JP2000138042A - Organic electrolyte battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a sealant from leaking liquid due to softening at heating by interposing a gasket between a positive electrode can and a negative electrode can that serve respective terminals of a coin-type battery, and by arranging, in the facing portion, the sealant composed of one or more kinds of fluororesin where a part of butyl rubber, styrene-butadiene rubber, and a side chain is substituted by silicone resin. SOLUTION: In a gasket 3 portion facing a positive electrode can 1 and a negative electrode can 2 in which a generating element of a positive electrode 4 and a negative electrode 5 that face to each other through a separator 6 and organic electrolyte is sealed, these rubber or resin are diluted with toluene or the like and is coated, and a sealant 8 is formed. When a battery is mounted to a circuit board, the sealant 8 is not softened at a temperature about 250 deg.C during passing through a reflow furnace and therefore, holds its sealing ability. As this organic electrolyte, a solvent containing at least one of sulfolane and 3-methyl sulfolane which have a boiling point not less than 250 deg.C is preferably used, and it prevents inner pressure from rising during passing of the reflow furnace.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an organic electrolyte battery used for a main power supply of an electronic device and a power supply for memory backup, and more particularly, to a method of imparting high-temperature heat resistance to a battery component so as to improve reliability during high-temperature storage. The present invention relates to a coin-type organic electrolyte battery that has high temperature resistance and can be mounted on a circuit board by automatic soldering using a reflow method, while enhancing the performance.

[0002]

2. Description of the Related Art In general, an organic electrolyte battery using lithium or an alloy thereof for a negative electrode has a high energy density, is capable of reducing the size and weight of equipment, and has high reliability such as storage characteristics and leakage resistance. Due to its excellent performance, demand for a main power supply for various electronic devices and a power supply for memory backup is increasing year by year. This type of battery is mainly a non-rechargeable primary battery, but as a rechargeable secondary battery, a battery in which a negative electrode is composed of a lithium aluminum alloy or the like, and a positive electrode is a combination of vanadium pentoxide, lithium manganate, etc. A coin-type organic electrolyte battery in which these power generating elements are housed in a flat battery container has been widely put into practical use.

[0003] A coin-type organic electrolyte battery is suitably used as a power supply for memory backup of a small portable device. In particular, recently, a battery having a battery diameter of 6 mm or less has been actively developed. I have. In mounting such a battery on a circuit board, the size of the battery and the circuit board is reduced, so that if a manual mounting method is employed, the number of steps will be significantly increased. Therefore, as an efficient mounting method, an attempt has been made to mount the lead terminals of the battery by automatic soldering using a reflow method.

Hereinafter, the structure of the above-described coin-type organic electrolyte battery will be described with reference to the drawings.

In FIG. 1, a flat battery container for accommodating a power generating element includes a positive electrode can 1 also serving as a positive electrode terminal and made of stainless steel having excellent corrosion resistance, a negative electrode can 2 also serving as a negative electrode terminal, and a positive electrode can 1. And a gasket 3 between the anode can 2
The power generation element is hermetically sealed with the interposition of The power generating element is configured by arranging the positive electrode 4 and the negative electrode 5 with the separator 6 interposed therebetween.

The gasket 3 has a function of insulating the positive electrode can 1 and the negative electrode can 2 and a function of liquid-tightly sealing the power generating element in the battery container. In order to further improve the liquid tightness, the gasket 3 is provided with a sealant 8 on a surface in contact with the positive electrode can and the negative electrode can. As the sealant 8, a pitch such as asphalt or coal tar is used.

[0007]

The mounting of a small coin-type battery on a circuit board using the reflow method is performed by passing the battery through a reflow furnace.
The inside of the reflow furnace is in a high temperature state for a short period of time, and particularly in a peak time, it is in an extremely high temperature state of 250 ° C. for about several tens of seconds. At this time, the battery case is directly exposed to a high-temperature atmosphere as compared with the power generation element housed inside the battery case. Since both the positive and negative electrode cans are made of stainless steel, the effects of heat are small,
Other components are affected by heat.

In particular, since the sealant is applied to the contact surface between the metal part having higher heat conductivity than other components and the positive and negative electrode cans, the effect of the heat is remarkable.
It softens easily. Due to this softening, the properties of the sealant are deteriorated, and in addition, the sealant is caused to flow from the applied portion, so that the liquid tightness between the positive electrode can and the negative electrode can and the gasket is reduced, thereby causing leakage.

As described above, in the coin-type organic electrolyte battery,
There is a problem of suppressing generation of liquid leakage due to softening of the sealant due to heat during passage through a reflow furnace.

[0010]

Means for Solving the Problems To solve the above problems, an organic electrolyte battery according to the present invention comprises a positive electrode can also serving as a positive electrode terminal, a negative electrode can also serving as a negative electrode terminal, and a structure between the positive electrode can and the negative electrode can. A coin-type organic electrolyte battery in which a power generation element disposed opposite to a separator is hermetically sealed by an interposed gasket, and a portion where the gasket faces the positive electrode can and the negative electrode can, to a temperature range of about 250 ° C. It is characterized by disposing a sealant which does not cause softening. According to this configuration, even when the battery is passed through the reflow furnace,
It is possible to obtain a coin-type organic electrolyte battery in which the sealant does not soften and the probability of liquid leakage is greatly reduced.

[0011]

Embodiments of the present invention will be described below.

According to the first aspect of the present invention, a positive electrode can also serving as a positive electrode terminal, a negative electrode can also serve as a negative electrode terminal, and a gasket interposed between the positive electrode can and the negative electrode can are disposed to face each other with a separator interposed therebetween. In a coin-type organic electrolyte battery in which a power generation element is sealed, a portion of a gasket facing a positive electrode can and a negative electrode can has butyl rubber, styrene butadiene rubber, and a part of a side chain replaced with a silicone resin. It is characterized by disposing a sealant selected from a fluororesin.

These rubbers and resins applied as sealants are all excellent in heat resistance, and do not soften even when passed through a reflow furnace.
The tightness of the battery is maintained.

[0014] The invention described in claim 2 is the first invention.
Wherein the solvent containing at least one of sulfolane and 3-methylsulfolane is used as the organic electrolyte.

Since the sealant disposed on the surface of the gasket comes into contact with the organic electrolyte present in the battery container, the sealant must have chemical stability to the organic electrolyte. In other words, it is necessary to select an organic electrolyte that does not dissolve the sealant according to the present invention. Further, it is desired that the battery has a boiling point of 250 ° C. or higher in order to prevent the internal pressure of the battery container from rising due to the instantaneous vaporization of the electrolyte when passing through the reflow furnace. Propylene carbonate and ethylene carbonate, which are widely used as solvents for organic electrolytes, both have a boiling point of 250 ° C. or less, and therefore are not desirable for use as organic electrolyte batteries requiring high-temperature resistance. So, sulfolane,
A solvent containing at least one of 3-methylsulfolane is used as an organic electrolyte.

Here, the boiling point of sulfolane is about 287 ° C.
Since the boiling point of 3-methylsulfolane is about 275 ° C,
It is higher than the temperature inside the reflow furnace and has stable characteristics even in a high temperature atmosphere when passing through the reflow furnace. Further, since the sealant according to the present invention is not dissolved, liquid leakage is not induced.

As described above, the coin-type organic electrolyte battery according to the present invention has heat resistance of about 250 ° C. by combining a sealant having high temperature resistance and a power generation element, and has an automatic reflow method. It becomes possible to support mounting of a battery on a board using soldering.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below.

Example 1 In this example, a coin-type organic electrolyte battery having the structure shown in FIG. 1 was manufactured. A battery container having an outer dimension of 6.8 mm in diameter and 2.1 mm in thickness by combining a positive electrode can 1 made of stainless steel and a negative electrode can 2 was used. Polyphenylene sulfide (hereinafter, PPS) was used for the gasket 3 interposed between the positive electrode can 1 and the negative electrode can 2. This gasket 3 and positive electrode can 1
As the sealant 8 disposed between the negative electrode can 2 and the gasket 3, butyl rubber diluted with toluene is used, and is applied to a gasket in advance to be disposed at a predetermined position.

The positive electrode 4 is prepared by mixing carbon black as a conductive agent and a fluororesin powder as a binder with lithium manganate as an active material, forming a pellet having a diameter of 4 mm and a thickness of 1.2 mm. Was dried under an atmosphere of 12 hours. The obtained pellet-shaped positive electrode material is
The positive electrode can 1 is placed on a positive electrode current collector 7 formed by applying a carbon paint to the inner surface of the positive electrode can 1. On the other hand, the negative electrode 5 is made of aluminum-containing manganese added at a ratio of 5% by weight.
A manganese alloy is punched into a disk having a diameter of 4 mm and a thickness of 0.3 mm, and a lithium metal foil and an aluminum-manganese alloy are placed inside the negative electrode can 2 in this order. Furthermore, at the time of assembling the battery, in order to alloy the aluminum alloy with the lithium metal foil, a lithium metal foil is pressed against an aluminum-manganese alloy, and lithium is occluded in the aluminum alloy in the presence of an electrolytic solution to electrochemically form the lithium. An aluminum alloy is created. The prepared alloy was used as a negative electrode 5.

A PPS was used for the separator 6 disposed between the positive electrode 4 and the negative electrode 5 as in the case of the gasket. Further, as the electrolyte, sulfolane was used as an organic solvent for dissolving lithium salt as a solute. 10 μl is filled in the volume attached to the battery container. The battery obtained in this manner was referred to as Battery A according to Example 1.

(Example 2) As Example 2, a styrene-butadiene rubber diluted with toluene was applied as a sealant 8 to be applied to the gasket 3, and the other structure was as in Example 1.
A battery B having the same configuration as that of the battery A was prepared.

(Embodiment 3) As Embodiment 3, as a sealant 8 applied to the gasket 3, a fluororesin in which a part of a side chain is replaced with a silicone resin is diluted with toluene and applied. Battery C having the same configuration as battery A in Example 1 was produced.

(Comparative Example) As a comparative example, a pitch was applied as the sealant 8 applied to the gasket 3, and the other configuration was the same as that of the battery A in the first embodiment.
It was created.

The obtained batteries A to D were passed through a high-frequency heating type reflow furnace and subjected to a high-temperature environmental property test. The temperature profile inside the reflow furnace through which each battery passes is exposed to an environment of 180 ° C. for 2 minutes as a preheating step, and then is heated to 180 ° C. and 245 ° C. as a heating step.
After passing through each temperature atmosphere of 30 ° C. and 180 ° C. for 30 seconds, it is naturally cooled to room temperature. In this example, for each of the 50 batteries, after confirming in advance that there was no leakage before inserting the battery into the reflow furnace, the batteries were passed through the reflow furnace and inspected for the state of occurrence of the leakage.
The batteries that did not generate liquid leakage were passed through a reflow furnace again to check the generation status. (Table 1) shows the occurrence of liquid leakage after passing through the reflow furnace.

[0026]

[Table 1]

As shown in Table 1, the battery according to the present invention is superior in the liquid leakage resistance after passing through the reflow as compared with the comparative product D using the pitch as the sealant.

As described above, the batteries A, B, and C according to the present invention were obtained.
In any case, no liquid leakage occurred after passing through the reflow furnace, and it was found that the liquid was excellent in liquid leakage resistance. This is because butyl rubber, styrene butadiene rubber, and a fluororesin whose side chains are partially substituted with a silicone resin used for the sealant have heat resistance and did not soften.

In this embodiment, an organic electrolytic solution using sulfolane as a solvent is used as the electrolytic solution. However, the same effect can be obtained when 3-methylsulfolane is used. Further, in the present embodiment, the case of a secondary battery capable of charging and discharging has been described as an example, but for example, an organic electrolyte primary battery using lithium metal for the negative electrode and manganese dioxide or graphite fluoride for the positive electrode, for example. The same effect can be obtained by applying

[0030]

As described above, according to the present invention, it is possible to provide an organic electrolyte battery having high temperature resistance, which can be mounted on a circuit board by automatic soldering using a reflow method. Furthermore, since mounting by automatic soldering becomes possible, it goes without saying that the manufacturing process of a small portable device using this type of battery can be simplified. In addition, by imparting high-temperature heat resistance to the battery components, characteristics during high-temperature storage are improved, and the reliability of an organic electrolyte battery used in a high-temperature environment is greatly improved.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a configuration of a coin-type organic electrolyte battery.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Positive electrode can 2 Negative electrode can 3 Gasket 4 Positive electrode 5 Negative electrode 6 Separator 7 Positive electrode current collector 8 Sealant

Continued on the front page (51) Int.Cl. ⁷ Identification FI FI Theme Court (Reference) H01M 10/40 H01M 10/40 ZB (72) Inventor ▲ Takayoshi Hashihashi 1006 Kazuma Kadoma, Kadoma City, Osaka Matsushita Electric F-term (reference) within Sangyo Co., Ltd.

Claims (2)

[Claims] 1. A power generating element which is disposed opposite to a separator via a separator is sealed by a positive electrode can also serving as a positive electrode terminal, a negative electrode can also serving as a negative electrode terminal, and a gasket interposed between the positive electrode can and the negative electrode can. At least one of butyl rubber, styrene-butadiene rubber, and a fluorine resin in which a part of a side chain is replaced by a silicone resin is provided in a portion of the coin-type organic electrolyte battery facing the positive electrode can and the negative electrode can in the gasket. An organic electrolyte battery comprising a sealant comprising: 2. The organic electrolyte battery according to claim 1, wherein an organic electrolyte comprising a solvent containing at least one of sulfolane and 3-methylsulfolane is used.