高導電度膠態電解液於固態超級電容之應用

Abstract

近年來，超級電容器成為非常受歡迎的能量存儲元件，其具有高比電容值、高功率密度、快速充放電、壽命長等優點。然而電解液可能會有電解液外漏、封裝體積大、電解液侵蝕等缺點進而導致嚴重的安全問題。為了解決以上問題，固態超級電容器的相關研究開始普及發展。 離子液體具有高電壓窗、低熔點、不可燃、高穩定性等優點，所以可以應用於膠態電解液的製備上。一開始嘗試改變高分子對離子液體的比例，發現在重量比為1:4時，導電度可達到最大值2.74 mS cm-1，為了近一步提高導電度至接近 10mS cm-1，在膠態電解液中我們混入了EC、PC等有機溶劑，增加離子的解離率使導電度可達到8.52 mS cm-1。接著，我們加入了鋰鹽LiClO4進膠態電解液中。另一方面使用高分子PVDF、活性碳粉、奈米碳管制備活性碳電極，在最佳化情況下，將電極及電解液組合成固態超級電容。此電容在0.5A g-1下單電極電容值為78.8 F g-1，能量密度與功率密度在3A g-1下分別為7.71Wh kg-1與 3.747kW kg-1。

In recent years, supercapacitors have become very popular energy storages. There are many advantages of supercapacitors such as high specific capacitance, high power density, fast charge/discharge rate, long lifetime. However, the liquid electrolytes which have some disadvantages such as electrolyte leakage, bulky design, corrosion, and may lead to serious safety issues. In order to solve these problems, the development of all-solid-state supercapacitors related research begins to prevail. The ionic liquids have the advantages of high operation voltage window, low melting point, nonflammable and high stability, so it could be applied to the preparation of gel electrolyte. At the beginning, We attempt to change the proportion of polymer and the ionic liquid and found that the conductivity reached the maximum value at the weight ratio of 1: 4.In order to improve the conductivity to near 10-2 mS cm-1, we mixed EC or PC into gel electrolyte, The conductivity can be increased to 8.52 mS cm-1in EC case. Then, we added the lithium salt LiClO4 into the gel electrolyte. On the other hand, I used PVDF, activated carbon, carbon nanotubes to prepared active carbon electrode. In the case of optimization, we combined electrodes and electrolytes into an all solid state supercapacitor. This supercapacitor has a single electrode capacitance value of 78.8 F g-1 at 0.5A g-1. The energy density7.71 Wh kg-1 at power density of 3.747 kW kg-1.