Bern University of Applied Sciences (BFH) is collaborating on a research project with e-bike manufacturer Thömus Ltd. Data points are being collected from a fleet of 200 e-bikes and analysed to provide information about batteries’ ageing process. The aim of the research project is to slow down the ageing of batteries and to make second-life battery applications possible.
Picture: Berner Fachhochschule
Developing a closed-loop circular economy for lithium-ion batteries is a challenge for research and industry alike. Batteries with a residual capacity of less than 80 percent are inadequate for mobility applications and most just get recycled, even though they could easily be used as stationary storage units in second-life applications. At the same time, the rise of battery-powered mobility applications is increasing the need to extend battery life for primary use.
In order to reduce batteries’ resource consumption, their service life must be extended. Accordingly, batteries that no longer meet the requirements of the mobility sector need to be given a second life in a different application, such as stationary energy storage. E-bike manufacturer Thömus Ltd is working with Bern University of Applied Sciences (BFH) and other partners in pursuit of this goal. “The aim is to better understand the ageing process that batteries undergo when they are being used by riders – in other words, to identify and ultimately avoid the conditions that damage batteries and that cause them to age quickly,” says Professor Priscilla Caliandro, Managing Co-Director of the Energy Storage Research Centre at BFH.
Every newly sold Twinner e-bike from Thömus Ltd captures valuable battery data for research purposes. This involves the logging of relevant data points, such as temperature, state of charge and amperage. The BFH research group led by Priscilla Caliandro and Andrea Vezzini has developed a statistical system specifically for such usage data. “Our system has two key advantages: it anonymises data immediately, so that it is impossible to deduce which route was travelled, and the storage space for recorded data is constant over the entire service life. In addition, the computing time needed for the subsequent analysis is significantly reduced because the microchip on the battery preprocesses the data before it is wirelessly uploaded to the server at BFH. Overall, this results in a very lean, low-cost system,” Caliandro points out. In the laboratory, the researchers then combine the usage data with an ageing model and develop optimal operational strategies.
This analysis will then be used to create a forecast of future battery performance and further service life. On one hand, this is crucial for battery safety, and on the other hand, it is essential for secondary-use business models. The researchers are currently working on improving the validity of their predictions and, together with other partners, on implementing the usage data gathering system in other applications. “We are also in talks with European partners,” remarks Caliandro with regard to future possibilities, “and we hope that our system will be added to the EU’s digital battery passport, which will contain all relevant data about the life cycle of a vehicle battery.” This will also bolster the market for used vehicles by making it easier to determine the value of the batteries and thus of the vehicles.
One previously missing component that is needed in order to improve the environmental footprint of e-bikes has been in use at Swiss Bike Park Oberried for some months now: a stationary battery storage facility. The electricity generated during the day by a photovoltaic system on a bike shelter is fed into a storage unit consisting of eight disused e-bike batteries – in a second-life application, for charging an e-bike test fleet at night. This prototype, suitable for single-family homes, demonstrates on a small scale how batteries from the electromobility sector can be integrated into the power supply, how storage capacity can be created for electrical energy from renewable sources, and how the sustainability of batteries can be improved. In the future, disused vehicle batteries could continue to be utilised in such stationary storage systems for many years to come.
The research at BFH is also part of CircuBAT, a Swiss research project for reducing the ecological footprint of lithium-ion batteries. The aim of CircuBAT is to establish a sustainable circular business model for lithium-ion batteries from the electromobility sector by 2025. This includes seeking solutions for greater sustainability at all stages of the life cycle. CircuBAT is funded by Innosuisse and 24 partners. Alongside BFH, which is also the lead institution for the project, six other Swiss research institutions are involved in this multidisciplinary project.
