Elektrospun, ion-conducting polymer membranes as solid electrolytes

本课题拟合成由不同离子配位聚合物和导电盐添加剂组成的电纺固体电解质。在确定和优化电化学性能后，我们打算确定离子通过膜的潜在传导机制。四种不同的聚合物，精选的Li， Na和Mg导电盐和添加剂将通过静电纺丝制备纤维膜。我们将测试这些膜的热、机械和电化学性能，以确定性能最好的离子导电系统。四种不同的聚合物，聚乙烯氧化物（PEO），聚丙烯腈（PAN），聚甲基丙烯酸甲酯（PMMA），聚偏氟乙烯（PVdF）和选定的导电盐将被静电纺成纤维膜，然后通过热分析，x射线衍射和温度相关阻抗谱根据它们的结晶度和离子电导率进行检测。选定的离子传导系统将通过固态核磁共振波谱检查，以确定其局部离子动力学。电纺Li和na基导电salt@polymer体系的离子电导率比具有较高导电盐浓度的溶液或热压样品的离子电导率提高了一到两个数量级。两种体系的电化学稳定性具有可比性。甚至PVdF也表现出显著增强的离子电导率作为电纺LiBF4@PVdF膜。在静电纺固体电解质膜的成功合成和表征后，我们将通过润滑剂和纳米级惰性材料来增强和优化其机械和电化学性能。根据光谱结果，我们将推导出不同膜系统的潜在传导机制。由于纤维膜的本征各向异性，这种机制将明显不同于最先进的热压样品的溶液铸造。我们打算实现电纺丝固态电解质体系，其在室温下的电导率为>0 - 3 S cm - 1，热稳定性为> 80°C，并具有足够的机械和电化学稳定性。目的是了解与传统合成的溶液铸造或热压系统相比，静电纺丝膜的离子迁移率和电导率的增加，并优化这些系统，以便在固态电池和超级电容器中应用。

In the proposed project we intend to synthesize electrospun solid electrolytes composed by different ion-coordinating polymers and conductive salt additives. After determination and optimization of the electrochemical properties we intend to identify the underlying conduction mechanism for the ion transport through the membranes. Four different polymers, selected Li, Na and Mg conductive salts and additives will be used to prepare fiber membranes via electrospinning. Such membranes will be tested concerning their thermal, mechanical and electrochemical properties in order to identify the best performing ion conductive systems. Four different polymers, polyethylene oxide (PEO), polyacrylonitrile (PAN), polymethyl¬ methacrylate (PMMA), polyvinylidene fluoride (PVdF), and selected dissolved conductive salts will be electrospun to fiber membranes which will be examined by thermal analysis, X-ray diffraction and temperature-dependent impedance spectroscopy according their crystallinity and ion conductivity afterwards. Selected ion conducting systems will be checked by solid state NMR spectroscopy to determine their local ion dynamics. Electrospun Li and Na-based conductive salt@polymer systems showed one to two orders of magnitude enhanced ion conductivity than comparable solution cased or hot-pressed samples with higher conductive salt concentration. The electrochemical stability of the two systems kept comparable. Even PVdF showed a significant enhanced ion conductivity as an electrospun LiBF4@PVdF membrane. After the successful synthesis and characterization of electrospun solid electrolyte membranes we will enhance and optimize the mechanical and electrochemical properties by lubricants and nano-scaled inert materials. Based on the spectroscopic results we will derive the underlying conduction mechanisms of the different membrane systems. Due to the intrinsic anisotropy of the fiber membranes this mechanism will be significantly different than for the state-of-the-art solution-casted of hot-pressed samples. We intend to achieve electrospun solid state electrolyte systems with conductivities > 10−3 S cm−1 at room temperature, thermal stability > 80°C and a sufficient mechanical and electrochemical stability. The aim is to understand the increase of the ion mobility and conductivity of the electrospun membranes compared with conventionally synthesized solution-casted or hot-pressed systems, and to optimize such systems for a potential usage in sild state battery and super capacitor applications.