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Low-cost bipolar plates: Fibre-reinforced compound films for lightweight fuel cells

Can bipolar plates be made thinner and cheaper by reinforcing compound films with carbon fibre? Researchers from ZBT and Leibniz Institute for Composite Materials are investigating this idea.

Planned production process from compounding to embossed, fibre-reinforced bipolar film (click to enlarge)

Extrusion of bipolar films in the pilot plant at ZBT. Mechanical defects are to be prevented by carbon fibres. (click to enlarge)

Bipolar plates (BPP) in low-temperature fuel cells are exposed to high thermal and mechanical loads. In a joint project, ZBT and Leibniz Institute for Composite Materials (Leibniz-Institut für Verbundwerkstoffe) in Kaiserslautern, Germany are pursuing an innovative idea to produce inexpensive, thin, yet resistant plates: Highly filled calendered compound films with thicknesses below 1 mm are to be reinforced with carbon fibres.

For this purpose, the compound films are to be produced in a continuous process directly from the extruder melt via a wide slot die and a rolling mill and then mechanically reinforced by pressing in carbon fibres (continuous fibres or fabric). In a further step, the necessary functional structures are introduced into the fibre-reinforced films by means of variothermal pressing processes.

Due to the continuous manufacturing process, the forming of electrically and thermally conductive plastic films offers the potential to significantly reduce the manufacturing costs of PEM fuel cells and to reduce the BPP thickness. Prerequisite: The formed films must be sufficiently mechanically stable despite their low residual wall thickness. This is to be achieved by reinforcing the compound films with fibres before forming.

The mass production of bipolar sheets – distributed among different SMEs along the value chain (compound production, film extrusion, reinforcement with C-fibres, forming/embossing) – is thereby decoupled from the specific application, so that a wide range of uses for the bipolar sheets with different embossing designs would be possible. The investigated manufacturing process could enable SMEs in the rapidly growing fuel cell manufacturing sector to produce suitable plates for mass applications in the medium power range (trucks, CHP) up to large megawatt applications (stationary power supply, shipping, aviation).

Department Fuel Cells & Stacks

IGF No. 22342 N
Project period: 01 JUL 2022 - 30 JUN 2024 (2 years)

Project partner:
Leibniz-Institut für Verbundwerkstoffe (IVW)
Erwin-Schrödinger-Strasse 58
67663 Kaiserslautern

Funding body:
IUTA - Institute for Energy and Environmental Technology
IGF - Industrial Cooperative Research
AiF - Alliance for Industrial Research
Federal Ministry of Economic Affairs and Climate Action

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