Energy & Fuels · 2010 · 47 citations · 32 references
Natural SciencesChemical EngineeringMaterials ScienceElectrochemical EngineeringElectrochemistryInterface ScienceActivated Carbon TreatmentCarbon-based Energy MaterialsCatalytic MaterialsElectrode MaterialsSupercapacitorsSurface AdsorptionActivated CarbonCapacitorsElectric Double LayerElectric Double-layer CapacitorsPore Network StructurePore StructurePore VolumeSpecific Surface Area
Activated carbons (ACs) are obtained by microwave-assisted activation of petroleum coke with KOH as an activation agent and used as electrode materials for electric double-layer capacitors. The pore structure and functional groups of ACs are characterized by Fourier transform infrared spectroscopy and the nitrogen adsorption technique. The results show that both the specific surface area ( S BET ) and the total pore volume ( V t ) of ACs go through a maximum as the KOH/coke mass ratio increases. At 5:1 of the KOH/coke mass ratio, S BET of AC (denoted as AC5/1) made by microwave-assisted activation is 2312 m 2 g −1, with V t of 1.13 m 3 g −1, while S BET of AC made by conventional activation is only 532 m 2 g −1, with V t being at 0.24 m 3 g −1 . The microwave-assisted KOH activation process is capable of creating and enlarging micropores of petroleum coke by increasing the KOH/coke ratio from 3:1 to 5:1. Nevertheless, some micropores are destroyed when the KOH/coke ratio is 6:1. The specific capacitance of AC5/1 electrode remains at 246.0 F g −1 even after 1000 charge−discharge cycles. For the capacitor made of AC5/1 or AC3/1 heated at 1073 K, the energy retention ratio after 1000 cycles is 75.1 or 79.6%.
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Anomalous Increase in Carbon Capacitance at Pore Sizes Less Than 1 Nanometer
John Chmiola, Gleb Yushin, Yury Gogotsi et al. · Science · 2006 · 3.9K citations
Natural Sciences, Materials Engineering, Materials Science +17