Metal working – Battery-grid making
Reexamination Certificate
2000-06-08
2001-10-09
Kalafut, Stephen (Department: 1745)
Metal working
Battery-grid making
C429S211000
Reexamination Certificate
active
06298530
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to coiled electrode assemblies having conductive tabs, methods of attaching the conductive tabs to the coiled electrode, and electrochemical cells employing such assemblies.
Electrochemical cells employing coiled electrode assemblies are widely known in the art. In many of these cell structures the coiled electrode assembly is inserted into a composite housing which serves as the current conductive terminals for the cell. When this type of cell is assembled, a conductive tab must first be secured to the electrodes by an appropriate means such as welding.
Cells employing coiled electrode assemblies can be produced using various electrochemical systems such as nickel metal hydride, nickel cadmium, nickel zinc and the like. When using nickel metal hydride cells, the negative electrode of nickel metal hydride cells is typically a hydrogen storage electrode in the form of a metal hydride. The positive electrode is typically nickel hydroxide. These cells also contain a separator and electrolyte, as is known in the art.
The positive electrode strip is generally the outermost wound electrode for nickel metal hydride cells and has a conductive tab secured to a selected area of the carrier at one end and to the cell housing at the opposite end. Prior to securing the conductive tab to the electrode, a selected area of the conductive carrier must be cleared of any active electrode material. Conventionally, this removal is by processes such as air blasting, scraping, suction, ultrasonic clearing and the like. However, use of these methods is carrier (substrate) dependent both for efficiency of removal of active material from the substrate and strength of the resulting weld connection of the conductive tab to the substrate.
With the development of conductive carriers made of felt, foam and other fragile substrates, the task of removing active material from the substrate and attaching a conductive tab has become more difficult. Various methods have been used to break or loosen the active material from the substrate, such as ultrasonic removal of active material from the desired area, removal of active material from the substrate along an entire edge of the electrode, attaching conductive tabs in the shape of a “t” or “v” or “h” in order to strengthen the tab area, and others.
Although removal of active material from the entire length of the electrode contributes to manufacturing efficiency of these type cells, the trend today is to maximize capacity by reacting as much of the active material present in the electrochemical cell as possible. The need still exists for methods of manufacturing coiled electrode assemblies which substantially remove only a small section of active material from fragile substrates without weakening or damaging the substrates, and which allow for attachment of a conductive tab to the thus cleared substrates.
SUMMARY OF THE INVENTION
The invention relates to electrode plates used in coiled electrode assemblies having a conductive tab attached thereon. By treating the conductive tab area of an electrode plate coated with active material in the manner described herein, subsequent steps of ultrasonic clearing removes substantially all of the active material present in that area. Significantly, the cleared area is reinforced with a reinforcing material. Ultrasonic welding of a conductive tab to the thus treated area results in an electrode plate having a strong integrated tab assembly.
The first step of the invention is a piercing step, where opposing, offset piercing plates are pressed against the electrode plate in the conductive tab area. The piercing plates have raised surface probes which penetrate the active material and form a pattern of pinholes in the treated area. The next step of clearing the treated area results in a conductive tab area substantially free of active material. After the clearing step, the area is reinforced with a reinforcing material by folding and compressing the material on the cleared area. Various types of conductive tabs may then be attached to the cleared area, resulting in a strong integrated tab assembly.
It has also been found that electrodes prepared by the process of the present invention are easier to assemble as coiled assemblies for use in electrochemical cells, due to a relatively flat tab area. In addition, the process allows for incorporation of more active material in the finished electrochemical cell, resulting in higher capacity. The reinforcement can strengthen the weld and can lead to longer product lifetimes.
REFERENCES:
patent: 4049882 (1977-09-01), Beatty
patent: 4329281 (1982-05-01), Schneider et al.
patent: 4963445 (1990-10-01), Marple et al.
patent: 5154993 (1992-10-01), Beatty
patent: 5314544 (1994-05-01), Oweis
patent: 5329681 (1994-07-01), Sauer
patent: 5657522 (1997-08-01), Figueira et al.
patent: 5667915 (1997-09-01), Loustau et al.
patent: 5773164 (1998-06-01), Venkatesan et al.
patent: 2200068A (1988-07-01), None
patent: 53-25839 (1978-03-01), None
patent: 62-202457 (1987-09-01), None
patent: 63-40252 (1988-02-01), None
patent: 5-13064 (1993-01-01), None
patent: 5-205735 (1993-08-01), None
patent: 09-017425 (1997-01-01), None
Crompton, TR, Battery Reference Book, 2ndEdition;(Reed Educational and Professional Publishing, Ltd., Boston 1996), Chapter 19, p. 10 (No Month available).
Linden, “Handbook of Batteries”, p. 28.6/Fig. 28.5, 1995 (McGraw-Hill, Inc., NY) (No Month Available).
Barber Donald
Ingram Bruce
Pavlinsky Robert
Smith Robert
Duracell Inc.
Fish & Richardson P.C.
Kalafut Stephen
Tsang Susy
LandOfFree
Reinforced coiled electrode assemblies and methods of... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Reinforced coiled electrode assemblies and methods of..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Reinforced coiled electrode assemblies and methods of... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2616477