JP3302200B2 - Sealed rectangular non-aqueous electrolyte battery - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sealed rectangular nonaqueous electrolyte battery.

[0002]

2. Description of the Related Art In recent years, with the development of electronic equipment, there has been a demand for the development of a secondary battery using a non-aqueous electrolyte that is small, lightweight, has a high energy density, and can be repeatedly charged and discharged. As a secondary battery of this type, a battery using lithium or a lithium alloy as a negative electrode active material and using an oxide, sulfide, or selenide such as molybdenum, vanadium, titanium, or niobium as a positive electrode active material is known. .
Recently, lithium ion secondary batteries using carbon as a negative electrode active material and lithium cobalt oxide or lithium manganese oxide as a positive electrode active material have been actively developed and commercialized.

[0003] Most of such battery systems were initially developed mainly in coin or cylindrical shapes, but with the diversification of applications, the demand for batteries having excellent volumetric efficiency, such as rectangular or oval, has increased. ing.

Conventionally, the following method has been mainly used for sealing a battery having a straight portion such as an oval. One is a crimp sealing after bead processing which is generally used for a sealing method of a cylindrical battery (see FIG. 5).
This holds the inside of the outer can 1 with the upper die of the bead processing machine,
A groove having a depth of 1 mm or more, that is, a pedestal 12 for holding the sealing lid group 3 is formed by applying a grooving roller while pressing the outer can 1 from below, and the sealing lid group 3 is inserted into the can. The opening was bent 13 inward. The other is sealing with a laser. In this case, a sealing lid in which one terminal is insulated with glass hermetic is placed on the opening of the outer can and the peripheral portion is sealed by laser welding.

[0005]

However, when the above-mentioned sealing structure is used, there are the following problems. First, in the case of crimp sealing after bead processing, dents appear in the holding member from the inside after the processing, that is, in the straight portion 14 under the groove of the outer can, which is a portion where the upper die does not hit,
Pressing the internal electrode group caused an internal short circuit due to separator breakage, and processing distortion appeared in the straight part on the groove, making it difficult to maintain a certain clearance between the outer can and the sealing lid group, crimping Pressure applied to the can due to dimensional change of the coil during charging and discharging after sealing, high temperature storage state,
An internal pressure rise due to gasification of the electrolyte at the time of abnormality such as overcharge, overdischarge, or short circuit caused a liquid leakage failure. Further, when the groove was made shallow to suppress such distortion of the can, the sealing lid group 3 sunk into the can at the time of crimping, and similarly, a liquid leakage defect occurred. On the other hand, although the sealing method using a laser is very excellent in sealing property, it is very expensive in terms of parts cost and production cost such as processing of a glass hermetic on a lid and introduction of a laser welding machine.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a prismatic battery that does not affect the internal electrode group 2 and that is not affected by the dimensional change of the coil during charging and discharging. An object of the present invention is to provide an inexpensive sealing structure capable of withstanding an increase in internal pressure due to gasification of an electrolytic solution at the time of abnormality such as swelling of a can, overcharging, overdischarging, or short circuit.

[0007]

SUMMARY OF THE INVENTION The present invention is directed to a closure having a wound electrode group 2 comprising a positive electrode, a separator and a negative electrode, an outer can 1 for accommodating them, and a valve mechanism 4 for releasing pressure when the internal pressure of the battery rises. A lid group 3; the sealing lid group 3 is bent outward and inward at an upper end portion and a lower end portion to form a pedestal; further, a thin portion is provided on a side surface of the inner pedestal; A packing 9 that forms an intermediate pedestal by having a pressure valve in a central hole, a holding plate 7 having projections at upper and lower ends, and an inner cap 8 that covers the outer periphery and bottom surface of the holding plate; In the elliptical nonaqueous electrolyte battery composed of the overcurrent heating protection element 6 and the terminal plate 5, the sealing lid group 3 is held by the outer pedestal portion of the packing 9 at the outer can opening and is present. Keep can 1 and packing 9 Projecting portion of the plate 7, i.e. the width 1mm from the outside between the thick portion of the packing 9, depth 0.5mm
By drawing inward to the inside, a first sealing process 10 is performed, and the openings of the outer can 1 and the packing 9 are further formed by the upper protruding portion of the holding plate 7, the overcurrent overheat protection element 6, and the terminal plate 5.
Is a sealed rectangular non-aqueous electrolyte battery having a second sealing process 11 by being bent inward at around.

[0008]

1 and 2, an embodiment of the present invention will be described.

First, as a power generating element, a conductive material and a binder are added to a lithium-manganese composite oxide LiMn ₂ O ₄ for a positive electrode, and the resultant is coated and dried on an aluminum substrate to form a sheet. After being pressure-bonded to the substrate, wound with a polypropylene porous film interposed therebetween as a separator, and then pressure-formed to form an elliptical electrode group 2, housed in an outer can 1, and One of the protruding lead wires was welded to the outer can 1. Next, a mixed solvent of propylene carbonate and diethyl carbonate (volume ratio: 50:50) in which lithium hexafluorophosphate (LiPF ₆ ) was dissolved as an electrolyte was used as an electrolyte, and the solution was poured into the outer can 1. Next, the sealing lid group 3 having the valve mechanism 4 for releasing the pressure when the battery internal pressure rises is bent outward and inward at the upper end and the lower end, respectively, to form the pedestal 12, and further form the pedestal 12. A packing plate 9 having a thin portion on the side surface and a projection forming an intermediate pedestal is provided with a pressure valve in a central hole, and a holding plate 7 having projections at upper and lower ends, respectively, and an outer periphery other than the upper projection. Then, the lid integrated with the inner cap 8 covering the bottom face was fitted, and was welded to the other lead wire coming out of the electrode group 2. Further, the overcurrent heating protection element 6 and the terminal plate 5 were mounted on the lid, and the sealing lid group 3 was held at the outer can opening at the outer base of the packing 9. Here, the outer can 1 and the packing 9 are separated from the outside by a width 1 between the projecting portions of the holding plate 7, that is, between the thick portions of the packing.
mm and a depth of 0.5 mm to form a first sealing process 10, and furthermore, the opening of the outer can and the packing is formed by the upper protruding portion of the reinforcing plate, the overcurrent overheat protection element 6 and the terminal plate 5. By bending around the inside, 100 sealed rectangular nonaqueous electrolyte batteries having a length of 10 mm, a width of 40 mm, a height of 50 mm, and a capacity of 1,500 mAh were produced as the second sealing process 11.

Comparative Example 1 A sealed rectangular non-aqueous electrolyte was prepared in the same manner as in the embodiment, except that the protective plate 7 had no upper projection and the packing 9 had a structure in which the projection was buried. 100 batteries were produced. (See Fig. 3)

Comparative Example 2 A sealed rectangular non-aqueous electrolyte was prepared in the same manner as in the embodiment, except that the holding plate 7 had no lower projection and the packing 9 had a structure in which the projection was buried. One hundred batteries were produced (see FIG. 4).

(Conventional example) An outer can 1 is placed on an upper die of a bead processing machine.
After applying a grooving roller to the outer can 1 while applying pressure from below, a groove having a depth of 1.3 mm, that is, a pedestal 12 holding the sealing lid group 3, is formed. 3 was inserted, and the can opening was crimped 13 to produce 100 sealed rectangular nonaqueous electrolyte batteries (see FIG. 5).

For each of these batteries, the results of an investigation of the number of internal short-circuits after assembling and an investigation of the number of leaks after 5D, 10D, and 20D by a 60 ° C. high-temperature storage test are shown in Tables 1 and 2, respectively. Shown in

[0014]

[Table 1]

[0015]

[Table 2]

According to the embodiment, the lower protruding portion of the holding plate 7 suppresses the occurrence of dents in the straight portion below the groove of the outer can, and the upper protruding portion plays a role in suppressing the processing distortion of the straight portion above the groove. It was possible to provide a sealed rectangular nonaqueous electrolyte battery having excellent sealing properties without occurrence of internal short circuit after sealing. However, the holding plate 7 as in Comparative Example 1
When a material having no upper protrusion is used, processing distortion appears in the straight portion on the groove, making it difficult to maintain a constant clearance between the outer can 1 and the sealing lid group 3, and storing at 45 ° C. high temperature after sealing. In the test, a liquid leakage failure occurred due to an increase in internal pressure due to gasification of the electrolytic solution. Further, when a holding plate 7 having no lower protrusion is used as in Comparative Example 2, a dent 14 appears in a straight portion under the groove of the outer can 1 and presses the internal electrode group to prevent an internal short circuit due to separator breakage. Occurred.

From these results, the batteries of the examples do not cause liquid leakage or internal short circuit in any of the tests, but the comparative example and the conventional example have structural defects that cause liquid leakage or internal short circuit.

[0018]

According to the present invention, the sealing process for the outer can 1 is very loose compared with the conventional bead forming method, so that not only the occurrence of distortion of the can after processing is small but also Further, the lower protruding portion of the holding plate suppresses the occurrence of dents in the straight portion below the groove of the outer can, and the upper protruding portion serves to reduce processing distortion of the straight portion above the groove. Finally, the outer can 1 and the packing 9 are formed. The opening is bent inward around the upper protruding portion of the holding plate 7, the overcurrent overheat protection element 6 and the terminal plate 5, so that an internal short circuit does not occur, the sealing property is excellent, and the sealed rectangular nonaqueous electrolytic solution is excellent. A liquid battery can be provided.

[Brief description of the drawings]

FIG. 1 shows a cross-sectional view of a battery of an example.

2A is a sectional view of the battery sealing structure of the embodiment, b: a sectional view of the holding plate 7, and c: a sectional view of the packing 9. FIG.

3A is a sectional view of the battery sealing structure of Comparative Example 1, b is a sectional view of the holding plate 7, and c is a sectional view of the packing 9. FIG.

4A is a cross-sectional view of the battery sealing structure of Comparative Example 2, b is a cross-sectional view of a holding plate, and c is a cross-sectional view of a packing 9. FIG.

FIG. 5 is a cross-sectional view of a conventional battery sealing structure.

[Explanation of symbols]

 1: exterior can 2: electrode group 3: sealing lid group 4: valve mechanism 5: terminal plate 6: overcurrent heating protection element 7: protection plate 8: inner cap 9: packing 10: first sealing process 11: second Sealing process 12: Pedestal

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-2-297860 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01M 10/40 H01M 2/02 H01M 2 / 08

Claims (1)

(57) [Claims] 1. A sealing body group comprising: a wound electrode group consisting of a positive electrode, a separator and a negative electrode; an outer can for accommodating them; and a sealing lid group having a valve mechanism for releasing pressure when the internal pressure of the battery rises. Packing forming an intermediate pedestal by forming a pedestal bent outward and inward at the upper end and lower end, respectively, further having a thin portion on the side surface of the inner pedestal, and having a protruding portion at the center. A sealing plate comprising a holding plate having a pressure valve disposed in a central hole and having projections at upper and lower ends, an inner cap covering the outer periphery and the bottom surface of the holding plate, an overcurrent heating protection element and a terminal plate. In the prismatic non-aqueous electrolyte battery, the sealing lid group is present at the outer can opening at the outer pedestal portion of the packing, and the outer can and the packing are protruded from the holding plate, that is, the thick portion of the packing. of The first sealing process is performed by drawing from the outside between them, and the opening of the outer can and the packing is further bent inward around the upper projecting portion of the holding plate, the overcurrent overheat protection element, and the terminal plate. A sealed non-aqueous electrolyte battery with a second sealing process.