© Rainer Bez Fraunhofer IPA

Robot recycles batteries

Used batteries from electric cars contain raw materials that can still be used. In order to be able to recycle them, a research team from the Center for Digitized Battery Cell Production (ZDB) at Fraunhofer IPA is developing a robotic cell with very different tools. It should be able to carry out all the necessary steps of disassembly and be suitable for all types of batteries.

The electric drive is becoming more and more important for cars. Last year, around 13 percent of new vehicles in this country were already equipped with an electric drive, sometimes in combination with a combustion engine. By 2030, there could be nearly 50 million electric cars on the road worldwide if all the announcements come true.
This trend, due to climate change, is creating a recycling problem: more and more batteries are accumulating that need to be processed. Since a rechargeable battery lasts around ten years on average, the problem is becoming more pressing every year. A team of scientists and technicians from various institutes is therefore looking for a way to master this threatening flood. The research project “Industrial Disassembly of Batteries” (DeMoBat), coordinated by the Fraunhofer Institute for Manufacturing Engineering and Automation IPA, aims to deliver a universal solution that is suitable for all work steps and battery types.

Giving batteries a second life
The components of a battery cell are to be dismantled according to type and then checked to see whether they are still good enough for direct reuse. In this way, second-life batteries will one day be created from used components. If the used components are no longer suitable for this purpose, at least their chemical components should be reprocessed. This is because spent batteries contain many raw materials that can still be used, such as nickel, cobalt, manganese or lithium. To get to them, you first have to take the component apart: Wires, cables, plugs, seals, screws, battery cells, electronic components, brackets – it all has to be disassembled.

Lorenz Halt from the Robotics and Assistance Systems department at Fraunhofer IPA is responsible for this part of the research project. The challenge here: not a worker, but an industrial robot is to take over the work. This is all the more difficult because car batteries are not standardized. Different makes of cars, even different models, each have different power storage units. Therefore, the disassembly system must be very flexible. Halt therefore compares it to a Swiss Army knife.

Robot screws or mills the housing on
A two-by-three-meter table serves as the work surface, with a flexible clamping system that can firmly grip any battery. There, the robot first opens the lid by unscrewing the screws. Intelligent image processing shows him the way. But that doesn’t always work, because after ten years in the wind and weather, some screws are corroded and can only be loosened with more. Thanks to machine learning, the robot recognizes at an early stage whether it can reach its goal with a screwdriver or whether it needs to reach for a milling cutter.

“He could, of course, mill right away,” says researcher Halt. “But that’s not the optimal strategy, because it creates metal chips that could lead to a short circuit and ultimately a fire.” But the plant is also equipped for such cases: If a fire breaks out, a slide unceremoniously clears all parts lying on the work table into an extinguishing bath.

First demonstrator already this autumn
As with screws, the devil is in the detail elsewhere. Halt and his team had to solve numerous problems and develop new tools. Thus, a kind of can opener is used to loosen seals. And for lifting out the individual battery cells, which are glued together, the experts involved have developed a kind of mini jack. Resourcefulness is also required when handling cables and plugs that are difficult to grip.

The DeMoBat research project, which will run for a total of three years, has just reached the halfway point. The interim results are promising: the first demonstrator should be on display as early as this autumn. “In the future, we would also like to develop solutions that make it possible to process the recovered and still intact components of a battery for a further life cycle and reassemble them into a new system,” announces project manager Max Weeber.