CN102479963A - Membrane module, flow battery unit and battery stack - Google Patents

Abstract

Disclosed is a membrane assembly, a membrane assembly for a liquid flow battery unit, comprising: two frame bodies, each frame body includes a frame portion and a hollow portion defined by the frame portion, and at least A through hole for allowing fluid to pass through, the first sides of the two frame parts face each other, and the second sides of the two frame parts opposite to the respective first sides are respectively provided with at least one The liquid flow groove of the hollow part; a plurality of support members, the support members pass through the hollow part in the first direction and are connected to the frame part; and the diaphragm, the diaphragm is held in the hollow of the two frames by the support members partly on. The present invention also provides a liquid flow battery unit and a battery stack including the membrane assembly. The use of this membrane module can make the electrolyte more evenly distributed in the process of flowing in the diaphragm, reduce the internal resistance of the liquid flow battery unit, and improve the service life of the diaphragm.

Description

Membrane module, flow battery unit and battery stack

technical field

The present invention relates to a liquid flow battery, in particular to a membrane assembly, a flow battery unit and a battery stack including the membrane assembly.

Background technique

At present, with the intensification of energy shortage and environmental degradation, as an energy storage device, flow batteries have been widely used due to their long life, high reliability, and low operation and maintenance costs. In particular, an all-vanadium redox flow battery has been developed, which does not cause cross-contamination of positive and negative electrolytes, and vanadium ions are more suitable for high-current fast charging and discharging. All-vanadium redox flow batteries generally include end plates, bipolar plates, separators, electrode materials, electrode frames, sealing materials, etc.

Chinese patent application number CN200910157588.0 discloses an integrated device for flow batteries, including negative electrode flow frame, negative electrode, proton exchange membrane, positive electrode, positive electrode flow frame connected in sequence, between the proton exchange membrane and the flow frame The acid-resistant adhesive is bonded, and the positive electrode and the proton exchange membrane and the negative electrode and the proton exchange membrane are bonded together by conductive glue.

One of the characteristics of traditional flow batteries is the separation of power and capacity, that is, by using a pump, the electrolyte is driven from the electrolyte storage tank into the battery stack inlet, flows through each flow battery unit in the battery stack, and finally flows from the battery stack. The outlet flows out and returns to the electrolyte storage tank, so the cycle goes on and on.

The flow of electrolyte in the battery stack is a key factor affecting the performance of the battery stack. In flow battery technology, flow channels are usually processed on the electrode plate to solve the problem of uniform flow. However, in traditional flow batteries such as vanadium redox flow batteries, since the electrode liquid is highly corrosive to the material of the electrode plate (such as graphite), processing the liquid flow channel on the electrode plate will increase the The contact area with the electrolyte increases the degree of corrosion of the electrode plate. When the electrode plate is corroded, the oxidized groups (or oxides) generated on its surface will increase the internal resistance of the battery stack, and even corrode and perforate, causing electrolyte leakage, causing the battery to stop charging and discharging, and further corroding other components and equipment , causing environmental pollution.

In another conventional flow battery, a flow distribution structure is added in the inlet and outlet regions or inside of the electrolyte. However, adding a liquid flow distribution structure in the inlet and outlet areas can only allow the electrolyte to enter the working area more uniformly, and will not contribute to the flow of the electrolyte in the working area of the flow battery. Moreover, increasing the liquid flow distribution structure will Restricted by material performance and processing level, it also brings technical problems to the seal.

Contents of the invention

In order to solve the technical problem of uneven distribution of electrolyte in the working area of the battery in the prior art, the present invention provides a membrane module, a flow battery unit and a battery stack including the membrane module, and the membrane module can be used to The resistance drop of the electrolyte at each point in the battery working area is made more uniform, so that the electrolyte is distributed more evenly in the process of flowing in the battery working area, and finally the polarization potential of the flow battery unit is reduced, and the performance of the battery stack is improved.

In addition, the membrane assembly proposed by the present invention, as well as the flow battery unit and the battery stack including the membrane assembly, can reduce the flow resistance inside the battery stack while reducing the head loss of the liquid supply pump, and further improve the performance of the diaphragm. service life and improve the sealing performance of the battery stack.

According to an embodiment of an aspect of the present invention, there is provided a membrane assembly for a flow battery unit, comprising: two frames, each of which includes a frame portion and a hollow portion defined by the frame portion, and The frame portion is provided with at least one through hole for allowing fluid to pass through, the first sides of the two frame portions face each other, and the second sides of the two frame portions opposite to the respective first sides Two sides are respectively provided with at least one liquid flow groove extending from the through hole to the hollow part; a plurality of support members, the support members pass through the hollow part in the first direction and are connected to the frame part and a diaphragm held on the hollow portions of the two frames by the support.

In the above membrane assembly, the supporting members of the two frames are alternately arranged in parallel to support the diaphragm in a corrugated shape.

In the above membrane module, the liquid flow groove further extends along a second direction perpendicular to the first direction on an edge of the second side of the frame portion adjacent to the hollow portion to form a distribution groove.

In the above membrane module, the support member is integrally formed with the frame portion.

In the above-mentioned membrane module, the support member is connected to the frame part through a connecting member.

In the above membrane module, a plurality of grooves are formed on the first side of the frame portion, and the grooves are alternately arranged with the support members.

In the above membrane module, the frame is made of polytetrafluoroethylene or polyvinyl chloride.

According to another aspect of the present invention, a liquid flow battery unit is provided, comprising: two electrode plates, an annular electrode frame is provided on the outer edge of the electrode plates; two porous electrodes, each of which is arranged on The electrode plate is located in the electrode frame; and any one of the above-mentioned membrane components, the frame part of the membrane component is arranged between the two electrode frames, and the porous electrode corresponds to the hollow part and in contact with the diaphragm.

According to a further aspect of the present invention, a battery stack is provided, including a plurality of the above-mentioned flow battery units, and the plurality of flow battery units are stacked in sequence and electrically connected in series.

According to the flow battery unit and the battery stack according to the exemplary embodiments of the present invention, since the membrane assembly is used, the diaphragm forms a parallel flow guide structure, which can guide the electrolyte solution from the flow tank to be evenly distributed on the diaphragm. The support supports the porous electrode, thereby reducing the contact resistance between the porous electrode and the electrode plate. Further, the support member can prevent the diaphragm from being damaged due to stretching, rubbing, etc. of the diaphragm during assembly and working of the flow battery unit.

Description of drawings

In order to make the purpose, features and advantages of the present invention more obvious and understandable, the present invention will be further described below in conjunction with the accompanying drawings and specific embodiments, wherein:

1 is a schematic cross-sectional view showing a flow battery unit according to an exemplary embodiment of the present invention;

FIG. 2 is an exploded schematic view showing an exemplary embodiment of a membrane assembly of the flow battery unit shown in FIG. 1;

Fig. 3 is a schematic perspective view showing a frame of the membrane module shown in Fig. 2 viewed from the first side;

Fig. 4 is a schematic plan view showing a frame of the membrane assembly shown in Fig. 2 viewed from a second side;

Figure 5 is a side view showing the arrangement of the membranes of the membrane assembly shown in Figure 2;

Fig. 6 is a schematic diagram showing the assembly process of the membrane module shown in Fig. 2;

7 is a graph showing the voltage distribution on the electrode plate of a conventional flow battery unit;

8 is a graph showing the voltage distribution on the electrode plate of the flow battery unit according to the present invention;

FIG. 9 is a graph showing changes in charging voltage of a conventional flow battery unit and a flow battery unit according to the present invention;

FIG. 10 is a graph showing changes in discharge voltage of a conventional flow battery unit and a flow battery unit according to the present invention;

FIG. 11 is a comparative graph showing energy efficiency and electrolyte utilization of a conventional flow battery unit and a flow battery unit according to the present invention; and

FIG. 12 is a schematic side view showing a battery stack according to an embodiment of the present invention.

Detailed ways

While the present invention will be fully described with reference to the accompanying drawings containing preferred embodiments of the invention, it should be understood before proceeding that those skilled in the art may modify the invention described herein while obtaining the technical effects of the present invention. Therefore, it should be understood that the above description is a broad disclosure for those skilled in the art, and its content is not intended to limit the described exemplary embodiments of the present invention.

FIG. 1 is a schematic cross-sectional view showing a flow battery unit 100 according to an exemplary embodiment of the present invention. As shown in FIG. 1, the flow battery unit 100 according to the present invention includes: two electrode plates 2, each electrode plate 2 is provided with a ring-shaped electrode frame 21 on the outer edge; Two porous electrodes 3 made of gum base material, each porous electrode 3 is arranged on one side of the electrode plate 2 and is located in the electrode frame 21; membrane assembly 1 (will be described in detail below), and the membrane assembly 1 is located in Between two porous electrodes 3 .

2-5 are schematic diagrams showing an exemplary embodiment of the membrane assembly 1 of the flow battery unit 100 shown in FIG. 1 . According to an exemplary embodiment of the present invention, the membrane assembly 1 for the flow battery unit 100 includes: for example, two frame bodies 12 in a substantially ring shape, referring to FIGS. 2-4 , each frame body 12 includes The integrally connected frame portion 121 and the hollow portion defined by the frame portion 121 are provided with at least one through hole 124 for allowing fluid to pass through the frame portion 121, the first sides of the two frame portions 121 face each other, and the two The second side opposite to the respective first side of the frame portion 121 is respectively provided with at least one liquid flow groove 125 extending from the through hole 124 to the hollow portion 123; Up through the hollow portion 123 and connected to the frame portion 121 ; the diaphragm 11 is held on the hollow portion 123 of the two frame bodies 12 by the support member 122 .

In the membrane module 1 of the present invention, the frame body 12 is made of materials such as polytetrafluoroethylene, polyvinyl chloride (PVC), polyethylene (PE) or polypropylene (PP), and this material is for example vanadium The electrolyte has good corrosion resistance. The support member 122 is made of materials such as polyethylene, polyvinyl chloride, and acrylonitrile-butadiene-styrene copolymer. The plane shape of the frame body 12 is roughly rectangular, square, circular or oval, so as to form the external structure of the membrane module 1 . As shown in FIG. 4 , two through holes 124 for allowing the electrolyte to flow are formed on the frame portion 121 of the frame body 12 , and a hole extending from the through holes 124 to the hollow portion 123 is formed on the second side of the frame portion 121 . The liquid flow groove 125 , so that the electrolyte solution from the through hole 124 can flow to the diaphragm 11 provided at the hollow portion 123 through the liquid flow groove 125 . The diaphragm 11 can be an ion exchange membrane such as Nafion 117 membrane or sulfonated polyethersulfone, which can realize the conduction process of protons or ions in the electrochemical liquid flow, thereby completing the electrochemical reaction process. Further, a plurality of installation holes 127 are also provided on the frame part 121, through which connecting members such as bolts pass through the installation holes 127 and the installation holes on the electrode plate 2 and the electrode frame 21 to install the entire flow battery unit 100 together. In addition, a sealing groove 129 is provided on the outer edge of the frame part 121 of the housing 12 , for example, a sealing ring can be provided in the sealing groove 129 to realize the sealing connection between two adjacent frames 12 .

According to a characteristic exemplary embodiment of the present invention, the support member 122 is integrally formed with the frame portion 121, for example, by molding. Alternatively, the supporting member 122 may also be connected to the frame portion 121 through a buckle, a socket, or even welding. The supporting pieces 122 of the two frame bodies 12 are alternately arranged in parallel, so that, as shown in FIG. 5 , the supporting pieces 122 of the two frame bodies 12 are respectively located on both sides of the diaphragm 11 and support the diaphragm 11 in a corrugated shape. The corrugated shape formed by the support member 122 can make the diaphragm 11 form a parallel flow guide structure, so as to guide the electrolyte solution from the liquid flow tank 125 to evenly distribute to the working area of the battery. The support member 122 also supports the porous electrode 3 , thereby reducing the contact resistance between the porous electrode 3 and the electrode plate 2 . Further, the use of the support member 122 can prevent the diaphragm 11 from being damaged due to stretching, rubbing, etc. of the diaphragm 11 during assembly and operation of the flow battery unit 100 .

According to a further embodiment of the present invention, the liquid flow groove 125 is further extended along the second direction perpendicular to the first direction (the extending direction of the support member 122 in FIG. 4 ) on the edge of the second side of the frame portion 121 adjacent to the hollow portion 123 The extension forms the distribution groove 126 . The distribution groove 126 spans the entire length of one side of the diaphragm 11 , so that the electrolyte solution can be more evenly distributed on the diaphragm 11 . Further, a plurality of grooves 128 are formed on the first side of the frame portion 122, and the grooves 128 are alternately arranged with the support members 122, and the grooves 128 on the two opposite frame portions 121 are kept corresponding, that is, a concave-convex fit is formed, Thus, the two frame bodies 12 are more closely combined. And the diaphragm 11 is formed into a corrugated shape.

Fig. 6 is a schematic diagram showing the assembly process of the membrane module according to the present invention. Firstly, install the support member 122 across the hollow portion 123 of the frame body 12 to the preset position of the frame portion 121; then, lay the diaphragm 11 on one of the installed frame bodies 12, and then install the other Once the frame body 12 with the supporting member 122 installed, it is locked with a fastening member, and the installation is completed. In particular, as shown in Figure 6, when two frames 12 are installed, one side of the upper and lower frames 12 is used as an "axis", one end of the diaphragm 11 is pressed, and the other end of the diaphragm 11 is kept loose, and then Evenly rotate the two frame bodies 12 toward the diaphragm 11 with the axis as the center of the circle, finally combine the two frame bodies 12, and then lock them with fastening parts, and the installation is completed.

Referring to Fig. 1 again, the flow battery unit 100 according to the present invention includes: two electrode plates 2, each electrode plate 2 is provided with a ring-shaped electrode frame 21 on the outer edge; two porous electrodes 3, each porous electrode 3 are arranged on one side of the electrode plate 2 and located in the electrode frame 21; the membrane assembly 1, the frame portion 121 of the membrane assembly 1 is arranged between the two electrode frames 21, and the porous electrode 3 corresponds to the hollow portion 123 And in contact with the diaphragm 11.

The following describes some performance curves of the conventional flow battery unit and the flow battery unit 100 according to the present invention obtained according to experiments with reference to FIGS. 7-11 . It should be noted that, except for the membrane module 1 , other structures and working conditions of the conventional flow battery unit are the same as those of the flow battery unit 100 according to the present invention. Wherein, FIG. 7 is a graph showing the voltage distribution on the electrode plate of the conventional flow battery unit; FIG. 8 is a graph showing the voltage distribution on the electrode plate of the flow battery unit according to the present invention. It can be seen from Figures 7 and 8 that in the flow battery unit of the present invention, since the electrolyte distribution in the working area of the battery unit 100 is more uniform, the voltage values at different positions on the electrode plate 2 are relatively more uniform, and the polarization potential lower.

9 is a graph showing the change in voltage of a conventional flow battery unit and a flow battery unit according to the present invention during charging, and FIG. 10 is a graph showing the voltage changes of a conventional flow battery unit and a flow battery unit according to the present invention during discharge. change graph. It can be seen from Fig. 9 and Fig. 10 that the charging voltage of the flow battery unit 100 using the membrane module 1 according to the present invention is slightly lower than that of the traditional flow battery unit, while the discharge voltage of the flow battery unit 100 of the present invention is Slightly higher than the discharge voltage of conventional flow battery cells. Therefore, it can be explained that the total internal resistance of the flow battery of the flow battery unit 100 of the present invention using the membrane module is relatively small when working online.

FIG. 11 is a graph showing the comparison of energy efficiency and electrolyte utilization of a conventional flow battery unit and a flow battery unit according to the present invention. Among them, energy efficiency is the ratio of battery output energy to input energy, which is the main indicator for evaluating battery performance, and electrolyte utilization refers to the ratio of actual battery storage capacity to theoretical battery storage capacity. In terms of efficiency, the flow battery unit 100 of the present invention has a 4% higher power generation efficiency than the traditional flow battery unit, and the flow battery unit 100 of the present invention has a flow battery discharge capacity ( That is, the utilization rate of the electrolyte) is about 9% higher. Therefore, compared with the conventional flow battery unit, the flow battery unit 100 according to the present invention has reduced internal resistance of the flow battery, and improved energy efficiency and electrolyte utilization.

According to a further embodiment of the present invention, as shown in FIG. 12 , the battery stack 10 of the present invention includes a plurality of flow battery units 100 connected in series in sequence, electrolyte solution inlets and outlets 102 on the two outermost flow battery units, End caps 103 packaged outside the two outermost flow battery units, and connecting devices 104 such as bolts, which are used to connect the two end caps 103 so as to assemble the entire battery stack 10 together .

In the flow battery unit and the battery stack according to the above embodiments of the present invention, since the membrane assembly 1 is used, the diaphragm 11 forms a parallel flow guide structure, which can guide the electrolyte from the flow tank 125 to be evenly distributed to the battery working area superior. The support member 122 supports the porous electrode 3 so as to reduce the contact resistance between the porous electrode 3 and the electrode plate 2 . Further, the use of the support member 122 can prevent the diaphragm 11 from being damaged due to stretching, rubbing, etc. of the diaphragm 11 during assembly and operation of the flow battery unit 100 .

After describing the preferred embodiments of the present invention in detail, those skilled in the art can clearly understand that various changes and changes can be made without departing from the scope and spirit of the appended claims, and the present invention is not limited by Implementation is limited to the exemplary embodiments set forth in the specification.

Claims (9)

1. A membrane assembly for a flow battery unit, comprising: Two frame bodies, each frame body includes a frame portion and a hollow portion defined by the frame portion, at least one through hole for allowing fluid to pass is provided on the frame portion, the two frame portions The first sides face each other, and the second sides of the two frame parts opposite to the respective first sides are respectively provided with at least one liquid flow groove extending from the through hole to the hollow part; a plurality of supports connected to the frame portion through the hollow portion in a first direction; and and a diaphragm held on the hollow portions of the two frames by the support. 2. The membrane module according to claim 1, wherein the support members of the two frames are alternately arranged in parallel to support the diaphragm in a corrugated shape. 3. The membrane module according to claim 1, wherein the liquid flow groove is along a second direction perpendicular to the first direction on an edge of the second side of the frame portion adjacent to the hollow portion. The direction is further extended to form distribution grooves. 4. The membrane module according to any one of claims 1-3, wherein the support member is integrally formed with the frame portion. 5. The membrane module according to any one of claims 1-3, wherein the supporting member is connected to the frame part through a connecting member. 6. The membrane module according to any one of claims 1-3, wherein a plurality of grooves are formed on the first side of the frame portion, and the grooves are alternately arranged with the support members. 7. The membrane module according to any one of claims 1-3, wherein the frame body is made of polytetrafluoroethylene or polyvinyl chloride. 8. A flow battery unit, comprising: Two electrode plates, the outer edges of the electrode plates are provided with a ring-shaped electrode frame; two porous electrodes each disposed on the electrode plate and within the electrode frame; and The membrane module according to any one of claims 1-7, the frame part of the membrane module is arranged between the two electrode frames, the porous electrode corresponds to the hollow part and is connected to the Diaphragm contact. 9. A battery stack, comprising a plurality of the flow battery units according to claim 8, the plurality of the flow battery units are stacked in sequence and electrically connected in series.

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