CN215118953U

CN215118953U - Composite bipolar plate of fuel cell

Info

Publication number: CN215118953U
Application number: CN202120680666.1U
Authority: CN
Inventors: 甘全全; 李丽; 汪天青; 陈广明; 朱伟; 王永湛; 戴威
Original assignee: Shanghai Shenli Technology Co Ltd
Current assignee: Shanghai Shenli Technology Co Ltd
Priority date: 2021-04-02
Filing date: 2021-04-02
Publication date: 2021-12-10
Anticipated expiration: 2031-04-02

Abstract

The utility model relates to a fuel cell composite bipolar plate, which comprises a graphite plate (1) and a frame (2) arranged outside the graphite plate (1), wherein a connection strengthening part is arranged at the joint of the graphite plate (1) and the frame (2). Compared with the prior art, the utility model discloses bipolar plate has better mechanical strength and electric conductivity concurrently when satisfying the frivolous demand of bipolar plate.

Description

Composite bipolar plate of fuel cell

Technical Field

The utility model relates to a fuel cell technical field, concretely relates to fuel cell composite bipolar plate.

Background

As the fuel cell technology becomes mature, the fuel cell is used as a power generation device which has zero pollution and high efficiency and can directly convert chemical energy into electric energy, and the fuel cell is increasingly applied to the fields of communication base stations, vehicle-mounted power, distributed power supplies and the like. The bipolar plate is one of the core components of a fuel cell, and functions to distribute gas, conduct heat, and generate electricity. With the gradual increase of the volume power density requirement of the electric pile, the thinning of the bipolar plate and the membrane electrode becomes a necessary trend. The bipolar plates at present mainly include metal bipolar plates, graphite bipolar plates, and bipolar plates of a multi-layer material using two materials at the same time. The graphite bipolar plate formed by the mixed material die-casting method is considered to be the process which has the most accurate forming size and can completely meet the requirements of sealing, electric conduction and the like.

In the presently disclosed data on graphite bipolar plates, uniform materials, such as mixed condensates of graphite and resin and additives, are used for the preparation of the bipolar plates. In order to ensure the electrical and thermal conductivity of the material, the resin content in the mixture is relatively low, which results in relatively weak strength, and cannot meet the requirement of high strength of some non-conductive parts of the bipolar plate. However, as the requirement for thinning of the bipolar plate is more and more demanding, these portions with higher strength become bottlenecks that limit the graphite bipolar plate.

The prior art mainly focuses on the formula of a composite plate material or directly changes a bipolar plate substrate material to improve and balance the relationship between sealing, electric conduction and strength, for example, the carbon content in the composite conductive plate is kept at a lower level in the patent of invention CN108511764A, and the patent of invention CN110581291A directly adopts a silicon plate made of a doped conductive crystalline silicon material, but the method still cannot give consideration to the relationship between strength, electric conduction and lightness and thinness, and does not fundamentally solve the bottleneck problem of the material.

SUMMERY OF THE UTILITY MODEL

The utility model aims at providing a fuel cell composite bipolar plate has better mechanical strength and electric conductivity concurrently when satisfying the frivolous demand of bipolar plate.

The purpose of the utility model can be realized through the following technical scheme: the composite bipolar plate for fuel cell includes graphite plate and frame outside the graphite plate, and the joint between the graphite plate and the frame has connecting reinforcing part. The bipolar plate is a further subdivision of the regional function, the frame is a non-reaction region, the graphite plate is a reaction region, the frame part can use a material with higher strength, such as a non-conductive material, without considering a conductive factor, so that the thickness of the part is reduced, the thickness of the whole bipolar plate is reduced, the graphite plate is used as the reaction region under the protection of the frame, the material with higher conductivity can be adopted, the conductivity is improved, the connection strengthening part further improves the connection strength and stability of the graphite plate and the frame, and the fuel cell composite bipolar plate has better mechanical strength and conductivity while meeting the requirement of lightening and thinning of the bipolar plate.

Further, the connection reinforcing part comprises a non-planar structure arranged at the inner edge of the frame, and the shape of the outer edge of the graphite plate is matched with the non-planar structure. The non-planar structure can enhance the mechanical strength of the joint of the graphite plate and the frame.

Preferably, the non-planar structure is arranged at the bottom of the inner edge of the frame and extends towards the graphite plate. The design can improve the stability of the graphite plate on the frame while improving the connection strength of the graphite plate and the frame.

Further preferably, the cross-sectional shape of the non-planar structure includes a dovetail groove shape, a taper shape, a concave shape or a convex shape. The non-planar structure may also be a more complex raised structure to enhance the connection of the border to the graphite plate.

The thickness of the non-planar structure does not exceed the thickness of the graphite plate and the frame. In order to ensure the normal function of the graphite plate, the non-planar structure must not damage the continuity of the graphite plate, and at the same time, the non-planar structure must not damage the strength of the graphite plate, preferably, the thickness of the non-planar structure must not exceed 70% of the thickness of the graphite plate, so as to prevent the strength of the connecting part from being weakened due to the fact that the graphite plate is too thin.

The graphite plate is located in the center of the frame, two channel areas are arranged on the frame, and the two channel areas are symmetrically arranged on two sides of the graphite plate respectively.

The channel area is internally provided with a hydrogen channel, a cooling water channel and an air channel.

The hydrogen channel, the cooling water channel and the air channel are all kidney-shaped holes with the same size. The waist-shaped hole has smooth profile, the damage to the frame structure can be reduced, and the frame strength is improved.

A plurality of linear flow channels are arranged on the graphite plate in parallel.

The area of the graphite plate accounts for 55 to 75 percent of the total area of the composite bipolar plate. The area of the graphite plate cannot be too large or too small, the efficiency is reduced when the area is too small, and the overall structural strength of the composite bipolar plate is weakened when the area is too large.

The preparation method of the fuel cell composite bipolar plate comprises the steps of firstly carrying out injection molding, extrusion molding or die casting on resin powder to prepare a frame, then placing the frame into a die cavity, adding composite graphite powder into the die, further carrying out die assembly and die casting, heating and demoulding to finish the preparation of the fuel cell composite bipolar plate. The resin powder is preferably a high-strength non-conductive material.

Compared with the prior art, the utility model has the advantages of it is following:

1. the utility model discloses divide into frame and graphite cake with fuel cell composite bipolar plate, regard as non-reaction zone and reaction zone respectively to further subdivide bipolar plate's regional function, generally speaking, the gap bridge part in bipolar plate port and with flow field UNICOM is higher to the intensity requirement, in the utility model discloses because of need not consider conductive factor, make this part material intensity can improve by a wide margin, thereby reduce this part thickness, and then reduce whole bipolar plate thickness;

2. the port area of the utility model can use non-conductive material, after the galvanic pile is formed, the short-distance bridging of adjacent bipolar plates in the port due to reaction water or cooling liquid is fundamentally solved, and the external power generation loss is avoided and weakened;

3. the frame of the utility model can use non-conductive material, when the galvanic pile is assembled, the isolation between the adjacent bipolar plates can be avoided, the short circuit phenomenon can not be caused, the reliability of the galvanic pile is greatly improved, the galvanic pile has the IP67 characteristic, and the extra external packing design is not needed;

4. the utility model adopts the splicing mode, the frame can be molded in advance, and the working efficiency is effectively improved;

5. the utility model improves the connection strength between the frame and the graphite plate through the non-planar structure arrangement on the frame;

6. the utility model can reduce the overall development difficulty of the polar plate, and compared with the reaction zone, the structural shape of the frame is more complex, the utility model can separate the frame and the reaction zone through the design of the frame and the graphite plate, thereby effectively reducing the overall development difficulty of the polar plate;

7. the utility model discloses can reduce the graphite material consumption and the development degree of difficulty of reaction zone.

Drawings

Fig. 1 is a schematic structural view of a composite bipolar plate of a fuel cell according to the present invention;

FIG. 2 is a cross-sectional view of the intersection of the border and graphite sheet of example 1;

FIG. 3 is a cross-sectional view of the intersection of the border and graphite sheet of example 2;

FIG. 4 is a cross-sectional view of the intersection of the border and graphite sheet of example 3;

FIG. 5 is a cross-sectional view of the intersection of the border and graphite sheet of example 4;

in the figure: 1-graphite plate, 11-linear flow channel, 2-frame, 21-non-planar structure and 22-channel region.

Detailed Description

The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. The following examples are carried out on the premise of the technical solution of the present invention, and detailed embodiments and specific operation procedures are given, but the scope of the present invention is not limited to the following examples.

Example 1

The utility model provides a fuel cell composite bipolar plate, as shown in fig. 1-2, includes graphite plate 1 and frame 2, and the inward flange of frame 2 is equipped with the cross sectional shape and is convex type non-planar structure 21, and graphite plate 1 sets up at frame 2 inboard and the outward flange shape and the non-planar structure 21 phase-match of graphite plate 1, makes graphite plate 1 and frame 2 stably connected. A plurality of parallel linear flow channels 11 are arranged on the graphite plate 1, channel regions 22 are arranged on the frame 2, the two channel regions 22 are symmetrically arranged on the left side and the right side of the graphite plate 1, and a hydrogen channel, a cooling water channel and an air channel are arranged in the channel regions 22.

The preparation method of the fuel cell composite bipolar plate comprises the following steps:

(1) weighing 10 parts of graphite powder, 10 parts of carbon fiber and 80 parts of PPS resin according to parts by weight, uniformly mixing to obtain resin powder, weighing 70 parts of graphite powder, 20 parts of PPS resin, 5 parts of short carbon fiber and 5 parts of carbon black according to parts by weight, and uniformly mixing to obtain composite graphite powder;

(2) preparing the frame 2 from the resin powder by adopting an injection molding method, then placing the frame 2 into a mold cavity, adding the composite graphite powder into the mold, further carrying out die assembly and die casting, and completing the preparation of the fuel cell composite bipolar plate by adopting hot-pressing die casting, heating and demolding.

Example 2

A composite bipolar plate for a fuel cell, as shown in FIG. 3, comprises a graphite plate 1 and a frame 2, wherein the inner edge of the frame 2 is provided with a non-planar structure 21 having a dovetail groove-shaped cross section, and the rest of the structure is the same as that of example 1.

(1) weighing 8 parts of graphite powder, 12 parts of carbon fiber and 75 parts of PVC resin according to the parts by weight, uniformly mixing to obtain resin powder, weighing 65 parts of graphite powder, 25 parts of PVC resin and 8 parts of carbon black according to the parts by weight, and uniformly mixing to obtain composite graphite powder;

Example 3

A composite bipolar plate for fuel cell is shown in FIG. 4, and comprises a graphite plate 1 and a frame 2, wherein the inner edge of the frame 2 is provided with a non-planar structure 21 with a conical cross section, and the rest of the structure is the same as that of embodiment 1.

(1) weighing 12 parts of graphite powder, 8 parts of glass fiber and 85 parts of PP resin according to parts by weight, uniformly mixing to obtain resin powder, weighing 75 parts of expanded graphite powder, 15 parts of PP resin and 12 parts of short carbon fiber according to parts by weight, and uniformly mixing to obtain composite graphite powder;

(2) preparing the frame 2 from the resin powder by adopting an injection molding method, then placing the frame 2 into a mold cavity, adding the composite graphite powder into the mold, further carrying out die assembly and die casting, and carrying out vacuum hot-pressing die casting, heating and demolding to finish the preparation of the composite bipolar plate of the fuel cell.

Example 4

A composite bipolar plate of a fuel cell comprises a graphite plate 1 and a frame 2, as shown in figure 5, wherein the inner edge of the frame 2 is provided with a non-planar structure 21 with a concave cross section, and the rest of the structure is the same as that of the embodiment 1.

(1) weighing 10 parts of graphite powder, 10 parts of glass fiber and 80 parts of PVDF resin according to parts by weight, uniformly mixing to obtain resin powder, weighing 70 parts of graphite powder, 20 parts of PVDF resin and 10 parts of carbon black according to parts by weight, and uniformly mixing to obtain composite graphite powder;

The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. It will be readily apparent to those skilled in the art that various modifications to these embodiments may be made, and the generic principles described herein may be applied to other embodiments without the use of the inventive faculty. Therefore, the present invention is not limited to the above embodiments, and those skilled in the art should make improvements and modifications within the scope of the present invention according to the disclosure of the present invention.

Claims

1. The composite bipolar plate of the fuel cell is characterized by comprising a graphite plate (1) and a frame (2) arranged on the outer side of the graphite plate (1), wherein a connection reinforcing part is arranged at the joint of the graphite plate (1) and the frame (2).

2. The fuel cell composite bipolar plate according to claim 1, wherein the connection reinforcement comprises a non-planar structure (21) provided at the inner edge of the frame (2), and the outer edge of the graphite plate (1) is shaped to match the non-planar structure (21).

3. The fuel cell composite bipolar plate according to claim 2, wherein the non-planar structure (21) is disposed at the bottom of the inner edge of the frame (2) and extends toward the graphite plate (1).

4. The fuel cell composite bipolar plate according to claim 3, wherein the cross-sectional shape of said non-planar structure (21) comprises a dovetail groove type, a taper type, a concave type or a convex type.

5. The fuel cell composite bipolar plate according to claim 2, wherein the thickness of the non-planar structure (21) does not exceed the thickness of the graphite plate (1) and the frame (2).

6. The fuel cell composite bipolar plate according to claim 1, wherein the graphite plate (1) is located at the center of the frame (2), two channel regions (22) are provided on the frame (2), and the two channel regions (22) are respectively symmetrically provided at two sides of the graphite plate (1).

7. The fuel cell composite bipolar plate according to claim 6, wherein a hydrogen channel, a cooling water channel and an air channel are provided in the channel region (22).

8. The fuel cell composite bipolar plate of claim 7, wherein said hydrogen gas channel, cooling water channel and air channel are all kidney-shaped holes having the same size.

9. The fuel cell composite bipolar plate according to claim 1, wherein a plurality of linear flow channels (11) are arranged in parallel on the graphite plate (1).

10. The fuel cell composite bipolar plate according to claim 1, wherein the area of the graphite plate (1) accounts for 55-75% of the total area of the composite bipolar plate.