Applications of Porous Glass Membranes in Redox-Flow-Batteries - Investigations on the Influence of Membrane Thickness, Pore Structure and Surface Modification

2014年4月13日IPCC第五次评估报告第三次分报告摘要指出，尽管气候保护工作持续进行，但温室气体排放仍在迅速增加。因此，有必要加强在可再生能源领域的活动。与发电同样重要的是储能。氧化还原液流电池（RFB）特别适合于这一目的，与锂离子电池等相比，它表现出高效率和相对较低的成本。他们的模块化设计便于生产从少数单个到数百个并行和串行单元的堆栈。尽管如此，这种电池仍然存在不足之处，比如电流密度相对较低，所用膜的材料成本较高，以及离子通过膜的交叉，这会导致混合电位的形成，从而污染所用的电解质。虽然rfb中的电解质系统不断得到增强和优化，但所使用的分离器仍然主要由非多孔且昂贵的Nafion®组成。虽然其他材料和复合材料也被研究作为隔膜/膜的适用性，但这些主要是聚合物基的。机械和化学稳定的多孔玻璃（PG）几乎没有被研究，即使它们显示出各种各样的好处。多孔玻璃膜提供了灵活修改其宏观几何形状，孔径和表面性质的可能性。因此，多孔玻璃膜应完全适应rfb的条件。使用PG膜允许高电流密度和电导率，并通过调整适当的表面特性来防止离子交叉。因此，PG膜是系统研究孔隙率、孔径、孔结构、膜厚度、表面电荷、表面能等不同参数对rfb性能影响的理想模型系统，这在科学文献中存在争议。因此，我们认为将这两种现代技术以一种新颖的方式结合起来是合理的。为此，将在钒氧化还原液流电池中生产并研究具有定制性能的多孔玻璃膜。所得结果将与相同条件下对Nafion®膜的估计结果进行比较。

In an abstract of the 3rd sub-report of the 5th assessment report of the IPCC from 13.04.2014 it is stated that the greenhouse gas emission is rapidly increasing, though continuous work on climate protection. Therefore, it is necessary to intensify the activities in the field of regenerative energy. Just as important as power generation is also its storage. Redox-Flow-Batteries (RFB) are particularly suited for this purpose, showing high efficiencies as well as relatively low costs compared with, for example, Lithium ion batteries. Their modular design facilitates the production of stacks with few individual to several hundreds of parallel and serial cells. Though, such cells still show deficiencies, like relatively low current densities, high material costs of the used membranes as well as an ion crossover through the membrane, which leads to the formation of mixed potentials and thus to contamination of the electrolytes used. While the electrolyte systems in RFBs have continuously been enhanced and optimized, the separators used still mainly consist of nonporous and expensive Nafion®. Although other materials and composites are examined regarding their applicability as separators/membranes, these are mainly polymer based.Mechanically and chemically stable porous glasses (PG) are almost not investigated, even though they show a variety of benefits. Porous glass membranes provide the possibility of the flexible modification of their macroscopic geometry, pore sizes and surface properties. Hence porous glass membranes should be fully adaptable to the conditions in RFBs. The use of PG membranes allows high current densities and conductivities and the prevention of ion crossover by adjusting adequate surface properties. Thus, PG membranes represent an ideal model system for systematic investigations on the influence of different parameters, like porosity, pore size, pore structure, membrane thickness, surface charge, surface energy, etc., on the performance of RFBs, which is discussed controversially in the scientific literature.Therefore, we think it is reasonable to combine these two modern technologies in a novel way. For this purpose, porous glass membrane with tailor-made properties will be produced and investigated in a Vanadium Redox-Flow-Battery. The obtained results will be compared to those estimated for Nafion® membranes under the same conditions.