阅读说明：本技术 一种快速检测膜电极传质与排水是否正常的方法 (Method for rapidly detecting whether membrane electrode mass transfer and drainage are normal ) 是由 胡里清 于 2021-08-31 设计创作，主要内容包括：本发明涉及一种膜电极性能的检测方法,具体涉及一种快速检测膜电极在整个有效面积范围内的传质与排水是否正常的方法,包括以下步骤：(1)将单电池的正负极接入恒定电压输出,测出电流强度I-(0)；(2)将上述单电池的膜电极取出,在其两侧表面对应位置遮盖绝缘薄膜,然后重新组装成单电池,重新接入上述恒定电压输出,测出电流强度I-(1)；(3)膜电极单侧表面总有效面积记为S-(0),遮盖该侧表面的绝缘薄膜的面积记为S-(1)；(4)当I-(0)/S-(0)＝A-(0),I-(1)/(S-(0)-S-(1))＝A-(1),当A-(0)与A-(1)的比值差异≤10％时,表明燃料电池膜电极从整体上来说传质、排水正常,否则,不正常,从而导致膜电极电流密度分布不均匀。与现有技术相比,通过本发明的检测方法可以快速、简便地判断燃料电池膜电极(MEA)在单电池中传质与排水是否正常。(The invention relates to a method for detecting the performance of a membrane electrode, in particular to a method for rapidly detecting whether mass transfer and drainage of the membrane electrode are normal in the whole effective area range, which comprises the following steps: (1) connecting the positive and negative electrodes of the single battery to constant voltage for output, and measuring current intensity I 0 (ii) a (2) Taking out the membrane electrode of the single cell, covering the insulating films at the corresponding positions on the two side surfaces, then reassembling into the single cell, switching in the constant voltage output again, and measuring the current intensity I 1 (ii) a (3) The total effective area of the one-side surface of the membrane electrode is denoted as S 0 And the area of the insulating film covering the side surface is denoted as S 1 (ii) a (4) When I is 0 /S 0 ＝A 0 ，I 1 /(S 0 ‑S 1 )＝A 1 When A is 0 And A 1 When the difference of the ratios is less than or equal to 10 percent, the mass transfer and the water discharge of the membrane electrode of the fuel cell are normal as a whole, otherwise, the mass transfer and the water discharge are abnormal, so that the current density distribution of the membrane electrode is not uniform. Compared with the prior art, the inventionThe clear detection method can quickly and simply judge whether the mass transfer and the water discharge of the fuel cell Membrane Electrode (MEA) in a single cell are normal.)

1. A method for rapidly detecting whether membrane electrode mass transfer and drainage are normal is characterized by comprising the following steps:

(1) connecting the positive and negative electrodes of the single battery to the two ends of constant voltage discharge, and measuring the current intensity I of the single battery discharging under constant voltage₀；

(2) Taking out the membrane electrode of the single cell, covering the insulating films at the corresponding positions on the two side surfaces, assembling into a single cell, switching in the two ends of the constant voltage discharge, and measuring the current intensity I of the single cell₁；

(3) The total effective area of the one-side surface of the membrane electrode is denoted as S₀And the area of the insulating film covering the side surface is denoted as S₁；

(4)I₀/S₀＝A₀，I₁/(S₀-S₁)＝A₁When A is₀And A₁When the difference of the ratios is less than or equal to 10%, the mass transfer and the water drainage of the membrane electrode of the fuel cell are normal as a whole, otherwise, the mass transfer and the water drainage of the membrane electrode are abnormal, and whether the mass transfer and the water drainage of the membrane electrode are normal is judged by detecting whether the current density distribution of the membrane electrode is uniform or not.

2. The method for rapidly detecting whether membrane electrode mass transfer and water drainage are normal or not according to claim 1, wherein when A is normal, the method is characterized in that₀And A₁Difference in ratio of (2)>Above 10% indicates that the membrane electrode has regional mass transfer and water drainage abnormality as a whole, thereby causing the current density distribution of the membrane electrode to be uneven.

3. The method for rapidly detecting whether mass transfer and water discharge of the membrane electrode are normal or not according to claim 1, wherein the area of the insulating film is 1/5-2/3 of the effective area of the membrane electrode.

4. The method according to claim 1, wherein the insulating film is made of an insulating, water-impermeable and gas-impermeable material.

5. The method for rapidly detecting whether the membrane electrode mass transfer and water drainage are normal or not according to claim 4, wherein the insulating film is made of polyester, polyimide or polytetrafluoroethylene.

6. The method for rapidly detecting whether mass transfer and water discharge of the membrane electrode are normal or not according to claim 1, wherein the thickness of the insulating film is 1-10 μm.

7. The method for rapidly detecting whether mass transfer and water discharge of the membrane electrode are normal or not according to claim 6, wherein the thickness of the insulating film is 2-6 μm.

8. The method of claim 1, wherein the position of the insulating film covering the membrane electrode is adjusted, the current intensity of the membrane electrode at different positions is measured, and whether the mass transfer and the water discharge of each part of the membrane electrode are normal is determined.

9. The method for rapidly detecting whether mass transfer and drainage of the membrane electrode are normal or not according to claim 1, wherein the mass transfer and drainage are judged to be normal by repeating the steps (2) - (4) for 3-5 times.

10. The method for rapidly detecting whether the mass transfer and water discharge of the membrane electrode are normal or not according to claim 1 or 8, characterized in that when the mass transfer and water discharge are judged to be normal, insulating films with different areas are adopted to cover different parts of the membrane electrode, and whether the mass transfer and water discharge of the whole membrane electrode are normal or not is judged.

Technical Field

The invention relates to a detection method of membrane electrode performance, in particular to a method for rapidly detecting whether membrane electrode mass transfer and drainage are normal.

Background

A Membrane Electrode Assembly (MEA) is a place where electrochemical reactions occur in a proton exchange Membrane fuel cell, and is a core link of fuel cell technology. The membrane electrode is the 'chip' of the proton exchange membrane fuel cell, and the cost of the membrane electrode accounts for more than 60% of the total cost of the fuel cell stack.

Generally, a Membrane Electrode Assembly (MEA) or CCM produced and prepared is subjected to performance test evaluation in a single cell or a short stack of a fuel cell, and mainly relates to the influences of current, voltage, polarization curves and air flow metering ratios on membrane electrode performance, current-voltage discharge curves and performance curves, influences of hydrogen flow metering ratios on the discharge curves and current-voltage performance curves of the membrane electrode, whether drainage is normal or not and the like. Wherein, whether the water discharged from the bipolar plate is normal or not can affect the mass transfer and diffusion of air and hydrogen in the single cell membrane electrode, and further can affect the working performance and the working efficiency of the fuel cell. The mass transfer comprises the timely diffusion of oxygen in the air and the electrochemical reaction after the oxygen permeates into the membrane electrode, and also comprises the timely diffusion of hydrogen and the electrochemical reaction after the hydrogen permeates into the membrane electrode. The process of permeation and diffusion is influenced by various factors such as the thickness of the carbon diffusion layer material, whether the drainage is normal and the like.

The output performance of the membrane electrode can be measured by testing the membrane electrode of the fuel cell, and the working state of the membrane electrode can be represented by some electrochemical testing means. Common membrane electrode testing methods mainly include polarization curve testing, linear potential scanning testing, alternating current impedance testing and the like, and can be used for investigating the power generation performance of a membrane electrode, the active area of a catalyst, the hydrogen permeation quantity of the membrane electrode, the contact impedance of the membrane electrode and the like. When a large amount of water is generated and accumulated in the membrane electrode, permeation, diffusion, and mass transfer of air and hydrogen are affected, thereby affecting various properties of the fuel cell and the unit cell, which can be reflected from the current-voltage polarization curve of the membrane electrode. The current technology for testing the current density distribution of membrane electrode is that the effective area of membrane electrode is divided into several equal parts, and under the same test condition the membrane electrodes are made into independent small cells, and the positive and negative electrodes are separately connected, and the discharge result is separately tested.

Disclosure of Invention

The invention aims to provide a method for rapidly detecting whether mass transfer and drainage of a membrane electrode are normal or not by detecting whether current density distribution on the whole membrane electrode is uniform or not, so as to solve the problem that whether mass transfer and drainage of the membrane electrode are normal or not is difficult to judge in the prior art, and realize rapid and simple detection of mass transfer and drainage conditions of the membrane electrode.

The purpose of the invention is realized by the following technical scheme:

a method for rapidly detecting whether membrane electrode mass transfer and drainage are normal comprises the following steps:

(1) connecting the positive and negative electrodes of the single battery to the two ends of constant voltage discharge, and measuring the current intensity I of the single battery discharging under constant voltage₀；

(2) Taking out the membrane electrode of the single cell, covering the insulating films at the corresponding positions on the two side surfaces, assembling into a single cell, switching in the two ends of the constant voltage discharge, and measuring the current intensity I of the single cell₁；

(3) The total effective area of the one-side surface of the membrane electrode is denoted as S₀And the area of the insulating film covering the side surface is denoted as S₁；

(4)I₀/S₀＝A₀，I₁/(S₀-S₁)＝A₁When A is₀And A₁When the difference of the ratios is less than or equal to 10%, the mass transfer and the water drainage of the membrane electrode of the fuel cell are normal as a whole, otherwise, the mass transfer and the water drainage of the membrane electrode are abnormal, and whether the mass transfer and the water drainage of the membrane electrode are normal is judged by detecting whether the current density distribution of the membrane electrode is uniform or not.

When A is₀And A₁Difference in ratio of (2)>When the concentration is more than 10%, the mass transfer and water drainage of the membrane electrode as a whole are abnormal, so that the current density distribution of the membrane electrode is not uniform, and the membrane electrode needs to be replaced.

Wherein, I₀/S₀Refers to the current intensity I of the normal uncovered membrane electrode discharging at a specified constant voltage₀Total effective area S with membrane electrode₀The ratio in square centimeters is designated A₀；

I₁/(S₀-S₁) Is the I discharge under the same operation conditions (specified constant voltage discharge, same hydrogen and air metering ratio, temperature and the like) after the corresponding positions on the two side surfaces of the membrane electrode cover the insulating film₁/(S₀-S₁) A ratio.

Preferably, the area of the insulating film is 1/5-2/3 of the effective area of the membrane electrode.

Preferably, the area of the insulating film is 1/3-2/3 of the effective area of the membrane electrode.

Preferably, the insulating film is made of an insulating, waterproof and airtight material.

Preferably, the insulating film is made of polyester, polyimide or polytetrafluoroethylene.

Preferably, the thickness of the insulating film is 1-10 μm.

Preferably, the thickness of the insulating film is 2-6 μm.

Preferably, the position of the insulating film covering the membrane electrode is adjusted, the current intensity of the membrane electrode at different positions is measured, and whether mass transfer and drainage of each part of the membrane electrode are normal or not is judged.

Preferably, repeating the steps (2) - (4) for 3-5 times, and judging that the mass transfer and the drainage are normal.

Preferably, when mass transfer and water drainage are judged to be normal, insulating films with different areas are adopted to cover different parts of the membrane electrode, and whether the mass transfer and the water drainage of the whole membrane electrode are normal is judged.

The working principle of the invention is as follows:

the method for judging whether the membrane electrode mass transfer and water drainage are normal or not by detecting whether the current density distribution on the whole membrane electrode is uniform or not includes the steps of firstly, measuring the current intensity of the membrane electrode under the condition that an insulating film is not covered under a certain operation condition, and marking as an initial value I₀(ii) a Covering insulating films with known areas on the corresponding positions of the upper surface and the lower surface of the membrane electrode, measuring the current intensity of the membrane electrode in the state under the same operation condition as the previous measurement, and recording as an experimental value I₁. When the membrane electrode I is not covered normally₀/S₀(intensity of current discharged at a given constant voltage I₀Total effective area S with membrane electrode₀The ratio (square centimeter) is denoted as A₀)，A₀/S₀Shielding at the positions corresponding to the two side surfaces of the membrane electrodeI discharge under the same operating conditions (specified constant voltage discharge, same hydrogen, air metering ratio, temperature, etc.) after covering with an insulating film₁/(S₀-S₁) The same ratio indicates that the mass transfer and water drainage of the membrane electrode of the fuel cell are normal, such as I₀/S₀<I₁/(S₀-S₁) And the difference in the ratio>When the concentration is more than 10%, the mass transfer and water drainage of the membrane electrode are abnormal.

Compared with the prior art, the invention has the following beneficial effects:

1. the detection method of the invention can quickly and simply judge whether the mass transfer and the water discharge of the fuel cell Membrane Electrode (MEA) in a single cell are normal.

2. The detection method only needs to measure the current intensity under the constant voltage, can obtain the result through simple calculation, has strong applicability, can be accessed into a computer program and a control device to realize automatic detection, can also carry out manual calculation when automatic equipment is lacked or necessary, and judges whether the mass transfer and the drainage of the membrane electrode are normal or not by detecting whether the current density distribution on the whole membrane electrode is uniform or not.

Detailed Description

The present invention will be described in detail below with reference to specific examples.

A method for rapidly detecting whether membrane electrode mass transfer and drainage are normal comprises the following steps:

(1) connecting the positive and negative electrodes of the single battery to the two ends of constant voltage discharge, and measuring the current intensity I of the single battery discharging under constant voltage₀；

(2) Taking out the membrane electrode of the single cell, covering the insulating films at the corresponding positions on the two side surfaces, assembling into a single cell, switching in the two ends of the constant voltage discharge, and measuring the current intensity I of the single cell₁；

(3) The total effective area of the one-side surface of the membrane electrode is denoted as S₀And the area of the insulating film covering the side surface is denoted as S₁；

(4)I₀/S₀＝A₀，I₁/(S₀-S₁)＝A₁When A is₀And A₁When the difference of the ratios is less than or equal to 10 percent, the mass transfer and the water discharge of the membrane electrode of the fuel cell are normal, otherwise, the mass transfer and the water discharge are abnormal. When A is₀And A₁Difference in ratio of (2)>When the water content is more than 10%, the mass transfer and drainage of the membrane electrode are abnormal, and the membrane electrode needs to be replaced.

The area of the insulating film is 1/5-2/3 of the area of the membrane electrode, more specifically 1/3-2/3. The insulating film is made of an inert, insulating, waterproof, air-impermeable, harmless and stable material, and more specifically, Polyester (PET), Polyimide (PI), or Polytetrafluoroethylene (PTFE). The thickness of the insulating film is 1 to 10 μm, more specifically, 2 to 6 μm. The insulating film is adhered to the front and back sides of the membrane electrode by a small amount of double-sided adhesive tape with the thickness of 1 μm, and the covered area, shape and position need to be kept the same.

The detection method also needs to adjust the position of the insulating film covering the membrane electrode to determine the current intensity of the membrane electrode at different positions and judge whether the mass transfer and the water drainage of each part of the membrane electrode are normal or not; or adopting insulating films with different areas to cover different parts of the membrane electrode and judging whether the mass transfer and the water drainage of the whole membrane electrode are normal or not. And (3) repeating the steps (2) - (4) for 3-5 times in the whole detection process, and judging that the mass transfer and the water drainage of each position are normal, namely judging that the mass transfer and the water drainage of the whole membrane are normal.

Example 1

For effective area S₀Is 300cm²The measurement of the membrane electrode for a vehicle according to (1) is carried out by first measuring the current intensity of the membrane electrode when the insulating film is not covered: assembling the membrane electrode into a single cell, connecting two ends of 0.6V voltage, setting the hydrogen metering ratio to be 1.2 and the air metering ratio to be 2.5, operating the membrane electrode at 65 ℃, operating the membrane electrode under the condition that the relative humidity of hydrogen and air is 60 percent, and measuring the current density to be 1A/cm²Current intensity I₀Is 300A.

The thickness is 2 μm, the area covered is S₁Is 150cm²The polyester insulating films are sequentially covered on the effective areas of the upper part and the lower part of the membrane electrode, and the current intensity I is measured under the same operation condition₁In order to achieve the effect of 151A,

A₀＝I₀/S₀＝1A/cm²，A₁＝I₁/(S₀-S₁)＝1.01A/cm²it can be seen that A₀/S₀And A₁/(S₀-S₁) The mass transfer and water drainage of the upper and lower membrane electrodes are normal, which can be indicated as effective power generation.

Example 2

The same membrane electrode for vehicle (effective area S) as in example 1 was used₀Is 300cm²) The test under the same operating conditions as in example 1 gave the current intensity I when the insulating film was uncovered₀Is 300A, A₀＝I₀/S₀＝1A/cm²。

The thickness was 6 μm and the area S covered₁Is 150cm²The polyimide insulating films are sequentially covered on the effective areas of the upper part and the lower part of the membrane electrode, and the current intensity I is measured₁Is 130A, A₁＝I₁/(S₀-S₁)＝0.87A/cm²(ii) a Taking out the membrane electrode, moving the insulating film to the effective area of the upper part and the lower part of the membrane electrode, covering the area S₂Is still 150cm²Measured, current intensity I₂Is 170A, A₂＝I₂/(S₀-S₂)＝1.13A/cm². The ratios of A1 and A2 to A0 exceed 10%, which indicates that the mass transfer and water drainage of the upper and lower membrane electrodes in the left half part of the membrane electrode are abnormal.

It can be shown that the membrane electrode is not properly mass-transferred and drained in some areas.

Example 3

The same membrane electrode for vehicle (effective area S) as in example 1 was used₀Is 300cm²) The test under the same operating conditions as in example 1 gave the current intensity I when the insulating film was uncovered₀Is 300A, A₀＝I₀/S₀＝1A/cm²。

The thickness was 3 μm and the area S covered₁Is 100cm²The polytetrafluoroethylene insulating films are sequentially covered on the effective areas of the upper part and the lower part of the membrane electrodeMeasured, current intensity I₁Is 204A, A₁＝I₁/(S₀-S₁)＝1.02A/cm²；A₀And A₁The difference of the ratio is less than or equal to 10 percent, which can indicate that the mass transfer and the water drainage of the part of the membrane electrode are normal and belong to effective power generation. Taking out the membrane electrode, removing the insulating film at the position, changing the position of the insulating film, measuring at the position where the effective area of the membrane electrode is not measured for 3 times until the whole membrane electrode is measured, and measuring the current intensity I_xThe results of (a) were 204A (x ═ 1), 201A (x ═ 2), 213A (x ═ 3), and 210A (x ═ 4), respectively, and the current densities were 1.02A/cm, respectively²、1.01A/cm²、1.07A/cm²、1.05A/cm²Can be seen to be in the form of₀The ratio of the water to the membrane electrode is less than 10%, which can indicate that the mass transfer and the water drainage of the whole membrane electrode are normal and belongs to effective power generation.

Example 4

The same membrane electrode for vehicle (effective area S) as in example 1 was used₀Is 300cm²) The test under the same operating conditions as in example 1 gave the current intensity I when the insulating film was uncovered₀Is 300A, A₀＝I₀/S₀＝1A/cm²。

The thickness was 7 μm and the area S covered₁Is 60cm²The polyester insulating films are sequentially covered on the effective areas of the upper part and the lower part of the membrane electrode, and the current intensity I is measured₁Is 250A, A₁＝I₁/(S₀-S₁)＝1.04A/cm²(ii) a And A is₀Ratio of<0.1, the mass transfer and water drainage of the part of the membrane electrode are normal, and the part belongs to effective power generation. Taking out the membrane electrode, removing the insulating film at the position, changing the area and position of the insulating film, measuring for 4 times at the position where the effective area of the membrane electrode is not measured until the whole membrane electrode is measured, and measuring the covering area S of the insulating film_xAre respectively 60cm²(x＝1)、100cm²(x＝2)、150cm²(x＝3)、180cm²(x-4) and 200cm²(x-5), measured Current intensity I_xThe results of (a) were 250A (x ═ 1), 208A (x ═ 2), and 151A (x ═ 3), respectively) 129A (x ═ 4) and 105A (x ═ 5), and the current densities were 1.04A/cm and 5, respectively²、1.04A/cm²、1.01A/cm²、1.08A/cm²、1.05A/cm²Can be seen to be in the form of₀The ratio of the water to the membrane electrode is less than 10%, which can indicate that the mass transfer and the water drainage of the whole membrane electrode are normal and belongs to effective power generation.

The embodiments described above are described to facilitate an understanding and use of the invention by those skilled in the art. It will be readily apparent to those skilled in the art that various modifications to these embodiments may be made, and the generic principles described herein may be applied to other embodiments without the use of the inventive faculty. Therefore, the present invention is not limited to the above embodiments, and those skilled in the art should make improvements and modifications within the scope of the present invention based on the disclosure of the present invention.