JP2001155779A - Nonaqueous electrolyte battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a non-aqueous electrolyte battery that may prevent short circuit within the battery in the case where a bulge is occurring in the sheathing which is apt to be transformed by increase of a little inner pressure of the battery. SOLUTION: A non-aqueous electrolyte battery comprises a cell element including a positive electrode 5 having a positive core 10 formed with a positive active material 9, a negative electrode 6 having a negative core 17 formed with a negative active material 19, and a separator 15 interposed between the positive and negative electrodes. This cell element 1 is wound and received in a laminated sheathing 3 together with the non-aqueous electrolyte. Further, a positive core exposed portion 14 and a negative core exposed portion 18 in which both active materials are not coated are formed in the respective positive and negative electrode. Collector tabs 7, 8 are extended from both core exposed portions 14, 18. The non-aqueous electrolyte battery is characterized in that a flexibility securing film 16 is spreadingly attached to the separator 15 located at the positive core exposed portion 14 in the vicinity of the collector tabs 7, 8.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-aqueous electrolyte battery having an outer casing which is deformed by a slight increase in battery internal pressure, and in which a power generating element is housed.

[0002]

2. Description of the Related Art Heretofore, as an exterior body of a non-aqueous electrolyte battery, one entirely made of metal such as stainless steel has been used. However, in a battery using such an exterior body, the metal exterior body has to be thickened, and the mass of the battery increases accordingly. As a result, there are problems that it is difficult to reduce the thickness of the battery and that the mass energy density of the battery is reduced.

[0003] Therefore, the present inventors previously constructed a laminate outer package by forming a laminate material having a resin layer formed on both sides of a metal layer made of aluminum or the like via an adhesive layer in a bag shape. In the storage space of the laminate exterior, FIG.
As shown in (a), a thin battery that accommodates a power generating element 26 having current collecting tabs 24 and 25 extending from positive and negative electrodes 22 and 23 has been proposed. A battery having such a structure has the advantages that the size of the battery can be dramatically reduced and the mass energy density of the battery increases.

[0004] However, the battery using the above-mentioned laminated exterior body has a larger size than the battery using the metal exterior body.
The exterior body is flexible. Therefore, when the battery swells due to heating or overcharging or the like, the swelling becomes larger than when the outer body is made of a metal such as stainless steel, and as a result, as shown in FIG. As shown, the power generating element 26 is also significantly deformed. In this case, the current collecting tabs 24 and 25
Since the film itself is covered and protected by the film, the problem of a short circuit does not occur. On the other hand, in the vicinity of the current collecting tabs 24 and 25, stress concentrates on the portions due to the fact that only the current collecting tabs 24 and 25 are fixed to the laminate exterior body. As a result, as shown in FIGS. 9C and 9D, the core exposed portion 27 of the positive electrode 22 or the negative electrode 23 near the current collecting tabs 24 and 25 is greatly deformed so as to protrude, and comes into contact with other electrodes. As a result, there is a problem that a short circuit occurs in the battery.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and uses an exterior body such as a laminate exterior body which is deformed by a slight increase in battery internal pressure. It is an object of the present invention to provide a non-aqueous electrolyte battery that can suppress a short circuit in a battery even when the battery swells.

[0006]

Means for Solving the Problems To achieve the above object, the invention according to claim 1 of the present invention is directed to a positive electrode having a positive electrode active material layer formed on a belt-like positive electrode core, and a belt-like negative electrode. The negative electrode in which the negative electrode active material layer is formed on the core has a flat spiral power generating element wound through a separator, and the power generating element and the non-aqueous electrolyte are caused by a slight increase in battery internal pressure. A positive electrode core exposed portion and a negative electrode core exposed portion where the both active materials are not applied are formed on the positive electrode and the negative electrode, respectively, which are housed in a deformable exterior body. In a non-aqueous electrolyte battery having a structure in which a positive electrode current collecting tab and a negative electrode current collecting tab are respectively extended,
The positive electrode core exposed portion or the negative electrode core exposed portion in the vicinity of at least one current collecting tab of the two current collecting tabs, and the counter electrode core exposed at a position facing the positive electrode core exposed portion or the negative electrode core exposed portion. Wherein a flexible protective film is attached to at least one of the portion and the separator facing the exposed portion of the positive electrode core or the exposed portion of the negative electrode core. Electrolyte battery.

With the above structure, even if the outer package is deformed and the exposed portion of the positive electrode core or the exposed portion of the negative electrode core in the vicinity of the current collecting tab is greatly deformed, the presence of the protective film allows the two cores to be formed. Since the body exposed portion can be prevented from coming into contact with another electrode, it is possible to suppress a short circuit in the battery. The invention according to claim 2 is characterized in that, in the invention according to claim 1, a laminate exterior body is used as the exterior body that is deformed by the slight increase in the internal pressure of the battery.

According to a third aspect of the present invention, in the first or second aspect, the width of the flexible protective film is equal to the width of the exposed portion of the positive electrode core and / or the exposed portion of the negative electrode core. It is characterized in that it is configured to be larger. If the width of the protective film is larger than the width of the exposed portion of the positive electrode core and / or the exposed portion of the negative electrode core as in the above configuration, the exposed portions of the two cores can be further prevented from coming into contact with the other electrode. Short-circuiting can be reliably suppressed.

The invention described in claim 4 is the first or second invention.
In the invention according to the third aspect, the flexible protective film is made of a heat-resistant film. As in the above configuration, if the protective film is a heat-resistant film, even if the temperature of the battery rises, deformation of the protective film can be suppressed, so that short-circuiting in the battery can be reliably suppressed. .

The invention according to claim 5 is the invention according to claim 4, wherein the heat-resistant film is made of polyimide or polyphenylene sulfide. In addition, the invention described in claim 6 is based on claims 1, 2, 3, and 4.
Alternatively, in the invention described in Item 5, an ion-conductive polymer is used as the nonaqueous electrolyte.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First Embodiment A first embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a front view of the nonaqueous electrolyte battery according to the first embodiment, and FIG.
3 is a cross-sectional view taken along line AA of FIG. 3, FIG. 3 is a cross-sectional view of a laminate exterior body used in the nonaqueous electrolyte battery according to the first embodiment, and FIG. 4 is a power generation element used in the nonaqueous electrolyte battery according to the first embodiment. FIG. 5 is a sectional view taken along line BB of FIG. 4, FIG. 6 is a front view of a positive electrode used in the nonaqueous electrolyte battery according to the first embodiment, and FIG. 7 is a nonaqueous electrolyte according to the first embodiment. It is a front view of the negative electrode used for a battery.

As shown in FIG. 2, the non-aqueous electrolyte battery of the present invention has a power generating element 1, which is disposed in a storage space 2. As shown in FIG. 1, the storage space 2 is formed by sealing the upper and lower ends and the central portion of the laminate exterior body 3 with sealing portions 4a, 4b, and 4c, respectively. In addition, 1 mol / L of LiPF was added to a mixed solvent in which ethylene carbonate (EC) and diethyl carbonate (DEC) were mixed at a volume ratio of 4: 6.
_The solution obtained by dissolving ₆ was used as an electrolytic solution. This electrolytic solution and polyethylene glycol acrylate (molecular weight: 1000) were mixed at a ratio of 10: 1, and a polymerization initiator was further added to obtain a pregel solution. The pre-gel solution is injected into the storage space 2. As shown in FIGS. 4 and 5, the power generating element 1 includes a positive electrode 5 mainly composed of LiCoO ₂ (thickness: 0.17 mm) and a negative electrode 6 mainly composed of graphite (thickness: 0.14 mm). The separator (not shown in FIG. 4) 15 for separating these electrodes is wound in a flat spiral shape. The separator 15 has a low reactivity with an organic solvent and a microporous film (thickness: 0.1 μm) made of an inexpensive polyolefin resin.
025 mm).

Here, as shown in FIG.
Is a positive electrode core 10 (thickness: 20 μm) made of aluminum foil or aluminum mesh;
A positive electrode active material layer 9 having an active material applied thereto, and a positive electrode core exposed portion 14 having no active material applied to the positive electrode core 10, and the positive electrode core exposed portion 14 is made of aluminum. The positive electrode current collection tab 7 is connected. As shown in FIG. 7, the negative electrode 6 has a negative electrode core 17 made of copper foil.
(Thickness: 20 μm), a negative electrode active material layer 19 in which an active material is applied to the negative electrode core 17, and a negative electrode core exposed portion 18 in which the active material is not applied to the negative electrode core 17, The negative electrode current collector tab 8 made of copper is connected to the negative electrode core exposed portion 18. The two current collecting tabs 7 and 8 allow the chemical energy generated inside the battery to be extracted to the outside as electric energy. Further, as shown in FIG. 5, a flexible protective film 16 made of PPS (polyphenylene sulfide) is provided on the separator 15 at a position corresponding to the positive electrode core exposed portion 14 in the vicinity of the positive electrode current collecting tab 7. The protective film 16 suppresses a short circuit in the battery even when the battery swells.

As shown in FIG. 3, a specific structure of the laminate exterior body 3 is an aluminum layer 11 (thickness:
30 μm), resin layers 13 and 13 (thickness: 30 μm) made of polypropylene via adhesive layers 12 and 12 (thickness: 5 μm) made of modified polypropylene, respectively.
Is a structure to be bonded.

Here, the battery having the above structure was manufactured as follows. First, LiCoO ₂ as a positive electrode active material
And acetylene black and graphite as conductive agents, and polyvinylidenefluoride (PVdF) as binder at a mass ratio of 90: 5: 5 with N-
A positive electrode active material slurry or a positive electrode active material paste was prepared by dissolving and mixing in an organic solvent composed of methylpyrrolidone. Next, the positive electrode active material slurry or the positive electrode active material paste, a positive electrode active material slurry using a die coder or a doctor blade, and the positive electrode active material paste using a roller coating method, etc. The positive electrode active material layer 9 was formed by coating on both surfaces of the positive electrode positive electrode core 10 of the above. Next, the electrode plate coated with the positive electrode active material is dried in a drier to remove an organic solvent necessary for preparing the positive electrode active material slurry or the positive electrode active material paste. Then, the positive electrode 5 having a thickness of 0.17 mm was produced. At this time, on both surfaces of the positive electrode core 10 in the vicinity of the positive electrode current collecting tab 7, a positive electrode core exposed portion 14 where the positive electrode active material layer 9 was not formed was formed.

At the same time, natural graphite (d value = 3.36 °) as a negative electrode active material and polyvinylidene fluoride (PVdF) as a binder were added in a weight ratio of 9%.
The mixture was dissolved in an organic solvent composed of N-methylpyrrolidone at a ratio of 0:10 and mixed to prepare a negative electrode active material slurry or a negative electrode active material paste. Next, the negative electrode active material slurry or the negative electrode active material paste, in the case of the negative electrode active material slurry, using a die coder or a doctor blade,
In the case of the negative electrode active material paste, the negative electrode active material layer 19 was formed by applying the paste on both surfaces of a strip-shaped negative electrode core 17 made of copper by using a roller coating method or the like. Then, the electrode plate coated with the negative electrode active material is dried in a drier to remove an organic solvent necessary for preparing the negative electrode active material slurry or the negative electrode active material paste. The thickness is 0.14 by rolling at
mm of the negative electrode 6 was produced.

At this time, on both surfaces of the negative electrode core 17 in the vicinity of the negative electrode current collecting tab 8, a negative electrode core exposed portion 18 where no negative electrode active material layer 19 was formed was formed. Next, after the positive electrode current collecting tab 7 and the negative electrode current collecting tab 8 are attached to the both core exposed portions 14 and 18 of the positive and negative electrodes 5 and 6 respectively, the positive and negative electrodes 5 and 6 are arranged via the separator 15. I do. After a while
Positive and negative electrodes 5.6 and separator 15 using a winder
Was wound in a flat spiral shape, and the outermost peripheral portion was taped to produce a power generating element 1. At the time of this winding, a flexible protective film 1 made of PPS (polyphenylene sulfide) is provided on the separator 15 at a position corresponding to the positive electrode core exposed portion 14 in the vicinity of the positive electrode current collecting tab 7.
No. 6 was stuck.

Next, a sheet-like laminated material having a five-layered structure of a resin layer (polypropylene) / adhesive layer / aluminum alloy layer / adhesive layer / resin layer (polypropylene) is prepared, and an end portion of the laminated material is prepared. Neighboring parts were overlapped, and the overlapped part was welded to form a sealing part 4c. Next, the power generating element 1 was inserted into the storage space 2 for the cylindrical laminate. At this time, the power generating element 1 was arranged so that both the current collecting tabs 7 and 8 protruded from one opening of the cylindrical laminated material. Next, in this state, the laminated material in the opening from which the current collecting tabs 7 and 8 protruded was welded and sealed to form a sealed portion 4a. At this time, welding was performed using a high frequency induction welding apparatus.

Next, in this state, vacuum heating and drying (temperature: 105 ° C.) was performed for 2 hours to remove moisture from the laminate material and the power generating element 1. Thereafter, a solution in which 1 mol / l of LiPF ₆ is dissolved in a mixed solvent of ethylene carbonate and diethyl carbonate at a volume ratio of 4: 6 is used as an electrolyte, and this electrolyte and polyethylene glycol acrylate are used. (Molecular weight: 1000) and 1
The mixture was mixed at a ratio of 0: 1, and a polymerization initiator was further added to obtain a pregel solution. After injecting the pregel solution, the end of the laminate material opposite to the sealing portion 4a was welded using an ultrasonic welding device to form a sealing portion 4b. Next, in this state, the pregel solution was allowed to stand at room temperature for 3 hours to permeate the space between the positive and negative electrodes and the positive and negative electrode active materials. Thereafter, the exterior body was heated at 60 ° C. for 3 hours to gel the pregel solution inside the exterior body, thereby producing a non-aqueous electrolyte battery. still,
Only the pregel solution injection step was performed in a dry box in an argon atmosphere.

The protective film is not limited to the above PPS (polyphenylene sulfide).
A heat-resistant film such as polyimide may be used. However, the protective film is not limited to a heat-resistant film, but the effect of the present invention can be sufficiently exhibited by using a heat-resistant film.

The resin layer of the laminate exterior body is not limited to the above-mentioned polypropylene, but may be, for example, a polyolefin polymer such as polyethylene, a polyester polymer such as polyethylene terephthalate, polyvinylidene fluoride, polyvinylidene chloride, etc. Polyvinylidene polymer, nylon 6, nylon 66, nylon 7
And the like. Further, the structure of the laminate exterior body is not limited to the above five-layer structure. Furthermore, the exterior body is not limited to a laminate exterior body, and it goes without saying that the present invention can be applied to any exterior body that is deformed by a slight increase in battery internal pressure.

In addition, as the positive electrode material, the above LiCoO
_In addition to ₂ , for example, LiNiO ₂ , LiMn ₂ O ₄ or a composite thereof, or a conductive polymer such as polyaniline or polypyrrole is suitably used.In addition to the above-mentioned natural graphite, carbon black, Coke, glassy carbon, carbon fiber, or a fired body thereof are preferably used. Further, the present invention is not limited to a non-aqueous electrolyte battery provided with the above-mentioned gel electrolyte, but can be applied to other batteries such as a lithium ion battery using a non-aqueous electrolyte as an electrolyte. Further, as the electrolyte salt used,
The present invention is not limited to the above-described LiPF ₆ , but rather LiN (CF
It is also possible to use ₃ SO ₂ ) ₂ , LiClO ₄ , LiBF ₄ or the like.

Second Embodiment A second embodiment of the present invention will be described below with reference to FIG. FIG. 8 is a sectional view of a power generating element according to the second embodiment. As shown in FIG. 8, a flexible protective film 16 made of PPS (polyphenylene sulfide) is not attached to the separator 15 at a position facing the positive electrode core exposed portion 14 near the positive electrode current collecting tab 7, A non-aqueous electrolyte battery was produced in the same manner as in the first embodiment except that a flexible protective film 16 made of PPS (polyphenylene sulfide) was adhered to the positive electrode core exposed portion 14 near the electric tab 7. .

The position where the protective film is adhered is not limited to the separator of the first embodiment or the exposed portion of the positive electrode core of the second embodiment. The exposed portion of the negative electrode core may be located at a position facing the portion.
The above parts may be used. In the above two embodiments, the protective film is attached to the exposed core or the separator near the positive electrode current collecting tab, but the protective film is attached to the exposed core or the separator near the negative electrode current collecting tab. Of course, it may be possible.

[0025]

EXAMPLES Example 1 In Example 1, the battery shown in the first embodiment was used. The battery fabricated in this manner is hereinafter referred to as Battery A1 of the invention.

Example 2 In Example 2, the battery shown in the second embodiment was used. The battery fabricated in this manner is hereinafter referred to as Battery A2 of the invention.

Comparative Example A non-aqueous electrolyte battery was manufactured in the same manner as in Example 1 except that a flexible protective film made of PPS (polyphenylene sulfide) was not attached to the separator. The battery fabricated in this manner is hereinafter referred to as Comparative Battery X.

[Experiment 1] A heating test was performed on the batteries A1 and A2 of the present invention and the comparative battery X, and the results are shown in Table 1. In the test, after charging the batteries A1 and A2 of the present invention and the comparative battery X under the following conditions, a thermocouple was attached to the surface of each battery, the temperature was raised to 150 ° C. at a rate of 5 ° C./min, and the temperature was increased for 3 hours. This is the condition for holding. The number of samples was 10 for each battery.

Charging conditions: constant current, constant voltage charging, specifically charging at a current of 600 mA until the battery voltage reaches 4.2 V, and further constant after the battery voltage reaches 4.2 V The battery was charged for a total of 3 hours under the condition of conversion to voltage charging.

[0030]

[Table 1]

As is clear from Table 1, the comparative battery X produced smoke and fire, whereas the battery A1 of the present invention did not.
In A2, it is recognized that neither smoke, ignition nor rupture occurred. This is because, in the batteries A1 and A2 of the present invention, gas is generated inside the electrode plate at the time of heating, and even when the gas swells and the power generating element is deformed, the gas is generated at a position corresponding to the portion where the deformation is greatest. Since a protective film is stuck to the existing separator or the exposed portion of the positive electrode core, a short circuit inside the battery is prevented, whereas in the comparative battery X, the protective film does not exist in the relevant portion.
This is probably because a short circuit may occur inside the battery.

[Experiment 2] The overcharge test was performed on the batteries A1 and A2 of the present invention and the comparative battery X, and the results are shown in Table 2. Note that the test conditions were as follows:
After attaching the thermocouple to the surface of the battery 2 and the comparative battery X, the battery was charged at a constant current of 1200 mA for 3 hours. The number of samples was 10 for each battery.

[0033]

[Table 2]

As is clear from Table 2, the comparative battery X produced smoke and burst, whereas the battery A1 of the present invention did not.
In A2, it is recognized that neither smoke, ignition nor rupture occurred. This is considered to be due to the same reason as that described in Experiment 1 above.

[0035]

As described above, according to the present invention,
Uses an exterior body that is deformed due to a slight increase in battery internal pressure such as a laminate exterior body, and is excellent in that even if a battery using this exterior body swells, short-circuiting within the battery can be suppressed. It works.

[Brief description of the drawings]

FIG. 1 is a front view of a nonaqueous electrolyte battery according to a first embodiment.

FIG. 2 is a sectional view taken along line AA of FIG. 1;

FIG. 3 is a cross-sectional view of a laminate exterior body used for the nonaqueous electrolyte battery according to the first embodiment.

FIG. 4 is a perspective view of a power generating element used for the nonaqueous electrolyte battery according to the first embodiment.

FIG. 5 is a sectional view taken along line BB of FIG. 4;

FIG. 6 is a front view of a positive electrode used in the nonaqueous electrolyte battery according to the first embodiment.

FIG. 7 is a front view of a negative electrode used in the nonaqueous electrolyte battery according to the first embodiment.

FIG. 8 is a sectional view of a power generating element according to a second embodiment.

FIG. 9 is an explanatory cross-sectional view showing a state where a conventional battery swells and a short circuit occurs in the battery.

[Description of Signs] 1: Power generation element 2: Storage space 3: Laminate exterior body 5: Positive electrode 6: Negative electrode 7: Positive electrode current collecting tab 8: Negative electrode current collecting tab 9: Positive electrode active material layer 10: Positive electrode core 14: Positive electrode Core exposed part 15: Separator 16: Protective film 17: Negative electrode core 18: Negative electrode core exposed part 19: Negative electrode active material layer

 ────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Ikuo Nakane 2-5-5 Keihanhondori, Moriguchi-shi, Osaka F-term in Sanyo Electric Co., Ltd. (reference) 5H011 AA13 BB03 CC02 HH02 5H029 AJ12 AK03 AL07 AM00 AM03 AM05 AM07 AM16 BJ03 BJ14 DJ02 DJ04 DJ05 DJ07 EJ12

Claims (6)

[Claims] 1. A flat spiral in which a positive electrode in which a positive electrode active material layer is formed on a belt-shaped positive electrode core and a negative electrode in which a negative electrode active material layer is formed on a band-shaped negative electrode core are wound via a separator. In addition to having a power generating element in a shape, the power generating element and the non-aqueous electrolyte are housed in an outer casing that is deformed by a slight increase in battery internal pressure, and the aforesaid positive electrode and the negative electrode are coated with the amphoteric active material. A non-aqueous electrolyte battery having a structure in which a positive electrode core exposed portion and a negative electrode core exposed portion are respectively formed, and a positive current collecting tab and a negative current collecting tab are respectively extended from these two core exposed portions, The positive electrode core exposed portion or the negative electrode core exposed portion in the vicinity of at least one current collecting tab of the two current collecting tabs, and the counter electrode core exposed at a position facing the positive electrode core exposed portion or the negative electrode core exposed portion. Part, and the positive electrode core exposed part or the negative part Among the separator at the position facing the substrate exposed portion, at least in part, a non-aqueous electrolyte battery, characterized in that the flexible protective film is adhered. 2. The non-aqueous electrolyte battery according to claim 1, wherein a laminate exterior body is used as the exterior body deformed by a slight increase in battery internal pressure. 3. The non-woven fabric according to claim 1, wherein the width of the flexible protective film is configured to be larger than the width of the exposed portion of the positive electrode core and / or the exposed portion of the negative electrode core. Water electrolyte battery. 4. The non-aqueous electrolyte battery according to claim 1, wherein the flexible protective film comprises a heat-resistant film. 5. The non-aqueous electrolyte battery according to claim 4, wherein the heat-resistant film is made of polyimide or polyphenylene sulfide. 6. The non-aqueous electrolyte battery according to claim 1, wherein an ion conductive polymer is used as the non-aqueous electrolyte.