The recent trials and tribulations of The Boeing Co. with its 787 Dreamliner—specifically, potential thermal runaway concerns with its lithium-ion batteries—are being closely watched by the automotive engineering community. The news brings back memories of similar recent issues with the Chevrolet Volt’s battery pack and before that with Sony laptop computers.
By most expert accounts, the potential for lithium-ion batteries is great, but it must be remembered that the technology is still in its infancy. The smartest government and industry minds are busy working on improving the technology for many applications, highlighted by two recent announcements.
The U.S. Department of Energy’s Oak Ridge National Laboratory announced in January that its scientists had developed the first high-performance, nanostructured solid electrolyte for more energy-dense lithium-ion batteries, which could have implications for electric vehicles. Today’s lithium-ion batteries rely on a liquid electrolyte that conducts ions between the negatively charged anode and positive cathode. According to ORNL, liquid electrolytes often entail safety issues because of their flammability, especially as researchers try to pack more energy in a smaller battery volume. Building batteries with a solid electrolyte could overcome these safety concerns and size constraints. ORNL researchers claim that the ability to use pure lithium metal as an anode could ultimately yield batteries five to ten times more powerful than current versions that employ carbon-based anodes.
Also in January, the DOE’s National Renewable Energy Laboratory (NREL) launched the three-year Advanced Management and Protection of Energy Storage Devices (AMPED) program specifically to make EVs more viable options for a larger and wider population of drivers. Its engineers will work with others’ to optimize utilization, life, cost, and safety of lithium-ion batteries for EVs through improved battery management and controls. Funded with more than $7.4 million from DOE’s Advanced Research Projects Agency-Energy (ARPA-E), the three projects are:
• Power management of large battery packs: Led by Utah State University, the goal is reduction in battery size, 20% longer battery pack lifetime, or 20% reduction in battery pack energy content and 50% increase in cold-temperature charge rate. Researchers in NREL’s Center for Transportation Technologies and Systems will work with the Utah State team to develop hardware and control software for an advanced plug-in hybrid-electric vehicle battery management system to maximize the cell lifetimes. Other project partners include the University of Colorado and Ford.
• Battery management system design: Led by Washington University, the targets are a 20% increase in utilization of untapped lithium-ion battery capacity at the cell level. The Washington team will develop a predictive battery management system with innovative control hardware that uses advanced math models to optimize battery performance.
• Predictive battery management for hybrid vehicles: Led by Eaton Corp., the project seeks a 50% improvement in fuel economy of heavy-duty hybrid EVs without sacrificing battery life. Eaton will collaborate with NREL to develop a power control system to optimize the operation of commercial-scale hybrid-electric vehicles, integrating NREL battery life predictive models with Eaton control algorithms. The planned approach provides a cost-effective solution that reduces the size of the battery needed for operating large hybrid-electric vehicles with no loss in battery life or vehicle performance.
The advanced technologies developed under the AMPED and other programs could unlock enormous untapped potential in lithium-ion performance, safety, and longevity. The hope is that these projects will accelerate the safety, security, and economics of batteries, electric vehicles, and the grid.