The interface between electrolyte and cathode is a primary factor affecting the performance of solid oxide fuel cells (SOFCs). Enhancing the chemical compatibility of the interface, fortifying the charge conduction, and mitigating the interdiffusion of elements between the interfaces are imperative to optimize the performance of SOFC single-cells and ensure a long-term operational stability. This review represents the methodologies used to enhance the interface between electrolyte and cathode in recent years. These methodologies encompass the optimization of cathode composition and structure, the design and construction of multilayer composite electrolyte, and interfacial reinforcement methods. These approaches serve as a valuable reference for SOFC development and application.

At the cathode layer, a dense electrolyte and a porous electrolyte backbone are constructed. A solution infiltration technique is utilized to prepare highly active nano-cathodes within the porous electrolyte backbone, thereby eliminating the macroscopic interface between the electrolyte and the cathode. Advanced coating techniques and infiltration technique are employed to modify the cathode surface, thereby enhancing cathode electrochemical performance and single-cell operational durability. The development of novel cathode materials, regulation of component ratios within composite cathodes, and the addition of negative thermal expansion materials prove effective in enhancing the thermal expansion compatibility of the cathode. The thermal-expansion offset enhances long-term electrode durability and ORR activity.

At the electrolyte layer, constructing multi-layer electrolyte films and optimizing the structure of single cell enhance performance and reduce degradation. Multi-layer composite structures improve an electrolyte reliability and a cathode interface chemical compatibility. However, the preparation becomes a challenge and primarily relies on advanced coating technologies. Low-cost, high-density coating technologies are urgently needed, and a hydrothermal in-situ growth technique emerges, thus reducing production costs, while enhancing single-cell performance and long-term durability.

At the electrolyte-cathode interface, the contact between the electrolyte and the cathode directly affects the interface resistance, oxygen ion conduction, and interface bonding strength. Therefore, interface reinforcement can effectively improve the energy efficiency and stability of single cells. The dense nanostructure functional layer (NFL) overcomes the physical limitations of the porous cathode-dense electrolyte interface, thus enhancing single-cell performance, interfacial bonding, and long-term durability.

This review summarizes some research work related to the interface between the electrolyte and cathode in SOFCs, thus providing a reference for the development of high-performance and long-term durability. This review also provides a reference for SOEC research and development since the materials and structure of solid oxide electrolysis cells (SOECs) are similar to those of SOFCs.