CN116053503A - Graphite bipolar plate, battery unit and fuel cell stack - Google Patents

Graphite bipolar plate, battery unit and fuel cell stack Download PDF

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Publication number
CN116053503A
CN116053503A CN202310237071.2A CN202310237071A CN116053503A CN 116053503 A CN116053503 A CN 116053503A CN 202310237071 A CN202310237071 A CN 202310237071A CN 116053503 A CN116053503 A CN 116053503A
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bipolar plate
graphite
graphite bipolar
flow channel
transition zone
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崔龙
孙宗华
郭轩成
何仕豪
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FAW Jiefang Automotive Co Ltd
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FAW Jiefang Automotive Co Ltd
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/02—Details
    • H01M8/0202—Collectors; Separators, e.g. bipolar separators; Interconnectors
    • H01M8/0258—Collectors; Separators, e.g. bipolar separators; Interconnectors characterised by the configuration of channels, e.g. by the flow field of the reactant or coolant
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/02—Details
    • H01M8/0202—Collectors; Separators, e.g. bipolar separators; Interconnectors
    • H01M8/0204—Non-porous and characterised by the material
    • H01M8/0213—Gas-impermeable carbon-containing materials
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/02—Details
    • H01M8/0202—Collectors; Separators, e.g. bipolar separators; Interconnectors
    • H01M8/0258—Collectors; Separators, e.g. bipolar separators; Interconnectors characterised by the configuration of channels, e.g. by the flow field of the reactant or coolant
    • H01M8/0263—Collectors; Separators, e.g. bipolar separators; Interconnectors characterised by the configuration of channels, e.g. by the flow field of the reactant or coolant having meandering or serpentine paths
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/24—Grouping of fuel cells, e.g. stacking of fuel cells
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/30—Hydrogen technology
    • Y02E60/50—Fuel cells

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  • Life Sciences & Earth Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Sustainable Development (AREA)
  • Sustainable Energy (AREA)
  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Fuel Cell (AREA)

Abstract

The invention relates to a graphite bipolar plate, a battery unit and a fuel cell stack, wherein the graphite bipolar plate comprises a flow field region, and the flow field region comprises a transition region and a reaction active region; the transition zone includes a fluid inlet transition zone and a fluid outlet transition zone; the fluid inlet transition zone and the fluid outlet transition zone are arranged at two sides of the reaction active zone; the reactive zone comprises a densified flow channel; the thickness of the graphite bipolar plate is 0.9-1.5 mm. According to the invention, by adopting the fine densified runner, the flow cross section area is increased while the runner size is reduced, the flow resistance of fluid is reduced, the graphite bipolar plate with the thickness reduced to below 1.5mm is obtained, the service life requirement is ensured, and the power density of the battery is improved.

Description

Graphite bipolar plate, battery unit and fuel cell stack
Technical Field
The invention belongs to the technical field of fuel cells, and relates to a graphite bipolar plate, in particular to a graphite bipolar plate, a cell unit and a fuel cell stack.
Background
The bipolar plates have the main function of providing transport channels for reactants (hydrogen and oxidant), separating the gas flow, conducting electricity, and removing heat and water generated by the reaction out of the fuel cell. The requirements for bipolar plates are better thermal and electrical conductivity and longer life. Meanwhile, in order to meet the requirements of the working and running conditions of the fuel cell, the bipolar plate is required to have certain strength. Bipolar plates are often referred to as the "backbone" of a fuel cell.
In addition to the need to increase the power density, performance and life of fuel cells for automotive applications, it is also desirable to reduce the thickness of bipolar plates for better storage in the limited space of an automobile. Bipolar plates typically have fuel (hydrogen, methanol, etc.) flow fields, oxidant (oxygen, air, etc.) flow fields, and cooling flow fields. Graphite has been used in fuel cells for its good chemical stability, but graphite bipolar plates are generally thicker, typically around 1.5-2 mm, due to weaker mechanical properties of the materials.
CN201910136524.6 discloses an ultrathin graphene composite flexible graphite bipolar plate and a preparation method thereof, wherein the bipolar plate comprises a flexible graphite plate and a graphene film, the graphene film is adhered to the outer surface of the flexible graphite plate to form a flexible graphite substrate plate with the graphene film on the surface, and then the ultrathin graphene composite flexible graphite bipolar plate is obtained through compression molding and a polar plate connecting process. According to the invention, the ultrathin compact graphene film is adhered to the surface of the flexible graphite plate raw material, and the high-strength ultrathin high-toughness flexible graphite plate is prepared through a die pressing process, so that the strength and the gas barrier performance of the flexible graphite plate are improved, then the oxyhydrogen plate is adhered to the bipolar plate, the thickness of the plate is reduced under the condition of ensuring the original performance, the preparation of the ultrathin flexible graphite bipolar plate is realized, the specific power density of a galvanic pile is improved, and the ultrathin flexible graphite bipolar plate has good practical value.
CN201910136764.6 discloses an ultrathin flexible graphite bipolar plate and a preparation method thereof, and relates to the technical field of fuel cells, wherein the flexible graphite bipolar plate comprises an upper flexible graphite polar plate, a lower flexible graphite polar plate and a graphene film of an intermediate layer, and the graphene film is positioned between the two flexible graphite polar plates to form a flexible graphite-based bipolar plate structure with a graphene film sandwich. According to the preparation method, the graphene film is added into the raw material of the flexible graphite plate, so that the strength and the gas resistance of the flexible graphite plate are improved, the ultrathin flexible graphite oxyhydrogen polar plate is prepared by adopting a mould pressing process, the strength of the bipolar plate is improved, the thickness of the bipolar plate is reduced under the condition of ensuring the original performance, and the preparation process of the ultrathin graphite bipolar plate disclosed by the invention has good practical value.
CN201910136543.9 discloses an ultrathin metal sheet sandwich flexible graphite bipolar plate and a preparation method thereof, and relates to the technical field of fuel cells. According to the invention, the ultrathin flexible graphite oxyhydrogen polar plate is prepared by adding the metal sheet into the polar plate flexible graphite plate raw material in a mould pressing mode, so that the strength of the bipolar plate is improved, the thickness of the bipolar plate is reduced, the ultrathin flexible graphite bipolar plate preparation process is developed, the specific power density of the galvanic pile is improved, and the bipolar plate has good practical value.
According to the technical scheme, graphene films are adhered to the original flexible graphite bipolar plates respectively, or the graphene films are used in the middle interlayer of the original flexible graphite bipolar plate base material, or the metal sheet is added in the middle of the flexible graphite base material, however, the thickness of graphite cannot be greatly reduced.
Therefore, how to reduce the thickness of the graphite bipolar plate and improve the power density of the battery while meeting the service life requirement is needed to be solved in the technical field of fuel cells.
Disclosure of Invention
In view of the problems existing in the prior art, the invention provides a graphite bipolar plate, a battery unit and a fuel cell stack.
To achieve the purpose, the invention adopts the following technical scheme:
in a first aspect, the present invention provides a graphite bipolar plate comprising a flow field region comprising a transition region and a reaction active region;
the transition zone includes a fluid inlet transition zone and a fluid outlet transition zone;
the fluid inlet transition zone and the fluid outlet transition zone are arranged at two sides of the reaction active zone;
the reactive zone comprises a densified flow channel;
the thickness of the graphite bipolar plate is 0.9 to 1.5mm, for example, 0.9mm, 1mm, 1.05mm, 1.3mm or 1.5mm, but the graphite bipolar plate is not limited to the recited values, and other values not recited in the numerical range are equally applicable.
According to the invention, by adopting the fine densified runner, the flow cross section area is increased while the runner size is reduced, the flow resistance of fluid is reduced, the graphite bipolar plate with the thickness reduced to below 1.5mm is obtained, the service life requirement is ensured, and the power density of the battery is improved.
The fine runner means that the sum of the widths of the runner and the runner ridge in the runner structure is less than 1.5mm.
Preferably, the bottom of the transition zone comprises a web.
The web preferably has a thickness of 0.15 to 0.25mm, for example, 0.15mm, 0.18mm, 0.2mm, 0.22mm or 0.25mm, but is not limited to the values recited, and other values not recited in the range of values are equally applicable.
Preferably, the transition region has a lattice structure.
Preferably, the array structure has an arrangement pitch of 5-30 mm along the long side direction of the graphite bipolar plate, for example, 5mm, 10mm, 15mm, 20mm or 30mm, but not limited to the recited values, and other non-recited values in the numerical range are equally applicable.
Preferably, the array structure has an arrangement pitch of 3 to 30mm along the short side direction of the graphite bipolar plate, for example, 3mm, 5mm, 10mm, 15mm, 20mm, 25mm or 30mm, but not limited to the recited values, and other non-recited values in the numerical range are equally applicable.
Through the lattice structure and the arrangement distance adopted by the invention, the fluid can be uniformly distributed through the transition region, so that the fluid flow in different flow channels of the reaction active region is the same, and the mechanical properties of the graphite bipolar plate are not affected.
Preferably, the basic structure of the lattice comprises a column.
Preferably, the number of the columns is 1 to 2 times the number of the fine flow channels, for example, 1 time, 1.2 times, 1.4 times, 1.6 times, 1.8 times or 2 times, but not limited to the recited values, and other non-recited values in the numerical range are equally applicable.
Preferably, the height of the column is 0.9 to 1.1 times the depth of the fine flow channel, for example, 0.9 times, 0.95 times, 1 times, 1.05 times or 1.1 times, but not limited to the recited values, and other non-recited values within the numerical range are equally applicable.
Preferably, the lateral dimension of the pillar is 0.5-3 mm, for example, 0.5mm, 1mm, 1.5mm, 2mm, 2.5mm or 3mm, but not limited to the recited values, and other non-recited values within the range of values are equally applicable.
Preferably, the shape of the fine flow channel includes any one or a combination of at least two of a straight flow channel, a serpentine flow channel, a wavy flow channel or a variable, and the combination of the structure flow channel includes a combination of a straight flow channel and a serpentine flow channel, a combination of a straight flow channel and a wavy flow channel, a combination of a serpentine flow channel and a wavy flow channel, a combination of a wavy flow channel and a variable cross-section structure flow channel, a combination of a straight flow channel, a serpentine flow channel and a wavy flow channel, a combination of a serpentine flow channel, a wavy flow channel and a variable cross-section structure flow channel, or a combination of a straight flow channel, a serpentine flow channel, a wavy flow channel and a variable cross-section structure flow channel.
Preferably, the length of the fine flow channel is 100 to 600mm, for example, 100mm, 200mm, 300mm, 400mm, 500mm or 600mm, but the present invention is not limited to the recited values, and other values not recited in the numerical range are equally applicable.
Preferably, the depth of the fine flow channel is 0.15 to 0.3mm, for example, 0.15mm, 0.2mm, 0.22mm, 0.28mm or 0.3mm, but not limited to the recited values, and other values not recited in the numerical range are equally applicable.
Preferably, the densified flow channel includes a flow channel structure and a flow channel ridge.
Preferably, the sum of the widths of the flow channel structure and the flow channel ridge is 0.9-1.2 mm, for example, 0.9mm, 0.95mm, 1mm, 1.05mm, 1.1mm or 1.2mm, but not limited to the recited values, other non-recited values within the range of values are equally applicable, and preferably 1-1.2 mm.
Preferably, the reactive zone comprises a flow channel structure and flow channel ridges arranged periodically.
Preferably, the width of the flow channel structure is 0.2-1 mm, for example, 0.2mm, 0.4mm, 0.6mm, 0.8mm or 1mm, but not limited to the recited values, and other values not recited in the numerical range are equally applicable.
Preferably, the width of the flow channel ridge is 0.2-1 mm, for example, 0.2mm, 0.4mm, 0.6mm, 0.8mm or 1mm, but not limited to the recited values, and other values not recited in the numerical range are equally applicable.
Preferably, the graphite in the graphite bipolar plate is a composite graphite material.
Preferably, the composite graphite material includes graphite, a conductive agent, and a resin.
Preferably, the graphite comprises crystalline flake graphite.
Preferably, the resin comprises a thermosetting resin and/or a thermoplastic resin.
The materials of the resin include any one or a combination of at least two of phenolic resin, polyethylene, polypropylene or polyphenylene sulfide, and typical but non-limiting combinations include a combination of phenolic resin and polyethylene, a combination of polyethylene and polypropylene, a combination of polypropylene and polyphenylene sulfide, a combination of phenolic resin, polyethylene and polypropylene, a combination of polyethylene, polypropylene and polyphenylene sulfide, or a combination of phenolic resin, polyethylene, polypropylene and polyphenylene sulfide.
The compressive strength of the graphite in the graphite bipolar plate is preferably 40 to 100MPa, and may be, for example, 40MPa, 50MPa, 60MPa, 70MPa, 80MPa, 90MPa or 100MPa, but is not limited to the values recited, and other values not recited in the numerical range are equally applicable.
Preferably, the conductivity of the graphite in the graphite bipolar plate is 150S/cm or more, for example, 150S/cm, 160S/cm, 170S/cm, 180S/cm or 200S/cm, but not limited to the recited values, and other values not recited in the numerical range are equally applicable.
Preferably, the thickness of the graphite bipolar plate is 0.9 to 1.25mm, for example, 0.9mm, 0.95mm, 1.05mm, 1.1mm, 1.15mm, 1.2mm or 1.25mm, but not limited to the recited values, other non-recited values within the numerical range are equally applicable, and preferably 0.9 to 1mm.
In a second aspect, the present invention provides a battery cell comprising a graphite bipolar plate according to the first aspect;
the battery cell also includes a membrane electrode.
In a third aspect, the present invention provides a fuel cell stack obtained from the stack of cells of the second aspect.
By the technical scheme, the invention has the following beneficial effects:
according to the invention, by adopting the fine densified runner, the flow cross section area is increased while the runner size is reduced, the flow resistance of fluid is reduced, the graphite bipolar plate with the thickness reduced to below 1.5mm is obtained, the service life requirement is ensured, and the power density of the battery is improved.
Drawings
Fig. 1 is a schematic structural view of a graphite bipolar plate provided by the present invention.
Fig. 2 is a schematic structural view of a cathode plate in a symmetrical structure of a graphite bipolar plate provided in example 1.
Fig. 3 is a schematic structural diagram of an anode plate in the symmetrical structure of the graphite bipolar plate provided in example 1.
Fig. 4 is a schematic structural view of a cooling nest structure of a graphite bipolar plate provided in example 2.
Fig. 5 is a schematic structural view of a graphite bipolar plate wave structure provided in example 3.
Wherein:
1-fluid inlet zone, 2-1 cooling inlet, 3-1 oxidant inlet, 4-1 fuel inlet, 2-2 cooling outlet, 3-2 oxidant outlet, 4-2 fuel outlet, 5-transition zone, 6-reaction active zone, 7-fluid outlet zone, 8-runner ridge, 8-1-cathode runner ridge, 8-2 cooling runner ridge, 8-3-anode runner ridge, 9-runner, 9-1-cathode runner, 9-2-cooling runner, 9-3-anode runner, 10-cathode plate, 11-anode plate.
Detailed Description
The technical scheme of the invention is further described below by the specific embodiments with reference to the accompanying drawings. The following examples are merely illustrative of the present invention and are not intended to represent or limit the scope of the invention as defined in the claims.
The invention provides a graphite bipolar plate as shown in fig. 1, which consists of a cathode plate and an anode plate, wherein the graphite bipolar plate comprises a fluid inlet area 1, a transition area 5, a reaction active area 6 and a fluid outlet area 7. The fluid inlet zone 1 is distributed with a cooling inlet 2-1, an oxidant inlet 3-1 and a fuel inlet 4-1. The fluid outlet zone 7 is distributed with a cooling outlet 2-2, an oxidant outlet 3-2 and a fuel outlet 4-2.
Example 1
The present embodiment provides a graphite bipolar plate (fig. 1), the flow field region comprising a transition region 5 and a reactive region 6; the transition zone 5 comprises a fluid inlet transition zone and a fluid outlet transition zone; the fluid inlet transition zone and the fluid outlet transition zone are disposed on either side of the reactive zone 6.
The thickness of the graphite bipolar plate is 1.55mm.
The transition zone 5 is provided with a web having a thickness of 0.25mm. The transition area is of a lattice structure, the basic structural unit is a cylinder, the diameter of the cylinder is 1.5mm, the height of the cylinder is 0.25mm, the arrangement distance along the long side direction of the graphite bipolar plate is 15mm, and the arrangement distance along the short side direction is 15mm.
The graphite bipolar plate consists of a cathode plate and an anode plate.
The cathode plate 10 (fig. 2) has a thickness of 0.75mm, and the reactive area of the cathode plate 10 includes an air flow field, a cooling flow field, and a cathode web. The air flow field is a straight flow channel with the depth of 0.25mm, the straight flow channel comprises a cathode flow channel ridge 8-1 with the width of 0.35mm and a cathode flow channel 9-1 with the width of 0.65mm, the cooling flow field is arranged on the back surface of the air flow field, the cooling flow field is a straight flow channel with the depth of 0.25mm, and the cooling flow field comprises a cooling flow channel ridge 8-2 with the width of 0.35mm and a cooling flow channel 9-2 with the width of 0.65 mm. The thickness of the cathode web was 0.25mm.
The anode plate 11 (fig. 3) has a thickness of 0.55mm and includes a hydrogen flow field and an anode web. The hydrogen flow field is a direct flow channel and has a depth of 0.25mm. The hydrogen flow field comprises an anode flow channel ridge 8-3 with the width of 0.35mm and an anode flow channel 9-3 with the width of 0.65 mm. The anode web had a thickness of 0.25mm.
And bonding the anode plate and the cathode plate to obtain the graphite bipolar plate with the thickness of 1.25 mm. The graphite in the graphite bipolar plate is a composite graphite material and comprises graphite, conductive carbon black and phenolic resin, wherein the compressive strength of the composite graphite material is 70MPa, and the conductivity of the composite graphite material is 170S/cm.
Example 2
The present embodiment provides a graphite bipolar plate (fig. 1), the flow field region comprising a transition region 5 and a reactive region 6; the transition zone 5 comprises a fluid inlet transition zone and a fluid outlet transition zone; the fluid inlet transition zone and the fluid outlet transition zone are disposed on either side of the reactive zone 6.
The thickness of the graphite bipolar plate is 1.06mm.
The transition zone 5 is provided with a web having a thickness of 0.25mm. The transition area is of a lattice structure, the basic structural unit is a cylinder, the diameter of the cylinder is 1.5mm, the height of the cylinder is 0.25mm, the arrangement distance along the long side direction of the graphite bipolar plate is 15mm, and the arrangement distance along the short side direction is 15mm.
The graphite bipolar plate consists of a cathode plate and an anode plate nested (fig. 4).
The thickness of the cathode plate 10 is 0.5mm, and the reactive area of the cathode plate 10 comprises an air flow field and a cathode web. The air flow field is a serpentine flow channel with the depth of 0.25mm, and the serpentine flow channel comprises a cathode flow channel ridge 8-1 with the width of 0.35mm and a cathode flow channel 9-1 with the width of 0.65 mm. The thickness of the cathode web was 0.25mm.
The thickness of the anode plate 11 is 0.56mm, and the anode plate comprises a hydrogen flow field, a cooling flow field and an anode web, wherein the cooling flow field is arranged on the back surface of the hydrogen flow field. The hydrogen flow field is a serpentine flow channel with the depth of 0.2mm. The hydrogen flow field comprises an anode flow channel ridge 8-3 with the width of 0.75mm and an anode flow channel 9-3 with the width of 0.25mm. The anode web had a thickness of 0.25mm. The cooling flow field is a serpentine flow channel with the depth of 0.25mm, and comprises cooling flow channel ridges 8-2 with the width of 0.75mm and cooling flow channels 9-2 with the width of 0.3mm.
And bonding the anode plate and the cathode plate to obtain the graphite bipolar plate with the thickness of 1.06mm. The graphite in the graphite bipolar plate is a composite graphite material and comprises graphite, conductive carbon black and polypropylene, wherein the compressive strength of the composite graphite material is 40MPa, and the conductivity of the composite graphite material is 150S/cm.
Example 3
The present embodiment provides a graphite bipolar plate (fig. 1), the flow field region comprising a transition region 5 and a reactive region 6; the transition zone 5 comprises a fluid inlet transition zone and a fluid outlet transition zone; the fluid inlet transition zone and the fluid outlet transition zone are disposed on either side of the reactive zone 6.
The thickness of the graphite bipolar plate is 1mm.
The transition zone 5 is provided with a web having a thickness of 0.25mm. The transition area is of a lattice structure, the basic structural unit is a cylinder, the diameter of the cylinder is 1.5mm, the height of the cylinder is 0.25mm, the arrangement distance along the long side direction of the graphite bipolar plate is 15mm, and the arrangement distance along the short side direction is 15mm.
The graphite bipolar plate consists of a cathode plate and an anode plate nested (fig. 5).
The thickness of the cathode plate 10 is 0.25mm, and the reactive area of the cathode plate 10 comprises an air flow field and a cathode web. The air flow field is a wave flow channel with the depth of 0.25mm, and the wave flow channel comprises a cathode flow channel ridge 8-1 with the width of 0.35mm and a cathode flow channel 9-1 with the width of 0.65 mm. The thickness of the cathode web was 0.25mm.
The anode plate 11 has a thickness of 0.56mm and includes a hydrogen flow field and an anode web. The hydrogen flow field is a wave flow channel with the depth of 0.25mm. The hydrogen flow field comprises an anode flow channel ridge 8-3 with the width of 0.35mm and an anode flow channel 9-3 with the width of 0.65 mm. The anode web had a thickness of 0.25mm.
The cooling flow field is a wave flow channel with the depth of 0.5mm, and comprises cooling flow channel ridges 8-2 with the width of 0.35mm and cooling flow channels 9-2 with the width of 0.65 mm.
And bonding the anode plate and the cathode plate to obtain the graphite bipolar plate with the thickness of 1mm. The graphite in the graphite bipolar plate is a composite graphite material and comprises graphite, graphene and polyethylene, the compressive strength of the composite graphite material is 100MPa, and the conductivity of the composite graphite material is 200S/cm.
Example 4
The present example provides a graphite bipolar plate, which is different from example 1 in that the arrangement pitch of the lattice structure in the transition region along the long side direction of the graphite bipolar plate is 2mm, and the arrangement pitch in the short side direction is 2mm.
Example 5
The present example provides a graphite bipolar plate, which is different from example 1 in that the arrangement pitch of the lattice structure in the transition region along the long side direction of the graphite bipolar plate is 35mm, and the arrangement pitch in the short side direction is 35mm.
Example 6
This example provides a graphite bipolar plate differing from example 1 in that the sum of the widths of the flow channel structures and flow channel ridges on the cathode and anode plates is 1.5mm.
Example 7
This example provides a graphite bipolar plate, which differs from example 1 in that the graphite is flexible.
Comparative example 1
This comparative example provides a conventional graphite bipolar plate differing from example 1 in that the sum of the channel structures of the cathode and anode plates and the width of the channel ridges is 2mm, and the thickness of the bipolar plate is 2mm.
The graphite bipolar plates were combined with membrane electrodes and stacked to obtain a fuel cell stack, and the structure was tested as shown in table 1.
Test conditions: assembling the bipolar plate and the membrane electrode into a fuel cell assembly, and obtaining electrochemical performance through an electrochemical workstation test, wherein the working pressure is 2.7bar for an anode and 2.5bar for a cathode; humidity 100%, rated current 2A/cm 2 。
TABLE 1
Test number Mechanical strength Power density of
Example 1 45MPa 3.65kW/L
Example 2 80MPa 4.72kW/L
Example 3 95MPa 4.81kW/L
Example 4 45MPa 3.57kW/L
Example 5 45MPa 3.22kW/L
Example 6 45MPa 3.46kW/L
Example 7 45MPa 3.54kW/L
Comparative example 1 40MPa 2.63kW/L
From table 1 the following conclusions are drawn:
(1) As can be seen from the comparison of examples 1-3 and comparative example 1, the invention reduces the flow channel size, increases the flow cross section area, reduces the flow resistance of the fluid, and obtains the graphite bipolar plate with the thickness reduced to below 1.5mm by adopting the fine densified flow channel, and ensures the mechanical strength of the plate and improves the power density of the battery while meeting the service life requirement.
(2) As is clear from comparison of examples 4 and 5 with example 1, when the arrangement pitch in the lattice structure is not within the preferred range provided by the present invention, the mechanical strength and power density reduction of the resulting graphite bipolar plate cannot be satisfied when the thickness of the bipolar plate is ultra-thin due to the influence of the flow rate and uniformity of the fluid and the influence of the stress of the graphite bipolar plate.
(3) As is clear from a comparison between example 6 and example 1, when the sum of the widths of the fine flow channels is not within the preferable range of 0.9 to 1.2mm of the present invention, the influence of the fluid resistance cannot be solved when the flow channel thickness is reduced, and thus the resulting graphite bipolar plate cannot satisfy the reduction of the mechanical strength and the power density of the plate when the thickness is ultra-thin.
(7) As can be seen from a comparison of example 7 and example 1, the composite graphite material in the graphite bipolar plate provided by the invention is beneficial to obtaining the graphite bipolar plate with the thickness reduced to below 1.5mm, ensures the mechanical strength of the plate, improves the power density of the battery, and breaks through the limitation of adopting flexible graphite to reduce the thickness in the traditional technology.
In summary, the graphite bipolar plate with the thickness reduced to below 1.5mm is obtained, the service life requirement is met, the mechanical strength of the plate is ensured, and the power density of the battery is improved.
The detailed structural features of the present invention are described in the above embodiments, but the present invention is not limited to the above detailed structural features, that is, it does not mean that the present invention must be implemented depending on the above detailed structural features. It should be apparent to those skilled in the art that any modifications of the present invention, equivalent substitutions of selected components of the present invention, addition of auxiliary components, selection of specific modes, etc., are within the scope of the present invention and the scope of the disclosure.

Claims (10)

1. A graphite bipolar plate, wherein the graphite bipolar plate comprises a flow field region comprising a transition region and a reaction active region;
the transition zone includes a fluid inlet transition zone and a fluid outlet transition zone;
the fluid inlet transition zone and the fluid outlet transition zone are arranged at two sides of the reaction active zone;
the reactive zone comprises a densified flow channel;
the thickness of the graphite bipolar plate is 0.9-1.5 mm.
2. The graphite bipolar plate of claim 1 wherein the bottom of said transition zone comprises a web;
preferably, the web has a thickness of 0.15 to 0.25mm.
3. The graphite bipolar plate of claim 1 or 2, wherein the transition region is of lattice structure;
preferably, the array spacing of the lattice structure along the long side direction of the graphite bipolar plate is 5-30 mm;
preferably, the array pitch of the lattice structure along the short side direction of the graphite bipolar plate is 3-30 mm;
preferably, the basic structure of the lattice comprises a column;
preferably, the number of the columnar shapes is 1-2 times of the number of the fine flow channels;
preferably, the height of the columnar shape is 0.9-1.1 times of the depth of the fine runner;
preferably, the lateral dimension of the pillar is 0.5-3 mm.
4. The graphite bipolar plate of any of claims 1-3 wherein the shape of said densified flow channels comprises any one or a combination of at least two of straight flow channels, serpentine flow channels, wavy flow channels, or variable cross-section structured flow channels;
preferably, the length of the fine runner is 100-600 mm;
preferably, the depth of the fine flow channel is 0.15-0.3 mm.
5. The graphite bipolar plate of any of claims 1-4 wherein said densified flow channels comprise a flow channel structure and flow channel ridges;
preferably, the sum of the widths of the flow channel structure and the flow channel ridge is 0.9-1.2 mm, preferably 1-1.2 mm;
preferably, the reaction active region comprises a flow channel structure and flow channel ridges which are arranged periodically;
preferably, the width of the flow channel structure is 0.2-1 mm;
preferably, the width of the flow channel ridge is 0.2-1 mm.
6. The graphite bipolar plate of any one of claims 1-5 wherein the graphite in said graphite bipolar plate is a composite graphite material;
preferably, the composite graphite material comprises graphite, a conductive agent and a resin;
preferably, the graphite comprises flake graphite;
preferably, the resin comprises a thermosetting resin and/or a thermoplastic resin.
7. The graphite bipolar plate of any one of claims 1-6 wherein the compressive strength of graphite in said graphite bipolar plate is 40-100 MPa;
preferably, the conductivity of graphite in the graphite bipolar plate is 150S/cm or more.
8. The graphite bipolar plate according to any of claims 1-7, wherein the thickness of the graphite bipolar plate is 0.9-1.25 mm, preferably 0.9-1 mm.
9. A battery cell comprising a graphite bipolar plate according to any one of claims 1-8;
the battery cell also includes a membrane electrode.
10. A fuel cell stack, characterized in that the fuel cell stack is obtained from a stack of cells according to claim 9.
CN202310237071.2A 2023-03-13 2023-03-13 Graphite bipolar plate, battery unit and fuel cell stack Pending CN116053503A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202310237071.2A CN116053503A (en) 2023-03-13 2023-03-13 Graphite bipolar plate, battery unit and fuel cell stack

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202310237071.2A CN116053503A (en) 2023-03-13 2023-03-13 Graphite bipolar plate, battery unit and fuel cell stack

Publications (1)

Publication Number Publication Date
CN116053503A true CN116053503A (en) 2023-05-02

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Family Applications (1)

Application Number Title Priority Date Filing Date
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Country Status (1)

Country Link
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