Surface proton hopping conduction mechanism dominant polymer electrolytes created by self-assembly of bicontinuous...

For the development of the next generation of fuel cells, it is essential to create an innovative design principle of polymer electrolytes that is beyond extension of the existing strategy. In the present study, we focused on the surface hopping proton conduction mechanism where an activation energy for proton conduction is greatly reduced by decreasing the distance between SO₃^- groups. Our gyroid nanostructured polymer film (Film-G), with a hydrophilic surface where the SO₃^- groups are aligned densely and precisely, shows high proton conductivity of the order of 10^-2 S cm^-1 when the water content is about 15 wt%. We reveal that the high proton conductivity of Film-G is attributed to the exhibition of an extremely-fast surface hopping conduction mechanism due to the reduced activation energy barrier along the gyroid minimal surface. This finding should introduce a game-changing novel opportunity in polymer electrolyte design.