KR20240051663A - Electrode Assembly having Electrode Tab and a Cylindrical Battery Cell using the same - Google Patents

Abstract

The present invention relates to a jelly-roll type electrode assembly including a sheet-shaped electrode, and an electrode tab electrically connected to the electrode and wound around a core together with the electrode, wherein the width direction of the electrode tab corresponds to the circumferential direction of the electrode assembly, and the length direction of the electrode tab corresponds to the axial direction of the electrode assembly. At least one groove is provided on the surface of the electrode tab facing the core of the electrode assembly, which is sunken in the centrifugal direction and extends in the length direction, and at least a portion of the length direction section of the electrode tab portion exposed to the axial end of the electrode assembly is provided with a cut portion extending in the length direction from the length direction end of the electrode tab. At least a portion of the length direction section of the electrode tab where the cut portion is provided is bent in the radial direction of the electrode assembly to form a bent portion.

Description

Electrode assembly having an electrode tab and a cylindrical battery cell including the same {Electrode Assembly having Electrode Tab and a Cylindrical Battery Cell using the same}

The present invention relates to a jelly-roll shaped electrode assembly having an electrode tab, and a battery cell containing the electrode assembly inside a cylindrical can.

A cylindrical battery cell has a cylindrical electrode assembly that is wound in a jelly-roll shape inside a cylindrical can. The cylindrical can is provided with electrode terminals that are electrically connected to have a polarity different from that of the can. And the first electrode of the electrode assembly is electrically connected to the can so that the can has a first polarity, and the second electrode of the electrode assembly is electrically connected to the electrode terminal so that the electrode terminal is the second electrode. Make it stand out. Generally, the first electrode is a cathode and the second electrode is an anode.

The jelly-roll has a form in which sheets stacked in the order of the first electrode sheet, separator, second electrode sheet, and separator are wound around the core axis. A first electrode tab and a second electrode tab are electrically connected to the first electrode sheet and the second electrode sheet, respectively, and the jelly-roll is wound with the electrode tabs connected to the electrode sheets. In the wound state, the ends of the electrode tabs protrude from the axial ends of the jelly-roll, and the protruding electrode tab portions are electrically connected to the can or electrode terminal. For electrical connection between the electrode tab and the can or the electrode tab and the electrode terminal, the protruding portion of the electrode tab can be bent in the radial direction to form a bent portion, and this bent portion can be welded to the can or electrode terminal. .

The electrode tab has a predetermined width along the circumferential direction of the jelly-roll and a predetermined length along the axial direction of the jelly-roll. Among them, in the case of the electrode tab installed on the core side of the jelly-roll, that is, on the side close to the core axis, the curvature is particularly large in the width direction of the electrode tab, so the electrode tab portion protrudes outside the jelly-roll when the width of the electrode tab is large. It becomes difficult to bend in the radial direction. For this reason, although the internal resistance of the cell can be reduced as the width of the electrode tab increases, there is a limit to increasing the width of the electrode tab.

In addition, because the thickness of the electrode tab is several times thicker than the thickness of the electrode sheet connected to it, due to the difference in rigidity between the section where the electrode tab is placed and the section where the electrode tab is not placed along the circumferential direction of the jelly-roll, the jelly-roll It was difficult to wind it close to the epicenter. This phenomenon was especially noticeable when the electrode tab was on the core side.

Meanwhile, as the charging/discharging of the cylindrical battery cell is repeated, the electrode sheet repeatedly becomes thicker or thinner, and the jelly-roll repeatedly expands or contracts in the radial direction. At this time, the outer circumference of the jelly-roll is supported by the can, so it can regulate expansion and contraction as described above, but the inner circumference, that is, the core portion, of the jelly-roll has no structure that can regulate such expansion and contraction. Accordingly, a phenomenon in which the hollow core of the jelly-roll is deformed occurs.

The present invention was created under the background of the prior art as described above, and provides a battery cell with a sufficient width of the electrode tab to further reduce internal resistance, and a structure of the electrode tab therefor.

Another technical task of the present invention is to provide a structure of an electrode tab that is easy to bend even if the width is large, and a cylindrical battery cell to which the same is applied.

Another technical problem of the present invention is to create an electrode tab structure that can further increase the roundness of the jelly-roll by preventing a difference in rigidity between a section in which electrode tabs are installed in the circumferential direction and a section in which they are not installed, and a cylindrical battery cell to which this is applied. It is provided.

Another technical object of the present invention is to provide an electrode tab structure that is easy to process and weld, and a cylindrical battery cell to which the same is applied.

Another technical object of the present invention is to provide an electrode tab structure that can prevent or reduce deformation of the core portion of a jelly-roll and a cylindrical battery cell using the same.

The technical problems of the present invention are not limited to the purposes mentioned above, and other purposes and advantages of the present invention that are not mentioned can be understood through the following description and will be more clearly understood by the examples of the present invention. . Additionally, it will be readily apparent that the objects and advantages of the present invention can be realized by the means and combinations thereof indicated in the patent claims.

The present invention was created to solve the above-mentioned problems, and is provided in a jelly-roll type electrode assembly including a sheet-shaped electrode and an electrode tab that is electrically connected to the electrode and wound around a core together with the electrode. It can be applied.

The electrode tab is installed in the electrode assembly so that the width direction of the electrode tab corresponds to the circumferential direction of the electrode assembly and the longitudinal direction of the electrode tab corresponds to the axial direction of the electrode assembly.

At least one groove recessed in the centrifugal direction and extending in the longitudinal direction is provided on the centripetal surface of the electrode tab facing the core of the electrode assembly. These grooves facilitate deformation of the electrode tab when winding the electrode tab. Then, the electrode tab can be maintained wound at or close to the epicenter.

A cut portion extending in the longitudinal direction from the longitudinal end of the electrode tab is provided in at least some of the longitudinal sections of the electrode tab portion exposed to the axial end of the electrode assembly. And at least a portion of the longitudinal section of the electrode tab where the cutout is provided is bent in the radial direction of the electrode assembly to form a bent portion.

According to the electrode assembly having this structure, even if the width of the electrode tab is wide, the area to be bent is divided by a cut portion, so that the width of two or more individual bent portions formed in one electrode tab can be reduced. Therefore, the forming of the bent portion becomes smooth regardless of the overall width of the electrode tab. Additionally, deformation of the electrode tab that may occur due to processing of the bent portion can be minimized.

The electrode tab may be disposed on the core side of the electrode assembly. Then, due to the electrode tab, the area around the hollow portion of the core (core portion) of the electrode assembly can be maintained close to the epicenter.

The central angle of the width of the electrode tab in the electrode assembly may be 180 degrees or more and 360 degrees or less.

Preferably, the central angle of the width of the electrode tab in the electrode assembly may be substantially 360 degrees. The thickness of the electrode tab is thicker than the thickness of the sheet-shaped electrode. Accordingly, the electrode tab not only serves as an electrical passage for the battery, but also reinforces the strength of the core hollow portion, that is, the inner peripheral portion, of the electrode assembly. Then, the attachment width of the electrode tab at the core of the electrode assembly can be greatly increased, thereby lowering the internal resistance of the battery, and the electrode tab prevents deformation of the core of the electrode assembly that occurs during the charging/discharging process of the battery. Deformation of the core part can be alleviated.

Two or more grooves may be provided, and the grooves may be arranged along the width direction of the electrode tab. Then, even if the electrode tab, which is thicker than the thickness of the sheet-shaped electrode, is disposed on the core side of the electrode assembly and has a greater curvature or a smaller radius of curvature than the sheet-shaped electrode, the electrode tab can be wound smoothly. It can be done.

The grooves may be arranged at equal intervals along the circumferential direction. Because of this, the winding shape of the electrode tab can be substantially circular.

The groove may have a shape whose width gradually decreases in the depth direction. Accordingly, when the portion corresponding to the groove is deformed more than the remaining portion as the electrode tab is wound, the phenomenon of interference between the two inner surfaces of the groove facing each other with the groove in between can be further minimized.

Specifically, the shape of the electrode tab portion corresponding to two adjacent grooves in the width direction may be an equilateral trapezoid or an isosceles triangle.

The incision may be provided in the groove.

The number of incisions may be equal to or less than the number of grooves.

The groove may be formed through press processing or the like.

The incision may be processed with an optical cutter such as a laser or a mechanical cutter such as a knife.

The central angle occupied by the width direction end of the electrode tab and the section between the adjacent cutouts in the electrode assembly, or the central angle occupied by the section between two adjacent cutouts in the electrode assembly may be 45 degrees or more and 120 degrees or less. there is. That is, the central angle occupied by the width of the bent portion may be between 45 degrees and 120 degrees. Preferably, the central angle may be 60 degrees or more and 90 degrees or less. More preferably, the central angle may be substantially 90 degrees.

If the central angle occupied by the width of the bent portion is less than 45 degrees, there is a possibility that the number of bent portions may become too large. Additionally, if the width of the bent portion exceeds 120 degrees, the forming of the bent portion will not be performed smoothly.

The bent portion may be bent in the centripetal direction of the electrode assembly.

When viewed in the axial direction, the bent portion may cover at least a portion of the hollow portion of the core. The bent portion covering the hollow portion of the core can be welded to the can accommodating the electrode assembly or to the electrode terminal installed on the can. This welding may be resistance welding.

The length of the portion where the electrode tab is bent in the radial direction may be 2/3 or more and 1 or less of the diameter of the core hollow portion. Preferably, the length may be 3/4 or more and 5/6 or less of the diameter of the hollow portion of the winding core. More preferably, the length may be substantially 4/5 of the diameter of the core hollow portion.

If the length is less than 2/3, the area of the core hollow portion covered by the bent portion is small, and the mutually overlapping area between the bent portions is narrowed, making it difficult to secure a welding area between the bent portion and the can that accommodates the electrode assembly. You can. On the other hand, if the length exceeds 1, when one bent part is bent, a phenomenon in which the bent part interferes with another bent part occurs.

When viewed in the axial direction of the electrode assembly, the end of the bent portion of the electrode tab may be disposed within the cross section of the core hollow portion of the electrode assembly.

The bent portions that face each other with the center of the electrode assembly in between may overlap at least some areas when viewed in the axial direction.

At least some areas of adjacent bent portions in the circumferential direction of the electrode assembly may overlap each other when viewed in the axial direction.

These overlapping parts can be welded together to the can or electrode terminals installed on the can.

In contrast, one of the bent parts facing each other across the center of the electrode assembly may be bent in a centripetal direction, and the other may be bent in a centripetal direction. This can simplify the bending process of the electrode tab.

Alternatively, the bent portion may be bent in the centrifugal direction of the electrode assembly.

The bent portion may be welded to a can that accommodates the electrode assembly. This welding may be laser welding.

Additionally, the present invention provides a cylindrical cell containing the electrode assembly in the can. The bent portion of the electrode assembly may be welded to the can or to an electrode terminal installed on the can.

In the cylindrical battery cell having the electrode tab structure according to the present invention, the width of the bent portion can be divided in the circumferential direction due to the cut portion provided at the longitudinal end of the electrode tab, so even if the width of the electrode tab is large, the bent portion is formed by bending. This can be done smoothly.

The cylindrical battery cell having the electrode tab structure according to the present invention can secure a sufficient width of the electrode tab, thereby further lowering the internal resistance of the battery cell.

The cylindrical battery cell having the electrode tab structure according to the present invention significantly reduces the winding resistance of the electrode tab due to one or more grooves formed in the electrode tab, thereby minimizing the difference between the winding resistance rigidity of the electrode tab and the winding resistance rigidity of the electrode sheet. You can. Accordingly, in the circumferential direction of the electrode assembly, the difference in curvature between the section where the electrode tab is placed and the section where the electrode tab is not placed can be minimized, thereby further increasing the roundness of the electrode assembly.

The cylindrical battery cell having the electrode tab structure according to the present invention is arranged to surround the entire circumferential direction of the core without difficulty in bending the bent portion and while minimizing the difference in curvature between the electrode sheet and the electrode tab. It is possible. Therefore, through these electrode tabs, it is possible to prevent or reduce deformation of the core part of the jelly-roll during the charging/discharging process.

In addition to the above-described effects, specific effects of the present invention are described below while explaining specific details for carrying out the invention.

Figures 1 and 2 are a perspective view and a front view schematically showing a press for processing electrode tabs according to the present invention.
Figure 3 is a front view showing a state in which the upper die of Figure 2 is lowered to process an electrode tab.
Figure 4 is a perspective view schematically expressing a roll press processing an electrode tab according to the present invention.
Figure 5 is a perspective view showing an electrode tab whose surface is grooved by a press or roll press.
FIG. 6 is a plan view showing the electrode tab of FIG. 5 with a cutout portion formed therein.
Figures 7 and 8 are a plan view and a front view showing a state in which a separator, a first electrode, a separator, and a second electrode in the form of a long sheet are stacked in that order, and the electrode tab of Figure 6 is connected to the second electrode.
Figures 9 and 10 are a perspective view and a plan view showing a state in which a jelly-roll shaped electrode assembly is formed by winding sheets stacked in the direction shown in Figure 8.
Figure 11 is a perspective view showing only the electrode tab portion of Figure 9.
FIGS. 12 and 13 are a perspective view and a plan view showing a state in which one of the electrode tab portions divided by a cut portion at the longitudinal end of the electrode tab shown in FIGS. 9 to 11 is bent radially inward.
Figure 14 is a perspective view showing only the electrode tab portion of Figure 12.
FIGS. 15 and 16 are a perspective view and a plan view showing one of the electrode tab portions divided by a cut portion at the longitudinal end of the electrode tab shown in FIGS. 12 to 14 bent further radially inward.
Figure 17 is a perspective view showing only the electrode tab portion of Figure 15.
Figures 18 and 19 are a perspective view and a plan view showing a state in which one of the electrode tab parts divided by a cut portion at the longitudinal end of the electrode tab shown in Figures 15 to 17 is bent further radially inward.
Figure 20 is a perspective view showing only the electrode tab portion of Figure 18.
21 and 22 show that the last part of the electrode tab divided by the cut portion at the longitudinal end of the electrode tab shown in Figures 18 to 21, which has not yet been bent, is bent radially inward to bend all electrode tab parts. It is a perspective view and a plan view showing one state.
Figure 23 is a perspective view showing only the electrode tab portion of Figure 21.
Figure 24 is a perspective view showing the process of accommodating the electrode assembly in a can with an insulator on the bottom in a state where the electrode assembly of Figure 21 is upside down.
Figure 25 is a front cross-sectional view showing the electrode assembly and insulator of Figure 24 housed in a can.
Figure 26 is a perspective view of another embodiment of the electrode tab according to the present invention.
Figure 27 is a front view of the electrode tab of Figure 26.
FIG. 28 is a perspective view showing the electrode tab shown in FIGS. 26 and 27 in a wound state, and FIG. 29 is a plan view thereof.
Figure 30 is a perspective view of another embodiment of an electrode tab according to the present invention.
FIG. 31 is a front view of the electrode tab of FIG. 30.
Figure 32 is a perspective view showing the electrode tab shown in Figures 30 and 31 in a wound state, and Figure 33 is a plan view thereof.
Figures 34 and 35 are front cross-sectional views showing other embodiments in which the electrode tabs of the electrode assembly are bent.

The above-described objects, features, and advantages will be described in detail later with reference to the attached drawings, so that those skilled in the art will be able to easily implement the technical idea of the present invention. In describing the present invention, if it is determined that a detailed description of known techniques related to the present invention may unnecessarily obscure the gist of the present invention, the detailed description will be omitted. Hereinafter, preferred embodiments according to the present invention will be described in detail with reference to the attached drawings. In the drawings, identical reference numerals are used to indicate identical or similar components.

Although first, second, etc. are used to describe various components, these components are of course not limited by these terms. These terms are only used to distinguish one component from another component, and unless specifically stated to the contrary, the first component may also be a second component.

Throughout the specification, unless otherwise stated, each element may be singular or plural.

Hereinafter, the “top (or bottom)” of a component or the arrangement of any component on the “top (or bottom)” of a component means that any component is placed in contact with the top (or bottom) of the component. Additionally, it may mean that other components may be interposed between the component and any component disposed on (or under) the component.

Additionally, when a component is described as being “connected,” “coupled,” or “connected” to another component, the components may be directly connected or connected to each other, but the other component is “interposed” between each component. It should be understood that “or, each component may be “connected,” “combined,” or “connected” through other components.

As used herein, singular expressions include plural expressions unless the context clearly dictates otherwise. In the present application, terms such as “consists of” or “comprises” should not be construed as necessarily including all of the various components or steps described in the specification, and some of the components or steps may include It may not be included, or it should be interpreted as including additional components or steps.

Additionally, as used herein, singular expressions include plural expressions, unless the context clearly dictates otherwise. In the present application, terms such as “consists of” or “comprises” should not be construed as necessarily including all of the various components or steps described in the specification, and some of the components or steps may include It may not be included, or it should be interpreted as including additional components or steps.

Throughout the specification, when referred to as “A and/or B”, this means A, B or A and B, unless specifically stated to the contrary, and when referred to as “C to D”, this means unless specifically stated to the contrary. Unless there is one, it means that it is C or higher and D or lower.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

In describing the embodiment, the axial direction refers to the direction in which the axis of the core 6 of the jelly roll-shaped electrode assembly extends. The axial direction of the electrode assembly may correspond to the longitudinal direction of the electrode tab connected to the electrode assembly.

In describing the embodiment, the circumferential direction or circumferential direction refers to the winding direction of the electrode assembly. This refers to the direction surrounding the core axis of the electrode assembly, and may correspond to the width direction of the electrode tab connected to the electrode assembly.

In describing the embodiment, the radial direction or radial direction means a direction closer to or away from the core axis of the electrode assembly. The direction approaching the core axis can be called the centripetal direction, and the direction away from the core axis can be called the centripetal direction. The radial direction may correspond to the thickness direction of the electrode tab connected to the electrode assembly. In addition, the centripetal direction of the electrode assembly may correspond to the direction that the inner surface of the electrode tab faces, that is, the normal direction, and the centrifugal direction of the electrode assembly may correspond to the direction that the outer surface of the electrode tab faces, that is, the normal direction.

The drawings presented to explain embodiments of the present invention are exaggerated or simplified drawings for understanding of the invention and do not represent the actual object itself.

1 to 6 show devices related to an electrode tab and a processing method thereof according to an embodiment of the present invention.

First, referring to FIG. 5, the electrode tab 40 of the embodiment according to the present invention has a shape in which a groove 41 extending in the longitudinal direction is formed on the surface of a metal sheet extending long in the longitudinal direction with a predetermined width. have The grooves 41 are provided in plural numbers, and the plurality of grooves 41 are arranged in the width direction.

An example of a method of processing the electrode tab 40 in this form will be described with reference to FIGS. 1 to 3. First, the electrode tab 40 before the groove 41 is processed is placed on the lower die 2-2, which is the second type of the press 2, as shown in Figures 1 and 2, and it is placed on the upper die, which is the first type. By pressing and forming (2-1) as shown in FIG. 3, the groove 41 can be formed on the surface of the electrode tab 40 as shown in FIG. 5.

Another example of machining a groove 41 in the electrode tab 40 will be described with reference to FIG. 4 . When the electrode tab base material before the groove 41 is processed is supplied to the rolling roll 4, which is a roll press, in the longitudinal direction and rolled, the upper roll 4-1, which is the first roll, has a protruding shape corresponding to the groove 41. ) and the lower roll (4-2), which is a flat second roll, continuously processes the groove (41). By cutting the electrode tab base material with the grooves 41 machined in this way to a certain length, an electrode tab 40 of a certain length with the grooves 41 formed on the surface can be manufactured, as shown in FIG. 5.

The shape of the groove 41 may be such that its width gradually decreases as it goes from the surface to the depth. As an example, this shape may be like the two equilateral sides of an isosceles triangle. However, the cross-sectional shape of the groove 41 is not limited to this. For example, grooves 41 of various shapes such as trapezoid, parabola, semicircle, and semi-ellipse can be applied.

As the shape of the electrode tab portion divided by the two adjacent grooves 41 in the width direction, an equilateral trapezoid shape is exemplified in the embodiment. However, the shape is not necessarily limited to this, and various shapes such as an isosceles triangle (see Figure 31) and a rectangle can be applied. This shape will correspond to the cross-sectional shape of the groove 41.

When the cut portion 43 is formed for a predetermined length from the longitudinal end of the electrode tab 40 manufactured in this way, one longitudinal end of the electrode tab 40 is formed into a plurality of pieces in the width direction, as shown in FIG. 6. A divided electrode tab 40 can be manufactured. The cutting portion 43 may be processed using laser processing or cutter knives.

The location where the cut portion 43 is formed in the width direction may be a portion of the groove 41.

5 and 6 show the electrode tab 40 with the same number of grooves 41 and the same number of cuts 43, but the number of grooves 41 and the number of cuts 43 must match. That is not the case. Of course, like other embodiments of the electrode tab 40 shown in FIGS. 26 to 33, the number of grooves 41 may be greater than the number of cut portions 43.

Additionally, the incision 43 does not necessarily have to be formed at the location of the groove 41. However, if the cut portion 43 is formed at the location of the groove 41, cutting processing is easier, and the processing process of bending the portion of the electrode tab 40 divided by the cut portion 43, as will be described later, is easier. It can be easy.

The number of the cut portions 43 may be one or more, and in the embodiments, a structure in which three cut portions 43 are formed is exemplified. However, the number of incisions 43 is not limited to this and may vary, such as 4, 5, or 6.

Figures 7 and 8 show a state in which the sheet-shaped electrode 30 and the separator 50 are stacked, and the electrode tab 40 is electrically connected to the electrode by welding or the like.

As shown, the electrode and separator in the form of a rectangular sheet with a predetermined width in the axial direction and extending long in the winding direction are a first separator 51, a first electrode 31, and a second separator 52. , and the second electrode 32 may be formed in that order. The first electrode 31 may be a cathode, and the second electrode 32 may be an anode.

The positive electrode and negative electrode may be coated with a positive electrode active material and a negative electrode active material on the surfaces of the positive electrode current collector and the negative electrode current collector, respectively.

In the present invention, the positive electrode active material coated on the positive electrode and the negative electrode active material coated on the negative electrode plate can be used without limitation as long as they are active materials known in the art.

The positive electrode active material may be a layered compound such as lithium cobalt oxide (LiCoO ₂ ), lithium nickel oxide (LiNiO ₂ ), or a compound substituted with one or more transition metals; Lithium manganese oxide (LiMnO ₂ ) with the formula Li _1+x Mn _2-x O ₄ (where x is 0 to 0.33), LiMnO ₃ , LiMn ₂ O ₃ , LiMnO ₂ , etc.; lithium copper oxide (Li ₂ CuO ₂ ); Vanadium oxides such as LiV ₃ O ₈ , LiFe ₃ O ₄ , V ₂ O ₅ , and Cu ₂ V ₂ O ₇ ; _Nickelsite type lithium nickel oxide (lithiated nickel) represented by the formula LiNi _{1-x M} oxide); _{Formula LiMn 2 - x M} Lithium manganese complex oxide expressed as Ni, Cu or Zn); LiMn ₂ O ₄ in which part of the lithium in the chemical formula is replaced with alkaline earth metal ions; disulfide compounds; It is mainly composed of lithium intercalation material, such as Fe ₂ (MoO ₄ ) ₃ or a complex oxide formed by a combination thereof, and there are types like the above, but it is not limited to these.

The positive electrode current collector has a thickness of, for example, 3 to 500 ㎛. This positive electrode current collector is not particularly limited as long as it is conductive without causing chemical changes in the battery, and may include, for example, stainless steel, aluminum, nickel, titanium, calcined carbon, or carbon on the surface of aluminum or stainless steel. , surface treated with nickel, titanium, silver, etc. can be used. The electrode current collector can increase the adhesion of the positive electrode active material by forming fine irregularities on its surface, and can take various forms such as films, sheets, foils, nets, porous materials, foams, and non-woven fabrics.

A conductive material may be additionally mixed with the positive electrode active material particles. This conductive material is added, for example, in an amount of 1 to 50% by weight based on the total weight of the mixture including the positive electrode active material. These conductive materials are not particularly limited as long as they have high conductivity without causing chemical changes in the battery, and examples include graphite such as natural graphite and artificial graphite; Carbon black, such as carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black, and summer black; Conductive fibers such as carbon fiber and metal fiber; Metal powders such as carbon fluoride, aluminum, and nickel powder; Conductive whiskeys such as zinc oxide and potassium titanate; Conductive oxides such as titanium oxide; Conductive materials such as polyphenylene derivatives may be used.

In addition, the negative electrode is manufactured by applying and drying negative electrode active material particles on the negative electrode current collector, and if necessary, components such as the conductive material, binder, solvent, etc. described above may be further included.

The negative electrode current collector has a thickness of, for example, 3 to 500 ㎛. This negative electrode current collector is not particularly limited as long as it is conductive without causing chemical changes in the battery, for example, copper, stainless steel, aluminum, nickel, titanium, fired carbon, the surface of copper or stainless steel. Surface treatment with carbon, nickel, titanium, silver, etc., aluminum-cadmium alloy, etc. can be used. In addition, like the positive electrode current collector, the bonding power of the negative electrode active material can be strengthened by forming fine irregularities on the surface, and can be used in various forms such as films, sheets, foils, nets, porous materials, foams, and non-woven materials.

The negative electrode active material includes, for example, carbon such as non-graphitized carbon and graphitic carbon; Li _x Fe _{2 O 3 (} 0≤x≤1), Li _x WO ₂ (0≤x≤1), _Sn Al, B, P, Si, group 1, 2, and 3 elements of the periodic table, halogen; 1≤y≤3; 1≤z≤8); lithium metal; lithium alloy; silicon-based alloy; tin-based alloy; SnO, SnO ₂ , PbO, PbO ₂ , Pb ₂ O ₃ , Pb ₃ O ₄ , Sb ₂ O ₃ , Sb ₂ O ₄ , Sb ₂ O ₅ , GeO, GeO ₂ , Bi ₂ O ₃ , Bi ₂ O ₄ , oxides such as Bi ₂ O ₅ ; Conductive polymers such as polyacetylene; Li-Co-Ni based materials, etc. can be used.

The binder polymer that can be used in the electrode is a component that assists in the bonding of the electrode active material particles and the conductive material and the bonding to the electrode current collector, for example, 1 to 50% by weight based on the total weight of the mixture containing the electrode active material. is added. Examples of such binder polymers include polyvinylidene fluoride-co-hexafluoropropylene (PVdF), polyvinylidene fluoride-co-trichloroethylene, and polymethyl methacrylate. (polymethylmethacrylate), polybutylacrylate, polyacrylonitrile, polyvinylpyrrolidone, polyvinylacetate, polyethylene-co-vinyl acetate, Polyethylene oxide, polyarylate, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, cyanoethylpullulan, Any one binder selected from the group consisting of cyanoethylpolyvinylalcohol, cyanoethylcellulose, cyanoethylsucrose, pullulan, and carboxyl methyl cellulose Polymers or mixtures of two or more of them may be used, but are not limited thereto.

Non-limiting examples of solvents used to manufacture the electrode include acetone, tetrahydrofuran, methylene chloride, chloroform, dimethylformamide, and N-methyl-2. -N-methyl-2-pyrrolidone (NMP), cyclohexane, water, or mixtures thereof. These solvents provide an appropriate level of viscosity so that a slurry coating layer can be created at a desired level on the electrode current collector surface.

The negative electrode includes a current collector; and a negative electrode active material layer located on at least one surface of the current collector and including a negative electrode active material, a binder polymer, and a conductive material, wherein the negative electrode active material layer has a lower layer area in contact with the current collector and a negative electrode layer while in contact with the lower layer area. It consists of an upper layer region extending to the surface of the active material layer, and the lower layer region and the upper layer region may each independently include at least one type of graphite or a silicon-based compound as a negative electrode active material.

The lower layer region may include natural graphite as a negative electrode active material, and the upper layer region may include artificial graphite as a negative electrode active material.

The lower layer region and the upper layer region may each independently further include a silicon-based compound as a negative electrode active material.

The silicon-based compound is SiO _x (0 x 2) and may include one or more of SiC.

According to one embodiment of the present invention, the negative electrode is formed by applying and drying a lower layer slurry containing a lower layer negative electrode active material on a current collector to form a lower layer area, and then forming an upper layer slurry containing a lower layer negative electrode active material on the lower layer area. It can be manufactured by applying and drying the slurry to form an upper layer region.

In addition, according to one embodiment of the present invention, the negative electrode includes the steps of preparing a slurry for a lower layer containing a negative electrode active material for a lower layer; and a slurry for an upper layer containing a negative electrode active material for an upper layer;

Coating the lower layer slurry on one surface of a negative electrode current collector and coating the upper layer slurry on the lower layer slurry simultaneously or at a predetermined time interval; and

It may be manufactured by a method comprising: simultaneously drying the coated slurry for the lower layer and the slurry for the upper layer to form an active material layer.

In the case of manufacturing by the latter method, a mixed region (intermixing) in which different types of active materials are mixed may exist in the portion where the lower layer region and the upper layer region of the cathode come into contact. This is to form an active material layer by coating the lower layer slurry containing the lower layer negative electrode active material and the upper layer slurry containing the upper layer negative electrode active material on the current collector simultaneously or continuously with a very short time difference, and then drying them simultaneously. In this case, a predetermined mixing section occurs on the interface where the slurry for the lower layer and the slurry for the upper layer come into contact before drying, and as they are dried, this mixing section is formed in the form of a layer of mixing area.

In the active material layer of the negative electrode of one embodiment of the present invention, the upper region and the lower region The weight ratio (or ratio of loading amount per unit area) may be 20:80 to 50:50, specifically 25:75 to 50:50.

The thickness of the lower region and upper region of the active material layer of the negative electrode of the present invention may not completely match the thicknesses of the coated slurry for the lower layer and the slurry for the coated upper layer. However, as a result of the drying or selective rolling process, the ratio of the thickness of the lower layer region and the upper layer region of the active material layer of the negative electrode of the finally obtained negative electrode of the present invention is the thickness of the coated lower layer slurry and the coated upper layer slurry. It may be consistent with the ratio.

The first slurry is coated, and the second slurry is coated on the first slurry simultaneously or with a predetermined time difference, and according to one embodiment of the present invention, the predetermined time difference is 0.6 seconds or less, or 0.02 seconds to 0.02 seconds. The time difference may be 0.6 seconds, or 0.02 seconds to 0.06 seconds, or 0.02 seconds to 0.03 seconds. Since the time difference that occurs when coating the first slurry and the second slurry is due to the coating equipment, it may be more preferable to coat the first slurry and the second slurry at the same time. A method of coating the second slurry on the first slurry may use a device such as a double slot die.

In forming the active material layer, the step of rolling the active material layer after the drying step may be further included. At this time, rolling may be performed by a method commonly used in the art, such as roll pressing, and may be performed, for example, at a pressure of 1 to 20 MPa and a temperature of 15 to 30°C.

The step of simultaneously drying the coated slurry for the lower layer and the slurry for the upper layer to form an active material layer may be performed by a method commonly used in the art using a combination of hot air drying and infrared drying equipment.

The weight percent of the first binder polymer in the solid content of the slurry for the lower layer may be equal to or greater than the weight percent of the second binder polymer in the solid content of the slurry for the upper layer. According to one embodiment of the present invention, the weight percent of the first binder polymer in the solid content of the slurry for the lower layer is 1.0 to 4.2 times, or 1.5 to 3.6 times the weight percent of the second binder polymer in the solid content of the slurry for the upper layer, Or it may be 1.5 to 3 times larger.

At this time, when the ratio of the weight % of the first binder in the coated slurry for the lower layer and the weight % of the second binder in the coated slurry for the upper layer satisfies this range, the binder in the lower layer region is not too small and the electrode layer is detached. does not occur, and there is not too much binder in the upper layer region, so the resistance of the upper layer of the electrode is reduced and rapid charging performance can be advantageous.

The weight percent of the first binder polymer in the solid content of the lower layer slurry is 2 to 30 weight percent, or 5 to 20 weight percent. Or it may be 5 to 20% by weight, and the proportion (% by weight) of the second binder polymer in the solid content of the slurry for the upper layer is 0.5 to 20% by weight, or 1 to 15% by weight, or 1 to 10% by weight, or 2 It may be from 5% by weight.

The total ratio (% by weight) of the first binder polymer and the second binder polymer in the total solid content of the slurry for the lower layer and the slurry for the upper layer may be 2 to 20% by weight, or 5 to 15% by weight.

The separator is a porous polymer substrate; and a porous coating layer located on both sides of the porous polymer substrate and containing inorganic particles and a binder polymer.

The porous polymer substrate may be a polyolefin-based porous substrate.

The polyolefin porous substrate may be in the form of a film or non-woven web. By having such a porous structure, the electrolyte can move smoothly between the anode and the cathode, and the electrolyte impregnation of the substrate itself can be increased to ensure excellent ionic conductivity. In addition, an increase in resistance inside the electrochemical device is prevented, thereby increasing the electrical power. Deterioration in the performance of chemical devices can be prevented.

The polyolefin porous substrate used in the present invention can be any planar porous substrate commonly used in electrochemical devices, and its material or shape can be selected in various ways depending on the purpose.

The polyolefin porous substrate may be, but is not limited to, high-density polyethylene, low-density polyethylene, linear low-density polyethylene, ultra-high molecular weight polyethylene, polypropylene, or a film or non-woven web formed of a mixture of two or more of these. It is not limited to this.

The polyolefin porous substrate may have a thickness of 8 to 30 ㎛, but this is only an example and thicknesses outside the above range may be adopted in consideration of mechanical properties or high rate charge/discharge characteristics of the battery.

The nonwoven sheet according to the present invention may be formed of polyethylene (PE), polypropylene (PP), or a mixture of two or more thereof. For example, the nonwoven sheet may be manufactured by fiber spinning. For example, it may be manufactured by mixing the fibers of the above material into fiber spinning form at a melting point or higher using a melt blown method.

The nonwoven sheet may have an elongation of 200 to 400%, more preferably 300 to 400%. If the elongation rate is less than 200%, the probability of contact between electrodes increases when the nail penetrates, and if it is greater than 400%, the area around the nail penetration is also stretched, making the separator thinner and reducing the barrier property. I do it.

A plurality of pores having an average diameter of 0.1 to 10 μm are formed in the nonwoven fabric sheet. If the pore size is smaller than 0.1㎛, smooth movement of lithium ions and/or electrolyte may not occur, and if the pore size is larger than 10㎛, the anode and cathode may be damaged due to stretching of the non-woven fabric sheet when the nail penetrates. The effect of the present invention to prevent contact may not be achieved.

Additionally, the nonwoven sheet may have a porosity of 40 to 70%. If the porosity is less than 40%, smooth movement of lithium ions and/or electrolyte may not occur, and if the porosity is greater than 70%, the pattern is designed to prevent contact between the anode and cathode by stretching the non-woven sheet when nail penetration. The effect of the invention may not be achieved. The nonwoven sheet prepared in this way may have an air permeability of 1 to 20 seconds/100 mL.

Additionally, the nonwoven sheet may have a thickness of 10 to 20 ㎛, but this is only an example and is not limited thereto. Depending on the permeability of the non-woven fabric sheet, non-woven fabric sheets with thicknesses outside the above range can also be adopted.

The nonwoven sheet may be joined to a separator component underlying the nonwoven sheet by lamination. The lamination may be performed in a temperature range of 100 to 150°C. If the lamination is performed at a temperature lower than 100°C, the lamination effect will not occur, and if the lamination is performed at a temperature higher than 150°C, the nonwoven fabric may be damaged. Some of it melts.

Compared to a separator made of a conventional non-woven fabric sheet, the separator according to one aspect of the present invention, which is laminated under the above conditions, is a separator in which a layer containing inorganic particles is formed on at least one side of the film or non-woven fabric sheet. Compared to , it has improved resistance to nail penetration.

In the porous coating layer, the inorganic particles may be bound to each other by the binder polymer in a state where they are filled and in contact with each other, and as a result, an interstitial volume is formed between the inorganic particles, thereby forming an interstitial volume between the inorganic particles. The static volume can become an empty space to form a pore.

The inorganic particles used to form the porous coating layer include additional inorganic particles, that is, inorganic particles in which oxidation and/or reduction reactions do not occur in the operating voltage range of the electrochemical device (e.g., 0 to 5 V based on Li/Li ⁺ ). You can use it. In particular, when using inorganic particles capable of ion transport, performance can be improved by increasing the ionic conductivity within the electrochemical device. In addition, when inorganic particles with a high dielectric constant are used as the inorganic particles, the ionic conductivity of the electrolyte solution can be improved by contributing to an increase in the degree of dissociation of electrolyte salts, such as lithium salts, in the liquid electrolyte.

For the above-mentioned reasons, the inorganic particles preferably include high dielectric constant inorganic particles having a dielectric constant of 5 or more, preferably 10 or more, inorganic particles having lithium ion transport ability, or a mixture thereof.

Non-limiting examples of inorganic particles with a dielectric constant of 5 or more include BaTiO ₃ , Pb(Zr,Ti)O ₃ (PZT), Pb _1-x La _x Zr _1-y Ti _y O ₃ (PLZT), PB(Mg _{1 /3} Nb _2/3 )O ₃ -PbTiO ₃ (PMN-PT), hafnia (HfO ₂ ), SrTiO ₃ , SnO ₂ , CeO ₂ , MgO, NiO, CaO, ZnO, ZrO ₂ , Y ₂ O ₃ , Al ₂ O ₃ , TiO ₂ , SiC or mixtures thereof.

In particular, the above-mentioned BaTiO ₃ , Pb(Zr,Ti)O ₃ (PZT), Pb _1-x La _x Zr _1-y Ti _y O ₃ (PLZT), PB(Mg _1/3 Nb _2/3 )O ₃ -Inorganic particles such as PbTiO ₃ (PMN-PT) and hafnia (HfO ₂ ) not only exhibit high dielectric constant characteristics with a dielectric constant of 100 or more, but also generate electric charges when stretched or compressed by applying a certain pressure, creating a potential difference between both sides. By having piezoelectricity, it is possible to improve the safety of electrochemical devices by preventing internal short circuits of both electrodes due to external shock. In addition, when the above-mentioned high dielectric constant inorganic particles and inorganic particles having lithium ion transport ability are mixed, their synergistic effect can be doubled.

Inorganic particles having the ability to transport lithium ions refer to inorganic particles that contain lithium element but do not store lithium but have the function of moving lithium ions. Inorganic particles with lithium ion transport ability can transport and move lithium ions due to a type of defect present inside the particle structure, thereby improving lithium ion conductivity in the battery, thereby improving battery performance. You can. Non-limiting examples of the inorganic particles having the ability to transport lithium ions include lithium phosphate (Li ₃ PO ₄ ), lithium titanium phosphate (Li _x Ti _y (PO ₄ ) ₃ , 0<x<2, 0<y<3) _{, lithium aluminum titanium phosphate ( Li ​ ​ 2} O _{5 ,} etc. (LiAlTiP) _x O _y series glass (0 < x < ₄ , 0 < y < 13), lithium _lanthanum titanate (Li ), lithium germanium thiophosphate (Li _x Ge _y P _z S _{w ,} 0 < x < ₄ , 0 < y < ₁ , 0 < z < 1 _, 0 < w < 5), lithium nitride (Li _x N _y , 0 < x < 4, 0 _< y < ₂ ) such as Li ₃ N _{, SiS 2 series} glass ₍ Li _{x P 2} S _{5 series} glass (Li _{x P y S z ,} 0 _< x<3, 0<y<3, 0<z<7) or mixtures thereof.

The size of the inorganic particles in the porous coating layer is not limited, but is preferably 0.001 to 10 ㎛ in order to form a coating layer of uniform thickness and have an appropriate porosity. If it is less than 0.001㎛, the dispersibility of inorganic particles may decrease, and if it exceeds 10㎛, the thickness of the porous coating layer may increase and mechanical properties may deteriorate, and internal short circuits may occur during battery charging and discharging due to excessively large pore sizes. The probability of it happening increases.

Binder polymers that form the porous coating layer include polyvinylidene fluoride-co-hexafluoropropylene (PVdF), polyvinylidene fluoride-co￢trichloroethylene, and polymethyl. methacrylate, polybutylacrylate, polyacrylonitrile, polyvinylpyrrolidone, polyvinylacetate, ethylene vinyl acetate copolymer (polyethylene-co-vinyl) acetate, polyethylene oxide, polyarylate, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, cyanoethylflurane ( From the group consisting of cyanoethylpullulan, cyanoethylpolyvinylalcohol, cyanoethylcellulose, cyanoethylsucrose, pullulan, and carboxyl methyl cellulose. Any one selected binder polymer or a mixture of two or more of them may be used, but is not limited thereto.

The composition ratio of the inorganic particles and binder polymer used in the porous coating layer is preferably in the range of, for example, 50:50 to 99:1, and more preferably 70:30 to 95:5. If the content ratio of the inorganic particles to the binder polymer is less than 50:50, the content of the binder polymer increases and the improvement in thermal safety of the separator may be reduced. In addition, the pore size and porosity are reduced due to a decrease in the empty space formed between the inorganic particles, which may cause a decrease in final battery performance. If the content of the inorganic particles exceeds 99 parts by weight, the peeling resistance of the porous coating layer may be weakened because the binder polymer content is too low. The thickness of the porous coating layer is not particularly limited, but is preferably in the range of 0.01 to 20㎛. In addition, there is no particular limitation to the pore size and porosity, but the pore size is preferably in the range of 0.001 to 10㎛, and the porosity is preferably in the range of 10 to 90%. Pore size and porosity mainly depend on the size of the inorganic particles. For example, when inorganic particles with a particle diameter of 1 ㎛ or less are used, the pores formed are also approximately 1 ㎛ or less. This pore structure is filled with an electrolyte that is later injected, and the filled electrolyte plays a role in ion transfer. If the pore size and porosity are less than 0.001㎛ and 10%, respectively, it may act as a resistance layer, and if the pore size and porosity exceed 10㎛ and 90%, respectively, mechanical properties may be reduced.

The porous coating layer can be formed by dissolving or dispersing a binder polymer in a dispersion medium, adding inorganic particles to obtain a slurry for forming a porous coating layer, and coating and drying this slurry on at least one side of the substrate. The dispersion medium is preferably one that has a solubility index similar to that of the binder polymer to be used and a low boiling point. This is to facilitate uniform mixing and subsequent removal of the dispersion medium. Non-limiting examples of usable dispersion media include acetone, tetrahydrofuran, methylene chloride, chloroform, dimethylformamide, N-methyl-2-pyrrolidone ( Examples include N-methyl-2-pyrrolidone (NMP), cyclohexane, water, or mixtures thereof.

It is preferable to crush the inorganic particles after adding the inorganic particles to the dispersion liquid in which the binder polymer is dispersed in the dispersion medium. At this time, the appropriate crushing time is 1 to 20 hours, and the particle size of the crushed inorganic particles is preferably 0.001 to 10 ㎛ as described above. Conventional methods can be used as the crushing method, and the ball mill method is especially preferable.

Then, the binder polymer dispersion in which the inorganic particles are dispersed is coated on at least one side of the porous polymer substrate under humidity conditions of 10 to 80% and dried. A method of coating the dispersion on a porous polymer substrate can use a conventional coating method known in the art, for example, dip coating, die coating, roll coating, comma. Various methods can be used, such as coating or a mixture of these methods.

In addition to the inorganic particles and binder polymer described above as components of the porous coating layer, other additives such as conductive agents may be further included.

The final manufactured separator according to the present invention may have a thickness of 1 to 100 μm or 5 to 50 μm. If the thickness is less than 1㎛, the function of the separator may not be fully exercised and mechanical properties may deteriorate, and if it is more than 100㎛, the characteristics of the battery may deteriorate during high rate charging and discharging. Additionally, it may have a porosity of 40 to 60% and an air permeability of 150 to 300 seconds/100 mL.

According to one embodiment of the present invention, the porous polymer substrate may be polyethylene or polypropylene. Additionally, Al oxide and Si oxide-based coating materials can be used as inorganic particles in the porous coating layer.

When using the separator according to one embodiment of the present invention, since porous coating layers are provided on both sides of the porous polymer substrate, a uniform solid electrolyte interface layer can be formed by improving the impregnation performance for the electrolyte solution, and it is possible to form a uniform solid electrolyte interface layer compared to the conventional cross-sectional inorganic material. Superior air permeability can be secured compared to coated separators. For example, it may be within 120s/100cc. In addition, even if an inorganic porous coating layer is provided on both sides, a thickness comparable to that of a conventional single-sided inorganic coating separator can be achieved. For example, it may be within ~15.0㎛.

In addition, when using a separator according to an embodiment of the present invention, the stability of the separator is improved and heat resistance and compression resistance characteristics can be secured. Specifically, it is possible to secure heat resistance with a heat shrinkage characteristic of less than 5% at 180℃, a puncture strength of 550gf or more, and core deformation during the cycle of a battery using this separator. ) When this occurs, damage or penetration of the separator can be prevented in the step area.

Electrode tabs are connected to the first electrode 31 and the second electrode 32, respectively. In the embodiment, the structure in which the electrode tab is connected to the first electrode 31 is omitted for convenience of explanation. The electrode tab 40 of the embodiment may be connected to the surface of the second electrode 32 as shown in FIGS. 7 and 8. The electrode tab 40 is connected to a portion of the positive electrode current collector where the positive electrode active material is not applied.

The electrode tab 40 may be disposed on the core side of the second electrode 32. One longitudinal end of the electrode tab 40 may protrude further outward in the axial direction than the laminate. Accordingly, the cutout portion 43 of the electrode tab 40 may also be disposed in a section where the electrode tab 40 protrudes from the laminate. The groove 41 of the electrode tab 40 is provided on a surface opposite to the surface where the electrode tab 40 and the second electrode 32 are in contact.

When the core side end of the laminate is connected to the core 6 and the laminate is wound around the core 6, the electrode assembly 10 is wound in a jelly-roll shape as shown in FIGS. 9 to 11. can be produced.

A core portion 12 is provided in the core portion of the electrode assembly 10, and the electrode tab 40 is disposed on the inner periphery of the electrode assembly 10 defining the core hollow portion 12.

The electrode tab 40 may be in a form that surrounds the electrode assembly 10 once. That is, the central angle corresponding to the circumferential section of the electrode assembly 10 occupied by the electrode tab 40 being wound may be 360 degrees. Then, the inner peripheral wall of the electrode assembly 10 of the electrode tab 40, that is, the inner peripheral wall of the core hollow portion 12 of the electrode assembly 10, is formed, so that the electrode tab 40 is thicker than the electrode 30. ) has the effect of supporting the inner peripheral surface of the electrode assembly 10. This reduces the phenomenon in which the electrode assembly 10 is deformed in the centripetal direction due to the thickness of the second electrode 32 becoming thicker and thinner in the process of charging/discharging the battery, thereby deforming the core hollow portion 12. It prevents me.

Meanwhile, as shown further inside the electrode tab 40, the separator 50 may be wound one or more times.

The groove 41 provided on the surface of the electrode tab 40 is disposed on the centripetal surface of the electrode tab 40 in the electrode assembly 10 and has a centrifugally depressed shape. At this time, in the process of winding the electrode tab 40, the width of the groove 41 formed in the electrode tab 40 may become narrower.

And at the portion where the groove 41 is formed, the rigidity of the electrode tab 40, which is originally thicker than the electrode 30, is lowered, so that the electrode tab 40 can maintain a wound shape close to a substantially circular shape. there is. This effect can be further exhibited as more of the grooves 41 are arranged in the width direction.

In the embodiment, when the electrode tab 40 is wound, the central angle of the width of the electrode tab 40 in the electrode assembly 10 is 360 degrees. However, the central angle occupied by the electrode tab 40 is not necessarily limited to this. For example, the central angle of the width of the electrode tab 40 may be 180 degrees or more and 360 degrees or less. This is one of the things that greatly differentiates the electrode tab 40 of the present invention from typical existing electrode tabs. According to the structure of the electrode tab 40 of the present invention in which the groove 41 is provided on the inner peripheral surface, the width of the electrode tab 40 can be sufficiently widened, and the electrode tab 40 does not affect the roundness of the electrode assembly 10. This can be minimized.

Next, the longitudinal section of the electrode tab 40 where the cutout portion 43 is provided is exposed to the axial end of the electrode assembly 10.

In an embodiment, in a state in which the electrode tab 40 is wound, a circumferential section between the width direction end of the electrode tab and the adjacent cut portion 43, and/or two adjacent cut portions in the width direction ( 43), the central angle C that the circumferential section occupies along the circumference of the electrode assembly is substantially 90 degrees.

The spacing between the incisions 43 may be set so that the central angle is 45 degrees or more. Preferably, the distance between the incisions 43 may be set so that the central angle is 60 degrees or more. The intervals between the plurality of cut portions 43 may substantially correspond to each other. For example, seven incisions 43 may be set at 45-degree intervals, five may be set at 60-degree intervals, or three may be set at 90-degree intervals. If the gap between the cut portions 43 is too narrow, the bending process becomes cumbersome because the number of bent portions to be bent is large. In addition, after the bent parts are bent, the number of layers of partially bent parts that overlap in the axial direction is large, so the axial thickness of the overlapped bent parts becomes too thick, which makes welding, which will be described later, difficult, and is accommodated inside the can 70. This may cause the volume of the electrode assembly 10 to be reduced.

The spacing between the incisions 43 may be set so that the central angle is 120 degrees or less. Preferably, the distance between the incisions 43 may be set so that the central angle is 90 degrees or less. If the central angle corresponding to the gap between the cut portions 43 exceeds 120 degrees, the bent portion 45 is not bent smoothly and the electrode tab 40 disposed inside the electrode assembly 10 during the bending process. There is a possibility of causing deformation of the area.

As in the embodiment, when the central angle occupied by the bent portion 45 is about 90 degrees, the number of bent portions to be bent is appropriate, and the stacked thickness of the bent portions substantially corresponds to the thickness of the insulator 90, which will be described later, so that the can ( It does not affect the volume of the electrode assembly 10 accommodated in 70), and the bent portion 45 can be easily bent without affecting the remaining portion of the electrode tab 40.

Three cut portions 43 are provided at the end of the electrode tab 40 provided in the electrode assembly 10, and thus four bent portions 45 can be formed.

The bent portions 45 may be bent one by one in the radial direction. According to the embodiment, the bent portion 45 may be sequentially bent along the circumferential direction and bent in the centripetal direction.

First, referring to FIGS. 12 to 14, among the portions of the electrode tab 40 exposed at the axial end of the electrode assembly 10, the bent portion 45 disposed most centripetally in the winding direction is first bent in the centripetal direction. A bent portion 45 can be formed. And as sequentially shown in FIGS. 15 to 23, the bent portion 45 can be formed by sequentially bending along the circumferential direction. However, the order of forming the bent portion 45 is not necessarily limited to this.

The axial length of the bent portion 45 before being bent may be smaller than the diameter of the core hollow portion 12 of the electrode assembly 10.

The axial length of the bent portion 45 before being bent may be 2/3 or more and 1 or less of the diameter of the core hollow portion 12 of the electrode assembly 10, and is preferably 3/4 or more and 5/6. It may be below. In the examples, a configuration of 4/5 is illustrated. If the length of the bent portion 45 is less than 2/3 of the diameter of the core hollow portion 12, it is difficult to secure a welding area between the bent portion 45 and the can 70, which will be described later. In addition, if the length of the bent portion 45 is longer than the diameter of the core hollow portion 12, in the process of bending the bent portion 45, another bent portion ( 45), making the bending process cumbersome.

Next, referring to FIGS. 15 to 17 , the first bent portion 45 that was bent first and the adjacent portion in the circumferential direction are bent to form the second bent portion 45. The second bent bent portion 45 may be superimposed on the first bent bent portion 45.

Next, referring to FIGS. 18 to 20, the area adjacent to the first bent second bent part 45 in the circumferential direction is bent to form the third bent part 45. The third bent portion 45 may be superimposed on the second bent portion 45.

Next, referring to FIGS. 21 to 23, the third bent portion 45 that was bent first and the adjacent portion in the circumferential direction are bent to form the fourth bent portion 45. The fourth bent portion 45 may be superimposed on the third bent portion 45.

10, 13, 16, 19 and 22, when viewed in the axial direction, each of the bent portions 45 covers at least a portion of the core hollow portion 12. The areas covered by each bent portion 45 partially overlap with each other.

When viewed in the axial direction of the electrode assembly 10, the longitudinal end of the bent portion of the electrode tab 40 is disposed within the cross section of the core hollow portion 12 of the electrode assembly 10.

The bent portions 45 that face each other across the center of the electrode assembly 10 overlap each other at least in some areas when viewed in the axial direction. That is, in the embodiment, portions of the first bent portion 45 and the third bent portion 45 overlap each other, and portions of the second bent portion 45 and the fourth bent portion 45 overlap each other.

The bent portions 45 adjacent to each other in the circumferential direction of the electrode assembly 10 overlap each other at least in some areas when viewed in the axial direction. That is, in the embodiment, parts of the first bent part 45 and the second bent part 45 overlap each other, parts of the second bent part 45 and the third bent part 45 overlap each other, and the third bent part ( 45) and the fourth bent portion 45 partially overlap each other.

The bent portion 45 of the present invention does not have to be bent in the bending order mentioned in the previous embodiment. However, if the electrode tab 40 is bent from a more centripetal side to form the bent portion 45, the process of forming the plurality of bent portions 45 by overlapping them can be performed more smoothly.

Referring to Figures 24 and 25, the electrode assembly 10 can be accommodated inside a cylindrical can 70 made of metal. According to an embodiment, the electrode assembly 10 is inserted into the can 70 with its bent portion 45 facing the bottom 73 of the can 70. At this time, an insulator 90 may be interposed between the electrode assembly 10 and the bottom 73 of the can 70. The electrode 30 of the electrode assembly 10 wound in a jelly-roll shape is electrically insulated from the bottom 73 of the can 70 by the insulator 90. In addition, since the separator 50 is wound around the outer peripheral surface of the electrode assembly 10, the side of the can 70, that is, the peripheral wall 71, and the electrode assembly 10 are also insulated.

The insulator 90 may be in the shape of a flat ring that covers the surface of the jelly-roll and exposes the bent portion 45 in the axial direction.

The thickness of the insulator 90 may substantially correspond to the thickness of the overlapping portion of the bent portion 45. Accordingly, since the bent portion 45 does not require a separate space inside the can 70, the volume of the electrode assembly 10 accommodated inside the can 70 can be maximized.

The bent portion 45 is in contact with the bottom 73 of the can 70 and may be welded to the bottom 73. For example, the welding may be performed by resistance welding. The resistance welding is performed using a long rod-shaped resistance welder through the open end of the can 70 and the core hollow portion 12 of the electrode assembly 10 while the electrode assembly 10 is accommodated in the can 70. may be inserted to press the bent portion 45 toward the bottom portion 73. However, the welding method does not have to be limited to this.

Alternatively, although not shown, an electrode terminal may be installed at the center of the bottom 73 of the can 70, and the bent portion 45 may be welded to the electrode terminal and electrically connected to the electrode terminal. Additionally, the electrode terminal may be insulated from the can 70.

Hereinafter, with reference to FIGS. 26 to 29, another embodiment of the electrode tab 40 according to the present invention will be described. In explaining this, the differences from the previously described embodiment will be mainly explained. In other words, contents not described here can be sufficiently confirmed from the contents of the previously described embodiments.

The electrode tab 40 is formed with a plurality of grooves 41 compared to the number of incisions 43. The cross-sectional shape of the groove 41 may be an isosceles triangle. According to this configuration of the electrode tab 40, when the electrode tab 40 is wound, the rigidity is lowered in more areas along the width direction of the electrode tab 40, so the profile of the wound electrode tab 40 is aligned with the true circle. It can be formed even closer.

Next, with reference to FIGS. 30 to 33, another embodiment of the electrode tab 40 according to the present invention will be described. The electrode tab 40 also has a plurality of grooves 41 formed in proportion to the number of incisions 43. In addition, the width of the groove 41 of the electrode tab 40 may be narrower than the width of the groove 41 of the electrode tab 40 previously shown in FIGS. 26 to 29. Accordingly, when the electrode tab 40 is wound, the width of the groove 41 can be further reduced.

In Figure 33, the groove 41 is shown to have a slight width even in a narrowed state. However, if the width of the groove 41 is set narrower, the width of the groove 41 can be almost eliminated or completely eliminated when the electrode tab 40 is wound. Then, in the process of winding the electrode tab 40, the rigidity of the electrode tab 40 is relaxed, but when the electrode tab 40 is wound, the rigidity of the electrode tab 40 can be further increased. Then, even if the thickness of the electrode 30 of the electrode assembly 10 changes due to charging/discharging of the battery cell, the peripheral wall 71 of the can 70 supports the outer circumference of the electrode assembly 10, and the electrode The tab 40 strongly supports the inner periphery of the electrode assembly 10, thereby further reducing deformation of the electrode assembly 10.

Meanwhile, if the grooves 41 are formed densely as shown in FIGS. 26 to 33, the protrusions provided between the grooves 41 may become sharper. Then, sharp protrusions come into contact with each other at the areas where the plurality of bent portions 45, which are distinguished from the cut portion 43 and are bent, come into contact with each other, so resistance welding can easily proceed even without forming separate protrusions for resistance welding. .

In the previous embodiments, a structure in which the bent portion 45 was bent in the centripetal direction was described. However, this bent portion 45 may be formed by bending in the centrifugal direction as shown in FIG. 34.

In the electrode assembly 10 having such a bent structure, the insulator 90 may be disposed between the axial end surface of the electrode assembly 10 and the bent portion 45.

This type of bent portion 45 can be welded to the bottom 73 of the can 70 in a state where the bent portion 45 is in contact with the bottom 73 of the can 70. For example, the welding may be laser welding performed by irradiating a laser to the outer surface of the bottom 73 of the can 70 from the outside of the bottom 73 of the can 70.

Meanwhile, Figure 35 shows a structure in which one of the two bent portions 45 disposed across the center of the electrode assembly 10 is bent in the centripetal direction, and the other is bent in the centrifugal direction.

In the electrode assembly 10 having this type of bent portion 45, an insulator 90 may be disposed between the bent portion 45 bent in the centrifugal direction and the axial end surface of the electrode assembly 10.

If the bending direction of the bent portion 45 is set as shown in Figure 34 or 35, even if the length of the bent portion 45 is larger than the diameter of the core hollow portion 12 of the electrode assembly 10, it does not interfere with bending. Rather, the length can be significantly increased, thereby further securing the contact area between the can 70 and the bent portion 45.

The above-described embodiments should be understood in all respects as illustrative and not restrictive, and the scope of the present invention will be indicated by the claims to be described later rather than the detailed description given above. In addition, the meaning and scope of the patent claims to be described later, as well as all changes and modifications derived from the equivalent concept, should be construed as being included in the scope of the present invention.

As described above, the present invention has been described with reference to the illustrative drawings, but the present invention is not limited to the embodiments and drawings disclosed herein, and various modifications may be made by those skilled in the art within the scope of the technical idea of the present invention. It is obvious that transformation can occur. In addition, although the operational effects according to the configuration of the present invention were not explicitly described and explained in the above description of the embodiments of the present invention, it is natural that the predictable effects due to the configuration should also be recognized.

2: press
2-1: Type 1 (higher type)
2-2: Type 2 (lower type)
4: Roll press (rolling roll)
4-1: 1st roll (upper roll)
4-2 2nd roll (lower roll)
6: winding core
10: Electrode assembly (jelly roll)
12: Winding core hollow part (core part)
30: electrode
31: First electrode (cathode)
32: Second electrode (anode)
40: Electrode tab
41: Home
43: incision
45: bend part
50: Separator
51: first separator
52: second separator
70: can
71: perimeter wall
73: Bottom part
90: insulator
C: central angle

Claims (19)

A jelly-roll type electrode assembly including a sheet-shaped electrode and an electrode tab that is electrically connected to the electrode and wound around a core together with the electrode,
The width direction of the electrode tab corresponds to the circumferential direction of the electrode assembly, and the longitudinal direction of the electrode tab corresponds to the axial direction of the electrode assembly,
At least one groove recessed in the centrifugal direction and extending in the longitudinal direction is provided on the centripetal surface of the electrode tab facing the core of the electrode assembly,
A cut portion extending in the longitudinal direction from the longitudinal end of the electrode tab is provided in at least some of the longitudinal sections of the electrode tab portion exposed to the axial end of the electrode assembly,
An electrode assembly, wherein at least a portion of a longitudinal section of the electrode tab where the cut portion is provided is bent in a radial direction of the electrode assembly to form a bent portion.
In claim 1,
The electrode tab is disposed on the core side of the electrode assembly.
In claim 1,
An electrode assembly wherein two or more grooves are provided, and the grooves are arranged along the width direction of the electrode tab.
In claim 3,
An electrode assembly in which the shape of the electrode tab portion corresponding to two adjacent grooves in the width direction is an equilateral trapezoid or an isosceles triangle.
In claim 1,
The groove includes a shape whose width gradually decreases in the depth direction.
In claim 1,
The electrode assembly wherein the cut portion is provided in the groove.
In claim 1,
An electrode assembly wherein the number of incisions is equal to or less than the number of grooves.
In claim 1,
The central angle occupied by the widthwise end of the electrode tab and the section between the adjacent cutouts in the electrode assembly, or the central angle occupied by the section between two adjacent cutouts in the electrode assembly is 45 degrees or more and 120 degrees or less, Electrode assembly.
In claim 1,
The central angle occupied by the widthwise end of the electrode tab and the section between the adjacent cutouts in the electrode assembly, or the central angle occupied by the section between two adjacent cutouts in the electrode assembly is 60 degrees or more and 90 degrees or less, Electrode assembly.
In claim 1,
The electrode assembly wherein the length of the portion where the electrode tab is bent in the radial direction is 2/3 or more and 1 or less of the diameter of the core hollow portion.
In claim 1,
The electrode assembly wherein the length of the portion where the electrode tab is bent in the radial direction is between 3/4 and 5/6 of the diameter of the hollow portion of the winding core.
In claim 1,
An electrode assembly wherein the central angle of the width of the electrode tab in the electrode assembly is 180 degrees or more and 360 degrees or less.
In claim 1,
The electrode assembly wherein the central angle of the width of the electrode tab in the electrode assembly is substantially 360 degrees.
In claim 1,
The bent portion is bent in the centripetal direction of the electrode assembly,
When viewed in the axial direction, the bent portion covers at least a portion of the core hollow portion.
In claim 14,
An electrode assembly wherein at least some areas of the bent portions facing each other across the center of the electrode assembly overlap each other when viewed in the axial direction.
In claim 14,
An electrode assembly wherein at least some areas of adjacent bent portions in the circumferential direction of the electrode assembly overlap with each other when viewed in the axial direction.
In claim 14,
An electrode assembly, wherein an end of the bent portion of the electrode tab is disposed within a cross section of the core hollow portion of the electrode assembly when viewed in the axial direction of the electrode assembly.
In claim 1,
One of the bent parts facing each other with the center of the electrode assembly in between is bent in the centripetal direction, and the other is bent in the centrifugal direction.
The electrode assembly of any one of claims 1 to 18; and
It includes a can accommodating the electrode assembly,
A cylindrical cell wherein the bent portion is welded to the can or to an electrode terminal installed on the can.