A fuel cell bipolar plate

Abstract

The application discloses a fuel cell bipolar plate, which comprises a stainless steel support frame, an anticorrosion layer I and a flow field plate I fixed on the stainless steel support frame in sequence; the stainless steel support frame is provided with grooves for mounting the anticorrosion layer and the flow field plate; and the anticorrosion layer is a flexible graphite anticorrosion layer. The fuel cell bipolar plate provided by the application has a greatly reduced volume compared with a fuel cell with a graphite bipolar plate, and the flexible graphite is used as the anticorrosion layer to isolate the contact between a membrane electrode and a stainless steel bottom plate. The voltage performance is stable and no corrosion occurs after 200 hours of continuous monitoring.

Description

Technical Field

[0001] This application relates to a bipolar plate for a fuel cell, belonging to the field of fuel cells. Background Technology

[0002] A fuel cell is a clean energy power generation device that directly converts chemical energy into electrical energy. The fuel cell stack is its core component, mainly composed of bipolar plates, membrane electrode assemblies (MEAs), and seals stacked in series. Depending on the power specifications, the number of fuel cell stacks ranges from approximately 70 to 200 cells. Each cell corresponds to two bipolar plates. The volume and weight of the bipolar plates directly affect the volume and weight of the fuel cell stack. Therefore, to achieve a high specific power stack, it is first necessary to reduce the volume and weight of the bipolar plates.

[0003] Currently, the most common bipolar plate material is graphite, which has high conductivity, stable acid and alkali resistance, and is easy to machine. However, due to its low mechanical strength, graphite bipolar plates are prone to breakage during fuel cell stack assembly and subsequent operation. Increasing their thickness is often used to avoid this. Therefore, to ensure fuel cell stack reliability, there is not much room for reducing the volume and weight of graphite bipolar plates. Alternatively, gold-plated stainless steel is used as the bipolar plate. Stainless steel has relatively high mechanical strength, allowing the bipolar plate thickness to be reduced to 0.1 mm. However, because the bipolar plate is in direct contact with the membrane electrode assembly (MEA), the acidic solution inside the MEA can corrode the stainless steel plate. Even with a gold plating layer, under high temperature and electrochemical reaction environments, the gold plating layer still cannot prevent the acid from corroding the stainless steel plate. Summary of the Invention

[0004] This invention addresses the issues of thinning and corrosion resistance of fuel cell stack plates by proposing an ultrathin composite material bipolar plate structure.

[0005] One aspect of this application provides a fuel cell bipolar plate. The fuel cell bipolar plate includes: a stainless steel support frame, and an anti-corrosion layer I and a flow field plate I sequentially fixed on the stainless steel support frame.

[0006] The stainless steel support frame is provided with a cavity adapted for installing the anti-corrosion layer I and the flow field plate I.

[0007] The anti-corrosion layer I is a flexible graphite anti-corrosion layer.

[0008] Stainless steel has high strength, and while ensuring the strength of the electrode plate, the thickness can be reduced to 0.1mm.

[0009] Optionally, the stainless steel support frame includes a stainless steel base plate I, a stainless steel interlayer I, and a stainless steel outer frame I that are bonded together in sequence.

[0010] The stainless steel interlayer I is provided with a cavity I for installing the anti-corrosion layer I and the flow field plate I;

[0011] The thickness H of the stainless steel interlayer I is the sum of the thickness h1 of the anti-corrosion layer I and the thickness h2 of the flow field plate.

[0012] Optionally, the thickness h1 of the anti-corrosion layer I is 0.05 to 0.1 mm.

[0013] The anti-corrosion layer serves to isolate the stainless steel electrode plate from the corrosion caused by acids in the membrane electrode.

[0014] Optionally, the stainless steel outer frame I is provided with a cavity II for installing the anti-corrosion layer I and the flow field plate;

[0015] Cavity I, cavity II, and the side of the stainless steel base plate I together form cavity I for installing the anti-corrosion layer I and the flow field plate I.

[0016] Optionally, the stainless steel base plate I, the stainless steel interlayer I, and the stainless steel outer frame I are all provided with main channel holes;

[0017] The main channel holes of the stainless steel interlayer I are provided with comb-shaped stainless steel strips.

[0018] At the main flow channel, the upper and lower stainless steel base plates and cover plates, together with the comb-shaped stainless steel strips in the middle, form a branch channel for distributing gas from the main flow channel to the interior of the flow field.

[0019] Optionally, the cavity I has a plurality of slots I for auxiliary positioning on its cavity wall;

[0020] The edge of the anti-corrosion layer is provided with multiple protrusions I for auxiliary positioning;

[0021] The groove I mates with the protrusion I;

[0022] The groove I is bonded to the protrusion I.

[0023] Optionally, the flow field plate I is a carbon fiber flow field plate.

[0024] The carbon fiber is selected from at least one of carbon paper and carbon cloth.

[0025] Carbon fiber material is loose and porous, and its flow pattern is not fixed. Its thickness can be arbitrarily adjusted according to the flow field thickness required by the membrane electrode.

[0026] Optionally, the stainless steel base plate further includes side II;

[0027] The fuel cell bipolar plate also includes a stainless steel sandwich layer II, a stainless steel outer frame II, an anti-corrosion layer II, and a flow field plate II;

[0028] The stainless steel interlayer II, stainless steel outer frame II, anti-corrosion layer II, and flow field plate II are structurally similar to the stainless steel interlayer I, stainless steel outer frame I, anti-corrosion layer I, and flow field plate I, and are installed on the side II.

[0029] The beneficial effects that this application can produce include:

[0030] The fuel cell bipolar plate provided in this application has a significantly reduced volume compared to fuel cells with graphite bipolar plates. Furthermore, it uses flexible graphite as a corrosion-resistant layer to isolate the membrane electrode assembly from the stainless steel base plate. After 200 hours of continuous monitoring, its voltage performance remained stable, and no corrosion was observed. Attached Figure Description

[0031] Figure 1 This is an exploded view of the bipolar plate of the fuel cell in Embodiment 1 of this application;

[0032] Figure 2 This is a schematic diagram of the bipolar plate of the fuel cell in Embodiment 1 of this application;

[0033] Figure 3 This is a schematic diagram of the stainless steel interlayer in Embodiment 1 of this application;

[0034] Figure 4 This is a schematic diagram of the flexible graphite anti-corrosion layer in Embodiment 1 of this application;

[0035] Figure 5 This is a schematic diagram of the carbon fiber flow field plate in Embodiment 1 of this application;

[0036] Figure 6 This is the voltage diagram for 200 hours in Test Example 1 of this application.

[0037] in:

[0038] 1. Stainless steel base plate; 2. Stainless steel sandwich layer; 3. Stainless steel outer frame; 4. Flexible graphite anti-corrosion layer; 5. Carbon fiber flow field A; 6. Carbon fiber flow field B; 7. Positioning groove; 8. Comb-shaped stainless steel strip. Detailed Implementation

[0039] The present application is described in detail below with reference to the embodiments, but the present application is not limited to these embodiments.

[0040] Unless otherwise specified, all raw materials used in the embodiments of this application were purchased through commercial channels.

[0041] Example 1

[0042] A fuel cell bipolar plate includes a stainless steel base plate 1, a stainless steel sandwich layer 2, a stainless steel outer frame 3, a flexible graphite anti-corrosion layer 4, and a flow field plate. The flow field plate is formed by stacking carbon fiber flow fields A5 and B6, with a combined thickness of 0.4 mm. Both carbon fiber flow fields A5 and B6 have protrusions II with positioning functions at their edges.

[0043] The flexible graphite anti-corrosion layer 4 has a thickness of 0.05 mm and has a protrusion I with positioning function on its edge;

[0044] The stainless steel interlayer 2 is provided with a cavity I for installing the flexible graphite anti-corrosion layer 4 and the flow field plate. The edge of the cavity I is provided with a positioning groove 7. The positioning groove 7 cooperates with the protrusion I and the protrusion II. The thickness of the stainless steel interlayer is 0.45mm. The main channel of the stainless steel interlayer 2 is provided with a comb-shaped stainless steel strip 8.

[0045] The thickness of both the stainless steel base plate 1 and the stainless steel outer frame 3 is 0.1mm.

[0046] Stainless steel base plate 1, stainless steel interlayer 2, and stainless steel outer frame 3 are bonded together with double-sided adhesive. Flexible graphite anti-corrosion layer 4 is bonded and fixed by the cooperation of protrusion I and positioning groove 7. Carbon fiber flow field A5 and carbon fiber flow field B6 are bonded and fixed to the stainless steel interlayer 2 on which flexible graphite anti-corrosion layer 4 is installed by the cooperation of protrusion II and positioning groove 7.

[0047] The thickness of the fuel cell bipolar plate in this embodiment is 0.65 mm.

[0048] Example 2

[0049] On the other side of the fuel cell bipolar plate prepared in Example 1, the same stainless steel interlayer 2, stainless steel outer frame 3, flexible graphite anti-corrosion layer 4, carbon fiber flow field A5, and carbon fiber flow field B6 as in Example 1 were selected; the same assembly method as in Example 1 was used to assemble the bipolar plate to obtain a bipolar plate with a total thickness of 1.2 mm.

[0050] Test Example 1

[0051] Using the fuel cell bipolar plate prepared in Example 1, two fuel cell stacks were assembled and operated for 200 hours at a pure hydrogen to air ratio of 1.2 and 2.0, and a temperature of 160 degrees Celsius. The voltage of the fuel cell stack was monitored, and the test results are as follows: Figure 6 As shown, the voltage of both battery cells remained stable during the 200-hour operation, indicating that the stainless steel base plate did not show any corrosion. In the figure, #1 and #2 are the first and second cells of the two battery stacks, with the horizontal axis representing time (200 hours) and the vertical axis representing voltage.

[0052] The above description is merely a few embodiments of this application and is not intended to limit this application in any way. Although this application discloses preferred embodiments as described above, it is not intended to limit this application. Any changes or modifications made by those skilled in the art without departing from the scope of the technical solution of this application using the disclosed technical content are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

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