Preparation And Properties Of Lithium-ion Battery Separator By Electrospinning

Lithium-ion battery separator as an important part of a battery,whose role is to avoid the contact of the positive and negative electrode and as the transmission intermediary of lithium-ion.The separator has significant impacts to the battery electrochemical properties,durability and safety.The separator prepared by electrospinning has the characteristics of high porosity,easy control of thickness and simple process.It has some advantages for the preparation of lithium-ion battery separator.In this paper,lithium-ion battery separator was prepared by electrospinning technology,and its performance was studied.Firstly,PVDF-HFP separator was prepared.The effects of spinning conditions on the properties of the separator were studied.The best spinning conditions were as follows:T he concentration of PVDF-HFP was 0.26g/ml.The volume ratio of N,N-dimethylformamide?DMF?and acetone was 7:3,the electrospinning voltage was 20KV and the spinning temperature was30?.The diameter of PVDF-HFP nano-fibers prepared under optimum spinning condition distributed over 150-300nm.The melting point of PVDF-HFP fiber separator was 157.94?which is higher than commercial lithium-ion battery separator.The tensile strength of PVDF-HFP separator was 10.09MPa and the elongation at break was 74.34%.The porosity achieved 84%and electrolyte uptake was as high as 570%.Ion conductivity was 1.19mS/cm.Secondly,SiO2@PVDF-HFP separator was prepared.We used silane coupling agent to successfully modify the nano-SiO₂,the best amount of SiO₂ was 0.3g.The water contact angle was 108°.The tensile strength was 3.86MPa,elongation at break was 72.11%.The dimensional shrinkage of the separator below 170?is maintained at about 4%.The separator had a porosity of 87%and a liquid absorption rate of 620%,the ionic conductivity was 2.92mS/cm.Finally,aramid liquid 1313 was used as substrate to fabricate separator by electrospinning.The best spinning conditions were as follows:The concentration was 1.60g/ml,the voltage was20KV,the receiving distance was 20cm.The water contact angle of the separator was 54.3°,the tensile strength was 3.92MPa and the elongation at break was 55.55%.The shrinkage of the separator at 170°C or less was maintained at about 4%.The separator had a porosity of 85%,a liquid absorption rate of 750%and an ionic conductivity of 1.38mS/cm.