new avenue for developing advanced high-energy-density cathode materials for AAHSCs.
Keywords: RuO2; ammonium ion; hydrogen bonds; silicon; supercapacitors.
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