Graphene and 3D printing represent two exciting developments in science and technology. Graphene has long been regarded as a wonder material. Made from carbon, it’s an extremely versatile material that has piqued researchers’ interest for years.
Graphene’s been seen as a wonder material because it has so many desirable characteristics. It’s good at conducting electricity. It’s a semimetal with lots of tensile strength. It lies flat, but at the molecular level its structure is similar to that of a carbon nanotube. The bonds that make graphene are neat, and there’s never any overlap between bonds. It’s a remarkably stable material, and lies very thin. In spite of all this promise, however, it’s been difficult for engineers and scientists to really unlock graphene’s potential. Until now, that is.
Recently, researchers in China combined graphene with 3D printing technology. By incorporating graphene into an ink that dries as a solid, they were able to print an object with highly conductive properties. By using a 3D printer, they were able to print three-dimensional graphene, a combination that the research team used to print supercapacitors. This technology could revolutionize the way energy is stored for electronics. These graphene oxide capacitors have the potential to reduce the size of batteries for a variety of electronic devices.
One unique thing about the process used by the research team is that they’ve devised a fairly green process. They used graphene sheets on a salt template, and made the deposit via chemical vapor. If this process can be scaled up effectively, it could change the way items like smartphone and laptop batteries are manufactured. However, at the present time, there’s not enough high-quality graphene that’s readily available to really scale this up.
Another issue is the form of graphene that’s used. In order to make the ink, powdered graphene is needed. In that powdered state, it’s hard to find graphene of high quality. Unusable graphene samples the research team encountered had a number of problems. Some had chemical impurities. Others didn’t have an even thickness. Still others had structural problems.
The technology used in the research team’s process helped to overcome many of these issues. To make the ink, graphene nanosheets were coated with nitrogen. The NaCl template used had advantages, too. Table salt is readily available. It’s water soluble, meaning it’s easy to remove from the ink after it’s in its final state. Originally created in a cage shape, the ink is collapsed into a 2D shape using ultrasound. At proper thickness, the graphene ink is just 5 to 7 graphite layers in thickness. When this composite ink was finished, it was easy to print flexible battery parts.
The researchers were then able to print flexible electrodes for supercapacitors. They were also used to print interlayers for Li−S batteries, along with other materials. In comparison to traditional batteries, these supercapacitors had improved conductivity. They performed better, and didn’t require the separators traditionally seen in batteries.
Because it’s affordable, lightweight and uses readily available materials, this technology holds great promise. It’s speculated that 3D printed graphene inks will have applications for wearables, phones and other smart devices. This method has the potential to make technology much more affordable to produce.