A fuel cell flow field plate, a fuel cell single cell

Abstract

The present application provides a fuel cell flow field plate and a fuel cell single cell. The fuel cell flow field plate includes a parallel flow field, and the parallel flow field includes at least two longitudinal units distributed transversely along the parallel flow field. Each longitudinal unit includes at least one flow channel, and each longitudinal unit is provided with a plurality of labyrinthine resistance zones arranged at longitudinal intervals along the parallel flow field. The labyrinthine resistance zone includes a labyrinthine channel formed by alternately arranged protrusions on opposite two flow channel walls; the labyrinthine resistance zones provided in one of any two adjacent longitudinal units and the labyrinthine resistance zones provided in the other are alternately arranged longitudinally in the parallel flow field. The fuel cell flow field plate provided by the present application effectively avoids the problem of too large a difference in the reactant concentration between the catalytic layer under the ridge and the catalytic layer under the flow channel existing in the traditional parallel flow field, and improves the distribution uniformity of the reactants in the catalytic layer.

Description

Technical Field

[0001] The present application relates to the technical field of fuel cells, and in particular to a fuel cell flow field plate and a fuel cell single cell. Background Art

[0002] A fuel cell stack is formed by repeatedly stacking membrane electrodes and flow field plates. The catalytic layer in the membrane electrode is the place where the electrochemical reaction occurs. The flow field plate is responsible for transporting reactants to the membrane electrode, discharging the reaction products in the membrane electrode, and conducting the current and heat generated by the reaction. By designing a suitable flow field plate structure to improve the concentration and distribution uniformity of reactants in the catalytic layer can effectively reduce the concentration polarization of the fuel cell, which is an important means to improve the power generation performance of the fuel cell.

[0003] For a traditional parallel flow field, reactants are mainly transported from the flow channel to the catalytic layer in the form of molecular diffusion. Due to the existence of ridges, the distance from the flow channel to the catalytic layer under the ridge is greater than the distance from the flow channel to the catalytic layer under the flow channel, resulting in a lower reactant concentration in the catalytic layer under the ridge than that in the catalytic layer under the flow channel. In addition, the liquid water generated by the reaction needs to be discharged to the flow channel through the gas diffusion layer. Since the distance from the flow channel to the gas diffusion layer under the ridge is greater than the distance from the flow channel to the gas diffusion layer under the flow channel, the liquid water is more likely to accumulate in the gas diffusion layer under the ridge, and the resistance formed by the liquid water to the reactant diffusion further exacerbates the difference in reactant concentration between the catalytic layer under the ridge and the catalytic layer under the flow channel. The lower reactant concentration in the catalytic layer under the ridge generates a higher concentration polarization, and it is urgent to improve the transport efficiency of reactants from the flow channel to the catalytic layer under the ridge through a suitable flow field plate design. Summary of the Invention

[0004] In view of this, the present application provides a fuel cell flow field plate and a fuel cell single cell. The fuel cell flow field plate effectively avoids the problem of excessive difference in reactant concentration between the catalytic layer under the ridge and the catalytic layer under the flow channel existing in the traditional parallel flow field, and improves the distribution uniformity of reactants in the catalytic layer.

[0005] In order to achieve the above object, the present application provides the following technical solutions:

[0006] A fuel cell flow field plate includes a parallel flow field. The parallel flow field includes at least two longitudinal units distributed along the transverse direction of the parallel flow field. Each longitudinal unit includes at least one flow channel. Each longitudinal unit is provided with a plurality of labyrinth resistance zones spaced longitudinally along the parallel flow field. The labyrinth resistance zone includes a labyrinth channel formed by alternately arranged protrusions on opposite two flow channel wall surfaces; the labyrinth resistance zones provided in one of any two adjacent longitudinal units are alternately arranged longitudinally with the labyrinth resistance zones provided in the other.

[0007] Optionally, in the above fuel cell flow field plate, the labyrinth resistance zones provided in one of the two longitudinal units adjacent to any one of the longitudinal units are arranged opposite to the labyrinth resistance zones provided in the other longitudinal unit in the transverse direction of the parallel flow field.

[0008] Optionally, in the above fuel cell flow field plate, when the labyrinth resistance zones are alternately arranged in the longitudinal direction of the parallel flow field for any two adjacent longitudinal units, the alternating pitch is not less than 5 mm and not more than 120 mm.

[0009] Optionally, in the above fuel cell flow field plate, the projection shape of the protrusion in the direction perpendicular to the largest plane of the fuel cell flow field plate is rectangular, trapezoidal or semi-circular.

[0010] Optionally, in the above fuel cell flow field plate, when the labyrinth resistance zones are alternately arranged in the longitudinal direction of the parallel flow field for any two adjacent longitudinal units, the alternating pitch decreases successively along the flow direction of the flow channel.

[0011] Optionally, in the above fuel cell flow field plate, the flow channel form of the parallel flow field is a parallel straight flow channel or a parallel meandering flow channel.

[0012] Optionally, in the above fuel cell flow field plate, the alternating pitch of the protrusions is not less than 1.2 times the width of the protrusions in the flow direction of the flow channel, and the width of the protrusions in the flow direction of the flow channel is not less than 0.2 mm.

[0013] Optionally, in the above fuel cell flow field plate, the width of the protrusions in the direction perpendicular to the flow direction of the flow channel is not less than half of the width of the flow channel.

[0014] Optionally, in the above fuel cell flow field plate, the parallel flow field is located in the middle of the fuel cell flow field plate, and the fuel cell flow field plate further includes dot-shaped flow fields located at both ends of the parallel flow field.

[0015] A fuel cell single cell includes the fuel cell flow field plate disclosed in any one of the above.

[0016] According to the above technical solution, in the fuel cell flow field plate provided by the present application, the longitudinal unit includes at least one flow channel, and there are at least two longitudinal units distributed transversely along the parallel flow field. Each longitudinal unit is provided with a plurality of labyrinth resistance zones arranged longitudinally at intervals along the parallel flow field. When the gas flows through the labyrinth resistance zone, the air flow collides with the protrusions and changes the flow direction multiple times under the constraint of the protrusions, generating local resistance loss. Since the labyrinth resistance zones of two adjacent longitudinal units are arranged alternately longitudinally in the parallel flow field, the pressure drop gradients of two adjacent longitudinal units from the inlet side to the outlet side are different. Therefore, there is a pressure difference between two adjacent longitudinal units transversely in the parallel flow field. The pressure difference forces the gas to pass through the gas diffusion layer under the ridge from the high-pressure longitudinal unit to the low-pressure longitudinal unit, thus avoiding the problem of too large difference in the reactant concentration between the catalyst layer under the ridge and the catalyst layer under the flow channel in the traditional parallel flow field, and improving the distribution uniformity of the reactants in the catalyst layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only the embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained according to the provided drawings.

[0018] Figure 1 is a cross-sectional schematic diagram of a fuel cell single cell provided by an embodiment of the present application;

[0019] Figure 2 is a structural schematic diagram of a fuel cell flow field plate provided in Embodiment 1 of the present application;

[0020] Figure 3 is Figure 2 a structural schematic diagram of the parallel flow field of the fuel cell flow field plate shown;

[0021] Figure 4 is Figure 3 a curve graph of the pressure of two adjacent flow channels changing with the flow in;

[0022] Figure 5 is a structural schematic diagram of the parallel flow field of a fuel cell flow field plate provided in Embodiment 2 of the present application;

[0023] Figure 6 is a structural schematic diagram of the parallel flow field of a fuel cell flow field plate provided in Embodiment 3 of the present application;

[0024] Figure 7 is a structural schematic diagram of the parallel flow field of a fuel cell flow field plate provided in Embodiment 4 of the present application.

[0025] The labels in the figure are as follows:

[0026] 1a, anode flow field plate; 1c, cathode flow field plate; 2, rib; 3, flow channel; 4, gas diffusion layer; 5, catalyst layer; 6, proton exchange membrane;

[0027] 52, catalyst layer under rib; 53, catalyst layer under flow channel;

[0028] P, parallel flow field; D, dot flow field;

[0029] Q, labyrinth resistance area; L, alternate spacing of resistance areas; W1, first width; W2, second width; W3, flow channel width; 7, protrusion; J, alternate spacing of protrusions;

[0030] L1, first alternate spacing; L2, second alternate spacing; L3, third alternate spacing. Detailed implementation manners

[0031] Next, the technical solutions in the embodiments of the present application will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present application.

[0032] As Figure 1 shown, the fuel cell single cell provided by the embodiment of the present application includes an anode flow field plate 1a, a cathode flow field plate 1c, and a proton exchange membrane 6. A gas diffusion layer 4 and a catalyst layer 5 are provided between the anode flow field plate 1a and the proton exchange membrane 6, and between the cathode flow field plate 1c and the proton exchange membrane 6. The catalyst layer 52 under the rib refers to the part of the catalyst layer 5 corresponding to the rib 2 of the flow field plate, and the catalyst layer 53 under the flow channel refers to the part of the catalyst layer 5 corresponding to the flow channel 3 of the flow field plate.

[0033] The fuel cell flow field plate provided by this application includes a parallel flow field. The parallel flow field includes at least two longitudinal units distributed transversely along the parallel flow field. Each longitudinal unit includes at least one flow channel 3, and each longitudinal unit is provided with a plurality of labyrinth resistance zones arranged at longitudinal intervals along the parallel flow field. The longitudinal direction of the parallel flow field refers to the length direction of the parallel flow field, which can be understood as the direction from the flow channel inlet side to the flow channel outlet side. The transverse direction of the parallel flow field refers to the width direction of the parallel flow field, that is, the direction perpendicular to the longitudinal direction of the parallel flow field. The labyrinth resistance zone includes a labyrinth channel formed by alternately arranged protrusions on two opposite flow channel walls. That is, these two flow channel walls are opposite in the width direction of the flow channel 3, but the protrusions on these two flow channel walls are not opposite in the width direction of the flow channel 3, but are arranged in a staggered manner. The labyrinth resistance zones provided in one of any two adjacent longitudinal units and the labyrinth resistance zones provided in the other are alternately arranged longitudinally in the parallel flow field. That is, the labyrinth resistance zones of two adjacent longitudinal units are not opposite in the width direction of the parallel flow field, but are arranged in a staggered manner.

[0034] Embodiment 1

[0035] As Figure 2 and Figure 3 shown, this application can make the flow channel form of the parallel flow field P be a parallel straight flow channel. Figure 3 The direction of the X-axis in [figure] is the longitudinal direction of the parallel flow field P, and the direction of the Y-axis is the transverse direction of the parallel flow field P. A plurality of labyrinth resistance zones Q are arranged in each flow channel. That is, in this embodiment, the number of flow channels included in one longitudinal unit is one.

[0036] When the gas flows through the labyrinth resistance zone Q, the air flow collides with the protrusion 7 and changes the flow direction multiple times under the constraint of the protrusion 7, generating local resistance loss. Since the labyrinth resistance zones Q of two adjacent flow channels are not opposite in the transverse direction of the parallel flow field P, that is, there is an offset in the longitudinal direction of the parallel flow field P, the pressure drop gradients of two adjacent flow channels from the inlet to the outlet are different. As Figure 4 shown, the pressure at the center of flow channel one and flow channel two changes alternately along the X-axis direction. Therefore, there is a pressure difference between two adjacent flow channels in the direction perpendicular to the flow channel. The pressure difference forces the gas to pass through the gas diffusion layer under the ridge from the high-pressure flow channel to the low-pressure flow channel, thus avoiding the problem of too large a difference in the reactant concentration between the catalytic layer under the ridge and the catalytic layer under the flow channel in the traditional parallel flow field and improving the distribution uniformity of the reactants in the catalytic layer.

[0037] In a preferred embodiment, the present application makes the alternating spacing of any two adjacent longitudinal units when arranging the labyrinth resistance zones Q alternately in the longitudinal direction of the parallel flow field P not less than 5 mm and not more than 120 mm, that is, the size of the resistance zone alternating spacing L is preferably 5 mm to 120 mm. The projection shape of the protrusion 7 in the direction perpendicular to the largest plane of the fuel cell flow field plate can be rectangular, trapezoidal or semi-circular. Figure 3 Taking the rectangular protrusion 7 as an example for illustration. In a preferred embodiment, the present application makes the alternating spacing of the protrusions 7 (i.e., the protrusion alternating spacing J) not less than 1.2 times the width of the protrusion 7 in the flow direction of the flow channel (i.e., the first width W1). Further preferably, the width of the protrusion 7 in the flow direction of the flow channel (i.e., the first width W1) is not less than 0.2 mm. The width of the protrusion 7 in the direction perpendicular to the flow direction of the flow channel (i.e., the second width W2) can be set according to the distance between the two opposite flow channel walls described above. The second width W2 is generally not less than half of the distance between the two flow channel walls. For example, in Embodiment 1, the distance between the two flow channel walls of the labyrinth resistance zone Q is the flow channel width W3, so the second width W2 is not less than half of the flow channel width W3.

[0038] Specifically, the present application can make the fuel cell flow field plate adopt a combined flow field structure form, such as Figure 2 shown, the parallel flow field P is located in the middle of the fuel cell flow field plate, and the fuel cell flow field plate further includes dot-shaped flow fields D located at both ends of the parallel flow field P.

[0039] Embodiment 2

[0040] As Figure 5 shown, different from that each longitudinal unit in Embodiment 1 includes one flow channel, in Embodiment 2, one longitudinal unit includes two flow channels. This is mainly considered that when the flow channel width W3 is relatively small, setting the labyrinth resistance zone Q in a single flow channel will face the problem of large processing difficulty, increasing the manufacturing cost of the flow field plate. In addition, the number of flow channels included in one longitudinal unit can also be other values such as three or four. It is easy to understand that when the number of flow channels included in one longitudinal unit is more than two, the ridges between these flow channels are discontinuous to form the aforementioned labyrinth resistance zone Q at the discontinuous places. The two flow channel walls where the protrusions 7 are set respectively belong to the outermost two flow channels, that is, the aforementioned two opposite flow channel walls belong to different flow channels, and these two flow channel walls are opposite in the width direction of the flow channel due to the discontinuous structure of the ridges. It should be noted that within the same parallel flow field P, the number of flow channels included in different longitudinal units can be different, and the present application does not limit this. For example, one longitudinal unit includes two flow channels, and another longitudinal unit includes three flow channels.

[0041] Embodiment 3

[0042] As Figure 6 shown, different from the parallel straight flow channel in the first embodiment, in the third embodiment, the flow channel of the parallel flow field P is a parallel meandering flow channel. In addition, the meandering shape of the flow channel can be a wavy shape as Figure 6 shown, or other shapes. For example, the periodically repeated unit shape of the flow channel is a zigzag or a triangle.

[0043] Embodiment Four

[0044] As Figure 7 shown, in this embodiment, when the labyrinth resistance zones Q are arranged alternately in the longitudinal direction of the parallel flow field P for any two adjacent longitudinal units, the alternating spacing decreases successively along the flow direction of the flow channel. Taking the two lowermost flow channels in Figure 7 as an example, the magnitude relationship of the first alternating spacing L1, the second alternating spacing L2, and the third alternating spacing L3 is: L1 > L2 > L3. On this basis, the present application preferably makes the labyrinth resistance zones Q arranged by one of the two longitudinal units adjacent to any longitudinal unit be arranged directly opposite to the labyrinth resistance zones Q arranged by the other in the transverse direction of the parallel flow field P. In this way, the labyrinth resistance zones Q can be arranged in rows in the transverse direction of the parallel flow field P, as Figure 7 shown. The setting of the labyrinth resistance zones Q can produce the effect of enhancing mass transfer, but inevitably brings additional pressure loss. Gradually decreasing the resistance zone alternating spacing L along the flow direction of the flow channel can better balance the pressure loss and the mass transfer efficiency, and finally obtain a better comprehensive effect.

[0045] The present application also provides a fuel cell single cell, which includes the fuel cell flow field plate disclosed in the above embodiments. Since the fuel cell flow field plate disclosed in the above embodiments has the above technical effects, the fuel cell single cell having the fuel cell flow field plate also has the above technical effects, which will not be elaborated herein again.

[0046] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present application. Various modifications to the embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A fuel cell flow field plate, including a parallel flow field, characterized in that, The parallel flow field includes at least two longitudinal units distributed transversely along the parallel flow field. Each longitudinal unit includes at least one flow channel, and each longitudinal unit is provided with a plurality of labyrinthine resistance zones arranged at longitudinal intervals along the parallel flow field. The labyrinthine resistance zone includes a labyrinthine channel formed by protrusions alternately arranged on opposite two flow channel walls; the labyrinthine resistance zones arranged in one of any two adjacent longitudinal units are alternately arranged longitudinally with the labyrinthine resistance zones arranged in the other longitudinal unit in the parallel flow field. When any two adjacent longitudinal units alternately arrange the labyrinthine resistance zones longitudinally in the parallel flow field, the alternating spacing decreases successively along the flow direction of the flow channel. The alternating spacing of the protrusions is not less than 1.2 times the width of the protrusions in the flow direction of the flow channel, and the width of the protrusions in the flow direction of the flow channel is not less than 0.2 mm. The width of the protrusions in the direction perpendicular to the flow direction of the flow channel is not less than half of the width of the flow channel. The labyrinthine resistance zones arranged in one of the two longitudinal units adjacent to any longitudinal unit are arranged opposite to each other transversely along the parallel flow field with the labyrinthine resistance zones arranged in the other longitudinal unit.

2. The fuel cell flow field plate according to claim 1, wherein When any two adjacent longitudinal units alternately arrange the labyrinthine resistance zones longitudinally in the parallel flow field, the alternating spacing is not less than 5 mm and not greater than 120 mm.

3. The fuel cell flow field plate according to claim 1, characterized in that, The projection shape of the protrusions in the direction perpendicular to the largest plane of the fuel cell flow field plate is rectangular, trapezoidal or semi-circular.

4. The fuel cell flow field plate according to claim 1, wherein, The flow channel form of the parallel flow field is a parallel straight flow channel or a parallel meandering flow channel.

5. The fuel cell flow field plate according to claim 1, wherein, The parallel flow field is located in the middle of the fuel cell flow field plate, and the fuel cell flow field plate further includes dot-shaped flow fields at both ends of the parallel flow field.

6. A fuel cell single cell, characterized in that, It includes the fuel cell flow field plate according to any one of claims 1 to 5.

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