As development of micro- and nano-scale devices continues to advance, so does the need for an equally-tiny method of powering them. There’s not much point in developing a surveillance micro air vehicle the size of a housefly, for instance, if it requires a watch battery in order to fly. That’s why DARPA (the U.S. Defense Advanced Research Projects Agency) is funding a project to create really tiny batteries. Just how tiny are we talking, here? Well, they’re aiming for something smaller than a grain of salt.

Jane Chang, an engineer from the University of California, Los Angeles, is designing the electrolyte that will allow the charge to flow between electrodes in such batteries. “We're trying to achieve the same power densities, the same energy densities as traditional lithium ion batteries, but we need to make the footprint much smaller,” she stated.

In order to do so, she has coated well-ordered micro-pillars or nano-wires with lithium aluminosilicate, an electrolyte material. The structures are fabricated to maximize their surface-to-volume ratio, for maximum energy density. The lithium was applied through a process of atomic layer deposition, in which one-atom-thick layers of a material can be sprayed onto a surface.

The electrodes have also been developed, but a fully-functioning salt-sized battery has still yet to be assembled, and probably won’t be for some time yet.

Chang presented her work at the AVS 57th International Symposium & Exhibition this week in Albuquerque, New Mexico.