聚丙烯酸锂基固态聚合物电解质的改性研究

【作者】 袁云兰；

【导师】 潘春跃；

【作者基本信息】 中南大学 ， 应用化学， 2004， 硕士

【摘要】 为改进聚丙烯酸锂（PAALi）基SPE的性能，本文从聚合物电解质改性角度出发，对聚合物基体（聚丙烯酸锂）进行了共聚改性，锂盐进行了正交优化配比实验，添加SiO₂制备出P（AALi-AN-BA）／SiO₂／LiX复合型SPE，并对其性能进行了研究。 本文在聚丙烯酸锂（PAALi）基体上引入高介电常数的丙烯腈（AN）和具有柔性结构的丙烯酸丁酯（BA）单元，采用溶液聚合法制备出三元共聚物P（AALi-AN-BA），使聚合物电解质基体的成膜性能及溶解性能得到改善。 聚合物电解质中所添加锂盐对其性能影响较大，为了制备熔点较低、电导率较高的共熔盐，本文采用两次正交实验，对锂盐的比例进行了优化，制得室温电导率为3.1×10^-4 S.cm^-1、熔点为138℃的共熔锂盐（LiX），其最佳配比（质量比）为高氯酸锂（LiClO₄）：硝酸锂（LiNO₃）：溴化锂（LiBr）=2：3：1。将此共熔盐与聚合物基体P（AALi-AN）复合制备出高盐含量的PISE（polymer-in-salt electrolyte），其室温电导率最高为4.5×10^-5S.cm^-1。热分析表明盐与聚合物基体形成了低共熔物，其玻璃化转变温度降到75℃（聚合物基体为105℃）。X射线衍射及红外分析表明聚合物与锂盐复合后有新相生成，这是-CN基团与Li⁺相互作用的结果。 在聚合物电解质中引入SiO₂等无机单元可对聚合物电解质的性能有明显改善，本文采用sol-gel法在P（AALi-AN-BA）聚合物基体中引入SiO₂，将P（AALi-AN-BA）／SiO₂复合物作为聚合物电解质的基体。热分析（DTA、TG）、傅立叶红外分析（FTIR）及透射电镜（TEM）结果表明P（AALi-AN-BA）／SiO₂复合物能形成均一稳定的膜，SiO₂的加硕士学位论文摘要入提高了聚合物基体的热稳定性。将P（AALi^AN.BA）/ 510:复合物与低温共熔盐共混制备出P（AALi^AN一BA）/5102几iX聚合物电解质。结果表明添加510:降低了离子迁移的表观活化能（Ea），当510:的含量为10wt.%时，所制得的P（AALi.AN一A）/s 102几iX电解质的室温电导率最高可达6.2 x 10一s.cm‘，，Ea值为40.6 KJ/mol。通过红外、差热及交流阻抗测试，分析研究了5102、聚合物基体及LIX之间的相互作用，并推测了离子在其中的导电机理。对510:在此高盐含量的复合型聚合物电解质中的作用做了分析。更多还原

【Abstract】 In order to obtain a kind of composite polymer electrolyte(CPE) with good properties, the base of CPE, PAALi was modifided and the proportion of lithium salts available was optimized.Firstly, the monomers of acrylonitrile(AN) with high dielectric constant and butyl acrylate(BA) with flexibility were introduced into the base of CPE and terpolymer of AALi, AN, BA was synthesized by solution copolymerization in methanol. Then self-sustained membranes with good mechanical properties can be obtained. It is also proved that the blends of AALi, AN and BA are compatible system.Two orthogonal experiments on lithium salts were done to optimize proportion of lithium salts and a new type of eutectic salt(LiX) was obtained ,which has high room temperature conductivity?3.1 10-4S.cm-1) and low molten point(138). The eutectic salt consists of lithium perchlorate (LiClO4), lithium nitrate(LiNO3) and lithium bromide(LiBr) and its composition is LiClO4/LiNO3/LiBr=2/3/l in mass ratio. The eutectic salt was mixed with copolymer P(AALi-AN) to form polymer in salt electrolyte(PISE), which exhibits a lower glass transition temperature(Tg)(75 ) compared to the pure polymer(105) by differential thermal analysis (DTA). X-ray diffraction(XRD) and Fourier transform Raman spectra(FTIR) indicat that a new complex was formed between polymer and salt by interacting Li+ with -CN and polymer matrix can suppress the salt crystallinity.In order to introduce inorganic compound into CPE, a series of hybrids comprising P(AALi-AN-BA) and silica(SiO2) were synthesized in situ by a sol-gel process and the hydrolyzation of the tetraethyl orthosilicate(TEOS) precursors and polymerization of monomers reacted spontaneously in methanol. A mechanical uniformly membrane idetifided by TEM was obtained, which exhibits good thermal stability characterized by DTA and thermogravimetry (TG). The hybrids was successfully used to enhance the conductivity of P(AALi-AN-BA)/LiXby mixing the hybrids with LiX to form P(AALi-AN-BA)/SiO2/LiX electrolytes. In the curves of conductivity versus composition for the CPEs, the room temperature conductivity shows a maximun value of 6.26 l0S.cm-1,corresponding to the sample with a 10 wt% of silica. The CPEs were examined by AC impedenc, DTA and FTIR. The results indicated that SiO2 can reduced the ion transfer activation energy(Ea) in the system. The interactions of components of the investigated system in the system and the possible conduction mechanism were also discussed. In addition, some interesting phenomena such as thermal hysteresis and stability of conductivity to time also were discussed.更多还原