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Renewable energy sources such as solar and wind power are important for the future energy supply chain, but require suitable energy storage and conversion technologies due to the nature of the intermittency in electricity generation. Solid oxide cell (SOC) is such a highly efficient device which can store the renewable electricity into chemical energy of fuels under solid oxide electrolysis cell (SOEC) operation mode and to regenerate the electricity using the stored fuels under solid oxide fuel cell (SOFC) operation mode. However, there are significant technological barriers for the commercial viability of SOCs, one of them is the significant performance degradation under the SOEC mode. This paper reviews critically the durability and performance degradation issues of SOCs under SOEC operation conditions and the emphasis is mainly on the physical, chemical and microstructural processes that cause the degradation and their dependence on the operation conditions and nature of the oxygen and hydrogen electrodes and electrolyte materials. The degradation due to the contaminants such as chromium, boron and silica from metallic interconnect, borosilicate glass sealants and/or raw materials is also reviewed. The development of high performance and durable SOECs technology is discussed and based on the observed evidences, the sequence of the delamination processes at the oxygen electrode/YSZ electrolyte has been proposed.

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Solid oxide cells (SOCs) are highly efficient and environmentally benign devices that can be used to store renewable electrical energy in the form of fuels such as hydrogen in the solid oxide electrolysis cell mode and regenerate electrical power using stored fuels in the solid oxide fuel cell mode. Despite this, insufficient long-term durability over 5–10 years in terms of lifespan remains a critical issue in the development of reliable SOC technologies in which the surface segregation of cations, particularly strontium (Sr) on oxygen electrodes, plays a critical role in the surface chemistry of oxygen electrodes and is integral to the overall performance and durability of SOCs. Due to this, this review will provide a critical overview of the surface segregation phenomenon, including influential factors, driving forces, reactivity with volatile impurities such as chromium, boron, sulphur and carbon dioxide, interactions at electrode/electrolyte interfaces and influences on the electrochemical performance and stability of SOCs with an emphasis on Sr segregation in widely investigated (La,Sr)MnO3 and (La,Sr)(Co,Fe)O3−δ. In addition, this review will present strategies for the mitigation of Sr surface segregation. Graphic Abstract

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