US-12626933-B2 - Bipolar plate for an electrochemical cell, method for manufacturing said bipolar plate, arrangement of electrochemical cells, and method for operating said arrangement of electrochemical cells

US12626933B2US 12626933 B2US12626933 B2US 12626933B2US-12626933-B2

Abstract

The invention relates to a bipolar plate ( 7 ) for an electrochemical cell ( 1 ), said bipolar plate comprising at least one first monopolar plate ( 13 ) having a first bead ( 15 ) and a second monopolar plate ( 17 ) having a second bead ( 19 ), the first bead ( 15 ) and the second bead ( 19 ) being arranged opposite one another and forming a channel ( 21 ), the first bead ( 15 ) and the second bead ( 19 ) each comprising a central base surface ( 23 ) and at least two inclined surfaces ( 24 ), and the first bead ( 15 ) and/or the second bead ( 19 ) comprising at least one outer base surface ( 25 ). At least one opening element ( 111 ) for the passage of at least one medium ( 29 ) between one of the at least two inclined surfaces ( 24 ) and the at least one outer base surface ( 25 ) is located on the first bead ( 15 ) and/or the second bead ( 19 ), said at least one opening element ( 111 ) comprising a lateral surface ( 121 ), a first open side surface ( 113 ), a second open side surface ( 115 ), and a top surface ( 140 ) having an opening ( 27 ), said first open side surface ( 113 ) being located in the at least one outer base surface ( 25 ), and said second open side surface ( 115 ) being located in one of the at least two inclined surfaces ( 24 ). The invention also relates to a method for manufacturing the bipolar plate ( 7 ), to an arrangement ( 69 ) of electrochemical cells ( 1 ), and to a method for operating said arrangement ( 69 ) of electrochemical cells ( 1 ).

Inventors

Christian Diessner
Harald Schmeisser
Jochen Wessner
Stefan Schoenbauer
Ulrich Berner

Assignees

ROBERT BOSCH GMBH

Dates

Publication Date: 20260512
Application Date: 20211025
Priority Date: 20201130

Claims (15)

1 . A bipolar plate ( 7 ) for an electrochemical cell ( 1 ), the bipolar plate comprising at least one first monopolar plate ( 13 ) having a first bead ( 15 ), and a second monopolar plate ( 17 ) having a second bead ( 19 ), wherein the first bead ( 15 ) and the second bead ( 19 ) are arranged opposite one another and form a channel ( 21 ), wherein the first bead ( 15 ) and the second bead ( 19 ) each comprise a central base surface ( 23 ) and at least two inclined surfaces ( 24 ) and the first bead ( 15 ) and/or the second bead ( 19 ) comprise at least one outer base surface ( 25 ), and wherein at least one opening element ( 111 ) for the passage of at least one medium ( 29 ) between one of the at least two inclined surfaces ( 24 ) and the at least one outer base surface ( 25 ) is located on the first bead ( 15 ) and/or the second bead ( 19 ), said at least one opening element ( 111 ) comprising a lateral surface ( 121 ), a first open side surface ( 113 ), a second open side surface ( 115 ), and a top surface ( 140 ) having an opening ( 27 ), said first open side surface ( 113 ) being located in the at least one outer base surface ( 25 ), and said second open side surface ( 115 ) being located in one of the at least two inclined surfaces ( 24 ).
2 . The bipolar plate ( 7 ) according to claim 1 , wherein the top surface ( 140 ) is arranged substantially parallel to the at least one outer base surface ( 25 ).
3 . The bipolar plate ( 7 ) according to claim 2 , wherein the top surface ( 140 ) has a rectangular shape or is at least partially circular in shape.
4 . The bipolar plate ( 7 ) according to claim 3 , wherein the lateral surface ( 121 ) is bordered by the top surface ( 140 ), the at least one outer base surface ( 25 ), and one of the at least two inclined surfaces ( 24 ).
5 . The bipolar plate ( 7 ) according to claim 4 , wherein the opening ( 27 ) has a circular cross-section.
6 . The bipolar plate ( 7 ) according to claim 5 , wherein the opening ( 27 ) forms a third side surface of the opening element ( 111 ).
7 . The bipolar plate ( 7 ) according to claim 6 , wherein the first bead ( 15 ) and/or the second bead ( 19 ) each comprise at least three inclined surfaces ( 24 ), wherein the at least one outer base surface ( 25 ) is arranged between two of the at least three inclined surfaces ( 24 ) and forms a step ( 31 ).
8 . The bipolar plate ( 7 ) according to claim 1 , wherein the top surface ( 140 ) has a rectangular shape or is at least partially circular in shape.
9 . The bipolar plate ( 7 ) according to claim 1 , wherein the lateral surface ( 121 ) is bordered by the top surface ( 140 ), the at least one outer base surface ( 25 ), and one of the at least two inclined surfaces ( 24 ).
10 . The bipolar plate ( 7 ) according to claim 1 , wherein the opening ( 27 ) has a circular cross-section.
11 . The bipolar plate ( 7 ) according to claim 1 , wherein the opening ( 27 ) forms a third side surface of the opening element ( 111 ).
12 . The bipolar plate ( 7 ) according to claim 1 , wherein the first bead ( 15 ) and/or the second bead ( 19 ) each comprise at least three inclined surfaces ( 24 ), wherein the at least one outer base surface ( 25 ) is arranged between two of the at least three inclined surfaces ( 24 ) and forms a step ( 31 ).
13 . A method for manufacturing a bipolar plate ( 7 ) according to claim 1 , wherein the first bead ( 15 ) and/or the second bead ( 19 ) and the at least one opening element ( 111 ) are manufactured by embossing from a base plate ( 123 ) of the first monopolar plate ( 13 ) and the second monopolar plate ( 17 ), respectively.
14 . An arrangement ( 69 ) of electrochemical cells ( 1 ) comprising at least one bipolar plate ( 7 ) according to claim 1 and at least one membrane-electrode assembly ( 4 ), wherein the at least one opening element ( 111 ) is arranged on the at least one bipolar plate ( 7 ) such that the opening ( 27 ) faces the at least one membrane-electrode assembly ( 4 ).
15 . A method for operating an arrangement ( 69 ) of electrochemical cells ( 1 ) according to claim 14 , wherein the at least one medium ( 29 ) is passed from the channel ( 21 ) through the at least one opening element ( 111 ) to the at least one membrane-electrode assembly ( 4 ), wherein the at least one medium ( 29 ) enters the at least one opening element ( 111 ) through the second open side surface ( 115 ) and/or through the first open side surface ( 113 ) and exits the at least one opening element ( 111 ) through the opening ( 27 ).

Description

BACKGROUND The invention relates to a bipolar plate for an electrochemical cell comprising at least one first monopolar plate having a first bead and a second monopolar plate having a second bead, the first bead and the second bead being arranged opposite one another and forming a channel, and the first bead and the second bead in each case comprising a central base surface and at least two inclined surfaces. The invention also relates to a method for manufacturing the bipolar plate, to an arrangement of electrochemical cells, and to a method for operating said arrangement of electrochemical cells. Electrochemical cells are electrochemical energy converters and are known in the form of fuel cells or electrolyzers. A fuel cell converts chemical reaction energy into electrical energy. In known fuel cells, hydrogen (H2) and oxygen (O2) are in particular converted to water (H2O), electrical energy, and heat. Proton-exchange membrane (PEM) fuel cells are known, among others. Proton-exchange membrane fuel cells comprise a centrally arranged membrane that is permeable to protons, i.e., hydrogen ions. The oxidizing agent, in particular atmospheric oxygen, is thereby spatially separated from the fuel, in particular hydrogen. Fuel cells comprise an anode and a cathode. The fuel is continuously supplied to the fuel cell at the anode and catalytically oxidized with loss of electrons to form protons that reach the cathode. The lost electrons are discharged from the fuel cell and flow via an external circuit to the cathode. The oxidizing agent is supplied to the fuel cell at the cathode and reacts to form water by receiving the electrons from the external circuit and protons. The resulting water is drained from the fuel cell. The gross reaction is: O2+4H++4e−→2H2O A voltage is in this case applied between the anode and the cathode of the fuel cell. In order to increase the voltage, multiple fuel cells can be mechanically arranged one behind the other to form a fuel cell stack, which can also be referred to as a fuel cell setup, and can be electrically connected in series. A stack of electrochemical cells, which can be referred to as an arrangement of electrochemical cells, typically comprises end plates that press the individual cells together and impart stability to the stack. The electrodes, i.e., the anode and the cathode, and the membrane can be structurally assembled to form a membrane-electrode assembly (MEA). Stacks of electrochemical cells further comprise bipolar plates, also referred to as gas distributor plates or distributor plates. Bipolar plates are used to distribute the fuel evenly to the anode and to distribute the oxidizing agent evenly to the cathode. In addition to the media guidance with respect to oxygen, hydrogen, water, and optionally a coolant, the bipolar plates ensure a planar electrical contact to the membrane. A fuel cell stack typically comprises up to several hundred individual fuel cells stacked one on top of the other in layers. The individual fuel cells comprise one MEA as well as one respective bipolar plate half on the anode side and on the cathode side. In particular, a fuel cell comprises an anode monopolar plate and a cathode monopolar plate, typically each in the form of embossed sheets, which together form the bipolar plate and thus form channels for guiding gas and liquids, between which the cooling medium can flow. Electrochemical cells typically further comprise gas diffusion layers arranged between a bipolar plate and an MEA. In contrast to a fuel cell, an electrolyzer is an energy converter which, while applying electrical voltage, preferably splits water into hydrogen and oxygen. Electrolyzers also comprise MEAS, bipolar plates, and gas diffusion layers, among other things. Electrochemical cells in a stack are often supplied with the media, in particular hydrogen and oxygen, or these media are discharged via media channels arranged perpendicular to the membrane of the electrochemical cell. The media channels are fluidically connected to the electrochemical cells, in particular to the bipolar plates, by ports, which can also be referred to as fluid terminals. The media channels are typically located on the edge of the stack and are often generated by congruently overlapping recesses forming the ports. From the ports, the media are fed through port passages into what is referred to as the flow-field, the active surface of the bipolar plate or membrane. In particular, the port passages for air or hydrogen facing the MEA are designed so that the port passages provide as large an opening as possible for the inflowing and outflowing media and, on the other hand, provide the best possible mechanical support effect for seals arranged on the opposite side of the MEA. DE 10158772 C1 and DE 10248531 B4 relate to fuel cell stacks with a layering of multiple fuel cells, whereby media are fed or discharged by bipolar plates and bead arrangements are provided for the sealing. SUMMARY A bi