© 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.