# US 8,569,067 B2 · Method and apparatus for evaluating ex-situ chemical degradation of membranes

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- Number: US 8,569,067 B2
- Document ID: US8569067B2
- Status: Granted
- Kind: B2
- Application number: 13/327,051
- Filed: 2011-12-15
- Published: 2013-06-20
- Granted: 2013-10-29
- Earliest claimed: 2011-12-15
- Assignees: Nissan North America, Inc.
- Applicants: Rameshwar Yadav; Kevork Adjemian
- Inventors: Rameshwar Yadav; Kevork Adjemian
- Web page: https://patentgrep.com/patent/US8569067B2

## CPC

- H01M 8/1039: halogenated, e.g. sulfonated polyvinylidene fluorides
- H01M 8/008: Disposal or recycling of fuel cells
- H01M 2008/1095: {Fuel cells with polymeric electrolytes}
- Y02E 60/50: Fuel cells
- Y02W 30/84: Recycling of batteries or fuel cells
- Y10T 436/193333: In aqueous solution
- 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
- Y02W: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
- Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION

## Abstract

Disclosed herein are methods and devices for evaluating ex-situ chemical degradation of fuel cell membranes. One embodiment of a method for evaluating ex-situ chemical degradation of a membrane comprises submerging a membrane in Fenton solution in a reaction vessel with a non-reactive weight configured to maximize exposure of the membrane to the Fenton solution, sealing the reaction vessel, heating the reaction vessel at a fixed rate to a predetermined temperature, holding the reaction vessel at the predetermined temperature for a predetermined test period, cooling the reaction vessel to room temperature, removing the membrane and analyzing the Fenton solution for fluoride ions.

## Claims

### Claim 1

A method for evaluating ex-situ chemical degradation of a membrane comprising the steps of:
submerging a membrane in an aqueous hydrogen peroxide solution and ferrous iron (Fenton solution) in a reaction vessel with a non-reactive weight configured to maximize exposure of the membrane to free hydroxyl radicals produced from the Fenton solution;
tightly sealing the reaction vessel;
heating the Fenton solution in the reaction vessel at a fixed rate to a predetermined temperature;
holding the Fenton solution in the reaction vessel at the predetermined temperature for a predetermined test period;
cooling the Fenton solution in the reaction vessel to room temperature;
analyzing the Fenton solution for fluoride ions released from the membrane due to exposure to the free hydroxyl radicals; and
determining a fluoride emission rate from the fluoride ions to obtain membrane degradation.

### Claim 2 (depends on 1)

The method of claim 1, further comprising removing the membrane and the non-reactive weight from the Fenton solution prior to analyzing.

### Claim 3 (depends on 1)

The method of claim 1, wherein the non-reactive weight comprises two magnets coated in a non-reactive coating placed on opposing sides of the membrane.

### Claim 4 (depends on 1)

The method of claim 1, wherein the reaction vessel has a single sealable opening providing access to a cavity of the reaction vessel.

### Claim 5 (depends on 1)

The method of claim 1, wherein heating the reaction vessel at a fixed rate is performed in an oven.

### Claim 6 (depends on 5)

The method of claim 5, wherein holding the predetermined temperature is performed in the oven.

### Claim 7 (depends on 1)

The method of claim 1, wherein the predetermined temperature is 80° C. or greater.

### Claim 8 (depends on 1)

The method of claim 1, wherein analyzing the Fenton solution is performed with a meter having an ion selective electrode.

### Claim 9 (depends on 1)

The method of claim 1, wherein the steps are performed on a plurality of membranes, each membrane submerged in Fenton solution in a respective reaction vessel with a respective non-reactive weight.

### Claim 10 (depends on 9)

The method of claim 9, wherein each of the plurality of membranes are identical and the predetermined test period is different for each of the plurality of membranes.

### Claim 11 (depends on 9)

The method of claim 9, wherein the plurality of membranes are each different and the predetermined test period is the same for each of the plurality of membranes.

### Claim 12

A method for evaluating ex-situ chemical degradation of a membrane comprising the steps of:
placing two magnets coated in a non-reactive coating on opposing sides of the membrane, each magnet having an arcuate surface that directly contacts the membrane to minimize a contact area;
submerging the membrane with the magnets in an aqueous solution of hydrogen peroxide and iron catalyst in a reaction vessel, the magnets maximizing exposure of the membrane to free hydroxyl radicals produced from the aqueous solution;
tightly sealing the reaction vessel;
heating the aqueous solution in the reaction vessel at a fixed rate to a predetermined temperature;
cooling the aqueous solution in the reaction vessel to room temperature after a predetermined test period has lapsed;
analyzing the aqueous solution for fluoride ions released from the membrane due to exposure to the free hydroxyl radicals; and
determining a fluoride emission rate from the fluoride ions to obtain membrane degradation.

### Claim 13 (depends on 12)

The method of claim 12, wherein each magnet is cylindrical in cross-section.

### Claim 14 (depends on 12)

The method of claim 12, wherein the reaction vessel has a single sealable opening providing access to a cavity of the reaction vessel.

### Claim 15 (depends on 12)

The method of claim 12, wherein the predetermined temperature is 80° C. or greater.

### Claim 16 (depends on 12)

The method of claim 12, wherein analyzing the aqueous solution is performed with a meter having an ion selective electrode.

### Claim 17 (depends on 12)

The method of claim 12, wherein the steps are performed on a plurality of membranes, each membrane submerged in aqueous solution in a respective reaction vessel with respective magnets.

### Claim 18

A method for evaluating ex-situ chemical degradation of a membrane comprising the steps of:
submerging a plurality of membranes in an aqueous solution of hydrogen peroxide and iron catalyst, each membrane submerged in a respective reaction vessel to expose the membrane to free hydroxyl radicals produced from the aqueous solution;
tightly sealing each reaction vessel;
heating at a same time the aqueous solution in each reaction vessel at a fixed rate to a predetermined temperature;
after a first elapsed time, removing one of the respective reaction vessels from the heat and cooling the aqueous solution to room temperature;
after a second elapsed time, removing another of the respective reaction vessels from the heat and cooling the aqueous solution to room temperature, and continuing removing each reaction vessel after a different elapsed time until the plurality of membranes are cooled;
analyzing the aqueous solution of each reaction vessel for fluoride ions released from the membrane due to exposure to the free hydroxyl radicals; and
determining a fluoride emission rate from the fluoride ions to obtain membrane degradation for each of the plurality of membranes.

### Claim 19 (depends on 18)

The method of claim 18, wherein a non-reactive weight is attached to each membrane, each non-reactive weight configured to maximize exposure of the membrane.

### Claim 20 (depends on 19)

The method of claim 19, wherein the non-reactive weight comprises two magnets coated in a non-reactive coating placed on opposing sides of the membrane, each magnet having an arcuate surface as a contact surface.