| Lithium ion battery?LIB?has been considered as a major energy storage device because of its high energy density,long cycle life,and minimal memory effect.However,the safety problems caused by the leakage and combustion of organic liquid electrolytes,which limit the large-scale application of LIB.Gel polymer electrolyte?GPE?has been considered as a promising alternative because of its thermal resistance,the dimension stability and well compatibility with lithium electrodes.The way to prepare GPE with good pore structure,excellent mechanical properties and high ionic conductivity is the main research hotspot.We use the poly?acrylonitrile??PAN?with high ionic conductivity and thermal stability,the thermoplastic polyurethane?TPU?with excellent mechanical properties and the poly?propylene carbonate??PPC?with good compatibility with electrodes and electrolytes as the matrix materials and prepare ternary PAN/TPU/PPC based GPEs with excellent physical and electrochemical properties by electrospinning in this study.This paper studies from the following three aspects.?1?The PAN/TPU/PPC,PAN/TPU,PAN/PPC,and TPU/PPC based Nanofibrous films?NFs?are prepared by the electrospinning technique.The physical properties of the films are characterized,such as morphology,porosity,thermal stability and mechanical properties.After electrospun films activated to GPE,we test their electrochemical properties.The morphology and the thermal stability of the PVDF/TPU/PPC NFs are the best.It shows the high tensile strength of 10.9 MPa and the maximum elongation of 111.6%.The ionic conductivity of its corresponding GPE is as high as 5.45 mS cm-1,and the electrochemical stability window is up to 5.7 V at room temperature.In addition,it shows a high initial charge capacity of 166.9 mAh g-1 and a high initial discharge capacity of 166.3 mAh g-1.The excellent comprehensive properties make the PVDF/TPU/PPC based GPE more suitable for lithium ion batteries.?2?At the concentration of 10%,we change the mass ratio among the three polymers?PAN,TPU and PPC?.And five kinds of GPEs with different mass ratios are prepared by the electrospinning technique.The morphology test,physical property test and electrochemical performance test are also put into practice.The morphology and the mechanical property of the PTP5 based NFs are the best.The electrolyte absorption rate of it is as high as 372%,and the ionic conductivity is 5.45×10-3 S cm-1 at room temperature.It shows a high initial charge-discharge capacity of 166.9mAh g-1 and 166.3 mAh g-1.After 50 cycles,the discharge capacity of PTP5 is still up to 160.5 mAh g-1 with a small capacity attenuation.?3?Fibrous membranes of PAN/TPU/PPC were fabricated by the electrospinning method with different concentrations of polymer solution.Their morphology and performance are systematically investigated by scanning electron microscopy?SEM?,thermal analysis?TGA?,charge-discharge tests,and so on.The electrolyte absorption rate of the electrospun film prepared by 10%concentration of PAN/TPU/PS solution is 372%,and the ionic conductivity of the PAN/TPU/PS?10%?based GPE is 5.45×10-33 S cm-11 at room temperature.At 25?,the initial charge and discharge capacities of the cell containing the PAN/TPU/PPC based GPE?10%?are 166.9 mAh g-1 and 166.3mAh g-1,respectively under 0.1 C rate.After 50 cycles,the discharge capacity is still up to 160.5 mAh g-1 with a small capacity attenuation. |
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