Activated Biomass-derived Graphene-based Carbons for Supercapacitors with High Energy and Power Density

Abstract

Here, we present a facile and low-cost method to produce hierarchically porous graphene-based carbons from a biomass source. Three-dimensional (3D) graphene-based carbons were produced through continuous sequential steps such as the formation and transformation of glucose-based polymers into 3D foam-like structures and their subsequent carbonization to form the corresponding macroporous carbons with thin graphene-based carbon walls of macropores and intersectional carbon skeletons. Physical and chemical activation was then performed on this carbon to create micro- and meso-pores, thereby producing hierarchically porous biomass-derived graphene-based carbons with a high Brunauer-Emmett-Teller specific surface area of 3,657 m2 g−1. Owing to its exceptionally high surface area, interconnected hierarchical pore networks, and a high degree of graphitization, this carbon exhibited a high specific capacitance of 175 F g−1 in ionic liquid electrolyte. A supercapacitor constructed with this carbon yielded a maximum energy density of 74 Wh kg−1 and a maximum power density of 408 kW kg−1, based on the total mass of electrodes, which is comparable to those of the state-of-the-art graphene-based carbons. This approach holds promise for the low-cost and readily scalable production of high performance electrode materials for supercapacitors.

The synthesis and performance analysis of various biomass‐based carbon materials for electric double‐layer capacitors: A review

“…For example, by pre‐carbonization at 900°C and then activation, the prepared CAs have an SSA of 997 m 2 /g, while by pre‐carbonization at 500°C and then activation, the SSA of the prepared CAs is increased by 47% to 1468 m 2 /g . In addition, high temperature can promote the etching of activating agent, improving not only the graphitic degrees but also the SSA and pore structure of carbon materials as mentioned earlier …”

“…Besides, good conductivity can also offer a low resistant pathway for electron transfer. This means that porous carbons with graphitic structure are superior to amorphous carbons as electrodes in DLECs . Gabhi et al found that the electrical conductivity of biochar was highly dependent on its degree of graphitization.…”

“…Gabhi et al found that the electrical conductivity of biochar was highly dependent on its degree of graphitization. So far, many methods have been used to synthesize porous graphitic carbon materials (PGC), such as catalytic activation of biological waste liquid, sacrificial template methods using SiO 2 , combination hydrothermal, graphitization approach, and so on . Regrettably, a high degree of graphitization often requires dramatically reaction conditions (>1000°C), which would lead to the reduction of SSA due to the excessive activation .…”

“…This means that porous carbons with graphitic structure are superior to amorphous carbons as electrodes in DLECs. 71,72 Gabhi et al 7 found that the electrical conductivity of biochar was highly dependent on its degree of graphitization. So far, many methods have been used to synthesize porous graphitic carbon materials (PGC), such as catalytic activation of biological waste liquid, sacrificial template methods using SiO 2 , combination hydrothermal, graphitization approach, and so on.…”

“…So far, many methods have been used to synthesize porous graphitic carbon materials (PGC), such as catalytic activation of biological waste liquid, sacrificial template methods using SiO 2 , combination hydrothermal, graphitization approach, and so on. 71,[73][74][75][76] Regrettably, a high degree of graphitization often requires dramatically reaction conditions (>1000 C), which would lead to the reduction of SSA due to the excessive activation. 77 It is significant to look for a balance between the SSA and graphitization degree.…”