CN110649279A

CN110649279A - Proton exchange membrane electrode, fuel cell, stack and method for manufacturing the same

Info

Publication number: CN110649279A
Application number: CN201911071209.6A
Authority: CN
Inventors: 陶霖密
Original assignee: Individual
Current assignee: Individual
Priority date: 2019-11-05
Filing date: 2019-11-05
Publication date: 2020-01-03
Anticipated expiration: 2039-11-05
Also published as: CN110649279B

Abstract

Proton exchange membrane electrode, fuel cell, stack, and cell fabrication method. The fuel cell comprises a hydrogen flow field plate, an oxygen flow field plate and a proton exchange membrane electrode between the hydrogen flow field plate and the oxygen flow field plate, wherein the proton exchange membrane electrode comprises: the device comprises a first diffusion layer, a first catalyst layer, a proton exchange membrane, a second catalyst layer, a second diffusion layer and two electric and heat conduction film layers, wherein the first diffusion layer, the first catalyst layer, the proton exchange membrane, the second catalyst layer and the second diffusion layer are sequentially stacked, and the two electric and heat conduction film layers are respectively positioned on the outer sides of the two diffusion layers and used for leading out current generated by electrochemical reaction without bypassing hydrogen and oxygen flow field plates. The reactor can diffuse reaction current and reaction heat to the periphery of the reactor from the middle of the reactor, wherein the current is conducted to the two ends of the reactor through an external circuit of the reactor, and the reaction heat can be dissipated through air or liquid around the reactor, so that a flow field plate inside the reactor does not need to have a conductive function, the temperature inside the fuel cell stack is maintained, the normal operation of the stack is ensured, and the stack with high power, stable performance and high power-weight ratio can be realized.

Description

Proton exchange membrane electrode, fuel cell, stack and method for manufacturing the same

Technical Field

The present invention relates generally to fuel cells, and more particularly to a device for generating electrical energy by reacting fuel gas (such as hydrogen gas, methane gas, ethanol gas, etc.) with air, which can be used as power generation equipment, power supply devices for various vehicles, various devices, etc., to the use of graphene-based high thermal conductivity materials in the field of new energy, and to a method for designing and manufacturing a device for generating energy by chemical reaction of fuel gas and air.

Background

A hydrogen fuel cell stack is a device for converting chemical energy of hydrogen-oxygen reaction into electric energy, and generally comprises a cathode flow field plate, an anode flow field plate, and a membrane electrode therebetween. The membrane electrode comprises a diffusion layer, a catalyst layer, a proton membrane and the like. The membrane electrode converts chemical energy of the hydrogen-oxygen reaction into electric energy and heat energy, and assuming that the efficiency of converting chemical energy of the hydrogen-oxygen reaction into electric energy is 50%, 50% of the chemical energy is converted into heat energy. Therefore, heat dissipation is one of the important issues that must be addressed for stable operation of the pem fuel cell stack.

At present, proton exchange membrane fuel cell stacks are mainly divided into two types according to the heat dissipation mode: gas cooled reactors and water cooled reactors. The gas-cooled reactor has simple structure but low gas-cooled efficiency, and is mainly used for cooling the small-sized and experimental proton exchange membrane fuel cell stack. Since dry air easily blows the proton membrane to reduce the operation efficiency of the electric pile, the utilization efficiency of the air cooled reactor is limited, and the air cooled reactor is generally used for demonstrating the electric pile. The water-cooling or liquid-cooling pile has a complex structure and a good heat dissipation effect, reduces the air flow in the pile, and enables the pile to stably run in a dry air environment by humidifying the air entering the pile. However, the water-cooled reactor has a complex structure, and the water-cooled channel occupies 30-50% of the reactor, so that the reaction area of the reactor is reduced, the proton membrane and the catalyst thereof cannot be effectively utilized, and finally the price of the reactor is high. At present, the liquid cooling mode is generally adopted by the automobile stacks.

FIGS. 10-13 are schematic diagrams illustrating the structure of a conventional air-cooled PEM fuel cell stack. With the cathode flow field shown at 31 in fig. 10, the hydrogen flow channels shown at 32, and the anode flow field shown at 33 in fig. 11. Figure 12 shows a five-layer membrane electrode sandwiched between two flow field plates, comprising an intermediate proton exchange membrane 34, a catalyst 35 in both membrane sides, and a further outer diffusion layer 36. Figure 13 shows a pem fuel cell stack formed by stacking a plurality of flow field plates and membrane electrodes, and the resulting current 9 of the stack.

In general, the flow field plate is horizontally arranged, the cathode flow field is horizontal, gas flows from left to right or from right to left, and water generated by hydrogen-oxygen reaction flows out from one end or two ends of the flow field plate. In the hydrogen-oxygen reaction, the hydrogen releases electrons under the action of a catalyst, the electrons pass through the flow field plate and are captured by oxygen, and the protons pass through the proton exchange membrane and are combined with the oxygen on the other side to capture the electrons released by the hydrogen under the action of the catalyst. The movement of electrons and protons creates an electric current that is output from both ends of the stack through the flow field plates (fig. 13). At present, graphite is generally used as the material of the flow field plate. On the one hand, graphite has many advantages of corrosion resistance, high electrical conductivity, no leakage, easy manufacturing, etc. On the other hand, the graphite flow field plate has poor thermal conductivity, and the reaction heat of hydrogen and oxygen is difficult to diffuse in time, so that the electric pile is difficult to be enlarged. Thus, graphite gas cooled electric reactors are mostly low power electric reactors within thousands of watts.

In the air direct-cooling reactor, oxygen required by hydrogen-oxygen reaction and air required by cooling are both derived from air flow passing through a flow field plate of the reactor, and the humidity of a proton membrane and the temperature of the electric pile can be conveniently controlled by adjusting the size of cathode air flow so as to maintain stable power generation of the electric pile. The advantages of the design are simple structure of the pile system, small volume, light weight and low cost. Accordingly, the drawbacks of this design are also quite clear, firstly because the efficiency of air heat dissipation is limited, the flow field plates cannot be made too large, thus limiting the total power of the stack; secondly, in areas with dry air, such as deserts and winter low-temperature drying, too much water vapor is taken away by the heat dissipation air, so that the proton membrane is dry to influence power generation; finally, a large amount of heat dissipation air enters the galvanic pile and brings in a large amount of air pollutants, so that various problems such as blockage of a diffusion layer, poisoning of a catalyst and the like are caused, and the service life of the galvanic pile is greatly shortened. Therefore, the air direct-cooled stack is advantageous in terms of a low-cost low-power stack, and is significantly disadvantageous in terms of a high-power commercial stack.

The above situation is essentially a common problem faced by proton membrane hydrogen stacks, namely that the flow field plates have to assume three functions within the stack: firstly, a gas flow field requires that the flow field plate is compact enough and cannot leak, otherwise, hydrogen and oxygen are directly mixed, which easily causes danger; the second is a heat dissipation flow field, which requires the gas or liquid passing through the flow field plate to dissipate heat of the electric pile; and thirdly, the flow field plate is conductive, the flow field plate is required to be a good electric conductor, and current generated by hydrogen-oxygen reaction passes through the flow field plate and reaches two ends of the galvanic pile. In addition, the flow field plate is also resistant to acid corrosion, and hydrogen ions generated by a hydrogen pile during reaction have strong acidity and can generate strong acid corrosion and hydrogen corrosion on the metal flow field plate. Furthermore, metal ions generated during acid etching are toxic to the catalyst in the proton exchange membrane. Therefore, the material of the flow field plate which meets all the requirements and is suitable in price only has high-purity graphite at present. But also has the problems of low heat dissipation efficiency, high manufacturing cost and the like. On the contrary, the metal flow field plate has the advantages of low manufacturing cost and high heat dissipation efficiency due to the heat dissipation liquid contained therein, but is not resistant to acid corrosion, hydrogen corrosion and poor in conductivity.

Research on proton membrane stacks has been very hot in recent years, mainly aiming at solving the problem of heat dissipation and at the same time finding better materials for bipolar plates. The current representative direction is a metal water-cooled reactor, and the main idea is to add closed liquid cooling pipelines in a cathode flow field and an anode flow field, so that the reaction heat of the reactor can be carried to the outside of the reactor through cooling liquid. The metal plate stack can theoretically be completely independent of air cooling, and can be used for manufacturing a hydrogen-oxygen stack. There are three main problems with metal plate stacks: firstly, as mentioned above, the liquid cooling pipes occupy a large amount of space inside the reactor, which results in a decrease in the utilization rate of the proton membrane and the catalyst in the reactor and an increase in the cost of the reactor; secondly, the conductivity of general metal is not good, which hinders the movement of electrons during the hydrogen-oxygen reaction, and the metal plate can generate heat due to the strong current generated during the operation of the high-power galvanic pile; and thirdly, proton current is generated when the galvanic pile runs, the proton current is strong in acidity and has a corrosion effect on metal, the metal is subjected to hydrogen embrittlement under the action of current and hydrogen to reduce the strength, and metal ions are generated at the same time and have toxicity on the metal in the catalyst. The metal or alloy satisfying the conditions of high strength, high conductivity, corrosion resistance, etc. is generally a noble metal or noble metal alloy, etc. This greatly increases the manufacturing cost of the stack.

There are many patents on proton exchange membrane fuel cell stacks at home and abroad, and 12 related patents in the last decade are preferred in the present application as follows. It can be seen from these patents that the early fuel cells were low power air cooled cell systems, and through years of improvement, the fuel cells gradually changed from air cooled low power to metal bipolar plate water cooled high power electric stacks.

【1】 CN 03120950, Small Power air cooled Fuel cell System, Atai Fuel cell technologies, Inc., 2003-03-24;

【2】 CN 200620069309, air-cooled fuel cell stack, Nanjing Boneng Fuel cell, Inc., 2006-02-15;

【3】 CN 200710007706, cooling plate with improved flow channel, samsung Sdi ltd, 2007-01-29;

【4】 CN 200710172148, proton exchange membrane fuel cell bipolar plate formed by metal sheet, shanghai university of transportation, 2007-12-13;

【5】 CN 200880010515, fuel cell system and power control method, toyota automotive, 2008-04-18;

【6】 CN 201010288866, metal bipolar plates of proton exchange membrane fuel cells and single cells and galvanic piles formed by the metal bipolar plates, Wuhan university of engineering, 2010-09-21;

【7】 CN 201010543786, air-cooled proton exchange membrane fuel cell bipolar plate, Wuxi national win science and technology Limited, 2010-11-15;

【8】 CN 201420388910, hydrogen power supply based on metal bipolar plate, electricity material of ice city, jiangsu, 2014-07-14;

【9】 CN 201420213337, a bipolar plate for enhancing the heat dissipation of a fuel cell stack, 2014-04-29, Nanjing Bidaofu technical development research institute Limited;

【10】 CN 201410543495, water-cooled proton exchange membrane fuel cell stack and water-cooled proton exchange membrane fuel cell, Beijing hydrogen jade energy creation technology ltd, 2014-10-15;

【11】 CN 201310087948, a high thermal conductivity thin graphene-based composite material, a preparation method and application thereof, 2013-03-19, Grey Feng, Suzhou;

【12】 CN 201310172499, a preparation method of a high-thermal-conductivity natural graphite radiating fin, Shenzhen, same-Antai electronics science and technology Limited, 2013-05-1.

In summary, the current fuel cell mainly has two construction modes: gas-cooled galvanic stacks based on graphite bipolar plates, and water-cooled galvanic stacks based on metallic bipolar plates. The graphite bipolar plate has the characteristics of stable performance, good conductivity, no corrosion and no metal ion pollution, but low air cooling and heat dissipation efficiency, and can not manufacture a hydrogen-oxygen battery stack; the metal bipolar plate has the characteristics of high water-cooling heat dissipation efficiency, poor conductivity of common metals, easy corrosion, easy hydrogen embrittlement and the like. The fundamental reason for these problems is that the flow field plate integrates various functions such as gas flow field, electric conduction, heat dissipation, acid corrosion resistance and the like in the stack, so that the flow field plate which fully meets these requirements is high in price and difficult to manufacture, and is difficult to popularize and apply in a large-scale commercial manner.

Disclosure of Invention

The invention aims to solve the comprehensive problems of flow field, electric conduction and heat dissipation of the flow field plate in the fuel electric pile.

One embodiment of the present invention inventively manufactures a high electrical and thermal conductivity proton exchange membrane electrode (for example, by using a new high electrical and thermal conductivity thin layer material, etc.) for conducting the current and reaction heat generated by the hydrogen-oxygen reaction from the inside of the reactor to the periphery of the reactor, i.e., bypassing the electrical and thermal conductivity solid proton exchange membrane battery stack. The current generated by the hydrogen-oxygen reaction is firstly conducted to the outside of the reactor through the high-conductivity heat-conducting film on the proton exchange membrane electrode, then flows to the two ends of the reactor through the bypass circuit outside the reactor, and outputs electric energy to the outside. The reaction heat is conducted in a solid state in the reactor, namely conducted to the outside of the reactor through a high-conductivity heat-conducting film on the proton exchange membrane electrode, and then radiated by air or liquid around the reactor. Therefore, the embodiment of the present invention provides an off-stack bypass electric-conduction solid-state heat-conduction pem fuel cell stack, which has at least two creative contributions: (1) a solid state heat conductive proton exchange membrane fuel cell stack. Compared with the existing fuel cell stack based on the heat dissipation mode of gaseous and liquid heat conduction materials, the fuel cell stack disclosed by the embodiment of the invention adopts the solid high-heat-conduction film to conduct the reaction heat of the fuel cell from the inside of the stack to the periphery of the stack, so that the fuel cell stack has higher heat dissipation efficiency and more compact structure. (2) The outside of the stack bypasses the current proton exchange membrane fuel cell stack. Compared with the internal conduction mode that the current of the existing fuel cell stack passes through the flow field plate to reach the two ends of the stack, the embodiment of the invention adopts the bypass current mode that the high-conductivity film conducts the current generated by the reaction of the fuel cell to the periphery of the stack from the inside of the stack and then to the two ends of the stack, so that the flow field plate does not need to have the function of conduction, and the material and the manufacturing cost of the flow field plate are greatly reduced.

The embodiment of the invention revolutionarily provides a method and an implementation scheme for separating three functions of gas flow field, electric conduction and heat dissipation of a flow field plate, so that the gas flow field does not need to have the three functions of gas flow field, electric conduction and heat dissipation at the same time, and the method comprises the following steps: (1) a non-conductive flow field plate with heat dissipation capability, (2) a flow field plate with conductive but non-heat dissipation capability, and (3) a non-conductive, non-heat dissipating flow field plate. Therefore, this embodiment of the present invention will greatly facilitate the development of flow field plate materials and manufacturing processes, and ultimately the commercialization of hydrogen stacks.

The invention also provides a technical scheme for coating the conductive coating on the surface of the flow field plate and leading out the current by-pass.

The invention also provides a technical scheme for manufacturing the diffusion layer by using the conductive material and leading out the current bypass.

According to one aspect of the present invention, a proton exchange membrane fuel cell is provided, which includes a hydrogen flow field plate, an oxygen flow field plate, and a proton exchange membrane electrode therebetween, wherein the proton exchange membrane electrode includes: the proton exchange membrane electrode comprises a first diffusion layer, a first catalyst layer, a proton exchange membrane, a second catalyst layer and a second diffusion layer which are sequentially stacked, and is characterized by further comprising a first electric conduction and heat conduction thin film layer and a second electric conduction and heat conduction thin film layer which are respectively positioned on the outer sides of the first diffusion layer and the second diffusion layer, wherein the first electric conduction and heat conduction thin film layer and the second electric conduction and heat conduction thin film layer are used for leading out current generated by electrochemical reaction without bypassing a flow field plate.

Optionally, the first electrically and thermally conductive thin film layer and the second electrically and thermally conductive thin film layer are further configured to bypass and conduct away heat generated by the electrochemical reaction.

Optionally, each of the first and second electrically and thermally conductive thin film layers includes: bypass electricity and heat conduction radiating part, hydrogen passageway, electrically conductive heat conduction film net, bypass electric circuit, electrically conductive heat conduction radiating part connect electrically conductive heat conduction film net and bypass electric circuit, and the electric current flows to bypass electric circuit and draws forth the outside in the oxyhydrogen reaction zone of galvanic pile from electrically conductive electric heat film net through bypass electricity and heat conduction radiating part, forms series circuit, improves the voltage of galvanic pile.

Optionally, the bypass conductive heat dissipation part is located outside the hydrogen-oxygen reaction region, has a conductive function, and communicates with the positive electrode and the negative electrode of the flow field plate, so that current generated by the hydrogen-oxygen reaction in the membrane electrode does not pass through the flow field plate and is led out to two ends of the stack.

Optionally, the bypass conductive heat sink dissipates heat through air or liquid.

Optionally, the flow field plate is made of a non-conductive material.

Optionally, the flow field plate is made of a non-heat dissipating material.

Optionally, the flow field plates are made of a non-conductive and non-heat dissipating material.

Alternatively, the flow field plates are not used as electrodes.

Optionally, the pem fuel cell further comprises: and air or oxygen required by the hydrogen-oxygen reaction passes through the hydrogen flow field plate and the oxygen flow field plate through the filtering and humidifying device and enters the reactor.

Optionally, the flow field plate is made of one of resin, ceramic and plastic.

Optionally, the bypass circuit is made of non-noble metal.

Optionally, the electrically and thermally conductive film mesh is made of a graphene composite film or a highly thermally conductive graphite film.

According to another aspect of the present invention, there is provided a proton exchange membrane fuel cell stack formed by stacking the proton exchange membrane cells, wherein the current generated by the hydrogen-oxygen reaction is firstly conducted to the outside of the reaction area of the stack through the network of electrically and thermally conductive membranes on the proton exchange membrane electrode, and then flows to the two ends of the stack through the bypass conductive circuit outside the stack.

Optionally, adjacent bypass conductive circuits in two adjacent pem fuel cells in the pem fuel cell stack are connected, so that the pem stacked with the flow field plate forms a series structure through the bypass circuits, wherein current does not flow through the flow field plate.

According to still another aspect of the present invention, there is provided a proton exchange membrane electrode comprising: the proton exchange membrane electrode comprises a first diffusion layer, a first catalyst layer, a proton exchange membrane, a second catalyst layer and a second diffusion layer which are sequentially stacked, and is characterized by further comprising a first electric conduction and heat conduction thin film layer and a second electric conduction and heat conduction thin film layer which are respectively positioned on the outer sides of the first diffusion layer and the second diffusion layer, wherein the first electric conduction and heat conduction thin film layer and the second electric conduction and heat conduction thin film layer are used for leading out current generated by electrochemical reaction without bypassing a flow field plate.

According to another aspect of the present invention, there is provided a method for manufacturing the proton exchange membrane fuel cell, including: sequentially stacking a first diffusion layer, a first catalyst layer, a proton exchange membrane, a second catalyst layer and a second diffusion layer; characterized in that the method also comprises: and a first electric conduction and heat conduction film layer and a second electric conduction and heat conduction film layer are arranged on the outer sides of the first diffusion layer and the second diffusion layer and used for bypassing and leading out the current generated by the electrochemical reaction without passing through a flow field plate.

Implementations of embodiments of the invention may have at least one or more of the following advantages:

(1) aiming at the problems of electric conduction and heat dissipation commonly existing in the operation of a proton exchange membrane fuel cell stack, reaction current and reaction heat are diffused to the periphery of the reactor from the middle of the reactor by utilizing an electric-conduction and heat-conduction film, preferably a high-electric-conduction and heat-conduction film material, wherein the current is conducted to two ends of the reactor through an external circuit of the reactor, and the reaction heat can be dissipated through air or liquid around the reactor, so that the temperature inside the fuel cell stack is maintained, and the normal operation of the stack is guaranteed. Therefore, in the present invention, unlike the conventional art, the medium for conducting the hydrogen-oxygen reaction current and heat from the inside of the stack to the outside of the stack is not a gaseous substance such as air, carbon dioxide, etc., nor a liquid substance such as water, etc., but a solid substance, a highly electrically and thermally conductive thin film material.

(2) A third cooling mode of the proton exchange membrane fuel cell stack is created: a solid heat-conducting proton exchange membrane fuel cell stack. Meanwhile, the embodiment of the invention also creates a brand new current conduction mode of the proton exchange membrane fuel cell stack: the outside of the stack bypasses the current proton exchange membrane fuel cell stack.

(3) Due to the excellent performances of solid heat conduction and bypass electric conduction, the proton exchange membrane fuel cell stack disclosed by the embodiment of the invention has the characteristics of high power, stable performance, high power-weight ratio and the like; can conveniently realize hydrogen-air and hydrogen-oxygen proton exchange membrane fuel cell stacks, methane-gas and oxygen fuel cell stacks and the like.

The invention relates to a high electric and heat conduction proton exchange membrane, a battery and a galvanic pile, which are basic inventions in the field and can be applied to all proton exchange membrane battery galvanic pile devices. Breaks through the patent barriers of foreign manufacturers and opens up a wide prospect for the development of independent green clean energy in China.

According to another aspect of the present invention, there is provided a proton exchange membrane fuel cell comprising a hydrogen flow field plate composite system, an oxygen flow field plate composite system and a proton exchange membrane electrode therebetween, the proton exchange membrane electrode comprising: the hydrogen flow field plate composite system and the oxygen flow field plate composite system respectively comprise a flow field plate, a conductive coating part coated on the surface of the flow field plate and a bypass conductive joint, wherein the flow field plate is made of conductive or non-conductive materials; the conductive plating film part is a plating layer made of a conductive material and used for diffusing current generated by hydrogen-oxygen reaction to the surface of the whole plating layer; the bypass conductive connector is connected with the conductive coating part, crosses two poles of the flow field plate system, and connects the positive pole and the negative pole of the flow field plate system together to form a bypass conductive circuit outside the flow field plate, and the bypass conductive circuit is used for leading out current generated by electrochemical reaction without bypassing the flow field plate.

Optionally, the hydrogen flow field plate composite system further comprises a gas sealing ring positioned at the edge of the hydrogen flow field plate, and the gas sealing ring is used for blocking a path for gas to diffuse out of the sealing ring and preventing gas leakage; under the condition that the air inlet of the oxygen flow field plate composite system is an oxygen source instead of air, the oxygen flow field plate composite system also comprises an air sealing ring positioned at the edge of the oxygen flow field plate, and the air sealing ring is used for blocking the path of gas diffusing to the outside of the sealing ring and preventing the gas from leaking.

Optionally, the flow field plate is made of a non-conductive material.

Optionally, the flow field plate is made of ceramic or plastic.

Optionally, the flow field plate is made of stainless steel.

Optionally, the conductive coating part is made of a metal coating, a graphite deposition layer or graphene.

Optionally, the bypass conductive contact is made of conductive metal or graphene.

According to another aspect of the present invention, a proton exchange membrane fuel cell stack is provided, which is formed by stacking the proton exchange membrane cells.

According to another aspect of the present invention, there is provided a flow field plate composite system for use in a proton exchange membrane fuel cell, the flow field plate composite system each comprising a flow field plate, a conductive coated portion coated on a surface of the flow field plate, and a bypass conductive joint, wherein the flow field plate is made of a conductive or non-conductive material; the conductive plating film part is a plating layer made of a conductive material and used for diffusing current generated by hydrogen-oxygen reaction to the surface of the whole plating layer; the bypass conductive connector is connected with the conductive coating part, crosses two poles of the flow field plate system, and connects the positive and negative poles of different flow field plate systems together to form a bypass conductive circuit outside the flow field plate, and the bypass conductive circuit is used for leading out current generated by electrochemical reaction without bypassing the flow field plate.

According to another aspect of the present invention, there is provided a method for manufacturing the proton exchange membrane fuel cell, including: sequentially stacking a first diffusion layer, a first catalyst layer, a proton exchange membrane, a second catalyst layer and a second diffusion layer to form a proton exchange membrane electrode; coating conductive coating parts on the surfaces of the hydrogen flow field plate and the oxygen flow field plate, and connecting the conductive coating parts with the bypass conductive connector to obtain a hydrogen flow field plate composite system and an oxygen flow field plate composite system; sequentially stacking a hydrogen flow field plate composite system, a proton exchange membrane electrode and an oxygen flow field plate composite system; and arranging a bypass conductive connector to be connected with the conductive coating part, crossing the two poles of the flow field plate system, and connecting the positive pole and the negative pole of the flow field plate system together to form a bypass conductive circuit outside the flow field plate, wherein the bypass conductive circuit is used for leading out current generated by electrochemical reaction without bypassing the flow field plate.

The inventive contribution of the embodiment of the invention is as follows: a bypass current proton exchange membrane fuel cell stack. Compared with the internal conduction mode that the current of the existing fuel cell stack passes through the flow field plate/bipolar plate to reach the two ends of the stack, the embodiment of the invention adopts the bypass current mode that the flow field plate composite system containing the conductive coating conducts the current generated by the reaction of the fuel cell from the inside of the stack to the periphery of the stack and then to the two ends of the stack, so that the bipolar plate does not need to have the function of conduction and becomes the flow field plate only with oxyhydrogen gas diversion, thereby greatly reducing the material and manufacturing cost of the flow field plate.

The embodiment of the invention revolutionarily provides a method and an implementation scheme for separating the gas flow field and the electric conduction of the flow field plate, so that the flow field plate does not need to have the two functions of the gas flow field and the electric conduction at the same time. Therefore, the embodiment of the invention can change the high-demand bipolar plate with the functions of gas flow field, electric conduction and heat conduction into a flow field plate composite system which is easy to manufacture: the flow field plates, the conductive plated portions, and the conductive tab portions will greatly facilitate the development of flow field plate materials and manufacturing processes, and ultimately the commercial development of hydrogen stacks.

According to another aspect of the present invention, there is provided a proton exchange membrane fuel cell comprising a hydrogen flow field plate, an oxygen flow field plate, and a proton exchange membrane electrode therebetween, the proton exchange membrane electrode comprising: the first diffusion layer, the first catalyst layer, the proton exchange membrane, the second catalyst layer and the second diffusion layer are sequentially stacked, wherein the first diffusion layer and the second diffusion layer have oxyhydrogen gas diffusion, electric conductivity and bypass electric conduction functions, extend outwards and are connected with a bypass electric conduction joint to form a bypass electric conduction circuit outside the flow field plate, a sealing ring is formed around the diffusion layers to prevent gas from diffusing to the outside of a oxyhydrogen reaction area of the battery, but the diffusion layers extend to the outside of the oxyhydrogen reaction area to form a bypass electric conduction area, and electric energy is conducted to the outside of the oxyhydrogen reaction area through the bypass electric conduction area.

Optionally, an insulating portion is formed between the bypass conductive portion of the first diffusion layer and the bypass conductive portion of the second diffusion layer.

Optionally, the hydrogen flow field plate and the oxygen flow field plate are made of non-conductive materials.

Optionally, the hydrogen flow field plates and oxygen flow field plates do not serve as electrodes.

Optionally, the proton exchange membrane fuel cell further comprises a filtering and humidifying device, and air or oxygen required by the hydrogen-oxygen reaction passes through the hydrogen flow field plate and the oxygen flow field plate after passing through the filtering and humidifying device, and enters the reactor.

Optionally, the hydrogen flow field plate and the oxygen flow field plate are made of one of resin, ceramic and plastic.

According to another aspect of the present invention, there is provided a proton exchange membrane fuel cell stack formed by the proton exchange membrane cells connected in series.

According to another aspect of the present invention, there is provided a method of manufacturing a proton exchange membrane fuel cell, including: manufacturing a first diffusion layer and a second diffusion layer by using conductive materials; sequentially stacking a first diffusion layer, a first catalyst layer, a proton exchange membrane, a second catalyst layer and a second diffusion layer to form a proton exchange membrane electrode; the first diffusion layer and the second diffusion layer have oxyhydrogen gas diffusion, conductivity and bypass conductivity, extend outwards and are connected with a bypass conductive joint to form a bypass conductive circuit outside the flow field plate, and a sealing ring is arranged around the diffusion layers to prevent gas from diffusing to the outside of the battery, but the diffusion layers extend to the outside of an oxyhydrogen gas reaction region to form a bypass conductive region, and electric energy is conducted to the outside of the oxyhydrogen reaction region through the bypass conductive region; and a hydrogen flow field plate, a proton exchange membrane electrode and an oxygen flow field plate are sequentially superposed.

The inventive contribution of the embodiment of the invention is as follows: a bypass current proton exchange membrane fuel cell stack. Compared with the internal conduction mode that the current of the existing fuel cell stack passes through the flow field plate/bipolar plate to reach the two ends of the stack, the embodiment of the invention adopts the extended diffusion layer and the bypass conductive joint to conduct the current generated by the reaction of the fuel cell to the periphery of the stack from the inside of the stack and then to the two ends of the stack, so that the bipolar plate does not need to have the function of conduction and becomes the flow field plate only with oxyhydrogen gas diversion, thereby greatly reducing the material and manufacturing cost of the flow field plate.

The embodiment of the invention revolutionarily provides a method and an implementation scheme for separating the gas flow field and the electric conduction of the flow field plate, so that the flow field plate does not need to have the two functions of the gas flow field and the electric conduction at the same time. Therefore, the embodiment of the invention can change the traditional high-demand bipolar plate with the functions of gas flow field, electric conduction and heat conduction into the flow field plate which is easy to manufacture, and can greatly promote the development of the material and the manufacturing process of the flow field plate, thereby finally promoting the commercial development of the hydrogen electric pile.

Drawings

FIG. 1 shows a side view of a seven-layer proton exchange membrane electrode assembly in accordance with an embodiment of the present invention;

FIG. 2 more clearly illustrates the structure of a highly electrically and thermally conductive film according to one embodiment of the present invention;

fig. 3(a) and 3(b) show another structure of a high electric and thermal conductive film in a seven-layer proton exchange membrane electrode according to an embodiment of the present invention;

fig. 4 shows a structural composition example of a unit fuel cell 200 according to an embodiment of the invention;

FIG. 5 is a schematic diagram of the structure of a high electrical and thermal conductivity PEM fuel cell stack 300 according to an embodiment of the invention;

fig. 6 and 7 show a high thermal conductivity pem fuel cell stack and its liquid heat sink, wherein fig. 6 shows a hydrogen flow field view and fig. 7 shows an oxygen flow field view.

Fig. 8 is a schematic diagram illustrating a construction of a stack of a bypass conductive pem fuel cell and a bypass circuit device thereof according to an embodiment of the present invention.

Fig. 9 is a schematic diagram showing a structure of a high electric and thermal conductivity pem fuel cell stack and a bypass electric and liquid heat dissipation device thereof.

FIGS. 10-13 are schematic diagrams illustrating the structure of a conventional air-cooled PEM fuel cell stack.

Figure 14 shows a schematic diagram of the structure of a bypass conductive hydrogen flow field plate composite system of a pem fuel cell stack according to a second aspect of the present invention.

Figure 15 shows an example of a structure of a bypass conductive oxygen flow field plate composite system of a pem fuel cell stack according to an embodiment of the present invention.

Fig. 16 shows a side view of an example of a three layer structure highly conductive bypass conductive flow field plate composite system in accordance with one embodiment of the present invention.

Figure 17 shows a side view of the structure of a fuel cell stack comprised of a bypass conductive flow field plate composite system 408, a proton exchange membrane electrode 409 in accordance with one embodiment of the present invention.

Figure 18 illustrates a front view of an oxygen flow field plate of a bypass conductive pem fuel cell stack according to one embodiment of the present invention.

Figure 19 shows a front view of hydrogen flow field plates of a bypass conductive proton exchange membrane fuel cell stack in accordance with one embodiment of the present invention.

1 bypass conductive heat sink, 2 hydrogen channels, 3 conductive and thermally conductive film mesh, 4 bypass conductive circuitry, 5 hydrogen flow field plates, 6 oxygen flow field plates, 7 heat sinks external to the stack, 8 filtration and humidification devices, 9 current, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31 hydrogen flow field, 32 hydrogen flow channel, 33 oxygen flow field, 34 proton exchange membrane, 35 catalyst layer, 36 diffusion layer, 401 bypass conductive joint, 402 conductive coating portion, 403 hydrogen flow field plate, 404 gas seal, 405 oxygen flow field plate, 407 flow field plate substrate, 408 bypass conductive composite system, 409 proton exchange, 360 first diffusion layer, second diffusion layer, 361 gas seal, 362 bypass conductive portion 363,

insulation portion

363, 364 bypass conductive joint.

Detailed Description

It should be noted that the term "oxygen flow field plate" herein includes both the case of using a pure oxygen source and the case of using air as an oxygen source.

Herein, "hydrogen flow field plate" and "hydrogen flow field plate" are used interchangeably, and "oxygen flow field plate" are used interchangeably.

I. First aspect

The device comprises an off-stack bypass current proton exchange membrane electrode utilizing a high-conductivity heat-conducting film, a proton exchange membrane fuel cell and a proton exchange membrane fuel cell stack.

Firstly, summarizing the general idea of the first embodiment of the present invention, aiming at the problems of electrical conduction and heat dissipation commonly existing in the operation of the pem fuel cell stack, the first embodiment of the present invention utilizes a new material of a thin film with high electrical and thermal conductivity to diffuse reaction current and reaction heat from the middle of the reactor to the periphery of the reactor, wherein the current is conducted to both ends of the reactor through an external circuit, and the reaction heat is dissipated through air or liquid around the reactor, so as to maintain the temperature inside the fuel cell stack and ensure the normal operation of the stack. Therefore, the medium for transmitting the hydrogen-oxygen reaction current and heat from the inside of the stack to the outside of the stack is not gaseous substances such as air, carbon dioxide and the like, nor liquid substances such as water and the like, but is solid substances proposed in the first embodiment of the present invention, and is a new material with high electrical and thermal conductivity. The first embodiment of the present invention creates a third cooling method for a pem fuel cell stack: a solid state heat conductive proton exchange membrane fuel cell stack. Meanwhile, the invention also creates a brand new current conduction mode of the proton exchange membrane fuel cell stack: the outside of the stack bypasses the current proton exchange membrane fuel cell stack.

Due to the excellent performances of solid heat conduction and bypass electric conduction, the proton exchange membrane fuel cell stack has the characteristics of high power, stable performance, high power-weight ratio and the like. Can conveniently realize hydrogen-air and hydrogen-oxygen proton exchange membrane fuel cell stacks, methane-gas and oxygen fuel cell stacks and the like.

As described above, the fuel cell stack is formed by stacking a plurality of single fuel cells, which are conventionally formed by a cathode flow field plate, an anode flow field plate and a proton exchange membrane electrode therebetween, wherein the conventional proton exchange membrane electrode has a 5-layer structure, i.e., a first diffusion layer, a first catalyst layer, a proton exchange membrane, a second catalyst layer and a second diffusion layer are sequentially stacked, and the conventional proton exchange membrane, in other words, is formed by a proton exchange membrane and a catalyst layer and a diffusion layer respectively disposed at both sides thereof. In order that those skilled in the art will better understand the invention, the following aspects of the invention are described in conjunction with the sequence of drawings: 1. novel proton exchange membranes; 2. proton exchange membrane fuel cells; 3. a proton exchange membrane fuel cell stack.

A novel proton exchange membrane

As described in the background art, the core membrane electrode in the prior art pem fuel cell stack is composed of a five-layer structure including a middle pem, catalyst layers on both sides, and a diffusion layer. The membrane electrode with the structure can effectively promote the hydrogen-oxygen reaction to generate current and heat, but has no electric conduction and heat dissipation functions. On the basis of the traditional five-layer membrane electrode, the invention adds a layer of high electric and heat conduction layer made of high electric and heat conduction film material on two sides of the membrane electrode respectively to form the proton exchange membrane electrode with seven-layer structure.

A proton exchange membrane electrode of a seven-layer structure according to an embodiment of the present invention will be described below with reference to the accompanying drawings.

Fig. 1 shows a side view of a proton exchange membrane electrode of seven-layer structure according to an embodiment of the present invention, which has high electrical and thermal conductivity. The proton exchange membrane electrode includes a proton exchange membrane 34, a catalyst layer 35 on both sides, and a diffusion layer 36, and the structures and properties of these three layers may be the same as conventional. The proton exchange membrane electrode of the embodiment of the invention is different from the traditional proton exchange membrane electrode in that: and two electric and heat conduction film layers 30(30-1 and 30-2) positioned at the outermost sides.

As can be seen from fig. 1, the electric and thermal conductive film layer 30 includes a bypass electric and thermal conductive heat sink portion 1, a hydrogen channel 2, an electric and thermal conductive film network 3, and a bypass electric and thermal conductive circuit 4, and the high electric and thermal conductive film network 3 is located at two sides of the membrane electrode, so that the current 9 generated by the reaction can flow from the surface of one membrane 30-1 to the surface of the other membrane 30-2, thereby forming a novel high electric and thermal conductive proton exchange membrane electrode. Hydrogen needed by the hydrogen-oxygen reaction passes through the high-electric-conductivity heat-conduction film network 3, and then is diffused by the diffusion layer 36 to generate hydrogen ions under the action of the catalyst 35, and after passing through the proton exchange membrane 34, the hydrogen ions are subjected to electrochemical reaction with oxygen and electrons (electrons released by hydrogen) on the other side of the proton exchange membrane 34 to generate current, reaction heat, water and the like; the electrons released by the hydrogen do not pass through the proton exchange membrane and are led out by the high electric and heat conduction film net 30-1, and two high electric and heat conduction film nets 30-1 and 30-2 are shown in the figure.

By way of example, the first and second electrically and thermally conductive thin film layers 30-1 and 30-2 also serve to bypass heat generated by the electrochemical reaction.

In the example, the bypass conductive heat sink member 1 is located outside the hydrogen-oxygen reaction region.

Illustratively, the bypass conductive heat sink member 1 dissipates heat by air or liquid.

Illustratively, the bypass circuit 4 is fabricated from a non-noble metal.

Illustratively, the electrically and thermally conductive film mesh 3 is made of a graphene composite film or a highly thermally conductive graphite film.

Fig. 2 more clearly shows the structure of the highly electrically and thermally conductive film according to one embodiment of the present invention. The structure consists of four parts, wherein 1 is a bypass conductive heat dissipation part which is in contact with air or liquid and dissipates heat through heat exchange with gas or liquid; 2 is a hydrogen channel, and hydrogen required by the hydrogen-oxygen reaction reaches a hydrogen flow field in the reactor through the channel 2; 3 is a high electric and heat conducting film network, the current 9 and heat generated by the hydrogen-oxygen reaction are diffused to the heat dissipation part 1 through the high heat conducting film network 3, meanwhile, the gas of the hydrogen-oxygen reaction passes through the gaps in the high electric and heat conducting film network 3 to reach the diffusion layer of the membrane electrode 100, and the water generated by the reaction also passes through the electric and heat conducting film network 3 to be discharged; 4 is bypass electric conduction circuit, bypass electricity conduction heat dissipation part 1 connects electrically conductive heat conduction film net (3) and bypass electric conduction circuit (4), the outside that the electric current flows to bypass electric conduction circuit (4) and draws forth the oxyhydrogen reaction zone from electrically conductive electric heating film net (3) through bypass electricity conduction heat dissipation part (1), contact and pass high electrically conductive heat conduction film by electrically conductive metal and high electrically conductive heat conduction film, form the electric conduction circuit between two high electrically conductive heat conduction films of connection oxyhydrogen flow field board both sides, make the monomer battery establish ties and output higher voltage.

Fig. 3(a) and 3(b) show a structure of a highly conductive film in a seven-layer structure proton exchange membrane electrode according to an embodiment of the present invention, in which fig. 3(a) shows a heat dissipation structure. The high-conductivity thin film structure consists of four parts: a bypass conductive part 1, a hydrogen channel 2, a conductive film net 3 and a bypass conductive circuit 4. Wherein 1 is a bypass conductive part, the part is in contact with a bypass conductive circuit 4, conductive metal is in contact with the high conductive thin film and penetrates through the high conductive thin film to form a conductive circuit between the high conductive thin films, so that current 9 produced by reaction can flow from the surface of the conductive film on one side of the flow field plate to the surface of the conductive film on the other side of the flow field plate; 2 is a hydrogen channel, and hydrogen required by the hydrogen-oxygen reaction reaches a hydrogen flow field in the reactor through the channel; 3 is a high conductive film net, the current generated by the oxyhydrogen reaction is diffused to the bypass conductive circuit through the high conductive net, meanwhile, the gas generated by the oxyhydrogen reaction passes through the gaps in the high conductive net to reach the diffusion layer of the membrane electrode, and the water generated by the reaction also passes through the net to be discharged. The highly electrically and thermally conductive film structure shown in fig. 3(a) and 3(b) is different from the highly electrically and thermally conductive film structure shown in fig. 2 in that the highly electrically and thermally conductive film structure shown in fig. 3(a) and 3(b) does not have the heat dissipation structure shown in fig. 2.

Proton exchange membrane fuel cell

The high electric and heat conduction proton exchange membrane electrode is combined with the flow field plate to form a high electric and heat conduction proton exchange membrane fuel cell monomer, and a plurality of proton exchange membrane fuel cell monomers are stacked to form a fuel cell stack.

Fig. 4 shows an example of the structural composition of a single fuel cell 200 according to an embodiment of the present invention, where the single fuel cell 200 is composed of two flow field plates, namely a highly electrically and thermally conductive proton exchange membrane electrode 100 and a hydrogen flow field plate 5 and an oxygen flow field plate 6. Wherein the high electric and heat conduction proton exchange membrane electrode 100 is positioned in the middle, and the hydrogen flow field plate 5 and the air flow field plate 6 are respectively positioned at two sides of the high electric and heat conduction proton exchange membrane electrode 100. The bypass electrical circuit 4 of the highly electrically and thermally conductive film layer 100 enables the current 9 produced by the reaction to flow from the surface of one highly electrically and thermally conductive film to the surface of the other highly electrically and thermally conductive film, and the current no longer passes through the bipolar plate (the positions correspond to the hydrogen flow field plate 5 and the oxygen flow field plate 6 in the embodiment of the present invention) as is conventional. It can be seen that the bypass conductive heat sink portion 1 in the proton exchange membrane electrode 100 with high electrical and thermal conductivity is located outside the medium hydrogen-oxygen reaction region of the single cell. The outermost black portions in fig. 4 represent hydrogen and oxygen flow field plates to distinguish them from the hydrogen and oxygen flow field plates inside the stack.

Three, proton exchange membrane fuel cell stack

Fig. 5 is a schematic diagram illustrating the structure of a high electrical and thermal conductivity pem fuel cell stack 300 according to an embodiment of the present invention. The pem fuel cell stack 300 is formed by stacking a plurality of pem fuel cells. The hydrogen flow field plate 5 and the oxygen air flow field plate 6 form an oxyhydrogen flow field plate when being overlapped, and the high-conductivity heat-conduction proton exchange membrane electrode is positioned in the middle of the oxyhydrogen flow field plate. The bypass conductive circuit 4 of the high-conductivity heat-conducting thin film layer is made of high-conductivity materials to avoid oxyhydrogen

flow field plates

5 and 6 to link two high-conductivity heat-conducting proton exchange membrane electrodes together, so that current 9 generated by oxyhydrogen reaction is conducted through the bypass conductive circuit 4, flows from the surface of one membrane to the surface of the other membrane and does not pass through the oxyhydrogen flow field plate any more, and the oxyhydrogen flow field plate does not need to conduct electricity, so that the high-conductivity heat-conducting thin film layer can be made of materials with much lower cost such as ceramics. The bypass electric conduction heat dissipation part 1 of the high electric conduction heat conduction proton exchange membrane electrode is positioned outside the hydrogen-oxygen reaction area of the proton exchange membrane battery cell stack and dissipates heat through air or liquid. The outermost black portions in fig. 5 represent hydrogen and oxygen flow field plates to distinguish them from the hydrogen and oxygen flow field plates inside the stack.

The fuel cell stack based on the proton exchange membrane with high electric and heat conductivity provided by the embodiment of the invention has two major innovation points of bypass electric conductivity and solid-state heat conductivity. Based on the innovation, the bipolar plate in the original galvanic pile no longer has the function of conducting electricity, and in the new galvanic pile, only plays the role of guiding oxyhydrogen gas, so that in the newly invented galvanic pile, the bipolar plate is called as follows: oxyhydrogen flow field plates, or simply flow field plates. Specific implementations can be combined to form a plurality of fuel cell stacks with proton exchange membranes having different functions, and specific implementation examples are given below.

The first embodiment is as follows: solid state heat-conducting proton exchange membrane fuel cell stack

The heat dissipation is one of the core problems faced by the proton exchange membrane battery stack, and in the embodiment, a solid high heat conduction membrane material is adopted to conduct the reaction heat of the hydrogen-oxygen reaction from the inside of the stack to the periphery of the stack, and then the heat dissipation is performed through an air or liquid heat exchange device.

Fig. 6 and 7 show a high thermal conductivity pem fuel cell stack and its liquid heat sink, where reference numeral 7 denotes a heat sink outside the stack and 8 denotes a filtering and humidifying device. Wherein fig. 6 shows a hydrogen flow field view in which a liquid heat sink is arranged around a heat dissipating portion of the highly electrically and thermally conductive film, and heat exchange is performed with the heat dissipating portion, thereby dissipating the heat of the hydrogen-oxygen reaction. Figure 7 shows an oxygen flow field view that provides an oxygen or air heating, humidifying device, in addition to the same heat sink as shown in figure 6, enabling a wider climate adaptability and longer life of the oxyhydrogen stack. Reference numeral 7 denotes a heat sink, and in the stack, heat exchange air or liquid required by the heat sink and oxygen or air required by the reactor reaction are independent from each other and do not interfere with each other, so that the oxygen source of the pem fuel cell stack may be either air, i.e., a hydrogen-air fuel cell stack, or oxygen, i.e., a hydrogen-oxygen fuel cell stack.

As can be seen from fig. 6 and 7, no matter the electric stack of the present embodiment adopts air heat dissipation or liquid heat dissipation, air required for hydrogen-air reaction and air flow or liquid required for heat dissipation are independent of each other and do not interfere with each other, so that the air required for hydrogen-air reaction can pass through the filtering and humidifying device 8, the service life of the battery is prolonged, and the adaptability of the battery to the use environment is increased.

Example two: bypass conductive proton exchange membrane fuel cell stack

High electrical conductivity is another core problem faced by pem cell stacks. Generally, a proton exchange membrane cell stack generates an extremely large internal current at the time of power generation, for example, a small stack having a power generation power of several tens kw has an internal current as high as several hundreds amperes, and thus a flow field plate is required to have an excellent conductivity property and an extremely low internal resistance. The current flow field plate material meeting this requirement is high purity graphite, but is difficult to manufacture and dissipate heat. For the metal flow field plate proton exchange membrane battery pile, hydrogen needed by hydrogen-oxygen reaction can generate hydrogen corrosion action on a plurality of metals, and hydrogen ions generated in the hydrogen-oxygen reaction can react with the metals to corrode the metals and generate metal ions to poison the catalyst. Therefore, metal flow field plates typically require precious metals and complex processing techniques, which greatly increases the price of the stack. In the embodiment of the invention, the electric and heat conducting film net 3 is made of a new material with a high electric conducting film, the current generated by the hydrogen-oxygen reaction is led out to the periphery of the galvanic pile from the inside of the galvanic pile, and then the current is conducted through the bypass circuit outside the galvanic pile, so that the flow field plate inside the galvanic pile does not need to have the electric conducting function and can be made of non-conducting and corrosion-resistant materials such as resin, ceramics, plastics and the like. And a bypass circuit outside the pile does not contact hydrogen and hydrogen ions and can be realized by common metal with good conductivity.

Fig. 8 is a schematic diagram illustrating a construction of a stack of a bypass conductive pem fuel cell and a bypass circuit device thereof according to an embodiment of the present invention. In the stack of the bypass conductive proton exchange membrane fuel cell, the high conductive film diffuses the current 9 generated by the hydrogen-oxygen reaction to the whole membrane surface, and a bypass conductive device 4 outside the stack crosses the flow field plate to connect the positive and negative electrodes of the two high conductive proton exchange membrane electrodes together to form a bypass conductive circuit outside the flow field plate, so that the proton exchange membranes stacked together with the flow field plate form a series structure through the bypass circuit.

As can be seen from fig. 8, the bypass conductive device outside the stack and the flow field plate in the embodiment of the present invention have the same effect, and the positive and negative electrodes of the two highly conductive proton exchange membrane electrodes are connected together, so that the stacked single cells form a series structure, thereby increasing the output voltage of the stack. However, after the bypass circuit is adopted, the flow field plate can be made of non-conductive materials, such as various plastics, ceramics and the like, or can also be made of metal materials which have poor conductivity and low price and are easy to manufacture, so that the cost of the galvanic pile is greatly reduced, the service life of the battery is prolonged, and the service environment adaptability of the battery is improved.

Example three: solid state heat-conducting proton exchange membrane fuel cell stack

With the development of material science and technology, the film surface of the new material of the electric and heat conducting film can simultaneously have excellent performances of high electric conductivity and high heat conductivity, so that the local heat and electricity on the film surface can be rapidly diffused to the whole surface. The invention adopts a new material of a solid high-conductivity high-heat-conduction membrane, quickly guides reaction heat of hydrogen-oxygen reaction from the inside of the galvanic pile to the periphery of the galvanic pile, and then radiates the heat through an air or liquid heat exchange device. Meanwhile, the high-conductivity heat-conducting film guides the current generated by the hydrogen-oxygen reaction from the inside of the galvanic pile to the periphery of the galvanic pile, and then the current is conducted through a bypass circuit outside the galvanic pile, so that the flow field plate inside the galvanic pile does not need to have a conductive function and can be made of non-conductive and corrosion-resistant materials such as resin, ceramics, plastics and the like.

Fig. 9 is a schematic diagram showing a structure of a high electric and thermal conductivity pem fuel cell stack and a bypass electric and liquid heat dissipation device thereof. In the electric pile, electricity and heat generated by hydrogen-oxygen reaction are conducted to the periphery of the electric pile from the inside of the electric pile through the high-conductivity heat-conducting film, and then the current is conducted through the bypass circuit outside the electric pile, so that the heat dissipation device dissipates heat. The heat exchange air or liquid required by the heat radiator and the oxygen or air required by the reactor reaction are mutually independent and do not interfere with each other, so that the oxygen source of the high-heat-conduction proton exchange membrane fuel cell stack can be air, namely a hydrogen-air fuel cell stack, and can also be oxygen, namely a hydrogen-oxygen fuel cell stack. The service life of the battery is prolonged, and the service environment adaptability of the battery is improved.

Example four: graphene solid-state electric and heat conduction proton exchange membrane fuel cell stack

The high-conductivity heat-conducting film of the embodiment of the invention can be realized by a noble metal material, such as gold foil. The gold foil has very good electric and heat conducting properties, and the gold itself has very good acid corrosion resistance. However, noble metals are on the one hand expensive and on the other hand resource-limited and are not suitable for large-scale industrial applications.

In recent years, with the development of scientific research and technology of materials, a plurality of new thin film materials with high electric conductivity and thermal conductivity emerge. One embodiment of the invention adopts a novel film material meeting the requirements of high electric conductivity, corrosion resistance and high heat conductivity of a galvanic pile: high-conductivity and heat-conductivity graphene composite material film, high-conductivity and heat-conductivity graphite film and the like.

The graphene-based Graphite film is also called a Thermal conductive Graphite material (Thermal Flexible Graphite sheet), a Thermal conductive Graphite sheet, a Graphite heat sink, a graphene-based composite heat dissipation material and the like, and is a brand new electric and Thermal conductive heat dissipation material. The brand new heat conduction material is a high-purity composite graphene film or graphite film synthesized by purifying graphite powder at high temperature and removing a plurality of impurities in the graphite powder. Or preparing graphite oxide from natural crystalline flake graphite by a Hummers method, thermally stripping the graphite oxide to form graphene, or dispersing and stripping the graphite oxide by ultrasonic waves to form graphene oxide, and chemically reducing the graphene oxide to form the graphene-based composite film material.

The graphene-based graphite film is mainly characterized by having ultrahigh horizontal electric and thermal conductivity far higher than that of common natural graphite, the horizontal heat conductivity of the graphene-based graphite film is higher than 1500W/m-k, and the vertical heat conductivity of the graphene-based graphite film is 20W/m-k, so that local high heat can be rapidly diffused to the surface of the whole film, large-area heat dissipation is realized, and the local high-temperature state is improved. The high-thermal-conductivity graphite film material has low thermal resistance: thermal resistance 40% lower than that of aluminum and 20% lower than that of copper, and light weight: the composite material has the advantages of being lighter than aluminum by 25 percent, lighter than copper by 75 percent, stable in chemical performance and the like, provides a unique solution with comprehensive high performance for the heat management industry, brings a new technical scheme for the industrial heat dissipation field which is increasingly widely demanded, and is an innovative technology of heat management.

Aiming at the problem of electric conduction and heat dissipation of the fuel cell stack, the embodiment of the invention adopts innovative materials in the field of heat management, a high-heat-conduction thin-layer graphene-based composite material, a high-heat-conduction graphite heat dissipation material and the like to manufacture the high-heat-conduction graphene-based composite material thin-layer heat sink to form the high-heat-dissipation membrane electrode, so that the reaction heat of hydrogen and oxygen is brought to the periphery of the reactor from the inside of the reactor, and the heat is dissipated through air or liquid. Therefore, one embodiment of the present invention creates a solid state cooling method for a pem fuel cell stack based on a highly electrically and thermally conductive graphene-based material.

Bipolar plate with conductive coating according to the second aspect

In the foregoing first aspect, the proton exchange membrane electrode further includes a first electrically and thermally conductive thin film layer and a second electrically and thermally conductive thin film layer, which are respectively located outside the first diffusion layer and the second diffusion layer, and the first electrically and thermally conductive thin film layer and the second electrically and thermally conductive thin film layer are used for leading out the current generated by the electrochemical reaction without bypassing the flow field plate.

According to a second aspect of the present invention, a flow field plate is modified, wherein a side of the flow field plate close to a proton exchange membrane is coated (the coating is a broad concept and comprises various electroplating, coating and other processes) with a conductive coating film and is provided with a conductive joint, and the flow field plate can be made of a non-conductive material, so that the original bipolar plate has the dual functions of gas flow field and electric conduction but only needs to bear the function of the gas flow field, and the electric conduction function is achieved by the conductive coating film and a bypass conductive circuit outside the bipolar plate. In other words, the bipolar plates of the prior art are composed of a single material (mainly graphite), while the bipolar plates of the present invention (corresponding to the name flow field plate composite system in the claims) are composed of several composite parts, including at least a flow field plate, a conductive coated part coated on the surface of the flow field plate, and a conductive joint.

A bipolar plate with an electrically conductive coating according to an embodiment of the present invention is described below with reference to the accompanying drawings.

Figure 14 shows a schematic diagram of the structure of a bypass electrically conductive hydrogen-oxygen flow field plate composite system of a proton exchange membrane fuel cell stack according to a second aspect of the present invention. As shown in fig. 14, the hydrogen-oxygen flow field plate composite system comprises: conductive coated portions 401 (on the front and back sides of an oxyhydrogen flow field plate 403), a bypass conductive contact 402, and the oxyhydrogen flow field plate 403, wherein the bypass conductive contact 402 is in contact with the conductive coated portions 401. A bypass conductive contact 402 crosses (bypasses or penetrates) the oxyhydrogen flow field plate 403 and contacts the conductive coated portion 401 on the back side of the oxyhydrogen flow field plate 403 to form a conductive circuit between the two sides of the oxyhydrogen flow field plate, so that the current generated by the reaction can flow from one side of the flow field plate to the other side of the flow field plate. Hydrogen required for the hydrogen-oxygen reaction passes through a hydrogen flow field in a hydrogen-oxygen flow field plate, passes through a diffusion layer of a proton exchange membrane (not shown in fig. 14), and is contacted with a catalyst of a proton exchange membrane electrode to generate electrochemical reaction. 404 is a gas seal ring, which blocks the way of gas diffusion out of the seal ring and prevents gas leakage.

Figure 15 shows an example of the structure of a bypass conductive hydrogen-oxygen flow field plate composite system of a proton exchange membrane fuel cell stack according to an embodiment of the present invention. The oxygen required for the hydrogen-oxygen reaction passes through the oxygen flow field in the hydrogen-oxygen flow field plate 403, passes through the diffusion layer of the proton exchange membrane (not shown in fig. 15), and contacts the catalyst of the proton exchange membrane electrode, and the electrochemical reaction occurs.

It should be noted that in the case of using air as an oxygen source, a gas seal ring does not need to be arranged around the oxygen flow field in the hydrogen-oxygen flow field plate composite system, but in the case of using pure oxygen as an oxygen source, similar to the case of the hydrogen flow field plate composite system, a gas seal ring located at the edge of the flow field plate needs to be arranged to block the path of gas diffusing out of the seal ring, so as to prevent gas leakage.

It should be noted that the surface close to the diffusion layer and the opposite surface of the hydrogen flow field plate in the hydrogen-oxygen flow field plate composite system are coated with a conductive layer, and the surface close to the diffusion layer and the opposite surface of the oxygen flow field plate in the hydrogen-oxygen flow field plate composite system are coated with a conductive layer.

Fig. 16 shows a side view of an example of a three layer structure highly conductive bypass conductive flow field plate composite system in accordance with one embodiment of the present invention. As can be seen from the figure, the bypass conductive flow field plate system is composed of a substrate 407 as a flow field plate, conductive coated portions 4010 and 4011, and bypass conductive connectors 402 at two ends, and is characterized in that the substrate 407 can be any conductive or non-conductive material, such as ceramic, plastic, stainless steel, etc., and the conductive coating 402 can be a metal coating, a graphite deposited layer, graphene, etc.; the conductive connectors 402 at the two ends can be made of highly conductive metal, graphene and other materials, so that current produced by reaction can be rapidly diffused in the highly conductive coating, and flows from one surface of the flow field plate to the back surface of the flow field plate through a bypass conductive circuit formed by the conductive connectors 402, and a novel bypass conductive flow field plate composite system is formed.

The bypass conductive flow field plate composite system is combined with the proton exchange membrane electrode to form a bypass conductive proton exchange membrane fuel cell monomer, and a plurality of proton exchange membrane fuel cell monomers are stacked to form a bypass conductive circuit proton exchange membrane fuel cell stack.

Figure 17 shows a side view of the structure of a fuel cell stack comprised of a bypass conductive flow field plate composite system 408, a proton exchange membrane electrode 409 in accordance with one embodiment of the present invention. The current produced by the proton exchange membrane electrode reaction flows from the surface of one flow field plate to the other surface of the flow field plate through a bypass circuit through the highly conductive coating layers 4010 and 4011 and the conductive connector 402, and the current does not pass through the flow field plate any more, so that the flow field plate becomes a bypass conductive bipolar plate.

The proton exchange membrane fuel cell stack based on the bypass conductive flow field plate composite system has the significant innovation point of bypass conductivity. Based on the innovation, the bipolar plate in the original galvanic pile no longer has the current penetrating conducting function, and the conducting function is replaced by a bypass conducting circuit formed by a high-conducting plating layer on the surface of the flow field plate and an outer bypass conducting structure. In the novel stack of the present embodiment, the flow field plates only serve to conduct oxyhydrogen gas, and therefore, are not referred to herein as bipolar plates, but as hydrogen flow field plates, oxygen flow field plates, or occasionally as bypass conductive oxyhydrogen flow field plates, or simply flow field plates. Specific implementations may be combined to form a variety of bypass conductive fuel cell stacks having different functions.

As previously mentioned, the high electrical conductivity of conventional bipolar plates is a central problem faced by pem cell stacks. Generally, a proton exchange membrane cell stack generates a large internal current, for example, a small stack with a power generation power of several tens kw, and the internal current is as high as several hundreds amperes, so that a bipolar plate/flow field plate is required to have excellent conductivity and extremely low internal resistance. The current flow field plate material meeting this requirement is high purity graphite, but is difficult to manufacture and dissipate heat. For the metal flow field plate proton exchange membrane battery pile, hydrogen needed by hydrogen-oxygen reaction can generate hydrogen corrosion action on a plurality of metals, and hydrogen ions generated in the hydrogen-oxygen reaction can react with the metals to corrode the metals and generate metal ions to poison the catalyst. Therefore, metal flow field plates typically require precious metals and complex processing techniques, which greatly increases the price of the stack. In the embodiment of the invention, a new composite flow field plate material (a plating layer of a flow field plate system is a high-conductivity material, and a flow field plate or a base material can be a non-conductive material) is adopted, current generated by hydrogen-oxygen reaction is led out to the periphery of a galvanic pile from the interior of the galvanic pile, and then the current is conducted through a bypass circuit outside the galvanic pile, so that the flow field plate inside the galvanic pile does not need to have a conductive function, and can be made of non-conductive and corrosion-resistant materials such as resin, ceramics, plastics and the like. And a bypass circuit outside the pile does not contact hydrogen and hydrogen ions and can be realized by common metal with good conductivity.

Figure 17 illustrates a side view of a bypass conductive pem fuel cell stack and bypass circuit assembly thereof according to one embodiment of the present invention. Figure 14 illustrates a front view of a hydrogen flow field of an oxyhydrogen flow field plate of a bypass conductive proton exchange membrane fuel cell stack according to one embodiment of the invention, and figure 15 illustrates a front view of an oxygen flow field of an oxyhydrogen flow field plate of a bypass conductive proton exchange membrane fuel cell stack according to one embodiment of the invention.

In the example of the bypass conductive proton exchange membrane fuel cell stack, the high conductive coating 401 on the surface of the flow field plate diffuses the current generated by the hydrogen-oxygen reaction to the surface of the whole coating, and the bypass conductive connector device 402 outside the stack crosses over two poles of the flow field plate to connect the anode coating 4010 of the oxygen flow field and the cathode coating 4011 of the hydrogen flow field of the flow field plate together to form a bypass conductive circuit outside the flow field plate, so that the proton exchange membrane electrode stacked with the flow field plate forms a series structure through the bypass circuit.

As can be seen from fig. 17, 14 and 15, the bypass conductive device outside the stack according to the embodiment of the present invention has the same effect as the conventional bipolar plate/flow field plate, and the positive and negative electrodes of the two proton exchange membrane electrodes are connected together, so that the stacked unit cells form a series structure, thereby increasing the output voltage of the stack. However, after the bypass circuit is adopted, the flow field plate can be made of non-conductive materials, so that the cost of the galvanic pile is greatly reduced, the service life of the battery is prolonged, and the service environment adaptability of the battery is improved.

The flow field plate composite system of the embodiment comprises a flow field plate, a conductive coating part (6) coated on the surface of the flow field plate (7) and a conductive connector, wherein current generated by hydrogen-oxygen reaction is conducted to the whole conductive coating through a conductive layer on the surface of the flow field plate, and then flows to two ends of a reactor through a bypass circuit to output electric energy outwards. Therefore, the embodiment of the invention is a stack of a bypass conductive proton exchange membrane fuel cell, and the inventive contribution of the embodiment of the invention is as follows: a bypass current proton exchange membrane fuel cell stack. Compared with the internal conduction mode that the current of the existing fuel cell stack passes through the flow field plate/bipolar plate to reach the two ends of the stack, the embodiment of the invention adopts the bypass current mode that the flow field plate composite system containing the conductive coating conducts the current generated by the reaction of the fuel cell from the inside of the stack to the periphery of the stack and then to the two ends of the stack, so that the bipolar plate does not need to have the function of conduction and becomes the flow field plate only with oxyhydrogen gas diversion, thereby greatly reducing the material and manufacturing cost of the flow field plate.

Third aspect: diffusion layer bypass conductive proton exchange membrane electrode

The first aspect provides a scheme of additional arrangement outside a diffusion layer of a proton exchange membrane electrode, the second aspect provides a scheme of coating a high-conductivity layer on the surface of a flow field plate, and a scheme of a diffusion layer bypass conductive proton exchange membrane electrode is provided below, namely the scheme of the proton exchange membrane electrode with the diffusion layer bypass conductive function.

The diffusion layer bypass conductive proton exchange membrane fuel cell comprises a hydrogen flow field plate, an oxygen flow field plate and a diffusion layer bypass conductive proton exchange membrane electrode arranged between the hydrogen flow field plate and the oxygen flow field plate. As shown in fig. 18, the bypass conductive proton exchange membrane electrode includes: the first diffusion layer 360, the first catalyst layer 35, the proton exchange membrane 34, the second catalyst layer 35, and the second diffusion layer 360 are sequentially stacked. In contrast to the diffusion layer 36 (fig. 12) of a conventional proton exchange membrane electrode, the diffusion layer of the present invention includes a gas diffusion portion, which functions as the diffusion layer of a conventional proton exchange membrane electrode and is responsible for gas diffusion; the embodiment of the invention is different from the traditional diffusion layer in that the diffusion layer is extended to form a bypass conductive device, which comprises a gas seal ring 361 formed by gas sealant penetrating into the diffusion layer, a bypass conductive part 362 and an insulating part 363 formed by insulating glue between the first diffusion layer and the second diffusion layer.

As shown in fig. 18 and 19, the first diffusion layer and the second diffusion layer have oxyhydrogen gas diffusion, conductivity, bypass conductivity, etc. functions, and form a bypass conductive circuit outside the flow field plate, and form a gas seal 361 around the diffusion layer to prevent oxyhydrogen gas from diffusing out of the reaction area of the stack, but the diffusion layer extends out of the oxyhydrogen gas reaction area to form a bypass conductive area 362, through which electric energy passes out of the oxyhydrogen reaction area and is connected by a bypass conductive connector 364 crossing the oxyhydrogen flow field plate. In order to prevent the bypass conductive portions of the first and second diffusion layers from contacting, the insulating part 363 formed between the two is filled with an insulating paste to increase the strength of the bypass conductive portion of the diffusion layer and prevent gas leakage.

As shown in fig. 19, a plurality of unit cells are connected in series by a bypass conductive connector 364 to form a high voltage output hydrogen-oxygen proton exchange membrane stack.

The remaining aspects may refer to the previous description regarding the first and second aspects.

The embodiment of the invention revolutionarily provides a method and an implementation scheme for separating the gas flow field and the electric conduction of the flow field plate, so that the flow field plate does not need to have the two functions of the gas flow field and the electric conduction at the same time. Therefore, the embodiment of the invention can change the high-demand bipolar plate with the functions of gas flow field, electric conduction and heat conduction into the flow field plate which is easy to manufacture, and greatly promotes the development of the material and the manufacturing process of the flow field plate, thereby finally promoting the commercial development of the hydrogen electric pile.

It should be noted that, in the foregoing description of the first, second, and third aspects of the present invention, the bypass conductive portion and the device cannot exist independently because the electricity generated by the reaction is extracted from different places (the additional conductive layer, the conductive coating on the flow field plate, the extension portion of the diffusion layer, and the like), and therefore, the bypass conductive portion can only be integrated with the device for extracting electricity.

Having described embodiments of the present invention, the foregoing description is intended to be exemplary, not exhaustive, and not limited to the embodiments disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims

1. A proton exchange membrane fuel cell comprises a hydrogen flow field plate, an oxygen flow field plate and a proton exchange membrane electrode between the two,

the proton exchange membrane electrode includes: a first diffusion layer, a first catalyst layer, a proton exchange membrane, a second catalyst layer and a second diffusion layer which are sequentially stacked,

the proton exchange membrane electrode is characterized by further comprising a first electric conduction and heat conduction thin film layer and a second electric conduction and heat conduction thin film layer which are respectively positioned on the outer sides of the first diffusion layer and the second diffusion layer, and the first electric conduction and heat conduction thin film layer and the second electric conduction and heat conduction thin film layer are used for leading out current generated by electrochemical reaction without bypassing a flow field plate.

2. The pem fuel cell of claim 1 wherein the first and second conductive thin film layers are further configured to bypass heat generated by the electrochemical reaction.

3. The pem fuel cell of claim 1, each of the first and second electrically and thermally conductive thin film layers comprising: a bypass electric heat radiation part (1), a hydrogen channel (2), an electric heat conduction film net (3), a bypass electric circuit (4),

the bypass electricity and heat conducting and radiating part (1) is connected with the electricity and heat conducting film net (3) and the bypass electricity and heat conducting circuit (4), current flows to the bypass electricity and heat conducting circuit (4) from the electricity and heat conducting film net (3) through the bypass electricity and heat conducting and radiating part (1) and is led out to the outside of the hydrogen and oxygen reaction area of the electric pile, a series circuit is formed, and the voltage of the electric pile is improved.

4. The proton exchange membrane fuel cell according to claim 3, wherein the bypass conductive heat sink (1) is located outside the hydrogen-oxygen reaction region, has a conductive function, and is communicated with the positive electrode and the negative electrode of the flow field plate, so that the current generated by the hydrogen-oxygen reaction in the membrane electrode is not led out to two ends of the stack through the flow field plate.

5. The pem fuel cell of claim 3, the bypass heat sink (1) being heat sink by air or liquid.

6. A proton exchange membrane fuel cell according to claim 3, said hydrogen and oxygen flow field plates being fabricated from a non-conductive and non-heat dissipating material.

7. The pem fuel cell of any of claims 1-6 further comprising: and air or oxygen required by the hydrogen-oxygen reaction passes through the filtering and humidifying device (8) and then enters the reactor through the hydrogen flow field plate and the oxygen flow field plate.

8. A proton exchange membrane fuel cell stack formed by connecting proton exchange membrane cells according to any one of claims 1 to 7 in series, wherein the electric current generated by the hydrogen-oxygen reaction is conducted to the outside of the reaction area of the stack through the electric and heat conductive membrane mesh (3) on the proton exchange membrane electrode, and then flows to the two ends of the stack through the bypass electric conduction circuit (4) outside the stack.

9. A proton exchange membrane electrode comprising:

a first diffusion layer, a first catalyst layer, a proton exchange membrane, a second catalyst layer and a second diffusion layer which are sequentially stacked,

10. A method of manufacturing a proton exchange membrane fuel cell as claimed in any one of claims 1 to 7, comprising:

sequentially stacking a first diffusion layer, a first catalyst layer, a proton exchange membrane, a second catalyst layer and a second diffusion layer;

characterized in that the method also comprises: and a first electric conduction and heat conduction film layer and a second electric conduction and heat conduction film layer are arranged on the outer sides of the first diffusion layer and the second diffusion layer and used for leading out the current generated by the electrochemical reaction without bypassing the oxyhydrogen gas flow field plate.