Promising Nitrogen-Rich Porous Carbons Derived from One-Step Calcium Chloride Activation of Biomass-Based Waste for High Performance Supercapacitors

Abstract

It has long been demonstrated that KOH and ZnCl2 can be used as efficient chemical activation agents to prepare porous carbons. Herein, we develop a green activation method, that is, one-step calcium chloride (CaCl2) activation sugar cane bagasse with urea, for the preparation of nitrogen-rich porous carbons (NPCs). The nitrogen contents, specific surface areas, pore sizes, and specific capacitances of the obtained NPCs can be effectively tuned by adjusting the ratio of carbon precursor (sugar cane bagasse), nitrogen source (urea), and activation agent (CaCl2). The synthesized three-dimensional oriented and interlinked porous nitrogen-rich carbons (3D-NPCs) contain not only abundant porosities which can impose an advantage for ion buffering and accommodation, but also high nitrogen content in the carbons which can obviously increase the pseudocapacitance. Therefore, for the typical sample, obtained from pyrolysis of the mixture of sugar cane bagasse, urea, and CaCl2 in a mass ratio of 1:2:2 at 800 °C for 2 h under N2 atmosphere, shows a high specific capacitance, excellent rate capability (with 323 and 213 F g–1 at the discharge/charge current densities of 1 and 30 A g–1, respectively), and outstanding cycle performance (a negligible capacitance loss after 10 000 cycles at 5 A g–1).

Biomass-derived carbon materials with structural diversities and their applications in energy storage

“…The hierarchical porous carbon has high energy storage capacity and excellent rate capability. So far, various biomass, such as bagasse [113,114], endothelium corneum gigeriae galli [115], silk [98], auricularia [116][117][118], spores [53], lignin [119], cellulose [120], cotton [73], honeysuckle [121], lotus seedpods [59], enteromorpha [122,123], willow catkins [78], sheep manure [124], tobacco rods [125], corn leaf [126], bacterial cellulose [62], have been widely used as precursors to prepare hierarchical porous carbons through carbonization and activation process. Hou et al [98] have prepared hierarchical porous N-doped carbon nanosheets (HPNC-NSs) from natural silk by the metal salt activation-graphitization (Fig.…”

“…Other biomass derived carbons, such as wheat flour [136], stem bark [58], MOB [127], tobacco rods [125], perilla frutescens [34], pine needle [103], had 1 at% nitrogen. In order to increase the nitrogen content of biomass-derived carbon materials, some nitrogen-containing dopants (NH 4 Cl [109], (NH 4 ) 2 SO 4 [137], NH 3 [138], urea [114], melamine [139]) were introduced. Because of the strong electronegativity of nitrogen and the hybridization of nitrogen lone pair electrons with the π electrons in carbon, N-doped biomass-derived carbon material is beneficial to bind the effective charge for energy storage.…”

Bio‐Nanotechnology in High‐Performance Supercapacitors

“…[73a,b] The post-activation treatment method and intrinsic properties of the natural biomaterials are pivotal to controlling the microstructure of biochar and thus influence their electrochemical performances. [18][19][20][21]28,30,33,41] Wu et al [20] have successfully prepared four different SC electrode materials from fir wood and pistachio shell with similar S BET but different pore structures by steam and KOH activation, respectively. The influence of pore structure on the electrochemical performances of SCs was studied, with mainly micropores for KOH-activated carbons and mesopores for steam-activated carbons.…”

“…[35,74] Additionally, KOH, steam, CO 2 , NH 3 , H 3 PO 4 , NiCl 2 , and CaCl 2 were also commonly used as effective activators to achieve the fabrication of high capacitive biochar. [33,37,40,41] Adv. Energy Mater.…”

Aqueous supercapacitors based on carbonized silk electrodes

“…4,6,41 In addition, it also avoids the environmental pollution that results from achieving high nitrogen doping by the addition of a nitrogen source such as urea 34,42 or NH 3 .…”