具多孔矽結構/石墨烯/RuO2複合電極之抗壓耐震型超級電容的開發

Supercapacitors have the advantages of rapid charging/discharging, high power density and long life time, applicable to the fields of mobile communications, vehicle transportation and smart grid. Most current fabrication techniques of supercapacitor utilize planar metal electrodes, appended 3D porous carbon structures such as carbon sponge, carbon aerogel or electrospun carbon fiber. By increasing the specific surface area of the carbon active materials, the power density of the supercapacitor can be improved. However, these planar metal/porous carbon structures will produce serious delamination or collapse failure under large stress, high-speed impact and vibration, making it cannot be applied to the fields which demands load-bearing and anti-shock, like defense industry, aerospace technology, and electric vehicles. Therefore, this project will use porous silicon as the electrode structure and then deposit a carbon film as a passivation film and increase the conductivity. The electrolyte is prepared by mixing graphene flakes, electrolytic salts, transition metal oxides and polymer, then penetrated into the porous structure and heat curing to develop a high load-bearing and anti-shock supercapacitor. The working items of this project are as followed: 1. Development of porous silicon/carbon film composite electrode: To fabricate the silicon porous arrays/silicon composite structures using an electrochemical etching technique, and the silicon nanopillar arrays/silicon composite structures using a catalytic etching technique, which are used as load-bearing electrodes. Low-resistance porous silicon structures themselves have good conductivity and large surface area, which will largely increase the contact area with the electrolyte. The thickness of porous silicon is about 170 microns and their pore diameter is about 2~3 microns. Porous silicon surface will then be deposited a carbon film by CVD for increasing its chemical stability and conductivity. 2. Development of high efficiency solid electrolyte: The electrolyte will be formed by using polymer materials as substrate, mixed with graphene flakes, further doped with transition metal oxide (RuO2), etc. Coated on the surface of porous silicon, placed the specimen in a vacuum chamber, and the polymer electrolyte is infiltrated into the porous silicon structures by means of vacuum suction, and then the solid electrolyte can be formed by heat curing. 3. Supercapacitor assemble and performance evaluation: Two porous silicon electrode plates penetrated with solid electrolyte are appropriately pressed and assembled, then fixed with a PDMS to complete the fabrication of load-bearing and anti-shock supercapacitors. The electrochemical characteristics will be evaluated by cyclic voltammetry, including charge-discharge cycle life (V-T), specific capacitance (Fg-1)-current (Ag-1), power density (Wkg-1)-energy density (Wh kg-1), vibration performance difference test, etc. Expected characteristics are specific capacitance ≧ 1.5 Fg-1 , power density ≧207 Wkg-1-energy density ≧0.115 Wh kg-1 ,and the static and dynamic mechanical stresses can withstand at least 15 kPa, the vibratory accelerations above 30 g will not be delaminated.