For most of us, the only way we judge a battery is by how long it can deliver electrons to our favorite devices. But many applications require more than that. They need batteries that operate across a large temperature range, are compact or flexible, and can manage a fast charge/discharge rate. Plus, we'd all like them not to explode or fail suddenly.
Most energy storage tech involves balancing a trade-off among these various properties. But a new report from a collaboration between academic researchers and Toyota seems to promise it all: a battery more compact than lithium-ion, a better energy density, the charge speed of a supercapacitor, and improved safety. How is this all possible? They got rid of the liquid electrolyte typical of most lithium-ion batteries.
In principle, batteries are structurally very simple: two electrodes where ions exchange electrons, separated by an electrolyte that allows the ions to shuffle between the two. These electrolytes are almost always liquids, since they can easily dissolve the ions, allowing their free movement between the electrodes. Unfortunately, leaking electrolytes are often a cause of failure in these batteries. Fixing this is a challenge—you can't just shove ions through a solid, right?
Actually, you can, just not as efficiently. A few solid-state electrolytes have been developed, but they haven't had the performance of the existing technology on the market, largely because of the difficulty of pushing ions across the solid electrolyte. But a paper involving Toyota researchers, published in 2011, showed that some solids can be pretty good at conducting lithium ions. The trick is that these solids need to have a crystal structure that arranges the lithium ions in a line, essentially creating a channel for them to move along.
To read more, click here.