In a recent Science Friday episode on NPR, the topic was “Aiming For ‘Wild and Crazy’ Energy Ideas“.  The Advanced Research Projects Agency-Energy, or ARPA-E, backs energy technologies that are too risky for investors, but offer a potentially huge payoff—if they work. The agency has gambled on flywheels, compressed air energy storage, lithium-air batteries, even wind-energy kites.

One of the profiled technologies was a 3D printed battery. “The concept is to integrate form and function,” said Jennifer Lewis, Wyss Professor of Biologically Inspired Engineering at Harvard University. “Our batteries 1000 times smaller than the smallest rechargeable Lithium Ion battery that you can find commercially.” They are so small, in fact, that each battery can fit on a grain of sand.

Now don’t get too excited yet. You can’t 3D print one of these batteries on your MakerBot, Lewis explained, “We’ve custom designed and built our own 3D printers as well as the inks that allow you print the anode and cathode in interdigitated fashion.”

Applications of these batteries include autonomous sensors, micro robots, and biomedical devices. For example, 98% of hearing aids are 3D printed, at least the plastic molding is. But you have to hand pot the electronics and replace the batteries every 7 days. With Lewis’ 3D printed micro battery technology, it’s possible to 3D print both the plastic and the electronics.

In the video below, 3D printing is used to deposit a specially formulated “ink” through a fine nozzle to build a microbattery’s anode layer by layer. Unlike an office inkjet printer that dispenses ink droplets onto paper, these inks are formulated to exit the nozzle like toothpaste from a tube and immediately harden into thin layers. The printed anode contains nanoparticles of a lithium metal oxide compound that provide the proper electrochemical properties.

You can learn more about this research at Harvard’s website and read the work published in the journal Advanced Materials.