Operation of molten carbonate fuel cells with high electrolyte fill level

Patent metadata

Field	Value
Publication number	US-2021159531-A1
Application number	US-201916695356-A
Country	US
Kind code	A1
Filing date	Nov 26, 2019
Priority date	Nov 26, 2019
Publication date	May 27, 2021
Grant date	—

Abstract

An elevated target amount of electrolyte is used to initially fill a molten carbonate fuel cell that is operated under carbon capture conditions. The increased target electrolyte fill level can be achieved in part by adding additional electrolyte to the cathode collector prior to start of operation. The increased target electrolyte fill level can provide improved fuel cell performance and lifetime when operating a molten carbonate fuel cell at high current density with a low-CO2 content cathode input stream and/or when operating a molten carbonate fuel cell at high CO2 utilization.

First claim

1 . A method for producing electricity in a molten carbonate fuel cell comprising a lithium-containing electrolyte, the method comprising: operating a molten carbonate fuel cell comprising an anode, a matrix, and a cathode with a cathode input stream comprising 10 vol % or less of CO 2 at an average current density of 120 mA/cm 2 or more and a CO 2 utilization of 60% or more, the molten carbonate fuel cell further comprising a combined target electrolyte fill level of 70 vol % or more of a combined matrix pore volume and cathode pore volume.

2 . The method of claim 1 , wherein operating the molten carbonate fuel cell comprises operating at a measured CO 2 utilization of 75% or more.

3 . The method of claim 1 , wherein the cathode input stream comprises 5.0 vol % or less of CO 2 , or wherein the cathode exhaust comprises 2.0 vol % or less of CO 2 , or wherein the molten carbonate fuel cell is operated at a transference of 0.95 or less, or a combination of two or more thereof.

4 . The method of claim 1 , wherein the electrolyte comprises a non-eutectic mixture, or wherein the lithium carbonate content of the electrolyte is greater than a corresponding eutectic composition by 10 wt % or more.

5 . The method of claim 1 , wherein the current density is 150 mA/cm 2 or more.

6 . The method of claim 1 , wherein the molten carbonate fuel cell is operated for a cumulative time of 50 hours or more.

7 . The method of claim 1 , wherein a target cathode electrolyte fill level comprises 85 vol % to 140 vol % of the cathode pore volume.

8 . The method of claim 1 , wherein the combined target electrolyte fill level is 85 vol % to 128 vol %.

9 . The method of claim 1 , wherein at least a portion of the electrolyte is stored in a cathode collector.

10 . A method for producing electricity in a molten carbonate fuel cell comprising a lithium-containing electrolyte, the method comprising: operating a molten carbonate fuel cell comprising an anode, a matrix, and a cathode with a cathode input stream comprising CO 2 at an average current density of 120 mA/cm 2 or more and a CO 2 utilization of 90% or more, the molten carbonate fuel cell further comprising a combined target electrolyte fill level of 70 vol % or more of a combined matrix pore volume and cathode pore volume.

11 . The method of claim 10 , wherein the cathode input stream comprises 5.0 vol % or less of CO 2 , or wherein the cathode exhaust comprises 2.0 vol % or less of CO 2 , or wherein the molten carbonate fuel cell is operated at a transference of 0.95 or less, or a combination of two or more thereof.

12 . The method of claim 10 , wherein the electrolyte comprises a non-eutectic mixture, or wherein the lithium carbonate content of the electrolyte is greater than a corresponding eutectic composition by 10 wt % or more.

13 . The method of claim 10 , wherein the current density is 150 mA/cm 2 or more.

14 . The method of claim 10 , wherein the molten carbonate fuel cell is operated for a cumulative time of 50 hours or more.

15 . The method of claim 10 , wherein a target cathode electrolyte fill level comprises 85 vol to 140 vol % of the cathode pore volume.

16 . The method of claim 10 , wherein the combined target electrolyte fill level is 85 vol % to 128 vol %.

17 . A molten carbonate fuel cell comprising:
a cathode collector, a cathode, a matrix, and an anode; and a lithium-containing electrolyte, a combined target electrolyte fill level of the lithium-containing electrolyte corresponding to 85 vol % or more of a combined matrix pore volume and cathode pore volume.

18 . The fuel cell of claim 17 , wherein the cathode pore volume is 1.5 to 2.0 times the matrix pore volume.

19 . The fuel cell of claim 17 , wherein the electrolyte comprises a lithium carbonate content that is greater than a corresponding lithium content in a corresponding eutectic mixture by 10 wt % or more.

20 . The fuel cell of claim 17 , wherein at least a portion of the combined target electrolyte fill level is stored in the cathode collector.

21 . The fuel cell of claim 17 , wherein the combined target electrolyte fill level is 90 vol % to 127 vol %.

22 . The fuel cell of claim 17 , wherein the fuel cell comprises a target cathode electrolyte fill level of 85 vol % to 140 vol %.

Assignees

• Exxonmobil Res & Eng Co
• Fuelcell Energy Inc

Inventors

• Rosen Jonathan
• Elsen Heather A
• Kiss Gabor
• Lamberti William A
• Horn William C
• Zhang Anding
• Geary Timothy C
• Franco Adam
• Hilmi Abdelkader

Classifications

• Y02E60/50

  Fuel cells · CPC title

• H01M2008/147

  Fuel cells with molten carbonates · CPC title

• H01M8/145 Primary

  comprising carbonates · CPC title

• H01M8/142 Primary

  with matrix-supported or semi-solid matrix-reinforced electrolyte · CPC title

• H01M8/0295

  Matrices for immobilising electrolyte melts · CPC title