JP2000048853A - Winding core of winding material for rectangular battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To thin a core part without deteriorating the rigidity of the core part of a winding core, as well as to improve bending rigidity of the winding core for obtaining a winding material for a rectangular battery. SOLUTION: This winding core 21 is composed of a pair of core materials 22, 22, each core material 22 has formed into an approximately rectangular- shaped section having long sides and short sides, surfaces 24a on the short sides are faced to each other to constitute the winding core, and the facing surfaces 24a on the short sides are formed into pinching surfaces for pinching the end of a separator 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a winding core for a wound product for a prismatic battery.

[0002]

2. Description of the Related Art FIG. 5 shows an example of a power generating element of a prismatic battery. In FIG. 1, reference numeral 2 denotes a positive electrode, 3 denotes a negative electrode, and 4 denotes a separator. The positive electrode 2 and the negative electrode 3 are separated and wound by the separator 4. Li
In the case of an ion secondary battery, as shown in FIG.
Is a positive electrode current collector 2 made of, for example, a strip-shaped aluminum foil.
The negative electrode 3 is formed by applying lithium cobalt oxide as the positive electrode active materials 2b, 2b on both sides of the negative electrode current collector 3a.
3b is formed by applying graphite. At one end of the positive electrode 2, an uncoated portion 2c in which the positive electrode active material 2b is not applied to the positive electrode current collector 2a is provided, and the positive electrode tab lead 5 is welded thereto. Similarly, at one end of the negative electrode 3, a non-coated portion 3c in which the negative electrode active material 3b is not applied to the negative electrode current collector 3a is provided, and the negative electrode tab lead 6 is welded thereto. The separator is a porous synthetic resin film that insulates the electrodes 2 and 3 from each other and allows ions to move between the electrodes in a non-aqueous electrolyte. Such a roll is inserted into an outer can (battery can).

FIGS. 7 to 9 show a winding core 11 for obtaining the above-mentioned wound material. The wound core 11 is composed of a pair of core materials 12. The core 12 includes a base 13 and a core 14 protruding from the base 13. Core 14
Has a substantially rectangular cross section having a long side and a short side, in other words, a flat plate.

In use, the two core members 12, 12 are advanced in a direction in which the core portions protrude from each other, and the overlapped ends of the separators 4, 4 are brought into contact with the long sides of the core portions 14, 14. The ends of the cores are inserted into the core receivers 15 on the other side and fixed. Then, the positive electrode 2 and the negative electrode 3 are arranged on the front side and the back side of one separator 4 so as not to short-circuit each other, and by rotating both core members 12, 12, the separators 4, 4 and both electrodes are rotated. The wound product of the prismatic battery is formed by winding a few pieces.

[0005]

When the winding core 11 is removed from the above-mentioned wound material, the trace becomes a void. The wound product is inserted into the outer can while being sandwiched from both sides so that the gap is crushed, and the gap is preferably narrow. It is for the following reasons.

The positive electrode 2 and the negative electrode 3 are bent at both edges of the gap, but when the gap is wide,
When the gap is crushed across the wound material, a large load is applied to the bent portion. When the gap is narrow, the winding amount of the innermost peripheral portion of the separator can be reduced. When the gap is narrow, loosening of the winding is reduced, and the distance between the positive and negative electrodes is stabilized.

However, if the thickness of the winding core is reduced to narrow the gap, the rigidity of the winding core is reduced correspondingly, which causes a problem of bending and breakage of the winding core.

An object of the present invention is to increase the rigidity of a winding core or to reduce the gap without reducing the rigidity of the winding core.

[0009]

The present invention solves such a problem by disposing a pair of core members constituting the winding core differently from the conventional one.

That is, the present invention comprises a pair of core materials, and the two core materials are aligned and sandwiched between the two band-shaped separators with their respective ends overlapped, and a band-shaped positive electrode and a band-shaped negative electrode are sandwiched therebetween. The electrodes and the separator are arranged on the front side and the back side of one separator so as not to short-circuit each other, and by rotating the aligned core material, the separator and the electrodes are wound to form a wound product of the prismatic battery. A wound core of a wound battery for a rectangular battery that is formed, wherein each of the pair of core materials is formed in a substantially rectangular shape having a cross section having a long side portion and a short side portion. Are arranged so that the short sides thereof face each other so as to face each other to form a winding core, and the facing short sides are formed on a sandwiching surface sandwiching the ends of the separators.

With such a wound core, the bending rigidity when a force is applied in the thickness direction of the core material is smaller than that of a conventional wound core in which the long sides of the core material face each other. If they are the same, they are doubled. This means that if the same bending rigidity is obtained, the total thickness of the winding core is made thinner than it is, that is, the above-mentioned gap can be reduced.

Each of the two core members includes a base and a core protruding from the base and having a substantially rectangular cross section having a long side and a short side. It is preferable that a core receiver into which the tip of the core part of the mating core material is inserted is opened on the part projecting surface. This eliminates the need to separately provide a wound core receiver.

[0013]

Therefore, according to the present invention, the wound core of the wound product for a prismatic battery is constituted by a pair of cores, and each of the cores has a long side and a short side in cross section. And so as to form a winding core so that the surfaces on the short sides of each other are aligned so as to face each other to form a winding core, so that the end of the separator is sandwiched by the surfaces on the short sides facing each other. Compared to conventional wound cores where the long sides of the core material face each other,
It is possible to increase the bending rigidity to increase the durability of the wound core, or reduce the gap of the wound material without lowering the bending rigidity, and reduce the load on the electrode when inserting the wound material into the outer can. It is possible to reduce the size, to reduce the winding slack and to stabilize the charge / discharge amount, or to reduce the innermost winding amount of the separator to increase the electrode length and increase the charge / discharge amount.

[0014]

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

As shown in FIGS. 1 and 2, the winding core 21 of the rectangular battery winding according to the present invention comprises a pair of core members 22 and 2.
2. The core members 22 and 22 have the same shape as each other, and include a rectangular parallelepiped base 23 and a core 24 protruding from the base 23. The core 24 has a substantially rectangular cross section having a long side and a short side. On the protruding surface of the core portion of the base portion 23, a core receiver 25 having a substantially rectangular cross-section into which the tip of the core portion of the mating core material 22 is inserted at a portion adjacent to the short side of the core portion 24.

That is, the wound core 21 is constituted by a pair of core materials 22, 22 facing each other in a core projecting direction, and inserting the respective core portions 24 into the core receiver 25 of the mating core material 22. As shown in FIG. 3, the cores 24, 24 are aligned so that the short sides 24a, 24a face each other. Therefore, the facing short sides 24a, 24a serve as sandwiching surfaces for sandwiching the end of the separator 4 of the wound product (power generation element) of the prismatic battery.

In use, two separators 4, 4
The two core members 22, 22 are opposed to each other with the overlapped end portions therebetween, and the two core members 22, 22 are advanced toward each other. The separators 4, 4 are sandwiched between the short sides 24a, 24a of the cores 24, 24 by being inserted into the receivers 25, 25.
Then, the positive electrode and the negative electrode are arranged on the front side and the back side of one of the separators 4, and the wound core 21 is rotated to wind up both the electrodes and the separator to obtain a wound product. After the wound core 21 has been removed,
It is inserted into the outer can.

(Regarding the bending rigidity of the winding core) Here, the bending rigidity of the winding core 21 according to the present invention and the conventional winding core 11 will be compared.

FIG. 4 is a drawing in which the cross-sectional shape of the core of the wound core 21 according to the present invention is compared with the cross-sectional shape of the core of the conventional wound core 11. Assuming that the width of one core 14 of the conventional wound core 11 is b ₀ and the height (thickness) is h ₀ , the secondary moment of area I ₀ is as follows.

[0020] On the contrary ^{_{I 0 = b 0 h 0 3}} /12, when the seeded core 21 according to the present invention, the core unit the total cross-sectional area (the sum of the cross-sectional area of the two core) the same as the conventional example Then, the width b ₁ of the one core portion 24 is b _0/2 , and the height h ₁
Is 2h ₀ . Therefore, the second moment of area I ₁
Is as follows.

[0021] ^{_{I 1 = b 1 h 1 3}} /12 = (b 0/2) (2h 0) 3/12 = b 0 h 0 3/3 = 4I 0 Therefore, one of the core portion of the flexural rigidity EI (E Is Young's modulus, I
Is the second moment of area) of the winding core 21 according to the present invention is four times that of the conventional example. However, in the case of the conventional winding core 11, since the two core portions 14 overlap, the bending rigidity of the winding core 21 according to the present invention is doubled as compared with the conventional example.

In the wound core 21 according to the present invention,
Core height h ₁ which can obtain the same bending rigidity as Maki core 11 prior becomes approximately 1.6 times that of h _0, core total cross-sectional area S ₁ is _{S 1 = 2 × 1.6h 0 ×} (b _0/2 ). This corresponds to 80% of the total core cross-sectional area S ₀ = 2 × h ₀ × b ₀ of the conventional wound core 11. That is, the void generated when the winding core 21 is removed from the wound material is reduced to 80% of the conventional one.

Therefore, according to the present invention, it is possible to increase the bending stiffness of the winding core 21 as compared with the related art, or to reduce the gap of the wound material without lowering the bending stiffness.

[Brief description of the drawings]

FIG. 1 is a front view of a wound core according to the present invention.

FIG. 2 is a side view of the wound core.

FIG. 3 is a cross-sectional view of the wound core.

FIG. 4 is a cross-sectional view showing a winding core according to the present invention and a conventional winding core in comparison.

FIG. 5 is a plan view showing a wound product of a prismatic battery.

FIG. 6 is a sectional view showing positive and negative electrodes and a separator.

FIG. 7 is a front view of a conventional winding core.

FIG. 8 is a side view of the wound core.

FIG. 9 is a cross-sectional view of the wound core.

[Explanation of symbols]

 2 Positive electrode 3 Negative electrode 4 Separator 5 Positive tab lead 6 Negative tab lead 21 Wound core 22 Core material 23 Base 24 Core portion 24a Short side surface 25 Core receiver

Claims (2)

[Claims] 1. A belt-shaped positive electrode and a band-shaped negative electrode are made of a pair of cores, and the two cores are aligned and sandwiched between the two band-shaped separators with their respective ends overlapped. Arranged on the front side and the back side of one separator so as not to cause a short circuit, and by rotating the aligned core materials, the separator and the electrodes are wound to form a wound product of a prismatic battery. A wound core of a wound battery for a rectangular battery, wherein each of the pair of core members is formed in a substantially rectangular shape having a cross-sectional shape having a long side portion and a short side portion. Are wound so as to face each other to form a winding core, and the facing short side surface is formed on a sandwiching surface sandwiching the ends of the separators, wherein the wound material for a rectangular battery is Winding core. 2. The wound core for a wound product for a prismatic battery according to claim 1, wherein each of the core materials has a base and a cross-sectional shape protruding from the base and having a long side and a short side. And a core portion formed into a substantially rectangular shape having a core portion, and a core receiver into which a core end of a mating core material is inserted is opened on a core projecting surface of each base portion. Wound core for wound products for prismatic batteries.