Strengthening the competitiveness of the American transportation industry relies on developing domestically produced electric vehicle batteries that enable rapid charging and long-range performance. The energy density needed to extend driving distance can, however, come at the expense of charging rates and battery life.
By integrating a new type of current collector, which is a key battery component, researchers at the Department of Energy's Oak Ridge National Laboratory have demonstrated how to manufacture a battery with both superior energy density and a lasting ability to handle extreme fast charging. This enables restoring at least 80% of battery energy in 10 minutes. By using less metal, particularly high-demand copper, the technology also relieves strain on U.S. supply chains.
"This provides a significant savings on near-critical materials, because much less copper and aluminum are needed," said lead researcher Georgios Polyzos. "At the same time, this will greatly enhance the energy density achievable with a 10-minute charge."
A current collector conducts electricity from the active material within the battery to an external circuit. Current collectors are generally made of metal foil, with one at each pole of the electrode: copper for the anode and aluminum for the cathode. The metals add weight to the battery, increasing the overall weight of the car and the amount of energy required to move it.
The novel current collector, made by industry partner Soteria Battery Innovation Group, is a polymer sandwiched between very thin layers of copper or aluminum. ORNL researchers found that this new component can reduce current collector costs by 85%, pack in 27% more energy for longer trips, and maintain significant energy density after a thousand cycles, even under extreme fast charging conditions that can degrade battery materials more rapidly over time. The new current collector performs as well as its conventional counterpart at about a quarter of the weight, enabling an EV to travel farther on the same charge.
To ensure the technology could be scaled up for commercialization, ORNL researchers made coin and pouch cell batteries using industry-standard processes at ORNL's open-access Battery Manufacturing Facility .
Polyzos said the team pinpointed parameters for successfully incorporating the thinner material into the roll-to-roll production process, despite its being more prone to wrinkling. Other experimental current collectors have generally required expensive and complex manufacturing processes that are incompatible with standard roll-to-roll methods.
ORNL's study results, published in Energy & Environmental Materials , highlight the potential of the metal-polymer current collector to "revolutionize the roll-to-roll battery manufacturing process and significantly advance the performance metrics of lithium-ion batteries in electric vehicle applications."
Brian Morin, CEO of South Carolina-based Soteria, said ORNL has helped the company understand how to achieve rapid battery charging with the technology, despite increased physical resistance from the plastic film.
"We take 80% of the metal out, which makes it harder to do things quickly," Morin said. "But they've shown that you can still get fast charge and discharge. Soteria's testing has shown the polymer also makes the battery safer. If there is an internal short circuit that produces a brief rush of energy, it eats the plastic film, which pulls the metal away. Our current collector acts like a circuit breaker inside the battery and eliminates about 90% of lithium-ion battery fires caused by short circuits."
The metalized polymer current collector research was funded through DOE's Advanced Materials and Manufacturing Technologies Office, or AMMTO. Other ORNL researchers involved in the project include Sergiy Kalnaus, Sabine Neumayer, Wheatley Steenman and Jaswinder Sharma.
UT-Battelle manages ORNL for the Department of Energy's Office of Science, the single largest supporter of basic research in the physical sciences in the United States. The Office of Science is working to address some of the most pressing challenges of our time. For more information, please visit energy.gov/science .
