Three-dimensional (3D) printing can now be used to print lithium-ion microbatteries. The printed microbatteries could supply electricity to tiny devices in fields from medicine to communications, including many that have lingered on laboratory benches for lack of a battery small enough to fit the device, yet powerful enough to drive the device.
This image shows the interlaced stack of electrodes that were printed layer by layer to create the working anode and cathode of a microbattery. Photo by Jennifer Lewis.
As reported in the June 17 online edition of Advanced Materials (DOI: 10.1002/adma.201301036), a research team based at Harvard University and the University of Illinois at Urbana-Champaign created an ink for the anode with nanoparticles of Li4Ti5O12 (LTO), and an ink for the cathode from nanoparticles of LiFePO4 (LFP). Through nozzles of 30 µm in diameter, the printer deposited the inks onto the teeth of two gold combs, creating a tightly interlaced stack of anodes and cathodes. The researchers found that LTO and LFP inks produced with respective solids loadings of 57 wt% and 60 wt% yielded the desired rheological and printing behavior. The research team then packaged the electrodes into a tiny container and filled it with an electrolyte solution of de-ionized water, ethylene glycol, glycerol, and a cellulose-based viscosifier to complete the battery.
“Not only did we demonstrate for the first time that we can 3D-print a battery, we demonstrated it in the most rigorous way,” said Jennifer Lewis, senior author of the study, who is also the Hansjörg Wyss Professor of Biologically Inspired Engineering at the Harvard School of Engineering and Applied Sciences (SEAS), and a Core Faculty Member of the Wyss Institute for Biologically Inspired Engineering at Harvard University. Lewis led the project in her prior position at the University of Illinois at Urbana-Champaign, in collaboration with co-author Shen Dillon, an Assistant Professor of Materials Science and Engineering there.
After fabricating the microbatteries, the research team measured how much energy could be packed into the batteries, how much power they could deliver, and how long they held a charge. “The electrochemical performance 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,” Dillon said.
