A seal structure for a polar plate of a fuel cell single cell

Abstract

The application relates to the field of fuel cells and discloses a polar plate sealing structure of a fuel cell single cell, which comprises a polar plate, a membrane electrode, a sealing gasket and a hot melt adhesive film. The polar plate is provided with a protruding boss between a three-cavity inlet and outlet and a flow field edge and a polar plate frame, the boss plane is higher than the flow field ridge plane, and the height is the thickness of a single layer of a gas diffusion layer of the membrane electrode after assembly; the boss surface of the cathode and anode polar plates is pasted with the hot melt adhesive film, the membrane electrode is clamped between the cathode and anode polar plates, and the plastic frame of the membrane electrode is bonded by the hot melt adhesive film; the back side of the boss is a groove, an elastic sealing gasket is pasted in the groove of one of the polar plates, the single cell gas cavity is bonded and sealed by the hot melt adhesive film, and the cooling cavity is sealed by the sealing gasket. The application avoids the slippage between the membrane electrode and the polar plate during the application of the stack, is simple in assembly, good in single cell flatness, and improves the service life of the stack.

Description

Technical Field

[0001] This invention relates to the field of fuel cell technology, and in particular to a plate sealing structure for a single fuel cell. Background Technology

[0002] A proton exchange membrane fuel cell (PEMFC) is a power generation device that uses hydrogen as the anode, air (oxygen) as the cathode, and a proton exchange membrane (PEM) as the electrolyte. The bipolar plate is a structural component in the PEMFC stack that separates hydrogen from oxygen (or air) and the coolant, serving functions of gas conduction, heat conduction, and electrical conduction. The PEMFC plate structure includes three chambers (hydrogen chamber, air chamber, and water chamber) with inlet and outlet channels, flow fields, and a plate frame surrounding the inlet and outlet and flow fields. A sealing structure is installed at the plate frame. A conventional PEMFC structure consists of stacked bipolar plates and membrane electrode assemblies (MEAs), with gaskets used to isolate and seal the MEAs and plates. MEAs, plates, and gaskets are manufactured separately. The stack assembly involves sequentially stacking bipolar plates and MEAs. The anode and cathode cavity gaskets are either pre-attached to the bipolar plates or pre-integrated with the MEAs. The bipolar plate cooling chamber can be sealed by adhesive bonding, while metal bipolar plates can be sealed by welding. The cooling chamber can also be sealed with an elastic gasket. Although the anode and cathode cavity gaskets are fixed, during fuel cell assembly, fuel cell vibration or impact, and fuel cell operating temperature cycling, the elastic gaskets will shift or deform unevenly, causing leaks, unstable assembly forces, and other faults. This makes resetting difficult during fuel cell maintenance and reduces fuel cell life. Summary of the Invention

[0003] The purpose of this invention is to provide a plate sealing structure for a single cell of a fuel cell, which prevents slippage between the membrane electrode and the plate during the application of the fuel cell stack and improves the service life of the fuel cell stack.

[0004] Therefore, the present invention provides the following technical solution:

[0005] A electrode sealing structure for a single fuel cell, characterized in that it includes an electrode plate, a membrane electrode assembly, a sealing gasket, and a hot melt adhesive film;

[0006] The electrode plates have protruding bosses around the three-cavity inlet and outlet and between the flow field edge and the electrode plate frame. The plane of the boss is higher than the ridge plane of the flow field, and the height is the thickness of the single-layer gas diffusion layer of the membrane electrode after assembly. Hot melt adhesive film is pasted on the surface of the boss of the anode and cathode plates. The membrane electrode is sandwiched between the anode and cathode plates, and the plastic frame of the membrane electrode is bonded by the hot melt adhesive film. The back side of the boss is a groove. An elastic sealing gasket is pasted in the groove of one of the electrode plates. The gas cavity of the single cell is sealed by the hot melt adhesive film, and the cooling cavity is sealed by the sealing gasket.

[0007] Furthermore, the three-cavity stamped edge ring is flipped up at the electrode plate entry point to form a gas channel and a cooling cavity channel, i.e., a protruding boss as described in claim 1. Reinforcing ribs are provided on both sides of this boss, supporting the bonding surface on one hand and limiting the sealing gasket on the other. Holes are drilled on the reinforcing rib side of the protrusion in the cathode (and anode) gas inlet / outlet channel facing the flow field. Gas enters the flow field through these holes. Dot-shaped bosses are provided between the channel holes and the flow field. Sealing gaskets are attached to the back of these dot-shaped bosses. The surface of the sealing gasket is machined with protrusions that embed into the dot-shaped grooves of the electrode plate, ensuring the sealing gasket is not misaligned and is fixed, thus isolating the gas cavity and cooling cavity of the bipolar plate. The sealing gasket and the cooling cavity sealing gasket are integrally formed. The cooling cavity inlet / outlet channels utilize the shape or length difference of the corresponding groove reinforcing ribs of the cathode and anode plates to form intersections or extensions to guide the coolant into and out of the bipolar plate.

[0008] Furthermore, the thickness of the sealing gasket used in the single-cell sealing structure is specified as follows:

[0009] Let the thickness of the electrode material be l, the thickness of the hot melt adhesive film be t, the thickness of the active part of the membrane electrode be δ, the thickness of the membrane electrode frame be τ, and the thickness of the cooling chamber sealing gasket be λ; the thickness of the electrode flow field region be α1, and the thickness of the other electrode is α. 2， After the fuel cell stack is assembled, the hot melt adhesive film compression rate is η, the active part of the membrane electrode compression rate is γ, and the sealing gasket compression rate is σ.

[0010] δ*γ+α1+α2=2*l+2t *η+τ+λ*σ

[0011] Right now

[0012] λ*σ=[δ*γ+α1+α2]-[2*l+2t *η+τ]

[0013] The single-cell structure described in this invention firmly bonds the electrode plates and the membrane electrode with a hot melt adhesive film, preventing slippage between the membrane electrode and the electrode plates during the application of the stack. The cooling chamber sealing gasket is also attached to the electrode plates, making the stack assembly simple, the single cell flat, the positioning accurate, and the stack disassembly and maintenance operations convenient. Attached Figure Description

[0014] Figure 1 This is an exploded view of a single cell in one embodiment of the present invention.

[0015] Figure 2 This is a schematic diagram of the electrode gas cavity in one embodiment of the present invention.

[0016] Figure 3 This is a partial schematic diagram of the electrode plate air cavity in one embodiment of the present invention.

[0017] Figure 4 This is a schematic diagram of the electrode cooling cavity in one embodiment of the present invention.

[0018] Figure 5 This is a schematic diagram of the sealing gasket at the single-cell channel portion in one embodiment of the present invention.

[0019] Figure 6 This is a schematic diagram of hot melt adhesive film bonding and sealing gasket bonding in one embodiment of the present invention.

[0020] Figure 7 This is a partial schematic diagram of the cross-section of electrode plate AA in one embodiment of the present invention.

[0021] Figure 8 This is a schematic diagram of partial sealing of a single battery AA section in one embodiment of the present invention.

[0022] Figure 9 This is a schematic diagram of gas entry at section AA of the fuel cell stack in one embodiment of the present invention.

[0023] In the diagram, 1 represents the electrode plate, 101 and 102 are the electrode plate air cavity inlets, 103 is the electrode plate cooling cavity inlet, 104 is the positioning hole, 106 is the air cavity channel opening, 107 is the electrode plate boss, 108 is the cavity inlet pressure ring, 109 is the boss stamping recess, 110 is the cooling cavity boss channel, 111 is the electrode plate flow field, 112 is the electrode plate frame, and 113 is the small protruding boss; 2 represents the counter electrode plate, 201 and 202 are the electrode plate air cavity inlets, and 203 is the electrode plate cooling cavity inlet. 204 is the positioning hole, 206 is the air cavity channel opening, 207 is the electrode plate boss, 208 is the cavity inlet pressure ring, 209 is the boss stamping recess, 210 is the cooling cavity boss channel, 211 is the electrode plate flow field, 212 is the electrode plate frame, and 213 is the small protruding boss; 3 is the membrane electrode, 301 and 302 are the battery air cavity inlet, and 303 is the cooling cavity inlet; 4 is the elastic sealing gasket, and 413 is the sealing gasket small protrusion; 5 and 6 are die-cut hot melt adhesive film. Detailed Implementation

[0024] The single-cell electrode plate and sealing structure described in this invention are as follows: A raised platform is provided around the three-chamber inlet / outlet and between the flow field edge and the electrode plate edge. The plane of the raised platform is higher than the ridge plane of the flow field, and its height is approximately the thickness of the membrane electrode gas diffusion layer after assembly. A hot melt adhesive film is pasted onto the surface of the raised platform of the anode and cathode plates. The membrane electrode is sandwiched between the anode and cathode plates, and the plastic frame of the membrane electrode is bonded by the hot melt adhesive film. The back side of the raised platform is a groove, and an elastic sealing gasket is pasted into one of the electrode plate grooves. The single-cell gas chamber is sealed by the hot melt adhesive film, and the cooling chamber is sealed by the sealing gasket.

[0025] The electrode cavity of this invention comprises three parts: a flow field part, a hot melt adhesive film bonding part, and a three-cavity inlet / outlet and channel part. The height of the hot melt adhesive film bonding part on the gas cavity side of the electrode, i.e., the boss 107, is designed to accommodate cell matching; the boss plane is higher than the gas flow field plane by a height comparable to the thickness of the single-layer gas diffusion layer after assembly. A sealing gasket is adhered to the electrode cooling cavity groove 207. Both the anode and cathode plates have opposing cooling cavity grooves, and a sealing gasket is placed between two single cells, embedded and fixed within the opposing cooling cavity grooves of the anode and cathode plates.

[0026] The thickness of the sealing gasket is determined according to the following formula:

[0027] like Figure 1 The thickness of the electrode material is l, the thickness of the hot melt adhesive films 5 and 6 is t, the thickness of the active part of the membrane electrode is δ, the thickness of the membrane electrode frame is τ, and the thickness of the cooling chamber sealing gasket is λ; Figure 2 The thickness of plate flow field region 111 is α1, and the thickness of 211 is α. 2， Assume that after assembling the fuel cell stack, the compressibility of the hot melt adhesive film is η, the compressibility of the active part of the membrane electrode is γ, the compressibility of the sealing gasket is σ, and other materials do not deform under compression. Thus:

[0028] δ*γ+α1+α2=2*l+2t *η+τ+λ*σ

[0029] Right now

[0030] λ*σ=[δ*γ+α1+α2]-[2*l+2t *η+τ]

[0031] For example:

[0032] The electrode material thickness is 0.10 mm, the hot melt adhesive film thicknesses 5 and 6 are 0.05 mm, the active part thickness of the membrane electrode is 0.38 mm, the membrane electrode frame thickness is 0.10 mm, and the cooling chamber sealing gasket thickness is λ; Figure 2 The thickness of plate flow field region 111 is 0.45 mm, and the thickness of plate 211 is 0.40 mm. ， Assume that after assembling the fuel cell stack, the hot melt adhesive film compression rate is 30%, the active part of the membrane electrode compression rate is 25%, and the sealing gasket compression rate is 28%.

[0033] Therefore, the gasket thickness λ*(1-28%) = [0.38*(1-25%) + 0.45 + 0.40] - [2*0.10 + 2*0.05*(1-30%) + 0.10]

[0034] λ=1.06mm

[0035] The single-cell electrode plate and sealing structure described in this invention are configured as follows at the three-cavity inlet and outlet: the stamped edge ring at the three-cavity inlet flips up at the electrode plate entry point, forming a gas channel and a cooling cavity channel, i.e., the protruding platform as described in 1. Reinforcing ribs are provided on both sides of the protrusion at this location, supporting the bonding surface on one hand and limiting the sealing gasket on the other. Holes are drilled on the reinforcing ribs of the protrusions of the cathode (and anode) gas inlet and outlet channels facing the flow field, allowing gas to enter the flow field through the holes. Dot-shaped protrusions are provided between the channel holes and the flow field, with sealing gaskets adhered to the back of these protrusions. Protrusions are machined on the surface of the sealing gasket at this location, embedding into the dot-shaped grooves of the electrode plate to ensure the sealing gasket is not misaligned and is fixed, thus isolating the gas cavity and cooling cavity of the bipolar plate. The sealing gasket and the cooling cavity sealing gasket are integrally formed. The cooling cavity inlet and outlet channels utilize the shape or length difference of the corresponding groove reinforcing ribs of the cathode and anode plates to form intersections or extensions to guide the coolant flow into and out of the bipolar plate.

[0036] like Figure 3 When the electrode gas cavity inlet 102 is stamped, it has a pressure ring 108. The pressure ring flips up at the gas inlet channel to form a protrusion, i.e., a boss 107. The boss plane is bonded to the electrode hot melt adhesive film. The boss 107 on the periphery of the electrode flow field and the boss plane on the periphery of the cavity are on the same plane and are connected to each other. The boss plane has a consistent width of 3-10mm, preferably 4-5mm. The hot melt adhesive film 4 is pasted on the boss 107. The membrane electrode covers the hot melt adhesive film and is bonded to the membrane electrode frame film to form a seal for the fluid inlet, channel and flow field.

[0037] To increase the strength of the boss and form a fluid channel, recesses 109 are punched on both sides of the boss (see...). Figure 2 , Figure 3 ) and 209 (see Figure 4 , Figure 5 The reinforcing ribs, also known as ribs, support the gas flow path at the inlet of the three-chamber system, opposite to the recess on the other electrode of the single cell. At the flow field inlet, the reinforcing rib protrudes at point 106 (see...). Figure 2 , Figure 3 ) and 206 (see Figure 4 , Figure 5 A hole is drilled in the part, and gas enters the flow field through the channel. Between the boss and the flow field, such as... Figure 2 Small protrusions 113 are arranged, which can be distributed in a dotted pattern. The back of each small protrusion is a recess, and a cooling chamber sealing gasket is embedded in the recess. See Figure 5 The sealing gasket has a raised section with a boss that is embedded in the electrode plate recess for fixation. Gas enters the flow field through the gas chamber inlet 102 and the channel hole 106, while isolation from the cooling chamber is achieved through the sealing gasket. Similarly, the flow field channel structure for gas entering the other electrode is the same as described above.

[0038] See Figure 2 , Figure 3The cooling chamber inlet 103 and channel 110 structure of the electrode plate of the present invention, relative to the electrode plate frame and the outer periphery of the flow field, 110 is a boss, the surface of the boss is bonded to the membrane electrode frame, and the gas cavity is isolated from the cooling chamber; the back is a cooling chamber, which is a groove, and the grooves of the anode and cathode plates overlap. The length of the reinforcing ribs entering the flow field direction at the inlet and outlet of the cooling chamber is different or the angle of the reinforcing ribs is different, forming a coolant channel for entering and exiting the bipolar plate.

[0039] The manufacturing process of the single cell of this invention is as follows:

[0040] The single-cell manufacturing process includes: positioning and attaching a die-cut hot melt adhesive film with release paper onto the surface of the electrode bosses (107, 207) using positioning holes (104, 204); heating the film to 80-100℃ and pressing it to adhere to the electrode bosses; peeling off the release paper after cooling; and then placing electrode 1, membrane electrode 3, and electrode 2 with hot melt adhesive film sequentially on a fixture with corresponding positioning holes. The hot pressing temperature is 130-135℃, the hot pressing time is 10s-120s, preferably 60-120s, and the corresponding hot pressing bonding surface pressure is 0.3-1kgf / cm². 2 Preferred concentration: 0.6-1 kg / cm³ 2 The cells are subjected to pressure holding and rapid cooling until the temperature drops below 60°C, at which point they are removed to obtain a single cell. Before pre-applying the hot melt adhesive film, if the dyne value of the electrode bonding surface is below 36, the bonding surface needs to be surface-treated. Treatment methods include laser or plasma bombardment or applying KH560 coupling agent as a primer. If the dyne value of the plastic frame bonding surface is below 36, the surface needs to be plasma-cleaned before bonding. If the dyne value is above 36, the bonding will be stronger.

[0041] The single-cell structure described in this invention is obtained by attaching a pre-formed sealing gasket or other process-formed sealing gasket to the cooling cavity side of the single cell. Figure 8 The single cells described in this invention are stacked and fastened together to obtain a fuel cell stack, as shown below. Figure 9 As can be seen, the gas entering the fuel cell stack is sealed and isolated by the sealing gasket and hot melt adhesive film.

[0042] Finally, it should be noted that the above specific embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit them; those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing specific embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the specific embodiments of the present invention.

Claims

1. A plate sealing structure for a fuel cell single cell, characterized in that, Includes electrode plates, membrane electrodes, sealing gaskets, and hot melt adhesive film; The electrode plates have protruding bosses around the three-cavity inlet and outlet and between the flow field edge and the electrode plate frame. The plane of the boss is higher than the ridge plane of the flow field, and the height is the thickness of the single-layer gas diffusion layer of the membrane electrode after assembly. Hot melt adhesive film is pasted on the surface of the boss of the anode and cathode plates. The membrane electrode is sandwiched between the anode and cathode plates, and the plastic frame of the membrane electrode is bonded by the hot melt adhesive film. The back side of the boss is a groove. An elastic sealing gasket is pasted in the groove of one of the electrode plates. The gas cavity of the single cell is sealed by the hot melt adhesive film, and the cooling cavity is sealed by the sealing gasket.

2. The electrode sealing structure of a fuel cell single cell according to claim 1, characterized in that, The three-cavity stamped edge ring is flipped up at the electrode plate entry point to form a gas channel and a cooling cavity channel, i.e., the protruding boss as described in claim 1. Reinforcing ribs are provided on both sides of this boss, supporting the bonding surface and limiting the sealing gasket. Holes are drilled on the reinforcing rib side of the protrusion in the cathode (and anode) gas inlet / outlet channel facing the flow field. Gas enters the flow field through these holes. Dot-shaped bosses are provided between the channel holes and the flow field. Sealing gaskets are attached to the back of these dot-shaped bosses. The surface of the sealing gasket is machined with protrusions that embed into the dot-shaped grooves of the electrode plate, ensuring the sealing gasket is not misaligned and is fixed, thus isolating the gas cavity and cooling cavity of the bipolar plate. The sealing gasket and the cooling cavity sealing gasket are integrally formed. The cooling cavity inlet / outlet channels utilize the shape or length difference of the corresponding groove reinforcing ribs of the cathode and anode plates to form intersections or extensions to guide the coolant flow into and out of the bipolar plate.

3. The electrode sealing structure of a fuel cell single cell according to claim 1, characterized in that, The thickness of the sealing gasket used in the single-cell sealing structure is specified as follows: Let the thickness of the electrode material be l, the thickness of the hot melt adhesive film be t, the thickness of the active part of the membrane electrode be δ, the thickness of the membrane electrode frame be τ, and the thickness of the cooling chamber sealing gasket be λ; the thickness of the electrode flow field region be α1, and the thickness of the other electrode is α. 2， After the fuel cell stack is assembled, the hot melt adhesive film compression rate is η, the active part of the membrane electrode compression rate is γ, and the sealing gasket compression rate is σ. δ*γ+α1+α2=2*l+2t *η+τ+λ*σ Right now λ*σ=[δ*γ+α1+α2]-[2*l+2t *η+τ].

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