Cylindrical battery, battery pack including the same, and motor vehicle

Abstract

A cylindrical battery according to an embodiment of the present invention includes an electrode assembly in which a first electrode, a second electrode, and a separator interposed therebetween are wound. The first electrode and the second electrode include a first uncoated portion and a second uncoated portion, respectively. At least one of the first uncoated portion and the second uncoated portion is defined as an electrode tab, and includes a core-side uncoated portion, an outer periphery-side uncoated portion, and a middle uncoated portion interposed therebetween. At least one of the core-side uncoated portion and the outer periphery-side uncoated portion has a lower height in the winding axial direction than the middle uncoated portion. The cylindrical battery includes a battery housing that receives the electrode assembly from an opening and is electrically connected to the second uncoated portion, an external terminal that is electrically connected to the first uncoated portion and is exposed to the outside through a closing portion of the battery housing, and a cap plate that covers the opening of the battery housing.

Description

Technical Field

[0001] The present invention relates to a cylindrical battery, a battery pack including the same, and an automobile.

[0002] This application claims priority based on Korean Patent Application No. 10-2021-0142189 filed on October 22, 2021, and the content of the application on which the priority is based is incorporated herein by reference.

Background Art

[0003] Generally, when manufacturing a battery pack using cylindrical batteries, a plurality of cylindrical batteries are erected and arranged in a housing, and the upper and lower ends of the cylindrical batteries are used as a positive electrode terminal and a negative electrode terminal, respectively, to electrically connect the plurality of cylindrical batteries to each other.

[0004] In the electrical connection of a cylindrical battery, the non-coated part of the negative electrode of the electrode assembly housed inside the battery housing extends downward and is electrically connected to the bottom surface of the battery housing, and the non-coated part of the positive electrode extends upward and is electrically connected to the top cap. That is, in a cylindrical battery, it is common that the bottom surface of the battery housing is used as a negative electrode terminal and the top cap covering the upper end opening of the battery housing is used as a positive electrode terminal.

[0005] When the positive electrode terminal and the negative electrode terminal of the cylindrical battery are located on opposite sides, electrical connection components such as bus bars for electrically connecting a plurality of cylindrical batteries must be applied to both the upper and lower parts of the cylindrical battery. This complicates the electrical connection structure of the battery pack.

[0006] Furthermore, in such a structure, components for insulation and components for ensuring waterproofness and airtightness are applied to the upper and lower parts of the battery pack, respectively, resulting in an increase in the number of applied components and a complication of the structure.

[0007] Therefore, in order to simplify the electrical connection structure of a plurality of cylindrical batteries, there is a demand for the development of a cylindrical battery having a structure in which the positive and negative terminals are applied in the same direction.

[0008] On the other hand, secondary batteries with high applicability for each product group, capable of repeating charge and discharge, and having electrical characteristics such as high energy density are widely applied not only to portable devices but also to electric vehicles (EVs) or hybrid electric vehicles (HEVs) driven by an electric drive source. Hereinafter, the battery refers to a secondary battery.

[0009] Batteries are attracting attention as a new energy source for improving energy efficiency because they not only have the primary advantage of dramatically reducing the use of fossil fuels but also are environmentally friendly in that they do not generate any by-products from the use of energy.

[0010] Currently, batteries such as lithium-ion batteries, lithium polymer batteries, nickel cadmium batteries, nickel metal hydride batteries, and nickel zinc batteries are widely used, and the operating voltage of a single battery is about 2.5 V to 4.5 V. Therefore, when a higher output voltage is required, a plurality of batteries are connected in series to form a battery pack. Also, depending on the charge and discharge capacity required for the battery pack, a plurality of batteries may be connected in parallel to form a battery pack. Therefore, the number and electrical connection form of the batteries included in the battery pack can be variously set according to the required output voltage and / or charge and discharge capacity.

[0011] On one hand, as types of unit batteries, cylindrical, rectangular, and pouch-type batteries are known. In the case of a cylindrical battery, a separator, which is an insulator, is interposed between the positive electrode and the negative electrode, and this is wound up to form a jelly-roll type electrode assembly, which is inserted into the interior of a battery housing to constitute a battery. And strip-shaped electrode tabs are connected to the plain portions of the positive electrode and the negative electrode respectively, and the electrode tabs electrically connect between the electrode assembly and the electrode terminals exposed to the outside. For reference, the positive electrode terminal is the cap plate of the sealing body that seals the opening of the battery housing, and the negative electrode terminal is the battery housing.

[0012] However, according to the conventional cylindrical battery having such a structure, since the current is concentrated on the strip-shaped electrode tab coupled to the positive electrode plain portion and / or the negative electrode plain portion, there is a problem that the resistance is large, heat generation is much, and the current collection efficiency is not good.

[0013] In the case of a small cylindrical battery having a form factor of 1865 or 2170, the problems of large resistance and heat generation do not occur. However, when increasing the form factor for applying the cylindrical battery to an electric vehicle, there is a risk that the cylindrical battery catches fire while a large amount of heat is generated around the electrode tab during the rapid charging process.

[0014] In order to solve such problems, a cylindrical battery (so-called tab-less cylindrical battery) having a structure in which the positive electrode plain portion and the negative electrode plain portion are respectively located at the upper end and the lower end of the jelly-roll type electrode assembly, and a current collector plate is welded to such a plain portion to improve the current collection efficiency has been presented.

[0015] Figs. 1 to 3 are diagrams showing the manufacturing process of the tab-less cylindrical battery. Fig. 1 shows the structure of the electrode, Fig. 2 shows the winding process of the electrode, and Fig. 3 shows the process in which the current collector plate is welded to the folded surface of the plain portion.

[0016] Referring to FIGS. 1 to 3, the positive electrode 10 and the negative electrode 11 have a structure in which an active material layer 21 is coated on a sheet-shaped current collector 20, and include a plain portion 22 on one long side along the winding direction X.

[0017] The electrode assembly A is manufactured by sequentially laminating the positive electrode 10 and the negative electrode 11 together with two separator membranes 12 as shown in FIG. 2, and then winding them in one direction (X-axis direction). At this time, the plain portion of the positive electrode 10 and the plain portion of the negative electrode 11 are arranged in opposite directions.

[0018] After the winding process, the plain portion 10a of the positive electrode 10 and the plain portion 11a of the negative electrode 11 are bent toward the core side. Then, current collector plates 30 and 31 are welded and joined to the plain portions 10a and 11a, respectively.

[0019] No separate electrode tabs are joined to the positive electrode plain portion 10a and the negative electrode plain portion 11a, and the current collector plates 30 and 31 are connected to external electrode terminals. Since the current path is formed with a large cross-sectional area along the winding axis direction (refer to the arrow) of the electrode assembly A, there is an advantage that the resistance of the battery can be reduced. This is because the resistance is inversely proportional to the cross-sectional area of the path through which the current flows.

[0020] In a tabless cylindrical battery, in order to improve the welding characteristics between the plain portions 10a and 11a and the current collector plates 30 and 31, it is necessary to apply a strong pressure to the welding points of the plain portions 10a and 11a and bend the plain portions 10a and 11a as flat as possible.

[0021] However, when bending the welding points of the plain portions 10a and 11a, the patterns of the plain portions 10a and 11a may be deformed while being irregularly distorted. In this case, the deformed portion may come into contact with an electrode of the opposite polarity and cause an internal short circuit, or may induce fine cracks in the plain portions 10a and 11a. Also, while the plain portion 32 adjacent to the core of the electrode assembly A is being bent, all or a considerable part of the cavity 33 in the core of the electrode assembly A is blocked. In this case, problems occur in the electrolyte injection process. That is, the cavity 33 in the core of the electrode assembly A is used as a passage through which the electrolyte is injected. However, if the passage is blocked, it is difficult to inject the electrolyte. Also, in the process of inserting the electrolyte injector into the cavity 33, interference may occur with the plain portion 32 near the core, and there may be a problem that the plain portion 32 is torn.

[0022] Also, the bent portions of the plain portions 10a and 11a where the current collectors 30 and 31 are welded overlap multiple times, and there should be no empty space (gap). Thereby, sufficient welding strength can be obtained, and when using the latest technologies such as laser welding, it is possible to prevent the problem that the laser penetrates inside the electrode assembly A and melts the separator or the active material.

[0023] On the other hand, in the conventional tabless cylindrical battery, the positive electrode plain portion 10a is entirely formed on the upper part of the electrode assembly A. Therefore, when forming the beading portion by pushing the outer peripheral surface of the upper end of the battery housing inward, the peripheral edge region 34 of the upper end of the electrode assembly A is subjected to pressure by the battery housing. Such pressure partially deforms the electrode assembly A, and at this time, an internal short circuit may occur while the separator 12 is torn. If a short circuit occurs inside the battery, there is a risk of leading to heat generation or explosion of the battery.

[0024] On the other hand, when manufacturing an electrode by applying a conventional positive electrode active material containing secondary particles, particle cracking may occur, and gas generation may increase due to internal cracks generated during charge and discharge, which may cause problems in battery stability.

[0025] In an attempt to solve this problem, a positive electrode active material in the form of single particles or pseudo-single particles with a relatively large size of primary particles has been developed. However, when the positive electrode active material in the form of single particles or pseudo-single particles is applied to a high-loading electrode and rolled, the electrode cracks before the porosity of the electrode reaches the target level, and there is a problem that the resistance characteristics and charge-discharge efficiency of the lithium secondary battery are not good.

Summary of the Invention

Problems to be Solved by the Invention

[0026] The present invention has been made in view of the above-described problems, and an object thereof is to provide a cylindrical battery having a structure in which a positive electrode terminal and a negative electrode terminal are applied in the same direction.

[0027] Another object of the present invention is to secure a sufficient area for welding an electrical connection component such as a bus bar for manufacturing a battery pack and an electrode terminal of a cylindrical battery when attempting to electrically connect a plurality of cylindrical batteries in one direction.

[0028] Another object of the present invention is to provide an electrode assembly having an improved structure of a plain portion that can relieve the stress applied to the plain portion when the plain portion exposed at both ends of the electrode assembly is bent.

[0029] Another object of the present invention is to provide an electrode assembly in which an electrolyte injection passage is not blocked even when the plain portion is bent.

[0030] Another object of the present invention is to provide an electrode assembly including a structure capable of preventing the upper peripheral edge of the electrode assembly from coming into contact with the inner surface of the battery housing when the upper end of the battery housing is beaded.

[0031] Another object of the present invention is to provide an electrode assembly having an improved energy density and a reduced resistance.

[0032] Furthermore, another object of the present invention is to provide a cylindrical battery including an electrode assembly with an improved structure, a battery pack including the same, and an automobile including the battery pack.

[0033] Furthermore, another object of the present invention is to provide an electrode and an electrode assembly including the same, which can achieve excellent thermal stability by applying single particles or pseudo-single particles as a positive electrode active material, and have high electrical conductivity and high rolling characteristics.

[0034] Furthermore, another object of the present invention is to provide an electrode assembly with improved energy density by including a silicon-based negative electrode active material in the negative electrode.

[0035] Furthermore, another object of the present invention is to provide an electrode assembly in which the section of the positive electrode active material part is increased without concern about lithium precipitation.

[0036] Furthermore, another object of the present invention is to provide a cylindrical battery that can exhibit excellent thermal stability even when the volume of the battery increases due to an increase in the form factor.

[0037] The technical problems to be solved by the present invention are not limited to the above problems, and other problems will be clearly understood by those of ordinary skill in the art from the following description of the invention.

Means for Solving the Problems

[0038] To achieve the above problems, a cylindrical battery according to an aspect of the present invention includes an electrode assembly in which a first electrode, a second electrode, and a separator interposed therebetween are wound around a winding axis to define a core and an outer peripheral surface.

[0039] Each of the first electrode and the second electrode includes a first plain part and a second plain part on which an active material layer is not coated along the winding direction.

[0040] At least one of the first non-land portion and the second non-land portion is defined as an electrode tab by itself, and includes a core-side non-land portion, an outer-periphery-side non-land portion, and an intermediate non-land portion interposed therebetween.

[0041] At least one of the core-side non-land portion and the outer-periphery-side non-land portion has a height in the winding axis direction lower than that of the intermediate non-land portion.

[0042] The cylindrical battery includes a battery housing that houses the electrode assembly from an opening and is electrically connected to the second non-land portion, and an external terminal that is electrically connected to the first non-land portion and penetrates a closing portion of the battery housing located on the opposite side of the opening and is exposed to the outside of the battery housing, and a cap plate that covers the opening of the battery housing.

[0043] The cap plate is insulated from the battery housing and has no polarity by not being electrically connected to the electrode assembly.

[0044] The external terminal can be electrically connected to the first non-land portion having a first polarity.

[0045] The battery housing can be electrically connected to the second non-land portion having a second polarity different from the first polarity.

[0046] The external terminal can be located at the center of the closing portion of the battery housing.

[0047] The external terminal may include a terminal exposed portion extending to the outside of the battery housing and a terminal insertion portion penetrating the closing portion of the battery housing.

[0048] A cross-section of the terminal exposed portion is larger than a cross-section of the terminal insertion portion, and a periphery of a lower end portion of the terminal insertion portion facing the electrode assembly can be riveted toward an inner surface of the closing portion.

[0049] The cylindrical battery may further include an insulating gasket interposed between the battery housing and the external terminal to insulate the external terminal from the battery housing.

[0050] The insulating gasket may include a gasket exposed portion extending outside the battery housing and a gasket insertion portion penetrating a closed portion of the battery housing.

[0051] A part of the insulating gasket interposed between the peripheral edge of the lower end portion of the terminal insertion portion and the battery housing may be in close contact with the inner surface of the closed portion by the riveting.

[0052] The cylindrical battery may further include a beading portion formed by pushing in around the outer peripheral surface of the battery housing adjacent to the opening of the battery housing, a crimping portion formed by bending an end portion on the opening side of the battery housing in the winding axis direction so as to wrap the peripheral edge of the cap plate, and a sealing gasket that is crimped by the crimping portion while being interposed between the opening of the battery housing and the cap plate to seal between the cap plate and the opening of the battery housing.

[0053] At least a partial section of the intermediate plain portion may include a plurality of divided sections that can be independently bent.

[0054] At least one of the height in the winding axis direction and the width in the winding direction of the plurality of divided sections may increase stepwise from the core side to the outer peripheral side individually or for each group.

[0055] The plurality of divided sections form a plurality of divided section groups from the core side to the outer peripheral side, and at least one of the width in the winding direction, the height in the winding axis direction, and the separation pitch in the winding direction of the divided sections belonging to the same divided section group may be the same as each other.

[0056] Among the partial slices belonging to the same partial slice group, at least one of the width in the winding direction, the height in the winding axis direction, and the separation pitch in the winding direction may increase stepwise from the core side toward the outer peripheral side.

[0057] While being bent toward the core side, the plurality of partial slices may be stacked multiple times along the winding axis direction.

[0058] The radial length R of the non-patterned portion on the core side and the bending length H of the innermost partial slice of the intermediate non-patterned portion may satisfy the relational expression "H ≦ R".

[0059] A gap may be provided between the lower end of the cutting line of the partial slice and the active material layer.

[0060] The first non-patterned portion is itself defined as an electrode tab. The first non-patterned portion includes a core-side non-patterned portion adjacent to the core of the electrode assembly, an outer peripheral-side non-patterned portion adjacent to the outer peripheral surface of the electrode assembly, and an intermediate non-patterned portion interposed between the core-side non-patterned portion and the outer peripheral-side non-patterned portion. The intermediate non-patterned portion of the first non-patterned portion includes a plurality of independently bendable partial slices. The plurality of partial slices of the first non-patterned portion may be bent toward the core side to form a bent surface of the partial slice at one end portion of the electrode assembly.

[0061] The cylindrical battery may further include a first current collector plate coupled to the bent surface of the partial slice of the first non-patterned portion and an insulator interposed between the first current collector plate and the inner surface of the closed portion. In this case, the end portion of the external terminal facing the electrode assembly may pass through the insulator and be coupled to the first current collector plate.

[0062] The second non-patterned portion is itself defined as an electrode tab. The second non-patterned portion includes a core-side non-patterned portion adjacent to the core of the electrode assembly, an outer peripheral-side non-patterned portion adjacent to the outer peripheral surface of the electrode assembly, and an intermediate non-patterned portion interposed between the core-side non-patterned portion and the outer peripheral-side non-patterned portion. The intermediate non-patterned portion of the second non-patterned portion includes a plurality of independently bendable partial slices. The plurality of partial slices of the second non-patterned portion may be bent toward the core side while forming a bent surface of the partial slice at the other end portion of the electrode assembly.

[0063] The cylindrical battery may further include a second current collector plate coupled to the folded surface of the sliced portion of the second non-patterned portion. In this case, at least a part of the periphery of the second current collector plate may extend toward the inner surface of the beading portion and be interposed and fixed between the inner surface of the beading portion and the sealing gasket.

[0064] The cap plate may include a venting portion formed of a region thinner than an adjacent region. The venting portion may be a notching pattern. The venting portion may be a continuous or discontinuous linear pattern or a curved pattern.

[0065] When the cylindrical battery is erected with the cap plate facing the ground, the lower end portion of the cap plate may be located above the lower end portion of the battery housing.

[0066] The boundary region between the patterned portion and the non-patterned portion of the first electrode includes a first slide portion where the thickness of the active material layer decreases, and the boundary region between the patterned portion and the non-patterned portion of the second electrode includes a second slide portion where the thickness of the active material layer decreases, and the first slide portion and the second slide portion may be located in opposite directions in the winding axis direction.

[0067] The patterned portion of the first electrode includes a loading decrease portion where the loading amount of the active material decreases, and the position of the loading decrease portion may correspond to the position of the second slide portion.

[0068] The active material layer of the first electrode may include a positive electrode active material including single particles, pseudo single particles, or a combination thereof.

[0069] The minimum particle size D appearing in the volume cumulative distribution of the positive electrode active material min may be 1.0 μm or more.

[0070] The particle size D when the volume cumulative amount is 50% in the volume cumulative distribution of the positive electrode active material50 can be 5.0 μm or less.

[0071] The maximum particle size D appearing in the volume cumulative distribution of the positive electrode active material max can be 12 μm to 17 μm.

[0072] The positive electrode active material has a unimodal particle size distribution in which a single peak appears in the volume cumulative particle size distribution graph, and the particle size distribution (PSD: Particle Size Distribution) represented by the following formula 1 can be 3 or less. [Formula 1] Particle size distribution (PSD) = (D max - D min ) / D 50

[0073] The single particle, pseudo single particle, or a combination thereof may be contained in an amount of 95 wt% to 100 wt% based on the total weight of the positive electrode active material contained in the active material layer of the first electrode.

[0074] The positive electrode active material may contain a lithium nickel-based oxide containing 80 mol% or more of Ni based on the total number of moles of transition metals.

[0075] The active material layer of the first electrode may have a porosity of 15% to 23%.

[0076] The active material layer of the first electrode may contain flaky graphite in a weight ratio of 0.05 wt% to 5 wt%.

[0077] The active material layer of the first electrode may further contain carbon nanotubes (CNT).

[0078] The active material layer of the second electrode may contain a silicon-based negative electrode active material and a carbon-based negative electrode active material.

[0079] The silicon-based negative electrode active material and the carbon-based negative electrode active material may be contained in the active material layer of the second electrode at a weight ratio of 1:99 to 20:80.

[0080] A battery pack according to another aspect of the present invention includes a plurality of cylindrical batteries having at least one of the above-described features, and a pack housing that houses the same.

[0081] A motor vehicle according to still another aspect of the present invention includes the above-described battery pack.

Advantages of the Invention

[0082] According to one aspect of the present invention, since a cylindrical battery having a structure in which a positive electrode terminal and a negative electrode terminal are applied in the same direction is provided, the electrical connection structure of a plurality of cylindrical batteries can be simplified.

[0083] Further, according to one aspect of the present invention, since the electrode terminal of the cylindrical battery has a sufficient area to be welded to an electrical connection component such as a bus bar, the bonding strength between the electrode terminal and the electrical connection component can be sufficiently ensured, and the resistance at the bonding site between the electrical connection component and the electrode terminal can be reduced to a desired level.

[0084] Further, according to one aspect of the present invention, by using the plain portions protruding from the upper and lower portions of the electrode assembly itself as electrode tabs, the internal resistance of the battery can be reduced and the energy density can be increased.

[0085] Further, according to one aspect of the present invention, by improving the structure of the plain portion of the electrode assembly, the electrode assembly and the inner peripheral surface of the battery housing do not interfere with each other in the process of forming the beading portion of the battery housing, and an internal short circuit of the cylindrical battery due to partial deformation of the electrode assembly can be prevented.

[0086] Further, according to one aspect of the present invention, by improving the structure of the plain portion of the electrode assembly, it is possible to prevent the plain portion from being broken when the plain portion is bent, and to sufficiently increase the number of overlapping layers of the plain portion to improve the welding strength.

[0087] Further, according to one aspect of the present invention, by improving the structure of the plain portion adjacent to the core of the electrode assembly, it is possible to prevent the cavities in the core of the electrode assembly from being blocked when the plain portion is bent, and to easily perform the electrolyte injection step and the welding step between the battery housing and the current collector plate.

[0088] Also, according to one aspect of the present invention, it is possible to provide a cylindrical battery having a structure with low internal resistance, prevention of internal short circuit, and improved welding strength between the current collector plate and the plain portion, a battery pack including the same, and an automobile.

[0089] Also, according to one aspect of the present invention, D min By including a positive electrode active material powder having a particle size of 1.0 μm or more in the positive electrode, the thermal stability of the battery can be further improved. According to the research of the present inventors, even when single particles and / or pseudo-single particles are applied as the positive electrode active material, it has been confirmed that the effect of suppressing particle breakage after rolling and improving thermal stability varies depending on the particle size of the positive electrode active material powder. In particular, when particles having a particle size of less than 1.0 μm are included in the positive electrode active material powder, an increase in the linear pressure in the rolling process increases particle cracking and reduces thermal stability, and sufficient thermal stability could not be ensured when applied to a large cylindrical battery. Therefore, in the present invention, by using a positive electrode active material powder in which the minimum particle size D min is controlled to be 1.0 μm or more, the effect of improving thermal stability can be maximized.

[0090] Also, according to one aspect of the present invention, D 50 、D max And by including a positive electrode active material powder in which the particle size distribution (PSD) is appropriately adjusted in the positive electrode, it is possible to minimize the increase in resistance due to the application of single particles, and thus excellent capacity characteristics and output characteristics can be realized.

[0091] Also, according to one aspect of the present invention, the conductivity of the electrode can be improved by including a single-particle-based positive electrode active material coated with a conductive coating layer in the positive electrode or by including a novel CNT as a conductive material.

[0092] Also, according to one aspect of the present invention, since the flaky graphite is included in the positive electrode active material layer, when rolling the positive electrode active material layer, the flaky graphite provides a sliding effect to the positive electrode active material, improving the rolling characteristics of the electrode and reducing the electrode porosity to a target level. Thereby, the stability, initial resistance characteristics, and charge / discharge efficiency of the cylindrical battery are improved.

[0093] Also, according to one aspect of the present invention, by including a silicon-based negative electrode active material with a large capacity in the negative electrode, a higher energy density can be achieved.

[0094] Also, according to one aspect of the present invention, since the positive electrode includes a loading reduction portion with a small loading amount of the positive electrode active material, the section of the positive electrode active material portion can be increased without worry about lithium precipitation.

[0095] Also, according to one aspect of the present invention, compared with a conventional battery equipped with a strip-shaped electrode tab, the internal heat generation of the battery can be effectively reduced, so the thermal stability of the battery can be improved.

[0096] The present invention also has various effects, which will be described later with reference to embodiments. However, for effects that can be easily inferred by ordinary technicians, such explanations will be omitted.

[0097] The following drawings attached to this specification illustrate desirable embodiments of the present invention and are for the purpose of further understanding the technical idea of the present invention together with the detailed description of the invention. Therefore, the present invention should not be construed as being limited only to the matters described in the drawings.

Brief Description of the Drawings

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Embodiments for Carrying Out the Invention

[0099] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Prior to this, the terms and words used in this specification and the claims are not to be construed as being limited to ordinary and dictionary meanings. The inventor himself interprets them in accordance with the meaning and concept corresponding to the technical idea of the present invention in accordance with the principle that he can appropriately define the concept of the terms in order to explain the invention in the best way. Therefore, it should be understood that the embodiments described in this specification and the configurations shown in the drawings are only the most preferred embodiments of the present invention and do not represent all of the technical ideas of the present invention. Therefore, there may be various equivalents and modifications that can replace them at the time of this application.

[0100] Also, for the purpose of assisting in the understanding of the invention, the attached drawings are not illustrated to actual scale, and the dimensions of some components may be exaggerated. Also, the same reference numerals may be assigned to the same components in different embodiments.

[0101] The size and thickness of each illustrated component are arbitrarily shown for convenience of explanation, and the present invention is not necessarily limited by the illustration. In the drawings, the thickness is enlarged to clearly show many layers and regions. Also, in the drawings, for convenience of explanation, the thickness of some layers and regions is exaggerated.

[0102] Also, when a part such as a layer, film, region, or plate is said to be "on" or "above" another part, this includes not only the case where it is directly above the other part but also the case where there are other parts in between. Conversely, when a part is said to be "directly above" another part, it means that there are no other parts in between. Also, being "on" or "above" the reference part means being located above or below the reference part, and does not necessarily mean being located "on" or "above" in the opposite direction to gravity.

[0103] Throughout the specification, unless otherwise specified, when a part "includes" other components, it means that it can further include other components rather than excluding them.

[0104] Throughout the specification, when a "plan view" is referred to, it means the case of looking at the target part from above, and when a "cross-sectional view" is referred to, it means the case of looking at the cross-section obtained by vertically cutting the target part from the side.

[0105] Referring to FIGS. 4 to 6, a cylindrical battery 1 according to an embodiment of the present invention includes an electrode assembly A, a battery housing BH, a cap plate 40, and an external terminal 50.

[0106] In addition to the above-described components, the cylindrical battery 1 may further include an insulating gasket 35 and / or a first current collector plate 36 and / or an insulator 37 and / or a second current collector plate 38 and / or a sealing gasket 39.

[0107] The electrode assembly A includes a first electrode having a first polarity, a second electrode having a second polarity, and a separator interposed between the first electrode and the second electrode. The first electrode is a positive electrode or a negative electrode, and the second electrode corresponds to an electrode having a polarity opposite to that of the first electrode.

[0108] The electrode assembly A may have, for example, a jelly roll structure. That is, the electrode assembly A can be manufactured by winding a laminate formed by sequentially laminating the first electrode, the separator, and the second electrode at least once around a winding center C. In this case, a separator may be further provided on the outer peripheral surface of the electrode assembly A for insulation from the battery housing BH.

[0109] The first electrode includes a first current collector and a first electrode active material coated on one or both surfaces of the first current collector. At one end of the first current collector in the width direction (Z-axis direction), there is a non-coated part (first non-coated part) of the first electrode where the first electrode active material is not coated. The first non-coated part functions as the first electrode tab 13. The first electrode tab 13 is provided at the upper part in the height direction (Z-axis direction) of the electrode assembly A housed in the battery housing BH.

[0110] The second electrode includes a second current collector and a second electrode active material coated on one or both surfaces of the second current collector. At the other end of the second current collector in the width direction (Z-axis direction), there is a non-coated part (second non-coated part) of the second electrode where the second electrode active material is not coated. The second non-coated part functions as the second electrode tab 14. The second electrode tab 14 is provided at the lower part in the height direction (Z-axis direction) of the electrode assembly A housed in the battery housing BH.

[0111] The first electrode tab 13 and the second electrode tab 14 extend and protrude in opposite directions along the width direction of the electrode assembly A, that is, the height direction (Z-axis direction) of the cylindrical battery 1.

[0112] Referring to FIGS. 4 to 7, the battery housing BH is a substantially cylindrical container with an opening formed downward, and is made of a conductive material such as metal. The material of the battery housing BH can be, for example, aluminum. The side surface (outer peripheral surface) and the upper surface of the battery housing BH can be integrally formed. The upper surface (a plane parallel to the X-Y plane) of the battery housing BH has a substantially flat form. The upper part located on the opposite side of the opening is referred to as the closing part. The battery housing BH houses the electrode assembly A through the opening formed downward and also houses the electrolyte together.

[0113] The battery housing BH is electrically connected to the electrode assembly A. The battery housing BH is electrically connected to, for example, the second electrode tab 14 of the electrode assembly A. In this case, the battery housing BH has the same polarity as the second electrode tab 14.

[0114] Referring to FIGS. 5 and 10, the battery housing BH may include a beading portion 23 and a crimping portion 24 formed at its lower end. The beading portion 23 is located at the lower part of the electrode assembly A. The beading portion 23 is formed by pushing in around the outer peripheral surface of the battery housing BH. The beading portion 23 can function as a support portion on which the cap plate 40 is placed so that the electrode assembly A having a size substantially corresponding to the width of the battery housing BH does not come out from the opening formed at the lower end of the battery housing BH.

[0115] The crimping portion 24 is formed below the beading portion 23. The crimping portion 24 has a form that extends and is bent so as to wrap the outer peripheral surface of the cap plate 40 disposed below the beading portion 23 and a part of the lower surface of the cap plate 40.

[0116] However, the present invention does not exclude the case where the battery housing BH does not include such a beading portion 23 and / or crimping portion 24. In one embodiment of the present invention, when the battery housing BH does not include the beading portion 23 and / or crimping portion 24, the fixing of the electrode assembly A and / or the fixing of the cap plate 40 and / or the sealing of the battery housing BH can be realized, for example, through the additional application of components that can function as stoppers for the electrode assembly A and / or the additional application of structures on which the cap plate 40 can be placed and / or welding between the battery housing BH and the cap plate 40.

[0117] Referring to FIGS. 5 and 10, the cap plate 40 may be made of, for example, a metal material to ensure rigidity. The cap plate 40 covers an opening formed at the lower end of the battery housing BH. That is, the cap plate 40 constitutes the lower surface of the cylindrical battery 1. In the cylindrical battery 1 according to an embodiment of the present invention, the cap plate 40 has no polarity even when it is a metal material having conductivity. Having no polarity means that the cap plate 40 is electrically insulated from the battery housing BH and the external terminal 50. Therefore, the cap plate 40 does not function as a positive electrode terminal or a negative electrode terminal. Therefore, the cap plate 40 does not need to be electrically connected to the electrode assembly A and the battery housing BH, and its material does not necessarily have to be a conductive metal.

[0118] When the battery housing BH according to an embodiment of the present invention includes a beading portion 23, the cap plate 40 can be placed on the beading portion 23 formed on the battery housing BH. Also, when the battery housing BH according to an embodiment of the present invention includes a crimping portion 24, the cap plate 40 is fixed by the crimping portion 24. A sealing gasket 39 may be interposed between the cap plate 40 and the crimping portion 24 of the battery housing BH to ensure the airtightness of the battery housing BH. On the other hand, as described above, the battery housing BH according to an embodiment of the present invention does not necessarily include the beading portion 23 and / or the crimping portion 24. In this case, the sealing gasket 39 may be interposed between a fixed structure provided on the open portion side of the battery housing BH and the cap plate 40 to ensure the airtightness of the battery housing BH.

[0119] Referring to FIGS. 10 and 11, the cap plate 40 may further include a venting portion 41 formed to prevent the internal pressure from increasing beyond a preset value due to the gas generated inside the battery housing BH. The venting portion 41 corresponds to a region of the cap plate 40 that is thinner than the peripheral region. The venting portion 41 is structurally weaker than the peripheral region. Therefore, if an abnormality occurs in the cylindrical battery 1 and the internal pressure of the battery housing BH increases above a certain level, the venting portion 41 breaks and the gas generated inside the battery housing BH is discharged. The venting portion 41 can be formed, for example, by notching on one or both surfaces of the cap plate 40 to partially reduce the thickness of the cap plate 40.

[0120] The cylindrical battery 1 according to an embodiment of the present invention has a structure in which all the positive and negative terminals are present at the upper part as described later, so the upper structure is more complex than the lower structure. Therefore, a venting portion 41 may be formed on the cap plate 40 constituting the lower surface of the cylindrical battery 1 for smooth discharge of the gas generated inside the battery housing BH.

[0121] As shown in FIG. 10, it is desirable that the lower end portion of the cap plate 40 is located above the lower end portion of the battery housing BH. In this case, even if the lower end portion of the battery housing BH contacts the ground or the bottom surface of the housing for module or pack configuration, the cap plate 40 does not contact the ground or the bottom surface of the housing for module or pack configuration. Therefore, it is possible to prevent the phenomenon that the pressure required for breaking the venting portion 41 changes from the design value due to the weight of the cylindrical battery 1, thereby ensuring the smoothness of breaking of the venting portion 41.

[0122] On the one hand, when the bending portion 41 has a closed-loop form as shown in FIGS. 10 and 11, in terms of ease of breakage, it is more advantageous that the distance from the central portion of the cap plate 40 to the bending portion 41 is greater. This is because when the same bending pressure acts, the greater the distance from the central portion of the cap plate 40 to the bending portion 41, the greater the force acting on the bending portion 41 and the easier it is to break. Also, in terms of the smoothness of the discharge of the bending gas, it is more advantageous that the distance from the central portion of the cap plate 40 to the bending portion 41 is greater. From such a perspective, it is advantageous that the bending portion 41 is formed along the periphery of a substantially flat region protruding downward (downward with reference to FIG. 10) from the peripheral region of the cap plate 40.

[0123] FIG. 11 shows a case where the bending portion 41 is continuously formed while drawing a substantially circle on the cap plate 40, but the present invention is not limited thereby. The bending portion 41 may be discontinuously formed while drawing a substantially circle on the cap plate 40, or may be formed in a substantially linear form or other forms.

[0124] Referring to FIGS. 4 to 6, the external terminal 50 is made of a conductive metal material and passes through the upper surface of the battery housing BH, that is, the surface parallel to the X - Y plane located on the opposite side of the opening of the battery housing BH. The external terminal 50 is electrically connected to, for example, the first electrode tab 13 of the electrode assembly A. In this case, the external terminal 50 has a first polarity. Therefore, the external terminal 50 can function as the first electrode terminal E1 in the cylindrical battery 1 according to an embodiment of the present invention. When the external terminal 50 has such a first polarity, the external terminal 50 is electrically insulated from the battery housing BH having a second polarity. The electrical insulation between the external terminal 50 and the battery housing BH can be realized in various ways. For example, insulation can be achieved by interposing an insulating gasket 35 as described later between the external terminal 50 and the battery housing BH. Alternatively, insulation may be achieved by forming an insulating coating layer on a part of the external terminal 50. Or, a method of structurally and firmly fixing the external terminal 50 so that the external terminal 50 and the battery housing BH cannot come into contact may be applied. Or, a combination of a plurality of the above - described methods may be applied.

[0125] The external terminal 50 includes a terminal exposed portion 50a and a terminal insertion portion 50b. The terminal exposed portion 50a is exposed outside the battery housing BH. The terminal exposed portion 50a may be located at a substantially central portion of the upper surface of the battery housing BH. The maximum width of the terminal exposed portion 50a may be formed larger than the maximum width of the hole of the battery housing BH through which the external terminal 50 passes. The terminal insertion portion 50b may penetrate through a substantially central portion of the upper surface of the battery housing BH and be electrically connected to the first electrode tab 13. The peripheral region of the lower end portion of the terminal insertion portion 50b may be rivet - coupled to the inner surface of the battery housing BH. That is, the peripheral region of the lower end portion of the terminal insertion portion 50b may have a form bent toward the inner surface of the battery housing BH, whereby the maximum width of the lower end portion of the terminal insertion portion 50b may be formed larger than the maximum width of the hole of the battery housing BH through which the terminal insertion portion 50b passes.

[0126] On the one hand, when the cylindrical battery 1 according to an embodiment of the present invention includes the first current collector plate 36, the central region of the lower end of the terminal insertion portion 50b can be coupled to the first current collector plate 36. The central region of the lower end of the terminal insertion portion 50b can be, for example, substantially cylindrical. The diameter of the bottom surface of the central region of the lower end of the terminal insertion portion 50b can be set to about 6.2 mm.

[0127] The connection between the bottom surface of the central region of the lower end of the terminal insertion portion 50b and the first current collector plate 36 can be performed, for example, by laser welding or ultrasonic welding.

[0128] The laser welding can be performed by irradiating a laser through a hole formed at the winding center C of the electrode assembly A to form a laser welding line on one surface of the first current collector plate 36. The laser welding line can be formed in a form that draws substantially concentric circles on the opposite side surface that does not contact the bottom surface of the central region of the lower end of the terminal insertion portion 50b among the upper and lower surfaces of the first current collector plate 36. The welding line can be formed continuously or partially discontinuously.

[0129] The concentric welding line can have a diameter of about 60% to 80% of the diameter of the bottom surface of the central region of the lower end of the terminal insertion portion 50b. For example, when the diameter of the bottom surface of the central region of the lower end of the terminal insertion portion 50b is about 6.2 mm, it is desirable that the diameter of the circle drawn by the welding line is about 4.0 mm or more. If the diameter of the circle drawn by the welding line is too small, the bonding force by welding may become insufficient. On the other hand, if the diameter of the circle drawn by the welding line is too large, the electrode assembly A may be damaged by heat and / or welding spatter, etc.

[0130] The ultrasonic welding can be performed by inserting a welding rod for ultrasonic welding through a hole formed in the winding center C of the electrode assembly A. The welded portion formed by the ultrasonic welding is formed at the contact interface between the bottom surface of the central region of the lower end portion of the terminal insertion portion 50b and the first current collector plate 36. The welded portion formed by the ultrasonic welding can be entirely formed within a concentric circle having a diameter of about 30% to 80% with respect to the bottom surface of the central region of the lower end portion of the terminal insertion portion 50b. For example, when the diameter of the bottom surface of the central region of the lower end portion of the terminal insertion portion 50b is about 6.2 mm, the diameter of the circle drawn by the welded portion by ultrasonic welding can desirably be about 2.0 mm or more. If the diameter of the circle drawn by the welded portion by ultrasonic welding is too small, the bonding force by welding may be insufficient. On the other hand, if the diameter of the circle drawn by the welded portion by ultrasonic welding is too large, the electrode assembly A may be damaged by heat and / or vibration, etc.

[0131] In one embodiment of the present invention, the upper surface of the battery housing BH and the external terminal 50 exposed outside the battery housing BH face the same direction while having opposite polarities. Also, a step may be formed between the external terminal 50 and the upper surface of the battery housing BH. Specifically, when the entire upper surface of the battery housing BH has a flat shape or a shape protruding upward at its central portion, the terminal exposed portion 50a of the external terminal 50 may protrude further upward than the upper surface of the battery housing BH. Conversely, when the upper surface of the battery housing BH is concave at its central portion, that is, in the direction toward the electrode assembly A, the upper surface of the battery housing BH may protrude further upward than the terminal exposed portion 50a of the external terminal 50.

[0132] On the other hand, when the upper surface of the battery housing BH is concave at its central portion, that is, in the direction toward the electrode assembly A, the upper surface of the battery housing BH and the upper surface of the terminal exposed portion 50a can be in the same plane depending on the depth of the concavity and the thickness of the terminal exposed portion 50a of the external terminal 50. In this case, a step may not be formed between the upper surface of the battery housing BH and the terminal exposed portion 50a.

[0133] The insulating gasket 35 is interposed between the battery housing BH and the external terminal 50 to prevent the battery housing BH and the external terminal 50 having opposite polarities from coming into contact with each other. As a result, the upper surface of the battery housing BH having a substantially flat shape can function as the second electrode terminal E2 of the cylindrical battery 1.

[0134] The insulating gasket 35 includes a gasket exposed portion 35a and a gasket insertion portion 35b. The gasket exposed portion 35a is interposed between the terminal exposed portion 50a of the external terminal 50 and the battery housing BH. The gasket insertion portion 35b is interposed between the terminal insertion portion 50b of the external terminal 50 and the battery housing BH. The gasket insertion portion 35b can be deformed together during the reveting of the terminal insertion portion 50b and be in close contact with the inner surface of the battery housing BH. The insulating gasket 35 can be made of, for example, a resin material having insulating properties.

[0135] Referring to FIG. 7, the gasket exposed portion 35a of the insulating gasket 35 may have a form extending so as to cover the outer peripheral surface of the terminal exposed portion 50a of the external terminal 50. When the insulating gasket 35 covers the outer peripheral surface of the external terminal 50 in this way, it is possible to prevent a short circuit from occurring in the process of coupling an electrical connection component such as a bus bar to the upper surface of the battery housing BH and / or the external terminal 50. Although not shown, the gasket exposed portion 35a of the insulating gasket 35 may have a form extending so as to cover not only the outer peripheral surface of the terminal exposed portion 50a but also a part of the upper surface.

[0136] When the insulating gasket 35 is made of a resin material, the insulating gasket 35 can be joined to the battery housing BH and the external terminal 50 by heat fusion. In this case, the airtightness at the joining interface between the insulating gasket 35 and the external terminal 50 and at the joining interface between the insulating gasket 35 and the battery housing BH is enhanced. On the other hand, when the gasket exposed portion 35a of the insulating gasket 35 has a form extending to the upper surface of the terminal exposed portion 50a, the external terminal 50 may be joined to the insulating gasket 35 by insert injection.

[0137] According to an embodiment of the present invention, the insulating gasket 35, the insulator 37, and the sealing gasket 39 may be formed of the same material, but are not necessarily limited thereto. The thickness of the insulating gasket 35 and the thickness of the insulator 37 may be the same, but are not necessarily limited thereto. When these thicknesses are different, the insulator 37 may be thinner than the insulating gasket 35, and vice versa.

[0138] On the upper surface of the battery housing BH, the entire other region excluding the regions occupied by the external terminal 50 and the insulating gasket 35 corresponds to the second electrode terminal E2 having a polarity opposite to that of the external terminal 50. In contrast, in one embodiment of the present invention, when the insulating gasket 35 is omitted and the external terminal 50 is partially provided with an insulating coating layer, the entire other region excluding the region occupied by the external terminal 50 provided with the insulating coating layer from the upper surface of the battery housing BH can function as the second electrode terminal E2.

[0139] The cylindrical side wall of the battery housing BH can be formed in one piece with the second electrode terminal E2 so that there is no discontinuous portion between them. The connection from the side wall of the battery housing BH to the second electrode terminal E2 can be a smooth curve. However, the present invention is not limited thereto, and the connection portion may include at least one edge having a predetermined angle.

[0140] Referring to FIGS. 5 to 7, the first current collector plate 36 is coupled to the upper part of the electrode assembly A. The first current collector plate 36 is made of a conductive metal material and is connected to the first electrode tab 13. Although not shown, the first current collector plate 36 may have a plurality of irregularities formed radially on its lower surface. When the irregularities are formed, the first current collector plate 36 can be pressed to push the first electrode tab 13 into the irregularities.

[0141] Referring to FIG. 8, the first current collector plate 36 is coupled to the end of the first electrode tab 13. The coupling between the first electrode tab 13 and the first current collector plate 36 can be performed, for example, by laser welding. The laser welding can be performed in a manner of partially melting the base material of the first current collector plate 36, or may be performed with solder for welding interposed between the first current collector plate 36 and the first electrode tab 13. In this case, it is desirable that the solder has a melting point lower than that of the first current collector plate 36 and the first electrode tab 13.

[0142] Referring to FIG. 9, the first current collector plate 36 can be coupled to a bonding surface formed by bending the end of the first electrode tab 13 in a direction parallel to the first current collector plate 36 (see the partial enlarged structure). The bending direction of the first electrode tab 13 can be, for example, a direction toward the winding center C of the electrode assembly A. When the first electrode tab 13 has such a bent form, the space occupied by the first electrode tab 13 is reduced, and the energy density can be improved. In addition, an increase in the bonding area between the first electrode tab 13 and the first current collector plate 36 can achieve the effects of improving the bonding force and reducing the resistance.

[0143] Referring to FIGS. 5 to 7, the insulator 37 is provided between the upper end of the electrode assembly A and the inner surface of the battery housing BH or between the first current collector plate 36 coupled to the upper part of the electrode assembly A and the inner surface of the battery housing BH. The insulator 37 prevents contact between the first electrode tab 13 and the battery housing BH and / or between the first current collector plate 36 and the battery housing BH. Additionally, the insulator 37 can also be interposed between the upper end of the outer peripheral surface of the electrode assembly A and the inner surface of the battery housing BH. The first current collector plate 36 can be a plate extending completely across the upper end of the outer peripheral surface of the electrode assembly A. However, the present invention is not limited thereto, and the first current collector plate 36 may be formed to extend only partially across the upper end of the outer peripheral surface of the electrode assembly A.

[0144] When the cylindrical battery 1 according to an embodiment of the present invention includes the insulator 37, the terminal insertion portion 50b of the external terminal 50 passes through the insulator 37 and is coupled to the first current collector plate 36 or the first electrode tab 13.

[0145] The insulator 37 may include an opening adjacent to the winding center C. The terminal insertion portion 50b of the external terminal 50 can directly contact the first current collector plate 36 through the opening.

[0146] In one embodiment of the present invention, the terminal insertion portion 50b may have a circular planar shape, but is not limited thereto. The terminal insertion portion 50b can alternatively be polygonal, star-shaped, a shape having legs extending from the center, etc.

[0147] Referring to FIGS. 5 and 10, the second current collector plate 38 is coupled to the lower part of the electrode assembly A. The second current collector plate 38 is made of a conductive metal material and is connected to the second electrode tab 14. Also, the second current collector plate 38 is electrically connected to the battery housing BH. As shown in FIG. 10, the second current collector plate 38 can be interposed and fixed between the inner surface of the battery housing BH and the sealing gasket 39. Alternatively, the second current collector plate 38 may be welded to the inner wall surface of the battery housing BH.

[0148] Although not shown, the second current collector 38 may have a plurality of irregularities formed radially on one surface thereof. When the irregularities are formed, the second current collector 38 can be pressed to push the second electrode tab 14 into the irregularities.

[0149] Referring to FIG. 8, the second current collector 38 is coupled to the end of the second electrode tab 14. The coupling between the second electrode tab 14 and the second current collector 38 can be performed, for example, by laser welding. The laser welding can be performed in a manner of partially melting the base material of the second current collector 38, or may be performed with solder for welding interposed between the second current collector 38 and the second electrode tab 14. In this case, it is desirable that the solder has a melting point lower than that of the second current collector 38 and the second electrode tab 14.

[0150] Referring to FIG. 9, the second current collector 38 can be coupled to a bonding surface formed by bending the end of the second electrode tab 14 in a direction parallel to the second current collector 38 (see the partial enlarged structure). The bending direction of the second electrode tab 14 can be, for example, a direction toward the winding center C of the electrode assembly A. When the second electrode tab 14 has such a bent form, the space occupied by the second electrode tab 14 can be reduced to improve the energy density. Also, an increase in the bonding area between the second electrode tab 14 and the second current collector 38 can achieve the effects of improving the bonding force and reducing the resistance.

[0151] Referring to FIGS. 10 and 12, the second current collector 38 may include a plurality of sub-plates 38a extending radially from the central portion and spaced apart from each other. In this case, each of the plurality of sub-plates 38a is coupled to the second electrode tab 14 and the battery housing BH.

[0152] The outer end 38b of each sub-plate 38a is bent toward the inner surface of the beading portion 23, and the end can be fixed in a state of being interposed between the sealing gasket 39 and the inner surface of the beading portion 23. Also, the end of the outer end 38b can be welded to the inner surface of the beading portion 23, for example, the lower surface. The battery housing BH and the second electrode tab 14 can be electrically connected through welding. Since the sealing gasket 39 is interposed between the cap plate 40 and the welding region of the outer end 38b, the cap plate 40 has no electrical polarity.

[0153] When the second current collector plate 38 includes a plurality of sub-plates 38a separated from each other, the second current collector plate 38 partially covers the lower surface of the electrode assembly A. Therefore, a sufficient space is ensured for the gas generated in the electrode assembly A to move toward the cap plate 40, enabling smooth gas venting downward of the cylindrical battery 1. On the other hand, the structure of the second current collector plate 38 having a plurality of sub-plates 38a as described above can be similarly applied to the first current collector plate 36 described above.

[0154] Referring to FIGS. 6 and 10, the cylindrical battery 1 according to an embodiment of the present invention includes an external terminal 50 having a first polarity on one side in its longitudinal direction (Z-axis direction), and a second electrode terminal E2 that is electrically insulated from the external terminal 50 and has a second polarity. That is, in the cylindrical battery 1 according to an embodiment of the present invention, since a pair of electrode terminals (first electrode terminal E1, second electrode terminal E2) are located in the same direction, when a plurality of cylindrical batteries 1 are electrically connected, electrical connection components such as bus bars can be arranged only on one side of the cylindrical battery 1. This can lead to the simplification of the battery pack structure and the improvement of energy density.

[0155] Further, the cylindrical battery 1 has a structure that enables one surface of the battery housing BH having a substantially flat form to be used as the second electrode terminal E2, thereby ensuring a sufficient bonding area when bonding electrical connection components such as bus bars to the second electrode terminal E2. As a result, the cylindrical battery 1 can ensure sufficient bonding strength between the electrical connection component and the second electrode terminal E2, and can reduce the resistance at the bonding site to a desired level.

[0156] Referring to FIG. 4, bus bars B are connected to the first electrode terminal E1 and the second electrode terminal E2 of the cylindrical battery 1 according to an embodiment of the present invention, respectively. At each of the first electrode terminal E1 and the second electrode terminal E2, in order to ensure a sufficient area for the connection of the bus bar B, the width D1 of the upper surface of the region of the first electrode terminal E1 that is exposed outside the battery housing BH, that is, the terminal exposed portion 50a, can be set to about 10% to 60% of the width D2 of the upper surface of the second electrode terminal E2, that is, the battery housing BH.

[0157] Desirably, the cylindrical battery can be, for example, a cylindrical battery having a form factor ratio (a value obtained by dividing the diameter of the cylindrical battery by its height, that is, defined by the ratio of the height (H) to the diameter (Φ)) greater than about 0.4.

[0158] Here, the form factor means a value indicating the diameter and height of the cylindrical battery. The cylindrical battery according to an embodiment of the present invention can be, for example, a 46110 battery, a 4875 battery, a 48110 battery, a 4880 battery, or a 4680 battery. In the numerical value indicating the form factor, the first two digits indicate the diameter of the battery, and the remaining digits indicate the height of the battery.

[0159] The battery according to an embodiment of the present invention can be a substantially cylindrical battery having a diameter of about 46 mm, a height of about 110 mm, and a form factor ratio of about 0.418.

[0160] Batteries according to other embodiments can be cylindrical batteries that are substantially cylindrical, with a diameter of about 48 mm, a height of about 75 mm, and a form factor ratio of about 0.640.

[0161] Batteries according to yet other embodiments can be cylindrical batteries that are substantially cylindrical, with a diameter of about 48 mm, a height of about 110 mm, and a form factor ratio of about 0.436.

[0162] Batteries according to yet other embodiments can be cylindrical batteries that are substantially cylindrical, with a diameter of about 48 mm, a height of about 80 mm, and a form factor ratio of about 0.600.

[0163] Batteries according to yet other embodiments can be cylindrical batteries that are substantially cylindrical, with a diameter of about 46 mm, a height of about 80 mm, and a form factor ratio of about 0.575.

[0164] Conventionally, batteries with a form factor ratio of about 0.4 or less have been used. That is, conventionally, for example, 1865 batteries, 2170 batteries, etc. have been used. In the case of an 1865 battery, its diameter is about 18 mm, its height is about 65 mm, and its form factor ratio is about 0.277. In the case of a 2170 battery, its diameter is about 21 mm, its height is about 70 mm, and its form factor ratio is about 0.300.

[0165] Referring to FIG. 13a, a battery pack 3 according to an embodiment of the present invention includes a battery assembly in which a plurality of cylindrical batteries 1 according to an embodiment of the present invention as described above are electrically connected, and a pack housing 2 that houses the same. For the sake of illustration, components such as busbars, cooling units, and power terminals for electrical connection are not shown.

[0166] Referring to FIG. 13b, the vehicle 5 according to an embodiment of the present invention can be, for example, an electric vehicle, a hybrid vehicle or a plug-in hybrid vehicle, and includes a battery pack 3 according to an embodiment of the present invention. The vehicle 5 includes a four-wheel vehicle or a two-wheel vehicle. The vehicle 5 operates by receiving power supply from the battery pack 3 according to an embodiment of the present invention.

[0167] Hereinafter, various embodiments of the electrode plate, the electrode assembly and the cylindrical battery will be described with reference to FIGS. 11 to 35.

[0168] First, the electrode assembly according to an embodiment of the present invention will be described. The electrode assembly is a jelly roll type electrode assembly having a structure in which a sheet-like first electrode and a second electrode are wound in one direction with a separator interposed therebetween.

[0169] Preferably, at least one of the first electrode and the second electrode includes a plain portion where the active material is not coated at the long side end portion in the winding direction. At least a part of the plain portion is itself used as an electrode tab. The plain portion includes a core side plain portion adjacent to the core of the electrode assembly, an outer peripheral side plain portion adjacent to the outer peripheral surface of the electrode assembly, and an intermediate plain portion interposed between the core side plain portion and the outer peripheral side plain portion.

[0170] Preferably, the height of at least one of the core side plain portion and the outer peripheral side plain portion is relatively lower than that of the intermediate plain portion.

[0171] FIG. 14 is a plan view showing the structure of the electrode 60a according to the first embodiment of the present invention.

[0172] Referring to FIG. 14, the electrode 60a of the first embodiment includes a current collector 61 made of a metal foil and an active material layer 62. The metal foil can be aluminum or copper and is appropriately selected according to the polarity of the electrode 60a. The active material layer 62 is formed on at least one surface of the current collector 61 and includes a plain portion 63 at the long-side end in the winding direction X. The plain portion 63 is a region where the active material is not coated. An insulating coating layer 64 can be formed at the boundary between the active material layer 62 and the plain portion 63. The insulating coating layer 64 is formed so as to overlap at least partially with the boundary between the active material layer 62 and the plain portion 63. The insulating coating layer 64 contains a polymer resin and may contain an inorganic filler such as Al2O3.

[0173] The plain portion 63 includes a core-side plain portion B1 adjacent to the core side of the electrode assembly, an outer-periphery-side plain portion B3 adjacent to the outer periphery side of the electrode assembly, and an intermediate plain portion B2 interposed between the core-side plain portion B1 and the outer-periphery-side plain portion B3.

[0174] The core-side blank area B1, the outer-periphery-side blank area B3, and the intermediate blank area B2 can be defined as the blank areas in the regions adjacent to the core side, the blank areas in the regions adjacent to the outer-periphery side, and the blank areas in other regions excluding these, respectively, when the electrode 60a is wound as a jelly-roll type electrode assembly. The boundary between the core-side blank area B1 and the intermediate blank area B2 can be appropriately defined at a point where the height (or change pattern) of the blank area substantially changes from the core side to the outer-periphery side of the electrode assembly, or at a point of a predetermined percentage (for example, 5%, 10%, 15% of the radius, etc.) based on the radius of the electrode assembly. The boundary between the intermediate blank area B2 and the outer-periphery-side blank area B3 can be defined at a point where the height (or change pattern) of the blank area substantially changes from the outer-periphery side to the core side of the electrode assembly, or at a point of a predetermined percentage (for example, 85%, 90%, 95% of the radius, etc.) based on the radius of the electrode assembly. When the boundary between the core-side blank area B1 and the intermediate blank area B2 and the boundary between the intermediate blank area B2 and the outer-periphery-side blank area B3 are specified, the intermediate blank area B2 can be automatically specified. If only the boundary between the core-side blank area B1 and the intermediate blank area B2 is specified, the boundary between the intermediate blank area B2 and the outer-periphery-side blank area B3 can be appropriately selected at a point near the outer-periphery side of the electrode assembly. Conversely, if only the boundary between the intermediate blank area B2 and the outer-periphery-side blank area B3 is specified, the boundary between the core-side blank area B1 and the intermediate blank area B2 can be appropriately selected at a point near the core side of the electrode assembly. In the first embodiment, the height of the blank area 63 is not constant and there is a relative difference in the winding direction X. That is, the height (length in the Y-axis direction) of the outer-periphery-side blank area B3 is relatively lower than that of the core-side blank area B1 and the intermediate blank area B2.

[0175] FIG. 15 is a plan view showing the structure of the electrode 60b according to the second embodiment of the present invention.

[0176] Referring to FIG. 15, the electrode 60b of the second embodiment is different only in that the height of the outer-periphery-side blank area B3 gradually decreases toward the outer-periphery side as compared with the first embodiment, and other configurations are substantially the same.

[0177] In a modified form, the outer-periphery-side blank area B3 can be deformed into a stepped shape (refer to the dotted line) in which the height decreases stepwise.

[0178] FIG. 16 is a plan view showing the structure of the electrode 60c according to the third embodiment of the present invention.

[0179] Referring to FIG. 16, in the electrode 60c of the third embodiment, the heights of the core-side non-patterned portion B1 and the outer-periphery-side non-patterned portion B3 are relatively lower than that of the intermediate non-patterned portion B2. Also, the height of the core-side non-patterned portion B1 and the height of the outer-periphery-side non-patterned portion B3 may be the same or different.

[0180] Desirably, the height of the intermediate non-patterned portion B2 may be in a stepped shape that increases stepwise from the core side toward the outer-periphery side.

[0181] Patterns 1 to 7 divide the intermediate non-patterned portion B2 centering on the position where the height of the non-patterned portion 63 changes. Desirably, the number of patterns, the height (length in the Y-axis direction) and the width (length in the X-axis direction) of each pattern are adjustable so as to maximize the dispersion of stress during the bending process of the non-patterned portion 63. The dispersion of stress is for preventing the non-patterned portion 63 from being torn.

[0182] The width d of the core-side non-patterned portion B1 B1 is designed by applying the condition that it does not block the cavity of the core of the electrode assembly when the pattern of the intermediate non-patterned portion B2 is bent toward the core side.

[0183] In one example, the width d of the core-side non-patterned portion B1 B1 may increase in proportion to the bending length of Pattern 1. The bending length corresponds to the height of the pattern based on the bending point of the pattern.

[0184] In a specific example, when the electrode 60c is used to manufacture the electrode assembly of a cylindrical battery with a form factor of 4680, the width d of the core-side non-patterned portion B1 B1 may be set to 180 mm to 350 mm according to the diameter of the core of the electrode assembly.

[0185] In one example, the width of each pattern may be designed to constitute the same winding turn of the electrode assembly.

[0186] In other examples, the height of the intermediate land portion B2 may be in a stepped shape that increases from the core side toward the outer peripheral side and then decreases.

[0187] In still other examples, the outer peripheral land portion B3 may be deformed to have the same structure as that of the second embodiment.

[0188] In still other examples, the pattern structure applied to the intermediate land portion B2 may be extended to the outer peripheral land portion B3 (see the dotted line).

[0189] FIG. 17 is a plan view showing the structure of the electrode 60d according to the fourth embodiment of the present invention.

[0190] Referring to FIG. 17, in the electrode 60d of the fourth embodiment, the heights of the core-side land portion B1 and the outer peripheral land portion B3 are relatively lower than that of the intermediate land portion B2. Also, the height of the core-side land portion B1 and the height of the outer peripheral land portion B3 may be the same or different.

[0191] Desirably, at least a partial section of the intermediate land portion B2 may include a plurality of segmented pieces P. The plurality of segmented pieces P may have their heights increasing stepwise from the core side toward the outer peripheral side.

[0192] The segmented piece P may be formed by notching with a laser. The segmented piece P may be formed by a known metal foil cutting process such as ultrasonic cutting or punching.

[0193] In the fourth embodiment, when bending the non-patterned portion 63, in order to prevent the active material layer 62 and / or the insulating coating layer 64 from being damaged, it is desirable to provide a predetermined gap between the lower end of the cutting line between the divided segments P and the active material layer 62. This is because when the non-patterned portion 63 is bent, stress is concentrated near the lower end of the cutting line. The gap is preferably 0.2 mm to 4 mm. By adjusting the gap within the above numerical range, it is possible to prevent the active material layer 62 and / or the insulating coating layer 64 near the lower end of the cutting line from being damaged by the stress generated during the bending process of the non-patterned portion 63. Also, the gap can prevent damage to the active material layer 62 and / or the insulating coating layer 64 due to the tolerance during notching or cutting of the divided segment P. Desirably, when the electrode 60d is wound as an electrode assembly, at least a part of the insulating coating layer 64 can be exposed outside the separator membrane. In this case, when the divided segment P is bent, the insulating coating layer 64 can support the bending point.

[0194] The plurality of divided segments P can form a plurality of divided segment groups from the core side toward the outer peripheral side. The width, height, and separation pitch of the divided segments belonging to the same divided segment group can be substantially the same.

[0195] FIG. 18 is a diagram showing the definitions of the width, height, and separation pitch of the divided segment P according to an embodiment of the present invention.

[0196] Referring to FIG. 18, the width C1, height C2, and separation pitch C3 of the divided segment P are designed to prevent the non-patterned portion 63 from tearing and improve the welding strength during the bending process of the non-patterned portion 63, while sufficiently increasing the number of overlapping layers of the non-patterned portion 63 to prevent abnormal deformation of the non-patterned portion 63. Abnormal deformation means that the non-patterned portion below the bending point C4 cannot maintain a straight state and collapses and is deformed irregularly.

[0197] Preferably, the width C1 of the slit piece P can be adjusted in the range of 1 mm to 6 mm. When C1 is less than 1 mm, when the slit piece P is bent toward the core side, a region or an empty space (gap) that does not overlap enough to ensure sufficient welding strength is generated. On the other hand, when C1 exceeds 6 mm, when the slit piece P is bent, the plain portion 63 near the bending point C4 may be broken by stress. Further, the height of the slit piece P can be adjusted in the range of 2 mm to 10 mm. When C2 is less than 2 mm, when the slit piece P is bent toward the core side, a region or an empty space (gap) that does not overlap enough to ensure sufficient welding strength is generated. On the other hand, when C2 exceeds 10 mm, it is difficult to manufacture the electrode while maintaining the flatness of the plain portion in the winding direction X uniformly. That is, the plain portion becomes high and swell occurs. Further, the separation pitch C3 of the slit piece P can be adjusted in the range of 0.05 mm to 1 mm. When C3 is less than 0.05 mm, when the slit piece P is bent, the plain portion 63 near the bending point C4 may be broken by stress. On the other hand, when C3 exceeds 1 mm, when the slit piece P is bent, there is a possibility that the slit piece P does not overlap enough to ensure sufficient welding strength, or an empty space (gap) is generated.

[0198] Referring further to FIG. 17, the width d of the core-side plain portion B1 B1 is designed by applying the condition that the cavity of the core of the electrode assembly is not blocked when the slit piece P of the intermediate plain portion B2 is bent toward the core side.

[0199] In one example, the width d of the core-side plain portion B1 B1 can increase in proportion to the bending length of the slit piece P of Group 1. The bending length corresponds to the height of the slit piece P based on the bending point (C4 in FIG. 18).

[0200] In a specific example, when the electrode 60d is used to manufacture an electrode assembly of a cylindrical battery with a form factor 4680, the width d of the core-side plain portion B1 B1 can be set to 180 mm to 350 mm according to the diameter of the core of the electrode assembly.

[0201] In one example, the width of each segment group can be designed to form the same winding turn of the electrode assembly.

[0202] In other examples, the width and / or height and / or separation pitch of the segments P belonging to the same segment group can increase or decrease gradually and / or stepwise and / or irregularly within the group.

[0203] Groups 1 to 7 are only an example of segment groups. The number of groups and the number of segments P included in each group can be adjusted so that the segments P overlap multiple times to maximize the dispersion of stress during the bending process of the plain part 63 and ensure sufficient welding strength.

[0204] In still other examples, the height of the outer peripheral plain part B3 can decrease gradually or stepwise as in the first and second embodiments. Also, the segmenting structure of the intermediate plain part B2 can be extended to the outer peripheral plain part B3 (see the dotted line). In this case, the outer peripheral plain part B3 can also include a plurality of segments, similar to the intermediate plain part B2. In this case, the segments of the outer peripheral plain part B3 can have a larger width and / or height and / or separation pitch than the intermediate plain part B2.

[0205] In a specific example, when the electrode 60d is used to manufacture the electrode assembly of a cylindrical battery with a form factor of 4680, the segments can be formed in 8 groups. At this time, the segments of groups 1 to 7 can be formed in the intermediate plain part B2, and the segments of group 8 can be formed in the outer peripheral plain part B3 as in the above-described example.

[0206] In a specific example, the width d of the core-side plain part B1 B1can be 180 mm to 350 mm. The width of Group 1 can be 35% to 40% compared to the width of the non-patterned part B1 on the core side. The width of Group 2 can be 130% to 150% compared to the width of Group 1. The width of Group 3 can be 120% to 135% compared to the width of Group 2. The width of Group 4 can be 85% to 90% compared to the width of Group 3. The width of Group 5 can be 120% to 130% compared to the width of Group 4. The width of Group 6 can be 100% to 120% compared to the width of Group 5. The width of Group 7 can be 90% to 120% compared to the width of Group 6. The width of Group 8 can be 115% to 130% compared to the width of Group 7.

[0207] The reason why the widths of Group 1 to Group 8 do not show a constant increase or decrease pattern is that although the width of the segmented slices gradually increases from Group 1 to Group 8, the number of segmented slices included in each group is limited to an integer. Therefore, in a specific segmented slice group, the number of segmented slices can decrease. Therefore, the width of the group can show an irregular change pattern as exemplified above from the core side to the outer peripheral side.

[0208] That is, when the widths in the winding direction for each of three continuously adjacent segmented slice groups in the radial direction of the electrode assembly are W1, W2, and W3 respectively, it may include a combination of segmented slice groups where W3 / W2 is smaller than W2 / W1.

[0209] In the specific example described above, Groups 4 to 6 correspond to this. The width ratio of Group 5 to Group 4 is 120% to 130%, and the width ratio of Group 6 to Group 5 is 100% to 120%, and its value is smaller than 120% to 130%.

[0210] FIG. 19 is a plan view showing the structure of the electrode 60e according to the fifth embodiment of the present invention.

[0211] Referring to FIG. 19, the electrode 60e of the fifth embodiment is substantially the same as that of the fourth embodiment (or the modified form) in other configurations, except that the shape of the segmented piece P' is changed from a square to a trapezoid compared with the fourth embodiment.

[0212] FIG. 20 is a diagram showing the definitions of the width, height, and separation pitch of the trapezoidal segmented piece P'.

[0213] Referring to FIG. 20, the width D1, height D2, and separation pitch D3 of the segmented piece P' are designed to prevent the unpatterned portion 63 near the bending point D4 from being broken during the bending process of the unpatterned portion 63 and to ensure sufficient welding strength, while preventing abnormal deformation of the unpatterned portion 63 by sufficiently increasing the number of overlapping layers of the unpatterned portion 63.

[0214] Preferably, the width D1 of the segmented piece P' can be adjusted in the range of 1 mm to 6 mm. If D1 is less than 1 mm, when the segmented piece P' is bent toward the core side, there may be a region or space (gap) where the segmented piece P' does not overlap to a sufficient extent to ensure sufficient welding strength. On the other hand, if D1 exceeds 6 mm, when the segmented piece P' is bent, the unpatterned portion 63 near the bending point D4 may be broken by stress. Also, the height of the segmented piece P' can be adjusted in the range of 2 mm to 10 mm. If D2 is less than 2 mm, when the segmented piece P' is bent toward the core side, there may be a region or space (gap) where the segmented piece P' does not overlap to a sufficient extent to ensure sufficient welding strength. On the other hand, if D2 exceeds 10 mm, it is difficult to manufacture the electrode while maintaining the flatness of the unpatterned portion 63 in the winding direction uniformly. Further, the separation pitch D3 of the segmented piece P' can be adjusted in the range of 0.05 mm to 1 mm. If D3 is less than 0.05 mm, when the segmented piece P' is bent, the unpatterned portion 63 near the bending point D4 may be broken by stress. On the other hand, if D3 exceeds 1 mm, when the segmented piece P' is bent, there may be a region or space (gap) where the segmented piece P' does not overlap to a sufficient extent to ensure sufficient welding strength.

[0215] In the fifth embodiment, for the plurality of divided segments P', the lower inner angle θ of the trapezoid can increase from the core side toward the outer peripheral side. As the radius of the electrode assembly A increases, the curvature decreases. If the lower inner angle θ of the divided segment P' increases as the radius of the electrode assembly increases, the stress generated in the radial direction and the circumferential direction when the divided segment P' is bent can be relieved. Further, if the lower inner angle θ increases, the area and the number of overlapping layers that overlap with the inner divided segment P' when the divided segment P' is bent both increase, so that the welding strength can be ensured uniformly in the radial direction and the circumferential direction, and the bent surface can be formed flat.

[0216] In one example, when the electrode 60e is used to manufacture an electrode assembly of a cylindrical battery with a form factor 4680, when the radius of the electrode assembly A increases from 4 mm to 22 mm, the inner angle of the divided segment P' can increase stepwise in the range of 60° to 85°.

[0217] In another example, the height of the outer peripheral plain portion B3 can decrease gradually or stepwise, similar to the first and second embodiments. Further, the dividing structure of the intermediate plain portion B2 can be extended to the outer peripheral plain portion B3 (see the dotted line). In this case, the outer peripheral plain portion B3 can also include a plurality of divided segments similar to the intermediate plain portion B2. In this case, the divided segments of the outer peripheral plain portion B3 can have a larger width and / or height and / or separation pitch than the intermediate plain portion B2.

[0218] When the intermediate plain portion B2 includes a plurality of divided segments P, P' as in the fourth and fifth embodiments, the shape of each divided segment P, P' can be changed to a triangle, a semi - circle, a semi - ellipse, a parallelogram, etc.

[0219] Also, it is possible to change the shape of the divided segments P, P' for each region of the intermediate plain portion B2. In one example, a round shape (e.g., semi - circle, semi - ellipse, etc.) advantageous for stress dispersion can be applied to the section where stress is concentrated, and a polygonal shape with the largest possible area (e.g., square, trapezoid, parallelogram, etc.) can be applied to the section where stress is relatively low.

[0220] In the fourth and fifth embodiments, the slitting structure of the intermediate non-patterned portion B2 is also applicable to the core-side non-patterned portion B1. However, if the slitting structure is applied to the core-side non-patterned portion B1, depending on the radius of curvature of the core, there is a possibility that a reverse forming phenomenon may occur in which the end of the core-side non-patterned portion B1 bends toward the outer peripheral side when the slit pieces P and P' of the intermediate non-patterned portion B2 are bent. Therefore, it is desirable not to apply the slitting structure to the core-side non-patterned portion B1, or, even if the slitting structure is applied, to adjust the width and / or height and / or separation pitch of the slit pieces P and P' to a level at which reverse forming does not occur in consideration of the radius of curvature of the core.

[0221] The electrode structure of the above-described embodiment (deformed form) can be applied to at least one of the first electrode and the second electrode having different polarities included in the jelly roll type electrode assembly A. Further, when the electrode structure of the embodiment (deformed form) is applied to one of the first electrode and the second electrode, a conventional electrode structure can be applied to the other. Further, the electrode structures applied to the first electrode and the second electrode may not be the same and may be different.

[0222] As an example, when the first electrode and the second electrode are the positive electrode and the negative electrode, respectively, any one of the embodiments (deformed forms) may be applied to the first electrode, and a conventional electrode structure (see FIG. 1) may be applied to the second electrode.

[0223] As another example, when the first electrode and the second electrode are the positive electrode and the negative electrode, respectively, any one of the embodiments (deformed forms) may be selectively applied to the first electrode, and any one of the embodiments (deformed forms) may be selectively applied to the second electrode.

[0224] Hereinafter, the structure of the electrode assembly according to the embodiment of the present invention will be described in detail.

[0225] FIG. 21 is a cross-sectional view of a jelly roll type electrode assembly A1 in which the electrode 60a of the first embodiment is applied to the first electrode (positive electrode) and the second electrode (negative electrode), cut along the Y-axis direction (winding axis direction).

[0226] The electrode assembly A1 can be manufactured by the winding method described with reference to FIG. 2. For convenience of explanation, the protruding structures of the plain portions 43a and 43b extending outside the separation membrane are shown in detail, and the illustration of the winding structure of the first electrode, the second electrode, and the separation membrane is omitted. The plain portion 43a protruding upward extends from the first electrode, and the plain portion 43b protruding downward extends from the second electrode.

[0227] A pattern in which the heights of the plain portions 43a and 43b change is schematically shown. That is, the heights of the plain portions 43a and 43b can change irregularly depending on the cutting position of the cross section. As an example, if the sides of the trapezoidal segments P and P' are cut, the height of the plain portion in the cross section will be lower than the heights of the segments P and P'. Therefore, it should be understood that the heights of the plain portions 43a and 43b shown in the drawing showing the cross section of the electrode assembly correspond to the average of the heights of the plain portions included in each winding turn (C2 in FIG. 18, D2 in FIG. 20).

[0228] Referring to FIG. 21, the plain portion 43a of the first electrode includes a core-side plain portion B1 adjacent to the core of the electrode assembly A1, an outer-periphery-side plain portion B3 adjacent to the outer peripheral surface of the electrode assembly A1, and an intermediate plain portion B2 interposed between the core-side plain portion B1 and the outer-periphery-side plain portion B3.

[0229] The height (length in the Y-axis direction) of the outer-periphery-side plain portion B3 is relatively lower than the height of the intermediate plain portion B2. Therefore, it is possible to prevent the phenomenon that the outer-periphery-side plain portion B3 is pressed against the beading portion of the battery housing and an internal short circuit occurs.

[0230] The lower plain portion 43b has the same structure as the upper plain portion 43a. In a variant form, the lower plain portion 43b may have a conventional electrode structure or an electrode structure of other embodiments (variant forms).

[0231] The ends 81 of the upper plain portion 43a and the lower plain portion 43b can be bent from the outer peripheral side to the core side of the electrode assembly A1. At this time, the outer-periphery-side plain portion B3 may not be substantially bent.

[0232] FIG. 22 is a cross-sectional view of a jelly roll type electrode assembly A2 in which the electrode 60b of the second embodiment is applied to a first electrode (positive electrode) and a second electrode (negative electrode), taken along the Y-axis direction (winding axis direction).

[0233] Referring to FIG. 22, the blank portion 43a of the first electrode includes a core-side blank portion B1 adjacent to the core of the electrode assembly A2, an outer-periphery-side blank portion B3 adjacent to the outer peripheral surface of the electrode assembly A2, and an intermediate blank portion B2 interposed between the core-side blank portion B1 and the outer-periphery-side blank portion B3.

[0234] The height of the outer-periphery-side blank portion B3 is relatively lower than the height of the intermediate blank portion B2, and gradually or stepwise decreases from the core side toward the outer periphery side. Therefore, it is possible to prevent the phenomenon that the outer-periphery-side blank portion B3 is pressed against the beading portion of the battery housing and an internal short circuit occurs.

[0235] The lower blank portion 43b has the same structure as the upper blank portion 43a. In one modified form, the lower blank portion 43b may have a conventional electrode structure or an electrode structure of other embodiments (modified forms).

[0236] The end portions 91 of the upper blank portion 43a and the lower blank portion 43b can be bent from the outer periphery side to the core side of the electrode assembly A2. At this time, the outermost side 92 of the outer-periphery-side blank portion B3 may not be substantially bent.

[0237] FIG. 23 is a cross-sectional view of a jelly roll type electrode assembly A3 in which any one of the electrodes 60c, 60d, 60e of the third to fifth embodiments (these modified forms) is applied to a first electrode (positive electrode) and a second electrode (negative electrode), taken along the Y-axis direction (winding axis direction).

[0238] Referring to FIG. 23, the blank portion 43a of the first electrode includes a core-side blank portion B1 adjacent to the core of the electrode assembly A3, an outer-periphery-side blank portion B3 adjacent to the outer peripheral surface of the electrode assembly A3, and an intermediate blank portion B2 interposed between the core-side blank portion B1 and the outer-periphery-side blank portion B3.

[0239] The height of the core-side non-land portion B1 is relatively lower than the height of the intermediate non-land portion B2. Also, the bending length of the non-land portion 43a located innermost in the intermediate non-land portion B2 is the same as or shorter than the radial length R of the core-side non-land portion B1. The bending length H corresponds to the height of the non-land portion 43a based on the point where the non-land portion 43a is bent (C4 in FIG. 18, D4 in FIG. 20).

[0240] Therefore, even when the intermediate non-land portion B2 is bent, the bent portion does not block the cavity 102 of the core of the electrode assembly A3. If the cavity 102 is not blocked, there is no problem in the electrolyte injection process, and the efficiency of electrolyte injection is improved. Also, a welding jig can be inserted through the cavity 102 to easily perform the welding process between the current collector plate on the negative electrode side and the battery housing.

[0241] The height of the outer peripheral side non-land portion B3 is relatively lower than the height of the intermediate non-land portion B2. Therefore, it is possible to prevent the phenomenon that the outer peripheral side non-land portion B3 is pressed against the beading portion of the battery housing and an internal short circuit occurs.

[0242] In one modified form, unlike FIG. 23, the height of the outer peripheral side non-land portion B3 can gradually or stepwise decrease. Also, in FIG. 23, the height of the intermediate non-land portion B2 is equal in a part of the outer peripheral side, but the height of the intermediate non-land portion B2 can gradually or stepwise increase from the boundary between the core-side non-land portion B1 and the intermediate non-land portion B2 to the boundary between the intermediate non-land portion B2 and the outer peripheral side non-land portion B3.

[0243] The lower non-land portion 43b has the same structure as the upper non-land portion 43a. In one modified form, the lower non-land portion 43b may have a conventional electrode structure or an electrode structure of other embodiments (modified forms).

[0244] The end portions 101 of the upper non-land portion 43a and the lower non-land portion 43b can be bent from the outer peripheral side to the core side of the electrode assembly A3. At this time, the core-side non-land portion B1 and the outer peripheral side non-land portion B3 are not substantially bent.

[0245] When the non-coated portion B2 in the middle includes a plurality of segmented pieces, the bending stress is relaxed, so that it is possible to prevent the non-coated portion 43a near the bending point from being torn or abnormally deformed. Further, when the width and / or height and / or separation pitch of the segmented pieces are adjusted within the numerical range of the above-described embodiment, the segmented pieces are overlapped multiple times to such an extent that sufficient welding strength can be ensured while being bent toward the core side, and no space (gap) is formed in the bent surface (the surface viewed from the Y-axis direction).

[0246] FIG. 24 is a cross-sectional view of the electrode assembly A4 according to still another embodiment of the present invention, taken along the Y-axis direction (the winding axis direction).

[0247] Referring to FIG. 24, the electrode assembly A4 has substantially the same configuration as the electrode assembly A3 in FIG. 23, except that the height of the outer peripheral non-coated portion B3 is substantially the same as the outermost height of the middle non-coated portion B2.

[0248] The outer peripheral non-coated portion B3 may include a plurality of segmented pieces. The description of the configuration of the plurality of segmented pieces is substantially the same as that in the fourth and fifth embodiments (modified forms) and is incorporated herein by reference.

[0249] In the electrode assembly A4, the height of the non-coated portion B1 on the core side is relatively lower than the height of the middle non-coated portion B2. Further, the bending length H of the non-coated portion located innermost in the middle non-coated portion B2 is the same as or shorter than the radial length R of the non-coated portion B1 on the core side.

[0250] Therefore, even when the middle non-coated portion B2 is bent, the bent portion does not block the cavity 112 of the core of the electrode assembly A4. If the cavity 112 is not blocked, there is no problem in the electrolyte injection process, and the efficiency of electrolyte injection is improved. Further, a welding jig can be inserted through the cavity 112, and the welding process between the current collector plate on the negative electrode side and the battery housing can be easily performed.

[0251] In one deformation form, the structure in which the height of the intermediate non-patterned portion B2 gradually or stepwise increases from the core side toward the outer peripheral side can be extended to the outer peripheral non-patterned portion B3. In this case, the height of the non-patterned portion 43a can gradually or stepwise increase from the boundary between the core-side non-patterned portion B1 and the intermediate non-patterned portion B2 to the outermost surface of the electrode assembly A4.

[0252] The lower non-patterned portion 43b has the same structure as the upper non-patterned portion 43a. In one deformation form, the lower non-patterned portion 43b may have a conventional electrode structure or an electrode structure of other embodiments (deformation forms).

[0253] The end portions 111 of the upper non-patterned portion 43a and the lower non-patterned portion 43b can be bent from the outer peripheral side to the core side of the electrode assembly A4. At this time, the core-side non-patterned portion B1 is not substantially bent.

[0254] When the intermediate non-patterned portion B2 and the outer peripheral non-patterned portion B3 include a plurality of divided sections, since the bending stress is relaxed, it is possible to prevent the non-patterned portions 43a and 43b near the bending point from being broken or abnormally deformed. Further, when the width and / or height and / or separation pitch of the divided sections are adjusted within the numerical range of the above-described embodiments, the divided sections are overlapped multiple times to a sufficient extent to ensure the welding strength while being bent toward the core side, and no space (gap) is formed in the bent surface (the surface viewed from the Y-axis direction).

[0255] FIG. 25 is a cross-sectional view of an electrode assembly A5 according to still another embodiment of the present invention, taken along the Y-axis direction (winding axis direction).

[0256] Referring to FIG. 25, the electrode assembly A5 is different only in that it has a pattern in which the height of the intermediate non-patterned portion B2 gradually or stepwise increases and then decreases, as compared with the electrode assembly A3 of FIG. 23, and other configurations are substantially the same.

[0257] Such a change in the height of the intermediate non-patterned portion B2 can be realized by adjusting the height of the stepped pattern (see FIG. 16) or the divided sections (see FIG. 17 or FIG. 19) included in the intermediate non-patterned portion B2.

[0258] In the electrode assembly A5, the height of the core-side plain portion B1 is relatively lower than the height of the intermediate plain portion B2. Also, the bending length H of the plain portion located innermost in the intermediate plain portion B2 is the same as or shorter than the radial length R of the core-side plain portion B1.

[0259] Therefore, even if the intermediate plain portion B2 is bent toward the core side, the bent portion does not block the cavity 122 of the core of the electrode assembly A5. If the cavity 122 is not blocked, there is no problem in the electrolyte injection process, and the efficiency of electrolyte injection is improved. Also, a welding jig can be inserted through the cavity 122, and the welding process between the current collector plate on the negative electrode side and the battery housing can be easily performed.

[0260] Also, the height of the outer peripheral side plain portion B3 is relatively lower than the height of the intermediate plain portion B2. Therefore, it is possible to prevent the phenomenon that the outer peripheral side plain portion B3 is pressed against the beading portion of the battery housing and an internal short circuit occurs. In one modified form, the height of the outer peripheral side plain portion B3 may gradually or stepwise decrease toward the outer peripheral side.

[0261] The lower plain portion 43b has the same structure as the upper plain portion 43a. In a modified form, the lower plain portion 43b may have a conventional electrode structure or an electrode structure of other embodiments (modified forms).

[0262] The end portions 121 of the upper plain portion 43a and the lower plain portion 43b can be bent from the outer peripheral side to the core side of the electrode assembly A5. At this time, the core-side plain portion B1 and the outer peripheral side plain portion B3 are not substantially bent.

[0263] When the intermediate plain portion B2 includes a plurality of segmented pieces, since the bending stress is relaxed, it is possible to prevent the plain portions 43a and 43b from being torn or abnormally deformed. Also, when the width and / or height and / or separation pitch of the segmented pieces are adjusted within the numerical range of the above-described embodiments, the segmented pieces are overlapped multiple times to ensure sufficient welding strength while being bent toward the core side, and no space (gap) is formed in the bent surface (the surface viewed from the Y-axis direction).

[0264] FIG. 26 is a cross-sectional view of the electrode assembly A6 according to still another embodiment of the present invention, taken along the Y-axis direction (winding axis direction).

[0265] Referring to FIG. 26, the electrode assembly A6 is different in that, compared with the electrode assembly A5 of FIG. 25, the height of the outer peripheral plain portion B3 has a pattern that gradually or stepwise decreases from the boundary point between the outer peripheral plain portion B3 and the intermediate plain portion B2 toward the outermost surface of the electrode assembly A6, and other configurations are substantially the same.

[0266] Such a change in the height of the outer peripheral plain portion B3 can be realized by extending the stepped pattern (see FIG. 16) included in the intermediate plain portion B2 to the outer peripheral plain portion B3 and gradually or stepwise decreasing the height of the pattern toward the outer peripheral side. Also, in other modified forms, the change in the height of the outer peripheral plain portion B3 can be realized by extending the segmented structure of the intermediate plain portion B2 to the outer peripheral plain portion B3 and gradually or stepwise decreasing the height of the segments toward the outer peripheral side.

[0267] In the electrode assembly A6, the height of the core-side plain portion B1 is relatively lower than the height of the intermediate plain portion B2. Also, the bending length H of the plain portion located innermost in the intermediate plain portion B2 is the same as or shorter than the radial length R of the core-side plain portion B1.

[0268] Therefore, even if the intermediate plain portion B2 is bent toward the core side, the bent portion does not block the cavity 132 of the core of the electrode assembly A5. If the cavity 132 is not blocked, there is no problem in the electrolyte injection process, and the efficiency of electrolyte injection is improved. Also, a welding jig can be inserted through the cavity 132 to easily perform the welding process between the current collector plate on the negative electrode side and the battery housing.

[0269] The lower plain portion 43b has the same structure as the upper plain portion 43a. In one modified form, the lower plain portion 43b may have a conventional electrode structure or an electrode structure of other embodiments (modified forms).

[0270] The ends 131 of the upper non-land portion 43a and the lower non-land portion 43b can be bent from the outer peripheral side of the electrode assembly A6 toward the core side. At this time, the non-land portion B1 on the core side is not substantially bent.

[0271] When the intermediate non-land portion B2 and the outer peripheral side non-land portion B3 include a plurality of divided sections, the bending stress is relaxed, so that it is possible to prevent the non-land portions 43a and 43b near the bending point from being torn or abnormally deformed. Further, when the width and / or height and / or separation pitch of the divided sections are adjusted within the numerical range of the above-described embodiment, the divided sections are overlapped multiple times to such an extent that sufficient welding strength can be ensured while being bent toward the core side, and a space (gap) is not formed in the bent surface (the surface viewed from the Y-axis direction).

[0272] The structure of the various electrode assemblies according to the embodiment of the present invention is applicable to a jelly roll type cylindrical battery.

[0273] Desirably, the cylindrical battery can be a cylindrical battery having a form factor ratio (a value obtained by dividing the diameter of the cylindrical battery by the height, that is, a ratio of the height (H) to the diameter (Φ)) greater than about 0.4.

[0274] The cylindrical battery according to an embodiment of the present invention can be, for example, a 46110 battery, a 4875 battery, a 48110 battery, a 4880 battery, or a 4680 battery.

[0275] When an electrode assembly having a tabless structure is applied to a cylindrical battery having a form factor ratio exceeding 0.4, the stress applied in the radial direction during bending of the non-land portion is large, and the non-land portion is easily torn. Further, when welding a current collector plate to the bent surface of the non-land portion, in order to ensure sufficient welding strength and reduce resistance, the number of overlapping layers of the non-land portion must be sufficiently increased. Such requirements can be achieved by the electrodes and electrode assemblies according to the embodiment (modified form) of the present invention.

[0276] Hereinafter, the cylindrical battery according to the embodiment of the present invention will be described in detail.

[0277] FIG. 27 is a cross-sectional view of a cylindrical battery 140 according to an embodiment of the present invention, cut along the Y-axis direction.

[0278] Referring to FIG. 27, a cylindrical battery 140 according to an embodiment of the present invention includes an electrode assembly 141 including a first electrode, a separator, and a second electrode, a battery housing 142 for housing the electrode assembly 141, and a sealing body 143 for sealing an opening of the battery housing 142.

[0279] The battery housing 142 is a cylindrical container having an opening formed upward. The battery housing 142 is made of a conductive metal material such as aluminum or steel. The battery housing 142 houses the electrode assembly 141 in the inner space through the upper end opening, and also houses the electrolyte together.

[0280] The electrode assembly 141 may have a jelly roll structure. The electrode assembly 141 can be manufactured by winding a laminate formed by sequentially laminating at least once a lower separator, a first electrode, an upper separator, and a second electrode as shown in FIG. 2 around a winding center C.

[0281] The first electrode and the second electrode have different polarities. That is, if one has a positive polarity, the other has a negative polarity. At least one of the first electrode and the second electrode may have an electrode structure according to the above-described embodiment (deformed form). Also, the other of the first electrode and the second electrode may have a conventional electrode structure or an electrode structure according to an embodiment (deformed form).

[0282] From the upper and lower parts of the electrode assembly 141, the non-patterned part 146a of the first electrode and the non-patterned part 146b of the second electrode protrude respectively. The first electrode has the electrode structure of the first embodiment (deformed form). Therefore, the height of the outer peripheral non-patterned part B3 of the first electrode is lower than the height of the non-patterned parts of other parts. The outer peripheral non-patterned part B3 is separated from the inner peripheral surface of the battery housing 142, particularly the beading part 147, by a predetermined distance. Therefore, since the outer peripheral non-patterned part B3 of the first electrode does not contact the battery housing 142 electrically connected to the second electrode, an internal short circuit of the battery 140 is prevented.

[0283] The non-patterned parts 146b of the second electrode have the same height. In a deformed form, the non-patterned part 146b of the second electrode may have the same structure as the non-patterned part 146a of the first electrode. In other deformed forms, the non-patterned part 146b of the second electrode may selectively have the structure of the non-patterned part of the electrode according to the embodiment (deformed form).

[0284] The sealing body 143 may include a cap plate 143a, a first gasket 143b that provides airtightness between the cap plate 143a and the battery housing 142 and has insulation properties, and a connection plate 143c electrically and mechanically coupled to the cap plate 143a.

[0285] The cap plate 143a is a component made of a conductive metal material and covers the upper end opening of the battery housing 142. The cap plate 143a is electrically connected to the non-patterned part 146a of the first electrode and is electrically insulated from the battery housing 142 through the first gasket 143b. Therefore, the cap plate 143a can function as the first electrode terminal of the cylindrical battery 140.

[0286] The cap plate 143a is placed on the beading portion 147 formed on the battery housing 142 and fixed by the crimping portion 148. A first gasket 143b may be interposed between the cap plate 143a and the crimping portion 148 to ensure the airtightness of the battery housing 142 and the electrical insulation between the battery housing 142 and the cap plate 143a. The cap plate 143a may include a protruding portion 143d formed to protrude upward from the central portion thereof.

[0287] The battery housing 142 is electrically connected to the plain portion 146b of the second electrode. Therefore, the battery housing 142 has the same polarity as the second electrode. If the second electrode has a negative polarity, the battery housing 142 also has a negative polarity.

[0288] The battery housing 142 includes a beading portion 147 and a crimping portion 148 at the upper end. The beading portion 147 is formed by pushing in around the outer peripheral surface of the battery housing 142. The beading portion 147 can function as a support portion on which the sealing body 143 is placed so that the electrode assembly 141 housed inside the battery housing 142 does not come out from the upper end opening of the battery housing 142.

[0289] The inner peripheral surface of the beading portion 147 is separated from the outer peripheral plain portion B3 of the first electrode by a predetermined distance. More specifically, the lower end of the inner peripheral surface of the beading portion 147 is separated from the outer peripheral plain portion B3 of the first electrode by a predetermined distance. Further, since the outer peripheral plain portion B3 has a low height, the outer peripheral plain portion B3 is not substantially affected even when the battery housing 142 is pushed in from the outside to form the beading portion 147. Therefore, the outer peripheral plain portion B3 is not pressed by other components such as the beading portion 147, thereby preventing the occurrence of partial deformation of the electrode assembly 141 and preventing an internal short circuit of the cylindrical battery 140.

[0290] Desirably, if the pushing depth of the beading portion 147 is D1 and the radial length from the inner peripheral surface of the battery housing 142 to the boundary point between the outer peripheral plain portion B3 and the intermediate plain portion B2 is D2, the relational expression "D1 ≦ D2" can be satisfied. In this case, when the battery housing 142 is pushed in to form the beading portion 147, damage to the outer peripheral plain portion B3 is substantially prevented.

[0291] The crimping portion 148 is formed on the upper part of the beading portion 147. The crimping portion 148 has a form that extends and is bent so as to wrap the outer peripheral surface of the cap plate 143a disposed on the beading portion 147 and a part of the upper surface of the cap plate 143a.

[0292] The cylindrical battery 140 may further include a first current collector 144 and / or a second current collector 145 and / or an insulator 146.

[0293] The first current collector 144 is coupled to the upper part of the electrode assembly 141. The first current collector 144 is made of a metallic material having conductivity such as aluminum, copper, nickel, etc., and is electrically connected to the plain portion 146a of the first electrode. A lead 149 may be connected to the first current collector 144. The lead 149 may extend above the electrode assembly 141 and be coupled to the connection plate 143c, or may be directly coupled to the lower surface of the cap plate 143a. The connection between the lead 149 and other components may be made through welding.

[0294] Desirably, the first current collector 144 may be integrally formed with the lead 149. In this case, the lead 149 may be in the form of a long plate extending outward from the central portion of the first current collector 144.

[0295] The first current collector 144 may be provided with a plurality of concavo-convex portions (not shown) formed radially on its lower surface. When the radially concavo-convex portions are provided, the first current collector 144 can be pressed to push the plain portion 146a of the first electrode into the concavo-convex portions.

[0296] The first current collector plate 144 is coupled to the end of the non-patterned portion 146a of the first electrode. The coupling between the non-patterned portion 146a and the first current collector plate 144 can be performed, for example, by laser welding. Laser welding can be performed in a manner that partially melts the base material of the current collector plate. In a modified form, the welding between the first current collector plate 144 and the non-patterned portion 146a can be performed with solder interposed therebetween. In this case, the solder can have a melting point lower than that of the first current collector plate 144 and the non-patterned portion 146a. Laser welding can be replaced with resistance welding, ultrasonic welding, etc.

[0297] A second current collector plate 145 can be coupled to the lower surface of the electrode assembly 141. One surface of the second current collector plate 145 can be coupled to the non-patterned portion 146b of the second electrode by welding, and the other surface can be coupled to the inner bottom surface of the battery housing 142 by welding. The coupling structure between the second current collector plate 145 and the non-patterned portion 146b of the second electrode can be substantially the same as the coupling structure between the first current collector plate 144 and the non-patterned portion 146a of the first electrode.

[0298] The non-patterned portions (the first non-patterned portion 146a, the second non-patterned portion 146b) are not limited to the illustrated structure. Therefore, the non-patterned portions 146a, 146b can selectively have the structure of the non-patterned portion of the electrode according to the conventional non-patterned portion structure as well as the embodiment (modified form).

[0299] The insulator 146 can cover the first current collector plate 144. By covering the first current collector plate 144 on the upper surface of the first current collector plate 144, direct contact between the first current collector plate 144 and the inner peripheral surface of the battery housing 142 can be prevented.

[0300] The insulator 146 is provided with a lead hole 151 so that a lead 149 extending upward from the first current collector plate 144 can be drawn out. The lead 149 is drawn upward through the lead hole 151 and coupled to the lower surface of the connection plate 143c or the lower surface of the cap plate 143a.

[0301] The peripheral region of the insulator 146 is interposed between the first current collector plate 144 and the beading portion 147, and can fix the combined body of the electrode assembly 141 and the first current collector plate 144. Thereby, the combined body of the electrode assembly 141 and the first current collector plate 144 has its movement in the height direction of the battery 140 restricted, and the assembly stability of the battery 140 can be improved.

[0302] The insulator 146 can be made of an insulating polymer resin. As an example, the insulator 146 can be made of polyethylene, polypropylene, polyimide, or polybutylene terephthalate.

[0303] The battery housing 142 may further include a bending portion 152 formed on its lower surface. The bending portion 152 corresponds to a region having a thinner thickness than the peripheral region on the lower surface of the battery housing 142. The bending portion 152 is structurally weaker than the peripheral region. Therefore, if an abnormality occurs in the cylindrical battery 140 and the internal pressure increases above a certain level, the bending portion 152 can rupture and the gas generated inside the battery housing 142 can be discharged to the outside.

[0304] The bending portion 152 can be formed continuously or discontinuously by drawing a circle on the lower surface of the battery housing 142. In a modified form, the bending portion 152 can be formed in a straight line pattern or other pattern outside thereof.

[0305] FIG. 28 is a cross-sectional view of a cylindrical battery 150 cut along the Y-axis direction according to another embodiment of the present invention.

[0306] Referring to FIG. 28, the cylindrical battery 150 has substantially the same other configuration as the cylindrical battery 140 in FIG. 27, except that the electrode structure of the second embodiment (modified form) is adopted for the plain portion 146a of the first electrode.

[0307] Referring to FIG. 28, the plain portion 146a of the first electrode may be configured such that the height of the outer peripheral plain portion B3 gradually or stepwise decreases toward the inner peripheral surface of the battery housing 142. Desirably, a virtual line connecting the uppermost ends of the outer peripheral plain portion B3 may have the same or a similar shape as the inner peripheral surface of the beading portion 147.

[0308] The outer peripheral plain portion B3 forms an inclined surface. Therefore, when the battery housing 142 is pushed in to form the beading portion 147, it is possible to prevent the outer peripheral plain portion B3 from being pressed and damaged by the beading portion 147. In addition, it is possible to suppress a phenomenon in which the outer peripheral plain portion B3 comes into contact with the battery housing 142 of the opposite polarity and causes an internal short circuit.

[0309] Other configurations of the cylindrical battery 150 are substantially the same as those of the above-described embodiments (modifications).

[0310] The plain portions (the first plain portion 146a and the second plain portion 146b) are not limited to the illustrated structures. Therefore, the plain portions 146a and 146b may selectively have the structures of the plain portions of the electrodes according to the embodiments (modifications) as well as the structures of the conventional plain portions.

[0311] FIG. 29 is a cross-sectional view of a cylindrical battery 160 according to still another embodiment of the present invention, taken along the Y-axis direction.

[0312] Referring to FIG. 29, the cylindrical battery 160 has a structure in which, compared with the above-described cylindrical batteries 140 and 150, a lead 149 connected to the first current collector 144 passes through a lead hole 151 of an insulator 146 and is directly connected to a cap plate 143a of a sealing body 143, and the insulator 146 and the first current collector 144 are in close contact with the lower surface of the cap plate 143a. Other configurations are substantially the same.

[0313] In the cylindrical battery 160, the diameter of the first current collector plate 144 and the outermost diameter of the intermediate non-patterned portion B2 are smaller than the minimum inner diameter of the battery housing 142. Also, the diameter of the first current collector plate 144 can be the same as or larger than the outermost diameter of the intermediate non-patterned portion B2.

[0314] Specifically, the minimum inner diameter of the battery housing 142 can correspond to the inner diameter of the battery housing 142 at the position where the beading portion 147 is formed. At this time, the outermost diameters of the first current collector plate 144 and the intermediate non-patterned portion B2 are smaller than the inner diameter of the battery housing 142 at the position where the beading portion 147 is formed. Also, the diameter of the first current collector plate 144 can be the same as or larger than the outermost diameter of the intermediate non-patterned portion B2. The peripheral region of the insulator 146 is interposed between the outer peripheral non-patterned portion B3 and the beading portion 147 in a state of being bent downward, and can fix the combined body of the electrode assembly 141 and the first current collector plate 144.

[0315] Desirably, the insulator 146 includes a portion covering the outer peripheral non-patterned portion B3 and a portion covering the first current collector plate 144, and the portion connecting these two portions can have a form bent together corresponding to the bent shape of the beading portion 147. The insulator 146 can insulate the outer peripheral non-patterned portion B3 from the inner peripheral surface of the beading portion 147 and at the same time insulate the first current collector plate 144 from the inner peripheral surface of the beading portion 147.

[0316] The first current collector plate 144 can be positioned higher than the lower end of the beading portion 147 and can be coupled to the core-side non-patterned portion B1 and the intermediate non-patterned portion B2. At this time, the pushing depth D1 of the beading portion 147 is smaller than or the same as the distance D2 from the inner peripheral surface of the battery housing 142 to the boundary between the outer peripheral non-patterned portion B3 and the intermediate non-patterned portion B2. Therefore, the core-side non-patterned portion B1 and the intermediate non-patterned portion B2, and the first current collector plate 144 coupled thereto can be positioned higher than the lower end of the beading portion 147. The lower end of the beading portion 147 means the bending point B between the portion of the battery housing 142 where the electrode assembly 141 is accommodated and the beading portion 147.

[0317] Since the core-side blank portion B1 and the intermediate blank portion B2 occupy the inner space in the radial direction of the beading portion 147, the empty space between the electrode assembly 141 and the cap plate 143a is minimized. Also, the connecting plate 143c that was located in the empty space between the electrode assembly 141 and the cap plate 143a is omitted. Therefore, the lead 149 of the first current collector plate 144 can be directly coupled to the lower surface of the cap plate 143a. According to such a structure, the empty space in the battery is reduced, and the energy density can be maximized only by the reduced empty space.

[0318] In the cylindrical battery 160, the first current collector plate 144 and the second current collector plate 145 can be welded to the ends of the first blank portion 146a and the second blank portion 146b, respectively, in the same manner as in the above-described embodiment.

[0319] The blank portions 146a and 146b are not limited to only the illustrated structure. Therefore, the blank portions 146a and 146b can selectively have not only the structure of the conventional blank portion but also the structure of the blank portion of the electrode according to the embodiment (deformed form).

[0320] FIG. 30 is a cross-sectional view of a cylindrical battery 170 cut along the Y-axis direction according to still another embodiment of the present invention.

[0321] Referring to FIG. 30, the cylindrical battery 170 is different from the cylindrical battery 140 shown in FIG. 27 in that the structure of the electrode assembly is substantially the same, and other structures except for the electrode assembly are changed.

[0322] Specifically, the cylindrical battery 170 includes a battery housing 171 in which an external terminal 172 is penetratingly provided. The external terminal 172 is attached to the closed surface (the upper surface in the drawing) of the battery housing 171. The external terminal 172 is riveted to the through-hole of the battery housing 171 with an insulating second gasket 173 interposed therebetween. The external terminal 172 is exposed to the outside in the direction opposite to the direction of gravity.

[0323] The external terminal 172 includes a terminal exposed portion 172a and a terminal insertion portion 172b. The terminal exposed portion 172a is exposed outside the closing surface of the battery housing 171. The terminal exposed portion 172a may be located at a substantially central portion of the closing surface of the battery housing 171. The maximum diameter of the terminal exposed portion 172a may be formed larger than the maximum diameter of the through hole formed in the battery housing 171. The terminal insertion portion 172b may penetrate through a substantially central portion of the closing surface of the battery housing 171 and be electrically connected to the non-coated portion 146a of the first electrode. The terminal insertion portion 172b may be rivet-coupled to the inner surface of the battery housing 171. That is, the lower edge portion of the terminal insertion portion 172b may have a form bent toward the inner surface of the battery housing 171. The maximum diameter of the lower portion of the terminal insertion portion 172b may be larger than the maximum diameter of the through hole of the battery housing 171.

[0324] The lower end surface of the terminal insertion portion 172b may be welded to the first current collector plate 144 connected to the non-coated portion 146a of the first electrode. An insulator 174 made of an insulating material may be interposed between the first current collector plate 144 and the inner surface of the battery housing 171. The insulator 174 covers the upper portion of the first current collector plate 144 and the upper peripheral edge portion of the electrode assembly 141. Thereby, it is possible to prevent the non-coated portion B3 on the outer peripheral side of the electrode assembly 141 from contacting the inner surface of the battery housing 171 having an opposite polarity and causing a short circuit. The terminal insertion portion 172b of the external terminal 172 may penetrate through the insulator 174 and be welded to the first current collector plate 144.

[0325] The second gasket 173 is interposed between the battery housing 171 and the external terminal 172 to prevent the battery housing 171 and the external terminal 172 having opposite polarities from being in electrical contact. Thereby, the upper surface of the battery housing 171 having a substantially flat shape can function as the second electrode terminal of the cylindrical battery 170.

[0326] The second gasket 173 includes a gasket exposed portion 173a and a gasket insertion portion 173b. The gasket exposed portion 173a is interposed between the terminal exposed portion 172a of the external terminal 172 and the battery housing 171. The gasket insertion portion 173b is interposed between the terminal insertion portion 172b of the external terminal 172 and the battery housing 171. The gasket insertion portion 173b can be deformed together during the reveting of the terminal insertion portion 172b and be in close contact with the inner surface of the battery housing 171. The second gasket 173 can be made of, for example, a polymer resin having insulation properties.

[0327] The gasket exposed portion 173a of the second gasket 173 may have a form extending so as to cover the outer peripheral surface of the terminal exposed portion 172a of the external terminal 172. When the second gasket 173 covers the outer peripheral surface of the external terminal 172, it is possible to prevent a short circuit from occurring in the process of coupling an electrical connection component such as a bus bar to the upper surface of the battery housing 171 and / or the external terminal 172. Although not shown, the gasket exposed portion 173a may have a form extending so as to cover not only the outer peripheral surface of the terminal exposed portion 172a but also a part of the upper surface.

[0328] When the second gasket 173 is made of a polymer resin, the second gasket 173 can be coupled to the battery housing 171 and the external terminal 172 by heat fusion. In this case, the airtightness at the coupling interface between the second gasket 173 and the external terminal 172 and at the coupling interface between the second gasket 173 and the battery housing 171 is enhanced. On the other hand, when the gasket exposed portion 173a of the second gasket 173 has a form extending to the upper surface of the terminal exposed portion 172a, the external terminal 172 may be integrally coupled to the second gasket 173 by insert injection.

[0329] Another region 175 excluding the regions occupied by the external terminal 172 and the second gasket 173 on the upper surface of the battery housing 171 corresponds to a second electrode terminal having a polarity opposite to that of the external terminal 172.

[0330] The second current collector 176 is coupled to the lower portion of the electrode assembly 141. The second current collector 176 is made of a metal material having conductivity such as aluminum, steel, copper, nickel, etc., and is electrically connected to the plain portion 146b of the second electrode.

[0331] Desirably, the second current collector 176 is electrically connected to the battery housing 171. Therefore, at least a part of the peripheral portion of the second current collector 176 can be interposed and fixed between the inner surface of the battery housing 171 and the first gasket 178b. In one example, at least a part of the peripheral portion of the second current collector 176 can be fixed to the beading portion 180 by welding while being supported by the lower end surface of the beading portion 180 formed at the lower end of the battery housing 171. In a modified example, at least a part of the peripheral portion of the second current collector 176 can be directly welded to the inner wall surface of the battery housing 171.

[0332] The second current collector 176 may be provided with a plurality of irregularities (not shown) formed radially on the surface facing the plain portion 146b. When the irregularities are formed, the second current collector 176 can be pressed to press the plain portion 146b into the irregularities.

[0333] Desirably, the second current collector 176 and the end of the plain portion 146b can be joined by welding, for example, laser welding.

[0334] The sealing body 178 that seals the lower opening of the battery housing 171 includes a cap plate 178a and a first gasket 178b. The first gasket 178b electrically separates the cap plate 178a and the battery housing 171. The crimping portion 181 fixes the peripheral edge of the cap plate 178a and the first gasket 178b together. The cap plate 178a is provided with a vent portion 179. The configuration of the vent portion 179 is substantially the same as that of the above-described embodiment (modified form).

[0335] Preferably, the cap plate 178a is made of a conductive metal material. However, since the first gasket 178b is interposed between the cap plate 178a and the battery housing 171, the cap plate 178a has no electrical polarity. The seal 178 seals the opening at the lower part of the battery housing 171 and functions to discharge gas when the internal pressure of the battery 170 increases above the critical value.

[0336] Preferably, the external terminal 172 electrically connected to the non-patterned portion 146a of the first electrode is used as the first electrode terminal. Also, a portion 175 of the upper surface of the battery housing 171, excluding the external terminal 172, which is electrically connected to the non-patterned portion 146b of the second electrode through the second current collector plate 176, is used as a second electrode terminal having a polarity opposite to that of the first electrode terminal. In this way, when the two electrode terminals are located at the upper part of the cylindrical battery 170, it is possible to arrange electrical connection components such as a bus bar only on one side of the cylindrical battery 170. This can lead to the simplification of the battery pack structure and the improvement of the energy density. Also, since the portion 175 used as the second electrode terminal has a substantially flat form, a sufficient bonding area can be ensured when bonding electrical connection components such as a bus bar. Thereby, the cylindrical battery 170 can reduce the resistance at the bonding site of the electrical connection components to a desirable level.

[0337] The structure of the electrode assembly 141 and the structure of the non-patterned portion are not limited to those shown, and can be replaced with the structures of the above-described embodiments (modification forms).

[0338] FIG. 31 is a cross-sectional view of a cylindrical battery 180 cut along the Y-axis direction according to still another embodiment of the present invention.

[0339] Referring to FIG. 31, the cylindrical battery 180 has substantially the same structure as the cylindrical battery 150 shown in FIG. 28 with respect to the electrode assembly 141, and the other configurations excluding the electrode assembly 141 are substantially the same as those of the cylindrical battery 170 shown in FIG. 30.

[0340] Therefore, the configuration of the embodiments (deformed forms) of the cylindrical batteries 150 and 170 can be similarly applied to the cylindrical battery 180.

[0341] In addition, the structure of the electrode assembly 141 and the structure of the plain portion are not limited to those shown, and can be replaced with the structures of the above-described embodiments (deformed forms).

[0342] FIG. 32 is a cross-sectional view of a cylindrical battery 190 according to still another embodiment of the present invention, cut along the Y-axis direction.

[0343] Referring to FIG. 32, the cylindrical battery 190 includes the electrode assembly A4 shown in FIG. 24, and the other components excluding the electrode assembly A4 are substantially the same as the cylindrical battery 140 shown in FIG. 27.

[0344] Referring to FIG. 32, the plain portions 146a and 146b of the electrode assembly A4 are bent from the outer peripheral side toward the core side. At this time, since the height of the core-side plain portion B1 is lower than that of the other portions, it is not substantially bent. The first current collector plate 144 can be welded to the bent surface of the plain portion 146a, and the second current collector plate 145 can be welded to the bent surface of the plain portion 146b. The bent surfaces can be formed at the upper and lower portions of the electrode assembly A4 while overlapping multiple times along the Y-axis direction when the plain portions 146a and 146b are bent.

[0345] The height of the core-side plain portion B1 of the electrode assembly A4 is relatively lower than that of the other portions. Also, as shown in FIG. 24, the bending length H of the plain portion located innermost in the intermediate plain portion B2 is the same as or shorter than the radial length R of the core-side plain portion B1.

[0346] Therefore, even if the plain portion 146a is bent toward the core side, the cavity 112 of the core of the electrode assembly A4 is not blocked and can be opened at the upper portion (see the dashed-dotted circle).

[0347] If the cavity 112 is not blocked, there is no problem in the electrolyte injection process, and the efficiency of electrolyte injection is improved. Further, a welding jig can be inserted through the cavity 112 to easily perform the welding process between the second current collector plate 145 and the battery housing 142.

[0348] When the plain portions 146a and 146b have a slit structure, if the width and / or height and / or separation pitch of the slit pieces are adjusted to satisfy the numerical range of the above-described embodiment, when the slit pieces are bent, the slit pieces overlap multiple times to such an extent that sufficient welding strength can be ensured, and a space (gap) is not formed on the bent surface.

[0349] The structure of the plain portions 146a and 146b can be changed without limitation to the structure according to the above-described embodiment (deformed form), different from the illustration. Further, the application of the structure of the conventional plain portion to either one of the plain portions 146a and 146b is not limited.

[0350] FIG. 33 is a cross-sectional view of a cylindrical battery 200 according to still another embodiment of the present invention, cut along the Y-axis direction.

[0351] Referring to FIG. 33, the cylindrical battery 200 includes the electrode assembly A4 shown in FIG. 24, and the other configurations except the electrode assembly A4 are substantially the same as those of the cylindrical battery 180 shown in FIG. 31.

[0352] Referring to FIG. 33, the plain portions 146a and 146b of the electrode assembly A4 are bent from the outer peripheral side to the core side. At this time, since the height of the core-side plain portion B1 is lower than that of the other portions, it is not substantially bent. The first current collector plate 144 may be welded to the bent surface of the plain portion 146a, and the second current collector plate 176 may be welded to the bent surface of the plain portion 146b.

[0353] The electrode assembly A4 has a relatively lower height of the core-side plain portion B1 than that of the other portions. Further, as shown in FIG. 24, the bending length H of the plain portion located innermost at the intermediate plain portion B2 is the same as or shorter than the radial length R of the core-side plain portion B1.

[0354] Therefore, even if the plain portions 146a and 146b are bent toward the core side, the cavity 112 of the core of the electrode assembly A4 is not blocked and can be opened at the upper part (see the dotted circle).

[0355] If the cavity 112 is not blocked, there is no problem in the electrolyte injection process, and the efficiency of electrolyte injection is improved. Further, a welding jig can be inserted through the cavity 112, and the welding process between the second current collector plate 176 and the battery housing 171 can be easily performed.

[0356] When the plain portions 146a and 146b have a slit structure, if the width and / or height and / or separation pitch of the slit pieces are adjusted to satisfy the numerical range of the above-described embodiment, when the slit pieces are bent, the slit pieces overlap multiple times to such an extent that sufficient welding strength can be ensured, and no space (gap) is formed on the bent surface.

[0357] The structure of the plain portions 146a and 146b can be changed without being limited to the structure according to the above-described embodiment (deformed form) different from the illustration. Further, it is not limited that the structure of the conventional plain portion is applied to either one of the plain portions 146a and 146b.

[0358] FIG. 34 is a cross-sectional view of a cylindrical battery 210 according to still another embodiment of the present invention, cut along the Y-axis direction.

[0359] Referring to FIG. 34, the cylindrical battery 210 includes the electrode assembly A3 shown in FIG. 23, and the other configurations except the electrode assembly A3 are substantially the same as those of the cylindrical battery 140 shown in FIG. 27.

[0360] Desirably, the plain portions 146a and 146b of the electrode assembly A3 are bent from the outer peripheral side toward the core side. At this time, since the core-side plain portion B1 and the outer peripheral-side plain portion B3 of the plain portion 146a are lower in height than the other portions, they are not substantially bent. The same applies to the plain portion 146b. The first current collector plate 144 can be welded to the bent surface of the plain portion 146a, and the second current collector plate 145 can be welded to the bent surface of the plain portion 146b.

[0361] The height of the core-side non-patterned portion B1 is relatively lower than that of the intermediate non-patterned portion B2. Also, as shown in FIG. 23, the bending length H of the non-patterned portion located innermost in the intermediate non-patterned portion B2 is the same as or shorter than the radial length R of the core-side non-patterned portion B1.

[0362] Therefore, even if the non-patterned portions 146a and 146b are bent toward the core side, the cavity 102 of the core of the electrode assembly A3 is not blocked and can be open at the top (see the dotted circle).

[0363] If the cavity 102 is not blocked, there is no problem in the electrolyte injection process, and the efficiency of electrolyte injection is improved. Also, a welding jig can be inserted through the cavity to easily perform the welding process between the second current collector plate 145 and the battery housing 142.

[0364] Also, the height of the outer peripheral side non-patterned portion B3 is relatively lower than that of the intermediate non-patterned portion B2. Therefore, when the non-patterned portion 146a is bent, the outer peripheral side non-patterned portion B3 is not substantially bent. Also, since the outer peripheral side non-patterned portion B3 is sufficiently separated from the beading portion 147, the problem that the outer peripheral side non-patterned portion B3 is damaged in the process of the beading portion 147 being pushed in can be solved.

[0365] When the non-patterned portions 146a and 146b have a slit structure, if the width and / or height and / or separation pitch of the slit pieces are adjusted to satisfy the numerical range of the above-described embodiment, when the slit pieces are bent, the slit pieces overlap multiple times to a sufficient extent to ensure welding strength and do not form a space (gap) left on the bent surface.

[0366] The structure of the non-patterned portions 146a and 146b can be changed without limitation to the structure according to the above-described embodiment (deformed form), different from the illustration. Also, it is not restricted that the structure of a conventional non-patterned portion is applied to either one of the non-patterned portions 146a and 146b.

[0367] FIG. 35 is a cross-sectional view of a cylindrical battery 220 cut along the Y-axis direction according to still another embodiment of the present invention.

[0368] Referring to FIG. 35, the cylindrical battery 220 includes the electrode assembly A3 shown in FIG. 23, and the other configurations except the electrode assembly A3 are substantially the same as the cylindrical battery 180 shown in FIG. 31.

[0369] Desirably, the plain portions 146a, 146b of the electrode assembly A3 are bent from the outer peripheral side toward the core side. At this time, since the core-side plain portion B1 of the plain portion 146a has a lower height than other portions, it is not substantially bent. The same applies to the plain portion 146b. The first current collector 144 can be welded to the bent surface of the plain portion 146a, and the second current collector 176 can be welded to the bent surface of the plain portion 146b.

[0370] In the electrode assembly A3, the height of the core-side plain portion B1 is relatively lower than that of the intermediate plain portion B2. Also, as shown in FIG. 23, the bending length H of the plain portion located innermost at the intermediate plain portion B2 is the same as or shorter than the radial length R of the core-side plain portion B1.

[0371] Therefore, even if the plain portion 146a is bent toward the core side, the cavity 102 of the core of the electrode assembly A3 is not blocked and can be opened at the upper part (see the dotted circle).

[0372] If the cavity 102 is not blocked, there is no problem in the electrolyte injection process, and the efficiency of electrolyte injection is improved. Also, a welding jig can be inserted through the cavity 102 to easily perform the welding process between the second current collector 176 and the battery housing 171.

[0373] Also, the height of the outer peripheral-side plain portion B3 of the plain portion 146a is relatively lower than that of the intermediate plain portion B2. Therefore, when the plain portion 146a is bent, the outer peripheral-side plain portion B3 is not substantially bent. The same applies to the plain portion 146b.

[0374] When the non-coated portions 146a and 146b have a split structure, if the width and / or height and / or separation pitch of the split pieces are adjusted to satisfy the numerical range of the above-described embodiments, when the split pieces are bent, the split pieces overlap multiple times to such an extent that sufficient welding strength can be ensured, and no space (gap) is formed on the bent surface.

[0375] The structure of the non-coated portions 146a and 146b can be changed without limitation to the structure according to the above-described embodiments (deformed forms), different from the illustration. Also, the application of the structure of the conventional non-coated portion to either one of the non-coated portions 146a and 146b is not restricted.

[0376] The cylindrical battery according to the above-described embodiments (deformed forms) can be used for manufacturing a battery pack (see Fig. 13a), and the battery pack can be mounted on an automobile (see Fig. 13b).

[0377] According to an embodiment of the present invention, by using the non-coated portion itself protruding above and below the electrode assembly as an electrode tab, the internal resistance of the cylindrical battery can be reduced and the energy density can be increased.

[0378] Also, according to an embodiment of the present invention, by improving the structure of the non-coated portion of the electrode assembly, the electrode assembly and the inner peripheral surface of the battery housing do not interfere with each other during the process of forming the beading portion of the battery housing, and an internal short circuit of the cylindrical battery due to partial deformation of the electrode assembly can be prevented.

[0379] Also, according to an embodiment of the present invention, by improving the structure of the non-coated portion of the electrode assembly, a phenomenon in which the non-coated portion near the bending point is broken when the non-coated portion is bent can be prevented, and the number of overlapping layers of the non-coated portion can be sufficiently increased to improve the welding strength.

[0380] Further, according to an embodiment of the present invention, by improving the structure of the plain portion adjacent to the core of the electrode assembly, it is possible to prevent the cavities in the core of the electrode assembly from being blocked when the plain portion is bent, and to easily perform the electrolyte injection step and the welding step between the battery housing and the current collector plate.

[0381] Also, according to an embodiment of the present invention, it is possible to provide a cylindrical battery having a structure with low internal resistance, prevention of internal short circuit, and improved welding strength between the current collector plate and the plain portion, a battery pack including the same, and an automobile.

[0382] Hereinafter, an embodiment of the positive electrode active material used in the cylindrical battery according to an example of the present invention will be described.

[0383] In the embodiment, the "primary particle" means a particle unit in which no grain boundaries are present in appearance when observed at a magnification of 5,000 to 20,000 times using a scanning electron microscope (SEM) or an electron backscatter diffraction (EBSD) pattern analyzer. The "average particle size of primary particles" means the arithmetic mean value calculated after measuring the particle sizes of the primary particles observed in the SEM or EBSD image.

[0384] The "secondary particle" is a particle formed by aggregation of a plurality of primary particles. In the present invention, in order to distinguish from the conventional secondary particles formed by aggregation of several tens to several hundreds of primary particles, the secondary particles formed by aggregation of 10 or less primary particles will be referred to as pseudo single particles.

[0385] In the present invention, the "specific surface area" is measured by the BET method, and specifically, it can be calculated from the nitrogen gas adsorption amount at liquid nitrogen temperature (77K) using Belsorp-mini II manufactured by Nippon Bell Co., Ltd.

[0386] In the present invention, "D min ", "D 50 " and "D max」 is the particle size value of the volume cumulative distribution of the positive electrode active material measured using the laser diffraction method. Specifically, D min is the minimum particle size in the volume cumulative distribution, and D 50 is the particle size when the volume cumulative amount is 50%, and D max is the maximum particle size in the volume cumulative distribution. When the positive electrode active material is a single particle, D 50 means the average particle diameter of the primary particles. Also, when the positive electrode active material is a pseudo-single particle, D 50 means the average particle diameter of the particles formed by aggregation of the primary particles.

[0387] The particle size value of the volume cumulative distribution can be measured, for example, by dispersing the positive electrode active material in a dispersion medium and then introducing it into a commercially available laser diffraction particle size measuring device (for example, MT3000 manufactured by Microtrac), irradiating it with ultrasonic waves of about 28 kHz at an output of 60 W, and then obtaining and measuring a volume cumulative particle size distribution graph.

[0388] In the present invention, "consisting essentially of A" means including the A component and any component not mentioned that does not substantially affect the basic and novel features of the present invention. The basic and novel features of the present invention include at least one of minimizing particle cracking during battery manufacturing, minimizing the gas generated by such particle cracking, and minimizing the generation of internal cracks. A person of ordinary skill in the art can recognize the physical effects of such characteristics.

[0389] As a result of repeated research to develop a positive electrode for an electrochemical element that is excellent in safety while achieving a high capacity and an electrochemical element including the same, the inventors have found that when using, alone, a positive electrode active material in the form of a single particle composed of 1 primary particle or a pseudo-single particle that is an aggregate of 10 or fewer primary particles as the positive electrode active material, the safety of a large cylindrical battery can be remarkably improved.

[0390] According to one embodiment, the positive electrode includes a positive electrode current collector and a positive electrode active material layer formed on at least one side surface of the positive electrode current collector. The positive electrode active material layer may include a positive electrode active material and optionally may include a conductive material and / or a binder.

[0391] The positive electrode may have a structure in which a positive electrode active material layer is formed on at least one or both surfaces of a long sheet-like positive electrode current collector. The positive electrode active material layer may include a positive electrode active material and a binder.

[0392] Specifically, the positive electrode may be manufactured by applying a positive electrode slurry, which is produced by dispersing a positive electrode active material, a conductive material, and a binder in a solvent such as dimethyl sulfoxide (DMSO), isopropyl alcohol, N-methylpyrrolidone (NMP), acetone, water, etc., onto one or both surfaces of a long sheet-like positive electrode current collector, removing the solvent of the positive electrode slurry through a drying process, and then rolling. On the other hand, a positive electrode including a non-coated portion (non-coated part) may be manufactured by a method of not applying the positive electrode slurry to a partial region of the positive electrode current collector, for example, one end portion of the positive electrode current collector, during the application of the positive electrode slurry.

[0393] In another embodiment, the positive electrode active material includes single-particle system active material particles. In one embodiment, the single-particle system active material particles may be included at 90 wt% or more, 95 wt% or more, 98 wt% or more, or 99 wt% or more based on 100 wt% of the positive electrode active material. In a specific embodiment, the positive electrode active material may be composed only of the single-particle system active material particles.

[0394] In this specification, the single-particle system active material particles refer to those including all single particles, pseudo-single particles, or both of them. The single particle is a particle composed of one primary particle, and the pseudo-single particle is an aggregate of 10 or fewer primary particles.

[0395] Conventionally, as the positive electrode active material of a lithium battery, spherical secondary particles aggregated from dozens to hundreds of primary particles have generally been used. However, in the case of a positive electrode active material in the form of secondary particles in which many primary particles are aggregated in this way, the primary particles are likely to fall off and particle cracking is likely to occur during the rolling process in the production of the positive electrode, and there is a problem that cracks occur inside the particles during the charge and discharge process. When particle cracking or cracks inside the particles of the positive electrode active material occur, the contact area with the electrolytic solution increases, so there is a problem that gas generation due to side reactions with the electrolytic solution increases. If gas generation increases inside a cylindrical battery, there is a risk that the internal pressure of the battery will increase and the battery will explode. In particular, when increasing the volume of a cylindrical battery, the amount of active material inside the battery increases due to the increase in volume, and as a result, the amount of gas generation also increases significantly, so the risk of ignition and / or explosion of the battery becomes even greater.

[0396] On the other hand, single-particle active material particles in the form of single particles composed of one primary particle or pseudo-single particles aggregated from 10 or fewer primary particles have higher particle strength than conventional secondary particle-shaped positive electrode active materials in which dozens to hundreds of primary particles are aggregated. Therefore, almost no particle cracking occurs during rolling. Also, in the case of single-particle active material particles, since the number of primary particles constituting the particles is small, there are few changes due to volume expansion and contraction of the primary particles during charge and discharge, and as a result, the occurrence of cracks inside the particles is also significantly reduced.

[0397] Therefore, when using single-particle active material particles as in one embodiment of the present invention, the amount of gas generation due to particle cracking and internal cracks can be significantly reduced. As a result, when applied to a large cylindrical battery, excellent safety can be achieved.

[0398] On the other hand, it is desirable that the single particles and / or pseudo-single particles be contained in an amount of 95 wt% to 100 wt%, preferably 98 wt% to 100 wt%, more preferably 99 wt% to 100 wt%, and even more preferably 100 wt% based on the weight of the total positive electrode active material contained in the positive electrode.

[0399] When the content of single particles and / or pseudo-single particles satisfies the above range, sufficient safety can be obtained when applied to large-sized batteries. When the secondary particle form of the positive electrode active material is contained in an amount exceeding 5 wt% in the total positive electrode active material, side reactions with the electrolyte increase due to fine powder generated from the secondary particles during the manufacture of the electrode and during charge and discharge, resulting in a decrease in the effect of suppressing gas generation, and thus a decrease in the effect of improving stability when applied to large-sized batteries.

[0400] On the other hand, the positive electrode active material containing single particles and / or pseudo-single particles according to an embodiment of the present invention has a D min that can be 1.0 μm or more, 1.1 μm or more, 1.15 μm or more, 1.2 μm or more, 1.25 μm or more, 1.3 μm or more, or 1.5 μm or more. When the D min of the positive electrode active material is less than 1.0 μm, the line pressure increases in the rolling process of the positive electrode, resulting in easy occurrence of particle cracking, a decrease in thermal stability, and insufficient thermal stability assurance when applied to large cylindrical batteries.

[0401] On the other hand, considering the resistance and output characteristics, the D min of the positive electrode active material can be 3 μm or less, 2.5 μm or less, or 2 μm or less. If the D min is too large, the diffusion distance of lithium ions in the particles increases, which may lead to a decrease in resistance and output characteristics.

[0402] For example, the D min of the positive electrode active material can be 1.0 μm to 3 μm, 1.0 μm to 2.5 μm, or 1.3 μm to 2.0 μm.

[0403] On the other hand, the positive electrode active material can have a D 50 of 5 μm or less, 4 μm or less, or 3 μm or less, and can be, for example, 0.5 μm to 5 μm, preferably 1 μm to 5 μm, more preferably 2 μm to 5 μm.

[0404] The cathode active material in single-particle and / or pseudo-single-particle form has a problem that the lithium ion mobility is lower than that of the cathode active material in secondary particle form due to fewer interfaces between primary particles that serve as diffusion paths for lithium ions inside the particles, resulting in an increase in resistance. Such an increase in resistance becomes more severe as the particle size increases, and an increase in resistance affects the capacity and output characteristics. Therefore, by adjusting D 50 of the cathode active material to 5 μm or less, the increase in resistance can be suppressed by minimizing the lithium ion diffusion distance inside the particles of the cathode active material.

[0405] Also, the cathode active material may have D max in the range of 12 μm to 17 μm, preferably 12 μm to 16 μm, more preferably 12 μm to 15 μm. When D max of the cathode active material satisfies the above range, the resistance characteristics and capacity characteristics are further excellent. If D max of the cathode active material is too large, it means that aggregation occurs between single particles, and the lithium ion migration path inside the aggregated particles becomes long, resulting in a decrease in lithium ion mobility and thus an increase in resistance. On the other hand, if D max of the cathode active material is too small, it means that excessive crushing has occurred, and due to excessive crushing, D min can be less than 1 μm, so there is a risk of inducing particle cracking during rolling and reducing the thermal stability.

[0406] On the other hand, the cathode active material may have a particle size distribution (PSD) represented by the following formula 1 of 3 or less, preferably 2 to 3, more preferably 2.3 to 3. [Formula 1] Particle size distribution (PSD) = (D max - D min ) / D 50

[0407] When the cathode active material has the above particle size distribution, the electrode density of the cathode can be appropriately maintained, and particle cracking and resistance increase can be effectively suppressed.

[0408] On the one hand, the average particle size of the primary particles of the positive electrode active material can be 5 μm or less, 4 μm or less, 3 μm or less, or 2 μm or less, and for example, it can be 0.5 μm to 5 μm, desirably 1 μm to 5 μm, more desirably 2 μm to 5 μm. When the average particle size of the primary particles satisfies the above range, it is possible to form a positive electrode active material in the form of single particles and / or pseudo single particles with excellent electrochemical properties. If the average particle size of the primary particles is too small, the number of aggregated primary particles forming the positive electrode active material increases, and the effect of suppressing particle cracking during rolling may decrease. Also, if the average particle size of the primary particles is too large, the lithium diffusion path inside the primary particles becomes longer, the resistance increases, and the output characteristics may decrease.

[0409] In one embodiment of the present invention, it is desirable that the positive electrode active material has a unimodal particle size distribution. Conventionally, in order to improve the electrode density of the positive electrode active material layer, a bimodal positive electrode active material in which a large particle size positive electrode active material with a large average particle size and a small particle size positive electrode active material with a small average particle size are mixed and used has been widely used. However, in the case of a positive electrode active material in the form of single particles or pseudo single particles, as the particle size increases, the lithium migration path becomes longer and the resistance increases significantly. Therefore, when using a mixture of large particle size particles, there is a risk of problems such as a decrease in capacity and output characteristics. Therefore, in the present invention, by using a positive electrode active material having a unimodal distribution, an increase in resistance can be minimized.

[0410] On the other hand, the positive electrode active material may contain a lithium nickel-based oxide, and specifically, it may contain a lithium nickel-based oxide containing 80 mol% or more of Ni based on the total number of moles of transition metals. Desirably, the lithium nickel-based oxide may contain 80 mol% or more and less than 100 mol% of Ni, 82 mol% or more and less than 100 mol% of Ni, or 83 mol% or more and less than 100 mol% of Ni. When using a lithium nickel-based oxide with a high Ni content as described above, a high capacity can be achieved.

[0411] More specifically, the positive electrode active material may contain a lithium nickel-based oxide represented by the following Chemical Formula 1. [Chemical Formula 1] Li a Ni b Co c M 1 d M 2 e O2 In Chemical Formula 1, the M 1 may be Mn, Al, or a combination thereof, and desirably may be Mn, or Mn and Al.

[0412] The M 2 is one or more selected from the group consisting of Zr, W, Y, Ba, Ca, Ti, Mg, Ta, and Nb, and desirably may be one or more selected from the group consisting of Zr, Y, Mg, and Ti, and more desirably may be Zr, Y, or a combination thereof. The M 2 element is not necessarily included, but when included in an appropriate amount, it can play a role in promoting particle growth during firing or improving the stability of the crystal structure.

[0413] The a represents the lithium molar ratio in the lithium nickel-based oxide, and may be 0.8 ≤ a ≤ 1.2, 0.85 ≤ a ≤ 1.15, or 0.9 ≤ a ≤ 1.2. When the molar ratio of lithium satisfies the above range, the crystal structure of the lithium nickel-based oxide can be stably formed.

[0414] The b represents the nickel molar ratio in the total metal excluding lithium in the lithium nickel-based oxide, and may be 0.8 ≤ b < 1, 0.82 ≤ b < 1, 0.83 ≤ b < 1, 0.85 ≤ b < 1, 0.88 ≤ b < 1, or 0.90 ≤ b < 1. When the nickel molar ratio satisfies the above range, a high energy density can be exhibited and a high capacity can be realized.

[0415] The c represents the molar ratio of cobalt in the total metal excluding lithium in the lithium nickel-based oxide, and can be 0 < c < 0.2, 0 < c < 0.18, 0.01 ≤ c ≤ 0.17, 0.01 ≤ c ≤ 0.15, 0.01 ≤ c ≤ 0.12, or 0.01 ≤ c ≤ 0.10. When the molar ratio of cobalt satisfies the above range, good resistance characteristics and output characteristics can be realized.

[0416] The d represents the molar ratio of the M element in the total metal excluding lithium in the lithium nickel-based oxide 1 and can be 0 < d < 0.2, 0 < d < 0.18, 0.01 ≤ d ≤ 0.17, 0.01 ≤ d ≤ 0.15, 0.01 ≤ d ≤ 0.12, or 0.01 ≤ d ≤ 0.10. When the molar ratio of the M element satisfies the above range, the structural stability of the positive electrode active material is excellent. 1

[0417] The e represents the molar ratio of the M element in the total metal excluding lithium in the lithium nickel-based oxide 2 and can be 0 ≤ e ≤ 0.1 or 0 ≤ e ≤ 0.05.

[0418] On the other hand, the positive electrode active material according to an embodiment of the present invention may further include, if necessary, a coating layer containing one or more coating elements selected from the group consisting of Al, Ti, W, B, F, P, Mg, Ni, Co, Fe, Cr, V, Cu, Ca, Zn, Zr, Nb, Mo, Sr, Sb, Bi, Si, and S on the surface of the lithium nickel-based oxide particles. Desirably, the coating element can be Al, B, Co, or a combination thereof.

[0419] When a coating layer exists on the surface of the lithium nickel-based oxide particles, the contact between the electrolyte and the lithium nickel-based oxide is suppressed by the coating layer, and thus the effect of reducing the elution of transition metals or gas generation due to side reactions with the electrolyte can be obtained.

[0420] The positive electrode active material may be contained in an amount of 80 wt% to 99 wt%, preferably 85 wt% to 99 wt%, more preferably 90 wt% to 99 wt% based on the total weight of the positive electrode active material layer.

[0421] On the other hand, as the positive electrode current collector, various positive electrode current collectors used in the art can be used. For example, as the positive electrode current collector, stainless steel, aluminum, nickel, titanium, fired carbon, those obtained by surface treatment with carbon, nickel, titanium, silver, etc. on the surface of aluminum or stainless steel, etc. can be used. The positive electrode current collector may usually have a thickness of 3 μm to 500 μm, and fine irregularities may be formed on the surface of the positive electrode current collector to enhance the adhesive force of the positive electrode active material. The positive electrode current collector can be used in various forms such as films, sheets, foils, nets, porous bodies, foams, non-woven fabric bodies, etc.

[0422] On the other hand, in one embodiment of the present invention, all or part of the single-particle active material particles may have a core-shell structure in which the surface of the particles is coated with a conductive coating layer. The conductive coating layer may cover at least part or all of the particles. The conductive coating layer contains a conductive nanomaterial.

[0423] In the case of the single-particle active material particles, compared with the conventional secondary particle form of the positive electrode active material, there is a problem that the resistance is high and the contact area with the conductive material is small, so the electrical conductivity decreases. If an excessive amount of the conductive material is added to improve the electrical conductivity, aggregation occurs in the positive electrode slurry and the viscosity increases, resulting in a problem of reduced coating properties. Therefore, in order to achieve smooth coating properties, it is necessary to reduce the solid content to lower the viscosity of the positive electrode slurry. However, if the solid content in the positive electrode slurry decreases, the content of the active material decreases, resulting in a problem of reduced capacity characteristics. In order to solve such problems, the present invention enables excellent electrical conductivity to be realized without adding a separate conductive material to the positive electrode slurry by coating the surface of the single-particle active material particles with a conductive nanomaterial.

[0424] In an embodiment of the present invention, when applying a positive electrode active material obtained by coating a conductive nanomaterial on the surface of the single-particle-based active material particles, the positive electrode active material layer may not use a conductive material in a portion excluding the conductive coating layer. Since it is not necessary to additionally use a conductive material that induces aggregation of the positive electrode slurry in this way, the viscosity of the positive electrode slurry decreases and the solid content increases, and the workability of the electrode coating process and the electrode adhesion can be improved.

[0425] In one embodiment of the present invention, the conductive nanomaterial has a nano-size so as to be smoothly coated on the particles, and may be any material having conductivity, and its type is not particularly limited. For example, the conductive nanomaterial can be a carbon nanotube, carbon nanoparticles, or the like.

[0426] The conductive nanomaterial can have various forms, for example, spherical, flaky, or fibrous.

[0427] On the other hand, the conductive coating layer can be formed by a method of heat-treating after mixing the single-particle-based active material particles as the core part and the conductive nanomaterial. At this time, the mixing can be performed by solid-phase mixing or liquid-phase mixing.

[0428] In one embodiment of the present invention, the positive electrode active material layer contains flaky graphite. When using the single-particle-based active material as the positive electrode active material, when the positive electrode active material layer contains flaky graphite, when rolling the positive electrode active material layer, the flaky graphite provides a sliding effect to the positive electrode active material, improving the rolling characteristics of the electrode and reducing the porosity of the electrode to a target level. Thereby, the battery to which the positive electrode according to one embodiment of the present invention is applied can improve stability, initial resistance characteristics, and charge and discharge efficiency.

[0429] In one embodiment of the present invention, the flaky graphite can be contained in an amount of 0.1 wt% to 5 wt%, preferably 0.1 wt% to 3 wt%, based on 100 wt% of the positive electrode active material layer.

[0430] When the content of the flaky graphite satisfies the above range, the rolling characteristics of the positive electrode can be improved, and excellent electrode density can be achieved. If the content of the flaky graphite is small, the improvement effect of the rolling characteristics is low. If it is excessive, it may induce an increase in the slurry viscosity and a decrease in the phase stability, and the electrode uniformity may be reduced due to the combination with the conductive material, and the resistance may increase.

[0431] On the other hand, the flaky graphite used in the present invention may have an average particle size of 1 μm to 20 μm, preferably 2 μm to 10 μm, more preferably 3 μm to 5 μm, but is not limited thereto. If the flaky graphite is too small, it is difficult to achieve the desired porosity, and the current density may be reduced and the capacity may decrease. At this time, the average particle size of the flaky graphite can be measured by the laser diffraction method (ISO 13320).

[0432] Further, the flaky graphite may have an aspect ratio of 0.1 to 500, preferably 1 to 100, more preferably 1 to 30. When the aspect ratio of the flaky graphite satisfies the above range, it has the effect of improving conductivity and reducing electrode resistance.

[0433] Further, the flaky graphite has a density of 2.0 g / cm 3 ~2.5 g / cm 3 , preferably 2.1 g / cm 3 ~2.4 g / cm 3 , more preferably 2.2 g / cm 3 ~2.3 g / cm 3 and may be.

[0434] On the other hand, in one embodiment of the present invention, the porosity of the positive electrode active material layer may be 15% to 23%, preferably 17% to 23%, more preferably 18% to 23%. When the porosity of the positive electrode active material layer satisfies the above range, the electrode density can be increased to achieve excellent capacity, and the resistance can be reduced. If the porosity is too low, the electrolyte impregnation property may be reduced, and lithium precipitation may occur due to the non-impregnation of the electrolyte. If the porosity is too high, the contact between the electrodes is not good, the resistance increases, the energy density decreases, and the effect of improving the capacity is low.

[0435] The porosity numerical value of the positive electrode active material layer can be achieved by i) the positive electrode active material containing single-particle active material particles, and ii) adding flaky graphite to the positive electrode active material.

[0436] When realizing a high-loading electrode with a relatively high loading amount of the positive electrode active material layer, when using a positive electrode active material in the form of single particles or pseudo-single particles as in an embodiment of the present invention, compared with the conventional positive electrode active material in the form of secondary particles, the particle cracking of the active material during rolling is significantly reduced, and the damage to the positive electrode current collector (Al foil) is reduced. Therefore, it becomes possible to roll at a relatively high linear pressure, and the porosity of the positive electrode active material layer is reduced to the numerical range as described above, and the energy density can be increased.

[0437] Also, when the positive electrode active material layer contains flaky graphite as in an embodiment of the present invention, the flaky graphite provides a sliding effect during rolling and can fill the voids of the positive electrode active material layer. Therefore, the porosity of the positive electrode active material layer can be reduced to the numerical range as described above.

[0438] Also, the positive electrode has a loading amount of 570 mg / 25 cm 2 or more, desirably 600 mg / 25 cm 2 ~800 g / 25 m 2 and more desirably 600 mg / 25 cm 2 ~750 mg / 25 cm 2 It can be. Specifically, in the case of a lithium secondary battery according to an embodiment of the present invention, by applying a positive electrode active material and flaky graphite in the form of single particles and / or pseudo-single particles, the rolling characteristics of the electrode are improved, so that the loading amount of the positive electrode can be ensured at a relatively high level, and thereby high-capacity characteristics can be realized.

[0439] In one embodiment of the present invention, the positive electrode active material layer may further contain a conductive material. The conductive material is used to impart conductivity to the electrode, and can be used without particular limitation as long as it has electron conductivity without causing a chemical change inside the battery. Specific examples include graphite such as natural graphite and artificial graphite; carbon-based materials such as carbon black, acetylene black, ketjen black, channel black, furnace black, lamp black, thermal black, carbon fiber, and carbon nanotube; metal powders or metal fibers such as copper, nickel, aluminum, and silver; conductive whiskers such as zinc oxide and potassium titanate; conductive metal oxides such as titanium oxide; or conductive polymers such as polyphenylene derivatives. One of these or a mixture of two or more thereof can be used. The conductive material can usually be contained in an amount of 1 wt% to 30 wt%, preferably 1 wt% to 20 wt%, more preferably 1 wt% to 10 wt% based on the total weight of the positive electrode active material layer.

[0440] In a specific embodiment according to an example of the present invention, the conductive material may include carbon nanotubes.

[0441] In one embodiment of the present invention, the positive electrode active material may include multi-walled carbon nanotubes having a high specific surface area and a small number of layers (wall number) as a conductive material. The multi-walled carbon nanotubes can be contained in an amount of 50 wt% or more, 70 wt% or more, 90 wt% or more, or 99 wt% or more based on 100 wt% of the conductive material. In a specific embodiment of the present invention, the conductive material may be composed only of the multi-walled carbon nanotubes.

[0442] In one example of the present invention, the multi-walled carbon nanotubes 2 have a BET specific surface area of 300 m 2 / g to 500 m

[0443] / g. To distinguish this from the prior art, it is referred to as "novel CNT". Conventionally, commonly used carbon nanotubes (conventional CNTs) have a BET specific surface area of 300 m2 Less than / g. When comparing the scanning electron microscope images and physical properties of the novel CNT (Figure 36) and the conventional CNT (Figure 37) used in the present invention (Figure 38), the following is the case.

[0444] As can be seen from the SEM image, the novel CNT applied to an embodiment of the present invention is of a bundled type and has a multi-wall structure. However, compared with the conventional CNT, it has a higher BET, fewer layers and a smaller diameter.

[0445] When using a cathode active material in the form of secondary particles, sufficient electrical conductivity can be achieved even when using about 0.4 wt% to 0.6 wt% of the conventional CNT. However, in the case of a cathode active material in the form of single particles or pseudo-single particles, the resistance is higher than that of the conventional cathode active material in the form of secondary particles, the contact area with the conductive material is small, and the electrical conductivity decreases. Therefore, in order to achieve sufficient electrical conductivity using a conventional CNT with a BET specific surface area of less than 300 m 2 / g, the content of the conductive material must be 0.9 wt% or more.

[0446] Figures 39 to 42 are graphs showing the surface resistance and high-temperature life characteristics according to the ratio of the conductive material when applying single particles or pseudo-single particles as the cathode active material.

[0447] From the graph, it can be seen that when applying single particles or pseudo-single particles as the cathode active material, it is necessary to increase the amount of the conductive material used compared with the case of applying the conventional cathode active material in the form of secondary particles.

[0448] However, if the content of the carbon nanotube increases to 0.9 wt% or more, aggregation occurs in the cathode slurry and the viscosity increases, thereby reducing the coating property. Therefore, in order to achieve a smooth coating property, it is necessary to reduce the solid content in the cathode slurry to lower the viscosity of the cathode slurry. However, there is a problem that when the solid content in the cathode slurry decreases, the active material content decreases and the capacity characteristics deteriorate.

[0449] As a result of repeated studies to solve such problems, the inventors of the present invention, together with a positive electrode active material which is a single-particle active material particle, used carbon nanotubes having a BET specific surface area of 300 m 2 / g to 500 m 2 / g as a conductive material. It was confirmed that even a relatively small amount of carbon nanotubes can ensure sufficient electrical conductivity, and thus, even when the solid content of the positive electrode slurry is increased to about 70 wt% to 80 wt%, the slurry viscosity can be kept low.

[0450] Specifically, the carbon nanotubes used in the present invention may be multi-walled carbon nanotubes having a BET specific surface area of 300 m 2 / g to 500 m 2 / g, preferably 300 m 2 / g to 450 m 2 / g. When the BET specific surface area satisfies the above range, sufficient electrical conductivity can be ensured even with only a small amount of carbon nanotubes.

[0451] Further, the carbon nanotubes may be multi-walled carbon nanotubes having a layer number (wall number) of 2 to 8, preferably 2 to 6, more preferably 3 to 6.

[0452] Further, the carbon nanotubes may have a diameter of 1 nm to 8 nm, preferably 3 nm to 8 nm, more preferably 3 nm to 6 nm.

[0453] The carbon nanotubes may be contained in an amount of 0.7 wt% or less, preferably 0.3 wt% to 0.7 wt%, more preferably 0.4 wt% to 0.6 wt% based on the total weight of the positive electrode active material layer. When the content of the carbon nanotubes satisfies the above range, sufficient electrical conductivity can be realized and the solid content in the positive electrode slurry can be kept high. Therefore, the content of the positive electrode active material can be increased in the positive electrode active material layer, and excellent capacity characteristics can be realized thereby.

[0454] The table shown in FIG. 43 shows that the BET specific surface area is 300 m 2 / g to 500 m2 When applying carbon nanotubes (new CNTs) with a BET specific surface area of 200 m 2 / g or more and less than 300 m 2 / g (conventional CNTs), the solid content, viscosity, resistance value in the MP coating layer, and resistance value in the MP interface layer of the positive electrode slurry were compared. From the table, it can be confirmed that when applying new CNTs, even when the solid content of the positive electrode slurry is higher than that of conventional CNTs, it shows a lower viscosity and also has excellent electrical conductivity.

[0455] The binder plays a role in improving the adhesion between the positive electrode active material particles and the adhesion force between the positive electrode active material and the positive electrode current collector. Specific examples include polyvinylidene fluoride (PVDF), vinylidene fluoride - hexafluoropropylene copolymer (PVDF - co - HFP), polyvinyl alcohol, polyacrylonitrile, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone, polytetrafluoroethylene, polyethylene, polypropylene, ethylene - propylene - diene monomer (EPDM) rubber, sulfonated EPDM, styrene - butadiene rubber (SBR), fluorine rubber, or various copolymers thereof, etc. One of these alone or a mixture of two or more can be used. The binder can be contained in an amount of 1 wt% to 30 wt%, preferably 1 wt% to 20 wt%, more preferably 1 wt% to 10 wt% based on the total weight of the positive electrode active material layer.

[0456] Another embodiment of the present invention relates to an electrode assembly including the positive electrode and a battery including the same. The electrode assembly includes a negative electrode and a positive electrode, and the positive electrode has the structural features as described above.

[0457] The electrode assembly may be laminated, for example, with a separator interposed between the negative electrode and the positive electrode to form a laminated or laminated / folded structure, or may be wound to form a jelly roll-type structure. When forming a jelly roll-type structure, a separator may be further disposed on the outside to prevent contact between the negative electrode and the positive electrode.

[0458] The negative electrode includes a negative electrode current collector and a negative electrode active material layer formed on at least one surface of the negative electrode current collector. The negative electrode may have a structure in which a negative electrode active material layer is formed on one or both surfaces of a long sheet-shaped negative electrode current collector, and the negative electrode active material layer may include a negative electrode active material, a conductive material, and a binder.

[0459] Specifically, the negative electrode can be manufactured by applying a negative electrode slurry prepared by dispersing a negative electrode active material, a conductive material, and a binder in a solvent such as dimethyl sulfoxide (DMSO), isopropyl alcohol, N-methylpyrrolidone (NMP), acetone, water, etc. on one or both surfaces of a long sheet-shaped negative electrode current collector, removing the solvent of the negative electrode slurry through a drying process, and then rolling. When applying the negative electrode slurry, a negative electrode without a coating portion can be manufactured by a method of not applying the negative electrode slurry to a partial region of the negative electrode current collector, for example, one end portion of the negative electrode current collector.

[0460] As the negative electrode active material, a compound capable of reversible intercalation and deintercalation of lithium can be used. Specific examples include carbonaceous materials such as artificial graphite, natural graphite, graphitized carbon fiber, and amorphous carbon; silicon-based materials such as Si, Si-Me alloy (where Me is one or more selected from the group consisting of Al, Sn, Mg, Cu, Fe, Pb, Zn, Mn, Cr, Ti, and Ni), SiO y (where 0 < y < 2), Si-C composites, etc.; lithium metal thin films; metal materials capable of alloying with lithium such as Sn, Al, etc.; and the like. Any one or a mixture of two or more of these can be used.

[0461] In one embodiment of the present invention, the negative electrode may contain a silicon-based negative electrode active material. The silicon-based negative electrode active material may be Si, Si-Me alloy (where Me is one or more selected from the group consisting of Al, Sn, Mg, Cu, Fe, Pb, Zn, Mn, Cr, Ti, and Ni), SiO y (where 0 < y < 2), a Si-C composite, or a combination thereof, and preferably SiO y (where 0 < y < 2). Since the silicon-based negative electrode active material has a high theoretical capacity, when the silicon-based negative electrode active material is included, the capacity characteristics can be improved.

[0462] The silicon-based negative electrode active material may be doped with M b metal. At this time, the M b metal may be a Group 1 metal element or a Group 2 metal element, and specifically, may be Li, Mg, etc. Specifically, the silicon-based negative electrode active material may be Si doped with M b metal, SiO y (where 0 < y < 2), a Si-C composite, etc. In the case of a metal-doped silicon-based negative electrode active material, although the active material capacity decreases somewhat due to the doping element, it has high efficiency, so a high energy density can be realized.

[0463] FIG. 60 is a graph showing the change in energy density according to the content of the silicon-based negative electrode active material and the presence or absence of doping of the silicon-based negative electrode active material in a battery using a mixture of the silicon-based negative electrode active material and the carbon-based negative electrode active material as the negative electrode active material.

[0464] In FIG. 60, low-efficiency SiO is undoped SiO, and ultra-high-efficiency SiO means Mg / Li-doped SiO. From FIG. 60, it can be confirmed that the energy density improves as the content of the silicon-based negative electrode active material in the total negative electrode active material increases. Also, it can be confirmed that the improvement effect of the energy density is more excellent as the ratio of the doped silicon-based negative electrode active material in the silicon-based negative electrode active material increases.

[0465] The silicon-based negative electrode active material may further include a carbon coating layer on the surface of the particles. At this time, the carbon coating amount may be 20 wt% or less, preferably 1 to 20 wt% based on the total weight of the silicon-based negative electrode active material. The carbon coating layer may be formed through methods such as dry coating, wet coating, chemical vapor deposition (CVD), physical vapor deposition (PVD), atomic layer deposition (ALD), etc.

[0466] In one embodiment of the present invention, the silicon-based negative electrode active material may have a capacity of 1,000 to 4,000 mAh / g, and the initial efficiency may be about 60 to 95%.

[0467] In another embodiment of the present invention, the D 50 of the silicon-based negative electrode active material may be 3 μm to 8 μm, and D min ~D max may be included in the range of 0.5 μm to 30 μm.

[0468] The negative electrode may further include a carbon-based negative electrode active material as a negative electrode active material as needed. The carbon-based negative electrode active material may be, for example, artificial graphite, natural graphite, graphitized carbon fiber, amorphous carbon, soft carbon, hard carbon, etc., but is not limited thereto.

[0469] When using a mixture of a silicon-based negative electrode active material and a carbon-based negative electrode active material as the negative electrode active material, the mixing ratio of the silicon-based negative electrode active material and the carbon-based negative electrode active material may be 1:99 to 20:80, preferably 1:99 to 15:85, more preferably 1:99 to 10:90 by weight ratio.

[0470] The negative electrode active material may be contained in an amount of 80 wt% to 99 wt%, preferably 85 wt% to 99 wt%, more preferably 90 wt% to 99 wt% based on the total weight of the negative electrode active material layer.

[0471] As needed, the negative electrode active material may further include one or more selected from lithium metal and metal substances capable of alloying with lithium such as Sn and Al.

[0472] As the negative electrode current collector, a negative electrode current collector generally used in the art can be used. For example, copper, stainless steel, aluminum, nickel, titanium, fired carbon, those surface-treated with carbon, nickel, titanium, silver, etc. on the surface of copper or stainless steel, aluminum-cadmium alloy, etc. can be used. The negative electrode current collector can usually have a thickness of 3 μm to 500 μm. Similar to the positive electrode current collector, fine irregularities may be formed on the surface of the current collector to strengthen the bonding force of the negative electrode active material. For example, the negative electrode current collector can be used in various forms such as films, sheets, foils, nets, porous bodies, foams, non-woven fabrics, etc.

[0473] The conductive material is used to impart conductivity to the negative electrode. As long as it has electronic conductivity without causing chemical changes inside the battery, it can be used without particular limitation. Specific examples of the conductive material include graphite such as natural graphite and artificial graphite; carbon-based substances such as carbon black, acetylene black, ketjen black, channel black, furnace black, lamp black, thermal black, carbon fiber, carbon nanotube; metal powders or metal fibers such as copper, nickel, aluminum, silver; conductive whiskers such as zinc oxide, potassium titanate; conductive metal oxides such as titanium oxide; or conductive polymers such as polyphenylene derivatives. One of these alone or a mixture of two or more can be used. The conductive material can usually be contained in an amount of 1 wt% to 30 wt%, preferably 1 wt% to 20 wt%, more preferably 1 wt% to 10 wt% based on the total weight of the negative electrode active material layer.

[0474] The binder plays a role in improving the adhesion between negative electrode active material particles and the adhesion force between the negative electrode active material and the negative electrode current collector. Specific examples of the binder include polyvinylidene fluoride (PVDF), vinylidene fluoride - hexafluoropropylene copolymer (PVDF - co - HFP), polyvinyl alcohol, polyacrylonitrile, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone, polytetrafluoroethylene, polyethylene, polypropylene, ethylene - propylene - diene monomer (EPDM) rubber, sulfonated EPDM, styrene - butadiene rubber (SBR), fluorine rubber, or various copolymers thereof. Among these, one kind alone or a mixture of two or more kinds can be used. The binder may be contained in an amount of 1 wt% to 30 wt%, preferably 1 wt% to 20 wt%, more preferably 1 wt% to 10 wt% based on the total weight of the negative electrode active material layer.

[0475] The electrode assembly further includes a separator, and the separator is disposed in the electrode assembly in a manner interposed between the negative electrode and the positive electrode. The separator separates the negative electrode and the positive electrode and provides a migration path for lithium ions, and can be used without particular limitation as long as it is usually used as a separator in a lithium battery.

[0476] As the separator, a porous polymer film, for example, a porous polymer film made of polyolefin - based polymers such as ethylene homopolymer, propylene homopolymer, ethylene / butene copolymer, ethylene / hexene copolymer, and ethylene / methacrylate copolymer, or a laminated structure of two or more layers thereof can be used. Also, a normal porous non - woven fabric, for example, a non - woven fabric made of high - melting - point glass fibers, polyethylene terephthalate fibers, etc. may be used. Further, for ensuring heat resistance or mechanical strength, a coated separator containing a ceramic component or a polymer substance may be used.

[0477] Still another embodiment of the present invention relates to a battery including the electrode assembly. In the battery, the electrode assembly and the electrolyte are together housed in a battery case. As the battery case, any suitable one can be selected without particular limitation as long as it is commonly used in the art, such as a pouch type or a metal can type.

[0478] As the electrolyte used in the present invention, various electrolytes that can be used in lithium batteries, such as organic liquid electrolytes, inorganic liquid electrolytes, solid polymer electrolytes, gel-type polymer electrolytes, solid inorganic electrolytes, molten inorganic electrolytes, etc. can be used, and the type thereof is not particularly limited.

[0479] Specifically, the electrolyte may contain an organic solvent and a lithium salt.

[0480] As the organic solvent, any substance can be used without particular limitation as long as it can serve as a medium through which ions involved in the electrochemical reaction of the battery can move. Specifically, examples of the organic solvent include ester solvents such as methyl acetate, ethyl acetate, γ-butyrolactone, and ε-caprolactone; ether solvents such as dibutyl ether or tetrahydrofuran; ketone solvents such as cyclohexanone; aromatic hydrocarbon solvents such as benzene, fluorobenzene; carbonate solvents such as dimethyl carbonate (DMC), diethyl carbonate (DEC), methyl ethyl carbonate (MEC), ethyl methyl carbonate (EMC), ethylene carbonate (EC), and propylene carbonate (PC); alcohol solvents such as ethyl alcohol and isopropyl alcohol; nitriles such as R-CN (where R is a hydrocarbon group having a linear, branched, or cyclic structure of C2 to C20 and may contain a double bond, aromatic ring, or ether bond); amides such as dimethylformamide; dioxolanes such as 1,3-dioxolane; or sulfolanes. Among them, carbonate solvents are desirable, and a mixture of a cyclic carbonate (e.g., ethylene carbonate or propylene carbonate) having high ionic conductivity and high dielectric constant, which can improve the charge-discharge performance of the battery, and a linear carbonate compound with low viscosity (e.g., ethyl methyl carbonate, dimethyl carbonate, or diethyl carbonate) is more desirable.

[0481] The lithium salt can be used without particular limitation as long as it is a compound capable of providing lithium ions used in a lithium battery. Specifically, examples of the lithium salt that can be used include LiPF6, LiClO4, LiAsF6, LiBF4, LiSbF6, LiAlO4, LiAlCl4, LiCF3SO3, LiC4F9SO3, LiN(C2F5SO3)2, LiN(C2F5SO2)2, LiN(CF3SO2)2, LiCl, LiI, or LiB(C2O4)2. The concentration of the lithium salt can be in the range of 0.1 to 5.0 M, preferably 0.1 M to 3.0 M. If the concentration of the lithium salt is within the above range, the electrolyte has appropriate conductivity and viscosity, exhibits excellent electrolyte performance, and lithium ions can move effectively.

[0482] In addition to the above-described electrolyte components, the electrolyte may further contain an additive for the purpose of improving battery life characteristics, suppressing a decrease in battery capacity, improving the discharge capacity of the battery, and the like. For example, examples of the additive include haloalkylene carbonate compounds such as difluoroethylene carbonate, pyridine, triethyl phosphite, triethanolamine, cyclic ether, ethylenediamine, n-glyme, hexamethylphosphoric triamide, nitrobenzene derivatives, sulfur, quinoneimine dyes, N-substituted oxazolidinone, N,N-substituted imidazolidine, ethylene glycol dialkyl ether, ammonium salts, pyrrole, 2-methoxyethanol, or aluminum trichloride, which may be used alone or in combination, but are not limited thereto. The additive may be contained in an amount of 0.1 wt% to 10 wt%, preferably 0.1 wt% to 5 wt%, based on the total weight of the electrolyte.

[0483] In still another embodiment of the present invention, the positive electrode may include a loading reduction portion where the loading amount of the positive electrode active material is less than that in the adjacent region. When the positive electrode has such a structure, the section of the positive electrode active material portion can be increased without fear of lithium precipitation. Thereby, the energy density of the electrode assembly can be improved.

[0484] In recent years, in order to achieve high energy density and cost reduction, development has been progressing in the direction of increasing the size of batteries. As the energy increases according to the size of the battery, the resistance per battery must decrease. To reduce the resistance, instead of attaching an electrode tab to the electrode, a method of using the current collector of the electrode as the electrode tab can be used. At this time, due to the characteristics of the electrode manufacturing process of applying the electrode slurry onto the electrode current collector, a portion where the loading amount decreases occurs at the boundary between the negative electrode active material portion coated with the negative electrode slurry and the negative electrode current collector. Considering the N / P ratio, there is a risk that metallic lithium may precipitate on the positive electrode active material portion facing the portion where the loading amount decreases. Here, the N / P ratio is a value obtained by dividing the capacity of the negative electrode calculated based on the area and capacity per mass of the negative electrode by the capacity of the positive electrode obtained based on the area and capacity per mass of the positive electrode, and generally has a value of 1 or more. That is, the capacity of the negative electrode is manufactured to be larger. For reference, if the N / P ratio does not become 1, metallic lithium is likely to precipitate during charge and discharge, which causes a rapid deterioration of the battery safety during high-rate charge and discharge. In other words, the N / P ratio has a great influence on the safety and capacity of the battery. Thus, due to the risk of precipitation of metallic lithium, the positive electrode active material portion cannot be positioned in the positive electrode portion facing the portion where the loading amount of the negative electrode decreases. This causes the energy density of the battery not to be increased. Therefore, the present invention increases the section of the positive electrode active material portion to improve the energy density.

[0485] FIG. 48 is a view showing an electrode assembly according to an embodiment of the present invention, and FIG. 49 is a cross-sectional view taken along the line A-A' of FIG. 48.

[0486] Referring to FIGS. 48 and 49, an electrode assembly 300 according to an embodiment of the present invention includes a negative electrode 400, a positive electrode 500, and a separator 600. The separator 600 is positioned between the negative electrode 400 and the positive electrode 500. The negative electrode 400, the positive electrode 500, and the separator 600 are wound together to form a jelly roll structure 300S. Here, the jelly roll structure 300S refers to a structure formed by winding the negative electrode 400, the positive electrode 500, and the separator 600. Further, when forming the jelly roll structure 300S, it is desirable that a separator 600 is further disposed on the outside to prevent the negative electrode 400 and the positive electrode 500 from contacting each other.

[0487] The negative electrode 400 includes a negative electrode current collector 410 and a negative electrode active material portion 420 formed by applying a negative electrode active material on the negative electrode current collector 410. In particular, as shown in the figure, the negative electrode active material may be applied to both surfaces of the negative electrode current collector 410 to form the negative electrode active material portion 420. Further, a negative electrode blank portion 430 where no negative electrode active material is applied extends in the first direction d1 in the negative electrode current collector 410. The negative electrode blank portion 430 extends along one end of the wound negative electrode 400. Further, the negative electrode blank portion 430 extends longer than the separator 600 in the first direction d1. Thereby, the negative electrode blank portion 430 may be exposed at one end in the first direction of the jelly roll structure 300S.

[0488] The positive electrode 500 includes a positive electrode current collector 510 and a positive electrode active material portion 520 formed by applying a positive electrode active material on the positive electrode current collector 510. In particular, as shown in the figure, the positive electrode active material may be applied to both surfaces of the positive electrode current collector 510 to form the positive electrode active material portion 520. Further, a positive electrode blank portion 530 where no positive electrode active material is applied extends in the second direction d2 in the positive electrode current collector 510. The positive electrode blank portion 530 extends along one end of the wound positive electrode 500. Further, the positive electrode blank portion 530 extends longer than the separator 600 in the second direction d2. Thereby, the positive electrode blank portion 530 may be exposed at one end in the second direction of the jelly roll structure 300S.

[0489] Here, the first direction d1 and the second direction d2 are opposite directions. Also, the first direction d1 and the second direction d2 can be directions parallel to the height direction of the jelly roll structure 300S.

[0490] In the electrode assembly 300 according to the present embodiment, instead of attaching a separate electrode tab, the electrode tab is utilized by using the non-coated portion 430 of the negative electrode current collector 410 and the non-coated portion 530 of the positive electrode current collector 510 themselves for resistance reduction.

[0491] Although not shown, the non-coated portion 430 of the negative electrode and / or the non-coated portion 530 of the positive electrode may substantially have the same structure as the non-coated portion of the electrode described above.

[0492] In one embodiment, the positive electrode active material portion 520 includes a loading reduction portion 500D where the loading amount of the positive electrode active material is less than that in the adjacent region, and the loading reduction portion 500D is located at one end of the positive electrode 500 in the first direction d1. More specifically, the loading amount of the positive electrode active material may gradually decrease in the first direction d1.

[0493] Here, the loading amount means the coating amount of the active material per unit area. In a portion where the loading amount is large, a large amount of negative electrode active material or positive electrode active material is coated per unit area, and the thickness of the negative electrode active material portion or the positive electrode active material portion may become relatively thick. In a portion where the loading amount is small, a small amount of negative electrode active material or positive electrode active material is coated per unit area, and the thickness of the negative electrode active material portion or the positive electrode active material portion may become relatively thin.

[0494] A slurry containing the active material is applied to form the active material portion, and in such a process, a boundary portion where the loading amount gradually decreases may be formed between the non-coated portion and the active material portion.

[0495] Specifically, the negative electrode active material portion 420 may include a negative electrode boundary portion 420B that forms a boundary between the negative electrode active material portion 420 and the non-coated portion 430 of the negative electrode. The negative electrode boundary portion 420B may gradually decrease in the loading amount in the direction in which the non-coated portion 430 of the negative electrode is located.

[0496] Similarly, the positive electrode active material portion 520 may include a positive electrode boundary portion 520B that forms a boundary between the positive electrode active material portion 520 and the positive electrode non-coated portion 530. The positive electrode boundary portion 520B may gradually decrease in loading amount in the direction in which the positive electrode non-coated portion 530 is located.

[0497] The negative electrode boundary portion 420B and the positive electrode boundary portion 520B in which the loading amount gradually decreases in this way are naturally generated in the process of applying the slurry containing the active material to the negative electrode current collector 410 and the positive electrode current collector 510.

[0498] At this time, based on the direction perpendicular to the second direction d2, in the region corresponding to the positive electrode boundary portion 520B, the amount of the positive electrode active material is less than the amount of the negative electrode active material. As a result, since the N / P ratio becomes a value greater than 1, problems such as precipitation of metallic lithium do not occur.

[0499] However, there is a problem in the region corresponding to the negative electrode boundary portion 420B. Based on the direction perpendicular to the first direction d1, in the region corresponding to the negative electrode boundary portion 420B, the amount of the negative electrode active material is less than the amount of the positive electrode active material. As a result, since the N / P ratio becomes a value less than 1, there is a possibility that a problem of precipitation of metallic lithium may occur.

[0500] Therefore, in the present embodiment, a loading reduction portion 500D is provided in the positive electrode 500, and the negative electrode active material portion 420 is positioned in a portion corresponding to the loading reduction portion 500D based on the direction perpendicular to the first direction d1. More specifically, based on the direction perpendicular to the first direction d1, the negative electrode boundary portion 420B may be located in a portion corresponding to the loading reduction portion 500D.

[0501] By providing a loading reduction portion 500D where the loading amount of the positive electrode active material is less than that of the adjacent region at a position corresponding to the negative electrode boundary portion 420B where the loading amount gradually decreases, the section coated with the positive electrode active material can be increased without fear of lithium precipitation. In particular, the loading reduction portion 500D may have a form in which the loading amount of the positive electrode active material gradually decreases in the first direction d1 so as to correspond to the shape of the negative electrode boundary portion 420B where the loading amount gradually decreases toward the negative electrode non-coated portion 430. Therefore, the N / P ratio of the negative electrode 400 to the positive electrode 500 in the region where the negative electrode boundary portion 420B is formed can be maintained high, and lithium precipitation can be prevented.

[0502] Hereinafter, a method for manufacturing an electrode assembly according to an embodiment of the present invention will be described in detail with reference to FIGS. 50 to 55.

[0503] FIGS. 50 and 51 are diagrams showing the process of manufacturing a negative electrode according to an embodiment of the present invention. Specifically, FIG. 50 is a top view of the negative electrode sheet, and FIG. 51 is a front view of the negative electrode sheet of FIG. 50.

[0504] Referring to FIGS. 50 and 51, a method for manufacturing an electrode assembly according to an embodiment of the present invention includes a step of manufacturing a negative electrode sheet 400S such that a negative electrode active material portion 420 coated with a negative electrode active material and a negative electrode non-coated portion 430 not coated with a negative electrode active material are alternately positioned on a negative electrode current collector 410.

[0505] Specifically, the negative electrode active material portion 420 can be formed by applying the negative electrode active material so as to extend in the third direction d3. Further, by separating the coating regions along the fourth direction d4 perpendicular to the third direction d3, the plurality of negative electrode active material portions 420 can be separated and positioned along the fourth direction d4. That is, the coating process can be performed such that the negative electrode non-coated portion 430 is positioned between the plurality of negative electrode active material portions 420.

[0506] Here, the third direction d3 and the fourth direction d4 are directions for explanation with reference to the negative electrode sheet 400S, and are directions unrelated to the first direction d1 and the second direction d2 in the jelly roll structure 300S described above.

[0507] Thereafter, it may include a step of manufacturing the negative electrode 400 by slitting the negative electrode blank portion 430 and the negative electrode active material portion 420. FIG. 52 is a perspective view showing a negative electrode according to an embodiment of the present invention.

[0508] Referring to FIGS. 50 to 52, slitting can be performed in a direction parallel to the third direction d3 with respect to each of the negative electrode blank portion 430 and the negative electrode active material portion 420, as shown by the dotted lines in FIGS. 50 and 51. Thereby, a plurality of negative electrodes 400 as shown in FIG. 52 can be manufactured from the negative electrode sheet 400S. That is, the negative electrode 400 in FIG. 52 corresponds to one of the plurality of negative electrodes manufactured by slitting the negative electrode sheet 400S in FIGS. 50 and 51. By slitting the negative electrode blank portion 430 and the negative electrode active material portion 420 in the negative electrode sheet 400S respectively, a negative electrode 400 with the negative electrode blank portion 430 extending on one side can be manufactured.

[0509] When forming the negative electrode active material portion 420, a slurry containing the negative electrode active material is applied onto the negative electrode current collector 410. In such a slurry application process, a negative electrode boundary portion 420B in which the loading amount gradually decreases in the direction in which the negative electrode blank portion 430 is located may be formed at the boundary between the negative electrode active material portion 420 and the negative electrode blank portion 430.

[0510] FIGS. 53 and 54 are diagrams showing the process of manufacturing a positive electrode according to an embodiment of the present invention. Specifically, FIG. 53 is a top view of the positive electrode sheet, and FIG. 54 is a front view of the positive electrode sheet in FIG. 53.

[0511] Referring to FIGS. 53 and 54, a method for manufacturing an electrode assembly according to an embodiment of the present invention includes a step of manufacturing a positive electrode sheet 500S such that a positive electrode active material portion 520 coated with a positive electrode active material and a positive electrode blank portion 530 not coated with a positive electrode active material are alternately positioned on a positive electrode current collector 510.

[0512] Specifically, the positive electrode active material can be applied so as to extend in a third direction d3 to form the positive electrode active material portion 520. Also, by adjusting the application interval along a fourth direction d4 perpendicular to the third direction d3, a plurality of positive electrode active material portions 520 can be spaced apart and positioned. That is, the application process can be performed such that a positive electrode blank portion 530 is positioned between the plurality of positive electrode active material portions 520.

[0513] Here, the third direction d3 and the fourth direction d4 are directions for explanation with reference to the positive electrode sheet 500S, and are directions not related to the first direction d1 and the second direction d2 in the jelly roll structure 300S described above.

[0514] Thereafter, it may include a step of manufacturing the positive electrode 500 by slitting the positive electrode blank portion 530 and the positive electrode active material portion 520. FIG. 55 is a perspective view showing the positive electrode 500 according to an embodiment of the present invention.

[0515] Referring to FIGS. 53 to 55, slitting can be performed in a direction parallel to the third direction d3 with respect to each of the positive electrode blank portion 530 and the positive electrode active material portion 520, as shown by the dotted lines in FIGS. 53 and 54. As a result, a plurality of positive electrodes 500 as shown in FIG. 55 can be manufactured from the positive electrode sheet 500S. That is, the positive electrode 500 in FIG. 55 corresponds to one of the plurality of positive electrodes manufactured by slitting the positive electrode sheet 500S in FIGS. 53 and 54. By slitting the positive electrode blank portion 530 and the positive electrode active material portion 520 in the positive electrode sheet 500S, a positive electrode 500 having a positive electrode blank portion 530 extending on one side can be manufactured.

[0516] When forming the positive electrode active material portion 520, a slurry containing the positive electrode active material is applied onto the positive electrode current collector 510. In such a slurry application process, a positive electrode boundary portion 520B in which the loading amount gradually decreases in the direction in which the positive electrode non-coated portion 530 is located may be formed at the boundary between the positive electrode active material portion 520 and the positive electrode non-coated portion 530.

[0517] Referring to FIGS. 48, 52, and 55 together, the step of winding the manufactured negative electrode 400 and positive electrode 500 together with the separator 600 to form the jelly roll structure 300S may be subsequently performed. At this time, in the jelly roll structure 300S, the negative electrode non-coated portion 430 may extend longer than the separator 600 in the first direction d1, and the positive electrode non-coated portion 530 may extend longer than the separator 600 in the second direction d2 opposite to the first direction d1.

[0518] Referring further to FIGS. 53 to 55, in the method for manufacturing an electrode assembly according to an embodiment of the present invention, the positive electrode sheet 500S includes a loading reduction region 500DA where the loading amount of the positive electrode active material is less than that in the adjacent region. There is no particular limitation on the method for forming the loading reduction region 500DA, and it can be formed, for example, by adjusting the coating degree of the slurry.

[0519] In the step of manufacturing the positive electrode 500, the loading reduction region 500DA is slit from the positive electrode active material portion 520. The slit loading reduction region 500DA forms a loading reduction portion 500D in which the loading amount of the positive electrode active material is less than that in the adjacent region in the jelly roll structure 300S shown in FIGS. 48 and 49.

[0520] Specifically, a loading reduction region 500DA where the loading amount of the positive electrode active material is less than that in the adjacent region is formed in the positive electrode active material portion 520 formed on the positive electrode sheet 500S. As shown in FIG. 54, the loading reduction region 500DA can be formed at the center of the positive electrode active material portion 520. On the other hand, the loading reduction region 500DA can be configured such that the loading amount of the positive electrode active material gradually decreases toward the central portion 500C of the loading reduction region 500DA. In the step of manufacturing the positive electrode 500, the loading reduction portion 500D according to the present embodiment can be formed by slitting the central portion 500C of the loading reduction region 500DA.

[0521] That is, the loading reduction region 500DA is formed by applying a slurry containing a positive electrode active material, and a plurality of positive electrodes 500 in which the loading reduction portion 500D is formed can be manufactured by slitting the central portion 500C of the loading reduction region 500DA.

[0522] Referring to FIG. 55, a loading reduction portion 500D is provided at one end of the manufactured positive electrode 500, and a positive electrode blank portion 530 can be provided at the other end of the positive electrode 500 facing the one end.

[0523] Referring to FIGS. 48 and 49, when such a positive electrode 500 is wound to form the jelly roll structure 300S, the loading reduction portion 500D is located at one end of the positive electrode 500 in the first direction d1, and the positive electrode blank portion 530 can be located at one end of the positive electrode 500 in the second direction d2.

[0524] Further, by slitting the central portion 500C of the loading reduction region 500DA, the loading amount of the positive electrode active material in the loading reduction portion 500D can gradually decrease toward the first direction d1.

[0525] Further, in the jelly roll structure 300S, the negative electrode active material portion 420 may be located at a portion corresponding to the loading reduction portion 500D with reference to the direction perpendicular to the first direction d1. More specifically, in the jelly roll structure 300S, the negative electrode boundary portion 420B may be located at a portion corresponding to the loading reduction portion 500D with reference to the direction perpendicular to the first direction d1.

[0526] The corresponding positional relationship between the loading reduction portion 500D and the negative electrode boundary portion 420B is the same as the above-described explanation, so it is omitted.

[0527] Hereinafter, an electrode assembly according to a comparative form of the present invention will be described with reference to FIGS. 56 to 59, and advantages of the electrode assembly according to an embodiment of the present invention over the electrode assembly according to the comparative form will be described.

[0528] FIG. 56 is a diagram showing an electrode assembly according to a comparative form of the present invention, and FIG. 57 is a cross-sectional view taken along line B-B' of FIG. 56.

[0529] Referring to FIGS. 56 and 57, an electrode assembly 600 according to a comparative form of the present invention includes a negative electrode 700, a positive electrode 800, and a separator 900, and the negative electrode 700, the positive electrode 800, and the separator 900 are wound to form a jelly roll structure 600S.

[0530] The negative electrode 700 may include a negative electrode current collector 710, a negative electrode active material portion 720, and a negative electrode non-coated portion 730. Further, the negative electrode non-coated portion 730 may extend in the first direction d1, and the negative electrode active material portion 720 may include a negative electrode boundary portion 720B in which the loading amount gradually decreases while forming a boundary between the negative electrode active material portion 720 and the negative electrode non-coated portion 730.

[0531] FIG. 58 is a diagram showing a process of manufacturing the negative electrode 700 according to a comparative form of the present invention.

[0532] Referring to FIG. 58, after the negative electrode sheet 700S is manufactured such that the negative electrode active material portion 720 and the negative electrode non-coated portion 730 are alternately positioned along the fourth direction d4, the negative electrode non-coated portion 730 and the negative electrode active material portion 720 may be slit to manufacture a plurality of negative electrodes 700.

[0533] On the other hand, referring further to FIGS. 56 and 57, the positive electrode 800 may include a positive electrode current collector 810, a positive electrode active material portion 820, and a positive electrode non-coated portion 830. Further, the positive electrode non-coated portion 830 may extend in the second direction d2 facing the first direction d1, and the positive electrode active material portion 820 may include a positive electrode boundary portion 820B in which the loading amount gradually decreases while forming a boundary between the positive electrode active material portion 820 and the positive electrode non-coated portion 830.

[0534] FIG. 59 is a diagram showing a process of manufacturing the positive electrode 800 according to a comparative form of the present invention.

[0535] Referring to FIG. 59, after the positive electrode sheet 800S is manufactured such that the positive electrode active material portion 820 and the positive electrode non-coated portion 830 are alternately positioned along the fourth direction d4, the positive electrode non-coated portion 830 and the positive electrode active material portion 820 may be slit to manufacture a plurality of positive electrodes 800.

[0536] Thereafter, the manufactured negative electrode 700 and positive electrode 800 may be wound together with the separator 900 to manufacture an electrode assembly 600 according to a comparative form of the present invention.

[0537] That is, the electrode assembly 600 according to the comparative form of the present invention may have a structure similar to that of the electrode assembly 300 according to the embodiment of the present invention, except for the loading reduction portion 500D (see FIG. 49).

[0538] Referring to FIGS. 56 and 57, in the case of the electrode assembly 600 according to the comparative form, with respect to the direction perpendicular to the first direction d1, the positive electrode active material portion 820 cannot be located at the portion corresponding to the negative electrode boundary portion 720B. If the positive electrode active material portion 820 extends to the portion corresponding to the negative electrode boundary portion 720B, the corresponding portion will have a low N / P ratio, and metallic lithium is likely to precipitate. Therefore, in order to prevent lithium precipitation, the length of the positive electrode active material portion 820 has to be limited. That is, the positive electrode active material portion 820 can be formed only in the illustrated B1 region, and the positive electrode active material portion 820 cannot be formed in the B2 region, resulting in the reduction of the length of the positive electrode active material portion 820 by the negative electrode boundary portion 720B.

[0539] On the other hand, referring to FIGS. 48 and 49, in the case of the electrode assembly 300 according to the embodiment of the present invention, with respect to the direction perpendicular to the first direction d1, the positive electrode active material portion 520, particularly the loading reduction portion 500D, can be located at the portion corresponding to the negative electrode boundary portion 420B. Since the loading reduction portion 500D where the loading amount of the positive electrode active material is less than that of the adjacent region is provided at the position corresponding to the negative electrode boundary portion 420B, the N / P ratio at the corresponding portion can be maintained high, and precipitation of lithium can be prevented. Thereby, the positive electrode active material portion 520 can be formed over the A1 region, and the A2 region where the positive electrode active material portion 520 cannot be formed can be reduced. As an example, the width of the positive electrode 500 in the height direction can be increased to 98% or more with respect to the width of the negative electrode 400 in the height direction.

[0540] Comparing the A1 region in FIGS. 48 and 49 with the B1 region in FIGS. 56 and 57, the electrode assembly 300 according to the present embodiment can increase the length of the positive electrode active material portion only by the loading reduction portion 500D. Therefore, a higher energy density can be realized in a limited space as compared with the electrode assembly 600 according to the comparative form.

[0541] Yet another embodiment of the present invention relates to a cylindrical battery including a jelly-roll type electrode assembly having a structure in which a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode are wound in one direction, a cylindrical battery housing in which the electrode assembly is housed, and a battery cap disposed on an upper portion of the battery housing to seal the battery housing. Here, the positive electrode is according to an embodiment of the present invention and contains single-particle active material particles having an average particle diameter D 50 of 5 μm or less as a positive electrode active material. The cylindrical battery may further include an electrolytic solution, and reference may be made to the above description regarding the electrolytic solution.

[0542] The electrode assembly may have a structure such as a laminated type, a laminated / folded type, or a jelly-roll type as described above. In a specific embodiment of the present invention, the electrode assembly may be one in which the positive electrode has a loading reduction portion as described above.

[0543] In the case of a conventional cylindrical battery, there is a problem that current is concentrated on a strip-shaped electrode tab, resulting in a large resistance, generation of a large amount of heat, and poor current collection efficiency.

[0544] In recent years, with the development of technologies related to electric vehicles and the increasing demand for high-capacity batteries, the development of large-sized cylindrical batteries with a large volume has been required. In the case of a small-sized cylindrical battery that has generally been used conventionally, that is, a cylindrical battery having a form factor of 1865 or 2170, since the capacity is small, resistance and heat generation do not seriously affect battery performance. However, if the specifications of a conventional small-sized cylindrical battery are directly applied to a large-sized cylindrical battery, there may be a serious problem with battery safety.

[0545] As the battery size increases, the amount of heat and gas generated inside the battery also increases accordingly. However, such heat and gas can cause the temperature and pressure inside the battery to rise, which may lead to battery ignition or explosion. To prevent this, the heat and gas inside the battery must be properly discharged to the outside. For this purpose, the cross-sectional area of the battery that serves as the heat discharge path to the outside of the battery needs to increase in accordance with the increase in volume. However, usually, the increase in the cross-sectional area does not keep up with the increase in volume. Therefore, as the battery becomes larger, the amount of heat generated inside the battery increases, resulting in problems such as an increased risk of explosion and a decrease in output. In addition, when rapid charging is performed at a high voltage, there is also a risk that the battery may catch fire while generating a large amount of heat around the electrode tab in a short time. Therefore, the present invention proposes a cylindrical battery that has a large volume to achieve a high capacity while having high safety.

[0546] In addition, since the high-loading electrode to which the positive electrode active material in the form of single particles or pseudo-single particles is applied is applied to the cylindrical battery, the initial resistance characteristics and charge-discharge efficiency of the cylindrical battery can be improved.

[0547] The cylindrical battery according to an embodiment of the present invention applies a positive electrode active material in the form of single particles or pseudo-single particles, thereby significantly reducing the amount of gas generation compared to the prior art. As a result, excellent safety can be achieved even in a large cylindrical battery with a foam factor ratio of 0.4 or more.

[0548] The cylindrical battery according to an embodiment of the present invention is preferably a tabless structure battery that does not include an electrode tab, but is not limited thereto.

[0549] The tabless structure battery may, for example, include a plain part where the positive electrode and the negative electrode do not have an active material layer formed thereon, a positive electrode plain part and a negative electrode plain part are respectively located at the upper end and the lower end of the electrode assembly, a current collector plate is coupled to the positive electrode plain part and the negative electrode plain part, and the current collector plate is connected to an electrode terminal.

[0550] When the cylindrical battery is formed in the tabless structure as described above, compared with the conventional battery provided with an electrode tab, current concentration is reduced, so that heat generation inside the battery can be effectively reduced, and thus the thermal stability of the battery can be improved.

[0551] Hereinafter, the present invention will be described in more detail with specific examples.

[0552] <Example 1> Average particle diameter D 50 having a unimodal particle size distribution with an average particle diameter of 3 μm and being in the form of single particles, the positive electrode active material Li[Ni 0.9 Co 0.06 Mn 0.03 Al 0.01 O2, carbon nanotubes, and a PVDF binder were mixed in N-methylpyrrolidone at a weight ratio of 97.8:0.6:1.6 to produce a positive electrode slurry. After applying the positive electrode slurry to one surface of an aluminum current collector sheet, it was dried at 120°C and then rolled to produce a positive electrode.

[0553] A negative electrode active material (a graphite:SiO = 95:5 (weight ratio) mixture), a conductive material (super C), styrene-butadiene rubber (SBR), and carboxymethyl cellulose (CMC) were mixed in water at a weight ratio of 96:2:1.5:0.5 to produce a negative electrode slurry. After applying the negative electrode slurry to one surface of a copper current collector sheet, it was dried at 150°C and then rolled to produce a negative electrode.

[0554] After a separator was interposed between the produced positive electrode and negative electrode and laminated in the order of separator / positive electrode / separator / negative electrode, it was wound up to produce a jelly roll type electrode assembly. After inserting the electrode assembly produced as described above into a cylindrical battery can, an electrolytic solution was injected to produce a 4680 cell.

[0555] <Comparative Example 1> As the positive electrode active material, a bimodal particle size distribution with a large particle size average particle diameter D 50 being 9 μm and a small particle size average particle diameter D 50 being 4 μm, and being in the form of secondary particles, Li[Ni 0.9Co 0.05 Mn 0.04 Al 0.01 A 4680 cell was manufactured in the same manner as in Example 1, except that O2 was used.

[0556] <Experimental Example 1> A hot box test was performed on the 4680 cells manufactured according to Example 1 and Comparative Example 1.

[0557] Specifically, the 4680 cells manufactured according to Example 1 and Comparative Example 1 were each placed in a hot box chamber at room temperature, heated to 130 °C at a heating rate of 5 °C / min, and then maintained for 30 minutes for a hot box evaluation, and the temperature change of the battery over time was measured. For accurate evaluation, the cells of Example 1 were subjected to two hot box evaluations. The measurement results are shown in FIGS. 45a and 45b.

[0558] FIG. 45a is a graph showing the results of the hot box test for the 4680 cells manufactured according to Example 1, and FIG. 45b is a graph showing the results of the hot box test for the 4680 cells manufactured according to Comparative Example 1.

[0559] From FIGS. 45a and 45b, in the case of the lithium secondary battery of Example 1 using the single-particle form of the positive electrode active material, the voltage and temperature of the battery were stably maintained until 65 minutes had elapsed, while it was confirmed that the battery temperature of the lithium secondary battery of Comparative Example 1 increased rapidly after 35 minutes.

[0560] <Example 2-1> Having a unimodal particle size distribution with D min = 1.78 μm, D 50 = 4.23 μm, D max = 13.1 μm, and a positive electrode active material (composition: Li[Ni 0.9 Co 0.06 Mn 0.03 Al 0.01 O2) in which single particles and pseudo single particles are mixed was prepared. FIG. 44a shows an SEM photograph of the positive electrode active material used in Example 2-1.

[0561] The positive electrode active material, carbon nanotubes, and a PVDF binder were mixed in N-methylpyrrolidone at a weight ratio of 97.8:0.6:1.6 to produce a positive electrode slurry. After applying the positive electrode slurry to one side of an aluminum current collector sheet, it was dried at 120 °C and then rolled to produce a positive electrode.

[0562] The negative electrode active material (a graphite:SiO = 95:5 (weight ratio) mixture), a conductive material (Super C), styrene-butadiene rubber (SBR), and carboxymethyl cellulose (CMC) were mixed in water at a weight ratio of 96:2:1.5:0.5 to produce a negative electrode slurry. After applying the negative electrode slurry to one side of a copper current collector sheet, it was dried at 150 °C and then rolled to produce a negative electrode.

[0563] After laminating a separator between the produced positive electrode and negative electrode in the order of separator / positive electrode / separator / negative electrode and then winding it up, a jelly roll-type electrode assembly was produced. After inserting the electrode assembly produced as described above into a battery can, an electrolytic solution was injected to produce a 4680 cell.

[0564] <Example 2-2> As the positive electrode active material, a positive electrode active material having a unimodal particle size distribution with D min = 1.38 μm, D 50 = 4.69 μm, D max = 18.5 μm and a mixture of single particles and pseudo single particles (composition: Li[Ni 0.9 Co 0.06 Mn 0.03 Al 0.01 O2) was used, and a 4680 cell was produced in the same manner as in Example 2-1 except for this. An SEM photograph of the positive electrode active material used in Example 2-2 is shown in Fig. 44b.

[0565] <Comparative Example 2-1> The positive electrode active material having a bimodal particle size distribution with a large particle size average particle size D 50 of 9 μm and a small particle size average particle size D 50 of 4 μm and in the form of secondary particles (composition: Li[Ni 0.9Co 0.05 Mn 0.04 Al 0.01 4680 cells were manufactured in the same manner as in Example 2-1, except that [[ID=]]O2) was used.

[0566] <Comparative Example 2-2> Having a unimodal particle size distribution and D min = 0.892 μm, D 50 = 3.02 μm, D max = 11 μm, and a positive electrode active material in which single particles and pseudo single particles are mixed (composition: Li[Ni 0.9 Co 0.06 Mn 0.03 Al 0.01 O2) was used. 4680 cells were manufactured in the same manner as in Example 2-1.

[0567] The SEM photograph of the positive electrode active material used in Comparative Example 2-2 was shown in Fig. 44c.

[0568] <Experimental Example 2-1> A hot box test was conducted on the 4680 cells manufactured according to Example 2-1, 2-2 and Comparative Example 2-1, 2-2.

[0569] Specifically, the 4680 cells manufactured according to Example 2-1 and Comparative Example 2-1 were respectively placed in a hot box chamber at room temperature, heated to 130 °C at a heating rate of 5 °C / min, maintained for 30 minutes, and then the temperature change of the battery was measured. When thermal runaway and ignition did not occur during the test, it was indicated as pass, and when thermal runaway and / or ignition occurred, it was indicated as fail. Also, for the accuracy of the test, the test was conducted on the cells of Example 2-1 and 2-2 more than twice.

[0570] The measurement results are shown in Table 1 below, Figure 45c, and Figure 45d. Figure 45c is a graph showing the results of a hot box test on Sample 1 of Example 2-1 and the 4680 cells manufactured by Comparative Example 2-1, and Figure 45d is a graph showing the results of a hot box test on Samples 2 and 3 of Example 2-1, Samples 1 and 2 of Example 2-2, and the 4680 cells manufactured by Comparative Example 2-2.

[0571]

Table 1

[0572] Referring to Table 1, Figure 45c, and Figure 45d, D min In the case of the 4680 cells of Example 2-1 to which a positive electrode active material in the form of single particles / pseudo single particles with D of 1.0 μm or more was applied, the voltage and temperature of the battery were stably maintained until 65 minutes elapsed. On the other hand, in Comparative Example 2-1 to which secondary particles were applied as the positive electrode active material and D min In the 4680 cells of Comparative Example 2-2 to which a positive electrode active material in the form of single particles / pseudo single particles with D of less than 1.0 μm was applied, it was confirmed that the battery temperature increased rapidly.

[0573] <Experimental Example 2-2> For the positive electrodes manufactured in Example 2-1 and Comparative Example 2-1, in order to confirm the degree of cracking of the positive electrode active material particles after rolling, the positive electrode was cut with an ion milling device, and then the cross-section was photographed with SEM. Figure 46a shows a cross-sectional SEM photograph of the positive electrode manufactured in Example 2-1, and Figure 46b shows a cross-sectional SEM photograph of the positive electrode manufactured in Comparative Example 2-1.

[0574] From Figures 46a and 46b, in the positive electrode of Example 2-1, there is almost no cracking of the positive electrode active material particles even after rolling, while in the positive electrode of Comparative Example 2-2 using secondary particles, a large number of cracks in the positive electrode active material particles are observed after rolling.

[0575] <Example 3-1> Having a unimodal particle size distribution and D min = 1.78 μm, D 50 = 4.23 μm, D max= 13.1 μm, and a positive electrode active material powder (composition: Li[Ni 0.9 Co 0.06 Mn 0.03 Al 0.01 O2), flaky graphite (SFG6L), a conductive material (multi-walled carbon nanotubes), and a PVDF binder were mixed in N-methylpyrrolidone at a weight ratio of 96.3:1.5:0.4:1.8 to produce a positive electrode slurry. The positive electrode slurry was applied to one side of an aluminum current collector sheet, dried, and rolled at a linear pressure of 3.0 ton / cm to produce a positive electrode. The porosity of the positive electrode active material layer of the produced positive electrode was measured. The porosity was 17.5%.

[0576] <Example 3-2> A positive electrode was produced in the same manner as in Example 3-1 except that the positive electrode active material, flaky graphite, the conductive material, and the binder were mixed at a weight ratio of 97.2:0.6:0.4:1.8, and the porosity of the positive electrode active material layer was measured. The porosity was 19%.

[0577] <Example 3-3> A positive electrode was produced in the same manner as in Example 3-1 except that the positive electrode active material, flaky graphite, the conductive material, and the binder were mixed at a weight ratio of 97.4:0.4:0.4:1.8, and the porosity of the positive electrode active material layer was measured. The porosity was 20%.

[0578] <Example 3-4> A positive electrode was produced in the same manner as in Example 3-1 except that the positive electrode active material, flaky graphite, the conductive material, and the binder were mixed at a weight ratio of 97.6:0.2:0.4:1.8, and the porosity of the positive electrode active material layer was measured. The porosity was 21%.

[0579] <Comparative Example 3-1> A positive electrode was produced in the same manner as in Example 3-1 except that no flaky graphite was added, and the positive electrode active material, the conductive material, and the binder were mixed in N-methylpyrrolidone at a weight ratio of 97.8:0.4:1.8 to produce a positive electrode slurry, and the porosity of the positive electrode active material layer was measured. The porosity was 24%.

[0580] <Comparative Example 3-2> A positive electrode slurry was produced by mixing a positive electrode active material, a conductive material, and a binder in a weight ratio of 97.8:0.4:1.8 in N-methylpyrrolidone without adding flaky graphite, and a positive electrode was produced in the same manner as in Example 3-1 except that it was rolled at a linear pressure of 2.0 ton / cm, and the porosity of the positive electrode active material layer was measured. The porosity was 30%.

[0581] <Experimental Example 3-1. Measurement of Charge and Discharge Capacity and Charge and Discharge Efficiency> Coin-type half cells including the positive electrodes according to Examples 3-1 to 3-4, Comparative Examples 3-1 and 3-2 were produced, charged to 4.25 V under a 0.2C current condition, and then discharged to 2.5 V under a 0.2C current condition, and the charge capacity (mAh / g) and discharge capacity (mAh / g) of each coin-type half cell were measured. The measurement results are shown in Table 2 below.

[0582]

Table 2

[0583] From Table 2, it can be confirmed that in the cases of Examples 3-1 to 3-4 using positive electrodes to which flaky graphite was added, lower porosity was shown compared to Comparative Examples 3-1 and 3-2, indicating excellent capacity characteristics.

[0584] <Experimental Example 3-2. Confirmation of Resistance Characteristics> While charging coin-type half cells including the positive electrodes according to Example 3-3, Comparative Example 3-1, and Comparative Example 3-2 to 4.2 V, the resistance characteristics according to the state of charge (SOC) were measured. The results of the experiment are shown in Fig. 47a.

[0585] Referring to Fig. 47a, it can be confirmed that based on SOC 10%, the resistance value of Example 3-3 in which flaky graphite was added to the positive electrode active material layer is lower than those of Comparative Example 3-1 and Comparative Example 3-2 that do not contain flaky graphite. This indicates that when adding flaky graphite to the positive electrode active material layer, there is an effect of improving the resistance characteristics at low SOC.

[0586] <Experimental Example 3-3. Measurement of High-Temperature Life Characteristics and Resistance Increase Rate> After a separator was interposed between the positive electrode and the negative electrode according to Example 3-1, Example 3-3, and Comparative Example 3-1, and they were laminated in the order of separator / positive electrode / separator / negative electrode and then wound up to manufacture a jelly roll type electrode assembly. After the manufactured electrode assembly was inserted into a cylindrical battery can, an electrolytic solution was injected to manufacture a 4680 cell.

[0587] At this time, for the negative electrode, a negative electrode active material (graphite:SiO = 95:5 (weight ratio) mixture), a conductive material (Super C), styrene-butadiene rubber (SBR), and carboxymethyl cellulose (CMC) were mixed in water at a weight ratio of 96:2:1.5:0.5 to manufacture a negative electrode slurry. Then, the negative electrode slurry was applied to one surface of a copper current collector sheet, dried at 150°C, and then rolled to manufacture it.

[0588] Regarding the 4680 cell manufactured in this way, charging it to 4.2 V at 0.5C at 40°C and then discharging it to 2.5 V at 0.5C was defined as one cycle, and after performing 50 cycles of charge and discharge, the capacity retention rate and the resistance (DCIR) increase rate were measured. The measurement results are shown in Fig. 47b.

[0589] Referring to Fig. 47b, in the case of the secondary batteries of Example 3-1 and 3-3, it can be seen that the change in the capacity retention rate according to the number of cycles is small, and the change in the resistance increase rate according to the number of cycles is also small, compared with the secondary battery of Comparative Example 3-1.

[0590] As described above, although the present invention has been described with reference to limited embodiments and drawings, the present invention is not limited thereto, and it goes without saying that various modifications and variations can be made within the equivalent scope of the technical idea and claims of the present invention by those having ordinary knowledge in the technical field to which the present invention pertains.

Explanation of Reference Numerals

[0591] 10 Positive electrode 10a Positive electrode plain part 11 Negative electrode 11a Negative electrode plain part 12 Separator 13 First electrode tab 14 Second electrode tab 20 Current collector 21 Active material layer 22 Plain part 23 Beading part 24 Crimping part 30 Current collecting plate 31 Current collecting plate 32 Plain part 33 Cavity 34 Peripheral region 35 Insulating gasket 35a Gasket exposed part 35b Gasket insertion part 36 First current collecting plate 37 Insulator 38 Second current collecting plate 38a Sub-plate 38b Outer end part 39 Sealing gasket 40 Cap plate 41 Bending part 43a Upper plain part 43b Lower plain part 50 External terminal 50a Terminal exposed part 50b Terminal insertion part 60a Electrode 60b Electrode 60c Electrode 60d Electrode 60e Electrode 61 Current collector 62 Active material layer 63 Plain part 64 Insulating coating layer

Claims

1. An electrode assembly in which a first electrode, a second electrode, and a separation membrane interposed therebetween are wound around a winding shaft to define a core and an outer peripheral surface. The first electrode and the second electrode each include a first plain portion and a second plain portion on which an active material layer is not coated along the winding direction. At least one of the first plain portion and the second plain portion is itself defined as an electrode tab, and includes a core-side plain portion adjacent to the core of the electrode assembly, an outer peripheral-side plain portion adjacent to the outer peripheral surface of the electrode assembly, and an intermediate plain portion interposed between the core-side plain portion and the outer peripheral-side plain portion. At least one of the core-side plain portion and the outer peripheral-side plain portion has a relatively lower height in the winding shaft direction than the intermediate plain portion, an electrode assembly, A battery housing that houses the electrode assembly from an opening formed at the lower end and is electrically connected to the second plain portion, An external terminal that is electrically connected to the first plain portion and penetrates a closing portion of the battery housing located on the opposite side of the opening and is exposed to the outside of the battery housing, A cap plate that covers the opening of the battery housing, and The closing portion has the same polarity as the second electrode, and the external terminal has the same polarity as the first electrode, A cylindrical battery.

2. An electrode assembly in which a first electrode, a second electrode, and a separation membrane interposed therebetween are wound around a winding shaft to define a core and an outer peripheral surface. The first electrode and the second electrode each include a first plain portion and a second plain portion on which an active material layer is not coated along the winding direction. At least one of the first plain portion and the second plain portion is itself defined as an electrode tab, and includes a core-side plain portion adjacent to the core of the electrode assembly, an outer peripheral-side plain portion adjacent to the outer peripheral surface of the electrode assembly, and an intermediate plain portion interposed between the core-side plain portion and the outer peripheral-side plain portion. At least one of the core-side plain portion and the outer peripheral-side plain portion has a relatively lower height in the winding shaft direction than the intermediate plain portion, an electrode assembly, A battery housing that houses the electrode assembly from an opening formed at the lower end and is electrically connected to the second plain portion, An external terminal that is electrically connected to the first plain portion and penetrates a closing portion of the battery housing located on the opposite side of the opening and is exposed to the outside of the battery housing, A cap plate that covers the opening of the battery housing, and The cap plate is insulated from the battery housing and has no polarity because it is not electrically connected to the electrode assembly, a cylindrical battery. **Claim 3**: An electrode assembly in which a first electrode, a second electrode, and a separator interposed therebetween are wound around a winding axis to define a core and an outer peripheral surface, wherein the first electrode and the second electrode each include a first non-coated portion and a second non-coated portion along the winding direction where the active material layer is not coated, and at least one of the first non-coated portion and the second non-coated portion is itself defined as an electrode tab, a core-side non-coated portion adjacent to the core of the electrode assembly, an outer peripheral-side non-coated portion adjacent to the outer peripheral surface of the electrode assembly, and an intermediate non-coated portion interposed between the core-side non-coated portion and the outer peripheral-side non-coated portion, and at least one of the core-side non-coated portion and the outer peripheral-side non-coated portion has a relatively lower height in the winding axis direction than the intermediate non-coated portion, an electrode assembly; A battery housing that houses the electrode assembly from an opening formed at the lower end and is electrically connected to the second non-coated portion; An external terminal that is electrically connected to the first non-coated portion and is exposed outside the battery housing through a closing portion of the battery housing located on the opposite side of the opening; A cap plate that covers the opening of the battery housing, and The surface of the external terminal exposed outside the battery housing is a first electrode terminal; A portion of the outer surface of the closing portion of the battery housing that is parallel to the upper surface of the first electrode terminal is a second electrode terminal, a cylindrical battery. **Claim 4** The external terminal is located at the center of the closing portion, the cylindrical battery according to claim 1.

5. An electrode assembly in which a first electrode, a second electrode, and a separation membrane interposed therebetween are wound around a winding axis to define a core and an outer peripheral surface, wherein the first electrode and the second electrode each include a first non-coated portion and a second non-coated portion along the winding direction where an active material layer is not coated, and at least one of the first non-coated portion and the second non-coated portion is itself defined as an electrode tab, including a core-side non-coated portion adjacent to the core of the electrode assembly, an outer peripheral-side non-coated portion adjacent to the outer peripheral surface of the electrode assembly, and an intermediate non-coated portion interposed between the core-side non-coated portion and the outer peripheral-side non-coated portion, and at least one of the core-side non-coated portion and the outer peripheral-side non-coated portion has a relatively lower height in the winding axis direction than the intermediate non-coated portion, an electrode assembly, a battery housing that houses the electrode assembly from an opening formed at the lower end and is electrically connected to the second non-coated portion, an external terminal that is electrically connected to the first non-coated portion and penetrates a closing portion of the battery housing located on the opposite side of the opening and is exposed to the outside of the battery housing, and a cap plate that covers the opening of the battery housing. The external terminal includes a terminal exposed portion extending outside the battery housing, and a terminal insertion portion penetrating the closing portion of the battery housing. A cross-section of the terminal exposed portion is larger than a cross-section of the terminal insertion portion. A peripheral edge of a lower end portion of the terminal insertion portion facing the electrode assembly is riveted toward an inner surface of the closing portion, a cylindrical battery.

6. An insulating gasket is provided between the battery housing and the external terminal on the closing portion side of the battery housing. A part of the insulating gasket interposed between a peripheral edge of a lower end portion of the terminal insertion portion and the battery housing is in close contact with the inner surface of the closing portion by the riveting. The cylindrical battery according to claim 5. **Claim 7**: An electrode assembly in which a first electrode, a second electrode, and a separation membrane interposed therebetween are wound around a winding axis to define a core and an outer peripheral surface, wherein the first electrode and the second electrode each include a first plain portion and a second plain portion along the winding direction, on which an active material layer is not coated, and at least one of the first plain portion and the second plain portion is itself defined as an electrode tab, and includes a core-side plain portion adjacent to the core of the electrode assembly, an outer peripheral-side plain portion adjacent to the outer peripheral surface of the electrode assembly, and an intermediate plain portion interposed between the core-side plain portion and the outer peripheral-side plain portion, and at least one of the core-side plain portion and the outer peripheral-side plain portion has a relatively lower height in the winding axis direction than the intermediate plain portion, an electrode assembly; A battery housing that houses the electrode assembly from an opening formed at a lower end and is electrically connected to the second plain portion; An external terminal that is electrically connected to the first plain portion and penetrates a closing portion of the battery housing located on the opposite side of the opening to be exposed outside the battery housing; A cap plate that covers the opening of the battery housing; A beading portion formed by pushing in around the outer peripheral surface of the battery housing adjacent to the opening of the battery housing; A crimping portion formed by bending an end portion on the opening side of the battery housing in the winding axis direction so as to wrap the periphery of the cap plate; A sealing gasket that is sandwiched between the opening of the battery housing and the cap plate and is crimped by the crimping portion to seal between the cap plate and the opening of the battery housing, a cylindrical battery. **Claim 8** The cylindrical battery according to claim 1, wherein at least a partial section of the intermediate plain portion includes a plurality of separately foldable segments. **Claim 9** The cylindrical battery according to claim 8, wherein at least one of the height in the winding axis direction and the width in the winding direction of the plurality of segments increases stepwise from the core side to the outer peripheral side individually or for each group. **Claim 10** The plurality of divided segments form a plurality of divided segment groups from the core side toward the outer peripheral side, and for the divided segments belonging to the same divided segment group, at least one of the width in the winding direction, the height in the winding axis direction, and the separation pitch in the winding direction is the same as each other. The cylindrical battery according to claim 8.

11. For the divided segments belonging to the same divided segment group, at least one of the width in the winding direction, the height in the winding axis direction, and the separation pitch in the winding direction increases stepwise from the core side toward the outer peripheral side. The cylindrical battery according to claim 10.

12. The plurality of divided segments are folded toward the core side and are overlapped multiple times along the winding axis direction. The cylindrical battery according to claim 8.

13. An electrode assembly in which a first electrode, a second electrode, and a separator interposed therebetween are wound around a winding axis to define a core and an outer peripheral surface, wherein the first electrode and the second electrode each include a first non-coated portion and a second non-coated portion along the winding direction where an active material layer is not coated, and at least one of the first non-coated portion and the second non-coated portion is itself defined as an electrode tab, including a core-side non-coated portion adjacent to the core of the electrode assembly, an outer peripheral-side non-coated portion adjacent to the outer peripheral surface of the electrode assembly, and an intermediate non-coated portion interposed between the core-side non-coated portion and the outer peripheral-side non-coated portion, and an electrode assembly in which at least one of the core-side non-coated portion and the outer peripheral-side non-coated portion has a relatively lower height in the winding axis direction than the intermediate non-coated portion, A battery housing that houses the electrode assembly from an opening formed at the lower end and is electrically connected to the second non-coated portion, An external terminal that is electrically connected to the first non-coated portion and penetrates a closing portion of the battery housing located on the opposite side of the opening and is exposed to the outside of the battery housing, And a cap plate that covers the opening of the battery housing. A cylindrical battery in which a radial length R of the core-side non-coated portion and a bent length H of the innermost divided segment of the intermediate non-coated portion satisfy the relational expression "H ≤ R".

14. A gap is provided between the lower end of the cutting line of the divided segment and the active material layer. The cylindrical battery according to claim 8.

15. The first non-coated portion is itself defined as an electrode tab, The first non-coated portion includes a core-side non-coated portion adjacent to the core of the electrode assembly, an outer-periphery-side non-coated portion adjacent to the outer peripheral surface of the electrode assembly, and an intermediate non-coated portion interposed between the core-side non-coated portion and the outer-periphery-side non-coated portion. The intermediate non-coated portion of the first non-coated portion includes a plurality of separately foldable segments. The cylindrical battery according to claim 1, wherein the plurality of segments of the first non-coated portion are bent toward the core side to form a folded surface of the segment at one end portion of the electrode assembly. **Claim 16**: An electrode assembly in which a first electrode, a second electrode, and a separator interposed therebetween are wound around a winding axis to define a core and an outer peripheral surface, wherein the first electrode and the second electrode each include a first non-coated portion and a second non-coated portion on which an active material layer is not coated along the winding direction, at least one of the first non-coated portion and the second non-coated portion is itself defined as an electrode tab, the electrode assembly includes a core-side non-coated portion adjacent to the core of the electrode assembly, an outer-periphery-side non-coated portion adjacent to the outer peripheral surface of the electrode assembly, and an intermediate non-coated portion interposed between the core-side non-coated portion and the outer-periphery-side non-coated portion, and at least one of the core-side non-coated portion and the outer-periphery-side non-coated portion has a relatively lower height in the winding axis direction than the intermediate non-coated portion; an electrode assembly A battery housing that houses the electrode assembly through an opening formed at a lower end and is electrically connected to the second non-coated portion; An external terminal that is electrically connected to the first non-coated portion and penetrates a closing portion of the battery housing located on the opposite side of the opening to be exposed outside the battery housing; A cap plate that covers the opening of the battery housing; and The first non-coated portion is itself defined as an electrode tab. The first non-coated portion includes a core-side non-coated portion adjacent to the core of the electrode assembly, an outer-periphery-side non-coated portion adjacent to the outer peripheral surface of the electrode assembly, and an intermediate non-coated portion interposed between the core-side non-coated portion and the outer-periphery-side non-coated portion. The intermediate non-coated portion of the first non-coated portion includes a plurality of separately foldable segments. The plurality of segments of the first non-coated portion are bent toward the core side to form a folded surface of the segment at one end portion of the electrode assembly. A first current collector plate coupled to the folded surface of the segment of the first non-coated portion; The battery further includes an insulator interposed between the first current collector plate and the inner surface of the closing portion. A cylindrical battery in which an end portion of the external terminal facing the electrode assembly is coupled to the first current collector through the insulator.

17. The second non-patterned portion is itself defined as an electrode tab, The second non-patterned portion includes a core-side non-patterned portion adjacent to the core of the electrode assembly, an outer peripheral-side non-patterned portion adjacent to the outer peripheral surface of the electrode assembly, and an intermediate non-patterned portion interposed between the core-side non-patterned portion and the outer peripheral-side non-patterned portion, The intermediate non-patterned portion of the second non-patterned portion includes a plurality of divided sections that can be independently bent, The cylindrical battery according to claim 7, wherein the plurality of divided sections of the second non-patterned portion form a bent surface of the divided section at the other end portion of the electrode assembly while being bent toward the core side.

18. Further including a second current collector coupled to the bent surface of the divided section of the second non-patterned portion, The cylindrical battery according to claim 17, wherein at least a part of the periphery of the second current collector extends toward the inner surface of the beading portion and is interposed and fixed between the inner surface of the beading portion and the sealing gasket.

19. The cylindrical battery according to claim 7, wherein the cap plate includes a bending portion formed of a region thinner than an adjacent region.

20. The cylindrical battery according to claim 1, wherein when the cylindrical battery is erected so that the cap plate faces the ground, a lower end portion of the cap plate is located above a lower end portion of the battery housing.

21. Including a first slide portion where the thickness of the active material layer decreases in a boundary region between the patterned portion and the non-patterned portion of the first electrode, Including a second slide portion where the thickness of the active material layer decreases in a boundary region between the patterned portion and the non-patterned portion of the second electrode, The cylindrical battery according to claim 1, wherein the first slide portion and the second slide portion are located in opposite directions in the winding axis direction.

22. The patterned portion of the first electrode includes a loading reduction portion where the loading amount of the active material decreases, The cylindrical battery according to claim 21, wherein the position of the loading reduction portion corresponds to the position of the second slide portion.

23. The active material layer of the first electrode includes a positive electrode active material including single particles, pseudo single particles, or a combination thereof, The minimum particle size D appearing in the volume cumulative distribution of the positive electrode active material ｍｉｎ is 1.0 μm or more, Particle size D when the volume accumulation amount is 50% in the volume accumulation distribution of the positive electrode active material ５０ is 5.0 μm or less, The maximum particle size D appearing in the volume cumulative distribution of the positive electrode active material ｍａｘ is 12 μm to 17 μm, and the cylindrical battery according to claim 1.

24. The positive electrode active material has a unimodal particle size distribution in which a single peak appears in a volume cumulative particle size distribution graph, and the following mathematical formula 1 【Mathematical formula 1】 Particle Size Distribution (PSD) = (D ｍａｘ - D ｍｉｎ ) / D ５０ The cylindrical battery according to claim 23, wherein the particle size distribution (PSD) represented by is 3 or less.

25. The single particle, pseudo single particle, or a combination thereof is included in an amount of 95 wt% to 100 wt% based on the total weight of the positive electrode active material contained in the active material layer of the first electrode. The cylindrical battery according to claim 23.

26. The positive electrode active material includes a lithium nickel-based oxide containing Ni in an amount of 80 mol% or more based on the total number of moles of transition metals. The cylindrical battery according to claim 23.

27. The porosity of the active material layer of the first electrode is 15% to 23%. The active material layer of the first electrode contains flaky graphite in a weight ratio of 0.05 wt% to 5 wt%. The cylindrical battery according to claim 23.

28. The active material layer of the first electrode further includes carbon nanotubes. The cylindrical battery according to claim 23.

29. The active material layer of the second electrode includes a silicon-based negative electrode active material and a carbon-based negative electrode active material. The silicon-based negative electrode active material and the carbon-based negative electrode active material are included in a weight ratio of 1:99 to 20:

80. The cylindrical battery according to claim 23.

30. A battery pack including a plurality of the cylindrical batteries according to any one of claims 1 to 29.

31. An automobile including the battery pack according to claim 30.

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