EP-4738489-A2 - FOUR-FLUID BIPOLAR PLATE FOR FUEL CELL

EP4738489A2EP 4738489 A2EP4738489 A2EP 4738489A2EP-4738489-A2

Abstract

A bipolar plate for a fuel cell, comprising: a nonporous sub-plate comprising a water management side, an opposing reactant side, and an internal coolant passage therebetween; and a porous sub-plate comprising a reactant side and an opposing water management side, the reactant side comprising a first reactant flow field, and the water management side fluidly connected to the water management side of the nonporous sub-plate.

Inventors

WILSON, MATTHEW, P.
GORMAN, MICHAEL, E.
ANGLES, Samuel, J.

Assignees

Nimbus Power Systems Inc.

Dates

Publication Date: 20260506
Application Date: 20220604

Claims (15)

A bipolar plate for a fuel cell, comprising: a nonporous sub-plate comprising a water management side, an opposing reactant side, and an internal coolant passage therebetween; and a porous sub-plate comprising a reactant side and an opposing water management side, the reactant side comprising a first reactant flow field, and the water management side fluidly connected to the water management side of the nonporous sub-plate.
The bipolar plate according to claim 1, wherein the reactant side of the nonporous sub-plate comprises a second reactant flow field.
The bipolar plate according to claim 2, wherein the water management side of the nonporous sub-plate comprises a water flow field.
The bipolar plate according to claim 3, wherein the water flow field comprises channels.
The bipolar plate according to claim 1, wherein the internal coolant passage of the nonporous sub-plate is subdivided into a primary pathway and a secondary pathway.
The bipolar plate according to claim 5, wherein the nonporous sub-plate further comprises a divider to separate the primary pathway from the secondary pathway.
The bipolar plate according to claim 2, wherein the first reactant flow field in the porous sub-plate comprises oxidant channels, and the second reactant flow field in the nonporous sub-plate comprises fuel channels.
The bipolar plate according to claim 1, wherein the water management side of the porous sub-plate comprises a water flow field.
The bipolar plate according to claim 8, wherein the water flow field comprises channels.
The bipolar plate according to claim 8, wherein the water flow field comprises a pore structure configured as a water reservoir to facilitate passive water migration across the fuel cell.
The bipolar plate according to claim 8, wherein the water flow field comprises a bubble barrier pore structure adapted to permit liquid transport through the pore structure and prevent reactant gas transport through the pore structure.
The bipolar plate according to claim 1, wherein the water management side of the nonporous sub-plate comprises a recessed perimeter adapted to provide a nested seal with the porous sub-plate.
The bipolar plate according to claim 1, wherein the nonporous sub-plate comprises a first half-plate joined to a second half-plate.
The bipolar plate according to claim 13, wherein the internal coolant passage is defined by the joined first half-plate and second half-plate.
The bipolar plate according to claim 1, wherein the nonporous sub-plate further comprises at least one weep hole fluidly connecting the reactant side to the water management side, the at least one weep hole configured as a bubble barrier to transport excess water from the reactant side to the water management side while inhibiting transport of reactant gas.

Description

CROSS REFERENCE TO RELATED APPLICATION Reference is made to and this application claims priority from and the benefit of U.S. Patent Application Serial No. 17/344,377, filed June 10, 2021, entitled "FOUR-FLUID BIPOLAR PLATE FOR FUEL CELL," which application is incorporated herein in its entirety by reference. BACKGROUND OF THE INVENTION This disclosure relates generally to fuel cell bipolar plates and, more specifically, to a bipolar plate structure that provides improved delivery of humidified reactants and better removal of product water. In a proton exchange membrane (PEM) fuel cell, hydrogen fuel is supplied to a negative electrode (anode) where it catalytically dissociates into protons and electrons according to the oxidation reaction H2 → 2H+ + 2e-. The protons (H+) pass through a membrane electrolyte to a positive electrode (cathode) while the electrons (e-) are conducted through an external path creating an electric current between the anode and cathode through an external load. At the cathode the protons and electrons recombine in the presence of oxygen to form water according the reduction reaction: O2 + 4e- + 4H+ → 2H2O. The by-products of the PEM fuel cell reaction are water and heat; the heat requiring that the fuel cell be cooled to maintain an acceptable internal temperature. A single fuel cell includes a membrane electrode assembly (MEA), comprising the membrane electrolyte interposed between a pair of electrodes (anode and cathode), and, adjacent each electrode opposite the membrane electrolyte, an electrically conductive plate that defines the reactant gas flow fields. Typical flow field plates direct the reactant gases through a gas diffusion layer and a microporous layer to their respective electrodes. In some designs, the flow field plate can also transport the water byproduct away from the cell. A plurality of fuel cells are typically arranged and connected consecutively in a stack to increase the electrical output of the electrochemical conversion assembly or fuel cell. In this arrangement, two adjacent cell units can share a common polar plate, which serves as the anode and the cathode for the two adjacent cell units it connects in series. Such a polar plate is commonly referred to as a "bipolar plate". BRIEF SUMMARY OF THE INVENTION In one embodiment, a bipolar plate for a fuel cell includes a nonporous sub-plate comprising at least one water management side and an internal coolant passage. The bipolar plate further includes a porous sub-plate comprising a reactant side and an opposing water management side. The reactant side of the porous sub-plate includes a first reactant flow field, and the water management side is fluidly connected to the water management side of the nonporous sub-plate. In another embodiment, a bipolar plate for a fuel cell includes an oxidant flow field, a fuel reactant flow field, a dedicated coolant passage, and a water management flow field. In yet another embodiment, a bipolar plate for a fuel cell includes a nonporous sub-plate comprising a water management side and a reactant side. The reactant side includes a first reactant flow field. The bipolar plate further includes a porous sub-plate comprising a reactant side and an opposing water management side. The reactant side includes a second reactant flow field. The water management side of the porous sub-plate is fluidly connected to the water management side of the nonporous sub-plate. BRIEF DESCRIPTION OF THE DRAWINGS The features described herein can be better understood with reference to the drawings described below. The drawings are not necessarily to scale, emphasis instead generally being placed upon illustrating the principles of the invention. In the drawings, like numerals are used to indicate like parts throughout the various views. FIG. 1 depicts an schematic cross sectional exploded view of a typical fuel cell;FIG. 2 depicts a schematic section view of a typical fuel cell power plant;FIG. 3 depicts an exploded perspective anode-side view of a bipolar plate in accordance with one embodiment of the present invention;FIG. 4 depicts an exploded perspective cathode-side view of the bipolar plate shown in FIG. 3;FIG. 5 depicts a further exploded view of the bipolar plate shown in FIG. 3;FIG. 6 depicts a further exploded view of the bipolar plate shown in FIG. 4;FIG. 7 depicts a perspective cathode-side section view of the bipolar plate shown in FIG. 3;FIG. 8 depicts an enlarged section view of the bipolar plate shown in FIG. 7;FIG. 9 depicts another perspective cathode-side section view of the bipolar plate shown in FIG. 3;FIG. 10 depicts an enlarged section view of the bipolar plate shown in FIG. 9;FIG. 11 depicts a section view of a fuel cell with a bipolar plate according to a first embodiment of the invention;FIG. 12 depicts a section view of a stack of fuel cells with the bipolar plate according to the first embodiment of the invention;FIG. 13 depicts a schematic section view of a fuel cell p