Study On The Preparation And Performance Of The Water-proof And Oxygen-permeable Layer For Organic Lithium-air Batteries

The current lithium-ion battery technology cannot meet the requirement of energy density for the energy consuming system,such as the electric vehicles.It is urgent to develop a new rechargeable battery with high energy density.Li-air batteries(LABs)possess high theoretical specific capacity(3860 mAh g-1)and specific energy(11425 Wh kg-1),several times higher than the current lithium ion batteries,which make it a promising next-generation energy storage system.However,at present,most LABs are operated in pure oxygen,since the water and carbon dioxide in the air can bring serious side reactions,leading to the performance decay and even severe safety issues.Therefore,it is necessary to develop oxygen-selective membrane(OSM)for LABs operated in ambient air.In this work,a perfluorocarbon compound(PFC)-silicone oil(PDMS)based OSM is prepared and applied in LABs in the ambient air with relative humidity of 68%.The results show that at 0.1 mA cm-2,the LAB with PFC-PDMS OSM delivers the initial discharge capacity of 4991 mAh g-1 in ambient air,closed to that of the Li-O2 battery(5363 mAh g-1n pure O2,and significantly higher than that of the LAB without OSM(1936 mAh g-1).Under the limited capacity of 500 mAh g-1,LAB with OSM can be stably cycled for 41 cycles in air,comparable to the Li-O2 battery(47 cycles)and much better than the LAB without OSM(8 cycles).At high current density of 0.5 mA cm-2,the LAB also show a high discharge voltage plateau in ambient air,and the comparable cycling performance to Li-O2 battery.XRD and FTIR characterizations further demonstrate that the LAB with OSM has less side product.In all,PFC-PDMS OSM with high oxygen solubility and hydrophobicity can efficiently serve Li-air batteries sufficient oxygen transport,and suppress water permeation and electrolyte solvent evaporation,making it a promising OSM material for Li-air batteries.