JPH01231261A - Manufacture of battery - Google Patents

Abstract

PURPOSE:To improve a retainable and cycle characteristic by sealing a vessel main body and a cover body by laser welding. CONSTITUTION:The cover body 2 to which a terminal 8 and an insulator 7 are attached is laser-welded 10 to a vessel main body 1, and the first sealing for closing the upper end opening part of the body 1 is conducted. Then an electrolyte E is injected into a battery vessel through the through hole 8a of the terminal 8, a sealing rod 11 is inserted into the hole 8a after the condition is left intactly for a given time, and the second sealing for closing the hole 8a by laser welding 12 is carried out. This causes the airtightness of the parts 10 and 12 to be retained for a long time, and the generation of a gap to be restricted even the conductive polymer of a positive electrode 3 is expanded and contracted by charging or discharging. Consequently the air intrusion into a battery is excluded, the deterioration of a negative electrode 4 by the outside impurities of lithium or a lithium alloy is prevented, and conservativeness and a cycle characteristic is improved with a liquid spill, etc., prevented.

Description

[Detailed Description of the Invention] The present invention relates to a method for manufacturing a battery using a conductive polymer for the positive electrode and lithium or a lithium alloy for the negative electrode, and more specifically, it relates to a method for manufacturing a battery using a conductive polymer for the positive electrode and lithium or a lithium alloy for the negative electrode. The present invention relates to a method for producing a polymer battery having good storage and cycle characteristics.

A variety of polymer batteries have been proposed in the past that use conductive raw polymers such as polyaniline as electrode active materials. Conductive polymer, lithium or lithium alloy for negative electrode,
Some secondary batteries using non-aqueous solvents containing lithium ions as electrolytes are in practical use.

When manufacturing such a battery, the positive and negative electrodes and electrolyte are contained in a battery container consisting of a metal container body and a plastic lid, and the container and the lid are sealed.
It is meant to be sealed, but what about attaching the lid to the container body and sealing it?

Traditionally, caulking using a press is often used.

However, the conventional press crimping process is a sealing method in which the end of the metal container body is pushed into the plastic lid, and there is a problem in terms of long-term sealability. In particular, in the electrode configuration described above in which a conductive polymer is used for the positive electrode and lithium or a lithium alloy is used for the negative electrode,
Even if this is housed in a battery container, the lid is attached to the container body using press caulking, and the lid is sealed, the conductive polymer used for pressure has the property of expanding during charging and contracting during discharging. Therefore, due to the expansion and contraction of the conductive polymer of the positive electrode that occurs when the battery is used, the caulked portion becomes loose, the sealing state is broken, and external air enters the battery container.

On the other hand, the lithium or lithium alloy used in the negative electrode has the property of becoming inactivated or generating hydrogen gas when it comes into contact with impurities in the air, so the air that has entered through the caulking part may not interact with the lithium or lithium alloy of the negative electrode. This causes problems such as reaction and deterioration of battery performance. In particular, when aiming for a battery with a large discharge capacity, the effects of expansion and contraction of the positive electrode, reaction of the negative electrode with external air, etc. become greater.

There is a problem in that it is difficult to obtain polymer batteries with excellent storage and cycle characteristics.

The present invention was made in view of the above circumstances, and uses lithium or a lithium alloy for the negative electrode, a conductive polymer for the positive electrode, and a nonaqueous solvent containing lithium ion as the electrolyte, and houses these components in a battery container. An object of the present invention is to provide a method for manufacturing a polymer battery having excellent storage characteristics and cycle characteristics by improving long-term sealing performance in a battery whose container body and lid are sealed.

In order to achieve the above object, the present invention uses an electrolyte consisting of a conductive polymer for the positive electrode, lithium or a lithium alloy for the negative electrode, and a non-aqueous solvent containing lithium ions. A battery manufacturing method in which these battery elements are housed in a battery container consisting of a container body and a lid, and the container body and the lid are sealed, wherein the sealing treatment is performed by laser welding. It is.

In the battery obtained by the present invention, the lid is airtightly attached to cover the opening of the container body, and the lid is firmly fixed to the container body, so the airtightness of the sealing part is maintained for a long period of time. Therefore, even if the conductive polymer of the positive electrode expands and contracts due to charging and discharging, there is no inconvenience such as the formation of a gap in the sealing portion. Therefore, since air intrusion into the battery is reliably blocked, the lithium or lithium alloy of the negative electrode is prevented from deteriorating due to external impurities, electrode deterioration is less likely to occur, and liquid leakage from the inside is also prevented. Therefore, storage characteristics and cycle characteristics are fully exhibited.

The present invention will be explained in more detail below.

As described above, the battery according to the present invention uses a conductive polymer for the positive electrode, lithium or a lithium alloy for the negative electrode, and a nonaqueous solvent containing lithium ions for the electrolyte.

Here, examples of the conductive polymer used for the positive electrode include organic conductive polymers such as polyaniline, polyacetylene, polyP-phenylene, polybenzene, polypyridine, polythiophene, polyfuran, polypyrrole, polyanthracene, polynaphthalene, and derivatives thereof. Among these, polyaniline or its derivatives are preferably used.

Note that there is no particular restriction on the form of the positive electrode substrate, and it can be used in various forms such as fiber, cloth, nonwoven fabric, film, and plate.

Further, the battery of the present invention uses lithium or a lithium alloy as the negative electrode, but in this case, 1. there is no particular restriction on the type of lithium alloy; for example, lithium and aluminum, magnesium, indium, mercury, zinc, cadmium, An alloy of one or more of lead, bismuth, tin, antimony, etc. can be suitably used. Among these, it is particularly preferable to use an alloy of aluminum and lithium in terms of negative electrode characteristics and formability.

Note that when a lithium alloy is used, lithium alloying of the metal to be alloyed with lithium can be performed within the battery container.

Further, as the electrolyte, a liquid electrolyte or a solid electrolyte is used. The liquid electrolyte consists of a nonaqueous liquid solvent containing lithium ions, and in this case, the lithium ions are supplied as a compound consisting of lithium ions and anions. Examples of this anion are PF, -, 5bFG-
, AsFl, 5bCI21. Halide anions of group VA elements such as -, B F4-, AU (m) halide anions of group A elements such as J4-, I- (I, -),
Halogen anions such as Br-, CQ-, perchlorate anions such as CQOl-, HF2-, CFJS○, -,5
CN-, 5OS-.

HS○, -, etc. can be mentioned. Specifically, lithium ions are LiPF, , Li5bF, ,■-iA s
F 6 HLiCQO4, LiI, LiBr, LiC
Q.LiBF.

LiAQ(j), 4. LiHF2. Li5CN,
Li5O, CF.

Among these, LiCQ○4゜LiB can be supplied as LiCQ
F,,LiPF6. Li5O, CF3, etc. are preferably used. On the other hand, as the non-aqueous solvent, a solvent with a relatively large () ratio is preferably used. Specifically, propylene carbonate, ethylene carbonate, benzonitrile, tetrahydrofuran, 2-methyltetrahydrofuran, and γ-butyrolactone.

Dioxolane, methylene chloride, 1-heliethyl phosphate, triethyl phosphite, dimethyl sulfate, dimethylformamide, dimethylacetamide, dimethyl sulfoxide, dioxane, 1-xyethane, polyethylene glycol, sulfolane, dichloroethane,
One type or a mixture of two or more types of organic solvents such as globenzene and nitrobenzene can be mentioned.

In addition, solid electrolytes that can be used in the battery of the present invention include:
Organic solid electrolytes, such as Li, N, LiBC (!4. Li4S
in4. Li, B.O.

Examples include inorganic solid electrolytes such as lithium glass.

When interposing an electrolyte between the positive and negative electrodes, if the electrolyte used is a solid electrolyte, there is no risk of contact between the positive and negative electrodes, and the solid electrolyte can be directly interposed between the positive and negative electrodes. When the electrolyte is a liquid electrolyte, there is a risk that the positive and negative electrodes may come into contact with each other, and it is preferable to interpose a separator between the positive and negative electrodes in order to prevent short-circuiting of current due to contact between the two electrodes. As the separator, it is possible to use porous materials that allow the electrolyte to pass through or be contained therein, such as nonwoven fabrics, woven fabrics, porous bodies, and nets made of synthetic resins such as polytetrafluoroethylene, polypropylene, and polyethylene. .

Therefore, the method for manufacturing a battery according to the present invention includes a battery comprising a container body and a lid body, with the positive and negative electrodes, electrolyte, and, if necessary, a separator as battery elements, and other battery elements used depending on the type of battery. The container is housed in a container, and the container body and lid are sealed. At this time, the sealing process is performed by irradiating the sealing portion with a laser and performing laser welding.

In this case, the shape of the battery container is not particularly limited and may be formed into various shapes such as a coin shape, a cylindrical shape, and a box shape. be effectively adopted.

In addition, the material of the container body and lid may be any metal-free material that can be laser welded. For example, nickel-plated steel can be used advantageously from a cost standpoint, but it is not strong enough. is SUS 304,316
Stainless steel such as L is preferably used.

Here, the electric container is not particularly limited, but
A WIJi body made of non-conductive synthetic resin or the like is interposed between the positive electrode part, which is normally connected to the positive electrode, and the negative electrode part, which is connected to the negative electrode, thereby insulating the two electrode parts.

As this insulator, materials commonly used as insulators for battery containers such as polypropylene can be used, but in particular polyacetal, polyetheretherketone, nylon, polytetrafluoroethylene, polyphenylene sulfide, etc. with a melting point of 170° can be used. It is preferable to use a heat resistant resin of C or higher. By using such a heat-resistant resin as an insulator, when sealing a battery container by laser welding, the battery container can be sealed by irradiating it with high-energy laser light that heats it. Also, a good sealing state can be achieved without softening of the insulator and creating gaps or poor insulation. Therefore, the sealing process can be completed in a short time using a high-energy laser beam, and the production time per battery can be shortened. In particular, when sealing a battery container where the insulating part and the part to be laser welded are close to each other due to restrictions such as battery usage, the high heat generated by laser beam irradiation is likely to be cut off and propagate to the bulb part. If a resin with a low melting point is used as an insulator, the high heat will cause the resin to soften and cause problems such as gaps, which will cause problems such as the creation of gaps.This requires the laser beam energy to be extremely low, and the sealing process will take a long time. Therefore, increasing the energy of the laser beam by using the above-mentioned thermal resin as an insulator is very effective in shortening the manufacturing time of the battery.

In addition, when housing an electrode in a battery container, the shape of the electrode can be selected from various shapes such as a laminated shape and a cylindrical shape, but a laminated shape is particularly preferable.

In the present invention, the sealing process is performed by laser welding as described above, but in this case, the laser welding can be performed under normal conditions. Although there are no particular limitations on the laser, a YAG laser is preferably used, which has a high power density, is suitable for fine processing, and can be irradiated from any angle by using an optical fiber.

Next, a preferred embodiment of the manufacturing method of the present invention will be described with reference to FIGS. 1-2.

FIG. 1 shows an example of a battery obtained by the present invention. In the figure, 1 is a box-shaped container body with an open top, and 2 is a lid that closes the top opening of the container body 1. A container body 1 accommodates an electrode having a laminated structure in which a positive electrode 3 and a negative electrode 4 are laminated with a separator 5 in between. here,
The electrode has a structure in which a positive electrode 3 is interposed within a negative electrode 4, and the negative electrode π4 is in contact with the metal container body 1. Further, the positive electrode 3 is connected via a lead wire 9 to a metal terminal 8 held within a cylindrical insulator 7 fixed to a through hole 6 formed in the center of the lid 2. It is something. Note that the insulator 7 is a hermetic seal made of glass, polypropylene,
It can be formed from synthetic resins such as polyacetal, polyetheretherketone, nylon, polytetrafluoroethylene, and polyphenylene sulfide, and in particular polyacetal and polyetheretherketone as mentioned above.

A material made of a heat-resistant resin having a melting point of 170° C. or higher, such as nylon, polytetrafluoroethylene, or polyphenylene sulfide, is preferably used.

When manufacturing such a battery, first, the electrode is housed in the container body 1, and as shown in FIG. 2A, a cylindrical metal terminal (having a through hole 8a) is used as the metal terminal 8. A first sealing process is performed to airtightly close the upper end opening of the container body 1 by laser welding 10 the lid 2 to which the terminal 8 and the insulator 7 are attached to the container body 1.

Next, as shown in FIG. 2B, the through hole 8 of the terminal 8 is opened.
Inject electrolytic solution (liquid electrolyte E) into the battery container through a, and after leaving it for a predetermined period of time, insert the enclosing rod 11 into the through hole 8a of the terminal 8 as shown in FIG. 2C, and perform laser welding 12. Therefore, a method of performing a second sealing process to airtightly close the through hole 8a is preferably adopted.

That is, the conductivity polymer used for the positive electrode in the present invention is
It is a material that easily absorbs moisture, and when it is housed in the container body, it already contains some moisture. For this reason, if the electrode is placed in the container body and then immediately sealed with a lid and completely sealed, the residual moisture in the conductive polymer of the positive electrode will react with the lithium or lithium alloy of the negative electrode to generate hydrogen gas. This causes problems such as blistering in the battery container.

In addition, to avoid this problem, after the electrode is housed, if the sealing process is stopped until the above-mentioned hydrogen generation is completed and the electrode is dry, the opening at the top of the container body is large, so when the electrolyte is injected, The electrolytic solution easily evaporates, and even if it is left in an inert gas atmosphere such as argon, it is inevitable that some impurities will enter.

Furthermore, it is dangerous to laser weld large openings once the electrolyte has been injected.

However, according to the two-stage sealing process described above, the first
After the sealing process, the presence of the opening allows hydrogen gas to escape from the battery container, and the opening for the first liquid is small, so the above-mentioned disadvantages are unlikely to occur.

Here, the size of the through hole 8a is O, 1 to 10 i
The diameter is preferably about n. Also.

The sealing process for this through hole 8a is performed by injecting an electrolytic solution,
This is carried out after the moisture in the positive electrode and battery container is left to react with the lithium in the negative electrode, and the standing time in this case is about 1 hour to 1 week.

The Qo method shown in FIG. 2 is more suitable for use as the battery container becomes larger, and the resulting battery as shown in FIG. Since the battery container is made stronger by laser sealing and is less likely to be deformed, the negative electrode and the battery container can be connected easily without using a current collecting pole or wire for negative damage, and without welding the negative electrode and the battery container. It is possible to conduct electricity for a sufficiently long time by contacting the
It is possible to simplify the labor during battery production.

In addition, in the two-step sealing process as shown in FIG. 2, instead of providing a through hole in the terminal, a through hole is provided in the lid body itself,
Finally, it is also possible to seal this through hole.
Also, other methods may be used for sealing the through holes instead of laser welding, and the two-step sealing treatment is not limited to the method described above.

DETAILED DESCRIPTION OF THE INVENTION As described above, the present invention uses a conductive polymer as a positive electrode,
When manufacturing a pond using lithium or a lithium alloy as a negative electrode and a non-aqueous solvent containing lithium ions as an electrolyte,
Since the container body and the lid are sealed by laser welding, the sealing process is performed reliably and the inside of the battery container is maintained in a sealed state for a long period of time. Therefore, impurities are prevented from entering from the outside, and there is no leakage of liquid from the inside, making it possible to obtain a battery with excellent retention and cycle characteristics.

EXAMPLES Hereinafter, the present invention will be specifically explained with reference to Examples and Comparative Examples, but the present invention is not limited to the Examples below.

[Example 1] A length of 180 nwn and a width of 30 mm were placed on both sides of an aluminum plate with a length of 180 nwn, a width of 34 cm, and a thickness of 200 mm.

A lithium-aluminum alloy made by laminating one lithium plate with a thickness of 200 mm, a length of 140 m, a width of 30 mm, and a thickness of 200 mm is used for the negative electrode, and the positive electrode is electrolyzed on stainless steel. Made of polymerized polyaniline, length 200 urns.

A polyaniline sheet with a width of 34 + nm and a thickness of 1 m was packed in a polypropylene porous membrane as a separator, and the positive and negative electrodes were rolled up so that the exposed part of the aluminum 11 was the outermost part, and this was wrapped into a 23 nm diameter ridge. height 4
It was inserted into a 3m++ bottomed cylindrical SUS container body.

On the other hand, a positive terminal part consisting of a positive terminal having a through hole and an insulator is in spot i8 contact with the through hole of the SUS lid body, and the lid body is arranged to cover the upper end opening of the container body, and the lid body is arranged to cover the upper end opening of the container body. The lid was sealed by YAG laser welding.

Next, the inside of the battery container was inspected for 1n through the through hole provided in the positive electrode terminal.
Reduce the pressure to ynHg and add 3 mol/Q of L into the vacuum container.
A 5.6 mQ solution of iBF4/propylene carbonate/dimethoxyethane 1:1 (volume ratio) electrolyte was prepared. After leaving it for 2 days and confirming that no hydrogen gas is generated, a piece of stainless steel with a diameter of 0.7 mm and a length of 10 nm is inserted into the through hole, and the through hole is laser welded to form a cylindrical shape as shown in Figure 1. A polymer secondary battery was constructed. Note that all of the above preparation operations were performed in an argon gas inert atmosphere. Further, the diameter of the through hole was 0.7 no.

When this secondary battery was vacuum dried in a 60°C oven for one week, there was no weight loss at all, and the charging current was 50mA.
When a charge/discharge test was conducted under the conditions of an upper limit voltage of 3.3 V, a discharge current of 50 mA, and a lower limit voltage of 2 V, as shown in FIG. 7, 90% of the initial value was retained even after 200 cycles.

[Comparative example]

A cylindrical polymer secondary battery was constructed in the same manner as in the example except that the battery container was sealed by caulking. Note that the electrolytic solution was injected before caulking.

Next, when this secondary battery was vacuum dried in a 60°C oven for one week, it lost about 10 square centimeters of weight. Next, a charge/discharge test similar to that in the example was conducted, and as shown in FIG. 7, the capacity decreased to 73% of the initial capacity at the 200th cycle.

[Example 2] Length shown in Fig. 4: 65 no, rl] 20 mm,
Stainless steel (S) with a thickness of 6m and a wall pressure of 0.5mwn
US304) container body 1 (opening 5X] 9nn) and the length 19 that closes the opening 13 of the container body 1 in FIG.
A battery container 14 made of stainless steel (SUS 304) and having a width of 5 ntn and a thickness of 1 mm was prepared. The lid body 2 is made of stainless steel (SUS) having a through hole 8a in a cylindrical insulator 7 (made of polytetrafluoroethylene resin with a melting point of 325°C) fixed to a through hole 6 drilled in the center of the lid body 2. A positive electrode terminal 8 made of 316L) is fixed.

Then, as shown in FIG. 6, the length is 240 IIn.

Width 18+IIn, JTI: 0. Length 230nn, Ill 15nv on one side of anwn aluminum plate 15
A lithium plate 16 of n, thickness Q, 2+m+ is IMm and l
It was pressed at a pressure of OO kg/ci and bent at five places so that the lithium plate side was on the inside to form a negative electrode 4. In addition, as a positive electrode, a polyaniline-stainless steel composite with a thickness of 1 m, prepared by electrolytically polymerizing and depositing polyaniline on a stainless steel mesh, was used as a positive electrode with a length of 120 + nm and a medium of 18 nn.
A lead wire 9 was spot welded to the center of the electrode, and the electrode was placed in a bag made of a porous polypropylene membrane as a separator (positive electrode 3).

This positive electrode 3 was folded in half and inserted into the inside of the negative electrode 4, and then housed together in the container body 1. Here, the negative electrode 4 is pressed against the inner surface of the container body 1 in a conductive state. Then,
The lead wire 9 of the positive side 3 and the positive electrode terminal 8 of the L lid 2 were spot welded, and the opening 13 of the container body 1 was closed with the lid 2. At this time, a cap 17 made of polypropylene is inserted between the electrode and the lid 2 so that the lead wire 9 and the battery container 14 do not come into contact with each other. A lead wire 9 was connected to the positive electrode terminal 8 through the inside. This lid 2 and the opening 13 of the container body 1 were welded 10 using a pulsed YAG laser to assemble a box-shaped battery 19 shown in FIG. 3. The laser welding conditions are a spot diameter of 0.5rrn and a laser output of IJ/ρ.
pulse, repetition rate 20 pulse/see
, at a movement speed of 2 an/sec.

Total output is 20W, 8 contact time between 2 openings and 2 laps is 24 seconds.
Next, the inside of the battery container was brought to L rtrn Hg M pressure through the through hole 8a provided in the positive electrode terminal 8, and the pressure was increased to 3y* into the reduced pressure container.
2.4 d of LiBF4/propylene carbonate/dimethoxyethane 1:1 (volume ratio) electrolyte of o1/Q was injected. After leaving it for 2 days and confirming that no hydrogen gas was generated, a diameter Q of 7nwn was formed in the first through hole 8a.

Insert a stainless steel piece with a length of 10 nn and open the through hole 8.
A was laser welded 12. Note that all of the above operations were performed in an argon gas inert atmosphere. Further, the diameter of the through hole 8a was 0.7 mwa.

When this secondary battery was vacuum dried in a 60° C. oven for one week, no weight loss was observed, and no thermal deformation of the insulator 7 was observed.

[Example 3] A box-shaped secondary battery was constructed in the same manner as in Example 2 except that polyetheretherketone having a melting point of 334° C. was used as the insulator 7.

When this secondary battery was vacuum-dried in a 60°C oven for one week, there was no weight loss at all, and there was no loss of weight. No thermal deformation of the element body was observed.

In addition, lI! A box-shaped battery was assembled in the same manner as in Example 2, except that polypropylene with a body melting point of 140°C was used for AR heating. The positive electrode terminal 8 fell into the battery container 14 and came into contact with the lid 2. Therefore, we investigated various laser welding conditions that would not melt the polypropylene insulator, and found that the spot diameter was Q, 5u.
wn, laser output I J /pulse, W repetition speed 5 pulse/see, movement speed 0.5wn/s
ec, total output is 5W, 8 contact time between opening and circumference is 9
The welding time was 6 seconds, which required a long welding time.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing an example of a battery obtained by the method of the present invention, FIG. 2 A-C is a perspective view sequentially illustrating one implementation step of the method of the present invention, and FIG. S3 is a battery obtained by the method of the present invention. FIG. 4 is a perspective view showing a container body constituting the battery, FIG. 5 is a lid constituting the battery, A is an enlarged plan view, and B is a perspective view showing another example of the battery. A cross-sectional view taken along line B-B in Figure A, Figure 6 is a perspective view showing the negative electrode constituting the same battery, and Figure 7 is a cycle of a battery obtained by the method of the present invention and a battery obtained by the comparative method. It is a graph showing the number and discharge capacity. 1. Container body, 2. Lid body, 3. Positive dawn, 4. Negative dawn,
5... Separator, 8... Positive electrode terminal, 8a... Through hole, 10.12... Sealing part. Applicant Brideston Co., Ltd. Agent Patent Attorney Takashi Kojima Bc Figure 3 Figure 4 Figure 6

Claims (1)

[Claims] 1. Using a conductive polymer for the positive electrode, lithium or lithium alloy for the negative electrode, and a non-aqueous solvent containing lithium ions as the electrolyte, these battery elements are housed in a battery container consisting of a container body and a lid. 1. A method of manufacturing a battery in which the lid and the lid are sealed, characterized in that the sealing treatment is performed by laser welding.