Addressing redox shuttling in Li-O2 batteries: Mechanistic insights by synchrotron X–ray tomography

In situ characterization on interface stability has been hardly tried in redox mediator (RM)-involved Li-O2 battery thus far. Here, benzyltriethylammonium iodide (BTEAI) can act as a self-defensive RM in the electrolyte LiTFSI/TEGDME to enhance the reaction kinetics and increase the cycling stability by suppressing the redox shuttling. I- effectively reduces the charging overpotential by changing decomposition route for Li2O2. BTEA+ can facilitate LiTFSI decomposition in the electrolyte, and participate in formation of an organic–inorganic composite SEI-contained layer on Li anode. Moreover, for the first time, non-destructive synchrotron X-Ray tomography is used to investigate the mechanism of suppressing shuttle effect by monitoring the morphological evolution of electrodes interface. This work provides an insight into the development of functional RM and in situ protection strategies for Li anodes in Li-O2 batteries.