| Lithium-sulfur batteries are considered as one of the most promising electrochemical energy storage systems due to their excellent theoretical specific capacity(1675 mAh.g-1)and high energy density(2600 Wh.kg-1).However,because of the“shuttle effect”of lithium polysulfides and the low conductivity of elemental sulfur and lithium polysulfides,the commercial development of lithium sulfur battery is seriously hindered.As an important part of lithium-sulfur battery,separator plays a very important role in the electrochemical performance and safety of lithium sulfur battery.However,the traditional alkene separators have poor wettability to the liquid electrolyte and“shuttle effect”to lithium polysulfide,and there is a potential safety hazard of easy contraction under high pressure or temperature conditions,resulting in short circuit of the battery.Therefore,the development of high performance and good temperature resistant lithium sulfur battery separator is rather important.Based on the excellent thermal stability between poly benzene formyl m-phenylene diamine（PMIA）as raw material,the high temperature resistant gel PMIA fiber membrane us prepared based on the F O,S doping by the electrospinning technology through the introduction of 3,4-ethylenedioxythiophene（EDOT）and fluorine-containing latex(Oliphobol TM7713).When the prepared membrane was used as the separator of lithium sulfur battery,its electrochemical properties were explored.The detailed specific content is as follows:（1）Firstly,adding a certain amount of fluoride emulsion to PMIA solution.Then different contents of EDOT were added into the PMIA solution including fluoride emulsion.The fluorine-containing PMIA fiber membrane modified by EDOT was successfully prepared by electrospinning technology.The effects of EDOT content and spinning process on the morphology of nanofibers were investigated by SEM test.The results showed that 5 wt%of EDOT doping amount,30 k V spinning voltage,receiving distance of 17 cm,the morphologies of EDOT modified fluoride-PMIA fiber membrane were neat.Besides,the EDS,XPS,FTIR and other characterization methods were used to prove the successful doping of EDOT and emulsion containing F.（2）The pure PMIA membrane,F-PMIA membrane and EDOT-5/F-PMIA membrane were prepared by electrospinning technology,and the influences of the incorporation of EDOT and fluorinated emulsion on the pore size and mechanical properties of fiber membrane were compared,and the thermal stability,gelation performance and electrochemical properties of the EDOT-5/F-PMIA were studied.The results showed that the addition of fluorinated emulsion significantly improved the hydrophilic performance to liquid electrolyte of PMIA membrane,and the prepared fiber membrane showed good gelation.The addition of EDOT further reduced the average diameter of the PMIA membrane,effectively improved the mechanical properties of the membrane and reduced the pore diameter of the membrane.Compared with commercial membrane,pure PMI membrane,F-PMIA membrane and EDOT-5/F-PMIA membrane all had good thermal stability below200°C.The small pore size and gelation of EDOT-5/F-PMIA can help to block the“shuttle effect”of lithium polysulfides.The assembled battery had higher ionic conductivity and lower impedance.At 0.5 C,its initial discharge specific capacity was740.2 mAh g-1and maintained 606.7 mAh g-1after 300 cycles with capacity attenuation of 0.060%per cycle. |
