With the world going digital and both traffic and mobile working machines being electrified, we will soon have to deal with mountains of discarded battery packs that are classified as hazardous waste. As the manufacturing of batteries drains our limited natural resources, could they be more effectively recycled? Researchers at Tampere University have developed a method that instantly reveals whether lithium-ion batteries can still be safely reused.
The CeLLife project carried out by a team of researchers at Tampere University studies and develops fast diagnostic methods to promote the safe, effective and sustainable reuse of batteries. Accurate state-of-health diagnostics will help to reduce the overall costs and environmental impact of batteries.
The CeLLife team has developed an electric fingerprint for batteries, demonstrating that a large number of batteries that end up in a recycling facility would still be salvageable. The unique method is capable to detecting the cells contained in a battery pack that are still reusable despite being weakened. This reduces the number of batteries that are crushed to recycle them.
“The technology we have developed is capable of detecting reusable cells among non-reusable cells. Up to 50–80% of cells in a battery pack can still be safely used in different applications”Tuomas Messo, senior research fellow and leader of the CeLLife project at Tampere University
Electric fingerprint enables the safe reuse of batteries
Although the recycling of batteries is mandatory under Finnish and EU laws, it is both difficult and expensive. When batteries are recycled, they are usually crushed and valuable raw materials, such as lithium and cobalt, are recovered with the help of chemical or mechanical processing.
Messo’s team believes that reuse is the best way to expand the lifespan of batteries. Cell compatibility is essential for the reuse of batteries, but verifying this compatibility is beyond the capabilities of conventional measurement techniques.
“The individual cells in a battery pack age at different rates. As the cells degrade, the performance of the battery deteriorates quickly and the battery can, for example, overheat. We have developed a method that takes a diagnostic snapshot of all the individual cells to determine their state-of-health and identify matching cells. The cells must be of uniform quality for them to be recycled into new, durable and safe battery packs”
Recycled batteries increase eBike lifespan
The charging method developed by the Tampere-based team can be used in a variety of applications, for example, in battery recycling facilities or battery production lines.
The CeLLife team collaborates, among others, with the Finnish eBike manufacturer Sähköpyöräkeskus. According to Messo, the new technology will initially be applied to electric bikes and electric scooters.
“We are, of course, looking to scale up the technology and move on to the testing of electric car batteries in the future,” Tuomas Messo points out.
The battery pack of an electric bike is usually composed of 50–100 cells, but the battery of an electric car or mobile machinery will contain thousands of cells. The battery of an electric car can last for up to ten years, whereas heavy-duty machines will wear out their battery systems in a couple of years.
High demand for products that promote a transition to a circular economy
The process of commercialising the method is already well underway. The team has applied for a patent for the measurement method, and a new startup company is set for launch in July 2022. Tuomas Messo encourages researchers who specialise in circular economy to keep an open mind when considering the potential applications of their research results.
“Demand is what determines commercial potential, but researchers should keep their options open when looking into potential applications. I would say that anything that reduces the use of raw materials has commercial potential”Messo
Jan Kolkkinen, innovation specialist at Tampere University, has been working with the team of researchers since the summer of 2019. He believes the key to the team’s success is their continuous dialogue with prospective customers.
“The CeLLife project has been so successful because the researchers have cooperated with customers right from the start, testing ideas and exploring customer needs. Instead of holding on to their original idea, they have collected more information to redirect their commercialisation efforts,” Kolkkinen says.
The CeLLife project has received Research to Business funding from Business Finland since January 2021. This funding supports, in particular, the study of the commercialisation opportunities of the new charging method developed by the CeLLife team.