Proton exchange membrane electrode with water-drop-shaped groove structure

Abstract

The utility model discloses a proton exchange membrane electrode with a water-drop-shaped groove structure, and belongs to the technical field of proton exchange membrane fuel cells. The membrane electrode comprises a catalyst layer, a proton exchange membrane and a gas diffusion layer, the proton exchange membrane is arranged below the catalyst layer, the gas diffusion layer is arranged above the catalyst layer, the upper surface of the catalyst layer is provided with a plurality of water-drop-shaped grooves which are uniformly distributed, and the grooves are of streamline shrinkage structures from top to bottom. And the cross section is of a water-drop-shaped structure with an arc-shaped top and a closed-up bottom. According to the structure, the capillary discharge capacity of water generated by reaction is enhanced while reaction gas is guided to rapidly permeate the catalyst layer, the gas mass transfer efficiency and the water management performance of the membrane electrode are improved, and the overall output power and the operation stability of the fuel cell are improved. The device is reasonable in structural design and controllable in preparation process, and has good popularization and application values.

Description

TECHNICAL FIELD

[0001] The utility model relates to proton exchange membrane fuel cell technical field especially relates to a kind of proton exchange membrane electrode with water droplet type groove structure. BACKGROUND

[0002] Proton exchange membrane fuel cell (PEMFC) is widely used in new energy vehicles, portable power supply and military energy system with its high energy conversion efficiency, low operating temperature and environmental friendly characteristics.Membrane electrode assembly (MEA) is the core functional unit of fuel cell, and its structure and mass transfer performance directly affect the output power and life of the cell.In traditional catalyst layer design, uneven gas transmission path, water retention after generation and other problems easily cause local oxygen deficiency, reaction efficiency reduction and waterlogging blockage, which seriously restricts the stable output of battery performance.Some existing technologies set linear, strip or rectangular grooves or form three-dimensional structures on ion exchange membrane for water treatment or ion transmission to improve gas transport capacity.However, this kind of structure is difficult to effectively guide the distribution of reaction gas on the surface of catalyst layer, so it cannot effectively solve the problems of uneven gas transmission, waterlogging and insufficient three-phase reaction activity during fuel cell operation, and there are still problems such as low liquid water discharge efficiency and insufficient groove capillary driving force.Therefore, the proton exchange membrane fuel cell technology field urgently needs to design a catalyst layer structure with more optimal geometric guidance to promote reactant mass transfer and product water discharge, improve catalyst utilization rate and improve water-gas co-management characteristics. SUMMARY

[0003] The utility model aims at providing a kind of proton exchange membrane electrode with optimized geometric parameters, water droplet type groove structure and surface functionalization treatment, which realizes rapid gas introduction, efficient capillary water discharge and continuous activation of three-phase interface by the matching arrangement of streamline expansion and contraction two-section design, hydrophobic and hydrophilic gradient side wall and gas diffusion direction, thereby significantly improving the power density and stability of fuel cell.

[0004] To achieve the above purpose, the technical scheme of the utility model embodiment is as follows:

[0005] A water droplet type groove proton exchange membrane electrode includes a catalyst layer, a proton exchange membrane and a gas diffusion layer, the proton exchange membrane is located below the catalyst layer, the gas diffusion layer is located above the catalyst layer, the upper surface of the catalyst layer is uniformly provided with a plurality of water droplet type grooves along the gas transmission direction, the water droplet type groove sequentially includes top expansion section (S1) and bottom contraction section (S2) from gas inlet end to outlet end, and the cross-sectional shape of the water droplet type groove is streamline water droplet structure with top circular arc and bottom close.

[0006] Preferably, the top width of the teardrop-shaped groove is 20~50 μm, the bottom opening width is less than 10 μm, the depth of the teardrop-shaped groove is 5~20 μm, the top arc radius is 10~25 μm, and the depth-to-width ratio is 0.2~0.5.

[0007] Preferably, the teardrop-shaped trench is formed by laser etching or micro / nano imprinting technology.

[0008] Preferably, the gas diffusion layer is a hydrophobically treated carbon paper, the hydrophobic contact angle of the gas diffusion layer is 95°~105°, and the porosity is 60%~80%.

[0009] Preferably, the ratio of the length of the top expansion section (S1) to the length of the bottom contraction section (S2) of the teardrop-shaped groove is 1.5 to 2.5.

[0010] Preferably, the trench direction is consistent with the gas diffusion direction and is arranged in accordance with the microporous structure direction of the gas diffusion layer.

[0011] Preferably, the hydrophobic contact angle of the gas diffusion layer is set to 100°, and the porosity is set to 70%.

[0012] Preferably, the teardrop-shaped groove has a top width of 30 μm, a bottom narrowing width of 8 μm, a groove depth of 10 μm, and the ratio of the length of the top expanding section (S1) to the length of the bottom contracting section (S2) is 2.

[0013] Beneficial effects: Compared with existing technologies, the teardrop-shaped trench structure of this invention guides the distribution of reactant gases on the catalyst layer surface while enhancing the capillary flow discharge capability of liquid water along the sidewall direction, effectively reducing local water retention. The streamlined trench profile reduces flow resistance, which is beneficial to improving gas resupply efficiency; the bottom tapering structure can play a compression and guiding role during gas entry into the catalyst layer, thereby promoting the effective formation of the three-phase boundary and enhancing electrochemical reaction activity. The overall structure has a synergistic optimization effect on catalyst utilization, water-gas management, and output performance.

[0014] In summary, this application features a teardrop-shaped groove structure, which has the advantage of simultaneously enhancing gas transport, liquid water discharge, and electrochemical reaction rate. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the three-dimensional exploded structure of the proton exchange membrane electrode of this utility model;

[0016] Figure 2 This is a three-dimensional structural diagram of the proton exchange membrane electrode of this utility model.

[0017] Figure 3This is a schematic diagram of the three-dimensional structure of the catalyst layer of this utility model;

[0018] Figure 4 This is a schematic diagram of the two-dimensional structure of the teardrop-shaped groove of this utility model.

[0019] Explanation of icon numbers:

[0020] 1. Proton exchange membrane, 2. Catalytic layer, 3. Gas diffusion layer, 4. Teardrop-shaped trench. Detailed Implementation

[0021] The technical solution of this utility model will be further described in detail below with reference to the accompanying drawings and specific embodiments. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this utility model belongs. The terminology used in this specification of this utility model is for the purpose of describing particular embodiments only and is not intended to limit the utility model. In the following description, the expression "some embodiments" refers to a subset of all possible embodiments; however, it should be understood that "some embodiments" can be the same subset or different subsets of all possible embodiments and can be combined with each other without conflict.

[0022] It should also be noted that when an element is referred to as being "fixed to" another element, it can be directly attached to the other element or there may be an intervening element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or there may be an intervening element. The terms "vertical," "horizontal," "inner," "outer," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only possible implementation.

[0023] Example 1

[0024] See attached document Figures 1-4 A 3D trench-type proton exchange membrane electrode includes a proton exchange membrane 1, a catalyst layer 2, a gas diffusion layer 3, and teardrop-shaped trenches 4. The proton exchange membrane 1 is disposed at the lower end of the catalyst layer 2, and the gas diffusion layer 3 is disposed at the upper end of the catalyst layer 2. Uniformly arranged teardrop-shaped trenches 4 are formed on the upper surface of the catalyst layer 2. Each teardrop-shaped trench 4 is divided into two structural parts, S1 and S2. The cross-section of the S1 structure gradually increases from top to bottom, while the cross-section of the S2 structure gradually decreases from top to bottom. The trenches 4 extend along the gas diffusion direction, and the cross-sectional shape of the teardrop-shaped trenches 4 is a teardrop profile with a rounded top and a contracting bottom, exhibiting an overall streamlined configuration.

[0025] Specifically, the teardrop-shaped trench 4 has a top width of 20-50 μm, a bottom narrowing width of less than 10 μm, a trench depth of 5-20 μm, a top arc radius of 10-25 μm, and a depth-to-width ratio of 0.2-0.5. The length ratio of the top expanding section (S1) to the bottom contracting section (S2) of the teardrop-shaped trench is 1.5:1 to 2.5:1. This structure can be fabricated using silicone microstructure mold imprinting or femtosecond laser etching, exhibiting good processing repeatability and dimensional control. The teardrop-shaped trench 4 provides gas guidance, water management, and three-phase interface enhancement functions. Its wide top opening facilitates the rapid entry of oxygen or hydrogen into the trench. The streamlined compression structure enhances the gas flow rate and improves the diffusion efficiency of the gas within the catalyst layer. The liquid water generated during the reaction forms a capillary flow along the sidewall of the teardrop-shaped trench 4, gradually flowing from the bottom towards the gas diffusion layer 3 and finally exiting the bipolar plate, significantly reducing the risk of water accumulation and flooding. The sidewall and internal area of ​​the trench provide richer three-phase boundaries, which helps to improve the effective utilization rate of catalyst particles and reaction kinetics.

[0026] Specifically, the catalyst layer 2 is composed of a platinum-carbon catalyst and a perfluorosulfonic acid ionomer (such as Nafion), and is uniformly loaded onto the upper surface of the proton exchange membrane 2 by spraying. The proton exchange membrane 1 has excellent proton conductivity and can effectively isolate the reacting gases at the anode and cathode. The gas diffusion layer 3 is made of carbon paper material treated with PTFE hydrophobicity, with a hydrophobic contact angle of 95°~105° and a porosity of 60%~80%, possessing good gas permeability and water drainage capabilities.

[0027] Example 2

[0028] This embodiment further optimizes the structural parameters of the teardrop-shaped groove 4 based on Embodiment 1. Specifically, the top width of the teardrop-shaped groove 4 is 30 μm, the bottom constriction width is 8 μm, and the groove depth is 10 μm. The direction of the teardrop-shaped groove 4 is consistent with the gas transport direction, and the ratio of the length of the top expansion section (S1) to the length of the bottom contraction section (S2) is 2. The sidewall of the teardrop-shaped groove 4 is provided with a hydrophobic-hydrophilic gradient coating with a contact angle of 100° to enhance the capillary discharge capability of liquid water. The fabrication process involves PDMS elastic mold microimprinting combined with hot pressing or femtosecond laser etching with controlled energy density of 1 J / cm³. - ². The catalyst layer is composed of a platinum-carbon catalyst and a perfluorosulfonic acid ionomer, and the gas diffusion layer 3 is PTFE-treated carbon paper with a porosity of 70%.

[0029] CFD simulation results show that, compared with the trenchless catalyst layer, this invention can achieve a 25cm... 2 The proton exchange membrane fuel cell exhibits an 18% increase in internal oxygen transport rate, a 35% increase in liquid water discharge rate, and a peak power density increase from 0.96 W / cm³. -2Increased to 1.08 W cm -2 The increase was 12.5%.

[0030] In summary, the embodiments of this utility model, by introducing a water droplet-shaped trench structure on the surface of the catalyst layer, achieve synergistic optimization of gas guidance, liquid water drainage, and enhanced electrochemical reaction in terms of structural design and functional zoning, and have good practicality and industrialization prospects.

[0031] The above are merely specific embodiments of this utility model, but the protection scope of this utility model is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this utility model should be included within the protection scope of this utility model. The protection scope of this utility model should be determined by the protection scope of the stated claims.

Claims

1. A proton exchange membrane electrode with a teardrop-shaped trench structure, comprising a catalyst layer, a proton exchange membrane, and a gas diffusion layer, wherein the proton exchange membrane is located below the catalyst layer, and the gas diffusion layer is located above the catalyst layer, characterized in that, The upper surface of the catalyst layer is uniformly provided with multiple teardrop-shaped grooves along the gas transport direction. The teardrop-shaped grooves include a top expansion section S1 and a bottom contraction section S2 from the gas inlet end to the outlet end. The cross-sectional shape of the teardrop-shaped grooves is a streamlined teardrop structure with a rounded top and a constricted bottom. The ratio of the length of the top expansion section S1 to the length of the bottom contraction section S2 of the teardrop-shaped groove is 1.5 to 2.

5.

2. The proton exchange membrane electrode with a teardrop-shaped trench structure according to claim 1, characterized in that, The teardrop-shaped groove has a top width of 20-50 μm, a bottom narrowing width of less than 10 μm, a depth of 5-20 μm, a top arc radius of 10-25 μm, and a depth-to-width ratio of 0.2-0.

5.

3. The proton exchange membrane electrode with a teardrop-shaped trench structure according to claim 1, characterized in that, The teardrop-shaped grooves are formed by laser etching or micro / nano imprinting technology.

4. The proton exchange membrane electrode with a teardrop-shaped trench structure according to claim 1, characterized in that, The gas diffusion layer is made of hydrophobic carbon paper, with a hydrophobic contact angle of 95°~105° and a porosity of 60%~80%.

5. The proton exchange membrane electrode according to claim 1, characterized in that, The direction of the trench is consistent with the direction of gas diffusion, and the direction of the trench is consistent with the direction of the microporous structure of the gas diffusion layer.

6. The proton exchange membrane electrode according to claim 4, characterized in that, The hydrophobic contact angle of the gas diffusion layer is set to 100°, and the porosity is set to 70%.

7. The proton exchange membrane electrode according to claim 2, characterized in that, The teardrop-shaped groove has a top width of 30 μm, a bottom narrowing width of 8 μm, and a groove depth of 10 μm.

8. The proton exchange membrane electrode according to claim 7, characterized in that, The ratio of the length of the top expansion segment S1 to the length of the bottom contraction segment S2 is 2.

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