With the growing number of electric vehicles, the amount of used batteries, as well as new, unused batteries that remain in OEM warehouses and ultimately go unused, is increasing. A promising approach to addressing this problem is the concept of “second-life batteries.” These are batteries that have either reached the end of their life in electric vehicles (but still retain a capacity of around 70% to 80%) or have been stored too long in OEM warehouses, reducing their expected lifespan before they could be installed in vehicles. These batteries can still be valuable for other applications (“second-life”), particularly as stationary energy storage systems, offering both economic and ecological benefits. It’s important to note that with the ongoing transition to electromobility, we can expect very large battery capacities that, after their use in the mobility sector, could become available as second-life batteries.
Advantages of Second-Life Batteries
1. Cost Efficiency in Acquisition
The production of new batteries is expensive and resource-intensive. Second-life batteries have already been depreciated, making them fundamentally cheaper to acquire. Used batteries for stationary storage solutions can be around 30% cheaper than new batteries.
2. Environmental Protection
By reusing these batteries, the lifespan of valuable raw materials such as lithium, cobalt, and nickel is extended. This reduces the demand for new resources and lowers the environmental impact associated with mining and processing these materials. Additionally, the carbon footprint is improved since the production of new batteries is highly energy-intensive.
While the benefits are generally convincing, the use of second-life batteries comes with risks and challenges that could hinder broad commercialization.
Risks and Challenges
1. Technical Risks
Since second-life batteries have already been used in vehicles, their remaining lifespan is difficult to predict. Their performance can vary significantly, and they may have a higher failure rate (see, for example, VDE). To minimize these uncertainties, regular monitoring and assessment of their capacity and performance is necessary, which can be costly.
2. Lack of Standardization
Another issue is the lack of standardization between different battery manufacturers. Batteries vary in terms of design, chemistry, and performance, making integration into stationary storage solutions more difficult. There are efforts to develop standards, but currently, customized solutions are required, which can increase costs.
3. Falling Costs of New Batteries
A financial risk for second-life batteries lies in the ongoing development of new battery technologies. The price of new batteries is continuously decreasing, which could reduce the attractiveness of second-life solutions. If the price of new products continues to drop, the window of economic viability for used batteries could shrink further.
Just a few days ago, EnBW announced the launch of an innovative project at the Haslach solar park in Rot an der Rot to integrate second-life batteries into renewable energy systems. In this project, used batteries from Audi electric vehicles (audi e‑tron) will be repurposed to store solar energy. In 2025, the battery storage system is planned to be built with a capacity of 2.4 MWh and put into operation. The capacity of this storage system is significantly smaller compared to other projects using new batteries, which underscores that second-life batteries are still in an experimental phase and occupy a niche.
