Flowing electrolyte fuel cell with improved performance and stability

Patent metadata

Field	Value
Publication number	US-2017187054-A1
Application number	US-201514981104-A
Country	US
Kind code	A1
Filing date	Dec 28, 2015
Priority date	Dec 28, 2015
Publication date	Jun 29, 2017
Grant date	—

Abstract

A flowing electrolyte fuel cell system design (DHCFC-Flow) is provided. The use of a flowing oxygen-saturated electrolyte in a fuel cell offers a significant enhancement in the cell performance characteristics. The mass transfer and reaction kinetics of the superoxide/peroxide/oxide ion (mobile oxygen ion species) in the fuel cell are enhanced by recirculating an oxidizing gas-saturated electrolyte. Recirculating oxygen-saturated electrolyte through a liquid channel enhances the maximal current observed in a fuel cell. The use of a oxygen saturated electrolyte ensures that the reaction kinetics of the oxygen reduction reaction are fast and the use of convection ameliorates concentration gradients and the diffusion-limited maximum current density. The superoxide ion is generated in situ by the reduction of the oxygen dissolved in the gaseous electrolyte. Also, a dual porosity membrane allows the uniform flow of fuel (e.g., methane) on the fuel side, without allowing phase mixing. The capillary pressure for liquid intrusion into the gas phase and vice versa is quite large, estimated to be 1-10 psi. This makes it easier to control the fluctuations in gas/liquid velocity which might otherwise lead to phase mixing and the loss of fuel cell performance. In one variation, a dual-porosity membrane structure is incorporated in the system to allow uniform flow of fuel and prevent mixing of fuel with a liquid electrolyte.

First claim

What is claimed is:

1 . An electrochemical fuel cell system employing the use of a fuel for electrochemical energy conversion and at least one fuel cell, the at least one fuel cell comprising:
an inlet portion configured to receive liquid electrolyte in a saturated state; a flow path configured to facilitate a flow of the liquid electrolyte; and, an outlet portion configured to provide an exit for the flowing liquid electrolyte in a depleted state.

2 . The system as set forth in claim 1 wherein the liquid electrolyte is saturated with at least one of oxygen, oxygen ions or a fuel.

3 . The system as set forth in claim 1 further comprising a mechanism configured to saturate the liquid electrolyte with oxygen, provide the oxygen-saturated liquid electrolyte to the inlet portion, and receive the oxygen-depleted liquid electrolyte liquid from the outlet portion.

4 . The system as set forth in claim 1 wherein oxygen ions are generated in-situ and incorporated into the flow of the liquid electrolyte.

5 . The system set forth in claim 1 wherein carbon-containing products of fuel cell reaction (CO x , x=1, 2) are dissolved in the liquid electrolyte and carried away for carbon capture and sequestration.

6 . The system as set forth in claim 1 further comprising a dual-porosity membrane configured to allow uniform flow of fuel on a fuel side of the at least one fuel cell and prevent mixing of the fuel with the liquid electrolyte.

7 . The system as set forth in claim 6 wherein the membrane comprises a porous gas diffuser bonded to a catalyst-coated nanoporous layer.

8 . The system as set forth in claim 7 wherein the gas diffuser has pores with diameters in a range of approximately 5-100 microns.

9 . The system as set forth in claim 7 wherein the gas diffuser has a thickness of approximately 5 millimeters.

10 . The system as set forth in claim 7 wherein the catalyst-coated nanoporous layer has pores with diameters in a range of approximately 5 nanometers to 10 microns.

11 . The system as set forth in claim 7 wherein the catalyst-coated nanoporous layer comprises a nanoporous layer having a thickness of approximately 50 microns and a coating layer of approximately 1 micron.

12 . The system as set forth in claim 7 wherein the nanoporous layer comprises at least one of an anodized aluminum oxide, a porous polymer including Teflon, expanded or porous PTFE (polytetrafluoroethylene), a polyimide including porous Kapton, or a porous ceramic including porous alumina or porous zirconia.

13 . The system as set forth in claim 7 wherein the nanoporous layer is surface treated to be nonwett-able by the electrolyte.

14 . The system as set forth in claim 11 wherein the coating layer comprises Teflon (PTFE) or a non-stick type coating.

15 . The system as set forth in claim 1 wherein the at least one fuel cell uses a gaseous fuel.

16 . The system as set forth in claim 1 wherein the at least one fuel cell uses a liquid fuel.

17 . The system as set forth in claim 1 wherein the at least one fuel cell uses a solid fuel.

18 . The system as set forth in claim 1 wherein the electrolyte is an ionic liquid.

19 . The system as set forth in claim 18 , wherein the ionic liquid is at least one of 1-ethyl, 3-methyl imidazolium trifluoromethanesulfonate [emim][OTf], 1-ethyl, 3-methyl imidazolium bis(trifluoromethylsulfonylimide) [emim][TFSI], butyl trimethylammonium bis(trifluoromethylsulfonylimide) [btma][TFSI], 1-propyl, 3-methylpyrrolidinium bis(trifluorosulfonylimide) [pmpy][TFSI], 1-butyl, 3-methylpyrrolidinium bis(trifluorosulfonylimide) [bmpy][TFSI], 1-ethyl-3-methylimidazolium dicyanamide [emim][-DCA], 1,2-dimethyl-3-propylimidazolium bis(trifluoromethylsulfonyl)imide [mmpim][TFSI], and 1-ethyl-2,3-dimethylimidazolium bis trifluoromethylsulfonyl)imide.

20 . The system as set forth in claim 1 wherein an operating temperature is in a range of approximately 100-400° C.

21 . The system as set forth in claim 1 wherein an operating temperature is an ambient temperature in a range of 0-100° C.

22 . The system as set forth in claim 1 comprising a stack of fuel cells.

23 . The system as set forth in claim 22 wherein the stack of fuel cells is electrically connected in a parallel configuration to maximize current delivering capability.

24 . The system as set forth in claim 22 wherein the stack of fuel cells is electrically connected in a series configuration to maximize voltage delivering capability.

25 . The system as set forth in claim 22 wherein the stack of fuel cells is electrically connected in a series-parallel combination configuration to achieve the desired voltage and current delivering capability.

26 . An electrochemical fuel cell system employing the use of a fuel for electrochemical energy conversion and at least one fuel cell, the at least one fuel cell comprising:
a fuel inlet; a fuel outlet; a liquid electrolyte; and, a dual-porosity membrane configured to allow uniform flow of fuel between the fuel inlet and fuel outlet to prevent mixing of the fuel with the liquid electrolyte.

27 . The system as set forth in claim 26 wherein the membrane comprises a porous gas diffuser bonded to a catalyst-coated nanoporous layer.

28 . The system as set forth in claim 27 wherein the gas diffuser has pores with diameters in a range of approximately 5-100 microns.

29 . The system as set forth in claim 27 wherein the gas diffuser has a thickness of approximately 5 millimeters.

30 . The system as set forth in claim 27 wherein the catalyst-coated nanoporous layer has pores with diameters in a range of approximately 5 nanometers to 1 micron.

31 . The system as set forth in claim 27 wherein the catalyst-coated nanoporous layer comprises a nanoporous layer having a thickness of approximately 50 microns and a coating layer of approximately 1 micron.

32 . The system as set forth in claim 27 wherein the nanoporous layer comprises at least one of an anodized aluminum oxide, a porous polymer including Teflon, expanded or porous PTFE (polytetrafluoroethylene), a polyimide including porous Kapton, or a porous ceramic including porous alumina or porous zirconia.

33 . The system as set forth in claim 27 wherein the nanoporous layer is surface treated to be nonwettable by the electrolyte.

34 . The system as set forth in claim 31 wherein the coating layer comprises Teflon (PTFE) or a non-stick type coating.

35 . A method for use in an electrochemical fuel cell system employing the use of a fuel for electrochemical energy conversion and at least one fuel cell, the method comprising:
receiving a liquid electrolyte in a saturated state; facilitating a flow of the liquid electrolyte in a flow path; and, allowing for an exit of the flowing liquid electrolyte in a depleted state.

36 . An electrochemical energy conversion system including at least one rechargeable battery, the at least one rechargeable battery comprising:
an inlet portion configured to receive liquid electrolyte in a saturated state; a flow path configured to facilitate a flow of the liquid electrolyte; and, an outlet portion configured to provide an exit for the flowing liquid electrolyte in

Assignees

• Palo Alto Res Ct Inc

Inventors

• Desai Divyaraj
• Vedharathinam Vedasri
• Sheridan Martin Joseph
• Pattekar Ashish V
• Eldershaw Craig
• Padmarajan Rajesh Kumar
• Iftime Gabriel

Classifications

• H01M8/2455

  with liquid, solid or electrolyte-charged reactants · CPC title

• H01M8/22

  Fuel cells in which the fuel is based on materials comprising carbon or oxygen or hydrogen and other elements; Fuel cells in which the fuel is based on materials comprising only elements other than carbon, oxygen or hydrogen · CPC title

• H01M8/04283 Primary

  Supply means of electrolyte to or in matrix-fuel cells · CPC title

• H01M8/188

  by recharging of redox couples containing fluids; Redox flow type batteries · CPC title

• H01M8/023

  Porous and characterised by the material · CPC title