JPH11273692A - Battery having spiral electrode body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a battery which prevents a decrease in voltage during discharge and a decrease in discharge capacity by preventing a negative electrode from running out even if a positive electrode is placed on the outermost periphery of a spiral electrode body. SOLUTION: A manganese dioxide positive electrode 10 is made longer than a lithium negative electrode 30 by X. This elongated part serves as an extension 11a when the electrodes are combined into a spiral electrode body. The positive electrode plate 10 and the lithium negative electrode plate 30 are stacked with a separator 40 therebetween and wound into a spiral shape in which the lithium negative electrode plate 30 is located inside and the part of the extension 11a to which an insulator 14 is bonded is located on the outermost periphery, to form the spiral electrode body (a). Therefore the lithium negative electrode plate 30 does not exist on the inner periphery of the part of the positive plate 10 to which the insulator 14 is bonded, but since this part undergoes a discharge reaction with the same amount of positive electrode active material as do other parts, the discharge reaction proceeds uniformly over the entire lithium negative electrode plate 30 and the negative electrode can be prevented from running out.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spiral electrode body formed by spirally winding a negative electrode formed in a strip shape of lithium or a lithium alloy as a negative electrode active material and a positive electrode formed in a strip shape via a separator. It is related to the structure of.

[0002]

2. Description of the Related Art Conventionally, in a sealed battery, a strip-shaped negative electrode and a strip-shaped positive electrode are spirally wound through a separator to form a spiral electrode body. Alternatively, it is housed in a metal outer can serving as one external terminal of the negative electrode, and the metal outer can is sealed.

[0003] Among them, a spiral electrode body in a nonaqueous electrolyte battery using lithium or a lithium alloy as a negative electrode active material is generally formed of a sheet of lithium or a lithium alloy to form a band-shaped negative electrode. A spiral electrode body is formed by spirally winding an electrode and a band-shaped positive electrode through a separator so that the negative electrode is located at the outermost periphery thereof. Therefore, the positive electrode and the negative electrode face each other on both sides, but the outermost negative electrode has a structure in which only the inner circumferential side faces the positive electrode.

By the way, the lithium active material of the lithium primary battery gradually wears out as the discharge reaction progresses and eventually disappears. As described above, the negative electrode located at the outermost periphery is limited only to the inner peripheral side. If it is configured to face the positive electrode with
The state of consumption of the negative electrode after complete discharge is as follows.
That is, in the negative electrode located at the outermost periphery, the lithium active material is not completely consumed and a part remains, and the discharge reaction is not necessarily uniform on all the opposing surfaces. Part of the substance remains.

As described above, when a part of the lithium active material remains on the negative electrode, the discharge reaction concentrates on the outermost periphery where a large amount of the lithium active material is present as the discharge reaction reaches a complete discharge. There was a problem that lithium was deposited on the surface of the positive electrode to cause an internal short circuit.

In order to solve such a problem, a configuration is adopted in which a positive electrode is arranged at the outermost peripheral portion of the spiral electrode body and the positive electrode at the outermost peripheral portion covers the negative electrode. It was proposed in Japanese Unexamined Patent Publication No. Hei 5-290826. As shown in FIG. 7 (FIG. 7 shows a half of the cross section of the spiral electrode body), the battery proposed in Japanese Patent Application Laid-Open No. 5-290826 has a negative electrode 2 previously formed in a band shape. A separator 3 is interposed between the negative electrode 2 and the positive electrode 1 previously formed in a strip shape so as to be longer than the negative electrode 2 by X to form a laminate. Thus, the spirally wound electrode body B is formed in a spiral shape (that is, with the positive electrode 1 being the outer peripheral portion).

A positive electrode current collecting tab (not shown) extending from the positive electrode 1 of the spiral electrode body B is disposed on the outer peripheral side,
The negative electrode current collection tab 2a extending from the negative electrode 2 is disposed on the inner peripheral side. As a result, in the positive electrode 1 having a length longer than the negative electrode 2 by X in advance, an extended portion 1a extending from the negative electrode 2 is formed at the outermost periphery of the spiral electrode body B. Will cover. Therefore, the problem that a part of the lithium active material remains in the negative electrode 2 located on the outer periphery does not occur.

[0008]

However, in the spiral electrode body proposed in JP-A-5-290826, the negative electrode 2 is disposed at the outermost periphery of the spiral electrode body B.
Since the extended portion 1a is further extended, the extended portion 1a does not face the negative electrode 2 but faces the positive electrode 1 on the inner peripheral portion thereof. Therefore, this portion (X portion in FIG. 7)
The amount of the active material of the positive electrode active material is relatively increased as compared with the other positive electrode active materials, and the discharge reaction is concentrated on the negative electrode 2b facing the positive electrode of the X portion.

As a result, the negative electrode 2b facing the positive electrode of the X section
Is consumed at a faster rate than the other part of the negative electrode 2, and a state in which the negative electrode active material does not remain occurs with the end of discharge, so that a so-called negative electrode cut-off phenomenon appears. When such a negative electrode break occurs, the negative electrode 2 located on the outer peripheral side with respect to the negative electrode 2b is not connected to the negative electrode current collecting tab 2a, so that there is a problem that the voltage rapidly decreases and the discharge capacity decreases. .

[0010]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to prevent the negative electrode from being cut even when the positive electrode is disposed at the outermost periphery of the spiral electrode body, thereby reducing the voltage during discharge and the discharge. An object of the present invention is to provide a battery that does not cause a decrease in capacity.

In order to achieve this object, the spiral electrode body of the present invention extends from the negative electrode such that the winding end of the positive electrode disposed at the outermost periphery thereof covers the winding end of the negative electrode. An extension is provided, and an insulator is provided at a portion where the extension and the positive electrode on the inner periphery of the spiral electrode body face each other. As described above, when an insulator is provided at a portion where the extension and the positive electrode at the inner periphery of the spiral electrode body are opposed to each other, the positive electrode of the extension and the positive electrode at the inner periphery are not opposed by the insulator. Therefore, the discharge reaction does not concentrate on the negative electrode facing the insulator. For this reason, the negative electrode is prevented from being broken,
It is possible to obtain a battery in which the voltage and the discharge capacity do not decrease during discharging. As a result, it is possible to prevent the battery voltage from suddenly lowering, to improve the discharge voltage, and to obtain a long-life non-aqueous electrolyte battery.

When the insulator is attached to the inner peripheral portion of the extension on the surface facing the positive electrode, the insulator is simply attached to the extension or the inner periphery of the extension. As a result, it is possible to insulate between the two positive electrodes, so that this kind of spiral electrode body can be easily manufactured. Furthermore, by using an adhesive tape made of a synthetic resin for the insulator, this kind of spiral electrode body can be manufactured more easily.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing an example of a manganese dioxide positive electrode of an example of the present invention, and FIG. 2 is a diagram showing a manganese dioxide positive electrode of a comparative example. FIG. 3 is a view showing a lithium negative electrode, and FIG. 4 is a view showing a half of a cross section of a spirally wound electrode body obtained by spirally winding a manganese dioxide positive electrode 2 and a lithium negative electrode of the example. FIG. 5 is a view showing a cross section of a non-aqueous electrolyte battery in which the spiral electrode body of FIG. 4 is housed in an outer can.

1. Manufacture of positive electrode plate (a) Example Manganese dioxide as a positive electrode active material, a carbon-based conductive agent as a conductive agent, polytetrafluoroethylene (PTFE) as a binder, and water were mixed and kneaded at a predetermined ratio. Thus, a positive electrode mixture having an appropriate viscosity is produced. This positive electrode mixture is applied to an expanded metal 11 made of stainless steel, rolled by a roller, cut, and cut to a length of, for example, 18 mm.
A rolled positive electrode plate having a thickness of 0 mm, a width of 30 mm, and a thickness of 0.6 mm is prepared. After the rolled positive electrode plate is dried, a part of the positive electrode mixture at the position of the outermost periphery when the spirally wound positive electrode plate is later wound is peeled off to expose the expanded metal 11, and the exposed portion is made of stainless steel. The positive electrode current collecting tab 12 made of a thin plate is spot-welded.

Thereafter, in order to protect the positive electrode current collecting tab 12, an adhesive tape 13 made of glass is attached so as to cover the upper surface of the positive electrode current collecting tab 12 except for the vicinity of the front end portion. After that, a synthetic resin (for example, polyethylene terephthalate) having electrical insulation properties at an end that does not face the negative electrode 20 described later at a position that becomes the outermost periphery when spirally wound later, for example, Length 40mm, width 30m
m of the adhesive tape 14 is applied, heated to 200 ° C. and dehydrated, to produce the manganese dioxide positive electrode 10 of the example. The manganese dioxide positive electrode 10 thus produced was
Is X (for example, 40 m
m: see FIG. 1), and the portion formed long by X is the extended portion 1 when it is formed as a spiral electrode body.
1a.

(B) Comparative Example A positive electrode mixture prepared in the same manner as in the above-described embodiment is applied to a stainless steel expanded metal 21, rolled by a roller, cut, and cut, for example, to a length of 180 mm and a width of 30 mm.
A rolled positive electrode plate having a thickness of 0.6 mm is produced. After the rolled positive electrode plate is dried, a part of the positive electrode mixture at the position of the outermost peripheral portion when it is later spirally wound is peeled off, and the expanded metal 21 is exposed. The positive electrode current collecting tab 22 made of a thin plate is spot-welded. Thereafter, in order to protect the positive electrode current collecting tab 22, a glass adhesive tape 23 is attached so as to cover the upper surface of the positive electrode current collecting tab 22 except for the vicinity of the front end portion thereof.
The manganese dioxide positive electrode plate 20 of the comparative example is manufactured by heating to 00 ° C. and dehydrating. The manganese dioxide positive electrode 20 manufactured in this manner is connected to a lithium negative electrode 30 described later.
It is formed longer by X (for example, 40 mm: see FIG. 2), and the portion formed longer by X becomes the extension 21a when the spiral electrode body is formed.

2. Production of Lithium Negative Plate First, a lithium metal or lithium alloy plate 31 (for example, having a thickness of 0.3 mm) is shorter than the manganese dioxide positive plates 10 and 20 by X (for example, 40 mm; see FIGS. 1 and 2). As described above, for example, after cutting into a length of 140 mm and a width of 28 mm, the negative electrode current collecting tab 32 made of a nickel thin plate is crimped and fixed from the center to the end side.
A synthetic resin adhesive tape 33 is attached so as to cover the upper surface of the negative electrode current collecting tab 32 except for the vicinity of the front end portion thereof, thereby producing the lithium negative electrode plate 30.

3. Production of Spiral Electrode Body (a) Example The manganese dioxide positive electrode plate 10 and the lithium negative electrode plate 30 of the example produced as described above are laminated with the separator 40 interposed therebetween to form a laminate. In forming this laminate, the positive electrode current collecting tab 12 and the negative electrode current collecting tab 32
Are arranged so that they face in the same direction as each other.

Then, the laminated body is made so that the manganese dioxide positive electrode plate 10 is on the inside and the lithium negative electrode plate 30 is on the outside, and the synthetic resin adhesive tape 14 of the manganese dioxide positive electrode plate 10 is attached ( The spirally wound electrode body a as shown in FIG. 4 is manufactured by spirally winding the extension 11a) so as to be the outermost periphery. Thereby, the portion (extended portion 11a) of the manganese dioxide positive electrode plate 10 formed longer than the lithium negative electrode plate 30 is arranged on the outermost periphery of the spiral electrode body A, and the synthetic resin of the manganese dioxide positive electrode plate 10 is formed. Negative electrode plate 30 does not exist on the inner peripheral side of the portion where the adhesive tape 14 made of aluminum is adhered.

(B) Comparative Example The manganese dioxide positive electrode plate 20 and the lithium negative electrode plate 30 of the comparative example produced as described above are laminated with a separator 40 interposed therebetween to form a laminate. In forming this laminate, the positive electrode current collecting tab 22 and the negative electrode current collecting tab 32
Are arranged so that they face in the same direction as each other. Then, the laminate is spirally wound with the manganese dioxide positive electrode plate 10 inside and the lithium negative electrode plate 30 outside, thereby producing a spiral electrode body (not shown) as in the example. As a result, the manganese dioxide positive electrode plate 20 formed longer than the lithium negative electrode plate 30 is arranged on the outermost periphery of the spiral electrode body, and the outermost peripheral portion of the manganese dioxide positive electrode plate 10 is located at the end side. The lithium negative electrode plate 30 does not exist on the inner peripheral side.

4. Preparation of Nonaqueous Electrolyte Battery First, ethylene carbonate (EC), butylene carbonate (BC), and 1,2-dimethoxyethane (DME)
Is dissolved in an organic solvent obtained by mixing at a volume ratio of 15:15:70 with lithium trifluoromethanesulfonate (LiCF ₃ SO ₃ ) as a solute (electrolyte) at a ratio of 0.5 mol / l. To produce a non-aqueous electrolyte.

Example 1 Next, as shown in FIG. 5, a stainless steel outer can (for example, 17 mm in diameter and 45 mm in height) also serving as a positive electrode external terminal.
mm cylindrical can) 50, a bottom insulating plate 51 having a hole 51a at the center, the spiral electrode body a of the above-described embodiment,
An insulating ring 52 having holes 52a and 52b at the center and its periphery and having a projection 52c is inserted.
Next, a sealing body 60 to which a negative electrode terminal 62 is fixed at the center via an insulating gasket 61 is prepared.

Thereafter, the lithium negative electrode 3 of the spiral electrode body A
In addition to spot welding the tip of the negative electrode current collector tab 32 fixed to the lithium plate 31 by pressure welding to the bottom of the negative electrode terminal 62, the positive electrode current collector tab 1 of the manganese dioxide positive electrode plate 10
2 is spot-welded to the inner side wall of the outer can 50. Then, after injecting the non-aqueous electrolyte prepared as described above into the outer can 50, the sealing body 60 is placed on the opening of the outer can 50, and the opening of the outer can 50 and the peripheral portion of the sealing body 60 are formed. Is sealed by laser welding to produce a non-aqueous electrolyte battery A of Example. At the bottom of the outer can 50, there is provided a safety valve 53 that operates when the internal pressure of the battery rises to a predetermined pressure and discharges gas inside the battery to the outside of the battery.

Comparative Example Similarly, a stainless steel outer can (also a cylindrical can having a diameter of 17 mm and a height of 45 mm) serving also as a positive electrode external terminal 5
0, a bottom insulating plate 51 having a hole 51a in the center,
The above-described spiral electrode body of the comparative example, and an insulating ring 52 having holes 52a and 52b at the center and the periphery thereof and having a projection 52c are inserted. Next, the tip of the negative electrode current collecting tab 32 fixed to the lithium plate 31 of the lithium negative electrode 30 of the spiral electrode body by press-fitting, as in the example,
Spot welding is performed on the bottom of the negative electrode terminal 62 and the positive electrode current collecting tab 22 of the manganese dioxide positive electrode plate 20 is attached to the outer can 50.
After spot welding to the inner side wall, a non-aqueous electrolyte is injected into the outer can 50, and the sealing body 60 is placed on the opening of the outer can 50, and the opening of the outer can 50 and the periphery of the sealing body 60 are placed. The part was sealed by laser welding to produce a non-aqueous electrolyte battery B of a comparative example.

[5] Experimental results Using the non-aqueous electrolyte batteries A and B manufactured as described above,
When the outside air temperature was set at 25 ° C. and the non-aqueous electrolyte batteries A and B were connected to a constant resistance of 560Ω to conduct a discharge test, the results shown in FIG. 6 were obtained. In FIG. 6, curve A shows the discharge characteristics of the non-aqueous electrolyte battery A of the example, and curve B shows the discharge characteristics of the non-aqueous electrolyte battery B of the comparative example. Further, when these non-aqueous electrolyte batteries A and B were completely discharged and then the non-aqueous electrolyte batteries A and B were disassembled, the non-aqueous electrolyte battery A did not show any negative electrode breakage. In the non-aqueous electrolyte battery B, the negative electrode 30
Of the negative electrode was observed at the end of the winding, and the outermost positive electrode 1
The negative electrode 30 inside 0 was left.

As is apparent from FIG. 6, the battery voltage of the non-aqueous electrolyte battery B of the comparative example drops extremely after a discharge time of 300 hours has passed, whereas the non-aqueous electrolyte battery A of the embodiment has a discharge time of 300 hours. It can be seen that the battery voltage does not decrease as in the non-aqueous electrolyte battery B of the comparative example even after the elapse of 300 hours.

This is because a portion of the manganese dioxide positive electrode plate 10 formed longer than the lithium negative electrode plate 30 (extension portion 11
a) is disposed on the outermost periphery of the spiral electrode body a, and the lithium negative electrode plate 30 does not exist on the inner peripheral side of the extension 11a. However, since an adhesive tape (insulator) 14 made of a synthetic resin is adhered to the extension portion 11a, the lithium negative electrode plate 30 (X in FIG.
Portion) undergoes a discharge reaction with the same amount of the positive electrode active material as in the other portions. For this reason, it is considered that the discharge reaction progressed uniformly throughout the lithium negative electrode plate 30, and the negative electrode was not cut off in the inner portion of the lithium negative electrode plate 30 (portion X in FIG. 4). As a result, all the lithium active materials of the lithium negative electrode plate 30 effectively discharge and react,
A battery in which the battery voltage does not decrease and the discharge capacity does not decrease can be obtained.

In the above-described embodiment, an example in which a cylindrical battery is manufactured has been described. However, it is apparent that the present invention can be applied not only to a cylindrical battery but also to a battery having another shape such as a square battery. Further, although an example in which the sealing portion is formed by laser welding has been described, a sealing method in which the sealing body is sealed by caulking the sealing body in an outer can may be employed instead of laser welding.

[Brief description of the drawings]

FIG. 1 is a diagram showing an example of a manganese dioxide positive electrode of the present invention.

FIG. 2 is a diagram showing a manganese dioxide positive electrode of a comparative example (conventional example).

FIG. 3 is a view showing a lithium negative electrode.

FIG. 4 is a diagram showing a half of a cross section of a spiral electrode body of the present invention.

FIG. 5 is a view showing a cross section of a non-aqueous electrolyte battery in which a spiral electrode body is housed in an outer can.

FIG. 6 is a diagram showing discharge characteristics of a non-aqueous electrolyte battery.

FIG. 7 is a diagram showing a half of a cross section of a conventional spiral electrode body.

[Explanation of symbols]

10, 20... Manganese dioxide positive plate, 11a, 21a.
Extensions 11, 21, ... expanded metal, 12, 22
... Positive electrode collecting tabs, 13,23 ... Adhesive tape, 14 ... Adhesive tape (insulator), 30 ... Lithium negative electrode plate, 31 ... Lithium alloy plate, 32 ... Negative electrode current collecting tab, 23 ... Adhesive tape,
40: separator, 50: outer can, 51: bottom insulating plate,
52: insulating ring, 53: safety valve, 60: sealing body, 61
... insulating gasket, 62 ... negative electrode terminal

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Satoru Satoru 2-5-5 Keihanhondori, Moriguchi-shi, Osaka Sanyo Electric Co., Ltd.

Claims (3)

[Claims] 1. A battery provided with a spiral electrode body formed by spirally winding a strip-shaped negative electrode and a strip-shaped positive electrode via a separator, wherein the positive electrode is the spiral electrode body. And an extension extending from the negative electrode so that the winding end of the positive electrode covers the winding end of the negative electrode, wherein the extension and the spiral electrode body A battery provided with a spiral electrode body, wherein an insulator is provided in a portion of the inner peripheral portion facing the positive electrode. 2. The spiral electrode body according to claim 1, wherein the insulator is attached to a surface of the inner peripheral portion of the extension portion facing the positive electrode. battery. 3. The battery according to claim 1, wherein the insulator is an adhesive tape made of a synthetic resin.