JP3301798B2 - 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 battery using a spiral electrode body having a non-circular cross section.

[0002]

2. Description of the Related Art Conventionally, the digitization of many devices has progressed, and batteries have been used as power sources for these devices. Among such devices, particularly in the fields of radios, tape recorders, cameras, and the like, devices are required to be smaller and thinner. When considering the miniaturization and thinning of this device, it is natural that the battery is expected to be small and light, and the ratio of the battery volume in the device (volume efficiency in the device)
Considering the above, it is known that the square type is advantageous in mounting efficiency.

As this prismatic type battery, a stacked type in which electrode plates are stacked in several layers is widely used in the fields of nickel-cadmium batteries, lead batteries and the like. However, large currents and high voltages are required in the equipment used, and in consideration of further increasing the output and improving the heavy load characteristics, the electrodes are made thinner and spirally wound to form non-circular electrodes. The method used as a spiral electrode body having a cross section of the shape is most effective,
It is also advantageous in terms of productivity.

[0004] As a method of manufacturing this spiral electrode body,
A method in which an electrode plate is wound around a plate-shaped core (Japanese Patent Application Laid-Open No. 58-218768), and a method in which a perfect circular electrode body is pressed in a predetermined direction (Japanese Patent Application Laid-Open No. 60-2516).
No. 4) has been proposed.

[0005] However, since the above method is difficult to wind up in an elliptical shape from the beginning, a winding device and a winding method are difficult, and a method of winding and pressing in a perfect circle is often used.

However, according to this method, when pressed in a predetermined direction, the central through-hole portion of the spiral electrode body formed at the time of winding the perfect circle shows irregular deformation. This deformation causes the electrode in the vicinity of the innermost peripheral portion of the spiral electrode body to bend at the maximum curvature, causing the separation of the active material from the core of the electrode and the damage of the electrode. Further, in an extreme case, the damaged electrode may break the separator and cause an internal short circuit.

Another major problem of this method is that the degree of tightness of the electrodes and the distance between the electrodes are non-uniform due to the difference in curvature between the inner and outer corners of the non-circular spiral electrode body. This has adversely affected discharge performance and cycle characteristics.

As a countermeasure for this, after inserting a core having a desired cross-sectional shape into the central opening of the perfect circular spiral electrode body,
Method for compression-molding a spiral electrode body (Japanese Patent Application Laid-Open No. 60-2516)
No. 4) has been proposed.

However, the purpose of this publication is to secure a spot hole. For this purpose, the core must be removed after inserting the spiral electrode body into the outer can. As a result, there is a problem that the degree of tension of the spiral electrode body cannot be secured.

Furthermore, this method cannot sufficiently prevent the electrode innermost part of the spiral electrode body from being damaged and the degree of tightness being non-uniform.

[0011]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned problems, and the electrode breakage or internal short-circuit occurring in a spiral electrode body having a non-circular cross section such as an ellipse or an ellipse. Alternatively, it is an object of the present invention to provide a high-quality, high-performance battery by preventing battery performance deterioration or the like caused by non-uniformity in the degree of electrode tension.

[0012]

According to the present invention, there is provided a battery comprising a spiral electrode body comprising a positive electrode and a negative electrode with a separator interposed therebetween, and pressing the spiral electrode body into a non-circular spiral electrode body. A hollow metal pipe is provided in a central through-hole of the spiral electrode body.

It is preferable that a cross section of the outer can housing the non-circular spiral electrode body has a rectangular or oval shape.

[0014]

The battery of the present invention is provided with a hollow metal pipe in the central through-hole of the spiral electrode body, so that when the perfect circular spiral electrode body is made non-circular by pressing, the non-circular spiral electrode is formed. Since the curvature within a certain amount formed by the outer periphery of the hollow metal pipe is ensured even at the innermost periphery of the body, internal short-circuit due to breakage of the electrode and lack of the electrode can be prevented.

In addition, since the stress of the inner peripheral portion is prevented from being deformed and the uniform stress is maintained, the battery reaction is promoted, and the discharge characteristics and the cycle characteristics in the case of a secondary battery are improved.

Furthermore, since the hollow metal pipe at the center of the non-circular spiral electrode body can be used as it is as the current collector core, the manufacturing process can be simplified.

[0017]

【Example】

Embodiment 1 Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 1 shows a non-circular spiral electrode body of the present invention. Reference numeral 1 denotes a hollow metal pipe provided in a central through hole of the spiral electrode body, and 2 denotes a spiral electrode body in which a positive electrode and a negative electrode are wound via a separator.

Here, the positive electrode was prepared by adding 80 parts by weight of manganese dioxide to which a lithium salt was previously added and mixed and calcined, 10 parts by weight of acetylene black as a conductive agent, and 10 parts by weight of a fluororesin powder as a binder. After kneading,
With the stainless steel punching as a core, the mixed mixture was added to prepare a strip-shaped electrode having a thickness of about 0.5 mm, which was used as a positive electrode. As the negative electrode, a lithium foil having a thickness of about 0.2 mm was processed into a belt shape and used. As the separator, a microporous film made of polypropylene was used.

The above-mentioned positive electrode and negative electrode are wound through a separator with a hollow metal pipe 1 made of iron-nickel plating having an outer diameter of 6 mm and an inner diameter of 5 mm made of iron-nickel wound as a core.
And The spiral electrode body 2 has a diameter of about 13 mm.

Next, the spiral electrode body 2 is pressed with a predetermined jig to obtain a long side of about 18 mm and a short side of about 8 m as shown in FIG.
m of non-circular spiral electrode bodies were produced. This non-circular spiral electrode body is inserted into a square outer can having an outer diameter of 20 × 10 mm and a height of about 50 mm, and after the organic electrolyte is injected, sealing is performed.
A prismatic battery was produced, and was designated as Battery A of the present invention. At this time, the metal pin at the center was used as a current collecting terminal of the negative electrode, and was connected to the negative electrode terminal provided on the sealing body.

FIG. 2 shows this battery configuration. In FIG. 2, reference numeral 2 denotes a non-circular spiral electrode body including a positive electrode, a negative electrode, and a separator, and 1 denotes a hollow metal pipe also serving as a current collecting terminal. Reference numeral 3 denotes a battery outer can, 4 denotes a sealing body, and 5 denotes a negative electrode terminal plate connected to a hollow metal pipe.

Although the battery A1 of the present invention uses a rectangular outer can, any cross-section of the outer can that can accommodate a non-circular spiral electrode body may be rectangular or oval.

COMPARATIVE EXAMPLE 1 As Comparative Example 1, as shown in FIG. 5, a perfect circular spiral electrode body having an opening (winding hole) of about 6 mm in the center through hole of the spiral electrode body was pressed. Then, a battery was fabricated in the same manner as in Example 1 except that a non-circular spiral electrode body was used, and a comparative battery X1 was obtained.

Comparative Example 2 As Comparative Example 2, as shown in FIG. 6, a core having a rectangular cross section was inserted into the central through hole of the spiral electrode body, and then pressed to form a non-circular shape. A battery was fabricated in the same manner as in Example 1 except that the spiral electrode body was used, and a comparative battery X2 was obtained.

[Experiment 1] Battery A1 of the present invention immediately after assembly
Table 1 shows the number of internal short-circuit defects of the comparative batteries X1 and X2.
The internal short circuit was determined from the open circuit voltage and the internal resistance value.

[0027]

[Table 1]

As is clear from Table 1, internal short-circuits occur in the comparative batteries X1 and X2, while the internal short-circuit can be completely prevented in the battery A1 of the present invention.

As a result of disassembly and examination of each battery, in the comparative batteries X1 and X2, which were internally short-circuited, peeling or falling off of the active material from the positive electrode core was confirmed near the innermost periphery of the spiral electrode body. Probable cause.

[Experiment 2] Battery A1 of the present invention and Comparative Battery X1
And X2 were subjected to a charge / discharge cycle test. The cycle conditions were 200 mA for both charging and discharging currents, 3.5 V for charging,
Discharging was performed at 2.0 V as a termination voltage. The result is shown in FIG.

The vertical axis of FIG. 3 shows the ratio of the battery capacity for each cycle when the initial battery capacity is 100, and the horizontal axis shows the number of cycles.

FIG. 3 shows that the battery A1 of the present invention is a comparative battery X
It can be seen that the cycle performance was excellent and the cycle characteristics were very stable with little variation compared to X1 and X2.

Next, FIG. 4 shows a cross-sectional view of the spiral electrode body before and after the press molding of the battery A1 of the present invention. Here, FIG. 4A shows the spiral electrode body before pressing and FIG. 4B shows the spiral electrode body after pressing. As described above, since the battery A1 of the present invention is provided with the hollow metal pipe in the central through-hole portion of the spiral electrode body when the perfect spiral electrode body is pressed and formed into the non-circular spiral electrode body, the pressing is performed. Since the pressure to the vicinity of the innermost periphery of the spiral electrode body can be absorbed by the hollow portion of the metal pipe, the curvature near the innermost periphery of the spiral electrode body can be reduced as shown in FIG. Peeling and falling off can be prevented.

However, the comparative battery X1 shown in FIG.
In the case of (1), the opening 6 formed in the center through hole of the spiral electrode body at the time of winding is deformed irregularly at the time of pressing as shown in FIGS. Normally, as shown in FIG. 5B, the electrode near the innermost peripheral portion of the spiral electrode body forms the maximum curvature and is almost bent. However, the curvature becomes smaller toward the outer periphery of the spiral electrode body, so that the curvature of the inner periphery and the outer periphery becomes unbalanced,
As a result, a gap is generated between the electrode plates. Alternatively, as shown in FIG. 5c, when the opening is deformed into a gourd shape as shown in FIG. 5c, and this non-circular spiral electrode body is inserted into an outer can, the electrode tightness near the central through-hole in the longitudinal direction decreases. I do.

As described above, in the case of FIG. 5, the distance between the electrodes becomes non-uniform, a contact failure is likely to occur, and the current density becomes non-uniform. I have.

Next, in the case of the comparative battery X2 shown in FIG.
After pressing on the non-circular spiral electrode, the core 7 having a rectangular cross section is removed, so that the degree of tightness between the electrodes cannot be maintained as in the comparative battery X1.

Even when the core is made of metal and used as it is, the curvature becomes large in the major axis direction of the innermost peripheral portion of the spiral electrode body as shown in FIG. Dropping occurs, resulting in variation and deterioration of cycle performance.

[0038]

According to the present invention, since the hollow metal pipe is arranged in the central through-hole of the spiral electrode body, even if the spiral electrode body is pressed into a non-circular shape, the vicinity of the innermost periphery of the spiral electrode body is kept. The curvature can be reduced, the peeling and falling off of the electrodes can be prevented, and the tightness between the electrodes can be secured by the hollow metal pipe, so that the variation and deterioration of the cycle performance can be prevented. .

Further, since the hollow metal pipe can be used as it is as a current collector, the hollow metal pipe can be used as it is without being pulled out, so that a complicated process is not required and the production efficiency is improved by a simple production process. be able to.

[Brief description of the drawings]

FIG. 1 is a perspective view of a non-circular spiral electrode body of a battery of the present invention.

FIG. 2 is a sectional view of the battery of the present invention.

FIG. 3 is a cycle characteristic diagram of a battery A1 of the present invention and comparative batteries X1 and X2.

FIG. 4a is a cross-sectional view of a spirally wound electrode body of the battery A1 of the present invention before being pressed. b is a cross-sectional view of the spirally wound electrode body of the battery A1 of the present invention after pressure molding.

FIG. 5A is a cross-sectional view of a spiral electrode body of a comparative battery X1 before press molding. b It is sectional drawing of the spiral electrode body after press-molding of the comparative battery X1. c It is sectional drawing of the spiral electrode body after press-molding of comparative battery X1.

FIG. 6A is a cross-sectional view of a spiral electrode body before press-molding a comparative battery X2. b It is sectional drawing of the spiral electrode body after press-molding of comparative battery X2.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Hollow metal pipe 2 ... Spiral electrode body 3 ... Battery outer can 4 ... Sealing body 5 ... Negative electrode terminal plate 6 ... core 7 ... opening A1 ... battery of the present invention X1 ... comparative battery X2 ... comparative battery

──────────────────────────────────────────────────続 き Continuation of front page (72) Nobuhiko Maenishi 2-18-18 Keihanhondori, Moriguchi-shi, Osaka Sanyo Electric Co., Ltd. (56) References JP-A-60-25164 (JP, A) JP-A JP-A-4-17271 (JP, A) JP-A-2-132758 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01M 10/04 H01M 10/12 H01M 10/28 H01M 10 / 40

Claims (2)

(57) [Claims] In a battery, a positive electrode and a negative electrode constitute a spiral electrode body with a separator interposed therebetween, and the spiral electrode body is pressed into a non-circular spiral electrode body. A battery comprising a hollow metal pipe in a part. 2. The battery according to claim 1, wherein a cross-sectional shape of the outer can for accommodating the non-circular spiral electrode body has a rectangular or oval shape.