Li-on batteries are great and all, but there's a barrier preventing them from storing much more power: they, um, tend to catch fire. But a company called Solid Energy claims to have developed a technology which makes the power source both more energy dense and safer too.
The company, spun out of MIT, wants to replace the usual graphite electrodes used in lithium-ion batteries with a high-energy lithium-metal ones. Sounds simple, but it's been done before with disastrous results: the metal short circuits and bursts into flames. Oh dear. But Solid Energy has been developing new and improved electrolytes -- the material between electrodes in the battery -- which make the technique completely safe. Technology Review explains:
First, it coats the lithium metal with a thin polymer, much like the solid electrolyte others have used. The key difference is that it's very thin, so it doesn't slow down lithium ions, and the battery doesn't need to be heated... On its own, the thin polymer isn't enough to prevent short circuits, so [it's supplemented] with a liquid electrolyte.
Unlike conventional liquid electrolytes, the ones SolidEnergy is using -- they're a type of what's known as an ionic liquid -- are not flammable, which improves safety.
In fact, they claim that the new electrolyte lets them use the once dangerous lithium-metal electrodes and bump up the storage capacity of a li-on battery by 30 per cent. Up to this point the batteries they've made are small, hand-built affairs, about the size you'd find in your phone. But the team says that with commercial, large-scale manufacturing systems in place it could produce batteries that hold 40 per cent more energy, which could even be big enough power electric vehicles.
What's more, they claim that it can all be done in such a way that the cells cost $US130 per kilowatt-hour -- which is in line with Department of Energy goals for making electric vehicles affordable. Because Solid Energy isn't making details of its new technology publicly available it's hard to predict how believable their claims are -- but we certainly hope they can follow through. [Solid Energy via Technology Review]