Minireview: Design of Cathode Structures for Solid-State Lithium–Air Batteries─Learning from Solid Oxide Fuel Cells

Solid-state lithium–air batteries (SSLABs) hold immense promise as energy storage and conversion devices for future electric vehicle applications as a result of their ultrahigh energy density and high safety. The air cathode is widely recognized as a crucial factor influencing the overall SSLAB performance. While significant advancements have been made in electrode materials and catalysts, gas diffusion and product accommodation remain big challenges, dictated by the structure of the air cathode. However, porous cathode structures have received little attention. In contrast, solid oxide fuel cells (SOFCs), which also involve gaseous reactants, have benefited from extensive research on gas diffusion electrodes, offering valuable insights for SSLAB development. In this review, we provide a critical discussion of the similarities and distinctions in the roles of gas electrodes in SOFCs and SSLABs, summarize current fabrication methods for gas electrodes for both types of cells, and compare key evaluation parameters and resulting cell performance across different structural designs. The aim of the review is to propose ideal gas electrode structures tailored for SSLABs, paving the way for the development of SSLABs with enhanced electrochemical performance.