Patent Application
20250112249
This disclosure relates to metal-reinforced solid based fuel cell electrodes, including both solid oxide fuel cells and protonic ceramic fuel cells.
Solid based fuel cells allow for conversion of electrochemical fuel to electricity with negligible pollution relative to fuel of choice. Among fuel cells under development, solid oxide fuel cells (SOFCs) operate at temperatures ranging from 500° C. to 1000° C. Because the SOFCs operate at such high temperature, the materials used as components are thermally challenged. Protonic ceramic fuel cells (PCFCs) reduce the operating range to about 400° C. to 600° C. but continue to see similar challenges in addition to resistive electrode processes and ionic mobility issues within SOFCs.
Conventional (SOFCs) having an electrolyte-supported configuration have poor mechanical strength and exhibit poor performance due to high electrolyte resistance. SOFCs having an electrode-supported configuration are somewhat stronger and better performing than the electrolyte-supported configurations. However, the SOFCs having an electrode-supported configuration also fail to meet the strength and performance requirements needed for automotive applications, due, in part, to the rapid heating and cooling cycles during start-up or switch off of the fuel cell.
Solid based fuel cells can operate with various fuels; however, to operate with non-hydrogen fuels, e.g., hydrocarbons and ethanol, solid based fuel cells require a reformer to reform hydrocarbon fuels to produce hydrogen from the non-hydrogen fuels. External reformers require additional space and add additional cost. Attempts at internalizing the reformation by using catalyst to internally reform the non-hydrogen fuels adds internal resistance, reducing the power output, as reforming catalysts are poor electronic conductors.
Disclosed herein are implementations of solid based fuel cells with metal-reinforced anodes as disclosed herein. The metal-reinforced anodes provide lower cost manufacturing, faster startup, thinner overall cells, reforming capabilities and carbon neutrality, as examples.
An implementation of a solid based fuel cell has a cathode layer, an interlayer, an electrolyte layer, and a metal-reinforced anode. The metal-reinforced anode has a first layer of first metal particles coated with solid electrolyte, the first metal particles embedded in anode active material, a second layer of metal through which holes are formed in a thickness direction, the holes filled with second metal particles coated with additional solid electrolyte, and a third layer of third metal particles coated with yet additional solid electrolyte, the third metal particles embedded in reforming catalyst.
An implementation of a metal-reinforced anode for a solid based fuel cell has a first layer of first metal particles coated with solid electrolyte, the first metal particles embedded in anode active material, the first layer having a first seal around a perimeter of the first layer. The metal-reinforced anode has a second layer of metal through which holes are formed in a thickness direction, the holes filled with second metal particles coated with additional solid electrolyte, the second layer having a second seal around a perimeter of the second layer. A third layer has third metal particles coated with yet additional solid electrolyte, the third metal particles embedded in reforming catalyst, the third layer having a third seal around a perimeter of the third layer.
The disclosure is best understood from the following detailed description when read in conjunction with the accompanying drawings. It is emphasized that, according to common practice, the various features of the drawings are not to-scale. On the contrary, the dimensions of the various features are arbitrarily expanded or reduced for clarity.
Solid based fuel cells, such as SOFCs, use fuels such as hydrogen, methane and ethanol. Some solid oxide, or ceramic, electrochemical devices operate at average temperatures as high as 1000° C. As a result of these high operating temperatures, exotic materials can be required that can withstand such temperatures. Solid based fuel cells include, but are not limited to, SOFCs, solid oxide electrolyzer cells, PCFCs and all solid-state energy conversion and storage devices such as sensors and batteries. Solid based fuel cells have a wide variety of applications, from use as auxiliary power units in vehicles to stationary power generation. These devices require start-up time to heat the device to operating temperature before obtaining the required performance. A slow start-up time is disadvantageous for use of the solid based fuel cells in automobiles. To utilize hydrocarbons in solid based fuel cells that are endothermic in nature, high heating is required to maintain an adequate operating temperature throughout the device.
The high temperatures at which the solid based fuel cells operate deteriorate the devices due to, for example, differences in coefficients of thermal expansion between components, whether electrolyte-supported or electrode-supported. The heavy vibrations and extreme cycling experienced when used in automotive applications can also exacerbate deterioration.
Solid based fuel cells using non-hydrogen fuels such as methanol or ethanol require a reformer to convert the non-hydrogen fuel to hydrogen, often mixed with one or more of carbon monoxide, carbon dioxide and steam, for example, when steam reforming is used. Conventional external reformers take up valuable space when used in vehicles, for example, and add to the system cost. To minimize the system cost and footprint, on-anode internal reforming using catalyst is being developed. Conventional on-anode internal reforming catalyst is usually a poor conductor of electricity, so the addition of the reforming catalyst can add internal ohmic resistance and decrease the power output of the solid based fuel cell.
Disclosed herein are metal-reinforced solid based fuel cells that are simpler to manufacture, that are light weight and designed for quick startup, provide high performance and durability using a nano-catalyst embedded design, allow for internal reforming, are easy to scale up can be used for hydrogen production and energy conversion, and allow for easy seal options. The disclosed solid based fuel cells can be used with both SOFCs and PCFCs.
An implementation of a solid based fuel cell 100 with the layers schematically illustrated in
The second layer 114 of the metal-reinforced anode 110 is a layer of metal through which holes 130 are formed in a thickness direction A. The holes 130 are best seen in
The holes 130 (shown empty in
Referring back to
The second layer 114 of metal, the first metal particles 120, the second metal particles 130 and the third metal particles 140 may all be the same material. As an example, the metal can be stainless steel, such as 434L or Cr-rich stainless steel.
The electrolyte 106, the solid electrolyte 122, the additional solid electrolyte 132, and the yet additional solid electrolyte 142 can all be the same solid electrolyte. One example is a scandia- and yttria-stabilized zirconia (ScYSZ) oxide.
In the implementations of the solid based fuel cell 100 disclosed herein, a seal can be included around the perimeter of the metal-reinforced anode 100. The seal provides for easy scale-up of cells as it eliminates the need for a separate mechanical seal or shim around each cell. The seal is necessary to prevent short circuiting or cross contamination. As illustrated in
In first layer 112 and third layer 116, the seals 160 are formed of a dense perimeter of solid electrolyte. The seals 160 are between 3 microns and 5 microns in thickness T around the perimeter of the layers.
The cathode layer 102 comprises cathode active material. The cathode active material can be, for example, lanthanum strontium cobaltite (LSC). Other examples include cerium-zirconium mixed oxides (CeZrO2-y) with transition metals or noble metals, lanthanum strontium manganite (LSM)-based perovskites, Sr-doped lanthanum ferrite (LSF) materials, Sr-doped lanthanum ferro-cobaltite (LSCF) materials, praseodymium oxide (PrOx), and neodymium oxide (NdOx). Other non-limiting examples include (La0.8Sr0.2)0.95MnO3, La0.6Sr0.4CoO3, Sr0.5Sm0.5O3, Ba0.5Sr0.5Co0.8Fe0.2O3, (La0.6Sr0.4)0.95(Co0.2Fe0.8)O3, PrBa0.5Sr0.5Co1.5Fe0.5O5+y with and without Gd-doped ceria. Using a cathode layer 102 consists of cathode active material keeps the thickness of the unit cell down.
The interlayer 104 can be, for example, gadolinium-doped ceria (GDC) oxide.
The electrolyte layer 106 is formed of a dense solid electrolyte. The solid electrolyte can be scandia- and yttria-stabilized zirconia (ScYSZ) oxide as noted. The solid electrolyte may also be doped bismuth oxide, scandia-ceria-stabilized zirconia (ScCeSZ), yttria-stabilized zirconia (YSZ), scandia-, cerium- and yttria-stabilized zirconia (ScCeYSZ), oxides thereof and La0.8Sr0.2Ga0.8Mg0.2O3 (LSGM).
The anode active material 124 in the first layer 112 can be, for example, one or more of nickel-based catalyst containing mixtures of cobalt and/or dopants of precious metals such as palladium, rhodium, and/or platinum, nickel-cerium oxide (Ni-CeOx), and cerium-zirconium mixed oxides (CeZrO2-y) with transition metals or noble metals. Other non-limiting examples include Ni—YSZ (Y-stabilized zirconia), Ni-GDC (Gd-doped ceria), Ni-SDC (Sm-doped ceria), Ni—ScYSZ (Sc, Y stabilized zirconia), and perovskite anodes (e.g., SrCo0.2Fe0.4Mo0.4O3).
The reforming catalyst 144 in the third layer 116 may depend on the type of fuel being reformed. As non-limiting examples, the reforming catalyst 144 can be Ni—BaCe0.7Zr0.1Y0.2O3-δ when the fuel is methane and can be Ru—Ni—Co/CZ or CeZrOx with multivalent ions such as Fe, Ni, Co and noble metals such as Pt, Ru, Rh, Pd, Ir, when the fuel is ethanol. Another example of a reforming catalyst 144 that can be used is NiMnCuCoCe oxide.
Electrochemical devices comprise multiple solid based fuel cells 100. In order to generate useful amounts of electrical power, unit fuel cells 100 can be configured in a stack, as a non-limiting example, with multiple planar cells separated by the interconnect components that conduct electricity between the cells.
While the disclosure has been described in connection with certain embodiments, it is to be understood that the disclosure is not to be limited to the disclosed embodiments but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the scope of the appended claims, which scope is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures as is permitted under the law.
