阅读说明：本技术 一种液流电池用半电池、单电池、电池堆以及液流电池系统 (Half cell for flow battery, single cell, cell stack and flow battery system ) 是由 黄峰 刘庆华 常彬杰 孙永伟 龙银花 蒋明哲 高星 于 2020-04-27 设计创作，主要内容包括：本发明提供一种液流电池用半电池、单电池、电池堆以及液流电池系统,其中,一种液流电池用半电池,包括：极板和电极,其中,所述电极具有相对的A侧面和B侧面,其中,所述A侧面刻有电解液流道,所述B侧面嵌入到所述极板中。通过将一侧刻有电解液流道的电极嵌入到极板内,从而增大了电极与极板的接触面积、减小了电池内阻并提高了电池功率密度,同时还能够防止电极在极板上移动使阴阳极对应更准确。(The invention provides a flow battery half-cell, a single cell, a cell stack and a flow battery system, wherein the flow battery half-cell comprises: the electrode comprises a polar plate and an electrode, wherein the electrode is provided with an A side face and a B side face which are opposite, an electrolyte flow channel is carved on the A side face, and the B side face is embedded into the polar plate. The electrode with the electrolyte flow channel carved on one side is embedded into the polar plate, so that the contact area of the electrode and the polar plate is increased, the internal resistance of the battery is reduced, the power density of the battery is improved, and the electrode can be prevented from moving on the polar plate to enable the corresponding of the cathode and the anode to be more accurate.)

1. A half-cell for a flow battery, comprising: the electrode comprises a polar plate and an electrode, wherein the electrode is provided with an A side face and a B side face which are opposite, an electrolyte flow channel is carved on the A side face, the B side face is embedded into the polar plate, and preferably, the B side face is also carved with the electrolyte flow channel.

2. Half-cell according to claim 1, characterized in that the depth of embedding of the electrode in the plate is comprised between 10% and 50%, preferably between 20% and 50%, more preferably between 30% and 40% of the thickness of the plate.

3. The half-cell according to claim 1 or 2, wherein the surface of the plate in contact with the electrode is a surface having a roughness grade of N3 to N10.

4. A half-cell according to any of claims 1 to 3, wherein the thickness of the plate is between 0.1mm and 10mm, preferably between 0.2mm and 3mm, more preferably between 0.5mm and 1 mm; and/or the thickness of the electrode is 0.1mm to 10mm, preferably 1mm to 6mm, more preferably 2mm to 5 mm.

5. The half-cell according to any of claims 1 to 4, wherein said electrolyte flow channel is a continuous electrolyte flow channel or an intermittent electrolyte flow channel, preferably said continuous electrolyte flow channel is of single-wire Z-type, multi-wire Z-type, interlaced or parallel type; and/or the section of the electrolyte flow channel is rectangular, square or trapezoidal.

6. The half-cell according to any one of claims 1 to 5, wherein the electrolyte flow channel has a width of 0.1mm to 5mm, preferably 0.2mm to 3mm, more preferably 0.5mm to 1.5 mm; and/or the depth of the electrolyte flow channel is less than or equal to the thickness of the electrode.

7. The half-cell according to any one of claims 1 to 6, wherein the plate is a dense carbon material selected from at least one of graphite, carbon and carbon or a metal material selected from at least one of titanium, iron and copper; and/or the electrode is a porous carbon material or a metal material, the porous carbon material is selected from at least one of graphite felt, carbon felt, graphite paper, carbon cloth and graphite cloth, and the metal material is selected from at least one of titanium, iron and copper.

8. A cell for a flow battery, comprising: a separator and a positive half cell and a negative half cell respectively located on both sides of the separator, the positive half cell and/or the negative half cell being the half cell of any one of claims 1-7.

9. A flow battery cell stack comprising at least two single cells of claim 8 connected in series one after another.

10. A flow battery system, comprising:

the cell stack of claim 9;

the positive liquid storage tank is connected with an external interface of an electrolyte flow channel of the positive half cell;

and the negative liquid storage tank is connected with an external interface of the electrolyte flow channel of the negative half cell.

Technical Field

The invention relates to the field of batteries, in particular to a half battery, a single battery, a battery stack and a flow battery system for a flow battery.

Background

The flow battery is a high-performance storage battery which utilizes the separation of positive and negative electrolytes and respective circulation, has the characteristics of high capacity, wide application field (environment) and long cycle service life, and is a new energy product. The redox flow battery is a novel high-capacity electrochemical energy storage device which is actively researched and developed, is different from a battery which usually uses a solid material electrode or a gas electrode, the active substance of the redox flow battery is a flowing electrolyte solution, the most obvious characteristic of the redox flow battery is large-scale electricity storage, and the redox flow battery can be expected to meet a period of rapid development under the situation of the sound rising trend of widely utilizing renewable energy sources.

CN102867978A discloses a structure of a liquid flow energy storage battery, in which a filling plate is disposed between a bipolar plate and a porous electrode in an electrode frame, the filling plate is made of carbon material with good conductivity and low porosity or metal material stable in an acidic medium, so as to reduce the body resistance of the electrode and electrolyte and the contact resistance between the electrode and the bipolar plate, and finally reduce the ohmic internal resistance of the liquid flow energy storage battery. The patent believes that it is possible to increase the operating current density and thus the energy efficiency and voltage efficiency of a flow energy storage battery, resulting in a significant reduction in weight, volume and cost of the same output power battery. However, the addition of the filler plates increases the complexity of the cell structure and increases the requirements for sealing and fixing the electrodes. The filler has good conductivity, but only reduces the resistance and does not solve the problem of resistance between the polar plate and the electrode.

CN202384431U discloses an integrated composite electrode bipolar plate and a preparation method and application effect thereof, the integrated composite electrode bipolar plate is composed of an integrated graphite felt/carbon felt and a plastic sheet, the plastic sheet is embedded between the two graphite felts/carbon felts, and the long axis and the wide axis of the plastic sheet are both larger than those of the graphite felts/carbon felts. The integrated composite electrode bipolar plate of the utility model can obviously reduce the resistance generated by the existing graphite felt/carbon felt and bipolar plate by a pressing contact mode; the integrated composite electrode bipolar plate is characterized in that the graphite felt/carbon felt is used as a conductive matrix, so that the conductivity is remarkably improved, the phenomenon of conductive chain fracture is less, the mechanical property is good, the machining is easy, the integrated composite electrode bipolar plate can be bent and is not easy to deform, the air tightness is good, and the phenomenon of battery liquid leakage is avoided; adopt this utility model discloses an integration combined electrode bipolar plate can improve the discharge middling pressure of full vanadium liquid stream energy storage battery, energy efficiency and the life of battery, can not cause the structural damage and the plastics carbonization decomposition of graphite felt or carbon felt. But greatly increases the complexity of the cell structure by adding additional components and also compresses the space for the active components of the cell. It has a side effect of increasing the power density per unit volume of the battery.

Disclosure of Invention

In view of the problems in the prior art, an object of the present invention is to provide a half-cell for a flow battery, in which an electrode with an electrolyte flow channel engraved on one side is embedded in a plate, so as to increase the contact area between the electrode and the plate, reduce the internal resistance of the battery, improve the power density of the battery, and prevent the electrode from moving on the plate, so that the cathode and anode can be more accurately corresponded.

A second object of the present invention is to provide a cell for a flow battery that corresponds to the first object.

A third object of the present invention is to provide a flow cell stack corresponding to the second object.

A fourth object of the present invention is to provide a flow battery system corresponding to the third object.

In order to achieve one of the purposes, the technical scheme adopted by the invention is as follows:

a half-cell for a flow battery, comprising: the electrode comprises a polar plate and an electrode, wherein the electrode is provided with an A side face and a B side face which are opposite, an electrolyte flow channel is carved on the A side face, and the B side face is embedded into the polar plate.

The inventor of the application finds that the electrolyte flow channel is arranged on one side surface or two opposite side surfaces of the electrode, and the electrode with the electrolyte flow channel is embedded into the polar plate, so that the contact area between the electrode and the polar plate can be increased, the internal resistance of the battery is reduced, the power density of the battery is improved, the electrode can be prevented from moving on the polar plate, and the corresponding of the cathode and the anode is more accurate. In addition, the arrangement of the electrolyte flow channel can enable the electrolyte to be distributed more uniformly.

According to the invention, the opposite sides a and B are two sides that are not in contact, preferably two sides that are parallel.

In some preferred embodiments of the present invention, the side B is also engraved with an electrolyte flow channel.

According to the invention, the electrolyte flow channel engraved on the side A and the electrolyte flow channel engraved on the side B can be the same in type or different in size.

In some preferred embodiments of the present invention, the electrode is embedded in the electrode plate to a depth of 10% to 50%, preferably 20% to 50%, more preferably 30% to 40% of the thickness of the electrode plate.

According to the invention, the depth of embedding of the electrode in the pole plate can be cited as 10%, 15%, 20%, 22%, 25%, 30%, 35%, 40%, 45% and 50% of the thickness of the pole plate and any value in between.

In some preferred embodiments of the present invention, the surface of the plate in contact with the electrode is a surface having a roughness grade of N3 to N10.

According to the invention, the roughness grades N3 to N10 correspond to roughness values Ra of 0.1, 0.2, 0.4, 0.8, 1.6, 3.2, 6.3 and 12.5, respectively. In the present invention, a surface having a roughness grade of N7, i.e., a roughness value Ra of 1.6, is preferable.

According to the invention, the desired roughness can be obtained by providing a pattern on the surface, wherein the pattern can be of the type commonly used in the art, such as Z-type, mesh-type and multi-channel type.

In some preferred embodiments of the present invention, the thickness of the plate is 0.1mm to 10mm, preferably 0.2mm to 3mm, and more preferably 0.5mm to 1 mm.

According to the invention, the thickness of the plates can be cited as 0.1mm, 0.5mm, 1.0mm, 1.5mm, 2.0mm, 2.5mm, 3.0mm, 3.5mm, 4.0mm, 4.5mm, 5.0mm, 5.5mm, 6.0mm, 6.5mm, 7.0mm, 7.5mm, 8.0mm, 8.5mm, 9.0mm, 9.5mm and 10.0mm and any value between them.

According to the invention, the thickness of the plate refers to the minimum length of the plate in the direction from the A side to the B side.

In some preferred embodiments of the invention, the thickness of the electrode is 0.1mm to 10mm, preferably 1mm to 6mm, more preferably 2mm to 5 mm.

According to the invention, the thickness of the electrodes can be cited as 0.1mm, 0.5mm, 1.0mm, 1.5mm, 2.0mm, 2.5mm, 3.0mm, 3.5mm, 4.0mm, 4.5mm, 5.0mm, 5.5mm, 6.0mm, 6.5mm, 7.0mm, 7.5mm, 8.0mm, 8.5mm, 9.0mm, 9.5mm and 10.0mm and any value in between.

According to the invention, the thickness of the electrode refers to the minimum vertical distance between the a-side and the B-side.

In some preferred embodiments of the present invention, the electrolyte flow channel is a continuous electrolyte flow channel or an intermittent electrolyte flow channel.

In some preferred embodiments of the present invention, the continuous type electrolyte flow channel is a single line Z type, a multi-line Z type, an interlaced type or a parallel type.

In some preferred embodiments of the present invention, the electrolyte flow channel has a rectangular, square or trapezoidal cross section.

According to the invention, cross-section refers to the surface perpendicular to the direction of flow of the liquid.

In some preferred embodiments of the present invention, the electrolyte flow channel has a width of 0.1mm to 5mm, preferably 0.2mm to 3mm, and more preferably 0.5mm to 1.5 mm.

According to the present invention, the width of the electrolyte flow channel may be enumerated as 0.1mm, 0.5mm, 1.0mm, 1.5mm, 2.0mm, 2.5mm, 3.0mm, 3.5mm, 4.0mm, 4.5mm and 5.0mm and any value therebetween. According to the present invention, the width refers to the width of the electrolyte flow channel on the a-side.

In some preferred embodiments of the present invention, the electrolyte flow channel has a depth equal to or less than a thickness of the electrode.

In some preferred embodiments of the present invention, the plate is a dense carbon material selected from at least one of graphite, carbon, and carbon, or a metal material selected from at least one of titanium, iron, and copper.

According to the invention, the density of the dense carbon material is 1.0g/mm³-2.0g/mm³。

According to the invention, the dense carbon material can be graphite, carbon or carbon, and can also be a composite material formed by two or three of graphite, carbon and carbon.

In some preferred embodiments of the present invention, the electrode is a porous carbon material selected from at least one of graphite felt, carbon felt, graphite paper, carbon cloth, and graphite cloth, or a metal material selected from at least one of titanium, iron, and copper.

According to the present invention, the porosity of the porous carbon material is 80% or more.

In order to achieve the second purpose, the invention adopts the following technical scheme:

a cell for a flow battery, comprising: the battery comprises a diaphragm, and a positive electrode half cell and a negative electrode half cell which are respectively positioned on two sides of the diaphragm, wherein the positive electrode half cell and/or the negative electrode half cell are/is the half cells.

In order to achieve the third purpose, the technical scheme adopted by the invention is as follows:

a flow battery cell stack comprises at least two single cells connected in series.

In order to achieve the fourth purpose, the technical scheme adopted by the invention is as follows:

a flow battery system, comprising:

the above-described cell stack;

the positive liquid storage tank is connected with an external interface of an electrolyte flow channel of the positive half cell;

and the negative liquid storage tank is connected with an external interface of the electrolyte flow channel of the negative half cell.

The invention has the beneficial effects that: based on the projected area of the electrode, the output power density of a single cell formed by the half cell provided by the invention is more than or equal to 300mW cm^-2Even 400 mW.cm or more^-2Even 500 mW/cm or more^-2。

Drawings

Fig. 1 is a schematic cross-sectional structure of a single cell of example 1.

Fig. 2 is a schematic front sectional view of the electrode of example 1.

Fig. 3 is a schematic bottom view of the electrode of example 1.

Fig. 4 is a schematic cross-sectional structure of a single cell of comparative example 1.

Description of the drawings: 1-pole plate; 2-an electrode; 3-an electrolyte flow channel; 4-a membrane.

Detailed Description

The present invention will be described in detail below by way of examples with reference to the accompanying drawings, but the scope of the present invention is not limited to the following description.

The contact resistance of the half cell was tested by the specification NB/T42132 and 2017.

And calculating the power density of the single cell through the battery charging and discharging equipment. The battery charging and discharging equipment can collect the voltage and the current of the battery. Using the formula: the cell power density was calculated as (current/electrode area) × (cell voltage/number of cells in the stack).

Example 1

The unit cell in this embodiment (shown in fig. 1) includes a perfluorosulfonic acid separator (4), and a positive electrode half cell and a negative electrode half cell respectively located on both sides of the perfluorosulfonic acid separator (4). The positive (or negative) half cell comprises a polar plate (1, the thickness is 10mm, the material is graphite, the surface in contact with the electrode is the surface with the roughness level of N7) and an electrode (2, the thickness is 8mm, the size is 200mm x 200mm, the material is graphite felt, the structure is shown in figure 2), an electrolyte flow channel (3, a Z-shaped flow channel with the 1mm wide and 1mm deep and square cross section is engraved on one side of the electrode, the total area is 200mm x 200mm, the structure is shown in figure 3), the side surface engraved with the electrolyte flow channel is in contact with a perfluorosulfonic acid diaphragm (4), the other opposite side surface is embedded into the polar plate (1), and the embedding depth is 2mm (namely 20% of the thickness of the polar plate). Further, a polytetrafluoroethylene sealing material and an end plate are placed around the electrode (2). The series-connected single cells form a cell stack, the cell stack further comprises a liquid distributor, an end plate is placed on the outer side of the one-way liquid distributor, and the components are fastened through preset holes by using bolts.

Through tests, the contact resistance of the half cell provided by the embodiment is 168mOhm, and the maximum power density of a single cell is 356mW cm^-2. The single cell provided by the present embodiment can bear the requirement of high power density operation. Wherein the initial concentration of the positive electrolyte is 0.8 mol.L^-1V(IV)+0.8mol·L^-1V(IV)+3mol·L^-1H₂SO₄The concentration of the cathode electrolyte is 0.8 mol.L^-1V(II)+0.8mol·L^-1V(III)+3mol·L^-1H₂SO₄。

Example 2

The structure of the single cell in this example was similar to that in example 1, except that the thickness of the electrode was 6mm and the thickness of the electrode was 8 mm.

Tests show that the contact resistance of the half cell provided by the embodiment is 160mOhm, and the maximum power density of a single cell is 450mW cm^-2. This implementationThe provided single cell can bear the requirement of high power density operation. Wherein the initial concentration of the positive electrolyte is 0.8 mol.L^-1V(IV)+0.8mol·L^-1V(IV)+3mol·L^-1H₂SO₄The concentration of the cathode electrolyte is 0.8 mol.L^-1V(II)+0.8mol·L^-1V(III)+3mol·L^-1H₂SO₄。

Example 3

The structure of the single cell in this example was similar to that in example 1, except that the thickness of the electrode was 4mm and the thickness of the electrode was 6 mm.

Tests show that the contact resistance of the half cell provided by the embodiment is 140mOhm, and the maximum power density of a single cell is 500mW cm^-2. The single cell provided by the present embodiment can bear the requirement of high power density operation. Wherein the initial concentration of the positive electrolyte is 0.8 mol.L^-1V(IV)+0.8mol·L^-1V(IV)+3mol·L^-1H₂SO₄The concentration of the cathode electrolyte is 0.8 mol.L^-1V(II)+0.8mol·L^-1V(III)+3mol·L^-1H₂SO₄。

Example 4

The structure of the single cell in this example is similar to that in example 3, except that the electrolyte flow channels are parallel flow channels.

Tests show that the contact resistance of the half cell provided by the embodiment is 105mOhm, and the maximum power density of a single cell is 600mW cm^-2. The single cell provided by the present embodiment can bear the requirement of high power density operation. Wherein the initial concentration of the positive electrolyte is 0.8 mol.L^-1V(IV)+0.8mol·L^-1V(IV)+3mol·L^-1H₂SO₄The concentration of the cathode electrolyte is 0.8 mol.L^-1V(II)+0.8mol·L^-1V(III)+3mol·L^-1H₂SO₄。

Example 5

The structure of the single cell in this example is similar to that in example 4, except that electrolyte flow channels are engraved on both sides of the electrode.

After the test, the test paper is tested,the contact resistance of the half cell provided in this example was 85mOhm, and the maximum power density of the single cell was 640mW · cm^-2. The single cell provided by the present embodiment can bear the requirement of high power density operation. Wherein the initial concentration of the positive electrolyte is 0.8 mol.L^-1V(IV)+0.8mol·L^-1V(IV)+3mol·L^-1H₂SO₄The concentration of the cathode electrolyte is 0.8 mol.L^-1V(II)+0.8mol·L^-1V(III)+3mol·L^-1H₂SO₄。

Example 6

The structure of the single cell in this example is similar to that in example 5, except that the cross section of the electrolyte flow channel is a lower trapezoid, and the width (i.e., the lower base of the trapezoid) is 1 mm.

Tests show that the contact resistance of the half cell provided by the embodiment is 75mOhm, and the maximum power density of a single cell is 700mW cm^-2. The single cell provided by the present embodiment can bear the requirement of high power density operation. Wherein the initial concentration of the positive electrolyte is 0.8 mol.L^-1V(IV)+0.8mol·L^-1V(IV)+3mol·L^-1H₂SO₄The concentration of the cathode electrolyte is 0.8 mol.L^-1V(II)+0.8mol·L^-1V(III)+3mol·L^-1H₂SO₄。

Example 7

The structure of the single cell in this example was similar to that in example 1, except that the depth of the electrode embedded in the plate was 1 mm.

Tests show that the contact resistance of the half cell provided by the embodiment is 150mOhm, and the maximum power density of a single cell is 420mW cm^-2。

Example 8

The structure of the single cell in this example was similar to that in example 1, except that the depth of embedding of the electrode in the plate was 3 mm.

Tests show that the contact resistance of the half cell provided by the embodiment is 182mOhm, and the maximum power density of a single cell is 340mW cm^-2。

Example 9

The structure of the single cell in this example was similar to that in example 1, except that the surface of the plate in contact with the electrode was a surface having a roughness grade of N1.

The results showed that the electrode was easily slipped or dropped and the embedding effect was poor.

Example 10

The structure of the single cell in this example was similar to that in example 1, except that the width of the electrolyte flow channel was 0.1 mm.

Through tests, the contact resistance of the half cell provided by the embodiment is 175mOhm, and the maximum power density of a single cell is 331mW cm^-2。

Example 11

The structure of the single cell in this example was similar to that in example 1, except that the width of the electrolyte flow channel was 5 mm.

Tests show that the contact resistance of the half cell provided by the embodiment is 180mOhm, and the maximum power density of a single cell is 310mW cm^-2。

Comparative example 1

The structure of the single cell of this comparative example is shown in fig. 4, which differs from the single cell of example 1 only in that the electrolyte flow channel in this comparative example is provided in the electrode plate, and the electrode is not embedded in the electrode plate.

The half cell provided in this comparative example was tested to have a contact resistance of 198mOhm and a maximum power density of 320mW cm^-2。

Comparative example 2

The structure of the single cell of this comparative example was similar to that of example 1, except that no electrolyte flow channel was provided.

The half cell provided in this comparative example was tested to have a contact resistance of 204mOhm and a maximum power density of 240mW cm^-2。

Comparative example 3

The structure of the single cell of this comparative example was similar to that of comparative example 1, except that no electrolyte flow channel was provided.

After testing, the comparative example providesThe contact resistance of the half cell was 224mOhm, and the maximum power density of the single cell was 298mW cm^-2。

For the purpose of analysis, the main experimental parameters and experimental results of the above examples are shown in table 1.

TABLE 1

Note: in the above table, "-" indicates that the data was not measured.

The inventor of the application finds that the contact resistance is 75-160 mOhm, and the maximum power density is 400-800 mW cm^-2This is desirable because, within the above range, high performance output such as high efficiency of the battery, long life, high current, and the like can be realized, and customer requirements can be satisfied.

It should be noted that the above-mentioned embodiments are only for explaining the present invention, and do not constitute any limitation to the present invention. The present invention has been described with reference to exemplary embodiments, but the words which have been used herein are words of description and illustration, rather than words of limitation. The invention can be modified, as prescribed, within the scope of the claims and without departing from the scope and spirit of the invention. Although the invention has been described herein with reference to particular means, materials and embodiments, the invention is not intended to be limited to the particulars disclosed herein, but rather extends to all other methods and applications having the same functionality.