JPH04351848A - Manufacture of negative electrode of nonaqueous electrolyte battery - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

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 negative electrode for a non-aqueous electrolyte battery, and more particularly to a method for manufacturing a negative electrode for a non-aqueous electrolyte battery using an improved pressing process.

0002

[Prior art] Previously, lithium, which has a high electronegativity,
Alkali metal elements such as magnesium and sodium are excellent materials as negative electrode active materials for batteries, and are particularly useful for button-shaped and coin-shaped lithium batteries that use lithium metal or lithium alloys (hereinafter collectively referred to as lithium). It is widely used as a power source for consumer equipment. Lithium is
When used as the negative electrode of coin-shaped or button-shaped batteries,
In a dry atmosphere with a moisture content of 5% or less, a hoop-shaped lithium sheet was punched out into a circular shape of a predetermined size and inserted into a negative electrode can for use. An example of the punching method is shown in FIG. In FIG. 3, 5 indicates an eccentric press, 1 is a lithium sheet that is unwound from a hoop shape and supplied, 6 is an upper punch for punching, and 7 is a lower die.

[0003] When punching is performed under such conditions, punching debris is generated and the yield is approximately 80 to 70%.
Unfortunately, this was one of the causes of increased battery costs. On the other hand, if the hoop-shaped lithium sheet 1 is simply cut into square lithium pieces of a predetermined amount and inserted into the negative electrode can, it will not be possible to insert a sufficient amount of lithium for the reaction because the negative electrode can has a circular shape. , the reaction surface area becomes smaller than that of the positive electrode, which is unfavorable in terms of battery characteristics. For this reason, when considering yield and battery characteristics, the best solution is to cut a hoop-shaped lithium sheet 1 into a predetermined amount of square pieces, insert and place them on the inner bottom surface of the negative electrode can, and then press them with a mold. Various attempts have been made to press-bond a square lithium piece to the inner bottom surface of a negative electrode can to form a substantially circular lithium piece.

0004

[Problem to be solved by the invention] In this case, lithium is
Its material properties are that it is sticky, flexible, and easily deformed, and when it is molded and crimped to the inner bottom surface of the negative electrode can into a predetermined shape using a mold with a flat lithium metal abutting part in a roughly circular shape, The outer periphery of the circular lithium is thinner than the inner radial part, and cracks occur in the extreme parts, causing detachment and preventing a sufficient electromotive reaction. , or caused process troubles during battery manufacturing.

[0005] The present invention has been made to solve these problems, and an object of the present invention is to provide a method for producing a negative electrode for a nonaqueous electrolyte battery that does not impede the electromotive reaction and has excellent mass productivity.

[0006]

[Means for Solving the Problems] In order to solve the above problems, the method for manufacturing a negative electrode for a non-aqueous electrolyte battery of the present invention includes, as one method, a method in which a square lithium piece is pressure-bonded to the inner bottom surface of a negative electrode can. , the first step is a step of pre-pressing with a pre-forming mold in which the lithium metal contact portion of the pre-forming mold has a blastosphere-like shape, and the second step is a pre-pressing step in which the lithium metal contact portion of the pre-form mold has a flat shape. The method includes a step of pressing the lithium into a circular lithium in the final processed shape using a mold.

Another method is to use a method in which a predetermined blastomere-shaped recess is provided in the inner bottom surface of the negative electrode can to which lithium metal is to be crimped, and the inner bottom surface of the negative electrode can is shaped into a rectangular shape using a mold so that it becomes flat. Lithium pieces are pressed using a flat mold and crimped.

[0008]

[Function] Accordingly, in the method for manufacturing a negative electrode for a non-aqueous electrolyte battery of the present invention, when a square lithium piece is pressed and developed into a substantially circular lithium in the first step, the outer peripheral edge of the square lithium piece is Since the shape of the lithium metal abutting part of the preforming mold is in the shape of a predetermined blastosphere, no strong pressing force is applied, so the wall thickness does not become extremely thin, and it can be processed into the final shape in the next process. Even if the molded body is molded, it is possible to process a molded body with a constant wall thickness without causing any cracks or cracks on the surface.

[0009] Furthermore, by forming a predetermined blastomere-shaped recess on the inner bottom surface of the negative electrode can, the blastomere-shaped recess and the lithium metal surface can fit well together, and the wall pressure at the outer peripheral edge of the lithium can be reduced. , fine cracks will not occur in the lithium.

0010

DESCRIPTION OF THE PREFERRED EMBODIMENTS Two embodiments of the present invention will be described below with reference to the drawings.

In this example, a CR2016 coin-shaped manganese dioxide/lithium battery with a diameter of 20 mm, a height of 1.6 mm, and a capacitance of 90 mAh was manufactured. This study compares and investigates the impact on

To explain the first embodiment shown in FIG.
Cut a predetermined amount of square lithium piece 1a into a square lithium piece 1a, insert it into the inner bottom surface of negative electrode can 2, and then cut the square lithium piece 1a so that the shape of the lithium metal contact part is 1.5 to 2.5 times the diameter of the final processed outer diameter. Step (a) of preforming the square lithium piece surface 3 into a substantially circular circular lithium 1b using a blastosphere-shaped preforming mold 4a having A negative electrode is constructed by the step (b) of pressurizing and bonding the circular lithium 1b into a predetermined shape into the negative electrode can 12.

[0013] The shape of the lithium metal contact portion of the preforming mold 4a is made as in this embodiment because its diameter is 1.
．． If it is smaller than 5 times, the prismatic lithium piece 1a will warp greatly when pressurized and will protrude to the side of the mold, resulting in extremely poor productivity. If it is larger than 2.5 times, the outer edge of the prismatic lithium piece 1a will warp. This is because the wall thickness of the part becomes thinner, and when it is molded to the final size (shape) in the next process, minute cracks occur, and the lithium in this part is released during the electromotive reaction or during production.

FIG. 2 shows a second embodiment (in other words, a blastosphere-shaped recess is provided on the inner bottom surface of the negative electrode can 2), in which the inner bottom surface of the negative electrode can 2 has a recess whose dimensions are that of lithium metal. When the outer diameter at the time of final processing is set to 1, a blastomere-shaped recess 2a with a diameter of 15 to 25 times is provided in advance, and a square lithium piece 1a is formed so that the shape of the lithium metal contact part is flat. The pressure bonding process is performed using a mold 4b.

[0015] The reason why the diameter of the blastomere is increased from 15 to 25 times is because if the diameter is less than 15 times, the warp of the lithium metal will become large when pressurizing the bottom of the negative electrode can to make it flat. Lithium leaked out to the top,
Maintenance such as mold cleaning is required, which reduces productivity. If it is 25 times or more, the thickness of the outer edge of lithium becomes thinner, minute cracks occur inside the lithium, and the lithium in this part separates during the electromotive reaction or during production and no longer participates in the reaction. be. (Table 1) shows a battery using a negative electrode processed by the manufacturing method using a blastosphere-shaped mold according to the first embodiment of the present invention, and a battery using a negative electrode manufactured by the manufacturing method using a blastosphere-shaped mold according to the first embodiment of the present invention, and a battery using the negative electrode manufactured by the method using the blastosphere-shaped mold according to the first embodiment of the present invention. We constructed 500 batteries each using negative electrodes processed using a manufacturing method that forms spherical recesses and batteries using negative electrodes processed using the conventional method, and calculated the utilization rate of the negative electrode when discharging with a load resistance of 50 kΩ. It shows.

[0016]

[Table 1]

As shown in Table 1, according to the methods of Examples 1 and 2, the utilization rate of the negative electrode is significantly improved compared to the conventional method.

Although the positive electrode side is not shown, the positive electrode is arranged on the inner bottom surface of the positive electrode can, and then the positive electrode,
The positive and negative electrode cans are fitted together through insulating packing arranged around the periphery so that the negative electrode cans face each other with a separator interposed therebetween, and are caulked and sealed to form a completed battery.

[0019] As the positive electrode active material, MnO2, Cu
Oxides such as O, V2O5, FeS2, CuS, NbS
Sulfides and selenides such as e3, (CF)n, CuCl2
Various halides such as PbI2 and iodides such as PbI2 can be used.

[0020]

[Effects of the Invention] As is clear from the explanation of the above embodiments, the method for manufacturing a negative electrode for a non-aqueous electrolyte battery of the present invention has a good utilization rate of the negative electrode, stable performance, and excellent mass production. It can provide lithium batteries.

[Brief explanation of drawings]

FIG. 1 is a partially cutaway perspective view schematically showing the steps of a method for manufacturing a negative electrode for a non-aqueous electrolyte battery according to a first embodiment of the present invention;

[Fig. 2] A partially cutaway perspective view of a negative electrode can used in the method for manufacturing a negative electrode of a non-aqueous electrolyte battery according to the second embodiment.

[Fig. 3] A perspective view showing an example of a lithium punching device used in a conventional method for manufacturing a negative electrode of a non-aqueous electrolyte lithium battery.

[Explanation of symbols]

1 Lithium sheet 1a Square lithium piece 1b Circular lithium 2 Negative electrode can 2a　　　Blastosphere-shaped recess 3　　　　　Square surface of prismatic lithium 4a Preforming mold 4b Molding mold

Claims (4)

[Claims] 1. A step of inserting and placing a predetermined amount of prismatic lithium pieces on the inner bottom surface of the negative electrode can, and then molding the prismatic lithium pieces into the inner bottom surface of the negative electrode can using a press molding die. A method for producing a negative electrode for a non-aqueous electrolyte battery, which comprises a pressing step of pressurizing the
A non-aqueous electrolyte battery consists of a pre-pressing process consisting of a pre-forming mold in which the shape of the lithium metal contact area is a blastosphere shape, and a main molding process consisting of a molding die in which the lithium metal contact area is flat in shape. Manufacturing method of negative electrode. 2. A step of inserting and placing a predetermined amount of prismatic lithium pieces on the inner bottom surface of the negative electrode can, and then molding the prismatic lithium pieces into approximately circular lithium pieces on the inner bottom surface of the negative electrode can using a press molding die. A method for manufacturing a negative electrode for a non-aqueous electrolyte battery comprising a pressing step of pressure-bonding, the method for manufacturing a negative electrode for a non-aqueous electrolyte battery in which a blastospherical recess is previously formed on the inner bottom surface of the negative electrode can. 3. The shape of the preforming mold is a blastomere having a diameter 1.5 to 2.5 times the outer diameter of the final processed shape of the lithium metal. A method for producing negative electrodes for water electrolyte batteries. 4. The non-aqueous electrolyte according to claim 2, wherein the recess on the inner bottom surface of the negative electrode can is a blastomere having a diameter 15 to 25 times larger than the outer diameter of the final processed shape of the lithium metal. A method for manufacturing negative electrodes for batteries.