WO2020098106A1 - 一种一体化双极性电极及其制备方法、应用 - Google Patents

一种一体化双极性电极及其制备方法、应用 Download PDF

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Publication number
WO2020098106A1
WO2020098106A1 PCT/CN2018/124579 CN2018124579W WO2020098106A1 WO 2020098106 A1 WO2020098106 A1 WO 2020098106A1 CN 2018124579 W CN2018124579 W CN 2018124579W WO 2020098106 A1 WO2020098106 A1 WO 2020098106A1
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active material
material layer
electrode active
positive
bipolar
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PCT/CN2018/124579
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English (en)
French (fr)
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刘素琴
袁修贵
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中南大学
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Priority to US16/976,872 priority Critical patent/US11380903B2/en
Publication of WO2020098106A1 publication Critical patent/WO2020098106A1/zh

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/86—Inert electrodes with catalytic activity, e.g. for fuel cells
    • H01M4/8647—Inert electrodes with catalytic activity, e.g. for fuel cells consisting of more than one material, e.g. consisting of composites
    • H01M4/8657—Inert electrodes with catalytic activity, e.g. for fuel cells consisting of more than one material, e.g. consisting of composites layered
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/86—Inert electrodes with catalytic activity, e.g. for fuel cells
    • H01M4/88—Processes of manufacture
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/86—Inert electrodes with catalytic activity, e.g. for fuel cells
    • H01M4/96—Carbon-based electrodes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/18—Regenerative fuel cells, e.g. redox flow batteries or secondary fuel cells
    • H01M8/184—Regeneration by electrochemical means
    • H01M8/188—Regeneration by electrochemical means by recharging of redox couples containing fluids; Redox flow type batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
    • H01M2004/029—Bipolar electrodes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/86—Inert electrodes with catalytic activity, e.g. for fuel cells
    • H01M2004/8678—Inert electrodes with catalytic activity, e.g. for fuel cells characterised by the polarity
    • H01M2004/8694—Bipolar electrodes

Definitions

  • the invention belongs to the field of battery materials, and particularly relates to an electrode and a preparation method and application thereof.
  • the all-vanadium flow battery has become a discontinuous type of solar energy, tidal energy, wind energy, etc. due to its advantages of long service life, adjustable capacity and power, large current non-destructive deep discharge, safe operation, easy operation and maintenance, and no environmental pollution The first choice for stable renewable energy power generation and storage.
  • the conductive current collector is usually a flexible graphite plate or mixed with graphite, high-density polyethylene powder, carbon fiber and conductive carbon black.
  • the specific mixing preparation process is usually: proportioning at room temperature, Using absolute ethanol as the dispersant, the resin powder and the conductive filler are fully mixed with magnetic stirring, and then the mixture is poured into a stainless steel evaporating dish, placed in a drying oven and dried at 100 °C for about 20min, and then molded in a mold Finally, put it in a drying oven to dry, dry at 150 °C for about 15min, take out air cooling.
  • the conductive current collector and the active electrode material are usually prepared by hot pressing or bonding together to form an integrated composite electrode.
  • the active electrode material and the conductive current collector are combined together by hot pressing or a conductive adhesive layer, the active electrode material and the conductive current collector are required to be firmly bonded and have good conductivity.
  • the binder is first stirred into a paste with a mixture of water and ethanol, and evenly spread on the conductive current collector, and then the processed graphite felt is pressed smoothly on top, maintaining a certain pressure, and maintained at 160 °C for 10 minutes in a thermostat, after cooling Take out to become an integrated composite electrode.
  • the integrated compound electrode includes two types, an end electrode connected to the pole ear, and a bipolar electrode that is in contact with two diaphragms on both sides.
  • the conductive current collector located in the bipolar electrode is also called bipolar plate. It not only undertakes the task of connecting the positive and negative electrodes of two adjacent single cells, but also plays the role of completely isolating the positive and negative electrolytes. Therefore, it is required to have not only good electronic conductivity, but also acid resistance, oxidation resistance, and completely impermeable electrolyte characteristics.
  • the bipolar plate is separated from the positive and negative electrode materials.
  • the bipolar plate and the positive and negative electrode materials are usually prepared by hot pressing or bonding. The electrode assembly is complicated and cumbersome, and the gap between the bipolar plate and the electrode material is also increased. The contact resistance affects the battery performance.
  • the technical problem to be solved by the present invention is to overcome the deficiencies and defects mentioned in the background art above, and to provide an integrated bipolar electrode with excellent performance and its preparation method and application.
  • the bipolar electrode in the present invention is positive and negative There is no contact resistance between the extremely active materials, and the assembled battery has excellent performance.
  • the technical solutions proposed by the present invention are:
  • An integrated bipolar electrode includes a sandwich structure and a bipolar plate (that is, equivalent to a current collector in the prior art).
  • the sandwich structure is formed by interconnecting a positive electrode active material layer and a negative electrode active material layer.
  • the bipolar plate is interposed in the cavity of the sandwich structure, and a side of the sandwich structure is provided with a sealing layer for cooperating with the fixing frame of the bipolar electrode to prevent the penetration of the positive and negative electrolytes.
  • the bipolar plate is a non-conductive sheet that does not react with the positive and negative electrolytes (eg, has acid resistance and oxidation resistance) and is impermeable to liquids. More preferably, the bipolar plate is composed of rubber, plastic or both to obtain a composite.
  • the bipolar plate can also use the conventional current collector in the prior art, but it is not recommended because the current collector generally emphasizes high conductivity, but when it has high conductivity, it isolates the electrolyte Performance is bound to be affected.
  • the current collector has high conductivity, the performance of insulating electrolyte will be reduced, and the current collector will have low conductivity, and the performance of insulating electrolyte will be improved, but its conductivity will be affected.
  • the electrochemical performance of the resulting battery will be reduced.
  • the conductive medium such as carbon contained in the current collector will react with the electrolyte when it is in contact with the electrolyte for a long time, resulting in a reduced service life of the bipolar electrode.
  • non-conductive sheets such as more preferred rubber, plastic, etc.
  • the above non-conductive sheet includes but is not limited to polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene or fluororubber, silicone rubber and the like.
  • the positive electrode active material layer and the negative electrode active material layer are graphite felt, carbon felt, carbon cloth, or a conductive sheet containing a carbon-based material. More preferably, the positive and negative electrode active material layers are polyacrylonitrile graphite felt.
  • the thickness h of the positive electrode active material layer and / or the negative electrode active material layer on the side of the sandwich structure is less than 1 mm.
  • the positive electrode active material layer and / or the negative electrode active material layer on the side of the sandwich structure are in a mesh shape.
  • the positive and negative electrode active material layers are directly in contact for electrical conduction. Studies have shown that there is no gap between the positive and negative electrode active material layers after the positive and negative electrode connecting contact parts are sealed with the side of the bipolar plate by a binder The problem of electrolyte penetration.
  • the thickness h of the positive active material layer and / or the negative active material layer on the side of the bipolar plate is controlled Less than the thickness of other parts (or, preferably, the positive electrode active material layer and / or the negative electrode active material layer on the side of the bipolar plate are meshed), which further reduces the electrolyte passing through the positive and negative electrodes on the side of the bipolar plate Possibility of penetration of the negative electrode active material layer.
  • the material of the positive electrode active material layer and the negative electrode active material layer are the same, the sandwich structure is formed by folding an integral sheet in half, and the bipolar plate is provided in the sandwich structure In the cavity.
  • the positive and negative electrode active material layers are a whole, and the sandwich structure can be formed by folding once or several times, and the preparation process of the sandwich structure is more concise.
  • the positive and negative electrode active material layers are a whole. Compared with the split positive and negative electrode active material layers, the contact resistance is smaller, which is more conducive to electron conduction.
  • the material on the side of the sandwich structure can be thinned or hollowed into a mesh structure to further reduce the possibility of electrolyte penetration.
  • the positive electrode active material layer and the negative electrode active material layer are two separate sheets, and the cavity of the sandwich structure is formed by folding two separate sheets A sealed cavity, the bipolar plate is provided in the sealed cavity.
  • the bipolar plate is completely wrapped by the positive electrode active material layer and / or the negative electrode active material layer to form a full package structure.
  • the contact area of the positive and negative electrode active material layers is relatively large, and the electron conduction is relatively Faster.
  • the all-inclusive structure when the sealing layer is coated on the side of the sandwich structure, will be more convenient and more advantageous.
  • the present invention also provides a method for preparing the above integrated bipolar electrode, which includes the following steps:
  • connection part in S1 is glued so that the positive electrode active material layer and the negative electrode active material layer form a connected whole;
  • the above preparation method is a generally applicable method.
  • the corresponding preparation method is also provided in the present invention.
  • the preparation method may include the following two situations: The first case (only one fold in half at this time) includes the following steps:
  • the second case (bending multiple times at this time) includes the following steps:
  • the preparation method includes the following steps:
  • the area ratio of the positive and negative active material layers is between 0.9-1.1, and the area of the bipolar plate and The area ratio of the smaller area of the positive and negative electrode active material layers is between 0.8-1.5.
  • the present invention also provides an application of the above integrated bipolar electrode in an all-vanadium flow battery.
  • the all-vanadium flow battery includes at least one integrated bipolar electrode, a bipolar electrode fixing frame for fixing the integrated bipolar electrode, and a positive electrode for isolating 3. Separator of negative electrolyte.
  • the present invention provides a more typical preparation method (the positive electrode active material layer and the negative electrode active material layer have different area sizes, which are separate sheets), and the process includes the following steps:
  • the research on bipolar electrodes focuses on the high conductivity, acid resistance, oxidation resistance and liquid impermeability of the liquid collector.
  • the actual situation is also that the above-mentioned poor performance of the current collector has become the key to restrict the performance improvement of the flow battery .
  • the research ideas in the present invention can solve the problems in the prior art very well.
  • the present invention is mainly based on the following principles: 1) In the present invention, the positive and negative active layer materials are directly contacted, and the electrons are directly contacted through the positive and negative active materials Partial transfer, electron transfer between positive and negative electrodes does not need to pass through an intermediate adhesive or other polymers, its contact resistance is small, and the performance of the resulting battery is better.
  • the positive and negative electrode active material layers of the present invention are acid-resistant, anti-oxidation, liquid-impermeable rubber or plastic.
  • the rubber or plastic is located between the positive and negative active materials to completely isolate the positive and negative electrolytes. The negative electrolyte will not penetrate through rubber or plastic, which can eliminate the problem of battery self-discharge.
  • the positive and negative electrode active material layers in the integrated bipolar electrode of the present invention are directly connected, the contact resistance between the two is very small, and the resulting battery has better performance.
  • the invention saves the preparation process of the current collector and the positive and negative active electrodes by hot pressing or bonding, the manufacturing process is simple, the process is shorter, and it can be greatly reduced cost.
  • FIG. 1 is a schematic structural diagram of an integrated bipolar electrode in Example 1.
  • FIG. 1 is a schematic structural diagram of an integrated bipolar electrode in Example 1.
  • FIG. 2 is a schematic diagram of the structure of the bipolar electrode in Example 1 (equivalent to the cross-sectional view of the A-A plane in FIG. 1).
  • FIG. 3 is another schematic diagram of the structure of the bipolar electrode in Embodiment 1.
  • FIG. 3 is another schematic diagram of the structure of the bipolar electrode in Embodiment 1.
  • Example 4 is a schematic structural view of the positive and negative active material layers in Example 1 after being unfolded.
  • Example 5 is a schematic structural diagram of a bipolar electrode in Example 2.
  • FIG. 6 is a schematic diagram of another structure of the bipolar electrode in Embodiment 2.
  • FIG. 6 is a schematic diagram of another structure of the bipolar electrode in Embodiment 2.
  • Example 7 is a schematic structural view of a bipolar electrode in Example 3.
  • Example 8 is a schematic structural view of a bipolar electrode in Example 4.
  • Example 9 is a schematic structural diagram of the positive and negative active material layers and the bipolar plate in Example 5 after being superimposed (unfolded).
  • Example 10 is a schematic structural diagram of the positive and negative active material layers and the bipolar plate in Example 6 after being superimposed (unfolded).
  • the integrated bipolar electrode of this embodiment includes a sandwich structure and a bipolar plate 2.
  • the sandwich structure is formed by connecting the positive electrode active material layer 1 and the negative electrode active material layer 3 to each other.
  • the bipolar plate 2 is sandwiched in the cavity of the above sandwich structure.
  • the side of the sandwich structure is provided with a frame for fixing the bipolar electrode.
  • a sealing layer 4 to prevent penetration of positive and negative electrolytes.
  • the materials of the positive electrode active material layer 1 and the negative electrode active material layer 3 are both polyacrylonitrile graphite felt, the bipolar plate 2 is a PP film, and the sealing layer 4 is an acid-resistant and oxidation-resistant epoxy resin.
  • the sandwich structure in this embodiment is formed by folding an integral polyacrylonitrile graphite felt in half, and the bipolar plate 2 is provided in the cavity of the sandwich structure.
  • the edge of the surface of the positive electrode active material layer 1 and the negative electrode active material layer 3 is also coated with sealant, so that the side sealing layer extends to the positive electrode active
  • the edges of the surface of the material layer 1 and the negative electrode active material layer 3 to achieve a better sealing effect.
  • the edge sealants on the surfaces of the positive electrode active material layer 1 and the negative electrode active material layer 3 are not shown in the figures, the same applies below.
  • the integrated bipolar electrode in this embodiment is used in an all-vanadium flow battery.
  • the all-vanadium flow battery includes an end plate with a liquid inlet and a liquid outlet, a conductive electrode ear, and at least one integrated double A polar electrode, a bipolar electrode fixing frame for fixing the above integrated bipolar electrode, and a separator for isolating positive and negative electrolytes.
  • the polyacrylonitrile graphite felt on the side of the sandwich structure (that is, around the fold fold) can also be thinned, as shown in FIG. 3.
  • the polyacrylonitrile graphite felt on the side of the sandwich structure (that is, the periphery of the fold fold) can also be hollowed into a mesh shape, and the structure after unfolding the polyacrylonitrile graphite felt is shown in FIG.
  • the integrated bipolar electrode in the situation shown in Fig. 3 and Fig. 4 is assembled into a battery pack composed of two single cells through internal series connection, and the constant current charge and discharge energy efficiency is 79.3 at a current density of 100 mA ⁇ cm -2 %, Its Coulomb efficiency is 97.3%, and the positive and negative electrolytes are completely impermeable.
  • the integrated bipolar electrode of this embodiment includes a sandwich structure and a bipolar plate 2.
  • the sandwich structure is formed by connecting the positive electrode active material layer 1 and the negative electrode active material layer 3 to each other.
  • the bipolar plate 2 is sandwiched in the cavity of the above sandwich structure.
  • the side of the sandwich structure is provided with a frame for fixing the bipolar electrode.
  • a sealing layer 4 to prevent penetration of positive and negative electrolytes.
  • the materials of the positive electrode active material layer 1 and the negative electrode active material layer 3 are both polyacrylonitrile graphite felt, the bipolar plate 2 is a PE film, and the sealing layer 4 is an acid-resistant and oxidation-resistant epoxy resin.
  • the positive electrode active material layer 1 and the negative electrode active material layer 3 are two separate sheets, and the sandwich structure is formed by folding the two separate sheets and the two separate sheets
  • the inner cavity of the sandwich structure is a sealed cavity, and the bipolar plate 2 is set in the sealed cavity (in FIG. 5, for ease of expression, the adhesive at the contact between the two split sheets is not shown, and its There is a small section overlapped and compacted at the contact between the two, the same below).
  • the bottom polyacrylonitrile graphite felt can also be thinned on the side of the sandwich structure (that is, around the crease).
  • the integrated bipolar electrode shown in FIG. 6 is used in an all-vanadium flow battery.
  • the integrated bipolar electrode shown in FIG. 6 is assembled into a battery pack consisting of two single cells connected in series.
  • the constant current charge and discharge energy efficiency at a current density of 100 mA ⁇ cm -2 is 79.8%, and its Coulomb efficiency is 97.5%.
  • the positive and negative electrolytes are completely impermeable.
  • the integrated bipolar electrode of this embodiment includes a sandwich structure and a bipolar plate 2.
  • the sandwich structure is formed by connecting the positive electrode active material layer 1 and the negative electrode active material layer 3 to each other.
  • the bipolar plate 2 is sandwiched in the cavity of the above sandwich structure.
  • the side of the sandwich structure is provided with a frame for fixing the bipolar electrode.
  • a sealing layer 4 to prevent penetration of positive and negative electrolytes.
  • the materials of the positive electrode active material layer 1 and the negative electrode active material layer 3 are both polyacrylonitrile graphite felt, the bipolar plate 2 is a PP film, and the sealing layer 4 is an acid-resistant and oxidation-resistant epoxy resin.
  • the sandwich structure in this embodiment is formed by connecting an integral polyacrylonitrile graphite felt end-to-end by bending 4 times, and the bipolar plate 2 is provided in the cavity of the sandwich structure.
  • the integrated bipolar electrode in this embodiment is assembled into a battery pack composed of two single cells through internal series connection, and the constant current charge and discharge energy efficiency is 99.5% at a current density of 100 mA ⁇ cm -2 , and its coulomb The efficiency is 97.4%, and the positive and negative electrolytes are completely impermeable.
  • the integrated bipolar electrode of this embodiment includes a sandwich structure and a bipolar plate 2.
  • the sandwich structure is formed by connecting the positive electrode active material layer 1 and the negative electrode active material layer 3 to each other.
  • the bipolar plate 2 is sandwiched in the cavity of the above sandwich structure.
  • the side of the sandwich structure is provided with a frame for fixing the bipolar electrode.
  • a sealing layer 4 to prevent penetration of positive and negative electrolytes.
  • the materials of the positive electrode active material layer 1 and the negative electrode active material layer 3 are both polyacrylonitrile graphite felt, the bipolar plate 2 is a silicon rubber film, and the sealing layer 4 is an acid-resistant and oxidation-resistant epoxy resin.
  • the positive electrode active material layer 1 and the negative electrode active material layer 3 are two separate sheets with the same width and different lengths, and the positive electrode active material layer 1 and the negative electrode active material layer 3
  • the edges of the three sides are flush, and the other edge of the sheet with a larger area is bent and directly in contact with the other edge of the sheet with a smaller area to form a sandwich structure.
  • the bipolar plate 2 is disposed in the cavity of the sandwich structure.
  • the integrated bipolar electrode in this embodiment is assembled into a battery pack composed of two single cells through internal series connection, and the constant current charge and discharge energy efficiency is 79.3% at a current density of 100 mA ⁇ cm -2 , and its coulomb The efficiency is 97.2%, and the positive and negative electrolytes are completely impermeable.
  • the integrated bipolar electrode of this embodiment includes a sandwich structure and a bipolar plate 2.
  • the sandwich structure is formed by connecting the positive electrode active material layer 1 and the negative electrode active material layer 3 to each other.
  • the bipolar plate 2 is sandwiched in the cavity of the above sandwich structure.
  • the side of the sandwich structure is provided with a frame for fixing the bipolar electrode.
  • a sealing layer 4 to prevent penetration of positive and negative electrolytes.
  • the materials of the positive electrode active material layer 1 and the negative electrode active material layer 3 are both polyacrylonitrile graphite felt, the bipolar plate 2 is a PP film, and the sealing layer 4 is an acid-resistant and oxidation-resistant epoxy resin.
  • the positive electrode active material layer 1 and the negative electrode active material layer 3 are two separate sheets with different widths and different lengths.
  • the edges of the positive electrode active material layer 1 and the negative electrode active material layer 3 are flush with a larger area.
  • the other two edges of the material are bent and directly contact with the other two edges of the sheet with a smaller area to form a sandwich structure.
  • the bipolar plate 2 is disposed in the cavity of the sandwich structure.
  • the integrated bipolar electrode in this embodiment is assembled into a battery pack composed of two single cells through internal series connection, and the constant current charge and discharge energy efficiency is 79.1% at a current density of 100 mA ⁇ cm -2 .
  • the efficiency is 97.2%, and the positive and negative electrolytes are completely impermeable.
  • the integrated bipolar electrode of this embodiment includes a sandwich structure and a bipolar plate 2.
  • the sandwich structure is formed by connecting the positive electrode active material layer 1 and the negative electrode active material layer 3 to each other.
  • the bipolar plate 2 is sandwiched in the cavity of the above sandwich structure.
  • the side of the sandwich structure is provided with a frame for fixing the bipolar electrode.
  • a sealing layer 4 to prevent penetration of positive and negative electrolytes.
  • the materials of the positive electrode active material layer 1 and the negative electrode active material layer 3 are both polyacrylonitrile graphite felt, the bipolar plate 2 is a PP film, and the sealing layer 4 is an acid-resistant and oxidation-resistant epoxy resin.
  • the positive electrode active material layer 1 and the negative electrode active material layer 3 are two separate sheets with different widths and different lengths, and one edge of the positive electrode active material layer 1 and the negative electrode active material layer 3 are flush The other three edges of the sheet with a larger area are bent and directly contact with the other three edges of the sheet with a smaller area to form a sandwich structure.
  • the bipolar plate 2 is provided in the cavity of the sandwich structure.
  • the integrated bipolar electrode in this embodiment is assembled into a battery pack composed of two single cells through internal series connection, and the constant current charge and discharge energy efficiency is 79.1% at a current density of 100 mA ⁇ cm -2 .
  • the efficiency is 97.0%, and the positive and negative electrolytes are completely impermeable.
  • the battery pack assembled by the conventional current collector and two graphite felts has a significant decrease in the energy efficiency of constant current charging and discharging at a current density of 100 mA ⁇ cm -2 .

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Abstract

一种一体化双极性电极及其制备方法、应用，该一体化双极性电极包括夹层结构和双极板(2)，夹层结构由正极活性材料层(1)与负极活性材料层(3)相互连接而成，双极板(2)夹设于夹层结构的空腔中，夹层结构的侧面设有用于与双极性电极固定框体相配合以防止正、负极电解液相互渗透的密封层(4)。一体化双极性电极中正、负极活性材料层(1，3)直接连接，二者之间的接触电阻非常小，最终制备得到的电池性能更好。并且，一体化双极性电极制作工艺简单、流程更短。

Description

一种一体化双极性电极及其制备方法、应用 技术领域
本发明属于电池材料领域，尤其涉及一种电极及其制备方法、应用。
背景技术
全钒液流电池因其具有使用寿命长、容量和功率可调、大电流无损深度放电、运行安全、易操作和维护、无环境污染等等优点而成为太阳能、潮汐能、风能等间断式不稳定可再生能源发电储能的首选。
现有钒电池中，导电集流体通常为柔性石墨板或以石墨、高密度聚乙烯粉末、碳纤维和导电炭黑为原料混合而成，其具体混合制备工艺通常为：在室温下按照比例配料，采用无水乙醇作为分散剂，用磁力搅拌使树脂粉末和导电填料充分混合，再将混合物倒入不锈钢蒸发皿，放入干燥箱烘干，在100℃烘干大约20min，然后在模具中压制成型，最后放入干燥箱烘干，在150℃烘干大约15min，取出空冷即可。
现有技术中，为简化电堆组装工艺，通常将导电集流体与活性电极材料通过热压或黏结在一起制备成一体化复合电极。当活性电极材料和导电集流体通过热压或导电黏结层结合在一起时，要求活性电极材料和导电集流体黏结牢靠，具有良好导电性。黏结剂首先用水和乙醇的混合物搅拌成糊状，均匀涂抹在导电集流体上，然后将处理好的石墨毡平稳地压在上面，保持一定的压力，在恒温箱中160℃保持10min，冷却后取出即可成为一体化复合电极。
一体化复合电极包括两类，与极耳相连的端电极和两边分别与两片隔膜相接触的双极性电极。位于双极性电极中的导电集流体又称双极板，它既承担着连接相邻两个单电池的正、负极的任务，又要起到完全隔离正、负极电解液的作用。因此，要求其不仅具有良好的电子导电性，而且具有耐酸、耐氧化、完全不渗透电解液等特性。现有技术中，双极板与正、负电极材料分离，双极板与正负极材料通常通过热压或黏结制备成型，电极组装复杂、繁琐，也增加了双极板与电极材料之间的接触电阻，影响电池性能。
发明内容
本发明所要解决的技术问题是，克服以上背景技术中提到的不足和缺陷，提供一种性能优异的一体化双极性电极及其制备方法、应用，本发明中的双极性电极正负极活性材料之间没有接触电阻，组装得到的电池性能非常优异。
为解决上述技术问题，本发明提出的技术方案为：
一种一体化双极性电极，包括夹层结构和双极板(即相当于现有技术中的集流体)，所述夹层结构由正极活性材料层与负极活性材料层相互连接而成，所述双极板夹设于所述夹层结 构的空腔中，所述夹层结构的侧面设有用于与双极性电极固定框体相配合以防止正、负极电解液相互渗透的密封层。
上述一体化双极性电极中，优选的，所述双极板为与正、负极电解液不反应(如具备耐酸、抗氧化)、不渗液的不导电薄片。更优选的，所述双极板为橡胶、塑料或其二者复合得到复合物。本发明中，双极板也可采用现有技术中常规的集流体，但不推荐，因为现有集流体一般都要强调高导电性能，但在其具备高导电性能时，其隔绝电解液的性能必然会受到影响。一般来说，现有集流体导电性能高，则隔绝电解液的性能会降低，现有集流体导电性能低，隔绝电解液的性能会有所提高，但其导电性会受到影响，利用其制备得到的电池的电化学性能会降低。另外，现有集流体中含有的导电介质(如碳)长时间与电解液接触时会与电解液发生反应，导致双极性电极的使用寿命减少。本发明中选用与电解液不反应、不渗液的不导电薄片(如更优选的橡胶、塑料等)，这些材料不仅价格便宜，而且可以完全杜绝正、负极电解液通过集流体相互渗透，从而引起电池自放电的问题。上述不导电薄片包括但不限于聚四氟乙烯、聚偏氟乙烯、聚乙烯、聚丙烯或氟橡胶、硅橡胶等。
上述一体化双极性电极中，优选的，所述正极活性材料层与负极活性材料层为石墨毡、碳毡、碳布或包含碳素类材料的导电薄片。更优选的，所述正、负极活性材料层为聚丙烯腈石墨毡。
上述一体化双极性电极中，优选的，位于夹层结构侧面的正极活性材料层和/或负极活性材料层的厚度h小于1mm。或者，优选的，位于夹层结构侧面的正极活性材料层和/或负极活性材料层呈网状。本发明中，正、负极活性材料层直接接触用于导电，研究表明，通过粘结剂将正、负极连接接触部分与双极板的侧面进行密封后，正、负极活性材料层之间不存在电解液渗透的问题。为了进一步杜绝电解液可能通过位于双极板侧边的正、负极活性材料渗透的可能性，本发明中，控制位于双极板侧边的正极活性材料层和/或负极活性材料层的厚度h小于其他部分的厚度(或者，优选的，使位于双极板侧边的正极活性材料层和/或负极活性材料层呈网状)，进一步降低了电解液通过位于双极板侧边的正、负极活性材料层渗透的可能性。
上述一体化双极性电极中，优选的，所述正极活性材料层与负极活性材料层的材料相同，所述夹层结构由一整体片材经对折而成，所述双极板设于夹层结构的空腔中。正、负极活性材料层为一整体，对折一次或弯折几次即可形成夹层结构，夹层结构的制备工艺更加简洁。另外，正、负极活性材料层本身为一整体，相比于分体式的正、负极活性材料层折叠接触而言，接触电阻更小，更加有利于电子传导。此种结构的双极性电极，可以将位于夹层结构侧面的材料做减薄处理或镂空成网状结构，以进一步减少电解液渗透的可能性。
上述一体化双极性电极中，优选的，所述正极活性材料层与负极活性材料层为两块分体片材，所述夹层结构的空腔为由两块分体片材折叠而成的密封腔体，所述双极板设于上述密封腔体中。上述结构中，即相当于双极板被正极活性材料层和/或负极活性材料层全包裹，形成一全包结构，此时，正、负极活性材料层接触的面积相对较大，电子传导相对较快。另外，全包形结构，在夹层结构的侧面涂覆密封层时，会更加便捷，更加有优势。
作为一个总的技术构思，本发明还提供一种上述一体化双极性电极的制备方法，包括以下步骤：
S1：将双极板插入正极活性材料层和负极活性材料层之间形成“三明治”结构，再将正极活性材料层和/或负极活性材料层的边缘沿双极板的侧边进行折叠使正极活性材料层和负极活性材料层相互连接，再将连接部分压实；
S2：将S1中的连接部分胶粘，使正极活性材料层和负极活性材料层成一相互连接的整体；
S3：对上述“三明治”结构的侧面进行胶粘密封形成密封层即得到一体化双极性电极。
上述制备方法是一种普遍适用性的方法，对于特殊的结构，本发明中也给出相应的制备方法，当正、负极活性材料为一整体片材时，制备方法可包括以下两种情况：第一种情况(此时只对折一次)包括以下步骤：
S1：将上述整体片材对折形成两块面积大小相同的正极活性材料层与负极活性材料层，再在正极活性材料层与负极活性材料层之间插入双极板形成三层叠加结构；
S2：将上述三层叠加结构的侧面进行胶粘密封形成密封层即得到一体化双极性电极。
第二种情况(此时弯折多次)包括以下步骤：
S1：将上述整体片材弯折使整体片材的首尾两端相连形成一用于容纳双极板的腔体，并将整体片材的首尾两端胶粘，再将双极板插入上述腔体中形成三层叠加结构；
S2：将上述三层叠加结构的侧面进行胶粘密封形成密封层即得到一体化双极性电极。
当正、负极活性材料为分体片材时，制备方法包括以下步骤：
S1：将双极板插入上述两块分体片材之间形成“三明治”结构，再将至少一块片材的边缘沿双极板的侧边进行折叠使上述两块分体片材直接接触，再将接触部分压实、胶粘，并使双极板被上述两块分体片材全部包裹；
S2：对上述“三明治”结构的侧面进行胶粘密封形成密封层即得到一体化双极性电极。
对于上述正极活性材料层与负极活性材料层为两块面积大小不同的分体片材时，优选控制正、负极活性材料层二者的面积比值在0.9-1.1之间，双极板的面积与正、负极活性材料层中面积较小者的面积比值在0.8-1.5之间。
作为一个总的技术构思，本发明还提供一种上述一体化双极性电极在全钒液流电池中的应用。
上述应用中，优选的，所述全钒液流电池包括至少一个所述一体化双极性电极、用于固定所述一体化双极性电极的双极性电极固定框体和用于隔绝正、负极电解液的隔膜。
为了便于理解，本发明提供一种较典型的制备方法(正极活性材料层与负极活性材料层的面积大小不同，为分体片材)，其过程包括以下步骤：
(1)根据电堆大小的要求，裁剪两块长方形的聚丙烯腈石墨毡分别作为正、负极活性材料层，并控制两块正、负极活性材料层的宽度相同，长度不同，长度较长者记为A层，另一层为C层；再将其二者在高纯水中洗涤，以去除其表面附着的灰尘、杂质和因裁剪造成的碎纤维，然后将洗涤后的活性电极材料进行离心或甩干，以除去其中80-99.5％的水分，备用；
(2)准备一块宽度与上述两块正、负极活性材料层相同，长度介于二者之间的橡胶薄膜，记为B层，备用；
(3)将B层插入A、C层之间，并将A层置于B层底下，保持A、B、C层的三边对齐，再将A层的另一边沿B层边缘向上折叠，使其与C层接触，将接触部分压实，再用环氧树脂将压实部分与各侧边进行胶粘密封，即得到本发明中的一体化双极性电极。
现有技术中，对双极性电极的研究着重于集液体的高导电性、耐酸、耐氧化、不渗液，现实情况也是集流体的上述性能不佳已成为制约液流电池性能提高的关键。本发明中的研究思路可以非常好的解决现有技术中存在的问题，本发明主要基于以下原理：1)本发明中使正、负极活性层材料直接接触，电子直接通过正、负极活性材料接触部分传递，正、负极之间电子传递无需通过中间胶黏剂或其他聚合物，其接触电阻小，最终制备得到的电池的性能更好。2)本发明正、负极活性材料层之间为耐酸、抗氧化、不渗液的橡胶或塑料等，上述橡胶或塑料位于正、负极活性材料之间可以完全隔绝正、负极电解液，正、负极电解液不会通过橡胶或塑料渗透，可以杜绝电池自放电的问题。
与现有技术相比，本发明的有益效果为：
1、本发明的一体化双极性电极中正、负极活性材料层直接连接，二者之间的接触电阻非常小，最终制备得到的电池性能更好。
2、本发明与传统一体化双极性电极的制备方法相比，省去了集流体与正、负极活性电极通过热压或黏结制备成型工序，制作工艺简单、流程更短，可大幅度降低成本。
附图说明
为了更清楚地说明本发明实施例或现有技术中的技术方案，下面将对实施例或现有技术描述中所需要使用的附图作简单地介绍，显而易见地，下面描述中的附图是本发明的一些实 施例，对于本领域普通技术人员来讲，在不付出创造性劳动的前提下，还可以根据这些附图获得其他的附图。
图1为实施例1中一体化双极性电极的结构示意图。
图2为实施例1中双极性电极的结构示意图(相当于图1中A-A面的剖切视图)。
图3为实施例1中双极性电极的另一种结构示意图。
图4为实施例1中正、负极活性材料层展开后的结构示意图。
图5为实施例2中双极性电极的结构示意图。
图6为实施例2中双极性电极的另一种结构示意图。
图7为实施例3中双极性电极的结构示意图。
图8为实施例4中双极性电极的结构示意图。
图9为实施例5中正、负极活性材料层与双极板叠加后的结构示意图(未折叠)。
图10为实施例6中正、负极活性材料层与双极板叠加后的结构示意图(未折叠)。
图例说明：
1、正极活性材料层；2、双极板；3、负极活性材料层；4、密封层。
具体实施方式
为了便于理解本发明，下文将结合说明书附图和较佳的实施例对本发明做更全面、细致地描述，但本发明的保护范围并不限于以下具体实施例。
除非另有定义，下文中所使用的所有专业术语与本领域技术人员通常理解含义相同。本文中所使用的专业术语只是为了描述具体实施例的目的，并不是旨在限制本发明的保护范围。
除非另有特别说明，本发明中用到的各种原材料、试剂、仪器和设备等均可通过市场购买得到或者可通过现有方法制备得到。
实施例1：
如图1所示，本实施例的一体化双极性电极，包括夹层结构和双极板2。夹层结构由正极活性材料层1与负极活性材料层3相互连接而成，双极板2夹设于上述夹层结构的空腔中，夹层结构的侧面设有用于与双极性电极固定框体相配合以防止正、负极电解液相互渗透的密封层4。
上述双极性电极中，正极活性材料层1与负极活性材料层3的材料均为聚丙烯腈石墨毡，双极板2为PP薄膜，密封层4为耐酸、耐氧化的环氧树脂。
具体的，如图2所示，本实施例中的夹层结构由一整体聚丙烯腈石墨毡经对折而成，双极板2设于夹层结构的空腔中。
本实施例中一体化双极性电极的制备方法包括以下步骤：
(1)裁取长、宽分别为80cm、40cm的聚丙烯腈石墨毡一块，将这块石墨毡浸泡于去离子水中10-30min，取出，置于离心干燥器中，以800-1200rpm的转速脱水1-2min；裁取长、宽分别为40cm、40cm的PP薄膜一片；
(2)将80cm×40cm的聚丙烯腈石墨毡沿长边的中点对折，将裁好的PP薄膜放置于石墨毡之间，使PP薄膜的四边与半块石墨毡的四边平齐；
(3)用环氧树脂将折叠好的聚丙烯腈基石墨毡/PP/聚丙烯腈基石墨毡的侧面进行粘接和密封，即得到本实施例的一体化双极性电极。
在实际密封时，为了保证侧面的密封效果，一般在侧面密封胶时，还会在正极活性材料层1与负极活性材料层3表面的边缘也涂密封胶，使侧面的密封层延伸至正极活性材料层1与负极活性材料层3表面的边缘，以达到更好的密封效果。为了便于表述，本实施例，图中均未示出正极活性材料层1与负极活性材料层3表面的边缘密封胶，下同。
将本实施例中的一体化双极性电极用于全钒液流电池，该全钒液流电池包括开有进液口与出液口的端板、导电极耳、至少一个上述一体化双极性电极、用于固定上述一体化双极性电极的双极性电极固定框体和用于隔绝正、负极电解液的隔膜。
将本实施例中的一体化双极性电极与正、负端电极、隔膜等组装成由两个单电池通过内串联组成的电池组，在100mA·cm -2的电流密度下恒流充、放电能量效率为79.8％，其库伦效率为98.0％，正负电解液完全不渗液。
本实施例中，夹层结构侧面(即对折折痕周边)的聚丙烯腈石墨毡还可做减薄处理，如图3所示。
另外，本实施例中，夹层结构侧面(即对折折痕周边)的聚丙烯腈石墨毡还可以镂空成网状，将聚丙烯腈石墨毡展开后的结构如图4所示。
图3与图4中所示情况的一体化双极性电极组装成由两个单电池通过内串联组成的电池组，在100mA·cm -2的电流密度下恒流充、放电能量效率为79.3％，其库伦效率为97.3％，正负电解液完全不渗液。
实施例2：
本实施例的一体化双极性电极，包括夹层结构和双极板2。夹层结构由正极活性材料层1与负极活性材料层3相互连接而成，双极板2夹设于上述夹层结构的空腔中，夹层结构的侧面设有用于与双极性电极固定框体相配合以防止正、负极电解液相互渗透的密封层4。
上述双极性电极中，正极活性材料层1与负极活性材料层3的材料均为聚丙烯腈石墨毡，双极板2为PE薄膜，密封层4为耐酸、耐氧化的环氧树脂。
具体的，如图5所示，正极活性材料层1与负极活性材料层3为两块分体片材，夹层结 构由两块分体片材经折叠而成，且两块分体片材构成的夹层结构的内腔为一密封的腔体，双极板2设于上述密封的腔体中(图5中，为了便于表达，两块分体片材接触处的胶粘剂未示出，且其二者接触处有一小段被重叠压实，下同)。
本实施例中一体化双极性电极的制备方法包括以下步骤：
(1)裁取长、宽分别为65cm、41cm的聚丙烯腈石墨毡与长、宽分别为68cm、45cm的聚丙烯腈石墨毡各一块，将这两块石墨毡浸泡于去离子水中10-30min，取出，置于离心干燥器中，以800-1200rpm的转速脱水1-2min；裁取长、宽分别为66cm、43cm的PE薄膜一片；
(2)将68cm×45cm的聚丙烯腈石墨毡平放于操作台，将裁好的PE薄膜平行放置于石墨毡中间；再在PE薄膜上平行放置尺寸为65cm×41cm的聚丙烯腈基石墨毡，保持2块石墨毡与PE薄膜的中心重合；
(3)将位于底部的聚丙烯腈石墨毡中的四边沿PE薄膜的四边向上折叠并置于上部聚丙烯腈石墨毡上，使位于最上部的聚丙烯腈石墨毡与位于底部的聚丙烯腈石墨毡直接接触，并将接触部分用环氧树脂胶粘密封；
(4)用环氧树脂将聚丙烯腈基石墨毡/PE/聚丙烯腈基石墨毡的侧面进行粘接和密封，即得到本实施例的一体化双极性电极。
另外，如图6所示，本实施例中，底部的聚丙烯腈石墨毡在夹层结构侧面(即折痕周边)还可做减薄处理。
将图6所示的一体化双极性电极用于全钒液流电池，由图6中所示情况的一体化双极性电极组装成由两个单电池通过内串联组成的电池组，在100mA·cm -2的电流密度下恒流充、放电能量效率为79.8％，其库伦效率为97.5％，正负电解液完全不渗液。
实施例3：
本实施例的一体化双极性电极，包括夹层结构和双极板2。夹层结构由正极活性材料层1与负极活性材料层3相互连接而成，双极板2夹设于上述夹层结构的空腔中，夹层结构的侧面设有用于与双极性电极固定框体相配合以防止正、负极电解液相互渗透的密封层4。
上述双极性电极中，正极活性材料层1与负极活性材料层3的材料均为聚丙烯腈石墨毡，双极板2为PP薄膜，密封层4为耐酸、耐氧化的环氧树脂。
具体的，如图7所示，本实施例中的夹层结构由一整体聚丙烯腈石墨毡经弯折4次首尾连接而成，双极板2设于夹层结构的空腔中。
本实施例中一体化双极性电极的制备方法包括以下步骤：
(1)裁取长、宽分别为82cm、40cm的聚丙烯腈石墨毡一块，将这块石墨毡浸泡于去离子水中10-30min，取出，置于离心干燥器中，以800-1200rpm的转速脱水1-2min；裁取长、 宽分别为40cm、40cm的PP薄膜一片；
(2)将82cm×40cm的聚丙烯腈石墨毡弯折4次形成容纳双极板2的腔体，并将聚丙烯腈石墨毡的首尾用环氧树脂胶粘，再将裁好的PP薄膜放置于上述腔体中；
(3)用环氧树脂将折叠好的聚丙烯腈基石墨毡/PP/聚丙烯腈基石墨毡的侧面进行粘接和密封，即得到本实施例的一体化双极性电极。
将本实施例中的一体化双极性电极组装成由两个单电池通过内串联组成的电池组，在100mA·cm -2的电流密度下恒流充、放电能量效率为79.5％，其库伦效率为97.4％，正负电解液完全不渗液。
实施例4：
本实施例的一体化双极性电极，包括夹层结构和双极板2。夹层结构由正极活性材料层1与负极活性材料层3相互连接而成，双极板2夹设于上述夹层结构的空腔中，夹层结构的侧面设有用于与双极性电极固定框体相配合以防止正、负极电解液相互渗透的密封层4。
上述双极性电极中，正极活性材料层1与负极活性材料层3的材料均为聚丙烯腈石墨毡，双极板2为硅橡胶薄膜，密封层4为耐酸、耐氧化的环氧树脂。
具体的，如图8所示，本实施例中，正极活性材料层1与负极活性材料层3为两块宽度相同、长度不同的分体片材，正极活性材料层1与负极活性材料层3的三边边缘平齐，面积较大的片材的另一边边缘弯折并与面积较小的片材的另一边边缘直接接触形成夹层结构，双极板2设于夹层结构的空腔中。
本实施例一体化双极电极的制备方法包括以下步骤：
(1)裁取长、宽分别为47cm、31cm和长、宽分别为44cm、31cm的聚丙烯腈石墨毡两块，将这两块石墨毡浸泡于去离子水中10-30min，取出，置于离心干燥器中，以800-1200rpm的转速脱水1-2min；裁取长、宽分别为45cm、31cm的硅橡胶薄膜一片；
(2)将31cm×47cm的聚丙烯腈石墨毡平放于操作台，将裁好的硅橡胶薄膜放置在其表面，再将31cm×44cm的聚丙烯腈石墨毡放置于硅橡胶薄膜表面，并使两块聚丙烯腈石墨毡与硅橡胶薄膜的三边边缘平齐；
(3)将位于底部的聚丙烯腈石墨毡中的另一边沿硅橡胶薄膜边缘向上折叠并置于上层聚丙烯腈石墨毡表面上，使位于最上面的聚丙烯腈石墨毡与位于底部的聚丙烯腈石墨毡直接接触，再将接触部分压实、并用环氧树脂胶粘；
(4)用环氧树脂将折叠好的聚丙烯腈基石墨毡/硅橡胶薄膜/聚丙烯腈基石墨毡的侧面进行粘接和密封，即得到本实施例的一体化双极性电极。
将本实施例中的一体化双极性电极组装成由两个单电池通过内串联组成的电池组，在 100mA·cm -2的电流密度下恒流充、放电能量效率为79.3％，其库伦效率为97.2％，正负电解液完全不渗液。
实施例5：
本实施例的一体化双极性电极，包括夹层结构和双极板2。夹层结构由正极活性材料层1与负极活性材料层3相互连接而成，双极板2夹设于上述夹层结构的空腔中，夹层结构的侧面设有用于与双极性电极固定框体相配合以防止正、负极电解液相互渗透的密封层4。
上述双极性电极中，正极活性材料层1与负极活性材料层3的材料均为聚丙烯腈石墨毡，双极板2为PP薄膜，密封层4为耐酸、耐氧化的环氧树脂。
具体的，正极活性材料层1与负极活性材料层3为两块宽度不同、长度不同的分体片材，正极活性材料层1与负极活性材料层3的两边边缘平齐，面积较大的片材的另外两边边缘弯折并与面积较小的片材的另外两边边缘直接接触形成夹层结构，双极板2设于夹层结构的空腔中。
本实施例一体化双极电极的制备方法包括以下步骤：
(1)裁取长、宽分别为47cm、31cm的聚丙烯腈石墨毡与长、宽分别为44cm、28cm的聚丙烯腈石墨毡各一块，将这两块石墨毡浸泡于去离子水中10-30min，取出，置于离心干燥器中，以800-1200rpm的转速脱水1-2min；裁取长、宽分别为45cm、29cm的PP薄膜一片；
(2)将47cm×31cm的聚丙烯腈石墨毡平放于操作台，将裁好的PP薄膜平行放置于聚丙烯腈石墨毡表面；再在PP薄膜上平行放置尺寸为44cm×28cm的聚丙烯腈基石墨毡；并使两块聚丙烯腈石墨毡与PP薄膜的某一角相互重叠(如图9所示)；
(3)将位于底部的聚丙烯腈石墨毡中的两条边沿PP薄膜侧边向上折叠并置于上部聚丙烯腈石墨毡上，使位于最上部的聚丙烯腈石墨毡的两条边与位于底部的聚丙烯腈石墨毡两条边直接接触，再将接触部分压实、并用环氧树脂胶粘；
(4)用环氧树脂将折叠好的聚丙烯腈基石墨毡/PP/聚丙烯腈基石墨毡的侧面进行粘接和密封，即得到本实施例的一体化双极性电极。
将本实施例中的一体化双极性电极组装成由两个单电池通过内串联组成的电池组，在100mA·cm -2的电流密度下恒流充、放电能量效率为79.1％，其库伦效率为97.2％，正负电解液完全不渗液。
实施例6：
本实施例的一体化双极性电极，包括夹层结构和双极板2。夹层结构由正极活性材料层1与负极活性材料层3相互连接而成，双极板2夹设于上述夹层结构的空腔中，夹层结构的侧面设有用于与双极性电极固定框体相配合以防止正、负极电解液相互渗透的密封层4。
上述双极性电极中，正极活性材料层1与负极活性材料层3的材料均为聚丙烯腈石墨毡，双极板2为PP薄膜，密封层4为耐酸、耐氧化的环氧树脂。
具体的，如图10所示，正极活性材料层1与负极活性材料层3为两块宽度不同、长度不同的分体片材，正极活性材料层1与负极活性材料层3的一边边缘平齐，面积较大的片材的另外三边边缘弯折并与面积较小的片材的另外三边边缘直接接触形成夹层结构，双极板2设于夹层结构的空腔中。
本实施例一体化双极电极的制备方法包括以下步骤：
(1)裁取长、宽分别为47cm、31cm的聚丙烯腈石墨毡与长、宽分别为44cm、28cm的聚丙烯腈石墨毡各一块，将这两块石墨毡浸泡于去离子水中10-30min，取出，置于离心干燥器中，以800-1200rpm的转速脱水1-2min；裁取长、宽分别为45cm、29cm的PP薄膜一片；
(2)将47cm×31cm的聚丙烯腈石墨毡平放于操作台，将裁好的PP薄膜平行放置于聚丙烯腈石墨毡表面；再在PP薄膜上平行放置尺寸为44cm×28cm的聚丙烯腈基石墨毡；并使两块聚丙烯腈石墨毡与PP薄膜的某一长边相互重叠；
(3)将位于底部的聚丙烯腈石墨毡中的另外三条边(即边缘不重叠的三边)沿PP薄膜侧边向上折叠并置于上部聚丙烯腈石墨毡上，使位于最上部的聚丙烯腈石墨毡的三条边与位于底部的聚丙烯腈石墨毡三条边直接接触，再将接触部分压实、并用环氧树脂胶粘；
(4)用环氧树脂将折叠好的聚丙烯腈基石墨毡/PP/聚丙烯腈基石墨毡的侧面进行粘接和密封，即得到本实施例的一体化双极性电极。
将本实施例中的一体化双极性电极组装成由两个单电池通过内串联组成的电池组，在100mA·cm -2的电流密度下恒流充、放电能量效率为79.1％，其库伦效率为97.0％，正负电解液完全不渗液。
对比例：
利用常规集流体与两块石墨毡(两块石墨毡通过外加压力贴于常规集流体的两面)组装成由两个单电池通过内串联组成的电池组，在100mA·cm -2的电流密度下恒流充、放电能量效率为75.3％，库伦效率为97.7％。
由对比例可知，常规集流体与两块石墨毡组装成的电池组，在100mA·cm -2的电流密度下恒流充、放电能量效率明显降低。

Claims (13)

  1. 一种一体化双极性电极，其特征在于，包括夹层结构和双极板(2)，所述夹层结构由正极活性材料层(1)与负极活性材料层(3)相互连接而成，所述双极板(2)夹设于所述夹层结构的空腔中，所述夹层结构的侧面设有用于与双极性电极固定框体相配合以防止正、负极电解液相互渗透的密封层(4)。
  2. 根据权利要求1所述的一体化双极性电极，其特征在于，所述双极板(2)为与正、负极电解液不反应、不渗液的不导电薄片。
  3. 根据权利要求1所述的一体化双极性电极，其特征在于，所述正极活性材料层(1)与负极活性材料层(3)为石墨毡、碳毡、碳布或包含碳素类材料的导电薄片。
  4. 根据权利要求1所述的一体化双极性电极，其特征在于，位于夹层结构侧面的正极活性材料层(1)和/或负极活性材料层(3)的厚度h小于1mm。
  5. 根据权利要求1所述的一体化双极性电极，其特征在于，位于夹层结构侧面的正极活性材料层(1)和/或负极活性材料层(3)呈网状。
  6. 根据权利要求1-5中任一项所述的一体化双极性电极，其特征在于，所述正极活性材料层(1)与负极活性材料层(3)的材料相同，所述夹层结构由一整体片材经对折而成，所述双极板(2)设于夹层结构的空腔中。
  7. 根据权利要求1-5中任一项所述的一体化双极性电极，其特征在于，所述正极活性材料层(1)与负极活性材料层(3)为两块分体片材，所述夹层结构的空腔为由两块分体片材折叠而成的密封腔体，所述双极板(2)设于上述密封腔体中。
  8. 一种如权利要求1-5中任一项所述的一体化双极性电极的制备方法，其特征在于，包括以下步骤：
    S1：将双极板(2)插入正极活性材料层(1)和负极活性材料层(3)之间形成“三明治”结构，再将正极活性材料层(1)和/或负极活性材料层(3)的边缘沿双极板(2)的侧边进行折叠使正极活性材料层(1)和负极活性材料层(3)相互连接，再将连接部分压实；
    S2：将S1中的连接部分胶粘，使正极活性材料层(1)和负极活性材料层(3)成一相互连接的整体；
    S3：对上述“三明治”结构的侧面进行胶粘密封形成密封层(4)即得到一体化双极性电极。
  9. 一种如权利要求6所述的一体化双极性电极的制备方法，其特征在于，包括以下步骤：
    S1：将上述整体片材对折形成两块面积大小相同的正极活性材料层(1)与负极活性材料层(3)，再在正极活性材料层(1)与负极活性材料层(3)之间插入双极板(2)形成三层叠加结构；
    S2：将上述三层叠加结构的侧面进行胶粘密封形成密封层(4)即得到一体化双极性电极。
  10. 一种如权利要求6所述的一体化双极性电极的制备方法，其特征在于，包括以下步骤：
    S1：将上述整体片材弯折使整体片材的首尾两端相连形成一用于容纳双极板(2)的腔体，并将整体片材的首尾两端胶粘，再将双极板(2)插入上述腔体中形成三层叠加结构；
    S2：将上述三层叠加结构的侧面进行胶粘密封形成密封层(4)即得到一体化双极性电极。
  11. 一种如权利要求7所述的一体化双极性电极的制备方法，其特征在于，包括以下步骤：
    S1：将双极板(2)插入上述两块分体片材之间形成“三明治”结构，再将至少一块片材的边缘沿双极板(2)的侧边进行折叠使上述两块分体片材直接接触，再将接触部分压实、胶粘，并使双极板(2)被上述两块分体片材全部包裹；
    S2：对上述“三明治”结构的侧面进行胶粘密封形成密封层(4)即得到一体化双极性电极。
  12. 一种如权利要求1-7中任一项所述的或如权利要求8-11中任一项所述的制备方法得到的一体化双极性电极在全钒液流电池中的应用。
  13. 根据权利要求12所述的应用，其特征在于，所述全钒液流电池包括至少一个所述一体化双极性电极、用于固定所述一体化双极性电极的双极性电极固定框体和用于隔绝正、负极电解液的隔膜。
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