Sustainable alternatives series: Breathe in a second life: How e-car batteries can be reused and recycled

The battery is at the heart of every electric car. So what happens, if it stops working as it should? If a battery’s performance drops, it often needs to be replaced. However, the battery’s life cycle does not end here. In this article we reveal the second life of an EV battery and what happens afterwards.

The lifecycle of a car battery has it’s limits: After eight to ten years or about 160,000 kilometers, the performance has usually dropped below 70 percent. The battery may then be no longer suitable for use in the vehicle it’s been used in before – but it still has plenty of power that can and should be harvested.

The first step is to check whether the battery can be reused in an EV after remanufacturing: For this, individual cells are replaced and the battery can be reused for replacement or other applications. Remanufacturing therefore avoids the production of a new battery and reduces the amount of waste, saving energy and raw materials.

Extending a battey’s life cycle

For batteries that are not apt for remanufacturing and reuse in a vehicle – for example, due to insufficient residual capacity – there is another solution to extend their life cycles. In second life battery storages the remaining energy of the battery’s cells are used. These storages provide concentrated energy and can cater to the grid.

BMW in cooperation with Bosch and energy company Vattenfall demonstrates how batteries can be secondarily utilised as flexible energy storage devices in their "Second Life Batteries" project which helps to ensure grid stability. Together the companies have connected around 2,600 battery modules from more than 100 BMW electric vehicles to form a power storage system. The first storage facility made from BMW i3 batteries has been built at the 122 MW onshore wind farm "Princess Alexia" near Amsterdam. With a capacity of 3.2 megawatts (MW), it is Vattenfall's first large-scale storage project in the Netherlands that supplies 88,000 households with clean electricity.The added batterie capacity helps store electricity from the wind turbines so that the wind farm can supply electricity even when the weather is relatively calm.

And Mercedes-Benz for example, together with technology company The Mobility House AG have built one of the largest 2nd-life battery storages for this purpose in Northrhine-Westphalia, Germany. A total of 1,000 batteries – all from smart fortwo electric drive models – are bundled into a huge storage system with a total capacity of twelve megawatts. The battery park is connected directly to the power grid and can store or release energy as needed. The power generated by the system is enough to light up all the street lamps in a city with over a million inhabitants.

Meanwhile Audi has joined forces with an Indian start-up to launch the secondary recycling of battery packs in Indian tuk-tuks. The cooperation partners want to convert the characteristic three-wheeled vehicles, which are common in many Asian metropolises, from combustion engines to electric drive. In this they support the Indian government in their plan to go electric in the coming decades.

These battery storage systems can compensate for fluctuations in the power grid to guarantee the balance of supply and demand: If there is too much electricity in the grid due to fluctuations in production or demand, the batteries store the surplus, if there is a shortage of electricity, the batteries supply it – within seconds. After about ten years, the power of a battery cell in second-life use is completely exhausted. It’s second life has come to an end and its time to feed reusable materials back to the production cycle.

And these examples are just to name a few. Many more new ideas and technologies to give batteries a second life are currently in the making.

Recycling: closing the material cycle

Did you know that up to 99% of a battery is recyclable. Tapping into innovative recycling methods is pivotal for a sustainable business model for electromobility. Battery housings, cables, and busbars can be recycled quite easily. The battery modules, which contain a large proportion of the rare materials, are more challenging. Existing processes still need to be refined so that the valuable raw materials in the battery cells can be recovered as purely as possible. However, today, various complex recycling processes make it possible to recover a great part of the materials for the production of new car batteries. The recovery process usually contains these three steps:

• 1. Separating: The outer plastic shell and any other plastic internal components are separated from the metal components. These are all valuable parts that can be used to make new batteries.
• 2. Shreding: Aluminum case, electrode material, and separator foil are then grounded into very small pieces in a special shredder.
• 3. Smelting: The most valuable materials, metals which come in the form of lead, nickel, and cobalt, are separated in two different steps: pyrometallurgy and hydrometallurgy. Pyrometallurgy involves shredding and burning the cells and other components of the battery, while hydrometallurgy dissolves them in acid.

The separated recycled materials go to a battery manufacturing plant, where they make up about 80% of new batteries. Today, the majority of EV batteries are currently in use in vehicles or second-life storage systems, hence, it will be some time before large numbers of old batteries can be recycled. For the car industry, the aim is to further optimize recycling processes. The recycling of lithium and cobalt, for example, still includes technical problems to be solved. In the case of lithium, recycling is not yet economical, as newly mined lithium is still cheaper than the raw material from recycling. However, this is expected to change given a swiftly increasing number of electric cars every year.