Fuel cell, fuel cell single cell and shrapnel

Abstract

Embodiments of the present invention disclose a fuel cell, a fuel cell single cell, and a shrapnel. The fuel cell includes a plurality of fuel cell single cells. The fuel cell single cell includes: a membrane electrode assembly, a gas diffusion layer, a plate electrode, and a shrapnel; a plurality of ridges are provided on a surface of the plate electrode facing the gas diffusion layer; the shrapnel is disposed between the corresponding plate electrode and the gas diffusion layer, and a position corresponding to the top surface of the ridge is a protection portion; the shrapnel sequentially includes three states, namely a first state, a second state, and a third state under the extrusion of the plate electrode and the gas diffusion layer; when in the first state, the protection portion is a first arc-shaped structure convex toward the gas diffusion layer; when in the second state, the protection portion is a second arc-shaped structure fitting between the top surface of the ridge and the gas diffusion layer; when in the third state, an edge portion of the protection portion is a fourth arc-shaped structure convex toward the gas diffusion layer, and the fourth arc-shaped structure covers a convex angle generated by the deformation of the ridge. The shrapnel of the present application can prevent the plate electrode from damaging the gas diffusion layer and the membrane electrode assembly.

Description

Technical Field

[0001] The present application relates to the field of batteries, and more particularly, to fuel cells, fuel cell single cells, and shrapnel. Background Art

[0002] A fuel cell single cell includes a membrane electrode assembly, a gas diffusion layer, and a plate electrode that are stacked. The plate electrode is generally provided with a flow field including a plurality of gas flow channels, and its function is to provide reaction gases (such as hydrogen or air) for the electrochemical reaction. Adjacent gas flow channels are separated by ridge portions.

[0003] When assembling a fuel cell, a plurality of fuel cell single cells need to be stacked together. To ensure close contact between adjacent layer structures, it is necessary to press-stack the multi-layer structure of the fuel cell. During the press-stacking process, the plate electrode, gas diffusion layer, and membrane electrode assembly of the single cell are squeezed, and finally the gaps are reduced or eliminated.

[0004] It has been found that the membrane electrode assembly in the fuel cell single cell is prone to damage after press-stacking. In response, related technicians prevent membrane electrode damage by monitoring and controlling the pressure during the press-stacking process, but it is not completely effective. Summary of the Invention

[0005] One of the key points of the present invention is that the inventor has discovered an important reason for the damage of the membrane electrode during the press-stacking of current fuel cells. The inventor has found that the ridge portion, as a protruding part of the flow field region, is in direct contact with the gas diffusion layer and is squeezed. If the pressure distribution of different single cells is uneven during press-stacking and the pressure in some areas is too high, the ridge portions in these areas are extremely prone to slight deformation; local protrusions appear on both sides of the width of the deformed ridge portion, and the local pressure generated by these protrusions on the gas diffusion layer and the proton exchange membrane may be much greater than the design allowable value, thereby causing the proton exchange membrane to be damaged. Based on the above discovery of the inventor, the present invention provides a fuel cell and a fuel cell single cell, aiming to solve the above problems existing in the prior art.

[0006] To achieve the above object, the present invention provides a shrapnel for a fuel cell single cell, characterized in that

[0007] the shrapnel is disposed between the plate electrode and the gas diffusion layer of the fuel cell single cell;

[0008] a plurality of ridge portions are provided on the surface of the plate electrode facing the gas diffusion layer;

[0009] the shrapnel includes a protection portion that covers the top surface of the ridge portion;

[0010] the shrapnel includes three states under the extrusion of the plate electrode and the gas diffusion layer:

[0011] When there is no pressure, the elastic piece is in the first state. The protection part in the first state is a first arc structure convex towards the gas diffusion layer, and the gas diffusion layer contacts but does not apply force to the elastic piece; when the pressure gradually increases within a preset range, the elastic piece gradually switches from the first state to the second state. The protection part in the second state is a second arc structure convex towards the gas diffusion layer, and the curvature of the second arc structure is smaller than that of the first arc structure; when the pressure increases beyond the preset range, the elastic piece switches from the second state to the third state. The middle part of the protection part in the third state protrudes towards the ridge part, and the edge part of the protection part covers the convex corners on both sides of the top surface width of the ridge part to protect the gas diffusion layer.

[0012] In some embodiments, the material of the elastic piece is metal; the surface of the elastic piece is a hydrophilic surface.

[0013] In some embodiments, the thickness of the middle part is smaller than the thickness of the edge part.

[0014] In some embodiments, the width of the top surface of the ridge part is W;

[0015] When the elastic piece is in the first state, the maximum height from the protection part to the top surface of the ridge part is H;

[0016] W and H satisfy the following conditions:

[0017] 0.2W ≤ H ≤ 0.4W.

[0018] In some embodiments, there is a groove part between two adjacent ridge parts;

[0019] The elastic piece is provided with a recessed part between two adjacent protection parts;

[0020] The recessed part is embedded in the groove part, and both sides are at least partially attached to the side walls of two adjacent ridge parts respectively.

[0021] In some embodiments, the bottom of the recessed part is separated from the bottom surface of the groove part, and the bottom of the recessed part has a plurality of openings.

[0022] In some embodiments, at least part of the openings are processed by punching process;

[0023] In the gas flow direction of the groove part, the connection part between the punched part and the elastic piece is located downstream of the opening, and the punched part deflects towards the bottom surface of the groove part.

[0024] In some embodiments, the length of the punched part is smaller than the distance between the bottom of the recessed part and the bottom surface of the groove part.

[0025] In addition, to achieve the above object, the present invention further provides a fuel cell single cell, which is characterized by comprising:

[0026] a membrane electrode assembly;

[0027] a gas diffusion layer disposed outside the membrane electrode;

[0028] a plate electrode disposed on a side of the gas diffusion layer away from the membrane electrode assembly;

[0029] a shrapnel as described in any one of the foregoing embodiments.

[0030] In addition, to achieve the above object, the present invention further provides a fuel cell, which is characterized by comprising a plurality of fuel cell single cells as described in any one of the foregoing embodiments.

[0031] The fuel cell proposed in this application includes a plurality of fuel cell single cells. A shrapnel for protection is disposed between the plate electrode and the gas diffusion layer of the fuel cell single cell, and the area of the shrapnel corresponding to the ridge is the protection part. When stacking the cells, the shrapnel is deformed under the extrusion of the plate electrode and the gas diffusion layer, and has a first state, a second state, and a third state; at the beginning, the shrapnel contacts the plate electrode and the gas diffusion layer but is not subjected to extrusion force, and the shrapnel is in the first state, and the protection part is a first arc structure convex toward the gas diffusion layer to play a buffering role; when the pressure between the plate electrode and the gas diffusion layer is within a reasonable range, the shrapnel is in the second state, and the protection part is a second arc structure convex toward the gas diffusion layer, and the curvature of the second arc structure is smaller than that of the first arc structure; when the pressure between the plate electrode and the gas diffusion layer is too large, the shrapnel is in the third state, and the middle part of the protection part is reversed and instead protrudes toward the ridge, and the edge part of the protection part covers the convex corners on both sides of the top width of the ridge. Therefore, when the pressure between the plate electrode and the gas diffusion layer is too large, the gas diffusion layer and the membrane electrode assembly do not directly contact the convex corners of the plate electrode ridge, but contact the edge part of the protection part; compared with the convex corners of the ridge, the contact area of the edge part of the protection part is larger, so that damage to the gas diffusion layer and the membrane electrode assembly can be avoided. Description of the Drawings

[0032] To more clearly illustrate the technical solutions of the embodiments of this application, the following will briefly introduce the drawings required for the embodiments. It should be understood that the following drawings only show some embodiments of this application, and therefore should not be regarded as limiting the scope. For those of ordinary skill in the art, other related drawings can also be obtained based on these drawings without creative efforts.

[0033] The methods, systems, and / or programs in the accompanying drawings will be further described according to exemplary embodiments. These exemplary embodiments will be described in detail with reference to the drawings. These exemplary embodiments are non-limiting exemplary embodiments, where reference numerals represent similar mechanisms in the various views of the drawings.

[0034] Figure 1 Schematic diagram of the structure of a shrapnel related to some embodiments of the present application;

[0035] Figure 2 Schematic diagram of the structure of a single fuel cell related to some embodiments of the present application;

[0036] Figure 3 Schematic diagram of the structure of a single fuel cell related to some embodiments of the present application when the shrapnel is in the second state;

[0037] Figure 4 Schematic diagram of the structure of a single fuel cell related to some embodiments of the present application when the shrapnel is in the third state;

[0038] Figure 5 For Figure 2 Partial enlarged view;

[0039] Figure 6 Schematic diagram of the structure of another single fuel cell related to some embodiments of the present application when the shrapnel is in the first state;

[0040] Figure 7 Schematic diagram of the structure of another single fuel cell related to some embodiments of the present application when the shrapnel is in the second state;

[0041] Figure 8 For Figure 6 Cross-sectional view along line C-C.

[0042] Icon: 10 - Membrane electrode assembly, 20 - Gas diffusion layer, 30 - Plate electrode, 31 - Ridge, 311 - Convex angle, 32 - Groove, 40 - Shrapnel, 41 - Protection part, 411 - First arc structure, 412 - Second arc structure, 413 - Third arc structure, 414 - Fourth arc structure, 42 - Depression, 421 - Opening, 422 - Punched-out part, 423 - Connection part, 43 - Spacing part, 44 - Connection part. Detailed implementation manners

[0043] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of this application. Apparently, the described embodiments are some, but not all, of the embodiments of this application. The components of the embodiments of this application usually described and illustrated in the accompanying drawings here can be arranged and designed in various different configurations.

[0044] Therefore, the following detailed description of the embodiments of this application provided in the drawings is not intended to limit the scope of the claimed application, but merely represents selected embodiments of this application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in this application without creative efforts fall within the scope of protection of this application.

[0045] It should be noted that like reference numerals and letters denote like items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings.

[0046] In the description of this application, it should be noted that if terms such as "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. are used to indicate the orientation or positional relationship, it is based on the orientation or positional relationship shown in the drawings or the orientation or positional relationship in which the product of this application is usually placed during use. It is only for the convenience of describing this application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to this application. In addition, in the description of this application, if terms such as "first", "second", etc. are used only for distinguishing descriptions, they cannot be understood as indicating or implying relative importance.

[0047] In addition, in the description of this application, if terms such as "horizontal" and "vertical" are used, it does not mean that the components are required to be absolutely horizontal or hanging vertically, but can be slightly inclined. For example, "horizontal" only means that its direction is more horizontal relative to "vertical", and does not mean that the structure must be completely horizontal, but can be slightly inclined.

[0048] In the description of this application, it should also be noted that unless otherwise clearly specified and limited, if terms such as "set", "installed", "connected", "connected" are used, they should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected, or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0049] Please refer to Figure 1, the shrapnel 40 located in the XY plane will now be described. The shrapnel 40 of this embodiment includes a plurality of protection parts 41 arranged in parallel, an interval part 43 located between two adjacent protection parts 41, and connection parts 44 located at both ends of the protection parts 41; the connection parts 44 connect the plurality of protection parts 41 to form an integral body.

[0050] Please refer to Figure 2 , and the cross-section of the flow field region of the fuel cell single cell in the XZ plane will be described. The fuel cell single cell of this embodiment includes: a membrane electrode assembly 10, two gas diffusion layers 20, two plate electrodes 30, and two shrapnels 40.

[0051] The membrane electrode assembly 10 includes a proton exchange membrane and a catalytic layer (not shown in the figure). Among them, the catalytic layer is provided on both sides of the proton exchange membrane. The two gas diffusion layers 20 are respectively attached to the catalytic layers of the membrane electrode assembly 10 from both sides.

[0052] The two plate electrodes 30 are respectively the cathode plate and the anode plate of the fuel cell. The two plate electrodes 30 are respectively arranged on one side of the two gas diffusion layers 20 away from the membrane electrode assembly 10, and a plurality of ridge parts 31 are provided on the surface facing the gas diffusion layer 20. There is a groove part 32 between two adjacent ridge parts 31. The groove part 32 serves as a gas flow channel for the reaction gas to flow, and the region where the groove part 32 and the ridge part 31 are located is the flow field region. When the fuel cell single cell works, part of the reaction gas enters the corresponding gas diffusion layer 20 from the groove part 32, and finally reaches the catalytic layer of the membrane electrode assembly 10 and undergoes an electrochemical reaction.

[0053] The two shrapnels 40 are respectively arranged between the corresponding plate electrode 30 and the gas diffusion layer 20. The protection part 41 covers the top surface of the ridge part 31, the interval part 43 is located in the groove part 32, and the interval part 43 is a void without solid material to facilitate the passage of gas. The width of the protection part 41 can be slightly larger than the width of the top surface of the ridge part 31. Correspondingly, the width of the interval part 43 can be slightly smaller than the width of the groove part 32.

[0054] As an alternative way, the protection parts 41 and the interval parts 43 of the shrapnel 40 are laid in the flow field region of the plate electrode 30, and the connection parts 44 are located outside the flow field region. All the protection parts 41 can cover all the ridge parts 31 of the plate electrode 30 one by one.

[0055] Furthermore, as an alternative way, positioning structures that cooperate with each other, such as positioning protrusions and positioning grooves, are provided on the plate electrode 30 and the connection parts 44. Since the connection parts 44 are located outside the flow field region, the positioning structures will not block the reaction gas. The positioning structures can fix the relative positions between the plate electrode 30 and the shrapnel 40, so that the protection part 41 can always cover the top surface of the ridge part 31 during the stacking process.

[0056] In this application, the cathode plate and the anode plate may have similar structures. Similarly, the two gas diffusion layers 20 and the two shrapnel pieces 40 also have similar structures respectively. Therefore, in order to highlight the detailed features, only the membrane electrode assembly 10, the gas diffusion layer 20, the plate 30, and the shrapnel piece 40 on one side thereof will be described in the following description of the specification. It can be understood that these descriptions also apply to the gas diffusion layer 20, the plate 30, and the shrapnel piece 40 on the other side.

[0057] Please refer to Figures 2 - 4 , the shrapnel piece 40 in this embodiment successively includes three states under the extrusion of the plate 30 and the gas diffusion layer 20: Figure 2 is a schematic structural diagram of the shrapnel piece 40 of the fuel cell single cell in the first state in the embodiment of this application; Figure 3 is a schematic structural diagram of the shrapnel piece 40 of the fuel cell single cell in the second state in the embodiment of this application; Figure 4 is a schematic structural diagram of the shrapnel piece 40 of the fuel cell single cell in the third state in the embodiment of this application.

[0058] As Figure 2 shown, at the beginning, the shrapnel piece 40 is in contact with the plate 30 and the gas diffusion layer 20 respectively, but the shrapnel piece 40 is not extruded by the plate 30 and the gas diffusion layer 20. At this time, the shrapnel piece 40 is in the first state, and the protection part 41 is a first arc-shaped structure 411 convex toward the gas diffusion layer 20, and the gas diffusion layer 20 is in contact with but does not apply force to the protection part 41.

[0059] As Figure 3 shown, as the stack pressing progresses, the shrapnel piece 40 is deformed under the combined extrusion of the plate 30 and the gas diffusion layer 20, and the first arc-shaped structure 411 of the protection part 41 is gradually flattened. When the pressure between the plate 30 and the gas diffusion layer 20 is within a preset reasonable range, the protection part 41 becomes a second arc-shaped structure 412 convex toward the gas diffusion layer 20, and the curvature of the second arc-shaped structure 412 is smaller than that of the first arc-shaped structure 411. At this time, the shrapnel piece 40 is in the second state, the contact area between the plate 30 and the gas diffusion layer 20 is large, and the pressure distribution is uniform, which will not cause damage to the gas diffusion layer 20 and the membrane electrode assembly 10.

[0060] As Figure 4As shown, when the pressure further increases until it exceeds the preset reasonable range, the ridge portion 31 of the plate electrode 30 is deformed: the middle part of the top surface of the ridge portion 31 is slightly sunken inward, and convex corners 311 facing the gas diffusion layer 20 are formed on both sides of the width. The shrapnel 40 in this embodiment is also deformed accordingly when the pressure exceeds the reasonable range: the middle part of the protection portion 41 bulges reversely under the action of the pressure, forming a third arc structure 413 convex toward the ridge portion 31; the edge portions of the protection portion 41 have the same protruding direction as in the first and second states, that is, a fourth arc structure 414 convex toward the gas diffusion layer 20 is formed; the two fourth arc structures 414 respectively cover the two convex corners 311 of the ridge portion 31, and at this time the shrapnel 40 is in the third state.

[0061] In this embodiment, both the first state and the third state of the shrapnel 40 are stable states, that is, after the pressure is removed, the shrapnel 40 can still maintain the existing state; the second state of the shrapnel 40 is an unstable state, and after the pressure is removed, the shrapnel 40 will return to the first state; when the pressure received by the middle part of the protection portion 41 exceeds the critical value (i.e., the upper limit of the reasonable range), the shrapnel 40 switches from the second state to the third state.

[0062] It can be understood that when there is no shrapnel 40, if the pressure exceeds the reasonable range, the convex corner 311 will directly contact the gas diffusion layer 20, resulting in a sharp increase in the local pressure of the gas diffusion layer 20 and the membrane electrode assembly 10 at this place and exceeding the design value, and the convex corner 311 will "pierce" the gas diffusion layer 20 and the membrane electrode assembly 10.

[0063] In this embodiment, when the shrapnel 40 is in the third state, the curvature of the fourth arc structure 414 is smaller than the curvature of the convex corner 311. Therefore, the contact area between the gas diffusion layer 20 and the fourth arc structure 414 is larger than the contact area between the gas diffusion layer 20 and the convex corner 311. Compared with the second state, the local pressure when the gas diffusion layer 20 contacts the fourth arc structure 414 in the third state increases slightly, but is still less than the design value. Therefore, the probability of damage to the gas diffusion layer 20 and the membrane electrode assembly 10 can be reduced.

[0064] As an optional method, the material of the shrapnel 40 is metal, which can reduce the contact resistance between the plate electrode 30, the shrapnel 40 and the gas diffusion layer 20; the surface of the shrapnel 40 is a hydrophilic surface, so that the water generated by the fuel cell can quickly spread along the surface of the shrapnel 40 after reaching the shrapnel 40 through the gas diffusion layer 20, and then be discharged along with the flow of the reaction gas.

[0065] Please refer to Figure 5 , Figure 5 For Figure 2The enlarged view of the middle B area shows that in some embodiments, the thickness d1 of the middle part of the protection portion 41 is less than the thickness d2 of the edge part, which helps the spring 40 to smoothly enter the third state when it is subjected to a pressure beyond the reasonable range. When the spring 40 switches from the second state to the third state under pressure, the middle part is thinner and is more likely to deform under the pressure of the gas diffusion layer 20 until it bulges in the opposite direction; the edge part is thicker, which can prevent the edge part from being squeezed by the convex corner 311 and deforming significantly, thereby forming a fourth arc structure 414 to protect the gas diffusion layer 20 and the membrane electrode assembly 10.

[0066] In some embodiments, Figure 5 As shown, the width of the top surface of the ridge 31 is W, and when the spring sheet 40 is in the first state, the maximum height from the protection portion 41 to the top surface of the ridge 31 is H, and W and H meet the condition: 0.2W≤H≤0.4W. If the height H is too large, the protection portion 41 of the spring sheet 40 in the first state is too protruding compared to the top surface of the ridge 31, resulting in that when the spring sheet 40 is subsequently squeezed into the second state, the protection portion 41 will fit between the top surface of the ridge 31 and the gas diffusion layer 20 with a larger curvature, thereby increasing the contact resistance between the electrode plate 30, the spring sheet 40 and the gas diffusion layer 20, and reducing the power generation efficiency of the fuel cell. If the height H is too small, the deformation margin of the spring piece 40 is insufficient, resulting in the spring piece 40 being unable to enter the third state, or when the spring piece 40 is in the third state, the curvature radius of the fourth arc structure 414 is too small, and thus the contact area between the fourth arc structure 414 and the gas diffusion layer 20 will also decrease, and the local pressure between the two will increase, and eventually the spring piece 40 will cause damage to the gas diffusion layer 20 and the membrane electrode assembly 10.

[0067] like Figure 6 As shown, in some embodiments, a spacer 43 located between two adjacent protective portions 41 and having no solid material is replaced by a recessed portion 42 having solid material. After assembly, the recessed portion 42 is embedded in the groove portion 32 of the electrode plate 30, and the two sides of the recessed portion 42 respectively fit the side walls of the two adjacent ridges 31. Since the protective portion 41 needs to completely cover the ridge 31, the width of the protective portion 41 is greater than the width of the ridge 31. Under this condition, in order to enable the two sides of the recessed portion 42 to better fit the side walls of the ridge 31, the cross-section of the ridge 31 in this embodiment can be a trapezoid that is narrow at the top and wide at the bottom. In this embodiment, the two adjacent protective portions 41 are connected by the recessed portion 42, so as to enhance the structural strength of the spring piece 40 and prevent the spring piece 40 from being damaged during processing, transportation and assembly. In addition, in this embodiment, relying on the matching relationship between the recessed portion 42 and the groove portion 32, it can be Figure 6 The spring piece 40 is fixed in the X direction, that is, in the direction perpendicular to the extension of the groove portion 32, to avoid misalignment between the protection portion 41 and the top surface of the ridge portion 31 during stacking.

[0068] As an alternative, the bottom of the recess 42 is separated from the bottom surface of the groove 32, that is, there is a certain distance between the bottom of the recess 42 and the bottom surface of the groove 32. In this embodiment, the recess 42 can not only play a fixing role, but also serve as a buffer when the shrapnel 40 switches states. As Figure 7 shown, when the shrapnel 40 switches from the first state to the second state, the protection part 41 changes from the first arc structure 411 to the second arc structure 412. At this time, the bottom of the recess 42 bends to accommodate the reduced part caused by the deformation of the protection part 41. Further, the bottom of the recess 42 has a plurality of openings 421; in this embodiment, the recess 42 divides the groove 32 into upper and lower regions, and the openings 421 can communicate these two regions, facilitating the reaction gas in the lower region of the groove 32 to flow into the gas diffusion layer 20, and also facilitating the water droplets generated by the gas diffusion layer 20 to enter the lower region of the groove 32 to accelerate the discharge.

[0069] Please refer to Figure 6 and Figure 8 , Figure 8 is Figure 6 the sectional view along the C-C line in Figure 8 In some embodiments, at least part of the openings 421 are processed by the punching process. The direction indicated by the short line segment arrow in

[0070] (i.e., the positive direction of the Y axis) is the gas flow direction of the groove 32. The connection part 423 between the punched part 422 and the shrapnel 40 is located downstream of the opening 421, and the punched part 422 deflects towards the bottom surface of the groove 32. In this embodiment, the shrapnel 40 can be obtained by stamping, and the bottom of the recess 42 is partially punched to form the openings 421. The punched part 422 is not completely separated from the shrapnel 40, but deflects from the connection part 423 towards the bottom surface of the groove 32, disturbing the gas flow in the lower region of the groove 32. Since the connection part 423 is located downstream of the opening 421, the gas can turn and flow through the opening 421 to the upper region of the groove 32 after being blocked by the punched part 422, thereby increasing the rate of gas entering the gas diffusion layer 20 and improving the gas utilization rate.

[0071] Some embodiments of the present application relate to a fuel cell, including a plurality of fuel cell single cells as described in any of the foregoing embodiments, a current collector plate, and end plates. The plurality of fuel cell single cells are stacked in sequence. The current collector plate is used to collect the current generated by the plurality of fuel cell single cells. The number of end plates is two, and the two end plates cooperate and are fixedly connected through anchor members to connect functional components such as the plurality of fuel cell single cells and the current collector plate into a whole.

[0072] The foregoing are only the preferred embodiments of the present application and are not intended to limit the present application. For those skilled in the art, the present application may have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included within the protection scope of the present application.

Claims

1. A shrapnel for a fuel cell single cell, characterized in that, the shrapnel is arranged between the plate electrode and the gas diffusion layer of the fuel cell single cell; a plurality of ridges are arranged on the surface of the plate electrode facing the gas diffusion layer; the shrapnel includes a protection part, and the protection part covers the top surface of the ridge; the shrapnel includes three states under the extrusion of the plate electrode and the gas diffusion layer: when there is no pressure, the shrapnel is in the first state, the protection part in the first state is a first arc structure convex towards the gas diffusion layer, and the gas diffusion layer contacts but does not exert force on the shrapnel; when the pressure gradually increases within a preset range, the shrapnel gradually switches from the first state to the second state, the protection part in the second state is a second arc structure convex towards the gas diffusion layer, and the curvature of the second arc structure is smaller than that of the first arc structure; when the pressure increases beyond the preset range, the shrapnel switches from the second state to the third state, the middle part of the protection part in the third state convex towards the ridge, and the edge part of the protection part covers the convex corners on both sides of the width of the top surface of the ridge to protect the gas diffusion layer.

2. The shrapnel according to claim 1, characterized in that, the material of the shrapnel is metal; the surface of the shrapnel is a hydrophilic surface.

3. The shrapnel according to claim 1, characterized in that, the thickness of the middle part is smaller than the thickness of the edge part.

4. The shrapnel according to claim 1, characterized in that, the width of the top surface of the ridge is W; when the shrapnel is in the first state, the maximum height from the protection part to the top surface of the ridge is H; W and H satisfy the following conditions: 0.2W ≤ H ≤ 0.4W.

5. The shrapnel according to claim 1, characterized in that, there is a groove between two adjacent ridges; a recess is arranged between two adjacent protection parts of the shrapnel; the recess is embedded in the groove, and both sides are at least partially attached to the side walls of two adjacent ridges respectively.

6. The shrapnel according to claim 5, characterized in that, the bottom of the recess is separated from the bottom surface of the groove, and the bottom of the recess has a plurality of openings.

7. The shrapnel according to claim 6, characterized in that, at least part of the openings are processed by punching; in the gas flow direction of the groove, the connection part between the punched part and the shrapnel is located downstream of the opening, and the punched part deflects towards the bottom surface of the groove.

8. The shrapnel according to claim 7, characterized in that, the length of the punched part is smaller than the distance between the bottom of the recess and the bottom surface of the groove.

9. A fuel cell single cell, characterized in that, comprising: a membrane electrode assembly; a gas diffusion layer arranged outside the membrane electrode; a plate electrode arranged on the side of the gas diffusion layer away from the membrane electrode assembly; the shrapnel according to any one of claims 1-8.

10. A fuel cell, characterized in that, comprising a plurality of fuel cell single cells according to claim 9.

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