A multilayered membrane for vanadium redox flow battery

In order to reduce the vanadium ions permeability of membranes used in vanadium redox flow battery (VRB) while keeping its chemical stability, sulfonated poly(ether ether ketone) (SPEEK)/polypropylene (PP)/perfluorosulfonic acid (PFSA) layered composite membrane (we name it as S/P/P membrane) has been fabricated and characterized. In the S/P/P membrane, polypropylene plays a role of central layer, which is sandwiched by SPEEK and PFSA layer. Results show that S/P/P membrane presents a very low permeability of vanadium ions, accompanied by slightly higher area resistance than that of Nafion 212 membrane (N212). The VRB single cell with S/P/P membrane shows higher coulombic efficiency but lower voltage efficiency in comparison with the one with N212. The performance of VRB with S/P/P membrane can be maintained after more than 50 cycles. Our experimental results suggest that the S/P/P membrane approach is a promising strategy to suppress the migration of vanadium ions in VRB, while retaining an outstanding VRB performance.

► A sandwich-type SPEEK/PP/PFSA composite membrane has been prepared.
► The delamination phenomena of PFSA and SPEEK layer can be avoided with this design.
► The SPEEK and PFSA layer are exposed to negative and positive half-cell electrolytes, respectively, in order to use the advantages of the SPEEK layer (low permeability of vanadium ions) and PFSA layer (good antioxygenic property).
► The S/P/P membrane displays much lower vanadium ions permeability and good cell performance compared to N212 membrane.