- 學位論文
應用於鋰離子電容器之氮摻雜石墨烯/奈米碳管複合材料之製備與性質研究
Preparation and Characterization of Nitrogen-doped Graphene/Carbon Nanotubes Composite for Lithium-Ion Capacitors
若您是本文的作者，可授權文章由華藝線上圖書館中協助推廣。
摘要
本研究將氮摻雜石墨烯(Nitrogen-doped graphene, NGR)結合奈米碳管(Carbon Nanotube, CNT)之複合材料應用於一新穎概念之儲能元件—鋰離子電容器(Lithium ion capacitor, LIC)。本研究之第一部分將製備NGR電極材料運用在LIC中，製備方法是使用具有苯環結構之三聚氰胺(Melamine, MA)作為氮前驅物，利用快速高溫退火之方法來製備NGR，其過程結合共價鍵轉換、快速膨脹與熱還原之概念，藉由氮原子之摻雜來改善石墨烯系材料之儲能特性，應用在LIC中具有良好之電化學之表現。本研究之第二部分為改善NGR材料堆疊的問題，以化學鍵鍵結的方式連結酸化奈米碳管(Acid-modified carbon nanotube；AOC)，製備出複合材料[NGR-CNT]，成為一3D立體結構之電極材料，最後，將此材料應用於LIC鈕扣型電池中，並用來發電LED燈泡。 電極材料NGR與[NGR-CNT]藉由SEM、XPS、FT-IR、XRD以及BET等分析證實基本材料性質。以SEM表面型態圖觀察到表面皺褶且蓬鬆多孔結構之NGR與CNT均勻地分布於NGR之[NGR-CNT]之表面型態。XPS分析證實氮原子確實摻入六角之碳苯環中，而[NGR-CNT]氮圖譜中pyrrolic-N比例與氮摻雜之含量上升，證實材料已成功地以醯胺鍵連接NGR與CNT。另外，從FT-IR可以再次證實[NGR-CNT]之醯胺鍵的產生。快速膨脹退火之方式可以有效地合成具有大比表面積與良好孔洞性結構之NGR，比表面積為671.7m2g-1，介孔洞與微孔洞，含量比例分別為49.3 %和45.8 %；而[NGR-CNT]比表面積為820.9 m2g-1，介孔洞與微孔洞比列分別為66.47%和32.32%，此現像可增進與電解液離子間之接觸，介孔洞可以使鋰離子在NGR中，快速地進入孔洞中，而微孔洞可以提供大量的空間儲存大量的鋰離子，增加電荷之儲存。 電化學性能之分析，首先是以一般商用電解液(1M TEABF4/PC) 系統中，分析NGR、活性碳(Activated carbon；AC)及石墨(Graphite)之電化學性質，其中，在5mVs-1掃描速率下，NGR之電極材料具有最高之比電容值約為 183.1Fg-1。再將NGR應用於LIC作為其正極與負極之材料，並與石墨(Graphite)及活性碳(Activated carbon；AC)做搭配之LIC做比較，可以顯示NGR可以儲存較多之電量，並且其循環穩定性極佳，於1Ag-1之電流密度下，經過1000迴圈之充放電下，仍有92.6%的電容值維持率；於1Ag-1之電流密度下，功率密度為1.5kW kg-1，能量密度可達57.6Wh kg-1。 [NGR-CNT]應用於LIC系統中，於1Ag-1之電流密度下，經過1000迴圈之充放電下，仍有93.5%的電容值維持率；於1Ag-1之電流密度下，功率密度為1.5kW kg-1，能量密度可達71.7Wh kg-1。上述之結果可以說明NGR與[NGR-CNT]對於鋰活性離子之充放電機制具有良好且可逆之電化學反應，使得此種LIC具有高能量密度的特性，並且保有超級電容器之高功率密度的特性。
並列摘要
The lithium ion capacitor (LIC), combining supercapacitors with lithium-ion batteries, has drawn considerable attention as a new class of energy storage system. Typically, LIC was composed of graphite as anode and activated carbon (AC) as cathode, which energy density is limited by the small capacity of AC cathode. To overcome this limitation, the innovative electrode material – nitrogen-doped graphene (NGR) is prepared. Doping heteroatoms such as nitrogen into graphene can improve the conductivity and electrochemical properties of the electrode material. However, NGR has the problem of agglomeration due to the restacking force between the NGR sheets, which limits the specific surface of NGR. In order to further improve the properties of NGR, carbon nanotubes (CNTs) are added into NGR to connect each layer of NGR sheets. Bridging NGRs with CNTs is proposed in this study, namely [NGR-CNT], with lamellar structure by amidation reaction. CNTs attached onto the edges and the surface of NGR not only act as spacers to increase the electrolyte-accessible surface area, but also provide a 3-D electrical conductive paths. The characteristics of the configuration, the surface area, the pore distribution and the electrochemical analysis of NGR and [NGR-CNT] for LICs are investigated. The LIC employing [NGR-CNT] shows high cycling stability that capacitance retention remains 93.5% at scan rate of 200mVs-1 after 1000 cycles. Moreover, LIC exhibits high energy density of 71.1 Whkg-1 at a power density of 1.50 kWkg-1, operated in the voltage of 1.5-4.5V. Consequently, [NGR-CNT] is the promising electrode material for high performance LIC.
並列關鍵字
無資料參考文獻
[2] WoodMackenzie. BP Statisitics Review 2005.
[3] CO2 emissions from fuel combustion. International energy agency. 2013.
[4] Simon P, Gogotsi Y. Materials for electrochemical capacitors. Nature materials. 2008;7:845-54.
[5] Qu W-H, Han F, Lu A-H, Xing C, Qiao M, Li W-C. Combination of a SnO 2–C hybrid anode and a tubular mesoporous carbon cathode in a high energy density non-aqueous lithium ion capacitor: preparation and characterisation. Journal of Materials Chemistry A. 2014;2:6549-57.
[6] Geim AK, Novoselov KS. The rise of graphene. Nature materials. 2007;6:183-91.