Patent Description:
The increased use of electrical power in aircraft systems and propulsion requires advanced electrical storage systems and/or a chemical to electrical power conversion system to generate adequate amounts of electrical power. Both high system efficiency and high power density of the conversion system are required.

Fuel cell based power systems, such as solid oxide fuel cell (SOFC) based power systems, are able to achieve electrical efficiencies of <NUM>% or greater. Further, SOFC power systems can operate with a variety of fuels and are scalable to achieve different power levels. Current, state of the art SOFC systems, however, have relatively low power densities of below <NUM> watts per kilogram, and relatively slow startup times typically exceeding <NUM> minutes. For aircraft and aerospace applications, increased power densities and reduced startup times are required.

<CIT>, <CIT> and <CIT> disclose a fuel cell stacks.

In one embodiment, a fuel cell includes a plurality of fuel cell layers stacked along a stacking axis. Each fuel cell layer includes a stacked arrangement of elements including a cathode, an anode, an electrolyte positioned between the anode and the cathode, a support layer positioned at the anode opposite the electrolyte, and a separator plate located at the support layer opposite the anode. The support layer is configured to contact the cathode of an adjacent fuel cell layer of the plurality of fuel cell layers. The separator plate defines a plurality of anode flow channels configured to deliver a fuel therethrough and a plurality of cathode flow channels configured to deliver an air flow therethrough.

Additionally or alternatively, in this or other embodiments the electrolyte is formed from a solid oxide material.

Additionally or alternatively, in this or other embodiments the separator plate defines the plurality of anode flow channels at a first side of the separator plate and the plurality of cathode flow channels at a second side of the separator plate opposite the first side.

Additionally or alternatively, in this or other embodiments the separator plate includes a plurality of curved portions separated by flat support portions, with the support portions interfacing with the support layer and curved portions contacting the cathode of the adjacent fuel cell layer.

Additionally or alternatively, in this or other embodiments the wherein the plurality of anode flow channels at least partially overlap the plurality of cathode flow channels along the stacking axis.

Additionally or alternatively, in this or other embodiments the support layer includes a porous portion located at the anode flow channels configured to allow fuel flow from the anode fuel channels to the anode through the porous portion.

Additionally or alternatively, in this or other embodiments the support layer further includes a non-porous portion surrounding the porous portion.

Additionally or alternatively, in this or other embodiments one or more manifolds are located in the solid portion to distribute fuel to the plurality of anode flow channels.

Additionally or alternatively, in this or other embodiments the support layer is formed from a metal material.

Additionally or alternatively, in this or other embodiments a metal catalyst foam is located between the support layer and the separator plate.

In another embodiment, fuel cell layer of a multi-layer fuel cell includes a cathode, an anode, an electrolyte located between the anode and the cathode, a support layer positioned at the anode opposite the electrolyte, and a separator plate positioned at the support layer opposite the anode. The support layer is configured to contact the cathode of an adjacent fuel cell layer. The separator plate defines a plurality of anode flow channels configured to deliver a fuel therethrough and a plurality of cathode flow channels configured to deliver an air flow therethrough.

Additionally or alternatively, in this or other embodiments the plurality of anode flow channels at least partially overlap the plurality of cathode flow channels along the stacking axis.

Additionally or alternatively, in this or other embodiments the support layer includes a porous portion disposed at the anode flow channels configured to allow fuel flow from the anode fuel channels to the anode through the porous portion.

Referring to <FIG>, shown is a schematic illustration of an embodiment of a fuel cell (<NUM>). In some embodiments, the fuel cell <NUM> is a solid oxide fuel cell, a proton conducting fuel cell, an electrolyzer, or other fuel cell apparatus. The fuel cell <NUM> includes an anode <NUM> and a cathode <NUM> with an electrolyte <NUM> disposed between the anode <NUM> and the cathode <NUM>. In the case of the solid oxide fuel cell <NUM>, the electrolyte <NUM> is a solid oxide material such as, for example, a ceramic material. A flow of fuel is introduced to the fuel cell <NUM> along with a flow of air. Chemical reactions of the fuel and air with the electrolyte <NUM> produces electricity. In some embodiments, an operating temperature of the fuel cell <NUM> is in the range of <NUM> -<NUM> degrees Celsius, while in other embodiments the operating temperature is in the range of <NUM>-<NUM> degrees Celsius. The flow of fuel may comprise, for example, natural gas, coal gas, biogas, hydrogen, or other fuels such as jet fuel.

Referring now to <FIG>, the fuel cell <NUM> includes a plurality of fuel cell layers <NUM> stacked along a stacking axis <NUM>. In some embodiments, each fuel cell layer <NUM> has a rectangular shape. It is to be appreciated, however, that the fuel cell layers <NUM> may have other polygonal shapes or may be, for example, circular, elliptical or oval in shape. As shown in <FIG>, each fuel cell layer <NUM> includes a separator plate <NUM> and a support <NUM> located over the separator plate <NUM> with the support <NUM> secured to the separator plate <NUM>. Joining the support <NUM> to the separator plate <NUM> increases their individual strength and rigidity, and allows for using thinner, lighter materials in forming the support <NUM> and the separator plate <NUM> than would be otherwise feasible. An anode <NUM>, electrolyte <NUM> and a cathode <NUM> are stacked atop the support <NUM> in that order. In some embodiments, the electrolyte <NUM> is formed from a solid oxide material, such as a ceramic material. The fuel cell layers <NUM> are stacked such that the cathode <NUM> contacts the separator plate <NUM> of the neighboring fuel cell layer <NUM>.

The separator plate <NUM> is compliant and lightweight and is shaped to define a plurality of anode flow channels <NUM> and a plurality of cathode flow channels <NUM> and separate the anode flow channels <NUM> from the cathode flow channels <NUM>. The plurality of anode flow channels <NUM> are defined at a first side of the separator plate <NUM> and the plurality of cathode flow channels <NUM> are defined at a second side of the separator plate <NUM> opposite the first side. As illustrated the anode flow channels <NUM> and the cathode flow channels <NUM> at least partially overlap along the stacking axis <NUM>. This improves a density of the fuel cell <NUM> along the stacking axis <NUM>.

Compliance of the separator plate <NUM> ensures good contact with the cathode <NUM> for high performance, and the separator plate <NUM> is configured for light weight to enable high power density of the fuel cell <NUM>. The fuel flows through the anode flow channels <NUM> and the air flows through the cathode flow channels <NUM>. In some embodiments, such as in <FIG>, the separator plate <NUM> includes a plurality of curved portions <NUM> separated by flat support portions <NUM>, with the support portions <NUM> interfacing with the support <NUM> and curved portions <NUM> contacting the cathode <NUM> of the neighboring fuel cell layer <NUM>. The waveform shape of the separator plate <NUM> with the plurality of curved portions <NUM> allows for greater levels of fuel flow coverage to the anode <NUM> and a greater level of airflow coverage to the cathode <NUM>. In other embodiments, the curved portions <NUM> may have other shapes, such as rectilinear as shown in <FIG>. The shapes illustrated in <FIG> are merely exemplary, with the shapes of anode flow channels <NUM> and cathode flow channels <NUM> selected to provide the desired compliance in the stacking axis <NUM> direction, while allowing for selected anode and cathode flows which may be at significantly different flow rates. The separator plate <NUM> may be formed from corrugated sheet stock with features on the order of millimeters to centimeters. Alternatively, the separator plate <NUM> may be formed from sheet material by, for example, stamping, extrusion, folding, bending, roll forming, hydroforming, or the like. Other methods may include injection molding, additive manufacturing including laser powder bed fusion, electron beam melting, directed energy deposition, or laminated object manufacture. In still other embodiments, the separator plate may be formed at least partially by a process such as ultraviolet lithography and etching which may be used to form features with a resolution below <NUM> microns, or by micro-EDM (electrical discharge machining) or laser micromachining, both of which that may be utilized to produce features with a resolution in the range of <NUM> to <NUM> microns. In some embodiments, the separator plate <NUM> is formed from a stainless steel or titanium material.

Referring again to <FIG> and also to the partially exploded view of <FIG>, fuel is distributed to the anode fuel channels <NUM> via a primary manifold <NUM> and a secondary manifold <NUM>. The primary manifold <NUM> extends between the fuel cell layers <NUM> to distribute fuel to each fuel cell layer <NUM> of the plurality of fuel cell layers <NUM>. Each fuel cell layer <NUM> includes a secondary manifold <NUM> located at, for example, a first end <NUM> of the anode flow channels <NUM>. The secondary manifold <NUM> is connected to the primary manifold <NUM> and the plurality of anode flow channels <NUM> to distribute fuel from the primary manifold <NUM> to each of the anode flow channels <NUM> of the fuel cell layer <NUM>. The anode flow channels <NUM> extend from the secondary manifold <NUM> at the first end <NUM> of the anode flow channels <NUM> to a collection manifold <NUM> at a second end <NUM> of the anode flow channels <NUM>. Fuel flows from the primary manifold <NUM> through the secondary manifold <NUM>, and through the anode flow channels <NUM> with anode byproducts such as water vapor and carbon dioxide exiting the anode flow channels <NUM> and flowing into the collection manifold <NUM>.

The support layer <NUM> is formed from a metal material in some embodiments, and includes a porous section <NUM> and a non-porous or solid section <NUM>, with the solid section <NUM> surrounding the porous section <NUM> and defining an outer perimeter of the support layer <NUM>. The porous section <NUM> may be formed by, for example, laser drilling of a metal sheet. or sintering of metal powder, or additive manufacturing. The porous section <NUM> is located over the anode flow channels <NUM> to allow the fuel flow to reach the anode <NUM> through the porous section <NUM>. In some embodiments, a metal catalyst foam layer <NUM> is located between the separator plate <NUM> and the support layer <NUM>.

The fuel cell <NUM> configurations disclosed herein enable a high performance electrical power system for, for example, an aircraft, especially for long duration operation. The configurations further reduce startup times and provide power densities in the range of <NUM>-<NUM> kilowatts/kilogram with a cell performance of <NUM>. 8W/cm<NUM>. Further, the improved power density may be achieved utilizing a lightweight separator plate <NUM>, with a separator plate <NUM> formed from, for example, stainless steel having a thickness of <NUM> mil to 10mil. Further, other materials such as titanium alloys, or other materials at lower operating temperatures may be used to form a lightweight separator plate <NUM>.

Claim 1:
A fuel cell layer of a multi-layer fuel cell, comprising:
a cathode (<NUM>);
an anode (<NUM>);
an electrolyte (<NUM>) disposed between the anode and the cathode;
a support layer (<NUM>) disposed at the anode opposite the electrolyte;
a separator plate (<NUM>) disposed at the support layer opposite the anode, the support layer configured to contact the cathode of an adjacent fuel cell layer, the separator plate defining a plurality of anode flow channels configured to deliver a fuel therethrough and a plurality of cathode flow channels configured to deliver an air flow therethrough wherein the anode flow channels and the cathode flow channels at least partially overlap along a stacking axis direction of the multilayer fuel cell.