PENNSYLVANIA, June 29: A plastic bottle tossed into a recycling bin could one day help power an electric vehicle, smartphone, or renewable energy storage system, according to researchers at Penn State.
In a new study, researchers converted waste polyethylene terephthalate (PET) into highly ordered synthetic graphite, a crystalline form of carbon. The resulting graphite exhibited large, well-ordered crystallites—microscopic regions of precisely aligned carbon layers—indicating a highly organized crystal structure.
The material outperformed commercial natural graphite samples in structural order, a key indicator of suitability for high-quality battery anodes. The findings, published in Diamond and Related Materials, suggest that a common waste product could become a valuable source of battery-grade carbon.
“Most people think of a plastic bottle as waste once they’re done using it,” said Shakshi Sekar, lead author of the study and a doctoral student in Penn State’s John and Willie Leone Family Department of Energy and Mineral Engineering. “Our work shows that the same material can become a valuable resource for producing graphite, which is essential for modern battery technologies.”
Graphite, classified as a critical mineral by the U.S. Department of Energy, is a key component of lithium-ion batteries, serving as the anode material that stores and releases electrical charges. As demand for electric vehicles, consumer electronics, and grid-scale energy storage systems continues to rise, so does the need for battery-grade graphite.
At the same time, PET remains one of the world’s most widely used plastics. According to the National Association for PET Container Resources, although many consumers recycle plastic bottles, much of the material is ultimately discarded, downcycled into lower-value products, or sent to landfills.
The research team saw an opportunity to address both challenges.
By combining shredded PET plastic with small amounts of graphene oxide and heating the material through a carefully controlled thermal process, the researchers reorganized the carbon atoms within the plastic into highly ordered graphitic structures.
“We’re not simply finding a use for waste plastic,” Sekar said. “We’re creating a valuable material that could help support the growing demand for batteries and clean energy technologies.”
The researchers found that adding just 2.5% graphene oxide by weight produced the highest-quality graphite. Under those conditions, the material developed crystallite dimensions exceeding those typically associated with natural graphite, indicating an exceptional degree of structural order.
According to the researchers, oxygen-containing functional groups along the edges of graphene oxide sheets help initiate and promote lateral graphite crystal growth. The exposed graphene surfaces serve as templates that guide carbon atoms into highly organized stacked arrangements during graphitization, the process of converting carbon into graphite.
The team’s approach differs from many conventional methods used to produce synthetic graphite. Traditional graphitization techniques often rely on metal catalysts such as iron, nickel, or cobalt, which can leave impurities that require additional chemical purification.
Instead, the researchers used graphene-based additives that promote graphitization without introducing metallic contaminants.
“By avoiding metal catalysts, we can produce cleaner graphite while reducing chemical use and waste generation,” Sekar said.
Eliminating catalyst removal steps could simplify future manufacturing while reducing the environmental footprint associated with producing battery materials, the researchers said.
Although additional research is needed to evaluate large-scale production and battery performance, the study demonstrates a promising pathway for transforming one of the world’s most common waste streams into a high-value energy storage material.
The findings also point to a broader shift in how plastic waste could be viewed in the future, Sekar noted.
“If waste plastic can become a feedstock for advanced energy materials, it changes how we think about recycling,” Sekar said. “Instead of viewing plastic as a disposal problem, we can see it as a resource that helps support clean energy technologies.”
Co-author Randy Vander Wal, a professor of energy and mineral engineering at Penn State and a faculty member at the university’s Institute of Energy and the Environment, also contributed to the study.
The research was supported by the U.S. National Science Foundation. (ANI)
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