The issue is calendar life — how many years a battery can be useful, regardless of whether the vehicle in which it’s installed is driven or not. The paper, written by nine authors at Stanford University led by Yi Cui, a materials scientist, found that in extreme testing, lithium-metal batteries lose up to 25% of their lifetime capacity just sitting around.
Major automakers including General Motors and Volkswagen are relying on pure lithium-metal batteries to make next-generation electric vehicles ultra-affordable and allow them to crack the mass market. But the paper waves a gigantic red flag, suggesting that researchers need to heed this potential flaw in order to ensure that lithium-metal batteries work for a full guaranteed lifetime. “If you lose 25%, it’s game over,” said Venkat Viswanathan, a professor at Carnegie Mellon. “At 20%, you already lose the useful life of the battery.”