Effect of surface groups of nano-SiO_2 on the electrochemical properties of composite polymer electrolytes for rechargeable lithium batteries

采用不同表面化学状态的纳米SiO2,制备了聚环氧乙烷[Poly(ethyleneoxide),PEO]基复合聚合物电解质(Compositepolymerelectrolytes,CPE),通过DSC技术和FTIR光谱研究了纳米填料对聚合物体系体相成分的影响,并对其离子电导率、锂离子迁移数、电化学稳定性等电化学性质进行了表征。结果表明,纳米填料的表面化学状态对CPE的影响很大,亲水性的SiO2对CPE的相组成几乎没有改变效果,但疏水性的SiO2明显降低了聚合物体系的晶相成分。电化学测试结果显示,采用表面烷基化的SiO2制备成的CPE比采用亲水性SiO2的CPE显出更高的离子电导率、锂离子迁移数和更宽的电化学稳定窗口,揭示了体系的相组成和PEO/SiO2相界层是影响CPE内离子传输的两个重要因素。Nano-SiO2 with different surface chemical states were introduced into PEO-based polymer electrolytes to form inorganic-polymer composite electrolytes. The composite electrolytes were studied by DSC and FTIR spectroscopic techniques, A.C impedance, chronoamperometry, linear potential scanning voltammetry etc. to explore the structural and electrochemical properties. The experimental results showed that the surface chemical states have distinctive effect on the properties of the composite polymer electrolytes. SiO2 with hydrophobic surface resulted in the decrease of crystallinity phase in the polymer system,while SiO2 with hydrophilic surface has little effect on the phase component of the CPE. The electrochemical experiments results showed that CPE dispersed with hydrophobic SiO2 demonstrate much better performances in ionic conductivity, lithium ion transference number and electrochemical stability window than that with hydrophilic SiO2. It could be concluded that the phase composition and PEO/ SiO2 interphase layer are both important factors for the ions transportation in CPEs.国家杰出青年科学基金(29925310);; 教育部霍英东优秀年轻教师基金(71014)资助课