Carbon coating enables lithium metal battery electrodes

Argonne National Lab

The energy storage density of batteries has made remarkable strides in the last few decades, but people will always be happy with further improvements. The more charge you can stuff into a limited space, the longer cellphones will last and the farther electric cars will drive.

Right now, the anodes of lithium-ion batteries contain material that stores lithium in its structure. It would be more efficient to simply make the anode out of lithium metal itself, but early attempts to do so haven't worked out especially well, as the metal forms structures that rapidly degrade performance of the battery. Now, researchers have figured out how to put a carbon cap on top of the metal, keeping the lithium in its place and greatly enhancing the anode's stability.

The researchers behind the new paper, who are based at Stanford, nicely describe the problems with some of the previous work on lithium metal electrodes. To begin with, as charge moves in and out of the electrodes, they will necessarily grow and shrink with the changes in the amount of lithium present. This strains any electrolyte they're in contact with, frequently causing defects to appear at the electrode-electrolyte interface. Once these defects form, lithium metal will preferentially be added at these sites, causing extremely uneven growth.