Advancements and challenges in lithium–oxygen battery technology: A comprehensive overview

Lithium–oxygen (Li–O₂) batteries are attractive beyond-lithium-ion systems because oxygen is stored outside the positive electrode and the Li₂O₂-forming reaction provides a theoretical specific energy of approximately 3500 Wh kg⁻¹ when oxygen is excluded from the carried mass. This review critically examines oxygen reduction/evolution mechanisms, cathode architecture, electrolytes, catalysts, redox mediators, Li-metal-anode protection, and discharge-product regulation. Particular attention is given to Li₂CO₃ suppression, Li₂O₂/LiOH pathway selection, morphology-controlled deposition, and external-field-assisted concepts using light, ultrasound, piezoelectricity, magnetostriction, and magnetic heating. Catalyst classes are compared in terms of activity, durability, cost, and product selectivity rather than by a single capacity metric. Recent flexible and solid-state interface designs reported during 2020–2025 are also incorporated. The analysis shows that the large theoretical advantage of Li–O₂ chemistry is substantially reduced at the cell level by oxygen-management hardware, electrolyte and protective-layer mass, limited areal capacity, parasitic chemistry, and recharge overpotential. Practical progress therefore requires coordinated control of the oxygen cathode, electrolyte, discharge product, and Li-metal interface. The review concludes with experimentally testable priorities for lowering charge voltage, suppressing carbonate and singlet-oxygen chemistry, stabilizing lithium, and reporting realistic full-cell metrics.