Effective ceramic sealing agents for solid oxide cells by low temperature curing below 200 °C

Abstract

Crystallized glass as a sealing agent for high-temperature solid oxide cells (SOCs) such as fuel cells and electrolyzers must first be melted at a high temperature and vitrified. Such high temperature can cause stress due to thermal expansion. The applicability is evaluated for ceramic sealing agents (CSAs) that do not require a high-temperature melting treatment and that can exhibit sealing properties by low temperature curing at 180 °C. In the evaluation of the bulk body of the CSAs, there is no change in physical properties and performance in a wide temperature range between a low temperature for curing and a high temperature for SOC operation. Moreover, in the CSA adhesion test with SUS430, almost no gas leakage occurs even after 150 heat-cycles (each cycle was 1 h at room temperature followed by 1 h at 800 °C) by optimizing the thermal expansion coefficient of the CSA. An SOC using the CSA as gas sealing material exhibits almost the same open-circuit voltage as the theoretical value and shows a stable fuel cell operation for 100 h without degradation. These results indicate that CSAs can be a candidate for the sealing material of SOCs in a wide temperature range.