JPS6180749A - Manufacturing method of flat 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 [Technical Field of the Invention] The present invention relates to a method for manufacturing a flat battery, and particularly to a method for manufacturing a flat battery with an improved sealing process.

[Technical background of the invention and its problems]

In recent years, as electronic devices have become smaller and thinner, there has been an increasing demand for thinner batteries that power these devices. However, in conventional button-type and coin-type batteries, the thickness can only be reduced to at least about 1.0 mm, and the above requirements cannot be fully satisfied.

For this reason, the applicant has already proposed a flat battery having the following structure. That is, this flat battery uses a positive terminal plate in which a positive electrode active material is arranged in an area excluding the area around the outer edge, and a frame-shaped insulating sealing plate made of synthetic resin is arranged around the outer edge of this positive electrode terminal plate. , a separator is disposed on the positive electrode active material, and a negative electrode terminal plate on which a negative electrode active material is disposed is brought into contact with the separator, and the periphery of the terminal plate is brought into contact with the insulating sealing plate. After arranging the positive and negative electrodes in this order, the terminal plates of the positive and negative electrodes and the insulating sealing plate are heat-fused and sealed. According to a flat battery having such a structure, the thickness is 1. It can be made thinner than the O limit and fully satisfies the above requirements.

However, in the above-mentioned sealing process by heat fusion, if there is an object such as an electrolyte between the terminal boards to be fused and the insulating sealing plate, the sealing performance will be insufficient.

In particular, if the impurity is an electrolytic solution, the heat during heat fusing is also used for evaporation of the electrolyte, resulting in insufficient heat fusing, and the sealability is significantly reduced.

As a means to solve the above-mentioned problems, a method can be considered that ``the amount of electrolyte is kept at 60% or less of the gap behind the sealing port of the battery so that the area to be fused is not wetted by the electrolyte.

However, if there are more voids inside the battery after the sealing port,
The following problems arise.

That is, as the number of voids increases, the portion of the terminal plate (N pole) facing the void increases and no electrode reaction takes place, resulting in a decrease in the effective electrode area. As a result, the voltage drop during discharging, especially during heavy load discharging, increases. In addition, as more parts are not involved in the electrovaginal reaction (in other words, involved in discharge),
The discharge capacity l of the battery decreases.

[Purpose of the invention]

The present invention aims to provide a method for manufacturing a flat battery, which not only can reliably seal the opening, but also greatly reduces the amount of voids remaining in the battery after the sealing, and improves heavy load discharge characteristics, etc. It is.

[Summary of the invention]

In the present invention, a frame-shaped insulating sealing plate is interposed between both terminal plates of a sheet-shaped positive and negative electrode, and a battery power generation element is housed in a space surrounded by both terminal plates and the sealing plate. In manufacturing the flat battery, the sealing step is performed in a reduced pressure environment. According to the present invention, by performing the sealing process in a lower pressure environment than when the battery is actually used, when the battery is put into the actual use state (atmospheric pressure) after the sealing, the difference between the pressure inside the battery and the atmospheric pressure causes The remaining voids within the battery are compressed and the amount of voids can be reduced. Furthermore, by sealing the opening in the reduced pressure environment, air remaining in the active material constituting the battery power generation element can be effectively discharged, so that the electrolyte can seep into the active material better. Therefore, not only can sealing be performed reliably, but also the amount of voids remaining in the battery after sealing has been significantly reduced, and the seepage of the electrolyte into the active material has been improved, improving heavy load discharge characteristics, etc. A flat battery can be obtained.

(Embodiments of the Invention) Hereinafter, an example in which the present invention is applied to a flat type lithium/manganese dioxide type organic solvent battery will be described with reference to FIG.

First, a sheet-shaped positive electrode terminal plate 2 is prepared, on which a positive electrode active material 1 made of manganese dioxide, a conductive agent, and a binder is placed on an area excluding the area around the outer edge. A frame-shaped insulating sealing plate 3 made of heat-fusible resin was placed. Subsequently, a separator 4 impregnated with an electrolytic solution was placed on the positive electrode active material 1. This electrolytic solution consists of a solution in which lithium perchlorate is dissolved in proprene carbonate at a ratio of 1 mol/liter. Subsequently, a sheet-like negative electrode terminal plate 6 on which metal lithium 5 is arranged is prepared, and the metal lithium 5 is connected to the separator 4.
The unsealed battery material shown in FIG. 1 was prepared by arranging the terminal plate 6 so that the outer edge of the terminal plate 6 was in contact with the insulating sealing plate 3.

Next, the unsealed battery material was subjected to o, oi, o.

2.0.4.0.6.0.8 and 1.0 atm using a frame-shaped heating/pressure jig to heat the positive and negative terminal plates 2.6 and the frame-shaped insulating sealing plate 3, respectively. Six types of flat organic solvent batteries were manufactured by heat-sealing and sealing the ports.

Therefore, for each of the above 20 batteries, 68
When the discharge capacity was measured with a final voltage of 2.7 Ω during continuous discharge of Ω, the characteristic diagram shown in FIG. 2 was obtained. In addition, for each 20 batteries, after discharging 80% of the discharge capacity, 1Ω at 0°C.

When the lowest terminal voltage was measured when pulse discharge was performed for 5 seconds, the characteristic diagram shown in FIG. 3 was obtained.

As is clear from these FIGS. 2 and 3, it can be seen that the lower the air pressure at the time of sealing, the greater the discharge capacity, and the smaller the variation thereof. It can also be seen that the voltage drop is small even in heavy load pulse discharge. From these results, the lower the pressure in the sealing step, the greater the effect can be achieved, but industrially, the effect can be efficiently and fully utilized by reducing the pressure to 0.2 atm or less.

In addition, although the above-mentioned example explained a lithium manganese dioxide type organic solvent battery, it is not limited to this. For example, the same effect as in the example can be obtained in other lithium-carbon batteries such as lithium-fluorocarbon-based Akebono solvent batteries, other primary batteries such as alkaline manganese batteries, or secondary batteries such as nickel-cadmium batteries. can be achieved.

〔Effect of the invention〕

As detailed above, according to the present invention, not only can sealing be performed reliably, but also the amount of voids remaining in the battery after sealing can be significantly reduced, and the seepage of the electrolyte into the active material can be improved. It is possible to provide a method for manufacturing a highly reliable, high-performance flat battery with improved heavy load discharge characteristics and the like.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing an unsealed battery material in an example of the present invention, FIG. 2 is a characteristic diagram showing the discharge capacity of batteries obtained by sealing under different atmospheric pressure environments, and FIG. FIG. 3 is a characteristic diagram showing the terminal voltage during low temperature heavy load pulse discharge in each of the same batteries. DESCRIPTION OF SYMBOLS 1... Positive electrode active material, 2... Positive electrode terminal plate, 3... Frame-shaped insulating sealing plate, 4... Separator, 5... Metal lithium (negative electrode active material), 6... Negative electrode terminal board. Applicant's agent Patent attorney Ken Suzue Takehiko

Claims (1)

[Claims] Production of a flat battery in which a frame-shaped insulating sealing plate is interposed between both terminal plates of a sheet-shaped positive and negative electrode, and a battery power generating element is housed and sealed in a space surrounded by both terminal plates and the sealing plate. A method for manufacturing a flat battery, characterized in that the sealing step is performed in a reduced pressure environment.