A zinc-based flow battery structure

Abstract

The application relates to a zinc-based liquid flow battery structure, which comprises a current collector, a positive electrode, a diaphragm, a negative electrode and a current collector arranged in sequence, and is provided with two or more through holes on the negative electrode; a non-conductive glue layer is coated on the surface of the current collecting plate close to the negative electrode at the position corresponding to the through hole, so that the projection of the through hole on the current collecting plate is on the non-conductive glue layer. The application solves the problem that the surface capacity of the zinc-based liquid flow battery is limited, and further improves the energy density of the battery. The method is simple to operate and easy to realize.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of flow battery, in particular to the field of zinc-based flow battery. BACKGROUND

[0002] With the increasing depletion of fossil energy, the development and utilization of renewable energy such as wind energy and solar energy have become the focus of attention of various countries. Due to the influence of weather and other factors, wind energy and solar energy have discontinuity and instability, which will cause impact on the power grid during the process of renewable energy power generation and grid connection, and affect the power supply quality and the stability of the power grid. Energy storage technology can solve this problem and ensure the efficient and stable operation of renewable energy power generation and grid connection. Energy storage technology mainly includes physical energy storage and chemical energy storage. Among them, the chemical energy storage represented by the flow battery has many advantages such as independent power and capacity, rapid response, simple structure, easy design, long cycle life and environmental friendliness, and has the most advantages in large-scale energy storage.

[0003] Zinc-based flow battery has attracted widespread attention due to its abundant active material resources, high energy density and low system cost. Among them, zinc-based flow battery with carbon felt, graphite felt and other porous materials as electrode material has become a research hotspot due to its high working current density and good cycle stability. Since the zinc deposition of zinc-based flow battery with carbon felt, graphite felt and other porous materials as electrode mainly occurs on the electrode surface close to the separator side, a common problem of this kind of zinc-based flow battery is that as the cell surface capacity gradually increases, the zinc deposition on the electrode surface becomes more and more dense, the resistance of zinc ion diffusion to the surface of deposited zinc becomes more and more large, which leads to the increase of battery polarization and the decrease of battery performance; in severe cases, even zinc dendrites will pierce the separator and cause battery failure. SUMMARY

[0004] Technical problems to be solved by the present application (invention purposes)

[0005] Since the zinc deposition of zinc-based flow battery with carbon felt, graphite felt and other porous materials as electrode mainly occurs on the electrode surface close to the separator side, a common problem of this kind of zinc-based flow battery is that as the cell surface capacity gradually increases, the zinc deposition on the electrode surface becomes more and more dense, the resistance of zinc ion diffusion to the surface of deposited zinc becomes more and more large, which leads to the increase of battery polarization and the decrease of battery performance; in severe cases, even zinc dendrites will pierce the separator and cause battery failure. In the present application, through the use of through holes in the negative electrode, and the coating of non-conductive glue on the surface of the current collector at the position of the through holes, the diffusion of zinc ions to the surface of deposited zinc is promoted, the ion transmission resistance is reduced, the battery polarization is reduced, and the battery performance and cycle life are improved.

[0006] The complete technical solution provided by the present application is described in detail in combination with the drawings

[0007] The method for reducing the battery polarization of zinc-based flow battery at high surface capacity, improving the battery performance and cycle life is to increase the through holes in the negative electrode.

[0008] A zinc-based flow battery structure comprises a current collector, a positive electrode, a separator, a negative electrode and a current collector arranged in sequence, characterized in that:

[0009] Two or more through holes are arranged on the negative electrode, and the surface of the current collector plate close to the negative electrode is coated with a non-conductive glue layer at the position corresponding to the through holes, so that the projection of the through holes on the current collector plate is on the non-conductive glue layer.

[0010] The opening positions of the two or more through holes are uniformly distributed on the electrode surface.

[0011] The cross-sectional area of each through hole parallel to the surface of the negative electrode is 0.1-0.5 cm 2 , preferably 0.1-0.4 cm 2 , and more preferably 0.3-0.4 cm 2 .

[0012] The opening rate of the through holes on the surface of the negative electrode (the ratio of the sum of the areas of all the through holes on the negative electrode surface to the electrode surface area) is 5%-20% of the electrode surface area; preferably 10%-15%.

[0013] The non-conductive glue can be divided into one or more of polyester resin glue, epoxy resin glue, polyurethane adhesive, polybutadiene resin glue, silicone resin glue, polyester imine resin glue and polyimide resin glue according to the composition of the main resin.

[0014] After coating the non-conductive glue, the projection of the through holes on the current collector plate is on the non-conductive glue, and the shape and size of the non-conductive glue corresponding to each through hole are the same as or equivalent to the port of the through hole close to the current collector plate.

[0015] The thickness of the non-conductive glue coating is 0.5-3 mm, preferably 0.5-1 mm.

[0016] The thickness of the negative electrode is 3-6 mm, preferably 4-5 mm.

[0017] The positive and negative electrode materials of the battery are carbon felt or graphite felt; and the current collector is a graphite plate.

[0018] The zinc-based flow battery includes a zinc-bromine flow battery, a zinc-iodine flow battery, a zinc-nickel flow battery or a zinc-manganese flow battery.

[0019] The beneficial effects brought by the technical scheme of the present application

[0020] 1. The zinc-based flow battery structure of the present application comprises a current collector, a positive electrode, a separator, a negative electrode and a current collector arranged in sequence, characterized in that: the negative electrode is provided with through holes, and the surface of the current collector close to the negative electrode at the position corresponding to the through holes is coated with a non-conductive adhesive layer, so that the projection of the through hole on the current collector is on the non-conductive adhesive layer.

[0021] 2. The zinc-based flow battery structure of the present application solves the problem of limited capacity of zinc-based flow battery and further improves the energy density of the battery.

[0022] The method is simple to operate and easy to implement. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 Battery structure schematic diagram; wherein 1 end plate 2 positive current collector 3 positive electrode 4 separator 5 negative electrode 6 negative current collector 7 end plate;

[0024] Figure 2 Schematic diagram of the opening of the carbon felt electrode. DETAILED DESCRIPTION

[0025] The zinc-based flow battery structure of the present application comprises a current collector, a positive electrode, a separator, a negative electrode and a current collector arranged in sequence, characterized in that:

[0026] The negative electrode is provided with through holes, and the surface of the current collector close to the negative electrode at the position corresponding to the through holes is coated with a non-conductive adhesive layer, so that the projection of the through hole on the current collector is on the non-conductive adhesive layer.

[0027] The opening positions of the through holes are uniformly distributed on the surface of the electrode.

[0028] After the non-conductive adhesive is coated, the projection of the through hole on the current collector is on the non-conductive adhesive, and the shape and size of the non-conductive adhesive corresponding to each through hole are the same as or comparable to or slightly larger than the port area of the through hole close to the current collector, and one-to-one correspondence.

[0029] Example 1

[0030] The zinc bromide flow battery cycle performance experiment was carried out with 2MZnBr2+3MKCl+0.8M N-ethyl, methyl pyrrolidine (MEP) bromide as electrolyte, graphite plate as current collector, and carbon felt as positive and negative electrode. The thickness of the carbon felt is 5mm, the negative electrode of the carbon felt is provided with through holes, and the opening positions are uniformly distributed on the surface of the electrode. The surface of the current collector close to the negative electrode at the position corresponding to the through holes is coated with epoxy non-conductive adhesive (i.e. epoxy resin adhesive, Wuxi Resin Factory of Bluestar Chemical New Materials Co., Ltd., Ex-20), so that the projection of the through hole on the current collector is on the epoxy non-conductive adhesive, and the thickness of the non-conductive adhesive is 0.5mm. The separator is PE film, the electrolyte flow rate is 60ml / min, the current density is 40mA / cm 2 , and the discharge is to 0.1V. The electrode area is 48cm 2The battery performance test was performed on the batteries with different open porosities and single hole areas.

[0031] The battery performance was as follows:

[0032]

[0033] The definition of the through hole area was the surface area of the through hole on the carbon felt electrode;

[0034] The definition of the total open porosity was the total sum of the through hole area accounting for the percentage of the surface area of the carbon felt electrode.

[0035] When the total open porosity was 10%, the battery VE increased with the increase of the single hole area, which was mainly due to the increase of the single hole area, which helped to accelerate the mass transfer of the electrolyte, reduce the battery concentration polarization and thus improve the battery VE; when the single hole area was greater than 0.4cm 2 , the battery CE and VE decreased, which was mainly due to the excessive open hole area of the electrode, which led to the destruction of the electrode conductive network and the increase of the battery polarization; in addition, due to the influence of VE, the battery discharge power first increased and then decreased, and when the through hole area was 0.4cm 2 , the battery power was the highest.

[0036] When the single hole area was 0.4cm 2 , the battery VE decreased with the increase of the total open porosity, which was mainly due to the decrease of the electrode reaction active area with the increase of the open porosity, which led to the increase of the battery polarization; when the open porosity was 5%, the battery surface capacity was 100mAh / cm 2 , which was mainly due to the low open porosity, and the increase of the electrolyte diffusion resistance to the electrode surface with the increase of the surface capacity, which led to the increase of the battery polarization; in addition, due to the decrease of the electrode effective area with the increase of the total open porosity, the battery discharge power gradually decreased.

[0037] Example 2

[0038] The zinc-bromine flow battery cycle performance experiment was performed with 2M ZnBr2+3MKCl+0.8M N-ethyl, methyl pyrrolidine (MEP) bromide as the electrolyte, the graphite plate as the current collector, and the carbon felt as the positive and negative electrodes, the thickness of the carbon felt was 5mm, the through hole was provided on the negative electrode of the carbon felt, and the open hole position was uniformly distributed on the electrode surface. The surface of the current collector near the negative electrode side at the position corresponding to the through hole was coated with epoxy non-conductive glue (i.e. epoxy resin glue, Wuxi Resin Factory of Bluestar Chemical New Materials Co., Ltd., Ex-20), so that the projection of the through hole on the current collector was on the epoxy non-conductive glue, and the thickness of the non-conductive glue was 0.5mm, 1mm, 1.5mm, 2mm and 3mm respectively. The separator was PE film, the electrolyte flow rate was 60ml / min, the current density was 40mA / cm 2 , and the discharge was to 0.1V. The electrode area was 48cm2 The total opening rate is 10%. 2 The total opening rate is 10%.

[0039] The battery performance of the battery coated with different thickness of non-conductive glue coating was tested.

[0040]

[0041]

[0042] With the increase of the thickness of the non-conductive glue coating, the battery VE decreases, which is mainly due to the increase of the thickness of the non-conductive glue coating affecting the mass transfer of the electrolyte in the through hole, causing the battery polarization to increase.

[0043] Comparative example 1

[0044] The zinc-bromine flow battery cycle performance experiment was carried out with 2M ZnBr2+3MKCl+0.8M MEP as the electrolyte, graphite plate as the current collector, carbon felt as the positive and negative electrodes of the battery, and the thickness of the carbon felt being 5mm. The carbon felt electrode had no through hole. The separator was PE film, the electrolyte flow rate was 60ml / min, the current density was 40mA / cm 2 , and the discharge was to 0.1V. The electrode area was 48cm 2 .

[0045] The battery surface capacity can reach 80mAh / cm 2 , and further increasing the battery surface capacity will cause the zinc dendrites to pierce the separator, resulting in battery failure. This is mainly due to the gradual increase of the battery surface capacity, the zinc deposition on the electrode surface becomes more and more dense, and the resistance of zinc ion diffusion to the surface of the deposited zinc becomes larger, resulting in the increase of the battery polarization.

[0046] Comparative example 2

[0047] The zinc-bromine flow battery cycle performance experiment was carried out with 2M ZnBr2+3MKCl+0.8M MEP as the electrolyte, graphite plate as the current collector, carbon felt as the positive and negative electrodes of the battery, and the thickness of the carbon felt being 5mm. The carbon felt electrode had no through hole. The separator was PE film, the electrolyte flow rate was 60ml / min, the current density was 40mA / cm 2 , and the discharge was to 0.1V. The electrode area was 48cm 2 . The total opening rate was 10%. 2

[0048] ​Zinc shedding occurs during the operation of the battery, which will block the battery and cause the battery to fail. This is mainly due to the fact that the surface of the current collector plate is not coated with non-conductive glue at the through-hole position, and zinc is deposited on the surface of the graphite plate current collector. As the graphite plate is used as the matrix for zinc deposition, the poor adhesion between zinc and the graphite plate leads to zinc shedding.

Claims

1. A zinc-based flow battery structure, comprising a current collector, a positive electrode, a separator, a negative electrode, and a current collector arranged in sequence, characterized in that: two or more through holes are provided on the negative electrode, and the current collector plate on the position corresponding to the through hole is coated with a non-conductive adhesive layer on the side surface close to the negative electrode, so that the projection of the through hole on the current collector plate is on the non-conductive adhesive layer, and the opening positions of the two or more through holes are uniformly distributed on the electrode surface, and the positive and negative electrode materials of the battery are carbon felt or graphite felt; and the current collector is a graphite plate.

2. The structure according to claim 1, characterized in that: Each through hole has a cross-sectional area parallel to the negative electrode surface of 0.1-0.5 cm 2 .

3. The structure according to claim 1, characterized in that: Each through hole has a cross-sectional area parallel to the negative electrode surface of 0.1-0.4 cm 2 .

4. The structure according to claim 1 or 3, characterized in that: the opening ratio of the through holes on the surface of the negative electrode, i.e. the ratio of the sum of the areas of all through holes on the negative electrode surface to the electrode surface area, is 5%-20% of the electrode surface area.

5. The structure according to claim 4, characterized in that: the opening ratio of the through holes on the surface of the negative electrode, i.e. the ratio of the sum of the areas of all through holes on the negative electrode surface to the electrode surface area, is 10%-15% of the electrode surface area.

6. The structure according to claim 1, characterized in that: the non-conductive adhesive can be one or more of polyester resin adhesive, epoxy resin adhesive, polyurethane adhesive, polybutadiene resin adhesive, silicone resin adhesive, polyester imine resin adhesive, and polyimide resin adhesive according to the composition of the main resin; after coating the non-conductive adhesive, the projection of the through hole on the current collector plate is on the non-conductive adhesive, and the shape and size of the non-conductive adhesive corresponding to each through hole are the same as or comparable to the port of the through hole close to the current collector plate.

7. The structure according to claim 1 or 6, wherein: the thickness of the non-conductive adhesive coating is 0.5-3mm; and the thickness of the negative electrode is 3-6mm.

8. The structure of claim 7, wherein: the thickness of the non-conductive adhesive coating is 0.5-1mm; and the thickness of the negative electrode is 4-5mm.

9. The structure of claim 1, wherein: the zinc-based flow battery includes zinc-bromine flow battery, zinc-iodine flow battery, zinc-nickel flow battery, or zinc-manganese flow battery.

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