A mesoporous catalytic membrane architecture for lithium-oxygen battery systems

Controlling the mesoscale geometric configuration of catalysts on the oxygen electrode is an effective strategy to achieve high reversibility and efficiency in Li-O₂ batteries. Here we introduce a new Li-O₂ cell architecture that employs a catalytic polymer-based membrane between the oxygen electrode and the separator. The catalytic membrane was prepared by immobilization of Pd nanoparticles on a polyacrylonitrile (PAN) nanofiber membrane and is adjacent to a carbon nanotube electrode loaded with Ru nanoparticles. During oxide product formation, the insulating PAN polymer scaffold restricts direct electron transfer to the Pd catalyst particles and prevents the direct blockage of Pd catalytic sites. The modified Li-O₂ battery with a catalytic membrane showed a stable cyclability for 60 cycles with a capacity of 1000 mAh/g and a reduced degree of polarization (∼0.3 V) compared to cells without a catalytic membrane. We demonstrate the effects of a catalytic membrane on the reaction characteristics associated with morphological and structural features of the discharge products via detailed ex situ characterization.