Batteries recycled by robots

The spent bat­ter­ies of elec­tric cars con­tain valu­able 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 a wide vari­ety of tools. It should be able to car­ry out all the nec­es­sary dis­as­sem­bly steps and be suit­able for all bat­tery types.

Elec­tric dri­ves are becom­ing increas­ing­ly 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 an inter­nal com­bus­tion engine. By 2030, there could be almost 50 mil­lion elec­tric cars on the roads world­wide, if all the announce­ments come true.
This trend, due to cli­mate change, cre­ates a recy­cling prob­lem: More and more bat­ter­ies are accu­mu­lat­ing that need to be refur­bished. Since a bat­tery lasts about 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 cope with this impend­ing flood. The “Indus­tri­al Dis­as­sem­bly of Bat­ter­ies” (DeMo­Bat) research project, 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 test­ed to deter­mine whether they are still good enough for direct reuse. In this way, sec­ond-life bat­ter­ies will one day be made from used com­po­nents. If the used com­po­nents are no longer suit­able for this pur­pose, at least their chem­i­cal com­po­nents should be processed. Used bat­ter­ies con­tain many raw mate­ri­als that can still be used, such as nick­el, cobalt, man­ganese and lithi­um. To get at them, the com­po­nent first has to be tak­en apart: Wires, cables, plugs, seals, screws, bat­tery cells, elec­tron­ic com­po­nents, brack­ets — it all has to be dismantled.

Lorenz Halt from the Robot­ics and Assis­tance Sys­tems depart­ment at Fraun­hofer IPA is respon­si­ble for this part of the research project. The chal­lenge here is that the work is to be car­ried out by an indus­tri­al robot rather than a work­er. This is all the more dif­fi­cult because car bat­ter­ies are not stan­dard­ized. Dif­fer­ent makes of car, even dif­fer­ent mod­els, each con­tain dif­fer­ent pow­er stor­age units. That’s why the dis­as­sem­bly sys­tem has to be very flex­i­ble. Halt there­fore com­pares it to a Swiss army knife.

Robot unscrews or mills the housing

A two-by-three-meter table with a flex­i­ble clamp­ing sys­tem that can firm­ly grip any bat­tery serves as the work sur­face. There, the robot first opens the lid by unscrew­ing the screws. Intel­li­gent image pro­cess­ing shows it 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 ear­ly on whether it can reach its goal with the screw­driv­er or whether it needs to reach for the milling machine.

“It 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 as early as this fall

As with the screws, the dev­il is in the details else­where, too. Halt and his team had to solve numer­ous prob­lems and devel­op new tools. For exam­ple, 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. Inge­nu­ity is also required to han­dle cables and con­nec­tors 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: a first demon­stra­tor should be on dis­play as ear­ly as this fall. “In the future, we also want 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.