System and method for MEA conditioning in a fuel cell

Patent metadata

Field	Value
Publication number	US-10784527-B2
Application number	US-201715846777-A
Country	US
Kind code	B2
Filing date	Dec 19, 2017
Priority date	Dec 19, 2017
Publication date	Sep 22, 2020
Grant date	Sep 22, 2020

Abstract

A controller-executed method for conditioning a membrane electrode assembly (MEA) in a fuel cell for use in a fuel cell stack includes humidifying a fuel inlet to the stack to a threshold relative humidity level, and maintaining a current density and cell voltage of the fuel cell at a calibrated current density level and hold voltage level, respectively, via the controller in at least one voltage recovery stage. The recovery stage has a predetermined voltage recovery duration. The method includes measuring the cell voltage after completing the predetermined voltage recovery duration, and executing a control action with respect to the fuel cell or fuel cell stack responsive to the measured cell voltage exceeding a target voltage, including recording a diagnostic code via the controller indicative of successful conditioning of the MEA. A fuel cell system includes the fuel cell stack and controller.

First claim

What is claimed is:

1. A method for conditioning a membrane electrode assembly (MEA) in a fuel cell for a fuel cell stack, the method comprising:
humidifying a fuel inlet to the fuel cell stack to a threshold relative humidity level;
controlling, via a controller in a load cycling stage, operation of the fuel cell to cycle a current density of the fuel cell within a calibrated current density range;
controlling, after the load cycling stage via the controller in voltage recovery stage having a predetermined voltage recovery duration, operation of the fuel cell to hold the current density and a cell voltage of the fuel cell substantially constant at a calibrated current density level and a calibrated hold voltage level, respectively;
measuring the cell voltage via a voltage sensor after completing the predetermined voltage recovery duration; and
executing a control action with respect to the fuel cell or fuel cell stack, including:
responsive to the measured cell voltage exceeding a target voltage, recording a diagnostic code in a memory device via the controller indicative of successful conditioning of the MEA, and
responsive to the measured cell voltage not exceeding the target voltage, repeating the load cycling stage and the voltage recovery stage and then determining again if the measured cell voltage exceeds the target voltage.

2. The method of claim 1 , wherein the calibrated current density level is in a range of 0.5 to 1 A/cm2 and the calibrated hold voltage level is in a range of 0 to about 0.4 volts.

3. The method of claim 1 , wherein the voltage recovery duration is at least 10 minutes in a single continuous step or in multiple steps.

4. The method of claim 3 , wherein the voltage recovery duration is in a range of 10-30 minutes in the single continuous step or in the multiple steps.

5. The method of claim 1 , wherein the voltage recovery stage includes a plurality of voltage recovery stages, and the load cycling stage includes a plurality of load cycling stages interleaved with the voltage recovery stages.

6. The method of claim 1 , wherein the calibrated current density range of the load cycling stage has a lower limit and an upper limit that both exceed the calibrated current density level used during the voltage recovery stage.

7. The method of claim 6 , wherein the lower limit is at least twice the calibrated current density level used during the voltage recovery stage.

8. The method of claim 7 , wherein the calibrated current density level used during the voltage recovery stage is about 0.6 A/cm2, the lower limit is about 1.5 A/cm2, and the upper limit is about 2 A/cm2.

9. The method of claim 1 , wherein the voltage recovery stage is conducted at a temperature in a range of ambient to about 50° C.

10. The method of claim 1 , wherein the at least one voltage recovery stage is executed at a temperature of at least about 80° C., and includes:
supplying hydrogen to an anode of the fuel cell;
supplying nitrogen to a cathode of the fuel cell; and
maintaining the cell voltage of the fuel cell at the calibrated hold voltage level of about 0 to 0.2 V.

11. A fuel cell system comprising:
a fuel cell stack having a plurality of fuel cells, each of the fuel cells having a respective membrane electrode assembly (MEA); and
a controller having memory on which is recorded instructions for breaking-in and/or conditioning the MEAs of the respective fuel cells, wherein execution of the instructions causes the controller to:
humidify a fuel inlet to the fuel cell stack to a threshold relative humidity level;
operate each of the fuel cells in a load cycling stage to cycle a respective current density of the fuel cell within a calibrated current density range;
after the load cycling stage, operate each of the fuel cells to maintain the respective current density and a respective cell voltage of each of the fuel cells substantially constant at a calibrated current density level and a calibrated hold voltage level, respectively, using voltage recovery stage having a predetermined voltage recovery duration;
measure the cell voltages of the fuel cells after completing the predetermined voltage recovery duration; and
execute a control action with respect to the fuel cell or fuel cell stack, including:
responsive to the measured cell voltages exceeding a target voltage, recording a diagnostic code indicative of successful conditioning of the MEA, and
responsive to one or more of the measured cell voltages not exceeding the target voltage, repeating the load cycling and voltage recovery stages for each of the fuel cells with the respective measured cell voltage thereof not exceeding the target voltage.

12. The fuel cell system of claim 1 , wherein the calibrated current density level is in a range of 0.3 to about 1 A/cm2 and the calibrated hold voltage level is in a range of 0 to about 0.4 volts.

13. The fuel cell system of claim 1 , wherein the voltage recovery duration is at least 10 minutes in a single continuous step or in multiple steps.

14. The fuel cell system of claim 13 , wherein the voltage recovery duration is in a range of 10-30 minutes in the single continuous step or the multiple steps.

15. The fuel cell system of claim 13 , wherein the at least one voltage recovery stage includes a plurality of voltage recovery stages, and the load cycling stage includes a plurality of load cycling stages interleaved with the voltage recovery stages.

16. The fuel cell system of claim 15 , wherein the calibrated current density range has a lower limit and an upper limit that both exceed the calibrated current density level used during the at least one voltage recovery stage.

17. The fuel cell system of claim 16 , wherein the lower limit of the calibrated current density range is at least twice the calibrated current density level used during the voltage recovery stage.

18. The fuel cell system of claim 17 , wherein the calibrated current density level used during the voltage recovery stage is about 0.6 A/cm2, the lower limit is about 1.5 A/cm2, and the upper limit is about 2 A/cm2.

19. The fuel cell system of claim 11 , wherein the voltage recovery stage is conducted at a temperature range of ambient to about 50° C.

20. The fuel cell system of claim 11 , wherein the voltage recovery stage is executed at a temperature of at least about 80° C., and includes instructions that cause the controller to:
supply hydrogen to an anode of the fuel cell;
supply nitrogen to a cathode of the fuel cell; and
maintain the calibrated hold voltage level to about 0 to 0.2 V.

Assignees

• Gm Global Tech Operations Llc

Inventors

• Kumaraguru Swaminatha P
• Zhang Jingxin
• Ramaswamy Nagappan
• Rapaport Pinkhas A

Classifications

• H01M8/043

  applied during specific periods · CPC title

• H01M8/04835

  of fuel cell reactants · CPC title

• H01M8/0491

  of fuel cell stacks · CPC title

• H01M8/0488

  of fuel cell stacks · CPC title

• H01M8/04589

  of fuel cell stacks · CPC title