JP2000243428A - Laminated electrode structure and secondary battery using same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent short-circuiting caused by a contact between a positive electrode member and a negative electrode member by maintaining or enhancing an electric capacity per predetermined volume. SOLUTION: This laminated electrode structure is constituted by laminating a positive electrode member 2 comprising positive electrode leads 8 at one side edge of a positive electrode foil having an active material layer 6 formed thereon, a negative electrode member 3 comprising negative electrode leads 10 at one side edge of a negative electrode foil 9, and a separator 4 interposed between the positive electrode member 2 and the negative electrode member 3. The positive electrode member 2 and the negative electrode member 3 are laminated in sequence in such a manner that the side edges provided with the positive electrode leads 8 and the negative electrode leads 10 formed thereon are located on sides opposite to each other. A lug 7 is provided, in which the positive electrode foil is exposed in a predetermined width along one side edge having the positive electrode leads 8 of the positive electrode member 2 formed thereon. The lug 7 is laminated in such a manner as to be located outside beyond the side edge of the negative electrode member 3 facing the end edge of the lug 7.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laminated electrode structure in which a positive electrode material and a negative electrode material are alternately laminated or wound, and a lithium ion secondary battery or the like using the laminated electrode structure as a power generating element. Related to secondary batteries.

[0002]

2. Description of the Related Art In a secondary battery such as a lithium ion secondary battery, a laminated electrode structure, for example, a positive electrode material 51 and a negative electrode material 52 shown in FIG. The jelly roll element 50 is housed in a container such as an outer case.

As shown in FIGS. 5 and 6, a positive electrode material 51 is formed of a positive electrode active material layer 55 in which a positive electrode mixture containing a positive electrode active material as one component is applied to both surfaces of a strip-shaped positive electrode foil 54 made of aluminum foil. Are formed. In addition, the positive electrode material 51 includes:
A plurality of positive electrode leads 56 formed by stamping one side edge of the positive electrode foil 54 are provided. In the positive electrode material 51, the positive electrode active material layer 55 is applied and formed on a portion other than the above-described positive electrode lead 56, that is, on the entire range of the positive electrode foil 54.

The negative electrode material 52 is provided with a negative electrode foil 57 made of copper foil (not shown in detail). Like the positive electrode material 51, a negative electrode lead formed by punching one side edge of the negative electrode foil 57 is formed. 58 are provided.

In the jellyroll element 50 having the above-described structure, the width of the positive electrode material 51 is smaller than that of the negative electrode material 52 in order to suppress variations in battery characteristics. The jelly roll element 50 is such that the entirety of the narrow positive electrode material 51 fits within the width dimension of the negative electrode material 52 and the positive electrode lead 5
The positive electrode material 51 and the negative electrode material 52 are overlapped with a separator 53 interposed therebetween so that the negative electrode lead 6 and the negative electrode lead 58 protrude from side portions in different width directions, respectively, and are wound.

[0006] Secondary batteries such as lithium ion secondary batteries,
The positive electrode lead 56 and the negative electrode lead 58 protruding from both sides of the jelly roll element 50 are each folded in the axial direction and housed in a container such as an outer case as described above.

[0007]

SUMMARY OF THE INVENTION Jellyroll element 5
Since the positive electrode material 51 is overlapped so as to fit within the width of the negative electrode material 52 as described above, the negative electrode material having a width wider than the positive electrode material 51 when these are wound in a stacked state. The cathode lead 56 protrudes from between the anode material 52 and the anode material 52. In the jelly roll element 50, when it is stored in a container such as an outer case body, it is folded as shown in FIG. 7A, but the positive electrode lead 56 is pressed in the direction of the arrow and contacts the adjacent negative electrode foil 57. There are cases.

In the jelly roll element 50, as shown in FIG. 1B, when the positive electrode lead 56 is formed in a direction perpendicular to the winding axis when housed in a container such as an outer case body, The positive electrode lead 56 bent and pressed from the inside of the negative electrode foil 57 may break the thin separator 53 and come into contact with the negative electrode material 57.

Further, in the positive electrode lead 56, the positive electrode foil 55 is formed by punching as described above, and a punch burr 59 may be generated at the peripheral portion of the positive electrode lead 56. As shown in FIG. 4C, when the punch burr 59 is generated in a direction in which the positive electrode material 51 is folded, that is, in a manner that the positive electrode lead 56 protrudes, as shown in FIG. Separator 53
May come in contact with the negative electrode material 52.

In a secondary battery such as a lithium ion secondary battery, there is a problem that a short circuit occurs due to the contact of the positive electrode lead 56 provided on the positive electrode material 51 with the negative electrode material 53 as described above. ing. In the jelly roll element 50, in order to solve the above-mentioned problem, a method of increasing the thickness of the separator 53 interposed between the positive electrode material 51 and the negative electrode material 52 is considered. However, a secondary battery such as a lithium ion secondary battery has a problem in that the electric capacity per fixed volume is reduced by using the thick separator 53 for the jelly roll element 50.

Accordingly, the present invention provides a laminated electrode structure for maintaining or improving the electric capacity per a fixed volume and preventing a short circuit caused by contact between a positive electrode material and a negative electrode material, and a method using the laminated electrode structure. It is intended to provide a secondary battery.

[0012]

According to the present invention, there is provided a laminated electrode structure according to the present invention, wherein a positive electrode active material layer is formed on a main surface of a positive electrode current collector and one side of the positive electrode current collector. A positive electrode material provided with a positive electrode lead at an edge portion, a negative electrode material provided with a negative electrode lead at one side edge portion of a negative electrode current collector, and a separator interposed between the positive electrode material and the negative electrode material are laminated. Be composed. Further, in the laminated electrode structure, the positive electrode material and the negative electrode material are sequentially laminated such that the side edge portions where the positive electrode lead and the negative electrode lead are formed are located on opposite side portions, respectively. An ear portion is provided along one side edge portion where the lead is provided so that the positive electrode current collector is exposed with a predetermined width, and the edge of the ear portion is located outside the opposing side edge portion of the negative electrode material. It is characterized by being laminated as follows.

Further, a secondary battery according to the present invention is characterized by including the laminated electrode structure having the above-described structure as a power generation element.

According to the laminated electrode structure and the secondary battery using the same according to the present invention having the above-described structure, even when the positive electrode lead is folded, the laminated structure is located outside the negative electrode material. Since the positive electrode material contacts and is supported by the side edges of the positive electrode material, short-circuiting due to contact between the positive electrode lead and the negative electrode material is prevented.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, specific embodiments of the laminated electrode structure according to the present invention and a secondary battery using the laminated electrode structure will be described in detail with reference to the drawings. In the present embodiment, the stacked electrode structure according to the present invention is applied to a so-called jelly-roll element 1 of a wound type, which is housed in a bottomed cylindrical metal outer case of the secondary battery 20, for example. Things will be described. The secondary battery 20 is connected to a metal plate constituting a positive electrode by closing the open surface of the outer case by closing a terminal on the positive electrode side of the jelly roll element 1 housed therein, although not shown in detail.
The terminal on the negative electrode side is connected to a metal outer case constituting the negative electrode.

As shown in FIG. 1, a jelly roll element 1 is composed of a band-shaped positive electrode material 2 and a band-shaped negative electrode material 3 separated by a separator 4.
And are wound by winding them.

As shown in FIG. 2 and FIG.
A positive electrode mixture containing a positive electrode active material as one component is applied to both surfaces of a positive electrode foil 5 made of a long aluminum foil to form an active material layer 6.
Are formed. The active material layer 6 contains at least a positive electrode active material such as lithium manganese oxide, and other conductive agents such as graphite for imparting conductivity, and polyfluoride for holding the lithium manganese oxide on the positive electrode foil 5. It is formed by applying a positive electrode mixture composed of a binder or the like such as a fluororesin such as vinylidene. In the positive electrode material 2, the active material layer 6 is not applied and formed within a certain distance from one side edge of the positive electrode foil 5, and the ear 7 is provided so that the positive electrode foil 5 is exposed at a predetermined width. I have.

In the positive electrode material 2, a plurality of rectangular positive electrode leads 8 are formed by punching out the positive electrode foil 5 at one side edge portion provided with the ear 7. The positive electrode lead 8 is formed by punching out one side edge of the positive electrode foil 5 as described above.
And are formed integrally. The positive electrode lead 8 is formed at substantially equal intervals on one side edge of the positive electrode material 2, and the jelly roll element 1 is formed by winding the positive electrode material 2 and the like as described later to form the secondary battery 2.
The jelly roll element 1 is folded toward the winding axis A of the jelly roll element 1 when stored in the outer case 0.

As shown in FIG. 1, the negative electrode material 3 is composed of a negative electrode foil 9 made of a long copper foil wider than the active material layer 6 formed on the above-described positive electrode material 2. A negative electrode lead 10 is formed on the substrate. The negative electrode lead 10 is formed integrally with the negative electrode foil 9 by punching out one side edge of the negative electrode foil 9 similarly to the positive electrode lead 8 described above. A plurality of negative electrode leads 10 are formed at substantially equal intervals on one side edge of the negative electrode foil 9.

The separator 4 is formed into a long shape like the cathode material 2 and the anode material 3 using, for example, microporous polyethylene, and is interposed between the cathode material 2 and the anode material 3 to insulate them. I do.

As shown in FIG. 3, the jelly roll element 1 is formed by laminating the above-described components in the order of the positive electrode material 2, the separator 4, the negative electrode material 3, and the separator 4. At this time, the positive electrode material 2 and the negative electrode material 3 are laminated such that the positive electrode lead 8 or the negative electrode lead 10 formed on one side edge is located on the opposite side. Further, the positive electrode material 2 and the negative electrode material 3
In order to prevent variations in the characteristics of the secondary battery 20, the active material layers 6 formed on the positive electrode foil 5 are stacked so as to be located inside both side edges of the negative electrode material 3. Jerry roll element 1
Is formed by winding each of the above-described members in a stacked state.

In the jelly roll element 1, the base of the positive electrode lead 8, that is, the edge of the ear 7 of the positive electrode foil 5 is located outside one side edge of the opposite negative electrode material 3.
Therefore, when the jelly roll element 1 is stored in the outer case of the secondary battery 20, even if the positive electrode lead 8 is folded as shown in FIG. It is supported and does not contact the negative electrode material 3. In the jelly roll element 1, short-circuit of the secondary battery 20 caused by the contact of the positive electrode lead 8 with the negative electrode material 3 can be prevented.

In the jelly roll element 1,
Since the entire positive electrode lead 8 is located outside the negative electrode material 3, even if a burr is formed on the positive electrode lead 8 folded in the winding axis direction, the burr is removed by the separator 4.
To contact the negative electrode material 3 by breaking through. The jelly roll element 1 has the above-described structure to prevent short-circuiting caused by the burrs of the positive electrode lead 8 piercing the separator 4, so that it is not necessary to change the thickness of the separator 4, 4. The positive electrode material 2 and the negative electrode material 3 can be wound more by reducing the thickness. Therefore, in the secondary battery 20,
By using the jelly roll element 1 described above,
Achieve increased battery capacity. Further, in the secondary battery 20, the quality control of the burrs for removing the positive electrode lead 8, which may cause a short circuit, can be eased and the working efficiency can be improved.

The positive electrode material 2 is located outside the side edge of the negative electrode material 3 where one side edge on the side of the ear 7 is opposite, specifically, at least (winding amount on the negative electrode side + tolerance) + (| It is sufficient that the layers are stacked so that they are located on the outer side of the winding deviation amount−tolerance |
0.1% is added to ensure the prevention of short circuit.
The layers may be stacked so as to be positioned on the outside by about mm.

In the present embodiment, the secondary battery 20 in which the wound jellyroll element 1 is housed as a power generating element has been described, but the present invention is not limited to such a form. The laminated structure housed as the power generating element is not limited to the above-described wound type, and may be a laminated type in which a positive electrode material, a negative electrode material, and a separator formed in a rectangular sheet shape are sequentially laminated.

The laminated structure is the same as that of the secondary battery 2 described above.
In addition to 0, the present invention can be applied to a capacitor or the like employing a laminated electrode structure.

[0027]

As described above in detail, in the laminated electrode structure according to the present invention, the ear portion is provided on one side edge of the positive electrode material provided with the positive electrode lead, and the edges of the ear portion are opposed to each other. By being positioned outside the side edge of the negative electrode material and laminated, even when the positive electrode lead is folded in a direction substantially perpendicular to the laminated positive electrode material, the positive electrode lead does not contact the negative electrode material, Are also supported by contacting the ears of adjacent stacked positive electrode materials located outside. For this reason, according to the laminated electrode structure and the secondary battery using the laminated electrode structure according to the present invention, it is possible to prevent short-circuiting caused by contact between the positive electrode lead and the negative electrode material. Further, according to the laminated electrode structure according to the present invention and the secondary battery using the laminated electrode structure, it is not necessary to increase the thickness of the separator in order to prevent a short circuit, so that the battery capacity of the secondary battery can be maintained. Further, the battery capacity can be increased by making the separator thinner.

[Brief description of the drawings]

FIG. 1 is a perspective view for explaining a stacked state of respective components of a jelly roll element housed in an outer case of a secondary battery.

FIG. 2 is a plan view of a main part of a positive electrode material.

FIG. 3 is a longitudinal sectional view of a main part in a state where a positive electrode material, a negative electrode material, and a separator are stacked.

FIG. 4 is a longitudinal sectional view of a main part of the jelly roll element showing a state in which a positive electrode lead is folded.

FIG. 5 is a sectional view of a main part of a conventional jelly roll element.

FIG. 6 is a plan view of a main part of a conventional positive electrode material.

FIG. 7 is a vertical cross-sectional view of a main part for describing a state in which a conventional jelly roll element is short-circuited.

[Explanation of symbols]

1 jelly roll element, 2 positive electrode material, 3 negative electrode material, 4
Separator, 5 Positive foil current collector, 6 Active material layer, 7
, 8 Positive electrode lead, 9 Negative electrode foil current collector, 10 Negative electrode lead, 20 Secondary battery

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Kiyoshi Arai 1-1-1 Shimosugishita, Takakura, Hiwada-cho, Koriyama-shi, Fukushima F-term in Soni Energy Tech Co., Ltd. (reference) 5H028 AA01 AA05 CC05 CC11 HH06 5H029 AJ01 AK03 DJ07 EJ12

Claims (2)

[Claims] 1. A positive electrode material having a positive electrode active material layer formed on a main surface of a positive electrode current collector and a positive electrode lead provided on one side edge of the positive electrode current collector; A negative electrode material provided with a negative electrode lead on a portion thereof, and a separator interposed between the positive electrode material and the negative electrode material are laminated, and the positive electrode material and the negative electrode material are formed of the positive electrode lead and the negative electrode. The positive electrode material is arranged in such a manner that the positive electrode current collector is exposed at a predetermined width along one side edge portion on which the positive electrode lead is provided. A laminated electrode structure, wherein the laminated electrode structure is provided such that the edge portion of the ear portion is located outside a side edge portion of the negative electrode material facing the edge portion. 2. A positive electrode material having a positive electrode active material layer formed on a main surface of a positive electrode current collector and a positive electrode lead provided on one side edge portion, and a negative electrode lead on one side edge portion of a negative electrode current collector. The provided negative electrode material and a separator interposed between the positive electrode material and the negative electrode material are sequentially laminated so that the positive electrode lead and the negative electrode lead are located at opposite side edges, respectively. An ear portion is provided along one side edge portion of the material where the positive electrode lead is provided so that the positive electrode current collector is exposed, and the ear portion is located outside the other side edge portion of the negative electrode material. A secondary battery comprising a stacked electrode structure.