Preparation And Properties Of Polyvinyl Alcohol-based Nanocomposite Ionogel

Ionic liquid(IL) is a kind of low-temperature molten salt which is entirely composed of anion and cation. Ionogel, as a new functional polymeric material, is prepared by adding the polymer into ionic liquid via physical or chemical method. This is a promising electrolyte material because of its unique properties such as high conductivity, suitable mechanical strength, thermal stability and excellent safety. It can be used not only as high performance gel electrolytes in the new solar cells, lithium batteries, supercapacitor, artificial muscles and electrochromic devices. In this paper, we prepared high performance nanocomposite ionogels based on PVA by adding new nanoparticles of halloysite nanotubes(HNTs), and the ionic liquid as the solvent and electrolyte. The results are as follows:(1) High-performance ionic liquid(ILs)-based nanocomposite polymer electrolytes(NCPE) with highly ordered honeycomb-like microporous poly(vinyl alcohol)(PVA) scaffolds has been prepared by coupling unidirectional freezing method and vacuum degassing method. Regarding its conductivity property, the ILs-based NCPE exhibits significant anisotropy, and its ionic conductivity can reach 5.2×10-3 S/cm at 30 o C in the direction parallel to the freezing, which is more than 500 times higher than that obtained the direction perpendicular to the freezing, which is 9.6×10-6 S/cm at 30 oC. More importantly, as a consequence of the compact self-assembly of HN Ts into structured composites, the obtained ILs-based NCPE, which presents extremely thin channel walls(60-100 nm), can exhibit a combination of very high compression modulus of 46.5 MPa and the dynamic modulus can reach 107 Pa at 200 oC.(2) Ionogel with orderly micro- and nanostructure has been achieved both by self-assembly and mechanical shearing method. Gelation, liquid crystalline properties, thermal stability and ionic conductivities for these nanocomposite ionogels have been comprehensively characterized. The research shows that the obtained ionogel is very stable and nonvolatile and they show LC phases over a wide temperature range. The highly aligned nanostructure can significantly improve the ionic conductivities, which are on the order of 10-3 S/cm at room temperature even with 60 wt% HNTs. And liquid crystal nanocomposite ionogel with high ionic conductivity anisotropy can be prepared by mechanical shearing method. Li battery cell tests revealed that the GPE based on these hybrid ionogels can deliver high specific capacity and good cycling performance.(3) PVA/HN Ts/AMIMC l nanocomposite ionogel with high tensile strength and high ionic conductivity consisting have been successfully prepared by solution blending method and mechanical shearing method. Gelation, thermal stability, and ionic conductivities for these nanocomposite ionogels have been comprehensively characterized. The research shows that the obtained ionogels has good thermal stability. The addition of HN Ts can greatly improve the tensile strength of ionogel and enhance the ionic conductivity. The anisotropic ionic conductivity can be obtained by mechanical shearing treatment.