By Allison Proffitt
July 29, 2020 | At day two of the International Battery Seminar, several speakers shifted focus away from the needs of electric vehicle batteries. Susan Babinec with Argonne National Laboratory highlighted the many ways grid requirements differ from EV needs. Grid applications do not require high energy density, she emphasized. Instead the grid needs more cycles, more calendar life, more safety and lower cost. At Argonne, Babinec and her team are using artificial intelligence to develop rapid cycle life evaluations. The goal, she said, it to move cycle life evaluations from two years to two weeks!
The requirements for batteries for wearables and medical devices are also significantly different than those for electric vehicles, said Lawrence Pan with Fitbit. The most obvious difference: the very small size. In wearables, we care more about volumetric energy density than gravimetric energy density, Pan explained. And as the battery gest smaller, the percentage of battery parts that don’t hold a charge—“overhead” like tabs, packaging, separators, and taping—goes up. Safety devices also take up valuable space in tiny batteries. Among several challenges Pan issued to battery manufacturers: What can we do to improve the energy density for wearable applications? And how can the size of the protection circuitry modules be decreased?
Jack Guo with Philips highlighted the special battery considerations for medical devices. While these devices are extremely complex and diversified—and heavily regulated—Guo pointed out that the market is stable with a long product life cycle. He advocated for designing batteries in this market with a platform architecture and reference design, making it easier to meet the different needs of the devices.
But nearly all speakers agreed that lithium ion EV batteries are doing the most to drive battery costs down and adoption up. And among the most high profile consumer of EV batteries: Tesla. In her keynote, Celina Mikolajczak, now with Panasonic Energy of North America (PENA), gave an update on the cell production at Tesla’s Gigafactory Nevada, where PENA occupies about two thirds of the completed Gigafactory space. PENA shipped its billionth battery cell in February 2019 and its second billionth cell by last November. All of the cells produced by PENA at Gigafactory Nevada are for Tesla.
Improved battery chemistries are important, Mikolajczak said, but cell price reductions really come by cost-effective sourcing and processing of raw materials, high volume pricing on both materials and production equipment, factory automation, and elimination of production stops and process upsets. At Gigafactory Nevada everything is high volume: 8 coating lines, 32 die heads, 46 press machines, 198 winding machines, and much more.
Editor’s Note: Have you missed Days 1 and 2? Registration for the International Battery Seminar and Exhibit is still available and many of the talks are on demand to registered attendees.