A molten carbonate fuel cell sealing structure and its preparation method and application

Abstract

The present invention belongs to the technical field of fuel cell preparation, and specifically relates to a molten carbonate fuel cell sealing structure, a preparation method and an application thereof. The molten carbonate fuel cell sealing structure includes electrodes, punching plates and flow field plates that are stacked in sequence in order of diagonal size from large to small. The molten carbonate fuel cell sealing structure can have good sealing performance without adding an external seal, reducing the risk of leakage. At the same time, the molten carbonate fuel cell sealing structure is used in battery preparation, which can also reduce the spacing between electrodes and increase the battery volume power density; in addition, since no external seal is added, the weight of the molten carbonate fuel cell sealing structure can also be reduced, further improving the power density.

Description

Technical Field

[0001] The present invention belongs to the technical field of fuel cell preparation, and specifically relates to a molten carbonate fuel cell sealing structure and a preparation method and application thereof; more specifically, it relates to a molten carbonate fuel cell sealing structure and a preparation method thereof, a bipolar plate including the molten carbonate fuel cell sealing structure, and a molten carbonate fuel cell including the bipolar plate. Background Art

[0002] Molten carbonate fuel cell (MCFC) is a high-temperature fuel cell that operates at 650°C. It has the advantages of not requiring precious metals as catalysts, a wide fuel source, low noise, basically zero pollutant emissions, high power generation efficiency, and the ability to achieve cogeneration of heat and power. It is suitable for distributed power stations or fixed power stations in the hundreds of kilowatts to megawatts range, and has good development prospects.

[0003] The molten carbonate battery is a power generation device that directly converts the chemical energy of fuel into electrical energy. It is composed of components such as a porous ceramic cathode, a porous ceramic electrolyte membrane, a porous metal anode, a metal bipolar plate, and a carbonate electrolyte. The bipolar plate is a device for introducing and discharging anode and cathode gases and cooling media. It is also a conductor for battery series connection and electrical energy output. It is one of the key components of all fuel cells.

[0004] The bipolar plates of fuel cells should have good conductivity and flatness, reasonable airflow distribution, and be as light as possible. At the same time, when operating under molten salt corrosion conditions, the bipolar plates are required to be resistant to oxidation and reduction as well as electrolyte corrosion. Since molten fuel cells contain both hydrogen, air and carbon dioxide as gas media when working, it is necessary to prevent the reaction gases from crossing each other and leaking out.

[0005] In the prior art, Chinese patent document CN110380074A discloses a method for preparing a lightweight bipolar plate for a molten carbonate fuel cell, the bipolar plate includes an anode flow field plate, an anode frame plate, a center plate, a cathode frame plate and a cathode flow field plate, the anode frame plate, the center plate and the cathode frame plate are connected by laser welding technology, after welding, a sealing material layer is applied to the welding position, and finally the anode flow field plate and the cathode flow field plate are respectively placed in the through hole to obtain a lightweight bipolar plate for a molten carbonate fuel cell. However, the structure is assembled by an integrated structure, and a sealing material is placed to ensure the sealing, resulting in a high stack height, affecting the power density, and inconvenient assembly, and prone to gas leakage. In addition, there is also a sealing form of compression after placing the sealing material in the prior art. This seal is thicker, and there will be problems such as a high stack height, affecting the power density, and causing gas leakage. Summary of the invention

[0006] Therefore, the technical problem to be solved by the present invention is to overcome the defects of the molten carbonate battery bipolar structure in the prior art, such as high battery stack density and poor sealing due to the placement of sealing materials, thereby providing a molten carbonate fuel cell sealing structure and its preparation method and application.

[0007] To this end, the present invention provides the following technical solutions.

[0008] The invention provides a molten carbonate fuel cell sealing structure, which comprises an electrode, a punching plate and a flow field plate which are sequentially stacked and arranged in descending order of diagonal size.

[0009] Taking the diagonal line as a reference, the size ratio of the electrode, the punching plate and the flow field plate is 1:(0.95-0.85):(0.85-0.75).

[0010] The punching plate is provided with a plurality of circular holes for filling electrolyte;

[0011] The flow field plate is provided with a flow channel, and the flow channel is a serpentine flow channel;

[0012] The electrode comprises a cathode and / or an anode; the porosity of the cathode is not more than 75%; the porosity of the anode is not less than 55%.

[0013] The thickness of the punching plate is 0.6-1 mm; the thickness of the flow field plate is 1.5-2 mm;

[0014] The perforated plate is made of stainless steel; the flow field plate is made of stainless steel; and the electrode is a nickel electrode and / or a nickel oxide electrode.

[0015] The sealing structure of the molten carbonate fuel cell does not require any additional sealing member or sealing material; the electrode, the perforated plate and the flow field plate may be, but not limited to, rectangular or square; the electrode, the perforated plate and the flow field plate have the same contour.

[0016] The present invention provides a method for preparing the above-mentioned molten carbonate fuel cell sealing structure, comprising the following steps:

[0017] The electrodes, the punching plate and the flow field plate are sequentially stacked, assembled, and pressed at a pressure not exceeding 2.0 MPa to obtain a molten carbonate fuel cell sealing structure.

[0018] The pressing time is 5-10 minutes.

[0019] In addition, the present invention provides a bipolar plate, comprising the above-mentioned molten carbonate fuel cell sealing structure or the molten carbonate fuel cell sealing structure prepared by the above-mentioned method, and also comprising a central frame plate;

[0020] The thickness of the central frame plate is 3-4 mm;

[0021] At least one groove is provided in the central frame plate;

[0022] The molten carbonate fuel cell sealing structure is embedded in the groove, and the thickness of the molten carbonate fuel cell sealing structure is matched with the depth of the groove.

[0023] Taking the diagonal line as a reference, the size ratio of the central frame plate to the electrode is (1.1-1.2):1.

[0024] The bipolar plate is also provided with an air inlet and an air outlet, wherein the air inlet is provided at the junction of the flow field plate and the central frame plate, is communicated with the flow channel of the flow field plate, and is embedded in the central frame plate;

[0025] The air outlet and the air inlet are arranged at the two ends of the same side of the bipolar plate and are symmetrical about the center. The air outlet is arranged at the junction of the flow field plate and the central frame plate, is connected to the flow channel of the flow field plate, and is embedded in the central frame plate.

[0026] A first groove and a second groove are provided in the central frame plate; the first groove and the second groove are arranged on two sides of the central frame plate opposite to each other;

[0027] A first molten carbonate fuel cell sealing structure is embedded in the first groove, and the electrode in the first molten carbonate fuel cell sealing structure is a cathode;

[0028] A second molten carbonate fuel cell sealing structure is embedded in the second groove, and the electrode in the second molten carbonate fuel cell sealing structure is an anode.

[0029] Furthermore, the present invention provides a molten carbonate fuel cell, comprising at least one of the above-mentioned molten carbonate fuel cell sealing structures and / or at least one of the above-mentioned bipolar plates.

[0030] When the molten carbonate fuel cell is a single cell, it includes a bipolar plate;

[0031] When the molten carbonate fuel cell is an assembled cell stack, it includes a plurality of bipolar plates;

[0032] The molten carbonate fuel cell further includes a diaphragm, an air-side end plate, and a fuel gas-side end plate.

[0033] The technical solution of the present invention has the following advantages:

[0034] 1. The molten carbonate fuel cell sealing structure provided by the present invention comprises electrodes, perforated plates and flow field plates which are stacked in sequence in the order of diagonal size from large to small. The molten carbonate fuel cell sealing structure can have good sealing performance without adding an external seal, reducing the risk of leakage. At the same time, the molten carbonate fuel cell sealing structure can be used in battery preparation to reduce the spacing between electrodes and increase the battery volume power density. In addition, since no external seal is added, the weight of the sealing structure can be reduced, further improving the power density.

[0035] According to the diagonal size from large to small, the sealing structure of the molten carbonate fuel cell includes electrodes, perforated plates and flow field plates in sequence. The electrodes, perforated plates and flow field plates of the present invention are pressed together layer by layer, which can not only ensure flatness, but also reduce the risk of leakage and improve the sealing of the sealing structure. By adopting a step-by-step reduction method, the problem of poor sealing at the boundary of electrodes, flow field plates, etc. in the prior art due to the same size and contour can be avoided. In the present invention, the perforated plate is arranged between the flow field plate and the electrode to support the electrode and collect current.

[0036] 2. The molten carbonate fuel cell sealing structure provided by the present invention can improve the flatness of the stepped structure by limiting the size ratio of the electrode, the perforated plate and the flow field plate, thereby improving the sealing effect of the sealing structure and the efficiency of the fuel cell. If the size ratio between adjacent ones is too large, the perforated plate cannot support the flow field plate, the gas flow channel in the flow field plate is too short, the gas pressure passing through is high and the energy loss is high, resulting in low efficiency of the fuel cell. If the size ratio between adjacent ones is too small, the sealing effect will be reduced, similar to the aligned integrated structure.

[0037] 3. The preparation method of the molten carbonate fuel cell sealing structure provided by the present invention, when preparing the step-by-step decreasing sealing structure of the present invention, the assembly pressure can be reduced to 2.0MPa. Compared with the pressing pressure of 3-5MPa in the prior art, the step-by-step decreasing sealing structure of the present invention can reduce the assembly pressure while ensuring the sealing of the structure; compared with the traditional aligned integrated structure, the present invention has no constraints of the seal and is more convenient for placement and assembly alignment.

[0038] 4. The bipolar plate provided by the present invention comprises the molten carbonate fuel cell sealing structure and the central frame plate of the present invention, wherein at least one groove is provided in the central frame plate; the molten carbonate fuel cell sealing structure is embedded in the groove and the thickness of the molten carbonate fuel cell sealing structure matches the depth of the groove. The bipolar plate has good sealing performance without adding sealing parts or sealing materials, which reduces the risk of leakage. At the same time, the bipolar plate can be used in the preparation of molten carbonate fuel cells to shorten the distance between the anode and the cathode, increase the volume power density of the battery, and the battery performance can reach 100mA / cm2 @0.7V.

[0039] 5. The molten carbonate fuel cell provided by the present invention, including the molten carbonate fuel cell sealing structure and / or bipolar plate provided by the present invention, can make the battery have better sealing performance, prevent gas leakage, and also have better volume power density, thereby avoiding the problem of poor boundary sealing due to the same size of electrodes, flow field plates, center frame plates, etc. in the prior art, and at the same time, it can also overcome the problem of reduced battery volume power density due to the addition of seals or sealing materials in the prior art. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0041] Figure 1 is a schematic diagram of the sealing structure of a molten carbonate fuel cell in Example 1 of the present invention;

[0042] Figure 2 is a schematic diagram of the structure of the bipolar plate in Example 5 of the present invention;

[0043] Figure 3 This is the arrangement of the air inlet and outlet holes on the bipolar plate in Example 1 of the present invention;

[0044] Figure 4 is a schematic diagram of the assembly of a molten carbonate fuel cell in Experimental Example 1 of the present invention;

[0045] 1-electrode; 2-punching plate; 3-flow field plate; 4-center frame plate; 5-air side end plate; 6-first diaphragm, 7-first sealing structure, 8-second sealing structure, 9-second diaphragm, 10-fuel gas side end plate. DETAILED DESCRIPTION

[0046] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0047] In the description of the present invention, it should be noted that the terms “first” and “second” are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0048] In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0049] Example 1

[0050] This embodiment provides a molten carbonate fuel cell sealing structure, which is denoted by A. Figure 1 As shown, in the order of diagonal size from large to small, it includes an electrode 1, a punching plate 2 and a flow field plate 3 which are stacked in sequence; the punching plate 2 is arranged between the flow field plate 3 and the electrode 1 to support the electrode and collect current; the electrode 1, the punching plate 2 and the flow field plate 3 are rectangular.

[0051] Taking the diagonal as a reference, the size of the electrode is 819 mm, the size of the punching plate is 778 mm, and the size of the flow field plate is 696 mm; the thickness of the electrode is 0.8 mm, the thickness of the punching plate is 0.6 mm, and the thickness of the flow field plate is 2 mm.

[0052] The perforated plate is made of stainless steel and is provided with a number of circular holes for filling electrolytes. The porosity of the perforated plate is 60%; the flow field plate is made of stainless steel and is provided with flow channels. The flow channels are serpentine flow channels for filling electrolytes and transporting gases; the electrode is a cathode, which is a nickel oxide electrode with a porosity of 75%.

[0053] This embodiment also provides a method for preparing the above sealing structure, comprising the following steps:

[0054] The electrode, the punching plate and the flow field plate were stacked and assembled in sequence, and then pressed for 5 minutes at 2 MPa to obtain a sealing structure A.

[0055] In addition, this embodiment also provides a bipolar plate, denoted as bipolar plate A, including a sealing structure A and a center frame plate. A groove is provided in the center frame plate, and the sealing structure A is embedded in the groove. The depth of the groove is adapted to the thickness of the sealing structure A. Taking the diagonal as the reference, the size of the center frame plate is 900 mm; the material is stainless steel, and the depth of the groove of the center frame plate is 3.4 mm.

[0056] The bipolar plate is also provided with air inlet and outlet holes, such as Figure 3 As shown, the air inlet is arranged at the junction of the flow field plate and the center frame plate, is connected to the flow field plate flow channel, and is embedded in the center frame plate; the air outlet and the air inlet are arranged at the two ends of the same side of the bipolar plate relative to each other and are symmetrical about the center, and the air outlet is arranged at the junction of the flow field plate and the center frame plate, is connected to the flow field plate flow channel, and is embedded in the center frame plate.

[0057] Example 2

[0058] The present embodiment provides a molten carbonate fuel cell sealing structure, which is denoted as B and includes an electrode 1, a perforated plate 2 and a flow field plate 3 which are stacked in sequence; the perforated plate 2 is arranged between the flow field plate 3 and the electrode 1 to support the electrode and collect current; the electrode 1, the perforated plate 2 and the flow field plate 3 are rectangular.

[0059] Taking the diagonal as a reference, the size of the electrode is 819 mm, the size of the punching plate is 778 mm, and the size of the flow field plate is 696 mm; the thickness of the electrode is 0.8 mm, the thickness of the punching plate is 0.6 mm, and the thickness of the flow field plate is 2 mm.

[0060] The perforated plate is made of stainless steel and is provided with a plurality of circular holes for filling electrolyte. The porosity of the perforated plate is 60%. The flow field plate is made of stainless steel and is provided with a flow channel. The flow channel is a serpentine flow channel for filling electrolyte and transporting gas. The electrode is an anode, which is a nickel electrode with a porosity of 55%.

[0061] This embodiment also provides a method for preparing the above sealing structure, comprising the following steps:

[0062] The electrode, the punching plate and the flow field plate were stacked and assembled in sequence, and then pressed for 5 minutes at 2 MPa to obtain a sealing structure B.

[0063] In addition, this embodiment also provides a bipolar plate, denoted as bipolar plate B, including a sealing structure B and a central frame plate. A groove is provided in the central frame plate, and the sealing structure B is embedded in the groove. The depth of the groove is adapted to the thickness of the sealing structure B. Taking the diagonal as the reference, the size of the central frame plate is 900mm; the material is stainless steel, and the depth of the groove of the central frame plate is 3.4mmmm.

[0064] The bipolar plate is also provided with an air inlet and an air outlet. The air inlet is arranged at the junction of the flow field plate and the center frame plate, is connected to the flow field plate flow channel, and is embedded in the center frame plate; the air outlet and the air inlet are arranged at the two ends of the same side of the bipolar plate relative to each other and are symmetrical about the center, and the air outlet is arranged at the junction of the flow field plate and the center frame plate, is connected to the flow field plate flow channel, and is embedded in the center frame plate.

[0065] Example 3

[0066] The present embodiment provides a molten carbonate fuel cell sealing structure, which is denoted as C and includes an electrode 1, a perforated plate 2 and a flow field plate 3 which are stacked in sequence; the perforated plate 2 is arranged between the flow field plate 3 and the electrode 1 to support the electrode and collect current; the electrode 1, the perforated plate 2 and the flow field plate 3 are rectangular.

[0067] Taking the diagonal as a reference, the size of the electrode is 820 mm, the size of the punching plate is 697 mm, and the size of the flow field plate is 615 mm; the thickness of the electrode is 1 mm, the thickness of the punching plate is 1 mm, and the thickness of the flow field plate is 2 mm.

[0068] The perforated plate is made of stainless steel and is provided with a number of circular holes for filling electrolytes. The porosity of the perforated plate is 60%; the flow field plate is made of stainless steel and is provided with flow channels. The flow channels are serpentine flow channels for filling electrolytes and transporting gases; the electrode is a cathode, which is a nickel oxide electrode with a porosity of 75%.

[0069] This embodiment also provides a method for preparing the above sealing structure, comprising the following steps:

[0070] The electrode, the punching plate and the flow field plate were stacked and assembled in sequence, and then pressed for 10 minutes under 2 MPa to obtain a sealing structure C.

[0071] In addition, this embodiment also provides a bipolar plate, denoted as bipolar plate C, including a sealing structure C and a central frame plate. A groove is provided in the central frame plate, and the sealing structure C is embedded in the groove. The depth of the groove is adapted to the thickness of the sealing structure C. Taking the diagonal as the reference, the size of the central frame plate is 984m; the material is stainless steel, and the depth of the groove of the central frame plate is 4mm.

[0072] The bipolar plate is also provided with an air inlet and an air outlet. The air inlet is arranged at the junction of the flow field plate and the center frame plate, is connected to the flow field plate flow channel, and is embedded in the center frame plate; the air outlet and the air inlet are arranged at the two ends of the same side of the bipolar plate relative to each other and are symmetrical about the center, and the air outlet is arranged at the junction of the flow field plate and the center frame plate, is connected to the flow field plate flow channel, and is embedded in the center frame plate.

[0073] Example 4

[0074] The present embodiment provides a molten carbonate fuel cell sealing structure, which is denoted as D, and includes an electrode 1, a perforated plate 2 and a flow field plate 3 which are stacked in sequence; the perforated plate 2 is arranged between the flow field plate 3 and the electrode 1 to support the electrode and collect current; the electrode 1, the perforated plate 2 and the flow field plate 3 are rectangular.

[0075] Taking the diagonal as a reference, the size of the electrode is 820 mm, the size of the punching plate is 697 mm, and the size of the flow field plate is 615 mm; the thickness of the electrode is 1 mm, the thickness of the punching plate is 1 mm, and the thickness of the flow field plate is 2 mm.

[0076] The perforated plate is made of stainless steel and is provided with a plurality of circular holes for filling electrolyte. The porosity of the perforated plate is 60%. The flow field plate is made of stainless steel and is provided with a flow channel. The flow channel is a serpentine flow channel for filling electrolyte and transporting gas. The electrode is an anode, which is a nickel electrode with a porosity of 55%.

[0077] This embodiment also provides a method for preparing the above sealing structure, comprising the following steps:

[0078] The electrode, the punching plate and the flow field plate were stacked and assembled in sequence, and then pressed for 10 min at 2 MPa to obtain a sealing structure D.

[0079] The present embodiment also provides a bipolar plate, denoted as bipolar plate D, including a sealing structure D and a central frame plate. A groove is provided in the central frame plate, and the sealing structure D is embedded in the groove. The depth of the groove is adapted to the thickness of the sealing structure D. Taking the diagonal as a reference, the size of the central frame plate is 984 mm; the material is stainless steel, and the depth of the groove of the central frame plate is 4 mm.

[0080] The bipolar plate is also provided with an air inlet and an air outlet. The air inlet is arranged at the junction of the flow field plate and the center frame plate, is connected to the flow field plate flow channel, and is embedded in the center frame plate; the air outlet and the air inlet are arranged at the two ends of the same side of the bipolar plate relative to each other and are symmetrical about the center, and the air outlet is arranged at the junction of the flow field plate and the center frame plate, is connected to the flow field plate flow channel, and is embedded in the center frame plate.

[0081] Example 5

[0082] This embodiment provides a bipolar plate, denoted as bipolar plate E, including a sealing structure A, a sealing structure B and a central frame plate, such as Figure 2 As shown, a first groove and a second groove are provided in the central frame plate 4, and the first groove and the second groove are arranged on both sides of the central frame plate relatively; a sealing structure A is embedded in the first groove, and the thickness of the sealing structure A is adapted to the depth of the first groove; a sealing structure B is embedded in the second groove, and the thickness of the sealing structure B is adapted to the depth of the second groove; taking the diagonal line as the reference, the size of the central frame plate is 910mm; the material is stainless steel, and the depths of the two grooves of the central frame plate are both 3.4mm.

[0083] The bipolar plate is also provided with air inlet and outlet holes, such as Figure 3 As shown, the air inlet is arranged at the junction of the flow field plate and the center frame plate, is connected to the flow field plate flow channel, and is embedded in the center frame plate; the air outlet and the air inlet are arranged at the two ends of the same side of the bipolar plate relative to each other and are symmetrical about the center, and the air outlet is arranged at the junction of the flow field plate and the center frame plate, is connected to the flow field plate flow channel, and is embedded in the center frame plate.

[0084] Example 6

[0085] The present embodiment provides a bipolar plate, denoted as bipolar plate F, including a sealing structure C, a sealing structure D and a central frame plate, wherein a first groove and a second groove are provided in the central frame plate 4, and the first groove and the second groove are relatively arranged on both sides of the central frame plate; the sealing structure C is embedded in the first groove, and the thickness of the sealing structure C is adapted to the depth of the first groove; the sealing structure D is embedded in the second groove, and the thickness of the sealing structure D is adapted to the depth of the second groove; taking the diagonal line as a reference, the size of the central frame plate is 943 mm; the material is stainless steel, and the depth of the central frame plate groove is 4 mm.

[0086] The bipolar plate is also provided with an air inlet and an air outlet. The air inlet is arranged at the junction of the flow field plate and the center frame plate, is connected to the flow field plate flow channel, and is embedded in the center frame plate; the air outlet and the air inlet are arranged at the two ends of the same side of the bipolar plate relative to each other and are symmetrical about the center, and the air outlet is arranged at the junction of the flow field plate and the center frame plate, is connected to the flow field plate flow channel, and is embedded in the center frame plate.

[0087] Example 7

[0088] The present embodiment provides a molten carbonate fuel cell sealing structure, which is denoted by E and includes an electrode 1, a perforated plate 2 and a flow field plate 3 which are stacked in sequence in order of diagonal size from large to small; the perforated plate 2 is arranged between the flow field plate 3 and the electrode 1 to support the electrode and collect current; the electrode 1, the perforated plate 2 and the flow field plate 3 are rectangular.

[0089] Taking the diagonal as a reference, the size of the electrode is 819 mm, the size of the punching plate is 573 mm, and the size of the flow field plate is 491 mm; the thickness of the electrode is 0.8 mm, the thickness of the punching plate is 0.6 mm, and the thickness of the flow field plate is 2 mm.

[0090] The perforated plate is made of stainless steel and is provided with a number of circular holes for filling electrolytes. The porosity of the perforated plate is 60%; the flow field plate is made of stainless steel and is provided with flow channels. The flow channels are serpentine flow channels for filling electrolytes and transporting gases; the electrode is a cathode, which is a nickel oxide electrode with a porosity of 75%.

[0091] This embodiment also provides a method for preparing the above sealing structure, comprising the following steps:

[0092] The electrode, the punching plate and the flow field plate were sequentially stacked and assembled, and then pressed for 5 minutes at 2 MPa to obtain a sealing structure E.

[0093] Comparative Example 1

[0094] This comparative example provides a sealing structure, which is denoted as sealing structure F. The difference from Example 1 is that the electrode, the punching plate and the flow field plate are of the same size, with the diagonal as the reference, and the size is 819 mm. The rest is the same as Example 1.

[0095] Comparative Example 2

[0096] This comparative example provides a sealing structure, denoted as sealing structure G, which differs from Example 1 in that the electrode and the punching plate have the same size, 819 mm, the size of the flow field plate is the same as that of Example 1, and other parameters are the same as that of Example 1.

[0097] Experimental Example 1

[0098] This experimental example provides a molten carbonate fuel cell, such as Figure 4 As shown, it includes a bipolar plate E, a first diaphragm 6 and a second diaphragm 9, an electrolyte salt, an air side end plate 5 and a fuel gas side end plate 10; wherein the diaphragm is LiAlO 2 , the electrolyte salt is a Li / K carbonate composed of 62% lithium carbonate and 38% potassium carbonate by mass; the bipolar plate includes a first sealing structure 7 and a second sealing structure 8;

[0099] Electrolyte salt is filled into the bipolar plates and then Figure 4 Assemble in sequence, press for 5 minutes under 2MPa, pay attention to alignment and horizontal placement during the assembly process, and do not allow tilting and protrusions to occur, and then obtain a molten carbonate fuel cell. Among them, 4-center frame plate, 5-air side end plate, 6-first diaphragm, 7-first sealing structure, 8-second sealing structure, 9-second diaphragm, 10-fuel gas side end plate. In this experimental example, the first sealing structure is sealing structure A, and the second sealing structure is sealing structure B.

[0100] Experimental Example 2

[0101] This experimental example provides a molten carbonate fuel cell, which differs from Experimental Example 1 in that bipolar plate F replaces bipolar plate E, sealing structure C replaces sealing structure A, and sealing structure D replaces sealing structure B, and the rest is the same as Experimental Example 1.

[0102] Experimental Example 3

[0103] This experimental example provides a molten carbonate fuel cell, which is different from Experimental Example 1 in that the sealing structure E replaces the sealing structure A, and the rest is the same as Experimental Example 1.

[0104] Experimental Example 4

[0105] This experimental example provides a molten carbonate fuel cell, which is different from Experimental Example 1 in that the sealing structure F in Comparative Example 1 is used to replace the sealing structure A, and the rest is the same as Experimental Example 1.

[0106] Experimental Example 5

[0107] This experimental example provides a molten carbonate fuel cell, which is different from Experimental Example 1 in that the sealing structure A is replaced by the sealing structure G in Comparative Example 2, and the rest is the same as Experimental Example 1.

[0108] Test example

[0109] This test example provides a molten carbonate battery performance test and test results. The test method is as follows and the test results are shown in Table 1.

[0110] The test method for the volume power density of the molten carbonate battery is as follows: the specific operation is to start the heating program, reach thermal equilibrium at the highest operating temperature, run the fuel cell test program, pass hydrogen to the anode, and pass air and carbon dioxide to the cathode, open the fuel cell test program Faish, monitor the open circuit voltage to 1.2V without adding load, add external load, and test at a constant voltage of 0.7V. The corresponding test power results are shown in Table 1.

[0111] The test method for the sealing of molten carbonate batteries is as follows: test according to the gas leakage test method in GB / T 29838-2013 "Fuel Cell Module"; the specific operation is to run the fuel cell module to full load current and reach thermal equilibrium at the highest operating temperature, introduce anode gas into the anode cavity pipeline, maintain a stable pressure for 1 minute, and record the pressure change; apply a specified pressure to the cathode cavity, similar to the anode, and record the pressure change. The pressure change value is shown in Table 1.

[0112] Table 1 Molten carbonate battery performance test results

[0113] Example Cathode voltage drop Anode voltage drop Volume power density Experimental Example 1 30Pa 40Pa <![CDATA[0.77kw / m 3 ]]> Experimental Example 2 40Pa 50Pa <![CDATA[0.84kw / m 3 ]]> Experimental Example 3 70Pa 90Pa <![CDATA[0.71kw / m 3 ]]> Experimental Example 4 2KPa 2.5KPa <![CDATA[0.68kw / m 3 ]]> Experimental Example 5 1KPa 3KPa <![CDATA[0.7kw / m 3 ]]>

[0114] From the test results in Table 1, it can be known that the use of the molten carbonate fuel cell sealing structure of the present invention in the preparation of molten carbonate batteries can improve the sealing performance and volume power density of the battery. Compared with the solution in the prior art in which the electrodes, perforated plates and flow field plates are of the same size, the present invention can significantly improve the sealing effect and power density.

[0115] The present invention optimizes the ratio of electrodes, perforated plates and flow field plates, and the obtained molten carbonate fuel cell sealing structure can further improve the sealing effect and volume power density when used in the battery. For example, compared with Experimental Example 3, the sealing structure in Experimental Example 3 is provided by Example 7, and the sealing structure in Experimental Example 1 optimizes the ratio of electrodes, flow field plates and perforated plates, which can improve the sealing effect and volume power density.

[0116] Obviously, the above embodiments are merely examples for the purpose of clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived from these are still within the scope of protection of the invention.

Claims

1. A molten carbonate fuel cell sealing structure, characterized in that: In descending order of diagonal size, it includes electrodes, punching plates and flow field plates which are stacked in sequence; The molten carbonate fuel cell sealing structure is embedded in the groove in the central frame plate of the bipolar plate, and the thickness of the molten carbonate fuel cell sealing structure is adapted to the depth of the groove in the central frame plate of the bipolar plate.

2. The molten carbonate fuel cell sealing structure according to claim 1, characterized in that: Taking the diagonal line as a reference, the size ratio of the electrode, the punching plate and the flow field plate is 1:(0.95-0.85):(0.85-0.75).

3. The molten carbonate fuel cell sealing structure according to claim 1 or 2, characterized in that: The punching plate is provided with a plurality of circular holes for filling electrolyte; The flow field plate is provided with a flow channel, and the flow channel is a serpentine flow channel; The electrode comprises a cathode and / or an anode; the porosity of the cathode is not more than 75%; the porosity of the anode is not less than 55%.

4. The molten carbonate fuel cell sealing structure according to claim 1 or 2, characterized in that: The thickness of the punching plate is 0.6-1 mm; the thickness of the flow field plate is 1.5-2 mm; The perforated plate is made of stainless steel; the flow field plate is made of stainless steel; and the electrode is a nickel electrode and / or a nickel oxide electrode.

5. A method for preparing a molten carbonate fuel cell sealing structure according to any one of claims 1 to 4, characterized in that: The following steps are included: The electrodes, the punching plate and the flow field plate are sequentially stacked, assembled, and pressed at a pressure not exceeding 2.0 MPa to obtain a molten carbonate fuel cell sealing structure.

6. A bipolar plate, characterized in that: The molten carbonate fuel cell sealing structure prepared by the preparation method of claim 5 further comprises a central frame plate; The thickness of the central frame plate is 3-4 mm; At least one groove is provided in the central frame plate; The molten carbonate fuel cell sealing structure is embedded in the groove, and the thickness of the molten carbonate fuel cell sealing structure is matched with the depth of the groove.

7. The bipolar plate according to claim 6, characterized in that: Taking the diagonal line as a reference, the size ratio of the central frame plate to the electrode is (1.1-1.2):

1.

8. The bipolar plate according to claim 6 or 7, characterized in that: The bipolar plate is also provided with an air inlet and an air outlet, wherein the air inlet is provided at the junction of the flow field plate and the central frame plate, is communicated with the flow channel of the flow field plate, and is embedded in the central frame plate; The air outlet and the air inlet are arranged at the two ends of the same side of the bipolar plate and are symmetrical about the center. The air outlet is arranged at the junction of the flow field plate and the central frame plate, is connected to the flow field plate flow channel, and is embedded in the central frame plate.

9. The bipolar plate according to claim 6 or 7, characterized in that: A first groove and a second groove are provided in the central frame plate; the first groove and the second groove are arranged on two sides of the central frame plate opposite to each other; A first molten carbonate fuel cell sealing structure is embedded in the first groove, and the electrode in the first molten carbonate fuel cell sealing structure is a cathode; A second molten carbonate fuel cell sealing structure is embedded in the second groove, and the electrode in the second molten carbonate fuel cell sealing structure is an anode.

10. A molten carbonate fuel cell, characterized in that: It comprises at least one molten carbonate fuel cell sealing structure according to any one of claims 1 to 4 and / or at least one bipolar plate according to any one of claims 6 to 9.

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