高稳定性化学交联聚乙烯醇/聚乙烯吡咯烷酮碱性固体电解质膜

碱性固体电解质膜的稳定性是影响其在电化学领域应用的一个重要因素.本文在前期研究工作的基础上,通过直接共混和化学交联修饰制备出了聚乙烯醇/聚乙烯吡咯烷酮(PVA/PVP)碱性聚合物电解质膜.采用傅里叶变换红外(FTIR)光谱、热重分析(TGA)、扫描电镜(SEM)和交流阻抗等方法详细考察了复合膜的分子结构、热稳定性、化学稳定性、氧化稳定性和尺寸稳定性.红外光谱结果表明,PVP成功地混入聚合物基体中,在1672cm-1处表现出来自于PVP第I带C襒O的强吸收峰.TGA结果表明,提高掺杂的KOH溶液浓度对PVA/PVP碱性膜的热稳定性没有明显影响.SEM分析结果表明,复合膜经高温、高浓度碱(80℃,10mol·L-1)处理后,其断面结构仍致密均匀,未出现类似小孔等膜降解情况,此时膜电导率(1.58×10-3S·cm-1)相比室温相同碱液时提高91.5%,表明PVA/PVP膜具有很好的耐碱化学稳定性.同时,PVA/PVP碱性膜表现出良好的抗氧化性,在60℃的3%和10%H2O2溶液中处理均没有观察到明显的质量损失,150h后仍能保持原膜质量的89%和85%.此外,由于膜内形成致密的内互交联网络结构,复合膜在水中800h之后也表现出很好的同向性和电导率稳定性.

Highly Stable Solid Alkaline Electrolyte Membranes from Poly(vinyl alcohol)/Poly(vinyl pyrrolidone)Based on Chemical Cross-Linking

The stability of alkaline electrolyte membranes is recognized as a key factor that affects their electrochemical applications, especially, in alkaline medium at temperatures above 60℃ and high KOH concentration. In this article, poly(vinyl alcohol)/poly(vinyl pyrrolidone)/KOH (PVA/PVP/KOH) alkaline membranes were succesfully prepared by direct blending and chemical cross-linking modifications. In particular, the molecular structure, thermal stability, chemical stability, oxidative stability, and mechanical strength stability of the composite membranes were studied in detail using fourier transform infrared spectra (FTIR), thermogravimetric analysis (TGA), scanning electron microscope (SEM), and alternating current impedance technique. FTIR results indicated that PVP was successfully incorporated into the PVA matrix due to the strong PVP C=O I peak centered at 1672 cm^-1. From the TGA, the increasing concentration of the doped KOH into membranes has little effect on the thermal stability. The homogeneous and compact morphology of the cross-section of the membranes were observed by SEM after conditioned at elevated temperatures and high concentration of KOH(80℃, 10 mol·L^-1). The conductivity of the membrans (1.58×10^-3 S·cm^-1) in 10 mol·L^-1 KOH at 80℃ was 91.5% higher than that in 10 mol·L^-1 KOH at room temperature, which demonstrated the perfect chemical stability of the PVA/PVP alkaline membranes. In addition, the membranes displayed very high oxidative durability. Still 89% and 85% mass of the membrane were retained after 150 h treatment in 3% and 10% H₂O₂ solution at 60℃, respectively. Due to the high dense cross-linkages in polymer matrics, the PVA/PVP/KOH membranes showed good isotropy and conductivity stability in pure water during the measuring time lasted for more than 800 h.