Cobalt-nickel silicate hydroxide on amorphous carbon derived from bamboo leaves for hybrid supercapacitors

Abstract

3D hierarchical cobalt-nickel silicate hydroxide/C (CoxNi3−xSi2O5(OH)4, denoted as CoNiSi) composites are derived from bamboo leaves and explored as electrode materials for supercapacitor. The CoNiSi architectures with hierarchical petal-like shapes are in-situ generated on 3D amorphous carbon derived from bamboo leaves using the biomass-inherent SiO2 species as the silicon source. The CoNiSi/C electrode shows a 3D hierarchical porous structure, high specific surface area and remarkable electrochemical performance with 226 F g−1 at 0.5 A g−1 in the voltage window of −0.8 ~ 0.6 V, which is superior to the specific capacitances of SiO2/C, CoSi/C, NiSi/C and even the reported values of silicates-based materials. It also achieves excellent cycling performance with 99% after 10,000 cycles. Moreover, a high-performance solid-state hybrid supercapacitor (HSC) device is fabricated by CoNiSi/C and Ni(OH)2. This HSC device achieves an outstanding electrochemical performance with the capacitance up to 254 mF cm−2 (64 F g−1) at 2 mA cm−2, and the energy density up to 0.793 Wh m−2 (20.0 Wh kg−1) at 3.75 W m−2 (94.5 W kg−1), which are higher than a majority of former SCs based on silicates. Besides, the HSC device shows good cycle stability with 82% after 10,000 cycles and can light the red LED lasting for more than 2 min. These features demonstrate that the 3D CoNiSi/C architectures can be considered as a promising and efficient material for SCs with high performance.