Anisotropic cte lsm for sofc cathode

Abstract

An anisotropic coefficient of thermal expansion (CTE) cathode of a solid oxide fuel cell (SOFC) is formed by placing a layer of perovskite powder between two platens, and sintering the layer while applying pressure to the platens, thereby forming the anisotropic CTE cathode. The perovskite can be lanthanum strontium manganite (LSM).

Description

RELATED APPLICATION(S)[0001]This application claims the benefit of U.S. Provisional Application No. 61 / 335,085, filed on Dec. 31, 2009. The entire teachings of the above application are incorporated herein by reference.BACKGROUND OF THE INVENTION[0002]A fuel cell is a device that generates electricity by a chemical reaction. Typically, in a fuel cell, an oxygen gas, such as O2, is reduced to oxygen ions (O2−) at the cathode, and a fuel gas, such as H2, is oxidized with the oxygen ions to form water at the anode. Among various types of fuel cells, solid oxide fuel cells (SOFCs) use hard ceramic compounds of metal oxides (e.g., calcium or zirconium oxides) to form components of the fuel cell, such as, for example, the anode, cathode, electrolyte, and interconnect. Fuel cells are generally designed as stacks, whereby subassemblies, each including a cathode, an anode and a solid electrolyte between the cathode and the anode, are assembled in series by locating an electrical interconnect...

AI Technical Summary

Benefits of technology

[0009]This invention has many advantages, including maintaining low thermal mismatch stresses in the cell and stack of a SOFC. As will be further described below, it has been found that compression of LSM during heat treatment lowers the CTE of the LSM, thereby minimizing or significantly reducing failure of SOFCs that employ LSM during use.

Problems solved by technology

Where there is sufficient mismatch of CTE among the layers, cooling, or any temperature change that is too rapid, can cause fracture and consequent failure of the SOFC.

The difference between the CTEs of the LSM and YSZ materials would generate a large thermal mismatch stress in the SOFC.

On the other hand, it is often undesirable to use an LSM with Sr content lower than 0.2, due to diminished electrochemical performance.

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