Particles have “fuzzy memory” in a solid-state battery

When you fire a laser at a solid-state battery, it turns out the particles inside aren’t tossed into chaos. This has surprised a team of US and UK researchers.

The team has found “persistence of memory” in the ions (charged atoms) that help move electricity around a solid-state battery.

The discovery improves understanding of solid-state batteries, which are candidates for the next generation of safer, more powerful batteries.

A paper describing the research is published in Nature.

The team was investigating the way ions behave in a solid-state battery electrolyte when a laser fires a sudden bolt of voltage through it.

Previously, researchers had observed ions in these electrolytes “hopping” from place to place in a jumbled way, eventually letting electric charge flow.

But this team found that, for a few billionths of a second, the ions briefly changed direction and went back to the positions they’d been in a moment earlier – before continuing on their chaotic way.

Lead author Andrey Poletayev, a postdoctoral researcher now at Oxford University, calls this “fuzzy memory”.

“Researchers have been investigating ionic transport with macroscopic tools for so long, and they couldn’t observe what we saw in this study,” says Poletayev.

Laser apparatus
A laser apparatus built by SLAC lead scientist Matthias C. Hoffmann for experiments that shook ions traveling through a solid-state battery electrolyte with a jolt of voltage. Credit: Andrey D. Poletayev/Oxford University

The researchers used high-frequency lasers, with pulses just a few trillionths of a second, to observe the ions moving – the way the light reflected off the electrolytes could tell them what the ions were up to.

“There are multiple weird and unusual things going on in the ion hopping process,” says senior author Aaron Lindenberg, a professor at Stanford University, and the SLAC National Accelerator Laboratory, US, where the experiments took place.

“When we apply a force that shakes the electrolyte, the ion doesn’t immediately respond like in most materials.

“The ion may sit there a while, suddenly jump, then sit there for quite a while again. You might have to wait for some time and then suddenly a giant displacement occurs.

“So there’s an element of randomness in this process which makes these experiments difficult.”

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