Insight of Redox Shuttling Inhibition for a Polyethylene Oxide/TiO2/Polypropylene Separator of Li–O2 Battery with Enhanced Cycling Stability

Although a redox mediator (RM) strategy can lower the overpotential of Li–O2 batteries (LOBs), the redox shuttling results in an undesired RM consumption and a continued decomposition of lithium metal anode, leading to a poor cycling stability. In this work, a hybrid inorganic–organic composite separator based on polyethylene oxide/TiO2/polypropylene (PEO/TiO2/PE) in LOBs has been reported for the first time, which aims to suppress the RM shuttling. The influences of TiO2 nanoparticles and PEO on battery performance are systematically investigated. Benefiting from the synergistic advantages, a LOB with PEO/TiO2/PE separator displays stable cyclability, considerable rate performance, and good reversibility. Additionally, the mechanism of inhibiting shuttling effect by this composite separator is proposed. We hope that this work can give an insight into the development of multiple functional separators for Li anode protection in LOBs.