JP2005108629A - Sealed battery and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a battery with a small volume of deformation caused by the swelling of a battery can. <P>SOLUTION: The sealed battery 1 with a positive electrode and a negative electrode arranged in opposition with a separator interposed has pressure inside the battery can maintained lower than ambient pressure by making an electrolyte solution overflow from an electrolyte immersion inlet 8 by pressing the wall face of the battery can after immersing the electrolyte solution in the battery can 2 housing battery elements and sealing the electrolyte immersion inlet 8 with a pressing force maintained. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a sealed battery, and more particularly to a sealed battery housed in a prismatic battery can such as a lithium ion battery.

  In battery-operated devices such as notebook computers and mobile phones, a rectangular parallelepiped battery storage unit is generally provided. In such a battery storage unit, there is a problem that an invalid volume increases in a cylindrical battery. Further, since the diameter of the cylindrical battery is limited by the thickness of the battery storage portion, a thin prismatic sealed battery is used instead of the cylindrical battery in a small or thin device. ing.

In a lithium ion secondary battery, a carbonaceous material that is doped or dedoped with lithium ions is used for the negative electrode, and it is known that the battery expands due to gas generation during charging. It has been.
For example, a battery can that has expanded due to charging and has a large thickness can be reduced to some extent as a result of ions being dedoped from the negative electrode when discharged, but does not return to its original thickness. In addition, when charging and discharging are repeated, there is a problem that the battery gradually expands and the thickness of the battery increases.

When the swelling of the battery can increases, the battery that is inserted into the hole-shaped battery housing provided in the device cannot be inserted from the hole, or the battery is attached to the battery mounting part. There was a problem that the lid could not be mounted.
In addition, in a battery that has been treated to increase the thickness of the active material applied to the current collector due to a recent increase in battery capacity, the problem of battery expansion during charging is a larger problem. It was.

  Therefore, there is a problem that an invalid space increases if a space is prepared by predicting the expansion amount in advance so that the battery can be installed in the battery mounting space of the battery-operated device without any problem even after repeated charging / discharging many times. . In addition, in a small device, preparing an invalid space in consideration of the expansion of the battery has been a problem in device design.

  In addition, a method of solving the expansion of the battery element by using a battery can having a large thickness and a large strength is also conceivable. However, using a battery can that is thicker than necessary increases the weight of the battery and accommodates it. In a battery with a small battery element and a small volume, there is a problem in dealing with it by increasing the strength of the battery can.

  In addition, it has been proposed that the electrolytic solution is injected into the battery by reducing the pressure inside the battery from the electrolyte injection port of each battery and then supplying the electrolyte with a pressurized gas. And when pressurizing and supplying the electrolyte solution with pressurized gas, it is proposed to prevent the deformation of the battery can by pressing the wall surface of the battery can (for example, Patent Document 1).

In addition, as a method for injecting a liquid such as an electrolytic solution, the electrolytic solution injection port of the battery can is placed in the unit injection tank with the bottom being located in the unit injection tank, and the pressure in the injection chamber is below atmospheric pressure. An infusion method for injecting an electrolytic solution by maintaining the pressure at atmospheric pressure or a pressure equal to or higher than atmospheric pressure after the pressure has been reduced to a low pressure is proposed (for example, Patent Document 2)
However, in any of these injection methods, the sealing after injection of the electrolytic solution is performed by placing a sealing metal member on the electrolytic solution injection port by laser welding or the like under atmospheric pressure. It was.

FIG. 3 is a diagram illustrating a state in which the inside of a conventional sealed battery is seen through.
A battery element 3 is accommodated inside the battery can 2 of the sealed battery 1 and is sealed in a state where the electrolyte 4 is filled therein. There was an internal space 5 that did not exist.
Moreover, since the sealing of the battery can is performed in an atmospheric pressure atmosphere, the atmosphere under the atmospheric pressure exists inside the battery can.
JP 2001-110400 A JP 2001-196050 A

  An object of the present invention is to provide a sealed battery in which expansion of a battery can caused by expansion of a battery element during charging of the sealed battery and expansion due to generation of gas inside the battery are reduced. .

An object of the present invention is to provide a sealed battery in which a positive electrode and a negative electrode are arranged to face each other with a separator interposed therebetween, and does not have a space in which a gas exists in a battery can containing battery elements, and the internal pressure is large. This can be solved by a sealed battery lower than the atmospheric pressure.
The sealed battery using a battery can made of aluminum or an alloy thereof.
The sealed battery as described above, which is a nonaqueous electrolyte battery.
The sealed battery is a lithium ion battery.

Further, in a manufacturing method of a sealed battery in which a positive electrode and a negative electrode are disposed to face each other with a separator interposed therebetween, an electrolytic solution is injected into a battery can containing battery elements and then the wall surface of the battery can is pressed to perform electrolysis. This is a method for manufacturing a sealed battery in which a liquid is overflowed from an electrolyte solution injection port and the electrolyte solution injection port is sealed in a state where a pressing force is maintained.
The method of manufacturing a sealed battery as described above, wherein the electrolytic solution overflowing from the electrolytic solution pouring port is sucked and removed when the battery can is pressed.

  In the present invention, the battery can is pressed before the sealed battery is sealed to overflow the electrolyte, and the gas is removed from the battery can. Therefore, no gas is present in the battery can after the sealing. In addition, since the wall surface of the battery can is pressed into the inside by the pressure difference between the atmospheric pressure and the inside of the battery can, the battery element housed in the battery can is pressed by the wall surface of the battery can. As a result, generation of gas in the battery can by subsequent charging and expansion of the battery due to expansion of the electrode active material can be reduced, and a sealed battery with good dimensional stability can be obtained.

  In the battery in which the battery can is sealed after the battery element in which the positive electrode and the negative electrode are arranged to face each other with the separator interposed between the battery can and the battery can is sealed, the electrolytic solution is injected into the battery can. After pressing the side surface in the battery can and overflowing the electrolyte from the electrolyte solution injection port, by attaching a sealing member to the electrolyte solution injection port in a state of pressing the side surface, It has been found that it is possible to provide a sealed battery in which a space in which a gas exists is not formed inside the battery.

The present invention will be described below with reference to the drawings.
FIG. 1 is a diagram illustrating a sealed battery according to the present invention.
FIG. 1A is a perspective view of the inside of the sealed battery of the present invention.
In the sealed battery 1, the battery element 3 is housed inside the battery can 2, and the inside of the battery can equipped with the electrode header 7 and the battery header 9 provided with the electrolyte injection port 8 is the electrolyte 4. There is no internal space where gas is present in the upper part of the battery can that is filled and pressed in a pressed state.

  As a result, as shown in FIG. 1B, the wall surface 10 of the battery can 2 is subjected to a pressure difference 6 due to the difference between the atmospheric pressure and the pressure inside the battery can. The battery element 3 is pressed by the wall surface 10 of the battery can 2 as shown in the sectional view cut in the direction.

  And since no gas is present inside, the expansion of the battery can due to the expansion of the internal gas can be prevented even when the temperature rises, and the expansion of the battery due to the expansion of the battery electrode can also be prevented. it can.

FIG. 2 is a diagram for explaining the manufacturing process of the sealed battery of the present invention.
As shown in FIG. 2A, after the battery element is stored in the battery can 2, a battery header 9 having an electrode terminal 7 and an electrolyte injection port 8 is attached to the opening of the battery can 2 and welded. Then, after injecting the electrolytic solution from the electrolytic solution injection port 8, the four wall surfaces 10 of the battery can 2 are pressed and pressed with the bottom surface 11 of the battery can 2 placed on the surface plate 12. Press with tools 13 and 14.

As a result, as shown in FIG. 2B, the pressing force 15 acts on the wall surface 10 of the battery can 2, and the electrolytic solution overflows from the electrolytic solution injection port 8.
As shown in FIG. 2C, the overflowing electrolyte solution is sucked by the electrolyte solution recovery means 16, and the electrolyte solution on the upper surface of the battery header 9 is removed.

  Next, as shown in FIG. 2 (D), with the wall surface of the battery can being pressed, the sealing member 17 is irradiated with a laser 18 in a state in which a sealing member 17 such as a pin or granule is attached to the electrolytic solution injection port 8. The member 17 is welded to the periphery of the electrolyte injection port 8 and sealed.

  When the pressure of the pressing jig is removed, the battery that has been sealed is sealed with the electrolyte filled up to the top, and the battery can has a negative pressure state due to the restoring force of the battery can. Is done.

  In the above description, the case where the side surface of the battery can is pressed with an L-shaped pressing jig and the electrolyte is overflowed to eliminate the internal space has been described, but the pressing member simultaneously presses the side surface of the battery can. If it can do, not only L-shape but a plate-shaped thing may be used.

Alternatively, one may be L-shaped, a battery can may be attached to the corner, and the other may be pressed by a flat member.
Also, the pressing jig is sufficient if it has a size that allows the electrolyte in the battery can to overflow from the electrolyte injection port by pressing the wall surface of the battery can and covers the entire surface. It is not necessary.
On the other hand, the bottom surface of the battery can is preferably held in a platen shape from the viewpoint of preventing the bottom surface of the battery can from bulging when the wall surface of the battery can is pressed.
Examples of the present invention will be described below to explain the present invention.

  A positive electrode formed on an aluminum foil and a negative electrode formed on a copper foil in a battery can made of an aluminum alloy (A3003) having a length of 50.0 mm, a width of 34.0 mm, a thickness of 5.0 mm, and a plate thickness of 0.25 mm After the electrodes were placed in the order of the separator, the positive electrode, the separator, and the negative electrode and wound, the battery element formed into a flat shape was accommodated in a battery can.

A battery header is attached to the opening of the battery can, and LiPF ₆ is added to a mixed solvent consisting of 30 parts by volume of ethylene carbonate and 70 parts by volume of diethyl carbonate from the electrolyte injection port of the battery header so that the concentration is 1.0 mol / l. After injecting the dissolved electrolyte, the battery can is placed on a surface plate and the side surface of the battery can is contacted with the battery surface at a surface of 32.0 mm × 48.0 mm and 5.0 mm × 48. The pressure which made the width | variety between pressing members 34.0 mm and 49.0 mm was applied to two L-shaped pressing members which have a 0-mm surface.

  The electrolytic solution overflowing from the electrolyte solution injection port is removed by the suction means while holding the pressing force by the L-shaped pressing member, and then the sealing member is placed on the electrolyte solution injection port, and laser welding is performed. The sealing member was welded and sealed.

  For the 100 batteries obtained, (a) the thickness of the battery can before pressing, (b) the thickness of the battery can after sealing, (c) the thickness of the battery can after initial charging, and (d) 2 discharges and charging after the initial charging. Each of the battery can thicknesses after the measurement was measured, and the average value is shown in Table 1.

Comparative Example 1
Except for not depressurizing the inside of the battery can, 100 batteries were produced in the same manner as in Example 1, the thickness of the battery can was measured in the same manner as in Example 1, and the results are shown in Table 1.

Table 1
Example 1 Comparative Example 1
(A) Battery can thickness before pressing (mm) 5.15 5.15
(B) Battery can thickness after sealing (mm) 5.02 5.15
(C) Battery can thickness after initial charge (mm) 5.15 5.30
(D) After initial charge (mm) 5.30 5.40

  According to the present invention, after the battery header is attached to the opening of the battery can, the battery can is pressed before the sealing to overflow the electrolyte and the gas is removed from the inside of the battery can. Later, there is no gas in the battery can, and the wall surface of the battery can is pressed inside by the pressure difference between the atmospheric pressure and the inside of the battery can, and the battery element stored in the battery can is pressed by the wall surface of the battery can. Therefore, it is possible to reduce the expansion of the battery due to the generation of gas in the battery can during charging and the expansion of the battery due to the expansion of the electrode active material, and to provide a sealed battery with good dimensional stability. it can.

FIG. 1 is a diagram illustrating a sealed battery according to the present invention. FIG. 2 is a diagram for explaining the manufacturing process of the sealed battery of the present invention. FIG. 3 is a diagram illustrating a state in which the inside of a conventional sealed battery is seen through.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Sealed battery, 2 ... Battery can, 3 ... Battery element, 4 ... Electrolyte, 5 ... Internal space, 6 ... Pressure difference, 7 ... Electrode terminal, 8 ... Electrolyte injection port, 9 ... Battery header, 10 ... Wall surface, 11 ... Bottom surface, 12 ... Surface plate, 13, 14 ... L-shaped pressing jig, 15 ... Pressing force, 16 ... Electrolyte recovery means, 17 ... Sealing member, 18 ... Laser

Claims (2)

In a sealed battery in which a positive electrode and a negative electrode are arranged opposite to each other with a separator interposed therebetween, there is no space in which a gas exists in a battery can containing battery elements, and the internal pressure is lower than atmospheric pressure. A sealed battery. In a manufacturing method of a sealed battery in which a positive electrode and a negative electrode are disposed to face each other with a separator interposed therebetween, an electrolytic solution is injected into a battery can containing battery elements and then the wall surface of the battery can is pressed to apply the electrolytic solution. A method for producing a sealed battery, comprising overflowing an electrolyte solution injection port and sealing the electrolyte solution injection port while maintaining a pressing force.

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