Longer lasting, higher capacity, and cheaper rechargeable batteries could be in the pipeline as scientists finally figure out exactly what’s going on inside, potentially opening the door to increased electric car range and smartphones that spend less time plugged in. The microscopic imaging techniques, developed by researchers at the US Department of Energy’s Pacific Northwest National Laboratory, are expected to make it possible to examine what’s happening within a live lithium-ion battery, particularly around areas of chemistry which so far power research has struggled to understand and refine for longer-lasting gadgets.
Traditional li-ion battery research takes place under so-called dry conditions, using transmission electron microscopes to examine how positively charged ions deform the shape of electrodes. The repeated transmission of those ions can cause the electrodes to swell, and eventually be worn down; over the life-span of the battery, this reduces the total charge it can hold, meaning more frequent charge cycles and, eventually, replacement.
What researchers haven’t been able to do, so far at least, is to examine how a wet battery operates. There, as in real-world conditions, electrodes are “bathed in liquid electrolytes” through which ions easily move, and a solid electrolyte layer forms which so far has been impossible to study in dry batteries.
That’s important, since the solid electrolyte layer is known to have “peculiar properties and to influence the charging and discharging performance of the battery” according to materials scientist Chongmin Wang.
What isn’t known is any detail around that, such as how it forms, what its structure is like, how its chemistry operates, and how it evolves across multiple charge/discharge cycles. Better understanding, Wang’s team suggests, could lead to more efficient, affordable batteries.
Unfortunately, initial experiments using the wet visualization technology – which required creating a battery so small that multiple examples could fit on the surface of a dime – failed to turn up the mysterious layer.
The team will now work on shrinking the wet layer thickness by at least half, Wang says, so that resolution increases.