Lifetime of lithium-ion batteries boosted by new cathode coating

Despite seemingly-endless advances in experimental battery designs, good old lithium-ion batteries continue to be the frontrunner. There’s still plenty of room for improvement though, and now researchers have identified a new cathode coating that could make them safer and longer lasting.

Ubiquitous as they may be, lithium-ion batteries are known to have some problems. One such issue is that the cathode in these batteries can generate excess oxygen, which reacts with the electrolyte. That forms a film on the cathode surface, which reduces the amount of energy that can be passed between the two, in turn reducing the performance of the whole battery.

To counter that problem, the cathodes in most lithium-ion batteries have special coatings that reduce the effect. Unfortunately, this slows down lithium ions passing in and out, decreasing efficiency. Plus, because the coating doesn’t cover the entire surface, the degradation can still occur when the battery is operating at a higher temperature or voltage.

For the new study, researchers at Argonne National Laboratory and Hong Kong University of Science and Technology (HKUST) investigated alternative coatings, to help these batteries last longer.

The team settled on a conducting polymer called PEDOT. This stuff, they found, protected the cathode while still allowing lithium ions and electrons to pass through. And because it’s applied from a gas, using an oxidative chemical vapor deposition technique, it covers every individual particle of the cathode. That makes it far more comprehensive than the usual coatings, which are only partial.

The new coating was able to boost the operating voltage of the battery to 4.6 V, up from 4.2 V on existing lithium-ion batteries. The team says that this would reduce the cost of battery packs, and extend the battery life of devices.

“This is an incredibly exciting advancement,” says Khalil Amine, an author of the study. “This could significantly improve our experience with the devices we’ve come to rely on.”

The research was published in two papers, one appearing in Advanced Energy Materials and the other in Nature.

Source: Argonne National Laboratory

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