Abstract An electrode suitable for use as a fluid electrode in a fuel cell or a metal-air cell, for example, is provided comprised of an electronically conductive carrier having narrow pores extending through its thickness. The pores have an average diameter less than one-tenth the thickness of the carrier. In a preferred form the carrier is a sintered plaque. An electrocatalyst lies in the pores in intimate contact with the carrier and a hydrophobic material lies in the pores and overlies the electrocatalyst. The hydrophobic material is uniformly distributed in the pores. In another aspect my invention is directed to process of manufacturing a hydrophobic fluid electrode. A finely divided particulate electrocatalytically active material is dispersed in water and delivered to one face of a carrier while a vacuum is drawn adjacent the opposite face. The aqueous dispersion is passed through until the desired level of electrocatalyst loading is achieved, and the loaded carrier is then impregnated with hydrophobic agent. The hydrophobic agent is cured by heating to complete formation of the electrode. In a preferred technique the aqueous dispersion is continuously recirculated through the carrier to make maximum utilization of the dispersed electrocatalyst. Preferably the carrier is compressed after loading but before wetproofing.
delivering said fluid medium with the active material dispersed to said upper major face of said substrate in said funnel at a rate less than the rate of transport through the substrate to inhibit surface deposition of said active material;
Claim 2
Dependent Claim
34 words
The process of claim 1 including drawing a portion of the ambient atmosphere through the substrate along with the fluid medium during deposition of the electrochemically active material in the pores of the substrate.
Claim 3
Dependent Claim
59 words
The process of claim 1 including the step of impregnating the substrate with hydrophobic agent by spraying the liquid dispersant onto the substrate at a rate below the maximum rate at which the fluid medium can enter the pores of the substrate and simultaneously heating the substrate so that the fluid medium is evaporated as it penetrates the substrate.
Claim 4
Dependent Claim
74 words
collecting the fluid medium after it passes through said substrate and recirculating it through said substrate in the same direction until a catalyst loading of about 2.5 mg/cm2 of substrate surface is achieved; e. impregnating the substrate with a liquid dispersion of a linear halocarbon hydrophobic agent having a critical surface tension less than 32 dynes/cm; and f. heating the substrate to (1) drive off the liquid dispersant; and (2) sinter the linear halocarbon.
Claim 5
Dependent Claim
23 words
The process of claim 1 including repeating the steps of impregnating with hydrophobic agent and heating the substrate after the first heating step.
Claim 6
Dependent Claim
19 words
The process of claim 1 including the step of compacting the substrate prior to impregnation with the hydrophobic agent.
Claim 7
Dependent Claim
30 words
The process of claim 5 in which said compacting step follows deposition of the electrochemically active material in the pores so that the active material is locked within the pores.
Claim 8
Dependent Claim
26 words
The process of claim 1 including the step of impregnating the substrate with hydrophobic agent by immersing the substrate in an aqueous suspension of hydrophobic agent.
Claim 9
Dependent Claim
23 words
The process of claim 7 including reducing the pressure ambient to the aqueous suspension of hydrophobic agent while the substrate is immersed therein.