High temperature air purge of solid oxide fuel cell anode electrodes
AssigneeBloom Energy Corporation
InventorsSwaminathan Venkataraman, Emad El Batawi, Matthias Gottmann, Tad Armstrong, Manoj Pillai, Padiadpu Shankara Anantha, Vijay Radhakrishnan, Mohamed Sharif, Pradhiba Mohan, Rakesh Kandiboina
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Abstract
A method of operating a solid oxide fuel cell (SOFC) system which contains a plurality of SOFCs having cermet anode electrodes includes operating the SOFC system above 760° C. to generate electricity and intentionally oxidizing the cermet anode electrodes at a temperature of at least 760° C. when the SOFC system stops operating to generate electricity.
Claims13
A method of operating a solid oxide fuel cell (SOFC) system comprising a plurality of SOFCs having cermet anode electrodes, comprising:
- operating the SOFC system above 760° C. to generate electricity;
- and
- intentionally oxidizing the cermet anode electrodes at a temperature of at least 760° C. when the SOFC system stops operating to generate electricity, wherein:
- the plurality of SOFCs are located in a SOFC stack;
- and
- the step of intentionally oxidizing the cermet anode electrodes comprises providing an air purge;
- the air purge is provided in response to an emergency stop of the SOFC system;
- and
- the air purge is provided if a measured temperature of the SOFC stack is equal to or greater than 760° C. after the emergency stop of the SOFC system, and the SOFC system operation is not restarted.
A method of restoring electrical conductivity of a solid oxide fuel cell having a cermet anode electrode, comprising:
- oxidizing the anode electrode at a temperature below 760° C. and reducing the anode electrode;
- re-oxidizing the anode electrode at a temperature above 760° C. after reducing the anode electrode;
- and
- re-reducing the anode electrode after re-oxidizing the anode electrode;
- wherein:
- an electrical contact resistivity of the anode electrode after the step of reducing is lower than the electrical contact resistivity of the anode electrode prior to the step of oxidizing the anode electrode;
- the electrical contact resistivity of the anode electrode after the step of re-reducing is higher than the electrical contact resistivity of the anode electrode after the step of reducing;
- the steps of oxidizing and re-oxidizing the anode electrode comprise converting a metallic phase of the cermet into a metal oxide phase;
- the cermet anode electrode comprises a nickel containing metallic phase and at least one of a doped ceria and a stabilized zirconia ceramic phase;
- converting the metallic phase of the cermet into the metal oxide phase comprises converting the nickel into nickel oxide;
- the steps of reducing and re-reducing convert the nickel oxide back into the nickel;
- the steps of oxidizing and reducing the cermet anode electrode disrupt a nickel electrically conductive percolation network in the cermet anode electrode;
- and
- the steps of re-oxidizing and re-reducing restore the nickel electrically conductive percolation network in the cermet anode electrode.
Dependencies are inferred from the claim text.