Composite Cathode Architecture with Improved Oxidation Kinetics in Polymer-Based Li-O-2 Batteries

摘要

The Li-O-2 battery based on the polymer electrolyte has been considered as the feasible solution to the safety issue derived from the liquid electrolyte. However, the practical application of the polymer electrolyte-based Li-O-2 battery is impeded by the poor cyclability and unsatisfactory energy efficiency caused by the structure of the porous cathode. Herein, an architecture of a composite cathode with improved oxidation kinetics of discharge products was designed by an in situ method through the polymerization of the electrolyte precursor for the polymer-based Li-O-2 battery. The composite cathode can provide sufficient gas diffusion channels, abundant reaction active sites, and continuous pathways for ion diffusion and electron transport. Furthermore, the oxidation kinetics of nanosized discharge products formed in the composite cathode can be improved by hexamethylphosphoramide during the recharge process. The polymer-based Li-O-2 batteries with the composite cathode demonstrate highly reversible capacity when fully charged and a long cycle lifetime under a fixed capacity with low overpotentials. Moreover, the interface contact between hexamethylphosphoramide and the Li metal can be stabilized simultaneously. Therefore, the composite cathode architecture designed in this work shows a promising application in high-performance polymer-based Li-O-2 batteries.