Bipolar plate for an electrolyzer, electrolyzer and method for producing a bipolar plate

Abstract

A bipolar plate for an electrolyzer, particularly a PEM electrolyzer, is formed with a central region and a peripheral region surrounding the central region. With a view to cost-effective production of the bipolar plate, the central region is made of metal sheet and the peripheral region is formed from a plastic frame. The plastic frame is made of at least one thermoplastic, particularly at least one high-temperature thermoplastic, and is injection-molded around the sheet metal.

Claims

1. A bipolar plate for an electrolyzer, the bipolar plate comprising: a central region formed of a metallic sheet; and a peripheral region surrounding said central region, said peripheral region being a plastic frame formed of a thermoplastic molded around said metallic sheet; said plastic frame having distribution channels formed therein and a plurality of rib elements between said distribution channels, said rib elements being configured and formed on said plastic frame for enhancing a rigidity and a strength of said plastic frame, said plastic frame having an outermost rim forming a peripheral boundary of the bipolar plate and said ribs extending perpendicularly outward from said central region between said central region and said outermost rim.

2. The bipolar plate according to claim 1, configured specifically for a PEM electrolyzer.

3. The bipolar plate according to claim 1, wherein said plastic frame is formed of at least one thermoplastic selected from the group consisting of polyetheretherketone (PEEK), polyphenylene sulfide (PPS), polysulfone (PSU), polyether sulfone (PES), polyetherimide (PEI), and aromatic polyamide (PA6/6T).

4. The bipolar plate according to claim 1, wherein said distribution channels for operating media are integrated only into said plastic frame.

5. The bipolar plate according to claim 1, wherein said plastic frame is formed with at least one groove for insertion of a seal between said central region and said ribs.

6. The bipolar plate according to claim 1, which comprises a seal molded onto said plastic frame between said central region and said ribs.

7. The bipolar plate according to claim 1, wherein said plastic frame consists of a plurality of different types of plastic.

8. The bipolar plate according to claim 1, wherein said plate is formed of a metal selected from the group consisting of titanium, stainless steel, and combinations thereof.

9. An electrolyzer, comprising at least one bipolar plate according to claim 1.

10. The electrolyzer according to claim 9, configured as a PEM electrolyzer.

11. A method of producing a bipolar plate, the method which comprises producing a metallic plate and molding a plastic frame around the plate, to thereby form the bipolar plate according to claim 1.

Description

BRIEF DESCRIPTION OF THE DRAWING

(1) The single FIGURE of the drawing shows a bipolar plate for an electrolysis cell.

DESCRIPTION OF THE INVENTION

(2) An exemplary embodiment of the invention is explained in greater detail with reference to a drawing. Here the single figure shows a bipolar plate 2 for an electrolysis cell of a PEM electrolyzer not shown in any greater detail. The bipolar plate 2 comprises a central region 3 made from a metallic sheet 4, as well as a peripheral region 5, which is formed by a plastic frame 6. In the exemplary embodiment shown the bipolar plate 2 has been produced by molding the plastic frame 6 around the completed metal plate 4 and in this way a non-releasable connection between the metal plate 4 and the plastic frame 6 has been created.

(3) The central area 3 is defined by this area not being in any direct contact with the membrane of the membrane-electrode-assembly during operation. The peripheral region is the area of the bipolar plate 2 which surrounds the central region and in parts is in direct contact with a polymer electrolyte membrane (PEM).

(4) The metal sheet 4 is a flat sheet consisting exclusively of titanium or stainless steel, having a smooth, flat surface on both sides. The metal sheet 4 has a thickness in the order of a few millimeters, especially 1 to 2 mm. The size of the metal sheet 4 essentially corresponds to the size of the active electrode surface of a membrane-electrode assembly not shown in any greater detail here. The size of the metal sheet 4 is selected so that, in the assembled state of the electrolysis cell, the metal sheet 4 merely contacts one of the electrodes indirectly via a gas diffusion layer 4. In the assembled state of the electrolysis cell or of the PEM electrolyzer there is no direct contact between the metal sheet 4 and the heavily acid surface of the membrane.

(5) In the assembled state of the PEM electrolyzer the bipolar plate 2 shown in the figure can be supplemented by additional contact, distribution, support and/or reinforcement elements in order to make possible a stable construction and trouble-free operation of the electrolyzer.

(6) By contrast with the metallic plate 4 the plastic frame 6 has a heavily-profiled surface. In the corners of the plastic frame 6 distribution channels 8a, 8b, 8c and 8d are provided for supply of water and removal of the oxygen and hydrogen gases generated in the electrolysis cell. A number of rib elements are provided between the distribution channels 8a, 8b, 8c and 8d to achieve a greater rigidity and firmness. In addition a groove 12 is provided around the central region for receiving an insert seal. In the exemplary embodiment shown the groove 12 (with brief interruptions) also runs around the distribution channels 8b, 8d, so that the metal sheet 4 as well as the distribution channels 8b and 8d are sealed by a single ring-shaped seal. Separate groups 14 are provided around the distribution channels 8a, 8c, so that the seals which are inserted into these grooves 14 merely seal the respective distribution channel 8a, 8c. As an alternative a central seal extends around the central region and the distribution channels 8a, 8b, 8c, 8d are sealed individually.

(7) The plastic frame 6 is embodied from at least one thermoplastic, especially from a high temperature thermoplastic, such as e.g. PEEK or PPS. Depending on the requirements imposed on the different functional areas of plastic frame 6, said area can also be embodied from different plastics. The functional areas which are imposed to a high mechanical stress, e.g. the distribution channels 8a, 8b, 8c and 8d, can also be reinforced by additional elements, e.g. insert elements made of metal or plastic.

(8) The bipolar plate 2 described above is primarily characterized by its low-cost production. Only the flat metal plate 4 is produced from the expensive material titanium or stainless steel. The rest of the bipolar plate 2 is made of low-cost plastic. Since the production method of the plastic frame 6 allows great freedom in relation to the molding of the plastic frame 6, the bipolar plate 2 shown is thus able to be produced simply and in few stages.