Sol-gel route: An original strategy to chemically stabilize proton exchange membranes for fuel cell

Abstract

We present the elaboration, via a Sol-Gel (SG) route, of a new generation of hybrid membranes for PEMFC applications, in order to improve their performances and durability. The strategy was to create, within a commercial sPEEK membrane, a reactive SG phase able to reduce the oxidative species generated during FC operation and to improve the proton conductivity. The SG content is adjusted by tuning the SG precursors/sPEEK ratio used for the impregnation step. Raman analyses show that a uniform distribution of the SG phase in the membrane section is obtained when NMR analyses demonstrate its high extent of condensation, and reveal the structuring effect of the sPEEK membrane on the SG phase at the nanoscale. The membranes exhibit a better liquid water uptake and proton conductivity than pristine sPEEK membrane up to a SG uptake of 18%, with a gas permeability slightly higher than sPEEK but still lower than the benchmark Nafion. H2O2 accelerated aging tests evidenced the ability of the SG phase to prevent the oxidative degradation of sPEEK. Finally, the FC operability tests showed better and more durable performances for the hybrid membranes, without any increase of the gas permeability during operation.