JP2001283894A - Cylindrical battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cylindrical battery that can promptly discharge gas generated in the electrode body from the electrode body. SOLUTION: The cylindrical battery comprises an electrode body 12, which has a separator 18 held between a positive electrode plate 14 and a negative electrode plate 16 housed wound in a whirlpool state together with an electrolyte in the cylindrical bottomed battery packaging can 30. In an opening 13 formed in the center of the winding core of the electrode body 12 wound in a whirlpool shape, a metal foil 40 of which both ends are rounded in a state of overlapping in cylindrical shape is inserted. And part of the outer circumference of the metal foil 40 contacts the innermost circumference of the electrode body 12. And the diameter of the rounded metal foil 40 is made variable to change according to the change of the size of the opening 13 due to swell and contraction of the electrode body 12.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cylindrical or rectangular cylindrical battery, and more specifically, to a hole formed at the center of the winding of the electrode body even if the electrode body expands or contracts. To
The present invention relates to a cylindrical battery which can be secured as a gas vent hole.

[0002]

2. Description of the Related Art A sealed secondary battery such as a non-aqueous electrolyte secondary battery such as a lithium ion battery or an alkaline storage battery such as a nickel-hydride battery is known. These secondary batteries are manufactured in a cylindrical shape such as a cylindrical shape or a cylindrical shape, or in a shape such as a coin shape in response to a request for a device to be mounted. The cylindrical battery (10) will be described with reference to FIG. 1 of the present invention. A negative electrode current collector (22), an electrode body (12) and a positive electrode current collector are provided in a bottomed cylindrical metal battery outer can (30). The electric body (20) is housed together with the electrolytic solution, and the opening of the outer can (30) is sealed with a sealing body (80). As shown in FIG. 1, the electrode body (12) is formed by spirally winding an ion-permeable separator (18) between a positive electrode plate (14) and a negative electrode plate (16). .

[0003] In these secondary batteries, when they are charged or discharged or when they are heated from the outside, the electrolytic solution and the like are decomposed, and gas is generated inside the electrode body (12). When the generated gas accumulates inside the electrode body (12), ion conduction between the electrode plates (14) and (16) is hindered, which leads to deterioration in charge / discharge characteristics such as capacity deterioration accompanying a charge / discharge cycle. I will. Therefore, a part of the gas generated in the electrode body (12) is led to the hole (13), which is the winding center of the electrode body (12), and when the gas pressure exceeds a predetermined value,
The safety valve device (60) formed in the sealing body (80) discharges to the outside.

[0004]

If the battery (10) generates heat due to overcharging or the battery (10) receives strong external heating, the electrode plates (14) and (16) expand. However, in the spirally wound state, the outer peripheral side (winding end side) can hardly be extended due to the regulation by the battery outer can (30). The end of extends toward the center of the winding. For this reason, the central hole (13), which is to be a hole for degassing, is closed, and it becomes difficult to transmit gas,
Gas generated inside the electrode body (12) cannot be guided to the safety valve device (60). As a result, there is a problem that not only the charge / discharge characteristics of the battery (10) are deteriorated, but also the deformation of the outer can (30) such as swelling is caused by the gas that has lost its place.

An object of the present invention is to provide a cylindrical battery capable of rapidly discharging gas generated in an electrode body from the electrode body.

[0006]

Means for Solving the Problems To solve the above problems, a cylindrical battery (10) of the present invention comprises a bottomed cylindrical battery outer can (3).
(0), a cylindrical battery in which an electrode body (12) in which a separator (18) is interposed between a positive electrode plate (14) and a negative electrode plate (16) is spirally wound and accommodated together with an electrolyte solution In the hole (13) formed at the center of the spirally wound electrode body (12), a metal foil (40) that is rolled into a cylindrical shape so that both ends overlap.
Is inserted, the metal foil (40) has a part of the outer periphery of the electrode body (12).
The diameter of the rounded metal foil (40) can be changed according to the change in the size of the hole (13) due to the expansion and contraction of the electrode body (12) It is what it was.

[0007]

Function and Effect When the cylindrical battery (10) of the present invention is charged, the electrode body (12) expands slowly. Electrode body
In (12), the outer periphery expands toward the outer can (30) due to expansion, but when the outer periphery hits the outer can (30), it cannot be further extended outward, so it is then extended to the inner periphery. Then, the diameter of the center hole (13) is gradually reduced. In such a case, the winding of the metal foil (40) proceeds from the state of FIG. 2 and the curvature increases as shown in FIG. Also in this case, since a cylindrical space exists in the center of the rounded metal foil (40), gas generated from the electrode body (12) during charging passes through the electrode body (12) through the cylindrical space. Released from). When discharging is performed after charging, the expanded electrode body (12) contracts slowly, and the center hole (13) of the electrode body (12) gradually expands in diameter.
The rounded metal foil (40), depending on the diameter of the center hole (13),
As shown in FIG. 2, the curvature is reduced by rewinding,
It gradually spreads and restores. The gas generated from the electrode body (12) due to the discharge is, as described above, a rounded metal foil (40).
Are emitted from the electrode body (12) through the central cylindrical space of the electrode.

When the battery (10) receives external heating or the like,
When the electrode body (12) expands rapidly, the electrode body (12) expands in diameter toward the outer peripheral side, and when the outer periphery hits the outer can (30), it expands toward the inner peripheral side to form the center hole (13). To reduce the diameter. Electrode body (12)
When the electrode rapidly expands, the diameter of the center hole (13) does not progress gently, and the electrode body (12) swells rapidly toward the center of the center hole (13). In such a case, the metal foil (40) does not proceed as described above, but is crushed non-uniformly at once by the electrode body (12) as shown in FIG. Metal foil
Even if (40) is crushed unevenly, a gap serving as a passage for discharging gas generated from the electrode body (12) is secured, so the generated gas stays in the electrode body (12). Never.

According to the cylindrical battery (10) of the present invention, even if the electrode body (12) expands due to charging / discharging or heating, the air permeability of the center hole (13) of the electrode body (12) does not increase. As a result, the gas generated from the electrode body (12) can be reliably guided to the safety valve device (60), and the deterioration of the charge and discharge characteristics due to the stagnation of the gas and the rupture of the battery due to the generated gas can be prevented. .

[0010]

DETAILED DESCRIPTION OF THE INVENTION The present invention is suitable for a secondary battery, specifically, a non-aqueous electrolyte secondary battery such as a lithium ion battery, and an alkaline storage battery such as a nickel-cadmium storage battery and a nickel-hydride storage battery. Can be applied to

FIG. 1 is a perspective view showing a cross section of a part of a cylindrical battery (10) of the present invention. As shown in FIG. 1, the cylindrical battery (10) of the present invention is a winding center of a spiral electrode body (12) housed inside a metal bottomed cylindrical outer can (30). The metal foil (40) is inserted into the hole (13) in a rounded state.

The electrode body (12) is composed of a positive electrode plate (14) and a negative electrode plate (16) obtained by applying a positive electrode active material and a negative electrode active material to a core of a conductive electrode plate such as a copper foil, respectively. It is manufactured by spirally winding with (18) interposed. The fabricated electrode body (1
The hole (1) is located in the center of the electrode body (12), where
3) is formed. The inner surface of the hole (13), that is, the electrode body (18)
Depending on the winding method, the positive electrode plate (14) and the negative electrode plate
(16) or a separator (18).

A metal foil (40), which is rounded so that both ends overlap, is inserted into the center hole (13) of the electrode body (12). Metal foil
(40) is formed from a flexible material and has a thickness of 0.02 mm or more.
It is desirable to set it to 0.15 mm. If the thickness of the metal foil (40) exceeds 0.15 mm, it is not possible to cope with the change in curvature due to the diameter reduction of the center hole (13).
If the metal foil (40) is reduced in diameter, the metal foil (40) is plastically deformed as it is, and even if the electrode body (12) shrinks and the center hole (13) expands again, the metal foil (40) is restored. This is because it may not be done. If the thickness of the metal foil (40) is less than 0.02 mm, the strength is low and the effect of inserting the metal foil (40) may not be sufficiently obtained. The length of the metal foil (40) is the same as or slightly shorter than the length of the electrode body (12). As the metal foil (40), a metal having a melting point higher than the heat generation temperature of the battery (10), for example, stainless steel, aluminum, copper or the like is suitably used. In the case of stainless steel (SUS304), the desirable thickness is 0.07 mm, and in the case of aluminum, the desirable thickness is 0.1 mm.
For copper, the desired thickness is 0.05 mm.

The electrode body (12) in which the metal foil (40) is inserted into the center hole (13) is housed in an outer can (30) in a known manner, and the negative electrode plate (16) is attached to the negative electrode plate. After electrically connecting to the outer can (30) via the current collector (22) and injecting the electrolyte, the positive electrode plate (14) is connected to the safety valve device (60) via the positive electrode current collector (20). Equipped sealing body
After connecting to (80), an insulating gasket (70) is attached to the outer periphery of the edge of the sealing body (80), and the opening end of the outer can (30) is bent to secure the sealing body (80) by caulking. Thus, the cylindrical battery (10) shown in FIG. 1 is manufactured. In the produced battery (10), the sealing body (80) serves as a positive electrode terminal, and the outer can (30) serves as a negative electrode terminal.

In the case of a prismatic battery, the electrode body (12) is housed in a rectangular outer can (30) in a state where it is squashed in a flat state. A metal foil (40) that has been rounded so that both ends thereof overlap with the center hole (13) may be inserted.

[0016]

EXAMPLE Inventive battery (10) in which metal foil (40) was inserted into center hole (13) of electrode body (12) and Comparative Example in which metal foil (40) was not inserted in center hole (13) Each of the batteries was manufactured and the state of the battery when rapidly heated from the outside was compared.

The electrode body (12) is formed by winding a negative electrode plate (16) mainly composed of carbon and a positive electrode plate (14) mainly composed of cobalt oxide via a separator (18) in both the invention example and the comparative example. It was made by turning.

In the invention example, a stainless steel (SUS304) foil having a thickness of 0.07 mm was rolled and inserted into the manufactured electrode body (12).

Batteries incorporating the obtained electrode assembly were prepared for each of the invention examples and the comparative examples, five cells at a time.

<< Measurement Conditions >> In a normal ion battery, the charging voltage is set to 4.2V. In this embodiment, assuming an abnormal state, a battery with a charging voltage of 4.3 V
It was placed on a hot plate heated to 50 ° C., and the progress up to combustion was compared.

<< Measurement Results >> In the invention example, after a short time from the start of heating, the safety valve device was activated, and the gas continued to be ejected, and after a certain period of time, the ejection of the gas was terminated. After the heating was completed, the battery of the invention example was disassembled and the condition of the electrode body was examined. As shown in FIG. 4, the metal foil (40) was unevenly crushed. Was in a state of existence. That is, the gas generated in the electrode body is
It can be seen that the gas is securely guided to the safety valve device through the gap formed by the metal foil (40). On the other hand, in the comparative example, a short time after the start of heating, the safety valve device was operated and gas was ejected, but immediately, gas ejection was stopped, and 4 cells out of 5 cells burst. This is because the center hole is closed by the expansion of the electrode body, and the generated gas is not guided to the safety valve device but stays in the electrode body.

The same measurement as above was carried out using an aluminum foil having a thickness of 0.1 mm as the metal foil, and one of the five cells burst. However, it can be seen that the characteristics are significantly improved as compared with the comparative example. When the charging voltage was reduced to 4.27 V, there was no battery that could burst due to only gas ejection.

Similarly, for the comparative example, the charging voltage was set to 4.
When the voltage was lowered to 27 V, three cells out of five cells still burst.

The description of the above embodiments is for the purpose of illustrating the present invention and should not be construed as limiting the invention described in the appended claims or reducing the scope thereof. Further, the configuration of each part of the present invention is not limited to the above embodiment, and various modifications can be made within the technical scope described in the claims.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a tubular battery according to the present invention in a longitudinal section.

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

FIG. 3 is a cross-sectional view of the cylindrical battery showing a state in which the electrode body is gradually expanded.

FIG. 4 is a cross-sectional view of the tubular battery showing a state where the electrode body has rapidly expanded.

[Explanation of symbols]

 (10) Cylindrical battery (12) Electrode body (13) Center hole (30) Outer can (40) Metal foil

Claims (1)

[Claims] An electrode body (12) having a separator (18) interposed between a positive electrode plate (14) and a negative electrode plate (16) is swirled inside a bottomed cylindrical battery outer can (30). In a cylindrical battery wound in a spiral shape and housed with an electrolytic solution, a cylindrical shape is formed such that both ends overlap with a hole (13) formed in the center of the spirally wound electrode body (12). A rounded metal foil (40) is inserted into the metal foil (40), and a part of the outer circumference of the metal foil (40) is in contact with the innermost peripheral surface of the electrode body (12). A cylindrical battery characterized in that the diameter can be changed in accordance with a change in the size of the hole (13) due to expansion and contraction of the electrode body (12).