HK1055847B - Battery of the type comprising a zinc can and a collector consisting of carbon for the cathode - Google Patents

Description

Battery of the type comprising a zinc can and a collector constituted by a carbon cathode

Technical Field

The invention relates to a battery of the type: it comprises a zinc can, the bottom of which is in contact with the negative terminal, and a collector electrode consisting of a carbon cathode, said zinc can being continuously surrounded by a layer of electrically insulating material and a protective metal shell. Batteries of this type are well known. The design of this known type of battery is schematically illustrated in fig. 1 of the drawing description and in the parts of the description of this figure. In this known cell design, the top end of the zinc can is sealed with a plastic sealing ring and in which the carbon rod is fixed in a sealing manner.

Background

Because the zinc can in this cell takes part in the current flow processes inside the cell, it becomes less robust and can corrode over time. Over time, the real hazards are: the electrolyte may begin to seep out of the cell through the zinc can which becomes unconsolidated. To prevent this from happening, in known designs a plastic shrink tube is typically fitted around the zinc outer casing, which also acts as a layer of electrically insulating material. In order to protect the cell from external damage and to enable printing thereon, a metal casing is usually fitted around the shrink tube. This metal shell usually comprises a pre-printed metal envelope which is closed by a longitudinal seam. The end of the sleeve formed in this way may then be flanged inwardly to enclose the battery structure. In this case it is also possible to seal other elements of the cell, such as metal caps in contact with the free ends of the carbon cathodes, metal caps resting on the bottom of the zinc can and insulating rings to enable the mounting of these metal caps so that they are electrically insulated from the can.

It has been found that there are drawbacks to using shrink tubing. Shrink films for this purpose are relatively expensive structural elements and it takes some time to install it and are therefore also expensive. Finally, an effective shrink tube requires a relatively thick shrink film, which takes up additional space in the cell.

Disclosure of Invention

It is an object of the present invention to alleviate said drawbacks. For this purpose, the invention consists in: the metal shell comprises on its inside an organic coating layer which serves as an electrically insulating material layer. It is thus possible to dispense with the shrink tube. The application of an organic coating on a metal sheet is a generally known technique, and for these coatings to be applied, it is possible to have various thicknesses and various properties. Various coatings using, for example, polyesters, polyolefins, etc., have been found suitable for this application of the present invention.

It should be noted that the metal can does not serve an electrical function during the current flow within the battery.

According to the invention, the metal shell may also have an organic coating on its outside, which may be printable or may even have been previously printed. Unlike the known metal shells, this involves the use of a metal sheet, for example a steel sheet, which has been coated on both sides with a coating, the inner coating of said metal shell having the function of providing electrical insulation to the zinc casing, while the outer coating thereof has the function of being printable and possibly of protecting the metal sheet itself.

The invention also relates to a novel battery wherein the metal can is comprised of a cladding having a longitudinal seam that is crimped inwardly at the ends of the battery, the resulting crimp sealing the various components of the battery to form an integral unit. It is particularly advantageous if the organic coating on the inside of the cladding comprises a thermoplastic which is located at the longitudinal seam and which has been temporarily heated to adhere the edges of the seam to each other. As a result, a gas-tight seal is formed, so that electrolyte seepage is no longer possible.

Although it is possible to first make the cladding from an uncoated metal sheet and then to apply an organic coating on one or both sides, it is preferred according to the invention to make the cladding from a metal sheet that has been applied with an organic coating.

Drawings

The invention will now be described with reference to some of the accompanying drawings.

Fig. 1 illustrates a zinc-carbon type single cell.

Fig. 2 shows a variant of the battery according to the invention.

In fig. 1, the reference numeral 1 refers to the zinc can forming the anode of a zinc-carbon battery, wherein the reference numeral 2 refers to the carbon rod as the cathode collector. Typically, the carbon rod 2 is at least partially composed of graphite. The space between the zinc can 1 and the carbon rod 2 is filled with a cathode material, i.e. a mixture of manganese dioxide, carbon powder and electrolyte. The design and filling of this space is not described in more detail here, since they are well known.

A plastic sealing ring 3 is located at the top end of the zinc can 1, wherein the ring is mounted in a clamped and sealed manner on the carbon rod 2. This sealing ring 3 is shaped so that the top edge 4 of the zinc can is bent inwards in a clamping manner, thus forming a seal. A shrink tube 5 is placed around the zinc can 1 and the sealing ring 3, the end edge of the shrink tube extending around the bottom edge of the zinc can and the top edge of the sealing ring 3. Metal caps 6 and 7 are in contact with the free end of the carbon rod 2 and the bottom of the zinc can 1, respectively. In this way, the positive and negative terminals of the battery are formed. Furthermore, the metal caps 6 and 7 are sealed by means of a steel cladding 10 surrounding the battery, which steel cladding is crimped inwards at the ends. Insulating rings 8 and 9 may also be installed between these crimped portions and the steel caps 6 and 7 to ensure that the cladding 10 cannot make electrical contact with the ends. The ends in the circumferential direction of the cladding are joined to each other along a seam. To protect the steel cladding 10 from corrosion, a layer of chromium, a layer of nickel, a layer of tin or another coating may be applied. It is also possible to provide a decorative layer on the outside.

Fig. 2 shows a variation of the known design illustrated in fig. 1, in which the new design of the present invention is used. Corresponding reference numerals indicate corresponding parts.

The most significant difference is the elimination of the shrink tube 5 and therefore of an expensive structural element, the labor-intensive operations required for the installation of this shrink tube, and the space saving in the radial direction of the cell. Now the shell 11, which comprises a layer of organic coating on the inside, which also serves as a layer of electrically insulating material, forms a protective metal shell. The shell is redesigned to have a cladding that also has a longitudinal seam. However, since the organic coating in this case consists of a thermoplastic, the longitudinal seam of the closed cell is first heated temporarily until the edges of the seam adhere to one another by means of the organic coating. This ensures a better seal to prevent electrolyte leakage. In this case, too, the ends of the cladding are connected to the inner flange, so that the ends of the metal caps 6 and 7 are closed again. Depending on the thickness and quality of the organic coating, sufficient electrical insulation between the cladding and the metal caps 6 and 7 may or may not be obtained. Additional insulating rings 12 and 13 may also be installed here if desired.

Claims (6)

1. A battery comprising a zinc can, the bottom of which is in contact with the negative terminal, and a collector electrode comprising a carbon cathode, said zinc can being continuously surrounded by a layer of electrically insulating material and a protective metal shell, characterized in that: the metal shell comprises on the inside an organic coating layer which serves as an electrically insulating material layer.

2. The cell of claim 1, characterized in that said metal casing also has an organic coating on its outside, which is printable or printed.

3. The battery of claim 1 or 2, characterized in that said metal can is comprised of a cladding having a longitudinal seam, which is crimped inwardly at the ends of said battery, the resulting crimp sealing the components of said battery to form an integral unit.

4. The cell of claim 3, characterized in that the organic coating on the inside of the envelope comprises a thermoplastic, which is located at the longitudinal seam, which is temporarily heated to bond the edges of the seam to each other.

5. The cell of claim 3, characterized in that said cladding is made of a metal sheet having an organic coating.

6. The cell of claim 4, characterized in that said cladding is made of a metal sheet having an organic coating.