Bipolar plate of flow battery, preparation method of bipolar plate and flow battery

Abstract

The invention provides a flow battery bipolar plate, a preparation method thereof and a flow battery. The preparation method of the flow battery bipolar plate comprises the following steps: obtaining the polyvinylidene fluoride emulsion and the graphite worm; carrying out fluidization treatment on the graphite worms; carrying out spray coating operation on the graphite worms subjected to fluidization treatment by adopting polyvinylidene fluoride emulsion, so that the polyvinylidene fluoride emulsion is attached to the surfaces of the graphite worms to obtain carbon-plastic composite particles; the carbon-plastic composite particles are dried, a mixed material is obtained, and the temperature of the drying operation is lower than the softening temperature of polyvinylidene fluoride; and carrying out molding operation on the mixed material. According to the preparation method of the bipolar plate of the flow battery, the dispersion uniformity of the graphite worms and the polyvinylidene fluoride can be better realized on the basis of ensuring the dispersion stability of the graphite worms and the polyvinylidene fluoride, so that the conductivity and the mechanical property of the bipolar plate can be better ensured.

Description

Technical Field

[0001] The present invention relates to the technical field of batteries, and in particular to a liquid flow battery bipolar plate and a preparation method thereof, and a liquid flow battery. Background Art

[0002] As a key component of liquid flow batteries, bipolar plates connect single cells in series to form a battery stack. They need to have good conductivity, liquid resistance, chemical stability and certain mechanical strength. Flexible graphite plates are currently more commonly used, such as the invention patent application with application number CN201811451411.7, which discloses a highly conductive flexible graphite bipolar plate for liquid flow batteries, which uses expanded graphite and PVDF. However, since expanded graphite, such as worm graphite, also known as graphite worms, is light in weight and has a large difference in specific gravity with PVDF, the dispersion uniformity of worm graphite and PVDF is poor, and the dispersion stability is poor. For example, the invention patent application with application number CN202211697187.6 melts the components to promote the adhesion of the resin to the surface of the graphite worms, so as to improve the dispersion stability of the resin, i.e., PVDF and the graphite worms, but The resin is adhered to the graphite worms by melt mixing, and the dispersion uniformity of the resin and the graphite worms in the final mixed material is poor, which will further cause the conductivity and mechanical properties of the prepared bipolar plate to be poor, thereby affecting the performance and service life of the battery. For example, in the invention patent application with application number CN202410155513.3, an air flow disperser is used to disperse the graphite worms and PVDF, and the waste heat of the graphite worms formed by the high-temperature expansion of expanded graphite is used to achieve uniform adhesion of PDVF on the surface of the graphite worms, which better ensures the dispersion stability of the graphite worms and PVDF. However, the temperature of the graphite worms needs to be strictly controlled, otherwise the adhesion effect of the resin is difficult to ensure, and the resin is sticky after it is melted. In this way, there is still the problem of graphite worm bonding and agglomeration, that is, the uniform coating and dispersion effect of the resin on the graphite worms is difficult to ensure. Summary of the invention

[0003] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a liquid flow battery bipolar plate and a preparation method thereof, and a liquid flow battery that can better ensure the dispersion stability of graphite worms and polyvinylidene fluoride while achieving the dispersion uniformity of graphite worms and polyvinylidene fluoride, thereby better ensuring the conductivity and mechanical properties of the bipolar plate.

[0004] The objective of the present invention is achieved through the following technical solutions:

[0005] A method for preparing a bipolar plate for a flow battery comprises the following steps:

[0006] Obtain polyvinylidene fluoride emulsion and graphite worms;

[0007] fluidizing the graphite worms;

[0008] The polyvinylidene fluoride emulsion is used to spray and coat the graphite worms after fluidization treatment, so that the polyvinylidene fluoride emulsion adheres to the surface of the graphite worms to obtain carbon-plastic composite particles;

[0009] Drying the carbon-plastic composite particles to obtain a mixed material, wherein the drying temperature is lower than the softening temperature of the polyvinylidene fluoride;

[0010] The mixed material is subjected to a molding operation.

[0011] In one embodiment, the method for obtaining the polyvinylidene fluoride emulsion comprises the following specific steps:

[0012] Obtain PVDF emulsion;

[0013] Graphene powder is added to the PVDF emulsion for shear mixing.

[0014] In one of the embodiments, the mass ratio of the graphene to the graphite worms is 1:(2-20).

[0015] In one embodiment, the particle size of the graphite worms is 500 μm to 1 cm.

[0016] In one of the embodiments, the mass ratio of the polyvinylidene fluoride emulsion to the graphite worms is (16-34): (66-84).

[0017] In one embodiment, the solid content of the polyvinylidene fluoride emulsion is 60% to 65%.

[0018] In one embodiment, the graphite worms are subjected to fluidization treatment, and the specific steps are as follows:

[0019] The graphite worms are added into a fluidized bed, the air flow velocity of the fluidized bed is 0.5 m / s to 7 m / s, the temperature is 100° C. to 150° C., and the fluidization time is 5 min to 10 min.

[0020] In one embodiment, the polyvinylidene fluoride emulsion is used to spray-coat the graphite worms after fluidization treatment, and the specific steps are as follows:

[0021] Performing centrifugal atomization treatment on the polyvinylidene fluoride emulsion;

[0022] The graphite worms are subjected to atomization spraying treatment using the polyvinylidene fluoride emulsion that has undergone centrifugal atomization treatment.

[0023] In one embodiment, the polyvinylidene fluoride emulsion is subjected to centrifugal atomization treatment, and the rotation speed of the centrifugal disk is 10000rpm~18000rpm; and / or,

[0024] In one embodiment, the polyvinylidene fluoride emulsion after centrifugal atomization is sprayed on the graphite worms, and the feeding speed of the polyvinylidene fluoride emulsion is 300mL / min to 500mL / min.

[0025] In one embodiment, the mixed material is subjected to a molding operation, and the specific steps are as follows:

[0026] Performing cold pressing operation on the mixed material to obtain a cold pressed board;

[0027] Performing microwave thermal bonding on the cold pressed plate to obtain a thermally bonded plate;

[0028] The heat-bonded sheet is subjected to a cold pressing shaping operation.

[0029] A liquid flow battery bipolar plate is obtained by the preparation method of the liquid flow battery bipolar plate described in any one of the above embodiments.

[0030] A liquid battery comprises the liquid flow battery bipolar plate described in any one of the above embodiments.

[0031] Compared with the prior art, the present invention has at least the following advantages:

[0032] The preparation method of the bipolar plate of the liquid flow battery of the present invention performs fluidization treatment on the graphite worms so that the graphite worms are in a flowing state, that is, firstly, the rapid flow dispersion of the graphite worms themselves is ensured, and then the polyvinylidene fluoride emulsion is used to disperse in the graphite worms. Since the polyvinylidene fluoride in the polyvinylidene fluoride emulsion exists in the form of particles, the polyvinylidene fluoride is not in a viscous state, and the polyvinylidene fluoride exists in the form of an emulsion, the polyvinylidene fluoride emulsion is used to spray and coat the graphite worms after the fluidization treatment, so that the polyvinylidene fluoride emulsion is added to the graphite worms in the flowing and dispersed state in the form of an aerosol. Since the viscosity of the polyvinylidene fluoride emulsion is relatively low, the polyvinylidene fluoride emulsion can be better ensured to be uniformly attached and coated on the surface of the graphite worms without adhesion, thereby better ensuring the dispersion uniformity of the polyvinylidene fluoride and the graphite worms, and also better ensuring the dispersion stability of the polyvinylidene fluoride and the graphite worms, thereby better ensuring the conductivity and mechanical properties of the bipolar plate. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0034] Figure 1 A flow chart of a method for preparing a bipolar plate for a flow battery according to an embodiment of the present invention;

[0035] Figure 2 This is a physical picture of the bipolar plate obtained in Example 8;

[0036] Figure 3 This is an electron microscope image of a cross section of the bipolar plate in Example 8. DETAILED DESCRIPTION

[0037] In order to facilitate the understanding of the present invention, the present invention will be described more fully below with reference to the relevant drawings. The preferred embodiments of the present invention are given in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present invention more thoroughly understood.

[0038] It should be noted that when an element is referred to as being "fixed to" another element, it may be directly on the other element or there may be a central element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are for illustrative purposes only and do not represent the only implementation method.

[0039] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0040] The present application provides a method for preparing a bipolar plate for a flow battery. The method for preparing a bipolar plate for a flow battery comprises the following steps: obtaining a polyvinylidene fluoride emulsion and graphite worms; subjecting the graphite worms to a fluidization treatment; spraying and coating the graphite worms after the fluidization treatment with the polyvinylidene fluoride emulsion so that the polyvinylidene fluoride emulsion adheres to the surface of the graphite worms to obtain carbon-plastic composite particles; drying the carbon-plastic composite particles to obtain a mixed material, wherein the drying temperature is less than the softening temperature of the polyvinylidene fluoride; and molding the mixed material.

[0041] The above-mentioned preparation method of liquid flow battery bipolar plates fluidizes the graphite worms so that the graphite worms are in a flowing state, that is, firstly, the rapid flow and dispersion of the graphite worms themselves are ensured, and then polyvinylidene fluoride emulsion is used to disperse them in the graphite worms. Since the polyvinylidene fluoride emulsion contains polyvinylidene fluoride in the form of particles, the polyvinylidene fluoride is not in a viscous state, and the polyvinylidene fluoride exists in the form of an emulsion. The polyvinylidene fluoride emulsion is used to spray and coat the graphite worms after fluidization treatment, so that the polyvinylidene fluoride emulsion is added to the graphite worms in a flowing and dispersed state in the form of an aerosol. Since the viscosity of the polyvinylidene fluoride emulsion is relatively low, the polyvinylidene fluoride emulsion can be better ensured to be uniformly attached and coated on the surface of the graphite worms without adhesion, thereby better ensuring the dispersion uniformity of polyvinylidene fluoride and graphite worms, and also better ensuring the dispersion stability of polyvinylidene fluoride and graphite worms, thereby better ensuring the conductivity and mechanical properties of the bipolar plate.

[0042] In order to better understand the preparation method of the liquid flow battery bipolar plate of the present application, the preparation method of the liquid flow battery bipolar plate of the present application is further explained below:

[0043] A method for preparing a bipolar plate for a flow battery according to one embodiment includes the following steps:

[0044] Obtaining polyvinylidene fluoride emulsion and graphite worms. It can be understood that in the polyvinylidene fluoride emulsion, the polyvinylidene fluoride exists in the form of particles, and the polyvinylidene fluoride is not in a viscous state, and the polyvinylidene fluoride exists in the form of an emulsion, which better ensures the adhesion effect of the polyvinylidene fluoride on the graphite worms.

[0045] The graphite worms are subjected to fluidization treatment. It is understood that due to the large difference in specific gravity between graphite worms and polyvinylidene fluoride, if stirring is directly adopted, it is difficult to evenly disperse polyvinylidene fluoride in the graphite worms. Therefore, the graphite worms are subjected to fluidization treatment to put the graphite worms in a flowing state, that is, firstly, to ensure the rapid flow and dispersion of the graphite worms themselves.

[0046] The polyvinylidene fluoride emulsion is used to spray and coat the graphite worms after fluidization treatment, so that the polyvinylidene fluoride emulsion is attached to the surface of the graphite worms to obtain carbon-plastic composite particles. It can be understood that the polyvinylidene fluoride emulsion is used to spray and coat the graphite worms, that is, the polyvinylidene fluoride emulsion is added to the graphite worms in a flowing and dispersed state in the form of an aerosol. Since the polyvinylidene fluoride in the polyvinylidene fluoride emulsion is not in a softened or molten state, that is, the viscosity is low, that is, only the spraying speed and spraying amount of the polyvinylidene fluoride emulsion need to be controlled, and the polyvinylidene fluoride emulsion can be better ensured to be uniformly attached and coated on the surface of the graphite worms without adhesion, thereby better ensuring the dispersion uniformity of polyvinylidene fluoride and graphite worms, and also better ensuring the dispersion stability of polyvinylidene fluoride and graphite worms.

[0047] The carbon-plastic composite particles are dried to obtain a mixed material, wherein the temperature of the drying operation is less than the softening temperature of the polyvinylidene fluoride. It can be understood that if the polyvinylidene fluoride emulsion is sprayed onto the surface of the graphite worms, since the difference in specific gravity between polyvinylidene fluoride and graphite worms still exists, the polyvinylidene fluoride emulsion and the graphite worms will still be stratified after being placed together. Therefore, the graphite worms after fluidized bed spraying are dried to remove the solvent in the polyvinylidene fluoride emulsion and reduce the fluidity of polyvinylidene fluoride so that the polyvinylidene fluoride can be more stably attached and coated on the surface of the graphite worms, further improving the dispersion stability of polyvinylidene fluoride and graphite worms, that is, on the basis of ensuring the dispersion stability of graphite worms and polyvinylidene fluoride, the dispersion uniformity of graphite worms and polyvinylidene fluoride is achieved, thereby better ensuring the conductivity and mechanical properties of the bipolar plate.

[0048] The mixed material is subjected to a molding operation to achieve the molding preparation of the bipolar plate.

[0049] The above-mentioned preparation method of liquid flow battery bipolar plates fluidizes the graphite worms so that the graphite worms are in a flowing state, that is, firstly, the rapid flow and dispersion of the graphite worms themselves are ensured, and then polyvinylidene fluoride emulsion is used to disperse them in the graphite worms. Since the polyvinylidene fluoride emulsion contains polyvinylidene fluoride in the form of particles, the polyvinylidene fluoride is not in a viscous state, and the polyvinylidene fluoride exists in the form of an emulsion. The polyvinylidene fluoride emulsion is used to spray and coat the graphite worms after fluidization treatment, so that the polyvinylidene fluoride emulsion is added to the graphite worms in a flowing and dispersed state in the form of an aerosol. Since the viscosity of the polyvinylidene fluoride emulsion is relatively low, the polyvinylidene fluoride emulsion can be better ensured to be uniformly attached and coated on the surface of the graphite worms without adhesion, thereby better ensuring the dispersion uniformity of polyvinylidene fluoride and graphite worms, and also better ensuring the dispersion stability of polyvinylidene fluoride and graphite worms, thereby better ensuring the conductivity and mechanical properties of the bipolar plate.

[0050] In one embodiment, the method for obtaining the polyvinylidene fluoride emulsion comprises the following specific steps: obtaining PVDF emulsion and further adding graphene powder to the PVDF emulsion for shear mixing.

[0051] Furthermore, the particle size of the graphene powder is 0.5 μm to 10 μm. Furthermore, the solid content of the polyvinylidene fluoride emulsion is 60% to 65%.

[0052] Further, graphene powder is added to the PVDF emulsion for shear mixing treatment, and the specific steps are as follows: adding the graphene powder to the PVDF emulsion, dispersing it by high-speed shear mixing at 6000rpm to 8000rpm for 0.5h to 1h, and then circulating it through a high-pressure homogenization device for 0.5h to 2h, with a flow rate of 400L / min to 500L / min and a pressure of 20MPa to 100MPa, so as to better ensure the full mixing and dispersion of graphene in the PVDF emulsion. Further, the mass ratio of polyvinylidene fluoride to graphene is 1:(0.03 to 0.08).

[0053] In one embodiment, the PVDF emulsion is PVDF 900. Further, PVDF 900 is a PVDF emulsion with a model number of MA-EN-B1-0009.

[0054] In one of the embodiments, the mass ratio of the graphene to the graphite worms is 1:(2-20), and the addition of graphene improves the conductivity and mechanical properties of the bipolar plate.

[0055] In one embodiment, the particle size of the graphite worms is 500 μm to 1 cm.

[0056] In one embodiment, the mass ratio of the polyvinylidene fluoride emulsion to the graphite worms is (16-34): (66-84), which better ensures the bonding strength of the graphite worms in the bipolar plate. Preferably, the mass ratio of the polyvinylidene fluoride emulsion to the graphite worms is 16:84. Preferably, the mass ratio of the polyvinylidene fluoride emulsion to the graphite worms is 34:66.

[0057] In one embodiment, the graphite worms are subjected to fluidization treatment, and the specific steps are as follows:

[0058] The graphite worms are added to a fluidized bed with an air flow velocity of 0.5 m / s to 7 m / s, a temperature of 100° C. to 150° C., and a fluidization time of 5 min to 10 min, thereby ensuring a good fluidization effect of the graphite worms and sufficient contact between the graphite worms and the polyvinylidene fluoride emulsion droplets, so that the polyvinylidene fluoride emulsion droplets are uniformly attached to the surface of the graphite worms.

[0059] In one embodiment, the polyvinylidene fluoride emulsion is used to spray-coat the graphite worms after fluidization treatment, and the specific steps are as follows:

[0060] Performing centrifugal atomization treatment on the polyvinylidene fluoride emulsion;

[0061] The graphite worms are subjected to atomization spraying treatment using the polyvinylidene fluoride emulsion that has undergone centrifugal atomization treatment.

[0062] In one embodiment, the polyvinylidene fluoride emulsion is subjected to centrifugal atomization treatment, and the rotation speed of the centrifugal disk is 10000 rpm to 18000 rpm. Further, the polyvinylidene fluoride emulsion is fed by a peristaltic pump and centrifugally thrown out through the centrifugal disk to form polyvinylidene fluoride emulsion droplets.

[0063] In one embodiment, the polyvinylidene fluoride emulsion after centrifugal atomization is sprayed on the graphite worms, and the feeding speed of the polyvinylidene fluoride emulsion is 300mL / min to 500mL / min. Further, the polyvinylidene fluoride emulsion after centrifugal atomization is sprayed on the graphite worms, and the specific steps are as follows: the polyvinylidene fluoride emulsion droplets thrown out by the centrifugal disk are dropped into the fluidized graphite worms for full contact, so that the polyvinylidene fluoride emulsion droplets are attached to the surface of the graphite worms. Furthermore, the particle size D50 of the polyvinylidene fluoride emulsion droplets is 5μm to 6μm.

[0064] In one embodiment, the carbon-plastic composite particles are dried by increasing the temperature of the fluidized bed. Further, the temperature of the fluidized bed is increased by increasing the temperature of the gas introduced into the fluidized bed. Further, the gas is an inert gas, such as nitrogen or argon.

[0065] In one embodiment, the carbon-plastic composite particles are dried, and the specific steps are as follows: fluidized hot air is introduced to dry the carbon-plastic composite particles, the temperature of the fluidized hot air is 50°C to 200°C, the drying time is 5min to 10min, and then the fluidization is stopped. Further, all the materials in the fluidized bed are sent to a cyclone separator through an induced draft fan, and the materials with a larger specific gravity will enter the receiving bottle of the cyclone separator to obtain a mixed material, and the materials with a smaller specific gravity will enter the dust removal tower to obtain tailings.

[0066] In one embodiment, the mixed material is subjected to a molding operation, and the specific steps are as follows:

[0067] S510, cold pressing the mixed material to obtain a cold pressed board. It can be understood that cold pressing the mixed material first, that is, compacting the mixed material by pressurizing, is beneficial to the subsequent bonding and forming of the cold pressed board.

[0068] S530, performing microwave thermal bonding operation on the cold-pressed plate to obtain a thermally bonded plate. It is understandable that hot pressing is generally used to melt polyvinylidene fluoride and bond it with graphite worms to form a shape. However, since polyvinylidene fluoride has a large fluidity after being heated and melted, further hot pressing of the cold-pressed plate will cause uneven dispersion of polyvinylidene fluoride. In this way, even if the stable and uniform dispersion of polyvinylidene fluoride and graphite worms is well achieved in the previous mixture, hot pressing will still cause local aggregation of polyvinylidene fluoride in the bipolar plate, resulting in uneven dispersion of polyvinylidene fluoride in the graphite worms, thereby affecting the electrical conductivity and mechanical properties of the bipolar plate. Therefore, in the present application, microwave thermal bonding operation is performed on the cold-pressed plate. Since the temperature of graphite worms will rise under microwaves, polyvinylidene fluoride Polyvinylidene fluoride has no temperature change or a small temperature change under microwaves. Thus, under the action of microwaves, the temperature of the mixed material starts to rise from the position of the internal graphite worms, so that when the temperature of the mixed material rises, the temperature of the polyvinylidene fluoride in contact with the internal graphite worms rises preferentially through heat transfer and melts. This avoids the serious problem of local agglomeration of polyvinylidene fluoride during the hot melting process, and improves the ability of polyvinylidene fluoride to be more evenly dispersed on the graphite worms after being melted and bonded to the graphite worms, that is, the dispersion uniformity of polyvinylidene fluoride and graphite worms in the bipolar plate is better ensured, thereby better ensuring the electrical conductivity and mechanical properties of the bipolar plate.

[0069] S550, performing cold pressing and shaping operation on the thermal bonding plate. It can be understood that when the polyvinylidene fluoride of the thermal bonding plate is close to being completely melted, the remaining polyvinylidene fluoride is melted by the residual heat, and is simultaneously led out for cold pressing and shaping, which better achieves the rapid cooling and solidification of the melted polyvinylidene fluoride after bonding with the graphite worms, thereby further ensuring the uniformity of the dispersion of polyvinylidene fluoride and graphite worms in the bipolar plate, thereby better ensuring the conductivity and mechanical properties of the bipolar plate.

[0070] It should be noted that, generally, external heating methods, such as heating by hot pressing plates, will cause the parts of the cold pressing plates that are in contact with the hot melt to melt first. This will make the local polyvinylidene fluoride easy to flow under the action of gravity and affect the uniformity of the dispersion of polyvinylidene fluoride. It should also be said that if the hot bonding plate is not cold pressed and shaped, the hot bonding plate cannot be quickly cooled and solidified. This will still cause the polyvinylidene fluoride to flow under the action of gravity after hot melting, resulting in local uneven dispersion of the overall polyvinylidene fluoride in the bipolar plate.

[0071] In one of the embodiments, the mixed material is subjected to cold pressing forming operation, and the specific steps are as follows: the mixed material is put into the feed bin of the rolling equipment, the mixed material enters the distributor from the bin, the distributor spreads the mixed material to a thickness of 10cm to 20cm, and then passes through the rolling equipment at a pressure of 10 tons to 80 tons and a rolling speed of 0.5m / min to 1m / min, thereby better achieving cold pressing forming of the mixed material to form a cold pressed plate.

[0072] In one embodiment, the cold press plate is subjected to microwave thermal bonding operation, and the specific steps are as follows: the cold press plate after the roller passes through the microwave treatment zone, wherein the length of the microwave treatment zone is 0.5m-1m, the microwave power is 100w-1000W, and the travel speed is 0.5m / min-1m / min. It can be understood that the graphite worms, as a medium for microwave heating, can quickly absorb microwave energy and convert it into heat, thereby realizing heat transfer heating of polyvinylidene fluoride, and the heating uniformity is high. Further, the length of the microwave treatment zone is 0.5m-1m, the microwave power is 100w-1000W, and the travel speed is 0.5m / min-1m / min. In this way, the cold press plate can be better realized after passing through the microwave treatment zone. The polyvinylidene fluoride is close to a completely molten state. Further, after passing through the microwave treatment zone, the polyvinylidene fluoride is further completely melted by the residual temperature. Further, the microwave power is 200w-500W. Further, the microwave power is 300w.

[0073] In one embodiment, the hot bonding plate is subjected to cold pressing and shaping operation, and the specific steps are as follows: the pressure is 10 tons to 80 tons for rolling, and the rolling speed is 0.5 to 1 m / min. It can be understood that the polyvinylidene fluoride is further completely melted by the residual temperature, and the cold pressing and shaping is carried out quickly at the same time, that is, the hot bonding plate is quickly cooled and solidified, and the hot bonding plate is further compacted and shaped, which better ensures the dispersion uniformity of the graphite worms and polyvinylidene fluoride of the prepared bipolar plate.

[0074] In one of the embodiments, the mixed material is subjected to a molding operation and continuously transmitted on the same transmission structure, i.e., continuously passed through a rolling device, a microwave treatment zone and another rolling device, which is beneficial to rapid cold pressing molding, rapid microwave hot melt bonding, and rapid cold pressing solidification of the mixed material, thereby better ensuring the dispersion uniformity of the graphite worms and polyvinylidene fluoride of the bipolar plate.

[0075] The present application also provides a liquid flow battery bipolar plate, which is obtained by the preparation method of the liquid flow battery bipolar plate described in any of the above embodiments. Further, in this embodiment, the preparation method of the liquid flow battery bipolar plate includes the following steps: obtaining polyvinylidene fluoride emulsion and graphite worms; fluidizing the graphite worms; spraying and coating the fluidized graphite worms with the polyvinylidene fluoride emulsion so that the polyvinylidene fluoride emulsion adheres to the surface of the graphite worms to obtain carbon-plastic composite particles; drying the carbon-plastic composite particles to obtain a mixed material, wherein the temperature of the drying operation is less than the softening temperature of the polyvinylidene fluoride; and molding the mixed material.

[0076] The above-mentioned liquid flow battery bipolar plate is obtained by adopting the preparation method of the liquid flow battery bipolar plate, which effectively ensures the conductivity and mechanical properties of the liquid flow battery bipolar plate.

[0077] The present application also provides a liquid battery, comprising the liquid flow battery bipolar plate described in any of the above embodiments.

[0078] Compared with the prior art, the present invention has at least the following advantages:

[0079] The preparation method of the bipolar plate of the liquid flow battery of the present invention performs fluidization treatment on the graphite worms so that the graphite worms are in a flowing state, that is, firstly, the rapid flow dispersion of the graphite worms themselves is ensured, and then the polyvinylidene fluoride emulsion is used to disperse in the graphite worms. Since the polyvinylidene fluoride in the polyvinylidene fluoride emulsion exists in the form of particles, the polyvinylidene fluoride is not in a viscous state, and the polyvinylidene fluoride exists in the form of an emulsion, the polyvinylidene fluoride emulsion is used to spray and coat the graphite worms after the fluidization treatment, so that the polyvinylidene fluoride emulsion is added to the graphite worms in the flowing and dispersed state in the form of an aerosol. Since the viscosity of the polyvinylidene fluoride emulsion is relatively low, the polyvinylidene fluoride emulsion can be better ensured to be uniformly attached and coated on the surface of the graphite worms without adhesion, thereby better ensuring the dispersion uniformity of the polyvinylidene fluoride and the graphite worms, and also better ensuring the dispersion stability of the polyvinylidene fluoride and the graphite worms, thereby better ensuring the conductivity and mechanical properties of the bipolar plate.

[0080] Some specific examples are listed below, and if % is mentioned, it means percentage by weight. It should be noted that the following examples do not exhaust all possible situations, and the materials used in the following examples can be obtained from commercial sources unless otherwise specified.

[0081] Example 1

[0082] 8.4 kg of graphite worms were placed in a fluidized bed apparatus with a fluidization velocity of 2.4 m / s, an air flow temperature of 120 °C, and a fluidization time of 6 min;

[0083] 1.6 kg of 60% PVDF emulsion was fed by a peristaltic pump at a feeding speed of 350 mL / min, and centrifuged to a centrifugal disk at a speed of 18,000 rpm to form polyvinylidene fluoride emulsion droplets dispersed in fluidized graphite worms, and fluidized drying was performed for 10 minutes at a hot air temperature of 120°C.

[0084] The prepared PVDF-coated graphite worms were put into a cold pressing device with a cold pressing pressure of 80 tons and a rolling speed of 0.5 m / min to form a cold pressed plate with a thickness of 20 cm;

[0085] After the cold pressing is completed, it enters the microwave heating section, the microwave power is 300W, the length of the microwave heating section is 0.5m, and the travel speed is 0.5m / min;

[0086] After microwave heating, it immediately enters the cold pressing equipment for secondary cold pressing. The cold pressing pressure is 70 tons and the roller pressing speed is 0.5m / min to obtain the finished product.

[0087] Example 2

[0088] 6.6 kg of graphite worms were placed in a fluidized bed apparatus with a fluidization velocity of 2.4 m / s, an air flow temperature of 120 °C, and a fluidization time of 6 min;

[0089] 1.6 kg of 60% PVDF emulsion was fed by a peristaltic pump at a feeding speed of 350 mL / min, and centrifuged to a centrifugal disk at a speed of 18,000 rpm to form polyvinylidene fluoride emulsion droplets dispersed in fluidized graphite worms, and fluidized drying was performed for 10 minutes at a hot air temperature of 120°C.

[0090] The prepared PVDF-coated graphite worms were put into a cold pressing device with a cold pressing pressure of 80 tons and a rolling speed of 0.5 m / min to form a cold pressed plate with a thickness of 20 cm;

[0091] After the cold pressing is completed, it enters the microwave heating section, the microwave power is 300W, the length of the microwave heating section is 0.5m, and the travel speed is 0.5m / min;

[0092] After microwave heating, it immediately enters the cold pressing equipment for secondary cold pressing. The cold pressing pressure is 70 tons and the roller pressing speed is 0.5m / min to obtain the finished product.

[0093] Example 3

[0094] 7.5 kg of graphite worms were placed in a fluidized bed apparatus with a fluidization velocity of 2.4 m / s, an air flow temperature of 120 °C, and a fluidization time of 6 min;

[0095] 2.5 kg of 60% PVDF emulsion was fed by a peristaltic pump at a feeding speed of 350 mL / min, and centrifuged to a centrifugal disk at a speed of 18,000 rpm to form polyvinylidene fluoride emulsion droplets dispersed in fluidized graphite worms, and fluidized drying was performed for 10 minutes at a hot air temperature of 120°C.

[0096] The prepared PVDF-coated graphite worms were put into a cold pressing device with a cold pressing pressure of 80 tons and a rolling speed of 0.5 m / min to form a cold pressed plate with a thickness of 20 cm;

[0097] After the cold pressing is completed, it enters the microwave heating section, the microwave power is 300W, the length of the microwave heating section is 0.5m, and the travel speed is 0.5m / min;

[0098] After microwave heating, it immediately enters the cold pressing equipment for secondary cold pressing. The cold pressing pressure is 70 tons and the roller pressing speed is 0.5m / min to obtain the finished product.

[0099] Example 4

[0100] 6.6 kg of graphite worms were placed in a fluidized bed apparatus with a fluidization velocity of 2.4 m / s, an air flow temperature of 120 °C, and a fluidization time of 6 min;

[0101] 3.4 kg of 60% PVDF emulsion was fed by a peristaltic pump at a feeding speed of 350 mL / min, and centrifuged to a centrifugal disk at a speed of 18,000 rpm to form polyvinylidene fluoride emulsion droplets dispersed in fluidized graphite worms, and fluidized drying was performed for 10 minutes at a hot air temperature of 120°C.

[0102] The prepared PVDF-coated graphite worms were put into a cold pressing device with a cold pressing pressure of 80 tons and a rolling speed of 0.5 m / min to form a cold pressed plate with a thickness of 20 cm;

[0103] After the cold pressing is completed, it enters the microwave heating section, the microwave power is 300W, the length of the microwave heating section is 0.5m, and the travel speed is 0.5m / min;

[0104] After microwave heating, it immediately enters the cold pressing equipment for secondary cold pressing. The cold pressing pressure is 70 tons and the roller pressing speed is 0.5m / min to obtain the finished product.

[0105] Example 5

[0106] 8.4 kg of graphite worms were placed in a fluidized bed apparatus with a fluidization velocity of 2.4 m / s, an air flow temperature of 120 °C, and a fluidization time of 6 min;

[0107] 3.4 kg of 60% PVDF emulsion was fed by a peristaltic pump at a feeding speed of 350 mL / min, and centrifuged to a centrifugal disk at a speed of 18,000 rpm to form polyvinylidene fluoride emulsion droplets dispersed in fluidized graphite worms, and fluidized drying was performed for 10 minutes at a hot air temperature of 120°C.

[0108] The prepared PVDF-coated graphite worms were put into a cold pressing device with a cold pressing pressure of 80 tons and a rolling speed of 0.5 m / min to form a cold pressed plate with a thickness of 20 cm;

[0109] After the cold pressing is completed, it enters the microwave heating section, the microwave power is 300W, the length of the microwave heating section is 0.5m, and the travel speed is 0.5m / min;

[0110] After microwave heating, it immediately enters the cold pressing equipment for secondary cold pressing. The cold pressing pressure is 70 tons and the roller pressing speed is 0.5m / min to obtain the finished product.

[0111] Example 6

[0112] 8.4 kg of graphite worms were placed in a fluidized bed apparatus with a fluidization velocity of 2.4 m / s, an air flow temperature of 120 °C, and a fluidization time of 6 min;

[0113] 2.5 kg of 60% PVDF emulsion was fed by a peristaltic pump at a feeding speed of 350 mL / min, and centrifuged to a centrifugal disk at a speed of 18,000 rpm to form polyvinylidene fluoride emulsion droplets dispersed in fluidized graphite worms, and fluidized drying was performed for 10 minutes at a hot air temperature of 120°C.

[0114] The prepared PVDF-coated graphite worms were put into a cold pressing device with a cold pressing pressure of 80 tons and a rolling speed of 0.5 m / min to form a cold pressed plate with a thickness of 20 cm;

[0115] After the cold pressing is completed, it enters the microwave heating section, the microwave power is 300W, the length of the microwave heating section is 0.5m, and the travel speed is 0.5m / min;

[0116] After microwave heating, it immediately enters the cold pressing equipment for secondary cold pressing. The cold pressing pressure is 70 tons and the roller pressing speed is 0.5m / min to obtain the finished product.

[0117] Example 7

[0118] 2.5 kg of PVDF emulsion with a solid content of 60% was mixed with 75 g of graphene powder with a D50 of 5 μm, and high-speed shearing was performed at 8000 rpm for 0.5 h, and then circulated through a high-pressure homogenizer at a flow rate of 500 L / min and a pressure of 60 MPa for 1 h to obtain a PVDF graphene composite emulsion;

[0119] 8.4 kg of graphite worms were placed in a fluidized bed apparatus with a fluidization velocity of 2.4 m / s, an air flow temperature of 120 °C, and a fluidization time of 6 min;

[0120] The PVDF graphene composite emulsion was fed by a peristaltic pump at a feeding speed of 350 mL / min, and reached the centrifugal disk for centrifugal throwing out. The rotation speed of the centrifugal disk was 18000 rpm, and the polyvinylidene fluoride emulsion droplets were dispersed in the fluidized graphite worms, and fluidized drying was performed for 10 minutes at a hot air temperature of 120°C.

[0121] The prepared PVDF-coated graphite worms were put into a cold pressing device with a cold pressing pressure of 80 tons and a rolling speed of 0.5 m / min to form a cold pressed plate with a thickness of 20 cm;

[0122] After the cold pressing is completed, it enters the microwave heating section, the microwave power is 300W, the length of the microwave heating section is 0.5m, and the travel speed is 0.5m / min;

[0123] After microwave heating, it immediately enters the cold pressing equipment for secondary cold pressing. The cold pressing pressure is 70 tons and the roller pressing speed is 0.5m / min to obtain the finished product.

[0124] Example 8

[0125] 2.5 kg of PVDF emulsion with a solid content of 60% was mixed with 125 g of graphene powder with a D50 of 5 μm, and high-speed shearing was performed at 8000 rpm for 0.5 h, and then circulated through a high-pressure homogenizer at a flow rate of 500 L / min and a pressure of 60 MPa for 1 h to obtain a PVDF graphene composite emulsion;

[0126] 8.4 kg of graphite worms were placed in a fluidized bed apparatus with a fluidization velocity of 2.4 m / s, an air flow temperature of 120 °C, and a fluidization time of 6 min;

[0127] The PVDF graphene composite emulsion was fed by a peristaltic pump at a feeding speed of 350 mL / min, and reached the centrifugal disk for centrifugal throwing out. The rotation speed of the centrifugal disk was 18000 rpm, and the polyvinylidene fluoride emulsion droplets were dispersed in the fluidized graphite worms, and fluidized drying was performed for 10 minutes at a hot air temperature of 120°C.

[0128] The prepared PVDF-coated graphite worms were put into a cold pressing device with a cold pressing pressure of 80 tons and a rolling speed of 0.5 m / min to form a cold pressed plate with a thickness of 20 cm;

[0129] After the cold pressing is completed, it enters the microwave heating section, the microwave power is 300W, the length of the microwave heating section is 0.5m, and the travel speed is 0.5m / min;

[0130] After microwave heating, it immediately enters the cold pressing equipment for secondary cold pressing. The cold pressing pressure is 70 tons and the roller pressing speed is 0.5m / min to obtain the finished product.

[0131] Example 9

[0132] 2.5 kg of PVDF emulsion with a solid content of 60% was mixed with 200 g of graphene powder with a D50 of 5 μm, and high-speed shearing was performed at 8000 rpm for 0.5 h, and then circulated through a high-pressure homogenizer at a flow rate of 500 L / min and a pressure of 60 MPa for 1 h to obtain a PVDF graphene composite emulsion;

[0133] 8.4 kg of graphite worms were placed in a fluidized bed apparatus with a fluidization velocity of 2.4 m / s, an air flow temperature of 120 °C, and a fluidization time of 6 min;

[0134] The PVDF graphene composite emulsion was fed by a peristaltic pump at a feeding speed of 350 mL / min, and reached the centrifugal disk for centrifugal throwing out. The rotation speed of the centrifugal disk was 18000 rpm, and the polyvinylidene fluoride emulsion droplets were dispersed in the fluidized graphite worms, and fluidized drying was performed for 10 minutes at a hot air temperature of 120°C.

[0135] The prepared PVDF-coated graphite worms were put into a cold pressing device with a cold pressing pressure of 80 tons and a rolling speed of 0.5 m / min to form a cold pressed plate with a thickness of 20 cm;

[0136] After the cold pressing is completed, it enters the microwave heating section, the microwave power is 300W, the length of the microwave heating section is 0.5m, and the travel speed is 0.5m / min;

[0137] After microwave heating, it immediately enters the cold pressing equipment for secondary cold pressing. The cold pressing pressure is 70 tons and the roller pressing speed is 0.5m / min to obtain the finished product.

[0138] Example 10

[0139] 2.5 kg of PVDF emulsion with a solid content of 60% was mixed with 125 g of graphene powder with a D50 of 5 μm, and high-speed shearing was performed at 8000 rpm for 0.5 h, and then circulated through a high-pressure homogenizer at a flow rate of 500 L / min and a pressure of 60 MPa for 1 h to obtain a PVDF graphene composite emulsion;

[0140] 8.4 kg of graphite worms were placed in a fluidized bed apparatus with a fluidization velocity of 0.5 m / s, an air flow temperature of 150 °C, and a fluidization time of 10 min;

[0141] The PVDF graphene composite emulsion was fed by a peristaltic pump at a feeding speed of 350 mL / min, and reached the centrifugal disk for centrifugal throwing out. The rotation speed of the centrifugal disk was 18000 rpm, and the polyvinylidene fluoride emulsion droplets were dispersed in the fluidized graphite worms, and fluidized drying was performed for 10 minutes at a hot air temperature of 120°C.

[0142] The prepared PVDF-coated graphite worms were put into a cold pressing device with a cold pressing pressure of 80 tons and a rolling speed of 0.5 m / min to form a cold pressed plate with a thickness of 20 cm;

[0143] After the cold pressing is completed, it enters the microwave heating section, the microwave power is 300W, the length of the microwave heating section is 0.5m, and the travel speed is 0.5m / min;

[0144] After microwave heating, it immediately enters the cold pressing equipment for secondary cold pressing. The cold pressing pressure is 70 tons and the roller pressing speed is 0.5m / min to obtain the finished product.

[0145] Embodiment 11

[0146] 2.5 kg of PVDF emulsion with a solid content of 60% was mixed with 125 g of graphene powder with a D50 of 5 μm, and high-speed shearing was performed at 7000 rpm for 1 hour, and then circulated through a high-pressure homogenizer at a flow rate of 450 L / min and a pressure of 20 MPa for 0.5 hours to obtain a PVDF graphene composite emulsion;

[0147] 8.4 kg of graphite worms were placed in a fluidized bed apparatus with a fluidization velocity of 7 m / s, an air flow temperature of 100 °C, and a fluidization time of 5 min;

[0148] The PVDF graphene composite emulsion was fed by a peristaltic pump at a feeding speed of 350 mL / min, and reached the centrifugal disk for centrifugal throwing out. The rotation speed of the centrifugal disk was 18000 rpm, and the polyvinylidene fluoride emulsion droplets were dispersed in the fluidized graphite worms, and fluidized drying was performed for 10 minutes at a hot air temperature of 120°C.

[0149] The prepared PVDF-coated graphite worms were put into a cold pressing device with a cold pressing pressure of 80 tons and a rolling speed of 0.5 m / min to form a cold pressed plate with a thickness of 20 cm;

[0150] After the cold pressing is completed, it enters the microwave heating section, the microwave power is 300W, the length of the microwave heating section is 0.5m, and the travel speed is 0.5m / min;

[0151] After microwave heating, it immediately enters the cold pressing equipment for secondary cold pressing. The cold pressing pressure is 70 tons and the roller pressing speed is 0.5m / min to obtain the finished product.

[0152] Example 12

[0153] 2.5 kg of PVDF emulsion with a solid content of 60% was mixed with 125 g of graphene powder with a D50 of 5 μm, and high-speed shearing was performed at 8000 rpm for 0.5 h, and then circulated through a high-pressure homogenizer at a flow rate of 500 L / min and a pressure of 60 MPa for 1 h to obtain a PVDF graphene composite emulsion;

[0154] 8.4 kg of graphite worms were placed in a fluidized bed apparatus with a fluidization velocity of 2.4 m / s, an air flow temperature of 120 °C, and a fluidization time of 6 min;

[0155] The PVDF graphene composite emulsion was fed by a peristaltic pump at a feeding speed of 300 mL / min, and reached a centrifugal disk for centrifugal throwing out. The rotation speed of the centrifugal disk was 15000 rpm, and polyvinylidene fluoride emulsion droplets were dispersed in the graphite worms in the fluidization, and fluidized drying was performed for 5 minutes at a hot air temperature of 200°C.

[0156] The prepared PVDF-coated graphite worms were put into a cold pressing device with a cold pressing pressure of 80 tons and a rolling speed of 0.5 m / min to form a cold pressed plate with a thickness of 20 cm;

[0157] After the cold pressing is completed, it enters the microwave heating section, the microwave power is 300W, the length of the microwave heating section is 0.5m, and the travel speed is 0.5m / min;

[0158] After microwave heating, it immediately enters the cold pressing equipment for secondary cold pressing. The cold pressing pressure is 70 tons and the roller pressing speed is 0.5m / min to obtain the finished product.

[0159] Embodiment 13

[0160] 2.5 kg of PVDF emulsion with a solid content of 60% was mixed with 125 g of graphene powder with a D50 of 5 μm, and high-speed shearing was performed at 8000 rpm for 0.5 h, and then circulated through a high-pressure homogenizer at a flow rate of 500 L / min and a pressure of 60 MPa for 1 h to obtain a PVDF graphene composite emulsion;

[0161] 8.4 kg of graphite worms were placed in a fluidized bed apparatus with a fluidization velocity of 2.4 m / s, an air flow temperature of 120 °C, and a fluidization time of 6 min;

[0162] The PVDF graphene composite emulsion was fed by a peristaltic pump at a feeding speed of 500 mL / min, and reached the centrifugal disk for centrifugal discharge. The rotation speed of the centrifugal disk was 10000 rpm, and the polyvinylidene fluoride emulsion droplets were dispersed in the fluidized graphite worms, and fluidized drying was performed for 10 minutes at a hot air temperature of 50°C.

[0163] The prepared PVDF-coated graphite worms were put into a cold pressing device with a cold pressing pressure of 80 tons and a rolling speed of 0.5 m / min to form a cold pressed plate with a thickness of 20 cm;

[0164] After the cold pressing is completed, it enters the microwave heating section, the microwave power is 300W, the length of the microwave heating section is 0.5m, and the travel speed is 0.5m / min;

[0165] After microwave heating, it immediately enters the cold pressing equipment for secondary cold pressing. The cold pressing pressure is 70 tons and the roller pressing speed is 0.5m / min to obtain the finished product.

[0166] Embodiment 14

[0167] 2.5 kg of PVDF emulsion with a solid content of 60% was mixed with 125 g of graphene powder with a D50 of 5 μm, and high-speed shearing was performed at 8000 rpm for 0.5 h, and then circulated through a high-pressure homogenizer at a flow rate of 500 L / min and a pressure of 60 MPa for 1 h to obtain a PVDF graphene composite emulsion;

[0168] 8.4 kg of graphite worms were placed in a fluidized bed apparatus with a fluidization velocity of 2.4 m / s, an air flow temperature of 120 °C, and a fluidization time of 6 min;

[0169] The PVDF graphene composite emulsion was fed by a peristaltic pump at a feeding speed of 350 mL / min, and reached the centrifugal disk for centrifugal throwing out. The rotation speed of the centrifugal disk was 18000 rpm, and the polyvinylidene fluoride emulsion droplets were dispersed in the fluidized graphite worms, and fluidized drying was performed for 10 minutes at a hot air temperature of 120°C.

[0170] The prepared PVDF-coated graphite worms were put into a cold pressing device with a cold pressing pressure of 10 tons and a rolling speed of 1 m / min to form a cold pressed plate with a thickness of 20 cm;

[0171] After the cold pressing is completed, it enters the microwave heating section, the microwave power is 100W, the length of the microwave heating section is 1m / min, and the travel speed is 0.5m / min;

[0172] After microwave heating, it immediately enters the cold pressing equipment for secondary cold pressing. The cold pressing pressure is 10 tons and the roller pressing speed is 1m / min to obtain the finished product.

[0173] Embodiment 15

[0174] 2.5 kg of PVDF emulsion with a solid content of 60% was mixed with 125 g of graphene powder with a D50 of 5 μm, and high-speed shearing was performed at 8000 rpm for 0.5 h, and then circulated through a high-pressure homogenizer at a flow rate of 500 L / min and a pressure of 60 MPa for 1 h to obtain a PVDF graphene composite emulsion;

[0175] 8.4 kg of graphite worms were placed in a fluidized bed apparatus with a fluidization velocity of 2.4 m / s, an air flow temperature of 120 °C, and a fluidization time of 6 min;

[0176] The PVDF graphene composite emulsion was fed by a peristaltic pump at a feeding speed of 350 mL / min, and reached the centrifugal disk for centrifugal throwing out. The rotation speed of the centrifugal disk was 18000 rpm, and the polyvinylidene fluoride emulsion droplets were dispersed in the fluidized graphite worms, and fluidized drying was performed for 10 minutes at a hot air temperature of 120°C.

[0177] The prepared PVDF-coated graphite worms were put into a cold pressing device with a cold pressing pressure of 60 tons and a rolling speed of 0.8 m / min to form a cold pressed plate with a thickness of 20 cm;

[0178] After the cold pressing is completed, it enters the microwave heating section, the microwave power is 600W, the length of the microwave heating section is 0.6m / min, and the travel speed is 1m / min;

[0179] After microwave heating, it immediately enters the cold pressing equipment for secondary cold pressing. The cold pressing pressure is 60 tons and the roller pressing speed is 0.8m / min to obtain the finished product.

[0180] Example 16

[0181] 2.5 kg of PVDF emulsion with a solid content of 60% was mixed with 125 g of graphene powder with a D50 of 5 μm, and high-speed shearing was performed at 8000 rpm for 0.5 h, and then circulated through a high-pressure homogenizer at a flow rate of 500 L / min and a pressure of 60 MPa for 1 h to obtain a PVDF graphene composite emulsion;

[0182] 8.4 kg of graphite worms were placed in a fluidized bed apparatus with a fluidization velocity of 2.4 m / s, an air flow temperature of 120 °C, and a fluidization time of 6 min;

[0183] The PVDF graphene composite emulsion was fed by a peristaltic pump at a feeding speed of 350 mL / min, and reached the centrifugal disk for centrifugal throwing out. The rotation speed of the centrifugal disk was 18000 rpm, and the polyvinylidene fluoride emulsion droplets were dispersed in the fluidized graphite worms, and fluidized drying was performed for 10 minutes at a hot air temperature of 120°C.

[0184] The prepared PVDF-coated graphite worms were put into a cold pressing device with a cold pressing pressure of 80 tons and a rolling speed of 1 m / min to form a cold pressed plate with a thickness of 20 cm;

[0185] After the cold pressing is completed, it enters the microwave heating section, the microwave power is 1000W, the length of the microwave heating section is 0.5m / min, and the travel speed is 1m / min;

[0186] After microwave heating, it immediately enters the cold pressing equipment for secondary cold pressing. The cold pressing pressure is 80 tons and the roller pressing speed is 0.5m / min to obtain the finished product.

[0187] Comparative Example 1

[0188] 1.5 kg PVDF powder and 8.4 kg graphite worms were mixed in a double motion mixer at 300 rpm for 30 min;

[0189] The mixed material is fed into the cold pressing equipment with a cold pressing pressure of 60 tons and a roller pressing speed of 1m / min to form a cold pressed plate with a thickness of 20cm;

[0190] After the cold pressing is completed, it enters the ordinary hot pressing, the hot pressing temperature is 220℃, the hot pressing pressure is 70 tons, and the rolling speed is 1m / min to obtain the finished product.

[0191] Comparative Example 2

[0192] 1.5 kg PVDF powder, 125 g graphene powder with a D50 of 5 μm and 8.4 kg graphite worms were mixed in a double motion mixer at a speed of 300 rpm for 30 min;

[0193] The mixed material is fed into the cold pressing equipment with a cold pressing pressure of 60 tons and a roller pressing speed of 1m / min to form a cold pressed plate with a thickness of 20cm;

[0194] After the cold pressing is completed, it enters the ordinary hot pressing, the hot pressing temperature is 220℃, the hot pressing pressure is 70 tons, and the rolling speed is 1m / min to obtain the finished product.

[0195] Comparative Example 3

[0196] 8.4 kg of graphite worms were placed in a fluidized bed apparatus with a fluidization velocity of 1.4 m / s, an air flow temperature of 120 °C, and a fluidization time of 6 min;

[0197] 1.5 kg PVDF powder was added into the fluidized bed together with the pre-graphite worms for fluidization dispersion. The fluidization time was 20 min.

[0198] The mixed material is fed into the cold pressing equipment with a cold pressing pressure of 60 tons and a roller pressing speed of 1m / min to form a cold pressed plate with a thickness of 20cm;

[0199] After the cold pressing is completed, it enters the ordinary hot pressing, the hot pressing temperature is 220℃, the hot pressing pressure is 70 tons, and the rolling speed is 1m / min to obtain the finished product.

[0200] It should be noted that the PVDF emulsion was purchased from CLUDE, the brand is ARKEMA, the model is MA-EN-BI-000905, the moisture content is ≤0.1%, the melting point is 160-180°C, and the purity is ≥99.5%.

[0201] The bipolar plates of the embodiments and the bipolar plates of the comparative examples were tested for conductivity, bending strength, bending modulus, deflection, and density. The test results are shown in Table 1.

[0202] Table 1

[0203]

[0204] From Table 1, further combined Figure 2 and Figure 3 It can be seen that the conductivity and mechanical properties of the bipolar plates obtained in each embodiment are significantly better than those of the bipolar plates obtained in each comparative example, especially the conductivity and mechanical properties of the bipolar plate obtained in Example 8 are better, indicating that the mixing ratio of the graphite worms and polyvinylidene fluoride, or the added graphene is adjusted, and the polyvinylidene fluoride emulsion is further mixed with the graphite worms in the fluidization through centrifugal atomization, and the mixing parameters are adjusted to better achieve the mixing uniformity of the graphite worms and polyvinylidene fluoride, or the added graphene. The mixed material is further subjected to continuous cold pressing, microwave heating and cold pressing, which further achieves the mixing uniformity of the graphite worms and polyvinylidene fluoride, or the added graphite in the bipolar plate, and better improves the conductivity and mechanical properties of the bipolar plate.

[0205] The above embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for those of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A method for preparing a bipolar plate for a flow battery, characterized in that: The steps include: Obtain polyvinylidene fluoride emulsion and graphite worms; fluidizing the graphite worms; The polyvinylidene fluoride emulsion is used to spray and coat the graphite worms after fluidization treatment, so that the polyvinylidene fluoride emulsion adheres to the surface of the graphite worms to obtain carbon-plastic composite particles; Drying the carbon-plastic composite particles to obtain a mixed material, wherein the drying temperature is lower than the softening temperature of the polyvinylidene fluoride; The mixed material is subjected to a molding operation.

2. The method for preparing a bipolar plate for a flow battery according to claim 1, characterized in that: The method for obtaining the polyvinylidene fluoride emulsion comprises the following specific steps: Obtain PVDF emulsion; Graphene powder is added to the PVDF emulsion for shear mixing.

3. The method for preparing a bipolar plate for a flow battery according to claim 2, characterized in that: The mass ratio of the graphene to the graphite worms is 1:(2-20).

4. The method for preparing a bipolar plate for a flow battery according to claim 1, characterized in that: The particle size of the graphite worms is 500 μm to 1 cm; and / or, The mass ratio of the polyvinylidene fluoride emulsion to the graphite worms is (16-34): (66-84); and / or, The solid content of the polyvinylidene fluoride emulsion is 60% to 65%.

5. The method for preparing a bipolar plate for a flow battery according to claim 1, characterized in that: The graphite worms are subjected to fluidization treatment, and the specific steps are as follows: The graphite worms are added into a fluidized bed, the air flow velocity of the fluidized bed is 0.5 m / s to 7 m / s, the temperature is 100° C. to 150° C., and the fluidization time is 5 min to 10 min.

6. The method for preparing a bipolar plate for a flow battery according to claim 1, characterized in that: The polyvinylidene fluoride emulsion is used to spray-coat the graphite worms after fluidization treatment, and the specific steps are as follows: Performing centrifugal atomization treatment on the polyvinylidene fluoride emulsion; The graphite worms are subjected to atomization spraying treatment using the polyvinylidene fluoride emulsion that has undergone centrifugal atomization treatment.

7. The method for preparing a bipolar plate for a flow battery according to claim 6, characterized in that: The polyvinylidene fluoride emulsion is subjected to centrifugal atomization treatment, and the centrifugal disk speed is 10000rpm~18000rpm; and / or, The graphite worms are subjected to atomization spraying treatment using the polyvinylidene fluoride emulsion after centrifugal atomization treatment, and the feeding speed of the polyvinylidene fluoride emulsion is 300 mL / min to 500 mL / min.

8. The method for preparing a bipolar plate for a flow battery according to claim 1, characterized in that: The mixed material is subjected to molding operation, and the specific steps are as follows: Performing cold pressing operation on the mixed material to obtain a cold pressed board; Performing microwave thermal bonding on the cold pressed plate to obtain a thermally bonded plate; The heat-bonded sheet is subjected to a cold pressing shaping operation.

9. A bipolar plate for a liquid flow battery, characterized in that: The method for preparing a bipolar plate for a liquid flow battery according to any one of claims 1 to 8 is used to obtain the bipolar plate.

10. A liquid battery, characterized in that: Including the liquid flow battery bipolar plate as described in claim 9.

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