KR20200134672A - Jelly-roll type electrode assembly and secondary battery including the same - Google Patents

Abstract

The present invention relates to a jelly-roll type electrode assembly and a secondary battery including the same. More particularly, the present invention relates to a jelly-roll type electrode assembly capable of preventing ignition of a battery and securing and increasing thermal safety accordingly by preventing a short caused by contact between a positive electrode and a negative electrode, and a secondary battery including the same. The jelly-roll type electrode assembly according to the present invention includes an electrode stack in which an electrode and a separator are stacked in a winding type, wherein the electrode stack includes a core portion positioned at a winding start portion, and the electrode and the separator are bonded at the core portion. The secondary battery according to the present invention includes: the jelly-roll type electrode assembly; and a can into which the jelly-roll type electrode assembly is inserted, wherein the jelly-roll type electrode assembly includes the electrode stack in which the electrode and the separator are stacked in a winding type, and the electrode stack includes the core portion positioned at the winding start portion. Also, the electrode and the separator are bonded at the core portion.

Description

JELLY-ROLL TYPE ELECTRODE ASSEMBLY AND SECONDARY BATTERY INCLUDING THE SAME}

The present invention relates to a jelly roll type electrode assembly and a secondary battery including the same, and in more detail, by preventing a short circuit caused by contact between a positive electrode and a negative electrode, a jelly that can prevent ignition of a battery and secure and increase thermal safety accordingly It relates to a roll-type electrode assembly and a secondary battery including the same.

Depending on the shape of the battery case, secondary batteries are classified into cylindrical and prismatic batteries in which the electrode assembly is embedded in a cylindrical or rectangular metal can, and pouch-type batteries in which the electrode assembly is embedded in a pouch-shaped case of an aluminum laminate sheet. .

In addition, the electrode assembly built in the battery case is a charge/discharge power plant consisting of a stacked structure of a positive electrode/separator/cathode, and a jelly roll-type structure wound with a separator interposed between a long sheet-shaped positive electrode and negative electrode coated with an active material. And, a stacked structure in which a plurality of positive and negative electrodes of a predetermined size are sequentially stacked with a separator interposed, and a bicell or full cell in which a predetermined unit of positive and negative electrodes is stacked with a separator interposed therebetween. cells) can be classified as a stack/folding electrode assembly of a wound structure.

Among them, jelly roll type electrode assemblies are widely manufactured because they are easy to manufacture and have high energy density per weight. The jelly roll type electrode assembly can be produced by assembling a long sheet-shaped positive electrode and negative electrode, and a laminate with a separator interposed therebetween, and winding the sheet in the longitudinal direction in a state in which the core is in contact with one end of the electrode laminate. have. Further, in order to fix the wound state, the other end of the electrode stack located on the outer surface of the electrode assembly may be attached to the outer surface of the electrode assembly using an insulating tape.

However, when the battery is charged and discharged, the jelly roll type electrode assembly tends to deform while undergoing repeated expansion and contraction. Since the jelly roll type electrode assembly has a dense shape, when such deformation occurs, the internal temperature may increase. In addition, the internal temperature of the jelly roll type electrode assembly may increase due to overcharging of the secondary battery or various other causes. However, when the internal temperature is overheated, shrinkage of the separator inside the electrode assembly may occur. When the separator shrinks, a short occurs between the anode and the cathode, which further increases the temperature inside the electrode assembly, which may cause serious safety problems such as ignition or explosion. Accordingly, many attempts and experiments are being conducted to solve this problem.

Korean Patent Application Publication No. 10-2018-0025542

The present invention was conceived to solve the above problems, and the object of the present invention is to prevent the ignition of the battery by preventing the short circuit caused by the contact between the positive electrode and the negative electrode in a jelly roll type electrode assembly, thereby securing and increasing thermal safety. It is to provide a jelly roll type electrode assembly capable of and a secondary battery including the same.

The jelly roll type electrode assembly according to the present invention includes an electrode stack formed in a winding type by stacking an electrode and a separator, and the electrode stack includes a core portion positioned at the start of winding, and the electrode and the separator are bonded at the core portion. Has been.

Bonding of the electrode and the separator in the core portion may be bonding by lamination.

The electrode includes an anode and a cathode, and the electrode stack is formed in a winding type by stacking an anode, a separator, and a cathode, and a cathode and a separator are bonded to the core portion.

The core portion includes a negative electrode core region located closer to the winding center of the electrode stack than the positive electrode without overlapping the positive electrode, and a separator facing the negative electrode and the negative electrode is bonded in the negative electrode core region.

The negative electrode core region may include a negative electrode uncoated portion to which the negative electrode active material is not coated.

The anode, the separator, and the cathode may not be bonded to each other in portions of the electrode stack except for the core portion.

In the core part, the electrode and the separator may be bonded to each other by double-sided tapes having adhesive strength on both sides.

The electrode includes an anode and a cathode, and the electrode stack is formed in a winding type by stacking an anode, a separator, and a cathode, and in the core portion, the cathode and the separator may be bonded to each other by a double-sided tape.

The core portion includes a negative electrode core region located closer to the winding center of the electrode stack than the positive electrode without overlapping the positive electrode, and the double-sided tape may be located in the negative electrode core region.

The negative electrode core region may include a negative electrode uncoated portion to which the negative electrode active material is not coated.

The electrode stack is formed by sequentially stacking a first separator, a cathode, a second separator, and an anode, and a double-sided tape is positioned between the second separator and the cathode to bond the second separator and the cathode.

The double-sided tape may be positioned only at both ends of the electrode stack in the width direction (W).

The secondary battery according to the present invention includes a jelly roll type electrode assembly; And a can in which the jelly roll type electrode assembly is inserted, wherein the jelly roll type electrode assembly includes an electrode stack formed in a winding type by stacking an electrode and a separator, and the electrode stack is at the start of winding It includes a core portion positioned, and the electrode and the separator are bonded to the core portion.

The jelly roll type electrode assembly and the secondary battery including the same according to the present invention include an electrode stack formed in a winding type by stacking an electrode and a separator, and the electrode stack includes a core portion positioned at a winding start portion, and a core portion As the electrode and the separator are bonded to each other, a short circuit caused by contact between the positive electrode and the negative electrode is prevented, thereby preventing the battery from being ignited, and thus securing and increasing thermal safety.

1 is a front view showing an electrode assembly according to a comparative example of the present invention.
2 is a plan view as viewed from above of the electrode assembly shown in FIG. 1.
3 is a plan view showing a state in which the separator is contracted by heat in the electrode assembly shown in FIG. 2.
4 is a front view showing an electrode assembly according to an embodiment of the present invention.
5 is a front view showing an electrode assembly according to another embodiment of the present invention.

Hereinafter, with reference to the accompanying drawings, preferred embodiments of the present invention will be described in detail so that those of ordinary skill in the art can easily implement the present invention. However, the present invention may be implemented in various different forms and is not limited or limited by the following examples.

In order to clearly describe the present invention, detailed descriptions of parts not related to the description or related known technologies that may unnecessarily obscure the subject matter of the present invention have been omitted, and reference numerals are added to elements of each drawing in the present specification. In this case, the same or similar reference numerals shall be attached to the same or similar elements throughout the specification.

In addition, terms or words used in the present specification and claims should not be construed as being limited to their usual or dictionary meanings, and the inventor appropriately defines the concept of terms in order to describe his own invention in the best way. It should be interpreted as a meaning and concept consistent with the technical idea of the present invention based on the principle that it can be done.

Comparative example

1 is a front view showing an electrode assembly according to a comparative example of the present invention. 2 is a plan view as viewed from above of the electrode assembly shown in FIG. 1. 3 is a plan view showing a state in which the separator is contracted by heat in the electrode assembly shown in FIG. 2.

1 to 2, the jelly roll type electrode assembly 10 according to the comparative example of the present invention includes an electrode stack formed in a wound type by stacking electrodes 11 and 13 and separators 15 and 17 can do. Here, the electrode stack 1 may have a form in which a first separator 15, a cathode 13, a second separator 17, and an anode 11 are sequentially stacked.

The electrode stack 1 may be wound in the R direction shown in FIG. 1 to be manufactured as a jelly roll type electrode assembly. In this case, the jelly roll-type electrode assembly 10 according to the comparative example of the present invention may include a core portion positioned at the winding start portion, which is an area adjacent to the winding center O. An anode uncoated portion 14 that is not coated with an anode active material may be provided at an end of the anode facing the center of the winding.

The jelly roll type electrode assembly 10 according to the comparative example of the present invention is not bonded between the electrode and the separator in the entire electrode stack 1 along the length direction L of the electrode stack. This means that there is no bonded or adhered place between the first separator 15 and the cathode 13, between the cathode 13 and the second separator 17, and between the second separator 17 and the anode 11 do.

In FIG. 3, as the jelly roll type electrode assembly 10 according to the comparative example of the present invention is overheated to a high temperature, the internal separator shrinkage is shown. In particular, it is shown that the second separator 17 is remarkably contracted in the width direction W in the core part. The Z arrow shows the point where the separation membrane shrinkage occurs most in the core part. Here, the state of being overheated to a high temperature may mean a state of being exposed at a temperature of 130 degrees Celsius for about 1 hour.

When the separator shrinks due to high temperature exposure as in the jelly roll electrode assembly 10 according to the comparative example of the present invention, the positive electrode 11 and the negative electrode 13 may be shorted to cause ignition or explosion. I can.

One embodiment

4 is a front view showing an electrode assembly according to an embodiment of the present invention.

Hereinafter, a jelly roll type electrode assembly according to an embodiment of the present invention will be described with reference to FIG. 4.

The jelly roll type electrode assembly 100 according to the exemplary embodiment of the present invention may include an electrode stack 110 formed in a winding type by stacking electrodes and a separator. The electrode stack 110 is

In addition, the electrode stack 110 may include a core portion (C) positioned at the winding start portion, and the electrode and the separator may be bonded or adhered to the core portion (C).

The bonding of the electrode and the separator in the core portion C may be bonding by lamination. Bonding by lamination may mean bonding by applying heat and pressure.

The electrode may include an anode 111 and a cathode 113. Accordingly, the electrode stack 110 may be formed in a winding type by stacking the anode 111, the separator, and the cathode 113. In the jelly roll-type electrode assembly according to an embodiment of the present invention, the electrode stack 110 has a form in which a first separator 115, a cathode 113, a second separator 117, and an anode 111 are sequentially stacked. I can. The electrode stack 110 stacked in this way may be wound based on the winding center O to form a jelly roll type electrode assembly (winding in the R direction as shown in FIG. 1 ).

When the electrode and the separator are bonded to each other in the core part C as in the jelly roll type electrode assembly according to an embodiment of the present invention, shrinkage of the separator may be prevented. In addition, the shrinkage rate of the separator can be significantly reduced.

Therefore, the jelly roll type electrode assembly according to an embodiment of the present invention can prevent the battery from igniting by preventing a short caused by contact between the positive electrode 111 and the negative electrode 113 in the jelly roll type electrode assembly even in a high temperature situation. Accordingly, it is possible to secure and increase thermal safety.

On the other hand, in the jelly roll type electrode assembly 100 according to an embodiment of the present invention, the core portion (C) is, without overlapping with the anode 111, the winding center of the electrode stack 110 than the anode 111 (O A negative electrode core region (B) located closer to) may be included. In addition, the cathode 113 and the separator may be bonded to each other in the anode core region B within the range of the core portion C. In this case, the cathode 113 and the separator facing the cathode 113 may be bonded.

Specifically, in the present invention, as the anode core region is heated and pressed through the lamination roller 130, the cathode 113 and the separator may be bonded to each other in the core region. Bonding may occur between the interface between the cathode 113 and the first separator 115 and between the cathode 113 and the second separator 117. This bonding may be achieved as the coating material coated on the separator is heated and pressurized to have adhesive strength.

In particular, if only the negative electrode core region (B) is heated and pressurized, the negative electrode 113 and the separator may be bonded only to the negative electrode core region (B). In this case, bonding may occur between the cathode 113 and the first separator 115 and between the cathode 113 and the second separator 117 in the cathode core region B. This can be achieved by adjusting the lamination area A shown in FIG. 4.

When the cathode 113 and the separator are bonded in this way, shrinkage of the separator may be prevented in the core portion C, thereby preventing a short circuit between the cathode 113 and the anode 111.

Conventionally, short-circuiting was prevented by relatively increasing the cathode 113 and the separator to secure the anode-cathode gap. On the other hand, the present invention does not have to lengthen the cathode 113 separator, so the effect of increasing battery capacity even with a smaller outer diameter, Energy density and energy efficiency increase effect can be obtained.

In the jelly roll type electrode assembly according to an embodiment of the present invention, the negative electrode core region B may include the negative electrode uncoated portion 114 to which the negative active material is not coated. If the non-coated part is attached (if joined), the adhesive force can be formed in the non-coated part, so that the effect of preventing shrinkage of the separator can be more effectively achieved.

In the jelly roll type electrode assembly according to an embodiment of the present invention, in the portion (E) of the electrode stack 110 excluding the core portion, the anode 111, the separators 115 and 117, and the cathode 113 are bonded to each other. May not be. Of the portions of the electrode stack 110, the portion E excluding the core portion C may be said to be a portion where the anode 111 and the cathode 113 face each other, and this portion is the anode 111 and the cathode ( 113) may not cause a problem of shrinkage of the separator. Since the separator is under pressure between the anode 111 and the cathode 113, shrinkage of the separator may be prevented.

Other examples

5 is a front view showing an electrode assembly according to another embodiment of the present invention.

It has a configuration similar to the jelly roll type electrode assembly according to another embodiment of the present invention. However, the other embodiment is different from the one embodiment in that the double-sided tape 230 is used instead of the core part (C) lamination.

Contents in common with one embodiment will be omitted and described focusing on differences.

Referring to FIG. 5, in the jelly roll type electrode assembly according to another embodiment of the present invention, both sides of the electrode and the separator in the core portion C may be bonded to each other by a double-sided tape 230 having adhesive force. In particular, the cathode 213 and the separator in the core portion C may be bonded to each other by a double-sided tape 230.

The electrode stack 210 is formed by sequentially stacking a first separator 215, a cathode 213, a second separator 217, and an anode 211, and the double-sided tape 230 is a second separator 217 It is positioned between the and the cathode 213 to bond the second separation membrane 217 and the cathode 213. The double-sided tape 230 may be positioned at an interface between the second separator 217 and the cathode 213. Both sides have adhesive strength, and one side may be attached to the second separator 217, and the other side may be attached to the cathode 213. Of course, although not shown in the drawings, the double-sided tape 230 may be positioned at an interface between the first separator 215 and the cathode 213 if necessary.

The core portion C includes a negative electrode core region B located closer to the winding center O of the electrode stack 210 than the positive electrode 211 without overlapping the positive electrode 211, and a double-sided tape ( 230 may be located in the negative electrode core region (B).

The jelly roll-type electrode assembly according to another embodiment of the present invention has the above structure and can prevent shrinkage of the separator by using the double-sided tape 230.

In another embodiment of the present invention, it may have the advantage that it can be easily applied without a large-scale lamination facility or lamination process that applies heat and pressure as a whole to a laminate in which an electrode and a separator are stacked. That is, the tape can be easily applied to only one electrode or only one separator, and the effect of preventing short circuit of the present invention can be obtained.

In the jelly roll-type electrode assembly according to another embodiment of the present invention, similarly to the embodiment, the negative electrode core region B may include the negative electrode 213 and the negative electrode uncoated part 214 to which the active material is not coated. Since the negative electrode uncoated portion is not coated with an active material, tape adhesion may be made stronger, thereby further increasing the effect of preventing shrinkage of the separator.

On the other hand, in the jelly roll type electrode assembly according to another embodiment of the present invention, the double-sided tape 230 may be positioned only at both ends of the electrode stack 210 in the width direction (W) (width direction W is 2). In this case, while effectively preventing shrinkage of the separator, it is possible to reduce the amount of the double-sided tape 230 used, thereby reducing production cost.

Secondary battery

The secondary battery according to another embodiment of the present invention may be a secondary battery including the jelly roll type electrode assembly described in the above or other embodiments.

A secondary battery according to another embodiment of the present invention may include a jelly roll type electrode assembly and a can into which the jelly roll type electrode assembly is inserted. Here, the jelly roll type electrode assembly inserted into the can includes an electrode stack formed in a winding type by stacking electrodes and a separator, and the electrode stack includes a core portion positioned at the start of winding, and an electrode and a separator at the core portion May be bonded.

In the above, although the present invention has been described by limited embodiments and drawings, the present invention is not limited thereto, and the technical idea of the present invention and the following description by those of ordinary skill in the art to which the present invention pertains. Various implementations are possible within the equal range of the claims to be made.

1 110, 210: electrode laminate
10, 100, 200: electrode assembly
11, 111, 211: anode
13, 113, 213: cathode
15, 115, 215: first separator
17, 117, 217: second separator
14, 114, 214: negative electrode uncoated portion
130: lamination roller
230: double-sided tape
O: center of winding
L: longitudinal direction
W: width direction
A: Lamination area
C: core part
B: cathode core region

Claims (13)

In the jelly roll type electrode assembly,
Including an electrode laminate formed in a winding type by stacking the electrode and the separator,
The electrode stack includes a core portion (C) positioned at the start of winding,
In the core part, the electrode and the separator are bonded to each other. The method according to claim 1,
Jelly roll type electrode assembly, characterized in that the bonding between the electrode and the separator in the core portion is by lamination. The method according to claim 1,
The electrode includes an anode and a cathode,
The electrode stack is formed in a winding type by stacking the anode, the separator, and the cathode,
Jelly roll type electrode assembly, characterized in that the cathode and the separator are bonded to the core part. The method of claim 3,
The core portion includes a negative electrode core region (B) located closer to the winding center of the electrode stack than the positive electrode without overlapping the positive electrode,
Jelly roll type electrode assembly, characterized in that the negative electrode and the separator facing the negative electrode are bonded to each other in the negative electrode core region. The method of claim 4,
The negative electrode core region is a jelly roll type electrode assembly, characterized in that the negative electrode uncoated portion is not coated with a negative active material. The method of claim 3,
A jelly roll type electrode assembly, wherein the positive electrode, the separator, and the negative electrode are not bonded to each other in a portion (E) of the electrode stack excluding the core portion. The method according to claim 1,
In the core portion, the electrode and the separator are both sides bonded to each other by a double-sided tape having adhesive force. The method of claim 7,
The electrode includes an anode and a cathode,
The electrode stack is formed in a winding type by stacking the anode, the separator, and the cathode,
In the core part, the cathode and the separator are bonded to each other by the double-sided tape. The method of claim 8,
The core portion includes a negative electrode core region (B) located closer to the winding center of the electrode stack than the positive electrode without overlapping the positive electrode,
The double-sided tape is a jelly roll type electrode assembly, characterized in that located in the negative electrode core region. The method of claim 9,
The negative electrode core region is a jelly roll type electrode assembly, characterized in that the negative electrode uncoated portion is not coated with a negative active material. The method of claim 8,
The electrode stack is formed by sequentially stacking a first separator, a cathode, a second separator, and an anode,
The double-sided tape is positioned between the second separator and the negative electrode to bond the second separator and the negative electrode to each other. The method of claim 7,
The double-sided tape is a jelly roll type electrode assembly, characterized in that located only at both ends of the electrode stack with respect to the width direction (W). Jelly roll type electrode assembly; And
In a secondary battery comprising a can in which the jelly roll type electrode assembly is inserted,
The jelly roll type electrode assembly,
Including an electrode laminate formed in a winding type by stacking the electrode and the separator,
The electrode stack includes a core portion positioned at the start of winding,
In the core portion, the electrode and the separator are bonded to each other.

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