3D printed lithium micro batteries
Using
3D printing researchers have created a nano-sized battery the size of a grain
of sand. It could be used to power tiny sensors or even implantable medical
devices
Three
dimensional printing now can be used to print lithium-ion microbatteries the
size of a grain of sand. The printed microbatteries could supply electricity to
tiny devices in fields from medicine to communications, including many that
have sat on lab benches for lack of a battery small enough to fit the device.
To make the microbatteries, a team based at Harvard University and the University of Illinois at Urbana-Champaign printed precisely interlaced stacks of tiny battery electrodes, each less than the diameter of a human hair.
“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, the senior author of the study. Lewis co-led the project with Shen Dillon. The results appear in Advanced Materials.
In recent years engineers have invented many miniaturised devices, including medical implants, flying insect-like robots, and tiny cameras and microphones that fit on a pair of glasses. But often the batteries that power them are as large as or larger than the devices themselves – which defeats the purpose of building small.
To get around this problem, manufacturers traditionally deposit thin films of solid materials to build the electrodes. However, because of their ultrathin design, these micro-batteries do not pack sufficient energy to power tomorrow’s miniaturised devices.
The scientists realised they could pack more energy if they could create stacks of tightly interlaced, ultrathin electrodes that were built out of plane. For this they turned to 3D printing. 3D printers follow instructions from three dimensional computer drawings, depositing successive layers of material – inks–to build a physical object from the ground up, much like stacking a deck of cards one at a time. The technique is used in a range of fields, from producing crowns in dental labs to rapid prototyping of aerospace, automotive and consumer goods. Lewis’ group has greatly expanded the capabilities of 3D printing. They have designed a broad range of functional inks – inks with useful chemical and electrical properties. And they have used those inks with their custom-built 3D printers to create precise structures with the electronic, optical, mechanical or biologically relevant properties they want.
To print 3D electrodes, the group created and tested several specialised inks. Unlike the ink in an inkjet printer, which comes out as droplets of liquid that wet the page, the inks developed for extrusion-based 3D printing must fulfil two requirements. They must exit fine nozzles like tooth paste from a tube, and they must harden instantly.
In this case, the inks also had to function as electrochemically active materials to create working anodes and cathodes, and they had to harden into layers that are as narrow as those in thin-film batteries. To accomplish these goals, they created an ink for the anode with nanoparticles of one lithium metal oxide compound, and an ink for the cathode from nanoparticles of another. The printer deposited the inks onto the teeth of two gold combs, creating a tightly interlaced stack of anodes and cathodes. They then packaged the electrodes into a tiny container and filled it with an electrolyte solution to complete the battery.
Next, they measured how much energy could be packed into the tiny 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,” Dillon said. “We’re just able to achieve this on a much smaller scale.”
To make the microbatteries, a team based at Harvard University and the University of Illinois at Urbana-Champaign printed precisely interlaced stacks of tiny battery electrodes, each less than the diameter of a human hair.
“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, the senior author of the study. Lewis co-led the project with Shen Dillon. The results appear in Advanced Materials.
In recent years engineers have invented many miniaturised devices, including medical implants, flying insect-like robots, and tiny cameras and microphones that fit on a pair of glasses. But often the batteries that power them are as large as or larger than the devices themselves – which defeats the purpose of building small.
To get around this problem, manufacturers traditionally deposit thin films of solid materials to build the electrodes. However, because of their ultrathin design, these micro-batteries do not pack sufficient energy to power tomorrow’s miniaturised devices.
The scientists realised they could pack more energy if they could create stacks of tightly interlaced, ultrathin electrodes that were built out of plane. For this they turned to 3D printing. 3D printers follow instructions from three dimensional computer drawings, depositing successive layers of material – inks–to build a physical object from the ground up, much like stacking a deck of cards one at a time. The technique is used in a range of fields, from producing crowns in dental labs to rapid prototyping of aerospace, automotive and consumer goods. Lewis’ group has greatly expanded the capabilities of 3D printing. They have designed a broad range of functional inks – inks with useful chemical and electrical properties. And they have used those inks with their custom-built 3D printers to create precise structures with the electronic, optical, mechanical or biologically relevant properties they want.
To print 3D electrodes, the group created and tested several specialised inks. Unlike the ink in an inkjet printer, which comes out as droplets of liquid that wet the page, the inks developed for extrusion-based 3D printing must fulfil two requirements. They must exit fine nozzles like tooth paste from a tube, and they must harden instantly.
In this case, the inks also had to function as electrochemically active materials to create working anodes and cathodes, and they had to harden into layers that are as narrow as those in thin-film batteries. To accomplish these goals, they created an ink for the anode with nanoparticles of one lithium metal oxide compound, and an ink for the cathode from nanoparticles of another. The printer deposited the inks onto the teeth of two gold combs, creating a tightly interlaced stack of anodes and cathodes. They then packaged the electrodes into a tiny container and filled it with an electrolyte solution to complete the battery.
Next, they measured how much energy could be packed into the tiny 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,” Dillon said. “We’re just able to achieve this on a much smaller scale.”
To create the microbattery, a
custom-built 3D printer extrudes special inks through a narrow nozzle. Those
inks solidify to create the battery’s anode (red) and cathode (purple), layer
by layer. A case (green) then encloses the electrodes and the electrolyte
solution is added to create a working microbattery; Bottom: The interlaced
stack of electrodes that were printed layer by layer.
MM130620
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