Renewable sources like solar and wind power are received more and more attention due to the critical issues of energy shortage and air pollution. However, for renewable energy to be competitive with fossil fuels, it need to be cost effective and reliable. Energy storage especially large scale energy storage is the key technology to achieve this. As one kind of energy storage techniques, a vanadium flow battery (VFB) is well-suited for large-scale energy storage applications due to its attractive features like high safety, high efficiency, long cycle life and flexible design. As a key component of a VFB, a membrane plays the role of transferring ions from the anode to cathode as well as preventing cross mixing of the positive and negative electrolytes. The membranes traditionally used in VFB are perfluorinated polymers such as Dupont Nafion®. Although they show both high proton conductivity and chemical stability, the extremely high cost and low ion selectivity of these membranes (high vanadium crossover) have limited their further commercialization. The non-perfluorinated hydrocarbon polymers like sulfonated or quaternary ammoniated aromatic polymers are widely investigated due to their advantages like high selectivity and low cost, however, these membranes often suffer from poor chemical instability, which is proved to be induced by the introduction of ion exchange groups. We first reported the application of porous membranes in VFB 1. The idea is based on separating vanadium ions from protons via pore size exclusion. The new design and concept can potentially overcome the traditional restriction from ion exchange membranes and provide more materials option. Followed our idea, different kinds of porous membranes were explored and investigated in VFB. The relation between membrane morphology and performance was studied in detail. Based on the results series porous membranes from different polymers with different morphologies were successfully developed and very impressive results were obtained. In this presentation, the recent progress and challenge of porous membranes in the application of VFB will be demonstrated.

Porous membranes for flow battery application

254th National Meeting (2017)

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