Metal/air cells and improved air electrodes for use therein
First Claim
1. An air electrode for use in electrochemical energy cells comprising:
- A. a hydrophilic layer consisting essentially of1. a hydrophilic composite comprisingi. about 1 part by weight of oxygen absorption/reduction carbon particles having a total surface area of from about 30 to about 600 sq. meters/gram;
ii. about 0.5-4 parts by weight of a low oxygen overvoltage material selected from the group consisting of CuWO4, NiWO4 CoWO4, WS2, WC and WC fuse sinter coated with 1-20 wt.% Co and mixtures thereof;
iii. an effective amount of a bonding/nonwetting agent including at least polytetrafluoroethylene; and
iv. an effective amount of a catalyst for oxygen reduction and decomposition of perhydroxides selected from the group consisting of silver, platinum and silver mercury alloy; and
2. a metal current collector molded into said composite to form a hydrophilic layer; and
B. a hydrophobic layer laminated to said hydrophilic layer.
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Abstract
Air electrodes for use in electrochemical energy cells which comprise a hydrophilic layer and a hydrophobic layer laminated thereto. The hydrophilic layer essentially comprises a hydrophilic composite which includes
I. an oxygen absorption/reduction carbon,
Ii. a material selected from the group consisting of
A. CuWO4, NiWO4, CoWO4 and WC with 1-20 wt. % Co. for a unifunctional electrode, or
B. WS2, WC, and WC with 1-20 Wt.% Co. for a bi-functional electrode, and
Iii. a nonwetting agent containing a polytetrafluoroethylene. A metal current collector is molded into the composite to form a substantially flat hydrophilic layer. A catalyst is preferably incorporated into the composite of a bifunctional electrode to increase cycling life. The hydrophobic layer, comprising a sheet of porous fluorinated ethylene propylene, polypropylene or polytetrafluoroethylene, is laminated to the hydrophilic layer to complete the air electrodes of the invention.
175 Citations
16 Claims
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1. An air electrode for use in electrochemical energy cells comprising:
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A. a hydrophilic layer consisting essentially of 1. a hydrophilic composite comprising i. about 1 part by weight of oxygen absorption/reduction carbon particles having a total surface area of from about 30 to about 600 sq. meters/gram; ii. about 0.5-4 parts by weight of a low oxygen overvoltage material selected from the group consisting of CuWO4, NiWO4 CoWO4, WS2, WC and WC fuse sinter coated with 1-20 wt.% Co and mixtures thereof; iii. an effective amount of a bonding/nonwetting agent including at least polytetrafluoroethylene; and iv. an effective amount of a catalyst for oxygen reduction and decomposition of perhydroxides selected from the group consisting of silver, platinum and silver mercury alloy; and 2. a metal current collector molded into said composite to form a hydrophilic layer; and B. a hydrophobic layer laminated to said hydrophilic layer. - View Dependent Claims (2, 3, 4, 5)
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6. An air electrode for use in electrochemical energy cells capable of non destructive charging comprising:
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A. a hydrophilic layer consisting essentially of 1. a hydrophilic composite comprising i. about 1 part by weight of substantially discrete oxygen absorption/reduction carbon black particles having a particle size range of between about 0.005-0.13 microns and a total probable surface area of from about 30-600 sq. meters/gram.; ii. about 0.5-4 parts by weight of low oxygen over voltage material selected from the group consisting of CuWO4, NiWO4, CoWO4, WS2, WC and WC fuse sinter coated with 1-20 wt.% Co. and mixtures thereof; iii. an effective amount of bonding/nonwetting agent including at least polytetrafluoroethylene; and iv. an effective amount of a catalyst for oxygen reduction and decomposition of perhydroxides selected from the group consisting of silver, platinum and silver mercury alloy; and 2. a metal current collector molded into said composite to form a hydrophilic layer; and B. a hydrophobic layer laminated to said hydrophilic layer. - View Dependent Claims (7, 8, 9, 10, 11, 12)
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13. A metal/air battery comprising a metal electrode selected from the group consisting of iron, zinc and cadmium;
- at least one electrode, effective to allow non destructive battery charging at between about 0.50-0.75 volts above a Hg/HgO reference electrode, spaced apart from said metal electrode, the electrode comprising;
A. a hydrophilic layer consisting essentially of 1. a hydrophilic composite comprising i. acetylene black carbon; ii. a low oxygen over voltage material selected from the group consisting of CuWO4, NiWO4, CoWO4, WS2, WC and WC fuse sinter coated with 1-20 wt.% Co. and mixtures thereof; iii. an effective amount of bonding/non-wetting agent including at least polytetrafluoroethylene; and iv. an effective amount of a catalyst for oxygen reduction and decomposition of perhydroxides selected from the group consisting of silver, platinum and silver mercury alloy; and - View Dependent Claims (15, 16)
- at least one electrode, effective to allow non destructive battery charging at between about 0.50-0.75 volts above a Hg/HgO reference electrode, spaced apart from said metal electrode, the electrode comprising;
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14. A metal current collector molded into said composite to form a substantially flat hydrophilic layer;
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B. a hydrophobic layer laminated to said hydrophilic layer; and
an alkali hydroxide electrolyte in contact with said metal electrode and the hydrophilic layer of said air electrode.
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Specification