MULTILAYER STRUCTURE FOR ELECTRODE-MEMBRANE ASSEMBLY AND ELECTROLYTIC PROCESS THEREBY

摘要

A unitary membrane-electrode assembly includes a structure with multiple layers having different overvoltages for the desired electrochemical reaction. The layer attached to the membrane has a higher overvoltage for the electrochemical reaction than the electrode layer attached to its upper surface thereby preferentially locating the electrochemical reaction zone a small but controlled distance away from the membrane surface. In an alkali metal halide or alkali metal sulfate electrolysis process the use of a unitary dual layer structure with a bonded remote electrode is particularly useful as a cathode side structure because it eliminates formation of concentrated caustic at the membrane surface. As a result, back migration of OH-ions is reduced and cathodic current efficiency is increased.