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

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 similar to 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 3.75W m(-2) (94.5W 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.