Abstract
Rational design of advanced carbon nanomaterials with a balanced mesoporosity to microporosity is highly desirable for achieving high energy/power density for supercapacitors because the mesopore can allow better transport pathways for the solvated ions of larger than 1 nm. Inspired by the inherent meso/macroporous architecture and huge absorption ability to aqueous solution of auricularia biomass, we demonstrate a new biomass-derived synthesis process for the three-dimensional (3D) few-layered graphene nanosheets incorporated hierarchical porous carbon (GHPC) nanohybrids. The as-prepared GHPC nanohybrids possess a balanced mesoporosity to microporosity with much improved conductivity, which is highly desirable for achieving high energy/power density for supercapacitors. As we predicted, they delivered a high specific capacitance of 256 F g−1 at 1 A g−1 with excellent rate capability (120 F g−1 at 50 A g−1) and long cycle life (92% capacity retention after 10000 cycles) for symmetric supercapacitors in 1 M H2SO4. Based on the as-obtained carbon materials, a flexible and all-solid-state supercapacitor was also assembled, which can be fully recharged within 10 s and able to light an LED even under bended state. Such excellent performance is at least comparable to the best reports in the literature for two-electrode configuration under aqueous systems.
Highlights
With the size of micropores[10,11]
Inspired by their inherent meso/macroporous architecture and huge absorption ability to solution, we demonstrate a new concept that 3D graphene incorporated hierarchical porous carbon (GHPC) nanohybrids have been successfully synthesized by immersing auricularia into exfoliated graphite oxide (GO) aqueous solution, hydrothermally carbonizing the as-prepared auricularia/GO composite and activating the porous carbon/GO hybrid using KOH
These results indicate our strategy is successful to realize the introduction of graphene into biomass-derived HPC framework, which will greatly improve their electrical conductivity
Summary
With the size of micropores[10,11]. In this regard, despite the great potential of these carbon matrials in providing large surface area for supercapacitor, they can only achieve a specific capacitance in the range of 100–300 F g−1 in aqueous electrolytes with a relatively poor rate capability[7]. The optimized GHPC nanohybrids exhibit high specific surface area (up to 1723 m2 g−1), rich mesoporosity (~75%) and large pore volume (up to 1.85 cm[3] g−1) Such particular structure can provide better transport pathways for solvated ion due to the introduction of more mesopores, and accelerate electron transport rate because of incorporated graphene into 3D porous carbon (Fig. 1), leading to a high specific capacitance of 256 F g−1 at 1 A g−1 and 120 F g−1 at 50 A g−1 with a long cycle life (92% retention after 10000 cycles) in 1 M H2SO4 for symmetric supercapacitors. Such excellent performance is at least comparable to the best results reported to date for two-electrode configuration in aqueous solution
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