KR20180025542A - Jelly-Roll Type Electrode Having Uncoated Part of Electrode Active Material - Google Patents

Abstract

Provided is an electrode assembly. More specifically, the present invention relates to a jelly roll-type electrode assembly which has a structure obtained via winding after interposing a separator between a negative electrode and a positive electrode which are in a sheet form and to which electrode active materials are applied to one or both sides respectively. At both lateral end portions of a negative electrode sheet, a first negative electrode uncoated part and a second negative electrode uncoated part are formed without negative electrode active materials applied thereon. A negative electrode tab is attached onto the first negative electrode uncoated part, and the second negative electrode uncoated part is positioned on an outermost edge of a jelly roll so as to come into contact with an inner wall of a case where the electrode assembly is accommodated.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a jelly-roll type electrode assembly including an electrode active material uncoated portion,

The present invention relates to a jelly-roll type electrode assembly including an electrode active material uncoated portion.

2. Description of the Related Art [0002] Recently, as technology development and demand for mobile devices have increased, the demand for secondary batteries capable of charging and discharging as energy sources has been rapidly increasing, and a lot of research has been conducted on secondary batteries that can meet various demands. In addition, the secondary battery is an electric vehicle (EV), a hybrid electric vehicle (HEV), a plug-in hybrid electric vehicle (HEV), and the like, which are proposed as solutions for air pollution of existing gasoline vehicles and diesel vehicles using fossil fuels (Plug-in HEV) and the like.

Therefore, an electric vehicle (EV) that can be operated only by a secondary battery, a hybrid electric vehicle (HEV) that uses a secondary battery and an existing engine in combination, and the like have been developed, and some of them have been commercialized. BACKGROUND ART [0002] Nickel metal hydride (Ni-MH) secondary batteries are mainly used as secondary batteries as power sources for EV, HEV, etc. Recently, researches using lithium secondary batteries having high energy density, high discharge voltage and output stability have been actively conducted And some are commercialized.

Such a lithium secondary battery includes a cylindrical battery and a prismatic battery in which an electrode assembly is embedded in a cylindrical or rectangular metal can according to the shape of the battery case, and a pouch type battery in which an electrode assembly is embedded in a pouch-shaped case of an aluminum laminate sheet .

In addition, the electrode assembly incorporated in the battery case is a power generation element which is composed of a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode, and is capable of charging and discharging. The separator is disposed between the positive electrode and the negative electrode, A jelly-roll type interposed between a separator and a stacked type in which a plurality of positive electrodes and negative electrodes of a predetermined size are stacked in a state in which they are interposed in a separator.

Among them, the jelly-roll type electrode assembly (hereinafter, referred to as "jelly-roll") has characteristics of being easy to manufacture and having high energy per weight, and the market for EVs and HEVs using the jelly- Together, there is a growing demand for cylindrical secondary batteries.

1 is a schematic vertical cross-sectional perspective view of a typical cylindrical battery, and FIG. 2 is a schematic diagram showing a plan view of an electrode sheet constituting an electrode assembly housed in the cylindrical secondary battery of FIG. 1 FIG. 3 is a schematic view of a jelly-roll electrode assembly wound around a separator between the anode and the cathode of FIG. 2.

1 to 3, the cylindrical rechargeable battery 10 accommodates the jelly-roll 20 in the battery case 30, and after the electrolyte solution is injected into the battery case 30, And a top cap 40 having an electrode terminal (for example, a positive electrode terminal) formed at the open upper end thereof. The electrode assembly 20 has a structure in which a positive electrode 21 and a negative electrode 22 are sandwiched between a separator 23 and a separator 23 therebetween. The electrode assembly 20 has a cylindrical center pin (50) is inserted.

In the case of such a cylindrical battery 10, it is necessary to design a small internal resistance as small as possible because the smaller the resistance is, the less heat is generated in an actual use environment, and the high rate discharge is advantageous. In order to achieve this, the positive electrode 21 has a positive electrode tab 21d and a non-positive portion 21b of the positive electrode plate 21a to which the active material is not applied so that the positive electrode coating portion 21c coated with the active material is located on both sides thereof And the negative electrode 22 is designed so that the two negative electrode tabs 22c and 22d are located on both sides of the negative electrode plate 22a except for the portion 22b coated with the negative electrode active material Thereby reducing the resistance of the battery.

However, when the jelly-roll 20 including the two negative electrode taps 22c and 22d is accommodated in the case 30, the negative electrode tab 22d positioned at the outermost side of the jelly- It is necessary to weld the cathode tab 22d perfectly to the inner wall of the cathode tab 30 to exhibit proper performance. In this case, a high level of welding technology is required, and spatter occurs in the process of welding the cathode tab 22d, Welding can damage the case and / or the separator. Here, a spatter is a phenomenon in which fine particles of a molten metal protrude to the periphery during melting welding.

Therefore, it is possible to solve the above-mentioned problems occurring in the process of welding the negative electrode tab located at the outermost portion of the jelly-roll, and achieve a resistance reduction effect equivalent to the conventional one with only one negative electrode tab located at the center of the jelly- There is a high need for an electrode assembly having an electrode assembly.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems of the prior art and the technical problems required from the past.

Specifically, it is an object of the present invention to reduce the resistance of the battery by allowing the plain paper to come into direct contact with the inner wall of the case by winding the plain paper formed at one end of the negative electrode sheet to be positioned at the outermost side of the jelly- And an electrode assembly capable of improving the quality of the battery cell including the electrode assembly by omitting the welding process of connecting the negative electrode tab.

According to an aspect of the present invention, there is provided an electrode assembly comprising:

A jelly-roll type electrode assembly having a structure in which a separator is interposed between a sheet-like positive electrode and a negative electrode coated with an electrode active material on one surface or both surfaces,

A first negative electrode uncoated portion and a second negative electrode uncoated portion to which the negative active material is not applied are formed on both side ends of the negative electrode sheet;

The negative electrode tab is attached to the first negative electrode non-coated portion and the second negative electrode non-coated portion is positioned at the outermost portion of the jelly-roll so as to contact the inner wall of the case accommodating the electrode assembly.

Therefore, the electrode assembly according to the present invention is different from the prior art in that instead of attaching a separate negative electrode tab to the second negative electrode non-coated portion, the non-coated portion itself is wound so as to contact the inner wall of the case, It is possible to solve the problems such as the occurrence of spatters, the damage to the casing and / or the separator, which may occur during the process of welding or connecting the negative electrode tab located at the outer periphery to the inner wall of the case, The efficiency of the process can be increased.

Particularly, considering that the second negative electrode non-coated portion is in direct contact with the inner wall of the case and is electrically connected, and the area of contact in this structure is considerable, the resistance of the battery can be reduced, And high-rate characteristics can be improved.

That is, through the electrode assembly according to the present invention, efficiency in the manufacturing process can be ensured and resistance characteristics of the battery can be improved.

The negative electrode sheet may be formed of a conductive metal thin plate such as a copper foil or a nickel foil and the positive electrode sheet may be a thin metal plate having excellent conductivity such as an aluminum foil Lt; / RTI > However, it is needless to say that these materials are not limited to these materials.

The anode tab may be attached by ultrasonic welding on the non-coated portion where the cathode active material is not coated. However, the method of attaching the cathode tab is not limited to the above-described method, and various tapping techniques may be applied.

At this time, the positive electrode sheet may have a structure in which the first positive electrode coating portion and the second positive electrode coating portion are positioned on both sides of the positive electrode uncoated portion.

In one specific example, the length of the negative electrode sheet may be about 105% to 150% of the length of the positive electrode sheet. In order to prevent lithium precipitation in the negative electrode, the amount of the negative electrode active material must be larger than that of the positive electrode active material. The area to which the active material is applied on the sheet may be relatively larger than the area of the active material application area of the positive electrode sheet.

If the length of the negative electrode sheet is less than 105% of the length of the positive electrode sheet, a sufficient amount of the negative active material can not be secured and problems such as lithium precipitation may occur. Conversely, %, The manufacturing cost may increase due to the excess portion of the negative electrode uncoated portion, and the battery is not suitable for miniaturization.

In one specific example, the length of the second negative electrode non-coated portion may be formed to be longer than the length of the first negative electrode non-coated portion with respect to the winding direction.

In addition, the second negative electrode non-coated portion may have a structure wrapping 10% to 100% of the outermost periphery of the jelly-roll.

When the length of the first negative electrode uncoated portion becomes longer, the area of the negative electrode coated portion is reduced, which may affect the capacity and output of the battery, and the second negative electrode uncoated portion is in direct contact with the inner wall of the case, The wider the cross-sectional area is, the smaller the internal resistance of the battery is.

As described above, the second negative electrode non-coated portion has a structure surrounding the outermost periphery of the jelly-roll. When the length of the second negative electrode coated portion is less than 10% of the outermost perimeter, If it is more than 100%, it is not preferable because the ignition part which is not related to the capacity of the battery is included in the case and the specific gravity becomes high.

In some cases, the second negative electrode uncoated portion may be fixed by the insulating tape in a state where the second negative electrode uncoated portion is located at the outermost portion. In this case, the width of the insulating tape may be a length corresponding to the width of the second negative electrode non- And may be formed to have a length of 5% to 30% of the width of the cathode uncoated portion.

If the width of the insulating tape is less than 5% of the width of the second uncoated portion, it may be difficult to prevent the jelly-roll from being loosened in the case. If the width of the insulating tape is more than 30% It is not preferable because the insulating tape does not allow easy penetration into the inside of the roll, and the efficiency of the process is lowered by delaying the time of injecting the electrolyte solution.

Further, the insulating tape may be attached to the center portion or attached to the upper / lower end portions, respectively, with respect to the longitudinal direction of the jelly-roll.

The present invention also relates to

A jelly-roll type electrode assembly having a structure in which a separator is interposed between a positive electrode and a negative electrode sheet in which an electrode active material is coated on one surface or both surfaces thereof, is housed in a cylindrical case in a state impregnated with an electrolyte,

The electrode assembly includes a first negative electrode uncoated portion and a second negative electrode uncoated portion that are not coated with a negative active material at both side ends of the negative electrode sheet;

And a second negative electrode uncoated portion is disposed on an outermost periphery of the jelly-roll so that the second negative electrode uncoated portion can contact the inner wall of the case accommodating the electrode assembly.

Also, the present invention provides a device including the secondary battery, wherein the device may be any one selected from the group consisting of an electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, to be.

The construction of such a device is well known in the art, and a detailed description thereof is omitted here.

As described above, in the electrode assembly according to the present invention, the unoccupied portion without the negative electrode tab is wound to be positioned at the outermost side of the jelly-roll, and the unoccupied portion directly contacts the inner wall of the case and is electrically connected, Reducing the amount of heat generated and reducing the number of processes in which the negative electrode tabs are connected to the inside of the case by welding so that welding problems that may occur during the connection process such as the occurrence of spatter and / Can be solved.

1 is a schematic view showing a vertical cross-sectional perspective view of a conventional cylindrical secondary battery;
FIG. 2 is a schematic view showing a plan view of an electrode sheet constituting an electrode assembly inserted into the cylindrical secondary battery of FIG. 1; FIG.
FIG. 3 is a schematic view of a jelly-roll electrode assembly wound around a separator between the anode and the cathode of FIG. 2; FIG.
4 is a schematic view showing a plan view of an electrode sheet constituting a jelly-roll type electrode assembly according to an embodiment of the present invention;
5 is a schematic view of a jelly-roll type electrode assembly wound around a separator between the positive electrode and the negative electrode of FIG. 4; And
FIG. 6 is a schematic view illustrating a process of inserting the jelly-roll type electrode assembly of FIG. 5 into a cylindrical case having an open upper end.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings, but the present invention is not limited by the scope of the present invention.

4 is a schematic diagram showing a top view of an electrode sheet constituting a jelly-roll type electrode assembly (hereinafter, referred to as "jelly-roll") according to an embodiment of the present invention. FIG. 6 is a schematic view showing a process of inserting the jelly-roll of FIG. 5 into a cylindrical case having an open upper end.

4 to 6, the jelly-roll 100 according to the present invention includes an anode 110 and a cathode 120 having a sheet-like elongated structure and a separation membrane (not shown) Direction (X). That is, the region A where the winding of the positive electrode 110 and the negative electrode 120 starts and the opposing region B of the positive electrode 110 and the negative electrode 120 are respectively wound around the center A and the outermost periphery A of the jelly- (B). The jelly-roll 100 is inserted into a cylindrical case 130 whose upper end is open.

The positive electrode 110 is formed with a non-coated portion 112 where a positive electrode active material is not applied on a portion located between both side ends of the positive electrode sheet 111 and a positive active material is coated on both sides of the non- The first anode coating portion 113 and the second anode coating portion 114 are formed and the cathode tab 115 is attached to the upper center portion of the non-coated portion 112 so as to protrude upward.

The negative electrode 120 is formed with uncoated portions 123 and 124 on both sides of the negative electrode sheet 121, to which a negative electrode active material is not applied by a predetermined length. The uncoated portion formed on the side where the winding is started is referred to as a first negative electrode uncoated portion 123 and the non-coated portion formed on the opposite side of the first negative uncoated portion 123 is referred to as a second negative electrode, And is referred to as an uncoated portion 124. The coating part 122 coated with the negative electrode active material is formed in the other part except for the non-coated parts 123 and 124. [ The negative electrode tab 125 is attached on the first negative electrode non-coated portion 123 so as to protrude downward at the lower middle portion.

The length L2 of the negative electrode sheet 121 is longer than the length L1 of the positive electrode sheet 111 when the positive electrode sheet 111 and the negative electrode sheet 121 are compared. In addition, the amount of the negative electrode active material must be larger than that of the positive electrode active material in order to prevent lithium precipitation in the negative electrode, and the area of the negative electrode coating portion 122 is formed larger than the sum of the areas of the positive electrode coating portions 113 and 114.

The length w2 of the second negative electrode uncoated portion 124 is larger than the length w2 of the second negative electrode uncoated portion 124 when the second negative electrode uncoated portion 124 of the negative electrode 120 is compared with the first negative electrode uncoated portion 123 formed on the opposite side thereof, Is formed to be relatively longer than the length (w1) of the non-coated portion (123).

In this structure, when the length w1 of the first negative electrode uncoated portion 123 located at the center of the innermost angle of the jelly-roll 100 after being wound is long, the area of the negative electrode coating portion 122 The capacity, output, etc. of the battery may be affected.

Since the area in which the second negative electrode uncoated portion 124 contacts the inner wall 131 of the case 130 is proportional to the length w2 of the second negative electrode uncooled portion 124, It is preferable that the length w2 is greater than the length w1 of the first negative electrode uncoated portion 123 while covering within the range of 30% to 100% of the outermost periphery of the jelly-roll 100.

In order to prevent the winding structure of the jelly-roll 100 from being loosened in the case, the insulating tape 140 is wound around or attached to a part C of the second negative electrode non- .

Those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.

Claims (10)

A jelly-roll type electrode assembly having a structure in which a separator is interposed between a sheet-like positive electrode and a negative electrode coated with an electrode active material on one surface or both surfaces,
A first negative electrode uncoated portion and a second negative electrode uncoated portion to which the negative active material is not applied are formed on both side ends of the negative electrode sheet;
Wherein the negative electrode tab is attached to the first negative electrode non-coated portion and the second negative electrode non-coated portion is positioned at the outermost portion of the jelly-roll so as to contact the inner wall of the case accommodating the electrode assembly. The electrode assembly according to claim 1, wherein the cathode sheet is made of an aluminum foil and the cathode sheet is made of a copper foil. The positive electrode sheet according to claim 1, wherein the length of the negative electrode sheet is in a range of 105% to 150% of the length of the positive electrode sheet, and the area of the negative electrode sheet on which the active material is coated is relatively larger than the area of the active material- Wherein the electrode assembly comprises a plurality of electrode assemblies. The electrode assembly according to claim 1, wherein a length of the second negative electrode non-coated portion is formed to be longer than a length of the first negative electrode non-coated portion with respect to a winding direction. The electrode assembly of claim 1, wherein the second cathode non-coated portion surrounds 10% to 100% of the outermost perimeter of the jelly-roll. The electrode assembly according to claim 1, wherein the second cathode uncoated portion is fixed by an insulating tape in a state of being located at an outermost position. The electrode assembly according to claim 6, wherein a width of the insulating tape is set to a length corresponding to a width of the second uncoated region or a length of 5% to 30% of a width of the second uncoated region. The electrode assembly according to claim 1, wherein the positive electrode sheet is formed with a positive electrode uncoated portion to which a positive electrode tab is attached without applying a positive electrode active material. The electrode assembly according to claim 8, wherein the positive electrode sheet has a first positive electrode coating portion and a second positive electrode coating portion on both sides of the positive electrode uncoated portion. A jelly-roll type electrode assembly having a structure in which a separator is interposed between a positive electrode and a negative electrode sheet in which an electrode active material is coated on one surface or both surfaces thereof, is housed in a cylindrical case in a state impregnated with an electrolyte,
The electrode assembly includes a first negative electrode uncoated portion and a second negative electrode uncoated portion that are not coated with a negative active material at both side ends of the negative electrode sheet;
Wherein the negative electrode tab is attached to the first negative electrode non-coated portion, and the second negative electrode non-coated portion is positioned at the outermost portion of the jelly-roll so as to contact the inner wall of the case accommodating the electrode assembly.

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