Reacquainting the Sudden-Death and Reaction Routes of Li-O Batteries by Ex Situ Observation of LiO Distribution Inside a Highly Ordered Air Electrode.

The unclear LiO distribution inside an air electrode stems from the difficulty of conducting observation techniques inside a porous electrode. In this work, an integrated air electrode is prepared with highly ordered channels. The morphological composition and distribution of LiO inside the real air electrode are clearly observed for the first time. The results show that the toroidal LiO is constrained by the channel size and exhibits a larger diameter on the separator side at high currents. In contrast to the reported single-factor experiments, the coupling effects of charge transfer impedance and concentration polarization on sudden death are analyzed in-depth at low and high currents. The growth model suggests that toroidal LiO exhibits a high dependence on the electrode surface structure. A new route is proposed in which the LiO/electrode interface of a toroid is controlled partially by the second single-electron reduction.