A discovery at Ohio State University poses new questions about the functional lifetime of a typical lithium-ion battery as used in a hybrid or battery electric vehicle.
A couple of Buckeye engineers found that, over time, a battery's lithium accumulates on the sheet of copper that serves as a "current collector" that transfers energy. With lithium ions traveling between the anode and cathode, lithium was previously thought to collect only on the anode's surface as the battery ages.
The issue of battery life and energy retention has been a major one as automakers offering electric-drive vehicles need to assure potential buyers that the newfangled car's battery life will equal or exceed the timeframe of typical vehicle ownership. General Motors gives an eight-year, 100,000-mile warranty on the batteries in the Chevrolet Volt extended-range plug-in (longer in California), while Nissan has said the battery pack for the all-electric Leaf will have 80 percent capacity after five years and 70 percent after a decade. Nonetheless, Nissan has been getting flak from a group of Leaf owners in Arizona who said their cars' battery capacity was shrinking more quickly than advertised. Perhaps OSU's research will help future electric vehicles avoid similar complaints.