UCR Scientists Upcycle PET Bottles to Make EV Batteries

Could excess plastic waste be used to reduce carbon emissions? Sounds too good to be true? Well, researchers at the University of California, Riverside, have devised a way to turn polyethylene terephthalate (PET) found in consumer plastic bottles into material useful for producing sustainable energy storage. While the storage capacity of batteries made using this technique may not match up to that of the lithium-ion ones currently in use, their significantly less charging time would make the proposed batteries practical nevertheless. 

This project, aimed at reducing plastic pollution and hastening the clean energy transition, is the latest among years of efforts undertaken by engineering professors Mihri and Cengiz Ozkan, and their students, to create improved energy storage materials from sustainable sources like glass bottles, beach sand, Silly Putty, and portabella mushrooms, etc. Cengiz Ozkan was recently awarded the 2020 TUBITAK Scientific Achievement Award, Turkey’s highest scientific honor.

The UCR scientists described the process in an open-access article entitled ‘Upcycling of Polyethylene Terephthalate Plastic Waste to Microporous Carbon Structure for Energy Storage’ published in August last year in the US journal Energy Storage. First, pieces of PET plastic bottles are dissolved in a solvent comprising a mixture of trifluoroacetic acid and dichloromethane. Following this, through electrospinning, microscopic fibers are fabricated from the polymer and the plastic threads are carbonised in a furnace. The resulting material is mixed with a binder and a conductive agent, after which it is dried and assembled into an electric double-layer supercapacitor within a coin-cell type format. With added pseudocapacitance, the active material is able to perform as a supercapacitator. Apparently, it has both a double-layer capacitor created by the separated ionic and electronic charges as well as redox reaction pseudo-capacitance, determined by the ions that are electrochemically absorbed onto surfaces of materials. 

The researchers noted, “Though they don’t store as much energy as lithium-ion batteries, these supercapacitors can charge much faster, making batteries based on plastic waste a good option for many applications.” While they were of the view that these batteries could be mass produced soon and pave the way for future experiments, they still wished to make improvements in electrical properties of the nonmaterial with compounds like boron, nitrogen, and phosphorous. “We believe that the proposed process is scalable, with environmental and economic advantages, and this study could present opportunities for future research and development,” they added.

This paper, however, is not the first to propose the use of plastic waste to make batteries for EVs. Another study published in 2019 and produced by researchers from Indiana’s Purdue University, described a method to extract pure carbon from plastic waste and turn it into anode material for lithium-ion batteries which could power a toy truck. Indeed, there is much hope for more innovations related to batteries to take place in the future, given the expected rise of EVs.   

Speaking of their latest success Mihri Ozkan, who teaches in UCR’s Marlan and Rosemary Bourns College of Engineering said, “Thirty percent of the global car fleet is expected to be electric by 2040, and high cost of raw battery materials is a challenge. Using waste from landfill and upcycling plastic bottles could lower the total cost of batteries while making the battery production sustainable on top of eliminating plastic pollution worldwide.” Doctoral student and first author Arash Mirjalili added, “We believe that this work has environmental and economic advantages and our approach can present opportunities for future research and development.”