This application is a continuation-in-part of U.S. application Ser. No. 13/649,602 filed on Oct. 11, 2012, which is a continuation-in-part of U.S. application Ser. No. 12/608,201 filed on Oct. 29, 2009 currently pending, which is a continuation-in-part of U.S. application Ser. No. 11/249,223 filed on Oct. 13, 2005 and abandoned, which in turn is a continuation of U.S. application Ser. No. 10/756,015 filed on Jan. 13, 2004 and abandoned. In addition, this application is a continuation-in-part of U.S. patent application Ser. No. 11/167,535 filed on Jun. 27, 2005, now U.S. Pat. No. 7,947,391, which is a continuation-in-part of U.S. patent application Ser. No. 10/756,015 filed on Jan. 13, 2004 and abandoned.
FIELD OF THE INVENTION
- Top of Page
The present invention relates to a novel type of storage battery which is distinguished by its unique electrochemistry. The positive electrode comprises, in the charged state, lead dioxide and the negative electrode highly pure zinc. The electrolyte consists of an aqueous solution of an alkali metal bisulfate salt. Various buffering agents, including borates, silicates, and phosphates, may be added to the electrolyte. Upon discharge the lead dioxide is reduced to a divalent lead compound and zinc is oxidized to zinc oxide, and the electrolyte is converted to an alkali metal hydroxide.
- Top of Page
OF THE INVENTION
The most common storage battery, found in almost every vehicle, is the lead-acid battery. This battery comprises a lead dioxide positive electrode, a lead metal negative electrode, and sulfuric acid for the electrolyte. Its chief advantage is low cost. Nevertheless, it has limited energy density and the electrolyte is extremely corrosive. Furthermore, sufficient acid is required to react with the electrodes during discharge. Maintenance-free types avoid the loss of evolved gases, as disclosed in U.S. Pat. No. 3,862,861, but their cycle-life is still restricted.
The search for alternatives to the lead-acid battery has been ongoing. As far back as 1934, Drumm disclosed the nickel oxide-zinc battery and the silver oxide-zinc battery. (U.S. Pat. No. 1,955,115) Both of these batteries employ zinc as the negative electrode and caustic potash as the electrolyte. Nickel oxide or silver oxide serves as the positive electrode. These batteries have improved energy densities and for many uses are a good compromise.
The ideal storage battery would combine the best features of existing batteries with none of the drawbacks. The need for such a battery is apparent for backup power systems and in mobile applications. Therefore, it is an object of the present invention to provide an improved storage battery, one that is both economical and highly efficient. These and other objects, features, and advantages of the invention will be recognized from the following description and the accompanying figure.
- Top of Page
OF THE DISCLOSURE
A storage battery is fabricated from a positive electrode of lead and a negative electrode of highly pure zinc. During charging, some lead is converted to lead dioxide. Upon discharge, lead dioxide is reduced to a divalent lead compound, more particularly, lead sulfate. Zinc is oxidized to zinc oxide. These reactions are reversible such that the battery fulfills both functions of a secondary battery: supplying electricity on demand and storing or accumulating surplus electricity.
The electrolyte of the cell is an aqueous solution of a salt selected from the group of alkali metal bisulfates. The alkali metals include lithium, sodium, potassium, rubidium, and cesium. Any combination of these metals may be used. Upon discharge, the electrolyte is converted to an alkali metal hydroxide.
Certain additives have been found to be effective buffers in the electrolyte. These additives include borates, silicates, and phosphates.
The electrodes of a practical embodiment of the invention may be configured as sheets, fibers, or particles, thereby to maximize the electrode surface area. Interspersed particles of a carbonaceous material may be used to improve the electrical conductivity. A gelling agent may be added to immobilize the electrolyte. As required, a separator may be employed between the positive and negative electrodes to prevent a short circuit.
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 is a rendering of a prototype of a lead-zinc battery according to the present invention, illustrating the principal components of the cell.
The chemistry of the lead-zinc battery is important in order to gain an understanding of its operation. A positive electrode comprises lead dioxide, which is reduced to divalent lead sulfate during discharge. The negative electrode comprises zinc, which is oxidized to zinc oxide when the cell is discharged. The electrolyte is an aqueous solution of an alkali metal bisulfate. In the special case where the alkali metal is sodium, the electrode reactions during discharge can be represented by the following equations.