Electrochemical cell having gas pressurized contact between laminar, gas diffusion electrode and current collector

In an electrochemical reaction process conducted in an electrochemical cell comprising a gas compartment, a semi-permeable membrane disposed between a cathode and an anode so as to form a catholyte compartment and an anolyte compartment, said catholyte compartment containing said cathode and a volume of catholyte, said anolyte compartment containing said anode and a volume of anolyte, the adjacent surfaces of said anode and said cathode being spaced apart sufficiently for said membrane to fit freely therebetween, the process improvement comprising:

• utilizing a gas diffusion electrode assembly consisting of
• (1) a gas diffusion laminar electrode having an electrically conductive, porous hydrophilic layer comprising conductive carbon and a polymeric binder therefor, and a porous, hydrophobic layer comprising a hydrophobic polymer and
• (2) an electrically conductive current collector means in contact with said hydrophilic layer
• whereby the electrical potential required to operate said electrochemical cell is reduced by establishing and maintaining sales by gas pressure said hydrophilic layer of said electrode in contact with said current collector means.

In a process for the electrolysis of an alkali metal halide brine wherein an aqueous brine is introduced into an anode compartment of an electrolytic cell containing a gas compartment;

• water or aqueous alkali metal hydroxide is introduced into a cathode compartment of the cell;
• said cathode and anode compartments are separated by a semi-permeable membrane;
• halogen and depleted brine are withdrawn through a common first conduit from the anode compartment to a brine collection point;
• and alkali metal hydroxide solution is withdrawn through a second conduit from the cathode compartment to an alkali metal hydroxide solution collection point;
• the improvement comprising providing as the cathode of said electrolytic cell, a laminar, gas diffusion cathode comprising an electrically conductive, porous hydrophilic layer and a porous hydrophobic layer adjacent to said gas compartment wherein gas pressure applied to said hydrophilic layer at a pressure is solely sufficient to force said cathode against a current collector means so as to make and maintain electrical contact in order to minimize the electrical potential required for electrolysis.