Battery for electrolysis with multi-layer component material connection and method for manufacturing such

Abstract

The invention relates to a cell (1, 11) for electrolysis, at least comprising: a layer sequence consisting of a bipolar plate (BPP), at least one cathode gas diffusion layer (PTLC), a proton exchange membrane (PEM) or a catalyst-coated membrane (CCM) located between a plurality of catalyst layers (CLC, CLA), and at least one anode gas diffusion layer (PTLA), which are arranged in a frame (4), a material connection (Con) is present between at least the individual layers of BPP, PTLAC and / or PTLBC.

Description

Technical Field

[0001] The present invention relates to a multilayer component in an electrochemical cell (e.g., an electrolytic cell) and a method for manufacturing the electrochemical cell. Background Technology

[0002] An electrolyzer is a device that uses an electric current to initiate a material conversion (electrolysis). Corresponding to the various types of electrolysis, there are also various types of electrolyzers, such as those used for water electrolysis.

[0003] The current consideration is to store excess energy from renewable energy sources during periods of abundant sunshine and wind, i.e., when solar or wind power generation is above average. This conversion can be achieved using electrochemical cells, particularly fuel cells or electrolyzers. Energy storage can also be achieved by producing energy carriers. Hydrogen, produced using a water electrolyzer, is one such chemical energy carrier. Hydrogen can be used to produce, for example, so-called EE gases.

[0004] In this scenario, the water electrolyzer, using electricity, particularly from wind or solar power, first produces hydrogen, oxygen, and waste heat. The hydrogen can then be used in the Sabatier process, along with carbon dioxide, to produce methane. The methane can then be fed into an existing natural gas network, thereby enabling storage and energy delivery to the consumption end, thus relieving pressure on the power grid. Alternatively, hydrogen can be mixed into either a natural gas network or a pure hydrogen network.

[0005] Alternatively, the hydrogen produced by the electrolyzer can be directly utilized, for example, in fuel cells.

[0006] In electrolyzers used for water electrolysis, water is electrochemically decomposed into hydrogen and oxygen. For PEM electrolyzers, distilled water is typically supplied as the reactant at the anode side. During this process, water is oxidized at the anode, at the catalyst used for the oxygen evolution reaction, into oxygen, protons, and electrons. The protons pass through a proton exchange membrane (PEM) that acts as the electrolyte.

[0007] On the cathode side, protons are reduced to hydrogen along with electrons at the catalyst used for the hydrogen evolution reaction.

[0008] A typical PEM electrolyzer structure includes at least one porous transport layer (gas diffusion layer) on both the anode and cathode sides, as well as catalyst layers. A proton exchange membrane (PEM) is arranged between these catalyst layers. Individual cells are separated by bipolar plates (BPPs). All layers are arranged within a cell frame. A disadvantage is that the arrangement of the gas diffusion layer within the cell frame must currently be very precise to manufacture a reliable electrolyzer. This makes component manufacturing and assembly complex and expensive.

[0009] Document DE 25 33 728 A1 discloses an electrolytic cell for the electrolysis of alkaline salt solutions. The electrolytic cell includes bipolar electrodes arranged adjacent to each other and at least one outer frame surrounding at least one chamber of the electrolysis region.

[0010] Other electrochemical cells with sealed battery frames are described in US 6,117,287 and US 2002 / 068208 A1.

[0011] A method for manufacturing a PEM film electrode unit is described in document CN 107 881 528 A.

[0012] In this type of electrochemical stack, several cells are connected in series and operate as a stack.

[0013] Each cell contains a variety of components: a proton exchange membrane (PEM), metal bipolar plates (BPP), a porous transport layer (PTL) (also known as a gas diffusion layer (GDL)) made of metal or carbon (the latter is used only for the cathode), and also a catalyst layer (CL) and a membrane (PEM).

[0014] Typically, the CL and PEM of the anode and cathode are further processed into a catalyst-coated membrane (CCM).

[0015] In addition, other components, such as seals and frames, are used. The current solution stipulates that components BPP, PTL, CCM (as well as frames and seals) must exist separately, be connected to each other in sequence, and be repeatedly stacked.

[0016] PEM components must withstand the potentially harsh conditions that may occur during electrolytic operation. This includes the electrochemical potentials of the anode and cathode, oxygen or hydrogen atmospheres and deionized water, acidic membranes and their potential degradation products (including HF), and metal cation contamination (e.g., due to the equipment's process flow). Therefore, typically, titanium is used as the base material for BPP and anode GDL, while stainless steel or carbon, or also titanium, is used for cathode GDL.

[0017] This presents the following challenges and problems:

[0018] - Electrochemical loss and corrosion during operation

[0019] - The (ohmic) contact resistance at the interface, referring here to the contact resistance between the metal component BPP and one or more PTLs, reduces efficiency.

[0020] - Interfaces between components where corrosion may occur.

[0021] Contact resistance and corrosion may increase or intensify during operation, thereby impairing efficiency and potentially shortening service life.

[0022] Manufacturing and assembly

[0023] - Several sequential working steps during stacking (e.g., for each cell): i) BPP placement, ii) seal placement, iii) frame placement, iv) PTL (anode) placement, v) CCM placement, vi) PTL (cathode) placement, and the resources consumed (time, manpower, machine time).

[0024] The tolerances, tolerance compensation, and positioning required by the interaction of a large number of individual components introduce assembly and quality complexities, from cargo inspection or component inspection to stacking of fuel cells. Summary of the Invention

[0025] Therefore, the object of the present invention is to solve the problems mentioned above.

[0026] This objective is achieved by the battery according to claim 1 and the method according to claim 7.

[0027] The dependent claims list other preferred measures that can be combined with each other to achieve further advantages. Attached Figure Description

[0028] The attached diagram shows:

[0029] Figure 1 The arrangement in the prior art,

[0030] Figure 2 , Figure 3 The arrangement according to the present invention.

[0031] The accompanying drawings and descriptions illustrate only embodiments of the present invention. Detailed Implementation

[0032] according to Figure 1 The exemplary battery 1' is a prior art solution having a component BPP and multiple PTLs (anode PTLA; cathode PTLC) that are individually stacked on top of each other. Figure 1 The battery design shown has one BPP, two cathode PTLs (PTLC1, PTLC2), three anode PTLs (PTLA1, PTL2, PTL3), and a PEM (i.e., CCM) with adjacent CLA and CLC.

[0033] These components are constructed in layers.

[0034] The contact resistance between components (which, especially on the anode side, may increase with the duration of electrolysis operation) and the potential corrosion surfaces are reduced or protected in part by relatively complex and expensive noble metal coatings (Pt, Ir).

[0035] Figure 2 A battery 1 according to the present invention is shown, wherein the present invention provides a material connection portion Con between the BPP and PTLA, between the plurality of PTLAs, and optionally between the BPP and the metal PTLC.

[0036] This invention is based on Figure 3 An exemplary battery 11 is shown, which has a structured BPP, i.e., using a flow field, such as being channel-shaped, and has material connections Con between the protrusions of the BPP and the PTLA and optionally also between the protrusions and one or more metal PTLCs.

[0037] The advantage of this is that it reduces the contact area and therefore the area that must be bonded with materials, which simplifies the material bonding process. It is advantageous to maintain the cross-sectional area of ​​the channel 14 as a percentage of the total cross-sectional area of ​​the PTLC or PTLA1.

[0038] In principle, the material connection Con between the BPP and PTL can be achieved through a suitable joining process, such as sintering, brazing, or welding. During this process, the components can be joined to each other simultaneously or sequentially, and preferably, form tolerances and position tolerances are checked sequentially.

[0039] This solution can be applied not only to water electrolysis systems or batteries 1, 11 ( Figure 2 and Figure 3It can also be applied to other electrochemical batteries, such as fuel cells and primary cells.

[0040] For example, in PEM water electrolysis, various components (BPP, PTL, CCM, frame, seals, etc.) are currently manufactured separately and assembled and stacked sequentially.

[0041] The invention described above enables pre-material bonding or pre-assembly of BPP and PTL.

[0042] Therefore, the present invention offers advantages during the manufacture and assembly of the fuel cell stack, as well as during operation. Consequently, savings and improvements can be achieved in cost areas, such as CAPEX and OPEX, as described below.

[0043] Electrochemical loss and corrosion during operation

[0044] - The material bonding between the BPP and one or more PTLs avoids contact points with contact resistance.

[0045] - The material bonding between the BPP and one or more PTLs avoids the formation of a poorly conductive metal oxide layer and the associated ohmic resistance that typically grows during electrolytic operation.

[0046] - The material bond between the BPP and one or more PTLs avoids interfaces that could potentially corrode.

[0047] - No more coating treatment is required for contact areas or interfaces.

[0048] Manufacturing and assembly

[0049] - Assembly is made easier by reducing the number of steps, as it only requires inserting pre-fabricated component assemblies.

[0050] - It is easier to achieve a higher degree of automation in assembly, because, for example, component complexes can be guided and placed with the help of robots.

[0051] - The positioning or form tolerances of PTL and BPP relative to each other can be performed and checked during pre-assembly. This avoids possible slippage of the individual parts relative to each other during subsequent assembly processes.

[0052] - Because the components are joined together, replacement in repair and maintenance applications can be simplified.

[0053] The layers (PTLC, BPP, PTLA) are preferably bonded to each other sequentially, that is, in particular, one PTLC is bonded first. Figure 3 (or each PTLC, then join the BPP, and finally join each PTLA.)

[0054] The layers (PTLC, BPP, PTLA) can also preferably be bonded to each other in one go.

[0055] Preferably, multiple layers (PTLC, BPP, PTLA) can be bonded to each other, but not all layers are bonded to each other at once. That is, PTLC1+PTLC2 is bonded first, then BPP+PTLA1 is bonded to it, and then PTLA2+PTLA3 is bonded to it.

[0056] Also preferably, the various types of layers (PTLC, PTLA) can be bonded separately and then optionally bonded to a bipolar plate (BPP).

[0057] Preferably, the bipolar plate (BPP) is integral, i.e., a single piece, and is not formed by joining or welding two or more parts together (at least at the layer level). If necessary, a flow field is machined into the bipolar plate (BPP).

[0058] It allows for large-area bonding, as well as point-like, linear, or meandering bonding, which reduces energy input and complexity. This is particularly significant for welding.

[0059] Single or multiple components can be joined together by means of sintering, welding or brazing.

[0060] The material connection point Con is clearly identifiable.

[0061] If bonding is achieved through sintering, there are diffusion regions between the layers (PTLC, BPP, PTLA).

[0062] If the layers are joined by welding, there must be at least a molten region and / or other microstructures or grain structures between the layers (PTLC, BPP, PTLA).

Claims

1. A battery for electrolysis (1, 11). At least have: Composed of bipolar plates (BPP), At least one cathode gas diffusion layer (PTLC) A proton exchange membrane (PEM) located between multiple catalyst layers (CLC, CLA) or a catalyst-coated membrane (CCM). At least one anodic gas diffusion layer (PTLA) The constructed layer sequence, They are arranged in a frame (4), in, There is at least one material connection (Con) between each of the layers of at least the bipolar plate (BPP), at least one anode gas diffusion layer (PTLA) and / or at least one cathode gas diffusion layer (PTLC).

2. The battery according to claim 1, The battery frame (4) has at least one seal (7). The seal is adjacent to the proton exchange membrane (PEM).

3. The battery according to claim 1 or 2, The bipolar plates (BPP) of the battery are structured and have a flow field (14). Specifically, the channel occupies 60% to 40% of the cross-sectional area of ​​the bipolar plate (BPP).

4. The battery according to one or more of claims 1, 2, or 3, The battery has at least two cathode gas diffusion layers (PTLC) and / or At least three anodic gas diffusion layers (PTLA).

5. The battery according to one or more of claims 1, 2, or 3, The battery has only one cathode gas diffusion layer (PTLC) and / or At most two anodic gas diffusion layers (PTLA).

6. The battery according to one or more of claims 1, 2, 3, 4 or 5, In the battery, each individual layer is bonded to the next. In particular, The bipolar plate (BPP) Each layer is bonded to the cathode gas diffusion layer (PTLC). and Specifically, the anode gas diffusion layer (PTLA) and the cathode gas diffusion layer (PTLC) They joined together separately.

7. The battery according to one or more of claims 1, 2, 3, 4, 5 or 6, In this battery, the bipolar plate (BPP) is integrally constructed.

8. A method for manufacturing a battery (1, 11) according to one or more of the preceding claims, In this method, the individual layers (PTLC, BPP, PTLA) are bonded to each other.

9. The method according to claim 8, In the method, the layers (PTLC, BPP, PTLA) are sequentially bonded to each other.

10. The method according to claim 8, In this method, the individual layers (PTLC, BPP, PTLA) are bonded to each other in a single step.

11. The method according to claim 8, In the method described, there are multiple layers (PTLC, BPP, PTLA). However, not all layers are joined together at once.

12. The method according to claim 8, In the method, Various types of layers (PTLC, PTLA) are individually bonded to each other, and It can then be optionally coupled to the bipolar plate (BPP).

13. The method according to claim 8, 9, 10, 11 or 12, In this method, the shape and position of the layers (PTLC, BPP, PTLA) are checked after each bonding.

14. The method according to any one of the preceding claims, In the method, the joining is performed by sintering and / or welding.

15. The method according to claim 14, In the method, the welding is performed in a point-like, line-like, or meandering manner.

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