Other U.S.-based sodium-ion startups have floundered of late. Natron Energy canceled plans to produce sodium-ion battery cells in North Carolina last year after funding difficulties. Bedrock Materials, which was making sodium-ion batteries for EVs, also closed up shop, citing a bet on a lithium supply shortage that hadn't panned out. But Peak Energy's model is different, said Mossburg. Unlike Natron, it won't be trying to make the batteries that go into their systems at first.