New Insight in Understanding Oxygen Reduction and Evolution in Solid-State Lithium–Oxygen Batteries Using an in Situ Environmental Scanning Electron Microscope

Via
designing a facile microscale all-solid-state lithium–oxygen
battery system constructed in an environmental scanning electron microscope,
direct visualization of discharge and charge processes of the lithium–oxygen
battery is achieved. Different morphologies of the discharge product
are observed, including a sphere, conformal film, and red-blood-cell-like
shape, with a particle size up to 1.5 μm; whereas upon charge,
the decomposition initiates at their surface and continues along a
certain direction, instead of from the contact point at the electrode.
These new findings indicate that the electron and lithium ion conductivities
of Li2O2 could support the growth and decomposition
of the discharge product in our system. In addition, our results indicate
that various morphologies of Li2O2 arise from
the different current density and surface chemistry of CNT, and the
growth and decomposition of the particle are related to the uneven
distribution of the ionic and electronic conductivities of Li2O2.