JPS5861557A - Production method of negative electrode of nonaqueous electrolyte cell - Google Patents

Abstract

PURPOSE:To prevent the lithium from adhering to a cutting tool by tentatively pressing with the cutting tool having a specific angle then punching with the cutting tool having a specific angle when punching the lithium in a disk shape from a lithium sheet. CONSTITUTION:When the lithium used as the negative electrode of a nonaqueous electrolyte cell is punched in a disk shape from a lithium sheet Li, first a groove with a depth of half the sheet thickness is formed in a tentative press process with a pressing edge having an angle theta1 of 100 deg.-130 deg., then the groove formed in the tentative press process is cut off with a cutting edge 1 using a cutting tool composed of the cutting edge 1 with an angle theta2 of 10 deg.-20 deg., a punch 2, and a stripper 3. Accordingly, the lithium can be prevented from adhering to the cutting tool and deteriorating its sharpness, and also the strength of the cutting part is not reduced and the life of the cutting tool can be remarkably extended.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a method for manufacturing a negative electrode for a non-aqueous electrolyte battery.

Recently, lithium nonaqueous batteries have come to be used in small portable devices such as calculators and watches, and the demand for coin-type lithium batteries has doubled.

Lithium (hereinafter referred to as L1) Fi is currently supplied by two major manufacturers in Japan.
Width: 20 to 50 WIk).

Conventionally, the method of punching out the L1 sheet using a punch and die (Fig. 1), or the method of punching the L1 sheet using a cutting edge (a) as shown in Fig.
) and a punch (b), the L1 sheet was pressed off by applying a constant load, the L1 pellet was left inside the cutting edge, and the L1 sheet was cut by force.

However, in the example shown in Figure 1, the L1 sheet was torn off by the shearing force, and the L1 scraps adhered to the inner surface of the die and the outer periphery of the punch, causing galling, making continuous use difficult after several dozen times. The method shown in Figure 2 does not generate Ll scraps, but the Ll deposits accumulate on the outer surface of the cutting edge (the Vv'vV part in Figure 2), causing the blade to become fc. The result was that the cutting quality deteriorated after several 10 times.

The present invention aims to effectively cut Ll by using both a pusher blade and a cutting edge, and set the pusher blade angle to 100° to 150° and the cutting edge angle to 10° to 20°. Furthermore, the present invention aims to provide a stripper on the outer periphery of the cutting edge to support the sheet in order to prevent Ll from easily adhering to the cutting edge due to the lifting of the sheet during L1 cutting. did.

Next, the present invention will be described with reference to practical examples.

FIG. 3 shows the temporary pressing state of Ll by the pressing blade. The optimum condition for the angle θ1 of the pushing blade was found through an L1 sheet pushing experiment as shown below.

Table 1 The adhesion amount is determined by the groove depth as shown in Figure 3-1.
After pressing the sheet until it reached half the sheet thickness (1) and returning it to its original position, the process was repeated 100 times, and then the t attached to the pressing blade was measured. From Table 1, it was found that θi is optimally between 90° and 120°, and Ll adhesion occurs at both lower and higher angles. The diameter d of the tip of the helmet and push blade was 17 utai, and the thickness of the L1 tip was α3 膓.

Next, the punching process will be explained.

Figures 4 to 6 show the states before punching, during punching, and after punching, respectively, and the jig has a cutting edge (L).
, a punch (b) and a stripper (e). In Fig. 4, the cutting edge (a) descends from above the groove made by temporary pressing, and at the same time, the stripper (c) cuts the L1 sheet approximately. The zero-order cutting edge is further lowered by fixing it with a load of 500 f/d.

Then, the punch (b) presses the top surface of the L1 sheet and completely cuts off the L1 sheet. (See Fig. 5) Next, the cutting edge rises, then the stripper rises, and the L1 pellet is completely separated from the L1 sheet while remaining blue in the hole. (Fig. 6) By performing temporary pressing and punching, the cutting edge can perform continuous cutting without generating Ll punching scum.

Ll when changing the cutting edge angle θ1 in the punching process
The amount of adhesion and the number of consecutive cuts are shown in the table below.

Table 2 () shows the aggregate results of defects due to chipping of the H1 blade and cracking of the pellet.

From Table 2, there is no Li adhesion in the range of θ = 10 to 20°, and the amount of adhesion is zero at the low angle side (8° and 5°), but the blade becomes very thin. A chip occurred while cutting the hole. Further, on the high angle side, the number of L1 adhesion violets increased, and the number of cuttings was only 200 times.

As described above in detail, according to the method of the present invention, when punching out a disk shape from a lithium sheet, the temporary pressing process
After pressing with a cutting tool with an angle of 0° to 120°, 10° to
By punching with a cutting tool having an angle of 20°, it is possible to prevent Ll from adhering to the cutting tool and making it difficult to cut, and it is possible to significantly extend the life of the cutting tool, and its industrial value is extremely large.

[Brief explanation of drawings]

1 and 2 are cross-sectional views of a conventional cutting tool, FIG. 3(A) is a temporary pressing tool according to the present invention, FIG. 5(B) is an enlarged sectional view thereof, and FIGS. 4 to 6 are cross-sectional views showing the continuous punching process using cutting edges (1) Cutting edge (2) Upper punch (3) Old... L1 sheet and above Figure 1 Figure 2 Oi Figure 3 (8) Figure 4 Figure 5 Figure 6

Claims (1)

[Claims] When punching lithium into a disk shape from a lithium sheet in a battery that uses lithium as the negative electrode, propylene carbonate and 1゜2 dimethoxyethane as the electrolyte, and manganese dioxide, cupric oxide, iron sulfide, etc. as the positive electrode active material. A method for producing a negative electrode for a non-aqueous electrolyte battery, which comprises pressing with a cutting tool having an angle of 90° to 120° in a temporary pressing step, and then punching with a cutting tool having an angle of 10° to 20°.