Layered Cathode for Molten Carbonate Fuel Cell

Patent metadata

Field	Value
Publication number	US-2020176784-A1
Application number	US-201916695278-A
Country	US
Kind code	A1
Filing date	Nov 26, 2019
Priority date	Nov 30, 2018
Publication date	Jun 4, 2020
Grant date	—

Abstract

A layered cathode structure for a molten carbonate fuel cell is provided, along with methods of forming a layered cathode and operating a fuel cell including a layered cathode. The layered cathode can include at least a first cathode layer and a second cathode layer. The first cathode layer can correspond to a layer that is adjacent to the molten carbonate electrolyte during operation, while the second cathode layer can correspond to a layer that is adjacent to the cathode collector of the fuel cell. The first cathode layer can be formed by sintering a layer that includes a conventional precursor material for forming a cathode, such as nickel particles. The second cathode layer can be formed by sintering a layer that includes a mixture of particles of a conventional precursor material and 1.0 vol % to 30 vol % of particles of a lithium pore-forming compound. The resulting layered cathode structure can have an increased pore size adjacent to the cathode collector to facilitate diffusion of CO2 into the electrolyte interface, while also having a smaller pore size adjacent to the electrolyte to allow for improved electrical contact and/or reduced polarization at the interface between the electrolyte and the cathode.

First claim

1 . A method for producing electricity, the method comprising:
contacting an anode of a molten carbonate fuel cell with an anode input stream; contacting a second cathode layer of a cathode of the molten carbonate fuel cell with a cathode inlet stream comprising O 2 and CO 2 , the second cathode layer comprising an average pore diameter of 5.5 μm or more, the cathode further comprising a first cathode layer adjacent to an electrolyte of the fuel cell, the first cathode layer having an average pore diameter of 4.5 μm or less; and operating the molten carbonate fuel cell at a current density of 60 mA/cm 2 or more to generate electricity, an anode exhaust comprising H 2 , CO, and CO 2 , and a cathode exhaust comprising CO 2 .

2 . The method of claim 1 , wherein the first cathode layer comprises lithiated nickel oxide, or wherein the second cathode layer comprises lithiated nickel oxide, or a combination thereof.

3 . The method of claim 1 , wherein 70 wt % or more of the second layer of the cathode comprises the composition of the first layer of the cathode.

4 . The method of claim 1 , wherein the first layer of the cathode comprises a thickness of 250 μm to 400 μm, or wherein the second layer of the cathode comprises a thickness of 500 μm to 800 μm, or a combination thereof.

5 . The method of claim 1 , wherein the molten carbonate fuel cell is operated at an average temperature of 650° C. or less.

6 . The method of claim 1 , wherein the second layer of the cathode of the molten carbonate fuel cell is formed by sintering a layer comprising 1.0 vol % to 30 vol % of a lithium pore-forming compound, or wherein the second layer of the cathode of the molten carbonate fuel cell is formed by sintering a layer comprising 1.0 vol % to 30 vol % of particles comprising a lithium pore-forming compound, or a combination thereof.

7 . The method of claim 6 , wherein the lithium pore-forming compound comprises particles having an average particle size of 4.0 μm to 10 μm.

8 . The method of claim 1 , wherein the first cathode layer is formed by sintering a layer comprising particles having an average particle size of 1.0 μm to 3.0 μm.

9 . The method of claim 1 , wherein the second cathode layer comprises an average pore diameter of 6.0 μm to 10 μm.

10 . The method of claim 1 , wherein the cathode exhaust comprises 2.0 vol % CO 2 or less, 1.0 vol % O 2 or more, and 1.0 vol % H 2 O or more; or a combination thereof.

11 . The method of claim 1 , wherein the cathode inlet stream comprises 5.0 vol % CO 2 or less, or wherein the cathode exhaust comprises 1.0 vol % CO 2 or less, or a combination thereof.

12 . The method of claim 11 , wherein the molten carbonate fuel cell is operated at a transference of 0.95 or less.

13 . A molten carbonate fuel cell, comprising:
an anode adjacent to an anode collector; an electrolyte matrix comprising an electrolyte; and a cathode comprising a first cathode layer adjacent to the electrolyte matrix and a second cathode layer adjacent to a cathode collector, the first cathode layer comprising an average pore diameter of 4.5 μm or less, the second cathode layer comprising an average pore diameter of 5.5 μm or more.

14 . The molten carbonate fuel cell of claim 13 , wherein the first cathode layer comprises lithiated nickel oxide, or wherein the second cathode layer comprises lithiated nickel oxide, or a combination thereof.

15 . The molten carbonate fuel cell of claim 13 , wherein 70 wt % or more of the second cathode layer comprises the composition of the first layer of the cathode.

16 . The molten carbonate fuel cell of claim 13 , wherein the first cathode layer comprises a thickness of 250 μm to 400 μm, or wherein the second cathode layer comprises a thickness of 500 μm to 800 μm, or a combination thereof.

17 . The molten carbonate fuel cell of claim 13 , wherein the second cathode layer comprises an average pore diameter of 6.0 μm to 10 μm.

18 . A method for forming a molten carbonate fuel cell, comprising:
depositing a first layer of first cathode precursor particles having an average particle size of 1.0 μm to 3.0 μm; depositing a second layer comprising 1.0 vol % to 30 vol % of lithium pore-forming compound particles and 70 vol % or less of second cathode precursor particles, the lithium pore-forming compound particles having an average particle size of 4.0 μm to 10 μm, the second cathode precursor particles having an average particle size of 1.0 μm to 3.0 μm; and sintering the first layer and the second layer to form a cathode comprising a first cathode layer comprising an average pore size of 4.5 μm or less and a second cathode layer comprising an average pore size of 5.5 μm or more.

19 . The method of claim 18 , wherein the first cathode precursor particles and the second cathode precursor particles have substantially the same composition.

20 . The method of claim 18 , wherein a porosity of the first layer of cathode precursor particles is 70% to 80% and a porosity of the second layer of cathode precursor particles is 78% to 88%.

21 . The method of claim 18 , wherein a porosity of the first cathode layer is 50% to 62% and a porosity of the second cathode layer is 65% to 77%.

22 . The method of claim 18 , wherein the first cathode layer comprises a thickness of 250 μm to 400 μm, or wherein the second cathode layer comprises a thickness of 500 μm to 800 μm, or a combination thereof.

23 . The method of claim 18 , wherein the first cathode layer comprises lithiated nickel oxide, or wherein the second cathode layer comprises lithiated nickel oxide, or a combination thereof.

Assignees

• Exxonmobil Res & Eng Co
• Fuelcell Energy Inc

Inventors

• Hilmi Abdelkader
• Kiss Gabor
• Blanco Gutierrez Rodrigo F
• Geary Timothy C
• Demeter Ethan L
• Yuh Chao-Yi

Classifications

• H01M4/8657 Primary

  layered · CPC title

• H01M4/9033

  Complex oxides, optionally doped, of the type M1MeO3, M1 being an alkaline earth metal or a rare earth, Me being a metal, e.g. perovskites · CPC title

• H01M2004/8684

  Negative electrodes · CPC title

• H01M4/8825

  Methods for deposition of the catalytic active composition · CPC title

• H01M2008/147

  Fuel cells with molten carbonates · CPC title