全钒液流电池用致密皮层非对称AEM结构优化

Morphology optimization of defect-free skinned asymmetric anion exchange membranes for all-vanadium flow battery

采用双凝胶浴相转化方法制备了厚度可控的具有致密皮层的季铵化聚砜非对称阴离子交换膜(AEM),应用于全钒液流电池.超薄无缺陷皮层保证了膜的阻钒能力.同时,与致密季铵化聚砜AEM相比,致密皮层季铵化聚砜非对称AEM的面电阻(AR)大幅度降低.通过改变初生态膜浸入正戊醇的时间,可以调节膜的形貌和性质,从而平衡膜的阻钒能力和AR.当浸入正戊醇的时间为20 s时,制备的致密皮层季铵化聚砜非对称AEM DC40%-20s的等效厚度大约为3.87μm,实现膜阻钒能力和AR的最好平衡,并获得了良好的电池性能(在60 mA/cm^2下,库伦效率为98.2%,电压效率为82.5%,能量效率为81.0%)和适中的放电容量衰减速率(在50 mA/cm^2下,0.57%/圈).

A dual-coagulation bath phase inversion method was used to prepare a defect-free skinned asymmetric quaternized polysulfone anion exchange membranes(AEMs) with controllable equivalent thickness which were applied to all-vanadium flow battery. The ultra-thin, defect-free skin layer guarantees the vanadium blocking ability of the membrane. At the same time, the area resistance(AR) of the defect-free skinned asymmetric AEM is greatly reduced compared with the dense AEM, mainly due to the interconnected pore structure in the support layer. By changing the immersion time of chloromethylated polysulfone solution in n-pentanol, the morphology and properties of the membranes can be adjusted, thus balancing the vanadium blocking ability and AR of the membrane. When the immersion time in n-pentanol was 20 s, the equivalent thickness of the prepared defect-free skinned asymmetric quaternized polysulfone AEM DC40%-20 s was about 3.87 μm, achieving the optimum balance of vanadium blocking ability and AR. The flow battery assembled with DC40%-20 s achieved good battery performance(at 60 mA/cm^2, coulombic efficiency: 98.2%;voltage efficiency: 82.5%;energy efficiency: 81.0%) and moderate discharge capacity decay rate(0.57% per cycle at 50 mA/cm^2).