tailieunhanh - Synthesis, characterization and electrochemical performance of activated carbon supported Mno2 for electrochemical capacitor

All the results indicated that the differences of the performances of MnAC electrodes from the different stirring methods arose from the different microstructure characteristic and the metal oxide loading of MnAC samples. | Vietnam Journal of Science and Technology 56 (5) (2018) 582-593 DOI: SYNTHESIS, CHARACTERIZATION AND ELECTROCHEMICAL PERFORMANCE OF ACTIVATED CARBON SUPPORTED MnO2 FOR ELECTROCHEMICAL CAPACITOR Luong Thi Thu Thuy, Le Van Khu, Nguyen Thi Kim Lien Faculty of Chemistry, Hanoi National University of Education, 136 Xuan Thuy St., Cau Giay Dist., Ha Noi * Email: thuyltt@ Received: 20 December 2017; Accepted for publication: 1 September 2018 Abstract. MnO2 was synthesized by adding activated carbon into KMnO4 solution and stirred in a magnetic or ultrasonic stirrer. The obtained MnAC samples were characterized by means of XRD, TGA, TPR-H2, SEM and BET. All samples are amorphous and have porous structure. MnAC-M prepared by magnetic stirring have higher manganese content, earlier reduction temperature, smoother surface area while MnAC-U prepared by ultrasonic stirring have larger specific surface area and pore volume. Electrochemical studies revealed that at low scan rate the specific capacitance of MnAC-U is larger than that of MnAC-M, while at high scan rate the specific capacitance of MnAC-M is higher. All the results indicated that the differences of the performances of MnAC electrodes from the different stirring methods arose from the different microstructure characteristic and the metal oxide loading of MnAC samples. Keywords: electrochemical capacitor, activated carbon, manganese oxide, magnetic stirring, ultrasonic stirring. Classification numbers: ; 1. INTRODUCTION Along with the development of sustainable energy which has intermitten nature, the need of energy storage system has grown dramatically in recent years. Due to the high power density, excellent reversibility and long cycle life, electrochemical capacitors have been attracting worldwide attention. Based on the charge storage mechanisms, electrochemical capacitor can be classified into two groups: i) Electric double layer capacitor (EDLC) that uses .