A battery pack in the lab. (credit: University of Warwick)

When electric vehicles end their life, the remaining storage capacity of the lithium battery is expected to be higher than 70%. After this, they can be reused for less demanding “second life” applications such as domestic and industrial energy storage.

Once EV batteries have fulfilled their lifespan for automotive applications, they are usually recycled by the manufacturer. However, many automotive Lithium-ion (Li-ion) batteries have enough life left in them after the car is scrapped for second life uses for both domestic and industrial applications.

To do this, it is necessary to grade the used batteries — identifying those suitable for use as spare parts, those suitable for second life, and those suitable for recycling of materials. This grading is traditionally a long and expensive process. Researchers at WMG, University, Warwick, however, have developed a new grading system that is “safe, robust and fast.” This methodology was successfully transferred to a pilot second-life facility, where the target of 1MWh of second-life energy storage was achieved. Nissan hopes to be able to re-use the vast majority of packs currently assembled in EVs in Europe.

In addition, the team at WMG developed ways of grading modules, the sub-components of battery packs, in as little as 3 minutes — a process that previously took over 3 hours. Graded second life battery packs can provide reliable and convenient energy storage options to a range of customers: from electric roaming products — providing electricity for customers on the move, to home storage products — enabling customers with solar panels to store energy. A really important function is storage to allow increased intermittent renewable energy sources on the grid, without putting security of supply at risk.

“Automotive batteries deliver some great environmental benefits, but they consume a lot of resources in doing so. Opening up a second life for batteries improves both the environmental and the economic value we draw from those resources before they need recycling. I’m delighted that by working with the partners in this project, we’ve been able to make it much easier to access those second life applications,” said Professor David Greenwood.

The algorithm was developed with assistance from AMETEK, Inc. EIS analyzers. AMETEK worked with WMG to embed their algorithms into a new robust, specialized industrial machine for doing the grading. It is currently being implemented in a new family of Solartron Analytical Battery Analyzer products.

“The number of electric vehicle batteries reaching end-of-service is set to increase from thousands to tens of thousands per annum by 2025. These batteries typically retain significant capacity and power-delivery capability, so their re-use in second life applications is a means to extend the battery value chain and minimize waste by deferring recycling,” said Francisco Carranza, Managing Director of Nissan Energy.