Degradation mechanisms of MEA characteristics during water electrolysis in solid polymer electrolyte cells

Resumo

The processes contributing to degradation of characteristics of membrane-electrode assemblies (MEA) of water electrolyzers with solid polymer electrolyte (SPE) are considered. Particularly, the life tests of an electrolysis cell with SPE reveal the migration of platinum from the cathodic active layer and its deposition in membrane’s near-cathode region. In addition to platinum, several other elements (Ti, Ir, Fe, Ni, Si) are detected in the membrane, carried there with the water-reagent from the structural elements of MEA, electrolysis cell, and its outer framing (anodic electrocatalytic layer, half-cells, tubes, water tank-separator, etc.). The observed considerable loss of platinum in the cathodic catalytic layer leads to a decrease in its activity (due to the decrease in concentration of platinum nanoparticles and the loss of their cohesion), while the appearance in the membrane of platinum and other ions that have the lower mobility as compared with hydrogen ions gives rise to modifications in the membrane structure thus increasing the electrolysis potential in the course of life tests.