Long-Term Stability of Nafion Hybrid Membranes for Use in Vanadium Redox-Flow Batteries

The membrane is the key component of a redox-flow system. It should possess high proton conductivity and should avoid cross contamination due to the diffusion of ions of the active material through membrane pores. A membrane with drastically reduced cross contamination ability would overcome the main problem of several redox couples and in consequence it would allow redox-flow systems with higher energy density and lower material costs. In previous works cross contamination of Nafion membranes could have been reduces significantly by several modification methods with SiO2 nano particles. This work deals with the long-term stability of this improvement that was investigated by cycling modified membranes for several weeks and analyzing the electrical performance in dependency of time. Nafion membrane modified with TEOS/DEDMS/NH3 showed a very good long-term stability.