Lithium–Oxygen Batteries: Fundamental and Practical Considerations

Lithium–oxygen batteries (LOBs) have emerged as a compelling next-generation energy storage technology for aviation due to their high theoretical energy densities and the use of abundant oxygen as a cathode reactant. Unlike conventional lithium-ion batteries (LIBs), which are limited by the mass of intercalation materials and one-electron redox processes, LOBs leverage multielectron oxygen redox chemistry to achieve gravimetric energy density exceeding 3,500 Wh kgLi2O2–1 based on lithium peroxide and up to 5,200 Wh kgLi2O–1 for lithium oxide. However, practical implementation of LOBs remains constrained by significant challenges including low round-trip efficiency and low system-level energy density, the latter arising from the need for oxygen management in both open and closed architectures. The electrolyte viscosity, oxygen solubility, volatility, and chemical stability toward reactive oxygen species can profoundly influence discharge capacity, rate capability, reversibility, and long-term stability. This review provides a comprehensive assessment of recent progress in LOBs, focusing on electrolyte designs, electrode engineering, and strategies for mitigating parasitic reactions as well as the interplay between material-level properties and system-level constraints, offering a critical perspective on the path toward realizing high-energy, practical LOB systems.