以石墨烯與活化的介相碳微球複合材料為電極在超級電容器之應用

Application of Graphene and Activated Mcmb Composites as Electrode Materials for Supercapacitors

本研究以氧化石墨經過熱還原膨脹法製備石墨烯 （G1），並與經KOH 活化的介相碳微球 （MCMB） 依不同的比例共同混摻，作為超級電容器之電極材料，研究其電化學性能的表現。碳材之孔洞特性以氮氣吸附儀測量；以X 光粉末繞射儀 （XRD）、掃描式電子顯微鏡 （FE-SEM） 及顯微拉曼光譜儀 （Raman）分析石墨烯和活化的MCMB （KM） 層間距變化、表面型態及晶體結構。電化學實驗使用電壓電流儀檢測混摻材料於循環伏安法、計時電位法及交流阻抗譜的電化學性能。實驗結果顯示，當摻入KM重量比率為66% （KM-G1-2） 時，於掃描速率與電流密度為5 mVs-1與0.5 Ag-1，其比電容分別為126 Fg-1與130Fg-1。在高電流密度10 Ag-1時，不同比例的混摻材料比電容近乎相似，顯示電化學反應只在電極材料的表面層進行。

In this study, graphene sheets (G1) were prepared by thermal reductionof graphite oxide. The carbonaceous composites were prepared by blendingthe G1 with KOH activated mesophase carbon microbeads (MCMB) byvarious ratios and were used as electrode materials for supercapacitors.The texture characteristics of carbonaceous composites were determined byusing nitrogen adsorption and desorption analysis. The morphology andcrystal structures of graphene were observed by XRD, FE-SEM, andRaman spectroscopy. The electrochemical characterizations are performedby cyclic voltammetry, galvanostatic charge/discharge and AC impedancein a three-electrode system. The specific capacitances of the activated MCMB (KM) and graphene composite (KM-G1-2) with 33%graphene were determined as 126 and 130 Fg-1, at a scan rate of 5 mVs-1and current density of 0.5 Ag-1, respectively. At a high current density of10 Ag-1, however, the specific capacitances of the composites with differentmixing ratios are almost the same. This implies that the electrochemicalreaction is only occurred in the surface layers of the electrode materials.