全钒液流电池用质子传导膜研究进展

Research advances of proton conductive membranes for vanadium redox flow battery

全钒液流电池(VRB)作为一种大规模蓄电储能装备,在可再生能源发电和节能技术领域将发挥重要作用。质子传导膜是VRB中的关键材料之一,其作用主要有两方面:传导质子连通电堆内电路;阻止正负极电解液间不同价态钒离子的相互渗透,避免能量损失。质子传导膜性能对电池效率和成本有重要影响。在分析VRB基本原理基础上,阐明质子传导膜需同时满足优良的导电性、阻钒性、稳定性和合理成本等要求。以高分子膜的化学组成与物理结构的演化过程为线索,分别论述三类膜材料,包括Nafion系列膜、非全氟型质子传导膜、纳米尺度孔径的多孔膜。在归纳现有膜材料化学结构、物理性质与电学性能的基础上,阐述高性能质子传导膜的重点研究方向与发展前景。

Vanadium redox flow battery （VRB）, which is regarded as one of the most promising devices for massive electricity storage in renewable energy and energy-saving processes, has attracted much attention, because of its long life-time, simple configuration and independent power and capacity ratings. Proton conductive membrane, one of key materials in VRB, performs the role of conducting protons during charge/discharge recycle, and prevents vanadium ions from direct contact between the positive and negative electrolytes. To achieve high energy efficiency, long life and low cost of VRB stack, the membrane should meet the requirements of high conductivity, chemical and mechanical resistance, low permeability of vanadium ions and acceptable cost. So far, Nafion membranes are generally employed in VRB due to their both high conductivity and chemical stability, however, their extremely high cost and poor ion selectivity have become the main barrier of commercialization of VRB. In this review, a detailed introduction about recent progress in the field of proton conductive membranes for VRB is given, including three aspects. （i） post-treated Nafion membranes to improve selectivity; （ii） non-perfluorinated membranes from polymerization and sulfonation of monomers; and （iii） nano-porous membranes based on difference between ion stokes radius and its valence, which provides selectivity for protons towards vanadium ions. Finally, there is a highlight of the relationship between morphology and performance of the advanced proton conductive membranes for research and development in future.