摘要:
以聚氧化乙烯（PEO）为基质,成功制备出纳米ZnO掺杂的（PEO）8-ZnO-LiClO4离子导电聚合物电解质,并利用多种实验技术,包括扫描电子显微镜、X射线衍射（XRD）、傅里叶变换红外光谱和正电子湮没寿命谱（PALS）,系统地研究了纳米ZnO与基质间相互作用及其对聚合物链段运动、纳米尺度自由体积、离子输运和复合电解质电导率的影响.实验结果发现,纳米ZnO的掺杂使聚合物电解质的离子电导率得到了大幅度提高,当ZnO与PEO质量比为6%时达到最大,（PEO）8-ZnO-LiClO4的电导率为1.82×10-4S·cm-1,比（PEO）8-LiClO4的电导率（6.58×10-5S·cm-1）提高了大约一个数量级.XRD结果显示,纳米ZnO的加入降低了PEO的结晶性,增加了锂离子传输的非晶相,从而提高了电导率.离散PALS测量结果表明,随着纳米ZnO的加入,复合电解质的自由体积、浓度和相对自由体积分数fr均增加.连续PALS分析揭示了自由体积的分布由一个峰劈裂成两个峰,表明纳米ZnO的掺杂对聚合物的微结构有很大影响.基于实验测量的fr和离子电导率,研究了离子导电机理.研究发现,fr与电导率之间存在一个直接关系,即fr越大,越有利于锂离子的传输,导致电导率越大.这个结果支持聚合物电解质导电的自由体积理论.
Abstract:
The effects of nanosized ZnO on the microstructure,the free volume and the ionic conductivity of poly ethylene oxide （PEO） nanocomposite electrolytes （PEO）8-ZnO-LiClO4 are systematically studied by scanning electron microscopy,X-ray diffraction,Fourier transform infrared spectroscopy and positron annihilation lifetime spectroscopy （PALS）,respectively.The experimental results show that the presence of the nanosized ZnO brings about a reduction in the crystallinity of the PEO phase and a very marked increase in ionic conductivity.PALS discrete analysis shows that the free volume size,the free volume concentration and the relative free volume fraction significantly increase with the increase of nano-ZnO.Specially,it is the first time to observe the occurrence of peaks of the free volume distribution split after nano-ZnO has been filled,which indicates that the ZnO added into （PEO）8-LiClO4 has an important effect on the microstructure for nanocomposites due to the interaction between the nano-ZnO and matrix.A direct correlation between the free volume fraction and the ionic conductivity is observed,and the ionic conductivity mechanism is discussed.
首页
登录
注册
下载: