Preparation And Properties Of NVP-Based Gel Polyelectrolyte

Gel polymer electrolyte(GPE) has the advantages of no liquid leakage, flexibility,simple structure, environmental protection and so on. Poly (N-vinyl pyrrolidone)(PVP) is a kind of good polymer electrolyte material with water-soluble, and easy to be modified and synthesied method is simple. Copolymerization and blending are effective methods for improving the ionic conductivity and mechanical strength of GPE.P(N-vinylpyrrolidone-co-sodium styrenesulfonate) copolymer gel electrolyte membrane, namely P(NVP-co-SSS) copolymer gel electrolyte membrane, was synthesized by free radical solution polymerization using N-vinylpyrrolidone and sodium styrenesulfonate as comonomer. The effects of amount of initiator, and crosslinking agent, temperature and ratio of monomer on liquid absorption and ionic conductivity of the GPE were investigated, respectively. The optimum comprehensive properties are obtained when the amount of initiator is 1.5 wt.%, the amount of crosslinker is 1.0 wt.%, the temperature is at 70℃ and the monomer ratio is 2: 1,respectively, and the ionic conductivity is 3.58×10-3 S/cm, the water absorption is 18.57 g·g-1. Comparing with PVP system, the ionic conductivity increased by two orders of magnitude. FTIR and XRD showed that the crystallinity of the film was decreased by the copolymerization of sodium styrene sulfonate. TGA analysis showed that the copolymerization can improved the thermal stability, and the maximum thermal decomposition temperature is 444.1℃, the mechanical strength is 4.2 MPa.The active carbon as the electrode, the electrochemical properties of P(NVP-co-SSS)GPE based supercapacitor was also studied, P(NVP-co-SSS) copolymer has good electrochemical performance, and the specific capacitance remained 75% after 1000 times charging and discharging.P(NVP-co-SSS)/PVA GPE was prepared by blending P(NVP-co-SSS) copolymer with polyvinyl alcohol (PVA). The effects of PVA content on the performance of GPE were investigated. Compared with P (NVP-co-SSS) copolymer GPE, the ionic conductivity of the blending membrane increased to 10-2 S/cm; the thermal stability of P(NVP-co-SSS)/PVA is better and the maximum thermal decomposition temperature is little higher . When the PVA content is 20 wt.%, the tensile strength is 10.27 MPa,which can reach 2.5 times of that of the P(NVP-co-SSS) film, When the PVA content is 50 %, the tensile strength is 20.33 MPa and the elongation at break is 637%. The active carbon as the electrode, the electrochemical properties of GPE based supercapacitor were also studied, the specific capacitance of P (NVP-co-SSS)/PVA GPE is 19.42 F/g and 23.55 F/g when PVA content is 20 wt.%, 30 wt.%, respectively.The specific capacitance still remained 90 % after 500 times charging and discharging,and the specific capacity still remained 85 % after 1000 times.