Thermal-expansion offset for high-performance fuel cell cathodes.

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Date: Mar. 11, 2021
From: Nature(Vol. 591, Issue 7849)
Publisher: Nature Publishing Group
Document Type: Report
Length: 6,994 words
Lexile Measure: 1660L

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Abstract :

One challenge for the commercial development of solid oxide fuel cells as efficient energy-conversion devices is thermo-mechanical instability. Large internal-strain gradients caused by the mismatch in thermal expansion behaviour between different fuel cell components are the main cause of this instability, which can lead to cell degradation, delamination or fracture.sup.1-4. Here we demonstrate an approach to realizing full thermo-mechanical compatibility between the cathode and other cell components by introducing a thermal-expansion offset. We use reactive sintering to combine a cobalt-based perovskite with high electrochemical activity and large thermal-expansion coefficient with a negative-thermal-expansion material, thus forming a composite electrode with a thermal-expansion behaviour that is well matched to that of the electrolyte. A new interphase is formed because of the limited reaction between the two materials in the composite during the calcination process, which also creates A-site deficiencies in the perovskite. As a result, the composite shows both high activity and excellent stability. The introduction of reactive negative-thermal-expansion components may provide a general strategy for the development of fully compatible and highly active electrodes for solid oxide fuel cells. Highly active but durable perovskite-based solid oxide fuel cell cathodes are realized using a thermal-expansion offset, achieving full thermo-mechanical compatibility between the cathode and other cell components.

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Gale Document Number: GALE|A660673927