Lithium-ion batteries (LIBs) can power a huge range of applications, covering most electric vehicles (EV) and consumer electronics devices. However, currently product designers have to cater to the commercially-available battery's size, shape and weight. In order to use 3D-printing technology to create any customized shape LIBs, a research team from Duke University published a solution.

Commercially-ready LIBs typically come in cylindrical or rectangular shapes. A model 18650 battery of EV is cylindrical, and a smartphone's battery is mostly rectangular. When manufacturers are designing products, they need to reserve a certain size and shape of space to the battery. This factor limits design options.

To unlock the "form factor" limitations, some institutions did experiments with 3D printing technology that promises to print any size and shape. However, the polymers used by traditional 3D printers, such as polylactic acid (PLA), are not ionic conductors.

A team from Duke University solved the issue by injecting PLA filament with a mix of ethyl methyl carbonate, propylene carbonate, and lithium perchlorate, so as to raise the ionic conductivity. Furthermore, the team infused lithium titanate battery with graphene or multi-walled carbon nanotubes in the anode or cathode, respectively, so that ionic conductivity can be raised up.

The team stated that the solution above can be achieved by low-cost and widely-used 3D printing technology. With fused filament fabrication (FFF) technology, LIBs can be printed in any shape or size.

The researchers 3D-printed a LED device to demonstrate their concept of LIB. The LIB can power the light of bangle's LED for 60 seconds. According to the essay, the capacity of first-generation 3D printed battery is still lower than that of commercial batteries. Thus, it is not commercially ready. In the future, they might replace the PLA-based paste with 3D-printable paste.

Duke University was not the only institute solving the issue with a 3D printing battery. US-based Carnegie Mellon University (CMU)'s researchers also fervently developed their 3D printing battery. CMU's advantage is that their electrodes have pores and channels.  Rahul Panat, an Associate Professor in the Mechanical Engineering Department of CMU, explained that the electrodes with porous structure can allow plenty of li ions to penetrate through the electrode volume. This factor vastly helps raise electrode utilization rate and higher energy storage capacity.

The CMU-led team has currently used microlattice structure to raise battery capacity and increase battery charging/re-charging rates. The team has used US-based Optomec's aerosol jet (AJ) 3-D printing system to print battery that creates a 3-D microlattice structure with controlled porosity.The AJ technology can create 3D prints of electronic components such as resistors, capacitors, antennas, sensors, and thin film transistors. It can adjust the ohm value of resistors by changing the printing parameters, and components can also be printed onto 3D surfaces. In this way, there is no need of independent substrate. The final product's size, thickness and weight might be reduced.

If the lab technologies' products can achieve a commercial scale, 3D print battery technology can benefit segments of consumer electronics products, bio-medical devices, and aerospace applications. Wearable devices that must be small-sized, light, and foldable will not be limited by the size of battery in the future.

 (Image credit: American Chemical Society. Article by Daisy Chuang)