Ever wonder why your lithium ion batteries degrade and die, and sometimes catch on fire? Well, a University of Arizona study has found a way to reduce the formation of lithium dendrites--kinda like a stalactite, but in a battery--to improve life and reduce the risk of fires. It's the same reason that lead-free solders (RoHS regulations) tend to result in electronic device failure. To draw a picture, current tends to flow along the dendrites instead of through the material between the lithium plates, and that results in a localized "hot spot" that destroys the battery, sometimes spectacularly in fire. The dendrite is acting, more or less, like a lightbulb filament. It's classic electromigration.
As Fat Albert said, if you're not careful, you just might learn something. I'd better watch out.