Chevrolet Volt and battery: A T-shaped Chevrolet Volt battery replica (left) is positioned near a 2011 Chevrolet Volt electric vehicle. The car's lithium-ion battery is based on technology developed at Argonne National Laboratory. Image: Flickr/Argonne National Laboratory
Researchers from around the world are gathering this week in New Orleans at the American Chemical Society's meeting to present more than three dozen reports on lithium-ion battery technology, highlighting improved components, better performance and more efficient production cycles.
This year's theme for the meeting is food and energy. Lithium-ion technologies make up a large part of the proceedings because energy storage is a crucial enabling technology for clean energy systems, such as powering electric vehicles and smoothing out electricity from wind and solar generators.
But as the recent battery troubles on the Boeing 787 Dreamliner illustrate, many of the products on the market leave much to be desired.
"The biggest hurdle is cost," said Arumugam Manthiram, director of the Texas Materials Institute at the University of Texas, Austin. This isn't just a battery's sticker price, he explained. Energy storage devices have to last long enough to provide a financial payback.
For cellphones and laptops, lithium batteries are very effective, since most consumers upgrade before the battery wears out. The batteries also make up a small fraction of the device's weight and cost, regulating small amounts of energy.
Contrast this with cars, where a battery can ring up as high as $15,000 and can double the weight of smaller vehicles. They also soak up and disperse large electricity surges, so engineers need to invest more time and resources to ensure the batteries are safe, pushing the price tag higher.
Manthiram is presenting some of his research on battery materials at the meeting that can resolve some of these problems. "Materials are the bottleneck," he said. "We do not [yet] have the magic material that will store a large amount of energy at low cost, will cycle for long and will not charge for long."
Battery disposal and recycling research
One approach is to use a better anode. Current lithium-ion batteries use an anode made of graphite. When you charge the battery quickly, especially in a cold environment, the lithium ions can plate on the anode, forming tree-like projections called dendrites. If the dendrites get long enough, they can touch other battery components, creating a short circuit that will make the battery fail.
Using an antimony-based nanocomposite anode, Manthiram said he could design a safer, more durable battery that tolerates higher voltages. Manthiram said he is also investigating other battery chemistries, like lithium-sulfur and sodium-ion, which use different materials and offer their own advantages. This way, engineers can reduce costs over the lifetime of the battery.
Disposing of dead batteries is another important research area. Yan Wang, an assistant professor at Worcester Polytechnic Institute, is presenting his work on improving recycling for lithium-ion systems. He explained that lithium batteries are already an $11-billion-per-year industry that some analysts expect will grow to $50 billion annually by 2020. As more electric vehicles hit the road and more wind turbines start spinning, the demand for batteries and their raw materials will explode.
However, there may not be enough lithium to go around, and American manufacturers will have to look to foreign sources as domestic supplies dry up. In addition, simply dumping aged lithium cells into landfills runs the risk of releasing hazardous chemicals into the environment.
Recycling then becomes the most appealing solution, but breaking down lithium batteries can be expensive, since separating the components is tedious and requires high-energy appliances like furnaces.
Wang is working on a low-temperature process that uses acids and solvents to break batteries down into useful elements like iron, nickel, cobalt, manganese and lithium. Exploiting their different physical properties, the process can pull away the more easily separable compounds.