CN109888325B - Multi-stage uniform flow field fuel cell and working method thereof - Google Patents

Abstract

The invention discloses a multi-level uniform flow field fuel cell and a working method thereof. In the multi-level uniform flow field fuel cell of the present invention, a tree-shaped fuel supply branch is expanded from a fuel distribution flow path through a tree-shaped flow field dispersed step by step, The vertical inflow flow field with dendritic dispersion is adopted to ensure that the electrolyte can enter the electrode surface evenly, improve the reaction degree of the electrolyte, and further improve the battery efficiency. The vertical outflow flow field is distributed in an array combined with the inflow flow field to ensure that the electrolyte can flow out of the electrode downstream after the reaction is completed, to ensure that the fuel on the electrode side is always at a uniform and high concentration, and to avoid the mixing of fuel and products.

Description

A kind of multistage uniform flow field fuel cell and its working method

technical field

The invention relates to the technical field of fuel cells, in particular to a multi-level uniform flow field fuel cell.

Background technique

Energy is an important material basis for human survival and development, and all activities of human society are inseparable from energy. With the rapid development of the economy and the continuous progress of the society, the consumption of energy by human beings also continues to increase. Global energy demand continues to grow, and traditional fossil energy consumption still dominates. However, traditional fossil energy reserves are limited, some of which will be exhausted in the coming decades. In addition, in the process of traditional fossil energy utilization, the problem of environmental pollution is also increasing day by day, and the resulting problems such as "greenhouse effect", "acid rain" and "destruction of the ozone layer" seriously threaten the survival and development of human beings. Faced with the severe challenges of energy crisis and environmental protection, finding clean and sustainable energy that can replace traditional fossil energy has become the focus of human research.

At present, solar energy, wind energy, tidal energy, geothermal energy, etc. have the advantages of sufficient energy, clean and pollution-free utilization process. However, there are some problems such as intermittency, instability and low efficiency in the utilization process of this kind of energy. Fuel cells have attracted extensive attention due to their high energy conversion efficiency, low pollution, and no noise. As a new generation of energy technology, fuel cells provide a new way of thinking for solving energy crisis and environmental pollution problems, which is of strategic significance. Fuel cell technology is a new type of power generation technology, which can directly convert chemical energy in fuel and oxidant into electrical energy, with high efficiency, no pollution, no noise, high reliability, modularity, and fast response to load changes. It is considered to be the ultimate solution to the energy crisis.

The fuel cell is mainly composed of ion exchange membrane, cathode and anode electrodes and bipolar plates. The membrane electrode (MEA), which is composed of a cathode electrode, an ion exchange membrane and an anode electrode, is the place where the electrochemical reaction of the fuel cell occurs. Fuel and oxidant are passed to the anode and cathode of the cell, respectively. The fuel (such as H ₂ , CH ₃ OH, CH ₃ CH ₂ OH, CO(NH ₂ ) ₂ , NaBH ₄ , HCOONa, etc.) fed into the anode undergoes an oxidation reaction to release electrons, and the electrons flow into the cathode through the external circuit and interact with the anode. The oxidant (such as O ₂ , H ₂ O ₂ , etc.) of the cathode combines and undergoes a reduction reaction. At the same time, ions migrate through the electrolyte membrane to the cathode (or anode), forming a circuit.

Among many types of fuel cells, direct liquid fuel cells (DLFC) have received extensive attention in recent years due to the advantages of high fuel energy density, convenient storage and transportation, etc. Direct liquid fuel cells use methanol, ethanol, urea, sodium borohydride, formate and other liquids as fuels. According to the different types of solid electrolyte membranes, direct liquid fuel cells can be divided into acidic direct liquid fuel cells and alkaline direct liquid fuel cells.

As a key part of the direct liquid fuel cell, the anode flow field plays the functions of transporting fuel, distributing fuel, and recovering products, and plays a key role in the entire fuel cell operation process. The current fuel cell anode flow field mainly includes serpentine flow field, parallel flow field, discontinuous flow field, interdigitated flow field, etc., which mainly enter the electrode reaction through the diffusion of fuel flowing on one side of the electrode. In this process, with the flow of fuel in the flow channel and the diffusion reaction in the electrode, the fuel is continuously consumed and the product continuously enters the flow channel, and the concentration of the fuel gradually decreases, which leads to the uneven distribution of the fuel concentration in the electrode and reduces the electrode. The reaction efficiency further reduces the working efficiency of the direct liquid fuel cell.

Therefore, in view of the problems of fuel product blending and uneven fuel concentration distribution in the fuel cell fuel flow reaction process, a high-efficiency fuel cell with phase-separated co-current transfer of fuel products and uniform fuel concentration distribution is urgently needed.

SUMMARY OF THE INVENTION

In view of the problems existing in the above-mentioned prior art, the purpose of the present invention is to provide a multi-level uniform flow field fuel cell and a working method thereof, so that the fuel can reach the electrode surface directly and uniformly, ensure the co-current transmission of the fuel and the product, and avoid the fuel Blending of products.

To achieve the above object, the present invention adopts the following technical solutions to realize:

A multi-level uniform flow field fuel cell, comprising an anode flow field plate, an anode current collector plate, an anode electrode, an exchange membrane, a cathode electrode, a cathode current collector plate and a cathode flow field plate arranged on the fuel cell body;

The anode current collector plate is connected with the anode flow field plate and the anode electrode, the anode electrode and the cathode electrode are separated by an exchange membrane, and the cathode current collector plate is connected with the cathode electrode and the cathode flow field plate;

The anode flow field plate is a flow field plate provided with a fuel inlet, a fuel distribution flow path, a tree-shaped fuel supply branch, an array-shaped product discharge branch, a product recovery flow path, and a product outlet, wherein the tree-shaped fuel supply branch passes through one by one. The hierarchically dispersed tree-like flow field is expanded by the fuel distribution flow path, and the array-shaped product discharge branches are evenly distributed and connected to the product recovery flow path;

The fuel inlet is the inlet connecting the fuel distribution flow path to the outside of the fuel cell, the tree-shaped fuel supply branch inlet is connected to the fuel distribution flow path, the tree-shaped fuel supply branch outlet is connected to the anode electrode through the anode current collector, and the array-shaped products are discharged The inlet of the branch is connected to the anode electrode through the anode current collector plate, the outlet of the array-shaped product discharge branch is connected to the product recovery flow path, and the dendritic fuel supply branch and the array-shaped product discharge branch are located in the anode flow field plate in a staggered manner. The connected pipeline, the product outlet is the outlet connecting the product recovery flow path and the outside of the fuel cell;

The anode current collector plate is a flat plate with an array of distribution holes, the holes in the anode current collector plate are connected with the outlet of the tree-shaped fuel supply branch and the inlet of the array-shaped product discharge branch, and the cathode current collector plate is in phase with the flow channel of the cathode flow field plate. Correspondingly, the flat plate with pores, and the cathode flow field plate is a flat plate with flow channels.

Further, the product recovery flow path is longitudinally arranged in the anode flow field plate, the product outlet is located at the top of the anode flow field plate, and the fuel inlet is located on the side wall of the anode flow field plate.

Further, a plurality of the tree-shaped fuel supply branch outlets and a plurality of array-shaped product discharge branch inlets are arranged at equal intervals.

Further, the dendritic fuel supply branch is a binary tree-like dispersed flow field step by step, that is, the dendritic fuel supply branch is divided into 4 branches by a 90° rotating array of one electrolyte supply flow path, and the 4 branches are further Divided into 16 branches, distributed through "1-4-16" step-by-step dispersion.

Further, the array-shaped product discharge branches are distributed outside the electrode in a "3×3" array.

Further, the materials used for the anode flow field plate and the cathode flow field plate are inorganic non-metallic materials, metal composite materials or organic polymer materials.

Further, the materials of the anode current collector plate and the cathode current collector plate are inorganic non-metallic or metallic conductive materials.

Further, the anode electrode and the cathode electrode are conductive metal materials or carbon materials coated with corresponding catalysts and having a porous structure.

Further, the exchange membrane is a cation exchange membrane, an anion exchange membrane or a neutral exchange membrane;

A working method of a multi-level uniform flow field fuel cell, comprising the following steps:

Step S100: The fuel is evenly distributed into the electrodes:

The unreacted fuel of the fuel cell enters the anode side of the fuel cell through the fuel inlet, and is evenly distributed to the tree-like fuel supply branch through the fuel distribution flow path under the action of the pump power, and enters the anode electrode; at the same time, the oxidant passes through the cathode flow field plate and The cathode current collector plate enters the cathode electrode;

Step S200: battery discharge reaction:

The fuel undergoes a discharge reaction on the surface of the anode electrode;

Step S300: The product flows out of the battery downstream:

After the fuel reaction is completed, the fuel flowing in from the outlet of each dendritic fuel supply branch passes through the anode electrode and flows out from the inlet of the array-shaped product discharge branch, and converges to the product recovery flow path and is discharged through the product outlet.

Compared with the prior art, the present invention has the following advantages and effects:

The multi-stage uniform flow field fuel cell of the present invention comprises an anode flow field plate, an anode current collector plate, an anode electrode, an exchange membrane, a cathode electrode, a cathode current collector plate and a cathode flow field plate arranged on the fuel cell body; The flow plate is connected with the anode flow field plate and the anode electrode, the anode electrode and the cathode electrode are separated by an exchange membrane, and the cathode current collector plate is connected with the cathode electrode and the cathode flow field plate; The flow field is expanded by the fuel distribution flow path, and the vertical inflow field with a tree-like dispersion is adopted to ensure that the electrolyte can enter the electrode surface uniformly, improve the reaction degree of the electrolyte, and further improve the efficiency of the battery;

At the same time, the array-shaped product discharge branches are evenly distributed and connected to the product recovery flow path, and an array combined with the inflow flow field is used to distribute the longitudinal outflow flow field to ensure that the electrolyte can flow out of the electrode downstream after the reaction is completed, and to ensure that the fuel on the electrode side always flows Uniform high concentration, avoiding the mixing of fuel and product.

Further, the plurality of tree-shaped fuel supply branch outlets and the plurality of array-shaped product discharge branch inlets are arranged at equal intervals, and after the fuel reaction is completed, the fuel flowing in from the outlet of each tree-shaped fuel supply branch is closer from the distance. The array-shaped product discharge branch flows out from the inlet, and converges to the product recovery flow path for discharge, which further reduces the pressure difference between the inlet and outlet, reduces the extra pump work of the battery, and improves the battery efficiency.

Description of drawings

Fig. 1 is a schematic diagram of the structure of the fuel cell of the present invention;

Figure 2 is a side view of a fuel cell current collector plate of the present invention;

In the figure, 1-anode flow field plate, 2-anode current collector plate, 3-anode electrode, 4-exchange membrane, 5-cathode electrode, 6-cathode current collector plate, 7-cathode flow field plate, 8-fuel inlet , 9-fuel distribution flow path, 10-tree fuel supply branch, 11-array product discharge branch, 12-product recovery flow path, 13-product outlet.

Detailed ways

The present invention will be described in further detail below with reference to the accompanying drawings and specific embodiments, but it is not intended to limit the present invention.

1-2, the multi-stage uniform flow field fuel cell of the present invention includes an anode flow field plate 1, an anode current collector plate 2, an anode electrode 3, an exchange membrane 4, a cathode electrode 5, and a cathode disposed on the fuel cell body. The current collector plate 6 and the cathode flow field plate 7; the anode current collector plate 2 is connected with the anode flow field plate 1 and the anode electrode 3, the anode electrode 3 and the cathode electrode 5 are separated by the exchange membrane 4, and the cathode current collector plate 6 is connected with the cathode electrode 5 is connected to the cathode flow field plate 7 .

The anode flow field plate 1 is a flow field plate provided with a fuel inlet 8, a fuel distribution flow path 9, a tree-shaped fuel supply branch 10, an array-shaped product discharge branch 11, a product recovery flow path 12 and a product outlet 13, wherein the tree The fuel supply branches 10 are spread out from the fuel distribution flow path 9 through a tree-shaped flow field dispersed step by step, and the product discharge branches 11 in an array are evenly distributed and connected to the product recovery flow path 12 .

The fuel inlet 8 is the inlet connecting the fuel distribution flow path 9 to the outside of the fuel cell, the inlet of the tree-shaped fuel supply branch 10 is connected to the fuel distribution flow path 9, and the outlet of the tree-shaped fuel supply branch 10 is connected to the anode electrode through the anode current collector plate 2. 3 is connected, the inlet of the array-shaped product discharge branch 11 is connected to the anode electrode 3 through the anode current collector plate 2, the outlet of the array-shaped product discharge branch 11 is connected to the product recovery flow path 12, and the tree-shaped fuel supply branch 10 and the array-shaped product are connected. The discharge branch 11 is a pipeline that is located in the anode flow field plate 1 in a staggered and disconnected manner, and the product outlet 13 is an outlet connecting the product recovery flow path 12 to the outside of the fuel cell.

The product recovery flow path 12 is longitudinally arranged in the anode flow field plate 1 , the product outlet 13 is located at the top of the anode flow field plate 1 , and the fuel inlet 8 is located on the side wall of the anode flow field plate 1 .

The outlets of a plurality of tree-shaped fuel supply branches 10 and the inlets of a plurality of array-shaped product discharge branches 11 are arranged at equal intervals.

The anode current collector plate 2 is a flat plate with an array of distribution holes. The holes in the anode current collector plate 2 are connected to the outlet of the tree-shaped fuel supply branch 10 and the inlet of the array-shaped product discharge branch 11. The cathode current collector plate 6 is connected to the cathode flow channel. The flow channel of the field plate 7 corresponds to a flat plate with holes. The cathode flow field plate 7 is a flat plate having serpentine flow channels, parallel flow channels, discontinuous flow channels, interdigitated flow channels, and the like.

The fuel is a liquid solution with chemical energy and can be converted into electrical energy, including solutions such as CH ₃ OH, CH ₃ CH ₂ OH, CO(NH ₂ ) ₂ , NaBH ₄ , and HCOONa.

The materials used for the anode flow field plate 1 and the cathode flow field plate 7 have the mechanical strength required by the fuel cell and the corrosion resistance to the electrolyte used, including inorganic non-metallic materials such as graphite, metal composite materials such as stainless steel, and polymethyl methacrylate. organic polymer materials such as esters.

The materials of the anode current collector plate 2 and the cathode current collector plate 6 are inorganic non-metals such as graphite or conductive materials of metals such as stainless steel.

The anode electrode 3 and the cathode electrode 5 are conductive metal materials or carbon materials coated with corresponding catalysts and have a porous structure; the exchange membrane 4 is a cation exchange membrane, an anion exchange membrane or a neutral exchange membrane;

The dendritic fuel supply branch 10 is a binary tree-like distributed flow field step by step, that is, the dendritic fuel supply branch can be divided into four branches by a 90° rotating array of one electrolyte supply flow, and the four branches further It is divided into 16 branches, and the "1-4-16" step-by-step dispersion method makes the electrolyte enter the electrode more uniform; the array-shaped product discharge branches 11 are distributed outside the electrode in a "3×3" array.

A working method of a multi-level uniform flow field fuel cell comprises the following steps:

Step S100: The fuel is evenly distributed into the electrodes:

The unreacted fuel of the fuel cell enters the anode side of the fuel cell through the fuel inlet 8, and is evenly distributed to the tree-shaped fuel supply branch 10 through the fuel distribution flow path 9 under the action of the pump power, and enters the anode electrode 3; Or passively enter the cathode electrode 5 through the cathode flow field plate 7 and the cathode current collector plate 6 in sequence;

Step S200: battery discharge reaction:

Taking the acid fuel cell as an example, the fuel undergoes an oxidation reaction on the surface of the anode electrode 3 and generates protons, loses electrons and increases its valence, and the lost electrons enter the anode side through the anode electrode 3 and the anode current collector plate 2 through the external circuit, and are in the electric field. Under the action, the protons enter the cathode side through the exchange membrane 4; the electrons reach the surface of the cathode electrode 3 through the cathode current collector plate 6 through the external circuit, and the oxidant and protons undergo a reduction reaction on the anode surface to obtain electrons to reduce the valence, thereby realizing a discharge reaction of the battery;

Step S300: The product flows out of the battery downstream:

After the fuel reaction is completed, the fuel flowing in from the outlet of each dendritic fuel supply branch 10 passes through the anode electrode 3 and flows out from the inlet of the array-like product discharge branch 11, and further the electrolyte has an array-like product discharge branch 11 to converge to the product. The recovery flow path 12 is discharged through the product outlet 13 .

Compared with the prior art, the present invention adopts a novel binary tree-like dispersed longitudinal inflow field to ensure that the electrolyte can enter the electrode surface uniformly, improve the reaction degree of the electrolyte, and further improve the battery efficiency; at the same time, the present invention adopts and inflow The array combined with the flow field distributes the longitudinal outflow flow field, ensuring that the electrolyte can flow out of the electrode downstream after the reaction is completed, ensuring that the fuel on the electrode side is always uniform and high in concentration, and avoiding the mixing of fuel products.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that: Modifications or equivalent substitutions are made to the specific embodiments, and any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention shall all be included in the scope of the present claims.

Claims (10)

1. A multi-level uniform flow field fuel cell, characterized in that: comprising an anode flow field plate (1), an anode current collector plate (2), an anode electrode (3), an exchange membrane (4) arranged on a fuel cell body ), cathode electrode (5), cathode current collector plate (6) and cathode flow field plate (7); The anode current collector plate (2) is connected to the anode flow field plate (1) and the anode electrode (3), the anode electrode (3) and the cathode electrode (5) are separated by an exchange membrane (4), and the cathode current collector plate (6) connected with the cathode electrode (5) and the cathode flow field plate (7); The anode flow field plate (1) is provided with a fuel inlet (8), a fuel distribution flow path (9), a tree-shaped fuel supply branch (10), an array-shaped product discharge branch (11), and a product recovery flow path (12). ) and the flow field plate of the product outlet (13), wherein the dendritic fuel supply branch (10) is expanded from the fuel distribution flow path (9) through the step-by-step dispersed dendritic flow field, and the array-shaped product discharge branch (11) Evenly distributed and connected to the product recovery flow path (12); The fuel inlet (8) is an inlet connecting the fuel distribution flow path (9) with the outside of the fuel cell, the tree-shaped fuel supply branch (10) inlet is connected with the fuel distribution flow path (9), and the tree-shaped fuel supply branch (10) The outlet is connected to the anode electrode (3) through the anode current collector plate (2), the inlet of the array-shaped product discharge branch (11) is connected to the anode electrode (3) through the anode current collector plate (2), and the array-shaped product discharge branch (11) is connected to the anode electrode (3). 11) The outlet is connected to the product recovery flow path (12), the tree-shaped fuel supply branch (10) and the array-shaped product discharge branch (11) are pipelines located in the anode flow field plate (1) that are interlaced and disconnected from each other, The product outlet (13) is an outlet connecting the product recovery flow path (12) with the outside of the fuel cell; The anode current collector plate (2) is a flat plate with an array of distribution holes, and the holes in the anode current collector plate (2) are communicated with the outlet of the tree-shaped fuel supply branch (10) and the inlet of the array-shaped product discharge branch (11). The current collecting plate (6) is a flat plate with holes corresponding to the flow channels of the cathode flow field plate (7), and the cathode flow field plate (7) is a flat plate with flow channels. 2. The multistage uniform flow field fuel cell according to claim 1, wherein the product recovery flow path (12) is longitudinally arranged in the anode flow field plate (1), and the product outlet (13) is located in the anode flow field plate (1). On the top of the field plate (1), the fuel inlet (8) is located on the side wall of the anode flow field plate (1). 3. The multi-stage uniform flow field fuel cell according to claim 2, characterized in that: the outlets of the plurality of tree-shaped fuel supply branches (10) and the inlets of the plurality of array-shaped product discharge branches (11) are equally spaced interval setting. 4. The multi-stage uniform flow field fuel cell according to claim 3, characterized in that: the tree-shaped fuel supply branch (10) is a binary tree-shaped step-by-step dispersed flow field, that is, there is one tree-shaped fuel supply branch. The electrolyte supply flow path is divided into 4 branches by a 90° rotating array, and the 4 branches are further divided into 16 branches, which are distributed in a step-by-step "1-4-16" manner. 5 . The multi-stage uniform flow field fuel cell according to claim 4 , wherein the array-shaped product discharge branches ( 11 ) are distributed outside the electrodes in a “3×3” array. 6 . 6. The multi-stage uniform flow field fuel cell according to any one of claims 1-5, wherein the materials used for the anode flow field plate (1) and the cathode flow field plate (7) are inorganic non-metallic materials , metal composite materials or organic polymer materials. 7. The multi-stage uniform flow field fuel cell according to any one of claims 1-5, wherein the anode current collector plate (2) and the cathode current collector plate (6) are made of inorganic non-metallic or metal materials conductive material. 8. The multi-stage uniform flow field fuel cell according to any one of claims 1-5, wherein the anode electrode (3) and the cathode electrode (5) are conductive materials coated with corresponding catalysts and having a porous structure Metal material or carbon material. 9 . The multistage uniform flow field fuel cell according to claim 1 , wherein the exchange membrane ( 4 ) is a cation exchange membrane, an anion exchange membrane or a neutral exchange membrane. 10 . 10. A working method of the multi-level uniform flow field fuel cell according to claim 1, characterized in that it comprises the steps of: Step S100: The fuel is evenly distributed into the electrodes: The unreacted fuel of the fuel cell enters the anode side of the fuel cell through the fuel inlet (8), and is evenly distributed to the tree-shaped fuel supply branch (10) through the fuel distribution flow path (9) under the action of the pump power, and enters the anode electrode (3). ); at the same time, the oxidant enters the cathode electrode (5) through the cathode flow field plate (7) and the cathode current collector plate (6); Step S200: battery discharge reaction: The fuel undergoes a discharge reaction on the surface of the anode electrode (3); Step S300: The product flows out of the battery downstream: After the fuel reaction is completed, the fuel flowing in from the outlet of each tree-shaped fuel supply branch (10) passes through the anode electrode (3) and flows downstream from the inlet of the array-shaped product discharge branch (11), and converges to the product recovery flow path (12). ) is discharged through the product outlet (13).

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