CN106887633B

CN106887633B - High-temperature fuel cell stack

Info

Publication number: CN106887633B
Application number: CN201510932806.9A
Authority: CN
Inventors: 孙公权; 孙雪敬; 杨林林; 孙海; 戚甫来
Original assignee: Dalian Institute of Chemical Physics of CAS
Current assignee: Dalian Institute of Chemical Physics of CAS
Priority date: 2015-12-15
Filing date: 2015-12-15
Publication date: 2020-01-14
Anticipated expiration: 2035-12-15
Also published as: CN106887633A

Abstract

A high-temperature fuel cell stack comprises two end plates and a single cell arranged between the two end plates, wherein the single cell comprises a bipolar plate and a membrane electrode, and a molecular sieve coating is coated on the inner side surface of the end plate close to the single cell and/or the two side surfaces of the bipolar plate. According to the design of the invention, the problem of battery performance reduction caused by water which cannot be discharged in time in the starting and stopping processes of the high-temperature proton exchange membrane fuel cell can be effectively solved. The stability of the battery in the operation process is improved, and the service life of the battery is prolonged. The problem of flooding caused by the fact that generated water cannot be timely removed in the operation process of the cell is solved, corrosion of materials such as a catalyst carrier, a noble metal catalyst, a diffusion layer and the like in the membrane electrode is reduced, and the stability of the membrane electrode is improved. The water removal method has a simple structure, and can effectively remove water without adding external facilities.

Description

High-temperature fuel cell stack

Technical Field

The invention relates to the technical field of fuel cells, in particular to a high-temperature fuel cell stack.

Background

A fuel cell is a device that directly converts chemical energy stored in a compound fuel into electrical energy through a chemical reaction. Proton exchange membrane fuel cells are typically comprised of an anode, a cathode, and a proton exchange membrane. During the operation of the cell, fuel is oxidized on the surface of the anode catalyst to generate protons and electrons, the protons reach the cathode through the proton exchange membrane, oxygen and the protons are reduced on the surface of the cathode catalyst to generate water, and the electrons do work through an external circuit to reach the cathode.

The high-temperature proton exchange membrane fuel cell has high operation temperature, and water is discharged into the atmosphere along with cathode tail gas in a gaseous state, but the temperature is low in the starting and stopping process of the cell, and liquid water is not enough to be vaporized, so that the water generated by the cell cannot be discharged in time, and the performance of the cell is reduced.

Disclosure of Invention

The invention aims to solve the problem of water flooding caused by difficulty in discharging water generated in the starting and stopping processes of a high-temperature proton exchange membrane fuel cell system, and provides an effective water removal method.

The invention is realized by adopting the following specific modes:

a high-temperature fuel cell stack comprises two end plates and a single cell arranged between the two end plates, wherein the single cell comprises a bipolar plate and a membrane electrode, and a molecular sieve coating is coated on the inner side surface of the end plate close to the single cell and/or the two side surfaces of the bipolar plate.

And a molecular sieve coating is coated on the inner surface of the cathode outlet pipeline of the electric pile.

And the surface of the inner side flow channel of the end plate close to the single battery and/or the surface of the flow channel on the two sides of the bipolar plate are/is coated with a molecular sieve coating.

The molecular sieve is a low-temperature water-absorbing and high-temperature dehydrating material.

The molecular sieve is one or a mixture of more than two of 3A, 4A, 5A, 10X and 13X.

The molecular sieve coating is a molecular sieve membrane.

The thickness of the molecular sieve coating is 0.001-10 mm.

According to the design of the invention, the problem of battery performance reduction caused by water which cannot be discharged in time in the starting and stopping processes of the high-temperature proton exchange membrane fuel cell can be effectively solved. The stability of the battery in the operation process is improved, and the service life of the battery is prolonged. The problem of flooding caused by the fact that generated water cannot be timely removed in the operation process of the cell is solved, corrosion of materials such as a catalyst carrier, a noble metal catalyst, a diffusion layer and the like in the membrane electrode is reduced, and the stability of the membrane electrode is improved. The water removal method has a simple structure, and can effectively remove water without adding external facilities.

Drawings

FIG. 1 is a flow channel distribution and a molecular sieve coating distribution of a bipolar plate;

1. an end plate; 2. coating a molecular sieve; 3. an anode catalyst layer; 4. a proton exchange membrane; 5. a cathode catalyst layer; 6. bipolar plate

FIG. 2 is a high temperature fuel cell stack assembly;

figure 3 is a diagram of a membrane electrode assembly MEA.

Detailed Description

The following describes a specific embodiment of the present invention with reference to the drawings and the like.

The specific implementation mode comprises the following steps:

an end plate 1 for fluid distribution and collection; the molecular sieve coating 2 is used for removing water in the process of starting and stopping the battery; an anode catalyst layer 3 that catalyzes an oxidation reaction of the fuel; the proton exchange membrane 4 is used for transferring protons and isolating cathode and anode reactants; a cathode catalyst layer 5 that catalyzes a reduction reaction of oxygen; bipolar plate 6, fluid distribution of the cathode and anode reactants. The working principle is as follows:

the molecular sieve coating 2 is coated on the flow channels of the end plate 1 and the bipolar plate 6, the anode catalyst layer 3, the proton exchange membrane 4 and the cathode catalyst layer 5 jointly form a membrane electrode assembly MEA, and the MEA is assembled between the end plate and the bipolar plate as well as between the end plate and the bipolar plate.

The implementation method coats the molecular sieve in the flow channel of the end plate and the bipolar plate and coats the molecular sieve at the tail discharge port of the battery so as to fulfill the aim of removing water in the starting and stopping process. The molecular sieve must have the following functions: the adsorbent has the function of adsorbing water at a low temperature (lower than 120 ℃), and can desorb water adsorbed at a low temperature at a high temperature (higher than 150 ℃).

In the starting and stopping process of the high-temperature fuel cell stack, because the temperature is low, water generated by cell discharge can not be timely discharged in a gaseous state and is retained in the cell, so that the high-temperature fuel cell stack is flooded, and the performance of the high-temperature fuel cell stack is attenuated. If the flow channel is coated with the molecular sieve coating with water absorption performance, water generated in the discharging process is absorbed inside the molecular sieve through the water absorption molecular sieve coated on the flow channel, and the flooding phenomenon can be effectively avoided. When the high temperature fuel cell stack is operated to a normal operating temperature, water generated at this time is discharged in a gaseous form together with the off-gas. Because the normal operation temperature of the high-temperature fuel cell stack is higher, the molecular sieve can desorb the water adsorbed at low temperature, and the water is changed into gaseous water which is discharged along with tail gas.

The first implementation mode comprises the following steps: in the embodiment, 20 single cells are arranged between two end plates to form a high-temperature fuel cell stack, the inner side surfaces of the end plates close to the single cells and the two side surfaces of the bipolar plates are coated with 3A molecular sieve coatings, and the thickness of the molecular sieve membrane is 0.005 mm.

The high-temperature fuel cell stack assembled in this way has no obvious reduction of cell performance after being continuously started and stopped for 100 times, and the high-temperature fuel cell stack coated with the molecular sieve membrane has obvious reduction of cell performance caused by water logging after being started and stopped for 73 times under the same conditions as the high-temperature fuel cell stack. Through the comparison of the two modes, the mode can effectively improve the water flooding phenomenon caused by the start-stop process of the high-temperature fuel cell stack.

The second embodiment: in the embodiment, 20 single cells are arranged between two end plates to form a high-temperature fuel cell stack, the inner side surfaces of the end plates close to the single cells and the two side surfaces of the bipolar plates are coated with 5A molecular sieve coatings, and the thickness of the molecular sieve membrane is 0.01 mm.

The fuel cell dehumidification system can effectively adsorb water generated in the cell at the start-stop stage of the high-temperature fuel cell stack, and avoids the occurrence of a flooding phenomenon. When the temperature of the high-temperature fuel cell stack is higher, water adsorbed in the molecular sieve can be desorbed, so that the recycling of the molecular sieve is ensured, and the method for coating the molecular sieve in the flow channel is realized. The system is also coated with the molecular sieve at the tail discharge of the cell, and the main function of the system is to ensure the drying of the cell in a non-operation state. Since the air in different seasons has different humidity, the tail outlet of the high-temperature fuel cell stack is always communicated with the atmosphere when the high-temperature fuel cell stack is in a non-operation state, which also means that water in the air can enter the cell along with the air, and can cause corrosion of some devices in the cell when the water is serious. The water absorption molecular sieve is placed at the tail discharge port, so that water contained in air is mainly absorbed, and the water in the air is prevented from entering the battery and corroding the battery.

Claims

1. A high-temperature proton exchange membrane fuel cell stack comprises two end plates and a single cell arranged between the two end plates, wherein the single cell comprises more than 2 membrane electrode MEA (membrane electrode assembly) separated by bipolar plates, and the high-temperature proton exchange membrane fuel cell stack is characterized in that: the end plate is coated with a molecular sieve coating on the inner side flow passage surface close to the single battery, the flow passage surfaces on two sides of the bipolar plate and the inner surface of the cathode outlet pipeline of the electric pile;

the molecular sieve is a material that absorbs water at low temperatures below 120 ℃ and dehydrates at high temperatures above 150 ℃.

2. A high temperature pem fuel cell stack according to claim 1 wherein: the molecular sieve is one or a mixture of more than two of 3A, 4A, 5A, 10X and 13X.

3. A high temperature pem fuel cell stack according to claim 1 wherein: the molecular sieve coating is a molecular sieve membrane.

4. A high temperature pem fuel cell stack according to claim 1 wherein: the thickness of the molecular sieve coating is 0.001-10 mm.