Researchers at Purdue University have devised a method of converting plastic waste into battery electrode material using microwaves. The process applies to PET — polyethylene terephthalate — the most commonly used plastic for single-use water and soda bottles. Their work is detailed in the American Chemical Society’s journal Sustainable Chemistry & Engineering under the catchy title of Rapid Upcycling of Waste Polyethylene Terephthalate to Energy Storing Disodium Terephthalate Flowers with DFT Calculations.
According to PV Magazine, the researchers used ultra-fast microwave irradiation to convert PET flakes into disodium terephthalate (DST) in a process they say took around two minutes. “The applicability of the microwave technique on organic reactions has gained attention in recent times due to its advantage of [a] rapid reaction process,” said Purdue associate professor Vilas Pol. “We have accomplished the complete conversion of PET to disodium terephthalate within 120 seconds, in a typical household microwave set-up.”
PET is one of the most heavily used materials in the world and is found in food and drink packaging, polyester clothing, and a huge range of other consumer and industrial materials. Though widely recycled, the mountains of PET in circulation make it a significant contributor to plastic pollution. PETRA, the North American plastics industry association, estimates only 31% of the material in the US is recycled, and only 52% in Europe.
The Purdue team tried the approach to make anodes for both lithium-ion and sodium-ion battery cells. Pol tells Science Daily that while lithium-ion technology is currently dominating both the portable electronics and electric vehicles market, sodium-ion battery research also has gained significant attention due to its low cost and appealing electro-chemical performance in grid applications. “We are helping to address the growth in the proliferation of renewable energy conversion and storage, which stems from the societal attention and increasing awareness of climate change and energy resource limitation,” he says.
The paper describes the synthesized DST produced by the process as a “low-cost, environmentally benign, organic molecular compound” that is sustainable and recyclable. The study does not address the potential scalability of the microwave process or how the price of synthesized DST compares with the graphite most commonly used as anode material in lithium-ion batteries.
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