Researchers in the US has used a microwave to convert waste plastic into a material that can be used as the anode of a battery.
The team at Purdue University created the technique to turn waste polyethylene terephthalate, one of the most recyclable polymers, into an anode for both lithium ion and sodium ion battery chemistries. The technique has already been used by the same team for lithium sufur battery chemistry.
"We use an ultrafast microwave irradiation process to turn PET, or polyethylene terephthalate, flakes into disodium terephthalate, and use that as battery anode material," said Vilas Pol, a Purdue associate professor of chemical engineering who has worked with the Purdue Research Foundation Office of Technology Commercialization to develop several battery technologies. "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."
The Purdue team tried the approach with both lithium-ion and sodium-ion battery cells. They worked with researchers from the Indian Institute of Technology and Tufts University.
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 electrochemical performance in grid applications says Pol.
"The applicability of the microwave technique on organic reactions has gained attention in recent times due to its advantage of the rapid reaction process," he said. "We have accomplished the complete conversion of PET to disodium terephthalate within 120 seconds, in a typical household microwave setup."
In tests, the disodium terephthalate-carbon black (Super P) composite electrode delivers discharge capacities of 182 and 224 mAh/g at a current density of 25 mA/g after 50 cycles in Li-ion and Na-ion cells respectively. The better charging performance for the lithium ion cell comes from the lower mobility of sodium ions in