Size and weight graded multi-layered EAS diffusion electrodes

Claim 2

An electrode for use in electrochemical energy cells which comprises: a porous backing sheet and a catalytically active layer attached to said porous backing sheet having an electrolyte permeable side and a backing sheet contacting side, characterized by said catalytically active layer comprising catalyst and a mixture of hydrophobic agglomerates and hydrophilic agglomerates; the particle size of the hydrophobic agglomerates and the hydrophilic agglomerates increasing from the electrolyte permeable side to the backing sheet contacting side and the weight ratio of hydrophobic material:hydrophilic material increasing from the electrolyte permeable side to the backing sheet contacting side.

Claim 3

An electrode according to claim 1, characterized in that the hydrophobic agglomerates comprise carbon particles and fluorocarbon material; the hydrophilic agglomerates comprise carbon particles, fluorocarbon material and an organic dispersion agent effective to reduce liquid surface tension between the hydrophilic agglomerates; and the catalyst is disposed equally throughout the active layer.

Claim 4

An electrode according to claim 1 or 2, characterized in that said electrode is an air electrode in which the backing sheet is hydrophobic to which is laminated the catalytically active layer which has at least two porous metallic current collectors disposed therein; said hydrophobic agglomerates comprising oxygen absorption/reduction carbon particles having a total surface area of from 30 to 300 square meters per gram; catalyst, low oxygen overvoltage material, and fluorocarbon bonding/nonwetting material; and said active hydrophilic agglomerates comprising oxygen absorption/reduction carbon particles having a total surface area of from 30 to 300 square meters per gram, catalyst, low oxygen overvoltage material; fluorocarbon bonding/non-wetting material, and an organic dispersion agent effective to reduce liquid surface tension between the hydrophilic agglomerates; the weight ratio of active hydrophilic material:active hydrophobic material varying from 1:0.2 at the highly electrolyte permeable side to 1:5 at the hydrophobic sheet contacting side.

Claim 5

An electrode according to claim 4, characterized in that the current collectors in the active layer comprise a metal fiber structure, the catalyst in the active layer is effective for the decomposition of per- hydroxides, and the low oxygen overvoltage material in the active layer is CoW0 4 , WS 2 , nickel spinels, NiS, FeW0 4 , WC, WC coated with 1 wt.% to 20 wt.% Co, or mixtures thereof.

Claim 6

An electrode according to claim 3 or 4, characterized in that the fluorocarbon in the active layer is polytetrafluoroethylene and the catalyst in the active layer is silver, said silver being deposited on the carbon particles.

Claim 7

An electrode of claim 3, 4 or 5, characterized in that the organic dispersion agent is an anionic surfactant, a non-ionic surfactant, or mixtures thereof.

Claim 8

An electrode according to claim 6, characterized in that the organic dispersion agent is octyl phenol ether alcohol, octyl phenol polyether alcohol, nonyl phenol polyether alcohol, alkylpolyether alcohol, alkylaryl polyethylene glycol ether or mixtures thereof.

Claim 9

An electrode according to any of claims 3 to 7, characterized in that the agglomerates in the active layer have a particle size diameter ranging from 150 microns to 2,000 microns.

Claim 10

An electrode according to any of claims 3 to 8, characterized in that the active layer is made up of at least two active material sections with a current collector between adjacent sections and between said backing sheet and said section adjacent thereto.

Claim 11

A metal/air cell, characterized in that said cell comprises a metal electrode, at least one air electrode as claimed in any of claims 3 to 9 and spaced apart from said metal electrode, and an alkali hydroxide electrolyte in contact with said metal and air electrode.

Claim 12

A cell according to claim 10, characterized in that the metal electrode is of iron, zinc, cadmium or aluminum.

Claim 13

A fuel cell characterized in that said cell comprises a fuel electrode, an electrode as claimed in claim 1 or 2 and spaced apart from said fuel electrode, and an electrolyte in contact with said electrodes.