Diamond Shamrock Corporation

Eltech Systems Corporation

Diamond Shamrock Chemicals Company

Electromedia, Inc.

Frank Solomon

Charles Grun

Lawrence J Gestaut

Yury Genodman

Marilyn J Niksa

Gerald R Pohto

Douglas J Wheeler

Andrew J Niksa

James J Stewart

Thomas J Schue

Thomas R Turk

Donald W Abrahamson

Donald F Lieb

Ronald L LaBarre

Leslie K Lakatos

Jaime Irizarry

Daniel P Hagel

A platinum black air cathode has an active layer and a support layer. The active layer comprises platinum black plus hydrophobic binder, typically a fluorinated polymer. The support layer may be made up from carbon black bound with a halopolymer binding agent. Such combination can provide for economical utilization of active ingredient without sacrifice of cathode structural integrity. To assist in this structural integrity, a thin support mesh may be used, preferably with the support layer. There can also be employed between the active layer and the support layer a porous bonding layer, which can find broader utilization with layered gas diffusion electrodes in general. For highly desirable, greatly extended operation of the platinum black air cathode, the cathode can be operated intermittently, or anodically polarized or be subjected to infrequent voltage suppression, as well as being involved with any combination of the foregoing.

Platinum black air cathode, method of operating same, and layered gas

A gas diffusion electrode is now prepared which offers extended, efficient operation. For this, the electrode matrix may include a hydrophobic layer containing hydrophobic polymer. The electrode has hydrophilic ingredient of particulate carbon bound by hydrophilic, halogenated polymer binder. The particulate carbon used is a catalyzed carbon. The resulting efficient electrode is capable of extended operation. Moreover, on the one hand carbon catalysis can now be done in economical, straightforward manner, while on the other hand the electrode can have a surface overlay of a dimensionally stable, thin non-cellulosic paper. Such paper may be pressed against the underlying component material by a foraminous overlay, e.g., a metal mesh.

Gas diffusion electrode

A battery assembly of the consumable metal anode type has now been constructed for ready assembly as well as disassembly. In a non-conductive and at least substantially inert cell body, space is provided for receiving an open-structured, non-consumable anode cage. The cage has an open top for facilitating insertion of an anode. A modular cathode is used, comprising a peripheral current conductor frame clamped about a grid reinforced air cathode in sheet form. The air cathode may be double gridded. The cathode frame can be sealed, during assembly, with electrolyte-resistant-sealant as well as with adhesive. The resulting cathode module can be assembled outside the cell body and readily inserted therein, or can later be easily removed therefrom.

Method of making a unitized electrode assembly

A unitized electrode-intercell connector module is prepared for use in a bipolar electrode, especially for use in such electrode of the M-alkaline electrolyte-AgO types. In such special electrode, an imperforate foil, contacted with a conductive foam, is plated to a unitized, electrobonded assembly. Pyrolysis can lighten the assembly and may further provide for subsequent resistance to attack in an electrode environment. For the special electrode the reticulate portion of the assembly can be filled to provide an AgO electrode and the bipolar electrode completed by using a suitable electronegative metal on the foil side opposite from the AgO electrode.

Unitized electrode-intercell connector module

Disclosed are gas fed, porous electrodes capable of steady, high current density operation for practical periods of service, e.g. as oxygen cathodes in metal-air batteries. The subject electrodes feature at least two bonded composite layers, one of which is a form-stable, conductive wetproofing layer while the other is an unusually thin active layer containing active carbon particles predominantly between about 2 and about 20 micrometers and having a high internal surface area, e.g. a B.E.T. surface area of over 1000 m.sup.2 /gram. A simple and highly successful method of preparing such electrodes is also disclosed, which avoids the necessity of separately forming and handling the thin active layer.

Fast response, high rate, gas diffusion electrode and method of making

The disclosure is directed to preparing three-layer laminated electrodes suitable for use as oxygen (air) cathodes in chlor-alkali and other electrochemical cells, fuel cells and in other electrochemical applications. This three-layer laminate includes an active layer or sheet containing from about 60 to about 85 wt. % active carbon, the remainder being unsintered, fibrillated polytetrafluoroethylene in intimate admixture with said active carbon, said active layer laminated on its working surface to a current distributor and on its opposite surface to a porous, coherent, hydrophobic polytetrafluoroethylene-containing wetproofing layer.

Three layer laminate

The disclosure is directed to preparing three-layer laminated 'matrix' electrodes suitable for use as oxygen (air) cathodes in chlor-alkali and other electrochemical cells, fuel cells and in other electrochemical applications. The term 'matrix' as used herein means that the active carbon particles are present within an unsintered network of carbon black-PTFE (fibrillated) material. This three-layer laminated electrode includes a porous, coherent, hydrophobic polytetrafluoroethylene (PTFE)-containing backing (wet proofing) layer, with or without carbon black therein, in contact with the non-working surface of a 'matrix' active layer containing catalyzed or uncatalyzed active carbon particles present within an unsintered network of fibrilliated carbon black-PTFE and an electroconductive current distributor laminated to the working surface of said active layer, and to a process for making said laminate.

Three layer laminated matrix electrode

This disclosure is directed to the preparation of a self-sustaining hydrophobic backing layer which also possesses excellent electrical conductivity so that it can serve as an intermediate layer between the current distributor and the active layer of a complete oxygen cathode. Said backing layer is formed by a simple process in which an intimate liquid dispersion containing finely divided carbon black and not more than equal parts by weight of PTFE particles ranging in size from about 0.05 to about 0.5 microns is dewatered and shaped into a thin layer which is thereafter lightly pressed and consolidated at elevated temperatures. Preferably, the carbon black is an acetylene black of a particle size range between 50 and 3000 Angstroms and the weight proportion of same is greater than the PTFE.

Method of preparing an electrode backing layer

The active layer of an electrode is laminated on its working surface to a current distributor and on its opposite surface to a porous coherent, hydrophobic, wetproofing layer. The active layer contains from about 60 to about 85 wt. % active carbon particles bound in a matrix of a fibrillated mixture of a fluorocarbon polymer and carbon black. The electrode is useful in chlor-alkali cells.

This disclosure is directed to a non-bleeding gas electrode for operation under the rigors of high current density and to the active layer thereof. This active layer is comprised of 60 to 90 weight percent high surface area, electroconductive carbon (with or without catalyst thereon), 10 to 40 weight percent particulate polytetrafluoroethylene (PTFE) and has pores sufficiently large to relieve internal hydrodynamic pressures thus preventing liquid being forced through the electrode wetproofing layer to the air side thereof. In addition such electrodes include a PTFE-containing wetproofing or backing layer secured on one side to said active layer and on the other side to a current distributor. The pores in both the active layer and the backing layer are controlled to relieve hydrodynamic pressures by coordinating the particle size of the pore former used to establish the pores in both said layers such that the repellancy of the backing layer to hot alkali exceeds the internal liquid pressures in the active layer. Of particular significance is the fact that the present electrode is non-bleeding when operated on air and preserves its low voltage at high current density over extended time periods without bleeding.

Non-bleeding electrode

This disclosure is directed to preparing deashed, precious metal catalyst-containing, partially fluorinated active carbon particles of the formula CF.sub.x, where x ranges from 0.l to about 0.18, preferably using either platinum or silver as the catalyzing material, which can be incorporated into an active layer component of a gas electrode, e.g., an oxygen (air) cathode suitable for use in a chlor-alkali electrolytic cell for producing chlorine and caustic while conserving electrical energy. These particles are deashed to have a B.E.T. surface area of at least 600 m.sup.2 /g and contain less than about 4 weight percent ash. Active electrode layers containing such particles demonstrate an unusually desirable combination of resistance to corrosion, retention of conductive properties and retention of catalytic surface area.

Process for preparing electrodes using precious metal-catalyst

This disclosure is directed to strengthening carbon-black particulate 'Teflon' (PTFE) mixes destined to be formed into active layers in air cathodes, which comprises mixing an aqueous dispersion of particulate polytetrafluoroethylene with an aqueous suspension of particulate carbon-black; washing and drying; mixing with a pore-forming agent; fibrillating said mixtures; washing and drying; adding polytetrafluoroethylene fibers while chopping said dried fibrillated mixture and thereafter forming said chopped mixture into a sheet, which was washed and dried.

Strengthening of carbon black-teflon-containing electrode

This disclosure is directed to the preparation of cohesive, self-sustaining electrode backing layers by a method comprising mixing from about 20 to about 50 weight parts of polytetrafluoroethylene (PTFE) having a particle size ranging from 0.05 to 0.5 micron with from about 50 to about 80 weight parts of a partially fluorinated carbon black of the formula CF.sub.x, where x is from about 0.1 to about 0.18 and having particles of a size ranging from about 50 to about 3000 angstroms to produce an electrode backing layer having a combination of enhanced electrical conductivity and hydrophobicity.

Electrode backing layer and method of preparing

This disclosure is directed to a process for extracting PTFE-wetting agent from PTFE particles containing small amounts of wetting agent in admixture with carbon particles comprising contacting said mixture with an organic liquid medium capable of extracting said wetting agent, and electrodes containing such extracted mixes. Also disclosed is a process for forming an electrode layer by depositing a soluble salt on a filter medium, depositing electrode layer material on said salt consolidating said electrode material and thereafter dissolving said salt.

Growing community of inventors

Great Neck, NY, United States of America

Frank Solomon