Chemistry: electrical current producing apparatus – product – and – Current producing cell – elements – subcombinations and... – Electrode
Reexamination Certificate
1998-01-12
2001-06-26
Kalafut, Stephen J. (Department: 1745)
Chemistry: electrical current producing apparatus, product, and
Current producing cell, elements, subcombinations and...
Electrode
C429S237000, C429S241000, C429S245000
Reexamination Certificate
active
06251540
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention is directed to electrodes of electrochemical devices which incorporate a woven or non-woven glass or ceramic fiber mesh or net with a metallic coating thereon.
2. Description of the Prior Art
Electrochemical devices such as electric batteries of the solid state type consist of at least an anode, a layer of electrolyte, and a cathode. The batteries require a base current collector and carrier for both the anode and the cathode. Various materials have been proposed for use as the base current collector and carrier, but none of them are entirely satisfactory.
Metallized plastic fiber nets do not possess optimal stiffness to resist shrinkage after coating by active materials, which can lead to curling and require additional calendering.
In addition glass or ceramic fiber nets of the same dimension, can be made lighter than nets formed from plastic fibers.
In the U.S. Patents to Hope et al., U.S. Pat. Nos. 4,794,059; 4,861,690; and 4,960,655 carbon fiber and graphite material in the form of a solid ribbon, or a woven or non-woven mesh are described which are used as base current collectors and carriers. While graphite and carbon in solid ribbon or mesh form are satisfactory for their intended purpose, the carbon fiber non-woven fabric is usually of 4 mils thickness, is heavier than polyethylene and other plastics, and also costs more than is optimal. Since the base current collector and carrier often account for as much as 50% (percent) of total battery weight, a reduction in the weight is desirable and will also increase the energy density of the battery.
In Japanese Patent No. 58-61566 (a) a production method for a lead storage battery is described where a lattice structure of synthetic resin with a cross-section of circular shape is immersed in melted lead so as to form a thin lead film on the surface of the lattice structure. The disclosed resin material is polyproproplene, this structure is restricted to lead batteries, and would not be suitable for use in other electrochemical devices as described by applicant.
In Japanese patent No. JA-7303501-R an electrode grid for lead accumulators is described which comprises a plastic film with holes, that has been coated by vacuum and electroplating of lead on the plastic film. This structure is only useful with lead batteries, and not suitable for other electrochemical devices as described by applicant.
In Japanese Patent NO. 55-39180 (A) a method of production for the electrode base of a cell is described. A porous member such as felt or unwoven cloth of polypropylene, or polyethylene is immersed in a binder solution that contains conductive powder such an nickel, iron, or carbon powder. The porous member is dried and non-electrolyte and electronic galvanization with nickel are non-electrolyte and electronic galvanization with nickel are performed to obtain a nickel layer on the member. This does not suggest the structure as described by applicant. The whole Japanese patent structure including powder is metallized after coating, while applicant only metallizes the fibers, which are of a different material than the Japanese patent.
In the German patent No. DT 2721560 expanded metal grids used as lead accumulator plates are described. The grids are made from a strip of stiff lead-antimony alloy or plastic resistant to H
2
SO
4
, which is coated on one or both sides with a rolled sheet or strip of lead-antimony, which is then made into expanded metal in the conventional manner. This structure is not suitable for use in other than lead acid batteries, and does not suggest applicant's structure which is used in other than lead acid batteries.
In the U.S. Patent to Drews et al., U.S. Pat. No. 5,139,902, an electrode is described which comprises a grid plate, which serves as the carrier for battery active material and for current supply and return. The grid plate includes woven plastic threads which are rendered electrically conductive by coating with a conductive layer of metal, and additionally metallized by coating with at least one coating of a lead-tin alloy or lead alone. The grid plate is further divided into two dimensional zones for storage of the active material, and current conducting zones for current supply and return. This plate which is described as having a thickness of 4 mils to ⅛ inch is useful only for lead acid batteries, and does not suggest the structure described by applicant.
In the U.S. Patent to King et al., U.S. Pat. No. 4,129,692 an electrode structure for an electrochemical cell in lead acid batteries is described, which is a fibrous support of organic polymeric material of a thickness of 0.1 to 3 mm, which has a pattern of solid conductors thereon, which extend over the surface of the porous support from current take-off regions to spaced regions, with electrochemically active material deposited on the fibrous material, which has had metal deposited thereon or wires to provide the electrical conductors. This structure is much thicker than applicants'. In addition, the King et al. structure is intended for use with lead acid batteries, and would not be suitable for the structures described by applicant.
SUMMARY OF THE INVENTION
It has now been found that a composite electrode for electrochemical devices, which uses a current collector having metallized glass fibers or ceramic fibers which are woven or non-woven, provides a structure of lighter weight than similar structure with metalized plastic fibers, possesses the required current collecting capability, which is stiff, resistant to shrinkage, has a long operating life, increases energy density, reduces the weight considerably, is economical, is suitable for mass production and provides numerous other benefits.
The principal object of the invention is to provide composite electrodes for electrochemical devices which have metallized glass or ceramic fiber current collectors, are strong, lightweight, inexpensive, resistant to shrinkage, and which fiber current collectors are not reactive with the components of the electrochemical devices.
A further object of the invention is to provide composite electrodes of the character aforesaid that are suitable for mass production.
A further object of the invention is to provide composite electrodes of the character aforesaid that are simple and inexpensive to construct.
A further object of the invention is to provide composite electrodes of the character aforesaid that are useful with a wide variety of electrochemical devices.
A further object of the invention is to provide composite electrodes of the character aforesaid which help to improve the energy density of the electrochemical devices into which they are incorporated.
A further object of the invention is to provide composite electrodes of the character aforesaid which have current collectors which are of lighter weight than plastic net current collectors.
Other objects and advantageous features of the invention will be apparent from the description and claims.
REFERENCES:
patent: 5045170 (1991-09-01), Bullock et al.
patent: 5232797 (1993-08-01), Moulton et al.
patent: 5294319 (1994-03-01), Kaczur et al.
patent: 5348817 (1994-09-01), Rao et al.
patent: 5766789 (1998-06-01), James et al.
Kalafut Stephen J.
Lithium Technology Corporation
Seidel Gonda, Lavorgna & Monaco, P.C.
Wills M.
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