JP3015579B2 - Manufacturing method of positive electrode plate - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a positive electrode plate,
Particularly, the present invention relates to a method for producing a positive electrode plate by a roll method.

[0002]

2. Description of the Related Art Conventionally, a slurry method, a pressing method, a paste method and the like have been adopted as a method for manufacturing a positive electrode plate.

However, in the slurry method, it is difficult to apply the slurry mixture uniformly to the electrode core material.
In order to produce this slurry-like mixture, there is a drawback that many steps and time such as mixing and kneading of the mixture are required,
In the pressing method, since the mixture in a wet state is pressed by a press to form a sheet, there is a disadvantage that it is difficult to obtain a long and uniform material.

[0004] In the paste method, a positive electrode mixture in a wet state is
It is necessary to carry out a process of winding a sheet formed into a preliminary sheet through a pair of rotating rolls and drying the sheet, and when winding a sheet coming out from between the rolls into a coil, the sheet is There is a disadvantage that it is easy to cut. For this reason, it has been proposed that a roll for producing a sheet is heated and the sheet forming step and the drying step are performed simultaneously (Japanese Patent Application Laid-Open No. 04-62750).

However, in this method, as shown in FIG. 3, there is not enough time to supply the sheet 3 to the pressure rolls H and I, and the molding amount of the sheet varies depending on the kneading state of the mixture and the difference in the moisture value. When a large number of sheets are supplied to the pressure-bonding roll, the sheet may be wavy or may have uneven pressure-bonding, and conversely, the sheet or the electrode core material may be cut.
In addition, since the pressure roll is not heated, if the mixture has a high moisture value, the dried state of the sheet becomes insufficient, and the electrode core material is stretched and cut at the time of pressure bonding, or the sheet adheres to the pressure roller. It is possible.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and has a constant sheet supply amount to a pressure roll so that a long positive electrode plate can be continuously and stably formed. The purpose is to manufacture with quality.

[0007]

A pendulum-type feed roll is provided between a heating roll and a pressure roll to allow a sufficient supply of sheets to the pressure roll, so that the sheet is continuously supplied regardless of the amount of the formed sheet. Be able to keep the volume constant.

[0008]

When a sheet formed by a heating roll is supplied to a pressure roll by a pendulum-type auxiliary roll provided between the heating roll and the pressure roll, a pendulum type may be used depending on the amount of sheet supplied to the pressure roll. The auxiliary roll is outward,
By moving inward and keeping the sheet tension constant, the sheet is prevented from waving or cutting.

Further, by heating the pressure roll, the moisture content in the sheet is reduced, and the sheet is prevented from adhering to the roll, and the pressed state of the sheet is also improved.

[0010]

【Example】

[Positive electrode mixture adjusting step] 90 parts by weight of manganese dioxide powder as a positive electrode active material and graphite 6 as a conductive agent
Parts by weight and 4 parts by weight of acetylene black for imparting a liquid retaining property to the electrolyte are mixed well. To this mixture, 5 parts by weight of a dispersion of polytetrafluoroethylene (PTFE) as a binder (3 parts by weight of the solid content of TFE with respect to the mixture) and 23 parts by weight of pure water were added and kneaded. Grain (d = 1
mm) to produce a wetted positive electrode mixture.

[Forming Step of Positive Electrode Mixture] FIG. 1 shows an outline of the forming step of the positive electrode plate.

The positive electrode mixture 1 in a wet state is put into a hopper 2, and two pairs of heating rolls A heated to 100 to 130 ° C.
And B, C and D are formed into two sheets 3.

The gap between the heating rolls A and B and the gap between C and D determine the thickness of the sheet to be formed. In this embodiment, the thickness of the sheet 3 is adjusted to 0.3 mm.

The heating rolls A, B, C and D form the positive electrode mixture 1 in a wet state and heat it to lower the moisture content of the formed sheet 3. Therefore, sheet 3
Can be controlled by the temperature of the heating roll.

[Step of pressing the formed sheet to the electrode core] The gap between the pressure bonding rolls F and G is adjusted so that the thickness of the positive electrode plate 4 becomes 0.57 mm, and the electrode core 5 is pressed to the pressure bonding roll F, G
And the pressure rolls F and G heated to 120 to 130 ° C. through the pendulum feed roll E in which the arm 6 moves the sheet 3 formed by the heating rolls A and B and C and D. Guide between.

The electrode core material used here has a thickness of 0.1 mm.
Stainless steel plate with mesh (SW × LW) 1.5 mm × 3.0
This is a SUS316 lath core processed to a thickness of 0.2 mm and a thickness of 0.2 mm. Here, SW is the center-to-center dimension in the short direction of the mesh, and LW is the center-to-center dimension in the long direction.

The operation is performed with the rotational speed of the pressure rolls F and G kept constant. When the amount of sheets supplied to the pressure rolls F and G is normal, the state is as shown in FIG. When the amount of sheets supplied to the pressure rolls F and G increases, the pendulum-type feed roll moves outward as shown in (b) of FIG. 2 to prevent the sheets from being loosened. As shown in FIG. 2C, the pendulum-type feed roll moves inward to prevent the sheet from being pulled too much and the sheet from being cut. That is, the pendulum-type feed roll allows the amount of sheets supplied to the heat-pressing roll to have a margin in advance, and the pendulum-type feed roll moves outward and inward depending on the amount of sheet supplied, and The tension is constantly maintained.

The heating roll used in the present invention has a temperature of 100.degree.
Heating to 130 ° C. prevents the sheet from adhering to the roll. In addition, since tetrafluoroethylene as a binder has a property that fiberization proceeds at 90 ° C. or higher, sufficient fiberization occurs simultaneously with sheeting,
The effect of increasing the tensile strength of the sheet is also obtained.

The pressure-bonding state of the sheet to the electrode core material depends on the dry state of the sheet, and the lower the moisture content, the better. Therefore, the pressing roll is also heated to prevent the sheet from adhering to the roll, and the sheet is dried to improve the pressing state.

[0020]

According to the present invention, by providing a pendulum-type feed roll between a sheet forming heating roll and a pressing roll, a forming amount of the sheet varies depending on a kneading state of the mixture and a difference in water value. Even if the amount of sheet supplied to the roll changes, the pendulum feed roll moves inward and outward, keeping the sheet tension constant, and preventing the sheet from waving or cutting. . Further, by heating the pressure roll, the moisture content in the sheet is reduced, the sheet is prevented from adhering to the roll, and the pressed state of the sheet is improved. As described above, according to the present invention, it is possible to continuously produce a positive electrode plate with stable quality, and its industrial value is extremely large.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of an apparatus used in one embodiment of a method for manufacturing a positive electrode plate of the present invention.

FIG. 2 is a diagram showing a state of a sheet supplied to a pendulum type feed roll and a pressure roll.

FIG. 3 is a schematic sectional view of an apparatus used in a conventional method for manufacturing a positive electrode plate.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Positive electrode mixture 2 Hopper 3 Sheet 4 Positive electrode plate 5 Electrode core material 6 Arm A, B, C, D Heating roll (sheet roll) E Pendulum feed roll F, G Heat press roll H, I Crimping roll

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-4-62750 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01M 4/08

Claims (2)

(57) [Claims] 1. A positive electrode mixture in a wet state is respectively supplied between two pairs of heating rolls to form a pair of positive electrode mixture sheets, and these sheets are laminated on both surfaces of an electrode core material, respectively. In a method of supplying the sheet to a pair of pressure rolls and pressing the sheet to both sides of the electrode core material with the pressure roll,
A method for producing a positive electrode plate, comprising a pendulum feed roll provided between a heating roll and a pressure roll. 2. The method according to claim 1, wherein the pressure roll is heated.