JP2002008634A - Battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a battery in which an electrolytic solution can be rapidly and surely filled up inside of a battery element 1 by injecting the electrolytic solution from not less than solution intake ports 5 into a unit battery case. SOLUTION: At a single battery case composed of a battery can 2 to house a battery element 1 and a cap plate 3 to occlude an opening part of this battery can 2, the solution intake ports 5 are installed at not less than two places.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a battery in which a battery element is housed in a unit cell case, an electrolyte is injected therein, and the battery is sealed.

[0002]

2. Description of the Related Art FIG. 6 shows an example of the structure of a conventional prismatic lithium ion secondary battery. This lithium ion secondary battery is assembled by storing a long cylindrical wound battery element 1 in a battery box 2 in the shape of an elongated box, and closing an opening of the battery can 2 with a cover plate 3. . The battery element 1 is formed by winding belt-like positive and negative electrodes into a long cylindrical shape via a separator. The battery can 2 is formed by forming a metal plate such as an aluminum plate, a stainless steel plate, or an iron plate into an elongated box-like container shape.
Insert The cover plate 3 is a rectangular metal plate made of the same material as the battery can 2, and is fitted into the opening of the battery can 2 and welded around the battery can 2, as shown in FIG. A unit cell case composed of the plate 3 is formed. In addition,
In this structural example, one terminal 4 is attached to the center of the cover plate 3. The terminal 4 penetrates through the front and back surfaces of the cover plate 3, and is attached to the cover plate 3 by insulation sealing.
It is connected to a tag-like lead 1a drawn from either the positive or negative electrode of the battery element 1 inside the unit cell case. Further, the other electrode of the battery element 1 is internally contact-collected with the battery can 2, and the cell case itself becomes the other terminal.

The lid plate 3 is provided with one liquid inlet 5. The liquid injection port 5 is a small-diameter through hole penetrating the cover plate 3. The lithium ion secondary battery assembled by fitting the cover plate 3 into the battery can 2 and welding is placed in a vacuum chamber and evacuated, and the liquid is discharged from the inlet 5 in a substantially vacuum atmosphere. The electrolyte is injected. The reason for injecting the electrolyte in a vacuum is that if air remains between the electrodes of the battery element 1, the electrolyte that has penetrated here surrounds the periphery, so that the air escapes and the air escapes. This is because there is a possibility that the liquid will collect and remain between the electrodes. When the injection of the electrolytic solution is completed, the injection port 5
Is sealed by laser welding or the like. Injection port 5
May be provided at one place on the side surface of the battery can 2 instead of the cover plate 3.

[0004]

However, in the conventional lithium ion secondary battery, only one injection port 5 is provided in the cover plate 3 of the unit cell case or the like. The electrolyte is injected only from one injection port 5, so that the entire battery element 1 is not sufficiently filled with the electrolytic solution, which may cause unevenness. Then,
Lithium electrodeposition occurs on a part of the electrode during charging, so that a problem such as the discharge capacity may not reach the rated value in the capacity test has occurred.

[0005] Since the battery element 1 is formed by winding the positive and negative electrodes very densely many times, the electrolyte gradually permeates into the separator between the positive and negative electrodes. For this reason, when the electrolyte is injected only from one injection port 5, the electrolyte permeates only from a specific location of the battery element 1, so that the electrolyte flows into the entire battery element 1. It takes an extremely long time to completely fill around. Therefore, charging must be started before the electrolyte is sufficiently filled,
Since the portion of the electrode that is not filled with the electrolyte is not charged, the amount of lithium ions absorbed is biased and lithium electrodeposition occurs, so that the discharge capacity does not reach a predetermined value.

The above problem is particularly remarkable in a non-aqueous electrolyte battery such as a lithium ion secondary battery using a non-aqueous electrolyte having a relatively high viscosity. The same problem that the electrolyte is not sufficiently filled in the battery element 1 due to the presence of only one injection port 5 may occur.

The present invention has been made in order to cope with such a situation. By providing two or more liquid inlets in a single cell case, an electrolytic solution is injected from a plurality of positions to sufficiently fill a battery element. It is an object to provide a battery that can be filled.

[0008]

According to a first aspect of the present invention, there is provided a battery cell in which two or more liquid inlets are provided in a unit cell case which houses and seals a battery element therein.

According to the first aspect of the present invention, since the electrolyte can be injected from two or more injection ports of the single cell case, the electrolyte penetrates into the inside of the battery element from a plurality of locations and is sufficiently provided in a short time. As a result, it is possible to prevent inconveniences such as a decrease in discharge capacity.

The present invention is particularly suitable for non-aqueous electrolyte batteries such as lithium ion secondary batteries. The non-aqueous electrolyte used by the non-aqueous electrolyte battery has a higher viscosity than the aqueous electrolyte, and therefore requires a particularly long time for penetration into the battery element. Further, as a result, when an unfilled portion of the electrolyte solution is generated in the battery element, the discharge capacity may be reduced due to the growth of lithium electrodeposition accompanying charge and discharge. The present invention can solve these problems by making the permeation of the electrolytic solution be performed quickly.

According to a second aspect of the present invention, the two or more liquid inlets are provided on a surface of the unit cell case facing a surface of the battery element on which an edge of the overlapping electrode is exposed. It is characterized by.

According to the second aspect of the present invention, since the electrolyte injected from the injection port is supplied to the surface of the battery element on the side where the overlapped electrodes are exposed, the electrode overlaps the electrodes. It can be made to penetrate smoothly between. In addition, in the case of a wound type battery element, the surface on the side where the edge of the overlapped electrode is exposed is:
It refers to both end surfaces such as a cylindrical shape and a long cylindrical shape that are orthogonal to the winding axis, and in the case of a stacked battery element, it refers to the peripheral side surface in the stacking direction.

[0013]

Embodiments of the present invention will be described below with reference to the drawings.

1 to 5 show an embodiment of the present invention. FIG. 1 is a perspective view of a lithium ion secondary battery having two liquid inlets in a battery lid, and FIG. FIG. 3 is a perspective view of a lithium ion secondary battery provided with two liquid inlets on a side surface of a can. FIG. 3 is a perspective view of a lithium ion secondary battery provided with one liquid inlet on a side surface of a lid plate and a battery can. FIG. 4 is a perspective view of a lithium-ion secondary battery in which two liquid inlets are provided on a side surface of a battery can into which a wound-type battery element is inserted laterally;
FIG. 5 is a perspective view of a lithium ion secondary battery in which two liquid inlets are provided on a side surface of a battery can into which a stacked battery element is inserted. Components having the same functions as those of the conventional example shown in FIGS. 6 and 7 are denoted by the same reference numerals.

In this embodiment, a rectangular lithium ion secondary battery having the same structure as that of the conventional example will be described. This lithium ion secondary battery is composed of a battery element 1, a battery can 2, and a cover plate 3 having the same structure as that of the conventional example, and here, as shown in FIG. The battery is inserted vertically into the battery can 2. However, in the present embodiment, as shown in FIG. 1, the liquid inlets 5 of the cover plate 3 are not only provided at one position, but are provided at two positions at both ends.
5 are provided. These injection ports 5 and 5 are small-diameter through holes penetrating the plate surface of the lid plate 3.

The lithium-ion secondary battery assembled by fitting the cover plate 3 into the battery can 2 and welding the battery can 2 is first placed in a vacuum chamber. At this time, the lithium ion secondary battery is placed upright so that the cover plate 3 provided with the liquid inlets 5 and 5 faces upward. Next, the inside of the vacuum chamber is evacuated.
Electrolyte is injected from each of the two injection ports 5 and 5.
Here, assuming that the opening diameters of the injection ports 5 and 5 are the same as those of the conventional one injection port 5, respectively, the electrolyte solution is supplied to both the injection ports 5 and 5 at the same speed as the conventional one. Can be injected, so that the entire injection speed can be doubled as compared with the conventional case, and the time required for injection of the electrolyte can be reduced. In addition, if the total injection rate of the electrolyte is the same as the conventional one, the injection rate of the electrolyte to be injected into each of the injection ports 5, 5 can be halved. The opening diameter can be reduced. In addition, since the electrolyte is injected from both ends of the cover plate 3, the electrolyte is poured into both ends of the end faces of the elongated cylindrical battery element 1 where the overlapped electrodes are exposed. It is possible to smoothly and evenly penetrate the entire space between these electrodes, and it is possible to reduce the time required until the entire battery element 1 is filled, as compared with the case where the injection is performed from only one side of this end face. it can. Then, the lithium ion secondary battery is taken out of the chamber, and the liquid inlet 5,
5 are sealed by laser welding or the like to complete the lithium ion secondary battery.

As described above, according to the present embodiment,
Since the electrolytic solution is injected into the inside of the single cell case from the two liquid inlets 5 and 5 provided at both ends of the cover plate 3, the electrolytic solution is sufficiently filled between the electrodes of the battery element 1. The time required for this can be reduced. In addition, since the battery element 1 is sufficiently filled with the electrolytic solution and an unfilled portion of the electrolytic solution does not occur, the discharge capacity does not decrease due to lithium electrodeposition.

In the above embodiment, the case where two liquid inlets 5 and 5 are provided at both ends of the cover plate 3 has been described, but these liquid inlets 5 and 5 are provided inside the battery element 1. As long as the position allows smooth filling of the electrolytic solution, it may be provided in any place of the unit cell case composed of the battery can 2 and the lid plate 3. For example, as shown in FIG. The battery can 2 may be provided at both ends of the side having the smaller area on the side. In this case, since the electrolyte is injected from both ends of the side surface of the battery can 2, the long cylindrical battery element 1 is formed.
The electrolyte solution permeates into the inside from both end faces of the battery element 1, and the time until the entire battery element 1 is filled can be reduced as compared with the case where the electrolyte is injected only from one end face side. . Also, by providing these liquid inlets 5 and 5 at positions substantially equal distance from both ends of the side surface of the battery can 2, the electrolyte can be almost uniformly filled from both end surfaces of the battery element 1. The filling time can be shortened as compared with the case where the filling amount from is large. Further, as shown in FIG. 3, for example, liquid inlets 5 and 5 are provided at one place on the side of the lid plate 3 and the side face of the battery can 2, respectively, and one liquid is injected at one place at each of the open end portions of the opposite sides of the battery can 2. Liquid ports 5 and 5 can also be provided.

However, it is preferable to supply the liquid injection ports 5 and 5 to the surface on the side where the edge of the overlapped electrode is exposed in order to allow the electrode of the battery element 1 to penetrate smoothly and evenly between the electrodes. That is, when the wound battery element 1 is vertically inserted into the battery can 2 as in the present embodiment, the liquid inlets 5 and 5 are provided in the cover plate 3 as shown in FIG. However, as shown in FIG. 4, when the spirally wound battery element 1 is inserted in a transverse direction perpendicular to the winding axis, the ends of the spirally overlapping electrodes in the battery element 1 It is preferable to provide it on the side surface of the battery can 2 facing the exposed end surface. In the case where the battery element 1 is of a stacked type, the battery element 1 may be penetrated from the surface facing the four sides around the sheet-shaped electrode in the stacking direction. In addition to being provided on the side surface of the battery can 2 facing, the battery can also be provided on the cover plate 3 or the bottom surface of the battery can 2.

The number of the liquid injection ports 5 is not limited to two, but may be three or more. However, if the number of the liquid injection ports 5 is too large, the sealing operation becomes troublesome. The sealing of the liquid injection port 5 is not necessarily limited to the method by welding as long as it can prevent leakage of the electrolyte and can seal the inside.

Further, in the above embodiment, the rectangular lithium ion secondary battery has been described. However, the shape of the single cell case is arbitrary, and the present invention can be similarly applied to a cylindrical or long cylindrical battery. . In addition, this cell case,
It is not limited to the one formed by closing the opening of the battery can 2 with the cover plate 3.

Further, in the above embodiment, the lithium ion secondary battery has been described. However, if the battery is a battery in which the battery element 1 is housed in a single cell case and an electrolyte is injected,
The present invention can be similarly applied to any type of secondary battery or primary battery.

[0023]

As is apparent from the above description, according to the battery of the present invention, the electrolytic solution is injected from two or more inlets of the single cell case so that the electrolytic solution can be discharged in a short time. The inside of the element can be sufficiently filled, and it is possible to prevent a decrease in discharge capacity due to generation of an unfilled portion of the electrolytic solution.

[Brief description of the drawings]

FIG. 1, showing one embodiment of the present invention, is a perspective view of a lithium ion secondary battery in which two liquid inlets are provided in a battery lid.

FIG. 2, showing one embodiment of the present invention, is a perspective view of a lithium ion secondary battery in which two liquid inlets are provided on a side surface of a battery can.

FIG. 3, showing one embodiment of the present invention, is a perspective view of a lithium ion secondary battery in which a liquid inlet is provided on each of a lid plate and one side of a battery can.

FIG. 4 shows one embodiment of the present invention, and is a perspective view of a lithium ion secondary battery in which two liquid inlets are provided on a side surface of a battery can into which a wound-type battery element is inserted laterally. It is.

FIG. 5, showing one embodiment of the present invention, is a perspective view of a lithium ion secondary battery in which two liquid inlets are provided on the side of a battery can into which a stacked battery element is inserted.

FIG. 6 is an exploded perspective view showing a conventional example and showing a structure of a lithium ion secondary battery.

FIG. 7 shows a conventional example, and is a perspective view of a lithium ion secondary battery in which one liquid inlet is provided in a lid plate.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Battery element 2 Battery can 3 Cover plate 5 Liquid inlet

Continuation of the front page (72) Inventor Toru Tabuchi 1 Nishinosho Inono Babacho, Kichijoin, Minami-ku, Kyoto-shi, Japan F-term (reference) 5H023 AA03 AS02 CC30 DD01

Claims (2)

[Claims] 1. A battery characterized in that two or more liquid inlets are provided in a unit cell case in which a battery element is housed and hermetically sealed. 2. The battery according to claim 1, wherein the two or more liquid inlets are provided on a surface of the unit cell case facing an end side of the overlapping electrode in the battery element.