The problem with lithium-ion batteries, is that there's only a certain limit of power you can store. And they tend to catch fire too. So a company called Solid Energy has claimed to have developed a technology that makes the power source more energy dense and safer.

Solid Energy intends to replace the usual graphite electrodes used in lithium-ion batteries with high-energy lithium-metal ones. The process has been done before, but not without disastrous results. First, the metal short circuits. Then the whole thing bursts into flames. Not good.

The version developed by Solid Energy improved electrolytes, making the technique, apparently, 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.
They claim that they can bump up the storage capacity of a lithium-ion battery by 30 percent. According to the team, commercial, large scale manufacturing could produce batteries that hold 40 percent more energy.

Too good to be true? We'll have to wait and see. [Solid Energy via Technology Review]