Q: You are working on converting plastic waste into graphite. We know plastic waste is a problem, but what’s the connection to graphite?
Vander Wal: Well, lithium ion batteries are the premier batteries used for almost everything from electric vehicles to flashlights. To make them, you need carbon in the form of graphite. But with the burgeoning global demand for electric vehicles in particular, there just isn’t enough natural graphite to make the batteries. The supply of synthetic graphite made from petroleum pitch and fossil alternatives is also insufficient and has some impurities, so we must look for other sources.
Q: And plastic waste is a solution to this shortage?
Vander Wal: Yes, the consumer plastics that we throw away—the single-use containers, everything from styrofoam to polyethylene and plastic bags—are a great resource for making carbon/graphite. Landfills are overflowing, there are millions of tons of this waste, and using it means no new mining is required. We look at this process as a sustainable, long-term solution to the dwindling supply and increased demand for graphite, because we’re going to have plastic waste for a very long time.
Q: Who’s providing you with the plastic waste?
Vander Wal: We hooked up with the Pennsylvania Manufacturers Recycling Association, an independent nonprofit corporation with a mission to reduce or eliminate barriers and lead to new, expanded use of Pennsylvania’s recycled materials.
Q: What’s your actual process for creating graphite?
Vander Wal: Our process is straightforward. We mix graphene oxide with recycled plastics, whether in shredded or pelletized form as received from plastic recyclers. We put the plastic through different stages of treatment, heating it at different temperatures to finally characterize the structure of the carbon yield and quantify it. We then process the mixture at staged temperatures.
Q: What results have you obtained?
Vander Wal: Depending on the form of plastic used, my graduate student Akshay Gharpure has been able to achieve a carbon yield increase of more than 200% of what was in the plastic. The quality of the carbon obtained was also a little bit better than that of the plastic itself.
Q: Will the carbon you obtain then go through another process to be turned into graphite?
Vander Wal: At the end of our process, the carbon should be nominally graphitic. But yes, there are many other steps to reduce the carbon into particles, make them smaller and uniform, and then configure them to finally incorporate them into a battery.
Randy Vander Wal is a professor of energy and mineral engineering in the College of Earth and Mineral Sciences.