Patent Publication Number: US-2022238894-A1

Title: Fuel cell

Description:
FIELD 
     The present disclosure relates to the field of electrochemical cells, and more particularly, to a fuel cell. 
     BACKGROUND 
     Fuel cells produce electricity by reacting hydrogen with oxygen in the air, and the product of the reaction is water. Without being limited by the Carnot cycle, the efficiency may reach more than 50%. Therefore, the fuel cells are not only environmentally friendly but also energy-saving. A bipolar plate fuel cell includes a cathode plate and an anode plate. The cathode plate has cathode channels formed on a side thereof, and an oxidizing gas (e.g., oxygen) is suitable to flow in the cathode channels. The anode plate has anode channels formed on a side thereof, and a reducing gas (e.g., hydrogen) is suitable to flow in the anode channels. Cooling channels are formed between the cathode plate and the anode plate and are provided to allow the cooling liquid to flow therein. The cathode plate and the anode plate are important components of the bipolar plate fuel cell, having the functions of supporting the fuel cell, providing reaction gas, and cooling the channels. 
     The fuel cell has wide application in the fields such as automobiles, airplanes and the like, which set higher requirements on a power density of the fuel cell. In the technical routes for improving the power density of the fuel cell, it has remarkable effects to reduce the thickness of the cathode plate and the anode plate. 
     Considering the processing convenience of the conventional fuel cell, the cathode channels, the anode channels, and the cooling channels are all disposed in parallel, for example, as disclosed in German Patent DE102013208450A1. Thus, it is required to distribute three fluids in fluid distribution transition regions at the two ends of the channels, resulting a concentration of complexity of the fluid distribution transition regions. This concentration of complexity is not a significant problem in the conventional bipolar plate structures having a thickness about 1 mm. However, when the thickness is reduced to be smaller than or equal to 0.6 mm, the fluid distribution transition region will become a bottleneck for increasing the single cell scale. A single cell current of the existing fuel cells, which have thin bipolar plates (for example, with a thickness of only 0.6 mm), can hardly reach 600A, failing to meet the application requirements of ultrahigh power in the fields such as automobiles, airplanes. 
     SUMMARY 
     In view of the above, the present disclosure provides a fuel cell to reduce the complexity of a fluid distribution transition region. 
     In order to achieve the purpose, the technical solution of the present disclosure is realized as follows. 
     A fuel cell includes at least two single cells stacked adjacent to each other. A cathode plate of one of the at least two single cells is stacked adjacent to an anode plate of an adjacent single cell. The cathode plate includes a cathode plate body, the cathode plate body has a cathode channel ridge disposed thereon and protruding towards the anode plate, and the cathode channel ridge has a cathode channel formed therein. The anode plate includes an anode plate body, the anode plate body has an anode channel ridge disposed thereon and protruding towards the cathode plate, and the anode channel ridge has an anode channel formed therein. A cooling channel is formed between the cathode plate and the anode plate. The anode channel ridge and the cathode channel ridge are intersected with each other, and an included angle between the anode channel ridge and the cathode channel ridge ranges from 60° to 120°. 
     According to some embodiments of the present disclosure, the anode channel ridge is arranged perpendicular to the cathode channel ridge. 
     According to some embodiments of the present disclosure, a recess is formed at an intersection between the anode channel ridge and the cathode channel ridge, the anode channel ridge is fitted in the recess, the recess is located on a flow path of the cathode channel and is recessed towards an inside of the cathode channel, and a channel depth of the cathode channel at the recess is smaller than a channel depth of the cathode channel at a position other than the recess. 
     Furthermore, the channel depth of the cathode channel at the recess is 0.2 mm, and the channel depth of the cathode channel at a position other than the recess is 0.4 mm. 
     According to some embodiments of the present disclosure, a plurality of anode channel ridges is provided, and the plurality of anode channel ridges is arranged in parallel and spaced apart from each other; and a plurality of cathode channel ridges is provided, and the plurality of cathode channel ridges is arranged in parallel and spaced apart from each other. 
     According to some embodiments of the present disclosure, the anode channel ridge has a plurality of sub-channel ridges, each of the plurality of sub-channel ridges has a sub-channel formed therein and in communication with the anode channel, and each of the plurality of sub-channel ridges is parallel to the cathode channel ridge. 
     Further, the plurality of sub-channel ridges of one of the plurality of anode channel ridges is arranged alternately with the plurality of sub-channel ridges of an adjacent anode channel ridge. 
     Further, the plurality of sub-channel ridges is located between two adjacent cathode channel ridges. 
     Further, the plurality of sub-channel ridge is spaced apart from the cathode plate body and in communication with the cooling channel; and the plurality of cathode channel ridge is attached to the anode plate body. 
     Further, the cathode plate is an oxygen-side plate, and the anode plate is a hydrogen-side plate. 
     Compared with the related art, the fuel cell has the following advantages. 
     For the fuel cell of the present disclosure, the anode channel ridge and the cathode channel ridge are intersected with each other, which is conducive to reducing a complexity of a fluid distribution transition regions and thus is conducive to reducing the thicknesses of the cathode plate and the anode plate, thereby increasing a power density and a maximum discharge current of the fuel cell. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       The accompanying drawings, as a part of the present disclosure, are provided to facilitate the understanding of the present disclosure. The exemplary embodiments of the present disclosure together with the description thereof serve to explain the present disclosure and do not constitute limitations of the present disclosure. In the drawings: 
         FIG. 1  is a schematic diagram illustrating a cathode plate and an anode plate that are stacked; 
         FIG. 2  is a schematic diagram of a side of an anode plate facing towards the cooling channels; 
         FIG. 3  is a schematic diagram of a side of a cathode plate facing towards a membrane electrode (MEA); 
         FIG. 4  is an enlarged view of C portion in  FIG. 1 ; 
         FIG. 5  is a cross-sectional view of  FIG. 4  along A-A; 
         FIG. 6  is a cross-sectional view of  FIG. 4  along A′-A′; 
         FIG. 7  is a cross-sectional view of  FIG. 1  along B-B; 
         FIG. 8  is an enlarged view of portion D in  FIG. 6 ; and 
         FIG. 9  is a schematic layout of a cathode channel, an anode channel, and a cooling channel. 
     
    
    
     Reference Symbols 
     cathode plate  1 , cathode plate body  11 , cathode channel ridge  12 , cathode channel  121 , recess  122 , anode plate  2 , anode plate body  21 , anode channel ridge  22 , anode channel  221 , sub-channel ridge  23 , sub-channel  231 , cooling channel  3 , hydrogen inlet manifold chamber  20 , hydrogen outlet manifold chamber  30 , oxygen inlet manifold chamber  40 , oxygen outlet manifold chamber  50 , reaction region  60  and transition region  70 . 
     DESCRIPTION OF EMBODIMENTS 
     It should be noted that embodiments of the present disclosure and features of the embodiments may be combined with each other, unless they are contradictory to each other. 
     The present disclosure will be described in detail below with reference to  FIGS. 1  to  9  in conjunction with embodiments. 
     Referring to  FIG. 1  to  FIG. 3  and  FIG. 7 , a fuel cell according to an embodiment of the present disclosure includes at least two single cells that are stacked adjacent to each other. A cathode plate  1  of one single cell is stacked adjacent to an anode plate  2  of an adjacent single cell. 
     The cathode plate  1  includes a cathode plate body  11 . The cathode plate body  11  has cathode channel ridges  12  disposed thereon and protruding towards the anode plate  2 . The cathode channel ridge  12  has a cathode channel  121  formed therein, and an oxidizing gas flows in the cathode channel  121 . The oxidizing gas may be air, and the oxygen in the air participates in an electrochemical reaction in the fuel cell. 
     The anode plate  2  includes an anode plate body  21 . The anode plate body  21  has anode channel ridges  22  disposed thereon and protruding towards the cathode plate  1 . The anode channel ridge  22  has an anode channel  221  formed therein, and a reducing gas flows in the anode channel  221 . The reducing gas may be hydrogen. 
     Cooling channels  3  are formed between the cathode plate  1  and the anode plate  2 . 
     Specifically, the cooling channel  3  is formed at a position where the cathode plate  1  and the anode plate  2  are not attached to each other, and a cooling liquid or a cooling agent flows in the cooling channels  3 . 
     At two ends of the cathode channel  121 , the anode channel  221  and the cooling channel  3 , it is necessary to provide fluid distribution transition regions to distribute the oxidizing gas, the reducing gas, and the cooling liquid. 
     The anode channel ridge  22  and the cathode channel ridge  12  are intersected with each other, and an included angle between the anode channel ridge  22  and the cathode channel ridge  12  ranges from 60° to 120°. In this way, the fluid distribution transition region for the cathode channels  121  and the fluid distribution transition region for the anode channels  221  can be arranged separately, i.e., a hydrogen inlet manifold chamber  20 , a hydrogen outlet manifold chamber  30 , an oxygen inlet manifold chamber  40 , and an oxygen outlet manifold chamber  50 , as illustrated in  FIG. 1 , which is beneficial to reducing the complexity of the fluid distribution transition regions. Therefore, it is conducive to overcoming the problem that the fluid distribution transition regions can be hardly arranged when the scale of single cells is enlarged by using the ultrathin cathode plates  1  and the ultrathin anode plates  2 , thereby advantageously improving the power density of the fuel cell. 
     According to the fuel cell of the present disclosure, since the anode channel ridge  22  and the cathode channel ridge  12  are intersected with each other, the complexity of the fluid distribution transition regions can be advantageously reduced, and further, the thicknesses of the cathode plate  1  and the anode plate  2  can be advantageously reduced, so as to achieve the purpose of increasing the power density and the maximum discharge current of the fuel cell. 
     Referring to  FIG. 1 , the anode channel ridge  22  is arranged to be perpendicular to the cathode channel ridge  12 , to maximize a distance between the fluid distribution transition region for the cathode channels  121  and the fluid distribution transition region for the anode channel  221 . Therefore, the thicknesses of the cathode plate  1  and the anode plate  2  can be further reduced, thereby improving the power density of the fuel cell and maximum discharge current of the fuel cell. 
     Referring to  FIG. 4 ,  FIG. 6 , and  FIG. 8 , a recess  122  is formed at an intersection between the anode channel ridge  22  and the cathode channel ridge  12 . The anode channel ridge  22  is fitted in the recess  122 . The recess  122  is located on a flow path of the cathode channel  121  and is recessed towards an inside of the cathode channel  121 . A channel depth e of the cathode channel  121  at the recess  122  is smaller than a channel depth f of the cathode channel  121  at a position other than the recess  122 . 
     Specifically, a plurality of recesses  122  recessed towards the inside of the cathode channel  121  is disposed on the cathode channel ridge  12  along the flowing direction of the oxidizing gas. The positions and the number of the recesses  122  correspond to the positions and the number of the intersections between the anode channel ridge  22  and the cathode channel ridge  12 , such that the recesses  122  on the cathode channel ridge  12  are engaged with the anode channel ridge  22 , thereby facilitating an assembly of the cathode plate  1  and the anode plate  2 , and ensuring the correct positioning between the cathode plate  1  and the anode plate  2 . 
     The recesses  122  may slightly increase a gas resistance of the cathode channel  121 . However, the number of the channels of the anode plate  2  is smaller, and the depth thereof is shallower, that is, the number of the recesses  122  on each cathode channel  121  is smaller, and thus the increase of the gas resistance is not significant. Meanwhile, when the oxidizing gas flows through the recesses  122 , turbulence may be generated, which is favorable for promoting mass transfer exchange. 
     Further, referring to  FIG. 8 , in some embodiments of the present disclosure, the channel depth e of the cathode channel  121  at the recess  122  is 0.2 mm, the channel depth f of the cathode channel  121  at a position other than the recess  122  is 0.4 mm. A thickness g of the cathode plate  1  before molding is 0.1 mm, and a thickness h of the anode plate  2  before molding is 0.1 mm. A depth i of the anode channel  221  is 0.2 mm, that is, a total thickness of the cathode plate  1  and the anode plate  2  that are assembled is 0.6 mm, which is beneficial to improving the power density of the fuel cell. The single cell current may reach 10000A, which can meet an application requirement of ultra-high power. 
     Referring to  FIG. 2 , a plurality of anode channel ridges  22  is provided. The plurality of anode channel ridges  22  is arranged in parallel and spaced apart from each other, which is beneficial to ensuring a uniform distribution of the hydrogen in the anode channel  221  to the maximal extent and timely discharging anode products. 
     Referring to  FIG. 3 , a plurality of cathode channel ridges  12  is provided. The plurality of cathode channel ridges  12  is arranged in parallel and spaced apart from each other in parallel, which is beneficial to ensuring a uniform distribution of the air in the cathode channel  121  to the maximal extent and discharging the cathode product in time. 
     Referring to  FIG. 2 , the anode channel ridge  22  has a plurality of sub-channel ridges  23 . Each sub-channel ridge  23  has a sub-channel  231  formed therein and in communication with the anode channel  221 , and each sub-channel ridge  23  is parallel to the cathode channel ridge  12 . 
     Further, the sub-channel ridges  23  of one anode channel ridge  22  are arranged alternately with the sub-channel ridges  23  of the adjacent anode channel ridge  22 . 
     Further, the sub-channel ridges  23  are located between two adjacent cathode channel ridges  12 . 
     That is, an anode flow field is an interdigitated flow field overlapping a two-level fractal interdigitated flow field, generated by the anode channel  221  and the sub-channel  231 . Specifically, as illustrated in  FIG. 2 , the interdigitated flow field is generated by the plurality of anode channels  221 , the two-level fractal interdigitated flow field is generated by the sub-channels  231  of the anode channels  221 . As illustrated in  FIG. 1 , the sub-channel ridges  23  are located between two adjacent cathode channel ridges  12  to ensure sufficient supply of oxygen at high current density, thereby ensuring the performance of the fuel cell. 
     In some embodiments of the present disclosure, as illustrated in  FIG. 5 , the sub-channel ridges  23  are spaced apart from the cathode plate body  11  and in communication with the cooling channels  3 . As illustrated in  FIG. 6 , the cathode channel ridges  12  are attached to the anode plate body  21 . As illustrated in  FIG. 7 , the cooling channels  3  are formed between the cathode plate body  11  and the anode plate body  21  and located between two adjacent cathode channel ridges  12 , and the cooling liquid flows in the cooling channels  3 . 
     In some embodiments of the present disclosure, the cathode plate  1  is an oxygen-side plate, and the anode plate  2  is a hydrogen-side plate. 
     Referring to  FIG. 1  and  FIG. 3  to  FIG. 4 , the cathode plate  1  has an oxygen inlet manifold chamber  40  at one end and an oxygen outlet manifold chamber  50  at the other end. Oxygen enters the cathode channels  121  via the oxygen inlet manifold chamber  40 , and the excess oxygen flows out of the cathode channels  121  and enters the oxygen outlet manifold chamber  50 . Referring to  FIG. 1  to  FIG. 2  and  FIG. 4 , the anode plate  2  has a hydrogen inlet manifold chamber  20  at one end and a hydrogen outlet manifold chamber  30  at the other end. Hydrogen gas flows into the cathode channels  121  via the hydrogen inlet manifold chamber  20 , and the excess hydrogen gas flows out of the anode channels  221  and enters the hydrogen outlet manifold chamber  30 . 
     As can be seen from  FIG. 1 , the hydrogen inlet manifold chamber  20  and the hydrogen outlet manifold chamber  30  are disposed at two ends of the anode plate  2 ; the oxygen inlet manifold chamber  40  and the oxygen outlet manifold chamber  50  are disposed at two ends of the cathode plate  1 ; and an included angle between a line connecting the hydrogen inlet manifold chamber  20  and the hydrogen outlet manifold chamber  30  and a line connecting the oxygen inlet manifold chamber  40  and the oxygen outlet manifold chamber  50  ranges from 60° to 120°, and preferably 90°. That is, the line connecting the hydrogen inlet manifold chamber  20  and the hydrogen outlet manifold chamber  30  may be perpendicular to the line connecting the oxygen inlet manifold chamber  40  and the oxygen outlet manifold chamber  50 . The hydrogen inlet manifold chamber  20 , the hydrogen outlet manifold chamber  30 , the oxygen inlet manifold chamber  40 , and the oxygen outlet manifold chamber  50  are separately arranged, to favorably reduce the complexity of the fluid distribution transition regions (i.e., the respective manifold chambers). Further, it can advantageously solve the problem caused by the fact that the fluid distribution transition regions can hardly be arranged when the scale of the single cells is increased by using the ultrathin cathode plate  1  and the ultrathin anode plate  2 , which is conducive to enhancing the power density of the fuel cell. 
     As illustrated in  FIG. 9 , in a reaction region  60 , the oxygen in the cathode channels  121  reacts with the hydrogen in the anode channels  221 , the cooling liquid flows in the cooling channels  3 , and there is a transition region  70  in the fuel cell to buffer the oxygen in the cathode channels  121  and the hydrogen in the anode channels  221 , which is conducive to the sufficient reaction between the hydrogen and the oxygen. 
     The above are merely the preferred embodiments of the present disclosure and should not be regarded as limitations of the present disclosure. Without departing from the spirit and scope of the present disclosure, any modifications, equivalents, improvements, etc. shall fall within the scope of the present disclosure.