Pouch-type hybrid Li-air battery enabled by flexible composite lithium-ion conducting membrane

Abstract

Pouch-type hybrid Li-air batteries with an air-breathing ability and lightweight packaging provide improved specific energy compared with commercial Li-ion batteries and Li–O2 batteries that require oxygen supply equipment. Because ceramic Li-ion conductors, used to separate aprotic and aqueous electrolytes, are brittle and inflexible, hybrid Li-air batteries are difficult to assemble into pouch cells for use in flexible device applications. A flexible pouch-type hybrid Li-air battery is realized by utilizing a flexible composite lithium-ion conducting membrane (FCLICM). This FCLICM, consisting of sol-gel-derived Li1+xAlxTi2-x(PO4)3 (LATP) as a Li-ion conductor and a chemically compatible poly (vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) polymer matrix, is produced by the tape-casting technique and applied in hybrid Li-air batteries. An assembled pouch-type hybrid Li-air battery containing a lithium foil anode, an aprotic electrolyte, an FCLICM, an aqueous electrolyte and a platinum air cathode is operated in ambient air, exhibiting a high capacity of 200 mAh g−1 with a cycle life of 12 cycles (48 h). This pouch cell shows an open-circuit voltage of 3.16 V regardless of being flat or bent, demonstrating its flexibility and electrochemical stability and its potential for use in wearable technology.