Research Progress of Double-layer Electrolyte and Its Preparation Technology for Intermediate Temperature Solid Oxide Fuel Cells

Solid oxide fuel cell (SOFC) is a new type of energy conversion device in which electrolyte is one of its core components. In order to realize the development of SOFC battery commercialization, the key factor is to make SOFC from high to intlermediate temperature, and the solid electrolyte at intermediate temperature shows many shortcomings, such as the internal generation of electronic conductance under low oxygen partial pressure of CeO₂-based electrolyte, which reduces the output performance of the battery, the resistance of the ZrO₂-based electrolyte increases sharply at intermediate temperature, the interface reaction between the LaGaO₃-based electrolyte and the electrode, and the reduction of the Bi₂O₃-based electrolyte to metallic bismuth in a reducing atmosphere will limit the application of the material. In order to solve these existing problems, a double-layer electrolyte is constructed on this basis. The double-layer electrolyte can block the electron conduction of the CeO₂-based electrolyte, block the reduction of the electrolyte to metal under the Bi₂O₃-based reducing atmosphere, and the interfacial diffusion reaction between the LaGaO₃-based electrolyte and the electrode, etc. problem, thereby improving the output performance of the battery. The application of intermediate temperature can also be realized by making ZrO₂-based electrolyte into thin film by thin film fabrication technology. In this paper, the development of double-layer electrolytes for intermediate-temperature solid oxide fuel cells in the widely studied DOC/doped Bi₂O₃, doped ZrO₂/DOC, and ZrO₂/stabilized Bi₂O₃ systems is summarized, and the preparation techniques of electrolyte films (including pulsed laser deposition, magnetron sputtering, casting and some chemical deposition methods), bilayer electrolytes made by thin film fabrication technology are widely used in solid fuel cells. Finally, the development trend of electrolyte thinning and preparation of bilayer electrolytes in SOFC is prospected.