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US-20260128279-A1 - BATTERY PASTE ADHESION PROCESS FOR BATTERIES

US20260128279A1US 20260128279 A1US20260128279 A1US 20260128279A1US-20260128279-A1

Abstract

A method of making substrates, such as grids, for assembly with lead-acid batteries is set forth herein. The grids can take the form of a strip of a multitude of serially-connected metal grids. The grids can ultimately be employed as positive electrodes or negative electrodes in a larger lead-acid battery assembly. Surfaces of the grids can be contacted with an aqueous solution, such as submergence in a bath thereof, as an example. The aqueous solution can comprise hydrogen peroxide.

Inventors

  • Roel Mendoza
  • Márcio Rocha

Assignees

  • WIRTZ MANUFACTURING COMPANY, INC.

Dates

Publication Date
20260507
Application Date
20231003

Claims (11)

  1. 1 . A method of forming a group of plates for cells of a lead-acid battery, the method comprising: forming a lead or a lead-based alloy sheet layer of interconnected, but separable, grids for the positive electrodes or the negative electrodes of lead-acid batteries, the sheet layer being formed using a casting process, or the combination of a casting process and a subsequent step of machine shaping of a cast sheet, the forming steps utilizing a carbon-containing lubricant such that a residue of the lubricant remains on surfaces of the sheet layer of interconnected grids; contacting the surfaces of the sheet layer with an aqueous solution consisting essentially of hydrogen peroxide in water so as to remove the lubricant residue from the surfaces of the sheet layer of interconnected grids and to oxidize the lead or lead-based alloy grids, the oxidized surfaces of the grids being characterized by the presence of at least one of lead hydroxide and a lead oxide; drying the surfaces of the sheet using atmospheric air; and applying a paste of precursors of active electrode material to the oxidized grid surface.
  2. 2 . A method as stated in claim 1 in which the carbon-containing lubricant used in the forming of the grid comprised at least one of a paraffin hydrocarbon, an unsaturated fatty acid, and a fluorinated hydrocarbon.
  3. 3 . A method as stated in claim 1 in which the surfaces of the sheet layer are contacted with an aqueous solution consisting essentially of hydrogen peroxide and the concentration of the solution of hydrogen peroxide in water is in the range of five to sixty five percent by volume and the grid surfaces are exposed to the solution at a temperature in the range from about 25° C. to a temperature no greater than about 70° C.
  4. 4 . A method as stated in claim 1 in which the oxidized sheet, following its treatment with aqueous hydrogen peroxide solution, is dried in a stream of flowing air.
  5. 5 . A method as stated in claim 1 in which the paste applied to the oxidized and dried sheet comprises lead oxide particles, lead particles, sulfuric acid, and water and the applied paste is steamed and reacted with the oxidized surface of the grid.
  6. 6 . A method as stated in claim 5 in which the paste applied to the oxidized and dried sheet further comprises a polymer and an expander.
  7. 7 . A method as stated in claim 1 in which the surfaces of the sheet layer are oxidized by passing the sheet through a bath of an aqueous solution of hydrogen peroxide.
  8. 8 . A method as stated in claim 1 in which the surfaces of the sheet layer are oxidized by immersing a roll of the sheet layer in an agitated bath of an aqueous solution of hydrogen peroxide.
  9. 9 . A method as stated in claim 1 in which the initial sheet layer of interconnected grids is formed as a wound spool.
  10. 10 . A method as stated in claim 1 in which the initial sheet layer of interconnected grids is formed as a wound spool containing at least 30,000 interconnected grids.
  11. 11 . A method of making substrates for use in batteries, the method comprising: providing an elongate strip of substrates, at least a portion of said substrates composed of a lead or lead-alloy material; and contacting said substrates with an aqueous solution of hydrogen peroxide.

Description

CROSS-REFERENCE TO RELATED APPLICATION This application claims the benefit of U.S. Provisional Ser. No. 63/412,589, with a filing date of Oct. 3, 2022, the contents of which are hereby incorporated by reference in their entirety. TECHNICAL FIELD This disclosure relates to batteries, and more particularly to cast and formed grids and substrates of battery plates and to the treatment of the surfaces thereof to improve adhesion of a subsequently applied battery paste. BACKGROUND Lead-acid batteries are assembled with a predetermined number of interposed positive and negative battery plates, each composed of a lead-based alloy grid and an electrochemically-active leaded paste applied to the surfaces of the grid. The grid serves as the current conductor or current collector for the electrode and the applied paste serves as the active electrochemical material of the electrode. Lead-acid battery grids are formed with a frame (typically square or rectangular) enclosing integral transversely extending wires or wire segments to define a reticulated grid having open spaces between the wire segments. The grids are usually flat, quite thin (e.g., a few millimeters in thickness), and sized in accordance with an amount of a paste of active electrode material required for the specified electrical capacity of the electrode of the battery. The grids are usually coated on both sides with the paste so that the wire segments are embedded in and surrounded by the paste, and the paste fills the open spaces between the wire segments. The grids support the paste of active electrode material. The wire segments of the battery grids may be of varying cross-section and are sufficiently spaced apart so that the open spaces between the wire segments comprise a majority of the superficial surface area of the sides of the grids. Lead-acid battery grids have been made by different manufacturing methods which often include the continuous casting of a sheet of the selected lead-based grid alloy. In one method, sheets may be cast between dies such that several interconnected (but readily separable) grid members are formed in substantially their finished shape. In a second method, flat sheets are cast of predetermined length and width and the sheets are cut, punched, and/or worked to form the crisscrossing wire segments. And in another process, the cast lead alloy sheet may be formed with suitable slits and subsequently drawn or stretched to form the frames and transverse wire segments. In a fully charged lead-acid battery, the applied and cured active material paste of the negative plate (the anode during cell discharge) consists largely of lead particles (Pb), sulfuric acid, and water, and the active material paste of the positive plate (the cathode) consists largely of lead dioxide particles (PbO2), sulfuric acid, and water. As cells of the battery are discharged, electrons are produced at the negative electrode plate which flow through the negative grid into an external electrical circuit, and the lead particles in the negative electrode paste are oxidized to lead sulfate (PbSO4). As the flow of electrons through the circuit enter the positive electrode plate, the lead dioxide particles are electrochemically reduced to lead sulfate (PbSO4). The reverse electrochemical reactions occur when the cells are recharged. As stated, in some instances, a suitable electrochemical connection should be obtained between the surfaces of the respective grid members and their coatings of a paste of active material. SUMMARY During the casting and subsequent forming and processing of lead alloy grids for lead-acid batteries, the surfaces of the casting and machining equipment are often coated with one or more of different lubrication or coolant materials composed of organic compounds. The purpose of the lubricating materials is to prevent or minimize adherence of the lead-based alloy grid material to the casting molds or to shape processing equipment. Sometimes, the lead alloy material is hot and tends to interact physically and chemically with the processing lubricant. Frequently the lubricants are composed of paraffin hydrocarbons derived from mineral oils or of unsaturated fatty acid compounds derived from vegetable oils. Frequently, these lubricant compositions are dispersed as colloids in other organic liquids and used as emulsions. Also, protective films of polytetrafluoroethylene materials (like Teflon®) may be used on the surface of the casting mold. Such materials (and other potential contaminants) adhere well to the surfaces of the lead-based grid materials, but when they are not substantially completely removed from the surfaces of the formed grid structures, it has been found, they can prevent good surface-to-surface contact with a subsequently applied, leaded paste in the formation of the plates for the lead-acid battery cells. In accordance with an embodiment, surfaces of lead or lead-based alloy strips or of formed interconnected battery grids