本研究主要是利用石墨烯作為助導劑並添加於活性碳，以製備活性碳/石墨烯複合電極材料。期望藉由石墨烯之添加、不同石墨烯助導劑的改質、活性碳與石墨烯之間的比例調整，使超高電容器具有更為優異之電化學性質表現。電解液則是選用商業上較常使用的1 M TEABF4/PC (Tetraethylammonium Tetrafluoroborate)/(Propylene Carbonate)做為電解液。 首先探討不同改質之石墨烯助導劑對於超高電容器的影響：本研究將採用四種不同的石墨烯作為助導劑並進行比較，分別為於氮氣的氣氛下將GO以升溫速率5 oC/min升溫至900 oC並持溫1 hr，製備無孔洞石墨烯 (GEs)，以及以升溫速率40 oC /min升溫至900 oC並持溫1 hr，製備多孔石墨烯 (HGEs)。至於氮摻雜之多孔石墨烯 (NHGEs)則是於NO的氣氛下，將GO以升溫速率40 oC /min升溫至900 oC並持溫1 hr後製備而成。此外，本研究也將選用準一維結構之石墨烯奈米條 (GNSPs)作為助導劑，藉以探討維度效應之石墨烯助導劑對於超高電容的影響，並且進一步地針對不同比例之GNSPs助導劑的添加量進行研究，其添加的比例分別為AC：GNSPs = 80：1、40：1、20：1。 在前述四種石墨烯助導劑之中，AC：GNSPs = 40：1具有最為優異之電性表現。由材料分析能夠觀察到：GNSPs屬於準一維結構之石墨烯，且其維度相較於另外三種還原氧化石墨烯 (GEs、HGEs、NHGEs)小；在電化學分析方面，GNSPs優異的導電性與其較小的尺度，將有助於提升超高電容器之電性表現，並改善漏電流等特性。研究結果顯示，AC/GNSPs於電流密度1 A/g時，擁有116 F/g之電容值；於電流密度50 A/g時，仍有54 F/g之電容值；於功率密度31.5 kW/kg時，具有能量密度11.7 Wh/kg，且於六千圈充放電後仍有85%的維持率。相較於AC/GNSPs，未添加石墨烯助導劑之ACs，其高速電容值為21 F/g，且於功率密度31.5 kW/kg時，能量密度僅有4.6 Wh/kg。 ;In this study, a AC/graphene composite was provided which used graphene as additive. Through the addition of graphene, different modifications of graphene additive and the different AC/graphene ratios enhance supercapacitor performance. 1 M TEABF4 in PC was used as commercial electrolyte. Firstly, we studied the effect of different modified graphene additive on supercapacitor. We chose four types of graphene additives: Graphene (GEs) and holey graphene (HGEs) were made by GO with heating rate 5 oC/min and 40 oC/min, respectively, to 900 oC for 1 hr in N2 atmosphere. Nitrogen-doped holey graphene (NHGEs) was produced by GO with heating rate 40 oC/min to 900 oC for 1 hr in NO atmosphere. Besides, we also provided the quasi-one dimension graphene additive (graphene nanostripes, GNSPs) to study the effect of reduced dimension graphene on supercapacitor. Finally, we studied the effect of different AC/graphene ratios. In this study, AC/GNSPs delivers a capacitance of 116 F/g and 54 F/g at 1 A/g and 50 A/g, respectively. At power density of 31.5 kW/kg, the energy density of AC/GNSPs is 11.7 Wh/kg which is around 2.5 times higher than ACs (4.6 Wh/kg). After 6000 cycles, the retention of AC/GNSPs is 85%.
