Tuesday, June 12, 2012
A123 Systems says it has developed an improved version of its lithium-ion battery cells that could open up new applications for lithium-ion batteries and lower the cost of electric vehicles.
The batteries work better at both high and low temperatures than the company's current batteries. That could make them useful in cars and as backup power for telecommunications towers, A123 says. The new battery design might also allow automakers to simplify or eliminate the liquid cooling and heating systems used in some electric vehicles.
A123 isn't saying much about the details of the new technology, except to say it involves tweaks to both of the battery's electrodes as well as the electrolyte. The new batteries still use a type of lithium-iron phosphate, the chemistry used in A123's conventional cells, and are expected to cost about the same amount to make, says Bart Riley, A123's chief technology officer. He says the new cells will be in commercial production by the beginning of next year.
A123 Systems supplies batteries for the Fisker Karma plug-in hybrid, hybrid buses, and electric grid support. It's fallen on hard times lately, in large part because of an expensive recall campaign to replace defective batteries, but also because it's relied heavily on Fisker, which is itself having trouble. A123 hopes the new cells will bring new customers, but it's also told regulators that because of its dire financial situation, it might not last through the end of the year.
Lithium-ion batteries are lightweight and compact, which makes them attractive for electric vehicles. But cold temperatures can lower their power output, and they degrade quickly when exposed to high temperatures, so automakers often incorporate complex liquid cooling and heating systems into battery packs for electric vehicles. A123 estimates that eliminating those systems could reduce the cost of an electric vehicle by $600, a significant amount, though it's small relative to the more than $10,000 per car for the total battery pack.
The new cells aren't likely to entirely eliminate the need for a cooling system of some sort, since part of the reason for cooling is to keep the batteries from catching fire, says Ahmad Pesaran, a principal engineer at the National Renewable Energy Laboratory in Golden, Colorado. But, he says, a battery that can operate at up to 45 ⁰C, as opposed to, say, 30 ⁰C, could make it feasible to switch from a liquid cooling system, with its complex system of pumps, coolant, pipes, and radiators, to an air cooling system that just requires a fan. He estimates that this might reduce the cost of a battery pack by 10 to 20 percent.
The new batteries could also be used instead of lead-acid batteries in conventional internal-combustion engine cars. Because they could operate at the range of temperatures needed for such a battery inside the engine compartment, the new cells would offer a drop-in replacement, A123 says. They could also be useful in micro-hybrids, cars that use slightly larger-than-normal starter batteries that allow the car engine to turn off at stops and quickly start up again, as well as recover some energy from braking.
Although the initial cost is about $250 more than for a conventional starter battery, A123 says that the economics work out over the lifetime of the vehicle because the batteries last longer than lead-acid batteries and allow for greater fuel savings, since the batteries can capture more energy from braking. This market, however, may be difficult to enter, since car owners may be reluctant to pay higher upfront costs for their cars.
The high- and low-temperature performance could make the batteries suitable for replacing lead-acid batteries in backup power systems for cell towers or in areas, such as India, without a stable supply of power from the grid. A123 says that such an application would offer savings of about 60 percent over lead-acid batteries. These power systems often use diesel generators to charge lead-acid batteries, since the batteries take a long time to charge, and can't be recharged completely from an intermittent grid. But where it takes five hours to charge a lead-acid battery, it would take only 48 minutes to charge A123's batteries, decreasing or eliminating the need for the diesel generator, lowering costs still more.
So far, outside sources haven't verified A123's claims, although initial tests through Ohio State University seem promising—they've shown similar performance at high temperatures, although only for a few hundred charge cycles. A123 claims the batteries maintain 90 percent capacity after charging and discharging at 45 ⁰C for 2,000 charges—the minimum number automakers want for electric cars. Real-world performance of the batteries could be much different than in laboratory tests, so further tests will be needed to confirm the capabilities of the new battery cells.