Eamex Corp is in a hurry to put its high-capacity capacitor to practical use. The capacitor is a solid polymer electrolyte membrane whose surface is metal-plated to form electrodes.
It is a kind of hybrid capacitor. The specific surface area of its electrodes was expanded by improving the plate processing method to enhance the physical absorption effects. And the energy density of the capacitor was increased through an electrochemical reaction caused by using Li ions as electrolyte salt .
Major automakers showed a strong interest in its energy density, which is higher than those of Li-ion secondary batteries. And Eamex allegedly is discussing the commercialization of the capacitor with some manufacturers.
In June 2009, Eamex announced that it achieved an energy density per unit volume of 600Wh/L (See related article), which is equivalent to the energy density of a high-performance Li-ion secondary battery. Though the company did not disclose the details, it increased the specific surface area of the electrodes by 20,000 times by improving plate processing conditions and reduced the thickness of the solid polymer electrolyte membrane from about 60μm to 31μm.
With those methods, the energy density per unit volume was dramatically enhanced. Because the thickness of the plated area, which becomes electrodes, is about 10μm, the positive and negative electrodes are as thick as the solid polymer membrane.
Moreover, the material of the capacitor, solid polymer, contributed to improving the energy density. The solid polymer capacitor, like a Li-ion capacitor, requires a pre-doping process* to absorb Li ions. Because the solid polymer has a negatively charged functional group, it is easy to dope with positively charged Li ions to increase the capacitance.
*Eamex calls the Li-ion injection process "activation." One of the disadvantages of Li-ion capacitors is that this activation process takes too long to complete.
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