PEEK-WC/Nanosponge Membranes for Lithium-Anode Protection in Rechargeable Li-O2 Batteries

Dextrin-based nanosponges (NSs) are hyper-crosslinked polymers characterized by the ability to encapsulate a great variety of substances in liquid phase. More importantly, dextrin-based NSs are nanostructured within a three-dimensional network. Here, an amorphous modified polyetheretherketone (PWC) and NS-derived from crosslinking dextrin and beta-ciclodextrins are used to prepare flat-sheet membranes. The presence of NSs in the membrane changes the features of PWC. The PWC/NS membrane displays very low oxygen permeability, good ionic conductivity, and assure a suitable interfacial stability with Li metal. For such properties, the membrane is suitable to protect the highly reactive Li-metal anode from oxygen crossover, dendrite formation, and from side reactions due to the oxygenated dimethyl sulfoxide (DMSO)-based electrolyte. Li-O-2 lab-scale cells are assembled with the membrane sandwiched between Li and the separator soaked by electrolyte, with continuous oxygen flow of 3 mL/min at the cathode side. XRD analysis demonstrates that the membrane does not interfere with the formation and decomposition of Li2O2. Membranes assure long cell-cycle life at reversible capacity and better capacity retention during cycling in full discharge/charge conditions.