CN117413391A

CN117413391A - Electrode assembly, manufacturing method of electrode assembly and battery cell including the same

Info

Publication number: CN117413391A
Application number: CN202280038955.9A
Authority: CN
Inventors: 郑赫; 张锡勋; 郑守宅; 裵尚镐
Original assignee: LG Energy Solution Ltd
Current assignee: LG Energy Solution Ltd
Priority date: 2021-12-06
Filing date: 2022-12-02
Publication date: 2024-01-16

Abstract

An electrode assembly according to an embodiment of the present invention includes: a cell stack in which electrodes and separators are alternately stacked; an adhesive layer formed on a side surface of the cell stack; and a finished separator surrounding a periphery of the cell stack having the adhesive layer formed thereon, wherein the adhesive layer comprises a laser-absorbing adhesive.

Description

Electrode assembly, manufacturing method of electrode assembly and battery cell including the same

Technical Field

Cross Reference to Related Applications

The present application claims the benefits of korean patent application No.10-2021-0173204, filed on 6 th 12 th year 2021, and korean patent application No.10-2022-0165842, filed on 1 th 12 th year 2022, which are incorporated herein by reference in their entireties.

The present disclosure relates to an electrode assembly, a method of manufacturing the electrode assembly, and a battery cell including the electrode assembly, and more particularly, to an electrode assembly, a method of manufacturing the electrode assembly, and a battery cell including the electrode assembly, the rigidity of which is supplemented.

Background

In modern society, with the daily use of portable devices such as mobile phones, notebook computers, video cameras, and digital cameras, technologies in the fields related to mobile devices as described above have been actively developed. In addition, chargeable/dischargeable secondary batteries are used as power sources for Electric Vehicles (EVs), hybrid Electric Vehicles (HEVs), plug-in hybrid electric vehicles (P-HEVs), etc., in an attempt to solve air pollution, etc., caused by existing gasoline vehicles using fossil fuel. Accordingly, the demand for developing secondary batteries is increasing.

The secondary batteries commercialized at present include nickel-cadmium batteries, nickel-hydrogen batteries, nickel-zinc batteries, and lithium secondary batteries. Among them, lithium secondary batteries are attracting attention because they have advantages such as free charge and discharge, very low self-discharge rate, and high energy density.

Based on the shape of the battery case, the secondary battery may be classified into a cylindrical or prismatic battery in which an electrode assembly is built in a cylindrical or prismatic metal can, and a pouch-shaped battery in which an electrode assembly is built in a pouch-shaped case made of laminated aluminum sheets.

In addition, the secondary batteries may be classified based on a structure of an electrode assembly in which a positive electrode and a negative electrode are stacked with a separator interposed therebetween. Typically, there may be a roll core (wrapping) type structure in which a long sheet type positive electrode and a long sheet type negative electrode are wound with a separator interposed between the positive electrode and the negative electrode, a laminate (lamination) type structure in which a plurality of positive electrodes and negative electrodes cut into a predetermined unit size are sequentially laminated with a separator interposed between the positive electrode and the negative electrode, and the like. In recent years, in order to solve the problems caused by the jellyroll type electrode assembly and the laminate type electrode assembly, a laminate/folding type electrode assembly has been developed as a combination of the jellyroll type electrode assembly and the laminate type electrode assembly.

Fig. 1 is a view showing a state in which an electrode assembly sags due to gravity.

The electrode assembly 10 is a stacked electrode assembly, and is mainly formed by stacking a positive electrode, a separator, a positive electrode, and a separator, or sequentially stacking a positive electrode, a separator, a negative electrode, and a separator. After the above lamination process, the electrode assembly 10 is transferred to perform welding of the electrode tabs and welding of the electrode tab-electrode leads. At this time, a sagging phenomenon, as shown in fig. 1, may occur in the electrode assembly 10 due to the size and weight of the electrode assembly 10.

When a sagging phenomenon occurs in the electrode assembly 10, it may be difficult to transfer the electrode assembly 10 for subsequent processing, and defects may occur in battery cells manufactured through the subsequent processing. Conventionally, a method of supplementing the rigidity of the electrode assembly 10 has been devised by pressing the electrode assembly 10 or by laminating each unit cell forming the electrode assembly. However, the above method has problems in that it cannot be applied to inexpensive separators and cannot be applied to various products.

Disclosure of Invention

Technical problem

It is an object of the present disclosure to provide an electrode assembly having enhanced overall rigidity thereof, a method of manufacturing the same, and a battery cell including the same.

However, the problems to be solved by the embodiments of the present disclosure are not limited to the above-described problems, and various extensions can be made within the scope of the technical ideas included in the present disclosure.

Technical proposal

According to an embodiment of the present disclosure, there is provided an electrode assembly including: a cell stack in which electrodes and separators are alternately laminated; an adhesive layer formed on a side surface of the cell stack; and a finished separator surrounding a periphery of the cell stack on which the adhesive layer is formed, wherein the adhesive layer comprises a laser-absorbing adhesive.

The laser absorbing adhesive may include a laser marking material that is responsive to laser light.

The laser marking material may be capable of absorbing laser energy transmitted through the finished separator.

The laser marking material may include SnO ₂ (tin oxide) based materials.

The laser marking material may also include doping SnO ₂ An Sb (antimony) doped material and/or an In (indium) doped material In the (tin oxide) -based material.

The average particle diameter value of the laser marking material may correspond to the wavelength value of the laser.

The adhesive layer may be formed on a side surface of the cell stack where the long side of the separator is located.

The separator may have a zigzag shape formed by bending a rectangular sheet.

According to another embodiment of the present disclosure, there is provided a method of manufacturing an electrode assembly, the method including the steps of: forming a cell stack in which electrodes and separators are alternately stacked; applying an adhesive to a side surface of the cell stack; wrapping a perimeter of the cell stack coated with the adhesive with a finished separator; irradiating laser to the outside of the finished membrane; and curing the adhesive by laser to form an adhesive layer.

The wavelength value of the laser may be selected according to the characteristics of the finished membrane.

The adhesive may include a laser marking material that is responsive to laser light.

The cell stack may include a zigzag-shaped separator.

According to yet another embodiment of the present disclosure, there is provided a battery cell including the above battery module.

Advantageous effects

According to embodiments, the electrode assembly, the manufacturing method of the electrode assembly, and the battery cell including the electrode assembly of the present disclosure may improve overall rigidity by including adhesive layers on both side surfaces of the electrode assembly.

The effects of the present disclosure are not limited to the above-described effects, and still other effects not mentioned above will be clearly understood by those skilled in the art from the description of the appended claims.

Drawings

Fig. 2 is a diagram illustrating an electrode assembly according to an embodiment of the present disclosure.

Fig. 3 and 4 are diagrams illustrating a manufacturing process of an electrode assembly according to an embodiment of the present disclosure.

Fig. 5 is a flowchart of a method of manufacturing an electrode assembly according to one embodiment of the present disclosure.

Fig. 6 is a graph illustrating optical characteristics of a separator included in an electrode assembly according to an embodiment of the present disclosure.

Detailed Description

Hereinafter, various embodiments of the present disclosure will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily implement them. The present disclosure may be modified in a variety of different ways, and is not limited to the embodiments set forth herein.

For clarity of description of the present disclosure, parts irrelevant to the description will be omitted, and like reference numerals denote like elements throughout the description.

In addition, in the drawings, the size and thickness of each element are arbitrarily exemplified for convenience of description, and the present disclosure is not necessarily limited to the size and thickness exemplified in the drawings. In the drawings, the thickness of layers, regions, etc. are exaggerated for clarity. In the drawings, the thickness of components and regions are exaggerated for convenience of description.

In addition, it will be understood that when an element such as a layer, film, region or sheet is referred to as being "on" or "over" another element, it can be directly on the other element or intervening elements may also be present. In contrast, when an element is referred to as being "directly on" another element, it means that there are no other intervening elements present. In addition, the word "upper" or "above" means disposed above or below the reference portion, and does not necessarily mean disposed on the upper end of the reference portion toward the opposite direction of gravity. Furthermore, similarly to the case where it is described as being located "on" or "above" another portion, it will also be understood with reference to the above that it is described as being located "under" or "below" another portion.

In addition, throughout the description, when a portion is referred to as "comprising" or "including" a certain component, this means that the portion may also include other components without excluding other components, unless otherwise stated.

In addition, throughout the description, when it is referred to as a "plane", this means when the target portion is viewed from the upper side, and when it is referred to as a "cross section", this means when the target portion is viewed from the side of the cross section cut vertically.

Now, an electrode assembly according to an embodiment of the present disclosure will be described.

Referring to fig. 2, the electrode assembly 100 of the present embodiment is a chargeable/dischargeable power generation device, and may include electrodes 110 and 120 and a separator 130. The electrodes 110 and 120 included in the electrode assembly 100 may include a positive electrode 110 and a negative electrode 120 with a separator 130 interposed between the respective electrodes 110 and 120, so that the electrode assembly 100 may have a structure in which the positive electrode 110/the separator 130/the negative electrode 120 are alternately stacked. Here, the positions of the positive electrode 110 and the negative electrode 120 shown in fig. 2 are shown for the sake of convenience, and may be changed from each other.

Here, the diaphragm 130 may have a zigzag shape formed by bending a rectangular diaphragm sheet. In other words, the electrode assembly 100 of the present embodiment may be formed by sequentially stacking the electrodes 110 and 120 cut in a predetermined size and the separator 130, but may be formed by inserting the positive electrode 110 or the negative electrode 120 in the separator 130 bent in a zigzag pattern. More specifically, the separator 130 may be folded in a direction covering the positive electrode 110 in a state where the positive electrode 110 is laminated, and may be folded in a direction covering the negative electrode 120 in a state where the negative electrode 120 is laminated on the separator 130 covering the positive electrode 110. Thereafter, the separator 130 may be folded in a direction to cover the positive electrode 110 in a state where the positive electrode 110 is laminated on the separator 130 covering the negative electrode 120. In this way, the electrode assembly 100 may be formed by repeatedly performing lamination of the electrodes 110 and 120 and folding of the separator 130.

In addition, in order to prevent sagging phenomenon of the electrode assembly 100, conventionally, it has been attempted to supplement the rigidity of the electrode assembly 100 through a pressing process or a lamination process. However, when the separator 130 used in the electrode assembly 100 is an inexpensive separator, the above-described process cannot be applied, and even when the process is applicable, there is a problem in that the electrode assembly 100 is damaged by a pressing process or a lamination process in which pressure or heat is applied.

However, the electrode assembly 100 of the present embodiment includes the adhesive layer 140 formed on the side surface thereof, whereby the rigidity of the electrode assembly 100 can be supplemented. The electrode assembly 100 of the present embodiment may improve rigidity of the electrode assembly 100 while omitting a process of applying pressure or heat to the electrode assembly 100, and may further include an inexpensive separator.

The adhesive layer 140 may be formed on a side surface of the cell stack 101 (see fig. 3) in which the electrodes 110 and 120 and the separator 130 are alternately stacked. Here, the cell stack 101 may mean a stack of the electrodes 110 and 120 and the separator 130 in the electrode assembly 100 of the present embodiment. In addition, the side surface of the cell stack 101 herein may refer to a surface in which the ends of the plurality of electrodes 110 and 120 and/or the separator 130 are exposed in the cell stack 101 in which the electrodes 110 and 120 and the separator 130 are alternately stacked.

The adhesive layer 140 may be in contact with the separator 130. When manufacturing the electrode assembly 100, the separator 130 may be sized larger than the electrodes 110 and 120, and the edges of the separator 130 may protrude beyond the ends of the electrodes 110 and 120. The edge of protruding diaphragm 130 may be referred to herein as an "extension 138 (see fig. 3)".

In addition, even when the electrode assembly 100 is formed by zigzag lamination, the edges of the separator 130 may protrude beyond the ends of the electrodes 110 and 120. In the electrode assembly 100 formed by stacking in a zigzag shape, one end portion of the two end portions of the electrodes 110 and 120 may be covered by the separator 130, and the other end portion may not be covered by the separator 130. At this time, when the sizes of the positive electrode 110 and the negative electrode 120 are different, the extension 138 may be easily formed in the separator 130 on the upper and lower surfaces of the electrodes 110 and 120 having relatively small sizes. Alternatively, a portion of the separator 130 that covers the ends of the electrodes 110 and 120 may be referred to as an extension 138.

When the extension 138 is formed on the separator 130, the adhesive layer 140 may be in contact with the extension 138 of the separator 130 that is not in contact with the electrodes 110 and 120, thereby being able to fix the shape of the separator 130. The separator 130 and another separator 130 adjacent thereto may be fixed to each other by an adhesive layer 140.

Further, the adhesive layer 140 is shown in fig. 2 as being in contact with the positive electrode 110, but the adhesive layer 140 is preferably not in contact with the positive electrode 110. This may be because the binder layer 140 impedes the flow of ions moving from the positive electrode 110 to the negative electrode 120. In addition, it is preferable that the binder layer 140 is not in contact with the negative electrode 120, but the negative electrode 120 is not a direct charging region, and thus, may have less influence than the contact between the positive electrode 110 and the binder layer 140.

The adhesive layer 140 may be formed on all side surfaces of the electrode assembly 100, but preferably may be formed on only some side surfaces. This may be because, if the adhesive layer 140 is formed on all side surfaces of the electrode assembly 100, the adhesive layer 140 blocks gas discharge of the electrode assembly 100 during an electrolyte impregnation or activation process of the electrodes 110 and 120.

The adhesive layer 140 may be formed to entirely cover one side surface of the electrode assembly 100, or may be formed to partially cover one side surface thereof. If the adhesive layer 140 does not entirely cover the side surfaces of the electrode assembly 100, the adhesive layer 140 may be prevented from blocking gas discharge of the electrode assembly 100 during the electrolyte impregnation or activation process of the electrodes 110 and 120.

The adhesive layer 140 may be formed on the surface on which the long sides of the electrodes 110 and 120 or the separator 130 are located among the side surfaces of the electrode assembly 100 or the cell stack 101. The adhesive layer 140 may be formed on the long sides of the electrodes 110 and 120 or the separator 130. This may be because sagging occurs more frequently along a long side relatively longer than the short sides of the electrodes 110 and 120 or the separator 130. However, this description does not completely exclude that the adhesive layer 140 may be formed on the short sides of the electrodes 110 and 120 or the separator 130.

Further, if the adhesive layer 140 is formed on the side surface of the cell stack 101, one surface of the adhesive layer 140 is in contact with the cell stack 101, but the other surface of the adhesive layer 140 is not in contact with the adhesive surface thereof, and has relatively weak rigidity, so that the effect due to the adhesive layer 140 cannot be sufficiently exhibited.

The electrode assembly 100 of the present embodiment may include a finished separator 150 for providing an adhesive surface to the adhesive layer 140 and supplementing the overall rigidity of the electrode assembly 100. The finished separator 150 may wrap around the perimeter of the cell stack 101. The finished separator 150 entirely surrounds the periphery of the cell stack 101 and thus may wrap around the side surfaces of the cell stack 101 once. In addition, the finished separator 150 surrounds the periphery of the cell stack 101 two or more times, and thus may wrap around the side surfaces of the cell stack 101 more than once.

The finished diaphragm 150 may be identical to the diaphragm 130 described above. For example, when the electrode assembly 100 is manufactured using the zigzag lamination method, the separator 130 folded to cover the outermost electrodes 110 and 120 is finally cut in a predetermined size. The membrane 130 may be rotated once and wrapped around the periphery of the cell stack 101 before cutting the membrane 130. At this time, the separator 130 surrounding the periphery of the cell stack 101 may be referred to as a finished separator 150.

The finished membrane 150 may be located outside the adhesive layer 140. The finished separator 150 may be secured to the cell stack 101 by an adhesive layer 140. One surface of the adhesive layer 140 is in contact with the cell stack 101 and the other surface of the adhesive layer 140 may be in contact with the finished separator 150. The adhesive layer 140 is positioned between the cell stack 101 and the finished separator 150 such that one surface of the adhesive layer 140 is supported by the cell stack 101 and the other side may be supported by the finished separator 150. Thereby, the effect of the adhesive layer 140 improving the rigidity and durability of the electrode assembly 100 may be exhibited to a greater extent.

On the other hand, the adhesive layer 140 may be formed by applying an adhesive such as an adhesive resin. However, if the adhesive is a material that cures at room temperature, it may cure immediately after being applied, and thus, there may be a problem in that the adhesive layer 140 does not adhere to the finished separator 150. Thus, the adhesive layer 140 of the present embodiment may be cured after the finished separator 150 is wrapped around the cell stack 101, whereby an adhesive surface may be formed between the cell stack 101 and the adhesive layer 140 or between the adhesive layer 140 and the finished separator 150. However, in the above example, since the adhesive layer 140 is covered by the finished separator 150, there may be a limitation in a method of curing the adhesive layer 140. For example, UV may not be able to penetrate the finished membrane 150, in which case the UV curable adhesive may not be used.

The adhesive layer 140 of the present embodiment may be cured using a laser, and the wavelength of the laser or the like may be selected according to the characteristics of the finished separator 150. The wavelength or output of the laser may be selected within a range that does not damage the finished membrane 150 even while penetrating the finished membrane 150.

The adhesive layer 140 may use a laser absorbing adhesive that absorbs laser light and whose adhesive component is activated or cured by the laser light. The laser absorbing adhesive may include a laser marking material that is responsive to laser light. The laser marking material may be activated by a laser of a specific wavelength. The laser marking material may be activated, thereby generating heat, and such heat may activate the adhesive component of the adhesive or cure the adhesive. The laser marking material may act as an initiator in this way. The adhesive is cured via a laser such that the adhesive layer 140 allows the side surfaces of the cell stack 101 and the finished separator 150 to be secured to each other and bonded to each other.

Further, after the laser absorbing adhesive for the adhesive layer 140 is applied to the side surface of the cell stack 101, there may be a predetermined time interval until the finished separator 150 wraps around the periphery of the cell stack 101 (which causes the adhesive in a pre-cured state to flow in the gravity direction). Thus, the laser absorbing adhesive used in the present embodiment may be provided in a high viscosity state to prevent bleeding after application, for example, it may have a viscosity of 90,000cp to 110,000cp at 25 ℃.

The laser absorbing type adhesive used in the adhesive layer 140 may be prepared using an adhesive polymer, an organic solvent, and a laser marking material as starting materials. The laser-absorbing adhesive may contain 0.1 to 0.5 parts by weight of the laser marking material based on 50 parts by weight of the adhesive polymer. If the laser marking material is contained in an amount less than 0.1 parts by weight, the laser absorption amount of the laser absorbing type adhesive is low, so that it may be difficult to cure the adhesive or activate the adhesive component, and if the laser marking material is contained in an amount more than 0.5 parts by weight, the dispersibility of the laser marking material and the resin may be lowered due to the laser marking material, and the viscosity of the electrolyte may be increased.

In addition, the type of laser marking material included in the adhesive layer 140 may be selected according to a wavelength value of laser used to cure the adhesive layer 140. The laser marking material may be selected to have an average particle size value that is similar to the wavelength value of the laser used. The average particle size value of the laser marking material may correspond to the laser wavelength value. Here, correspondence means that even if the laser wavelength value does not completely match the average particle diameter value, if the error thereof is within a predetermined range (for example, within 100 nm), it can be interpreted as "correspondence". As a specific example, when the wavelength value of the laser light is 900nm to 1200nm, the laser marking material may be selected to have an average particle diameter of 800nm to 1300 nm.

Next, a method of manufacturing an electrode assembly according to one embodiment of the present disclosure will be described.

Fig. 3 and 4 are diagrams illustrating a manufacturing process of an electrode assembly according to an embodiment of the present disclosure. Fig. 5 is a flowchart of a method of manufacturing an electrode assembly according to one embodiment of the present disclosure.

Referring to fig. 3 to 5, the manufacturing method (S1000) of the electrode assembly of the present embodiment may include:

a step (S1100) of forming the cell stack 101 in which the electrodes 110 and 120 and the separator 130 are alternately stacked,

a step of applying the adhesive 142 to the side surfaces of the cell stack 101 (S1200),

a step of wrapping the periphery of the cell stack 101 coated with the adhesive 142 with the finished separator 150 (S1300), irradiating laser light to the outside of the finished separator 150 (S1400), and

the adhesive 142 is cured by laser to form the adhesive layer 140 (S1500).

In the step of forming the cell stack 101 (S1100), any known method may be used as long as the electrode and the separator are laminated in the order of the positive electrode 110, the separator 130, the negative electrode 120, the separator 130, or the negative electrode 120, the separator 130, the positive electrode 110, and the separator 130. For example, the cell stack 101 may be manufactured in a layered shape, or may be manufactured in a zigzag shape. The step (S1100) is described with reference to "step 1" in fig. 3.

In the step of applying the adhesive 142 to the side surfaces of the cell stack 101 (S1200), any known method may be used as a method of applying the adhesive 142. For example, adhesive 142 may be pneumatically or piezoelectrically applied. In addition, the adhesive 142 may be applied in the form of dots by a dot application method or in the form of lines by a line application method. In addition, in order to prevent the applied adhesive 142 from flowing along, the adhesive 142 may be provided in a high viscosity state, for example, it may have a viscosity of 90,000cp to 110,000cp at 25 ℃. The step (S1200) may be described with reference to "step 2" in fig. 3.

In the step of wrapping the periphery of the cell stack 101 coated with the adhesive 142 with the finished separator 150 (S1300), the finished separator 150 may be identical to the separator 130. For example, when the cell stack 101 is formed by the zigzag lamination method, the separator 130 covers one surface of the outermost electrodes 110 and 120 and then may wrap around the periphery of the cell stack 101 before being cut. At this time, the separator 130 surrounding the periphery of the cell stack 101 may be referred to as a finished separator 150. When the finished separator 150 wraps around the periphery of the cell stack 101, a certain or greater force may be applied to the cell stack 101, whereby the adhesive 142 may be stably located between the cell stack 101 and the finished separator 150. Steps (S1300) and (S1400) may be described with reference to "step 3" in fig. 3.

In the step of irradiating the laser light to the outside of the finished diaphragm 150 (S1400), a wavelength value or the like of the laser light may be selected according to the characteristics of the finished diaphragm 150. The wavelength or output of the laser may be selected within a range that does not damage the finished membrane 150, even while penetrating the finished membrane 150.

For example, when the separator is a separator containing alumina (Al ₃ O ₂ ) Aluminum oxide may scatter or reflect light when used as SRS membrane. Therefore, it may be appropriate to use laser light having a wavelength of 900nm or more or laser light having a wavelength of 900nm to 1200 nm. In addition, since the conventional adhesive does not respond to laser light having a wavelength value of 900nm or more or 900nm to 1200nm, the adhesive 142 used in the present embodiment may include a laser marking material that responds to laser light having a wavelength value of 900nm or more or 900nm to 1200 nm. The adhesive according to the present embodiment is required to ensure that the adhesive polymer to be applied to the battery cellA certain level of transparency or higher. In one example, the laser marking material responsive to 900nm to 1200nm laser light may be SnO ₂ (tin oxide) based materials. In this way, snO ₂ A (tin oxide) based material is used as a basic structure, and a small amount of Sb (antimony), in (indium), or the like may be doped to SnO ₂ To improve the laser light absorption efficiency for 900nm to 1200nm light.

The adhesive 142 is cured by laser, whereby in the step of forming the adhesive layer 140 (S1500), the laser marking material included in the adhesive 142 can absorb energy of the irradiated laser. The laser marking material absorbs energy, and thus may exhibit an adhesive component of the adhesive 142, and thus may seal the side surfaces of the cell stack 101. The step (S1500) is described with reference to "step 4" in fig. 3.

Next, experiments for confirming characteristics of laser light that can be used to manufacture the electrode assembly of the present embodiment will be described.

Referring to fig. 6, when the diaphragm 130 of the present embodiment is an SRS diaphragm, the absorbance and the reflectance according to the light source wavelength value can be confirmed. As described above, the SRS membrane includes alumina, and light may be scattered or reflected by the alumina. Therefore, when the SRS separator is used in the present embodiment, a light source having a wavelength of 900nm or more or 900nm to 1200nm can be suitably used.

Referring to the reflectivity chart of fig. 6, when 980nm laser is used, it can be seen that at 100% output, about 40% of the light penetrates the SRS membrane. Based on this, in this experiment, 980nm laser was used as a light source, and whether or not the separator was damaged was confirmed according to the output level and the energy level.

TABLE 1

Line energy (J/mm)	25% output	35% output
			1.25	Bondable	-
1.75	Bondable	-
			1.94	Bondable	-
2.19	Bondable	Diaphragm damage
			2.33	Bondable	Diaphragm damage
2.50	Diaphragm damage	Diaphragm damage
			2.69	Diaphragm damage	-

Referring to the experimental results in table 1, it was confirmed that the separator may be damaged according to the energy level of 980nm laser. The line energy herein may be a value obtained by dividing the laser output (J/s) by the scanning speed (mm/s). In addition, 25% output or 35% output herein means that the scanning speed of the laser is adjusted to set the line energy values shown in table 1, and 35% output uses higher output energy than 25% output.

Specifically, in order to prevent the separator from being damaged when a laser having a wavelength of 980nm is used, the separator may be appropriately irradiated with energy of less than 2.50J/mm. Here, the preferred energy level of the laser having a wavelength of 980nm may be 1.25J/mm or more and less than 2.50J/mm or 1.25J/mm or more and 2.49J/mm or less. Here, the above energy level may be a value based on the case where the laser output is 25%.

Next, experiments of binders that can be used for the binder layer of the electrode assembly of the present embodiment will be described.

Experimental example 1

50 parts by weight of the binder polymer and 0.1 parts by weight of the laser marking additive (laser marking material) were dissolved in 200 parts by weight of an organic solvent to prepare a mixture. The mixture is sufficiently stirred using a mechanical stirrer or the like, and then the solvent is dried using a vacuum oven to prepare a binder resin. Here, a hot melt adhesive may be used as the adhesive polymer, and in particular, 3762 pellets (3762 pellet) from 3M may be used. In addition, iriotec 8850 or Iriotec 8841 from Merck may be used as the laser marking additive, and toluene may be used as the organic solvent.

Experimental example 2

A binder resin was prepared in the same manner as in experimental example 1, except that 0.2 parts by weight of the laser marking additive was used.

Experimental example 3

A binder resin was prepared in the same manner as in experimental example 1, except that 0.3 parts by weight of the laser marking additive was used.

Experimental example 4

A binder resin was prepared in the same manner as in experimental example 1, except that 0.4 parts by weight of the laser marking additive was used.

Experimental example 5

A binder resin was prepared in the same manner as in experimental example 1, except that 0.5 parts by weight of the laser marking additive was used.

Comparative example 1

A binder resin was prepared in the same manner as in experimental example 1, except that 0.6 parts by weight of the laser marking additive was used.

Comparative example 2

A binder resin was prepared in the same manner as in experimental example 1, except that 0.05 parts by weight of the laser marking additive was used.

When the electrode assembly 100 was manufactured using the binder resins prepared in experimental examples 1 to 5 and comparative examples 1 and 2 as a binder, the results shown in table 2 were obtained.

TABLE 2

Category(s)	Laser marking additive (wt.%)	Experimental results
			Experimental example 1	0.1	Can form an adhesive layer
Experimental example 2	0.2	Can form an adhesive layer
			Experimental example 3	0.3	Can form an adhesive layer
Experimental example 4	0.4	Can form an adhesive layer
			Experimental example 5	0.5	Can form an adhesive layer
Comparative example 1	0.6	The dispersibility of the resin decreases and the viscosity of the electrolyte increases due to the laser marking additive.
			Comparative example 2	0.05	Does not ensure sufficient adhesive strength

As shown in table 2, if the laser marking additive is included in an amount of less than 0.1 parts by weight, the laser absorption amount is low, and thus, the adhesive property activity does not show a desired level. In addition, if the laser marking additive is included in an amount of more than 0.5 parts by weight, there is a problem in that dispersibility is deteriorated or viscosity or concentration of the electrolyte contained in the battery cell is increased due to the laser marking additive. Therefore, in the manufacture of the electrode assembly 100 of the present embodiment, in order to form the adhesive layer 140 and exhibit the effect obtained thereby, 0.1 to 0.5 parts by weight of the laser marking additive may be appropriately included based on 50 parts by weight of the adhesive polymer.

Further, the electrode assembly 100 of the present embodiment described above may be stored in a battery cell case together with an electrolyte solution and provided as a battery cell.

A battery cell according to an embodiment of the present invention may include: an electrode assembly 100 in which a plurality of electrodes and a plurality of separators are alternately laminated; an electrode lead connected to an electrode tab extending from the plurality of electrodes; and a battery cell case sealing the electrode assembly in a state in which one end of the electrode lead protrudes.

In addition, the above battery cells may be stacked in one direction to form a battery cell stack, and may be modularized into a battery module together with a Battery Management System (BMS) and/or a cooling device that controls and manages the temperature, voltage, etc. of the battery to form a battery pack. The battery pack may be applied to various devices. For example, the device to which the battery pack is applied may be a vehicle device such as an electric bicycle, an electric vehicle, or a hybrid vehicle, but the present disclosure is not limited thereto, and the battery pack according to the present embodiment may be used for various devices other than the above examples, which also fall within the scope of the present disclosure.

Although the present invention has been described in detail hereinabove with reference to the preferred embodiments thereof, the scope of the present disclosure is not limited thereto, and various modifications and improvements made by those skilled in the art may be made using the basic idea of the present disclosure as defined in the appended claims, which also fall within the scope of the present disclosure.

[ description of reference numerals ]

100: electrode assembly

101: cell stack

110: positive electrode

120: negative electrode

130: diaphragm

140: adhesive layer

150: finished diaphragm

Claims

1. An electrode assembly, the electrode assembly comprising:

a cell stack in which electrodes and separators are alternately stacked,

an adhesive layer formed on a side surface of the cell stack; and

a finished separator surrounding a periphery of the cell stack on which the adhesive layer is formed,

wherein the adhesive layer comprises a laser absorbing adhesive.

2. The electrode assembly of claim 1, wherein:

the laser absorbing adhesive includes a laser marking material that is responsive to laser light.

3. The electrode assembly of claim 2, wherein:

the laser marking material is capable of absorbing laser energy transmitted through the finished diaphragm.

4. The electrode assembly of claim 2, wherein:

the laser marking material comprises SnO ₂ (tin oxide) based materials.

5. The electrode assembly of claim 4, wherein:

the laser marking material also comprises a material doped with SnO ₂ An Sb (antimony) doped material and/or an In (indium) doped material In the (tin oxide) -based material.

6. The electrode assembly of claim 2, wherein:

the average particle diameter value of the laser marking material corresponds to the wavelength value of the laser.

7. The electrode assembly of claim 1, wherein:

the adhesive layer is formed on a side surface of the cell stack where the long side of the separator is located.

8. The electrode assembly of claim 1, wherein:

the diaphragm has a zigzag shape formed by bending a rectangular sheet.

9. A method of manufacturing an electrode assembly, the method comprising the steps of:

forming a cell stack of alternating layers of electrodes and separator;

applying an adhesive to a side surface of the cell stack;

wrapping a perimeter of the cell stack coated with the adhesive with a finished separator;

irradiating laser to the outside of the finished membrane; and

the adhesive is cured by a laser to form an adhesive layer.

10. The manufacturing method according to claim 9, wherein:

the wavelength value of the laser is selected according to the characteristics of the finished diaphragm.

11. The manufacturing method according to claim 9, wherein:

the adhesive includes a laser marking material that is responsive to a laser.

12. The manufacturing method according to claim 9, wherein:

the cell stack includes a zigzag-shaped separator.

13. A battery cell comprising the electrode assembly of claim 1.