| Composite polymer electrolytes has a wide application prospect in lithiumbatteries for the properties of easy machining, large scale film forming and goodplasticity. PEO is the most important matrix of the composite polymer electrolytes.Li1+xAlxTi2-x(PO4)3(X=0.2-0.5)could add Li ion to the electrolytes, lower the degreeof crystallinity of the polymer, and improves the electrical conductivity. In this paper,Li1+xAlxTi2-x(PO4)3 nano powders was used as filler, which was prepared by sol-geland microwave heating method, then PEO/LiClO4/Li1+xAlxTi2-x(PO4)3 polymerelectrolytes were prepared by a solution-cast method. Investigations have been carriedon the structure, the crystallization property, the morphology and the conductivity ofthese composite polymer electrolytes, using IR, XRD, SEM and electricalimpedance(EI) measurement and so on.Li1+xAlxTi2-x(PO4)3 nano powders was acquired by conventional heating andmicrowave heating from precusor which was prepared by sol-gel method.The effects of pH value on the gelation and powder granularity, the influence ofthe heat treatment mode on the synthesis condition and the impact of Al mixingcontent on the conductivity were studied. It can be concluded that when the pH valueof solution was 3.8, stable sol could be obtained, while particle size of powders wassmallest. Treatment temperature and holding time of the microwave heating could belower and shorten, comparing with conventional heating. Grain size of the powdersobtained by microwave heating was smaller, and powers were well distributed, so thespecific surface area was bigger(＞400 m2/g). The ionic conductivity ofLi1+xAlxTi2-x(PO4)3 increased at first, then decreased as increasing of Al content. Theconductivity was best when the X is 0.3, which was 2.28×10-5S/cm..PEO/LiClO4/Li1.3Al0.3Ti1.7(PO4)3 was prepared with Li1.3Al0.3Ti1.7(PO4)3 as filler.The effects of PEO molecular weight and filler content on conductivity of polymerelectrolyte were studied. The results showed that smaller molecular weight washelpful to the ionic conduction. Polymer electrolyte membrane had the highest ionic conductivity when the molecular weight was 300000(σ=2.44×10-5S/cm). The ionicconductivity increased at first, then decreased with increasing of Li1.3Al0.3Ti1.7(PO4)3content. When n(LiClO4:nLi1.3+Al0.3Ti1.7(PO4)3=8:2, the conductivity was maximum,3.39×10-5S/cm.After surface modification with KH550, Li1.3Al0.3Ti1.7(PO4)3power was filled toPEO to obtain polymer electrolytes. The effects of the surface modification onstructure and disperson of the Li1.3Al0.3Ti1.7(PO4)3, and effects on structure and theionic conductivity of the polymer electrolytes were studied. The results proved thatKH550 was grafted to surface of Li1.3Al0.3Ti1.7(PO4)3 powder, and dispersion of theLi1.3Al0.3Ti1.7(PO4)3 in organic solvent was improved. Li1.3Al0.3Ti1.7(PO4)3 aftersurface modification dispersed better in the polymer film, so the conductivity ofpolymer electrolyte film was higher, 3.81×10-5S/cm at best. |
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