CN116830345A - Electrode assembly and method of manufacturing the same - Google Patents

Abstract

An electrode assembly according to an embodiment of the present application includes: a negative electrode; a positive electrode; and a separator positioned between the negative electrode and the positive electrode, wherein the negative electrode, the positive electrode, and the separator are wound together to form a wound structure. The anode includes an anode current collector and an anode active material portion formed by coating an anode active material onto the anode current collector. The positive electrode includes a positive electrode current collector and a positive electrode active material portion formed by coating a positive electrode active material onto the positive electrode current collector. The negative electrode uncoated portion of the negative electrode current collector, which is not coated with the negative electrode active material, extends in a first direction, and the positive electrode uncoated portion of the positive electrode current collector, which is not coated with the positive electrode active material, extends in a second direction opposite to the first direction. The positive electrode active material portion includes a load reduction portion in which a load amount of the positive electrode active material is smaller than that of the adjacent region, and the load reduction portion is located at one end of the positive electrode in the first direction.

Description

Electrode assembly and method of manufacturing the same

Technical Field

Cross Reference to Related Applications

The present application claims the benefits of korean patent application No. 10-2021-0012400 filed on 28 th month 2021 and korean patent application No. 10-2022-0012250 filed on 27 th month 2022 to the korean intellectual property office, the contents of which are incorporated herein by reference in their entireties.

The present disclosure relates to an electrode assembly and a method of manufacturing the same, and more particularly, to an electrode assembly having improved energy density and a method of manufacturing the same.

Background

Recently, demand for portable electronic products such as notebook computers, video cameras, cellular phones, etc. is rapidly increasing, and electric vehicles, energy storage batteries, robots, satellites, etc. are actively developing. Accordingly, many studies have been made on a secondary battery used as a driving power source thereof.

The secondary battery includes, for example, a nickel-cadmium battery, a nickel-hydrogen battery, a nickel-zinc battery, a lithium secondary battery, and the like. Among them, lithium secondary batteries are widely used in the field of high-tech electronic devices because they have advantages of exhibiting little memory effect to be freely charged and discharged, for example, compared with nickel-based secondary batteries, and having a very low self-discharge rate, a high operating voltage, and a high energy density per unit weight.

The secondary batteries are classified into cylindrical batteries in which an electrode assembly is mounted in a cylindrical metal can, prismatic batteries in which an electrode assembly is mounted in a prismatic metal can, and pouch-shaped batteries in which an electrode assembly is mounted in a pouch-shaped case formed of an aluminum laminate sheet, according to the shape of a battery case. Among them, the cylindrical battery has advantages in that it has a relatively large capacity and is structurally stable.

The electrode assembly mounted in the battery case is a power generation device capable of charging and discharging, having a cathode/separator/anode laminate structure, and is classified into a winding type, a stacking type, and a stacking/folding type. The winding type is a shape in which a separator sandwiched between a cathode and an anode each made of a long sheet coated with an active material is wound, the stacking type is a shape in which a plurality of cathodes and a plurality of anodes each having a predetermined size are laminated in order of sandwiching the separator therebetween, and the stacking/folding type is a combination of the winding type and the stacking type. Among them, the wound electrode assembly has advantages of easy manufacture and high energy density per unit weight.

Recently, in order to achieve high energy density and reduced cost, development is proceeding toward increasing the size of the battery cell. As the energy increases according to the size of the battery cells, the resistance of each battery cell should decrease. In order to reduce the resistance, a method of using an electrode current collector of an electrode as an electrode tab may be used instead of a method of attaching the electrode tab to the electrode. At this time, due to the characteristics of the electrode manufacturing process in which the electrode slurry is applied to the electrode current collector, a portion in which the load is reduced occurs at the boundary portion between the anode active material portion to which the anode slurry is applied and the anode current collector. In consideration of the N/P ratio, metallic lithium may be precipitated on the cathode active material portion facing the portion where the load is reduced. Here, the N/P ratio is a value obtained by dividing the capacity of the anode calculated in consideration of the area and capacity per mass of the anode by the capacity of the cathode obtained in consideration of the area and capacity per mass of the cathode, and it generally has a value of 1 or more. That is, the anode is manufactured to have a large capacity. For reference, if the N/P ratio is less than 1, metallic lithium is easily precipitated during charge and discharge, which is why the safety of the battery is rapidly deteriorated during high-rate charge and discharge. In other words, the N/P ratio has a significant effect on the safety and capacity of the battery.

Due to the concern of precipitation of metallic lithium as described above, the cathode active material portion cannot be positioned on the cathode portion facing the portion in which the load of the anode is reduced. This is why the energy density of the battery cells cannot be increased.

Disclosure of Invention

Technical problem

It is an object of the present disclosure to provide an electrode assembly having improved energy density by extending a section of a cathode active material portion and a method of manufacturing 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 solution

According to an embodiment of the present disclosure, there is provided an electrode assembly including: an anode; a cathode; and a separator disposed between the anode and the cathode, wherein the anode, the cathode, and the separator are wound together to form a wound structure, wherein the anode includes an anode current collector and an anode active material portion formed by applying an anode active material onto the anode current collector, wherein the cathode includes a cathode current collector and a cathode active material portion formed by applying a cathode active material onto the cathode current collector, wherein an anode uncoated portion in which the anode active material is not applied in the anode current collector extends in a first direction, wherein a cathode uncoated portion in which the cathode active material is not applied in the cathode current collector extends in a second direction opposite to the first direction, wherein the cathode active material portion includes a load reduction portion in which the load of the cathode active material is smaller than that of an adjacent region, and wherein the load reduction portion is disposed at one end of the cathode in the first direction.

The anode active material portion may be disposed at a portion corresponding to the load reducing portion based on a direction perpendicular to the first direction.

The anode active material portion may include an anode boundary portion forming a boundary between the anode active material portion and the anode uncoated portion, and the anode boundary portion may be disposed at a portion corresponding to the load reducing portion based on a direction perpendicular to the first direction.

The loading reduction part may be formed such that the loading amount of the cathode active material gradually decreases as it proceeds in the first direction.

The first direction and the second direction may be directions parallel to the height direction of the winding structure.

The anode uncoated portion may extend beyond the separator in a first direction, and the cathode uncoated portion may extend beyond the separator in a second direction.

The electrode assembly may further include an insulating layer formed on at least one of the anode and the cathode. The insulating layer formed on the anode may cover at least a portion of the anode uncoated portion and the anode active material portion, and the insulating layer formed on the cathode may cover at least a portion of the cathode uncoated portion and the cathode active material portion.

The insulating layer formed on the anode may be formed to cover an end portion of the anode active material portion in the first direction and a portion of the anode uncoated portion adjacent thereto. The insulating layer formed on the cathode may be formed to cover an end portion of the cathode active material portion in the second direction and a portion of the cathode uncoated portion adjacent thereto.

The insulating layer formed on the anode may be disposed at a position not overlapping the load reducing portion based on a direction perpendicular to the first direction.

At least a portion of the sections of the anode uncoated portion and the cathode uncoated portion may be machined in the form of a plurality of segments that are capable of bending independently of each other.

According to another embodiment of the present disclosure, there is provided a method for manufacturing an electrode assembly, the method including the steps of: manufacturing an anode sheet such that anode active material portions to which an anode active material is applied and anode uncoated portions to which no anode active material is applied are alternately disposed on an anode current collector; manufacturing a cathode sheet such that a cathode active material portion to which a cathode active material is applied and a cathode uncoated portion to which no cathode active material is applied are alternately disposed on a cathode current collector; slitting the anode uncoated portion and the anode active material portion to manufacture an anode; slitting the cathode uncoated portion and the cathode active material portion to manufacture a cathode; and winding the anode and the cathode together with the separator to form a winding structure, wherein the cathode sheet includes a load reduction region in which the load of the cathode active material is smaller than that of the adjacent region, wherein in the step of manufacturing the cathode, the load reduction region is slit, and wherein in the winding structure, the slit load reduction region forms a load reduction portion in which the load of the cathode active material is smaller than that of the adjacent region.

In the winding structure, the anode uncoated portion may extend in a first direction, and the cathode uncoated portion may extend in a second direction opposite to the first direction.

The loading reducing portion may be provided at one end of the cathode in the first direction.

The loading reduction part may be formed such that the loading amount of the cathode active material gradually decreases as it proceeds in the first direction.

In the winding structure, the anode active material portion may be positioned at a portion corresponding to the load reducing portion based on a direction perpendicular to the first direction.

The anode active material portion may include an anode boundary portion forming a boundary between the anode active material portion and the anode uncoated portion, and in the wound structure, the anode boundary portion may be positioned at a portion corresponding to the load reducing portion based on a direction perpendicular to the first direction.

The loading amount of the cathode active material may be gradually reduced as it proceeds toward the central portion of the loading reduction region, and in the step of manufacturing the cathode, the loading reduction portion may be provided by slitting the central portion of the loading reduction region.

Advantageous effects

According to the embodiments of the present disclosure, by providing the load reduction portion on the cathode in which the load of the cathode active material is smaller than that of the adjacent region, the section of the cathode active material portion can be increased without fear of deposition of lithium. Thus, the energy density of the electrode assembly can be improved.

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

Drawings

Fig. 1 is a diagram illustrating an electrode assembly according to an embodiment of the present disclosure;

FIG. 2 is a cross-sectional view showing a cross section taken along the cutting line A-A' of FIG. 1;

fig. 3 and 4 are diagrams showing a state of manufacturing an anode according to an embodiment of the present disclosure;

fig. 5 is a perspective view illustrating an anode according to an embodiment of the present disclosure.

Fig. 6 and 7 are diagrams showing a state of manufacturing a cathode according to an embodiment of the present disclosure;

fig. 8 is a perspective view illustrating a cathode according to an embodiment of the present disclosure;

fig. 9 is a diagram showing an electrode assembly according to a comparative example of the present disclosure;

FIG. 10 is a cross-sectional view showing a cross section taken along the cutting line B-B' of FIG. 9;

fig. 11 is a diagram showing a state of manufacturing an anode according to a comparative example of the present disclosure;

fig. 12 is a diagram showing a state of manufacturing a cathode according to a comparative example of the present disclosure;

fig. 13 and 14 are sectional views respectively showing an anode, a cathode, and a separator according to other embodiments of the present disclosure;

fig. 15 is a perspective view illustrating an electrode assembly according to another embodiment of the present disclosure; and

Fig. 16 to 18 are sectional views respectively showing an anode, a cathode, and a separator according to other embodiments 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 the various embodiments. The present disclosure may be modified in various different ways and is not limited to the embodiments set forth herein.

Portions irrelevant to the description will be omitted to clearly describe the present disclosure, and like reference numerals denote like elements throughout the specification.

Further, in the drawings, the size and thickness of each element are arbitrarily shown for convenience of description, and the present disclosure is not necessarily limited to those shown in the drawings. In the drawings, the thickness of layers, regions, etc. are exaggerated for clarity. In the drawings, the thickness of some layers 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 plate 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. Further, the word "upper" or "above" means being arranged on or below the reference portion, and does not necessarily mean being arranged on an upper end portion of the reference portion that is directed to the opposite direction of gravity.

Furthermore, throughout the specification, when a portion is referred to as "comprising" or "including" a certain component, this means that the portion may further include other components without excluding other components, unless otherwise specified.

Further, in the entire specification, when referred to as a "plane", this means that the target portion is viewed from the upper side, and when referred to as a "cross section", this means that the target portion is viewed from the vertically cut cross section side.

Fig. 1 is a view illustrating an electrode assembly according to an embodiment of the present disclosure, and fig. 2 is a sectional view illustrating a section taken along a cutting line A-A' of fig. 1.

Referring to fig. 1 and 2, an electrode assembly 100 according to an embodiment of the present disclosure includes an anode 200, a cathode 300, and a separator 400. The separator 400 is disposed between the anode 200 and the cathode 300. The anode 200, the cathode 300, and the separator 400 are wound together to form the winding structure 100S. Here, the winding structure 100S refers to a structure formed by winding the anode 200, the cathode 300, and the separator 400. Further, when forming the winding structure 100S, it is preferable that the separator 400 is further arranged at the outside so as to prevent the anode 200 and the cathode 300 from contacting each other.

The anode 200 includes an anode current collector 210 and an anode active material portion 220 formed by applying an anode active material to the anode current collector 210. In particular, as shown, an anode active material may be applied to both surfaces of the anode current collector 210 to form the anode active material portion 220. Further, the anode uncoated portion 230, to which the anode active material is not applied, in the anode current collector 210 extends in the first direction d 1. The anode uncoated portion 230 is continuous along one end of the wound anode 200. Further, the anode uncoated portion 230 extends beyond the separator 400 in the first direction d 1. Thereby, the anode uncoated portion 230 may be exposed at one end of the winding structure 100S in the first direction.

The cathode 300 includes a cathode current collector 310 and a cathode active material part 320 formed by applying a cathode active material to the cathode current collector 310. In particular, as shown, a cathode active material may be applied to both surfaces of the cathode current collector 310 to form a cathode active material part 320. Further, the cathode uncoated portion 330 in the cathode current collector 310 to which the cathode active material is not applied extends in the second direction d 2. The cathode uncoated portion 330 is continuous along one end of the wound cathode 300. Further, the cathode uncoated portion 330 extends beyond the separator 400 in the second direction d 2. Thereby, the cathode uncoated portion 330 may be exposed at one end of the winding structure 100S in the second direction.

Here, the first direction d1 and the second direction d2 are directions facing each other. Further, the first direction d1 and the second direction d2 may be directions parallel to the height direction of the winding structure 100S.

The electrode assembly 100 according to the present embodiment is not in the form of attaching a separate electrode tab, but has such a shape: wherein the anode electrode uncoated portion 230 of the anode current collector 210 and the cathode uncoated portion 330 of the cathode current collector 310 themselves serve as electrode tabs to reduce resistance. That is, the electrode assembly 100 according to the present embodiment has a tab-free structure, and the anode uncoated portion 230 and the cathode uncoated portion 330 may themselves be defined as electrode tabs.

At this time, the cathode active material portion 320 according to the present embodiment includes a load reduction portion 300D having a smaller load amount of the cathode active material than in the adjacent region, and the load reduction portion 300D is provided at one end portion of the cathode 300 in the first direction D1. Further, more specifically, the loading reducing part 300D may be formed such that the loading amount of the cathode active material gradually decreases as it proceeds in the first direction D1.

Here, the loading refers to the applied amount of active material per unit area. In the portion having a large load amount, a large amount of the anode active material or the cathode active material is applied to a unit area so that the thickness of the anode active material portion or the cathode active material portion may be relatively thick. In the portion having a small load amount, a small amount of the anode active material or the cathode active material is applied to a unit area so that the thickness of the anode active material portion or the cathode active material portion may be relatively thin.

The active material portion may be formed by applying a slurry containing an active material. In such a process, a boundary portion with a gradually decreasing load amount may be formed between the uncoated portion and the active material portion.

Specifically, the anode active material portion 220 may include an anode boundary portion 220B forming a boundary between the anode active material portion 220 and the anode uncoated portion 230. The anode boundary portion 220B may be formed such that the load amount decreases toward the direction in which the anode uncoated portion 230 is positioned.

Similarly, the cathode active material portion 320 may include a cathode boundary portion 320B forming a boundary between the cathode active material portion 320 and the cathode uncoated portion 330. The cathode boundary portion 320B may be formed such that the load amount decreases as it proceeds toward the direction in which the cathode uncoated portion 330 is positioned.

As described above, the anode boundary portion 220B or the cathode boundary portion 320B, which gradually decreases in load, is naturally generated in the process of applying the slurry containing the active material to the anode current collector 210 or the cathode current collector 310.

Specifically, the anode boundary portion 220B and the cathode boundary portion 320B may be regions where a sliding phenomenon occurs. The slipping phenomenon is the following phenomenon: due to the spreading of the slurry containing the active material, the electrode active material is less applied in the boundary region where the slurry is applied, so that the slurry in the applied boundary region has an approximately oblique shape. Here, when the electrode is completely dried, as the solvent contained in the slurry evaporates and the volume of the slurry is reduced, the slipping phenomenon may further deepen in the vicinity of the boundary between the region to which the active material is applied and the region to which the active material is not applied.

At this time, the amount of the cathode active material may be smaller than the amount of the anode active material in the region corresponding to the cathode boundary portion 320B based on the direction perpendicular to the second direction d 2. Even so, since it has a value of N/P ratio greater than 1, the problem of precipitation of metallic lithium does not occur.

The problem is in the region corresponding to the anode boundary portion 220B. Based on the direction perpendicular to the first direction d1, the amount of the anode active material may be smaller than the amount of the cathode active material in the region corresponding to the anode boundary portion 220B. At this time, since the N/P ratio has a value less than 1, a problem of precipitating metallic lithium may occur.

Therefore, in the present embodiment, the load reducing portion 300D is provided on the cathode 300, and the anode active material portion 220 may be positioned at a portion corresponding to the load reducing portion 300D based on a direction perpendicular to the first direction D1. More specifically, the anode boundary portion 220B may be disposed at a portion corresponding to the load reducing portion 300D based on a direction perpendicular to the first direction D1.

The load reducing portion 300D, in which the load amount of the cathode active material is smaller than that of the adjacent region, is provided at a position corresponding to the anode boundary portion 220B, in which the load amount is gradually reduced, so that the region to which the cathode active material is applied can be increased without having to worry about precipitation of lithium. In particular, in order to correspond to the shape of the anode boundary portion 220B in which the load amount gradually decreases toward the direction in which the anode uncoated portion 230 is positioned, the load reducing portion 300D may have a shape in which the load amount of the cathode active material gradually decreases as it travels in the first direction D1. Accordingly, in the region where the anode boundary portion 220B is formed, the N/P ratio of the anode 200 and the cathode 300 may be maintained high, thereby preventing precipitation of lithium. Further details will be described later by comparison with the comparative examples of fig. 9 to 12.

Next, a method of manufacturing an electrode assembly according to an embodiment of the present disclosure will be described in detail with reference to fig. 3 to 8.

Fig. 3 and 4 are diagrams illustrating a state of manufacturing an anode according to an embodiment of the present disclosure. Specifically, fig. 3 is a plan view of the anode sheet seen from above, and fig. 4 is a front view of the anode sheet of fig. 3 seen from the front.

Referring to fig. 3 and 4, a method of manufacturing an electrode assembly according to an embodiment of the present disclosure includes the steps of: the anode sheet 200S is manufactured such that the anode active material portions 220 to which the anode active material is applied and the anode uncoated portions 230 to which the anode active material is not applied are alternately disposed on the anode current collector 210.

Specifically, the anode active material portion 220 may be formed by applying the anode active material to be continuous along the third direction d3, and the plurality of anode active material portions 220 may be disposed separately from each other in the fourth direction d4 perpendicular to the third direction d 3. That is, the anode uncoated portion 230 may be positioned between the plurality of anode active material portions 220.

Here, the third direction d3 and the fourth direction d4 are directions mainly used to describe the anode sheet 200S, and are directions unrelated to the first direction d1 and the second direction d2 in the above-described winding structure 100S.

Then, the step of slitting the anode uncoated portion 230 and the anode active material portion 220 to manufacture the anode 200 may be followed. Fig. 5 is a perspective view illustrating an anode according to an embodiment of the present disclosure.

Referring to fig. 3 to 5, each of the anode uncoated portion 230 and the anode active material portion 220 may be slit in a direction parallel to the third direction d 3. Thus, a plurality of anodes 200 as shown in fig. 5 can be manufactured from the anode sheet 200S. That is, the anode 200 of fig. 5 corresponds to one of several anodes manufactured by slitting the anode sheet 200S of fig. 3 and 4. By separately slitting the anode uncoated portion 230 and the anode active material portion 220 of the anode sheet 200S, the anode 200 in which the anode uncoated portion 230 extends at one side can be manufactured.

In forming the anode active material portion 220, a slurry containing an anode active material may be applied to the anode current collector 210. In this slurry application process, at the boundary between the anode active material portion 220 and the anode uncoated portion 230, an anode boundary portion 220B in which the load amount decreases as it proceeds toward the direction in which the anode uncoated portion 230 is positioned may be formed.

Fig. 6 and 7 are diagrams illustrating a state in which a cathode is manufactured according to an embodiment of the present disclosure. Specifically, fig. 6 is a plan view of the cathode sheet as viewed from above, and fig. 7 is a front view of the cathode sheet of fig. 6 as viewed from the front.

Referring to fig. 6 and 7, a method of manufacturing an electrode assembly according to an embodiment of the present disclosure includes the steps of: the cathode sheet 300S is manufactured such that the cathode active material portions 320 to which the cathode active material is applied and the cathode uncoated portions 330 to which the cathode active material is not applied are alternately disposed on the cathode current collector 310.

Specifically, the cathode active material part 320 may be formed by applying the cathode active material to be continuous along the third direction d3, and the plurality of cathode active material parts 320 may be disposed separately from each other in the fourth direction d4 perpendicular to the third direction d 3. That is, the cathode uncoated portion 330 may be positioned between the plurality of cathode active material portions 320.

Here, the third direction d3 and the fourth direction d4 are directions mainly used to describe the cathode sheet 300S, and are directions unrelated to the first direction d1 and the second direction d2 in the above-described winding structure 100S.

Then, the step of slitting the cathode uncoated portion 330 and the cathode active material portion 320 to manufacture the cathode electrode 300 may be followed. Fig. 8 is a perspective view illustrating a cathode according to an embodiment of the present disclosure.

Referring to fig. 6 to 8, each of the cathode uncoated portion 330 and the cathode active material portion 320 may be slit in a direction parallel to the third direction d3 as shown by dotted lines in fig. 6 and 7. Accordingly, a plurality of cathodes 300 as shown in fig. 8 can be manufactured from the cathode sheet 300S. That is, the cathode 300 of fig. 8 corresponds to one of several cathodes manufactured by slitting the cathode sheet 300S of fig. 6 and 7. By separately slitting the cathode uncoated portion 330 and the cathode active material portion 320 in the cathode sheet 300S, the cathode 300 in which the cathode uncoated portion 330 extends on one side can be manufactured.

In forming the cathode active material portion 320, a slurry containing a cathode active material may be applied to the cathode current collector 310, and in the slurry application process, a cathode boundary portion 320B, in which the load amount decreases as it goes toward the direction in which the cathode non-coating portion 330 is positioned, may be formed at the boundary between the cathode active material portion 320 and the cathode non-coating portion 330.

Then, referring to fig. 1, 5 and 8 together, the steps of winding the fabricated anode 200 and cathode 300 together with the separator 400 to form the winding structure 100S may be followed. At this time, in the winding structure 100S, the anode uncoated portion 230 may extend beyond the separator 400 in the first direction d1, and the cathode uncoated portion 330 may extend beyond the separator 400 in the second direction d2 opposite to the first direction d 1.

Meanwhile, referring again to fig. 6 to 8, in the method of manufacturing an electrode assembly according to the embodiment of the present disclosure, the cathode sheet 300S includes a load reduction region 300DA in which the load amount of the cathode active material is smaller than that of the adjacent region. The method of forming the loading reduction region 300DA is not particularly limited, and as an example, it may be formed by adjusting the application degree of the slurry.

In the step of manufacturing the cathode 300, the load reduction regions 300DA of the cathode active material portion 320 are slit. The split load reduction region 300DA corresponds to the load reduction portion 300D in which the load of the cathode active material is smaller than that of the adjacent region in the winding structure 100S shown in fig. 1 and 2.

Specifically, a load reduction region 300DA in which the load of the cathode active material is smaller than that of the adjacent region is formed in the cathode active material portion 320 formed on the cathode sheet 300S. As shown in fig. 7, the load reduction region 300DA may be formed at the center of the cathode active material portion 320. Meanwhile, the load reduction region 300DA may be configured such that the load amount of the cathode active material gradually decreases as it proceeds toward the central portion 300C of the load reduction region 300DA, and in the step of manufacturing the cathode 300, the load reduction portion 300D according to the present embodiment may be provided by slitting the central portion 300C of the load reduction region 300DA.

That is, when the slurry containing the cathode active material is applied, a plurality of cathodes 300 in which the load reducing portions 300D are formed can be manufactured by forming the load reducing regions 300DA and slitting the central portions 300C of the load reducing regions 300DA.

Referring to fig. 8, a load reducing portion 300D may be provided at one end of the manufactured cathode 300, and a cathode uncoated portion 330 may be provided at the other end of the cathode 300 facing the one end.

Referring to fig. 1 and 2, when the cathode 300 is wound to form the winding structure 100S, the loading reducing part 300D is disposed at one end of the cathode 300 in the first direction D1, and the cathode uncoated part 330 may be disposed at one end of the cathode 300 in the second direction D2.

Further, as the central portion 300C of the load reducing region 300DA is slit, the load reducing portion 300D may be formed such that the load amount of the cathode active material gradually decreases as it proceeds toward the first direction D1.

Further, in the winding structure 100S, the anode active material portion 220 may be positioned at a portion corresponding to the load reducing portion 300D based on a direction perpendicular to the first direction D1. More specifically, in the winding structure 100S, the anode boundary portion 220B may be positioned at a portion corresponding to the load reducing portion 300D based on a direction perpendicular to the first direction D1.

The correspondence positional relationship between the loading reducing portion 300D and the anode boundary portion 220B is omitted because it overlaps with the above.

Next, referring to fig. 9 to 12, an electrode assembly according to a comparative example of the present disclosure will be described, and advantages of the electrode assembly according to the present embodiment compared to the electrode assembly according to the comparative example will be described.

Fig. 9 is a view showing an electrode assembly according to a comparative example of the present disclosure. Fig. 10 is a sectional view showing a section taken along a cutting line B-B' of fig. 9.

Referring to fig. 9 and 10, the electrode assembly 10 according to the comparative example of the present disclosure includes an anode 20, a cathode 30, and a separator 40, wherein the anode 20, the cathode 30, and the separator 40 are wound to form a winding structure 10S.

The anode 20 may include an anode current collector 21, an anode active material portion 22, and an anode uncoated portion 23. Further, the anode uncoated portion 23 may extend in the first direction d1, and the anode active material portion 22 may include an anode boundary portion 22B that forms a boundary between the anode active material portion 22 and the anode uncoated portion 23 and gradually reduces the load amount.

Fig. 11 is a diagram showing a state of manufacturing an anode according to a comparative example of the present disclosure. Specifically, it is a diagram for explaining a process of manufacturing the anode 20 included in the electrode assembly 10 of fig. 9 and 10.

Referring to fig. 11, the anode sheet 20S is manufactured such that the anode active material portions 22 and the anode uncoated portions 23 are alternately arranged along the fourth direction d4, and then the anode uncoated portions 23 and the anode active material portions 22 may be slit to manufacture a plurality of anodes 20.

Meanwhile, referring again to fig. 9 and 10, the cathode 30 may include a cathode current collector 31, a cathode active material portion 32, and a cathode uncoated portion 33. Further, the cathode uncoated portion 33 may extend in a second direction d2 opposite to the first direction d1, and the cathode active material portion 32 may include a cathode boundary portion 32B that forms a boundary between the cathode active material portion 32 and the cathode uncoated portion 33 and gradually reduces the load amount.

Fig. 12 is a diagram showing a state of manufacturing a cathode according to a comparative example of the present disclosure. Specifically, fig. 12 is a diagram for explaining a process of manufacturing the cathode 30 included in the electrode assembly 10 of fig. 9 and 10.

Referring to fig. 12, the cathode sheet 30S is manufactured such that the cathode active material portions 32 and the cathode uncoated portions 33 are alternately arranged along the fourth direction d4, and then the cathode uncoated portions 33 and the cathode active material portions 32 may be slit to manufacture a plurality of cathodes 30.

Then, the manufactured anode 20 and cathode 30 may be wound together with the separator 40 to manufacture the electrode assembly 10 according to the comparative example of the present disclosure.

That is, the electrode assembly 10 according to the comparative example of the present disclosure may have a structure similar to that of the electrode assembly 100 according to the present embodiment, except that the loading reducing part 300D (see fig. 2) is formed.

Referring to fig. 9 and 10, in the case of the electrode assembly 10 according to the present comparative example, the cathode active material portion 32 cannot be positioned at a portion corresponding to the anode boundary portion 22B based on the direction perpendicular to the first direction d 1. If the cathode material portion 32 extends up to the portion corresponding to the anode boundary portion 22B, the corresponding portion is a portion exhibiting a low N/P ratio, and metallic lithium is highly likely to precipitate. Therefore, in order to prevent precipitation of lithium, it is necessary to limit the length of the cathode active material portion 32. That is, the cathode active material portion 32 can be formed only in the illustrated region B1, and the cathode active material portion 32 cannot be formed in the region B2. This results in the length of the cathode active material portion 32 being reduced due to the anode boundary portion 22B.

On the other hand, referring to fig. 1 and 2, in the case of the electrode assembly 100 according to the present embodiment, the cathode active material portion 320, particularly the load reducing portion 300D, may be disposed at a position corresponding to the anode boundary portion 220B based on a direction perpendicular to the first direction D1. Since the load reduction portion 300D in which the load amount of the cathode material is smaller than that of the adjacent region is provided at a position corresponding to the anode boundary portion 220B, the N/P ratio can be kept high in the corresponding portion, and precipitation of lithium can be prevented. Thereby, the cathode active material portion 320 may be formed as much as the region A1, and the region A2 in which the cathode active material portion 320 cannot be formed may be reduced. In one example, the height-direction width of the cathode 300 relative to the height-direction width of the anode 200 may be increased to 98% or more.

Comparing the region A1 in fig. 1 and 2 with the region B1 in fig. 9 and 10, since the electrode assembly 100 according to the present embodiment can increase the length of the cathode material portion by the loading reducing part 300D, the electrode assembly 100 according to the present embodiment can have a higher energy density in a limited space as compared to the electrode assembly 10 according to the comparative example.

Next, an electrode assembly according to other embodiments of the present disclosure will be described in detail with reference to fig. 13 and 14. Since the embodiment of fig. 13 or 14 is similar to the previous embodiment of fig. 2, repeated description of the configuration substantially the same as or similar to that of the previous embodiment is omitted, and differences from the previous embodiment are mainly described.

Fig. 13 and 14 are sectional views respectively showing an anode, a cathode, and a separator according to other embodiments of the present disclosure.

Referring to fig. 13 and 14, the electrode assembly according to the present embodiment includes an anode 200, a cathode 300, and a separator 400, wherein the anode 200, the cathode 300, and the separator 400 are wound together to form a wound structure.

The anode 200 includes an anode current collector 210 and an anode active material portion 220, and an anode uncoated portion 230 extends beyond the separator 400 in the first direction d 1. The cathode 300 includes a cathode current collector 310 and a cathode active material portion 320, and a cathode uncoated portion 330 extends beyond the separator 400 in the second direction d 2.

Meanwhile, regarding the height direction of the above-described winding structure, the length Lp of the cathode active material portion 320 may be shorter than the length Ln of the anode active material portion 220. Further, the cathode active material portion 320 may be positioned inside the anode active material portion 220 in the height direction. For example, the length Ln in the height direction of the anode active material portion 220 may be greater than the length Lp in the height direction of the cathode active material portion 320.

Further, the length Lp in the height direction of the cathode active material portion 320 may be formed to be shorter than the length in the height direction of the region of the anode active material portion 220 other than the anode boundary portion 220B. This structure is intended to prevent the above-mentioned N/P ratio from decreasing to 1 or less and lithium metal from precipitating.

Meanwhile, the anode active material portion 220 and the cathode active material portion 320 may not protrude beyond the separator 400 in the height direction. If the anode active material portion 220 and the cathode active material portion 320 protrude beyond the separator 400 in the height direction, the possibility of contact between the anode 200 and the cathode 300 may be increased. If this is the case, internal shorts can occur in the contact area, increasing the risk of ignition. Therefore, it is important that the anode active material portion 220 and the cathode active material portion 320 do not protrude beyond the separator 400 in the height direction. That is, the anode active material portion 220 and the cathode active material portion 320 are preferably positioned inside the separator 400.

Meanwhile, the electrode assembly according to the present embodiment may further include insulating layers 500n and 500p formed on at least one of the anode 200 and the cathode 300. In order to minimize the possibility of contact between the anode 200 or the cathode 300, the electrode assembly of the present disclosure may further include insulating layers 500n and 500p formed on at least one of the anode 200 and the cathode 300.

Fig. 13 shows an insulating layer 500p formed on the cathode 300. The insulating layer 500p formed on the cathode 300 may cover at least a portion of the cathode non-coating portion 330 and the cathode active material portion 320.

The electrical contact between the anode 200 and the cathode 300 can be effectively prevented by the insulating layer 500p. More specifically, electrical contact between the cathode uncoated portion 330 and the anode active material portion 220 can be effectively prevented.

An insulating layer 500p may be disposed on at least one surface of the cathode 300. For example, the insulating layers 500p may be disposed on both surfaces of the cathode 300. Although not shown in fig. 13, in the wound structure, another portion of the wound anode 200 is positioned at the left side of the separator 400 positioned at the left side. Accordingly, in order to prevent electrical contact with the anode 200 positioned at the left and right sides, insulating layers 500p are preferably disposed on both surfaces of the cathode 300.

The insulating layer 500p may be disposed in a region of the cathode 300 that may face the anode active material portion 220. For example, the end of the insulating layer 500p in the second direction d2 may be positioned at the same height as the end of the separator 400 in the second direction d2, or positioned outside the end of the separator 400 in the second direction d 2. More specifically, referring to fig. 13 as an example, an end portion of the insulating layer 500p in the second direction d2 may be positioned at the same height as an end portion of the separator 400 in the second direction d 2. Since the separator 400 is wound between the cathode 300 and the anode 200 and protrudes in the height direction, electrical contact between the cathode 300 and the anode 200 can be prevented to some extent. However, since a flow such as bending of the cathode 300 or the anode 200 may occur inside the secondary battery including the electrode assembly, the possibility that the anode 200 is positioned near the end of the separator 400 cannot be excluded. Therefore, when the anode 200 is positioned to the end of the separator 400 or the anode 200 is projected outward beyond the end of the separator 400 due to occurrence of flow such as bending, electrical contact between the cathode 300 and the anode 200 becomes unavoidable. Alternatively, if the separator 400 is damaged for some reason, electrical contact between the cathode 300 and the anode 200 becomes unavoidable.

Therefore, in order to prevent electrical contact between the cathode 300 and the anode 200 even if this occurs, it is preferable that the insulating layer 500p provided in the cathode 300 extends up to at least the same height as the end of the separator 400 in the second direction d2 or extends out of the end of the separator 400 in the second direction d 2.

However, when the insulating layer 500p covers the entire cathode uncoated portion 330, since the cathode uncoated portion 330 cannot function as an electrode tab, the insulating layer 500p preferably covers a portion of the cathode uncoated portion 330. That is, the cathode uncoated portion 330 may have a shape protruding further to the outside of the insulating layer 500 p.

The insulating layer 500p may be an insulating coating or an insulating tape provided on a boundary region between the cathode non-coating portion 330 and the cathode active material portion 320. However, the shape of the insulating layer 500p is not limited thereto, and may be used in the present disclosure as long as the insulating layer 500p has a shape that can be attached to the cathode 300 while securing insulating properties. Meanwhile, the insulating layer 500p may include, for example, an oil-based SBR binder and alumina to ensure insulating properties.

The insulating layer 500p may cover at least a portion of the cathode uncoated portion 330 and at least a portion of the cathode active material portion 320 at the same time. For example, the insulating layer 500p may be disposed on a boundary region between the cathode active material portion 320 and the cathode uncoated portion 330. For example, the insulating layer 500p may cover at least a portion of the cathode boundary portion 320B. For example, the insulating layer 500p may extend from a boundary point between the cathode uncoated portion 330 and the cathode active material portion 320 to a point of about 0.3mm to 5mm, more preferably about 1.5mm to 3mm, in the entire region of the cathode uncoated portion 330.

If the insulating layer 500p is not present, it is preferable that the insulating layer 500p extends to a position where electrical contact between the cathode 300 and the anode 200 does not occur, because internal short circuits may occur due to contact between the cathode 300 and the anode 200.

Meanwhile, the insulating layer 500p may extend from the boundary point between the cathode non-coating portion 330 and the cathode active material portion 320 to a point of about 0.1mm to 3mm, more preferably about 0.2mm to 0.5mm, in the entire region of the cathode active material portion 320.

When the insulating layer 500p covers a portion of the cathode active material portion 320, a capacity loss of the battery occurs, and thus, it is necessary to minimize the covered length of the holding portion of the insulating layer 500 p. However, since the cathode active material portion 320 may be in contact with the anode 200, in order to prevent this, the insulating layer 500p preferably covers at least a portion of the cathode active material portion 320.

Meanwhile, if described with reference to fig. 13, the separator 400 may protrude outward from an end of the cathode 300 in the first direction d1, and may protrude outward from an end of the anode 200 in the second direction d 2.

Meanwhile, the separator 400 does not protrude beyond the end of the anode 200 in the first direction d 1. This is to allow the anode uncoated portion 230 to function as an electrode tab. Similarly, the separator 400 does not protrude beyond the end of the cathode 300 in the second direction d 2. This is to allow the cathode uncoated portion 330 to function as an electrode tab.

Meanwhile, one end of the anode 200 facing the insulating layer 500p with the separator 400 interposed therebetween may have a shape not to protrude outward from one end of the separator 400. For example, referring to fig. 13, the cathode 300 is provided with an insulating layer 500p, and one end of the anode 200 facing the insulating layer 500p may be positioned inside the separator 400. Therefore, even if the cathode uncoated portion 330 protrudes out of the separator 400, since one end portion of the anode 200 is positioned inside the separator 400, the possibility of contact between the cathode 300 and the anode 200 is greatly reduced.

In fig. 14, not only the insulating layer 500p formed on the cathode 300 but also the insulating layer 500n formed on the anode 200 are shown. Of course, although not shown, as another embodiment, an insulating layer formed only on the anode 200 is also included in the present disclosure. The insulating layer 500n formed on the anode 200 may cover at least a portion of the anode uncoated portion 230 and the anode active material portion 220. The insulating layer 500n may cover at least a portion of the anode uncoated portion 230 and at least a portion of the anode active material portion 220 at the same time. For example, the insulating layer 500n may be disposed on a boundary region between the anode active material portion 220 and the anode uncoated portion 230. For example, the insulating layer 500n may cover at least a portion of the anode boundary portion 220B.

A configuration similar to the configuration of the insulating layer 500p formed on the cathode 300 described above may be applied to the insulating layer 500n formed on the anode. Hereinafter, duplicate descriptions will be omitted, and differences from the previous embodiments will be mainly described.

The insulating layer 500n formed on the anode 200 may be positioned at a position not overlapping the load reducing portion 300D of the cathode 300 based on a direction perpendicular to the first direction D1. The portion where the insulating layer 500n is formed based on the direction perpendicular to the first direction d1 is an unreacted region. Therefore, if the insulating layer 500n is positioned at a position overlapping the loading reduction part 300D based on the direction perpendicular to the first direction D1, the capacity loss of the battery occurs as much as the amount, and the reason for providing the loading reduction part 300D disappears. Accordingly, as shown in fig. 14, based on the direction perpendicular to the first direction D1, the insulating layer 500n covering at least a portion of the anode boundary portion 220B may be positioned so as not to overlap the loading reducing portion 300D, thereby aiming at preventing capacity loss of the battery.

Next, an electrode assembly according to other embodiments of the present disclosure will be described in detail with reference to fig. 15 to 18, etc.

Fig. 15 is a perspective view illustrating an electrode assembly according to another embodiment of the present disclosure. Fig. 16 to 18 are sectional views respectively showing an anode, a cathode, and a separator according to other embodiments of the present disclosure.

First, referring to fig. 15 and 16, the electrode assembly 100 according to another embodiment of the present disclosure may have a structure in which at least a portion of the cathode uncoated portion 330 or the anode uncoated portion 230 is bent toward a winding center of the winding structure.

At least a portion of the sections of the anode uncoated portion 230 and the cathode uncoated portion 330 may be processed in the form of a plurality of segments that may be bent independently of each other. Fig. 15 and 16 show that at least a portion of the sections of the cathode uncoated portion 330 are processed in the form of a plurality of segments 330F that can be bent independently of each other. Here, the plurality of segments 330F may have a structure overlapping the plurality of layers while being bent toward the winding center side. For example, the plurality of segments 330F may be notched with a laser. The segment 330F may be formed by a known metal foil cutting process such as ultrasonic cutting or stamping.

Hereinafter, the segment 330F of the cathode uncoated portion 330 is mainly described, but the same or similar structure may be applied to the anode uncoated portion 230.

In order to prevent the active material layer and/or the insulating layer 500a from being damaged during bending of the cathode uncoated portion 330, it is preferable to provide a predetermined gap between the lower end of the cutting line in the segment 330F and the active material layer. This is because when the cathode uncoated portion 330 is bent, stress is concentrated near the lower end of the cutting line. The gap is preferably 0.2mm to 4mm. When the gaps are adjusted to the corresponding numerical ranges, the active material layer and/or the insulating layer 500a near the lower end of the cutting line may be prevented from being damaged by stress generated during bending of the cathode uncoated portion 330. In addition, the gap may prevent damage to the active material layer and/or the insulating layer 500a due to tolerances during grooving or cutting of the segment.

The bending direction of the cathode uncoated portion 330 may be a direction toward the winding center of the winding structure. When the cathode uncoated portion 330 has such a curved shape, the space in the up-down direction occupied by the cathode uncoated portion 330 may be reduced, thereby improving energy density. In addition, the increased coupling area between the cathode uncoated portion 330 and the current collector (not shown) may increase coupling force and reduce resistance.

In fig. 15 and 16, a state in which the segment 330F of the cathode uncoated portion 330 is bent in one direction is shown. The one direction may be a direction toward a winding center of the winding structure as described above.

The cathode uncoated portion 330 may be adjacent to the anode 200 side outside the separator 400. Therefore, it is preferable that the insulating layer 500a extends to the end of the cathode uncoated portion 330 on the surface facing the winding center side among the two surfaces of the cathode uncoated portion 330. According to such a structure, even if the cathode uncoated portion 330 is bent toward the winding center side and is close to the anode 200 side outside the separator 400, electrical contact between the cathode 300 and the anode 200 can be prevented. Therefore, the internal short circuit of the secondary battery can be effectively prevented.

Meanwhile, of the two surfaces of the cathode uncoated portion 330, a surface opposite to a surface facing the winding center side may be provided with the insulating layer 500a only in a partial region. That is, in the remaining part region of the surface opposite to the surface facing the winding center side, of the two surfaces of the cathode uncoated portion 330, the cathode uncoated portion 330 may be exposed to the outside. This allows electrical contact with an adjacent current collector plate (not shown). That is, the cathode uncoated portion 330 is exposed in an area not covered by the insulating layer 500a among the entire area of the cathode uncoated portion 330, and may be electrically coupled to the current collector plate. Further, the cathode uncoated portion 330 may be coupled to the current collector plate by welding in an area not covered by the insulating layer 500a among the entire area of the cathode uncoated portion 330. The welding may be, for example, laser welding. The laser welding may be performed in such a manner that the current collector plate base material is partially melted, and may also be performed in a state that the solder for welding is interposed between the current collector plate and the cathode uncoated portion 330. In this case, the solder preferably has a lower melting point than the current collector plate and the cathode uncoated portion 330. Meanwhile, resistance welding, ultrasonic welding, and the like are possible in addition to laser welding, but the welding method is not limited thereto.

Referring to fig. 17, the insulating layer 500b may have a shape surrounding an end of the cathode uncoated portion 330. Specifically, the insulating layer 500b may have a structure surrounding the end surface of the cathode uncoated portion 330. For example, when the length of the curved segment 330F of the cathode uncoated portion 330 is long, the possibility of contact with the anode 200 increases. In addition, the curved segment 330F may be further curved by flow or external pressure. At this time, the end surface of the cathode uncoated portion 330 is more likely to contact the anode 200. However, according to the above-described configuration of the present disclosure, even if the cathode uncoated portion 330 is further bent or deformed, the insulating layer 500b covers the end surface of the cathode uncoated portion 330, and thus, electrical contact between the cathode 300 and the anode 200 can be prevented.

Referring to fig. 18, the insulating layer 500c may extend to a bending point of the cathode uncoated portion 330 on a surface opposite to a surface facing the winding center side, of both surfaces of the cathode uncoated portion 330. Although not shown in fig. 18, in the wound structure, another portion of the wound anode 200 is positioned at the left side of the separator 400 positioned at the left side. That is, the cathode 300 has a possibility of making electrical contact not only with the portion of the anode 200 positioned on the right side of the cathode 300 but also with the anode 200 positioned on the left side of the cathode 300. However, according to the above-described configuration of the present disclosure, electrical contact with the anode 200 positioned at both sides of the cathode 300 can be reliably prevented.

Meanwhile, the electrode assembly according to the present embodiment may be accommodated in a battery having one side opened. The material of the battery may be aluminum. Such a battery may be electrically connected to the electrode assembly. The battery may be electrically connected to one of the cathode 300 and the anode 200. For example, the battery may be electrically connected to the anode 200 of the electrode assembly. In this case, the battery may have the same polarity as the anode 200. The anode uncoated portion 230 of the anode 200 may be electrically connected to a current collector and finally to a battery can.

Meanwhile, a terminal passing through the center portion of the closed end formed in the battery can is provided, and the terminal may be electrically connected to the other one of the cathode 300 and the anode 200. For example, the terminal may be electrically connected to the cathode 300. In this case, the terminal may have the same polarity as the cathode 300. The cathode uncoated portion 330 of the cathode 300 may be electrically connected to the current collector plate and finally electrically connected to the terminal.

In addition, the battery can and the terminal are electrically insulated from each other. The electrical insulation between the terminals and the battery can may be accomplished in various ways. For example, insulation may be achieved by inserting an insulating gasket between the terminal and the battery can.

Meanwhile, the secondary battery cell including the electrode assembly according to the present embodiment may be, for example, a secondary battery cell having a shape factor ratio (defined as a ratio of a diameter of the secondary battery cell divided by a height, i.e., a ratio of a diameter (Φ) to a height (H)) of greater than about 0.4.

Here, the form factor refers to a value indicating the diameter and height of the secondary battery cell. The secondary battery cell according to the embodiment of the present disclosure may be, for example, 46110 cell, 48750 cell, 48110 cell, 48800 cell, or 46800 cell. In the numerical values representing the form factors, the first two numbers represent the diameters of the cells, and the next two numbers represent the heights of the cells, and the last number 0 represents the cross section of the cell as a circle.

A secondary battery cell according to an embodiment of the present disclosure may be a cylindrical battery cell having a substantially cylindrical shape, which may be a cylindrical battery cell having a diameter of about 46mm, a height of about 110mm, and a shape factor ratio of about 0.418.

A secondary battery cell according to another embodiment may be a cylindrical battery cell having a substantially cylindrical shape, which may be a cylindrical battery cell having a diameter of about 48mm, a height of about 75mm, and a shape factor ratio of about 0.640.

A secondary battery cell according to still another embodiment may be a cylindrical battery cell having a substantially cylindrical shape, which may be a cylindrical battery cell having a diameter of about 48mm, a height of about 110mm, and a shape factor ratio of about 0.418.

The secondary battery cell according to still another embodiment may be a cylindrical battery cell having a substantially cylindrical shape, which may be a cylindrical battery cell having a diameter of about 48mm, a height of about 80mm, and a shape factor ratio of about 0.600.

A secondary battery cell according to still another embodiment may be a cylindrical battery cell having a substantially cylindrical shape, which may be a cylindrical battery cell having a diameter of about 46mm, a height of about 80mm, and a shape factor ratio of about 0.575.

Conventionally, a secondary battery cell having a shape factor ratio of about 0.4 or less has been used. That is, conventionally, for example, 18650 units, 21700 units, and the like have been used. For 18650 units, the diameter was about 18mm, the height was about 65mm, and the form factor ratio was about 0.277. For 21700 units, the diameter was about 21mm, the height was about 70mm, and the form factor ratio was about 0.300.

Terms indicating directions such as front side, rear side, left side, right side, upper side, and lower side have been used in the embodiments of the present disclosure, but the terms used are provided for convenience of description only and may become different according to the position of an object, the position of a viewer, and the like.

The electrode assembly according to the present embodiment described above may be accommodated in a battery can to form a battery cell. A plurality of such battery cells may be aggregated to constitute a battery module, and the battery module may be mounted together with various control and protection systems such as a BMS (battery management system) and a cooling system to form a battery pack.

The battery cell, the battery module, or the battery pack may be applied to various devices. For example, it may be applied to vehicle devices such as electric bicycles, electric automobiles, and hybrid electric vehicles, and may be applied to various devices capable of using secondary batteries, but is not limited thereto.

Although the preferred embodiments of the present disclosure have been described in detail above, the scope of the present disclosure is not limited thereto, and various modifications and improvements may be made by those skilled in the art using the basic concepts of the present disclosure as defined in the appended claims, which also fall within the scope of the present disclosure.

Description of the reference numerals

100: electrode assembly

200: anode

300: cathode electrode

400: partition piece

300D: load reducing portion

Claims (17)

1. An electrode assembly, comprising:

an anode;

a cathode; and

a separator disposed between the anode and the cathode,

Wherein the anode, the cathode, and the separator are wound together to form a wound structure,

wherein the anode includes an anode current collector and an anode active material portion formed by applying an anode active material to the anode current collector,

wherein the cathode includes a cathode current collector and a cathode active material portion formed by applying a cathode active material to the cathode current collector,

wherein an anode uncoated portion in the anode current collector to which the anode active material is not applied extends in a first direction,

wherein a cathode uncoated portion, in which the cathode active material is not applied, in the cathode current collector extends in a second direction opposite to the first direction,

wherein the cathode active material portion includes a load reduction portion in which the load of the cathode active material is smaller than that of the adjacent region, and

wherein the loading reducing portion is provided at one end of the cathode in the first direction.

2. The electrode assembly of claim 1, wherein:

the anode active material portion is disposed at a portion corresponding to the load reducing portion based on a direction perpendicular to the first direction.

3. The electrode assembly of claim 1, wherein:

the anode active material portion includes an anode boundary portion forming a boundary between the anode active material portion and the anode uncoated portion, and

the anode boundary portion is provided at a portion corresponding to the load reducing portion based on a direction perpendicular to the first direction.

4. The electrode assembly of claim 1, wherein:

the load reducing portion is formed such that the load amount of the cathode active material gradually decreases as the cathode active material proceeds in the first direction.

5. The electrode assembly of claim 1, wherein:

the first direction and the second direction are directions parallel to a height direction of the winding structure.

6. The electrode assembly of claim 1, wherein:

the anode uncoated portion extends beyond the separator in the first direction, and the cathode uncoated portion extends beyond the separator in the second direction.

7. The electrode assembly according to claim 1,

further comprising an insulating layer formed on at least one of the anode and the cathode,

an insulating layer formed on the anode covers at least a part of the anode uncoated portion and the anode active material portion, and

An insulating layer formed on the cathode covers at least a portion of the cathode uncoated portion and the cathode active material portion.

8. The electrode assembly of claim 7, wherein:

an insulating layer formed on the anode is formed to cover an end portion of the anode active material portion in the first direction and a portion of the anode uncoated portion adjacent to the end portion, and

an insulating layer formed on the cathode is formed to cover an end portion of the cathode active material portion in the second direction and a portion of the cathode uncoated portion adjacent to the end portion.

9. The electrode assembly of claim 7, wherein:

based on a direction perpendicular to the first direction, an insulating layer formed on the anode is provided at a position not overlapping the load reducing portion.

10. The electrode assembly of claim 1, wherein:

at least a portion of the sections of the anode uncoated portion and the cathode uncoated portion are machined in the form of a plurality of segments that are capable of bending independently of each other.

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

manufacturing an anode sheet such that anode active material portions to which an anode active material is applied and anode uncoated portions to which no anode active material is applied are alternately disposed on an anode current collector;

Manufacturing a cathode sheet such that a cathode active material portion to which a cathode active material is applied and a cathode uncoated portion to which no cathode active material is applied are alternately disposed on a cathode current collector;

slitting the anode uncoated portion and the anode active material portion to manufacture an anode;

slitting the cathode uncoated portion and the cathode active material portion to manufacture a cathode; and

the anode and the cathode are wound together with a separator to form a wound structure,

wherein the cathode sheet includes a load reduction region in which the load of the cathode active material is smaller than that of the adjacent region,

wherein, in the step of manufacturing the cathode, the load reduction region is slit, and

wherein, in the winding structure, the slit load reduction regions form load reduction portions in which the load amount of the cathode active material is smaller than that of the adjacent regions.

12. The method for manufacturing an electrode assembly according to claim 11, wherein:

in the winding structure, the anode uncoated portion extends in a first direction, and the cathode uncoated portion extends in a second direction opposite to the first direction.

13. The method for manufacturing an electrode assembly according to claim 12, wherein:

the loading reducing portion is provided at one end of the cathode in the first direction.

14. The method for manufacturing an electrode assembly according to claim 12, wherein:

the load reducing portion is formed such that the load amount of the cathode active material gradually decreases as the cathode active material proceeds in the first direction.

15. The method for manufacturing an electrode assembly according to claim 12, wherein:

in the winding structure, the anode active material portion is positioned at a portion corresponding to the load reducing portion based on a direction perpendicular to the first direction.

16. The method for manufacturing an electrode assembly according to claim 12, wherein:

the anode active material portion includes an anode boundary portion forming a boundary between the anode active material portion and the anode uncoated portion, and

in the winding structure, the anode boundary portion is positioned at a portion corresponding to the load reducing portion based on a direction perpendicular to the first direction.

17. The method for manufacturing an electrode assembly according to claim 11, wherein:

The loading amount of the cathode active material gradually decreases as the cathode active material proceeds toward the center portion of the loading reduction region, and

in the step of manufacturing the cathode, the load reducing portion is provided by slitting a center portion of the load reducing region.