Ionic Mobility in Ion-Exchange Membranes

Abstract

Membrane technologies are widely demanded in a number of modern industries. Ion-exchange membranes are one of the most widespread and demanded types of membranes. Their main task is the selective transfer of certain ions and prevention of transfer of other ions or molecules, and the most important characteristics are ionic conductivity and selectivity of transfer processes. Both parameters are determined by ionic and molecular mobility in membranes. To study this mobility, the main techniques used are nuclear magnetic resonance and impedance spectroscopy. In this comprehensive review, mechanisms of transfer processes in various ion-exchange membranes, including homogeneous, heterogeneous, and hybrid ones, are discussed. Correlations of structures of ion-exchange membranes and their hydration with ion transport mechanisms are also reviewed. The features of proton transfer, which plays a decisive role in the membrane used in fuel cells and electrolyzers, are highlighted. These devices largely determine development of hydrogen energy in the modern world. The features of ion transfer in heterogeneous and hybrid membranes with inorganic nanoparticles are also discussed.

Molecular and Ionic Diffusion in Ion Exchange Membranes and Biological Systems (Cells and Proteins) Studied by NMR

“…For this goal achievement, Nafion membranes were modified by inorganic dopants. The membrane modification and membrane conductivity properties specify in [ 119 ].…”

Membrane Technologies for Decarbonization

“…This leads to the formation of a system of pores and channels in membranes filled with an aqueous solution containing protons formed during the dissociation of functional groups, and their walls contain ions [202,203]. The presence of a bound system of pores containing an acidic solution leads to the presence of extremely high proton conductivity in such membranes [204,205]. The conductivity of membranes is largely determined by the size of the channels and the degree of hydration, which in turn is related to their ion-exchange capacity.…”

Nafion/Surface Modified Ceria Hybrid Membranes for Fuel Cell Application

“…In recent years, there has been an increasing interest in the modification of cation-exchange membranes by introducing inorganic oxides into the membrane pores and the channels system. Most of the works in this area are devoted to silica and zirconia [ 1 , 2 , 3 , 4 , 5 , 6 ], while far too little attention has been paid to ceria [ 7 , 8 , 9 ]…”

“…In recent years, there has been an increasing interest in the modification of cationexchange membranes by introducing inorganic oxides into the membrane pores and the channels system. Most of the works in this area are devoted to silica and zirconia [1][2][3][4][5][6], while far too little attention has been paid to ceria [7][8][9] During operation of low-temperature fuel cells (FCs), hydrogen peroxide and other reactive oxygen species (hydroxyl radicals, superoxide radicals) are generated in a number of side electrochemical reactions. These radicals cause proton-exchange membranes to degrade and decrease FC power [10][11][12][13].…”