Credit: Eamax

Credit: Eamax

New developments give hope for producing capacitors with the same energy density performance as lithium-ion batteries.

Researchers at Eamex Corp. of Osaka, Japan, announced that they have produced a solid polymer capacitor with a greater electrode surface area in order to achieve a performance of up to 600 watt hours per liter. Eamex says it hopes the capacitors could ultimately be used in applications such as electric vehicles and notebook computers.

Eamex’s capacitor is a solid polymer electrolyte membrane sandwiched in metal plating electrodes. The company says it has succeeded in increasing the effective surface area of the electrodes, enhancing adsorption.

Capacitors are seen as a possible improvement on battery technology because they could provide higher levels of power and be recharged very quickly (at a fraction of the time a typical Li-ion battery would take).

Although the company admitted, “conditions must be optimized to achieve the 600 Wh/l performance,” the device still provides much greater energy density than existing electric double-layer capacitors.

Eamex claims that in prototypes, it can increase the equivalent surface area by 20,000 times through their proprietary plating techniques. The company announced a capacitor with an energy density per unit volume of 100Wh/L back in December 2008, but the effective surface area was only about 1,000 times larger than that of existing electrodes.

The latest prototype is extremely small, measuring only 0.2 x 0.5 cm with a thickness of 31 μm. In order to commercialize the capacitor, its size must be increased and a stacked structure needs to be developed for larger capacity. Eamax is promoting joint research efforts with other manufacturers that possess the related technologies.