CN105702976A - Electrode, flow cell and flow cell stack - Google Patents

Abstract

The invention provides an electrode, a flow battery and a flow battery stack. Wherein, the electrode includes a first electrode layer, the first electrode layer has a first surface and a second surface opposite, and the electrode also includes a second electrode layer arranged on the first surface and/or a second electrode layer arranged on the second surface. Three electrode layers, the number of reactive sites in the second electrode layer is greater than the number of reactive sites in the first electrode layer, and the number of reactive sites in the third electrode layer is greater than the number of reactive sites in the first electrode layer. After the electrode is applied to the flow battery, the area of the electrode layer group close to the ion exchange membrane and/or bipolar plate can have a larger number of reactive sites than the remaining area, so that not only can the electrode thickness be increased without increasing the electrode thickness On the basis of making the number of reactive sites in the electrode meet the needs of the flow battery, the increase in internal resistance of the battery can be effectively reduced by adjusting the thickness of the electrode, and the voltage efficiency of the flow battery can be improved.

Description

Electrodes, flow batteries and flow battery stacks

technical field

The present invention relates to the technical field of flow batteries, in particular, to an electrode, a flow battery and a flow battery stack.

Background technique

Due to the separation of the electrolyte for energy storage and the battery stack for energy conversion, flow batteries have the advantages of high safety, flexible power and capacity design, long life, and low maintenance costs, and have been widely used in various energy storage fields. .

For the existing flow battery stack, on the one hand, in order to improve the voltage efficiency of the battery, it is necessary to reduce the internal resistance of the battery, and then it is necessary to reduce the thickness of the electrode or increase the number of reactive sites of the electrode; on the other hand, in order to improve The power density of the battery needs to be increased to increase the current density. In order for the battery to withstand a greater current density, it is necessary to increase the number of reactive sites on the electrode.

For each electrode, a uniform carbon felt is usually used as a stack in the prior art. When the number of reactive sites per unit volume of carbon felt is determined, in order to keep the reaction area constant, only by increasing the carbon felt Thickness to increase reactive active sites. However, increasing the thickness of the carbon felt increases the internal resistance of the battery, resulting in a drop in voltage efficiency.

Contents of the invention

The main purpose of the present invention is to provide an electrode, a flow battery and a flow battery stack to solve the problem of low voltage efficiency of the flow battery in the prior art.

In order to achieve the above object, according to one aspect of the present invention, an electrode is provided, including a first electrode layer, the first electrode layer has a first surface and a second surface opposite to each other, and the electrode further includes a first electrode layer disposed on the first surface. Two electrode layers and/or a third electrode layer arranged on the second surface, the number of reactive sites of the second electrode layer is greater than the number of reactive sites of the first electrode layer, the number of reactive sites of the third electrode layer greater than the number of reactive active sites of the first electrode layer.

Further, the ratio of the number of reactive sites of the second electrode layer to that of the first electrode layer is greater than 1.05; the ratio of the number of reactive sites of the third electrode layer to the first electrode layer is greater than 1.05.

Further, the specific surface area per unit volume of the second electrode layer is greater than the specific surface area per unit volume of the first electrode layer; the specific surface area per unit volume of the third electrode layer is greater than the specific surface area per unit volume of the first electrode layer.

Further, the ratio of the specific surface area per unit volume of the second electrode layer to the first electrode layer is greater than 1.05; the ratio of the specific surface area per unit volume of the third electrode layer to the first electrode layer is greater than 1.05.

Further, the first electrode layer includes a plurality of sub-electrode layers stacked sequentially along a direction from the first surface to the second surface.

Further, when the electrode includes the second electrode layer, the number of reactive sites of each sub-electrode layer decreases sequentially along the direction from the first surface to the second surface.

Further, when the electrode includes the third electrode layer, the number of reactive sites of each sub-electrode layer increases sequentially along the direction from the first surface to the second surface.

Further, when the electrode includes a second electrode layer and a third electrode layer, the number of reactive sites of the sub-electrode layer close to the first surface and the sub-electrode layer close to the second surface is greater than the reactive sites of the remaining sub-electrode layers number of points.

Further, the material forming the first electrode layer is carbon felt; the material forming the second electrode layer is selected from any one of carbon paper, electrochemically modified carbon felt and hydrophilic modified carbon felt or Various; the material forming the third electrode layer is selected from any one or more of carbon paper, electrochemically modified carbon felt and hydrophilically modified carbon felt.

According to another aspect of the present invention, a liquid flow battery is provided, including a bipolar plate, a flow frame, an electrode and an ion exchange membrane, and the electrode is the above-mentioned electrode, wherein, when the electrode includes a second electrode layer, the second The electrode layer is disposed adjacent to the ion exchange membrane; when the electrode includes a third electrode layer, the third electrode layer is disposed adjacent to the bipolar plate.

According to another aspect of the present invention, a flow battery stack is also provided, including a plurality of flow batteries, and the flow batteries are the above-mentioned flow batteries.

Applying the technical solution of the present invention provides an electrode that further includes a second electrode layer and/or a third electrode layer on the basis of including the first electrode layer, because the number of reactive active sites of the second electrode layer is greater than that of the first electrode layer The number of reactive sites of the electrode layer, the number of reactive sites of the third electrode layer is greater than the number of reactive sites of the first electrode layer, so that after the electrode is applied to the flow battery, the second electrode layer is close to the ion exchange membrane and/or the third electrode layer is arranged close to the surface of the bipolar plate, so that the area of the electrode layer group close to the ion exchange membrane and/or the bipolar plate can have a larger number of reactive sites than the remaining area Therefore, not only can the number of reactive sites in the electrode meet the needs of the flow battery without increasing the thickness of the electrode, but also can effectively reduce the increase in the internal resistance of the battery by adjusting the thickness of the electrode, and improve the flow battery’s performance. Voltage efficiency; and, due to the inhomogeneity of the reaction existing in the electrode of the flow battery, a larger reaction current density is required in the area near the ion exchange membrane and near the bipolar plate, thereby by improving the above electrode near the ion exchange membrane and the The number of reactive sites in the region of the/or bipolar plate increases the reaction current density in the desired region, thereby increasing the power density of the flow battery.

In addition to the objects, features and advantages described above, the present invention has other objects, features and advantages. Hereinafter, the present invention will be described in further detail with reference to the drawings.

Description of drawings

The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention, and the schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations to the present invention. In the attached picture:

Fig. 1 shows the structural representation of the electrode provided by the present invention;

Figure 2 shows a schematic diagram of a three-dimensional split structure of a flow battery provided by the present invention;

Fig. 3 shows a schematic structural view of a flow battery including a second electrode layer provided by the present invention;

Fig. 4 shows a schematic structural view of a flow battery including a third electrode layer provided by the present invention; and

Fig. 5 shows a schematic structural view of a flow battery including a second electrode layer and a third electrode layer provided by the present invention.

detailed description

It should be noted that, in the case of no conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and examples.

In order to enable those skilled in the art to better understand the solutions of the present invention, the following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only It is an embodiment of a part of the present invention, but not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts shall fall within the protection scope of the present invention.

It should be noted that the terms "first" and "second" in the description and claims of the present invention and the above drawings are used to distinguish similar objects, but not necessarily used to describe a specific sequence or sequence. It should be understood that the data so used may be interchanged under appropriate circumstances for the embodiments of the invention described herein. Furthermore, the terms "comprising" and "having", as well as any variations thereof, are intended to cover a non-exclusive inclusion, for example, a process, method, system, product or device comprising a sequence of steps or elements is not necessarily limited to the expressly listed instead, may include other steps or elements not explicitly listed or inherent to the process, method, product or apparatus.

As introduced in the background technology, in order to increase the power density of the battery in the prior art, it is necessary to increase the number of reactive sites of the electrode. However, in order to keep the reaction area unchanged, the only way to increase the reactive sites is to increase the thickness of the carbon felt. At the same time, increasing the thickness of the carbon felt will increase the internal resistance of the battery, resulting in a decrease in voltage efficiency. The inventors of the present invention have studied the above-mentioned problems and proposed an electrode. As shown in FIG. It also includes a second electrode layer 320 disposed on the first surface and/or a third electrode layer 330 disposed on the second surface, and when the electrode includes the second electrode layer 320, the reactive sites of the second electrode layer 320 The number of dots is greater than the number of reactive sites of the first electrode layer 310 , and when the electrode includes the third electrode layer 330 , the number of reactive sites of the third electrode layer 330 is greater than the number of reactive sites of the first electrode layer 310 .

In the above electrodes, since the number of reactive sites of the second electrode layer 320 is greater than the number of reactive sites of the first electrode layer 310, the number of reactive sites of the third electrode layer 330 is greater than the number of reactive sites of the first electrode layer 310 Therefore, after the electrode is applied to the flow battery, when the electrode includes the second electrode layer 320, the second electrode layer 320 is arranged on the surface of the ion exchange membrane; when the electrode includes the third electrode layer 330, the second electrode layer 320 The three-electrode layer 330 is arranged on the surface of the bipolar plate, so that the area close to the ion exchange membrane and/or bipolar plate in the electrode layer group can have a larger number of reactive sites than the remaining area, so that not only can the On the basis of not increasing the thickness of the electrode, the number of reactive sites in the electrode can meet the needs of the flow battery, and the increase in the internal resistance of the battery can be effectively reduced by adjusting the thickness of the electrode, and the voltage efficiency of the flow battery can be improved; and, because The inhomogeneity of the reaction in the electrodes of the flow battery requires a larger reaction current density in the area close to the ion exchange membrane and the bipolar plate, so that by increasing the The number of reactive sites in the region increases the reaction current density in the desired region, thereby increasing the power density of the flow battery.

The number of reactive sites in the present application is the same as the concept of the number of reactive sites in the prior art, and both refer to the number of positions in the electrode where electrochemical reactions can occur. In a preferred embodiment, the electrode includes a second electrode layer 320 disposed on the first surface, and after the electrode is applied to a flow battery, the second electrode layer 320 is disposed on the surface of the ion exchange membrane; In another preferred embodiment, the above electrode includes a third electrode layer 330 disposed on the second surface, and after the electrode is applied to a flow battery, the third electrode layer 330 is disposed on the surface of the bipolar plate; the above The electrode can also include a second electrode layer 320 arranged on the first surface and a third electrode layer 330 arranged on the second surface, the second electrode layer 320 is arranged on the surface of the ion exchange membrane, and the third electrode layer 330 is arranged on the surface of the ion exchange membrane. on the surface of the bipolar plate.

When the above electrode includes the second electrode layer 320 , preferably, the ratio of the number of reactive sites of the second electrode layer 320 to that of the first electrode layer 310 is greater than 1.05. Limiting the number of reactive sites of the first electrode layer 310 and the second electrode layer 320 within the above-mentioned preferred ratio range can ensure that the second electrode layer 320 has a large number of reactive sites, while making the first electrode The layer 310 has a smaller number of reactive sites, so that the electrode can not only have a smaller thickness, but also have a smaller internal resistance, and then after the electrode is applied to the flow battery, the performance of the flow battery can be further improved. Voltage efficiency; And, after this electrode is applied to liquid flow battery, by making the second electrode layer 320 close to ion exchange membrane have larger number of reactive sites, satisfy the reaction current of the region close to ion exchange membrane in the electrode The demand for density further increases the reaction current density in the required area, which further increases the power density of the flow battery.

When the above electrode includes the third electrode layer 330 , preferably, the ratio of the number of reactive sites of the third electrode layer 330 to that of the first electrode layer 310 is greater than 1.05. Limiting the number of reactive sites of the first electrode layer 310 and the third electrode layer 330 within the above-mentioned preferred ratio range can ensure that the third electrode layer 330 has a large number of reactive sites, while making the first electrode The layer 310 has a smaller number of reactive sites, so that the electrode not only has a smaller thickness, but also has a smaller internal resistance, and then the electrode is applied to the flow battery, which can further improve the flow battery. Voltage efficiency; and, after applying the electrode to the flow battery, by making the third electrode layer 330 close to the bipolar plate have a larger number of reactive sites, the reaction current in the region close to the bipolar plate is satisfied. The demand for density further increases the reaction current density in the required area, which further increases the power density of the flow battery.

In the above electrode of the present invention, when the number of reactive sites of the second electrode layer 320 is greater than the number of reactive sites of the first electrode layer 310, preferably, the specific surface area per unit volume of the second electrode layer 320 is larger than that of the first electrode layer 320. The specific surface area per unit volume of the electrode layer 310 . The specific surface area per unit volume refers to the total surface of the porous medium per unit volume. Therefore, making the second electrode layer 320 have a larger specific surface area per unit volume than the first electrode layer 310 can be achieved without increasing the first electrode layer. 310, by forming the first electrode layer 310 and the second electrode layer 320 with the same thickness, even making the second electrode layer 320 have a smaller volume than the first electrode layer 310, it is possible to make the second The number of reactive sites of the electrode layer 320 is greater than that of the first electrode layer 310, thereby effectively controlling the overall thickness of the electrode.

In the above preferred embodiment, more preferably, the ratio of the specific surface area per unit volume of the second electrode layer 320 to that of the first electrode layer 310 is greater than 1.05. Setting the specific surface area per unit volume of the second electrode layer 320 and the first electrode layer 310 within the above-mentioned preferred range can be based on the fact that the second electrode layer 320 has a smaller volume than the first electrode layer 310, The number of reactive sites of the second electrode layer 320 is greater than that of the first electrode layer 310, thereby further reducing the overall thickness of the electrode.

In the above electrode of the present invention, when the number of reactive sites in the third electrode layer 330 is greater than the number of reactive sites in the first electrode layer 310, preferably, the specific surface area per unit volume of the third electrode layer 330 is larger than that of the first electrode layer 330. The specific surface area per unit volume of the electrode layer 310 . Similarly, making the third electrode layer 330 have a larger specific surface area per unit volume than the first electrode layer 310, it is possible to form the first electrode layer with the same thickness without increasing the volume of the first electrode layer 310. 310 and the third electrode layer 330, even if the third electrode layer 330 has a smaller volume than the first electrode layer 310, the number of reactive sites in the third electrode layer 330 can be greater than that of the first electrode layer 310 The number of reactive sites effectively controls the overall thickness of the electrode.

In the above preferred embodiment, more preferably, the ratio of the specific surface area per unit volume of the third electrode layer 330 to that of the first electrode layer 310 is greater than 1.05. Setting the specific surface area per unit volume of the third electrode layer 330 and the first electrode layer 310 within the above preferred range can also be based on the fact that the third electrode layer 330 has a smaller volume than the first electrode layer 310 , the number of reactive sites of the third electrode layer 330 is greater than the number of reactive sites of the first electrode layer 310, thereby further reducing the overall thickness of the electrode.

Among the above-mentioned electrodes of the present invention, preferably, the first electrode layer 310 includes a plurality of sub-electrode layers stacked sequentially along the direction from the first surface to the second surface. Since the above-mentioned first electrode layer 310 includes a plurality of sub-electrode layers, after this electrode is applied to a flow battery, the number of reactive active sites at different positions in the electrode can be adjusted by adjusting the number of reactive active sites in each sub-electrode layer. adjustment, thereby more effectively controlling the thickness of the electrode, reducing the increase in the internal resistance of the battery, and improving the voltage efficiency of the flow battery; and, it is also possible to adjust each sub-electrode layer, the second electrode layer 320 and the third electrode The number of reactive sites in the layer 330 makes the number of reactive sites in the electrode gradually increase from the middle to both sides, which further satisfies the demand for the reaction current density in the area close to the ion exchange membrane and the bipolar plate, thereby passing Increasing the reaction current density in the desired area increases the power density of the flow battery.

In the above-mentioned electrode including multiple sub-electrode layers, preferably, when the electrode includes the second electrode layer 320 , the number of reactive sites of each sub-electrode layer decreases sequentially along the direction from the first surface to the second surface. Due to the inhomogeneity of the reaction in the electrodes of the flow battery, a larger reaction current density is required in the area close to the ion exchange membrane, and the reaction current density gradually decreases in the direction of the ion exchange membrane pointing to the bipolar plate, so that the above After the electrode is applied to the flow battery, the side of the electrode close to the ion exchange membrane has a larger number of reactive sites, and the number of reactive sites in the area closer to the ion exchange membrane is larger, further improving the Reactive current density in the desired area, which in turn increases the power density of the flow battery.

In the above-mentioned electrode including multiple sub-electrode layers, preferably, when the electrode includes the third electrode layer 330 , the number of reactive sites of each sub-electrode layer increases sequentially along the direction from the first surface to the second surface. Due to the inhomogeneity of the reaction in the electrodes of the flow battery, a larger reaction current density is required in the area close to the bipolar plate, and the reaction current density gradually decreases in the direction of the bipolar plate pointing to the ion exchange membrane, so that the above After the electrode is applied to the flow battery, by making the side of the electrode close to the bipolar plate have a larger number of reactive sites, and the closer to the bipolar plate, the number of reactive sites is larger, further improving the Reactive current density in the desired area, which in turn increases the power density of the flow battery.

In the above electrode comprising a plurality of sub-electrode layers, preferably, when the electrode comprises the second electrode layer 320 and the third electrode layer 330, the reactive sites of the sub-electrode layer close to the first surface and the sub-electrode layer of the second surface The number of dots is greater than the number of reactive sites in the remaining sub-electrode layers; more preferably, the number of reactive sites in the electrode directed from the middle to the first surface and the second surface gradually increases to better meet the requirements of the liquid The flow battery requires the distribution of the reaction current density in the electrodes, thereby effectively increasing the reaction current density in the required area, thereby increasing the power density of the flow battery.

In the above electrodes of the present invention, preferably, the material forming the first electrode layer 310 is carbon felt; the material forming the second electrode layer 320 is independently selected from carbon paper, electrochemically modified carbon felt, and hydrophilic modified carbon felt. Any one or more of carbon felts after properties; the material forming the third electrode layer 330 is selected from any one of carbon paper, electrochemically modified carbon felts, and hydrophilic modified carbon felts one or more species. The above-mentioned electrochemically modified carbon felt refers to increasing the number of effective functional groups of the material. The modification treatment method can be to place the carbon felt at 400 degrees Celsius for 8 hours or longer, or place the carbon felt in an aqueous hydrogen peroxide solution Processing at 80 degrees Celsius for more than 4 hours, etc. Using the above-mentioned carbon paper or the modified material can ensure that the number of reactive sites of the second electrode layer 320 and the third electrode layer 330 is greater than the number of reactive sites of the first electrode layer 310, so that the above-mentioned electrode is applied to liquid flow After the battery, the voltage efficiency and power density of the flow battery are improved.

According to another aspect of the present invention, a liquid flow battery is provided, as shown in FIGS. The first electrode layer 310, and when the electrode 30 also includes the second electrode layer 320, the second electrode layer 320 is set close to the ion exchange membrane 40; when the electrode also includes the third electrode layer 330, the third electrode layer 330 is close to the bipolar Plate 10 set.

In the above-mentioned flow battery, because the second electrode layer 320 is arranged on the surface of the ion exchange membrane 40, and the third electrode layer 330 is arranged on the surface of the bipolar plate 10, so that the electrode layer group is close to the ion exchange membrane 40 and/or The area of the bipolar plate 10 can have a larger number of reactive sites than the remaining area, and then by controlling the thickness of the electrode 30, the increase in the internal resistance of the battery can be effectively reduced, and the voltage efficiency of the flow battery can be improved; Moreover, due to the inhomogeneity of the reaction existing in the electrode 30 of the flow battery, a larger reaction current density is required in the area close to the ion exchange membrane 40 and the bipolar plate 10, thereby increasing the 40 and/or the number of reactive sites in the area of the bipolar plate 10 increases the reaction current density in the desired area, thereby increasing the power density of the flow battery.

In the above-mentioned flow battery of the present invention, the bipolar plate 10 plays the role of collecting charge and discharge reaction charge and compressing the electrode 30 . Preferably, the bipolar plate 10 is made of metal material, or conductive polymer material, or carbon/polymer composite material, or carbon material. Metal materials, or conductive polymer materials, or carbon/polymer composite materials, or carbon materials have the characteristics of high hardness and easy realization of high-precision machining. The ion exchange membrane 40 in the present invention is generally a perfluorosulfonic acid membrane, a semifluorosulfonic acid membrane or a non-fluorosulfonic acid membrane. By placing two planar electrodes 30 and ion exchange membranes 40 between two bipolar plates 10, and then making the two bipolar plates 10 approach and squeeze the electrodes 30 and ion exchange membranes under the assembly force of the flow battery stack The exchange membrane 40 makes the electrode 30, the ion exchange membrane 40 and the bipolar plate 10 closely adhere to and completely match each other, so as to complete the assembly of the flow battery.

In a preferred embodiment, the electrode 30 includes a second electrode layer 320 disposed on the first surface. At this time, the second electrode layer 320 is disposed on the surface of the ion exchange membrane 40, and the formed flow battery is as follows: As shown in FIG. 3; in another preferred embodiment, the above-mentioned electrode 30 includes a third electrode layer 330 disposed on the second surface, and at this time, the third electrode layer 330 is disposed on the surface of the bipolar plate 10, The constituted flow battery is shown in Figure 4; the electrode 30 may also include a second electrode layer 320 disposed on the first surface and a third electrode layer 330 disposed on the second surface, the second electrode layer 320 is disposed on the ion On the surface of the exchange membrane 40 , the third electrode layer 330 is disposed on the surface of the bipolar plate 10 , and the formed flow battery is shown in FIG. 5 .

According to still another aspect of the present invention, there is provided a flow battery stack including a plurality of flow batteries, each flow battery has the above-mentioned electrodes, and when the electrodes include a second electrode layer, the second electrode layer is close to the ion exchange Membrane arrangement, when the electrode includes a third electrode layer, the third electrode layer is arranged adjacent to the bipolar plate. The above-mentioned flow battery stack uses the above-mentioned flow battery as the basic unit, and multiple sections are sequentially stacked and compacted and connected in series. By improving the voltage efficiency and power density of the flow battery, the voltage efficiency and power of the flow battery stack are improved. density.

The electrodes and flow batteries provided by the present application will be further described below in conjunction with examples and comparative examples.

Example 1

The flow battery provided in this embodiment is shown in Figure 3, and includes a bipolar plate, a flow frame, an electrode and an ion exchange membrane, wherein the electrode includes a first electrode layer and a first electrode layer disposed on the first surface of the first electrode layer The second electrode layer, the second electrode layer is set close to the ion exchange membrane, the ratio of the number of reactive sites between the second electrode layer and the first electrode layer is 1.05:1, and the unit volume of the second electrode layer and the first electrode layer The ratio of specific surface area is 1.05:1;

Wherein, the material forming the bipolar plate is a graphite plate, the ion exchange membrane is a perfluorosulfonic acid membrane, the material forming the first electrode layer is unmodified carbon felt, and the material forming the second electrode layer is charcoal paper.

Example 2

The flow battery provided in this embodiment is shown in Figure 4, and includes a bipolar plate, a flow frame, an electrode and an ion exchange membrane, wherein the electrode includes a first electrode layer and an electrode disposed on the second surface of the first electrode layer. The third electrode layer, the third electrode layer is arranged close to the bipolar plate, the ratio of the number of reactive sites between the third electrode layer and the first electrode layer is 1.05:1, and the unit volume of the third electrode layer and the first electrode layer The ratio of specific surface area is 1.05:1;

Wherein, the material forming the bipolar plate is a graphite plate, the ion exchange membrane is a perfluorosulfonic acid membrane, the material forming the first electrode layer is unmodified carbon felt, and the material forming the third electrode layer is charcoal paper.

Example 3

The flow battery provided in this embodiment is shown in Figure 5, and includes a bipolar plate, a flow frame, an electrode and an ion exchange membrane, wherein the electrode includes a first electrode layer and a second electrode layer respectively arranged on the first surface And the third electrode layer arranged on the second surface, the second electrode layer is arranged near the ion exchange membrane, the third electrode layer is arranged near the bipolar plate, the reactivity of the third electrode layer, the second electrode layer and the first electrode layer The ratio of the number of sites is 1.05:1.05:1, and the ratio of the specific surface area per unit volume of the third electrode layer, the second electrode layer and the first electrode layer is 1.05:1.05:1;

Wherein, the material forming the bipolar plate is a graphite plate, the ion exchange membrane is a perfluorosulfonic acid membrane, the material forming the first electrode layer is unmodified carbon felt, and the material forming the second electrode layer is carbon paper, and the material for forming the third electrode layer is carbon paper.

Example 4

The difference between the flow battery provided in this embodiment and Embodiment 1 is:

The ratio of the number of reactive sites of the second electrode layer to the first electrode layer is 1.1:1, and the ratio of the specific surface area per unit volume of the second electrode layer to the first electrode layer is 1.1:1, and the above-mentioned first electrode is formed The layer material is unmodified carbon felt, and the material forming the second electrode layer is hydrophilically modified carbon felt.

Example 5

The difference between the flow battery provided in this embodiment and that in Embodiment 2 is:

The ratio of the number of reactive sites of the third electrode layer to the first electrode layer is 1.1:1, and the ratio of the specific surface area per unit volume of the third electrode layer to the first electrode layer is 1.1:1, and the above-mentioned first electrode is formed The layer material is unmodified carbon felt, and the material forming the third electrode layer is hydrophilic modified carbon felt.

Example 6

The difference between the flow battery provided in this embodiment and that in Embodiment 3 is:

The ratio of the number of reactive sites of the third electrode layer, the second electrode layer and the first electrode layer is 10 ⁴ : 10 ³ : 1, and the unit volume ratio of the third electrode layer, the second electrode layer and the first electrode layer The surface area ratio is 10 ⁴ : 10 ³ : 1, and the material for forming the first electrode layer is unmodified carbon felt, and the material for forming the second electrode layer is electrochemically modified carbon felt. The material of the three electrode layers is electrochemically modified carbon felt.

Comparative example 1

The flow battery provided in this comparative example includes a bipolar plate, a flow frame, an electrode layer and an ion exchange membrane, wherein the above electrode layer adopts the first electrode layer in Example 1, and is arranged between the ion exchange membrane and the bipolar plate between;

Wherein, the material forming the bipolar plate is a graphite plate, and the material forming the ion exchange membrane is a perfluorosulfonic acid membrane.

The voltage efficiency of the flow battery provided in the above-mentioned Examples 1 to 6 and Comparative Example 1 was tested, and the test results are as follows:

voltage efficiency Comparative example 1 88.0% Example 1 90.1% Example 2 90.1% Example 3 91.3% Example 4 91.6% Example 5 91.6% Example 6 92.2%

It can be seen from the above test results that the flow batteries provided in Examples 1 to 6 of the present application have higher voltage efficiency than Comparative Example 1.

From the above description, it can be seen that the above-mentioned embodiments of the present invention have achieved the following technical effects:

1. Make the area close to the ion exchange membrane and/or bipolar plate in the electrode layer group have a larger number of reactive sites than the remaining area, so that not only the electrode thickness can be increased without increasing the electrode thickness. The number of reactive sites meets the needs of the flow battery, and can also effectively reduce the increase in internal resistance of the battery by adjusting the thickness of the electrode, improving the voltage efficiency of the flow battery;

2. By increasing the number of reactive sites in the region near the ion exchange membrane and/or bipolar plate in the above electrodes, the reaction current density in the desired region is increased, thereby increasing the power density of the flow battery.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and changes. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims (11)

1. an electrode, including the first electrode layer (310), described first electrode layer (310) has relative first surface and second surface, it is characterized in that, described electrode also includes the second electrode lay (320) being arranged on described first surface and/or the 3rd electrode layer (330) being arranged on described second surface, the reactivity number of loci of described the second electrode lay (320) is more than the reactivity number of loci of described first electrode layer (310), the reactivity number of loci of described 3rd electrode layer (330) is more than the reactivity number of loci of described first electrode layer (310)。

2. electrode according to claim 1, it is characterised in that

The ratio of the reactivity number of loci of described the second electrode lay (320) and described first electrode layer (310) is more than 1.05；

The ratio of the reactivity number of loci of described 3rd electrode layer (330) and described first electrode layer (310) is more than 1.05。

3. electrode according to claim 1, it is characterised in that

The unit volume specific surface area of described the second electrode lay (320) is more than the unit volume specific surface area of described first electrode layer (310)；

The unit volume specific surface area of described 3rd electrode layer (330) is more than the unit volume specific surface area of described first electrode layer (310)。

4. electrode according to claim 3, it is characterised in that

The ratio of the unit volume specific surface area of described the second electrode lay (320) and described first electrode layer (310) is more than 1.05；

The ratio of the unit volume specific surface area of described 3rd electrode layer (330) and described first electrode layer (310) is more than 1.05。

5. electrode according to claim 1, it is characterised in that described first electrode layer (310) includes pointing to multiple sub-electrode layers of order stacking on the direction of described second surface along described first surface。

6. electrode according to claim 5, it is characterized in that, when described electrode includes described the second electrode lay (320), point to the reactivity number of loci of each described sub-electrode layer on the direction of described second surface along described first surface and reduce successively。

7. electrode according to claim 5, it is characterized in that, when described electrode includes described 3rd electrode layer (330), point to the reactivity number of loci of each described sub-electrode layer on the direction of described second surface along described first surface and increase successively。

8. electrode according to claim 5, it is characterized in that, when including described the second electrode lay (320) and described 3rd electrode layer (330) when described electrode, the reactivity number of loci of the described sub-electrode layer near described first surface and the described sub-electrode layer near described second surface is more than the reactivity number of loci of all the other each described sub-electrode layers。

9. electrode according to any one of claim 1 to 8, it is characterised in that

The material forming described first electrode layer (310) is carbon felt；

Any one or more in charcoal felt after forming the material of described the second electrode lay (320) the charcoal felt after carbon paper, electrochemical modification and being hydrophilically modified；

Any one or more in charcoal felt after forming the material of described 3rd electrode layer (330) the charcoal felt after carbon paper, electrochemical modification and being hydrophilically modified。

10. a flow battery, including bipolar plates (10), liquid flow frame (20), electrode (30) and ion exchange membrane (40), it is characterised in that the described electrode (30) electrode according to any one of claim 1 to 9, wherein

When described electrode includes described the second electrode lay (320), described the second electrode lay (320) is arranged near described ion exchange membrane (40)；

When described electrode includes described 3rd electrode layer (330), described 3rd electrode layer (330) is arranged near described bipolar plates (10)。

11. a liquid stream battery stack, including multiple flow batteries, it is characterised in that described flow battery is the flow battery described in claim 10。