KR20070054845A - Prismatic battery of improved structure - Google Patents

Abstract

The present invention forms an indentation of an intaglio structure on the bottom surface of the base plate to be mounted on the open top of the battery case, preferably a vertical through hole in both end portions of the upper insulating member mounted between the base plate and the electrode assembly. According to the present invention, it is possible to improve the injection characteristics of the electrolyte and prevent the ejection of the electrolyte during the initial charging process.

Description

Prismatic Battery of Improved Structure

1A is a plan view of the bottom surface of a base plate according to the prior art for use in prismatic batteries;

1B is a plan view and a partial cross-sectional view of a bottom surface of a base plate according to one embodiment in the rectangular battery of the present invention;

2 is a perspective view of an upper insulating member according to one embodiment used in the rectangular battery of the present invention;

3 is a schematic diagram of an assembly process of a square battery according to an embodiment of the present invention.

The present invention relates to an improved rectangular battery, and more particularly, to form an indentation of an intaglio structure on the bottom surface of the base plate mounted on the open top of the battery case, preferably between the base plate and the electrode assembly It relates to a rectangular battery consisting of perforating vertical through-holes on both side end portions of the upper insulating member mounted to.

As technology development and demand for mobile devices increase, the demand for secondary batteries as an energy source is rapidly increasing, and accordingly, a lot of researches on batteries that can meet various demands have been conducted.

Typically, there is a high demand for lithium secondary batteries such as high energy density, discharge voltage, and output stability lithium ion polymer battery in terms of battery material. There is a high demand for square batteries and pouch-type batteries that can also be used as batteries of stacked battery modules.

An electrode assembly in which a battery reaction occurs in a secondary battery generally has a structure in which an electrolyte solution is impregnated into a cathode plate coated with a cathode active material, an anode plate coated with an anode active material, and a separator. The electrode assembly of the secondary battery is classified into a jelly-roll type (wound) electrode assembly and a stacked type (laminated) electrode assembly according to its structure. Thus, a rectangular battery is produced by storing a jelly-roll type electrode assembly or a stacked type electrode assembly in a rectangular metal case.

In general, a rectangular battery is subjected to an assembly process in which an electrode assembly is mounted inside a rectangular metal can and an upper insulator is mounted on an open upper end thereof, and then the base plate is welded on it, followed by an injection of an electrolyte to seal it. At this time, a predetermined amount of electrolyte is injected and primary charging is performed to activate the battery without sealing the injection port, and after the electrolyte is injected again, the secondary charging is performed.

In general, during the injection of the electrolyte, the diameter of the injection hole is narrow, so that the injection of the electrolyte is not smooth. In the process of the primary charging, a gas or the like is ejected from the electrode assembly, causing the electrolyte to flow over the injection hole.

In order to solve this problem, Korean Patent Registration No. 0484115 has an injection hole corresponding to the electrolyte injection hole formed in the upper insulator and a channel is provided to facilitate the injection of the electrolyte solution around the upper insulator. 0436714 proposes a structure in which injection holes for injecting electrolyte solutions are provided on both sides of the upper insulator, and a slope is provided to allow the electrolyte to flow into the injection holes. In addition, Korean Utility Model Registration No. 0184429 proposes a structure in which a recess is formed to be concave around the electrode member formed at the center of the battery lid body.

However, the above techniques serve to guide the inflow path of the electrolyte, thereby facilitating the inflow, but do not increase the injection amount per unit time. In addition, the above techniques focus only on improving electrolyte injection characteristics, and do not solve a phenomenon in which an electrolyte flows out of an injection hole by ejecting a gas or the like during the first filling process.

In this regard, Korean Patent No. 0319111 discloses a gas outlet on a cap plate and a suction tube extending upward from an insulator to prevent the volume expansion of the battery due to the gas generated during the initial charging of the assembled secondary battery. It suggests a technique configured to communicate with an outlet.

The patent is generally due to the low impregnation of the polar electrolyte to the non-polar cathode carbon material of the negative electrode in the process of the substantial amount of the electrolyte sequentially descends along the electrode assembly during the initial injection of the electrolyte, so that some of the electrolyte flows back through the suction tube Rather, there is a serious problem in terms of injection of the electrolyte. Moreover, the patent has a problem that the manufacturing process of the battery is very complicated, such as the need for the manufacture of an insulator including a suction tube and precisely matching a small suction tube to the gas outlet during the assembly of the battery.

Therefore, the injection of the electrolyte is easy and there is a high need for a technology that can prevent the phenomenon that the electrolyte flows over the inlet in the initial charging process for the activation of the battery.

The present invention aims to solve the problems of the prior art as described above and the technical problems that have been requested from the past.

After repeated studies and various experiments, the inventors have formed an indentation of an intaglio structure on the bottom surface of the base plate mounted on the open top of the battery case, preferably an upper portion mounted between the base plate and the electrode assembly. In the case of drilling the vertical through-holes at both end portions of the insulating member, despite the simple structure, the electrolyte is more easily injected, and the indentation and the through-holes serve as a receiving space of the electrolyte, thereby initial charging for battery activation. It was confirmed that the electrolyte solution can be prevented from overflowing in the process, and came to complete the present invention.

Accordingly, the prismatic battery according to the present invention is a battery in which an electrode assembly is incorporated in a prismatic battery case, and an indentation portion having an intaglio structure for accommodating an electrolyte solution is formed on a lower surface of a base plate mounted on an open upper end of the case. It consists of a structure.

The base plate has a substantially plate-like structure, and the engraved indentation is concave on the bottom surface (inner surface) of the base plate without being protruded upward. The inventors were able to confirm that, as in the experimental example described below, the electrolyte that was ejected into the electrolyte inlet by the gas generated from the electrode assembly during the initial charging process for battery activation was remarkably suppressed by the indentation. . This is presumably because the indentation portion formed on the bottom surface of the base plate is sufficiently attained as a damping zone for accommodating the electrolyte even though the depth of the intaglio indentation formed by the base plate itself is limited. Therefore, the square battery according to the present invention can solve the problems occurring in the battery as in the prior art despite the simple structure.

Such engraved indentations have a depth of 10 to 50%, preferably 20 to 30%, based on the thickness of the base plate, so as not to substantially cause the base plate to lose strength while exhibiting the above effects. Preferably, the area thereof is formed to a size of 20 to 60%, preferably 30 to 40%, based on the total area of the bottom surface of the base plate. If the depth of the indentation is too shallow or the formation area is too small, the above effects are difficult to expect. On the contrary, if the depth is too deep or the formation area is too wide, the strength of the base plate may be deteriorated.

In general, a rectangular battery is provided with a member (top insulator) for insulation between the electrode assembly and the base plate. According to the present invention, a predetermined vertical through hole may be formed in the insulating member in a preferred embodiment so as to more easily inject the electrolyte into the battery case and further suppress the ejection of the electrolyte during the initial charging process for battery activation. .

In a specific example, the insulating member may have a structure in which downward protruding supports are formed at both end portions of the plate-shaped body corresponding to the horizontal inner surface structure of the battery case, and vertical through holes are formed in the protruding support.

The vertical through hole of the insulating member not only provides a flow path in which the electrolyte falls in the direction of the electrode assembly when the electrolyte is injected, but also serves as an additional accommodation space of the electrolyte. The area of the vertical through hole is preferably formed in a size of 20 to 70%, preferably 30 to 40% based on the horizontal cross-sectional area of the protruding support of the insulating member.

Since other components, such as an electrode assembly constituting the prismatic battery according to the present invention, are known in the art, a detailed description thereof will be omitted herein.

Hereinafter, the content of the present invention will be described with reference to the drawings, but the scope of the present invention is not limited thereto.

Figure 1a is a plan view of the bottom surface of the base plate according to the prior art used for the square battery, Figure 1b is a plan view and a partial cross-sectional view of the bottom surface of the base plate according to an embodiment of the present invention. It is.

First, referring to FIG. 1A, the base plate 100 is made of a metal plate such as aluminum or stainless steel, and the protruding terminal connecting member 110 is electrically insulated by a gasket 120 of an insulating material in the center. Formed from. The connection member 110 is welded to the cathode of the electrode assembly (not shown), the anode of the electrode assembly is welded to the base plate 100 itself.

The electrolyte injection hole 130 is perforated on one side of the base plate 100, and the electrolyte injection hole 130 is opened in a state in which the base plate 100 is coupled to an open upper end of a metal can (not shown) incorporating an electrode assembly. The electrolyte is injected through.

According to the present invention, the base plate 100 of such a structure includes a negative electrode indentation 200 as shown in Figure 1b. A plurality of indents 200 are formed at a predetermined depth from the bottom surface of the base plate 200. The indented indentation 200 serves as an accommodation space of the electrolyte during the initial charging process for battery activation to prevent the electrolyte from being ejected to the outside through the electrolyte inlet 130.

Figure 2 is a perspective view of the upper insulating member according to one embodiment used in the square battery of the present invention.

Referring to FIG. 2, the upper insulating member 300 has a plate-shaped body 310 corresponding to a horizontal inner surface structure of a battery case (not shown) and a downwardly protruding support portion 320 formed at both end portions thereof. Consists of The plate-shaped body 310 is formed with a pair of openings 330 into which an anode and a cathode of an electrode assembly (not shown) may be inserted, respectively. The positive and negative electrodes inserted through the opening 330 are connected by welding to the corresponding portions of the base plate of FIG. 1B. The opening 330 also serves as a flow path when the electrolyte is injected.

Protruding support 320 is formed with a vertical through hole 340 of a predetermined size, such a vertical through hole 340 facilitates the injection of the electrolyte into the battery case and in the initial charging process to activate the battery It serves to further suppress the ejection of the electrolyte.

3 schematically shows an assembly process of a square battery according to an embodiment of the present invention.

The electrode assembly 410 is inserted into the rectangular metal can 400 in such a manner that the positive electrode 412 and the negative electrode 414 protrude upward. The electrode assembly 410 is made by winding the positive electrode sheet and the negative electrode sheet in a state in which a separator is interposed therebetween, and then compressing the electrode assembly 410 into a rectangular shape.

The upper insulating member 300 is mounted on the upper end of the electrode assembly 410 with both protruding supports 320 facing downward. In this mounting process, the anode 412 and the cathode 414 of the electrode assembly 410 are inserted into the opening 330 to protrude from the insulating member 300.

The base plate 100 is coupled to the top of the metal can 400 by welding in a state where the upper insulating member 300 is mounted.

After the assembly process is completed, a predetermined amount of electrolyte is injected through the electrolyte injection hole 130, and after the initial charging, the electrolyte is replenished, and the electrolyte injection hole 130 is sealed to complete the rectangular battery.

Hereinafter, the experimental content for confirming the effect of the present invention will be described, of course, the scope of the present invention is not limited thereto.

Example 1

1-1. Manufacture of anode

95% by weight of LiCoO ₂ , 2.5% by weight of Super-P (conductor) and 2.5% by weight of PVdF (binder) were added to NMP (N-methyl-2-pyrrolidone) as a positive electrode active material to prepare a positive electrode mixture slurry. The positive electrode was prepared by coating, drying and pressing on aluminum foil.

1-2. Preparation of Cathode

95% by weight of artificial graphite, 2.5% by weight of Super-P (conductor) and 2.5% by weight of PVdF (binder) were added to NMP as a solvent to prepare a negative electrode mixture slurry, which was then coated and dried on copper foil. And pressed to prepare a negative electrode.

1-3. Coupling the Battery Assembly

As a separator, Celgard ^TM is used, and the electrode sheet laminate in which the anode of 1-1, the cathode of 1-2 and the separator are sequentially wound is wound to make a jelly-roll, and then compressed to form a jelly-roll. Likewise inserted into a rectangular metal can. An upper insulating member was mounted on the electrode assembly, and a rectangular battery was assembled by combining a base plate as shown in FIG. 1B with an open upper end of the can. The base plate has an indentation indentation of an average depth of about 0.15 mm, with a size of approximately 35% based on the total area of its bottom surface.

1-4. Electrolyte Filling and Inlet Sealing

1M LiPF ₆ and 2.05 ± 0.1 g of EC / EMC electrolyte are injected, and primary charging is performed under conditions of approximately 1/6 C charge capacity to activate the battery, and then the electrolyte is replenished and the electrolyte inlet is sealed to form a rectangular secondary battery. Prepared.

Example 2

A secondary battery was manufactured in the same manner as in Example 1, except for using an upper insulating member having a vertical through hole formed therein as shown in FIG. 2. The upper insulating member has a through hole having a size of 1.4 ± 0.2 on the protruding support.

Comparative Example 1

A secondary battery was manufactured in the same manner as in Example 1, except for using the same base plate as in FIG. 1A and using an upper insulation member having no vertical through hole formed in the protruding support in FIG. 2. It was.

 Experimental Example 1

For each of the batteries prepared in Example 1 and Comparative Examples 1 and 2, it was observed whether the electrolyte is ejected over the injection port during the initial primary charging process, the results are shown in Table 1 below.

As shown in Table 1, the battery manufactured according to the prior art (Comparative Example 1) shows a defect rate close to 60%, but the battery formed a negative size indentation of the predetermined size on the base plate according to the present invention shows a low failure rate In addition, the battery (Example 2) having an indentation portion formed in the base plate and a through hole formed in the upper insulating member showed no defect sample at all, thereby confirming that the backflow phenomenon of the electrolyte was remarkably suppressed with the improvement of the electrolyte injection characteristics. Can be.

As described above, the rectangular secondary battery according to the present invention forms an indentation of an intaglio structure formed on the inner surface of the base plate, preferably by forming a vertical through hole in the upper insulating member mounted between the electrode assembly and the base plate, The injection characteristics of the electrolyte are improved and the activation of the battery has an effect of preventing the ejection of the electrolyte during the initial charging process.

Those skilled in the art to which the present invention pertains will be able to perform various applications and modifications within the scope of the present invention based on the above contents.

Claims (6)

A battery in which an electrode assembly is incorporated in a rectangular battery case, and a rectangular battery having an indentation portion having an engraved structure for accommodating an electrolyte solution is formed on a lower surface of a base plate mounted on an open upper end of the case. According to claim 1, wherein the insulating member is mounted between the electrode assembly and the base plate, the insulating member is provided with downward projecting support portions at both ends of the plate-shaped body corresponding to the horizontal inner surface structure of the battery case, the projecting support portion The rectangular battery characterized in that the vertical through-hole is formed. The prismatic battery of claim 1, wherein the indentation portion is formed to a depth of 10 to 50% based on the thickness of the base plate. According to claim 1, wherein the negative indentation is based on the entire area of the bottom surface of the base plate A rectangular battery, which is formed with an area of 20 to 60%. The rectangular battery according to claim 2, wherein the through part is formed in a size of 20 to 70% based on a horizontal cross-sectional area of the protruding support part. The method according to claim 1 or 2, wherein the electrode assembly is inserted into the battery case, the insulating member is mounted on the electrode assembly, the base plate is coupled to the open top of the battery case, and then a predetermined amount of electrolyte is injected. A rectangular battery comprising: applying a current to activate the battery, replenishing the electrolyte, and sealing the electrolyte inlet;

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