Abstract An electrically rechargeable metal/air or metal/oxygen depolarized electrochemical cell and a method of generating electricity therefrom are described. The electrochemical cell comprises an anode capable of being regenerated and a composite cathode having an oxygen-permeable, hydrophobic member layered with catalyst and a bi-porous unit. The coarse pore layer of the bi-porous unit is in contact with the catalyst. A bubble barrier which can be integral with either the anode or composite cathode is in contact with the fine pore layer of the bi-porous unit. During discharge of the cell, the bi-porous unit is flooded with electrolyte and merely acts as a current collector. When charging, oxygen evolution occurs at the fine pore layer and, due to the bubble barrier, the evolved oxygen is forced into the coarse pore layer displacing the electrolyte, thereby protecting the catalyst layer from damage due to oxygen evolution and the high charging potential.
The cell of claim 1 wherein the bi-porous unit is an integral structure.
Claim 2
Dependent Claim
19 words
The cell of claim 1 wherein the coarse pore face and fine pore face are separate and distinct layers.
Claim 3
Dependent Claim
13 words
The cell of claim 3 wherein the coarse pore layer is a mesh.
Claim 4
Dependent Claim
39 words
The cell of claim 3 wherein the coarse pore layer is of a nonconductive material and the fine pore layer is of a conductive material, the fine pore layer and catalyst layer being in electrical contact at their peripheries.
Claim 5
Dependent Claim
23 words
The cell of claim 3 wherein the fine pore layer of said bi-porous unit has a lower oxygen over-potential than said catalyst layer.
Claim 6
Dependent Claim
24 words
The cell of claim 6 wherein said anode is a metal taken from the group consisting of zinc, cadmium, lead, iron, and mixtures thereof.
Claim 7
Dependent Claim
20 words
The cell of claim 7 in which the anode is porous zinc having from 40 percent to 85 percent porosity.
Claim 8
Dependent Claim
14 words
The cell of claim 1 wherein the bubble barrier is integral with the anode.
Claim 9
Dependent Claim
14 words
The cell of claim 1 wherein the bubble barrier is integral with said cathode.
Claim 10
Dependent Claim
11 words
The cell of claim 1 wherein the hydrophobic membrane is polytetrafluoroethylene.
Claim 11
Dependent Claim
14 words
The cell of claim 11 wherein said electrocatalyst is admixed with a hydrophobic binder.
Claim 12
Dependent Claim
11 words
The cell of claim 12 wherein said hydrophobic binder is polytetrafluoroethylene.