JPH027356A - Manufacture of thin type battery - Google Patents

Abstract

PURPOSE:To make it to excel in sealing performance and allow its electric-discharge property to be improved, by initially forming a recessed portion in at least one of the respective terminal plates of its positive and negative electrodes, and sealing up the opening of a battery except for its through hole before it is pregnated with electrolytic solution, then blocking the through hole with insulation sealing materials after the solution is poured therein. CONSTITUTION:Either one or both of a pair of terminal plates 1, 2 formed by setting of the sandwiching portion 9 of a battery power generation element 8 in the center part between them is constituted of a terminal plate provided with a recessed portion 3 continuing from the sandwiching portion 9 to its side edge. The battery power generation element 8 and insulation sealing materials 4 provided along the side periphery of the element are sandwiched and disposed in between these terminal plates paired so as to heat and press them together. Thus the battery power generation element is sealed with the insulation sealing materials 4 at side periphery thereof except for that of the recessed portion 3, then electrolytic solution is poured therein from the outside through a through hole interposed between this recessed portion and the insulation sealing materials, and thereafter this through hole is sealed up with insulation sealing materials 3B. There will hence be no need for initially impregnating the battery power generation element with the electrolytic solution so that it can be sealed up with good sealing performance; besides, a necessary and sufficient quantity of the electrolytic solution can be supplied to the contents of the battery so that its electric-discharge property can be improved.

Description

[Detailed description of the invention] (a) Industrial application field This invention relates to a method for manufacturing thin batteries, and in particular, it is possible to easily manufacture thin batteries with improved sealing performance, high reliability, and good discharge characteristics. It is about the method.

(B) Conventional technology Conventionally, thin batteries are batteries in which positive and negative electrodes are stacked with a separator interposed between a pair of metal terminal plates (positive and negative terminal plates) formed into a predetermined shape. The power generation element is sandwiched and stored without being impregnated with electrolyte in advance, and a frame-shaped insulating seal made of heat-fusible resin is sandwiched between the side periphery of the battery power generation element, that is, the periphery of both terminal plates, and the power generation element is sandwiched between both terminals. It was manufactured by sealing with a hot press using a plate and frame-shaped insulating sealing body.

In addition, for the purpose of improving the adhesion between the terminal board and the insulating sealing body, before the battery sealing process, an insulating sealing body is welded to at least one of the positive electrode and negative electrode terminal plates in advance. Thin batteries have also been constructed using the above procedure.

(c) Problems to be solved by the invention Regarding the sealing properties of batteries, the interface between the terminal board and the insulating sealing body,
Alternatively, the adhesion of the interface between the insulating sealing bodies is important.

In this regard, in the conventional manufacturing method described above, in the battery sealing process, the battery power generation element housed inside is impregnated with electrolyte, so it leaks to the outside of the battery due to the hot press in the battery sealing process. Electrolyte tends to adhere to the welded interface, causing poor sealing.

In addition, regarding the discharge characteristics of the battery, as mentioned above, when the battery is sealed, the electrolyte that has been impregnated in the battery power generation element leaks to the outside of the battery, so the amount of electrolyte remaining inside the battery decreases, and the battery power generation element In particular, gaps may form between the separator and each electrode, and the amount of electrolyte inside the battery power generation element may become insufficient, increasing the internal resistance of the battery.
There was a problem that the discharge characteristics deteriorated.

This invention was made under such circumstances, and in particular, provides a thin battery with excellent sealing properties and improved discharge characteristics without causing poor sealing properties due to electrolyte solution or shortage of electrolyte solution itself. The present invention aims to provide a method for manufacturing a thin battery that can be easily obtained.

(d) Means for Solving the Problems Thus, according to the present invention, in a pair of terminal plates in which the clamping part of the battery power generation element is set in the center, at least one of the terminal boards has a recessed part that continues from the clamping part to the side edge. By sandwiching the battery valve 'ri element and the insulating sealing material along its side periphery between the pair of terminal plates and hot pressing, the side periphery of the battery power generation element other than the recessed portion is is sealed with an insulating sealing material, then an electrolytic solution is injected from the outside through a through hole formed between the recess and the insulating sealing material, and then this through hole is sealed with an insulating sealing material. A method for manufacturing a thin battery is provided.

In order to solve the above-mentioned problem, the present invention provides a method for forming a through hole that penetrates into the inside of the battery when sealing the insulation of the thin battery.
A recess is formed in advance on at least one of the positive and negative terminal plates, the battery is sealed before electrolyte impregnation, leaving the through hole, and the through hole is closed with an insulating sealant after the electrolyte is injected. 6, whose biggest feature is that

In the present invention, at least one of a pair of terminal plates (a positive terminal plate and a negative terminal plate) is used in which a recessed portion is formed as described above. Such a recess can be formed, for example, by drawing, and it is not limited to a single recess, but a plurality of recesses may be provided.

As the battery power generating element in this invention, it is suitable to use one having a normal three-layer structure consisting of a positive electrode part/separator/negative electrode part or one having a porous structure. In addition, in the present invention, it is suitable to use one that is not impregnated with electrolyte.

As the insulating sealing material for sealing the side periphery of the battery power generation element in this invention, it is suitable to use a heat-fusible resin used in hot melt adhesives, etc., such as polyamide-based, polyolefin-based, etc. Various materials can be used, but polyolefin materials are preferred in terms of insulation, moisture resistance, ease of hot pressing, etc., and polyolefins modified with a small amount of organic acid component, such as maleic acid, are particularly preferred. It is preferable to use polyethylene, polypropylene, etc. modified with acrylic acid. Sealing with these sealing materials is performed by pressing the entire terminal board under heat using a press or the like.

On the other hand, it is preferable to use the above-mentioned polyolefin-based heat-fusible resin as an insulating sealing material for sealing the through-hole.

In this invention, the electrolytic solution is injected through the through hole (internal communication path) formed between the recess and the insulating sealing material.
Can be done via a suitable injection nozzle or syringe,
Depending on the case, this may be carried out by reducing pressure or pressurizing the injection, and in this case, two or more depressions are formed so that a through hole for injecting the electrolyte and a through hole for degassing are formed during sealing. It is suitable to use a terminal board having a Further, the electrolytic solution is injected so that the electrolytic solution is sufficiently impregnated into at least the inside of the battery power generating element.

In addition, sealing of the through hole after injecting the electrolyte can be carried out by filling or fitting the above-mentioned heat-fusible resin, for example, a modified polyolefin resin, into the through hole, and heating and pressurizing only that part. It is also possible to perform heating at a lower temperature than when sealing the entire structure.

(E) Function According to the present invention, when sealing a thin battery with an insulating sealing material, it is not necessary to impregnate the battery power generation element, which is the battery contents, with an electrolyte in advance, so that the sealing interface ( The interface between the terminal board and the insulating sealant, the interface between the insulating sealants, etc.) will not be contaminated by the electrolyte, and the electrolyte dissolved in the electrolyte and fine powder that may be contained in the battery power generation element will not be contaminated at the sealing interface. This eliminates the risk of residue remaining in the area, allowing for a seal with good sealing performance.

Furthermore, by injecting the electrolyte after sealing the parts other than the through-hole, it is possible to supply the necessary and sufficient amount of electrolyte to the battery contents, which was difficult to do if the electrolyte was injected before sealing. Therefore, a battery with low internal resistance and good discharge characteristics can be obtained.

(F) Examples Example 1 Regarding an example in which this invention is applied to a non-aqueous electrolyte secondary battery,
The explanation will be based on the drawings.

In Figure 3, ■ indicates stainless steel j14 (SUS30
4, a negative terminal plate made of a material having a thickness of 0.05xz), and 2 a positive terminal plate made of stainless steel as well. The positive electrode terminal plate 2 is drawn at the center in order to reduce the thickness of the moisture-permeable insulating sealing portion. Furthermore, a recess 3A is formed in the positive electrode terminal plate 2 by drawing so that a through hole for injecting electrolyte from the outside into the inside of the battery is formed.
3'A is applied. Negative terminal plate I and positive terminal plate 2
Insulating films 4A and 4B made of maleic acid-modified polyethylene resin are formed on predetermined peripheral portions of 0.00 to 0.000, respectively, by heat pressing. l
Attach it to a thickness of iz. First, on the positive terminal plate 2,
A positive electrode power generating element 5 consisting of a battery positive electrode mixture mainly composed of chromium oxide supported on a stainless steel wire mesh, a separator 6 consisting of a polypropylene nonwoven fabric (thickness 0.1x, w), and a device for reversibly charging and discharging lithium. A battery power generation element 8 made of a negative electrode power generation element 7 made of a nickel porous substrate coated with carbon is placed on top of the battery power generation element 8, and a negative electrode terminal plate l is placed on top of the negative electrode power generation element 7. The maleic acid-modified polyethylene coating film applied to the periphery of the positive and negative terminal plates by pressing a hot press plate is melted, cooled and solidified to form an insulating sealing body 4 as shown in FIG. The plate 2 and the negative electrode terminal plate 1 were joined and integrated, and at the same time, through holes 3 and 3' for electrolyte injection were formed. A propylene carbonate electrolyte containing 1 mol/Q of lithium perchlorate was injected into the through hole 3.3' using a microsyringe.

After that, a rod-shaped maleic acid-modified polyethylene resin is filled into the through hole 3.3', and a 180°C heat press is pressed against the through hole to seal it, resulting in a completed battery as shown in Figures 1 and 2. did.

To evaluate the sealability of the battery, a moisture resistance test (60°C, 90% R
H) was carried out, and the increase in internal resistance of the battery due to moisture intrusion into the battery from the outside was used as an index.

The results are shown in FIG. It was confirmed that the example according to the present invention was a battery with excellent sealing performance and good moisture resistance as compared with the comparative example described below.

The discharge characteristics of the battery were evaluated by measuring the internal resistance and discharge capacity of the battery. The internal resistance and discharge capacity showed excellent results as shown in FIG. 6 and Table 1.

The discharge capacity was measured by obtaining the discharge curve shown in FIG. 6, and as the internal resistance of the battery decreased, the slope of the discharge curve decreased and the capacity increased significantly.

Comparative example! In Example I, the electrolyte injection recess 3A.

Using the same members as in Example 1 except for using a positive terminal plate that does not have 3'A, a battery power generating element is placed on the positive terminal plate, and then the positive terminal plate and negative terminal are impregnated with electrolyte. The plates were bonded and sealed via a maleic acid-modified polyethylene resin adhered to the entire peripheral area of the plates to produce a battery.

The evaluation data of this battery is shown in FIGS. 5 to 6 and Table 1 as in Example 1, but the sealing performance was insufficient and the discharge capacity was small.

(G) Effects of the Invention According to the present invention, for example, in a thin battery, the adhesion of the sealing part interface becomes good, and reliability such as moisture resistance increases. In addition, a thin battery that is sufficiently filled with electrolyte, has low internal resistance, and high discharge capacity can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a thin battery according to an embodiment of the present invention, FIG. 2 is a sectional view taken along the line A-A in FIG. 1, and FIGS. An explanatory diagram showing the process,
FIG. 5 is a diagram showing the relationship between the number of days of humidity test and internal resistance of the thin battery, and FIG. 6 is a diagram showing the discharge capacity and voltage of the thin battery. l...Negative terminal plate, 2...Positive terminal plate, 3.3'...Through hole, 3A, 3'A...For electrolyte injection Hollow part, 3B,
3'B...Sealing part after electrolyte injection, 4...
...Insulating sealing body, 4A, 4B...Insulating film, 5.
... Positive electrode power generation element, 6 ... Separator,
7... Negative electrode power generation element, 8... Battery power generation element, 9... Sandwiching portion of the battery power generation element. Figure Figure Fi Electricity mAh')

Claims (1)

[Claims] 1. At least one of a pair of terminal plates with a sandwiching part of a battery power generation element set in the center is a terminal plate having a concave part continuous from the sandwiching part to the side edge, and the battery is placed between the pair of terminal plates. The power generating element and the insulating sealing material along its side periphery are sandwiched and heat pressed to seal the side periphery of the battery power generating element other than the recessed portion with the insulating sealing material, and then the recessed portion and the insulating sealing material are sealed. A method for manufacturing a thin battery, comprising injecting an electrolyte from the outside through a through hole formed between the two, and then sealing the through hole with an insulating sealing material.