CN102299348A - Porous electrode structure of redox flow battery and preparation method thereof - Google Patents

Abstract

The invention relates to a porous electrode structure of a liquid flow battery and a preparation method thereof. The porous electrode is provided with strip-shaped, triangular, trapezoidal or special-shaped regions with a density greater than and/or less than the average density of the porous electrode. The porous electrode is designed to have a convex or concave surface structure. After compression, the local compressibility of the electrode will be different. The part with higher compressibility is relatively difficult to flow through due to the large relative density of pores and small fluid resistance, while the part with small compressibility is due to the small relative density of large pores and small fluid resistance. Allows liquids to pass through relatively easily. The structural design optimizes the fluid distribution in the battery, thereby improving the energy conversion efficiency of the battery and prolonging the service life of the battery.

Description

A kind of porous electrode structure of liquid flow battery and its preparation method

technical field

The invention relates to a redox flow battery, in particular to a porous electrode structure of a flow battery and a preparation method thereof.

Background technique

With the rapid development of the national economy, the contradictions among energy, resources, and the environment have become increasingly prominent. The country proposes to develop renewable and clean energy based on solar and wind power generation, and build a sustainable economic growth model. However, solar energy and wind energy produce significant changes in power generation with day and night changes, and it is difficult to maintain a stable power output. It needs to cooperate with a certain scale of power storage devices to form a complete power supply system to ensure continuous and stable power supply. The redox flow battery system has the functions of electric energy storage and high-efficiency conversion, and the battery capacity can be increased with the increase of the volume of the liquid storage tank. It has the advantages of long service life, low operation and maintenance costs, etc., so it has good advantages in many fields. Prospects.

When the electrolyte of a redox flow battery flows inside the battery, it is prone to uneven distribution, and it is easy to form a dead angle where no electrolyte flows. The polarization of this part seriously affects the conversion efficiency of the battery, and even affects the service life of the battery.

Contents of the invention

The invention relates to a porous electrode structure of a redox flow battery capable of improving the charging and discharging performance of the battery and a preparation method thereof; the design and preparation are simple and the cost is low.

In order to achieve the above object, the technical scheme adopted in the present invention:

A porous electrode structure of a liquid flow battery, wherein the porous electrode is provided with a strip-shaped, triangular, trapezoidal or special-shaped area with a density greater than and/or less than the average density of the porous electrode; a parallel flow field, serpentine, etc. are formed inside the porous electrode Flow field, interdigitated flow field or profiled flow field.

The absolute value of the density difference between the region with a density greater and/or less than the average density of the porous electrode and the average density of the porous electrode is 5%-55% of the average density of the electrode.

Preparation of the electrode structure: cutting strip-shaped, triangular, trapezoidal or irregular grooves on the surface of the porous material, so that the surface of the porous material forms a surface structure with alternating protrusions and depressions;

When the flow battery is assembled, due to the difference in compressibility after the porous material is compressed, the size of the pores in each area of the electrode is different, forming an electrolyte flow field, which distributes the electrolyte by changing the resistance of the fluid.

The thickness compressibility range of the porous material is between 40% and 90%, and the difference of the thickness compressibility among various regions is between 5% and 55%. The porous material is graphite felt or carbon felt.

After compression, the local compressibility of the electrode will be different. The part with higher compressibility is relatively difficult to flow through due to the large relative density of pores and small fluid resistance, while the part with small compressibility is due to the small relative density of large pores and small fluid resistance. Allows liquids to pass through relatively easily. By changing the local compressibility of the electrode to change the local resistance of the electrode to the fluid, the electrode has the function of distributing the fluid to optimize the conversion efficiency of the battery.

The advantages of the present invention are:

a) The electrolyte flows smoothly inside the battery, which can optimize fluid distribution and improve battery conversion efficiency.

b) Simple implementation and low cost.

c) The structure design optimizes the fluid distribution in the battery, thereby improving the energy conversion efficiency of the battery and prolonging the service life of the battery.

Description of drawings

Fig. 1 is a schematic diagram of the surface structure of a porous material with strip-shaped protrusions in Example 1;

2 is a schematic diagram of the surface structure of a porous material with serpentine depressions in Example 2;

Fig. 3 is a schematic diagram of the surface structure of the porous material with irregular protrusions in Example 3.

Detailed ways

Example 1

Cutting the surface of the porous material, as shown in Figure 1, makes the surface of the porous material form a strip-shaped protrusion;

The porous material is 10 cm long, 8 cm wide, and the main body is 1 cm thick. 4 parallel rows of raised fluid distribution strips on the porous material. The length of the fluid distribution strip is 8 cm, the width is 0.8 cm, and the height is 0.5 cm. Dispense bar spacing 0.96cm. The porous electrode, plate, separator, electrolyte, etc. are assembled into an all-vanadium redox flow battery, and the thickness of the porous electrode is compressed to 9mm during the assembly process. Under the condition of 40mA/cm ² , the energy conversion efficiency of the test battery is 80%, which is 1% higher than that of the all-vanadium redox flow battery with untreated electrode surface.

Example 2

The porous material is 10 cm long, 8 cm wide, and the main body is 1 cm thick. The surface of the porous material is cut, as shown in FIG. 2 , so that a serpentine depression is formed on the surface of the porous material. The porous electrode, plate, separator, electrolyte, etc. are assembled into an all-vanadium redox flow battery, and the thickness of the porous electrode is compressed to 9mm during the assembly process. Under the condition of 40mA/cm ² , the energy conversion efficiency of the test battery is 79.6%, which is 0.05% higher than that of the all-vanadium redox flow battery with untreated electrode surface.

Example 3

The porous material is 10 cm long, 8 cm wide, and the main body is 1 cm thick. Cut the surface of the porous material, as shown in Figure 3, so that the surface of the porous material forms a special-shaped protrusion. The porous electrode, plate, separator, electrolyte, etc. are assembled into an all-vanadium redox flow battery, and the thickness of the porous electrode is compressed to 9mm during the assembly process. Under the condition of 40mA/cm ² , the energy conversion efficiency of the test battery is 79.7%, which is 0.06% higher than that of the all-vanadium redox flow battery with untreated electrode surface.

Claims (7)

1. A porous electrode structure for a flow battery, characterized in that: The porous electrode is provided with strip-shaped, triangular, trapezoidal or special-shaped regions whose density is higher and/or lower than the average density of the porous electrode. 2. The electrode structure according to claim 1, wherein the density of each region inside the porous electrode is different, and a parallel flow field, a serpentine flow field, an interdigitated flow field or a special-shaped flow field are formed inside the porous electrode. 3. The electrode structure according to claim 1, characterized in that: the absolute value of the density difference between the region with a density greater than and/or less than the average density of the porous electrode and the average density of the porous electrode is 5%-55% of the average electrode density. 4. A preparation method of the electrode structure according to claim 1, characterized in that: Cut strip-shaped, triangular, trapezoidal or special-shaped grooves or protrusions on the surface of the porous material, so that the surface of the porous material forms a surface structure with alternating protrusions and depressions; When the flow battery is assembled, due to the difference in compressibility after the porous material is compressed, the size of the pores in each area of the electrode is different, forming an electrolyte flow field, which distributes the electrolyte by changing the resistance of the fluid. 5 . The preparation method of the electrode structure according to claim 4 , wherein the thickness compressibility of the porous material ranges from 40% to 90%, and the difference in thickness compressibility between regions is 5% to 55%. 6. The preparation method of the electrode structure according to claim 4, characterized in that: the porous material is graphite felt, carbon felt or composite conductive plastic electrode. 7. The composite conductive plastic electrode according to claim 6, wherein the electrode material is composed of conductive filler and plastic, the conductive filler is carbon powder, graphite powder or graphite fiber, and the plastic is polyethylene or polypropylene.

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