MOF-Based Separator in an Li–O₂ Battery: An Effective Strategy to Restrain the Shuttling of Dual Redox Mediators

Tuning the electrochemical formation/decomposition of Li 2 O 2 from the circumscribed surface pathways to the solution ones, the dual redox mediator (RM) strategy largely promotes the discharge capacity and reduces the charge overpotential in aprotic Li–O 2 batteries, revealing a promising strategy to realize anticipated high specific energy cycling. However, both RM-induced Li degradation and electron shuttling between the cathode and anode become the become the inherent defects, resulting in poor sustainability. Here, with a narrow pore size window, a metal–organic framework (MOF)-based separator has been proposed, which acts as a RM molecule sieve to restrain the shuttling. By maximizing the advantages of the dual RM strategy, the Li–O 2 cell reveals a prolonged cycled life (100 cycles, 5000 mAh g –1 ) at high current rate (1000 mA g –1 ). Moreover, the Li–O 2 pouch cell fabricated by the flexible MOF-based separator exhibits the potential for the development of large-scale energy storage devices.