But some ultracapacitor manufacturers aren’t convinced. Maxwell Technologies, one such manufacturer, has agreed to test the new materials, says Michael Sund, vice president of communications and investor relations for the San Diego-based company. But he says that “all of the synthetic materials we have tested are significantly more expensive than activated carbon from organic sources,” so organic activated carbon remains “the best material available to us in terms of having sufficient quantity, and proven performance and cost.” When companies are considering using ultracapacitors in new applications, their biggest concern is cost, “so no way we can pay more for carbon to get a marginal performance improvement,” he says.
EnerG2’s technique for making activated carbon may prove more useful for overcoming some key challenges facing proposed advanced battery designs. Lithium-air batteries and lithium-sulfur batteries could store more than twice the energy of today’s batteries, although that’s still much less than the amount of energy stored in fuels such as gasoline. It’s been challenging to make these batteries practical. Many test batteries stop recharging after only a few cycles, or don’t come close to their theoretical energy-storage capacity because of problems with conductivity or unwanted chemical reactions. Having a precisely controlled pore structure within a carbon electrode could help with many of these problems.
For example, researchers recently demonstrated that well-ordered carbon electrodes–composed of regular rows of carbon nanostructures–allowed for relatively high energy storage in lithium-sulfur battery electrodes by improving conductivity and promoting desired chemical reactions within confined spaces in the material. The techniques for making these electrodes, however, would be expensive. EnerG2’s methods might provide a cheaper way to make such ordered carbon structures.
But these battery technologies still face several other problems, and might not be ready for commercial production for many years, if ever. “There must be a dozen challenges,” says Stanley Whittingham, professor of chemistry and materials science and engineering at the State University of New York, Binghamton. The new activated carbon materials might solve some problems, he says, but then it’s “on to the next issue.”