堆疊式透明超級電容之設計研究

Abstract

近年來，超級電容的高功率密度、長期穩定性及廣泛的應用性等優勢逐漸受到注意，因此被視為一種相當具有潛力且重要的儲能元件；然而，超級電容的能量密度的比起電化學電池仍然不足，目前為止已經有許多改善能量密度的方式像是改變電容材料、增加活性面積被提出，而超級電容也被預期能夠達到與電池同等的能量密度。本篇論文分為兩個部分，分別探討全透明超級電容的製備以及堆疊式超級電容的製作。 在雙電層電容材料中，大部分都以碳材(活性碳、奈米碳管、石墨烯等)為主，因為其具有良好的導電性、高比表面積、電化學活性高等優勢。但在所有以碳材製備的雙電層式超級電容中，皆不具備透明性；對於現在越來越多的穿戴式裝置以及高轉換率的太陽能電池，勢必需要一個具有透明性質、快速充放電特性的儲能裝置。此外，印刷技術的應用可以讓超級電容的組裝更為方便、快速，因此，在本研究中的第一部分提出了一種全透明式的印刷超級電容的製備。首先，在奈米纖維素之中添加奈米銀做為導電材料，並且以酸化奈米碳管做為輔助增強電容性質，製備出具有超高透明度的超級電容，其比電容最佳表現可以達到34.6F/g；同時，該元件亦具有良好的充放電倍率性能、機械彈性及循環充放電穩定性。 在本論文的第二部分，研究重點進入提升超級電容的電容能力。由於全透明式的超級電容受到要求所限制，電極電阻、電活性物質必然減少，因此，第二部分的研究嘗試利用摺疊堆積的方式仿造積層陶瓷電容，嘗試在相同的表面積上，製備出性能較高的積層超級電容。總而言之，本研究提出了一種新的全透明式的印刷超級電容的方法，並且為儲能技術方面拓展了一條嶄新的道路。

Supercapacitors have gained a lot of attention due to their unique features like high power, long cycle life and high power density. They act as a link for energy-power difference between a traditional capacitor (having high power) and batteries (having high energy storage). In this perspective, worldwide researches have been dedicated to address this issue and rapid progress has been achieved. The research presented in this thesis consists of two parts, namely, on the preparation of all solid state printed supercapacitor with high transparency and fabrication of origami stack supercapacitor. Among the electrical double layer capacitor materials, carbon based materials such as carbon nanotube, graphene, active carbon are the most widely used materials due to its high conductivity, high aspect ratio and high electrochemical activity. On the other hand, the demands for wearable electronics and solar cell are increasing. It is necessary to find a high transparent energy storage device because all of the carbon based materials lack transmittance. Therefore, in the first part of the thesis, an all printed method was applied for preparing high transparent supercapacitor. Nanocellulose was used to make good dispersion of silver nanowire. Carbon nanotube was used to enhance the ability of capacitance. And then, we used blade coating to fabricate high transparency supercapacitor. A specific capacitance 34.6 F/g was obtained in this study, and it demonstrated reasonable rate capability, flexibility and cycle stability at the same time. In the second part of the thesis, the research focuses on the enhancement of the supercapacitor capacitance. Because of the limitations for high transparency demand, the reduction of electrical resistance and electrochemical activity materials were inevitable. Therefore, we used stack structure like MLCC structure to achieve higher capacitance for supercapacitor at the same surface area. In summary, this study provides a new approach for all printing method supercapacitor with high transparency and pave the way for energy storage innovations.