Oxidative Decomposition of Off‐Cathode Discharge Deposits During Charging in Li–O ₂ Secondary Batteries

Although lithium–oxygen batteries (LOBs) offer an exceptionally high theoretical gravimetric energy density, the long‐standing trade‐off between high capacity and cyclability remains unsolved. In particular, discharge via the solution pathway, which enables three‐dimensional deposition of Li 2 O 2 within the porous cathode and thus high capacity, has generally been regarded as detrimental to rechargeability because discharge products can also be deposited onto electrochemically isolated off‐cathode sites. Here, we provide direct and unambiguous experimental evidence that such off‐cathode discharge products—formed on electrically insulating polyphenylene sulfide (PPS) fibers interwoven with conductive carbon fibers—are completely decomposed during charging in an amide‐based electrolyte. This finding overturns the prevailing assumption that solution‐mediated discharge inherently compromises rechargeability. Our findings indicate that, with appropriate control of cathode architecture and electrolyte chemistry, the solution pathway may be compatible with reversible charging. This insight reshapes the fundamental understanding of Li 2 O 2 redox chemistry in LOBs.