KR100670451B1 - Electrod Assembly and Li Ion Secondary Battery - Google Patents

Abstract

The present invention provides an electrode assembly and a lithium ion secondary battery having the same, wherein the position of the negative electrode tab is spaced apart from the active material layer by a predetermined distance, thereby preventing the electrode assembly from being deformed due to stress applied to the negative electrode tab or excessive heat concentration. A first electrode plate comprising a first uncoated portion at both ends of an electrode current collector for a first electrode plate, and a first active material layer on the electrode current collector for the first electrode plate; A first electrode tab attached to a first uncoated portion of the first electrode plate and protruding a predetermined length; A second electrode plate including a second uncoated portion at both ends of an electrode current collector for a second electrode plate, and a second active material layer on the electrode current collector for the second electrode plate; A second electrode tab attached to a second uncoated portion of the second electrode plate and spaced apart from the second active material layer by a distance of ~~; It is characterized by providing a wound electrode assembly including a separator interposed between the first electrode plate and the second electrode plate to insulate them.

Lithium Ion Secondary Battery, Electrode Tab

Description

Electrode assembly and lithium ion secondary battery having the same {Electrod Assembly and Li Ion Secondary Battery}

1A is a perspective view illustrating a secondary battery according to an embodiment of the present invention.

1B is a cross sectional view along line 1a-1a in FIG.

2A and 2B are views for explaining a lithium secondary battery according to one embodiment of the present invention.

(Explanation of symbols for main parts of drawing)

100; Lithium secondary battery 200; Electrode assembly

210; First electrode plate 211; The first collector

212; A first active material layer 213; First ignorance department

215; First electrode tab 220; Second electrode plate

221; Second current collector 222; Second active material layer

223; Second plain 225; Second electrode tab

230; Separators 241 and 245; Insulation Plate

300; Lithium Ion Secondary Battery Case

310; Side plates 320; Bottom plate

330; Creeping section 340; Beading part

400; Cap assembly 410; Safety vent

420; Printed circuit board 430; Positive temperature element

440; First electrode cap 450; Insulation Gasket

500; Electrolyte

The present invention relates to an electrode assembly and a lithium ion secondary battery having the same, and more particularly, by placing the negative electrode tab at a predetermined distance away from the active material layer, stress is applied to the negative electrode tab or excessive heat is concentrated. The present invention relates to an electrode assembly for preventing the assembly from being deformed and a lithium ion secondary battery having the same.

Recently, compact and lightweight electric / electronic devices such as cellular phones, notebook computers, camcorders, etc. have been actively developed and produced. These portable electric / electronic devices have a battery pack that can be operated in a place where no separate power source is provided. The built-in battery pack includes at least one battery therein for outputting a predetermined level of voltage for driving the portable electric / electronic device for a period of time.

In view of economical aspects, the battery pack employs a secondary battery capable of charging and discharging. Representative secondary batteries include lithium secondary batteries such as nickel-cadmium (Ni-Cd) batteries, nickel-hydrogen (Ni-MH) batteries, lithium (Li) batteries, and lithium ion (Li-ion) batteries.

In particular, the lithium secondary battery has an operating voltage of 3.6 V, which is three times higher than that of a nickel-cadmium battery or a nickel-hydrogen battery, which is widely used as a power source for portable electronic equipment, and is rapidly increasing in terms of high energy density per unit weight. to be.

Such lithium secondary batteries mainly use lithium-based oxides as positive electrode active materials and carbon materials as negative electrode active materials. In general, a battery is classified into a liquid electrolyte battery and a polymer electrolyte battery according to the type of electrolyte, and a battery using a liquid electrolyte is called a lithium ion battery, and a battery using a polymer electrolyte is called a lithium polymer battery. Moreover, although a lithium secondary battery is manufactured in various shapes, typical shapes include cylindrical shape, square shape, and pouch type.

In general, the cylindrical lithium secondary battery is positioned between a positive electrode plate coated with a positive electrode active material, a negative electrode plate coated with a negative electrode active material, and between the positive electrode plate and the negative electrode plate to prevent a short and prevent lithium ions (Li-ion). And an electrode assembly in which a separator capable of moving only is wound, a cylindrical case for a lithium secondary battery accommodating the electrode assembly, and an electrolyte solution injected into the lithium secondary battery case to allow lithium ions to move.

The cylindrical lithium secondary battery is coated with the positive electrode active material and the positive electrode tab is connected to the positive electrode tab, the negative electrode active material is coated, the negative electrode tab is connected to the negative electrode plate and the separator is laminated, and then wound to prepare an electrode assembly.

Thereafter, the electrode assembly is accommodated in the cylindrical case for the lithium secondary battery to prevent the electrode assembly from being separated, the electrolyte is injected into the lithium secondary battery case, and then sealed to complete the cylindrical lithium secondary battery.

However, in the cylindrical lithium secondary battery having the wound electrode assembly as described above, when the negative electrode tab formed on the negative electrode plate of the electrode assembly adheres too close to the active material layer, the cylindrical lithium ion secondary battery is charged and discharged. The stress caused by the expansion of the electrode assembly is applied to the overlapping portion of the negative electrode tab and the active material coating, and the heat generated during charging and discharging is concentrated on the negative electrode tab, which causes deformation of the electrode assembly. have.

An object of the present invention is to solve the above problems of the prior art, the present invention is to position the negative electrode tab to be spaced apart a predetermined distance, so as not to overlap the active material layer end with respect to the wound electrode assembly peripheral distance, An object of the present invention is to provide an electrode assembly and a lithium ion secondary battery having the same, which prevents the electrode assembly from being deformed due to stress or excessive heat being concentrated on the active material layer overlapping the negative electrode tab.

The present invention for achieving the above object is a first electrode plate having a first uncoated portion of both ends of the electrode current collector for the first electrode plate and the first active material layer on the electrode current collector for the first electrode plate; A first electrode tab attached to a first uncoated portion of the first electrode plate and protruding a predetermined length; A second electrode plate including a second uncoated portion at both ends of an electrode current collector for a second electrode plate, and a second active material layer on the electrode current collector for the second electrode plate; A second electrode tab attached to a second uncoated portion of the second electrode plate and spaced apart from the second active material layer by a distance of 5 mm or more; It is characterized by providing a wound electrode assembly including a separator interposed between the first electrode plate and the second electrode plate to insulate them.

In addition, the present invention provides a first electrode plate having a first active material layer and a first non-coating portion, a second electrode plate having a second active material layer and a second non-coating portion, and between the first electrode plate and the second electrode plate. The second electrode tab including a separator interposed therebetween, a first electrode tab and a second electrode tab attached to the first and second non-coating portions are wound at a central angle of 15 degrees or more from the second active material layer. A type electrode assembly; A case surrounding the electrode assembly; It is characterized in that it provides a lithium ion secondary battery comprising a cap assembly is coupled to the case and sealed and the terminal portion is electrically connected to the electrode assembly.

In an embodiment of the present invention, the first electrode plate is a positive electrode plate, the second electrode plate is a negative electrode plate, the distance between the second electrode tab and the first active material layer of the first electrode plate winding end is the It is preferable that it is larger than the distance between a 2nd electrode tab and the 2nd active material layer of the said 2nd electrode plate winding termination part.

In addition, the second electrode tab is preferably spaced apart from the end portion of the first active material layer by at least 5 mm or more.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

In the drawings, like reference numerals refer to like elements.

1A is a perspective view illustrating a rechargeable battery according to an exemplary embodiment of the present invention, and FIG. 1B is a cross-sectional view taken along the line 1a-1a of FIG. 1A.

As illustrated in FIGS. 1A and 1B, the cylindrical lithium secondary battery 100 according to an exemplary embodiment of the present invention includes an electrode assembly 200 that generates a voltage difference during charging and discharging, and accommodates the electrode assembly 200. A cylindrical case 300, a cap assembly 400 assembled on the cylindrical case 300 to prevent the electrode assembly 200 from being separated, and injected into the cylindrical case 300 to the electrode assembly 200. It consists of an electrolyte 500 to enable the movement of lithium ions between.

The electrode assembly 200 may include any one of a positive electrode active material and a negative electrode active material, for example, a first electrode plate 210 coated with a positive electrode active material, another one of the positive electrode active material and the negative electrode active material, for example, a negative electrode active material. A short of the first electrode plate 210 and the second electrode plate 220 is disposed between the coated second electrode plate 220, the first electrode plate 210, and the second electrode plate 220. ) And a separator 230 that allows only lithium ions to move. In addition, the first electrode plate 210, the second electrode plate 220, and the separator 230 are wound in a substantially circular shape and accommodated in the cylindrical case 300. In addition, the first electrode plate 210 is generally made of aluminum (Al) and is bonded to the first electrode tab 215 protruding a predetermined length upward. The second electrode plate 220 is generally made of nickel (Ni), and the second electrode tab 225 protruding to a predetermined length is bonded thereto, but the material of the above is not limited thereto. In addition, upper and lower insulating plates 241 and 245 are further attached to upper and lower portions of the electrode assembly 200 to avoid direct contact with the cap assembly 400 or the cylindrical case 300, respectively.

The cylindrical case 300 has a cylindrical side plate 310 having a predetermined diameter and a predetermined diameter so that the cylindrical electrode assembly 200 can be coupled, and the cylindrical side plate 310 is formed at the lower portion of the cylindrical side plate 310. A lower plate 320 blocking the lower space of the side plate 310 is formed, and an upper portion of the cylindrical side plate 310 is opened to insert the electrode assembly 200. Meanwhile, any one of the first electrode tab 215 and the second electrode tab 225 of the electrode assembly 200 may be disposed at the center of the lower plate 320 of the cylindrical case 300, for example, the second electrode tab ( As the 225 is bonded, the cylindrical case 300 itself serves as the same electrode as the second electrode plate 220, for example, a negative electrode terminal. In addition, the cylindrical case 300 is generally formed of aluminum (Al), iron (Fe) or an alloy thereof. In addition, the cylindrical case 300 has a crimping portion 330 that is bent to one side to press the cap assembly 400 at the top thereof, and is pressed inward to press the cap assembly 400 in the upper direction from the bottom thereof. A recessed beading portion 340 is further formed.

The cap assembly 400 has a conductive safety vent 410 in which the shape of the first electrode tab 215 is welded at the same time, the shape is reversed during overcharging or overheating, and an electrical and mechanical structure on the conductive safety vent 410. Connected to a printed circuit board (PCB) that breaks the circuit when the safety vent 410 is inverted, and is electrically and mechanically connected to an upper portion of the printed circuit board 420 so that the circuit is above a predetermined temperature. The positive temperature element 430 is disconnected, the conductive anode cap 440 is electrically and mechanically connected to the upper portion of the positive temperature element 430 to apply an actual current to the outside, and the safety vent 410 And an insulating gasket 450 that wraps around the sides of the printed circuit board 420, the positive temperature element 430, and the first electrode cap 440, and insulates the ones listed above from the cylindrical case 300.

The electrolyte 500 serves as a moving medium of lithium ions (Li Ion) generated by an electrochemical reaction at the positive and negative electrodes inside the battery during charging and discharging, which is a non-aqueous water mixture of lithium salts and high purity organic solvents. The organic electrolyte may be. In addition, the electrolyte 500 may be a polymer using a polymer electrolyte, and the type of the electrolyte material is not limited thereto.

2A and 2B are views for explaining a lithium secondary battery according to an embodiment of the present invention.

2A and 2B, an electrode assembly 200 of a cylindrical lithium secondary battery 100 according to an embodiment of the present invention may include a first electrode plate 210, a second electrode plate 220, and a separator 230. ) Has a structure each including a strip, and are arranged in the order of the first electrode plate 210, the separator 230, the second electrode plate 220, and the separator 230, and are approximately circular. It is wound up in the jelly-roll type of.

Alternatively, although not shown in the drawing, the first electrode plate 210 and the second electrode plate 220 are each made of one strip, and among the first electrode plate 210 and the second electrode plate 220. One electrode plate is wound in a circular jelly-roll shape in a state in which the separator 230 is formed to surround the electrode plate.

The first electrode plate 210 may be any one of a positive electrode active material and a negative electrode active material on the first electrode plate electrode current collector 211 having excellent conductivity and the first electrode plate electrode current collector 211. A first active material layer 222 including a positive electrode active material is provided. In this case, aluminum (Al) is generally used as the electrode current collector 211 for the first electrode plate, and a chalcogenide compound is used as the cathode active material. For example, LiCoO2, LiMn2O4, LiNiO2, and LiNi1-. Complex metal oxides such as xCoxO 2 (0 <x <1), LiMnO 2, etc. are used, but the material of the present invention is not limited thereto. In addition, the electrode current collector 211 for the first electrode plate includes a region where the first active material layer 212 is not formed at both ends, that is, a first uncoated portion 213, and any one of the first uncoated portions For example, the first electrode tab 215 is attached to the first uncoated portion 213 of the start of winding.

The second electrode plate 220 is formed on the second electrode plate electrode current collector 221 made of a conductive metal thin plate, and the other of the positive electrode active material or the negative electrode active material on the second electrode plate electrode current collector 221. For example, the 2nd active material layer containing a negative electrode active material is provided. In this case, the second electrode plate electrode current collector 221 is generally made of copper (Cu) or nickel (Ni), the negative electrode active material is a carbon (C) -based material, Si, Sn, tin oxide, tin alloy composite ( composite tin alloys), transition metal oxides, lithium metal nitrides or lithium metal oxides, and the like are used, but the present invention is not limited thereto. In addition, the electrode current collector 221 for the second electrode plate includes a region where the second active material layer 222 is not formed at both ends, that is, a second uncoated portion 223, and the second uncoated portion 223. For example, the second electrode tab 225 is attached to the second uncoated portion 223 of the winding end portion, for example.

The separator 230 prevents a short between the positive electrode plate 210 and the negative electrode plate 220 and allows only a charge of the cylindrical lithium secondary battery 100 to move, for example, lithium ions. To do so, but made of any one selected from the group consisting of polyethylene, polypropylene and a copolymer (co-polymer) of polyethylene and polyflopropylene, but the material is not limited in this embodiment. The separator 230 may be formed to be wider than the cathode electrode plate 210 and the cathode electrode plate 220 to prevent a short circuit between the anode electrode plate 210 and the cathode electrode plate 220.

In addition, the positive electrode active material layer 212 and the negative electrode active material layer 222 may be started after the positive electrode plate 210 and the negative electrode plate 220 are wound once. That is, the winding starts at the interface between the plain portions 213 and 223 and the cathode and anode active material layers 212 and 222.

On the other hand, the second electrode tab 225 is attached to be spaced apart from the second active material layer 222 of the second electrode plate 220 by a predetermined distance, the second electrode tab 225 and the first electrode plate ( 210. The distance B between the first active material layer 211 of the winding end is a distance between the second electrode tab 225 and the second active material layer 221 of the second electrode plate 220. Generally larger than A). In this case, the distance A between the second electrode tab 225 and the second active material layer is such that the circumferential distance measured along the outer circumference of the wound jelly roll is 5 mm or more apart. At this time, the circumferential distance is the distance between the electrode layers of the same polarity of the jelly roll, the measurement distance in the same layer, as well as the two electrode plates and the separator laminated structure as one layer, and the adjacent layers within two layers of the jelly roll which is the winding body of this laminated structure. It means the distance measured along the outer periphery between two parts, such as an electrode tab and an active material layer end, in a homogeneous or heterogeneous electrode plate and a separator layer.

The circumferential distance value of the electrode assembly 200 generated when the second electrode tab 225 is 5 mm or less away from the second active material layer when the lithium ion secondary battery 100 is charged and discharged. Stress due to expansion Increases the risk of being applied to the second electrode tab 225, and heat generated during charging and discharging is concentrated on the negative electrode tab 225 to cause deformation of the electrode assembly 200. To prevent it.

In addition, the circumferential distance B between the second electrode tab 225 and the first active material layer 212 of the first electrode plate 210 should also be 5 mm or more at the same time, and the end of the first active material layer and the second active material The layer ends are also spaced apart by the circumferential distance between the second electrode tab and the second active material layer end so that the first active material layer end and the second electrode tab are spaced apart by at least 10 mm. This is because stress concentration on the active material layer occurs not only when the anode active material end and the negative electrode tab overlap, but also when the positive electrode active material end and the negative electrode tab or the positive electrode active material end and the negative electrode active material end overlap one or two layers in the jelly roll. This is because the separator may be damaged or a problem of degrading the charge / discharge efficiency of the active material may occur.

In the cylindrical battery, it is possible to convert the concept of the circumferential distance into the center angle. When the electrode assembly 200 is wound using the first electrode plate 210 and the second electrode plate 220 as described above, the second electrode tab 225 and the second active material layer 222 are jelly. The outer periphery of the roll is spaced apart by a predetermined center angle. At this time, the angle (C) between the second electrode tab 225 and the second active material layer 222 is preferably a central angle of 15 degrees (degree) or more in an electrode assembly having a diameter of 20 to 40 mm. For example, it is desirable to be between 15 and 345 degrees with a range of 360 degrees.

In addition, after winding, the angle D between the second electrode tab 225 and the first active material layer 212 of the first electrode plate 210 may be 15 degrees to 345 degrees. At this time, considering that the second active material layer has already been separated from the second electrode tab by 15 to 345 degrees, the circumferential distance between the second active material layer and the end of the first active material layer should be about 5 mm. The separation angle between the layer end and the second electrode tab may be 30 degrees or more and 330 degrees or less.

As described above, the electrode assembly 200 and the lithium ion secondary battery 100 including the same according to the embodiment of the present invention maintains at least 5 mm or more the distance between the second active material layer 222 and the second electrode tab. It is possible to prevent deformation of the electrode assembly which may occur during charging and discharging of the lithium ion secondary battery 100.

According to the present invention as described above, the present invention is to position the negative electrode tab spaced apart from the active material layer by a predetermined distance, to prevent the deformation of the electrode assembly by preventing stress or excessive heat concentrated on the negative electrode tab. An electrode assembly and a lithium ion secondary battery having the same can be provided.

While the foregoing has been described with reference to preferred embodiments of the present invention, those skilled in the art will be able to variously modify and change the present invention without departing from the spirit and scope of the invention as set forth in the claims below. It will be appreciated.

Claims (8)

A first electrode plate including first uncoated portions at both ends of an electrode current collector for a first electrode plate, and a first active material layer on the electrode current collector for the first electrode plate; A first electrode tab attached to a first uncoated portion of the first electrode plate and protruding a predetermined length; A second electrode plate including a second uncoated portion at both ends of an electrode current collector for a second electrode plate, and a second active material layer on the electrode current collector for the second electrode plate; A second electrode tab attached to a second uncoated portion of the second electrode plate and spaced apart from the second active material layer by a circumferential distance of 5 mm or more; And a separator interposed between the first electrode plate and the second electrode plate to insulate them. The method of claim 1, The first electrode plate is a positive electrode plate, the second electrode plate is a wound electrode assembly, characterized in that the negative electrode plate. The method of claim 1, The distance between the second electrode tab and the first active material layer of the first electrode plate winding end is greater than the distance between the second electrode tab and the second active material layer of the second electrode plate winding end. Electrode assembly. The method of claim 3, wherein The second electrode tab may be spaced apart from the first active material layer of the first electrode plate winding end portion by a circumferential distance of 10 mm or more. A first electrode plate having a first active material layer and a first uncoated portion, a second electrode plate having a second active material layer and a second uncoated portion, a separator interposed between the first electrode plate and a second electrode plate, and And a first electrode tab and a second electrode tab attached to the first and second uncoated parts, wherein the second electrode tab is spaced apart from the second active material layer by 15 degrees or more relative to the second active material layer. An assembly; A case surrounding the electrode assembly; And a cap assembly coupled with the case to seal the cap and having a terminal portion electrically connected to the electrode assembly. The method of claim 5, The first electrode plate is a positive electrode plate, the second electrode plate is a lithium ion secondary battery, characterized in that the negative electrode plate. The method of claim 5, The separation center angle between the second electrode tab and the first active material layer of the first electrode plate winding end part is greater than the separation center angle between the second electrode tab and the second active material layer of the second electrode plate winding end part. Lithium ion secondary battery. The method of claim 5, And the second electrode tab is spaced apart from the first active material layer at a central angle of 30 degrees or more and 330 degrees or less.

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