Recent Progress in Applying In Situ/Operando Characterization Techniques to Probe the Solid/Liquid/Gas Interfaces of Li–O₂ Batteries

Lithium–oxygen (Li–O 2 ) batteries have attracted intensive attention owing to their potential to provide gravimetric energy density 2–5 times that of conventional Li‐ion batteries. However, Li–O 2 technology suffers from poor cycle life, low rate capability, and poor round‐trip efficiency. Insights into the Li–O 2 reaction mechanisms are prerequisites to breakthroughs in Li–O 2 battery technology. Here, recent progress in applying in situ/operando characterization techniques to probe the solid/liquid/gas interfaces of Li–O 2 batteries is reviewed. The working principle and experimental designs of these in situ/operando techniques are discussed, the critical mechanistic insights revealed, and how these studies advance the fundamental development of Li–O 2 batteries considered.