JPS5968176A - Nonaqueous electrolyte battery - Google Patents

Abstract

PURPOSE:To increase discharge performance and decrease defective ratio in a nonaqueous electrolyte battery by using a positive electrode which camber ratio is specified to a range of 1.2X10<-2>-3.6X10<-2>. CONSTITUTION:A negative can 1 and a positive can 7 consist of a 0.25mm. thick stainless steel having nickel plated its outer surface. A negative electrode 3 is constructed in such a way that a punched lithium sheet is press-bonded to a negative current collector 2 which is comprising a stainless steel net and spot- welded to the negative can 1. A separator 4 consists of a nonwoven fabric mainly comprising polypropylene. 8 shows a gasket mainly comprising polypropylene. A positive mix 5 is press-bonded to a positive current collector 6 comprising a stainless steel net to form a positive pellet. The positive pellet is obtained by specifying primary molding pressure and press-bonding pressure, and its camber is specified to a range of 0-0.9mm. (a camber ratio of 0-5.5X10<-2>).

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides L4. Nαe MI! The present invention relates to a non-aqueous electrolyte battery that uses all light metals such as metals as negative electrode active materials and metal oxides, metal sulfides, metal halides, etc. as positive electrode active materials.

An object of the present invention is to provide a non-aqueous electrolyte battery with good discharge characteristics while preventing the occurrence of defects due to warping of the positive electrode during battery manufacture.

In small batteries such as coin-type and button-type batteries, the positive electrode usually contains an active material such as a metal oxide, metal halide, or metal sulfide, and a conductive agent such as graphite or acetylene black.
A pellet is used that is made by pressure-molding a positive electrode mixture to which an organic binder made of a water-soluble polymer such as fluororesin or 0M0XTVA is added. In addition, expanded metal or Metal mesh bodies such as metal nets (hereinafter also referred to as positive electrode current collectors)
is pressure-molded together with the positive electrode mixture.

Conventionally, such integral molding of a metal mesh body and a positive electrode mixture has been carried out by filling a metal mold with positive electrode mixture powder, placing the metal mesh body on the second mold, and applying a force U. pressure molding or
After preforming the positive electrode mixture powder, a fully curved network f is placed on top of it.
f, and then pressure molded with a pressure greater than the pressure applied during preforming.

In this case, when the molded pellet is taken out from the mold,
Since the elongation of the pellet in the radial direction due to the spring bank phenomenon is not stopped on the metal net-like body side, a curve F) as shown in FIG. 1 occurs.

If a positive electrode with such large warpage is used and the entire battery is manufactured,
Due to the pressure of the battery sealing date, the positive electrode may crack or chip, or the chipped part or the dark edge of the positive electrode may shift from its designated position and become stuck between the positive electrode can and the gasket. Problems like this occur frequently, and as a result, the total thickness of the battery exceeds the standard, and battery performance such as leakage resistance, deterioration over time, and discharge characteristics deteriorates. In order to improve this point, only the positive electrode mixture was pressure-molded (-blow-molded) in advance, and then the molded body and the metal net-like body were integrated using a mold having a diameter larger than that of the blow-molding mold. A method of shaping was previously proposed by wood inventors.

That is, according to this method, after the next molding, the molded body is transferred to a mold for integral molding with a larger diameter, so that in this process, the molded body stretches in the radial direction due to the spring bank phenomenon described above. Springback after subsequent integral molding with the metal mesh body is reduced, and therefore, warpage of the positive electrode is reduced.

In this case, the magnitude of the warp depends on the mixture composition, the subsequent molding pressure, the integral molding pressure, etc., but in particular, the smaller the integral molding pressure, the smaller the warp.

In this way, it is possible to reduce the warpage, but after that, there is an optimal condition between the size of the warpage and the battery performance, and the warpage ratio (the warpage per unit length of pellet diameter,
(Anti-F))/C pellet diameter]] is 1.2xlO-”
It has been found that good battery performance can be obtained by using pellets in the range of ~3.6 x 10-''. That is, when the warpage is smaller than this range, the close layer force between the positive electrode mixture and the metal network increases. Although it is presumed that this is due to the weakness, the discharge performance of the battery, especially the heavy load characteristics at the end of discharge, is poor, and conversely, if the warpage is greater than this range, the incidence of the above-mentioned assembly failure will be extremely high.

The warpage rate can be controlled within this range by adjusting the subsequent molding pressure and the integral molding pressure. Although the molding pressure differs depending on the positive electrode mixture composition, the subsequent molding pressure is 1 to 8 tons.
/cm", the integral molding pressure is 1 to 4 t/, ;, 1?, and the conformal molding pressure is about -2゜5t/cm", the integral molding pressure is 1゜5t/cm. .

Note that, as shown in FIG. 1, the warpage is the difference between the step between the central part and the peripheral part of the positive electrode pellet and the pellet thickness α.

Hereinafter, the present invention will be explained in more detail based on Examples.

Example 1 FIG. 2 shows a cross-sectional view of the battery manufactured in this example. The negative electrode can No. 1 and the positive electrode can No. 7 are both made of BUs material with nickel plating on the outside, and have a thickness of 0.25 m+n. Reference numeral 3 denotes a negative electrode, which is punched out of a sheet of metal lithium and is placed on a negative electrode current collector 2 made of a 5UEI net that is spot-welded to the negative electrode can 1. 4 is a separator made of a nonwoven fabric mainly made of polypropylene; 8
is a gasket mainly made of polypropyne. The electrolyte was prepared by mixing lithium perchlorate Li0tO4 ((
A solution of 1 mol/ml was used.

5 is the positive electrode mixture, 5US11! It is press-molded integrally with a positive electrode current collector 6 consisting of a net of 1, to form a positive electrode pellet. The manufacturing method for the positive electrode is to heat electrolytic manganese dioxide to 400°C.
βM made by heat treatment for 2 hours? A positive electrode mixture consisting of 85% by weight of LO, 10% by weight of graphite, and 5% by weight of an organic binder mainly composed of tetrafluoroethylene resin was mixed in a mold 1 with an inner diameter of 16.2m++ at a rate of 1 to 8t/. After primary forming with a pressure of
Transfer to m+n mold ■, and place wire diameter 80μm, jf4 on it.
Place a SUS net with a mesh size of 50 to 1 to 4 tons.
The positive electrode pellets were integrally molded under a pressure of 1/rm''.Finally, the positive electrode pellets were dried at 100 to 300°C in the air, under reduced pressure, or in an inert gas atmosphere. can be controlled by the pressure applied during blow molding and integral molding.

The warpage was 0~0°9mm (warpage rate 0~
Using a positive electrode pellet in the range of 5°5X10”-”),
A battery with a diameter of 20 columns φ and a total thickness of 1°6 was made, and the results of the examination of the warpage rate of the positive electrode before battery assembly and the battery characteristics'f were determined in the third section.
It is shown in Fig. and Fig. 4. The amounts of active materials in the positive and negative electrodes were adjusted so that their theoretical capacities were 92 mAH and 84 mAH, respectively.

Figure 3 shows the closed circuit voltage E for a 500Ω load at -10°C after 264 hours of discharge with an external load of 15Ω.
Figure 4 shows the relationship between the incidence of defects where C (voltage after 5 seconds) is 2°4■ or less and the warpage rate of the positive electrode. It shows the defective rate due to deviations in the specifications of the total battery thickness caused by this.

As is clear from the figure, when the reversal ratio is less than 1.2xlO-" and more than 3.6xlO-", the decrease in the closing &8 voltage is significant and the defective rate increases.
-'' to 3.8xlO-'' or more, it can be seen that the defective rate of the total battery thickness increases significantly. On the other hand, the warpage rate is 1.2'X1
When using a positive electrode pellet controlled to be in the range of 0"-" to 3.6X10-", it is possible to obtain a good battery with a high closed circuit voltage, a low defect rate, and very few defects in the total battery thickness. It turns out that n.

Example 2゜Correct) As a mixture a, the same mixture as in Example 1 was added to the positive electrode mixture of Example 1, which was further dissolved in water, kneaded, dried and pulverized. Primary molding and integral molding were performed to create positive electrode pellets. Even when a battery similar to Example 1 was made except for using these pellets, almost the same results as in Example 1 were obtained regarding the battery characteristics and the relationship between defective rate and warpage rate. .

In addition, the amount of C114C is as follows when drying and removing moisture:
It was adjusted to 2% by weight in the mixture.

As described above in detail with examples, the present invention provides a positive electrode for non-aqueous electrolyte batteries by using a cathode with a warpage rate of 1.2xlO-'' to 3.6xlO''. This significantly improves discharge performance and the rate of defects during assembly.

In the examples, the positive electrode mixture and the metal mesh were integrally molded by transferring the blown pellets to the mold ■, placing the metal mesh on top of it, but Needless to say, it is also good to place the body under the primary molded pellet and mold it in one piece.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing the state of warpage of the positive electrode;
The figure is a cross-sectional view of a battery used in an example of the present invention. FIG. 3 is a graph showing the relationship between the positive electrode warpage rate and the failure rate of the closed circuit voltage of the battery, and FIG. 4 is a graph showing the relationship between the warpage rate and the battery total thickness failure rate. 1. Negative can 2゜. Negative electrode current collector 3. . Negative electrode 4. Separator 5. . Positive electrode mixture 6. Positive electrode current collector 70. Positive electrode can 8. Applicant for gaskets and above Daini Saya Kosha Co., Ltd. Agent -7'F Rishish Mogami Affairs Figure 1, Figure 2, Figure 3, Figure 4 Seifan'misaki (Melo-2)

Claims (3)

[Claims] (1) In a non-aqueous electrolyte battery in which a light metal is used as the negative electrode active material and a beret formed by integrally pressure-forming a metal network and a positive electrode mixture is used as the positive electrode, the positive electrode pellet is used as the positive electrode pellet. Pellet diameter) is 1.2X10-! ~
A non-aqueous electrolyte battery characterized by using a non-aqueous electrolyte battery having a size in the range of 3°6 x 10-''. (2) The non-aqueous electrolyte battery according to claim (1), wherein the metal network is a 5vsH net. (3) The negative electrode active material is lithium, and the positive electrode active material is manganese dioxide.
) The non-aqueous electrolyte battery described in item 2.