Ruthenium oxide/activated carbon composites for electrochemical capacitors

Activated carbon (AC) was prepared from lignite by microwave heating ZnCl2. The pore structure parameters of AC are characterized by nitrogen adsorption technique. The AC and ruthenium oxide/AC composite are characterized by thermogravimetric analysis and transmission electron microscope. Electrochemical properties of ACs and ruthenium oxide/AC composite electrodes were investigated by cyclic voltammetry and constant current charge-discharge after AC was pre-oxidized by HNO3 solution. The results show that the specific surface area and total pore volume of AC from lignite reaches 1310 m(2) g(-1) and 0.80 cm(3) g(-1), respectively. The micropore volume of AC from lignite totals only 12.5%. AC and ruthenium oxide/AC composite electrodes with 5wt.% ruthenium oxide loading show high cycle stability. Compared to pristine AC electrode, specific capacitance of ruthenium/AC composite electrode and energy density of ruthenium/AC capacitor after 100 charge-discharge cycles increases 40.8% and 39.1%, respectively.