CN2862344Y

CN2862344Y - Fuel battery metal electrode with current field modification

Info

Publication number: CN2862344Y
Application number: CNU2005200350124U
Authority: CN
Inventors: 王善理
Original assignee: Individual
Current assignee: Individual
Priority date: 2005-08-04
Filing date: 2005-08-04
Publication date: 2007-01-24
Anticipated expiration: 2015-08-04

Abstract

The utility model discloses a modified metal electrode having flow field for fuel cell belonging to device for converting chemical energy into electric energy. The problems of existing graphite electrode, including low groove photo-etching efficiency of graphite, high cost, battery performance influenced by reduced conductivity of die cast graphite, etc., can be solved. The electrode is made of electrolytic copper or copper alloy, distribution ribs are added in flow field groove of the electrode, and gold layer can be plated on outer surface on demand. The flow field groove is processed via stamping to form smooth and regular electrode with precise dimensions, and guarantee precise contact between electrode and catalyst layer. Contact resistance is low due to the low resistivities of copper, silver and gold. The added ribs have no influence on guide flow. The stamping process can greatly improve production efficiency to realize batch manufacture of various specifications. The gold plating layer has high corrosion resistance, and lower cost than sputtered noble metal. The fuel cell can be widely applied to vehicle, submarine, satellite, aircraft, etc.

Description

Fuel cell metal electrode with flow field modification

The technical field is as follows: fuel cells with flow field modified metal electrodes belong to the class of devices (H01M) for direct conversion of chemical energy into electrical energy.

(II) background technology:

the fuel cell is a high-efficiency pollution-free power generation device, and directly converts chemical energy in stored fuel and oxidant into electric energy. Can be used as power supply for automobile, submarine, satellite and airship.

The main parts and principles of the fuel cell are as follows: see fig. 1, electrodes with flow field with gas flow are 1 (anode) and 7 (cathode); anode, cathode catalyst layers 3 and 5, electrolyte 4, hydrogen as fuel (entering through anode inlet 2 a), air and pure oxygen as oxidant (entering through cathode inlet 6 a), gas and water being removed through anode exhaust 2b and cathode exhaust 6 b. Hydrogen gas is subjected to electrode reaction under the action of catalyst ( ) Generating electrons (e) to the cathode through an external circuit, hydrogen ions to the anode through an electrolyte, and oxygen, hydrogen ions and electrons reacting at the cathode to generate water ) The generated water does not dilute the electrolyte, but is discharged with the reaction off-gas through the electrode.

The existing fuel cell has the following 6 types according to different electrolytes, namely ① alkaline oxyhydrogen fuel cell (AFC) ② regenerated oxyhydrogen fuel cell fuel (RFC) ③ moltencarbonate fuel cell (NCFC) ④ Proton Exchange Membrane Fuel Cell (PEMFC) ⑤ Direct Methanol Fuel Cell (DMFC) ⑥ fixed oxide fuel cell (SOFC) which has new technology, high cost, unstable part process and realization of commercialization, scientific and technical personnel of various countries develop and improve, in 1983, Canada develops a perfluorinated proton sulfonic acid membrane (Nafion), DuPont company commercializes, and simultaneously adopts platinum/carbon catalyst and realizes the integration of cathode, anode and membrane hot pressing into a 'three-in-one' main part MEA.

The electrode with flow field is a key part of fuel cell and has not been solved so far. The flow guide grooves on the flow field plate are processed on a photoetching machine by using a graphite plate, are time-consuming and labor-consuming, can be manufactured only in a laboratory and cannot be commercialized. The brade company of canada makes the bipolar plates of three models, i.e., mank500, mank513 and mank700, but cannot be mass-produced. In order to realize mass production, the U.S. department of energy subsidies the national laboratory and adopts the die casting method to prepare the bipolar plate, and the resistance of the bipolar plate is greater than that of graphite, so that the performance of the PEMFC is reduced. The energy sector developed second generation graphite molded bipolar plates with a somewhat reduced resistance value, which is still undesirable. The american home laboratory again used 68% graphite powder molded with Heteron922 vinyl ether resin for bipolar plates, which was less effective than the modified stainless steel plates. Patent WO00/1126, barlader electric, canada, proposes the use of expanded graphite rolled embossing to produce bipolar plates with flow fields, with consequent failure in matrix lock. It has been proposed to use thin metal plates for the fabrication of bipolar plates, and the first problem encountered is the stability of the electrodes under the operating conditions of the fuel cell PEMFC (i.e., oxidizing and reducing atmosphere, a certain potential of weakly acidic electrolyte), i.e., the corrosion resistance. If alloy steel electrodes are used, the contact resistance with the carbon paper in the catalyst layer is high. The technology using the modified metal plate as the electrode is highly confidential in various countries, and the problem of mass production and cost reduction has not been solved so far.

(III) the invention content:

the utility model provides a fuel cell takes flow field modified metal electrode, two following problems of current electrode are solved to ① processing guiding gutter on the electrode on the photoetching machine with graphite plate wastes time and labor with high costs, can not commercialize, ② reduces resistance with die-casting graphite plate electrode, influences fuel cell's performance.

The technical scheme is as follows:

the fuel cell modified metal electrode with flow field includes flow field plate, flow guide channel and common air and water channel, and features that the electrode has flow field plate, flow guide channel and common air and water channel

A. The electrode flow field plate is made of electrolytic copper or copper alloy material;

B. the electrode flow field plate is additionally provided with ribs made of electrolytic copper or copper alloy materials.

The ribbed flow field plate can be additionally provided with a gold plating layer on the outer layer. The copper alloy may be a copper-silver alloy.

The added ribs are distributed at all positions of the flow field in groups (the distribution of the ribs can be determined according to the capacity of the battery and the size of the flow field). Each group of ribs is arranged in a group of diversion trenches, and each corner of the flow channel needs to be provided with a group of ribs. The ribbed metal electrode with the flow field can also be made of stainless steel. The width b of each rib is 1-2 mm. The flow field plate surface diversion trench is a snake-shaped flow field arranged in a snake shape.

The utility model discloses beneficial effect:

i. the electrolytic copper used is pure copper, copper alloy (such as copper-silver alloy) and gold-plating layer, which has large conductivity and small resistance, and can make the electrode current less than 0.3A. Since copper has good workability, the use of copper as a flow field plate enables die stamping (chipping due to stamping with graphite). Typically, at least 30 ten thousand pieces of copper product can be processed per die set. Moreover, because the ribs are arranged in the diversion trench, the geometric shape (no deformation) and performance of the punched electrode product with the flow field can be ensured: the punched electrode is very flat, regular and accurate in size, and the electrode can be accurately contacted with the catalyst-destroying layer, so that the reduction of contact resistance is facilitated. Because of the optimized design of the shape, size and position of the rib, the flow of the guide flow is not obstructed while the stamping process is realized. And iv, processing by using a stamping die, realizing mass production and designing dies with various specifications. The problem of the inefficiency of grooving on the current graphite cake is solved. v. copper is more corrosion resistant than iron, and if the electrode is gold plated, the corrosion resistance is enhanced, and the performance is changed and optimized; and gold plating is cheaper than vacuum sputtering of precious metals. And vi, the metal electrode with the flow field can also be manufactured by adopting a stainless steel material after the rib is additionally arranged and is processed by stamping. The utility model is provided under the conditions of summarizing home and abroad and on the basis of feasibility splitting and testing, which solves the problems of large resistance and low efficiency; realizes good performance, low cost and mass production, and further promotes the forward development of the fuel cell.

(IV) description of the drawings:

FIG. 1 shows a schematic diagram of the main part of a fuel cell

FIG. 2 is a view from the direction of FIG. 1K (electrode flat view)

FIG. 3 is a partial enlarged view of FIG. 2I

FIG. 4 is a sectional view taken along line A-A in FIG. 3

FIG. 5 is a cross-sectional view of FIG. 3B-B

(V) specific embodiment:

referring to fig. 2, the electrode plate with the flow field of the fuel cell adopts a serpentine flow field electrode. The common channels 8 are provided around the flow field plate 9: comprises a hydrogen inlet channel 8.3, a hydrogen outlet channel 8.2, an oxygen inlet channel 8.1, an oxygen outlet channel 8.4 and a water flow channel 8.5, 8.6. Referring to fig. 2, fig. 3 and fig. 4, a flow field plate 9 of an electrode is provided with flow guide grooves 10 arranged in a serpentine shape, and general flow channels on the flow field plate are composed of 2-5 flow guide grooves, wherein 5 flow channels are selected, and the flow channels are arranged on the flow field plate 9 in a serpentine shape.

Referring to fig. 3 and 5, 5 ribs 11.1-11.5 disposed in 5 flow guiding grooves 10 at one position of the flow channel are a set of ribs 11, and each set of ribs 11 can be distributed at each position of the flow channel route with serpentine arrangement. Typically, a set of ribs 11 is provided at each corner of the serpentine shape.

Referring to fig. 3, the width b of each rib in each flow guide groove 10 is generally 1-2 mm.

The ribbed flow field cross-section depicted in fig. 5 is in the shape of a bipolar plate (which is typically used for anodes). If a unipolar plate (which is typically used for the cathode) is used, the cross-sectional shape is 1/2, and the end lines are shown by dashed lines K- -K.

The whole electrode including the snakelike flow field plate 9 and the multiple groups of additionally arranged ribs 11 are made of copper-silver alloy materials, and a gold-plated layer can be additionally arranged according to the requirements of battery capacity and the like.

Claims

1. The fuel cell modified metal electrode with flow field includes flow field plate, flow guide channel and common air and water channel, and features that the electrode has flow field plate, flow guide channel and common air and water channel

2. The modified metal electrode of claim 1 wherein the entire outer surface of the flow field electrode is plated with gold.

3. The modified metal electrode of claim 1 wherein the copper alloy is a copper-silver alloy.

4. The modified metal electrode of claim 1 wherein the additional ribs are distributed evenly across the flow field in groups, each group of ribs being disposed in a group of channels, one group of ribs being disposed at each corner of the flow channel.

5. The modified metal electrode of claim 1 wherein the width b of each rib is 1 to 2 mm.

6. The modified metal electrode as claimed in claim 1, wherein the flow field plate surface channels are serpentine flow fields arranged in a serpentine manner.