Miniature Robots and More Come to Life with 3D-Printed Microbattery 

When you think of taking something with “a grain of salt,” you might be taking it lightly, but you shouldn’t be quick to dismiss this grain-sized technology from engineers at Harvard University and the University of Illinois at Urbana-Champaign. There, they’ve managed to 3D-print a working tiny lithium-ion battery that could offer big possibilities for little devices of the future.

Those who have been keeping track of the seemingly weekly innovations in additive manufacturing will note that a battery is, in fact, a novel addition to the list. But the mere fact that batteries can now be 3D-printed isn’t the most newsworthy aspect of the research, as Dr. Jennifer Lewis, senior author of the study pointed out: "Not only did we demonstrate for the first time that we can 3D-print a battery, we demonstrated it in the most rigorous way.”

The battery was printed with a nozzle as narrow as a human hair, which squeezed out lithium metal oxide nanoparticles that come together to create a network of interlaced electrodes. Naturally, this specialized ink required a great deal of research on its own. Like all 3D-printing systems based on extrusion, the ink had to fit through a fine nozzle and instantly harden to hold its shape. But in addition, it needed specific electrochemical properties. This mean that the anode needed one lithium metal oxide compound, while the cathode needed another.

After the printing is complete, they are sealed in a liquid-electrolyte-filled compartment that allows the battery to work, which is critical for use in microelectronics.

Currently, miniature devices such as medical implants, as well as some particularly small robots and electronics rely on thin-film solid batteries that will fall short as we approach the energy demands of tomorrow.

What’s significant about the components of this design is that lithium-ion batteries that use liquid electrolytes are currently the only known batteries to offer the power that microelectronics will demand, as Shen Dillon, a University of Illinois materials science and engineering assistant professor explained: "The electrochemical performance [of the microbattery] is comparable to commercial batteries in terms of charge and discharge rate, cycle life and energy densities. We’re just able to achieve this on a much smaller scale.”

Details of their research have been published online in Advanced Materials.