JPH07296821A - Thin battery and its manufacture - Google Patents

Abstract

PURPOSE:To manufacture a thin battery inside which a short circuit is prevented during manufacture for increased yields. CONSTITUTION:A method for manufacturing a thin battery, in which an anode active material 2 is set in a fixed pattern on the surface of an anode collector 1 made from a resin film or metallic foil with a series of metallic cover layers thereon, includes a process for arranging predetermined areas of the anode active material 2 in the sections of the anode collector 1; a process for putting a pressurizing member 4 on the surface of the anode active material 2; a process for deforming the anode active material 2 and press-fitting a greater area of the material 2 than the original area to the surface of the anode collector 1 by pressurizing the top surface of the pressurizing member 4 using a roll, a heating roll or a press; and a process for removing the pressurizing member 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thin battery and a manufacturing method thereof.

[0002]

2. Description of the Related Art In recent years, electronic devices have been miniaturized with the development of the electronics field, and batteries as well as the devices have been desired to be miniaturized. In particular, a battery using lithium as the negative electrode active material can be expected to have a high energy density, and is therefore a very suitable battery for miniaturization and thinning.
In a conventional lithium thin battery production, when using a pressing member having only a flat portion equal to the area of the negative electrode active material, when the negative electrode active material is pressed from the vertical direction to the negative electrode current collector,
The negative electrode active material may adhere to the pressing member, or the peripheral portion of the negative electrode active material may swell and protrude toward the positive electrode side. When this protrusion occurs, when the negative electrode active material, the separator and the positive electrode active material are combined, the protrusion of the negative electrode active material may break through the separator and come into contact with the positive electrode mixture, resulting in an internal short circuit.

[0003]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems of the prior art, and provides a thin battery and a method of manufacturing the thin battery that prevent an internal short circuit that occurs during manufacturing of the battery and improve the yield. The purpose is to

[0004]

In order to achieve the above-mentioned object, the present invention has a larger area than the negative electrode active material before pressure deformation and has a shape formed only by a flat portion or a pressure surface of the flat portion. A pressing member having a rectangular hole having a protruding portion on its side or having a size at least about 0.5 mm smaller than the outer peripheral edge of the arranged negative electrode active material is arranged on the negative electrode active material surface, and the upper surface of the pressing member is rolled. A thin battery and a method for producing the same, which comprises pressing a negative electrode active material onto a negative electrode current collector plate by applying pressure with a roll, a heating roll or a press, wherein the peripheral portion of the negative electrode active material has a wavy shape after the pressure bonding. , Concave shape, inclined shape, or
It is a shape having a curvature, and preferably, the ratio of the thickness h of the concave portion at the peripheral portion to the thickness H of the central flat portion is such that h / H is 0.6 or more. This is to solve the above problems.

[0005]

When a pressure member having a rectangular hole of about 0.5 mm or more from the outer peripheral edge of the negative electrode active material arranged on the negative electrode current collector surface is used and the negative electrode active material is pressure-bonded to the negative electrode current collector plate, The negative electrode active material may squeeze out, and an internal short circuit easily occurs. Therefore, the area is larger than the area of the negative electrode active material before pressure deformation, and the shape is formed only by the flat portion, has a protrusion on the pressing surface side of the flat portion, or is arranged from the outer peripheral edge of the arranged negative electrode active material. A pressing member having a rectangular hole at least about 0.5 mm smaller is arranged on the surface of the negative electrode active material, and the upper surface of the pressing member is pressed by a rolling roll, a heating roll or a press to make the negative electrode active material the negative electrode current collector. By press-bonding to the plate, it becomes possible to prevent the peripheral edge portion of the negative electrode active material from bulging and protruding toward the positive electrode side. Further, by making the peripheral region of the negative electrode active material into a wavy shape, a concave shape, an inclined shape, or a shape having a curvature, swelling, protrusion, and warpage of the peripheral portion of the negative electrode active material toward the positive electrode side are further suppressed. As compared with the conventional case, the internal short circuit at the time of manufacturing the battery is eliminated, and the yield can be improved.

[0006]

EXAMPLES Details of the present invention will be described below with reference to examples, but the present invention is not limited thereto.

Example 1 A thin battery of Example 1 of the present invention was manufactured according to the following procedure. a) Manganese dioxide is used as the positive electrode active material of the battery, Ketjen Black is used as the conductive agent, and ethylene oxide diacrylate (molecular weight: 4000) and polyethylene glycol monoacrylate (molecular weight: 400) are adjusted to 7: 3. A mixture of the mixed organic compounds was used as a composite positive electrode.

The method for producing this composite positive electrode is as follows. That is, 9 parts of manganese dioxide and ketjen black
The above organic compound 1 is added to a mixture of 7: 3 by weight.
A mixture of 0 parts by weight of azobisisobutyronitrile 0.05 parts by weight, 1 part by weight of lithium perchlorate, 10 parts by weight of propylene carbonate and 5 parts by weight of 1,2-dimethoxyethane was mixed with dry inert gas. Atmosphere 10:
Mixed in a weight ratio of 3. These mixtures were cast on a current collector in which a conductive carbon film was formed on the surface of a series of positive electrode current collector plates made of stainless steel. afterwards,
It was cured by leaving it in an inert gas atmosphere at 100 ° C. for 1 hour.

B) Lithium metal is used as the negative electrode active material of the battery, and the lithium metal is arranged in a fixed pattern on the surface of the negative electrode current collector. The area of the lithium metal is larger than the area of the negative electrode active material and is about 0. A pressing member having a rectangular hole of small size of 3, 0.5, 0.8 mm was applied to the upper surface side of the lithium metal, pressed by a rolling roll, and pressure-bonded to a series of negative electrode current collector plates made of stainless steel. . At this time, the thickness h of the concave portion at the peripheral portion of the lithium metal and the thickness H of the central flat portion
Was prepared so that the ratio h / H would be 1, 0.8, 0.6, 0.4, 0.2.

Next, 30 parts by weight of the organic compound, 1 part by weight of lithium 2,6-naphthalenesulfonate, and 0.05 parts by weight of benzyl dimethyl ketal are added to form an ion-conductive polymer compound layer on the lithium metal. A mixture of 1 part by weight of lithium perchlorate, 32 parts by weight of propylene carbonate and 16 parts by weight of 1,2-dimethoxyethane was cast on the above lithium metal and cured by UV irradiation in an inert gas atmosphere.

C) The electrolyte / lithium / negative electrode current collector obtained in b) and the positive electrode current collector / composite positive electrode obtained in a) are combined and heat-sealed with a heat sealer in each compartment. After sealing, the cells were separated into individual compartments to produce individual thin batteries.

FIG. 1 is a cross-sectional view of the lithium metal of Example 1 of the present invention when it is pressure-bonded to a current collector plate. In the figure, 1 is a negative electrode current collector plate made of a series of stainless steel, which also serves as an exterior. 2 is lithium metal. 3 is a sealing material made of modified polypropylene. Reference numeral 4 is a pressure member made of resin. FIG. 2 is a cross-sectional view of a conventional case where lithium metal is pressure-bonded to a current collector plate.

Comparative Example 1 a) Manganese dioxide was used as the positive electrode active material of the battery, Ketjen black was used as the conductive agent, and the diacrylate ester of ethylene oxide (molecular weight: 4000) and the monoacrylate ester of polyethylene glycol (molecular weight) were used. : 400) was mixed with an organic compound obtained by mixing 7: 3, and used as a composite positive electrode.

The method for producing this composite positive electrode is as follows. That is, 9 parts of manganese dioxide and ketjen black
The above organic compound 1 is added to a mixture of 7: 3 by weight.
A mixture of 0 parts by weight of azobisisobutyronitrile 0.05 parts by weight, 1 part by weight of lithium perchlorate, 10 parts by weight of propylene carbonate and 5 parts by weight of 1,2-dimethoxyethane was mixed with dry inert gas. Atmosphere 10:
Mixed in a weight ratio of 3. These mixtures were cast on a current collector in which a conductive carbon film was formed on the surface of a series of positive electrode current collector plates made of stainless steel. afterwards,
It was cured by leaving it in an inert gas atmosphere at 100 ° C. for 1 hour.

B) Lithium metal is used as the negative electrode active material of the battery, the lithium metal is arranged in a fixed pattern on the negative electrode current collector surface, and a rectangular pressing member having an area equal to that of the lithium metal is applied to the upper surface side of the lithium metal. An insulator and a press were used to apply pressure to a series of negative electrode current collector plates made of stainless steel. Next, in order to form an ion conductive polymer compound layer on the lithium metal, 30 parts by weight of the organic compound, 1 part by weight of lithium 2,6-naphthalene sulfonate, 0.05 part by weight of benzyl dimethyl ketal, and perchloric acid. A mixture of 1 part by weight of lithium, 32 parts by weight of propylene carbonate and 16 parts by weight of 1,2-dimethoxyethane was cast on the above lithium metal and cured by ultraviolet irradiation in an inert gas atmosphere.

C) The electrolyte / lithium / negative electrode current collector obtained in b) and the positive electrode current collector / composite positive electrode obtained in a) are combined and heat-sealed by a heat sealer in each compartment. After sealing, the cells were separated into individual compartments to produce individual thin batteries. The electrode area of the thin batteries of Examples and Comparative Examples can be variously changed depending on the manufacturing process. In the present Example and Comparative Example, the electrode area was 1 cm ² . Table 1 shows the percentage of non-defective batteries manufactured for this thin battery.
It was shown to.

[0017]

[Table 1]

As can be seen from Table 1, Example 1 of the present invention
It can be seen that the thin battery of No. 1 has an excellent non-defective battery manufacturing rate as compared with the thin battery of Comparative Example 1. In the thin battery of Example 1, when the lithium metal was pressure-bonded to the negative electrode current collector plate, the protrusion of the lithium metal, which causes an internal short circuit, disappeared,
It is considered that the yield in the assembly process was improved.

[0019]

As is apparent from the above description, the area of the negative electrode active material before the pressure deformation is larger than that of the negative electrode active material, and the shape is formed only by the flat portion, or the flat surface has the protrusion on the pressure surface side. Alternatively, a pressing member having a rectangular hole smaller than the outer peripheral edge of the arranged negative electrode active material by at least about 0.5 mm is arranged on the surface of the negative electrode active material, and the upper surface of the pressing member is a rolling roll, a heating roll or a press. By pressurizing and pressing the negative electrode active material onto the negative electrode current collector plate, the peripheral edge of the negative electrode active material is prevented from bulging to the positive electrode side and protruding, and internal short circuit during battery fabrication is eliminated as compared with the conventional case. It is possible to improve the yield. From these things, there is an effect that the rate of non-defective batteries can be improved. It should be noted that it is conceivable that the processing is performed only by a die roll or a press, excluding the pressure member.

[Brief description of drawings]

FIG. 1 is a cross-sectional view when the lithium metal of the present invention is pressure bonded to a current collector.

FIG. 2 is a cross-sectional view of a comparative example (conventional) in which lithium metal is pressure-bonded to a current collector.

[Explanation of symbols]

 1 Negative electrode current collector 2 Lithium metal 3 Sealing material 4 Pressurizing member 5 Lithium metal protrusion

Claims (7)

[Claims] 1. The negative electrode active material has a peripheral edge portion in a wavy shape, a concave shape, an inclined shape, or a shape having a curvature, and a solid polymer electrolyte is arranged on the upper surface of the negative electrode active material in the same shape. A thin battery characterized in that. 2. The negative electrode active material is a metallic lithium foil, and the ratio h / H of the thickness h of the concave portion at the peripheral portion to the thickness H of the central flat portion is 0.6 or more. The thin battery according to claim 5. 3. The thin battery according to claim 5, wherein an outer peripheral edge of the solid polymer electrolyte is larger than an outer peripheral edge of the negative electrode active material and an outer peripheral edge of the positive electrode active material. 4. A method for manufacturing a thin battery, in which a negative electrode active material is arranged in a fixed pattern on a surface of a negative electrode current collector made of a resin film or a metal foil having a series of metal coating layers and pressure-bonded to each of the negative electrode current collectors. The step of disposing a negative electrode active material having a predetermined area in the compartment, the step of disposing a pressing member on the surface of the negative electrode active material, the upper surface of the pressing member is pressed by a rolling roll, a heating roll or a press to form a negative electrode active material. A method of manufacturing a thin battery, comprising: a step of deforming the surface of the negative electrode current collector surface so as to have a larger area than the original area; and a step of removing the pressing member. 5. The pressing member is a plate, foil or film made of a metal and / or a resin, and is larger than the area of the negative electrode active material, and its shape is formed by only a flat portion or a flat portion. 2. A protrusion is provided on the pressing surface side, and a rectangular hole that is smaller than the outer peripheral edge of the arranged negative electrode active material by at least about 0.5 mm is formed.
A method for manufacturing the thin battery described. 6. The method of manufacturing a thin battery according to claim 1, wherein the negative electrode active material is deformed to provide wavy and uneven portions in a peripheral region of the negative electrode active material. 7. A series of negative electrode current collectors to which the negative electrode active material is pressure-bonded is combined with a positive electrode current collector prepared in a separate step, sealed in each section, and then separated into each section, 2. The method for manufacturing a thin battery according to claim 1, wherein the thin battery is manufactured.