A Battery With Multiple Personalities

Imara says it won't be pinned down by chemistry.

The startup, formerly known at Lion Cells, says it has designed its new battery in such a way that the company can swap the basic chemistry of the cathode, which in turn will allow it to tailor its batteries for a variety of markets and applications.  It will initially make lithium-nickel-manganese batteries, but it could also do lithium-nickel cobalt or phosphate.

"We're chemistry agnostic," said Jeffrey Depew, CEO, during a visit to their labs. An outside analyst told him it was the only "horizontal battery play" out there, Depew added.

The porous structure of the company's cathode – a three-foot strip of materials covered with chemicals that gets coiled tightly inside a battery – also allows it to insert a high number of lithium ions into its cells. Combine architectural flexibility with a novel cathode and you get power tools can run far longer on a single charge, or that notebook batteries will work as well as they did three years down the road.

"We offer more power, more energy density and significantly more cycle time," he said.

Big claims? Sure, but that's par for the course in the battery world today. The surge of interest in electric cars, renewable energy, and energy efficiency has set off a moon shot-like fever in the battery world. Several startups -- ZPower (zinc silver), PowerGenix (nickel zinc), Boston-Power (lithium deluxe), Altair Nanotechnologies (titanate spinels), A123 Systems (lithium phosphate) – have emerged in the past few years proposing ways to improve or replace the basic lithium-ion battery that came to prominence in the ‘90s (see Boston-Power Gets $55M More to Produce Lithium-Ion Batteries and With GE Snub, Is A123 on the Ropes?).

It won't be easy. Historically, batteries improve about 6 percent a year in performance, compared to 60 percent for things like memory chips and microprocessors. Batteries also tend to be expensive. But it's a huge opportunity. Besides car manufacturers, utilities are clamoring for inexpensive storage solutions. The notebook explosions of 2006 also fulfilled a 2004 prediction that lithium-ion batteries would hit the wall when they did.  

To top it off, Toshiba with its fast-charging Scib battery and other industry stalwarts who already have factories and customers are doing the same (see Green Light post). Although many startups will likely fail, a few could succeed spectacularly.

If anything, demand could easily outstrip supply if a marquee application takes off, said Depew. The manufacturing capacity of cylindrical 18650 cells, about 85 percent of the world's lithium batteries, is 720 million cells. If a car maker decided to come out with a plug-in hybrid, the manufacturer would suck up 200 million to 300 million worth of those cells. "That's just for 100,000 cars," he said.

Imara's initial proof point will come in the third quarter when its first batteries get released commercially. (Production samples are starting to be shipped to select customers.) The company's batteries – which are made up of cylindrical 18650 cells – will first be sold to power tool makers. Generally, power tools require high power cells, i.e. batteries that can deliver lots of power rapidly often at the expense of run-time.

After that, Imara will focus on powering motors on outdoor equipment: lawn mowers, weed whackers and similar devices. Replacing a four-stroke lawnmower engine with a battery-powered motor is equivalent of taking 11 SUVs off the road for an hour, said Neal Maguire, vice president of business development at Imara.

Mower companies don't sell a lot of electric motors today because the lead acid batteries can conk after an hour or so, not good enough for landscapers.

After that, it will try to sell batteries to vehicle makers and utility operators. Utilities want to use batteries to balance out the power coming from generators.

"We don't know which [vehicles or utility applications] will come first," said Depew.

The company grew out of a project at SRI that was created to invent vehicle batteries. The Department of Energy killed the project after the 2000 election. The technology vanquished until 2004.

But back to cathodes. Typically, battery manufacturers are wed to a particular chemical formula for their cathode. If a manufacturer large enough, they might have two separate, competing types of batteries. The cathode chemistry typically defines the personality of the battery much more than the anode, another three-foot strip chemicals coiled up in a battery. (In a battery, electrons traveling from the anode to the cathode are detoured along the way so they can run your cell phone. The amount of positive ions in the cathode determine the electrons that will be attracted to it.)

Lithium-ion phosphate batteries can run at higher temperatures (210 Celsius) before problems occur, higher than the conventional lithium-cobalt-oxide batteries (130 Celsius) batteries used in notebooks.

Lithium-phosphate batteries, however, don't have the same energy density or storage capacity. One of the reasons A123 Systems lost out on the Volt contract with General Motors was overall density: a phosphate pack would have taken considerably more room than the lithium nickel manganese prismatic (i.e., non-cylindrical) batteries selected from LG Chem.

Imara says its batteries can go up to 195 degrees Celsius, or close to the level of phosphates. Phosphates, however, have a 40 percent disadvantage in power density.

If there is a closely matched competitor, it is the well-funded Boston-Power. The company, which has raised $125 million, employs lithium cobalt but has extensively tweaked the basic architecture. The company touts a fast charging cycle and a lifetime that's three times longer than the average lithium-ion cell. Hewlett-Packard has adopted Boston-Power cells for a consumer notebook and others are expected to follow.