# US 2023/0056450 A1 · Fuel cell regeneration

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- Number: US 2023/0056450 A1
- Document ID: US20230056450A1
- Status: Published application
- Kind: A1
- Application number: 17/888,194
- Filed: 2022-08-15
- Published: 2023-02-23
- Earliest claimed: 2021-08-19
- Assignees: Cummins Inc.
- Applicants: Cummins Inc.
- Inventors: Richard ANCIMER; Ashok KUMAR
- Web page: https://patentgrep.com/patent/US20230056450A1

## CPC

- H01M 8/04126: {Humidifying}
- H01M 8/04835: {of fuel cell reactants}
- H01M 8/04097: {with recycling of the reactants (H01M8/04119, H01M8/04104 take precedence)}
- H01M 8/04238: {Depolarisation}
- H01M 8/04305: {Modeling, demonstration models of fuel cells, e.g. for training purposes}
- H01M 8/04313: characterised by the detection or assessment of variables; characterised by the detection or assessment of failure or abnormal function
- H01M 8/04559: {of fuel cell stacks}
- H01M 8/04701: Temperature
- H01M 8/04753: {of fuel cell reactants}
- H01M 8/04828: Humidity; Water content
- H01M 8/0488: {of fuel cell stacks}
- H01M 8/04902: {of the individual fuel cell}
- H01M 8/0491: {of fuel cell stacks}
- H01M 2250/20: Fuel cells in motive systems, e.g. vehicle, ship, plane
- Y02E 60/50: Fuel cells
- Y02T 90/40: Application of hydrogen technology to transportation, e.g. using fuel cells
- H01M: PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02T: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION

## Abstract

The present disclosure generally relates to systems and methods for fuel cell regeneration after degradation.

## Claims

### Claim 1

A method of regenerating degradation of a fuel cell or fuel cell stack, comprising:
monitoring time spent operating the fuel cell or fuel cell stack above a threshold voltage,
determining a need for regenerating the degradation of the fuel cell or fuel cell stack,
regenerating the degradation of the fuel cell or fuel cell stack, and
ending regeneration of the fuel cell or fuel cell stack.

### Claim 2 (depends on 1)

The method of claim 1, wherein regenerating the fuel cell or fuel cell stack comprises regenerating reversible degradation of the the fuel cell or fuel cell stack.

### Claim 3 (depends on 1)

The method of claim 1, wherein regenerating the fuel cell or fuel cell stack comprises changing an operating current density of the fuel cell or fuel cell stack, implementing intermittent non-open circuit voltage operation, or increasing humidity in the fuel cell or fuel cell stack.

### Claim 4 (depends on 3)

The method of claim 3, wherein changing the operating current density comprises operating the fuel cell or fuel cell stack at an intermediate current density of about 0.2 A/cm2 to about 0.8 A/cm2, and
wherein increasing the humidity in the fuel cell or fuel cell stack comprises adjusting an excess fuel ratio or an excess air ratio of the fuel cell or fuel cell stack.

### Claim 5 (depends on 1)

The method of claim 1, wherein monitoring time spent operating the fuel cell or fuel cell stack above the threshold voltage comprises determining if the time spent is above a threshold time.

### Claim 6 (depends on 1)

The method of claim 1, wherein determining the need for regenerating the fuel cell or fuel cell stack comprises using a model to estimate a threshold time that the fuel cell or fuel cell stack can spend operating above the threshold voltage.

### Claim 7 (depends on 1)

The method of claim 1, wherein determining the need for regenerating the fuel cell or fuel cell stack comprises determining the time the fuel cell or fuel cell stack has spent operating at high voltage conditions and comparing the time the fuel cell or fuel cell stack has spent operating at high voltage conditions to a threshold time.

### Claim 8 (depends on 7)

The method of claim 7, wherein the time the fuel cell or fuel cell stack has spent operating at high voltage conditions may be a fixed time or a weighted time, and may be determined by a model based on an operating current density or an operating voltage of the fuel cell or fuel cell stack.

### Claim 9 (depends on 1)

The method of claim 1, wherein ending regeneration of the fuel cell or fuel cell stack is initiated after a fixed time.

### Claim 10 (depends on 1)

The method of claim 1, wherein ending regeneration of the fuel cell or fuel cell stack is based on a model or is based on the fuel cell or fuel cell stack voltage before and after regenerating the fuel cell or fuel cell stack, and
wherein the fuel cell or fuel cell stack voltage after regenerating the fuel cell or fuel cell stack does change from the fuel cell or fuel cell stack voltage before regeneration by more than about 1%.

### Claim 11 (depends on 1)

The method of claim 1, wherein regenerating the degradation of the fuel cell or fuel cell stack comprises increasing the recirculation rate of a fuel in the fuel cell or fuel cell stack, reducing a purge rate of the fuel, decreasing a operating temperature of the fuel cell or fuel cell stack, decreasing a operating pressure of the fuel cell or fuel cell stack, or adjusting an excess air ratio or an excess fuel ratio of the fuel cell or fuel cell stack.

### Claim 12 (depends on 1)

The method of claim 1, wherein the threshold voltage is about 0.7 V to about 0.85 V.

### Claim 13 (depends on 5)

The method of claim 5, wherein the threshold time is about 25 hours.

### Claim 14

A fuel cell or fuel cell stack that operates at an operating current density, an operating voltage, and with an excess air ratio, comprising:
a fuel that flows through an anode inlet of the fuel cell or fuel cell stack at a first flow rate,
an oxidant that flows through a cathode inlet of the fuel cell or fuel cell stack at a second flow rate,
wherein an operating time of the fuel cell or fuel cell stack is monitored if the operating voltage is higher than a threshold voltage, and
wherein the fuel cell or fuel cell stack undergoes regeneration when required.

### Claim 15 (depends on 17)

The fuel cell or fuel cell stack of claim 17, wherein the regeneration of the fuel cell or fuel cell stack comprises changing the operating current density of the fuel cell or fuel cell stack, changing the operating voltage, decreasing the first flow rate or decreasing the second flow rate.

### Claim 16 (depends on 17)

The fuel cell or fuel cell stack of claim 17, wherein the regeneration of the fuel cell or fuel cell stack comprises regenerating reversible degradation of the fuel cell or fuel cell stack.

### Claim 17 (depends on 15)

The fuel cell or fuel cell stack of claim 15, wherein the operating voltage is decreased by implementing intermittent non-open circuit voltage operation,
wherein the operating current density of the fuel cell or fuel cell stack is changed to an intermediate current density of about 0.2 A/cm2 to about 0.8 A/cm2,
wherein the first flow rate or the second flow rate is decreased by adjusting the anode stoichiometry at the anode inlet or adjusting the cathode stoichiometry at the cathode inlet respectively, and
wherein if the time spent operating the fuel cell or fuel cell stack above the threshold voltage is above a threshold time, the operating current density of the fuel cell or fuel cell stack is increased, the operating voltage is decreased, the first flow rate is decreased or the second flow rate is decreased to regenerate the fuel cell or fuel cell stack.

### Claim 18 (depends on 14)

The fuel cell or fuel cell stack of claim 14, wherein the threshold voltage is about 0.7V to about 0.85 V.

### Claim 19 (depends on 17)

The fuel cell or fuel cell stack of claim 17, wherein the threshold time is about 25 hours.

### Claim 20 (depends on 14)

The fuel cell or fuel cell stack of claim 14, wherein a model is used to determine when to initiate the regeneration or when to stop the regeneration.