TWI876235B - Battery cell - Google Patents

Abstract

A battery cell including a membrane electrode assembly, a cathode bipolar plate and an anode bipolar plate. The cathode bipolar plate is stacked on a side of the membrane electrode assembly. The anode bipolar plate includes a metal layer and a thermally conductive layer. The metal layer is stacked on a side of the membrane electrode assembly located away from the cathode bipolar plate. The metal layer includes a bottom surface, a top surface, a first side surface and a second side surface. The bottom surface faces the membrane electrode assembly. The thermally conductive layer includes a first cover layer and two second cover layers. The first cover layer covers the top surface of the metal layer. Two second cover layers at least partially cover the first side surface and the second side surface of the metal layer, respectively.

Description

Battery Cell

The present invention relates to a battery cell, and more particularly to a battery cell having an anode bipolar plate comprising a heat conductive layer.

Generally speaking, a fuel cell includes an anode bipolar plate, a membrane electrode assembly, and a cathode bipolar plate stacked in sequence in a vertical direction. In order to dissipate the heat generated during the operation of the fuel cell, a plurality of heat dissipation openings are usually opened on the side of the cathode bipolar plate away from the membrane electrode assembly so that cold air can pass through these heat dissipation openings and take away the heat accumulated in the fuel cell.

However, since the heat dissipation openings are located on the side of the cathode bipolar plate away from the membrane electrode assembly, the cold air passing through these heat dissipation openings cannot effectively remove the heat accumulated on the side of the fuel cell. As a result, the heat generated by the fuel cell cannot be effectively transferred horizontally and there may be a risk of local overheating.

The present invention provides a battery unit which can achieve a uniform temperature effect in a horizontal direction and prevent local overheating.

The battery unit disclosed in one embodiment of the present invention includes a membrane electrode assembly, a cathode bipolar plate and an anode bipolar plate. The cathode bipolar plate is stacked on one side of the membrane electrode assembly. The anode bipolar plate includes a metal layer and a heat conductive layer. The metal layer is stacked on one side of the membrane electrode assembly away from the cathode bipolar plate. The metal layer has a bottom surface, a top surface, a first side surface and a second side surface. The bottom surface and the top surface are opposite to each other. The first side surface and the second side surface are opposite to each other. The first side surface and the second side surface are connected to the bottom surface and the top surface and are between the bottom surface and the top surface. The bottom surface faces the membrane electrode assembly. The heat conductive layer includes a first covering layer and two second covering layers. The first covering layer covers the top surface of the metal layer. The two second covering layers protrude from two opposite sides of the first covering layer. The two second covering layers at least partially cover the first side surface and the second side surface of the metal layer.

According to the battery cell disclosed in the above embodiment, the first covering layer of the heat conductive layer covers the top surface of the metal layer, and the second covering layer of the heat conductive layer at least partially covers the first side surface and the second side surface of the metal layer. Therefore, the heat conductive layer can effectively transfer heat between the top surface, the first side surface and the second side surface of the metal layer, and achieve a uniform temperature effect in the horizontal direction perpendicular to the stacking direction of the battery cell, thereby preventing the battery cell from having a local overheating problem.

In addition, since the second covering layer of the heat conductive layer at least partially covers the first side surface and the second side surface of the metal layer, when a plurality of battery cells are stacked to form a battery stack, the heat conductive layer will not be displaced relative to the metal layer and can maintain a close fit with the metal layer. In this way, the heat transfer efficiency between the heat conductive layer and the metal layer can be ensured, thereby ensuring the temperature uniformity effect provided by the heat conductive layer in the horizontal direction.

The detailed features of the embodiments of the present invention are described in detail in the following embodiments, and the contents are sufficient to enable any person with ordinary knowledge in the field to understand the technical contents of the embodiments of the present invention and implement them accordingly. Moreover, according to the contents disclosed in this specification, the scope of the patent application and the drawings, any person with ordinary knowledge in the field can easily understand the relevant purposes and effects of the present invention. The following embodiments are to further illustrate the viewpoints of the present invention, but are not to limit the scope of the present invention by any viewpoint.

Please refer to Figures 1 to 3. Figure 1 is a top view of a battery cell according to the first embodiment of the present invention. Figure 2 is a schematic cross-sectional view of the battery cell in Figure 1 along the cutting line A-A. Figure 3 is a schematic cross-sectional view of the battery cell in Figure 1 along the cutting line B-B.

In this embodiment, the battery cell 100 is, for example, a direct air-cooled fuel cell cell. In this embodiment, the battery cell 100 includes a membrane electrode assembly 110, a cathode bipolar plate 9, an anode bipolar plate 120, a first seal 10, and a second seal 11. The cathode bipolar plate 9 and the anode bipolar plate 120 are stacked on opposite sides of the membrane electrode assembly 110. In other words, the membrane electrode assembly 110, the cathode bipolar plate 9, and the anode bipolar plate 120 are stacked along a stacking direction S.

In this embodiment, the membrane electrode assembly 110 includes an anode side structure 111, a cathode side structure 112 and an ion conductive film 5. The anode side structure 111 includes an anode gas diffusion layer 3 and an anode electrode layer 4. The cathode side structure 112 includes a cathode gas diffusion layer 7 and a cathode electrode layer 6. The anode electrode layer 4 and the cathode electrode layer 6 are respectively stacked on opposite sides of the ion conductive film 5. The anode gas diffusion layer 3 is stacked on the anode electrode layer 4 on one side away from the ion conductive film 5. The cathode gas diffusion layer 7 is stacked on the cathode electrode layer 6 on one side away from the ion conductive film 5.

The cathode bipolar plate 9 is stacked on a side of the cathode gas diffusion layer 7 away from the cathode electrode layer 6. The side of the cathode bipolar plate 9 away from the cathode gas diffusion layer 7 has a plurality of heat dissipation channels 12. In addition, the side of the cathode bipolar plate 9 close to the cathode gas diffusion layer 7 has a plurality of cathode reaction channels 8.

The anode bipolar plate 120 includes a metal layer 1 and a heat conductive layer 13. The metal layer 1 is made of metal materials such as stainless steel, aluminum, aluminum alloy, titanium or titanium alloy. The metal layer 1 is stacked on a side of the membrane electrode assembly 110 away from the cathode bipolar plate 9. Specifically, the metal layer 1 is stacked on a side of the anode gas diffusion layer 3 away from the anode electrode layer 4. The metal layer 1 has a bottom surface 121, a top surface 122, a first side surface 123, a second side surface 124, a third side surface 125, a fourth side surface 126 and an anode reaction channel 2. The bottom surface 121 faces the anode gas diffusion layer 3. The bottom surface 121 and the top surface 122 are opposite to each other. The first side surface 123 and the second side surface 124 are opposite to each other. The first side surface 123 and the second side surface 124 connect the bottom surface 121 and the top surface 122 and are between the bottom surface 121 and the top surface 122. The third side surface 125 and the fourth side surface 126 connect the first side surface 123 and the second side surface 124 and are located between the first side surface 123 and the second side surface 124. The anode reaction channel 2 is separated from the bottom surface 121, the top surface 122, the first side surface 123, the second side surface 124, the third side surface 125 and the fourth side surface 126.

In this embodiment, the thermal conductive layer 13 is, for example, electrically conductive and does not need to be impregnated with resin. In addition, the thermal conductivity of the thermal conductive layer 13 is, for example, higher than the thermal conductivity of the metal layer 1. In this embodiment, the thermal conductive layer 13 added in this embodiment is, for example, made of natural graphite or artificial graphite that is lightweight and has good electrical conductivity, thermal conductivity, and corrosion resistance. In another embodiment, the thermal conductive layer 13 is, for example, ductile, pliable, or flexible. Therefore, this embodiment is able to take into account the electrical conductivity, thermal conductivity, and corrosion resistance of the thermal conductive layer 13 without increasing the overall weight of the battery cell 100 too much and without hindering the lightweighting of the battery cell 100.

Please refer to FIG. 1 to FIG. 3 again. In this embodiment, the heat conductive layer 13 includes a first cover layer 131, two second cover layers 132 and two third cover layers 133. The first cover layer 131 covers the top surface 122 of the metal layer 1. As shown in FIG. 1 and FIG. 2, the two second cover layers 132 protrude from opposite sides of the first cover layer 131. The two second cover layers 132 at least partially cover the first side surface 123 and the second side surface 124 of the metal layer 1. Further, in this embodiment, the two second covering layers 132, for example, completely cover the first side surface 123 and the second side surface 124 of the metal layer 1. The two third covering layers 133 protrude from the opposite sides of the first covering layer 131 and are between the two second covering layers 132. As shown in FIG1 and FIG3, the two third covering layers 133 at least partially cover the third side surface 125 and the fourth side surface 126 of the metal layer 1. Further, in this embodiment, the two third covering layers 133, for example, completely cover the third side surface 125 and the fourth side surface 126 of the metal layer 1.

By covering the metal layer 1 with the heat conductive layer 13, the heat conductive layer 13 can effectively transfer heat between the top surface 122, the first side surface 123, the second side surface 124, the third side surface 125 and the fourth side surface 126 of the metal layer 1, thereby achieving a uniform temperature effect in a first horizontal direction H1 and a second horizontal direction H2 perpendicular to the stacking direction S of the battery cell 100, thereby preventing the battery cell 100 from having a local overheating problem.

By covering the metal layer 1 with the second covering layer 132 and the third covering layer 133, when a plurality of battery cells 100 are stacked, the thermal conductive layer 13 will not be displaced relative to the metal layer 1 and can maintain a close fit with the metal layer 1. In this way, the heat transfer efficiency between the thermal conductive layer 13 and the metal layer 1 can be ensured, thereby ensuring the temperature uniformity effect provided by the thermal conductive layer 13 along the first horizontal direction H1 and the second horizontal direction H2.

In addition, in the present embodiment, the thickness T1 of the metal layer 1 along the stacking direction S is, for example, less than or equal to twice the thickness T2 of the heat conductive layer 13. It should be noted that the thickness T2 of the heat conductive layer 13 is the thickness of the first cover layer 131 along the stacking direction S, the thickness of the second cover layer 132 along the first horizontal direction H1, or the thickness of the third cover layer 133 along the second horizontal direction H2. In the present embodiment, the thickness T2 of the heat conductive layer 13 is, for example, between 25 microns and 75 microns. For example, in some embodiments, the thickness T1 of the metal layer is, for example, 50 microns, and the thickness T2 of the heat conductive layer 13 is, for example, 75 microns or 25 microns. In addition, for example, the two second covering layers 132 extend beyond the first side surface 123 and the second side surface 124 by a width W1 of 0.25 mm, and the two third covering layers 133 extend beyond the third side surface 125 and the fourth side surface 126 by a width W2 of 0.25 mm.

In this embodiment, the heat conductive layer 13 is attached to the metal layer 1 by, for example, compression. In addition, before the heat conductive layer 13 is compressed onto the metal layer 1, the thickness of the heat conductive layer 13 that is not compressed may be equal to the thickness of the metal layer 1.

The first seal 10 surrounds the anode side structure 111 and is between the metal layer 1 and the ion conductive film 5. The first seal 10 has a side surface 115 facing away from the anode side structure 111. The two second covering layers 132 and the two third covering layers 133 at least partially cover the side surface 115 of the first seal 10, so that the heat conductive layer 13 is firmly attached to the metal layer 1 to ensure the temperature uniformity of the heat conductive layer 13. The second seal 11 surrounds the cathode side structure 112 and is between the cathode bipolar plate 9 and the ion conductive film 5.

Please refer to FIG. 4 , which is a cross-sectional schematic diagram of a battery stack according to a second embodiment of the present invention. The present invention also provides a battery stack 200. The battery stack 200 includes two battery cells 100 according to the first embodiment. The two battery cells 100 are stacked on each other. Specifically, the cathode bipolar plate 9 of one of the battery cells 100 is stacked on the first covering layer 131 of the heat conductive layer 13 of the other battery cell 100. By covering the metal layer 1 with the second covering layer 132, when the two battery cells 100 are stacked into a battery stack 200, the thermal conductive layer 13 will not be displaced relative to the metal layer 1 due to the squeezing of the cathode bipolar plate 9, and can maintain a close fit with the metal layer 1. In this way, the heat transfer efficiency between the thermal conductive layer 13 and the metal layer 1 can be ensured, and the temperature uniformity effect provided by the thermal conductive layer 13 along the first horizontal direction H1 can be ensured.

It should be noted that throughout the specification and drawings, the same reference numerals represent the same or similar elements.

The heat conductive layer of the present invention is not limited to comprising two second covering layers and two third covering layers. Please refer to Figures 5 to 7, Figure 5 is a top view of a battery cell according to the third embodiment of the present invention. Figure 6 is a schematic cross-sectional view of the battery cell in Figure 5 along the cutting line C-C. Figure 7 is a schematic cross-sectional view of the battery cell in Figure 5 along the cutting line D-D. The battery cell 100a of this embodiment comprises a membrane electrode assembly 110, a cathode bipolar plate 9, an anode bipolar plate 120a, a first sealing member 10 and a second sealing member 11. The difference between the battery cell 100a of this embodiment and the battery cell 100 of the first embodiment is that the heat conductive layer 13a of the anode bipolar plate 120a of this embodiment does not include the two second cover layers 132 of the first embodiment. In other words, the heat conductive layer 13a of this embodiment only includes a first cover layer 131 and two third cover layers 133.

Alternatively, please refer to Figures 8 to 10, Figure 8 is a top view of a battery cell according to a fourth embodiment of the present invention. Figure 9 is a schematic cross-sectional view of the battery cell in Figure 8 along the cutting line E-E. Figure 10 is a schematic cross-sectional view of the battery cell in Figure 8 along the cutting line F-F. The battery cell 100b of this embodiment includes a membrane electrode assembly 110, a cathode bipolar plate 9, an anode bipolar plate 120b, a first seal 10 and a second seal 11. The difference between the battery cell 100b of this embodiment and the battery cell 100 of the first embodiment is that the heat conductive layer 13b of the anode bipolar plate 120b of this embodiment does not include the two third cover layers 133 of the first embodiment. In other words, the heat conductive layer 13b of this embodiment only includes a first cover layer 131 and two second cover layers 132.

The present invention is not limited to the coverage of the second covering layer. Please refer to FIG. 11, which is a cross-sectional schematic diagram of a battery cell according to the fifth embodiment of the present invention. The battery cell 100c of this embodiment includes a membrane electrode assembly 110, a cathode bipolar plate 9, an anode bipolar plate 120c, a first sealing member 10 and a second sealing member 11. The difference between the battery cell 100c of this embodiment and the battery cell 100 of the first embodiment is only the coverage of the two second covering layers 132c of a heat conductive layer 13c of the anode bipolar plate 120c of this embodiment. Specifically, in this embodiment, the second sealing member 11 has a side surface 116c facing away from the cathode-side structure 112. The two second covering layers 132c completely cover the side surface 115 of the first sealing member 10 and the side surface 116c of the second sealing member 11.

Alternatively, please refer to FIG. 12, which is a cross-sectional schematic diagram of a battery cell according to the sixth embodiment of the present invention. The battery cell 100d of this embodiment comprises a membrane electrode assembly 110, a cathode bipolar plate 9, an anode bipolar plate 120d, a first sealing member 10 and a second sealing member 11. The difference between the battery cell 100d of this embodiment and the battery cell 100 of the first embodiment is only the coverage range of the two second covering layers 132d of a heat conductive layer 13d of the anode bipolar plate 120d of this embodiment. Specifically, in this embodiment, the two second covering layers 132d do not cover the side surface 115 of the first sealing member 10 and only partially cover the first side surface 123 and the second side surface 124 of the metal layer 1, respectively.

According to the battery cell disclosed in the above embodiment, the first covering layer of the heat conductive layer covers the top surface of the metal layer, and the second covering layer of the heat conductive layer at least partially covers the first side surface and the second side surface of the metal layer. Therefore, the heat conductive layer can effectively transfer heat between the top surface, the first side surface and the second side surface of the metal layer, and achieve a uniform temperature effect in the horizontal direction perpendicular to the stacking direction of the battery cell, thereby preventing the battery cell from having a local overheating problem.

In addition, since the second covering layer of the heat conductive layer at least partially covers the first side surface and the second side surface of the metal layer, when a plurality of battery cells are stacked to form a battery stack, the heat conductive layer will not be displaced relative to the metal layer and can maintain a close fit with the metal layer. In this way, the heat transfer efficiency between the heat conductive layer and the metal layer can be ensured, thereby ensuring the temperature uniformity effect provided by the heat conductive layer in the horizontal direction.

Specifically, according to experimental data, under the same output and temperature control temperature, compared with a comparison example in which the anode bipolar plate does not include the heat conductive layer according to the present invention, the heat conductive layer reduces the temperature difference between the two sides of the cathode bipolar plate close to and far from the cathode gas diffusion layer of the battery cell according to the present invention by about 2 degrees Celsius.

Although the present invention is disclosed as above with the aforementioned embodiments, they are not used to limit the present invention. Anyone skilled in similar techniques may make some changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of patent protection of the present invention shall be subject to the scope of the patent application attached to this specification.

100, 100a, 100b, 100c, 100d: Battery cell 110: Membrane electrode assembly 111: Anode side structure 3: Anode gas diffusion layer 4: Anode electrode layer 112: Cathode side structure 7: Cathode gas diffusion layer 6: Cathode electrode layer 5: Ion conductive membrane 9: Cathode bipolar plate 8: Cathode reaction channel 12: Heat dissipation channel 120, 120a, 120b, 120c, 120d: Anode bipolar plate 1: Metal layer 121: bottom surface 122: top surface 123: first side surface 124: second side surface 125: third side surface 126: fourth side surface 2: anode reaction channel 13, 13a, 13b, 13c, 13d: thermal conductive layer 131: first cover layer 132, 132c, 132d: second cover layer 133: third cover layer 10: first seal 115: side surface 11: second seal 116c: side surface 200: battery stack S: stacking direction H1: first horizontal direction H2: second horizontal direction T1, T2: thickness W1, W2: Width

FIG. 1 is a top view of a battery cell according to a first embodiment of the present invention. FIG. 2 is a schematic cross-sectional view of the battery cell in FIG. 1 along the cutting line A-A. FIG. 3 is a schematic cross-sectional view of the battery cell in FIG. 1 along the cutting line B-B. FIG. 4 is a schematic cross-sectional view of a battery stack according to a second embodiment of the present invention. FIG. 5 is a top view of a battery cell according to a third embodiment of the present invention. FIG. 6 is a schematic cross-sectional view of the battery cell in FIG. 5 along the cutting line C-C. FIG. 7 is a schematic cross-sectional view of the battery cell in FIG. 5 along the cutting line D-D. FIG. 8 is a top view of a battery cell according to a fourth embodiment of the present invention. FIG. 9 is a schematic cross-sectional view of the battery cell in FIG. 8 along the cutting line E-E. FIG. 10 is a schematic cross-sectional view of the battery cell in FIG. 8 along the cut line F-F. FIG. 11 is a schematic cross-sectional view of a battery cell according to the fifth embodiment of the present invention. FIG. 12 is a schematic cross-sectional view of a battery cell according to the sixth embodiment of the present invention.

100:Battery cell

110: membrane electrode assembly

111: Anode side structure

3: Anode gas diffusion layer

4: Anode electrode layer

112: Cathode side structure

7: Cathodic gas diffusion layer

6: Cathode electrode layer

5: Ion conducting membrane

9: Cathode bipolar plate

8: Cathode reaction channel

12: Heat dissipation channel

120: Anode bipolar plate

1:Metal layer

121: Bottom

122: Top

123: First side

124: Second side

2: Anode reaction channel

13: Thermal conductive layer

131: First covering layer

132: Second covering layer

10: First seal

115: Side surface

11: Second seal

S: Stacking direction

H1: First horizontal direction

T1, T2: thickness

Claims (13)

A battery cell comprises: a membrane electrode assembly; a cathode bipolar plate, which is stacked on one side of the membrane electrode assembly; and an anode bipolar plate, which comprises a metal layer and a heat conductive layer, wherein the metal layer is stacked on one side of the membrane electrode assembly away from the cathode bipolar plate, and the metal layer has a bottom surface, a top surface, a first side surface and a second side surface, wherein the bottom surface and the top surface are opposite to each other, the first side surface and the second side surface are opposite to each other, and the first side surface and the second side surface are connected to the bottom surface. The bottom surface faces the membrane electrode assembly, the thermal conductive layer comprises a first covering layer and two second covering layers, the first covering layer covers the top surface of the metal layer, the two second covering layers respectively protrude from two opposite sides of the first covering layer, and the two second covering layers respectively at least partially cover the first side surface and the second side surface of the metal layer; wherein the thermal conductivity coefficient of the thermal conductive layer is higher than the thermal conductivity coefficient of the metal layer. A battery cell as described in claim 1, wherein the metal layer further has a third side and a fourth side facing each other, the third side and the fourth side are connected to the first side and the second side and are between the first side and the second side, and the thermal conductive layer further includes two third covering layers, the two third covering layers respectively protrude from the opposite sides of the first covering layer and are between the two second covering layers, and the two third covering layers respectively at least partially cover the third side and the fourth side of the metal layer. A battery cell as described in claim 1, wherein the thermally conductive layer is made of a carbon-containing material. A battery cell as described in claim 3, wherein the thermally conductive layer is made of natural graphite or artificial graphite. A battery cell as described in claim 1, wherein the thermally conductive layer is electrically conductive. A battery cell as described in claim 1, wherein the two second covering layers completely cover the first side and the second side of the metal layer respectively. A battery cell as described in claim 6, wherein the membrane electrode assembly includes an anode side structure, a cathode side structure and an ion conductive membrane, the ion conductive membrane is between the anode side structure and the cathode side structure, the cathode bipolar plate stack is arranged on a side of the cathode side structure away from the ion conductive membrane, and the metal layer stack is arranged on a side of the anode side structure away from the ion conductive membrane. The battery cell as described in claim 7 further includes a first seal and a second seal, wherein the first seal surrounds the anode side structure and is located between the metal layer and the ion conductive film, and the second seal surrounds the cathode side structure and is located between the cathode bipolar plate and the ion conductive film. A battery cell as described in claim 8, wherein the first seal has a side surface facing away from the anode side structure, and the two second covering layers at least partially cover the side surface of the first seal. A battery cell as described in claim 9, wherein the second seal has a side surface facing away from the cathode side structure, and the two second covering layers completely cover the side surface of the first seal and the side surface of the second seal. A battery cell as described in claim 1, wherein the thickness of the metal layer is less than or equal to twice the thickness of the thermal conductive layer. A battery cell as described in claim 1, wherein the thickness of the thermal conductive layer is between 25 microns and 75 microns. A battery cell as described in claim 1, wherein the thermally conductive layer is adhered to the metal layer by press bonding.

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