Researchers figure out how to get fresh lithium into batteries

In their testing, they use a couple of unusual electrode materials, such as a chromium oxide (Cr₈O₂₁) and an organic polymer (a sulfurized polyacrylonitrile). Both of these have significant weight advantages over the typical materials used in today’s batteries, although the resulting batteries typically lasted less than 500 cycles before dropping to 80 percent of their original capacity.

But the striking experiment came when they used LiSO₂CF₃ to rejuvenate a battery that had been manufactured as normal but had lost capacity due to heavy use. Treating a lithium-iron phosphate battery that had lost 15 percent of its original capacity restored almost all of what was lost, allowing it to hold over 99 percent of its original charge. They also ran a battery for repeated cycles with rejuvenation every few thousand cycles. At just short of 12,000 cycles, it still could be restored to 96 percent of its original capacity.

Before you get too excited, there are a couple of things worth noting about lithium-iron phosphate cells. The first is that, relative to their charge capacity, they’re a bit heavy, so they tend to be used in large, stationary batteries like the ones in grid-scale storage. They’re also long-lived on their own; with careful management, they can take over 8,000 cycles before they drop to 80 percent of their initial capacity. It’s not clear whether similar rejuvenation is possible in the battery chemistries typically used for the sorts of devices that most of us own.

The final caution is that the battery needs to be modified so that fresh electrolytes can be pumped in and the gases released by the breakdown of the LiSO₂CF₃ removed. It’s safest if this sort of access is built into the battery from the start, rather than provided by modifying it much later, as was done here. And the piping needed would put a small dent in the battery’s capacity per volume if so.

All that said, the treatment demonstrated here would replenish even a well-managed battery closer to its original capacity. And it would largely restore the capacity of something that hadn’t been carefully managed. And that would allow us to get far more out of the initial expense of battery manufacturing. Meaning it might make sense for batteries destined for a large storage facility, where lots of them could potentially be treated at the same time.

Nature, 2025. DOI: 10.1038/s41586-024-08465-y  (About DOIs).