Bio-Polymer Derived Activated Carbons for Electrochemical Double Layer Capacitors
In this work, low cost precursors were obtained locally. The precursors were ground and mixed with DI water, and the solution was then sealed in a Teflon lined pressure vessel. The pressure vessel was heated to 200 °C for 24 hours. After the reactor cooled down, the as-synthesized carbons were harvested by filtration and dried in an oven at 120 °C overnight. The morphology of the as-synthesized carbons was characterized by scanning electron microscopy (SEM) as shown in Figure 1. The as-synthesized carbons went through a one-step activation, which increased the surface area to over 1000 m2/g, with 70% micro porosity. Electrodes were made, and tested in 1.8M TEMABF4in PC and 38% sulfuric acid. Cyclic voltammetry (CV) and galvanostatic charge-discharge tests were run on these activated carbons to study the electrochemical performance. The activated carbons showed very nice capacitor characteristics such as rectangular CV curves and very fast charge-discharge rates in both organic and aqueous electrolytes, as shown in Fig 2. The specific capacitance of these materials in organic electrolyte was ~90-120 F/g and had a volumetric capacitance of ~40-60 F/cc, while in aqueous electrolyte the gravimetric capacitance ranged from 180-200 F/g and 100-120 F/cc.