The electrodes were prepared by mixing the activated carbon, binder, and solvent, and subsequent hot-pressing the resulting dough between two steel plates at 50 o C and 10,000 pounds to obtain 1 mm thick electrodes with a mass loading of 38 mg/cm 2 (Electrode area = 36 cm 2 ). The detailed synthesis and electrodes preparation procedure is discussed in the supporting information (section S1).