CN116848680A - Secondary battery and method for manufacturing secondary battery - Google Patents

Abstract

The secondary battery of the present application includes: an electrode assembly in which a laminate sheet including a positive electrode having a positive electrode tab, a separator, and a negative electrode having a negative electrode tab is wound in a jelly roll configuration, and a core portion is formed at the center of the electrode assembly; a can into which the electrode assembly is inserted and to which the negative electrode tab is connected; a cap assembly coupled to the opening of the can, and a positive tab connected to the cap assembly; and a reinforcing member that is provided at an end portion of the separator exposed to the outside from the positive electrode or the negative electrode, and that prevents heat of the positive electrode tab or the negative electrode tab from being transferred to the separator. Accordingly, the separator can be prevented from shrinking, and thus, a short circuit or fire can be prevented.

Description

Secondary battery and method for manufacturing secondary battery

Technical Field

Cross Reference to Related Applications

The present application claims the benefit of priority from korean patent application No. 10-2021-0055218, filed 28 at 4 at 2021, and korean patent application No. 10-2022-0047202, filed 15 at 4 at 2022, which are incorporated herein by reference in their entirety.

Technical Field

The present application relates to a secondary battery and a method for manufacturing the secondary battery, and more particularly, to a secondary battery capable of preventing heat of a positive electrode tab or a negative electrode tab from being transferred to a separator, and a method for manufacturing the secondary battery.

Background

In general, a secondary battery refers to a chargeable and dischargeable battery, unlike a primary battery that is not chargeable. Such secondary batteries are widely used in high-tech electronic devices such as telephones, notebook computers, and image pickup apparatuses.

Secondary batteries are classified into can-type secondary batteries in which an electrode assembly is inserted into a metal can and pouch-type secondary batteries in which an electrode assembly is inserted into a pouch. The can type secondary battery includes an electrode assembly, an electrolyte, a can accommodating the electrode assembly and the electrolyte, and a cap assembly mounted in an opening of the can. In addition, the pouch-type secondary battery includes an electrode assembly, an electrolyte, and a pouch accommodating the electrode assembly and the electrolyte.

The electrode assembly of the can type secondary battery has a structure in which electrodes and separators are alternately stacked and wound in the form of a jelly roll. In addition, the electrode includes a positive electrode and a negative electrode, and the positive electrode includes a positive electrode tab and the negative electrode includes a negative electrode tab. In addition, a positive tab is connected to the cap assembly, and a negative tab is connected to the can.

However, in the can-type secondary battery having the above-described structure, when an external short circuit occurs, high temperature is generated in the positive electrode tab and the negative electrode tab, and when the high temperature of the positive electrode tab and the negative electrode tab is transferred to the separator, the separator contracts, and thus, the positive electrode and the negative electrode respond to each other to cause a problem of the occurrence of a short circuit or fire.

In particular, since the separator is tightly wound in the core portion of the electrode assembly near the positive electrode tab instead of the peripheral portion, the separator is severely contracted, and thus, there is a problem in that the possibility of short circuit or fire is high.

Disclosure of Invention

Technical problem

An object of the present application is to provide a secondary battery capable of preventing heat of a positive electrode tab or a negative electrode tab from being transferred to a separator even when high temperature is generated in the positive electrode tab and the negative electrode tab to prevent the separator from shrinking, thereby preventing occurrence of a short circuit or fire, and a method for manufacturing the secondary battery.

Technical proposal

The secondary battery of the present application may include: an electrode assembly in which a laminate sheet having a structure in which a positive electrode provided with a positive electrode tab, a separator, and a negative electrode provided with a negative electrode tab are laminated is wound in a jelly roll form, and a core portion is formed at the center of the electrode assembly; a can into which the electrode assembly is inserted, and to which the negative electrode tab is connected; a cap assembly coupled to the opening of the can, and a positive tab connected to the cap assembly; and a reinforcing member provided on an end portion of the separator exposed to the outside from the positive electrode or the negative electrode to prevent heat of the positive electrode tab or the negative electrode tab from being transferred to the separator.

The reinforcing member may include a first reinforcing layer provided only on one surface of the partition arranged in the core portion.

The reinforcing member may further include a second reinforcing layer provided only on an end portion of the separator disposed within a set range with respect to the positive electrode tab or the negative electrode tab.

The reinforcing member may be made of a material having an electrical insulating property and an insulating property.

The second reinforcing layers disposed on the surfaces of the spacers corresponding to each other may be disposed not to contact each other, thereby preventing heat transfer.

The method for manufacturing a secondary battery of the present application may include: a process (a) of manufacturing an electrode assembly in which a laminate sheet having a structure in which a positive electrode provided with a positive electrode tab, a separator, and a negative electrode provided with a negative electrode tab are laminated is wound in the form of a jelly roll, and forming a core portion at the center of the electrode assembly; a process (b) of inserting the electrode assembly into a can, and connecting a negative electrode tab provided in the electrode assembly to the can; a process (c) of applying a reinforcing member on an end portion of the separator exposed to the outside from the positive electrode or the negative electrode to prevent heat of the positive electrode tab or the negative electrode tab from being transferred to the separator; and (d) connecting the positive electrode tab of the electrode assembly to the cap assembly, and coupling the cap assembly to the opening of the can to manufacture the secondary battery.

In process (c), the reinforcing member may include a first reinforcing layer applied only on one surface of the separator disposed in the core portion.

In the process (c), the reinforcing member may further include a second reinforcing layer applied only on an end portion of the separator disposed within a set range with respect to the positive electrode tab or the negative electrode tab.

In process (c), the reinforcing member may be made of a material having an electrical insulation property and a thermal insulation property.

The process (c) may further include a process of applying a protective layer, which is applied to the outside of the reinforcing member to protect the reinforcing member.

The protective layer may be applied in a form surrounding the entire reinforcing member.

In the process (c), the second reinforcing layers applied on the surfaces of the spacers corresponding to each other may be applied not to contact each other, thereby preventing heat transfer.

Process (c) may further comprise the following process performed prior to applying the second enhancement layer: a process of attaching a protective film to the positive electrode tab to prevent the second reinforcing layer from being applied to the positive electrode tab; and a process of removing the protective film attached to the positive electrode tab when the application of the second reinforcing layer is completed.

In the process (c), when the first reinforcing layer is applied, the first reinforcing layer may be applied on one surface of the separator in a state in which the can is vertically erected and the can is rotated in the left-right direction.

The set range may be a radius of rotation of 2mm to 10mm relative to the positive or negative electrode tab.

Advantageous effects

The secondary battery of the present application may include a reinforcing member for preventing heat of the positive electrode tab or the negative electrode tab from being transferred to the separator to prevent the separator disposed in the core portion of the electrode assembly and the separator adjacent to the positive electrode tab or the negative electrode tab from shrinking, thereby improving safety.

Drawings

Fig. 1 is a perspective view of a secondary battery according to a first embodiment of the present application.

Fig. 2 is a sectional view of a secondary battery according to a first embodiment of the present application.

Fig. 3 is an enlarged view of a portion "a" shown in fig. 2.

Fig. 4 is a plan view illustrating a portion of an electrode assembly in which a positive electrode tab of a secondary battery is disposed according to a first embodiment of the present application.

Fig. 5 is an enlarged view of a portion "B" shown in fig. 2.

Fig. 6 is a bottom view illustrating a portion of an electrode assembly in which a negative electrode tab of a secondary battery is disposed according to a first embodiment of the present application.

Fig. 7 is a flowchart illustrating a method for manufacturing a secondary battery according to a first embodiment of the present application.

Fig. 8 is a sectional view of a secondary battery according to a second embodiment of the present application.

Fig. 9 is a perspective view illustrating a protective film of a secondary battery according to a second embodiment of the present application.

Detailed Description

Hereinafter, embodiments of the present application will be described in detail with reference to the accompanying drawings so that those skilled in the art to which the present application pertains can easily implement the technical concept of the present application. This application may, however, be embodied in different forms and should not be construed as limited to the embodiments set forth herein. In the drawings, any content unnecessary for describing the present application will be omitted for clarity, and like reference numerals in the drawings also denote like elements.

[ Secondary Battery according to first embodiment of the application ]

As shown in fig. 1 to 6, the secondary battery 100 according to the first embodiment of the present application includes an electrode assembly 110, a can 120 accommodating the electrode assembly 110, and a cap assembly 130 mounted in an opening of the can 120.

Electrode assembly

The electrode assembly 110 has a structure in which a laminate in which a positive electrode 111, a negative electrode 112, and a separator 113 interposed between the positive electrode 111 and the negative electrode 112 are laminated is wound in the form of a jelly roll. Here, the positive electrode 111 is provided with a positive electrode tab 111a coupled to the cap assembly 130, and the negative electrode 112 is provided with a negative electrode tab 112a coupled to the can 120.

A core portion 110a vertically penetrated when viewed in fig. 1 is formed at the center of the electrode assembly wound in the form of a jelly roll.

Tank

The can 120 has a cylindrical shape and includes a receiving part receiving the electrode assembly 110, a coupling part disposed at an upper side of the receiving part and coupled to the cap assembly, and a beading part disposed between the receiving part and the coupling part to support the cap assembly. Here, the negative electrode tab 112a of the electrode assembly 110 is coupled to the bottom surface of the can.

Cap assembly

The cap assembly 130 is configured to seal the opening of the can, and has a structure in which an exhaust port, a current breaker, a PTC, and a top cap are sequentially disposed from the lower side. Here, the positive electrode tab 111a of the electrode assembly 110 is coupled to the bottom surface of the exhaust port.

In the secondary battery, when an external short circuit occurs, heat is generated from the positive and negative electrode tabs, and when the heat of the positive and negative electrode tabs is transferred to the separator, the separator contracts, and thus, there is a problem in that the short circuit and ignition occur. In particular, since the separator provided in the core of the electrode assembly is tightly wound, there is a problem in that the positive electrode tab and the negative electrode tab are greatly contracted due to the generated heat.

The secondary battery 100 according to the first embodiment of the present application may include a reinforcing member that is provided on an end portion of the separator 113 exposed to the outside from the positive electrode or the negative electrode, and is configured to prevent heat of the positive electrode tab 111a or the negative electrode tab 112a from being transferred to the separator 113. Accordingly, the separator can be prevented from shrinking, thereby preventing a short circuit or fire from occurring.

That is, the reinforcing member may reinforce the strength of the separator 113 adjacent to the positive and negative electrode tabs 111a and 112a and the separator 113 disposed in the core body portion 110a of the electrode assembly 110 and prevent heat transfer, thereby preventing the separator 113 from shrinking and also preventing short circuits and fires from occurring.

For example, as shown in fig. 3 to 6, the reinforcing member includes a first reinforcing layer 140 and a second reinforcing layer 150.

The first reinforcement layer 140 is provided while being applied on the surface of the separator 113 disposed in the core body portion 110a of the electrode assembly 110. That is, the first reinforcement layer 140 reinforces the strength of the separator 113 and prevents heat transfer to prevent the separator from shrinking.

In other words, referring to fig. 3 and 4, the first reinforcement layer 140 may be applied to the ends of the separator 113 exposed from the positive electrode 111 and the negative electrode 112 (the uppermost end and the lowermost end of the separator exposed from the positive electrode and the negative electrode when viewed in fig. 2) with the same thickness, and thus, the strength of the entire separator exposed to the outside of the positive electrode and the negative electrode may be enhanced, and heat transfer of the positive electrode tab and the negative electrode tab to the separator may be prevented to significantly prevent shrinkage of the separator 113, thereby preventing short circuits and fires from occurring.

The first reinforcement layer 140 may be disposed only on an end surface of the separator exposed to the outside of each of the positive and negative electrodes. Accordingly, an increase in weight of the electrode assembly may be minimized, and the use of the first reinforcing layer may be minimized. That is, shrinkage of the separator may occur on the end surface of the separator exposed to the outside of each of the positive and negative electrodes, and thus, the first reinforcing layer may be disposed only on the end surface of the separator exposed to the outside of each of the positive and negative electrodes to prevent the first reinforcing layer from being unnecessarily wasted.

The reinforcing member may include a second reinforcing layer 150 applied on the separator 113 disposed within a set range with respect to the positive and negative electrode tabs 111a and 112a of the electrode assembly 110.

In particular, the second reinforcement layer 150 may be provided only on the end of the separator disposed within a set range with respect to the positive electrode tab or the negative electrode tab.

That is, as shown in fig. 4, the second reinforcement layer 150 may be provided at the end of the separator 113 disposed within the set range α with respect to the positive electrode tab 111a, and thus, heat transfer of the positive electrode tab to the separator may be prevented to prevent shrinkage of the separator 113. In summary, the separator can be prevented from shrinking due to heat generated from the positive electrode tab during external short circuit.

In particular, since the second reinforcing layer 150 is provided only on the end portion of the separator disposed within the set range α with respect to the positive electrode tab, the second reinforcing layer can be prevented from being unnecessarily wasted, and thus, manufacturing costs can be greatly reduced. Since shrinkage occurs at most on the separator arranged within the set range α with respect to the positive electrode tab when heat is generated from the positive electrode tab, it is not necessary to apply the second reinforcing layer to the separator outside the set range.

Here, the set range α may be a rotation radius of 2mm to 10mm with respect to the positive electrode tab. That is, the high temperature of the positive electrode tab can be diffused from the radius of rotation of 2mm to the radius of rotation of 10mm, and therefore, it is necessary to provide the second reinforcing layer on the end portion of the separator arranged with respect to the radius of rotation of 2mm to 10mm of the positive electrode tab. The setting range may be set eccentrically with respect to the positive electrode tab according to a diffusion range of high temperature generated in the positive electrode tab.

In addition, as shown in fig. 5 and 6, the second reinforcing layer 150 may be provided on an end portion of the separator 113 disposed within the set range β with respect to the negative electrode tab 112a. Accordingly, heat transfer of the anode tab to the separator can be prevented, and thus, shrinkage of the separator 113 can be prevented. That is, the separator can be prevented from shrinking due to heat generated by the negative electrode tab during external short circuit.

In particular, since the second reinforcing layer 150 is provided only on the end portion of the separator disposed within the set range β with respect to the negative electrode tab, the second reinforcing layer can be prevented from being unnecessarily wasted, and thus, the manufacturing cost can be greatly reduced.

Here, the set range β may be a radius of rotation of 2mm to 10mm with respect to the negative electrode tab. That is, the high temperature of the anode tab can be diffused from the radius of rotation of 2mm to the radius of rotation of 10mm, and therefore, it is necessary to provide the second reinforcing layer on the end portion of the separator arranged with respect to the radius of rotation of 2mm to 10mm of the anode tab.

The second reinforcing layers 150 respectively applied on the corresponding spacers 113 may be disposed not to contact each other, thereby preventing heat transfer. That is, spaces may be formed between the second reinforcement layers 150 respectively applied on the corresponding spacers 113.

The reinforcing member may be made of a material having heat insulating properties and electrical insulating properties. Therefore, heat transfer of the positive electrode tab and the negative electrode tab to the separator can be prevented. For example, the reinforcing member may be made of ethylene propylene or epoxy.

Accordingly, since the secondary battery 100 according to the first embodiment of the present application may include a reinforcing member to prevent heat of the positive and negative electrode tabs from being transferred to the separator, and thus, the separator is prevented from being contracted due to high temperature of the positive and negative electrode tabs, thereby preventing short circuits and fires from occurring, and improving safety.

Hereinafter, a method for manufacturing a secondary battery according to a first embodiment of the present application will be described.

[ method for manufacturing secondary battery according to first embodiment of the present application ]

As shown in fig. 7, a method for manufacturing a secondary battery according to a first embodiment of the present application includes: a process (a) of manufacturing an electrode assembly; a process (b) of accommodating the electrode assembly in the can; a process (c) of applying a reinforcing member; and (d) a process of manufacturing the secondary battery.

In the process (a), a laminate sheet in which the positive electrode 111 provided with the positive electrode tab 111a, the separator 113, and the negative electrode 112 provided with the negative electrode tab 112a are laminated is wound in the form of a jelly roll to manufacture the electrode assembly 110. Here, referring to fig. 1, since the electrode assembly 110 is wound in the form of a jelly roll, a vertically penetrating core 110a is formed at the center of the electrode assembly.

In the process (b), the electrode assembly 110 is inserted into the can 120, and then the negative electrode tab 112a provided in the electrode assembly 110 is coupled to the bottom surface of the can.

In the process (c), a reinforcing member is applied on the end of the separator 113 exposed to the outside from the positive electrode 111 or the negative electrode 112 to prevent heat transfer of the positive electrode tab 111a or the negative electrode tab 112a to the separator 113.

That is, the process (c) includes a process of applying the first reinforcement layer, and in the process of applying the first reinforcement layer, the first reinforcement layer 140 is applied to only one surface of the separator 113 disposed in the core part 110a of the electrode assembly 110. Accordingly, the heat of the positive electrode tab is blocked by the first reinforcing layer to prevent shrinkage of the separator disposed in the core portion. Here, the first reinforcement layer 140 is formed by applying the first protective liquid to the surface of the separator 113 and then drying the first protective liquid.

Specifically, in the process (c), when the first reinforcement layer 140 is applied, the first reinforcement layer is applied on one surface of the partition arranged in the core portion 110a in a state where the can 120 is erected vertically and then the can 120 is rotated to the left and right. Thus, workability can be improved.

Process (c) further comprises a process of applying a second enhancement layer. In the process of applying the second reinforcing layer, the second reinforcing layer 150 is applied only on the end portion of the separator disposed within a set range with respect to the positive electrode tab 111a or the negative electrode tab 112a.

For example, as shown in fig. 4, the second reinforcement layer 150 may be provided at the end of the separator 113 disposed within the set range α with respect to the positive electrode tab 111a, and thus, heat transfer of the positive electrode tab to the separator may be prevented.

Here, the set range α may be a rotation radius of 2mm to 10mm with respect to the positive electrode tab.

In addition, as shown in fig. 6, the second reinforcing layer 150 may be provided on an end portion of the separator 113 disposed within the set range β with respect to the negative electrode tab 112a. Therefore, heat transfer of the anode tab to the separator can be prevented.

The set range β may be a radius of rotation of 2mm to 10mm relative to the negative electrode tab.

The reinforcing member may be made of a material having heat insulating properties and electrical insulating properties. For example, the first reinforcing layer may be made of ethylene propylene or epoxy.

In the process (c), the second reinforcement layers 150 respectively applied on the spacers 113 corresponding to each other may be provided in a non-contact structure. It is possible to prevent high temperature heat from being transferred to the second reinforcing layers corresponding to each other.

The first reinforcing layer 140 and the second reinforcing layer 150 are made of the same material, and the second reinforcing layer 150 is applied to be thinner than the first reinforcing layer 140. The first reinforcement layer has a thick thickness since the core portion of the electrode assembly has low heat dissipation, and the second reinforcement layer has a thin thickness since the heat dissipation increases toward the outer periphery of the electrode assembly.

In the process (d), the positive electrode tab 111a of the electrode assembly 110 is coupled to the cap assembly 130, and then the cap assembly 130 is coupled to the opening of the can 120.

When the above-described process is completed, the finished secondary battery 100 may be manufactured.

Hereinafter, in the description of another embodiment of the present application, constituent elements having the same configuration and function as those of the above embodiment are given the same reference numerals in the drawings, and thus duplicate descriptions will be omitted.

[ Secondary Battery according to the second embodiment of the application ]

As shown in fig. 8, the secondary battery according to the second embodiment of the present application includes an electrode assembly 110, a can 120 accommodating the electrode assembly 110, and a cap assembly 130 mounted in an opening of the can 120.

In addition, the secondary battery includes a first reinforcing layer 140 applied on the core portion of the electrode assembly 110 and a second reinforcing layer 150 applied on a separator adjacent to the positive and negative electrode tabs 111a and 112a of the electrode assembly 110.

Here, the protective layer 160 for protecting the first and second reinforcement layers 140 and 150 may be applied on the outside of each of the first and second reinforcement layers 140 and 150, and thus, the first and second reinforcement layers 140 and 150 may be prevented from being damaged.

In particular, the protective layer 160 is applied to surround the entire first reinforcing layer 140 and the entire second reinforcing layer 150, and thus, the entire first reinforcing layer 140 and the entire second reinforcing layer 150 can be reliably protected.

The protective layer 160 may be made of an insulating material cheaper than the first and second reinforcing layers 140 and 150 to reduce manufacturing costs.

Hereinafter, a method for manufacturing a secondary battery according to a second embodiment of the present application will be described.

[ method for manufacturing secondary battery according to the second embodiment of the present application ]

As shown in fig. 8 and 9, a method for manufacturing a secondary battery according to a second embodiment of the present application includes: a process (a) of manufacturing an electrode assembly; a process (b) of accommodating the electrode assembly in the can; a process (c) of applying a reinforcing member; and (d) a process of coupling the cap assembly to the can to manufacture the secondary battery.

Here, the processes (a), (b), (c), and (d) have the same manufacturing method as that of the first embodiment described above, and thus duplicate descriptions will be omitted.

However, the secondary battery manufacturing method according to the second embodiment of the present application further includes a process of applying a protective layer.

That is, as shown in fig. 8, in the process of applying the protective layer, the protective layer 160 is applied on the outer portions of the first and second reinforcing layers 140 and 150. In particular, the protective layer 160 is applied to encompass the entire first reinforcing layer 140 and the entire second reinforcing layer 150. Thus, the first enhancement layer and the second enhancement layer can be protected.

Referring to fig. 9, the process (c) may include a process of attaching a protective film before applying the second reinforcement layer 150. In the process of attaching the protective film, the protective film 170 is attached to the positive electrode tab 111a to prevent the second reinforcing layer 150 from being applied on the positive electrode tab.

Process (c) may further include a process of removing the protective film when the application of the second reinforcing layer 150 is completed. In the process of removing the protective film, the protective film 170 attached to the positive electrode tab 111a may be removed to prevent the electrode assembly from being contaminated in advance.

The scope of the application is, therefore, indicated by the appended claims rather than by the foregoing description and exemplary embodiments described therein. Various modifications made within the meaning of the equivalents of the claims of the application and within the claims are considered to be within the scope of the application.

[ description of reference numerals ]

100: secondary battery

110: electrode assembly

110a: core body

111: positive electrode

111a: positive electrode tab

112: negative electrode

112a: negative electrode tab

113: partition piece

120: tank

130: cap assembly

140: first enhancement layer

150: second enhancement layer

160: protective layer

170: protective film

Claims (15)

1. A secondary battery, comprising:

an electrode assembly in which a laminate sheet having a structure in which a positive electrode provided with a positive electrode tab, a separator, and a negative electrode provided with a negative electrode tab are laminated is wound in a jelly roll form, and a core portion is formed at the center of the electrode assembly;

a can into which the electrode assembly is inserted, and to which the negative electrode tab is connected;

a cap assembly coupled to the opening of the can, and the positive tab is connected to the cap assembly; and

and a reinforcing member provided on an end portion of the separator exposed to the outside from the positive electrode or the negative electrode to prevent heat of the positive electrode tab or the negative electrode tab from being transferred to the separator.

2. The secondary battery according to claim 1, wherein the reinforcing member includes a first reinforcing layer provided only on one surface of the separator arranged in the core portion.

3. The secondary battery according to claim 2, wherein the reinforcing member further includes a second reinforcing layer provided only on an end portion of the separator arranged within a set range with respect to the positive electrode tab or the negative electrode tab.

4. The secondary battery according to claim 1, wherein the reinforcing member is made of a material having an electrical insulation property and a heat insulation property.

5. The secondary battery according to claim 3, wherein the second reinforcing layers disposed on the surfaces of the separators that correspond to each other are disposed not to contact each other, thereby preventing heat transfer.

6. A method for manufacturing a secondary battery, the method comprising:

a process (a) of manufacturing an electrode assembly in which a laminate sheet having a structure in which a positive electrode provided with a positive electrode tab, a separator, and a negative electrode provided with a negative electrode tab are laminated is wound in the form of a jelly roll, and forming a core portion at the center of the electrode assembly;

a process (b) of inserting the electrode assembly into the can, and connecting the negative electrode tab provided in the electrode assembly to the can;

a process (c) of applying a reinforcing member on an end portion of the separator exposed to the outside from the positive electrode or the negative electrode to prevent heat of the positive electrode tab or the negative electrode tab from being transferred to the separator; and

and (d) connecting the positive electrode tab of the electrode assembly to a cap assembly, and coupling the cap assembly to an opening of the can to manufacture the secondary battery.

7. The method of claim 6, wherein in the process (c), the reinforcing member comprises a first reinforcing layer applied only on one surface of the separator disposed in the core.

8. The method of claim 7, wherein in the process (c), the reinforcing member further comprises a second reinforcing layer applied only on an end of the separator disposed within a set range with respect to the positive electrode tab or the negative electrode tab.

9. The method of claim 6, wherein in the process (c), the reinforcing member is made of a material having electrical insulation properties and thermal insulation properties.

10. The method of claim 6, wherein the process (c) further comprises a process of applying a protective layer applied to an exterior of the reinforcing member to protect the reinforcing member.

11. The method of claim 10, wherein the protective layer is applied in a form surrounding the entire reinforcing member.

12. The method of claim 10, wherein in the process (c), the second reinforcing layers applied on the surfaces of the spacers corresponding to each other are applied so as not to contact each other, thereby preventing heat transfer.

13. The method of claim 8, wherein the process (c) further comprises the following process performed prior to applying the second enhancement layer:

a process of attaching a protective film to the positive electrode tab to prevent the second reinforcing layer from being applied to the positive electrode tab; and

and a process of removing the protective film attached to the positive electrode tab when the application of the second reinforcing layer is completed.

14. The method according to claim 7, wherein in the process (c), when the first reinforcing layer is applied, the first reinforcing layer is applied on one surface of the separator in a state in which the can stands vertically and the can rotates in a left-right direction.

15. The method of claim 8, wherein the set range is a radius of rotation of 2mm to 10mm relative to the positive tab or the negative tab.