錳氧化物奈米複合材料與新穎三維碳奈米結構修飾電極製備及其應用於可撓式非對稱型超高電容器系統之研究

Abstract

在科技進步能源價格高漲的時代，能源材料開發與儲能技術的發展就更顯重要。超高電容器是現 階段受到重視的儲能元件之一，具備可靠性高、壽命長、可急速充放電等優異的特徵，與傳統電池相 比，雖能提供比電池更高的瞬間功率但其能量密度相顯遜色，成為超高電容器未來面臨的主要挑戰。 近年來，錳氧化物為超高電容器(擬電容器)中極具潛力的電極材料，具有價格低廉、無毒性、安全性 高等優點，然而，受限於材料本身導電率不佳，使元件等效串聯電阻ESR 過大，影響超高電容器的有 效儲能量及充放電循環壽命加上單體超高電容器耐電壓有限，因而造成應用上的限制。 根據上述所遭遇到之問題，本實驗室三年之研究計畫將提出改善解決方法，著重於三維新穎混合 型碳奈米網狀結構開發(石墨烯薄片上成長奈米碳管陣列)、低維度奈米複合式電極反應物材料 (Graphene/CNT/MnO2 Nanocomposites)合成、三維碳奈米網狀結構表面改質(氮摻雜)、複合式電極反應物 材料改質(銀原子摻雜錳氧化物)、超高電容器電極製備、超高電容器系統電解液選擇(離子液體)及可撓 式非對稱型正負極材料之超高電容器系統組裝等主題研究，探討其在超高電容器儲能性能及應用。 根據上述七大方向的改善，期待能藉由新穎混合型之碳奈米網狀結構具高比表面積特性並配合改 善奈米錳氧化物在石墨烯/碳管上之附著機制，以獲得較大反應面積及可靠的複合式奈米結構，期待能 開發出具有高功率密度(> 1,000 kW/kg)、高能量密度(> 200 Wh/kg)、寬操作電壓範圍(> 5 V)、高循環次 數 (> 50,000 cycles)及低充電時間 (3~5 分鐘)之高效能可撓式非對稱型正負極材料之超高電容器，隨後 積極於電容器廠配合，將研究的成果具體應用化。

The development of high-performance energy storage systems has sparked interest because of the environmental issues and the decreasing availability of fossil fuels. Supercapacitors (SCs), also named electrochemical capacitors, are supposed to be a promising candidate for alternative energy storage devices as a result of their high rate capability, fast charging/discharging rate, excellent cycle stability, and long cycle life. However, a major drawback of SCs is that they have limited energy density. In recent years, manganese oxide has been widely investigated as a promising supercapacitive material because of its low cost, high electrochemical activity and more friendly environmental nature than other transition metal oxides. However, the poor electrical conductivity of MnO2 and low accessible surface area, cause its charging and discharging cycle life to weaken, and the limited operating voltage of the monomer SCs. The main subjects of this three-year proposal to be investigated include: the development of three-dimensional (3D) carbon-based nanostructures of graphene-carbon nanotube that consists of carbon nanotubes vertically standing on graphene sheets, the surface modification of 3D carbon-based nanostructures (Nitrogen doping), the surface modification of MnO2 nanostructures (Silver doping), the preparation of nanocomposite electrode, the choice of ion liquid electrolyte for SCs system, and properties and application of such flexible asymmetric SCs. After solving the above issues, the nanocomposite electrodes with high surface area and reliable nanostructure will be obtained through utilization of 3D carbon-based nanostructures and improved adhesion between MnO2 and graphene/CNTs. High efficiency SCs with high power density (> 1,000 kW/kg), high energy density (> 200 Wh/kg), high operation voltage (> 5 V), high cycle-index (> 50,000 cycles) and low duration of charging will be expeted to be developed using such nanocomposite electrode and suitable electrolyte.