Electrochemical device using multicomponent composite membrane film

An electrochemical element comprising electrochemical cells which are multiply-stacked, wherein

• a) said electrochemical cells are formed by stacking:
• i) fuel cells having a positive electrode, a separator layer, and an negative electrode sequentially as a basic unit;
• or
• ii) {circle around (1)} bicells having a positive electrode, a separator layer, a negative electrode, another separator layer, and another positive electrode sequentially as a basic unit or
• {circle around (2)} bicells having a negative electrode, a separator layer, a positive electrode, another separator layer, and another negative electrode sequentially as a basic unit;
• and
• iii) a separator layer interposed between each stacked cell;
• b) each of said separator layers comprise a multi-component composite membrane comprising:
• i) a porous polymeric support layer and
• ii) a porous gellable polymer layer which is formed on one side or both sides of the porous polymeric support layer,
• wherein said porous polymeric support layer and the porous gellable polymer layer have the same or different pore size and are united with each other.