Can 500-mile lithium-air car battery make gas obsolete?

2013-03-11 17:27:43

Editor: John Roach


The days of gas-guzzling cars may come to an end before we run out of oil if technologies such as 500-mile-per-charge lithium-air batteries become a real and affordable option. A company that customizes carbons at the molecular level believes it can help us get there.

Along the way, the same process the company employs to manufacture carbons for prototype lithium-air batteries is being used to improve the efficiency of batteries in gasoline and hybrid-electric vehicles, making a dent in carbon emissions.

For example, Seattle-based EnerG2 is developing carbons that improve the life cycle of lead-acid batteries at the heart of so-called "start-stop" hybrid vehicles. These cars work like gas-fueled golf carts: punch the accelerator and the engine starts; come to a full stop and the engine idles off.

“That gives you about an 8 to 12 percent boost in fuel economy,” Rick Luebbe, EnerG2 co-founder and CEO, told me in an interview at the company’s headquarters.

The company manufactures a highly pure carbon with a precisely tailored pore structure that’s an additive to lead acid battery chemistry. This has led to a ten-fold improvement in the life cycle of the batteries, a key step to bringing down the cost of the technology and accelerating its adoption.

The carbon adds about $3 to $7 to the cost of a battery, Luebbe noted, but with a 10 percent boost in fuel economy it will pay for itself quickly. He expects the start-stop technology to be in most new cars within a few years.

“And it looks like our carbon is going to be one of the key enablers to make that work in a more cost-effective way,” he said.

Custom Carbons
Carbon comes in many forms — from diamonds to graphite to coal. Each form is determined by its molecular structure. The technology at the heart of EnerG2 is a platform that enables the customization of carbon structures at the molecular level.

“The way those carbons are structured really determines how good they are in an application,” Luebbe said. “We then realized that how a carbon is structured is really a reflection of the molecular structure of the precursor.”

The precursor is the source of the carbon. Coconut shells are the precursor for the porous carbon electrodes in ultracapacitors, for example. 

"Coconuts didn’t evolve with the intent to be involved in ultracapacitors," Luebbe noted.

Thinking there had to be a better way, EnerG2 modeled the ideal structure of a porous carbon for ultracapacitors and then built a precursor to match it. They make the precursor out of polymer materials commonly used as binders in the forest products industry for things such as particle board.

“We address the polymerization reaction with different catalysts and with different ratios of inputs in order to get that molecular structure that we want,” Luebbe explained.

This polymer is freeze dried, which removes solvents while retaining its shape, and then carbonized – cooked under high heat. “We are left with a pure carbon material that is structured the way that we want,” he said.

These custom tailored carbons, in turn, lead to ultracapacitors with a higher energy performance than their coconut-shell-based cousins.

Current and Future 
EnerG2 is currently working with about 60 companies in the ultracapacitor and lead-acid industries, Luebbe said. In addition, the carbon pushers are in talks with makers of lithium-ion and lithium-air batteries. 

The hurdle with lithium-air batteries is making them actually work as promised. IBM, which is plowing untold millions on its own lithium-air technology, recently announced success in the lab but said much more work is required before any such battery stands a chance in the real world.

EnerG2 is not working with IBM on its effort, but is collaborating with “some smaller companies” in the space as well as major car companies who see the technology as the next big thing, Luebbe noted.

None of these companies is expected to have a commercially available lithium-air battery anytime soon. 

One of the key hurdles is recharging the batteries, which generate energy via a chemical reaction that combines oxygen breathed in from the air and lithium ions, creating lithium peroxide. To recharge the battery, the lithium peroxide needs to cross a separator that returns the oxygen to the air.

This recharging process has proven difficult. Luebbe thinks EnerG2’s technology can tailor carbon pores in such a way that they “change the reaction kinetics of the reversibility.”

And this wonky bit of chemistry, enabled by a proprietary technology, is what gets Luebbe most excited when speaking about the future prospects of his company, which was founded in 2003.

"If we can make a lithium-air battery work commercially, then we can obsolesce gasoline as a transportation fuel," he said.