Research and application of  Ion Conducting Membranes for Flow Battery

Huamin Zhang

Division of Energy Storage, Dalian Institute of Chemical Physics, Chinese Academy of Sciences

Abstract: Increasing attention for large scale energy storage has recently emerged, e.g. due to urgent needs in grid management (load leveling and peak shaving), as backup power, or for utilization and integration of renewable energy sources. Flow batteries, vanadium flow batteries (VFBs) in particular, are regarded as the ideal choices for such large scale energy storage due to their perfect combination of high efficiency, high reliability, long cycle life and cost effectiveness1. Demonstrations in different application fields have recently confirmed the availability of VFBs for large scale energy storage.However, the commercial progress of VFBs has so far been limited by the high cost (500-700 dollar/m2)and low selectivity of the appliedperfluorinated membranes (Nafion)3. Thus, considerable efforts have been devoted to searching for a high performance membrane. The non-perfluorniated ion exchange membranes are proved to have high selectivity and conductivity, however, their low stability, which induced by ion exchange groups, has limited their further application.  The group from DICP has devoted to membranes research for several years, where porous ion conducting membranes were successfully introduced in VFB. The idea was to separate the larger vanadium ions from the small protons via pore size exclusion, where the stability issues were internally solved. Based on this concept, several kinds of porous membraneshave been designed and fabricated for potential use in VFBs, like polyacrylonitrile (PAN), poly (vinylidene fluoride) (PVDF) and polytetrafluoroethylene (PTFE). Further membrane modifications based on structuraldesign and self-assembly have been carried out to optimize the membrane performances as well.

In this presentation, the progress on membrane research at DICP will be introduced in detail.