Panasonic, Tesla's first battery supplier, plans to start mass-producing 4680 batteries in Japan during the financial year starting April 2023 and is reviewing sites for production in the United States. Tesla plans to use 4680 batteries to power new Texas-built Model Y cars.
Panasonic has developed a way to slow a battery’s degradation at a higher voltage that includes the use of new, more potent additives to the battery’s electrolyte, said Watanabe who is also Panasonic Energy’s executive vice president.
Higher voltages allow for increased ability to store energy but even small increases have also tended to drive outsized declines in battery performance.
“Improving energy density by 20 percent is entirely possible” if Panasonic can deliver on the improvements described, Shirley Meng, a professor at the University of Chicago and chief scientist for the U.S. Argonne National Laboratory’s center for battery science. “I am optimistic about this goal as the research has shown promising data on all those areas.”
The Argonne National Laboratory works with a number of battery manufacturers. Panasonic’s rivals, which include CATL, LG Energy Solution and Samsung SDI, are also working on technologies that promise to deliver batteries that charge faster, run longer and cost less.
Panasonic’s current battery cell for Tesla uses a voltage of 4.2 volts, and Watanabe said a boost to 4.3 or 4.4 volts was possible with a new mix of additives to the electrolyte, the chemical soup that separates the negative and positive charged electrodes.
“If we can get that to 4.5 or 4.6 volts, I think the whole world view in terms of what is possible for EVs would change,” Watanabe said.
Panasonic has also developed ways to prevent what engineers call “microcracking,” small cracks that develop in the positive electrode when a battery is charged and discharged, shortening its useful life. One protective measure includes use of so-called “single-crystal materials” for the battery’s positive electrode, he said.
In addition, Panasonic is working to replace more of the graphite used in battery’s negative electrodes with silicon-based materials to improve that part of the cell, although the trade-off there is the higher cost of silicon, Watanabe said.
“It’s difficult to balance but raising the energy density of batteries requires raising the potential of both electrodes,” he said.