Method of producing a gas diffusion electrode

Claim 1

A method of producing a gas diffusion electrode comprising the steps of: (a) preparing a dry, finely divided wetproofing mixture comprising a wetproofing agent and a pore forming agent; (b) preparing a plurality of dry, finely divided active mixtures each comprising an electrochemically active material, a wetproofing agent, and a pore forming agent, said active mixtures each containing a different weight proportion of electrochemically active material; (c) providing an electrically conductive current collector; (d) applying said wetproofing and active mixtures in superimposed layers to said current collector, the active mixture layers all being present on one side of the wetproofing mixture layer and arranged therefrom in layers of progressively increasing weight proportion of electrochemically active material, at least one active mixture layer being contiguously associated with said current collector, to form an article comprising said current collector and a multiplicity of superimposed layers of finely divided loose mixtures of particles; (e) pressing said article to form an electrode; and (f) removing said pore-forming agent from said electrode.

Claim 2

A method of producing a gas diffusion electrode comprising the steps of: (a) preparing a dry, finely divided wetproofing mixture comprising a wetproofing agent and a pore forming agent; (b) preparing a plurality of dry, finely divided active mixtures each comprising an electrochemically active material, a wetproofing agent, and a pore forming agent, said active mixtures each containing a different weight proportion of electrochemically active material; (c) providing an electrically conductive current collector; (d) applying said wetproofing and active mixtures in superimposed layers to said current collector, the active mixture layers all being present on one side of the wetproofing mixture layer and arranged therefrom in layers of progressively increasing weight proportion of electrochemically active material, at least one active mixture layer being contiguously associated with said current collector, to form an article comprising said current collector and a multiplicity of superimposed layers of finely divided loose mixtures of particles; (e) pressing said article to form an electrode; and (f) removing said pore-forming agent from said electrode.

Claim 16

A method of producing a gas diffusion electrode comprising the steps of: (a) preparing a dry, finely divided wetproofing mixture comprising polytetrafluoroethylene and pore-forming salt; (b) preparing a dry, finely divided precious metal-containing active mixture comprising polytetrafluoroethylene, a pore-forming salt, and activated carbon containing a precious metal catalyst selected from the group consisting of silver, gold, and metals of the platinum group including platinum, palladium, rhodium, ruthenium, osmium, and iridium; (c) preparing at least one additional dry, finely divided active mixture, said additional active mixture comprising polytetrafluoroethylene, a pore-forming salt, and activated carbon in a lower weight proportion than in said precious metal-containing active mixture; (d) providing an electrically conductive current collector; (e) applying said wetproofing and active mixtures in superimposed layers to said current collector, the active mixture layers all being present on one side of the wetproofing mixture layer and arranged therefrom in layers of progressively increasing weight proportion of activated carbon, the precious metal-containing active mixture layer being contiguously associated with said current collector, to form an article comprising said current collector and a multiplicity of superimposed layers of finely divided loose mixtures of particles; (f) hot pressing said article at temperature from about 60° to 350° C. and at pressure from about 1,000 to 10,000 psi to form an electrode; and (g) removing said pore-forming salt from said electrode.

Claim 17

A method of producing a gas diffusion electrode comprising the steps of: (a) preparing a dry, finely divided wetproofing mixture comprising polytetrafluoroethylene and pore-forming salt; (b) preparing a dry, finely divided precious metal-containing active mixture comprising polytetrafluoroethylene, a pore-forming salt, and activated carbon containing a precious metal catalyst selected from the group consisting of silver, gold, and metals of the platinum group including platinum, palladium, rhodium, ruthenium, osmium, and iridium; (c) preparing at least one additional dry, finely divided active mixture, said additional active mixture comprising polytetrafluoroethylene, a pore-forming salt, and activated carbon in a lower weight proportion than in said precious metal-containing active mixture; (d) providing an electrically conductive current collector; (e) applying said wetproofing and active mixtures in superimposed layers to said current collector, the active mixture layers all being present on one side of the wetproofing mixture layer and arranged therefrom in layers of progressively increasing weight proportion of activated carbon, the precious metal-containing active mixture layer being contiguously associated with said current collector, to form an article comprising said current collector and a multiplicity of superimposed layers of finely divided loose mixtures of particles; (f) hot pressing said article at temperature from about 60° to 350° C. and at pressure from about 1,000 to 10,000 psi to form an electrode; and (g) removing said pore-forming salt from said electrode.