Polyaniline Encapsulated Amorphous V₂O₅ Nanowire-Modified Multi-Functional Separator For Lithium-Sulfur Batteries

Lithium-sulfur batteries(LSB)not only have a high theoretical energy density,but also have a very low production cost,which makes them a promising energy storage device at present.However,the poor electrical conductivity of sulfur element and serious "shuttle effect" have always hindered its commercialization.In this paper,the electrochemical performance of lithium-sulfur batteries was improved by using a modified separator with high conductivity,strong adsorption and catalytic ability to achieve the inhibition of polysulfide shuttle.The main research results are as follows:1.Amorphous vanadium phenoxide nanowires(V2O5·nH2O nanowires,abbreviated as VOH NWs)with radial size of 5.7 ± 0.3 nm and length of 1-2 μm are prepared by sol-gel method.The VOH-PP modified separator is prepared by using VOH NWs as modified materials,and the physical properties and electrochemical properties of the separator are tested.The results show that VOH-PP separator can improve the wettability of electrolyte,and has strong chemical adsorption and catalytic conversion for polysulfide,which makes the LSB have a better electrochemical performance.The battery with VOH-PP separator can achieve an initial discharge specific capacity of 949.9 mAh/g at a test current of 0.2C,and it remains at 83.6%of the initial capacity after 100 charge/discharge cycles.In addition,the battery also has a favorable rate performance,showing a reversible capacity of 487.7 mAh/g at 5 C.2.The organic-inorganic composite material of conductive polyaniline(PANI)coated amorphous VOH NWs(VOH@PANI NWs)are prepared by in-situ oxidation process,and they are applied as coating material for functional separator of LSB.Benefit from the synergistic effect of the conductivity provided by polyaniline and the adsorption of polysulfides by imine(-N=)groups and the adsorption and catalysis of polysulfides by amorphous VOH,the electrochemical performances of LSB with VOH@PANI-PP separator are further improved.At the current density of 0.2 C,the initial discharge capacity is 1132.4 mAh/g.Moreover,the capacity retention rate is 61.5%after 1000 cycles under 1 C.At a current density of 5 C,a reversible specific capacity of 670 mAh/g can be obtained.Even when the sulfur loading reaches 6.5 mg/cm2,the reversible specific capacity of the LSB based on the VOH@PANI-PP separator is 1054 mAh/g at a current density of 0.1 C.