Lithium-ion batteries are common rechargeable batteries for portable electronics. They have a high energy density, tiny memory effect, and low self-discharge. Currently, their shape dictates the form of the device they power. In the future, it will be the other way around. A team of researchers from Duke University in North Carolina are already in the process of devising a solution to be able to fabricate lithium-ion batteries in any shape and size by using a standard low-cost 3D printer.
Consumer products today are regulated by their battery’s generic square or cylindrical shape. This limitation contributes to a less than innovative exterior design as well as a waste of internal casing space. For now, the battery is the only element that cannot be 3D printed to commercial quality standards. With the possibility of custom-sized lithium-ion batteries, all the components that make up a product can fit perfectly together without any leftover empty gaps around the battery. 3D printing technology could revolutionize the world of lithium-powered devices.
In a new study that was published in the ACP Applied Energy Materials, postdoctoral researcher Christopher Reyes and Associate Professor of Chemistry Benjamin Wiley explained that “the ability to 3D print lithium-ion batteries in an “arbitrary geometry” would allow a battery’s “form factor” (or shape) to be customized to fit a product’s design aesthetic, while facilitating the use of the battery as a structural component.”
In theory, a 3D printer would produce the electrolyte and two electrodes (the cathode and anode) in one process as compared to the current lithium-ion production scenario where the three elements are manufactured separately and combined inside a casing.
To make it work, a new kind of ink had to be invented. The polymers used in conventional 3D printers (such as poly(lactic) acid) are unable to duplicate the electric current technology used by lithium-ion batteries because they are not ordinarily conductive. Reyes and Wiley explained in their research article how they infused the poly(lactic) acid with a mixture of ethyl methyl carbonate, propylene carbonate, and lithium perchlorate in order to obtain an ionic conductivity comparable to that of polymer and hybrid electrolytes. A cutting-edge chemical ink mix resulted which could enable 3D printing of complete lithium-ion batteries, to any shape or size, using low-cost and widely available fused filament fabrication (FFF) machines.
To test their development, the team then 3D printed an LED bangle. The custom battery was shaped to match the contour of the bangle by printing the anode and cathode as freestanding curved electrodes. The battery was able to power a green LED for approximately 60 seconds. The bangle proves that the capacity of this first-generation 3D-printed battery is too low for practical use, but it works, and the research continues.