JP2003051292A - Sealed battery and sealing plate thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sealing plate equipped with superior safe functional parts operating upon overcharge or abnormal use and a sealed cell superior both sealing property and productivity, using this sealing plate. SOLUTION: The sealing plate for a sealed battery, in which a safe functional part is provided between an internal terminal plate and an insulating spacer, and an electrode terminal plate 2, to which a cap and the safe functional part have been connected, is caulked by a rib provided on the surface of the sealing plate 1, is used.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of a sealing plate and a sealed battery using the sealing plate.

[0002]

2. Description of the Related Art In recent years, the performance of mobile electronic devices such as mobile phones and personal digital assistants largely depends not only on the performance of semiconductor elements and electronic circuits, but also on the performance of rechargeable secondary batteries. It is desired to increase the capacity of the secondary battery to be mounted and to realize light weight and thinness at the same time. As a secondary battery that meets these demands, a nickel-hydrogen storage battery having an energy density about twice that of a nickel-cadmium storage battery has been developed, and then a lithium secondary battery using a nonaqueous electrolyte has a higher energy density. It was developed as and is in the spotlight.

Among these lithium secondary batteries, the proportion of prismatic sealed batteries, which are excellent in high energy density and load characteristics, suitable for thinning equipment and high in space efficiency, is increasing. Further, as the performance and functionality of electric devices have advanced, batteries of higher voltage and capacity have been demanded.

The structure of a conventional sealing plate as shown in FIG. 8 is generally known.

The sealing plate 1 is provided with an electrode terminal plate 2, and the electrode terminal plate 2 is constructed such that a part of the sealing plate 1 has a through hole (not shown) of about 1 to 2 mm. With the sealing plate 1 sandwiched between the lower terminal plate 13 and the battery inside the sealing plate 1,
The gasket 3 is laminated on the inner gasket 21 and the outer side of the battery, and the hollow rivet 20 is further penetrated through the gasket 3.
Insert and crimp with the crimp punch, and then electrode terminal plate 2
Are configured.

Then, after accommodating the power generating element 7 in which the positive electrode plate and the negative electrode plate are insulated via the separator in the bottomed metal case 6 having an open upper part, the power generating element 7 is inserted into the opening of the case 6 as described above. The sealing plate 1 having the above structure is fitted, and the sealing plate 1 and the case 6 are welded and sealed by using a laser or the like, and then the liquid injection hole 4 provided in either the sealing plate 1 or the case 6. Then, the electrolytic solution is injected thereinto, and then the sealing plug 5 is welded using a laser or the like to form a closed structure.

[0007]

However, with such a structure of the electrode terminal plate, as the battery becomes thinner, the pin diameter of the hollow rivet becomes thinner and the wall thickness also becomes thinner. Caulking becomes difficult,
In addition, the caulking strength decreases, the sealing of the electrode terminal part deteriorates, and defective liquid leakage easily occurs.Therefore, it is structurally very difficult to incorporate a safety function component with a current interruption function into this electrode terminal plate. Is.

Further, when the opening of the metal case and the sealing plate are welded by laser welding, the distance between the welded part and the gasket that insulates the electrode terminal plate formed through the sealing plate is reduced. This is very close to 0.5 mm to 1 mm, and there is a problem that the gasket is burned by the reflected light of the laser. Further, since the hole diameter of each component is about 1 mm, which is considerably small, there is a problem in production that a defective insertion is likely to occur when the pin of the hollow rivet is inserted or inserted.

Therefore, a method of replacing the hollow rivet with a solid rivet and caulking with a rivet,
Measures have been taken such that the gasket is made of fluororesin so that it is less likely to be burnt out by the reflected light of the laser, or the welding trajectory of the laser is released to the outside at the electrode terminal portion. However, these methods have problems such as longer processing time and higher component cost.

The present invention is intended to solve the above-mentioned problems, and by using a sealing plate provided with an excellent safety functional component that operates when overcharged or abnormally used, the sealing property and the productivity are also excellent. An object is to provide a sealed battery.

[0011]

In order to achieve the above object, a hermetically sealed battery sealing plate according to the present invention comprises an electrode terminal plate in which a gasket, an internal terminal plate, an insulating spacer, and a cap are sequentially laminated to form a part of the sealing plate. A sealing plate formed by a through hole provided in, wherein the electrode terminal plate and the sealing plate are insulated, a safety functional component is disposed between the internal terminal plate and the insulating spacer, The cap is electrically connected to the safety functional component, and the electrode terminal plate is caulked by a rib provided on the surface of the sealing plate.

The rib has a thickness of 0.1 mm to 0.5.
mm, height 0.5 mm to 3.0 mm is preferable,
This rib is formed on the surface of the sealing plate or the battery case surface which constitutes the electrode terminal plate and the electrode terminal plate of the different polarity, or because the caulking is performed around the liquid injection hole, the gasket is covered by the rib. When a metal case and a sealing plate are sealed by laser welding, the sealing plate is provided with excellent safety function parts that are not burned by laser light and easily operate when overcharged or abnormally used, and the like. By using the sealing plate, it is possible to obtain a sealed battery having excellent sealing property and productivity.

[0013]

1 is a sectional view of a sealed battery using the sealing plate of the present invention, FIG. 2 is a plan view and a sectional view of the sealing plate, FIG. 3 is a method of constructing an electrode terminal plate, and FIG. A cross-sectional view of the plate is shown in FIG.

This hermetically sealed battery is a prismatic hermetically sealed battery, in which a power generating element 7 and an electrolytic solution are housed inside a bottomed metal case 6 having an open upper part, and an opening portion of the case 6. It has a structure in which the sealing plate 1 is welded using a laser or the like and sealed and sealed.

The power generating element 7 is an element in which a positive electrode plate and a negative electrode plate are insulated via a separator, and a spirally wound electrode group is pressed into an oval shape. Applying a positive electrode active material and a binder on one side or both sides of a collector made of lathed or etched foil, a conductive agent if necessary, and a paste prepared by kneading and dispersing a plasticizer in a solvent,
It can be manufactured by drying and rolling.

As the positive electrode active material, for example, a lithium-containing transition metal compound capable of inserting and extracting lithium ions is used. For example, cobalt, manganese, nickel,
LiCoO, a composite metal oxide of lithium and at least one metal selected from chromium, iron and vanadium
₂ , LiMnO ₂ , LiNiO ₂ , LiCo _x Ni _(1-x) O ₂
(0 <x <1), LiCrO ₂ , αLiFeO ₂ , LiV
O _{2 and the} like are preferable.

Examples of the binder include a fluororesin material which maintains adhesion between active materials, a polymer material having a polyalkylene oxide skeleton, and a styrene-butadiene copolymer. As the fluorine-based resin material, polyvinylidene fluoride (PVDF), a copolymer P (VDF-) of vinylidene fluoride (VDF) and hexafluoropropylene (HFP).
HFP) is preferred.

Carbon-based conductive agents such as acetylene black, graphite and carbon fiber are preferable as the conductive agent added as required, and as the plasticizer, diisobutyl phthalate, diethyl phthalate, dibutyl phthalate, dipropyl phthalate, phthalate. Phthalates such as dihexyl acid are preferred.

As the solvent, a solvent capable of dissolving the binder is suitable. In the case of an organic binder, an organic solvent such as acetone, cyclohexanone, N-methyl-2-pyrrolidone (NMP), methyl ethyl ketone (MEK), etc. A single solvent or a mixed solvent obtained by mixing these is preferable, and water is preferable in the case of an aqueous binder.

The negative electrode plate is prepared by kneading and dispersing a negative electrode active material, a binder, and if necessary, a conductive agent and a plasticizer in a solvent on one or both sides of a current collector made of copper foil, lath-processed foil or etched foil. The paste can be applied, dried, and rolled to prepare. As the negative electrode active material, for example, a graphite material capable of inserting and extracting lithium ions, such as natural graphite or artificial graphite is used. In particular, the interplanar spacing (d) of the lattice plane (002)
It is preferable to use a graphite material having ₀₀₂ ) of 3.350 to 3.400Å.

As the binder, the solvent, and the conductive agent and the plasticizer which can be added if necessary, the same materials as those for the positive electrode plate can be used.

As the separator, polyethylene resin,
A microporous polyolefin resin such as polypropylene resin is preferred.

As a pressing method, not only the room temperature of the power generating element 7 but also a temperature of 40 ° C. to a temperature below the softening point of the binder in the power generating element is applied at a pressure of 1.0 MPa to 7.0 MPa. It is preferable to press.

Further, as shown in FIG. 2, a through hole 9 and a concave portion 8 are provided in the central portion of the sealing plate 1, and the concave portion 8 is formed.
As shown in FIG. 4, the gasket 3, the internal terminal plate 13,
Safety function component 14, insulating spacer 15, cap 12
As shown in FIG. 3, the electrode terminal plates 2 that are sequentially laminated are crimped by the crimping die 10 by the ribs 1 a of the sealing plate 1.

The electrode terminal plate 2 and the sealing plate 1 are insulated from each other, and the safety functional component 14 provided between the internal terminal plate 13 and the insulating spacer is a shape memory alloy having a current interruption function, a temperature fuse. , Preferably one selected from PTC elements.

The rib 1a has a thickness of 0.1 mm to
A range of 0.5 mm and a height of 0.5 mm to 3.0 mm is preferable. If the thickness is thinner than 0.1 mm, sufficient crimping strength cannot be secured, and if it is thicker than 0.5 mm, it is difficult to crimp and a large mold is required for crimping, which is not preferable. .

When the height is less than 0.5 mm, it is difficult to crimp and the gasket 3 is not sufficiently covered by the rib 1a, so that the metal case 6 and the sealing plate 1 are laser-welded. This is not preferable because it is burnt out by the laser light when sealing by, and when it is higher than 3.0 mm, it interferes with the cap and cannot be caulked well, and the caulking strength is reduced or varies, which is not preferable.

The rib 1a is formed on the surface of the sealing plate 1 or the surface of the metal case 6 which constitutes the electrode terminal plate 2 and the electrode terminal plate of different polarity, or around the liquid injection hole 4,
By crimping, the gasket 3 is covered by the rib 1a, and when the metal case 6 and the sealing plate 1 are sealed by laser welding, they can be easily sealed without being burned by laser light. A sealed battery having excellent sealing property and productivity can be obtained.

The ribs can be easily formed by tapping from a sealing plate or laser welding, and can be formed over the entire circumference, various slits can be formed, or a rectangular shape can be formed. In the case such as above, the same effect can be obtained even if it is provided only on two opposite sides.

Next, a non-aqueous electrolyte (not shown) is injected into the metal case 6 through the injection hole 4 of the sealing plate 1. The non-aqueous electrolytic solution includes a non-aqueous solvent and an electrolyte, and the non-aqueous solvent contains a cyclic carbonate and a chain carbonate as main components. Examples of the cyclic carbonate include ethylene carbonate (EC), propylene carbonate (PC), and butylene carbonate (BC).
It is preferably at least one selected from

As the chain carbonate, dimethyl carbonate (DMC), diethyl carbonate (DEC), and ethyl methyl carbonate (EM
It is preferably at least one selected from C) and the like.

As the electrolyte, for example, a lithium salt having a strong electron-withdrawing property is used. For example, LiPF ₆ or LiB is used.
F ₄ , LiClO ₄ , LiAsF ₆ , LiCF ₃ SO ₃ , L
iN (SO ₂ CF ₃ ) ₂ , LiN (SO ₂ C ₂ F ₅ ) ₂ , Li
C (SO ₂ CF _{3) 3} and the like. These electrolytes may be used alone or in combination of two or more. These electrolytes are preferably dissolved in the non-aqueous solvent at a concentration of 0.5 to 1.5M.

After injecting the liquid, the rib 5 provided around the injecting hole 4 is used to caulk the sealing plug 5, or the sealing plate 1 and the sealing plug 5 are laser-welded to be hermetically sealed to obtain hermeticity. A sealed battery having excellent productivity can be obtained.

In the present embodiment, the case where the liquid injection hole 4 is formed in the sealing plate 1 has been described.
May be opened in any part of the metal case 6.

[0035]

Embodiments of the present invention will be described below with reference to the drawings.

(Example 1) An example of a battery provided with a sealing plate having electrode terminals with built-in safety functional components will be described.

LiCoO ₂ as a positive electrode active material, a copolymer P (VDF-HFP) of vinylidene fluoride (VDF) and hexafluoropropylene (HFP) as a binder,
And a paste obtained by kneading and dispersing acetylene black as an electrically conductive material in an organic solvent consisting of NMP (N-methyl-2-pyrrolidone) is applied to an aluminum foil current collector having a thickness of 15 μm, dried and rolled to form a positive electrode plate. It was made.

Graphitizable carbon as the negative electrode active material, P
A paste prepared by kneading and dispersing (VDF-HFP) powder in a mixed organic solvent composed of acetone and cyclohexanone was applied to a copper foil current collector having a thickness of 12 μm, dried, and rolled to prepare a negative electrode plate.

The positive electrode plate and the negative electrode plate thus produced were spirally wound with a 25 μm thick separator made of a polyethylene resin having a microporous structure, and a power generating element 7 of 6.0 M was formed.
It was pressed at a pressure of Pa to form an elliptical shape, and was housed inside the metal case 6.

Then, as shown in FIGS. 2 (A) and 2 (B), the central portion of the sealing plate 1 has a width of 5.4 mm and a length of 33.
It is made of an aluminum alloy having a thickness of 4 mm and a thickness of 1.0 mm, and a through hole 9 for forming an electrode terminal having a diameter of 2.0 mm and a recess 8 having a diameter of 2.5 mm and a depth of 0.6 mm are provided in the central portion of the recess 8. Thickness 0.1mm, height 0.5mm all around
The rib 1a of No. 1 was provided by tapping.

Next, as shown in FIG. 4, a safety functional component 14 composed of a polypropylene resin gasket 3, an internal terminal plate 13, and a shape memory alloy plate is formed so as to cover the recess 8 and the through hole 9 of the sealing plate 1. As shown in FIG. 3, the electrode terminal plate 2 constituted by sequentially laminating the insulating spacer 15 and the cap 12 crimped the rib 1 a of the sealing plate 1 using the crimping die 10.

The safety function component 14 made of the shape memory alloy plate and the cap 12 are electrically connected to each other by the central protrusion 14a of the safety function component 14, and the safety function component 14 is It has a current interrupting function of deforming at a temperature of 105 ° C. or higher to interrupt the electrical connection with the cap 12.

The sealing plate 1 and the metal case 6 are welded and sealed by laser welding to have a thickness of 6.3 mm and a width of 3 mm.
4mm, height 50mm, battery capacity 850mAh
A prismatic closed type battery was manufactured.

(Example 2) An example of a battery provided with a sealing plate having an electrode terminal plate 2 and an electrode terminal plate of a different polarity will be described.

FIG. 5 shows an electrode terminal plate 2 similar to that of the first embodiment.
FIG. 3 is a cross-sectional view in which an electrode terminal plate 21 having a different polarity from this electrode terminal plate is provided on the sealing plate 1 after manufacturing the above.

As shown in FIG. 5, the central portion of the sealing plate 1 has a width of 5.4 mm, a length of 33.4 mm and a thickness of 1.2 mm.
Made of aluminum alloy of 3.0mm diameter in the center
Through-holes (not shown) for configuring the electrode terminals of and a width of 3.8 m
m, length 4.5 mm, depth 0.7 mm provided with a recess (not shown), further having slits at four locations around the recess width 3.6 mm, length 4.3 mm, thickness 0.5 mm, height A rib 1a having a thickness of 1.0 mm was provided by laser welding.

Next, a polypropylene resin gasket 3, an internal terminal board, a safety functional component (set operating temperature 115 ° C.) consisting of a thermal fuse, an insulating spacer and a cap are provided so as to cover the recess and the through hole of the sealing plate 1. The electrode terminal plate 2 formed by sequentially laminating was crimped with the rib 1 a of the sealing plate 1.

Next, a recess (not shown) having a diameter of 4.0 mm and a depth of 0.6 mm is provided in a part on the right side from the central portion of the sealing plate 1, and the periphery thereof has a thickness of 0.5 mm and a height of 0. .5m
The rib 1b of m is provided by laser welding, and the safety function component (set operating temperature 105
C.) 14, a polyethylene resin gasket 17, and a cap 12 are laminated in this order to crimp the heteropolar electrode terminal plate 16 with the rib 1b of the sealing plate 1.

Then, Example 1 was carried out except that the sealing plate 1 and the metal case 6 were laser-welded to perform the welding sealing.
A prismatic sealed battery was manufactured in the same manner as in.

By the way, there are two types of safety function parts having this structure, a safety function part composed of a thermal fuse and a safety function part composed of a shape memory alloy plate and having a current interruption function. Sometimes, it's a backup if it doesn't work.

When using two kinds of safety functional parts, it is preferable to use one or two kinds having different operating conditions selected from shape memory alloy, thermal fuse and PTC element.

(Embodiment 3) An embodiment in which a heteropolar terminal plate is provided in a metal case instead of the sealing plate of the embodiment 2 will be described.

In FIG. 6, the bottom of the metal case 6 has a 1
A square recess (not shown) having a side length of 4.0 mm and a depth of 0.2 mm is provided, and only the two opposing sides of the square recess are punched out with a rib 1c having a thickness of 0.1 mm and a height of 3.0 mm. A metal case is provided with a heteropolar terminal plate 16 which is provided by sequentially laminating a safety function component (set operating temperature 105 ° C.) 14 made of a shape memory alloy plate, a polypropylene resin gasket 17, and a cap 12 in the recess. 6
A sealed prismatic battery was produced in the same manner as in Example 1 except that the rib 1c was used.

(Embodiment 4) An embodiment in which the electrode terminal plate 2 and the liquid injection hole are provided in the sealing plate will be described.

In FIG. 7, a liquid injection hole 4 having a diameter of 1.5 mm and a concave portion (not shown) having a diameter of 2.0 mm and a depth of 0.6 mm provided in a part of the sealing plate 1 are provided, and a surrounding area 3 A rib 1d having a thickness of 0.2 mm and a height of 1.5 mm having a slit of 0.1 mm is provided by laser welding, and the sealing plate 1 is provided with a polypropylene resin gasket 18 and a sealing plug 5 sequentially stacked in the recess. A rectangular sealed battery was produced in the same manner as in Example 1 except that the ribs 1d were crimped.

(Comparative Examples 1 to 4) Example 1 except that the following combinations of rib thickness and height were used.
A rectangular sealed battery was produced in the same manner as in.

In the case of Comparative Example 1, the rib thickness is 0.08 m.
m, the height is 2.8 mm, in the case of Comparative Example 2, the rib thickness is 0.2 mm, the height is 0.4 mm, and in the case of Comparative Example 3,
Rib thickness 0.7 mm, height 1.0 mm, Comparative Example 4
In case of, rib thickness is 0.2mm and height is 3.5mm
I used the one.

In this way, a storage test was carried out using 20 prismatic sealed batteries prepared in Examples 1 to 4 and Comparative Examples 1 to 4. Storage test is 60 ℃
The results of visually observing the number of leaked liquids after standing for 4 weeks in 90% RH are shown in (Table 1).

[0059]

[Table 1]

As is clear from Table 1, the battery of the present invention is superior to the battery of the comparative example in liquid leakage resistance after storage.

In the case of Comparative Example 1, the rib thickness is 0.08 m.
Since the required compressive strength could not be ensured due to the small thickness of m, in the case of Comparative Example 2, the rib height was lower than 0.5 mm, so that it was difficult to crimp and the gasket 3 was sufficiently rib 1a. Since the metal case 6 and the sealing plate 1 are sealed by laser welding, it is considered that the metal case 6 and the sealing plate 1 were burned by the laser light and leaked from the portion.

In the case of Comparative Example 3, the rib thickness is 0.7 mm.
Because it was thick, I could not crimp well,
In the case of Comparative Example 4, since the rib height is as high as 3.5 mm, it is considered that the tip portion of the rib interfered with the cap and the caulking strength was reduced, so that liquid leakage occurred.

[0063]

As described above, by forming ribs on the sealing plate, the electrode terminal plate structure can be simplified and the safety functional component can be formed, as compared with the case where the electrode terminal plate is constructed by using the conventional rivets. It is possible to easily manufacture a sealing plate having a built-in.

Further, by using this technique, it is possible to provide a highly reliable technique for sealing the injection hole. Then, by using this sealing plate, a high-performance sealed battery can be supplied at low cost, and its industrial value is very large.

[Brief description of drawings]

FIG. 1 is a sectional view of a main part of a sealing plate portion of a sealed battery of the present invention.

FIG. 2A is a plan view of a rib portion of the sealing plate of the present invention. (B) Cross-sectional view of the rib portion of the sealing plate

FIG. 3 is a structural cross-sectional view showing a state when the electrode terminal plate of the present invention is manufactured.

FIG. 4 is a sectional view of an essential part of the sealing plate of the present invention.

FIG. 5 is a sectional view of another sealing plate of the present invention.

FIG. 6 is a sectional view of a main part of a sealing plate portion of another sealed battery according to the present invention.

FIG. 7 is a sectional view of another sealing plate of the present invention.

FIG. 8 is a sectional view of a main part of a sealing plate portion of a conventional sealed battery.

[Explanation of symbols]

1 Seal plate 1a, 1b, 1c, 1d ribs 2 electrode terminal board 3, 17, 18 Gasket 4 Injection hole 5 plugs 6 metal cases 7 power generation elements 8 recess 9 through holes 10 caulking die 12 caps 13 Internal terminal board 14 Safety function parts 14a protrusion 15 Insulation spacer 16 Different polarity terminal board 20 hollow rivets 21 Internal gasket

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) H01M 10/40 H01M 10/40 Z (72) Inventor Kaneto Masumoto 1006 Kadoma, Kadoma, Osaka Prefecture Matsushita Electric Sangyo Co., Ltd. F-term (reference) 5H011 AA09 AA13 CC02 CC06 CC08 DD05 DD07 DD13 DD15 EE04 FF02 FF04 GG01 GG02 HH00 HH02 JJ11 KK01 5H012 AA07 BB02 BB03 DD01 FF01 QC01 CC01 CC01 CC02 CC01 CC01 CC01 CC01 CC01 CC01 AM03 AM05 AM07 BJ27 CJ03 DJ02 DJ03 DJ05 EJ01 HJ04

Claims (7)

[Claims] 1. A sealing plate in which an electrode terminal plate in which a gasket, an internal terminal plate, an insulating spacer, and a cap are sequentially laminated is formed by a through hole provided in a part of the sealing plate, wherein the electrode terminal. The plate and the sealing plate are insulated, the safety functional component is disposed between the internal terminal plate and the insulating spacer, the cap and the safety functional component are electrically connected, and are provided on the surface of the sealing plate. A sealing plate for a sealed battery, wherein the electrode terminal plate is crimped by a rib. 2. The sealing plate for a sealed battery according to claim 1, wherein the electrode terminal plate and the electrode terminal plate having a different polarity are caulked by ribs provided on the surface of the sealing plate. 3. The hermetically sealed battery sealing plate according to claim 1, wherein the electrode terminal plate and the electrode terminal plate having a different polarity are crimped by ribs provided on the battery case. 4. The liquid injection hole is closed by caulking a plug with a rib provided around the liquid injection hole provided in the sealing plate.
Sealing plate for the sealed battery described. 5. The rib has a thickness of 0.1 mm to
The sealed plate for a sealed battery according to any one of claims 1 to 4, wherein the sealed plate has a height of 0.5 mm and a height of 0.5 mm to 3.0 mm. 6. The electrode terminal board according to claim 1, wherein the safety functional component is an electrode terminal plate using one kind selected from a shape memory alloy having a current interruption function, a thermal fuse, and a PTC element. A sealing plate for a sealed battery according to any one of 1. 7. A positive electrode plate and a negative electrode plate are insulated via a separator, and a power generating element and an electrolytic solution are housed in a bottomed metal case having an opening at the top, and an opening is provided in the case. A sealed battery, wherein the sealing plate according to any one of claims 1 to 6 is welded and sealed.