Chemistry: electrical current producing apparatus – product – and – Current producing cell – elements – subcombinations and... – Electrode
Reexamination Certificate
1997-09-03
2001-05-15
Maples, John S. (Department: 1745)
Chemistry: electrical current producing apparatus, product, and
Current producing cell, elements, subcombinations and...
Electrode
C429S211000, C429S235000, C429S241000, C429S245000
Reexamination Certificate
active
06232017
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a lead acid battery, and more particularly to a grid constituting electrodes of the lead acid battery.
2. Description of the Related Art
Because of, e.g., excellent stability in charging and discharging, lead acid batteries have been long used from the first commercialization, and a large number of the lead acid batteries are used. As compared with other system of storage batteries, however, the lead acid batteries have two main disadvantages that the energy density per weight is low and hence the weight of the battery itself has to be large. For this reason, although demand for lead acid batteries has increased as one type of portable power supplies in the recent trend toward cordless devices, there is a desire for lead acid batteries having more lighter weight, higher power and longer life than other battery systems. Conventional sealed lead acid batteries generally have the energy density per weight of about 34-35 WH/kg. However, a kind of lead acid battery having higher energy density of about 40-45 WH/kg is required for applications to an electric vehicle (EV), portable power supplies, etc.
In general lead acid batteries, an electrode plate is formed by coating lead oxide as a positive active material or lead as a negative active material on a grid made of lead or a lead alloy. The positive and negative electrode plates thus formed are positioned to face each other through a separator formed of glass fibers as a primary component, thereby fabricating a group of electrodes. The lead acid battery is then constructed by placing the group of electrodes in a container made of synthetic resin that is highly resistant against acid and shocks, and pouring dilute sulfuric acid as an electrolyte in the container.
Conventional grids for lead acid batteries have been manufactured by the casting method, the expanding method, the pressing method, etc. In any of these methods, other materials than lead or lead alloys have not been used as grid materials.
Of parts making up a lead acid battery, the part which can most effectively contribute to reducing the total weight of the lead acid battery without reducing the functions specific to that part is a grid. The grid of the lead acid battery is required to have three types of functions; (1) electrifying functions in charging and electricity collecting functions in discharging as electric conductors of the active materials in the processes of charging and discharging, (2) supporting functions of the grid itself and the active material, and (3) function of resisting corrosion ascribed to oxidizing and deoxidizing reactions occurred within the battery.
However, it has been very difficult for materials and structure of the grid to satisfactorily achieve the above functions of resisting vigorous oxidizing and deoxidizing reactions occurred within the battery, of enduring expansion and contraction of the electrode plates, and so on.
SUMMARY OF THE INVENTION
With the view of solving the above-stated problems in the related art, an object of the present invention is to provide a grid for a lead acid battery which can reduce the total weight of the lead acid battery without deteriorating its own functions.
To achieve the above object, according to the present invention, an electrode grid for a lead acid battery comprises a reticulate part made of an organic or inorganic compound, and an electricity collecting (or leading) part made of lead or a lead alloy and provided on the reticulate part, the electricity collecting part being formed on a mesh sheet. A reduction in weight can be achieved particularly in the negative electrode. This is because the negative electrode employs lead as active material and lead has electric conductivity in itself. Accordingly, the thickness of an electrically conductive part or thin film can be minimized. Also, because a negative electrode plate is less subject to corrosive reactions than a positive electrode, the electricity collecting part can be greatly cut down in comparison with conventional ones.
While a grid material may be in the form of a two- or three-dimensional reticulate sheet made of an organic or inorganic compound, a two-dimensional reticulate sheet formed of glass fibers is used in an embodiment described below. Electric conductivity can be given to the grid by forming a thin film of a lead alloy on the surface of the glass fiber sheet by vapour coating, fusion melt coating, or any other suitable process.
Thus, by employing a lead alloy in a minimum amount necessary to provide satisfactory electric conductivity and utilizing a light-weight material other than the lead alloy to provide a satisfactory ability of supporting the grid as a rigid structure, it is possible to reduce the total weight of the lead acid battery and increase the energy density per weight while maintaining the ability of the grid used as an electrode plate.
REFERENCES:
patent: 1214210 (1917-01-01), Mills
patent: 1228250 (1917-05-01), Skinner
patent: 2754348 (1956-07-01), Berchielli
patent: 2834825 (1958-05-01), Wenzelberger
patent: 3556855 (1971-01-01), Howells
patent: 3738871 (1973-06-01), Scholle
patent: 3923545 (1975-12-01), Margulies et al.
patent: 4160309 (1979-07-01), Scholle
patent: 4464446 (1984-08-01), Berger et al.
patent: 4476206 (1984-10-01), Viala et al.
patent: 4487792 (1984-12-01), Hartmann
patent: 5139902 (1992-08-01), Drews et al.
patent: 5667915 (1997-09-01), Loustau et al.
patent: 0076626 (1983-04-01), None
patent: 2352407 (1977-12-01), None
Patent Abstracts of Japan vol. 005, No. 086 (E-060), Jun. 5, 1981 and JP 56 032678 A (Shin Kobe Electric Mach Co. Ltd), Apr. 2, 1981.
Viala, et al. “Negative Composite Grids For Lead-Acid Accumulators”, Journal of Applied Electrochemistry, May 1985, UK, vol. 15, NR. 3, pp. 421-429, ISSN 0021-891X XP002080502.
Viala, et al. “Mechanical Properties And Corrosion Behavior Of Lead-Silicon Carbide Fiber And Lead-Carbide Fiber Composites Made By Electrodeposition”, Materials Chemistry and Physics, Nov. 1985, vol. 13, No. 5, pp. 393-408, XP002080501.
Patent Abstracts of Japan vol. 005, No. 015 (E-043), Jan. 29, 1981 and JP 55 144662 A (Shin Kobe Electric Mach Co. Ltd.), Nov. 11, 1980.
European Search Report dated Nov. 4, 1998.
Imai Hiroshi
Tsuchida Kensaku
Maples John S.
Matsushita Electric - Industrial Co., Ltd.
Stevens Davis Miller & Mosher LLP
LandOfFree
Grid for lead acid battery does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Grid for lead acid battery, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Grid for lead acid battery will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2556662