JPS63257181A - Manufacture of positive plate for cylinder type lithium battery - Google Patents

Abstract

PURPOSE:To obtain an excellent positive plate in absorbing ability of electrolytic solution and good workability in assembling work by a method wherein a plate is dried and pressed by passing between rollers and then it shall be bent more than once at the radius of curvature of 5% to 10% of the radius of the press roller. CONSTITUTION:A paste containing an active material for a positive plate is applied on a surface or on both surfaces of a metallic collector in a filmy state to form the positive plate 3 and after it is dried it is pressed with rollers and then the positive plate 3 is bent at the radius of curvature of 5% to 10% of the radius of the press roller at least more than once in order to lower the positive plate density by 0.3 to 5% in comparison with the positive plate density right after the roller pressing. Thereby the strain inside the positive plate 3 which occurs when the plate is pressed with rollers is decreased and even though the quantity of the paste is increased to improve the discharge capacity of a battery the deformation of the positive plate 3 which occurs after the roller pressing can be decreased. It becomes possible to increase the hole porosity on the surface of the positive plate 3. By this arrangement a positive plate 3 which does not deform much, with which a generating group can be easily constituted and an electrolytic solution can be well maintained can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for manufacturing a positive electrode plate for a cylindrical lithium battery.

Conventional technology In general, the positive electrode of a cylindrical lithium battery is made by adding a conductive agent such as acetylene black to a positive electrode active material mainly made of manganese dioxide or carbon fluoride, and then kneading the mixture with balunder and water. It is formed by adhering the interfering material (hereinafter referred to as paste) to one or both sides of the electric grid. The paste (hereinafter referred to as a positive electrode plate) attached to the metal current collection net is then dried and then pressed by a roller. In order to increase the discharge capacity of the battery, increasing the amount of paste and applying pressure increases the amount of positive electrode active material filled, but the following problems have occurred.

Problems to be Solved by the Invention (1) When the roller presses the positive electrode plate, the positive electrode plate is strained, and the positive electrode plate 3 is deformed as shown in FIG. The battery consists of a positive electrode made of this adhesive film, a negative electrode made of lithium, and a separator, which are wound in a spiral shape to form a power generation group, which is then inserted into a bottomed cylindrical metal can and filled with electrolyte. , and then sealed and manufactured. If the positive electrode plate was deformed, it would be difficult to configure a power generation group, and short circuits within the battery could occur.

偻) The porosity inside the positive electrode plate decreases, and the electrolyte retention capacity of the positive electrode plate decreases. Therefore, after the electrolyte is injected, it takes time for the power generation group to absorb the electrolyte, resulting in a large time loss in battery assembly.

In addition, the battery may be sealed while the power generation group does not absorb enough electrolyte, and in that case, the electrolyte leaks to the outside of the battery and the amount of electrolyte in the battery becomes insufficient, resulting in the battery's discharge capacity. There was a problem that the

The present invention solves the above-mentioned problems, and when manufacturing a positive electrode plate for a cylindrical lithium battery, there is little deformation of the positive electrode plate, so the power generation group configuration is easy, and the electrolyte absorption property is excellent. The purpose is to obtain a positive electrode plate.

Means for Solving the Problems The present invention involves depositing a paste containing a positive electrode active material in the form of a film on one or both sides of a metal current collector net to form a positive electrode plate, and then passing the positive electrode plate through a roller after drying. After that, the positive electrode plate is bent at least once to a diameter of 6 to 10% of the pressure roller diameter, so that the positive electrode plate density is 0.3 compared to the positive electrode plate density immediately after being pressed by the roller. ~6% reduction.

Function: According to the manufacturing method of the present invention, the positive electrode plate is bent after being pressed by the roller, so that the internal strain of the positive electrode plate that occurs when the roller is pressed is reduced, and the amount of paste is increased to increase the battery discharge capacity. However, deformation of the positive electrode plate that occurs after roller pressure can be reduced.

Further, according to the present invention, the porosity of the positive electrode plate, which has been increased in density and reduced in porosity after roller pressure is applied, is increased by curving the positive electrode plate after roller pressure is applied, particularly on the surface of the positive electrode plate. It is possible to do so. Therefore, according to the present invention, it is possible to obtain a positive electrode plate that is less deformed, is easy to configure as a power generation group, and has a good electrolyte retaining effect.

Embodiment FIG. 1A is a diagram showing the application of a paste containing a positive electrode active material to a metal current collector net, and the pressing of a dried positive electrode plate 3 with a pressure roller and the curvature after the pressing. In the figure, 1 indicates a pressure roller, and 2 indicates a positive electrode plate curved roller. In this example, the positive electrode plate was bent after being pressed by a roller using six rollers each having a diameter that was 10% of the diameter of the pressure roller.

If it is possible to curve the plate to a constant curvature, there is no need to use a roller to curve it as in this embodiment. For example, as shown in the opening in FIG. You can let it pass. Also, if the diameter of the curvature is 40% or more compared to the diameter of the pressure roller, there will be no density reduction due to the curvature of the positive electrode plate, but it will also be impossible to sufficiently remove the strain inside the positive electrode plate. Therefore, it was difficult to reduce the deformation of the positive electrode plate due to roller pressure. In addition, if the diameter of the curve is small, the paste attached to the metal current collection net may fall off, and the diameter of the curve after the positive electrode plate is pressed by the roller is 5% compared to the diameter of the pressure roller. ~40% is appropriate. The density of the positive electrode plate obtained in this way decreases by 0.3 to 6% due to the curvature compared to immediately after roller pressure is applied, but this decrease in density mainly occurs at the outer periphery of the curvature, that is, the positive electrode plate It is clear from microscopic observation that the density is clearly visible on the surface area of the positive electrode plate, and it is thought that this decrease in density centered on the positive electrode plate surface area contributes to the improvement of the positive electrode plate liquid absorption property.

Table 1 shows examples in which the present invention was implemented in positive electrode plates for cylindrical lithium manganese dioxide batteries.

In addition, the electrolyte liquid absorption time in the table is width 20 rras,
A positive electrode plate was cut into a size of 200W in length + 0.4ran in thickness, and 1.0y of electrolyte was dropped into the center of the positive plate using a dropper.The time required for the electrolyte to penetrate into the positive plate was It's time.

Further, in this example, the positive electrode plate was bent six times by six rollers, but the above-mentioned effects can be obtained even if the positive electrode plate is bent once. However, the most effective implementation effect of the present invention was obtained in the curves shown in Figures 2 to 5.

In addition, when the curve was performed six times or more, the positive electrode active material sometimes fell off from the metal current collection net.

The present invention is a cylindrical manganese dioxide lithium battery CR2/3
Conducted at A (diameter 17 mm, height 33.6 mm),
Table 2 shows the comparison results between Battery I manufactured by the manufacturing method of the present invention and Battery ■ manufactured by the conventional manufacturing method. The number of assembled batteries was n = 30. The number of discharge cycles in the table is to discharge at a current of 9oomA for 3 seconds, then pause for 27 seconds, then pulse discharge for 1 cycle of 30 seconds at a temperature of 20℃, and maintain the battery voltage at 1.55V. Indicates the number of discharge cycles between.

In addition, the positive electrode plate density in this example was 2.95 to 3.0 g/cc immediately after roller roller pressure, and 2.95 to 3.0 g/cc after one-way pressure.
．． It was 9-2.95y/CC. Further, when the positive electrode plate was immersed in the electrolytic solution for 20 seconds, the amount of electrolyte absorbed by the positive electrode plate was 1.2 cc for the positive electrode plate according to the present invention, whereas it was 09 cc for the conventional positive electrode plate.

Effects of the Invention As is clear from the above, according to the manufacturing method of the present invention, it is possible to easily assemble a battery and obtain a positive electrode plate with excellent electrolyte absorption ability, thereby improving battery performance. Can be done.

[Brief explanation of the drawing]

Figure 1A2 is a process diagram showing the positive electrode plate manufacturing method of the present invention, and Figure 2 is an external view of the positive electrode plate according to the conventional manufacturing method. 1... Pressure roller, 2... Curved roller, 3... Positive electrode plate, 4... Curved plate.

Claims (1)

[Claims] A paste consisting of a positive electrode active material, a conductive agent, and a binder is adhered in a film form to a metal current collection net to form an electrode plate, and then the electrode plate is dried and then passed through a roller and pressurized. is bent at least once to a diameter of 5% to 10% of the pressure roller diameter to reduce the paste density of the electrode plate by 0.3 to 5% compared to the paste density immediately after roller pressure. A manufacturing method for the characteristic cylindrical lithium battery positive electrode plate.