Porous electrode-bipolar plate integrated structure, preparation method thereof and flow battery

Abstract

The invention specifically discloses a porous electrode-bipolar plate integrated structure, a preparation method thereof and a flow battery, and the method comprises the following steps: S100, adding resin, graphite and carbon nanotubes into an ethanol solution to obtain a first mixed material; s200, the first mixed material is dried and smashed, first powder is obtained, then a pore forming agent and the first powder are evenly mixed in a dry mode, and a second mixed material is obtained; s300, pre-pressing the second mixed material to obtain a porous electrode material; s400, uniformly dry-mixing a resin material and a graphite material to obtain second powder, then paving a second powder layer on the porous electrode material, and pre-pressing again to obtain a porous electrode-bipolar plate integrated material; and S500, carrying out post-treatment on the porous electrode-bipolar plate integrated material to obtain a porous electrode-bipolar plate integrated structure. According to the invention, the contact resistance between the electrode and the bipolar plate is reduced, so that the energy efficiency is improved.

Description

Technical Field

[0001] The present application belongs to the technical field of bipolar plates for liquid flow batteries, and in particular, relates to a porous electrode-bipolar plate integrated structure and a preparation method thereof, and a liquid flow battery. Background Art

[0002] Liquid flow energy storage battery is a large-scale electrochemical energy storage technology. Compared with other energy storage technologies, it has the advantages of high energy conversion efficiency, flexible system design, large storage capacity, free site selection, deep discharge, safety and environmental protection, and low maintenance cost. It is widely used in wind power, solar energy and other renewable energy power generation and storage, emergency power supply systems, backup power stations and power system peak shaving and valley filling. Bipolar plate is one of the key components of liquid flow battery. It mainly plays the role of separating positive and negative electrolytes, conducting current and supporting electrodes, while electrodes are the place where electrochemical reactions occur in electrolytes. When existing liquid flow batteries are assembled into battery stacks, they often press the bipolar plates and electrodes together by pressure, which will produce a large contact resistance, thereby reducing the performance and efficiency of the battery. Summary of the invention

[0003] This application is made in view of the above technical problems and aims to provide a porous electrode-bipolar plate integrated structure with low contact resistance and a preparation method thereof, and a liquid flow battery.

[0004] In order to solve the above technical problems, the present application provides a method for preparing a porous electrode-bipolar plate integrated structure, the method comprising the following steps:

[0005] S100, sequentially adding a resin material, a pretreated graphite material, and a pretreated carbon nanotube material into a solvent and mixing them evenly to obtain a first mixed material, wherein the mass proportion of each component in the first mixed material is: 5-20% of the resin material, 75-94% of the graphite material, and 1-5% of the carbon nanotube material, and the solvent is one of water, ethanol solution, or methanol solution;

[0006] S200, drying the first mixed material and crushing it into powder to obtain a first powder, and then dry-mixing the pore-forming agent in a second preset ratio with the first powder to obtain a second mixed material;

[0007] S300, pre-pressing the second mixed material to obtain a porous electrode material;

[0008] S400, dry-mixing the resin material and the pretreated graphite material in a third preset ratio to obtain a second powder, and then spreading a layer of the second powder on the obtained porous electrode material and pre-pressing again to obtain a porous electrode-bipolar plate integrated material;

[0009] S500, the porous electrode-bipolar plate integrated material is subjected to hot pressing, curing, acid / alkali soaking, cleaning and drying treatment to obtain a porous electrode-bipolar plate integrated structure.

[0010] In the present application, the electrode is first pre-pressed into a porous structure, and then the bipolar plate is pre-pressed on the porous electrode to obtain a porous electrode-bipolar plate integrated structure. Due to the compression molding of the porous electrode and the bipolar plate, the conductive agent between the electrode and the bipolar plate can be directly contacted and conducted, thereby greatly reducing the contact resistance between the porous electrode and the bipolar plate; at the same time, the porous structure of the electrode can also effectively increase the number of reactive sites, thereby reducing polarization, improving energy efficiency, and increasing energy utilization. Therefore, the porous electrode-bipolar plate integrated structure prepared by the preparation method provided in the present application is applied to a liquid flow battery, which can effectively improve the battery performance.

[0011] In some embodiments, the resin includes at least one of polytetrafluoroethylene, polyimide resin, vinyl ester resin, polybenzoxazine resin, urea-formaldehyde resin, polyurethane resin, fluorinated ethylene-propylene, polypropylene, and epoxy resin, and the graphite includes at least one of flake graphite, expanded graphite, carbon fiber, graphene nanosheets, high conductive carbon black, and chopped carbon fiber.

[0012] In some embodiments, in step S100, the pretreatment of the graphite material specifically refers to: performing coupling treatment on the selected graphite.

[0013] In some embodiments, in step S100, the pretreatment of the carbon nanotube material specifically refers to: shearing and dispersing the selected carbon nanotubes so that the carbon nanotube material reaches a preset fineness and is evenly mixed.

[0014] In some embodiments, the step S200 is specifically as follows: placing the first mixed material in an oven at a temperature of 50-90°C and drying it for 3-12 hours, until the first mixed material is dried, and then using a crushing device to crush the first mixed material into powder to obtain a first powder, and dry-mixing a second preset ratio of a pore-forming agent with the first powder to obtain a second mixed material, wherein the second preset ratio is 1:1-5, the pore-forming agent includes at least one of an inorganic pore-forming agent and an organic pore-forming agent, the particle size of the pore-forming agent is 1-200 μm, and the purity is ≥99.5%, the inorganic pore-forming agent includes calcium carbonate, ammonium carbonate, ammonium bicarbonate, ammonium chloride, zinc acetate, polymer microspheres, and silica, and the organic pore-forming agent includes starch, polymethacrylate, methyl methacrylate, and nylon fiber.

[0015] In some embodiments, the step S300 is specifically as follows: pre-pressing the second mixed material for 30-100 seconds under a pre-pressing pressure of 30-90 MPa to obtain a porous electrode material.

[0016] In some embodiments, the step S400 is specifically as follows: coupling the graphite material, and dry-mixing the coupling-treated graphite material and the resin material in a third preset ratio to obtain a second powder; then spreading a layer of the second powder layer on the obtained porous electrode material and pre-pressing it again to obtain a porous electrode-bipolar plate integrated material, wherein the third preset ratio is 1:5-10, the thickness of the second powder layer is 2-10mm, the pre-pressing pressure is 30-90MPa, and the pre-pressing time is 30-100s.

[0017] In some embodiments, the step S500 is specifically as follows: hot pressing the obtained porous electrode-bipolar plate integrated material, the hot pressing temperature is 100-200°C, the hot pressing pressure is 30-90MPa, and the hot pressing time is 30-300s; then the hot pressed porous electrode-bipolar plate integrated material is cured, the curing temperature is 100-300°C, and the curing time is 1-3h; finally, the cured porous electrode-bipolar plate integrated material is soaked in acid / alkali to remove the pore-forming agent, and the acid and alkali used include hydrochloric acid, sodium hydroxide, sulfuric acid, nitric acid, potassium hydroxide, calcium hydroxide, etc. After washing with deionized water for multiple times and drying, the porous electrode-bipolar plate integrated structure can be obtained.

[0018] The present application also provides a porous electrode-bipolar plate integrated structure, and the porous electrode-bipolar plate integrated structure is prepared by the above-mentioned method for preparing the porous electrode-bipolar plate integrated structure.

[0019] The present application also provides a liquid flow battery, which comprises a porous electrode-bipolar plate integrated structure prepared by the preparation method of the porous electrode-bipolar plate integrated structure described above or includes the porous electrode-bipolar plate integrated structure described above.

[0020] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become apparent from the description below, or will be learned through the practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] 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.

[0022] Figure 1 is a flow chart of a method for preparing a porous electrode-bipolar plate integrated structure in some embodiments of the present application,

[0023] Figure 2 It is an electron microscope scanning image of the integrated structure of the porous electrode-bipolar plate in some embodiments of the present application. DETAILED DESCRIPTION

[0024] "Scope" disclosed in the present application is limited in the form of lower limit and upper limit, and a given range is limited by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of a special range. The scope limited in this way can be including end values ​​or not including end values, and can be arbitrarily combined, that is, any lower limit can be combined with any upper limit to form a scope. For example, if the scope of 60-120 and 80-110 is listed for a specific parameter, it is understood that the scope of 60-110 and 80-120 is also expected. In addition, if the minimum range values ​​1 and 2 are listed, and if the maximum range values ​​3, 4 and 5 are listed, the following scope can be all expected: 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5. In the present application, unless otherwise specified, the numerical range "ab" represents the abbreviation of any real number combination between a and b, wherein a and b are real numbers. For example, the numerical range "0-5" means that all real numbers between "0-5" are listed in this document, and "0-5" is just an abbreviation of these numerical combinations. In addition, when a parameter is expressed as an integer ≥ 2, it is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0025] If there is no special explanation, the "include" and "comprising" mentioned in this application are open-ended or closed-ended. For example, the "include" and "comprising" may mean that other components not listed may also be included or only the listed components may be included or only the listed components may be included.

[0026] If not specifically stated, in this application, the term "or" is inclusive. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, any of the following conditions satisfies the condition "A or B": A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0027] refer to Figure 1 As shown, the embodiment of the present application provides a method for preparing a porous electrode-bipolar plate integrated structure, the method comprising the following steps:

[0028] S100, sequentially adding a resin material, a pretreated graphite material, and a pretreated carbon nanotube material into a solvent and mixing them evenly to obtain a first mixed material, wherein the mass proportion of each component in the first mixed material is: 5-20% of the resin material, 75-94% of the graphite material, and 1-5% of the carbon nanotube material, and the solvent is one of water, ethanol solution, or methanol solution;

[0029] In this step, the resin includes at least one of polytetrafluoroethylene, polyimide resin, vinyl ester resin, polybenzoxazine resin, urea-formaldehyde resin, polyurethane resin, fluorinated ethylene-propylene, polypropylene, and epoxy resin, and the graphite includes at least one of flake graphite, expanded graphite, carbon fiber, graphene nanosheets, high conductive carbon black, and chopped carbon fiber.

[0030] Specifically, firstly, the selected graphite is subjected to coupling treatment, the selected carbon nanotubes are sheared and dispersed to make the carbon nanotube material reach a preset fineness and be evenly mixed, and then each component is sequentially added into a solvent and wet-mixed evenly.

[0031] S200, drying the first mixed material and crushing it into powder to obtain a first powder, and then dry-mixing the pore-forming agent in a second preset ratio with the first powder to obtain a second mixed material;

[0032] The step is specifically as follows: placing the first mixed material in an oven at a temperature of 50-90° C. and drying it for 3-12 hours, until the first mixed material is dried, then using a crushing device to crush the first mixed material into powder to obtain a first powder, and dry-mixing a second preset ratio of pore-forming agent with the first powder to obtain a second mixed material, wherein the second preset ratio is 1:1-5, the pore-forming agent includes at least one of an inorganic pore-forming agent and an organic pore-forming agent, the particle size of the pore-forming agent is 1-200 μm, and the purity is ≥99.5%, the inorganic pore-forming agent includes calcium carbonate, ammonium carbonate, ammonium bicarbonate, ammonium chloride, zinc acetate, and polymer microspheres, and the organic pore-forming agent includes starch, polymethacrylate, methyl methacrylate, and nylon fiber.

[0033] S300, pre-pressing the second mixed material to obtain a porous electrode material; specifically, pre-pressing the second mixed material for 30-100 seconds under a pre-pressing pressure of 30-90 MPa to obtain a porous electrode material;

[0034] In some embodiments, the pre-compression pressure can be any value between 30-90 MPa. For example, it can be 30 MPa, 35 MPa, 40 MPa, 45 MPa, 50 MPa, 55 MPa, 60 MPa, 65 MPa, 70 MPa, 75 MPa, 80 MPa, 85 MPa, 90 MPa, etc.

[0035] In some embodiments, the pre-pressing time may be any value between 30-100 s, for example, 30 s, 40 s, 50 s, 60 s, 70 s, 80 s, 90 s, 100 s, etc.

[0036] S400, dry-mixing the resin material and the pretreated graphite material in a third preset ratio to obtain a second powder, and then spreading a layer of the second powder on the obtained porous electrode material and pre-pressing again to obtain a porous electrode-bipolar plate integrated material;

[0037] This step is specifically as follows: coupling treatment is performed on the graphite material, and the graphite material after the coupling treatment and the resin material are dry-mixed evenly at a third preset ratio to obtain a second powder; and then a layer of the second powder is spread on the obtained porous electrode material and then pre-pressed again to obtain a porous electrode-bipolar plate integrated material, wherein the third preset ratio is 1:5-10, the pre-pressing pressure is 30-90MPa, and the pre-pressing time is 30-100s;

[0038] In some embodiments, the thickness of the second powder layer may be any value between 2-10 mm, for example, 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, 10 mm, etc.;

[0039] In some embodiments, the third preset ratio may be any value between 1:5-10, and illustratively, may be 1:5, 1:6, 1:7, 1:8, 1:9, 1:10, etc.;

[0040] In some embodiments, the re-prepressing pressure may be any value in the range of 30-90 MPa, for example, 30 MPa, 35 MPa, 40 MPa, 45 MPa, 50 MPa, 55 MPa, 60 MPa, 65 MPa, 70 MPa, 75 MPa, 80 MPa, 85 MPa, 90 MPa, etc.;

[0041] In some embodiments, the re-prepressing time may be any value between 30-100 s, for example, 30 s, 40 s, 50 s, 60 s, 70 s, 80 s, 90 s, 100 s, etc.

[0042] S500, the porous electrode-bipolar plate integrated material is subjected to hot pressing, curing, acid / alkali soaking, cleaning and drying treatment to obtain a porous electrode-bipolar plate integrated structure.

[0043] The step is specifically as follows: hot pressing the obtained porous electrode-bipolar plate integrated material, the hot pressing temperature is 100-200°C, the hot pressing pressure is 30-90MPa, and the hot pressing time is 30-300s; then curing the hot pressed porous electrode-bipolar plate integrated material, the curing temperature is 100-300°C, and the curing time is 1-3h; finally, the cured porous electrode-bipolar plate integrated material is pickled to remove the pore-forming agent, and washed with deionized water for multiple times and then dried to obtain a porous electrode-bipolar plate integrated structure;

[0044] In some embodiments, the hot pressing temperature can be any value between 100-200°C, for example, it can be 100°C, 110°C, 120°C, 130°C, 140°C, 150°C, 160°C, 170°C, 180°C, 190°C, 200°C, etc.

[0045] In some embodiments, the hot pressing pressure can be any value between 30 and 90 MPa. For example, it can be 30 MPa, 35 MPa, 40 MPa, 45 MPa, 50 MPa, 55 MPa, 60 MPa, 65 MPa, 70 MPa, 75 MPa, 80 MPa, 85 MPa, 90 MPa, etc.

[0046] In some embodiments, the hot pressing time can be any value between 30-300s, for example, 30s, 40s, 50s, 60s, 70s, 80s, 90s, 100s, 110s, 120s, 130s, 140s, 150s, 160s, 170s, 180s, 190s, 200s, 210s, 220s, 230s, 240s, 250s, 260s, 270s, 280s, 290s, 300s, etc.

[0047] In some embodiments, the curing temperature may be any value between 100-300°C, illustratively, 100°C, 110°C, 120°C, 130°C, 140°C, 150°C, 160°C, 170°C, 180°C, 190°C, 200°C, 210°C, 220°C, 230°C, 240°C, 250°C, 260°C, 70°C, 280°C, 290°C, 300°C, etc.;

[0048] In some embodiments, the curing time may be any value between 1-3 hours, and for example, may be 1 hour, 1.5 hours, 2 hours, 2.5 hours, 3 hours, etc.

[0049] In the above embodiment, the electrode is first pre-pressed into a porous structure, and then the bipolar plate is pre-pressed on the porous electrode to obtain a porous electrode-bipolar plate integrated structure. Compared with the existing electrode-bipolar plate integrated structure obtained by gluing, in the porous electrode-bipolar plate integrated structure in this embodiment, the porous electrode and the bipolar plate are molded, so that the conductive agent between the electrode and the bipolar plate can be directly contacted and connected, reducing an interface contact resistance, thereby greatly reducing the contact resistance between the electrode and the bipolar plate; at the same time, the porous structure of the electrode increases the number of reactive active sites, reduces polarization, and thus improves energy efficiency and increases energy utilization. Therefore, the porous electrode-bipolar plate integrated structure prepared by the preparation method provided in this application is applied to liquid flow batteries, which can effectively improve battery performance.

[0050] The embodiment of the present application also provides a porous electrode-bipolar plate integrated structure, which is applied to a liquid flow battery and is prepared by the above-mentioned method for preparing the porous electrode-bipolar plate integrated structure.

[0051] Based on the description of the beneficial technical effects of the above-mentioned method for preparing the porous electrode-bipolar plate integrated structure, the porous electrode-bipolar plate integrated structure prepared by this method has the same beneficial technical effects, which will not be repeated here.

[0052] An embodiment of the present application also provides a liquid flow battery, which includes a porous electrode-bipolar plate integrated structure prepared by the preparation method of the porous electrode-bipolar plate integrated structure described above or includes the porous electrode-bipolar plate integrated structure described above.

[0053] Based on the preparation method of the above-mentioned porous electrode-bipolar plate integrated structure and the description of the beneficial technical effects of the above-mentioned porous electrode-bipolar plate integrated structure, the porous electrode-bipolar plate integrated structure has the same beneficial technical effects when applied to liquid flow batteries, which will not be repeated here.

[0054] The following examples describe the disclosure of the present application in more detail, and these examples are merely illustrative, as it will be apparent to those skilled in the art that various modifications and variations within the scope of the disclosure of the present application are possible. Unless otherwise stated, all reagents and raw materials used in the examples are commercially available or synthesized according to conventional methods, and the instruments and equipment used in the examples are commercially available.

[0055] Example 1

[0056] (1) adding a resin material, a pretreated graphite material, and a pretreated carbon nanotube material in a mass ratio of 25:72:3 to an ethanol solution in sequence and mixing them evenly to obtain a first mixed material;

[0057] (2) drying the first mixed material and crushing it into powder to obtain a first powder, and then dry-mixing the pore-forming agent with the first powder in a ratio of 3:4 to obtain a second mixed material;

[0058] (3) pre-pressing the second mixed material to obtain a porous electrode material;

[0059] (4) dry-mixing the resin material and the pretreated graphite material in a ratio of 1:3 to obtain a second powder, and then spreading a layer of the second powder on the obtained porous electrode material and pre-pressing again to obtain a porous electrode-bipolar plate integrated material, wherein the thickness of the second powder layer is 6 mm;

[0060] (5) The porous electrode-bipolar plate integrated material is hot pressed at a temperature of 30 MPa, 115° C., and 300 s, followed by curing. After curing, the material is pickled, cleaned, and dried to obtain a porous electrode-bipolar plate integrated structure.

[0061] Example 2

[0062] (1) adding a resin material, a pretreated graphite material, and a pretreated carbon nanotube material in a ratio of 25:72:3 to an ethanol solution in sequence and mixing them evenly to obtain a first mixed material;

[0063] (2) drying the first mixed material and crushing it into powder to obtain a first powder, and then dry-mixing the pore-forming agent and the first powder in a ratio of 1:1 to obtain a second mixed material;

[0064] (3) pre-pressing the second mixed material to obtain a porous electrode material;

[0065] (4) dry-mixing the resin material and the pretreated graphite material in a ratio of 1:3 to obtain a second powder, and then spreading a layer of the second powder on the obtained porous electrode material and pre-pressing again to obtain a porous electrode-bipolar plate integrated material, wherein the thickness of the second powder layer is 6 mm;

[0066] (5) The porous electrode-bipolar plate integrated material is hot pressed at a temperature of 30 MPa, 115° C., and 300 s, followed by curing. After curing, the material is pickled, cleaned, and dried to obtain a porous electrode-bipolar plate integrated structure.

[0067] Example 3

[0068] (1) adding a resin material, a pretreated graphite material, and a pretreated carbon nanotube material in a ratio of 25:72:3 to an ethanol solution in sequence and mixing them evenly to obtain a first mixed material;

[0069] (2) drying the first mixed material and crushing it into powder to obtain a first powder, and then dry-mixing the pore-forming agent with the first powder in a ratio of 4:3 to obtain a second mixed material;

[0070] (3) pre-pressing the second mixed material to obtain a porous electrode material;

[0071] (4) dry-mixing the pretreated graphite material and the resin material in a ratio of 1:3 to obtain a second powder, and then spreading a layer of the second powder on the obtained porous electrode material and pre-pressing again to obtain a porous electrode-bipolar plate integrated material, wherein the thickness of the second powder layer is 6 mm;

[0072] (5) The porous electrode-bipolar plate integrated material is hot pressed at a temperature of 30 MPa, 115° C., and 300 s, followed by curing. After curing, the material is pickled, cleaned, and dried to obtain a porous electrode-bipolar plate integrated structure.

[0073] Comparative Example 1

[0074] The difference between Comparative Example 1 and Example 1 is that, in step (4), the pre-pressed porous electrode is hot pressed, and the second powder layer is hot pressed after pre-pressing to obtain the hot-pressed porous electrode and bipolar plate, respectively, and then the porous electrode and the bipolar plate are bonded together with conductive glue to obtain a porous electrode-bipolar plate integrated material, and the other processes are the same as Example 1.

[0075] Comparative Example 2

[0076] The difference between Comparative Example 2 and Example 2 is that, in step (4), the pre-pressed porous electrode is hot pressed, and the second powder layer is hot pressed after pre-pressing to obtain the hot-pressed porous electrode and bipolar plate, respectively, and then the porous electrode and the bipolar plate are bonded together with conductive glue to obtain a porous electrode-bipolar plate integrated material, and the other processes are the same as Example 2.

[0077] Comparative Example 3

[0078] The difference between Comparative Example 3 and Example 3 is that, in step (4), the pre-pressed porous electrode is hot pressed, and the second powder layer is hot pressed after pre-pressing to obtain the hot-pressed porous electrode and bipolar plate, respectively, and then the porous electrode and the bipolar plate are bonded together with conductive glue to obtain a porous electrode-bipolar plate integrated material, and the other processes are the same as Example 3.

[0079] The porous electrode-bipolar plate integrated structure obtained in Examples 1-3 and Comparative Examples 1-3 was subjected to contact resistance test analysis, the test pressure was 0.4 MPa, and the test results are shown in Table 1. At the same time, the porous electrode-bipolar plate integrated structure obtained in Example 1 was subjected to electron microscope scanning, specifically as shown in Table 1. Figure 2 shown.

[0080] Table 1 Contact resistance test results of the products obtained from Examples 1-3 and Comparative Examples 1-3

[0081] Contact resistance (mΩ.cm2) Example 1 49.36 Example 2 49.12 Example 3 49.51 Comparative Example 1 59.33 Comparative Example 2 60.52 Comparative Example 3 61.53

[0082] It can be seen from Table 1 that the contact resistance of the porous electrode-bipolar plate integrated structure obtained in Examples 1-3 is all within 50 mΩ.cm 2 The contact resistance of the porous electrode-bipolar plate integrated structure obtained in Comparative Examples 1-3 is 59 mΩ.cm 2 As described above, compared with the porous electrode material and the bipolar plate material in Comparative Examples 1-3, which are bonded with conductive adhesive to form an integrated structure, the porous electrode material and the bipolar plate in Examples 1-3 are compression molded, so that the conductive agent between the porous electrode and the bipolar plate can be directly contacted and conducted, thereby reducing an interface contact resistance. Therefore, Examples 1-3 can significantly reduce the contact resistance between the porous electrode and the bipolar plate.

[0083] from Figure 2 It can also be seen that the bipolar plate and the porous electrode in the porous electrode-bipolar plate integrated structure prepared by the present application are tightly fitted together. This electrode-bipolar plate integrated structure can reduce the contact resistance, thereby reducing the internal resistance of the entire battery. The bipolar plate structure is dense. At the same time, since one side of the electrode is porous and the pores are connected, more reaction sites can be provided for the active substance, that is, the number of reactive sites is increased, polarization is reduced, and thus energy efficiency and power density can be improved. Therefore, the porous electrode-bipolar plate integrated structure prepared by the preparation method provided in the present application is applied to a liquid flow battery, which can improve energy efficiency and increase energy utilization.

[0084] The above is a detailed introduction to a porous electrode-bipolar plate integrated structure and its preparation method, and a liquid flow battery provided by the present application. This article uses specific examples to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the core idea of ​​the present application. It should be pointed out that for ordinary technicians in this technical field, without departing from the principles of the present application, several improvements and modifications can be made to the present application, and these improvements and modifications also fall within the scope of protection of the claims of the present application.

Claims

1. A method for preparing a porous electrode-bipolar plate integrated structure, characterized in that: The method comprises the following steps: S100, sequentially adding a resin material, a pretreated graphite material, and a pretreated carbon nanotube material into a solvent and mixing them evenly to obtain a first mixed material, wherein the mass proportion of each component in the first mixed material is: 5-20% of the resin material, 75-94% of the graphite material, and 1-5% of the carbon nanotube material, and the solvent is one of water, ethanol solution, or methanol solution; S200, drying the first mixed material and crushing it into powder to obtain a first powder, and then dry-mixing the pore-forming agent in a second preset ratio with the first powder to obtain a second mixed material; S300, pre-pressing the second mixed material to obtain a porous electrode material; S400, dry-mixing the resin material and the pretreated graphite material in a third preset ratio to obtain a second powder, and then spreading a layer of the second powder on the obtained porous electrode material and pre-pressing again to obtain a porous electrode-bipolar plate integrated material; S500, the porous electrode-bipolar plate integrated material is subjected to hot pressing, curing, acid / alkali soaking, cleaning and drying treatment to obtain a porous electrode-bipolar plate integrated structure.

2. The method for preparing the porous electrode-bipolar plate integrated structure according to claim 1, characterized in that: The resin includes at least one of polytetrafluoroethylene, polyimide resin, vinyl ester resin, polybenzoxazine resin, urea-formaldehyde resin, polyurethane resin, fluorinated ethylene-propylene, polypropylene, and epoxy resin, and the graphite includes at least one of flake graphite, expanded graphite, carbon fiber, graphene nanosheets, high conductive carbon black, and chopped carbon fiber.

3. The method for preparing the porous electrode-bipolar plate integrated structure according to claim 2, characterized in that: In the step S100, the pretreatment of the graphite material specifically refers to: performing coupling treatment on the selected graphite.

4. The method for preparing the porous electrode-bipolar plate integrated structure according to claim 3, characterized in that: In the step S100, the pretreatment of the carbon nanotube material specifically refers to: shearing and dispersing the selected carbon nanotubes so that the carbon nanotube material reaches a preset fineness and is evenly mixed.

5. The method for preparing the porous electrode-bipolar plate integrated structure according to claim 4, characterized in that: The step S200 is specifically as follows: placing the first mixed material in an oven at a temperature of 50-90° C. and drying it for 3-12 hours, until the first mixed material is dried, and then crushing the first mixed material into powder using a crushing device to obtain a first powder, and dry-mixing a second preset ratio of pore-forming agent with the first powder to obtain a second mixed material, wherein the second preset ratio is 1:1-5, the pore-forming agent includes at least one of an inorganic pore-forming agent and an organic pore-forming agent, the particle size of the pore-forming agent is 1-200 μm, and the purity is ≥99.5%, the inorganic pore-forming agent includes calcium carbonate, ammonium carbonate, ammonium bicarbonate, ammonium chloride, zinc acetate, polymer microspheres, and silicon dioxide, and the organic pore-forming agent includes starch, polymethacrylate, methyl methacrylate, and nylon fiber.

6. The method for preparing the porous electrode-bipolar plate integrated structure according to claim 5, characterized in that: The step S300 specifically includes: pre-pressing the second mixed material for 30-100 seconds under a pre-pressing pressure of 30-90 MPa to obtain a porous electrode material.

7. The method for preparing the porous electrode-bipolar plate integrated structure according to claim 6, characterized in that: The step S400 is specifically as follows: coupling treatment is performed on the graphite material, and the graphite material after the coupling treatment and the resin material are dry-mixed evenly in a third preset ratio to obtain a second powder; then a layer of the second powder layer is spread on the obtained porous electrode material and pre-pressed again to obtain a porous electrode-bipolar plate integrated material, wherein the third preset ratio is 1:5-10, the thickness of the second powder layer is 2-10mm, the pre-pressing pressure is 30-90MPa, and the pre-pressing time is 30-100s.

8. The method for preparing the porous electrode-bipolar plate integrated structure according to claim 7, characterized in that: The step S500 is specifically as follows: hot pressing the obtained porous electrode-bipolar plate integrated material, the hot pressing temperature is 100-200°C, the hot pressing pressure is 30-90MPa, and the hot pressing time is 30-300s; then curing the hot pressed porous electrode-bipolar plate integrated material, the curing temperature is 100-300°C, and the curing time is 1-3h; finally, the cured porous electrode-bipolar plate integrated material is soaked in acid / alkali to remove the pore-forming agent, and is washed with deionized water for multiple times and then dried to obtain a porous electrode-bipolar plate integrated structure.

9. A porous electrode-bipolar plate integrated structure, characterized in that: The porous electrode-bipolar plate integrated structure is applied to a liquid flow battery, and is prepared by the method for preparing the porous electrode-bipolar plate integrated structure according to any one of claims 1 to 8.

10. A liquid flow battery, characterized in that: The liquid flow battery comprises a porous electrode-bipolar plate integrated structure prepared by the method for preparing a porous electrode-bipolar plate integrated structure according to any one of claims 1 to 8 or comprises the porous electrode-bipolar plate integrated structure according to claim 9.

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