The graphite gap: Penn State researchers call for plastic upcycling amid battery production concerns

13 May 2022 --- Single-use plastic packaging waste could be upcycled into needed graphite in a bid to further the circular economy, according to researchers at Penn State University, US. The team of researchers has been granted seed funding by the university’s Materials Research Institute to explore options for transforming single-use plastic waste into high-quality graphite to prevent a “huge shortfall” of the material. 

“We’re looking at a way to intersect a waste product with little commercial value and turn it into a commercial product with value but also facilitate the clean energy transition,” says Randy Vander Wal, professor of energy and mineral engineering, materials science and engineering, and mechanical engineering at Penn State.

“We literally have mountains of plastic waste, millions of metric tons every year, and most of it is still going into the landfill, but what if we have the opportunity to take a waste product that has no destiny per se and turn that into graphite?”

PackagingInsights recently reported on the annual financial losses the US economy faces as a consequence of landfilled plastic waste. We also spoke to graphene-enhanced bioplastic pioneer Toraphene after it closed a seed round of external financing for its compostable plastic alternative.

Much-needed graphite
The Penn State researchers highlight that with an abundance of plastic waste there is a forthcoming shortage in quality graphite. 

“When everyone thinks of lithium-ion batteries, they think of lithium, which is a critical mineral, but quality carbon in the form of graphite is also needed in lithium-ion batteries,” explains Vander Wal. “And there will be a huge shortfall in the graphite needed for batteries.”

“There will be a huge shortfall in the graphite needed for batteries,” warns Penn State professor Vander Wal.In addition to lithium-ion batteries, certain industrial practices also require graphite. For instance, in electrodes in aluminum refining and for electric arc furnaces used in steel manufacturing. 

“Every electric vehicle, like the Tesla Model 3, requires at least 70 kg of carbon,” says Vander Wal. “For every 1 million electric vehicles, a 10% increase of the current graphite market is projected.” 

Plastic upcycling 
Currently, petroleum-derived cokes (a byproduct of the oil refining process), coal tar pitches (remnants from the distillation of coal tar) and mined graphite are the main sources of graphitic carbons used in energy storage methods such as lithium-ion batteries. 

Petroleum-derived cokes and coal tar pitches are non-renewable resources and demand a lot of energy to produce. In addition, their production generates high emission levels of volatile organic compounds and as natural graphite is a limited resource, the mining process is environmentally destructive, stress the researchers. 

To turn single-use plastic waste into high-quality graphite, the Penn State researchers will use graphene oxide to provide the oxygen required for stabilization and an aromatic framework to guide the reconstruction of single-use plastics into a graphitic material. 

The researchers believe plastic upcycling could create a new path for graphite manufacturing.Environmentally sustainable transformation 
Compared to traditional catalysts, no purification or catalyst removal is required as the graphene oxide additive will have the same composition as the final graphite.

Since LDPE and PET plastics melt, they facilitate uniform mixing with the graphene oxide. During the heat treatment processing, the graphene’s chemical structure is imparted onto the surrounding plastic as it decomposes, explain the researchers.

Furthermore, this graphitization heat treatment can be performed at varied scales and does not require significant infrastructure.

Enhanced recycling economics
The researchers believe this work could create a new path for graphite manufacturing through the energy savings of a lower temperature process and the environmental benefits from reduced carbon dioxide emissions. 

In addition, upcycling waste plastic into high-value graphitic carbons will lead to improved recycling economics, increased recycling infrastructure investment, and recycling workforce growth, while reducing greenhouse gas emissions, the researchers say.

This growth becomes more important as clean energy technology drives the demand for carbon as a material. Lithium-ion battery production is expected to more than double by 2025, according to the Northern Graphite Corporation. 

Edited by Natalie Schwertheim