▎ 摘　　要

NOVELTY - An ion-conducting membrane (1) comprises: (i) a first ion-conducting layer (2) containing first ion-conducting polymer; and (ii) a barrier layer (3) containing graphene-based platelets. The ion-conducting membrane further comprises a second ion-conducting layer (4) containing at least one second ion-conducting polymer, where the second ion-conducting layer is applied to a face of the barrier layer not in contact with the first ion-conducting layer. USE - In catalyst-coated ion-conducting membrane; in membrane electrode assembly (claimed); and in electrochemical devices such as hydrogen-fuelled proton exchange membrane fuel cell (PEMFC) and direct methanol fuel cell (DMFC). ADVANTAGE - The ion-conducting membrane has increased durability and fuel efficiency. When the ion-conducting membranes are used in hydrogen-fuelled PEMFCs or DAFCs, reduced reactant cross-over is seen resulting in a reduction of a mixed potential on the cathode, there is reduced wastage of reactant fuel, and for hydrogen-fuelled PEMFCs, peroxide formation, which causes damage to the membrane, is reduced or eliminated. DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for the following: (1) a catalyst-coated ion-conducting membrane comprising the ion-conducting membrane and an electrocatalyst layer deposited on at least one side of the ion-conducting membrane; and (2) a membrane electrode assembly comprising the ion-conducting membrane or catalyst-coated ion-conducting membrane. DESCRIPTION OF DRAWING(S) - The figure shows a schematic diagram of an ion-conducting membrane. Ion-conducting membrane (1) First ion-conducting layer (2) Barrier layer (3) Second ion-conducting layer (4)