WO2022022053A1

WO2022022053A1 - Method and apparatus for measuring permeability and diffusion coefficient of gas diffusion layer for fuel cell

Info

Publication number: WO2022022053A1
Application number: PCT/CN2021/097648
Authority: WO
Inventors: 邱殿凯; 黄福享; 彭林法; 易培云; 来新民
Original assignee: 上海交通大学
Priority date: 2020-07-31
Filing date: 2021-06-01
Publication date: 2022-02-03
Also published as: CN111896453A; CN111896453B

Abstract

A method and apparatus for measuring the permeability and diffusion coefficient of a gas diffusion layer for a fuel cell. The apparatus comprises a gas source (12), a gas flow controller (10), a humidifying system (9), a temperature control system (11), a clamping device, a state monitoring module and a signal receiving module (6), wherein the clamping device comprises upper pressing blocks (5, 8), a lower pressing block (13), an upper porous metal block (7), a lower porous metal block (15), an O-shaped ring (4) and a sealing ring (16); a measured gas diffusion layer (14) is sandwiched between the upper pressing blocks (5, 8) and the lower pressing block (13); the upper porous metal block (7) is clamped in the upper pressing blocks (5, 8); and the lower porous metal block (15) is clamped in the lower pressing block (13). The measurement of the gas permeability and diffusion coefficient in the thickness and in-plane directions of the gas diffusion layer in a compression state in an environment with a controllable temperature and humidity can be achieved, the operation is convenient, and the mass transfer characteristics of different gas diffusion layers can be evaluated according to the measurement result of the apparatus.

Description

Method and equipment for measuring permeability and diffusion coefficient of gas diffusion layer for fuel cell

technical field

The invention belongs to the technical field of fuel cells, and in particular relates to a method and device for measuring permeability and diffusion coefficient in a compressed state of a gas diffusion layer of a fuel cell.

Background technique

A fuel cell is a "chemical energy power generation" device that directly converts chemical energy in raw materials into electrical energy. Its energy conversion efficiency is not limited by the Carnot cycle, and the power generation efficiency of the battery pack can reach more than 50%. It has excellent starting characteristics and high energy conversion efficiency, and is expected to be applied in many fields.

In recent years, with the continuous efforts of researchers from various countries, the overall performance of fuel cells has been greatly improved, but in order to meet the needs of different applications, fuel cells with high power density and high stability still need to be continuously developed. In fuel cells, the gas diffusion layer plays a crucial role in the diffusion of reactant gases and the management of water, so it is necessary to deeply understand the various mass transfer processes that occur in the gas diffusion layer of fuel cells. The gas diffusion layer is the transport channel for the reaction gas and the reaction product water. It can be seen from the electron microscope scanning pictures of the gas diffusion layer that the structure of the gas diffusion layer has obvious anisotropy, which is bound to cause the anisotropy of mass transfer in the gas diffusion layer. At the same time, in the fuel cell assembly and operating environment, the complex working conditions make the mass transfer characteristics of the gas diffusion layer more complex and diverse. The research shows that the main transport mode of gas in the gas diffusion layer is diffusion, and also includes part of the convective mass transfer. Therefore, it is of great significance to design a gas diffusion layer permeability and diffusion coefficient measurement device for fuel cells.

It is found through the literature search of the prior art that there are few measuring devices for the permeability and diffusion coefficient of the gas diffusion layer of the fuel cell. However, the device can only measure the intrinsic gas permeability in the thickness direction of the gas diffusion layer, and cannot characterize the mass transfer anisotropy of the gas diffusion layer under assembly compression and complex working conditions. US Patent US7913572B2 discloses a comprehensive testing system for gas diffusion layer compression properties of polymer electrolyte fuel cells. The system can measure the intrinsic permeability of the gas diffusion layer in the thickness direction and the in-plane permeability, but cannot measure the gas diffusion layer in the compressed state. The permeability in the thickness direction, and the diffusion coefficient in the thickness direction and the in-plane direction of the gas diffusion layer cannot be tested, and the temperature and humidity of the diffused gas are also uncontrollable.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a method and device for measuring the permeability and diffusion coefficient of the gas diffusion layer of a fuel cell in a compressed state in order to overcome the above-mentioned defects of the prior art, which can realize the compression of the gas diffusion layer in a controlled temperature and humidity environment. Gas permeability and diffusion coefficient measurements in the lower thickness and in-plane directions.

The object of the present invention can be realized through the following technical solutions:

A device for measuring the permeability and diffusion coefficient of a fuel cell gas diffusion layer in a compressed state, which is used to measure and evaluate the gas permeability and diffusion coefficient in the thickness direction and in-plane direction under the compressed gas diffusion layer in a temperature-controlled environment. Mass transfer properties of different gas diffusion layers. The measuring equipment includes a gas source, a gas flow controller, a humidification system, a temperature control system, a clamping device, a state monitoring module and a signal receiving module. The clamping device includes an upper pressure block and a lower pressure block. The upper pressing block and the lower pressing block are both flat plates with grooves in the middle, and gas inlets and outlets running through the flat plates are arranged on the side walls of the grooves. A longitudinal gas channel is formed, a transverse gas channel is formed between the upper pressure block and the lower pressure block, and the measured gas diffusion layer is sandwiched in the transverse gas channel formed between the upper pressure block and the lower pressure block, and the measured gas diffuses There are detachable sealing rings at both ends of the layer, and the measured gas flows out through the flow controller, and then reaches the clamping device after passing through the humidification system and the temperature control system. All sensors, flow controllers, temperature control systems and humidification systems are connected to the signal receiving module to record all experimental data in real time.

Preferably, an upper porous metal block and a lower porous metal block are provided on the upper and lower surfaces of the part of the gas diffusion layer to be measured located in the longitudinal gas channel, the upper porous metal block is clamped in the upper pressing block, and the lower porous metal block is clamped in the lower in the block. The upper pressing block is divided into an upper pressing block 1 and an upper pressing block 2. An O-ring for sealing is arranged between the upper pressing block 1 and the upper pressing block 2, which are connected by bolts, and the two parts are extruded through the O-ring in the middle. ring for sealing. The sample of the gas diffusion layer to be tested is sandwiched between the upper pressure block and the lower pressure block. In order to avoid dislocation of the assembly, the upper and lower pressure blocks are respectively provided with positioning holes. The degree of compression, the upper and lower pressure blocks exert clamping force through bolts or cylinders.

Further, the upper porous metal block and the lower porous metal block are made of metal materials with higher rigidity and far greater air permeability than the measured gas diffusion layer, including titanium alloy or stainless steel; the upper porous metal block and the lower porous metal block are respectively installed. It is clamped in the upper pressing block and the lower pressing block, and the dimensional accuracy and flatness of the assembly surfaces of the upper porous metal block and the lower porous metal block and the upper pressing block and the lower pressing block are controlled within 0.001.

Further, the sealing ring is a movable sealing ring, which can be freely assembled and disassembled, and the inner side of the sealing ring is close to the measured gas diffusion layer, and the distance between the outer side and the edge of the upper and lower pressing blocks is not more than 1mm.

Further, the heating method of the temperature control system is electric heating or circulating water bath heating, and the temperature control system simultaneously controls the gas pipeline and the gas temperature in the clamping device to ensure that the gas in the clamping device is stable at a specified temperature and humidity.

Further, the state monitoring module includes an oxygen concentration sensor, a temperature and humidity sensor and a differential pressure sensor; the oxygen concentration sensor, the temperature and humidity sensor, the differential pressure sensor, the gas flow controller, the temperature control system and the humidification system are all Connected to the signal receiving module to record all experimental data in real time.

The oxygen concentration sensor is installed in the lower pressing block, and the probe of the oxygen concentration sensor is closely attached to the gas diffusion layer to be measured, the measurement range of the oxygen concentration sensor is 0-100%, and the measurement accuracy is 0.01%;

The two probes of the differential pressure sensor are respectively installed in the second upper pressure block and the lower pressure block, so that they are connected to the upper and lower chambers, and the distance between the pressure measuring point and the gas diffusion layer to be measured is less than 1mm, and the The measurement range is 0 ~ 10kPa, and the measurement accuracy is 1Pa.

A method for using a device for measuring permeability and diffusion coefficient in a compressed state of a gas diffusion layer of a fuel cell, the method includes a method for measuring the permeability in the thickness direction of the gas diffusion layer, a method for measuring the diffusion coefficient in the thickness direction of the gas diffusion layer, and a method for measuring the permeability in the direction of the gas diffusion layer. rate measurement method, and directional diffusion coefficient measurement method within the gas diffusion layer.

Specifically, the method for measuring the permeability in the thickness direction of the gas diffusion layer includes the following steps:

(i) Clamp the gas diffusion layer to be tested between the upper pressing block and the lower pressing block, apply pressure on the upper and lower pressing blocks, and control it to be in the specified compression rate state;

(ii) The measured gas with the specified flow rate and temperature and humidity enters the clamping device through the gas port on the upper pressure block, and is discharged into the gas recovery device from the gas outlet of the lower pressure block through the measured gas diffusion layer;

(iii) By measuring the pressure difference of the measured gas passing through the gas diffusion layer, the permeability in the thickness direction of the gas diffusion layer is calculated according to the Darcy's law of porous materials;

Specifically, the method for measuring the diffusion coefficient in the thickness direction of the gas diffusion layer includes the following steps:

(ii) Enter the nitrogen gas into the clamping device through the gas port on the upper pressure block, and discharge it into the gas recovery device from the gas outlet of the lower pressure block through the gas diffusion layer to be measured, and use nitrogen to purge for more than 5 minutes until the clamping device is installed. The device and the gas diffusion layer to be tested are all filled with nitrogen, the oxygen concentration sensor shows that the oxygen concentration is 0, and the nitrogen supply is stopped;

(iii) Immediately plug the gas outlet of the lower pressure block, and remove the upper pressure block, so that the gas diffusion layer to be measured is filled with air as soon as possible, and the oxygen concentration sensor is used to record the oxygen in the air to the lower part of the gas diffusion layer to be measured. side diffusion process;

(iv) By measuring the change curve of the oxygen concentration on the lower side of the measured gas diffusion layer, the diffusion coefficient in the thickness direction of the gas diffusion layer is calculated according to Fick's diffusion law;

Specifically, the method for measuring the in-direction permeability of the gas diffusion layer comprises the following steps:

(i) Remove the sealing ring, the upper porous metal block and the lower porous metal block, and plug the gas outlet of the lower pressing block;

(ii) Clamp the gas diffusion layer to be tested between the upper and lower pressing blocks, and apply pressure to the upper and lower pressing blocks to control it under the specified compression rate state;

(iii) The measured gas with the specified flow rate and temperature and humidity enters the clamping device through the gas inlet of the upper pressure block, and is discharged from the surrounding to the gas recovery device through the measured gas diffusion layer;

(iv) By measuring the pressure difference of the measured gas passing through the gas diffusion layer, the permeability in the direction of the gas diffusion layer is calculated according to Darcy's law of porous materials;

Specifically, the method for measuring the directional diffusion coefficient in the gas diffusion layer includes the following steps:

(iii) The nitrogen gas enters the clamping device through the gas inlet of the upper pressure block, and is discharged from the surrounding to the gas recovery device through the gas diffusion layer to be measured, and is purged with nitrogen for more than 5 minutes until the clamping device and the measured gas are diffused. The layer (14) is completely filled with nitrogen, and the oxygen concentration sensor shows that the oxygen concentration is 0, and the introduction of nitrogen is stopped;

(iv) The oxygen concentration sensor records the process of oxygen in the air diffusing into the clamping device through the measured gas diffusion layer. By measuring the change curve of the oxygen concentration inside the clamping device, the inner direction of the gas diffusion layer can be calculated according to Fick's diffusion law. Diffusion coefficient.

Compared with the prior art, the present invention can realize the measurement of gas permeability and diffusion coefficient in the thickness direction and in-plane direction of the gas diffusion layer under the condition of compression of the gas diffusion layer in a controlled temperature and humidity environment. Realize the gas permeability and diffusion coefficient measurement in the thickness direction and in-plane direction of the gas diffusion layer, save the measurement cost, reduce the experimental error, and the operation is simple. Chemical simulation provides gas diffusion layer parameter input with the following advantages:

1) One device can realize the gas permeability and diffusion coefficient measurement in the thickness direction and in-plane direction of the gas diffusion layer, which saves the measurement cost, reduces the experimental error, and is easy to operate;

2) The invention can realize the measurement of gas permeability and diffusion coefficient under the condition of compression of the gas diffusion layer in a controlled temperature and humidity environment.

Description of drawings

FIG. 1 is a schematic diagram of a device for measuring the permeability and diffusion coefficient of a fuel cell gas diffusion layer.

In the figure, 1-temperature and humidity sensor, 2-oxygen concentration sensor, 3-differential pressure sensor, 4-O-ring, 5-upper pressure block 1, 6-signal receiving module, 7-upper porous metal block, 8-upper Briquetting 2, 9-humidification system, 10-gas flow controller, 11-temperature control system, 12-air source, 13-lower briquette, 14-measured gas diffusion layer, 15-lower porous metal block, 16 - Sealing ring.

detailed description

The present invention will be described in detail below with reference to specific embodiments. The following examples will help those skilled in the art to further understand the present invention, but do not limit the present invention in any form. It should be pointed out that for those skilled in the art, without departing from the concept of the present invention, several modifications and improvements can be made, which all belong to the protection scope of the present invention.

Example

A fuel cell gas diffusion layer permeability and diffusion coefficient measurement equipment, as shown in Figure 1, the equipment includes: a gas source 12, a gas flow controller 10, a humidification system 9, a temperature control system 11, a clamping device, Status monitoring module and signal receiving module 6 .

The clamping device includes an upper pressure block 1 5 , an upper pressure block 2 8 , a lower pressure block 13 , an upper porous metal block 7 , a lower porous metal block 15 , an O-ring 4 and a sealing ring 16 . The upper pressing block 1 5 and the upper pressing block 2 8 are connected by bolts, and the two parts are sealed by pressing the O-ring 4 in the middle. The sealing ring 16 is a movable sealing ring, which can be freely assembled and disassembled, and it is close to the measured gas diffusion layer 14 inward, and the distance between the outward and the edge of the upper and lower pressing blocks is 1mm. The gas diffusion layer 14 to be tested is sandwiched between the second upper pressing block 8 and the lower pressing block 13 . The upper and lower pressure blocks are respectively provided with positioning holes, and the compression degree of the gas diffusion layer 14 is controlled by the spacer between the upper and lower pressure blocks. Both the upper porous metal block 7 and the lower porous metal block 15 are made of stainless steel, and their air permeability is much greater than that of the measured gas diffusion layer. The upper porous metal block 7 is clamped in the upper pressing block 2 8 , the lower porous metal block 15 is clamped in the lower pressing block 13 , and the dimensional accuracy and flatness of the outer surface of the porous metal block and the assembly surface of the pressing block are 0.01. The state monitoring module includes an oxygen concentration sensor 2, a temperature and humidity sensor 1, and a differential pressure sensor 3. The oxygen concentration sensor 2 is installed in the lower pressing block 13, and the probe of the oxygen concentration sensor 2 is closely attached to the measured gas diffusion layer 14. The oxygen concentration The measurement range of the sensor 2 is 0-100%, and the measurement accuracy is 0.01%. The two probes of the differential pressure sensor 3 are respectively installed in the upper pressure block 2 8 and the lower pressure block 13, and the distance between the pressure measurement points and the gas diffusion layer 14 to be measured is 1mm, and the measurement range of the pressure difference sensor is 0 ~ 10kPa , the measurement accuracy is 1Pa. The measured gas is compressed air, the compressed air flows out through the gas flow controller 10, passes through the humidification system 9 and the temperature control system 11, and then reaches the clamping device. The humidification system 9 is set to a relative humidity of 60%, and the temperature control system 11 simultaneously controls the gas pipeline and the clamping device to maintain the same temperature, so that the measured gas is stabilized at a relative humidity of 60% in the gas pipeline and the clamping device. The oxygen concentration sensor 2 , the temperature and humidity sensor 1 , the differential pressure sensor 3 , the gas flow controller 10 , the temperature control system 11 and the humidification system 9 are all connected to the signal receiving module 6 to record all experimental data in real time.

The invention can realize the measurement of gas permeability and diffusion coefficient in the thickness direction and in-plane direction of the gas diffusion layer under the condition of compression of the gas diffusion layer in a controlled temperature and humidity environment. The specific working process includes the gas diffusion layer thickness direction permeability measurement process, gas Diffusion layer thickness direction diffusion coefficient measurement process, gas diffusion layer direction permeability measurement process, gas diffusion layer direction diffusion coefficient measurement process.

1. The gas diffusion layer thickness direction permeability measurement process includes the following steps:

(1) Clamp the measured gas diffusion layer 14 with an initial thickness of 180 μm between the upper and lower pressure blocks, and place spacers with a thickness of 144 μm around the gas diffusion layer, tighten the bolts, and control the torque at 15N m, The gas diffusion layer is controlled at 20% compressibility through the pad;

(2) Set the gas flow controller 10 so that the compressed air flow is controlled at 1 L/min. Set the humidification system 9, control the relative humidity of the outlet gas of the humidification system 9 to be 60%, set the temperature control system 11 to control the gas pipeline and the clamping device to maintain the same temperature, so that the measured gas is in the gas pipeline and the clamping device. The device is stabilized at 60% relative humidity. The humidified compressed air enters the clamping device through the inlet of the upper pressure block 15, and is discharged into the atmosphere from the gas outlet of the lower pressure block 13 after passing through the measured gas diffusion layer 14;

(3) Record the pressure difference when 1L/min compressed air passes through the gas diffusion layer, and calculate the permeability in the thickness direction of the gas diffusion layer under the condition of 20% compressibility according to Darcy's law of porous materials;

where k is the permeability, μ is the gas viscosity, ΔP is the differential pressure, and v is the velocity of the gas passing through the porous material.

(4) Similarly, by adjusting the compressed air flow rate, the degree of humidification and the thickness of the pad, the permeability of the gas diffusion layer in the thickness direction in a controlled temperature and humidity environment and under different compression conditions can be obtained.

2. The measurement process of the diffusion coefficient in the thickness direction of the gas diffusion layer includes the following steps:

(2) Set the gas flow controller 10 to 2L/min, and enter the nitrogen gas with a purity of 99.999% into the clamping device through the gas inlet of the upper pressing block 15, and then pass through the gas diffusion layer 14 to be tested and then pass through the lower pressing block 13. The gas outlet is discharged into the gas recovery device, and nitrogen is used to purge for more than 5 minutes, until the clamping device and the measured gas diffusion layer 14 are all filled with nitrogen;

(3) When the oxygen concentration sensor 2 shows that the oxygen concentration is 0, stop feeding nitrogen gas and immediately block the gas outlet of the lower pressure block 13, and remove the upper pressure block 15, so that the measured gas diffusion layer 14 is above the Fill the air with air as soon as possible, and record the diffusion process of oxygen in the air to the lower side of the gas diffusion layer 14 to be measured through the oxygen concentration sensor 2;

(4) Fitting and calculating the variation curve of the oxygen concentration on the lower side of the gas diffusion layer 14 under test with Fick's second law to obtain the thickness direction diffusion coefficient of the gas diffusion layer under the condition of 20% compressibility;

where D is the diffusion coefficient and C is the oxygen concentration.

(5) Similarly, by adjusting the degree of humidification, the temperature and the thickness of the pad, the diffusion coefficient of the gas diffusion layer in the thickness direction can be obtained in a controlled temperature and humidity environment and under different compression conditions.

3. The measurement process of directional permeability in the gas diffusion layer includes the following steps:

(1) on the basis of the equipment shown in Figure 1, remove the sealing ring 16, the upper porous metal block 7 and the lower porous metal block 15, and plug the gas outlet of the lower pressing block 13;

(2) Clamp the measured gas diffusion layer 14 with an initial thickness of 180 μm between the upper and lower pressure blocks, and place spacers with a thickness of 144 μm around the gas diffusion layer respectively, tighten the bolts, and control the torque at 15N·m. The gas diffusion layer is controlled at 20% compressibility through the pad;

(3) Set the gas flow controller 10 so that the compressed air flow is controlled at 1 L/min. Set the humidification system 9, control the relative humidity of the gas at the outlet of the humidification system to 60%, set the temperature control system 11 to control the gas pipeline and the clamping device to maintain the same temperature, so that the measured gas is in the gas pipeline and the clamping device. Stable at 60% relative humidity. The humidified compressed air enters the clamping device through the inlet of the upper pressure block 1 5, and is discharged into the atmosphere from around the gas diffusion layer after passing through the measured gas diffusion layer 14;

(3) Record the pressure difference when 1L/min compressed air passes through the gas diffusion layer, and calculate the inward permeability of the gas diffusion layer under the condition of 20% compressibility according to Darcy's law of porous materials;

(4) In the same way, by adjusting the compressed air flow rate, the degree of humidification and the thickness of the pad, the permeability of the gas diffusion layer in the inward direction under the controllable temperature and humidity environment and under different compression conditions can be obtained.

4. The measurement process of the directional diffusion coefficient in the gas diffusion layer includes the following steps:

(1) On the basis of the equipment shown in FIG. 1, remove the sealing ring 16, the upper porous metal block 7 and the lower porous metal block 15, and plug the gas outlet of the lower pressing block 13;

(3) Set the flow controller to 2L/min, enter the nitrogen gas with a purity of 99.999% into the clamping device through the inlet of the upper pressure block 15, and discharge it into the gas recovery device from the surrounding after passing through the measured gas diffusion layer 14 , use nitrogen to purge for more than 5 minutes, until the clamping device and the measured gas diffusion layer 14 are all filled with nitrogen, the oxygen concentration sensor 2 shows that the oxygen concentration is 0, and the nitrogen is stopped;

(4) The oxygen concentration sensor 2 records the process that the oxygen in the air diffuses from the surrounding through the gas diffusion layer 14 to be measured into the clamping device. Fitting the change curve of oxygen concentration inside the clamping device with Fick's second law to calculate the inward diffusion coefficient of the gas diffusion layer under the condition of 20% compressibility;

(5) In the same way, by adjusting the degree of humidification, temperature and thickness of the pad, the diffusion coefficient of the gas diffusion layer in the inward direction can be obtained in a controlled temperature and humidity environment and under different compression conditions.

The foregoing description of the embodiments is provided to facilitate understanding and use of the invention by those of ordinary skill in the art. It will be apparent to those skilled in the art that various modifications to these embodiments can be readily made, and the generic principles described herein can be applied to other embodiments without inventive step. Therefore, the present invention is not limited to the above-mentioned embodiments, and improvements and modifications made by those skilled in the art according to the disclosure of the present invention without departing from the scope of the present invention should all fall within the protection scope of the present invention.

Claims

A device for measuring the permeability and diffusion coefficient of a gas diffusion layer of a fuel cell, comprising a gas source (12), a gas flow controller (10), a humidification system (9), a temperature control system (11), a clamping device, and state monitoring A module and a signal receiving module (6), the clamping device includes an upper pressing block and a lower pressing block (13), and the upper pressing block and the lower pressing block (13) are flat plates with grooves in the middle, The side wall of the groove is provided with a gas inlet and an outlet running through the flat plate, and the grooves on the upper pressure block and the lower pressure block (13) are symmetrical in structure and are placed opposite to each other to form a longitudinal gas channel. A transverse gas channel is formed between the block and the lower pressure block (13), and the gas diffusion layer (14) to be measured is sandwiched in the transverse gas channel formed between the upper pressure block and the lower pressure block (13). (14) A detachable sealing ring (16) is provided on the outside, and the gas to be measured flows out through the flow controller (10), passes through the humidification system (9) and the temperature control system (11), and then reaches the clamping device.
The device for measuring the permeability and diffusion coefficient of a fuel cell gas diffusion layer according to claim 1, characterized in that the upper and lower surfaces of the gas diffusion layer (14) to be measured are provided with upper porous metal blocks (7) and The lower porous metal block (15), the upper porous metal block (7) is clamped in the upper pressing block, and the lower porous metal block (15) is clamped in the lower pressing block (13).
The device for measuring the permeability and diffusion coefficient of a gas diffusion layer of a fuel cell according to claim 2, characterized in that the upper porous metal block (7) and the lower porous metal block (15) are made of high rigidity and high air permeability. The metal material of the gas diffusion layer (14) to be tested includes titanium alloy or stainless steel; the upper porous metal block (7) and the lower porous metal block (15) are assembled with the upper pressure block and the lower pressure block (13) The dimensional accuracy and flatness are controlled within 0.001.
The device for measuring the permeability and diffusion coefficient of a gas diffusion layer of a fuel cell according to claim 1, wherein the upper pressure block is divided into an upper pressure block one (5) and an upper pressure block two (8). An O-ring (4) for sealing is provided between the first block (5) and the second upper pressing block (8).
The device for measuring the permeability and diffusion coefficient of a fuel cell gas diffusion layer according to claim 1, wherein the sealing ring (16) is a movable sealing ring, which can be freely assembled and disassembled, and the inner side of the sealing ring (16) is tightly By the gas diffusion layer (14) to be tested, the distance between the outer side and the edge of the upper and lower pressing blocks is not more than 1mm.
The device for measuring the permeability and diffusion coefficient of a gas diffusion layer of a fuel cell according to claim 1, wherein the temperature control system (11) is heated by electric heating or circulating water bath, and the temperature control system (11) Simultaneously control the gas temperature in the gas pipeline and the clamping device;

The upper pressure block and the lower pressure block (13) are respectively provided with positioning holes, the compression degree of the measured gas diffusion layer (14) is controlled by a spacer or a displacement sensor between the upper and lower pressure blocks, and the upper and lower pressure blocks pass through bolts or cylinders. Apply clamping force.
The device for measuring the permeability and diffusion coefficient of a gas diffusion layer of a fuel cell according to claim 1, wherein the state monitoring module comprises an oxygen concentration sensor (2), a temperature and humidity sensor (1) and a differential pressure sensor (3). );

Said oxygen concentration sensor (2), temperature and humidity sensor (1), differential pressure sensor (3), gas flow controller (10), temperature control system (11) and humidification system (9) are all connected to a signal receiving module. (6) Connected to record all experimental data in real time.
The fuel cell gas diffusion layer permeability and diffusion coefficient measuring device according to claim 7, wherein the oxygen concentration sensor (2) is installed in the lower pressing block (13), and the oxygen concentration sensor (2) The probe is closely attached to the gas diffusion layer (14) to be measured, the measurement range of the oxygen concentration sensor (2) is 0-100%, and the measurement accuracy is 0.01%;

The two probes of the differential pressure sensor (3) are respectively installed in the upper pressure block two (8) and the lower pressure block (13), so that they are connected to the upper and lower chambers, and the pressure measuring point is connected to the gas diffusion layer to be measured. The distance of (14) is less than 1mm, the measurement range of the differential pressure sensor (3) is 0-10kPa, and the measurement accuracy is 1Pa.
A method of using a gas diffusion layer permeability and diffusion coefficient measuring device for a fuel cell as claimed in claim 1, wherein the method comprises a method for measuring the permeability in the thickness direction of the gas diffusion layer, and a method for measuring the diffusion coefficient in the thickness direction of the gas diffusion layer. Method, measurement method of directional permeability in gas diffusion layer, measurement method of directional diffusion coefficient in gas diffusion layer.
The method for measuring the permeability and diffusion coefficient of a fuel cell gas diffusion layer according to claim 9, wherein the method for measuring the permeability in the thickness direction of the gas diffusion layer comprises the following steps:

(i) Clamping the gas diffusion layer (14) under test between the upper pressing block and the lower pressing block (13), applying pressure to the upper and lower pressing blocks, and controlling it to be in a state of a specified compression ratio;

(ii) The measured gas with the specified flow rate and temperature and humidity enters the clamping device through the gas port on the upper pressure block, and is discharged from the gas outlet of the lower pressure block (13) to the gas recovery through the measured gas diffusion layer (14). in the device;

(iii) By measuring the pressure difference of the measured gas passing through the gas diffusion layer, the permeability in the thickness direction of the gas diffusion layer is calculated according to the Darcy's law of porous materials;

The method for measuring the diffusion coefficient in the thickness direction of the gas diffusion layer comprises the following steps:

(i) Clamping the gas diffusion layer (14) under test between the upper pressing block and the lower pressing block (13), applying pressure to the upper and lower pressing blocks, and controlling it to be in a state of a specified compression ratio;

(ii) Nitrogen gas enters the clamping device through the gas port on the upper pressure block, and is discharged into the gas recovery device from the gas outlet of the lower pressure block (13) through the measured gas diffusion layer (14), and is purged with nitrogen gas for 5 minutes or more, until the clamping device and the measured gas diffusion layer (14) are all filled with nitrogen gas, the oxygen concentration sensor (2) shows that the oxygen concentration is 0, and the nitrogen gas is stopped;

(iii) Immediately plug the gas outlet of the lower pressure block (13), and remove the upper pressure block (5), so that the gas diffusion layer (14) to be measured is filled with air as soon as possible, and the oxygen concentration sensor (2) Record the diffusion process of oxygen in the air to the underside of the gas diffusion layer (14) under test;

(iv) By measuring the change curve of the oxygen concentration on the lower side of the measured gas diffusion layer (14), the diffusion coefficient in the thickness direction of the gas diffusion layer is calculated according to Fick's diffusion law;

The method for measuring the in-direction permeability of the gas diffusion layer comprises the following steps:

(i) Remove the sealing ring (16), the upper porous metal block (7) and the lower porous metal block (15), and plug the gas outlet of the lower pressing block (13);

(ii) Clamping the gas diffusion layer (14) to be tested between the upper and lower pressing blocks, and applying pressure to the upper and lower pressing blocks to control the gas diffusion layer (14) under the specified compression rate;

(iii) The measured gas with the specified flow rate and temperature and humidity enters the clamping device through the gas inlet of the upper pressure block, and is discharged from the surrounding to the gas recovery device through the measured gas diffusion layer (14);

(iv) By measuring the pressure difference of the measured gas passing through the gas diffusion layer, the permeability in the direction of the gas diffusion layer is calculated according to Darcy's law of porous materials;

The method for measuring the directional diffusion coefficient in the gas diffusion layer comprises the following steps:

(i) Remove the sealing ring (16), the upper porous metal block (7) and the lower porous metal block (15), and plug the gas outlet of the lower pressing block (13);

(ii) Clamping the gas diffusion layer (14) to be tested between the upper and lower pressing blocks, and applying pressure to the upper and lower pressing blocks to control the gas diffusion layer (14) under the specified compression rate;

(iii) The nitrogen gas enters the clamping device through the gas inlet of the upper pressure block, and is discharged into the gas recovery device from the surrounding through the gas diffusion layer (14) to be tested, and is purged with nitrogen for more than 5 minutes until the clamping device and the The gas diffusion layer (14) is all filled with nitrogen gas, the oxygen concentration sensor (2) shows that the oxygen concentration is 0, and the nitrogen gas is stopped;

(iv) The oxygen concentration sensor (2) records the process of oxygen in the air diffusing into the clamping device through the measured gas diffusion layer (14), and calculates according to Fick’s diffusion law by measuring the change curve of the oxygen concentration inside the clamping device The directional diffusion coefficient in the gas diffusion layer is obtained.