The ability to re-use high numbers of electric-vehicle (EV) Lithium-ion (Li-ion) batteries for domestic and industrial use is becoming a reality for Nissan, thanks to a new grading system developed by researchers at WMG (part of the University of Warwick).

When EV batteries have completed their life-span, they are usually recycled by the manufacturer, but many automotive Li-ion batteries have enough life left in them after the car is scrapped for ‘second life’ uses, both domestically and industrially.

To achieve 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 the materials.

This grading process has traditionally been a long and expensive process.

Car manufacturer Nissan (www.nissan-global.com) was keen to find a much faster grading process for used Li-ion batteries from the Nissan Leaf.

Part-funded by the Business Department, the ‘UK Energy Storage Laboratory’ project was launched, and 50 Nissan Leaf batteries were used to improve the existing grading process (led by Nissan, WMG, AMETEK and Element Energy).

WMG’s battery technology experts at the Energy Innovation Centre developed a safe, robust and fast methodology, and this was successfully transferred to a pilot second-life facility, where a target of 1MWh of second-life energy storage was achieved.

In addition, the team at WMG (www.warwick.ac.uk) developed ways of grading battery-pack modules in as little as 3min, compared to over 3hr previously.

Graded second-life battery packs can provide reliable and convenient energy storage options for a range of applications, including storing the energy from solar panels.