When it comes to energy storage, lead acid can seem so last century — especially compared with nickel-metal hydride (used in the current generation of hybrid cars) and lithium-ion (used in mobile devices today and held by many to be the future of electric cars). Automakers and energy storage startups are racing to create a lightweight battery that won’t interfere with a car’s all-electric range or design, and lead is one of the heaviest elements known to science. It’s not an obvious choice. So does an updated version of the old go-to really stand a chance in a market moving so determinedly toward lithium?
Pennsylvania-based Axion Power International, funded by Quercus Trust, thinks it does. The company’s lead-acid/carbon, or PbC, battery blends ultracapacitor technology with old-fashioned lead-acid batteries. The problem with ultracapacitors for electric vehicles has been low energy density; next to batteries, the amount of power ultracapacitors can store per kilogram doesn’t measure up. But they do excel in charge time and lifespan. Ultracapacitors can handle far more charge cycles than lithium-ion or lead-acid batteries, and they recharge quickly.
From the outside, Axion’s PbC looks much like its lead-acid predecessor. “We’ve just replaced a stack of lead electrodes with a stack of activated carbon electrodes,” Axion CEO Thomas Granville said. (The Economist and Green Car Congress both have done deep dives on Axion’s chemistry, but here’s the short version: Axion replaces the lead-based negative electrodes found in conventional lead-acid batteries with carbon assemblies.) “The only [noticeable] difference is the feel.” He said Axion’s PbC batteries weigh half as much as traditional lead-acid batteries, while offering just slightly less storage capacity.
Perhaps more importantly, PbCs have enough in common with the old technology that they can be assembled with existing lead-acid battery infrastructure. Like the conversion companies that have sprouted up to turn hybrids into plug-ins with battery packs, Axion says it can retrofit conventional trucks and SUVs to have an all-electric range of 40 miles-plus for less than $10,000.
“Obama keeps talking about having a million hybrids on the road by 2012,” Granville noted, adding that even with federal incentives to jumpstart the transition, switching 100 percent of the fleet over to clean, new vehicles would take decades. While PbC batteries may not offer the best long-term solution for electric cars, they do offer a way to clean up vehicle emissions without trading out the entire national fleet. Not surprisingly, Axion favors a three-year, 50 percent tax credit for retrofits, but Granville claims the company does not need aid to cover costs at this point, despite reporting a $2.2 million loss for the third quarter of 2008 (an improvement over the $3 million loss we noted in the first quarter). It landed a $1.2 million military grant in October to develop PbCs for cold-weather Marine and Navy operations, and it does contract manufacturing for lead-acid battery makers.
Moreover, Axion plans to ship out a new mobile energy storage system this year for grid buffering, starting with a delayed New York State Energy Research and Development Authority project in upstate New York, and for peak shaving, starting with a test project at a CUNY campus in New York City.
Next to lithium of course, PbCs are still heavy. But as Axion CTO Ed Buiel told the Economist recently, “Not everyone needs or can afford an electric car that accelerates like a Tesla.” In other words, an electric or plug-in vehicle priced for the mass-market (like those in the pipeline at Tesla, GM, Toyota and Daimler) can afford to carry a little extra weight.
A few years ago, Axion pitched its technology to members of FreedomCAR and Fuel Partnership. But the automakers wanted batteries at a maximum $87 per kilowatt-hour. Granville said Axion’s technology costs $240-$260 per kilowatt-hour, and so the deal went nowhere. Toyota, meanwhile, moved ahead with more expensive technology and took a hefty piece of the hybrid battery market as a result. (Lithium-ion and nickel-metal hydride batteries can cost upwards of $300 per kilowatt-hour.)
“Lithium is the element of the month,” Brian Jaskula, a mineral commodities specialist with the USGS told us in an interview earlier this month. “But something else may come along.” In fact, something else may have already arrived. The new generation of lead batteries don’t have to compete head-to-head with lithium-ion: To have an impact on the auto industry and energy grid, they need only show up, ready for work until other chemistries can take the charge.