Excellent electrolyte-electrode interface stability enabled by inhibition of anion mobility in hybrid gel polymer electrolyte based Li-O2 batteries

Lithium-oxygen (Li-O-2) batteries with excellent theoretical energy density (similar to 3500 Wh kg(-1)) have attracted much attention as next generation energy storage and conversion devices. However, the safety issues caused by the growth of lithium dendrites hinder the commercial application of Li-O-2 batteries at the current stage. Here, we propose a novel gel polymer electrolytes (GPE) based on poly (vinylidene fluoride-co-hexafluoropmpylene (PVDF-HFP)/poly (ethylene oxide) (PEO)/Ti3C2Tx MXene (refer to as PPM). The weak trapping interactions between ethylene oxide (EO) unit in PEO and anions in lithium salts can solidify anions and promote the dissociation of lithium salts. In addition, the parallel packed two-dimensional Ti3C2Tx MXene nanosheets can effectively guide the uniform nucleation and growth of lithium on the surface of lithium electrode, inhibiting the formation of lithium dendrites during lithium plating. Based on the above advantages, the ionic conductivity and the lithium ion migration amount of the synthetic GPE can reach 5.45 x 10(-4) s cm(-1) and 0.47, respectively, at room temperature. Base on the above merits, the Li/PVDF-HFP-PEO-5% Ti3C2Tx MXene/Li (Li/PPM-5/Li) symmetric cell can cycle steadily for more than 650 h at a current density of 0.5 mA cm(-2). Moreover, PPM-5 based Li-O-2 battery can cycle more than 200 cycles at room temperature. This work is of great significance to improve both safety and cycleability of Li-O-2 batteries.