Manufacturing And Research On Carbon Based Electrochemical Capacitor

Electrochemical capacitor is a new energy storage component between batteries and electrostatic capacitors, which has higher power density than that of batteries and higher energy density than that of electrostatic capacitors. When working with batteries, they can meet with the high power out-put need of electric vehicles when starting-up or accelerating. They can also be used as electric components and power sources for small electrical equipment and direct current switches. Now electrochemical capacitors have become a hot area in researches, and in many countries other than China, electrochemical capacitors have been sucessfully used in electric vehicles. For all purposes, it's very important to have study on electrochemical capacitors for the promotion of electric vehicles in our nation. According to the principle of energy-storage there are two types of capacitors: electric double-layer capacitor and faradaic pseudocapacitor.We conducted a series of experiments to research on electrodes of manufacturing, active material and current collector modification according to the mechanism of energy-storage materials, electrolytes, preparation techniques by the means of the experimental methods such as cyclic voltammetric measurements, constant charge/discharge measurements, impedance spectrums, scan microscope measurements, self-discharge, leakage current, and so on.The results show that: the electrolyte of LiClO₄/PC used in capacitors has coulomb efficiency for 91.86% while LiPF6/EC+DMC has done better in the charge storage capacity. Compared with SBR, the binder of LA132 has done better in adhesion. When 5% LA132 is added in the electrodes, the capacitor performs best. One hour is the best time for the capacitors placed in a vacuum oven to achieve better results. There are other important manufacturing conditions that need for capacitors such as 3.48mL electrolyte for every gram active materials and winding the capacitor through the mixed-assembly which performs less resistance and better capacitance characteristics. The results also show that the modification of the proper current collector can deduce the resistance for 60% between current collector and active materials and increase 16.76% of the utilization of active materials. Meanwhile when suitable surfactant is added to active material, it can be effective to improve the wettability of the electrolyte, increase the rate of utilization of 20.62% active electrode material,reduced 20% of the electron transfer between the electrolyte and active material resistance, and has better performance of the cycle.Both the current collector surface modification and active material modification were used at the same time by selecting the appropriate conditions to manufacture the electrochemical capacitor of large capacity. The testing results show that its electrochemical properties are better than the one that not modified, It can be seen of its better reversibility from CV measurements.