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

Abstract

A cylindrical battery according to one embodiment of the present invention includes an electrode assembly, a battery housing that receives the electrode assembly through an opening, a first current collecting plate that includes a support portion disposed on the electrode assembly, at least one first tab connecting portion extending from the support portion, and at least one housing connecting portion extending from an end of the first tab connecting portion and is positioned within the battery housing, a second current collecting plate that includes a peripheral portion disposed on the electrode assembly, a second tab connecting portion extending inward from the peripheral portion, and a terminal connecting portion positioned spaced apart from the second tab connecting portion, a cap plate configured to seal the opening, and a battery terminal that connects to the terminal connecting portion.

Description

Technical Field

[0001] The present invention relates to a cylindrical battery, a current collector plate applied thereto, a battery pack including such a cylindrical battery, and a vehicle.

[0002] More specifically, an embodiment of the present invention relates to a cylindrical battery having a structure in which force does not concentrate on a welded portion between components even when an external impact or vibration is applied during the use of the battery, a current collector plate applied thereto, a battery pack including the same, and a vehicle.

[0003] Also, an embodiment of the present invention relates to a positive electrode for an electrochemical element with improved electrochemical characteristics and an electrode assembly including the positive electrode.

[0004] This application claims priority based on Korean Patent Application No. 10-2021-0142188 filed on October 22, 2021, and all of the contents disclosed in the specification and drawings of the application are incorporated into this application.

Background Art

[0005] Secondary batteries with high applicability for each product group and having electrical characteristics such as high energy density are generally applied not only to portable devices but also to electric vehicles (EVs) and hybrid electric vehicles (HEVs) driven by an electric drive source.

[0006] Such secondary batteries not only have the primary advantage of significantly reducing the use of fossil fuels, but are also environmentally friendly in that no by-products are generated by the use of energy, and are attracting attention as a new energy source for improving energy efficiency.

[0007] Currently, secondary batteries such as lithium-ion batteries, lithium polymer batteries, nickel-cadmium batteries, nickel-metal hydride batteries, and nickel-zinc batteries are widely used. The operating voltage of such a single secondary battery cell is about 2.5V to 4.5V. 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 of batteries included in the battery pack and the electrical connection form can be variously set according to the required output voltage and / or charge and discharge capacity.

[0008] On the other hand, as types of secondary battery cells, cylindrical, prismatic, 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, and this is inserted together with an electrolyte into the inside of a battery housing to constitute a battery. Also, 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 outside. For reference, the positive electrode terminal is the cap plate of a sealing body that seals the opening of the battery housing, and the negative electrode terminal is the battery housing.

[0009] However, according to such a conventional cylindrical battery having such a structure, since 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.

[0010] In small cylindrical batteries having a form factor of 18650 or 21700, resistance and heat generation are not much of a problem. However, when increasing the form factor for applying the cylindrical battery to an electric vehicle, a problem may occur that the cylindrical battery catches fire while a large amount of heat is generated around the electrode tab during the rapid charging process.

[0011] In order to solve such problems, a cylindrical battery (so-called tab-less cylindrical battery) is proposed, which is designed such that a positive electrode non-coated portion and a negative electrode non-coated portion are respectively located at the upper end and the lower end of a jelly roll type electrode assembly, and a current collector plate is welded to such a non-coated portion to have a structure with improved current collection efficiency.

[0012] With reference to FIGS. 1 to 4, a conventional cylindrical battery will be described in more detail.

[0013] FIGS. 1 to 3 are diagrams showing the manufacturing process of a tab-less cylindrical battery. FIG. 1 shows the structure of an electrode, FIG. 2 shows the winding process of the electrode, and FIG. 3 shows the process in which a current collector plate is welded to the bent surface of the non-coated portion. FIG. 4 is a cross-sectional view of the tab-less cylindrical battery cut in the longitudinal direction (Y-axis).

[0014] Referring to FIGS. 1 to 4, the positive electrode 500 has a structure including a positive electrode active material portion 520 and a positive electrode non-coated portion 530 provided on one long side along the winding direction on a positive electrode sheet 500S. Further, the negative electrode 400 has a structure including a negative electrode active material portion 420 and a negative electrode non-coated portion 430 provided on one long side along the winding direction on a negative electrode sheet 400S. The electrode assembly 300 is manufactured by laminating the positive electrode 500 and the negative electrode 400 together with two separator membranes 600 in order as shown in FIG. 2 and then winding them in one direction (X-axis direction). At this time, the non-coated portion 530 of the positive electrode 500 and the non-coated portion 430 of the negative electrode 400 are arranged in opposite directions to each other.

[0015] After the winding process, the non-coated portion 530 of the positive electrode 500 and the non-coated portion 430 of the negative electrode 400 are bent toward the core side. Thereafter, the current collector plates 50 and 30 are welded and joined to the non-coated portions 530 and 430, respectively.

[0016] In the non-coated portion 530 of the positive electrode and the non-coated portion 430 of the negative electrode, no separate electrode tabs are connected. The current collector plates 50 and 30 are connected to external electrode terminals, and since the current path is formed with a large cross-sectional area along the winding axis direction of the electrode assembly 300 (refer to the arrow), 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.

[0017] However, when the form factor of the cylindrical battery increases and the charging current during rapid charging becomes large, the problem of heat generation occurs again even in the tabless cylindrical battery.

[0018] Specifically, as shown in FIG. 4, the conventional tabless cylindrical battery 1 includes a battery housing 20 and a sealing body A. The sealing body A includes a cap plate 40, a sealing gasket G1, and a connecting plate C1. The sealing gasket G1 is fixed by a crimping portion 22 while covering the periphery of the cap plate 40. Further, the electrode assembly 300 is fixed in the battery housing 20 by a beading portion 21 to prevent vertical movement.

[0019] Normally, the positive electrode terminal is the cap plate 40 of the sealing body A, and the negative electrode terminal is the battery housing 20. Therefore, the second current collector plate 50 connected to the non-coated portion 530 of the positive electrode 500 is electrically connected to the connecting plate C1 attached to the cap plate 40 through a strip-shaped lead L. Also, the first current collector plate 30 connected to the non-coated portion 430 of the negative electrode 400 is electrically connected to the bottom of the battery housing 20. The insulator S covers the second current collector plate 50 to prevent the battery housing 20 with a different polarity from coming into contact with the non-coated portion 530 of the positive electrode 500 and causing a short circuit.

[0020] When the second current collector 50 is connected to the connection plate C1, a strip-shaped lead L is used. The lead L is separately attached to the second current collector 50 or manufactured integrally with the second current collector 50. However, since the lead L is in the form of a thin strip, its cross-sectional area is small, and when a rapid charging current flows, a large amount of heat is generated. Further, the excessive heat generated in the lead L is transmitted to the electrode assembly 300 side and causes the separator 600 to contract, which may cause an internal short circuit, which is a main cause of thermal runaway.

[0021] The lead L also occupies a considerable installation space within the battery housing 20. Therefore, the cylindrical battery 1 including the lead L has low space efficiency and is limited in increasing the energy density.

[0022] Furthermore, in order to connect the conventional tabless cylindrical batteries 1 in series and / or in parallel, bus bar components must be connected to the cap plate 40 of the sealing body A and the bottom surface of the battery housing 20, resulting in a decrease in space efficiency. A battery pack mounted on an electric vehicle includes hundreds of cylindrical batteries 1. Therefore, the inefficiency of electrical wiring also causes considerable inconvenience during the assembly process of the electric vehicle and during the maintenance of the battery pack. Therefore, there is a need to develop a cylindrical battery having a structure in which the positive electrode terminal and the negative electrode terminal are applied in the same direction so as to simplify the electrical connection structure of a plurality of cylindrical batteries.

[0023] On the other hand, a conventional cylindrical battery generally has a structure in which a tab for connecting an electrode assembly and an external terminal is welded to a foil of the electrode assembly. However, in a cylindrical battery having such a structure, the current path is limited, and an excessive increase in the self-resistance of the electrode assembly cannot be avoided.

[0024] Therefore, a method of increasing the number of tabs for connecting the electrode assembly and the external terminal to reduce the resistance has been attempted. However, simply increasing the number of tabs in this way has limitations in reducing the resistance to a desired level and sufficiently ensuring the current path.

[0025] Therefore, due to the reduction of the self-resistance of the electrode assembly, it is necessary to develop a new structure of the electrode assembly and a structure of the current collector plate suitable for such a structure of the electrode assembly. In particular, such a new structure of the electrode assembly and the current collector plate is even more necessary in applications to devices that require high-output / high-capacity battery packs, such as electric vehicles.

[0026] In addition, it is also necessary to develop a cylindrical battery having a structure in which the bonding force between the current collector plate and the battery housing is maintained in an improved state, and a structure of the current collector plate applied to such a cylindrical battery.

[0027] Furthermore, when the current collector plate and the battery housing are coupled, a cylindrical battery is required that improves the energy density of the cylindrical battery by minimizing the dead space in the battery housing.

[0028] On the other hand, the application areas of batteries are very diverse. Among them, for example, battery packs applied to devices such as electric vehicles require large capacity and high output. Also, such a battery pack having a large capacity and high output may include, for example, cylindrical batteries as unit cells.

[0029] In the case of a cylindrical battery having large capacity and high output characteristics, in order to improve the current collection efficiency, electrode tabs are provided over the entire surfaces of both sides of the jelly roll, and current collector plates can be coupled to both surfaces of the jelly roll, respectively. By applying such a structure, the contact area between the electrode tab and the current collector plate can be maximized, and thereby the resistance generated at the connection site between components can be minimized.

[0030] As described above, when a cylindrical battery is applied to a device such as an automobile, external shocks and vibrations are frequently applied during use, which may damage the connection sites for the electrical connection between components. Such damage to the connection sites leads to product defects.

[0031] Also, even if the electrical connection is not completely interrupted due to damage to the coupling site for electrical connection, when the coupling area between components decreases due to damage to some welding sites, there is a risk of excessive heat due to increased resistance or internal short circuits due to component deformation.

[0032] Therefore, there is a need to develop a cylindrical battery having a structure in which force does not concentrate on the coupling site between components even when external impact and / or vibration is applied during use.

[0033] On the other hand, when manufacturing an electrode by applying a conventional positive electrode active material containing secondary particles, particle cracking occurs, and gas generation increases due to internal cracks generated during charge and discharge, which may lead to problems with battery stability.

[0034] To solve this problem, a positive electrode active material in the form of single particles or pseudo-single particles with a relatively large primary particle size has been developed. However, when applying the single particle or pseudo-single particle form of the positive electrode active material to a high loading electrode and rolling it, there is a problem that the electrode cracks before the porosity of the electrode reaches the target level, and the resistance characteristics and charge and discharge efficiency of the lithium secondary battery are not good.

Summary of the Invention

Problems to be Solved by the Invention

[0035] The present invention has been made in view of the above problems, and even when external impact and / or vibration is applied during the use of the battery, the impact and / or vibration is dispersed without concentrating on a specific site, thereby preventing damage to the coupling site between components. This is one object.

[0036] On the other hand, another object of the present invention is to ensure the safety in battery use by quickly interrupting the current when an overcurrent occurs due to a short circuit or the like by having the current collector plate itself perform a current interruption function without additionally providing a current interruption member.

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

[0038] On the other hand, the present invention has been made in view of the above-mentioned problems, and an object thereof is to provide a current collector having a structure suitable for an electrode assembly having a low-resistance structure, and a cylindrical battery including the same.

[0039] Another object of the present invention is to provide a current collector having a structure capable of significantly reducing the possibility of breakage at the welding site with the electrode assembly and / or the welding site with the battery housing even when vibration and impact are applied, and a cylindrical battery including the same.

[0040] Still another object of the present invention is to provide a current collector having a structure that can enhance the convenience of the welding process for the electrical connection between the battery housing and the current collector in the manufacture of a cylindrical battery, thereby improving productivity, and a cylindrical battery including the same.

[0041] However, the technical problems to be solved by the present invention are not limited to the above-mentioned problems, and other problems will be clearly understood by those skilled in the art from the following description of the invention.

[0042] On the other hand, the present invention has been made in view of the above-mentioned problems, and an object thereof is to provide an electrode for an electrochemical element and an electrode assembly for an electrochemical element 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.

[0043] Another object of the present invention is to provide an electrode assembly with improved energy density by applying a silicon-based negative electrode active material to the negative electrode.

[0044] Still 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.

[0045] Finally, an object of the present invention is to provide a cylindrical lithium secondary battery that can exhibit excellent thermal stability even when the volume increases.

[0046] Another object of the present invention is to provide an electrode having excellent thermal stability by applying single particles or pseudo single particles as a positive electrode active material, high electrical conductivity, and high rolling characteristics, and an electrode assembly including the same.

[0047] Another object of the present invention is to provide an electrode assembly with improved energy density by applying a silicon-based negative electrode active material to the negative electrode.

[0048] Another object of the present invention is to provide an electrode assembly in which the section of the positive electrode active material portion is increased without fear of lithium precipitation.

[0049] 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.

[0050] However, the technical problems to be solved by the present invention are not limited to the above-mentioned 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

[0051] To solve the above problems, a cylindrical battery according to one aspect of the present invention includes an electrode assembly including a first electrode tab and a second electrode tab, a battery housing that houses the electrode assembly and is electrically connected to the first electrode tab, a support portion disposed on one surface of the electrode assembly, at least one first tab coupling portion that extends from the support portion and is coupled to the first electrode tab, and at least one first housing coupling portion that extends from the support portion and is coupled to an inner surface of the battery housing, a first current collector plate located within the battery housing, a peripheral portion disposed on the other surface located on the opposite side of one surface of the electrode assembly, a second tab coupling portion that extends inward from the peripheral portion and is coupled to the second electrode tab, and a second current collector plate including a terminal coupling portion located apart from the second tab coupling portion, a cap plate configured to seal an opening portion of the battery housing, and a battery terminal electrically connected to the second electrode tab by being coupled to the terminal coupling portion.

[0052] The battery housing may include a beading portion formed at a peripheral portion adjacent to the opening portion and pushed inward.

[0053] The first housing coupling portion may be coupled on the beading portion of the battery housing.

[0054] The first housing coupling portion may include a first contact portion coupled to an inner surface of the battery housing and a first connecting portion connecting between the support portion and the first contact portion.

[0055] The first contact portion may have a form in which at least a part thereof extends along an inner circumferential surface of the battery housing.

[0056] The first connecting portion may include at least one first bent portion whose extending direction is changed.

[0057] The first current collector plate may further include a second housing coupling portion that extends from an end of the first tab coupling portion and is coupled to an inner surface of the battery housing.

[0058] The second housing coupling portion may include a second contact portion coupled to the inner surface of the battery housing, and a second connection portion connecting between the support portion and the second contact portion.

[0059] The second contact portion may have a form in which at least a part thereof extends along the inner circumferential surface of the battery housing.

[0060] The second connection portion may include at least one second bent portion whose extending direction is changed.

[0061] The peripheral portion may have a rim shape with a central portion being empty.

[0062] The second tab coupling portion and the terminal coupling portion may be electrically connected by the peripheral portion.

[0063] The terminal coupling portion may be located at the center of the inner space of the peripheral portion.

[0064] The second current collecting plate may further include a connecting portion extending inward from the peripheral portion and connected to the terminal coupling portion.

[0065] At least a part of the connecting portion may be formed to have a width narrower than that of the second tab coupling portion.

[0066] The connecting portion may include a tapered portion whose width gradually narrows along the direction from the inner surface of the peripheral portion toward the terminal coupling portion.

[0067] A plurality of the second tab coupling portions may be provided.

[0068] The plurality of second tab coupling portions may be arranged at the same intervals along the extending direction of the peripheral portion.

[0069] The extending length of each of the plurality of second tab coupling portions may be formed to be the same.

[0070] The terminal connection part may be arranged so as to be surrounded by a plurality of the second tab connection parts.

[0071] The connecting part is located between a pair of adjacent second tab connection parts, and the distance from the connecting part to one of the pair of second tab connection parts along the extending direction of the peripheral edge part may be the same as the distance from the connecting part to the other of the pair of second tab connection parts along the extending direction of the peripheral edge part.

[0072] A plurality of the connecting parts may be provided.

[0073] Each of the plurality of connecting parts may be arranged between a pair of adjacent second tab connection parts.

[0074] The plurality of connecting parts may be arranged at the same intervals along the extending direction of the peripheral edge part.

[0075] The connecting part may include a notch formed by narrowing the width of the connecting part.

[0076] The connecting part includes a notch formed by narrowing the width of the connecting part, and the notch may be located closer to the tapered part than the terminal connection part.

[0077] The terminal connection part may be arranged at a position corresponding to a hole formed in the winding center part of the electrode assembly.

[0078] The second electrode tab may extend toward a closing part located on the opposite side of the opening part of the battery housing.

[0079] The second tab connection part may be connected to a bonding surface formed by bending the end part of the second electrode tab along a direction parallel to the second current collector plate.

[0080] The cap plate may be configured not to be connected to the electrode assembly and not to have a polarity.

[0081] The battery terminal may penetrate through a closed portion located on the opposite side of the open portion of the battery housing.

[0082] The cylindrical battery may further include an insulator interposed between the closed portion and the second current collector.

[0083] The battery terminal may pass through the insulator and be coupled to the terminal coupling portion of the second current collector.

[0084] The active material layer of the second electrode includes a positive electrode active material containing single particles, pseudo single particles, or a combination thereof, and the minimum particle size D min appearing in the volume cumulative distribution of the positive electrode active material is 1.0 μm or more, and the particle size D 50 when the volume cumulative amount is 50% in the volume cumulative distribution of the positive electrode active material is 5.0 μm or less, and the maximum particle size D max appearing in the volume cumulative distribution of the positive electrode active material may be 12 μm to 17 μm.

[0085] 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 may be 3 or less.

[0086] [Formula 1] Particle size distribution (PSD) = (D max - D min ) / D 50 The single particles, pseudo single particles, or a combination thereof may be 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 second electrode.

[0087] The positive electrode active material may include a lithium nickel-based oxide containing 80 mol% or more of Ni based on the total number of moles of transition metals.

[0088] The active material layer of the second electrode has a porosity of 15% to 23%, and the active material layer of the second electrode may contain flaky graphite in a weight ratio of 0.05 wt% to 5 wt%.

[0089] The active material layer of the second electrode may further contain carbon nanotubes (CNT).

[0090] The active material layer of the first electrode contains a silicon-based negative electrode active material and a carbon-based negative electrode active material, and the silicon-based negative electrode active material and the carbon-based negative electrode active material may be contained in a weight ratio of 1:99 to 20:80.

[0091] A battery pack according to another aspect of the present invention includes the cylindrical battery according to one aspect of the present invention described above.

[0092] An automobile according to still another aspect of the present invention includes the battery pack according to one aspect of the present invention described above.

Advantages of the Invention

[0093] According to one aspect of the present invention, even when external impact and / or vibration are applied during the use of the battery, the impact and / or vibration are dispersed without concentrating on a specific part, thereby preventing damage from occurring at the joint part between components.

[0094] Also, according to one aspect of the present invention, even without additionally providing a current interruption member, the current interruption function is achieved by the current collector plate itself, so that when an overcurrent occurs due to a short circuit or the like, the current is quickly interrupted to ensure the safety of battery use.

[0095] According to one aspect of the present invention, the resistance in the electrical connection between the electrode assembly and the battery housing can be significantly reduced.

[0096] Also, according to one aspect of the present invention, even when vibration and impact are applied during the use of the battery, the possibility of damage occurring at the welding part between the current collector plate and the electrode assembly and / or the welding part between the current collector plate and the battery housing can be significantly reduced.

[0097] Also, according to one aspect of the present invention, in the manufacture of a cylindrical battery, the convenience of the welding process for the electrical connection between the battery housing and the current collector plate can be enhanced, thereby improving productivity.

[0098] Also, according to one aspect of the present invention, D min By including a positive electrode active material powder with D 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 suppression of particle breakage after rolling and the improvement effect of thermal stability differ depending on the particle size of the positive electrode active material powder. In particular, when particles with a particle size of less than 1.0 μm are included in the positive electrode active material powder, as the linear pressure increases in the rolling process, particle cracking increases and thermal stability decreases, and sufficient thermal stability could not be ensured when applied to large cylindrical batteries. 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 improvement effect of thermal stability can be maximized.

[0099] Also, according to one aspect of the present invention, D 50 、D max 、and by including a positive electrode active material powder with an appropriately adjusted particle size distribution (PSD) in the positive electrode, the increase in resistance due to the application of single particles can be minimized, so excellent capacity characteristics and output characteristics can be realized.

[0100] 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 new CNT as a conductive material.

[0101] Also, according to one aspect of the present invention, since 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 electrode porosity to a target level. As a result, the stability, initial resistance characteristics, and charge-discharge efficiency of the cylindrical battery are improved.

[0102] 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.

[0103] Also, according to one aspect of the present invention, since the positive electrode contains 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.

[0104] Also, according to one aspect of the present invention, compared with a conventional battery having 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.

[0105] The effects of the present invention are not limited to the above-described effects, and other effects not mentioned will be clearly understood by those skilled in the art from the description of the invention described below.

[0106] The following drawings attached to this specification illustrate preferred 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 is not 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

[0108] 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 limited to their ordinary and dictionary meanings, and the inventors themselves interpret them in accordance with the meaning and concept corresponding to the technical idea of the present invention in accordance with the principle that they 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 merely the most preferred embodiments of the present invention and do not represent all of the technical ideas of the present invention, and thus there may be various equivalents and modifications that can replace them at the time of this application.

[0109] Also, for the purpose of assisting in the understanding of the invention, the attached drawings are not illustrated at 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.

[0110] The sizes and thicknesses of the illustrated components are arbitrarily shown for convenience of explanation, and the present invention is not necessarily limited by the illustration. In the drawings, the thicknesses are enlarged to clearly show many layers and regions. Also, in the drawings, for convenience of explanation, the thicknesses of some layers and regions are exaggerated.

[0111] Also, when a part such as a layer, film, region, or plate is “above” or “on the upper side of” 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 “directly above” another part, it means that there are no other parts in between. Also, being “above” or “on the upper side of” a reference part means being located above or below the reference part, and does not necessarily mean being located “above” or “on the upper side of” in the direction opposite to gravity.

[0112] Also, throughout the specification, when a part “includes” another component, it means that, unless otherwise specified, it may further include other components rather than excluding other components.

[0113] Also, throughout the specification, when referring to a “plan view,” it means the view when looking at the target part from above, and when referring to a “cross-sectional view,” it means the view when looking at the cross-section obtained by cutting the target part vertically from the side.

[0114] First, referring to FIG. 5, a cylindrical battery 1 according to an embodiment of the present invention includes an electrode assembly 300, a battery housing 20, a first current collector plate 30, a cap plate 40, and battery terminals 60. The cylindrical battery 1 may further include, among other things, a sealing gasket G1 and / or an insulating gasket G2 and / or a second current collector plate 50 and / or an insulator S.

[0115] The electrode assembly 300 includes a first electrode tab 11 and a second electrode tab 12. The electrode assembly 300 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 either a negative electrode or a positive electrode, and the second electrode corresponds to an electrode having a polarity opposite to that of the first electrode. More specifically, the electrode assembly 300 can be manufactured by winding a laminate formed by laminating at least once in order a first electrode, a separator, a second electrode, and a separator. That is, the electrode assembly 300 applied to the embodiment of the present invention can be a jelly roll type electrode assembly. Such a jelly roll type electrode assembly 300 can include a winding center hole H1 formed at a substantially central portion thereof and extending along the height direction (a direction parallel to the height direction of the cylindrical battery 1 shown in FIG. 5). On the other hand, a separator may be further provided on the outer peripheral surface of the electrode assembly 300 for insulation from the battery housing 20.

[0116] The first electrode includes a first current collector and a first electrode active material layer applied on one or both surfaces of the first current collector. On one end portion in the width direction (a direction parallel to the height direction of the cylindrical battery 1 shown in FIG. 5) of the first current collector, there is a plain portion where the first electrode active material is not applied. The plain portion of the first electrode has a form extending from one end portion to the other end portion along the longitudinal direction of the first electrode when the first electrode is in an expanded state. The plain portion of the first electrode functions as the first electrode tab 11 as described above. The first electrode tab 11 is provided at the upper portion in the height direction (a direction parallel to the height direction of the cylindrical battery 1 shown in FIG. 5) of the electrode assembly 300 housed in the battery housing 20. The first electrode tab 11 can be, for example, a negative electrode tab.

[0117] The second electrode includes a second current collector and a second electrode active material layer coated on one or both sides of the second current collector. At the other end of the second current collector in the width direction (the direction parallel to the height direction of the cylindrical battery 1 shown in FIG. 5), there is a plain portion where the second electrode active material is not coated. The plain portion of the second electrode has a form extending from one end to the other end along the longitudinal direction of the second electrode when the second electrode is in an expanded state. The plain portion of the second electrode functions as the second electrode tab 12 as described above. The second electrode tab 12 is provided at the lower part in the height direction of the electrode assembly 300 housed in the battery housing 20. The second electrode tab 12 can be, for example, a positive electrode tab.

[0118] That is, the first electrode tab 11 and the second electrode tab 12 extend and protrude in opposite directions along the height direction of the cylindrical battery 1.

[0119] However, the present invention is not limited by such a form of the electrode assembly 300.

[0120] The battery housing 20 is a substantially cylindrical container with an opening formed on one side, and is made of a conductive metal material. The side surface of the battery housing 20 and the lower surface (the lower side surface with reference to FIG. 5) located on the opposite side of the opening portion can be integrally formed. That is, the upper end of the battery housing 20 in its height direction is open, and the lower end can have a closed form. The lower surface of the battery housing 20 can have a substantially flat form. The battery housing 20 houses the electrode assembly 300 through the opening formed on one side in its height direction. The battery housing 20 can also house the electrolyte together through the opening portion. However, the present invention is not limited by such a form of the battery housing 20.

[0121] The battery housing 20 is electrically connected to the electrode assembly 300. The battery housing 20 is connected to the first electrode tab 11 of the electrode assembly 300. Therefore, the battery housing 20 has the same polarity as the first electrode tab 11 electrically.

[0122] The battery housing 20 may include a beading portion 21 formed at a peripheral portion adjacent to the opening portion and pushed inward. The battery housing 20 may be provided with a beading portion 21 formed at an upper end portion. The battery housing 20 may further include a crimping portion 22 formed above the beading portion 21. The beading portion 21 has a form in which the periphery of the outer peripheral surface of the battery housing 20 is pushed in at a predetermined depth. The beading portion 21 is formed above the electrode assembly 300. The inner diameter of the battery housing 20 in the region where the beading portion 21 is formed is formed smaller than the diameter of the electrode assembly 300.

[0123] The beading portion 21 provides a support surface on which the cap plate 40 is placed. Also, the beading portion 21 may provide a support surface on which at least a part of the periphery of the first current collector plate 30 described later is placed and coupled. That is, on the upper surface of the beading portion 21, at least a part of the periphery of the first current collector plate 30 according to an embodiment of the present invention and / or the periphery of the cap plate 40 according to an embodiment of the present invention may be placed. As shown in FIGS. 10 and 11, in order to stably support at least a part of the periphery of the first current collector plate 30 and / or the periphery of the cap plate 40, the upper surface of the beading portion 21 may have a form in which at least a part thereof extends along a direction substantially parallel to the lower surface of the battery housing 20, that is, along a direction substantially perpendicular to the side wall of the battery housing 20.

[0124] The crimping portion 22 is formed on the upper part of the beading portion 21. The crimping portion 22 has a form that extends and is bent so as to cover the periphery of the cap plate 40 disposed on the upper part of the beading portion 21. Due to the shape of the crimping portion 22 like this, the cap plate 40 is fixed on the beading portion 21. Of course, such a crimping portion 22 may be omitted, and the cap plate 40 may be fixed while covering the open portion of the battery housing 20 through another fixing structure.

[0125] However, the present invention does not exclude the case where the battery housing 20 does not include such a beading portion 21 and / or crimping portion 22. In one embodiment of the present invention, when the battery housing 20 does not include the beading portion 21 and / or crimping portion 22, the fixing of the electrode assembly 300 and / or the fixing of the cap plate 40 and / or the sealing of the battery housing 20 can be achieved, for example, through the additional application of components that can function as stoppers for the electrode assembly 300 and / or the additional application of structures on which the cap plate 40 can be placed and / or welding between the battery housing 20 and the cap plate 40.

[0126] The closed end of the battery housing 20, that is, the region constituting the upper surface, may have a thickness of about 0.5 mm to 1.0 mm, and more preferably may have a thickness of about 0.6 mm to 0.8 mm. The side wall portion constituting the outer peripheral surface of the battery housing 20 may have a thickness of about 0.3 mm to 0.8 mm, and more preferably may have a thickness of about 0.40 mm to 0.60 mm. According to one embodiment of the present invention, a plating layer may be formed on the battery housing 20. In this case, the plating layer may contain, for example, nickel (Ni). The thickness of the plating layer may be about 1.5 μm to 6.0 μm.

[0127] The thinner the battery housing 20 is, the larger the internal space becomes, thereby improving the energy density and enabling the production of the cylindrical battery 1 having a large capacity. On the other hand, the thicker the battery housing 20 is, the less likely there is a chain propagation of flame to adjacent cells in the explosion test, which is advantageous in terms of safety.

[0128] The thinner the plating layer is, the more vulnerable it is to corrosion, and the thicker the plating layer is, the more difficult the manufacturing process becomes or the higher the possibility of plating peeling is. Considering all such conditions, it is necessary to set the optimal thickness of the battery housing 20 and the optimal thickness of the plating layer. Further, considering all such conditions, it is necessary to control the thickness of the closing portion and the thickness of the side wall portion of the battery housing 20, respectively.

[0129] Hereinafter, with reference to FIGS. 5 to 9, the first current collector 30 according to an embodiment of the present invention will be described in detail.

[0130] First, referring to FIGS. 5 and 6, the first current collector 30 according to an embodiment of the present invention is housed inside the battery housing 20, electrically connected to the electrode assembly 300, and also electrically connected to the battery housing 20. That is, the first current collector 30 electrically connects between the electrode assembly 300 and the battery housing 20.

[0131] The first current collector 30 includes a support portion 31 disposed on one surface of the electrode assembly 300, a plurality of first tab coupling portions 32 extending from the support portion 31 and coupled to the first electrode tab 11, and a plurality of first housing coupling portions 33 extending from the support portion 31 and coupled to the inner surface of the battery housing 20. The first tab coupling portion 32 and the first housing coupling portion 33 are indirectly connected via the support portion 31 and are not directly connected. Therefore, when an external impact is applied to the cylindrical battery 1 according to the embodiment of the present invention, damage occurring at the coupling site between the first current collector 30 and the electrode assembly 300 and at the coupling site between the first current collector 30 and the battery housing 20 can be minimized.

[0132] The support portion 31 and the plurality of first tab coupling portions 32 are disposed on the upper portion of the electrode assembly 300, and are positioned below the beading portion 21 when the beading portion 21 is formed in the battery housing 20.

[0133] The support portion 31 includes a first current collector plate hole H2 formed at a position corresponding to the winding center hole H1 formed at a substantially central portion of the electrode assembly 300. The winding center hole H1 and the first current collector plate hole H2 communicating with each other can function as a passage for inserting a welding rod for welding the battery terminal 60 and the second current collector plate 50 or welding the battery terminal 60 and a lead tab (not shown) described later, or for irradiating a laser.

[0134] The plurality of first tab coupling portions 32 may have a form extending radially from the support portion 31 toward the side wall of the battery housing 20. The plurality of first tab coupling portions 32 may be spaced apart from each other along the circumference of the support portion 31. On the other hand, in order to ensure the coupling force and reduce the electrical resistance by increasing the coupling area between the first current collector plate 30 and the electrode assembly 300, not only the first tab coupling portions 32 but also the support portion 31 can be coupled to the first electrode tab 11. The end portion of the first electrode tab 11 may be formed in a form bent parallel to the first tab coupling portion 32. When the end portion of the first electrode tab 11 is formed in this way and coupled to the first tab coupling portion 32 in a state parallel to the first tab coupling portion 32, the coupling area is increased, the coupling force is improved, and the effect of reducing the electrical resistance is obtained. In addition, the overall height of the electrode assembly 300 is minimized, and the effect of improving the energy density is obtained.

[0135] The plurality of the first housing coupling portions 33 may be configured to extend from the support portion 31 of the first current collector plate 30 substantially radially toward the side wall of the battery housing 20. The plurality of the first housing coupling portions 33 may be spaced apart from each other along the circumference of the support portion 31. At least one first housing coupling portion 33 may be located between adjacent first tab coupling portions 32. The plurality of the first housing coupling portions 33 may be coupled to, for example, the beading portion 21 on the inner surface of the battery housing 20. The first housing coupling portion 33 may be particularly coupled to the upper surface of the beading portion 21. In the cylindrical battery 1 according to one embodiment of the present invention, when such a structure is applied, the first housing coupling portion 33 may be naturally placed on the beading portion 21 through the step of accommodating the electrode assembly 300 with the first current collector plate 30 coupled thereto in the battery housing 20. Accordingly, the welding process between the battery housing 20 and the first current collector plate 30 is facilitated. Further, the upper surface of the beading portion 21 extends in a direction substantially parallel to the lower surface of the battery housing 20, that is, in a direction substantially perpendicular to the side wall of the battery housing 20, and the first housing coupling portion 33 also extends in the same direction, so that the first housing coupling portion 33 can stably contact the beading portion 21. Further, since the first housing coupling portion 33 stably contacts the beading portion 21 in this way, welding between the two parts is smoothly performed, thereby improving the bonding force between the two parts and minimizing an increase in resistance at the bonding site.

[0136] Next, referring to FIGS. 7 to 11, the first housing coupling portion 33 includes a first contact portion 33a coupled to the inner surface of the battery housing 20 and a first connecting portion 33b connecting between the support portion 31 and the first contact portion 33a.

[0137] The first contact portion 33a is coupled to the inner surface of the battery housing 20. When the beading portion 21 is formed on the battery housing 20, the first contact portion 33a can be coupled onto the beading portion 21 as described above. In this case, as described above, for stable contact and coupling, the beading portion 21 and the first contact portion 33a may all have a form extending along a direction substantially parallel to the lower surface of the battery housing 20, that is, a direction substantially perpendicular to the side wall of the battery housing 20.

[0138] The first connecting portion 33b may include at least one first bending portion B1 whose extending direction is changed between the support portion 31 and the first contact portion 33a. That is, the first connecting portion 33b may have a structure similar to a spring or a bellows structure that can contract and extend within a certain range. Such a structure of the first connecting portion 33b allows the first contact portion 33a to be brought into close contact with the beading portion 21 during the process of accommodating the electrode assembly 300 to which the first current collector plate 30 is coupled into the battery housing 20 even when the height of the electrode assembly 300 varies within a certain range.

[0139] For example, the vertical distance (D) between the first contact portion 33a and the support portion 31 in a state where no external force is applied to the first current collector plate 30 and there is no deformation is preferably the same as the vertical distance between the upper surface of the beading portion 21 and the support portion 31 when the electrode assembly 300 to which the first current collector plate 30 is coupled is placed in the battery housing 20, or is formed to be even smaller within the extendable range of the first connecting portion 33b. When the first connecting portion 33b is configured to satisfy such conditions, when the electrode assembly 300 to which the first current collector plate 30 is coupled is placed in the battery housing 20, the first contact portion 33a is naturally brought into close contact with the beading portion 21.

[0140] Furthermore, the structure of the first connecting part 33b that can be contracted and extended like this can mitigate the impact caused by the movement of the electrode assembly 300 within a certain range even when vibrations and / or impacts occur during the use of the cylindrical battery 1 (see FIG. 5) and the electrode assembly 300 moves up and down. That is, the structure of the first connecting part 33b that can be contracted and extended can buffer so that impacts are not transmitted to the coupling part between the first contact part 33a and the battery housing 20 and the coupling part between the first tab coupling part 32 and the first electrode tab 11 (see FIGS. 5 to 9).

[0141] Next, referring to FIG. 12, a first current collector 30 according to another embodiment of the present invention is shown. The first current collector 30 according to another embodiment of the present invention is different only in the form of the first contact part 33a compared to the first current collector 30 (the first current collector described with reference to FIG. 6), and the structure of the first current collector 30 described above can be substantially applied in other respects.

[0142] Referring to FIGS. 5 and 12, the first contact part 33a may have a form in which at least a part thereof extends along the inner peripheral surface of the battery housing 20. In this case, in order to maximize the contact area, the first current collector 30 may be configured such that the sum of the extension lengths of the first contact parts 33a of the respective first housing coupling parts 33 is substantially the same as the inner circumference of the battery housing 20.

[0143] Next, referring to FIGS. 13 and 14 together with FIG. 5, a first current collector 30 according to still another embodiment of the present invention is shown. The first current collector 30 according to still another embodiment of the present invention is different only in that it further includes a second housing coupling part 34 compared to the first current collector 30 according to the above-described embodiment (the first current collector 30 described with reference to FIGS. 6 and 12), and the structure of the first current collector 30 described above can be substantially applied in other respects.

[0144] The second housing coupling portion 34 extends from the end of the first tab coupling portion 32 and is coupled to the inner surface of the battery housing 20. At least one end of the plurality of first tab coupling portions 32 is provided with such a second housing coupling portion 34. The second housing coupling portion 34 includes a second contact portion 34a coupled to the inner surface of the battery housing 20 and a second connecting portion 34b connecting between the support portion 31 and the second contact portion 34a.

[0145] The second contact portion 34a is coupled to the inner surface of the battery housing 20. When the beading portion 21 is formed on the battery housing 20, the second contact portion 34a can be coupled on the beading portion 21 in the same manner as the first contact portion 33a described above. In this case, as described above, for stable contact and coupling, the beading portion 21 and the second contact portion 34a may all have a form extending in a direction substantially parallel to the lower surface of the battery housing 20, that is, in a direction substantially perpendicular to the side wall of the battery housing 20.

[0146] On the other hand, although not shown, like the form of the first contact portion 33a shown in FIG. 12, the second contact portion 34a may also have a form in which at least a part thereof extends along the inner circumferential surface of the battery housing 20. In this case, in order to maximize the contact area between the first current collector plate 30 and the battery housing 20, the first current collector plate 30 may be configured such that the sum of the extending lengths of the second contact portions 34a of the respective second housing coupling portions 34 is substantially the same as the inner circumference of the battery housing 20.

[0147] The second connecting portion 34b may include at least one second bending portion B2 whose extending direction is changed between the first tab coupling portion 32 and the second contact portion 34a, similar to the first connecting portion 33b described above. By forming the second bending portion B2, the second connecting portion 34b has a structure capable of contracting and extending, and thus has the advantages and buffering effects in the assembling process of the cylindrical battery 1 as described above.

[0148] The drawings illustrate a case where one second bent portion B2 is provided, but the present invention is not limited thereby, and similar to the first connecting portion 33b described above with reference to FIGS. 8 and 9, a plurality of second bent portions B2 may be provided.

[0149] Referring to FIG. 5, the cap plate 40 covers the open portion formed on one side of the battery housing 20. When the battery housing 20 according to an embodiment of the present invention includes a beading portion 21, the cap plate 40 may be placed on the beading portion 21 formed on the battery housing 20. Further, when the battery housing 20 according to an embodiment of the present invention includes a crimping portion 22, the cap plate 40 may be fixed by the crimping portion 22. In this case, in order to improve the fixing force and the sealing performance of the battery housing 20, a sealing gasket G1 may be interposed between the battery housing 20 and the cap plate 40 and between the first current collector plate 30 and the cap plate 40. However, in the embodiment of the present invention, the cap plate 40 is not a component that functions as a current path. Therefore, if the battery housing 20 and the cap plate 40 are firmly fixed through fixing by welding or application of other components and the sealing performance of the open portion of the battery housing 20 is ensured, the application of the sealing gasket G1 is not essential.

[0150] The cap plate 40 may be made of, for example, a metal material in order to ensure rigidity. In the cylindrical battery 1 according to one form 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 20 and the battery terminal 60 described later. 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 300 and the battery housing 20, and its material does not necessarily need to be a conductive metal.

[0151] For example, when the sealing gasket G1 is applied, the sealing gasket G1 may be in a substantially ring shape that covers and wraps the cap plate 40. The sealing gasket G1 can simultaneously cover the upper surface, lower surface, and side surface of the cap plate 40. The radial length of the portion of the sealing gasket G1 that covers the lower surface of the cap plate 40 may be shorter than or the same as the radial length of the portion of the sealing gasket G1 that covers the upper surface of the cap plate 40. If the radial length of the portion of the sealing gasket G1 that covers the lower surface of the cap plate 40 is too long, the sealing gasket G1 may press against the first current collector plate 30 during the process of vertically compressing the battery housing 20, and there is a risk that the first current collector plate 30 or the battery housing 20 may be damaged. Therefore, it is necessary to keep the radial length of the portion of the sealing gasket G1 that covers the lower surface of the cap plate 40 at a certain level and make it smaller. For example, as shown in FIG. 5, the radial length of the portion of the sealing gasket G1 that covers the lower surface of the cap plate 40 may be formed to be smaller than the radial length of the portion of the sealing gasket G1 that covers the upper surface of the cap plate 40. Alternatively, the radial length of the portion of the sealing gasket G1 that covers the lower surface of the cap plate 40 may be the same as the radial length of the portion of the sealing gasket G1 that covers the upper surface of the cap plate 40.

[0152] On the one hand, the cap plate 40 may include a venting portion 41 formed to prevent an increase in internal pressure due to gas generated inside the battery housing 20. The venting portion 41 is formed in a part of the cap plate 40 and corresponds to a region that is structurally weaker than the peripheral region so as to be easily broken when pressure is applied. The venting portion 41 may be, for example, a region with a smaller thickness compared to the peripheral region. Therefore, if an abnormality occurs in the cylindrical battery 1 and the internal pressure of the battery housing 20 increases above a certain level, the venting portion 41 breaks and the gas generated inside the battery housing 20 is discharged. The venting portion 41 may be formed, for example, by notching on one or both surfaces of the cap plate 40 to partially reduce the thickness of the battery housing 20.

[0153] The battery terminal 60 is electrically connected to the second electrode tab 12. The battery terminal 60 can penetrate the battery housing 20 from the side opposite to the open portion of the battery housing 20 and be electrically connected to the second electrode tab 12 of the electrode assembly 300. The battery terminal 60 may include a terminal exposed portion 60a and a terminal insertion portion 60b. The terminal exposed portion 60a is exposed outside the closed surface of the battery housing 20. The terminal exposed portion 60a may be located at substantially the center of the closed surface of the battery housing 20. The maximum diameter of the terminal exposed portion 60a may be formed larger than the maximum diameter of the through hole formed in the battery housing 20. The terminal insertion portion 60b can penetrate substantially the center of the closed surface of the battery housing 20 and be electrically connected to the second electrode tab 12. The terminal insertion portion 60b can be rivet-bonded to the inner surface of the battery housing 20. That is, the end portion of the terminal insertion portion 60b may have a form bent toward the inner surface of the battery housing 20. The maximum diameter of the end portion of the terminal insertion portion 60b may be larger than the maximum diameter of the through hole of the battery housing 20. A part of the battery terminal 60 may be exposed outside the battery housing 20, and the remaining part may be located inside the battery housing 20. The battery terminal 60 can be electrically connected to the electrode assembly 300 by being coupled to, for example, a second current collector plate 50 coupled to the second electrode tab 12 described later, or by being coupled to a lead tab (not shown) coupled to the second electrode tab 12. The inner surface of the terminal insertion portion 60b can be welded to the second current collector plate 50 connected to the second electrode tab 12. An insulator S described later may be interposed between the second current collector plate 50 and the inner surface of the battery housing 20.

[0154] When considering the polarity and function of such a battery terminal 60, the battery terminal 60 must maintain an insulated state from the battery housing 20 having the opposite polarity. Therefore, an insulating gasket G2 can be applied between the battery terminal 60 and the battery housing 20. Different from this, insulation may be achieved by coating a part of the surface of the battery terminal 60 with an insulating substance. Or, the battery terminal 60 and the battery housing 20 may be arranged so as not to be in contact with each other and spaced apart, and a method of structurally and firmly fixing the battery terminal 60 may be applied. Or, a combination of a plurality of the above-described methods may be applied.

[0155] That is, the cylindrical battery 1 according to one embodiment of the present invention has a structure in which a pair of electrode terminals (battery terminal 60, first electrode terminal T1) are located in the same direction. Therefore, when a plurality of cylindrical batteries 1 are electrically connected, electrical connection components such as a bus bar 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 the energy density. Further, the cylindrical battery 1 has a structure in which one surface of the battery housing 20 having a substantially flat form can be used as the first electrode terminal T1, so that a sufficient bonding area can be ensured when bonding an electrical connection component such as a bus bar to the first electrode terminal T1. Thereby, the cylindrical battery 1 can ensure sufficient bonding strength between the electrical connection component and the first electrode terminal T1, and can reduce the resistance at the bonding portion to a preferable level.

[0156] On one hand, when an insulating gasket G2 is applied for electrical insulation and riveting is applied for fixing the battery terminal 60, the insulating gasket G2 can be deformed together and bent toward the inner surface of the upper end closing portion of the battery housing 20 when the battery terminal 60 is riveted. When the insulating gasket G2 is made of a resin material, the insulating gasket G2 can be coupled to the battery housing 20 and the battery terminal 60 by heat fusion. In this case, the airtightness at the coupling interface between the insulating gasket G2 and the battery terminal 60 and at the coupling interface between the insulating gasket G2 and the battery housing 20 is enhanced.

[0157] In one embodiment of the present invention, the entire surface of the battery housing 20 can function as the first electrode terminal T1. For example, when the first electrode tab 11 is a negative electrode tab, the first electrode terminal T1 can be a negative electrode terminal. The cylindrical battery 1 according to the embodiment of the present invention uses the battery terminal 60 exposed on the lower surface located on the opposite side of the open portion of the battery housing 20 as the second electrode terminal T2, and uses the other regions of the lower surface of the battery housing 20 excluding the region occupied by the battery terminal 60 as the first electrode terminal T1. Therefore, when connecting a plurality of cylindrical batteries 1 electrically, the cylindrical battery 1 according to the embodiment of the present invention can connect all the positive / negative electrodes in one direction and simplify the electrical connection structure. In addition, the cylindrical battery 1 according to the embodiment of the present invention has a structure in which most of the lower surface located on the opposite side of the open portion of the battery housing 20 can be used as an electrode terminal, so that it has the advantage of being able to secure a sufficient area for welding parts for electrical connection.

[0158] On the one hand, in one embodiment of the present invention, the entire surface of the battery housing 20 can function as the first electrode terminal T1. When the first electrode tab 11 is a negative electrode tab, the first electrode terminal T1 can be a negative electrode terminal. The cylindrical battery 1 according to the embodiment of the present invention uses the battery terminal 60 exposed on the lower surface located on the opposite side of the open portion of the battery housing 20 as the second electrode terminal T2, and uses the other regions of the lower surface of the battery housing 20 excluding the region occupied by the battery terminal 60 as the first electrode terminal T1. Therefore, when electrically connecting a plurality of cylindrical batteries 1, the cylindrical battery 1 according to the embodiment of the present invention can connect all the positive / negative electrodes in one direction, and the electrical connection structure can be simplified. In addition, the cylindrical battery 1 according to the embodiment of the present invention has a structure in which most of the lower surface located on the opposite side of the open portion of the battery housing 20 can be used as an electrode terminal, so that it has the advantage of being able to secure a sufficient area for welding parts for electrical connection.

[0159] Referring to FIG. 15, the first current collector 30 according to the embodiment of the present invention may include at least one liquid injection hole H4. The liquid injection hole H4 may be provided, for example, in the first tab coupling portion 32. When a plurality of the first tab coupling portions 32 are provided, the liquid injection hole H4 may be provided in at least one of the first tab coupling portions 32. The liquid injection hole H4 may be provided on one side or both sides of at least one welding line W formed on the first tab coupling portion 32, for example. Referring to FIGS. 5 and 15, when manufacturing the cylindrical battery 1 according to an embodiment of the present invention, after accommodating the electrode assembly 300 and the combined body including the first current collector 30 in the battery housing 20, an electrolytic solution can be injected. At this time, the liquid injection property can be improved by the liquid injection hole H4.

[0160] Referring to FIG. 16, the first connecting portion 33b of the first housing coupling portion 33 and / or the second connecting portion 34b of the second housing coupling portion 34 of one embodiment of the present invention may have a once-bent form, but may have a form bent in a direction different from FIGS. 7 and 14. That is, the first bending portion B1 formed in the first connecting portion 33b and / or the second bending portion B2 formed in the second connecting portion 34b may have a form protruding in a direction toward the central portion of the cylindrical battery 1 (see FIG. 5). Such a bending direction of the first connecting portion 33b and / or the second connecting portion 34b is for preventing the bonding site between the first current collector plate 30 and the electrode assembly 300 and / or the bonding site between the first current collector plate 30 and the battery housing 20 from being damaged during the sizing process. Sizing is a compression process in the manufacture of the cylindrical battery 1 in which the height occupied by the beading portion 21 region of the battery housing 20 is reduced to decrease the overall height of the cylindrical battery 1. As a result of checking the degree of damage to the welded portion after the sizing process by changing the formation of the first bending portion B1 and the second bending portion B2 and the protruding directions of the first bending portion B1 and the second bending portion B2, it was confirmed that almost no damage occurred in the cylindrical battery 1 having a structure in which the first bending portion B1 and the second bending portion B2 protruded toward the central portion of the cylindrical battery 1.

[0161] Hereinafter, with reference to FIGS. 17 to 30, the above-described cylindrical battery 1 will be described more specifically. In the following description, there may be other embodiments that can be selectively applied in the description of the same components as the above-described description. Also, in the following description, there may be descriptions that partially overlap with the above-described description.

[0162] Referring to FIGS. 17 and 18, a cylindrical battery 1 according to an embodiment of the present invention includes an electrode assembly 300, a battery housing 20, a cap plate 40, a second current collector plate 50, and battery terminals 60. The cylindrical battery 1 may further include a sealing gasket G1 and / or an insulating gasket G2 and / or an insulator S and / or a first current collector plate 30 in addition to the above-described components.

[0163] The electrode assembly 300 includes a first electrode tab 11 and a second electrode tab 12. The second electrode tab 12 may be provided at an upper portion in the height direction (Z-axis direction) of the electrode assembly 300 housed in the battery housing 20. The first electrode tab 11 may be provided at a lower portion in the height direction (Z-axis direction) of the electrode assembly 300 housed in the battery housing 20.

[0164] The second electrode tab 12 and the first electrode tab 11 may extend in opposite directions along the width direction of the electrode assembly 300, that is, the height direction (Z-axis direction) of the cylindrical battery 1. The second electrode tab 12 may extend toward the closed portion of the battery housing 20, and the first electrode tab 11 may extend toward the open portion of the battery housing 20.

[0165] The battery housing 20 is a substantially cylindrical container having an open portion formed at the lower side, and is made of a conductive material such as metal. An open portion may be formed at the lower end in the height direction of the battery housing 20, and a closed portion may be formed at the upper end. The battery housing 20 houses the electrode assembly 300 through the open portion formed at the lower side, and may also house the electrolyte together. Referring to FIGS. 19 and 28, the battery housing 20 may include a beading portion 21 and a crimping portion 22 formed at its lower end. The beading portion 21 may be located at the lower portion of the electrode assembly 300. The beading portion 21 is formed by pushing in around the outer peripheral surface of the battery housing 20. The beading portion 21 can function as a support portion on which the cap plate 40 is placed so that the electrode assembly 300 having a size substantially corresponding to the width of the battery housing 20 does not come out from the open portion formed at the lower end of the battery housing 20.

[0166] The crimping portion 22 may be formed at a lower portion of the beading portion 21. The crimping portion 22 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 21 and a part of the lower surface of the cap plate 40.

[0167] Referring to FIGS. 18 and 27, the cap plate 40 can seal the open portion formed at the lower end of the battery housing 20. That is, the cap plate 40 can form the lower surface of the cylindrical battery 1.

[0168] 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 will be described later, so the structure of the upper part is more complex than that of the lower part. Therefore, in order to smoothly discharge the gas generated inside the battery housing 20, a venting portion 41 can be formed on the cap plate 40 constituting the lower surface of the cylindrical battery 1. As shown in FIG. 27, the lower end portion of the cap plate 40 is preferably disposed above the lower end portion of the battery housing 20. In this case, even if the lower end portion of the battery housing 20 contacts the ground or the bottom surface of the housing for the configuration of the module or pack, the cap plate 40 does not contact the ground or the bottom surface of the housing for the configuration of the module or pack. 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 breakage smoothness of the venting portion 41.

[0169] On the other hand, when the venting portion 41 has a closed loop form as shown in FIGS. 27 and 28, it is more advantageous in terms of ease of breakage that the distance from the center portion of the cap plate 40 to the venting portion 41 is farther. This is because when the same venting pressure acts, the farther the distance from the center portion of the cap plate 40 to the venting portion 41, the greater the force acting on the venting portion 41 and the easier it is to break. Also, in terms of the smoothness of discharging the venting gas, it is more advantageous that the distance from the center portion of the cap plate 40 to the venting portion 41 is farther. From such a viewpoint, it is advantageous that the venting portion 41 is formed along the periphery of a substantially flat region protruding downward (downward with reference to FIG. 17) from the peripheral region of the cap plate 40.

[0170] FIG. 28 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 thereto. 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.

[0171] Referring to FIGS. 18 to 20, the second current collector plate 50 is coupled to the upper portion of the electrode assembly 300. The second current collector plate 50 is made of a conductive metal material and is connected to the second electrode tab 12.

[0172] Referring to FIG. 20, the second current collector plate 50 can be coupled to a bonding surface formed by bending the end portion of the second electrode tab 12 in a direction parallel to the second current collector plate 50. The bending direction of the second electrode tab 12 can be, for example, a direction toward the winding center hole H1 of the electrode assembly 300. When the second electrode tab 12 has such a bent form, the space occupied by the second electrode tab 12 can be reduced to improve the energy density. Further, due to the increase in the bonding area between the second electrode tab 12 and the second current collector plate 50, the effects of improving the bonding force and reducing the resistance can be achieved.

[0173] Referring to FIGS. 18 to 20 together with FIGS. 21 to 24, the second current collector plate 50 includes a peripheral portion 51, a second tab coupling portion 52, and a terminal coupling portion 53. The peripheral portion 51 can be in a substantially rim form with a space E formed in the central portion. Only the case where the peripheral portion 51 is in a substantially circular rim form is shown in the drawings, but the present invention is not limited thereto. The peripheral portion 51 may be in a substantially square rim form or other forms different from the illustration.

[0174] The second tab coupling portion 52 extends inward from the peripheral portion 51 and is coupled to the first electrode tab 11. The terminal coupling portion 53 is located inside the peripheral portion 51, separated from the second tab coupling portion 52. The terminal coupling portion 53 can be coupled to the battery terminal 60 by welding. The terminal coupling portion 53 can be located, for example, at the center of the inner space of the peripheral portion 51. The terminal coupling portion 53 can be disposed at a position corresponding to a hole formed in the winding center hole H1 of the electrode assembly 300.

[0175] The second tab coupling portion 52 and the terminal coupling portion 53 are not directly connected, but are spaced apart and electrically connected by the peripheral portion 51. Thus, the second current collector plate 50 according to an embodiment of the present invention has a structure in which the second tab coupling portion 52 and the terminal coupling portion 53 are not directly connected but are connected through the peripheral portion 51. When an impact and / or vibration occurs in the cylindrical battery 1, the impact applied to the coupling site between the second tab coupling portion 52 and the second electrode tab 12 and the coupling site between the terminal coupling portion 53 and the battery terminal 60 can be dispersed. Therefore, the second current collector plate 50 according to the embodiment of the present invention can minimize or prevent damage to the welding site due to an external impact. The second current collector plate 50 according to the embodiment of the present invention has a structure in which stress is concentrated at the connection site between the peripheral portion 51 and the terminal coupling portion 53 when an external impact is applied. However, since such a connection site is not a site where a welding portion for coupling between parts is formed, it is possible to prevent product defects from occurring due to damage to the welding portion by an external impact.

[0176] The second current collector plate 50 may further include a connecting portion 54 that extends inward from the peripheral portion 51 and is connected to the terminal coupling portion 53. At least a part of the connecting portion 54 may be formed to have a narrower width than the second tab coupling portion 52. In this case, when the electrical resistance increases at the connecting portion 54 and current flows through the connecting portion 54, a larger resistance is generated compared to other parts, so that a part of the connecting portion 54 can be broken to cut off the overcurrent when the overcurrent occurs. The width of the connecting portion 54 can be adjusted to an appropriate level in consideration of such an overcurrent cutoff function.

[0177] The connecting portion 54 may include a tapered portion 54a whose width gradually narrows from the inner surface of the peripheral portion 51 toward the terminal connecting portion 53. When the tapered portion 54a is provided, the rigidity of the component is improved at the connecting portion between the connecting portion 54 and the peripheral portion 51.

[0178] A plurality of the second tab connecting portions 52 may be provided. The plurality of second tab connecting portions 52 may be arranged at the same intervals along the extending direction of the peripheral portion 51. The extending lengths of the respective second tab connecting portions 52 may be the same as each other. The terminal connecting portion 53 may be arranged so as to be surrounded by the plurality of second tab connecting portions 52. The connecting portion 54 may be located between a pair of adjacent second tab connecting portions 52. In this case, the distance from the connecting portion 54 to one of the pair of second tab connecting portions 52 along the extending direction of the peripheral portion 51 may be the same as the distance from the connecting portion 54 to the other of the pair of second tab connecting portions 52 along the extending direction of the peripheral portion 51.

[0179] A plurality of the connecting portions 54 may be provided. The plurality of connecting portions 54 may be respectively arranged between a pair of adjacent second tab connecting portions 52. The plurality of connecting portions 54 may be arranged at equal intervals along the extending direction of the peripheral portion 51.

[0180] As described above, when a plurality of second tab connecting portions 52 and / or connecting portions 54 are provided, if the distances between the second tab connecting portions 52 and / or the distances between the connecting portions 54 and / or the distances between the second tab connecting portions 52 and the connecting portions 54 are formed to be constant, the flow of current from the second tab connecting portion 52 to the connecting portion 54 or from the connecting portion 54 to the second tab connecting portion 52 is smoothly formed.

[0181] Referring to FIGS. 25 and 26, the connecting portion 54 may include a notch N formed by partially narrowing the width of the connecting portion 54. When the notch N is provided, the electrical resistance in the region where the notch N is formed increases, so that rapid current interruption is possible when an overcurrent occurs.

[0182] When the connecting portion 54 includes a tapered portion 54a, the notch N may be located closer to the tapered portion 54a than to the terminal connection portion 53. In this case, the notch N is located adjacent to the region with a large amount of heat generation due to the structure of the tapered portion 54a whose width gradually narrows, enabling even faster overcurrent interruption.

[0183] Referring to FIGS. 17 to 19 and FIG. 21, the battery terminal 60 is made of a conductive metal material and is coupled to the terminal connection portion 53 of the second current collector plate 50. The battery terminal 60 may be configured to penetrate a closed portion located on the opposite side of the open portion of the battery housing 20. When the cylindrical battery 1 according to an embodiment of the present invention includes an insulator S, the battery terminal 60 is configured to pass through the insulator S and be coupled to the terminal connection portion 53 of the second current collector plate 50.

[0184] As described above, the battery terminal 60 is electrically connected to the second electrode tab 12 of the electrode assembly 300 through the second current collector plate 50, and thus has a second polarity. Therefore, the battery terminal 60 can function as the second electrode terminal of the cylindrical battery 1 according to an embodiment of the present invention. Further, in the cylindrical battery 1 according to one embodiment of the present invention, a substantially flat surface formed on the closed portion side of the battery housing 20 having a first polarity can function as the first electrode terminal T1. Referring to FIG. 17, a bus bar U is connected to each of the second electrode terminal T2 and the first electrode terminal T1 of the cylindrical battery 1 according to an embodiment of the present invention. In each of the second electrode terminal T2 and the first electrode terminal T1, in order to ensure a sufficient bonding area for bonding with the bus bar U, the width D1 of the region of the second electrode terminal T2 exposed outside the battery housing 20 may be set to about 10% to 60% with respect to the width D2 of the first electrode terminal T1, that is, the upper surface of the battery housing 20.

[0185] Referring to FIGS. 18, 19, and 21, the insulator S can be provided between the second current collector 50 and the inner surface of the battery housing 20. The insulator S prevents contact between the second current collector 50 and the battery housing 20. The insulator S covers the upper surface of the second current collector 50 and the peripheral portion of the upper end of the electrode assembly 300. Thereby, it is possible to prevent the non-patterned portion on the outer peripheral side of the electrode assembly 300 from contacting the inner surface of the battery housing 20 having the opposite polarity and causing a short circuit. The insulator S can also be interposed between the upper end of the outer peripheral surface of the electrode assembly 300 and the inner surface of the battery housing 20. This is to prevent contact between the second electrode tab 12 extending toward the closing portion of the battery housing 20 and the inner peripheral surface of the battery housing 20.

[0186] When the cylindrical battery 1 according to an embodiment of the present invention includes the insulator S, the battery terminal 60 passes through the insulator S and is coupled to the second current collector 50. In order to allow the battery terminal 60 to pass through in this way, the insulator S may be provided with an opening formed at a position corresponding to the terminal coupling portion 53 of the second current collector 50.

[0187] Referring to FIG. 17, the first current collector 30 can be coupled to the lower part of the electrode assembly 300. The first current collector 30 is made of a conductive metal material and is coupled to the first electrode tab 11. Further, the first current collector 30 is electrically connected to the battery housing 20. The peripheral region of the first current collector 30 can be interposed and fixed between the inner surface of the battery housing 20 and the sealing gasket G1. In this case, the first current collector 30 can be welded onto the mounting surface formed by the beading portion 21 of the battery housing 20.

[0188] Referring to FIG. 20, the first current collector 30 can be coupled to a bonding surface formed by bending the end of the first electrode tab 11 in a direction parallel to the first current collector 30. The bending direction of the first electrode tab 11 can be, for example, a direction toward the winding center hole H1 of the electrode assembly 300. When the first electrode tab 11 has such a bent form, the space occupied by the first electrode tab 11 can be reduced to improve the energy density. Also, the effect of improving the bonding force and reducing the resistance between the first electrode tab 11 and the first current collector 30 can be achieved.

[0189] Preferably, the cylindrical battery cell can be a cylindrical battery cell having a form factor ratio (defined as the ratio of the diameter of the cylindrical battery cell divided by the height, i.e., the ratio of the height (H) to the diameter (Φ)) greater than about 0.4.

[0190] 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 48750 battery, a 48110 battery, a 48800 battery, or a 46800 battery. In the numerical value indicating the form factor, the first two digits indicate the diameter of the battery, the next two digits indicate the height of the battery, and the last digit 0 indicates that the cross-section of the battery is circular.

[0191] 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 0.518.

[0192] The battery according to another embodiment can be a substantially cylindrical battery having a diameter of about 48 mm, a height of about 75 mm, and a form factor ratio of about 0.640.

[0193] Batteries according to yet other embodiments may be substantially cylindrical batteries, which may be cylindrical batteries having a diameter of about 48 mm, a height of about 110 mm, and a form factor ratio of about 0.518.

[0194] Batteries according to yet other embodiments may be substantially cylindrical batteries, which may be cylindrical batteries having a diameter of about 48 mm, a height of about 80 mm, and a form factor ratio of about 0.600.

[0195] Batteries according to yet other embodiments may be substantially cylindrical batteries, which may be cylindrical batteries having a diameter of about 46 mm, a height of about 80 mm, and a form factor ratio of about 0.575.

[0196] Conventionally, batteries having a form factor ratio of about 0.4 or less have been used. That is, conventionally, for example, 18650 batteries, 21700 batteries, etc. have been used. In the case of 18650 batteries, the diameter is about 18 mm, the height is about 65 mm, and the form factor ratio is about 0.277. In the case of 21700 batteries, the diameter is about 21 mm, the height is about 70 mm, and the form factor ratio is about 0.300.

[0197] Referring to FIG. 29, a battery pack 3 according to an embodiment of the present invention includes a cylindrical battery 1 according to an embodiment of the present invention as described above. For the sake of illustration, components such as bus bars, cooling units, and power terminals for electrical connection are not shown.

[0198] Referring to FIG. 30, an automobile 5 according to an embodiment of the present invention may 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 automobile 5 includes four-wheel vehicles and two-wheel vehicles. The automobile 5 operates by receiving power supply from a battery pack 3 according to an embodiment of the present invention.

[0199] Hereinafter, embodiments of the positive electrode active material used in the cylindrical battery according to an embodiment of the present invention will be described.

[0200] In the embodiment, the "primary particle" means a particle unit in which no grain boundary is present visually 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 size of the primary particles observed in the SEM or EBSD image.

[0201] 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.

[0202] 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.

[0203] In the present invention, "D min ", "D 50 " and "D max " are particle size values of the volume cumulative distribution of the positive electrode active material measured by the laser diffraction method. Specifically, D min is the minimum particle size in the volume cumulative distribution, 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 size of the primary particles. Further, when the positive electrode active material is a pseudo single particle, D 50 means the average particle size of the particles formed by aggregation of the primary particles.

[0204] The particle size value of the volume cumulative distribution can be measured, for example, after dispersing the positive electrode active material in a dispersion medium, introducing it into a commercially available laser diffraction particle size analyzer (e.g., MT3000 manufactured by Microtrac), irradiating it with ultrasonic waves of about 28 kHz at an output of 60 W, and then obtaining a volume cumulative particle size distribution graph.

[0205] In the present invention, "consisting essentially of A" means including component A and any components not mentioned that do 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 occurrence of internal cracks. A person of ordinary skill in the art can recognize the material effects of such characteristics.

[0206] As a result of repeated research to develop a positive electrode for an electrochemical element and an electrochemical element including the same, which are excellent in safety while achieving a high capacity, the inventors have confirmed that when a positive electrode active material in the form of single particles composed of one primary particle or aggregates of 10 or fewer primary particles is used alone as the positive electrode active material, the safety of a large cylindrical battery can be remarkably improved.

[0207] According to one form, 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.

[0208] The positive electrode may have a structure in which a positive electrode active material layer is formed on at least one surface 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.

[0209] Specifically, the positive electrode can be manufactured by applying a positive electrode slurry, which is prepared 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, and after removing the solvent of the positive electrode slurry through a drying process, rolling it. On the other hand, when applying the positive electrode slurry, a positive electrode including a plain part (non-coated part) can be manufactured by a method of not applying the positive electrode slurry to a partial area of the positive electrode current collector, for example, one end of the positive electrode current collector.

[0210] In other forms, the positive electrode active material includes single-particle-based active material particles. In one embodiment, the single-particle-based active material particles can 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 can be composed only of the single-particle-based active material particles.

[0211] In this specification, the single-particle-based active material particles refer to those including all single particles, pseudo-single particles, or both. 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.

[0212] Conventionally, as the positive electrode active material of a lithium battery, spherical secondary particles aggregated from dozens to hundreds of primary particles are generally used. However, in the case of a positive electrode active material in the form of secondary particles in which many primary particles are aggregated like this, primary particles are likely to fall off and particle cracking is likely to occur in the rolling process during positive electrode manufacturing, 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, since the contact area with the electrolyte increases, there is a problem that gas generation due to side reactions with the electrolyte increases. If gas generation increases inside a cylindrical battery, there is a risk that the internal pressure of the battery increases and the battery explodes. In particular, when increasing the volume of a cylindrical battery, the amount of active material inside the battery increases due to the volume increase, and thereby the amount of gas generation also increases significantly, so the risk of ignition and / or explosion of the battery becomes even greater.

[0213] On the one hand, single-particle active material particles in the form of single particles composed of one primary particle or pseudo-single particles formed by aggregation of 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. In addition, 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 thus the generation of cracks inside the particles is also significantly reduced.

[0214] Therefore, when using single-particle active material particles as in one embodiment of the present invention, the amount of gas generated due to particle cracking and internal crack generation can be significantly reduced. As a result, excellent safety can be achieved when applied to large cylindrical batteries.

[0215] On the other hand, the single particles and / or pseudo-single particles are preferably contained in an amount of 95 wt% to 100 wt%, preferably 98 wt% to 100 wt%, more preferably 99 wt% to 100 wt%, and still more preferably 100 wt% based on the weight of the total positive electrode active material contained in the positive electrode.

[0216] When the content of single particles and / or pseudo-single particles satisfies the above range, sufficient safety can be obtained when applied to large batteries. When the positive electrode active material in the form of secondary particles 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 electrode manufacturing and charge and discharge, and the effect of suppressing gas generation decreases. As a result, the effect of improving stability when applied to large batteries decreases.

[0217] On the one hand, the positive electrode active material containing single particles and / or pseudo-single particles according to one 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. The D of the positive electrode active material minIf it is less than 1.0 μm, the linear 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 can be ensured when applied to a large cylindrical battery.

[0218] On the other hand, considering the resistance and output characteristics, the D of the positive electrode active material min can be 3 μm or less, 2.5 μm or less, or 2 μm or less. If D min is too large, the lithium ion diffusion distance inside the particles may increase, leading to a decrease in resistance and output characteristics.

[0219] For example, the D of the positive electrode active material min can be 1.0 μm to 3 μm, 1.0 μm to 2.5 μm, or 1.3 μm to 2.0 μm.

[0220] 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 for example, can be 0.5 μm to 5 μm, preferably 1 μm to 5 μm, more preferably 2 μm to 5 μm.

[0221] The positive electrode active material in the form of single particles and / or pseudo-single particles has a problem that the mobility of lithium ions is lower than that of the positive electrode active material in the form of secondary particles because there are few interfaces between the primary particles that serve as diffusion paths of 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 the D of the positive electrode active material 50 to 5 μm or less, an increase in resistance can be suppressed by minimizing the lithium ion diffusion distance inside the particles of the positive electrode active material.

[0222] Also, the positive electrode active material can have a D max of 12 μm to 17 μm, preferably 12 μm to 16 μm, more preferably 12 μm to 15 μm. When the D of the positive electrode active material max satisfies the above range, the resistance characteristics and capacity characteristics are further excellent. The D of the positive electrode active material maxIf it is too large, it means that aggregation has occurred between single particles, and the lithium migration path inside the aggregated particles becomes long, resulting in a decrease in lithium mobility and thus an increase in resistance. On the other hand, for the positive electrode active material D max If it is too small, it means that excessive pulverization has occurred, and due to excessive pulverization, D min can be less than 1 μm, so there is a risk of inducing particle cracking during rolling and reducing thermal stability.

[0223] On the other hand, the positive electrode active material can have a particle size distribution (PSD) represented by the following mathematical formula 1 of 3 or less, preferably 2 - 3, more preferably 2.3 - 3.

[0224] [Mathematical formula 1] Particle size distribution (PSD) = (D max - D min ) / D 50 When the positive electrode active material has the above particle size distribution, the electrode density of the positive electrode can be appropriately maintained, and particle cracking and resistance increase can be effectively suppressed.

[0225] On the other hand, the positive electrode active material can have an average primary particle size of 5 μm or less, 4 μm or less, 3 μm or less, or 2 μm or less, for example, 0.5 μm - 5 μm, preferably 1 μm - 5 μm, more preferably 2 μm - 5 μm. When the average primary particle size 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 primary particle size 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 primary particle size is too large, the lithium diffusion path inside the primary particles becomes long, resulting in an increase in resistance and a decrease in output characteristics.

[0226] In one embodiment of the present invention, the positive electrode active material preferably 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 having a large average particle size and a small particle size positive electrode active material having 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, when the particle size increases, the lithium migration path becomes longer and the resistance increases significantly. Therefore, when large particle size particles are mixed and used, there is a possibility that the capacity and output characteristics may deteriorate. Therefore, in the present invention, by using a positive electrode active material having a unimodal distribution, an increase in resistance can be minimized.

[0227] On the other hand, the positive electrode active material may contain a lithium nickel-based oxide. 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. Preferably, the lithium nickel-based oxide may contain Ni in an amount of 80 mol% or more and less than 100 mol%, 82 mol% or more and less than 100 mol%, or 83 mol% or more and less than 100 mol%. When a lithium nickel-based oxide having a high Ni content as described above is used, a high capacity can be realized.

[0228] More specifically, the positive electrode active material may contain a lithium nickel-based oxide represented by the following Chemical Formula 1.

[0229] [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 preferably may be Mn, or Mn and Al.

[0230] The M 2is one or more selected from the group consisting of Zr, W, Y, Ba, Ca, Ti, Mg, Ta, and Nb, preferably one or more selected from the group consisting of Zr, Y, Mg, and Ti, and more preferably Zr, Y, or a combination thereof. M 2 The 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.

[0231] Said a represents the lithium molar ratio in the lithium nickel-based oxide, and can 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.

[0232] Said b represents the nickel molar ratio in the total metal excluding lithium in the lithium nickel-based oxide, and can 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 shown and a high capacity can be realized.

[0233] Said c represents the cobalt molar ratio 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 cobalt molar ratio satisfies the above range, good resistance characteristics and output characteristics can be realized.

[0234] Said d represents the molar ratio of the M 1 element in the total metal excluding lithium in the lithium nickel-based oxide, 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. M 1 When the molar ratio of the element satisfies the above range, the structure stability of the positive electrode active material is excellent.

[0235] In the lithium nickel-based oxide, M represents the molar ratio of elements in the total metal excluding lithium, and 0 ≤ e ≤ 0.1 or 0 ≤ e ≤ 0.05 may hold. 2 It represents the molar ratio of the element M in the total metal excluding lithium in the lithium nickel-based oxide, and 0 ≤ e ≤ 0.1 or 0 ≤ e ≤ 0.05 can be satisfied.

[0236] On the other hand, the positive electrode active material according to an embodiment of the present invention may further include 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 as needed. Preferably, the coating element may be Al, B, Co, or a combination thereof.

[0237] When a coating layer is present 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, thereby obtaining the effect of reducing the elution of transition metals or gas generation due to side reactions with the electrolyte.

[0238] 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.

[0239] 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 of the surface of aluminum or stainless steel with carbon, nickel, titanium, silver, etc. can be used. The positive electrode current collector usually may 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 adhesion 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 fabrics, etc.

[0240] On the one 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.

[0241] In the case of the single-particle active material particles, compared with the conventional secondary particle-shaped positive electrode active material, there is a problem that the resistance is high and the contact area with the conductive material is small, resulting in a decrease in electrical conductivity. If an excessive amount of conductive material is added to improve electrical conductivity, aggregation occurs in the positive electrode slurry and the viscosity increases, resulting in a problem of decreased coating property. Therefore, in order to achieve smooth coating property, 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 decreased 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.

[0242] In an embodiment of the present invention, when applying a positive electrode active material in which the surface of the single-particle active material particles is coated with a conductive nanomaterial, the positive electrode active material layer may not use a conductive material in the 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.

[0243] In one example of the present invention, the conductive nanomaterial may have a nano-size and be a material having conductivity so as to be smoothly coated on the particles, and its type is not particularly limited. For example, the conductive nanomaterial may be a carbon nanotube, a carbon nanoparticle, or the like.

[0244] The conductive nanomaterial can have various forms, for example, it can be spherical, flaky, or fibrous, etc.

[0245] On the other hand, the conductive coating layer can be formed by a method of heat-treating after mixing single-particle active material particles, which are the core part, and the conductive nanomaterial. At this time, the mixing can be performed by solid-phase mixing or liquid-phase mixing.

[0246] In one embodiment of the present invention, the positive electrode active material layer contains flaky graphite. When the single-particle active material is used as the positive electrode active material, if 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 have improved stability, initial resistance characteristics, and charge and discharge efficiency.

[0247] 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.

[0248] When the content of the flaky graphite satisfies the above range, the rolling characteristics of the positive electrode can be improved to achieve an excellent electrode density. If the content of the flaky graphite is small, the improvement effect of the rolling characteristics is low, and if it is excessive, it may induce an increase in the slurry viscosity and a decrease in the phase stability, resulting in a decrease in the electrode uniformity due to the combination with the conductive material and an increase in the resistance.

[0249] On the other hand, the flaky graphite used in the present invention can 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 there is a risk of reducing the current density and decreasing the capacity. At this time, the average particle size of the flaky graphite can be measured by the laser diffraction method (ISO 13320).

[0250] In addition, 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.

[0251] In addition, 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 such.

[0252] 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 increases and excellent capacity can be realized, and the resistance decreases. If the porosity is too low, the electrolyte impregnation property may decrease and lithium precipitation due to non-impregnation of the electrolyte may occur. 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.

[0253] The porosity 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.

[0254] 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 one 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.

[0255] Further, as in one embodiment of the present invention, when the positive electrode active material layer contains flaky graphite, 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.

[0256] Further, the positive electrode has a loading amount of 570 mg / 25 cm 2 or more, preferably 600 mg / 25 cm 2 ~800 g / 25 m 2 and more preferably 600 mg / 25 cm 2 ~750 mg / 25 cm 2 It can be. Specifically, in the case of a lithium secondary battery according to one embodiment of the present invention, the rolling characteristics of the electrode are improved by applying a positive electrode active material and flaky graphite in the form of single particles and / or pseudo-single particles. Therefore, the loading amount of the positive electrode can be secured at a relatively high level, and high-capacity characteristics can be realized thereby.

[0257] 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 electrical 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. Among these, one kind alone or a mixture of two or more kinds 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.

[0258] In a specific embodiment according to one embodiment of the present invention, the conductive material may contain carbon nanotubes.

[0259] 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 may be included at 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.

[0260] In one example of the present invention, the multi-walled carbon nanotubes are 300 m 2 / g to 500 m 2 / g and have a BET specific surface area. To distinguish this from the prior art, it is referred to as "novel CNT".

[0261] Conventionally, generally used carbon nanotubes (conventional CNTs) have a BET specific surface area of less than 300 m 2 / g. When comparing the scanning electron microscope images and physical properties of the novel CNT (Figure 31) and the conventional CNT (Figure 32) used in the present invention (Figure 33), it is as follows.

[0262] As can be seen from the SEM image, the novel CNT applied to one example of the present invention is of a bundled type and has a multi-wall structure, but has a higher BET than the conventional CNT and smaller number of layers and diameter.

[0263] When using a positive electrode active material in the form of secondary particles, sufficient electrical conductivity can be achieved even when using conventional CNTs at about 0.4 wt% to 0.6 wt%. However, in the case of a positive electrode active material in the form of single particles or pseudo-single particles, the resistance is higher than that of the conventional positive electrode 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.

[0264] Figs. 34 to 37 are graphs showing the surface resistance and high-temperature life characteristics according to the ratio of the conductive material when single particles or pseudo single particles are applied as the positive electrode active material.

[0265] From the graphs, it can be seen that when single particles or pseudo single particles are applied as the positive electrode active material, it is necessary to increase the amount of the conductive material compared to the case where the conventional secondary particle-shaped positive electrode active material is applied.

[0266] However, if the content of the carbon nanotubes increases to 0.9 wt% or more, aggregation occurs in the positive electrode slurry and the viscosity increases, thereby reducing the coatability. Therefore, in order to achieve smooth coatability, it is necessary to reduce the solid content in the positive electrode slurry to lower the viscosity of the positive electrode slurry. However, when the solid content in the positive electrode slurry decreases, there is a problem that the active material content decreases and the capacity characteristics deteriorate.

[0267] As a result of repeated studies to solve such problems, the inventors of the present invention, together with the positive electrode active material which is single particle-based active material particles, carbon nanotubes having a BET specific surface area of 300 m 2 / g to 500 m 2 / g are applied as the conductive material. It was confirmed that even with a relatively small amount of carbon nanotubes, sufficient electrical conductivity can be ensured, and thus the slurry viscosity can be maintained low even when the solid content of the positive electrode slurry is formed as high as about 70 wt% to 80 wt%.

[0268] 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 a small amount of carbon nanotubes.

[0269] Further, the carbon nanotube can be a multi-walled carbon nanotube having a wall number of 2 to 8, preferably 2 to 6, more preferably 3 to 6.

[0270] Further, the carbon nanotube can have a diameter of 1 nm to 8 nm, preferably 3 nm to 8 nm, more preferably 3 nm to 6 nm.

[0271] The carbon nanotube can 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 nanotube satisfies the above range, sufficient electrical conductivity can be realized, and the solid content in the positive electrode slurry can be maintained 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.

[0272] The table shown in FIG. 38 compares the solid content, viscosity, resistance value in the MP coating layer, and resistance value in the MP interface layer of the positive electrode slurry when a carbon nanotube (new CNT) having a BET specific surface area of 300 m 2 / g to 500 m 2 / g is applied and when a carbon nanotube (conventional CNT) having a BET specific surface area of 200 m 2 / g or more and less than 300 m 2 / g is applied. From the table, it can be confirmed that when the new CNT is applied, it shows a lower viscosity even when the solid content of the positive electrode slurry is higher than that of the conventional CNT, and also has excellent electrical conductivity.

[0273] The binder serves to improve the adhesion between the positive electrode active material particles and the adhesion 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 kind alone or a mixture of two or more kinds of these 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 positive electrode active material layer.

[0274] 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.

[0275] 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 structure. When a jelly - roll structure is formed, a separator may be further disposed on the outside to prevent contact between the negative electrode and the positive electrode.

[0276] 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.

[0277] Specifically, the negative electrode can be manufactured by applying a negative electrode slurry, which is 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., onto one or both surfaces of a long sheet-like 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 including a plain part 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 of the negative electrode current collector.

[0278] As the negative electrode active material, a compound capable of reversible insertion 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 composite, etc.; lithium metal thin film; metal materials capable of alloying with lithium such as Sn, Al, etc. Among these, any one or a mixture of two or more of them can be used.

[0279] In one embodiment of the present invention, the negative electrode may include a silicon-based negative electrode active material. The silicon-based negative electrode active material can 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), 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.

[0280] The silicon-based negative electrode active material can be doped with M b a metal, and at this time, the M bThe metal can be a Group 1 metal element or a Group 2 metal element, specifically, it can be Li, Mg, etc. Specifically, the silicon-based negative electrode active material is M b Si doped with metal, SiO y (where 0 < y < 2), it can be 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 depending on the doping element, it has high efficiency, so a high energy density can be realized.

[0281] FIG. 55 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.

[0282] In FIG. 55, low-efficiency SiO is undoped SiO, and ultra-high-efficiency SiO means Mg / Li-doped SiO. From FIG. 55, 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.

[0283] 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 can be formed through methods such as dry coating, wet coating, chemical vapor deposition (CVD), physical vapor deposition (PVD), atomic layer deposition (ALD).

[0284] 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 an initial efficiency of about 60 to 95%.

[0285] In another embodiment of the present invention, the D of the silicon-based negative electrode active material 50can be 3 μm to 8 μm, and D min ~D max can be included in the range of 0.5 μm to 30 μm.

[0286] The negative electrode may further contain a carbon-based negative electrode active material as a negative electrode active material as necessary. The carbon-based negative electrode active material can be, for example, artificial graphite, natural graphite, graphitized carbon fiber, amorphous carbon, soft carbon, hard carbon, etc., but is not limited thereto.

[0287] 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 can be 1:99 to 20:80, preferably 1:99 to 15:85, more preferably 1:99 to 10:90 in terms of weight ratio.

[0288] The negative electrode active material can 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.

[0289] As necessary, the negative electrode active material may further contain one or more selected from lithium metal and metal substances capable of alloying with lithium such as Sn and Al.

[0290] 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 bodies, etc.

[0291] The conductive material is used to impart conductivity to the negative electrode, and can be used without particular limitation as long as it has electrical conductivity without causing chemical changes inside the battery. Examples of specific conductive materials 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, 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 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.

[0292] The binder plays a role in improving the adhesion between the negative electrode active material particles and the adhesive force between the negative electrode active material and the negative electrode current collector. Examples of specific binders 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), fluororubber, or various copolymers thereof. 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 negative electrode active material layer.

[0293] The electrode assembly further includes a separator membrane, which is disposed within the electrode assembly in such a manner as to be interposed between the negative electrode and the positive electrode. The separator membrane separates the negative electrode from 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.

[0294] As the separator membrane, 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 laminate structure of two or more layers thereof can be used. Further, a normal porous nonwoven fabric, for example, a nonwoven fabric made of high melting point glass fibers, polyethylene terephthalate fibers, etc. may be used. Further, a coated separator membrane containing a ceramic component or a polymer substance may be used to ensure heat resistance or mechanical strength.

[0295] Still another embodiment of the present invention relates to a battery including the electrode assembly. The battery is one in which the electrode assembly and the electrolyte are housed together in a battery case. As the battery case, any appropriate 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.

[0296] As the electrolyte used in the present invention, various electrolytes that can be used in a lithium battery, for example, 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.

[0297] Specifically, the electrolyte may contain an organic solvent and a lithium salt.

[0298] As the organic solvent, any solvent 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 with 2 to 20 carbon atoms 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 preferred, and a mixture of a cyclic carbonate having a high ion conductivity and a high dielectric constant that can improve the charge and discharge performance of the battery (for example, ethylene carbonate or propylene carbonate) and a linear carbonate compound having a low viscosity (for example, ethyl methyl carbonate, dimethyl carbonate, or diethyl carbonate) is more preferred.

[0299] 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. When 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.

[0300] 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, as the additive, a haloalkylene carbonate-based compound such as difluoroethylene carbonate, pyridine, triethyl phosphite, triethanolamine, cyclic ether, ethylenediamine, n-glyme, hexamethylphosphoric triamide, nitrobenzene derivative, sulfur, quinoneimine dye, N-substituted oxazolidinone, N,N-substituted imidazolidine, ethylene glycol dialkyl ether, ammonium salt, pyrrole, 2-methoxyethanol, or aluminum trichloride can be used alone or in combination, but is 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.

[0301] In still another embodiment of the present invention, the positive electrode may include a loading reduction portion having a lower loading amount of the positive electrode active material than 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.

[0302] In recent years, in order to achieve a high energy density and reduce costs, 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 utilizing 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.

[0303] FIG. 43 is a diagram showing an electrode assembly according to an embodiment of the present invention, and FIG. 44 is a cross-sectional view taken along the line A-A' of FIG. 43.

[0304] Referring to FIGS. 43 and 44, 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, in order to prevent the negative electrode 400 and the positive electrode 500 from contacting each other, it is preferable that the separator 600 is further disposed on the outside.

[0305] 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 the negative electrode active material is not applied extends in the first direction d1 in the negative electrode current collector 410. The negative electrode blank portion 430 extends along one end portion of the wound negative electrode 400. Further, the negative electrode blank portion 430 extends longer than the separator 600 in the first direction d1. As a result, the negative electrode blank portion 430 may be exposed at one end portion of the jelly roll structure 300S in the first direction.

[0306] 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 the positive electrode active material is not applied extends in the second direction d2 in the positive electrode current collector 510. The positive electrode blank portion 530 extends along one end portion of the wound positive electrode 500. Further, the positive electrode blank portion 530 extends longer than the separator 600 in the second direction d2. As a result, the positive electrode blank portion 530 may be exposed at one end portion of the jelly roll structure 300S in the second direction.

[0307] 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.

[0308] The electrode assembly 300 according to the present embodiment does not have a form in which a separate electrode tab is attached, but instead utilizes the negative electrode blank portion 430 of the negative electrode current collector 410 and the positive electrode blank portion 530 of the positive electrode current collector 510 themselves as electrode tabs for reducing resistance.

[0309] Although not shown, the negative electrode blank portion 430 and / or the positive electrode blank portion 530 may substantially have the same structure as the blank portion of the electrode described above.

[0310] 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 toward the first direction d1 in the loading reduction portion 500D.

[0311] 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 can be 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 can be relatively thin.

[0312] 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 blank portion and the active material portion.

[0313] 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 negative electrode blank portion 430. The negative electrode boundary portion 420B may gradually decrease in loading amount toward the direction in which the negative electrode blank portion 430 is located.

[0314] 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.

[0315] The negative electrode boundary portion 420B and the positive electrode boundary portion 520B in which the loading amount gradually decreases in this way naturally occur 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.

[0316] 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 becomes 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.

[0317] 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 becomes 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.

[0318] 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.

[0319] By providing a loading reduction part 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 part 420B where the loading amount gradually decreases, it is possible to increase the section where the positive electrode active material is applied without worry of lithium precipitation. In particular, the loading reduction part 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 part 420B where the loading amount gradually decreases toward the negative electrode non-coated part 430. Therefore, the N / P ratio with respect to the negative electrode 400 and the positive electrode 500 in the region where the negative electrode boundary part 420B is formed can be maintained high, and precipitation of lithium can be prevented.

[0320] 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. 45 to 50.

[0321] FIGS. 45 and 46 are diagrams showing the process of manufacturing a negative electrode according to an embodiment of the present invention. Specifically, FIG. 45 is a top view of the negative electrode sheet, and FIG. 46 is a front view of the negative electrode sheet of FIG. 45.

[0322] Referring to FIGS. 45 and 46, 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 part 420 coated with a negative electrode active material and a negative electrode non-coated part 430 not coated with a negative electrode active material are alternately positioned on a negative electrode current collector 410.

[0323] Specifically, the negative electrode active material part 420 may 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 parts 420 can be separated and positioned along the fourth direction d4. That is, the coating process can be performed so that the negative electrode non-coated part 430 is positioned between the plurality of negative electrode active material parts 420.

[0324] 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.

[0325] Thereafter, a step of manufacturing the negative electrode 400 by slitting the negative electrode non-coated portion 430 and the negative electrode active material portion 420 may be included. FIG. 47 is a perspective view showing a negative electrode according to an embodiment of the present invention.

[0326] Referring to FIGS. 45 to 47, slitting can be performed in a direction parallel to the third direction d3 with respect to each of the negative electrode non-coated portion 430 and the negative electrode active material portion 420, as shown by the dotted lines in FIGS. 45 and 46. As a result, a plurality of negative electrodes 400 as shown in FIG. 47 can be manufactured from the negative electrode sheet 400S. That is, the negative electrode 400 in FIG. 47 corresponds to one of the plurality of negative electrodes manufactured by slitting the negative electrode sheet 400S in FIGS. 45 and 46. By slitting the negative electrode non-coated portion 430 and the negative electrode active material portion 420 in the negative electrode sheet 400S, a negative electrode 400 in which the negative electrode non-coated portion 430 extends to one side can be manufactured.

[0327] When forming the negative electrode active material portion 420, a slurry containing a 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 non-coated portion 430 is located may be formed at the boundary between the negative electrode active material portion 420 and the negative electrode non-coated portion 430.

[0328] FIGS. 48 and 49 are diagrams showing a process of manufacturing a positive electrode according to an embodiment of the present invention. Specifically, FIG. 48 is a top view of a positive electrode sheet, and FIG. 49 is a front view of the positive electrode sheet in FIG. 48.

[0329] Referring to FIGS. 48 and 49, 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 the positive electrode active material are alternately positioned on a positive electrode current collector 510.

[0330] Specifically, the positive electrode active material may be applied so as to extend in a third direction d3 to form the positive electrode active material portion 520. Further, 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.

[0331] 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.

[0332] 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. 50 is a perspective view showing the positive electrode 500 according to an embodiment of the present invention.

[0333] Referring to FIGS. 48 to 50, 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 line portions in FIGS. 48 and 49. Thereby, a plurality of positive electrodes 500 as shown in FIG. 50 can be manufactured from the positive electrode sheet 500S. That is, the positive electrode 500 in FIG. 50 corresponds to one of the plurality of positive electrodes manufactured by slitting the positive electrode sheet 500S in FIGS. 48 and 49. 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.

[0334] 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.

[0335] Referring to FIGS. 43, 47, and 50 together, a 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.

[0336] Referring further to FIGS. 48 to 50, 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 in which the loading amount of the positive electrode active material is less than that in an 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.

[0337] 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 an adjacent region in the jelly roll structure 300S shown in FIGS. 43 and 44.

[0338] 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. 49, 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.

[0339] 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.

[0340] Referring to FIG. 50, 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.

[0341] Referring to FIGS. 43 and 44, 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.

[0342] 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 in the first direction d1.

[0343] 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 respect 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 respect to the direction perpendicular to the first direction d1.

[0344] The corresponding positional relationship between the loading reduction portion 500D and the negative electrode boundary portion 420B is the same as the above description and will be omitted.

[0345] Hereinafter, an electrode assembly according to a comparative form of the present invention will be described with reference to FIGS. 51 to 54, and advantages of the electrode assembly according to the embodiment of the present invention over the electrode assembly according to the comparative form will be described.

[0346] FIG. 51 is a view showing an electrode assembly according to a comparative form of the present invention, and FIG. 52 is a cross-sectional view taken along line B-B' of FIG. 51.

[0347] Referring to FIGS. 51 and 52, 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.

[0348] 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.

[0349] FIG. 53 is a view showing a process of manufacturing the negative electrode 700 according to a comparative form of the present invention.

[0350] Referring to FIG. 53, 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 can be slit to manufacture a plurality of negative electrodes 700.

[0351] On the other hand, referring further to FIGS. 51 and 52, 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.

[0352] FIG. 54 is a diagram showing a process of manufacturing the positive electrode 800 according to a comparative form of the present invention.

[0353] Referring to FIG. 54, 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 can be slit to manufacture a plurality of positive electrodes 800.

[0354] Thereafter, the manufactured negative electrode 700 and positive electrode 800 can be wound together with the separator 900 to manufacture the electrode assembly 600 according to the comparative form of the present invention.

[0355] 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. 44).

[0356] Referring to FIGS. 51 and 52, 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 in 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 there is a high possibility that metallic lithium will 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, 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.

[0357] On the other hand, referring to FIGS. 43 and 44, 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 in 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 in the corresponding portion can be maintained high, and lithium precipitation 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.

[0358] Comparing the A1 region in FIGS. 43 and 44 with the B1 region in FIGS. 51 and 52, 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.

[0359] Still 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 for the electrolytic solution.

[0360] 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.

[0361] 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, a large amount of heat generation, and poor current collection efficiency.

[0362] In recent years, with the development of technologies related to electric vehicles, the demand for high-capacity batteries has been increasing, and 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 have a serious impact on 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.

[0363] 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 ignition or explosion of the battery. 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 but also has high safety.

[0364] 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.

[0365] 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.

[0366] 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.

[0367] The tabless structure battery may, for example, include a plain portion where the positive electrode and the negative electrode do not have an active material layer formed thereon, a positive electrode plain portion and a negative electrode plain portion 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 portion and the negative electrode plain portion, and the current collector plate is connected to an electrode terminal.

[0368] When a cylindrical battery is formed in the tabless structure as described above, current concentration is reduced compared to a conventional battery having an electrode tab, so that heat generation inside the battery can be effectively reduced, and thereby the thermal stability of the battery can be improved.

[0369] Hereinafter, the present invention will be described in more detail with specific examples.

[0370] <Example 1> Average particle size D 50 having a unimodal particle size distribution of 3 μm and being in a single particle form, the cathode 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 cathode slurry. After applying the cathode slurry to one surface of an aluminum current collector sheet, it was dried at 120 °C and then rolled to produce a cathode.

[0371] An anode 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 produce an anode slurry. After applying the anode slurry to one surface of a copper current collector sheet, it was dried at 150 °C and then rolled to produce an anode.

[0372] After laminating a separator between the produced cathode and anode in the order of separator / cathode / separator / anode and then winding it up, a jelly roll type electrode assembly was produced. After inserting the electrode assembly produced as described above into a cylindrical battery can, an electrolytic solution was injected to produce a 4680 cell.

[0373] <Comparative Example 1> As the cathode 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 being in a secondary particle form, 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

[0374] <Experimental Example 1> A hot box test was performed on the 4680 cells manufactured according to Example 1 and Comparative Example 1.

[0375] Specifically, the 4680 cells manufactured according to Example 1 and Comparative Example 1 were respectively 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. 40a and 40b.

[0376] FIG. 40a is a graph showing the results of the hot box test on the 4680 cells manufactured according to Example 1, and FIG. 40b is a graph showing the results of the hot box test on the 4680 cells manufactured according to Comparative Example 1.

[0377] From FIGS. 40a and 40b, in the case of the lithium secondary battery of Example 1 using the positive electrode active material in the single-particle form, the voltage and temperature of the battery were stably maintained until 65 minutes elapsed, while it was confirmed that the battery temperature of the lithium secondary battery of Comparative Example 1 increased rapidly after 35 minutes elapsed.

[0378] <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. 39a shows the SEM photograph of the positive electrode active material used in Example 2-1.

[0379] The positive electrode active material, carbon nanotubes, and a PVDF binder were mixed in a weight ratio of 97.8:0.6:1.6 in N-methylpyrrolidone 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.

[0380] The negative electrode active material (graphite:SiO = 95:5 (weight ratio) mixture), conductive material (Super C), styrene-butadiene rubber (SBR), and carboxymethyl cellulose (CMC) were mixed in a weight ratio of 96:2:1.5:0.5 in water 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.

[0381] 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.

[0382] <Example 2-2> As the positive electrode active material, except that 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 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, a 4680 cell was produced in the same manner as in Example 2-1. An SEM photograph of the positive electrode active material used in Example 2-2 is shown in Fig. 39b.

[0383] <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.

[0384] <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.

[0385] The SEM photograph of the positive electrode active material used in Comparative Example 2-2 is shown in FIG. 39c.

[0386] <Experimental Example 2-1> A hot box test was performed on the 4680 cells manufactured according to Example 2-1, 2-2 and Comparative Examples 2-1, 2-2.

[0387] 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 cells of Example 2-1 and 2-2, the test was performed two or more times for the accuracy of the test.

[0388] The measurement results are shown in Table 1 and FIGS. 40c and 40d below. FIG. 40c is a graph showing the results of a hot box test on the 4680 cells manufactured by Sample 1 of Example 2-1 and Comparative Example 2-1, and FIG. 40d is a graph showing the results of a hot box test on the 4680 cells manufactured by Sample 2 and 3 of Example 2-1, Sample 1 and 2 of Example 2-2, and Comparative Example 2-2.

[0389]

Table 1

[0390] Referring to Table 1, FIG. 40c and FIG. 40d, D min In the case of the 4680 cells of Example 2-1 to which the single-particle / pseudo single-particle form cathode active material with D being 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 cathode active material and Comparative Example 2-2 min in which the 4680 cells with the single-particle / pseudo single-particle form cathode active material with D being less than 1.0 μm were applied, it was confirmed that the battery temperature increased rapidly.

[0391] <Experimental Example 2-2> For the cathodes manufactured in Example 2-1 and Comparative Example 2-1, in order to confirm the degree of cracking of the cathode active material particles after rolling, the cathode was cut with an ion milling device and then the cross-section was photographed with SEM. FIG. 41a shows the cross-sectional SEM photograph of the cathode manufactured in Example 2-1, and FIG. 41b shows the cross-sectional SEM photograph of the cathode manufactured in Comparative Example 2-1.

[0392] From FIGS. 41a and 41b, there is almost no particle cracking of the cathode active material after rolling in the cathode of Example 2-1, while a large number of particle cracks of the cathode active material are observed after rolling in the cathode of Comparative Example 2-2 using secondary particles.

[0393] <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 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), flaky graphite (SFG6L), a conductive material (multi-walled carbon nanotube), 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. After applying the positive electrode slurry to one side of an aluminum current collector sheet, it was 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%.

[0394] <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%.

[0395] <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%.

[0396] <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%.

[0397] <Comparative Example 3-1> A positive electrode was produced in the same manner as in Example 3-1 except that flaky graphite was not 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%.

[0398] <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%.

[0399] <Experimental Example 3-1. Measurement of Charge-Discharge Capacity and Charge-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.

[0400]

Table 2

[0401] 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, they showed a lower porosity and excellent capacity characteristics compared to Comparative Examples 3-1 and 3-2.

[0402] <Experimental Example 3-2. Confirmation of Resistance Characteristics> While charging the 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 SOC were measured. The results of the experiment are shown in Fig. 42a.

[0403] Referring to Fig. 42a, it can be confirmed that based on SOC10%, the resistance value of Example 3-3 in which flaky graphite was added to the positive electrode active material layer is lower than that of Comparative Example 3-1 and Comparative Example 3-2 which 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 a low SOC.

[0404] <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, a jelly roll-type electrode assembly was manufactured. After the manufactured electrode assembly was inserted into a cylindrical battery can, an electrolytic solution was injected to manufacture a 4680 cell.

[0405] At this time, the negative electrode was prepared by mixing 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) in a weight ratio of 96:2:1.5:0.5 in water to produce a negative electrode slurry. Then, the negative electrode slurry was applied to one side of a copper current collector sheet, dried at 150 °C, and then rolled.

[0406] The 4680 cells manufactured in this way were charged at 40 °C at 0.5C up to 4.2V and then discharged at 0.5C down to 2.5V. One cycle was defined as this process, 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. 42b.

[0407] Referring to Fig. 42b, it can be seen that in the case of the secondary batteries of Example 3-1 and 3-3, the change in the capacity retention rate according to the number of cycles is less, and the change in the resistance increase rate according to the number of cycles is also less than that of the secondary battery of Comparative Example 3-1.

[0408] As described above, the present invention has been described with reference to the limited embodiments and drawings. However, 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 of the present invention and the claims by those having ordinary knowledge in the technical field to which the present invention pertains.

Explanation of Reference Numerals

[0409] 1 Cylindrical battery 11 First electrode tab 12 Second electrode tab 20 Battery housing 21 Beading part 22 Crimping part 30 First current collector plate 31 Support part 32 First tab connection part 33 First housing connection part 33a First contact part 33b First connection part 34 Second housing connection part 34a Second contact part 34b Second connection part 40 Cap plate 41 Bending part 50 Second current collector plate 51 Peripheral part 52 Second tab connection part 53 Terminal connection part 54 Connecting part 54a Tapered part 60 Battery terminal 60a Terminal exposed part 60b Terminal insertion part 300 Electrode assembly 400 Negative electrode 410 Negative electrode current collector 420 Negative electrode active material part 430 Negative electrode non-coated part 500 Positive electrode 510 Positive electrode current collector 520 Positive electrode active material part 530 Positive electrode non-coated part 600 Separator 700 Negative electrode 710 Negative electrode current collector 720 Negative electrode active material part 730 Negative electrode non-coated part 800 Positive electrode 810 Positive electrode current collector 820 Positive electrode active material part 830 Positive electrode non-coated part 900 Separator

Claims

1. An electrode assembly including a first electrode tab and a second electrode tab; A battery housing that houses the electrode assembly through an opening formed on one side and is electrically connected to the first electrode tab; A support portion disposed on one surface of the electrode assembly, at least one first tab coupling portion extending from the support portion and coupled to the first electrode tab, and at least one first housing coupling portion extending from the support portion and coupled to an inner surface of the battery housing, and a first current collector plate positioned within the battery housing; A peripheral portion disposed on the other surface positioned opposite to one surface of the electrode assembly, a second tab coupling portion extending inwardly from the peripheral portion and coupled to the second electrode tab, and a second current collector plate including a terminal coupling portion positioned spaced apart from the second tab coupling portion; A cap plate configured to seal the opening of the battery housing; A battery terminal that is electrically connected to the second electrode tab by coupling to the terminal coupling portion, the cylindrical battery including the same.

2. The battery housing includes a beading portion formed on a peripheral portion adjacent to the opening and pushed inward; The cylindrical battery according to claim 1, wherein the first housing coupling portion is coupled on the beading portion.

3. The first housing coupling portion includes: A first contact portion coupled to an inner surface of the battery housing; The cylindrical battery according to claim 1 or 2, further including a first connecting portion connecting between the support portion and the first contact portion.

4. The cylindrical battery according to claim 3, wherein at least a part of the first contact portion extends along an inner circumferential surface of the battery housing.

5. The cylindrical battery according to claim 3, wherein the first connecting portion includes at least one first bent portion whose extending direction is changed.

6. The cylindrical battery according to claim 1 or 2, wherein the first current collector plate further includes a second housing coupling portion extending from an end of the first tab coupling portion and coupled to an inner surface of the battery housing.

7. The second housing coupling portion includes: A second contact portion coupled to an inner surface of the battery housing; The cylindrical battery according to claim 6, further including a second connecting portion connecting between the support portion and the second contact portion.

8. The cylindrical battery according to claim 7, wherein at least a part of the second contact portion has a form extending along the inner peripheral surface of the battery housing.

9. The cylindrical battery according to claim 7, wherein the second connecting portion includes at least one second bent portion whose extending direction is changed.

10. The cylindrical battery according to claim 1 or 2, wherein the peripheral portion has a rim shape with a central portion being empty.

11. The cylindrical battery according to claim 1 or 2, wherein the second tab connecting portion and the terminal connecting portion are electrically connected by the peripheral portion.

12. The cylindrical battery according to claim 1 or 2, wherein the terminal connecting portion is located at the center of the inner space of the peripheral portion.

13. The cylindrical battery according to claim 1 or 2, wherein the second current collecting plate further includes a connecting portion extending inward from the peripheral portion and connected to the terminal connecting portion.

14. The cylindrical battery according to claim 13, wherein at least a part of the width of the connecting portion is formed narrower than that of the second tab connecting portion.

15. The cylindrical battery according to claim 14, wherein the connecting portion includes a tapered portion whose width gradually narrows from the inner surface of the peripheral portion toward the terminal connecting portion.

16. The cylindrical battery according to claim 13, wherein a plurality of the second tab connecting portions are provided.

17. The cylindrical battery according to claim 16, wherein the plurality of second tab connecting portions are arranged at the same intervals along the extending direction of the peripheral portion.

18. The cylindrical battery according to claim 16, wherein the plurality of second tab connecting portions have the same extending length.

19. The cylindrical battery according to claim 16, wherein the terminal connecting portion is arranged so as to be surrounded by the plurality of second tab connecting portions.

20. The connecting portion is located between a pair of adjacent second tab connecting portions, The cylindrical battery according to claim 16, wherein the distance from the connecting portion to one of the pair of second tab connecting portions along the extending direction of the peripheral portion is the same as the distance from the connecting portion to the other of the pair of second tab connecting portions along the extending direction of the peripheral portion.

21. The cylindrical battery according to claim 16, wherein a plurality of the connecting portions are provided.

22. The cylindrical battery according to claim 21, wherein each of the plurality of connecting portions is arranged between a pair of adjacent second tab connecting portions.

23. The plurality of connecting portions are arranged at the same intervals along the extending direction of the peripheral edge portion, the cylindrical battery according to claim 21.

24. The connecting portion includes a notch formed by narrowing the width of the connecting portion, the cylindrical battery according to claim 13.

25. The connecting portion includes a notch formed by narrowing the width of the connecting portion, The notch is located closer to the tapered portion than the terminal connecting portion, the cylindrical battery according to claim 15.

26. The terminal connecting portion is disposed at a position corresponding to a hole formed in the winding center portion of the electrode assembly, the cylindrical battery according to claim 1 or 2.

27. The second electrode tab extends toward a closed portion located on the opposite side of the open portion of the battery housing, the cylindrical battery according to claim 1 or 2.

28. The second tab connecting portion is coupled to a coupling surface formed by bending the end of the second electrode tab along a direction parallel to the second current collector plate, the cylindrical battery according to claim 27.

29. The cap plate is not connected to the electrode assembly and has no polarity, the cylindrical battery according to claim 1 or 2.

30. The battery terminal penetrates a closed portion located on the opposite side of the open portion of the battery housing, the cylindrical battery according to claim 1 or 2.

31. The cylindrical battery further includes an insulator interposed between the closed portion and the second current collector plate, the cylindrical battery according to claim 30.

32. The battery terminal passes through the insulator and is coupled to the terminal connecting portion of the second current collector plate, the cylindrical battery according to claim 31.

33. The active material layer of the second electrode contains 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 or 2.

34. 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 following mathematical formula 1 【Mathematical formula 1】 Particle Size Distribution (PSD) = (D ｍａｘ - D ｍｉｎ ) / D ５０ The cylindrical battery according to claim 33, wherein the particle size distribution (PSD) represented by is 3 or less.

35. The single particles, pseudo single particles, or a combination thereof are 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 second electrode, the cylindrical battery according to claim 33.

36. The cylindrical battery according to claim 33, wherein the positive electrode active material contains 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.

37. The active material layer of the second electrode has a porosity of 15% to 23%, The cylindrical battery according to claim 33, wherein the active material layer of the second electrode contains flaky graphite in a weight ratio of 0.05 wt% to 5 wt%.

38. The cylindrical battery according to claim 33, wherein the active material layer of the second electrode further contains carbon nanotubes (CNT).

39. The active material layer of the first electrode contains a silicon-based negative electrode active material and a carbon-based negative electrode active material, The cylindrical battery according to claim 33, wherein the silicon-based negative electrode active material and the carbon-based negative electrode active material are contained in a weight ratio of 1:99 to 20:

80.

40. A battery pack including the cylindrical battery according to claim 1 or 2.

41. An automobile including the battery pack according to claim 40.

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