A promising approach to increase a battery’s volumetric energy density of is to build it up in a bipolar design wherein adjacent electrode layers form separate galvanic cells. The electrodes are coated on one side with the anode material and with cathode material on the opposite side. Additional separator layers prevent electric shorts.

In the EMBATT project thyssenkrupp System Engineering develops the processes to assemble a bipolar battery stack consisting of bipolar electrodes. The process chain includes the steps active material ablation, sheet cutting, stacking, sealing, evacuation, and electrolyte fi lling.

EMBATT is a R&D project with the partners Fraunhofer IKTS and IAV GmbH which is funded by EFRE and the Free State of Saxony.

Test bench for laser based active material ablation

Abstract

Laser based electrode preparation and electrode stacking

- Key technologies for the production of bipolar li-ion-batteries

• Pulsed fi ber laser (P < 50 W) used for ablation• Galvanometer scanner with F-theta optics• Camera based correction

• Automatic roll-to-roll electrode cutting• Disk laser (P > 1000 W) and 3D PFO • Cutting speed up to 2 m/sec

Active material ablation and electrode cutting

Stacking and sealing

Automatic laser cutting of electrodes

Electrolyte fi lling tool

• Integrated process during stacking• Automatic application of injection tubes• Vacuuming and electrolyte injection

Electrolyte fi lling

Assembly machine for bipolar electrode stack

M. A. Roscher, T. Echelmeyer, J. Schulze, L. Ebert, S. Dietzsch | thyssenkrupp System Engineering GmbH, Zeißigstraße 12, 09337 Hohenstein-Ernstthal, Germany

The bipolar electrodes consist of e.g. aluminum collector foils with an anode coating (e.g. LTO) on the fi rst and a cathode coating (e.g. LFP, NMC, LNMO) on the opposite site. For bipolar battery assembly the electrode sheets are laser cut out from a continuous band. After that, the shape of the coated patterns is modifi ed by using laser ablation in order to produce electrodes with the required dimensions (shape, coating edges).Stacking the electrodes yields the serial connection of Li-ion cells. During stacking the electrodes the electrolyte is injected in the space between the electrode layers and subsequently the layers are sealed hermetically.

Gripper for planar substrates

• Semi-automatic stacking station with 3D gantry • Feeding stations for electrodes and separator foils• Sealant application • Planar gripping system applicable for electrode

and separator• Pressing and sealant hardening (thermal/UV)