碱性固体聚合物电解质制备及电性能的研究

【作者】 李月丽；

【导师】 张正富；

【作者基本信息】 昆明理工大学 ， 材料学， 2006， 硕士

【摘要】 本论文对聚合电解质的种类进行了简述,介绍了碱性固体聚合物电解质的应用、研究现状及进展,并对固体聚合物电解质的改性方法作了详细的叙述。在查阅大量文献的基础上,研究了PVA-KOH-H₂O系列的碱性固体聚合物电解质膜的成分配比、制备工艺及其对电性能的影响,并对离子导电机理进行了初步探讨。 本实验采用溶液浇铸法制备了PVA-KOH-H₂O基系列碱性固体聚合物电解质。结合正交设计实验和单因素实验研究了碱浓度、温度、聚合物以及增塑剂对固体电解质离子电导率、电化学稳定性的影响,用红外光谱、X衍射分析和差热分析等手段研究其结构与离子导电性能的关系,摸索出了本实验条件下的最优方案。 实验结果表明:随着碱含量的增加,PVA-KOH-H₂O体系的聚合物电解质的离子电导率不断升高,直至达到最大值,之后电导率开始下降,电化学稳定电压范围先增加,后又下降直至稳定;温度与离子电导率关系即不完全符合VTF方程电导行为,也不完全与Arrhenius方程一致,而是呈现较为复杂的曲线关系,电化学稳定窗口随温度的升高而下降;离子电导率随着PEO的加入先略有降低,后增加直到最大值,继续增加PEO的量,膜的性能变差;离子电导率随着增塑剂量的增加不断提高,达到最大值后下降,在增塑剂量相同时,PC的效果比GROL的效果好,无沦添加聚合物还是增塑剂都会使复合体系的电化学稳定窗口略为变窄。 聚合物结构分析表明:碱性固体聚合物电解质中凝聚态结构以非晶态为主,仅有少量的晶态,结晶度最大为0.1646;添加的各组分与PVA之间都有一定的相互作用,这种作用不仅破坏了聚合物链段的规整性,能够降低聚合物的结晶度,增大无定形区域,提高链段运动的能力,同时这种作用限制K⁺离子的运动,提高OH^-的迁移率,从而提高离子电导率;碱性聚合物电解质的离子传导主要发生在无定形区;在本实验测试离子电导率温度范围内,聚合物内部的结构不会发生变化,即温度只会影响电解质内部络合物解离程度和载流子迁移以及聚合物链段运动的情况。 最后利用正交试验选择制备出复合固体聚合物电解质可能的优化方案为PVA:KOH:PEO:GROL:PC:H₂O=3:4.5:0:0.5:0.75:40。更多还原

【Abstract】 The polymer electrolyte has been considerably investigated due to their wide potential applications in electrochemical devices, categories of the polymer electrolyte are briefly related in the present paper, the application, research and development of alkaline solid polymer electrolytes （ASPE） are introduced and the method of modification for ASPE is narrated in detail. On the basis of abundant literatures, the blend ratio, synthesis and ionic conductivity mechanism of ASPE for PVA-KOH-H₂O series are studied.Alkaline solid polymer electrolyte films, which composed of PVA-KOH-H2O series, were synthesized by a solution cast technique. The influences of alkali concentration, temperature, polymer and additive on ionic conductivity and electrochemical stability were studied with orthogonal experiments and single factor experiments design, the relation of structure and ionic conductibility is researched by FIRT, XRD,DSC and SEM analysis ways.The experimental results indicate that the ionic conductivity of ASPE increases progressively up to a maximum, then decreases with the alkali blended, and the voltage of electrochemical potential stability window increases first and then decreases to leveling off;The temperature dependence of the ionic conductivity is neither according with a Vogel-Tamman-Fulcher（VTF） behavior nor completely to Arrhenius equation, but exhibits a kind of complicated curve, the voltage of electrochemical potential stability window is decreasing with temperature increased;Firstly the ionic conductivity falls by inches with poly（ethylene oxide） （PEO） added, and then increases up to a maximum, at last the property of electrolyte film gets worse with excessive PEO;The ionic conductivity decreases before growing gradually up to maximum with plasticizer blended, the effect of propylene carbonate （PC） on improving ionic conductivity is better than that of GROL, all additives make the electrochemical potential stability window narrow.The analysis of polymer structure indicates that the non-crystalline phase is the majority of the agglomerate structure and the crystalline phase is the minority, the highest crystal value only reaches the level of 0.1646;There is a definite interactionadditives and PVA, which not only reduces the crystal value of ASPE to make amorphous areas enlarge but also improve the ability of segmental motion by destroying the well-regulated and orderly character of polymer chain, meanwhile restricts the mobility of potassium cation and enhances the anionic transference number of hydroxide ions, all these improve the ionic conductivity;The ionic conductivity occurs essentially within the amorphous phase of the ASPE;The structure of ASPE doesn’t change in the range of our test temperature, this means, the temperature only takes effect on degradation of complex in certain compositions, ionic mobility and segmental motions of the polymer chain.In the end, in terms of above investigations the optimum scheme （PVA:KOH:PEO:GROL:PC:H2O=3:4.5:0:0.5:0.75:40） of the experiments was obtained by orthogonal design experiments.更多还原