JPH11195405A - Thin battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To open a battery before the internal pressure of the battery is increased without mounting a pressure releasing valve on the battery by opening the sealed part of a laminate facing body when the internal pressure of the battery reaches a specified range value. SOLUTION: This thin battery has a generating element 1 formed of a positive electrode consisting of LiCoO2 , a negative electrode consisting of a carbon material, and a separator for isolating both the electrodes. The generating element 1 is arranged within a housing space 3, and the housing space 3 is formed by sealing the upper and lower ends of a laminate facing body 2 by seal parts 4a, 4b. The seal parts 4a, 4b of the laminate facing body 2 are opened when the internal pressure of the battery reaches 3-5 kg/cm<2> . Even when the battery is ruptured, the scattering quantity of electrolyte can be suppressed also with suppression of reduction in battery performance. Thus, breakage of an equipment using the battery can be prevented without increasing the manufacturing cost of the battery.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thin battery having a power generating element and a laminate outer package having a housing space for housing the power generating element by welding and sealing a laminate material. .

[0002]

2. Description of the Related Art In recent years, as electronic devices and the like have become smaller, it has been desired to reduce the size of batteries. In order to achieve the miniaturization of the battery, the present inventors first formed a laminate outer body by forming a laminate material in which a resin layer was formed on both sides of an aluminum layer via an adhesive layer in a bag shape. Proposed a thin battery in which a power generation element is stored in the storage space of the laminate exterior body. With a battery having such a structure, the size of the battery can be dramatically reduced.

[0003] However, in a thin battery using the above-mentioned laminated outer package, the electrolyte in the battery may evaporate and the internal pressure of the battery may increase. If the battery ruptures in such a state, the battery components such as the electrolyte solution or the electrodes may scatter outside the battery, possibly damaging equipment using the battery. Therefore, it is conceivable to attach a pressure release valve to the battery so as to open before the internal pressure of the battery increases.
However, such a structure requires a new material for forming the pressure relief valve, and further requires a new operation step of attaching the pressure relief valve to the battery, so that the manufacturing cost of the battery increases. Had issues.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has been made in view of the above-mentioned circumstances by opening a battery before the internal pressure of the battery increases without mounting a pressure release valve on the battery. Without increasing manufacturing costs
It is an object of the present invention to provide a thin battery that can prevent damage to equipment using the battery.

[0005]

In order to achieve the above object, according to the first aspect of the present invention, the power generating element is housed by welding and sealing the power generating element and a laminate material. Battery having a storage space for storing the same, the sealing portion of the laminate outer case is opened when the internal pressure of the battery reaches ³ to 5 kg / cm ^2. Features.

As described above, the internal pressure of the battery is 3 to 5 kg /
The reason why the sealing portion is opened at the time of reaching cm ² is as follows. That is, when the internal pressure of the battery is less than 3 kg / cm ² and the sealing portion is opened, moisture may intrude from the sealing portion or the electrolytic solution may not be formed due to insufficient sealing force of the sealing portion. Evaporates, so that the battery performance such as storage characteristics deteriorates. On the other hand, if the internal pressure of the battery exceeds 5 kg / cm ² and the sealing portion is opened, when the battery ruptures, the amount of the battery component such as the electrolyte or the electrode scattered outside the battery is remarkably increased. The reason for this is that there is a possibility that the device using the battery may be damaged due to the increase in size.

According to a second aspect of the present invention, in the first aspect, the width of the sealing portion is 2 to 10 mm, preferably 3 to 7 mm. If the width of the sealing portion is less than 2 mm, the internal pressure of the battery is likely to be less than 3 kg / cm ^2, and if the width of the sealing portion exceeds 10 mm, This is because the internal pressure of the battery is likely to exceed 5 kg / cm ² , which increases the possibility of causing the above-described inconvenience.

According to a third aspect of the present invention, in the second aspect of the present invention, when the width of the sealing portion is 3 to 10 mm, the laminating material is welded when forming the sealing portion. It is characterized in that the temperature is 200 ° C. or more and 300 ° C. or less. By regulating the width of the sealing portion and the welding temperature of the laminate material in this manner, the internal pressure of the battery becomes 3 to 5 kg / c.
At the time when m ² is reached, the sealing portion is reliably opened.

According to a fourth aspect of the present invention, in the second aspect of the invention, when the width of the sealing portion is 2 to 7 mm, the laminating material is welded when forming the sealing portion. It is characterized in that the temperature is higher than 300 ° C. and not higher than 350 ° C. By regulating the width of the sealing portion and the welding temperature of the laminate material in this manner, the internal pressure of the battery becomes 3 to 5 kg / c.
At the time when m ² is reached, the sealing portion is reliably opened.

[0010] The invention described in claim 5 is based on claim 1,
The invention according to 2, 3 or 4, wherein an ultrasonic welding device or a high-frequency induction welding device is used for welding the laminate. When a laminate material is welded using such an apparatus, sealing can be performed without wetting the sealing portion with an electrolytic solution, so that better sealing can be achieved. Specifically, if the method of simply heating and welding the laminated material is used, the sealing is performed in a state where the electrolytic solution is sandwiched between the laminated materials, so that the sealing portion is wet with the electrolytic solution. On the other hand, if the laminate is welded using an ultrasonic welding device, the electrolyte between the laminates is pushed out of the battery by vibration, so that the sealing portion can be prevented from being wet with the electrolyte. In addition, if the laminate is welded using a high-frequency induction welding device, the electrolyte between the laminates is also pushed out of the battery as the resin moves, so that the sealing portion can be prevented from getting wet with the electrolyte.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a front view of the thin battery of the present invention, and FIG. 2 is a side view of the thin battery of the present invention. As shown in FIGS. 1 and 2, the thin battery of the present invention has a positive electrode made of LiCoO ₂ , A power generating element 1 including a negative electrode made of a carbon material and a separator separating the two electrodes. This power generating element 1 is a storage space 3
The storage space 3 is formed by sealing the upper and lower ends of the laminate exterior body 2 with the sealing portions 4a and 4b. The storage space 3 contains ethylene carbonate (EC) and diethyl carbonate (DEC).
Is mixed in a mixed solvent of 3: 7 in volume ratio with Li
An electrolyte in which PF ₆ is dissolved at a rate of 1 M (mol / liter) is injected.

Here, the laminate outer body 2 (thickness:
The specific structure of 100 μm) is such that a resin layer (thickness: 20 μm) of polypropylene is provided on one surface of an aluminum alloy layer (thickness: 30 μm) via an adhesive layer (thickness: 2 μm) of a urethane-based adhesive. Is bonded, and a resin layer (thickness: 60 μm) made of polypropylene is bonded to the other surface of the aluminum alloy layer via an adhesive layer (thickness: 2 μm) made of modified polypropylene.

The positive electrode is connected to a positive electrode current collecting terminal 5 made of aluminum, and the negative electrode is connected to a negative electrode current collecting terminal 6 made of nickel, so that chemical energy generated inside the battery can be taken out as electric energy. It has become. In addition, as shown in FIG. 1, the size of this battery is configured such that the width L ₁ is 36 mm and the length L ₂ is 65 mm, and the width L _3.
L ₄ is a is configured to be 5 mm.

Here, the battery having the above structure was manufactured as follows. First, both ends of a strip-shaped laminate material having a five-layer structure of a resin layer (polypropylene) / adhesive layer / aluminum alloy layer / adhesive layer / resin layer (polypropylene) are welded to form a cylindrical shape. The power generating element 1 was inserted into the storage space 3 of the laminate material. At this time, the power generating element 1 was arranged so that both the current collecting terminals 5 and 6 protruded from one opening of the cylindrical laminated material. Next, in this state, the laminated material in the opening from which the current collecting terminals 5 and 6 protruded was welded and sealed to form a sealed portion 4a. At this time, welding was performed using a high frequency induction welding apparatus. Here, the welding conditions at this time are a welding temperature of 300 ° C., a welding width of 5 mm, and a welding time of 1 second.

Next, in this state, vacuum heating and drying (temperature: 105 ° C.) was performed for 2 hours to remove moisture of the laminate material and the power generating element 1. Thereafter, an electrolyte in which LiPF _{6 as} a solute was dissolved at a ratio of 1 M (mol / liter) was injected into a mixed solvent in which ethylene carbonate and diethyl carbonate were mixed at a volume ratio of 3: 7. This was left for 1 hour. Thereafter, while pressing the laminate material corresponding to the power generating element 1 with a metal plate, the end of the laminate material opposite to the sealing portion 4a is welded using an ultrasonic welding device, and the sealing portion 4b is removed. By forming, a thin battery was manufactured. The welding conditions at this time were the same as those described above, and the steps after the electrolyte injection step were performed in a dry box in an argon atmosphere.

Here, the resin layer of the laminate outer package 2 is not limited to the above-mentioned polypropylene, but may be, for example, a polyolefin-based polymer such as polyethylene, a polyester-based polymer such as polyethylene terephthalate, polyvinylidene fluoride, or polyvinylidene. Polyvinylidene polymers such as vinylidene chloride; polyamide polymers such as nylon 6, nylon 66 and nylon 7;

The thickness of the resin layer is not less than 1 μm and not more than 500 μm.
μm or less, preferably 5 μm or more and 100 μm or less, and the thickness of the metal layer is 0.1 μm or more and 20 μm or less.
It is desirably 0 μm or less, preferably 1 μm or more and 50 μm or less. This is because if the thickness of the metal layer or the resin layer is too small, the oxygen permeability becomes high, causing a problem such as a decrease in battery characteristics. On the other hand, if the thickness of the resin layer is too large, the workability is reduced. This is because if the thickness of the metal layer is too large, the battery becomes heavy and the battery lacks flexibility. From these facts, it is desirable that the thickness of the entire resin / metal laminate is 2 μm or more and 1 mm or less, preferably 10 μm or more and 200 μm or less.

Further, as the positive electrode material, the above LiCoO ₂
However, for example, LiNiO ₂ , Li
Mn ₂ O ₄ or a composite thereof may be used,
Further, the present invention is not limited to the above-mentioned lithium ion battery, but can be applied to other batteries such as a polymer battery in which a solid electrolyte exists between the positive and negative electrodes. In addition, the welding time is 1
It is confirmed by experiments that the effect is not limited to seconds and that the same effect can be obtained if it is 1 to 3 seconds.

[0019]

EXAMPLES [Examples] As examples, batteries having the structure shown in the above embodiment of the present invention were used. The battery fabricated in this manner is hereinafter referred to as Battery A of the invention.

Comparative Example 1 The width of the sealing portions 4a and 4b was 1 m.
A battery was fabricated in the same manner as in the above example except that m was used. The battery fabricated in this manner is hereinafter referred to as Comparative Battery X
No. 1.

Comparative Example 2 A battery was manufactured in the same manner as in the above example, except that the fusion temperature at the time of forming the sealing portions 4a and 4b was 400 ° C. The battery fabricated in this manner is hereinafter referred to as Comparative Battery X2.

Comparative Example 3 A battery was manufactured in the same manner as in the above example except that the fusion temperature at the time of forming the sealing portions 4a and 4b was 180 ° C. The battery fabricated in this manner is hereinafter referred to as Comparative Battery X3.

[Experiment 1] In the battery A of the present invention and the comparative batteries X1 to X3, the internal pressure when the battery was opened, the scattering rate of the contents when the battery was opened, and the capacity after storing the battery at 60 ° C. for 20 days. The recovery rate was examined, and the results are shown in Table 1.
Shown in In addition, the scattering rate of the contents at the time of opening the battery was calculated by Equation 1, and the capacity recovery rate was calculated by Equation 2.

[0024]

(Equation 1)

[0025]

(Equation 2)

[0026]

[Table 1]

As apparent from Table 1, in the battery A of the present invention, the internal pressure at the time of opening the battery is about 4.3 kg / cm ² and the scattering rate of the contents is about 5.3%. In the comparative batteries X1 and X3, the internal pressure when the battery was opened was about 2.4 kg.
/ Cm ² and the scattering rate of the contents is about 3.5%. Therefore, it is recognized that the scattering rates of the contents of the comparative batteries X1 and X3 are smaller than that of the battery A of the present invention. But,
The battery A of the present invention has a capacity recovery rate of about 77%, while the comparative batteries X1 and X3 have a capacity recovery rate of about 65%, which is extremely small. In addition, since the welding temperature of the comparative battery X2 was too high, the resin layer of the sealing portion was largely melted by heat, and sufficient sealing could not be performed.

Based on the above experimental results, the relationship between the internal pressure when the battery is opened and the scattering rate of the contents, the relationship between the internal pressure when the battery is opened and the capacity recovery rate, and when the welding temperature is changed. The relationship between the sealing width and the internal pressure when the battery was opened was examined, and is shown below.

[Experiment 2] The relationship between the internal pressure when the battery was opened and the scattering rate of the contents was examined. The results are shown in FIG. The scattering rate of the contents when the battery was opened was calculated in the same manner as in Experiment 1. As is apparent from FIG. 3, when the internal pressure at the time of opening the battery is 5 kg / cm ² or less, the scattering rate of the contents is as small as about 7% or less, but the internal pressure at the time of opening the battery is 5 k / cm ^2.
When it exceeds g / cm ² , it is recognized that the scattering rate of the contents rapidly increases. Therefore, in order to suppress the scattering of the contents, it is desirable to regulate the internal pressure at the time of opening the battery to 5 kg / cm ² or less.

[Experiment 3] Internal pressure at battery opening and 60 ° C.
And the relationship with the capacity recovery rate after storage for 20 days was examined. The results are shown in FIG. The capacity recovery rate was calculated in the same manner as in Experiment 1. As is clear from FIG.
When the internal pressure at the time of opening the battery is 3 kg / cm ² or more, the capacity recovery rate is as high as about 75% or more. However, when the internal pressure at the time of opening the battery is less than 3 kg / cm ² , the sealing is insufficient and It is recognized that the capacity recovery rate sharply decreases due to intrusion of the electrolyte into the battery and evaporation of the electrolyte. Therefore, to keep the capacity recovery rate high,
It is desirable to regulate the internal pressure at the time of opening the battery to 3 kg / cm ² or more. From the results of Experiments 2 and 3, it can be seen that the internal pressure at the time of opening the battery must be regulated to ³ to 5 kg / cm ² in order to achieve a high capacity recovery rate and to suppress the scattering of the contents.

[Experiment 4] The relationship between the sealing width when the welding temperature was changed and the internal pressure when the battery was opened was examined, and the results are shown in FIG. As is clear from FIG.
When the width of the sealing portion is 3 to 10 mm and the welding temperature of the laminate material is 200 ° C. or more and 300 ° C. or less, it is recognized that the internal pressure at the time of opening the battery can be reliably regulated to 3 to 5 kg / cm ^2. When the width of the sealing portion is 2 to 7 mm, the welding temperature of the laminate exceeds 300 ° C.
If the temperature is 50 degrees or less, the internal pressure when the battery is opened is 3 to 5 kg.
/ Cm ² can be reliably controlled.

[0032]

As described above, according to the present invention,
It is possible to suppress a decrease in battery performance such as storage characteristics due to intrusion of moisture from the sealing portion or evaporation of the electrolyte,
Moreover, even when the battery is ruptured, the amount of the battery components such as the electrolyte solution or the electrodes scattered outside the battery can be suppressed, so that it is possible to prevent a device using the battery from being damaged. To play.

[Brief description of the drawings]

FIG. 1 is a front view of a battery of the present invention.

FIG. 2 is a side view of the battery of the present invention.

FIG. 3 is a graph showing a relationship between an internal pressure when a battery is opened and a scattering rate of contents.

FIG. 4 is a graph showing a relationship between an internal pressure at the time of opening a battery and a capacity recovery rate.

FIG. 5 is a graph showing the relationship between the sealing width when the welding temperature is changed and the internal pressure when the battery is opened.

[Explanation of symbols]

 1: power generation element 2: laminate exterior 3: storage space 4a: sealing portion 4b: sealing portion

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor: Nori Ikukawa 2-5-5 Keihanhondori, Moriguchi-shi, Osaka Sanyo Electric Co., Ltd.

Claims (5)

[Claims] 1. A thin battery comprising: a power generating element; and a laminate exterior body in which a housing space for housing the power generating element is formed by welding and sealing a laminate material. When it reaches 3-5 kg / cm ² ,
A thin battery, wherein a sealing portion of the laminate exterior body is open. 2. The thin battery according to claim 1, wherein the width of the sealing portion is 2 to 10 mm, preferably 3 to 7 mm. 3. The method according to claim 2, wherein when the width of the sealing portion is 3 to 10 mm, a welding temperature of the laminate material when forming the sealing portion is 200 ° C. or more and 300 ° C. or less. Thin battery. 4. When the width of the sealing portion is 2 to 7 mm, a welding temperature of the laminate material when forming the sealing portion is more than 300 ° C. and 350 ° C. or less. Thin battery. 5. An ultrasonic welding device or a high-frequency induction welding device is used for welding the laminate material.
The thin battery according to 2, 3 or 4.