A miniature model of the demonstrator.
A miniature model of the demonstrator.
( Source: TU Berlin/Arne Glodde)

Battery Production Z-folding continuously increases battery cell production by 150 percent

| Author/ Editor: Katharina Juschkat / Florian Richert

Lithium-ion batteries are costly to manufacture - but now the TU Berlin has developed a more efficient process that is expected to increase the throughput by 150 percent.

Electro-mobility is on the rise, but electric cars are still very expensive. One high-cost factor is the battery or battery cells in particular. At the moment, this is due to very inefficient production. TU Berlin has developed a new production process for lithium-ion battery cells that are intended to reduce time and costs: continuous Z-folding.

How batteries are manufactured to date

Battery cells for electric cars consist of electrode-separator composites, i.e. thin metallic electrode foils and extremely thin separator foils made of plastic between them. A Z-structure is formed in the battery. Such an arrangement enables a very high energy density in comparison to other composite designs so that electric cars can draw as much energy as possible from one battery charge and can be driven as far as possible until the battery needs to be recharged.

Previous methods of manufacturing these batteries include "pick-and-place" movements. Robots pick up and position the electrode and separator foils one on top of the other piece by piece. In the nature of this process, time-consuming movements and downtimes occur when the robot systems move back and forth. The time required leads to a limitation of throughput and thus to a cost-driving process step in battery cell production.

Avoiding downtimes in the workflow

The new procedure of the Department of Assembly and Handling Technology of the TU Berlin avoids downtimes in the process by a continuous material movement. This is intended to increase throughput by around 150 percent compared to the international status of technology. Meaning that in the time, in which today 100 batteries are produced, 250 batteries could be manufactured in the future with the new procedure. The use of transport systems with linearly circulating grippers allows continuous creasing. The electrodes are available as cut foils and the separator foil as strip material.

Principle of operation of the patented Z-fold.
Principle of operation of the patented Z-fold.
(Source: TU Berlin/Arne Glodde)

With the patented process, the research project is currently in a demonstration phase. In the KontiBAT project, funded by the Federal Ministry of Education and Research, a demonstrator is currently being developed that shows the functional principle of continuous Z-folding. With the targeted increase in throughput in production, the new process would be a leap forward innovation for the battery cell industry.

After the project's end in 2020, the demonstrator will be further developed into a near-series prototype together with practical partners in plant construction, system integration, and cell production. Now the project team is looking for cooperation partners from industry in order to jointly transfer the innovation further into application, as well as from science in order to further develop the process in a follow-up project and transfer it to other areas of application.