Researchers from Virginia Tech and Lawrence Livermore National Laboratory have developed a novel way to 3D print complex objects of one of the highest-performing materials used in the battery and aerospace industries.
Previously, researchers could only print this material, known as graphene, in 2D sheets or basic structures. But Virginia Tech engineers have now collaborated on a project that allows them to 3D print graphene objects at a resolution an order of magnitude greater than ever before printed, which unlocks the ability to theoretically create any size or shape of graphene.
Because of its strength – graphene is one of the strongest materials ever tested on Earth – and its high thermal and electrical conductivity, 3D printed graphene objects would be highly coveted in certain industries, including batteries, aerospace, separation, heat management, sensors, and catalysis.
Graphene is a single layer of carbon atoms organized in a hexagonal lattice. When graphene sheets are neatly stacked on top of each other and formed into a three-dimensional shape, it becomes graphite, commonly known as the “lead” in pencils.
Because graphite is simply packed-together graphene, it has fairly poor mechanical properties. But if the graphene sheets are separated with air-filled pores, the three-dimensional structure can maintain its properties. This porous graphene structure is called a graphene aerogel.
“Now a designer can design three-dimensional topology comprised of interconnected graphene sheets,” said Xiaoyu “Rayne” Zheng, assistant professor with the Department of Mechanical Engineering in the College of Engineering and director of the Advanced Manufacturing and Metamaterials Lab. “This new design and manufacturing freedom will lead to optimization of strength, conductivity, mass transport, strength, and weight density that are not achievable in graphene aerogels.”
Zheng, also an affiliated faculty member of the Macromolecules Innovation Institute, has received grants to study nanoscale materials and scale them up to lightweight and functional materials for applications in aerospace, automobiles, and batteries.
Previously, researchers could print graphene using an extrusion process, sort of like squeezing toothpaste, but that technology could only create simple objects that stacked on top of itself.
“With that technique, there are very limited structures you can create because there’s no support and the resolution is quite limited, so you can’t get freeform factors,” Zheng said. “What we did was to get these graphene layers to be architected into any shape that you want with high resolution.”
This project began three years ago when Ryan Hensleigh, lead author of the article and now a third-year Macromolecular Science and Engineering Ph.D. student, began an internship at the Lawrence Livermore National Laboratory in Livermore, California. Hensleigh started working with Zheng, who was then a member of the technical staff at Lawrence Livermore National Laboratory. When Zheng joined the faculty at Virginia Tech in 2016, Hensleigh followed as a student and continued working on this project.
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