Synthesis, characterization, and ionic conductivity of novel crosslinked polymer electrolytes for Li-ion batteries

摘要

In this work, we communicate on the synthesis, characterization, and ionic conductivity of a series of novel crosslinked inorganic-organic gel polymer electrolytes. These crosslinked polymers were prepared by the modification of poly(vinyl alcohol) (PVA) with poly(ethylene glycol) (PEG) in the presence of borane-tetrahydrofuran (BH _3/THF) complex. During crosslinking, the polymer was doped with lithium trifluoromethane-sulfonate (CF _3SO _3Li) salt. Molecular weight of both PVA and PEG was varied, and the concentration of Li-salt was arranged for the ratio of lithium atoms to ether oxygen atoms. Boron-containing polymer electrolytes were produced and abbreviated as PVA1PEGX-Y and PVA2PEGX-Y. The reaction of PEG with PVA and the interaction of Li ~+ ions with EO units were confirmed by FTIR. Thermal stability of these materials was measured with thermogravimetric analysis, and thermal behaviors were measured by differential scanning calorimetry. The ionic conductivity of these novel polymer electrolytes was studied by dielectric-impedance spectroscopy. Li-ion conductivity of these crosslinked polymer electrolytes depends on the length of the side units as well as the doping ratio. The maximum ionic conductivity was measured as 10 ~(-4) S cm ~(-1) at room temperature.