Fuel cell stack

Abstract

The invention discloses a fuel cell stack. The fuel cell stack comprises a plurality of stacked fuel cell units, each fuel cell unit comprises a cathode plate, an anode plate and a membrane electrode assembly clamped between the cathode plate and the anode plate, the membrane electrode assembly comprises a proton exchange membrane and an insulation frame arranged on the outer side of the proton exchange membrane, and the insulation frame is arranged between the cathode plate and the anode plate. The insulating frame protrudes out of the side edge of at least one of the cathode plate and the anode plate so as to increase the creepage distance between the cathode plate and the anode plate. According to the fuel cell stack provided by the invention, the creepage distance between the cathode plate and the anode plate is increased, and the insulating property of the fuel cell stack is improved. And moreover, the cost is low, the preparation is simple, newly added parts are not needed, the dependence on a relatively complicated technological process is avoided, and large-scale batch production is easy to realize.

Description

Technical Field

[0001] The present invention relates to the technical field of fuel cell stacks, and in particular to a fuel cell stack with better insulation performance. Background Art

[0002] A fuel cell is a device that uses chemical reactions to generate electricity. Its energy utilization method has the advantages of high efficiency, low pollution, and the use of renewable energy as raw materials. It is regarded as a promising energy utilization method. As an efficient and clean power conversion device, fuel cells are currently widely used in a variety of scenarios. The core component of a fuel cell is a fuel cell stack, which is composed of stacked fuel cell units. The fuel cell unit is composed of a bipolar plate and a membrane electrode assembly.

[0003] Because fuel cell stacks usually have a higher operating voltage, it is usually necessary to consider additional insulation isolation structure design during application. Prior art, such as invention patent applications with publication numbers CN114824353A and CN115377475A, all provide a solution that uses a structure with plastic coating on the edge of the electrode plate to achieve electrical isolation between the electrode plate and the external environment. Although the solution in the prior art can effectively improve the insulation performance of the fuel cell unit, its structure and preparation are complex, and additional components and processes need to be added, resulting in high production costs; in addition, the above-mentioned edge plastic coating solution also does not take into account the effects of factors such as misalignment caused by manufacturing errors of the electrode plate itself, cumulative bonding and assembly tolerances, etc. on the insulation performance. For the actual application of the product, there is still a lot of room for improvement.

[0004] Based on this, it is necessary to propose a technical solution to overcome the shortcomings of the existing technology. Summary of the invention

[0005] In order to overcome the defects of the prior art, the present invention proposes a fuel cell stack, which can improve the insulation performance of the fuel cell stack, and the insulation performance is achieved by relying on the structure of the fuel plate and the membrane electrode assembly itself, without the need for new components.

[0006] The present invention is implemented through the following technical scheme: a fuel cell stack, comprising a plurality of stacked fuel cell units, wherein the fuel cell units include a cathode plate, an anode plate, and a membrane electrode assembly sandwiched between the cathode plate and the anode plate, wherein the membrane electrode assembly includes a proton exchange membrane and an insulating frame arranged on the outside of the proton exchange membrane, and the insulating frame protrudes beyond the side edge of at least one of the cathode plate and the anode plate to increase the creepage distance between the cathode plate and the anode plate.

[0007] As a further improved technical solution, the insulating frame of each fuel cell unit protrudes beyond the side edges of the cathode plate and the anode plate, and the insulating frames of multiple stacked fuel cell units are in a fin-like structure with spacing arranged at the side edges of the fuel cell stack.

[0008] As a further improved technical solution, an impurity accommodating cavity is formed between two adjacent insulating frames.

[0009] As a further improved technical solution, a gap communicating with the impurity receiving cavity is formed between the portion of the insulating frame sandwiched between the cathode plate and the anode plate and the cathode plate or the anode plate.

[0010] As a further improved technical solution, a sealant is provided between the cathode plate, the anode plate and the insulating frame, and the inner end of the gap is blocked by the sealant.

[0011] As a further improved technical solution, the cathode plate and the anode plate between two adjacent insulating frames are fixedly connected to form a bipolar plate, and the side edge of the bipolar plate has a positioning area, in which: A groove is provided at the side edge of at least one of the cathode plate and the anode plate of the bipolar plate; The side edges of the cathode plate and the anode plate of the bipolar plate are arranged non-flushly; and The side edges of the two cathode plates of the two adjacent bipolar plates are flush with each other, and / or the side edges of the two anode plates are flush with each other.

[0012] As a further improved technical solution, at the positioning area, the insulating frame is flush with the side edge of the longer one of the cathode plate and the anode plate.

[0013] As a further improved technical solution, at the positioning area, there is a spacing of 0.8-1 mm between the side edges of the cathode plate and the anode plate of the bipolar plate.

[0014] As a further improved technical solution, at the positioning area, the side edges of the cathode plate and the anode plate of the bipolar plate are both provided with grooves, and the grooves on the cathode plate and the anode plate are staggered.

[0015] As a further improved technical solution, in the length direction of the groove, the groove on the cathode plate and the groove on the anode plate have an overlapping area of ​​1-2 mm.

[0016] The fuel cell stack provided by the present invention increases the creepage distance between the cathode plate and the anode plate by setting the insulating frame of the membrane electrode assembly to protrude beyond the side edge of at least one of the cathode plate and the anode plate, thereby increasing the creepage distance at least by the distance extended by the insulating frame, thereby improving the insulation performance of the fuel cell stack. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic cross-sectional view of a battery unit of a fuel cell stack of the present invention.

[0018] Figure 2 It is a cross-sectional schematic diagram of a stack of several battery units of a fuel cell stack of the present invention.

[0019] Figure 3 It is a partial view of the positioning area at the edge of the fuel cell stack of the present invention.

[0020] Figure 4 It is a cross-sectional schematic diagram of the positioning area at the edge of the fuel cell stack of the present invention.

[0021] The reference numerals are as follows: 1, cathode plate; 11, cathode plate side edge; 2, anode plate; 21, anode plate side edge; 3, insulating frame; 10, bipolar plate; 101, impurity containing cavity; 102, gap; 103, groove. DETAILED DESCRIPTION

[0022] In order to have a clearer understanding of the technical features, purposes and effects of the present invention, specific embodiments of the present invention are now described in detail with reference to the accompanying drawings.

[0023] The technical solutions in the embodiments of the present invention are clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0024] See also Figures 1 to 4As shown, the present invention provides a fuel cell stack. The fuel cell stack includes a plurality of stacked fuel cell units. The fuel cell unit includes a cathode plate 1, an anode plate 2, and a membrane electrode assembly sandwiched between the cathode plate 1 and the anode plate 2. The membrane electrode assembly includes a proton exchange membrane and an insulating frame 3 arranged on the outside of the proton exchange membrane. The insulating frame 3 protrudes beyond the side edge of at least one of the cathode plate 1 and the anode plate 2 to increase the creepage distance between the cathode plate 1 and the anode plate 2. It can be understood that in addition to the insulating frame 3 and the proton exchange membrane coated with a catalyst, the membrane electrode assembly also includes carbon paper stacked on both sides to enhance the diffusion of the reaction medium.

[0025] The fuel cell stack provided by the present invention increases the creepage distance between the cathode plate 1 and the anode plate 2 by setting the insulating frame 3 of the membrane electrode assembly to protrude beyond the side edge of at least one of the cathode plate 1 and the anode plate 2, thereby increasing the creepage distance by at least the distance extended by the insulating frame 3 and improving the insulation performance of the fuel cell stack.

[0026] See also Figure 1 As shown, in this embodiment, the cathode plate side edge 11 of the cathode plate 1 and the anode plate side edge 12 of the anode plate 2 are flush. The insulating frame 3 protrudes beyond the cathode plate side edge 11 and the anode plate side edge 12. Assuming that the dimension of the insulating frame 3 protruding beyond the side edge of the cathode and anode plates is L0, and the thickness of the insulating frame 3 is T0, the creepage distance L=2*L0+T0; while for the existing structure in which the insulating frame 3 does not protrude, the creepage distance is only the thickness T0 of the insulating frame 3. By comparison, it can be seen that the scheme of the present invention greatly increases the creepage distance of the cathode and anode plates. In other embodiments, the cathode plate side edge 11 and the anode plate side edge 12 may not be flush, and the insulating frame 3 may only protrude beyond the cathode plate side edge 11 or the anode plate side edge 12, so that the creepage distance is also increased by at least the distance T0 that the insulating frame 3 extends and protrudes.

[0027] See also Figure 2 As shown, multiple Figure 1 The fuel cell units shown are stacked together to form Figure 2The fuel cell stack shown. The fuel cell stack is usually operated in a sealed housing with a certain degree of protection, but in extreme cases, it is still necessary to consider the influence of impurities in the operating environment of the fuel cell stack, such as trace amounts of metal conductive particles, condensed liquid water droplets, etc. on the insulation performance of the fuel cell stack. In this embodiment, the insulating frame 3 of each of the fuel cell units protrudes beyond the side edges of the cathode plate 1 and the anode plate 2, and the insulating frames 3 of the multiple stacked fuel cell units are arranged at the side edges of the fuel cell stack. The spacing between adjacent insulating frames 3 is roughly the thickness of the two plates located therein, and the thickness of each plate is usually a few millimeters to a few millimeters, so that the spacing between the adjacent insulating frames 3 is also in the range of a few millimeters to a few millimeters. Therefore, the protruding parts of the multiple insulating frames 3 look like densely arranged fins as a whole, which can block larger conductive particles and impurities, making it difficult to adhere to the charged cathode plate 1 and anode plate 2, which is conducive to avoiding the risk of short circuit caused by the accumulation of large-sized conductive particles and impurities on the cathode and anode plates.

[0028] As for impurities such as conductive particles with smaller sizes, they can enter the impurity accommodation chamber 101 formed between two adjacent insulating frames 3. However, due to the obstruction of the protruding parts of the two insulating frames 3, the conductive particles with smaller sizes are blocked on one side of the insulating frame 3, and will not contact the electrode plate on the other side of the insulating frame 3, which is also conducive to avoiding the short circuit between the cathode and anode plates of the fuel cell unit. At the same time, when condensed droplets appear in the operating environment of the fuel cell stack, the droplets flow into the impurity accommodation chamber 101 and can be discharged from the fuel cell stack by further arranged inclined surfaces, gaps, etc. In this embodiment, a gap 102 connected to the impurity accommodation chamber 101 is formed between the part of the insulating frame 3 sandwiched between the cathode plate 1 and the anode plate 2 and the cathode plate 1 or the anode plate 2. There is a seal between the cathode plate 1, the anode plate 2 and the insulating frame 3, and the inner end of the gap 102 is blocked by the seal. The liquid flowing into the impurity accommodation chamber 101 can flow through the gap 102 and flow out of the fuel cell stack to both sides and the edge after being blocked by the seal.

[0029] The cathode and anode plates constituting the fuel cell unit are usually made by mold pressing, and the membrane electrode assembly is made by hot pressing and bonding of multi-layer membrane components. There are usually certain deformations and manufacturing tolerances in the process of preparing the electrode plates and membrane electrode assemblies. In the process of stacking the fuel cell units into a fuel cell stack, in order to ensure the consistency of the performance of the fuel cell units and avoid sealing failure and performance degradation caused by misalignment, it is usually necessary to rely on external positioning to limit their positions to ensure stacking accuracy. The prior art usually uses external positioning rods to perform external positioning of each component. In some embodiments of the present invention, since the insulating frame 3 protrudes from the side edges of the cathode and anode plates, the external positioning rod cannot contact and position the cathode and anode plates. To this end, the present invention further sets a positioning area on the side edges of the cathode and anode plates.

[0030] See also Figures 2 to 4 As shown, in this embodiment, the cathode plate 1 and the anode plate 2 between two adjacent insulating frames 3 are fixedly connected to form a bipolar plate 10. That is, the cathode plate 1 and the anode plate 2 included in a bipolar plate 10 belong to the plates of two adjacent fuel cell units, rather than the cathode plate 1 and the anode plate 2 of the same fuel cell unit. In this embodiment, the side edge of the bipolar plate 10 has a positioning area. The positioning area includes the following design: in the positioning area, at least one of the side edges of the cathode plate 1 and the anode plate 2 of the bipolar plate 10 is provided with a groove 103, the side edges of the cathode plate 1 and the anode plate 2 of the bipolar plate 10 are non-flush, and the side edges of the two cathode plates 1 in the two adjacent bipolar plates 10 are flush, and / or the side edges of the two anode plates 2 are flush. In this way, the external positioning rod can be positioned with the two cathode plates or two anode plates of the two adjacent fuel cell units, rather than being positioned with the help of the cathode plate and the anode plate of the same fuel cell unit. While achieving the positioning requirements, sufficient creepage distance can also be guaranteed in the positioning area.

[0031] In this embodiment, at the positioning area, the insulating frame 3 is flush with the side edge of the longer one of the cathode plate 1 and the anode plate 2. In this way, the creepage distance between the cathode plate 1 and the anode plate 2 is at least the sum of the thickness of the insulating frame 3 and the distance that the insulating frame 3 protrudes from the side edge of the shorter plate. Figure 3As shown, in the present embodiment, at the positioning area, there is a spacing of 0.8-1mm between the side edges of the cathode plate 1 and the anode plate 2 of the bipolar plate 10. That is, the groove depth of the groove 103 is 0.8-1mm; since the insulating frame 3 is flush with the edge of the plate where the groove 103 is not formed, the distance that the insulating frame 3 protrudes from the groove 103 is 0.8-1mm. Furthermore, at the positioning area, the side edges of the cathode plate 1 and the anode plate 2 of the bipolar plate 10 are both provided with grooves 103, and the grooves 103 on the cathode plate 1 and the anode plate 2 are staggered. In the length direction of the groove 103, the groove 103 on the cathode plate 1 and the groove 103 on the anode plate 2 have an overlapping area of ​​1-2mm, as shown in FIG. Figure 3 As shown in the mark d.

[0032] The present application provides grooves 103 with the same depth dimension on the cathode and anode plates in the positioning area, and arranges the grooves 103 on the cathode and anode plates in a staggered arrangement, so as to ensure that there is sufficient creepage clearance and insulation performance when the cathode and anode plates of the fuel cell stack are bonded and stacked in a misaligned manner. During the fuel cell stacking process, the anode plate side edge 21 corresponding to the cathode plate groove in the bipolar plate 10, the cathode plate side edge 11 corresponding to the anode plate groove in the adjacent bipolar plate 10, and the bottom edge of the membrane electrode groove are respectively aligned with the edge of the external positioning rod to position the various components of the fuel cell unit and each fuel cell unit.

[0033] Through the above description of the specific embodiments, it can be known that the fuel cell stack provided by the present invention, by setting the insulating frame 3 of the membrane electrode assembly to protrude beyond the side edge of at least one of the cathode plate 1 and the anode plate 2, the creepage distance is at least increased by the distance extended by the insulating frame 3, the creepage distance between the cathode plate 1 and the anode plate 2 is increased, and the insulation performance of the fuel cell stack is improved. Moreover, the structure of the protruding insulating frame 3 can effectively block or accommodate the conductive particulate impurities in the operating environment of the fuel cell stack, and improve the operating stability and safety of the fuel cell in a low cleanliness environment. The positioning area further set at the edge of the fuel cell unit of the present invention can meet the positioning requirements of the fuel cell stack while ensuring the insulation performance of the positioning area. Compared with other edge hemming insulation solutions, the technical solution provided by the present invention is low in cost, simple to prepare, does not require new parts, does not rely on more complex process steps, is easy to mass produce, and can reduce production costs.

[0034] The present invention is described by several specific embodiments, and it should be understood by those skilled in the art that various changes and equivalent substitutions may be made to the present invention without departing from the scope of the present invention. In addition, various modifications may be made to the present invention for specific situations or specific circumstances without departing from the scope of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed, but should include all implementation methods falling within the scope of the claims of the present invention.

Claims

1. A fuel cell stack, comprising a plurality of stacked fuel cell units, wherein the fuel cell units comprise a cathode plate, an anode plate, and a membrane electrode assembly sandwiched between the cathode plate and the anode plate, wherein: The membrane electrode assembly includes a proton exchange membrane and an insulating frame arranged outside the proton exchange membrane, and the insulating frame protrudes beyond the side edge of at least one of the cathode plate and the anode plate to increase the creepage distance between the cathode plate and the anode plate.

2. The fuel cell stack according to claim 1, wherein: The insulating frame of each fuel cell unit protrudes beyond the side edges of the cathode plate and the anode plate, and the insulating frames of the plurality of stacked fuel cell units are in a fin-like structure with spacing arranged at the side edges of the fuel cell stack.

3. The fuel cell stack according to claim 1 or 2, characterized in that: An impurity accommodating cavity is formed between two adjacent insulating frames.

4. The fuel cell stack according to claim 3, characterized in that: A gap communicating with the impurity receiving chamber is formed between the portion of the insulating frame sandwiched between the cathode plate and the anode plate and the cathode plate or the anode plate.

5. The fuel cell stack according to claim 4, characterized in that: A seal is provided between the cathode plate, the anode plate and the insulating frame, and the inner end of the gap is blocked by the seal.

6. The fuel cell stack according to claim 1 or 2, characterized in that: The cathode plate and the anode plate between two adjacent insulating frames are fixedly connected to form a bipolar plate, and the side edge of the bipolar plate has a positioning area, in which: A groove is provided at the side edge of at least one of the cathode plate and the anode plate of the bipolar plate; The side edges of the cathode plate and the anode plate of the bipolar plate are arranged non-flushly; and The side edges of the two cathode plates of the two adjacent bipolar plates are flush with each other, and / or the side edges of the two anode plates are flush with each other.

7. The fuel cell stack according to claim 6, characterized in that: At the positioning area, the insulating frame is flush with a side edge of the longer one of the cathode plate and the anode plate.

8. The fuel cell stack according to claim 6, characterized in that: At the positioning area, a gap of 0.8-1 mm is provided between side edges of the cathode plate and the anode plate of the bipolar plate.

9. The fuel cell stack according to claim 6, wherein: At the positioning area, grooves are arranged on the side edges of the cathode plate and the anode plate of the bipolar plate, and the grooves on the cathode plate and the anode plate are arranged in a staggered manner.

10. The fuel cell stack according to claim 9, characterized in that: In the length direction of the groove, the groove on the cathode plate and the groove on the anode plate have an overlapping area of ​​1-2 mm.

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