CN2879440Y

CN2879440Y - Proton exchanging film fuel cell pile

Info

Publication number: CN2879440Y
Application number: CNU2006200696409U
Authority: CN
Inventors: 乔永进; 沈建跃; 曲平; 康新
Original assignee: NANJING BONENG FUEL BATTERY CO Ltd
Current assignee: NANJING BONENG FUEL BATTERY CO Ltd
Priority date: 2006-02-27
Filing date: 2006-02-27
Publication date: 2007-03-14
Anticipated expiration: 2016-02-27

Abstract

The present utility model discloses a proton exchanging film fuel cell pile. The current collector of the fuel cell pile includes a metal flat plate and a current educe terminal. A gas flow plate is disposed with a concave chamber, a through hole on the bottom, a gas passage corresponding to the reacted gas through hole of the single electrode plate on the edge. The metal plate of the current collector is disposed in the concave chamber and contacted with the current collection area of the single electrode, the current educe terminal pass through the through hole and extends to the outside of the gas flow plate. The contact part of the gas flow plate and the single electrode plate isolates the current collector with the reacted gas, and prevents the phenomena that the moisture in the reacted gas will rust the current collector and pollutes the reacted gas. An elastic gasket is disposed between the metal flat plate and the bottom of the concave chamber of the gas flow plate, and the pressure from the end plate can be distributed uniformly to the current collector and the single electrode plate, thereby the contact resistant between them is made minimum.

Description

Proton exchange membrane fuel cell stack

One, the technical field

The utility model relates to a fuel cell stack, specific proton exchange membrane fuel cell stack that says so.

Second, background Art

A pem fuel cell stack is a device that generates electrical energy by the electrochemical reaction of a fuel and an oxidant. The core component of the device is a Membrane Electrode (MEA), which is composed of two porous gas diffusion layers and a proton exchange Membrane sandwiched therebetween. An electrochemical catalyst is attached to the interface of the proton exchange membrane and a gas diffusion layer (e.g., carbon paper).

Another important component of a pem fuel cell stack is the flow-guide plates. The anode and cathode reactions respectively occur at two sides simultaneously, which is called bipolar plate. One side of the plate, which is adjacent to the current collector, and the other side of the plate, which is attached to the membrane electrode, where the reaction occurs on one side only, is referred to as a monopolar plate bipolar plate or a monopolar plate, which contains channels for the flow of a gas (e.g., hydrogen or air) and channels for the flow of a coolant (e.g., air or water).

A membrane electrode is clamped between twoflow guide polar plates to form a basic unit, namely a single cell, in a fuel cell stack, a plurality of single cells are assembled into a single cell group in a series connection mode, wherein the flow guide polar plates on the outermost sides of two ends of the single cell group are unipolar plates, and the other flow guide polar plates positioned in the middle are bipolar plates. The voltage which can be provided by the single cell in the reaction is lower than 1.0V, and the output voltage of the fuel cell stack is the sum of the voltages of all membrane electrodes in the fuel cell stack. The structure of a conventional fuel cell stack is shown in fig. 1, in which a current collector, a gas collector plate, and an end plate are respectively and sequentially provided at both ends of a cell stack, a connecting rod penetrates the end plates at both ends and clamps the end plates by nuts, and the end plates are provided with an inlet and an outlet through which reaction gases (fuel and oxidant) flow into and out of the cell stack.

When fuel (such as hydrogen) enters the flow guide grooves of the bipolar plate or the unipolar plate from the fuel inlet of the fuel cell stack, the fuel penetrates through a gas diffusion layer (such as carbon paper) to reach the surface of the catalyst. Under the action of the catalyst, hydrogen gas is electrochemically reacted, and hydrogen atoms lose electrons to become positive ions (protons). The electrons reach the electrical appliance through a porous gas diffusion layer (such as carbon paper) and a conductive bipolar plate/unipolar plate, and then reach the catalyst surface on the other side of the membrane electrode through the conductive bipolar plate/unipolar plate and the gas diffusion layer (such as carbon paper). Under the action of the catalyst, the electrons electrochemically react with an oxidant (such as oxygen) that reaches the surface of the catalyst through a gas diffusion layer (such as carbon paper) and protons that reach the surface of the catalyst through a proton exchange membrane to generate reaction products. The electrochemical reaction that occurs in a hydrogen fuel cell can be represented by the following reaction equation:

and (3) anode reaction:

and (3) cathode reaction:

in the existing fuel cell stack, the current collectors are all located inside the gas collecting plates. During the operation of the fuel cell stack, firstly, reactant gases including fuel (such as hydrogen) and oxidant (such as air) are humidified, then sequentially pass through a gas collector plate and a current collector, and then enter the flow guide holes of the unipolar plate and the bipolar plate to reach a membrane electrode to participate in reaction; and part of unreacted fuel and oxidant leave the flow guide holes of the bipolar plate and the unipolar plate, pass through the current collector and then leave the fuel cell stack after passing through the gas collector plate. Because the current collector is made of metal materials, the humidified fuel and the oxidant can be contacted with the current collector for a long time to cause the current collector to be corroded, and metal ions generated by corrosion can pollute reaction gas and reach the membrane electrode along with the reaction gas to directly influence the reaction performance of the membrane electrode. In addition, because of the potential difference between different materials, the contact resistance between the unipolar plate and the current collector in contact therewith is higher than the resistance of the material itself, and is very sensitive to the contact pressure, and the flatter the contact surface, the more uniform the contact pressure, and the lower the contact resistance, which is beneficial to the output of currentin the fuel cell stack. The unipolar plate and the current collector are required to be in good contact, but the conventional fuel cell stack achieves the purpose of pressing the end plate to fix the whole fuel cell stack by tightening nuts on the connecting rods, and the tightness degree of each part on the cross section of the fuel cell stack is inconsistent due to different tightness degrees of the nuts on each connecting rod and different temperatures of each part in the working process of the fuel cell stack, so that the unipolar plate and the current collector are in non-uniform contact, the contact resistance between the unipolar plate and the current collector is increased, and the output of current is influenced.

Third, the invention

1. The purpose of the invention is as follows: the utility model aims at providing a make reactant gas not contact with the current collector, avoid reactant gas contaminated proton exchange membrane fuel cell pile, another purpose of the utility model is to make the contact between water conservancy diversion polar plate and the current collector more even among the fuel cell pile, reduce contact resistance between the two.

2. The technical scheme is as follows: in order to realize the utility model discloses a first purpose, a proton exchange membrane fuel cell stack, it includes monoblock group, current collector, gaseous current collector, end plate, connecting rod and nut, the monoblock group is including the unipolar plate that is located its both ends, stacks gradually in the outside of unipolar plate and sets up current collector, gaseous current collector and end plate, and the connecting rod passes the through-hole on the end plate of both sides to through the nut fastening each part on the connecting rod of screwing, the unipolar plate is including the collecting area that is located surface intermediate position to and be located the reaction gas through-hole around the collecting area, characterized by: the current collector comprises a metal flat plate and a current leading-out terminal positioned on the metal flat plate, a cavity is arranged on one surface of the gas collector plate, which is opposite to the current collector, a through hole is arranged at the bottom of the cavity, a gas channel corresponding to the reaction gas through hole on the unipolar plate is also arranged on the edge of the gas collector plate, the metal flat plate of the current collector is arranged in the cavity and clings to the collector area of the unipolar plate, the current leading-out terminal penetrates through the through hole to extend out of the gas collector plate, and the current collector and the reaction gas are isolated from each other by the contact part of the gas collector plate and the unipolar plate.

The gas collecting plate is provided with a cavity on one side opposite to the current collector, the cavity has a volume capable of accommodating a metal flat plate on the current collector, one side surface of the metal flat plate is tightly contacted with the current collecting area of the unipolar plate, and a through hole at the bottom of the cavity enables a current leading-out terminal to extend out of the gas collecting plate and extend out of the fuel cell stack through an opening on the end plate so as to lead out the current collected from the single cell group. The structure has the advantages that different reaction gases sequentially flow into or out of the fuel cell stack through the respective gas channels on the gas collector plate, the current collector is placed in the cavity of the gas collector plate, the current collector is only contacted with the collector region of the unipolar plate, the cavity of the gas collector plate and the plane around the gas channels are directly and tightly attached to the unipolar plate, the flow channels of the reaction gases are sealed, and the current collector and the reaction gases are isolated from each other, so that the reaction gases are not contacted with each other.

In order to realize the second purpose of the utility model, an elastic gasket is arranged between the metal flat plate of the current collector and the bottom wall of the cavity of the gas collector plate, and a terminal through hole for the current leading-out terminal to pass is arranged on the elastic gasket. This allows the pressure from the end plates to be evenly distributed by the resilient gasket to the current collector and unipolar plates, thereby minimizing contact resistance between the two.

3. Has the advantages that: the utility model has the advantages of it is following: (1) the current collector is arranged in the cavity of the gas collector plate, so that the current collector is only contacted with the collector region of the unipolar plate, the cavity of the gas collector plate and the plane around the gas channel are directly and tightly attached to the unipolar plate, and the current collector and the reaction gas are isolated from each other and are not contacted, thereby avoiding the phenomenon that the water in the reaction gas corrodes the current collector and the metal ions generated by the corrosion pollute the reaction gas; (2) by providing the resilient gasket, the pressure from the end plate is evenly distributed by the resilient gasket to the current collector and the unipolar plate, thereby minimizing contact resistance therebetween.

Description of the drawings

FIG. 1 is a schematic diagram of a PEM fuel cell stack;

FIG. 2 is an exploded view of a single plate, current collector, gas collector and end plate of the present invention;

fig. 3 is a schematic illustration of the connection of a unipolar plate to a current collector;

fig. 4 is a side sectional view showing a structural state of a current collector, a gas collecting plate, and an end plate.

Fifth, detailed description of the invention

The invention is further illustrated by the following figures and examples: as shown in fig. 1-4, a proton exchange membrane fuel cell stack according to the present invention comprises a single cell set 1, a current collector 2, a gas collector plate 3, an end plate 4, a connecting rod 5 and a nut 6, wherein the single cell set 1 comprises a single-pole plate 7 at two ends thereof, the current collector 2, the gas collector plate 3 and the end plate 4 are sequentially stacked outside the single-pole plate 7, the connecting rod 5 passes through the through holes on the end plates 4 at two sides and is fastened by screwing the nut 6 on the connecting rod, one side of the single-pole plate 7 contacting with the current collector comprises a collector area 71 at a middle position and a reaction gas through hole 72 around the collector area 71, the current collector 2 comprises a metal plate 21 and a current leading-out terminal 22 on the metal plate 21, one side of the gas collector plate 3 opposite to the current collector 2 is provided with a cavity 31, the cavity 31 is provided at the bottom with a through hole 32, and at the edge of the gas collecting plate 3, a gas channel 33 is provided, which corresponds to the reaction gas through hole 72 of the unipolar plate 7, and includes a fuel supply pipe 33a and an oxidant supply pipe 33 b. When the fuel cell stack is assembled, the gas channels 33 of the gas collecting plate 3 are overlapped with the reaction gas passing holes 72 of the unipolar plate 7 so that the reaction gas can be introduced and discharged. The gas collector plate 3 is made of a gas-impermeable, chemically stable and electrically non-conductive material, such as plastic, nylon or glass fibre. The metal plate 21 of the current collector 2 is arranged in the cavity 31 and is tightly attached to the collector region 71 of the unipolar plate, the current leading-out terminal 22 passes through the through hole 32 and extends out of the gas collector plate, and the part of the gas collector plate 3, which is in contact with the unipolar plate 7, isolates the current collector 2 and the reaction gas from each other. An elastic gasket 8 is arranged between the metal flat plate 21 of the current collector 2 and the bottom wall of the gas collecting plate cavity 31, and a terminal through hole 81 for the current leading-out terminal 22 to pass through is arranged on the elastic gasket 8. The thickness of the resilient gasket 8 is somewhat greater than the distance between the current collector 2 and the bottom wall of the cavity to ensure a good contact between the compressed unipolar plate 7 and the current collector 2. By providing the elastic gasket 8, the pressure from the end plate 4 can be uniformly distributed to the current collector 2 and the unipolar plate 7 by the elastic gasket 8, thereby minimizing the contact resistance therebetween.

Claims

1. The utility model provides a proton exchange membrane fuel cell stack, it includes monoblock (1), current collector (2), gas current collector plate (3), end plate (4), connecting rod (5) and nut (6), monoblock (1) is including unipolar plate (7) that are located its both ends, stacks gradually in the outside of unipolar plate (7) and sets up current collector (2), gas current collector plate (3) and end plate (4), and connecting rod (5) pass the through-hole on both sides end plate (4) to through nut (6) fastening parts on the connecting rodof screwing, one side that unipolar plate (7) and current collector contact is including collecting zone (71) that are located the intermediate position to and be located reactive gas through-hole (72) around collecting zone (71), characterized by: the current collector (2) comprises a metal flat plate (21) and a current leading-out terminal (22) located on the metal flat plate (21), one surface, opposite to the current collector (2), of the gas collector plate (3) is provided with a cavity (31), the bottom of the cavity (31) is provided with a through hole (32), the edge of the gas collector plate (3) is further provided with a gas channel (33) corresponding to a reaction gas through hole (72) in the unipolar plate (7), the metal flat plate (21) of the current collector (2) is arranged in the cavity (31) and clings to a collector area (71) of the unipolar plate, the current leading-out terminal (22) penetrates through the through hole (32) to extend out of the gas collector plate, and the current collector (2) and the reaction gas are isolated from each other by the part, in contact with the unipolar plate (7), of the gas collector plate (.

2. A proton exchange membrane fuel cell stack as claimed in claim 1, wherein: an elastic gasket (8) is arranged between the metal flat plate (21) of the current collector (2) and the bottom wall of the gas collecting plate cavity (31), and a terminal through hole (81) for the current leading-out terminal (22) to pass through is arranged on the elastic gasket (8).