Exploring PVFM-Based Janus Membrane-Supporting Gel Polymer Electrolyte for Highly Durable Li-O Batteries.

Electrolyte is the key to constructing the ionic transport paths and O gas diffusion routes in the cathode as well as maintaining the electrode interfacial stability in view of the complex chemistry of Li-O batteries. A novel poly(vinyl formal) (PVFM)-based Janus membrane, which is prepared via coating multiwalled carbon nanotubes (MWCNTs) on the porous side of the cross-linked PVFM membrane, has been proposed herein to achieve membrane-supporting gel polymer electrolyte (GPE) for Li-O batteries. Within Li-O batteries, the dense side of PVFM-based Janus membrane demonstrates a good compatibility with lithium metal anode, while the other side with MWCNTs coating reserves much more solvent on the surface, assisting the cathode to form enlarged electrolyte-wetted interface. Moreover, the comparative studies indicate that PVFM-based Janus membrane also can provide a conductive pathway, modulate the morphology of the discharge products, and produce accommodation space for the products. So, the Li-O batteries containing PVFM-based Janus membrane-supporting GPE not only demonstrate significantly improved discharge capacity and cycling stability, i.e., 150 times at 1000 mAh g capacity limitation, but also a narrow voltage gap of 0.90 V and an excellent rate performance up to 1000 mA g.