Automobile manufacturers usually give a warranty on the drive battery of an electric vehicle, which roughly corresponds to the average service life of a vehicle. This is in the range of eight years or 160,000 km. In practice, however, the batteries can also have a significantly longer service life. An initial indication of this is provided by vehicles at a Tesla rental in California, some of which have reached a mileage of up to 800,000 km without the need to replace the battery.
If the battery has only 70 to 80 percent of its original capacity left, after approximately 1,500 to 2,500 charging cycles, its performance is no longer sufficient for use in the vehicle. In this state, however, it makes neither economic nor ecological sense to dispose of the lithium-ion batteries. On the other hand, the batteries can continue to be used in stationary operation. Laboratory measurements have shown that due to the uniformly slow charging and discharging, use for up to 12 more years is possible. With average use, a traction battery would therefore only have to be disposed of after around 20 years.
For a holistic view of the battery life cycle, many automakers are also pursuing projects that help traction batteries have a “second life.”
- In this context, VW plans to use traction batteries for mobile charging columns based on the principle of a power bank, each with a charging capacity of 360 kWh. In self-sufficient operation, such a charging column will enable the charging of up to 15 electric vehicles.
- Together with Connected Energy, Renault is pursuing a similar model. Used batteries are to be used to provide fast-charging columns in locations where a high-capacity connection to the power grid would be very expensive. The batteries in the charging station can be charged at low power and release the stored energy at high power to an electric vehicle for charging.
- BMW and Bosch have joined forces with energy company Vattenfall to connect around 2,600 battery modules from more than 100 BMW electric vehicles to form an electricity storage system in the Port of Hamburg. This electricity storage system has a storage capacity of almost three megawatt hours, which could supply an average two-person household with electricity for seven months. However, the storage facility is used to balance out fluctuations and demand peaks in the primary energy market. The batteries are thus charged and discharged according to the requirements of the power grid, which means that the required electricity can be made available within a few seconds.
Stationary large-scale storage facilities with retired lithium-ion batteries from electric vehicles are also already being used as intermediate storage for solar and wind energy. “Second Life” projects thus make it possible to link the transportation and energy transformation.
If the capacity of a battery is less than 30%, it must be recycled. In order to be able to reuse the large number of important and rare raw materials, companies worldwide are working on developing appropriate recycling processes. (Read more about the raw material extraction of a traction battery here) However, the number of traction batteries of electric vehicles to be recycled is currently still very small, which is why recycling on the industrial scale that will be necessary in the future is not yet possible.
The market leader in battery recycling is the Belgian company Umicore. The company uses the most common type of battery recycling to date: thermal fusion. The battery is first burned and then ground. The raw materials cobalt, nickel and copper are recovered in this way. However, lithium, graphite, aluminum and the electrolyte cannot be returned to the cycle in this way.
The German chemical company Duesenfeld has developed a different process. The highly flammable batteries are shredded under nitrogen until only crushed material and the electrolyte remain. 96% of all battery components, including the rare raw materials, are thus recycled and go into the (re)production of new traction batteries.
The Frauenhofer Institute for Materials Recycling and Resource Strategy (IWKS) relies on electrohydraulic shredding. In the mechanical process, the lithium-ion batteries can be disassembled by controlled shock waves, which requires little energy. Housing parts, electrode foils, separators and the active materials of the electrodes can then be separated and reused using specific separation processes.
The extent to which the challenge of sustainable recycling of lithium-ion batteries can be successfully mastered in the long term will only become clear in the course of the next few years. Automobile manufacturers are increasingly launching electric vehicles on the market, investments are being made in the expansion of a nationwide charging infrastructure, and the acceptance of electrically powered vehicles among the population is also steadily increasing. Used traction batteries will therefore come onto the market all by themselves, and existing solutions will have to be further expanded and innovative concepts found for their second life or recycling.