Charging lithium-ion batteries at high currents just before they leave the factory is 30 times faster and increases battery lifespans by 50%, according to a study at the SLAC-Stanford Battery Center in California.
Researchers at the center report in a study published in energy research journal Joule that giving batteries their first charge at unusually high currents increased their average lifespan by 50% while decreasing the initial charging time from 10 hours to 20 minutes. This determines how well and how long the battery will work from then on—in particular, how many cycles of charging and discharging it can handle before deteriorating.
The researchers found that factory-charging a new lithium-ion battery with high currents significantly depletes its lithium supply but prolongs the battery’s life. The lost lithium is typically used to form a protective layer called solid electrolyte interphase (SEI) that forms on the surface of the negative electrode during the first charge. However, under fast charging conditions, lithium ions are also consumed during side reactions at the negative electrode. This creates additional headspace in both electrodes and helps improve battery performance and lifespan.
The researchers used machine learning to pinpoint specific changes in the battery electrodes that account for this increase in lifespan and performance, providing insights for EV battery manufacturers looking to streamline their processes and improve their products.
The study was carried out by a SLAC/Stanford team led by Professor Will Chueh in collaboration with researchers from the Toyota Research Institute (TRI), the Massachusetts Institute of Technology and the University of Washington.
“Battery manufacturing is extremely capital, energy and time intensive. It takes a long time to spin up manufacturing of a new battery, and it’s really difficult to optimize the manufacturing process because there are so many factors involved,” said Steven Torrisi, a senior research scientist at TRI who collaborated on the research.
Source: SLAC National Accelerator Laboratory
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