| Summary: | 碩士 === 國立中央大學 === 化學研究所 === 99 === The development of polymer electrolytes with high ionic conductivity has received considerable attention because of their potential applications in many solid electrochemical devices such as high-energy density batteries, chemical sensors, and light-emitting devices. Organic-inorganic hybrid electrolytes doped with LiClO4 and based on tri-block copolymer poly(propylene glycol)-block-poly(ethylene glycol)-block-poly(propylene glycol) bis(2-aminopropyl ether) (H2N-PPG-PEG-PPG-NH2), 3-isocyanatepropyltriethoxysilane (ICPTES) and central core 2,4,6-trichloro-1,3,5-triazine (cyanuric chloride, cc) have been synthesized by sol-gel process to get a double core-branched structure.
The structural and dynamic properties of the materials were systematically investigated by a variety of techniques including thermo gravimetric analyzer (TGA), AC impedance, Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), scanning electron microscope (SEM), 13C cross-polarization magic-angle spinning (CPMAS) NMR measurement and with varying contact times, 1H-13C 2D WISE (wide-line separation) NMR measurements. A VTF (Vogel- Tamman-Fulcher)-like temperature dependence of ionic conductivity was observed for all the hybrid electrolytes studied, implying that the diffusion of charge carriers was assisted by the segmental motions of the polymer chains. The Li-ion mobility was determined from 7Li static NMR line width measurements and correlated with their ionic conductivities. A maximum ionic conductivity value of 6.22 × 10-5 S/cm was obtained at 30 ?C for the hybrid electrolyte with a [O]/[Li] ratio of 32.
Also present the swelling ratio of the electrolyte membrane is measured with different electrolyte solvents and found to be very high in comparison to other reported polymer electrolyte membrane. The membrane exhibits ionic conductivity value near to 10-2 S/cm. The high ionic conductivity of the electrolyte membrane is attributed to the higher percentage of swelling as it can retain sufficient amount of electrolyte solvent, thus creating channels for free movement of ions. The membrane also depicts higher electrochemical stability window versus Li/Li+, which is required for practical battery applications.
|
|---|
