Cylindrical battery, current collecting plate applied thereto, battery pack including the same, and automobile

Abstract

Provided according to the present application are a cylindrical battery, a current collecting plate applied thereto, a battery pack including the same, and a vehicle, the cylindrical battery including: an electrode assembly having a first electrode tab and a second electrode tab; a battery case accommodating the electrode assembly through an open portion formed on one side; a first current collecting plate located inside the battery case and including a support portion disposed on one face of the electrode assembly, at least one tab coupling portion extending from the support portion and coupled to the first electrode tab, and at least one case coupling portion extending from an end of the tab coupling portion and coupled to an inner side surface of the battery case; a cover plate covering the open portion; a battery terminal penetrating the battery case on an opposite side of the open portion to be electrically connected to the second electrode tab; and a closure partition configured to prevent movement of the electrode assembly and to strengthen the closure of the battery case.

Description

Technical Field

[0001] This invention relates to cylindrical batteries, current collectors used therein, battery packs including therein, and automobiles. Furthermore, this invention relates to a positive electrode for electrochemical elements with improved electrochemical characteristics, and an electrode assembly including the aforementioned positive electrode. Background Technology

[0002] In addition to portable devices, secondary batteries, which are highly adaptable to various product groups and have high energy density and other electrical properties, are also widely used in electric vehicles (EVs) or hybrid electric vehicles (HEVs) driven by electric drive sources.

[0003] This type of rechargeable battery not only has the primary advantage of significantly reducing the use of fossil fuels, but also the advantage of producing no byproducts when using energy. Therefore, it has attracted much attention as a new energy source that is environmentally friendly and improves energy efficiency.

[0004] Currently, widely used rechargeable batteries include lithium-ion batteries, lithium polymer batteries, nickel-cadmium batteries, nickel-metal hydride batteries, and nickel-zinc batteries. The operating voltage of a single rechargeable battery cell is approximately 2.5V to 4.5V. Therefore, when a higher output voltage is required, multiple batteries are connected in series to form a battery pack. Furthermore, depending on the required charge / discharge capacity of the battery pack, sometimes multiple batteries are connected in parallel to form a battery pack. Therefore, depending on the required output voltage and / or charge / discharge capacity, the number of batteries included in a battery pack and the electrical connection method can be designed in various ways.

[0005] On the other hand, as types of secondary battery units, cylindrical, square, and pouch batteries are disclosed. In a cylindrical battery, a separator membrane serving as an insulator is sandwiched between the positive and negative electrodes, and this membrane is rolled up to form a gel-roll-shaped electrode assembly. This assembly, along with an electrolyte, is then inserted into the battery casing to form the battery. Furthermore, strip-shaped electrode tabs can be connected to the uncoated portions of both the positive and negative electrodes, electrically connecting the electrode assembly to the exposed electrode terminals. For reference, the positive electrode terminal is a cover plate of a sealant that seals the opening of the battery casing, and the negative electrode terminal is the battery casing itself.

[0006] However, according to existing cylindrical batteries with this structure, the current is concentrated on the strip electrode tabs that are combined with the uncoated positive electrode and / or the uncoated negative electrode, resulting in problems such as high resistance, high heat generation, and low current collection efficiency.

[0007] For small cylindrical batteries with a form factor of 18650 or 21700, resistance and heat generation are not major issues. However, when the form factor is increased to make cylindrical batteries suitable for electric vehicles, a lot of heat is generated around the electrode tabs during fast charging, which could potentially lead to a fire in the cylindrical battery.

[0008] To address this issue, a cylindrical battery with an improved current-collecting efficiency (a so-called tabless cylindrical battery) has been disclosed. The design features an uncoated positive electrode portion and an uncoated negative electrode portion located at the upper and lower ends of a gel roll-type electrode assembly, respectively, with a current-collecting plate welded to such uncoated portions.

[0009] Secondly, refer to Figures 1 to 4 Further details will be provided regarding existing cylindrical batteries.

[0010] Figures 1 to 3 This is a diagram illustrating the manufacturing process of a tabless cylindrical battery. Figure 1 The structure of the electrode is shown. Figure 2 The electrode winding process is shown. Figure 3 The process of welding a current collector to the bent surface of an uncoated section is shown. Figure 4 This is a cross-sectional view of a tabless cylindrical battery cut along its length Y direction.

[0011] Reference Figures 1 to 4 The positive electrode 500 has a structure in which the positive electrode tab 500S includes a positive electrode active material portion 520 and a positive electrode uncoated portion 530 extending along one long side in the winding direction, and the negative electrode 400 has a structure in which the negative electrode tab 400S includes a negative electrode active material portion 420 and a negative electrode uncoated portion 430 extending along one long side in the winding direction. The electrode assembly 300 is constructed as follows: Figure 2 The positive electrode 500 and the negative electrode 400 are sequentially stacked together with two separation membranes 600 and then wound in one direction X. At this time, the uncoated portion 530 of the positive electrode 500 and the uncoated portion 430 of the negative electrode 400 are arranged in opposite directions.

[0012] After the winding process, the uncoated portion 530 of the positive electrode 500 and the uncoated portion 430 of the negative electrode 400 are bent toward the core. Then, current collectors P and 30 are welded to the uncoated portions 530 and 430 respectively for bonding.

[0013] The uncoated positive electrode portion 530 and the uncoated negative electrode portion 430 are not fitted with additional electrode tabs. The current collectors P and 30 are connected to external electrode terminals, forming a current path with a large cross-sectional area along the winding axis direction of the electrode assembly 300 (refer to the arrow). Therefore, it has the advantage of reducing battery resistance. This is because resistance is inversely proportional to the cross-sectional area of ​​the current flow path.

[0014] However, if the shape factor of the cylindrical battery is increased, the charging current during fast charging will increase, and the overheating problem will reappear in the tabless cylindrical battery.

[0015] Specifically, such as Figure 4 As shown, the existing tabless cylindrical battery 1 includes a battery casing 20 and a sealing element A. The sealing element A includes a cover plate 40, a sealing gasket G1, and a connecting plate C1. The sealing gasket G1 wraps around the edge of the cover plate 40 and is fixed by a crimping portion 22. Furthermore, to prevent vertical movement, the electrode assembly 300 is fixed inside the battery casing 20 by a rolled edge portion 21.

[0016] Typically, the positive terminal is the cover plate 40 of the sealing element A, and the negative terminal is the battery casing 20. Therefore, the second current collector P, which is attached to the uncoated portion 530 of the positive electrode 500, is electrically connected to the connecting plate C1 attached to the cover plate 40 via a strip lead L. Furthermore, the first current collector 30, which is attached to the uncoated portion 430 of the negative electrode 400, is electrically connected to the bottom of the battery casing 20. An insulator S covers the second current collector P to prevent short circuits caused by contact between the battery casing 20 and the uncoated portion 530 of the positive electrode 500, which have different polarities.

[0017] When the second current collector P is connected to the connecting plate C1, a strip lead L is used. The lead L is either separately attached to the second current collector P or integrally formed with it. However, the lead L is a thin strip, resulting in a small cross-sectional area, which generates more heat when the current flows during rapid charging. Furthermore, the excessive heat generated in the lead L is transferred to the electrode assembly 300 side, shrinking the separation membrane 600, potentially causing an internal short circuit, which is a major cause of thermal runaway.

[0018] The lead L occupies a significant amount of space within the battery casing 20. Therefore, the cylindrical battery 1, including the lead L, has low space efficiency, thus limiting its ability to increase energy density.

[0019] In addition, to connect existing tabless cylindrical batteries 1 in series and / or parallel, busbar components need to be connected to the cover plate 40 of the seal A and the bottom surface of the battery casing 20, thus reducing space efficiency. Battery packs in electric vehicles comprise hundreds of cylindrical batteries 1. Therefore, the inefficiency of electrical wiring causes considerable trouble for the assembly process of electric vehicles and the maintenance of the battery pack. Therefore, there is a need to develop cylindrical batteries with a structure where the positive and negative terminals are oriented in the same direction, in order to simplify the electrical connection structure of multiple cylindrical batteries.

[0020] In a cylindrical battery with the structure described above, a relatively large space may be formed, particularly between the negative electrode current collector and the cover plate. Furthermore, an empty space may also be formed between the bottom surface of the battery casing, located on the side opposite to the cover plate, and the positive electrode current collector.

[0021] Such empty space could cause the gel-roll-shaped electrode assembly to move inside the battery casing, especially in the vertical direction, i.e., along the height of the cylindrical battery. When the electrode assembly moves vertically in this way, the connection between the current collector and the electrode tabs may be damaged, as may the connection between the current collector and the battery casing, and the connection between the current collector and the battery terminals.

[0022] Therefore, it is necessary to minimize the operating space of such electrode assemblies. Furthermore, using additional components to reduce the operating space of electrode assemblies increases process complexity and manufacturing costs; therefore, it is necessary to utilize previously used components to address these issues.

[0023] On the other hand, existing cylindrical batteries generally have a structure in which tabs connecting the electrode assembly and external terminals are soldered to the foil of the electrode assembly to achieve connection. This structure of cylindrical batteries has a limited current path, resulting in very high resistance of the electrode assembly itself.

[0024] Therefore, an attempt was made to reduce the resistance by increasing the number of tabs used to connect the electrode assembly and the external terminals. However, simply increasing the number of tabs has limitations in reducing the resistance to the desired level and ensuring a sufficient current path.

[0025] Therefore, in order to reduce the resistance of the electrode assembly itself, it is necessary to develop new electrode assembly structures and current collector structures suitable for such electrode assembly structures. In particular, the application of such new electrode assembly and current collector structures is even more necessary in devices such as electric vehicles that require battery packs with high output / high capacity.

[0026] Furthermore, there is a need to develop a cylindrical battery with a structure that maintains and enhances the bonding force between the current collector and the battery casing, as well as a current collector structure suitable for such a cylindrical battery.

[0027] On the other hand, when using existing positive electrode active materials that include secondary particles to manufacture electrodes, the occurrence of particle cracking and the increase in gas generation due to internal cracks during charging and discharging may lead to problems with battery stability.

[0028] To address this issue, positive electrode active materials with relatively large primary particle sizes or similar single-particle shapes have been developed. However, when these single-particle or similar single-particle shaped positive electrode active materials are applied to high-load electrodes and then rolled, the electrodes crack when the porosity does not reach the target level, resulting in poor resistance characteristics and charging / discharging efficiency of the lithium secondary battery. Summary of the Invention

[0029] Technical problems to be solved

[0030] The present invention was made in view of the above-mentioned problems, and its object 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.

[0031] Furthermore, the object of the present invention is to provide a current collector having a structure that can improve the bonding force at the joint between the current collector and the battery casing, and a cylindrical battery including the same.

[0032] Furthermore, its purpose is to prevent the gel roll from moving within the battery casing, thereby causing damage to the electrical connection points.

[0033] Furthermore, another objective of the present invention is to prevent the electrode assembly from moving by using previously employed components during the manufacturing of cylindrical batteries, thereby preventing the complexity of the manufacturing process and the increase in manufacturing costs caused by the use of additional components.

[0034] Furthermore, the object of the present invention is to provide a current collector having a structure capable of improving the energy density of a cylindrical battery, and a cylindrical battery including the same.

[0035] Furthermore, the object of the present invention is to provide a current collector having a structure that improves the convenience of the welding process for realizing the electrical connection between the battery casing and the current collector during the manufacture of a cylindrical battery, thereby increasing productivity, and a cylindrical battery including the same.

[0036] Another technical problem of the present invention is to provide a cylindrical battery including an electrode assembly with improved structure, a battery pack including the same, and a vehicle including the battery pack.

[0037] Another technical problem of the present invention is to provide an electrode that uses single particles or similar single particles as the positive electrode active material, thereby achieving good thermal stability, high conductivity, and high rolling characteristics, as well as an electrode assembly including the same.

[0038] Another technical problem of the present invention is to provide an electrode assembly that includes a silicon-based negative electrode active material in the negative electrode to improve energy density.

[0039] Another technical problem of the present invention is to provide an electrode assembly that increases the positive electrode active material region without worrying about lithium deposition.

[0040] Another technical problem of the present invention is to provide a cylindrical battery that can exhibit good thermal safety even when the battery volume increases due to the increase in shape factor.

[0041] It should be noted that the technical problem to be solved by the present invention is not limited to the above-mentioned technical problem. Those skilled in the art can clearly understand other technical problems not mentioned through the following description of the invention.

[0042] means of solving technical problems

[0043] A cylindrical battery according to an embodiment of the present invention for solving the above-mentioned problems includes: an electrode assembly having a first electrode tab and a second electrode tab; a battery housing housing the electrode assembly through an opening formed on one side; a first current collector located inside the battery housing and including a support portion disposed on one side of the electrode assembly, at least one tab connection portion extending from the support portion and engaging with the first electrode tab, and at least one housing connection portion extending from the end of the tab connection portion and engaging with the inner side surface of the battery housing; a cover plate covering the opening; a battery terminal penetrating the battery housing on the opposite side of the opening to be electrically connected to the second electrode tab; and a sealing partition configured to prevent movement of the electrode assembly and enhance the sealing of the battery housing.

[0044] The battery casing may include a rolled edge formed at the end adjacent to the opening and pressed inward.

[0045] The aforementioned housing joint can be attached to the aforementioned rolled edge portion.

[0046] The aforementioned housing joint may include: a contact portion, which is attached to the aforementioned rolled edge portion; and a connecting portion, which connects the aforementioned tab joint portion and the aforementioned contact portion.

[0047] The cylindrical battery may include a sealing gasket disposed between the battery casing and the cover plate.

[0048] The aforementioned contact portion can be fixed between the rolled edge portion of the battery casing and the aforementioned sealing gasket.

[0049] A welded portion may be formed between the rolled edge of the battery casing of the cylindrical battery and the contact portion of the current collector plate.

[0050] The boundary region between the tab joint and the casing joint of the cylindrical battery can be located inside the innermost part of the rolled edge.

[0051] The cylindrical battery described above may each have multiple of the aforementioned tab joints and the aforementioned casing joints.

[0052] The aforementioned connecting portion may have at least one curved portion that changes the extension direction.

[0053] The contact portion may have an arcuate shape extending along the rolled edge of the battery casing.

[0054] The connecting portion may have an arcuate shape extending along the contact portion.

[0055] The aforementioned enclosed partition may include: an anti-movement portion sandwiched between the first current collector and the cover plate; a sealing portion sandwiched between the battery casing and the cover plate; and a connecting portion connecting the anti-movement portion and the sealing portion.

[0056] The aforementioned anti-movement part may have a height corresponding to the distance between the aforementioned first collector plate and the aforementioned cover plate.

[0057] On one side of the aforementioned electrode assembly, the aforementioned anti-movement part may be located at the center.

[0058] The aforementioned anti-movement part may have a partition hole formed at a position corresponding to the winding center hole of the aforementioned electrode assembly.

[0059] The aforementioned closure may have a shape that extends along the inner circumferential edge of the battery casing.

[0060] The aforementioned connecting portion may include a plurality of extended supports extending radially from the aforementioned anti-movement portion.

[0061] The aforementioned multiple extension brackets can be configured to not contact the aforementioned first collector plate.

[0062] The aforementioned multiple extension brackets can be configured to not contact the aforementioned cover plate.

[0063] The aforementioned connecting portion can be positioned so that it does not overlap with the aforementioned casing joint portion along the height direction of the aforementioned cylindrical battery.

[0064] The aforementioned cylindrical battery may further include: a second current collector plate, which is coupled to the first electrode tab; and an insulator sandwiched between a blocking portion formed at the upper end of the battery casing and the second current collector plate.

[0065] The insulator may have a height corresponding to the distance between the second current collector and the blockage.

[0066] The active material layer of the second electrode may comprise positive electrode active material including single particles, similar single particles, or combinations thereof, wherein the minimum particle size D exhibited in the volumetric cumulative distribution of the positive electrode active material is...min For particles larger than 1.0 μm, the particle size D is the one that constitutes 50% of the total volume of the aforementioned positive electrode active material. 50 Below 5.0 μm, the largest particle size D exhibited in the volumetric cumulative distribution of the aforementioned positive electrode active material is... max It is 12μm to 17μm.

[0067] The aforementioned positive electrode active material can have a unimodal particle size distribution exhibiting a single peak in the volumetric particle size distribution curve, with a particle size distribution (PSD) of less than three, expressed by the following mathematical formula:

[0068] Particle size distribution (PSD) = (D max –D min ) / D 50 Mathematical expression

[0069] Based on the total weight of the positive electrode active material contained in the active material layer of the second electrode, it may contain 95 wt% to 100 wt% of the above-mentioned single particles, similar single particles, or combinations thereof.

[0070] The aforementioned positive electrode active material includes lithium nickel oxide, which contains more than 80 mol% Ni based on the total molar number of transition metals.

[0071] The porosity of the active material layer of the second electrode can be 15% to 23%, and the active material layer of the second electrode contains flake graphite in a weight ratio of 0.05wt% to 5wt%.

[0072] The active material layer of the second electrode may also include carbon nanotubes.

[0073] The active material layer of the first electrode may include silicon-based negative electrode active material and carbon-based negative electrode active material, in a weight ratio of 1:99 to 20:80.

[0074] A battery pack according to an embodiment of the present invention includes a cylindrical battery as described above according to an embodiment of the present invention.

[0075] A vehicle according to an embodiment of the present invention includes a battery pack as described above according to an embodiment of the present invention.

[0076] Invention Effects

[0077] According to the present invention, resistance can be significantly reduced when realizing the electrical connection between the electrode assembly and the battery casing.

[0078] Furthermore, according to the present invention, the bonding force at the joint between the current collector and the battery casing can be improved.

[0079] Moreover, according to the present invention, the energy density of cylindrical batteries can be increased.

[0080] Furthermore, according to the present invention, when manufacturing cylindrical batteries, the ease of the welding process for realizing the electrical connection between the battery casing and the current collector is improved, thereby increasing productivity.

[0081] Furthermore, according to one aspect of the invention, the movement of the gel roll within the battery casing is minimized, thereby preventing damage to the electrical bonding area.

[0082] According to another aspect of the invention, by utilizing previously used components instead of adding components to prevent the movement of the gel roll, it is possible to prevent the complexity of the manufacturing process and the increase in manufacturing costs.

[0083] According to another aspect of the invention, the positive electrode contains D min The positive electrode active material powder with a particle size of 1.0 μm or larger can further improve the thermal safety of the battery. The inventors of this invention have found that even when single particles and / or similar single particles are used as the positive electrode active material, the effect of suppressing particle cracking after calendering and the improvement of thermal safety vary depending on the particle size of the positive electrode active material powder. In particular, when the positive electrode active material powder contains particles with a particle size of less than 1.0 μm, the pressure of the calendering line increases, resulting in more particle cracking and decreased thermal stability. This makes it impossible to ensure sufficient thermal safety when used in large cylindrical batteries. Therefore, in this invention, by using a minimum particle size D… min By limiting the positive electrode active material powder to a size of 1.0 μm or larger, the thermal safety improvement effect can be maximized.

[0084] According to another aspect of the invention, the positive electrode contains D 50 D max The positive electrode active material powder with an appropriate particle size distribution (PSD) can minimize the increase in resistance caused by using single particles, thereby achieving good capacity and output characteristics.

[0085] According to another aspect of the present invention, the positive electrode comprises a single-particle positive electrode active material covered with a conductive coating or comprises novel CNTs as a conductive material, thereby improving the conductivity of the electrode.

[0086] According to another aspect of the present invention, the positive electrode active material layer comprises flake-shaped graphite. Therefore, when the positive electrode active material layer is rolled, the flake-shaped graphite provides a sliding effect on the positive electrode active material, thereby improving the rolling characteristics of the electrode and reducing the electrode porosity to a target level. This improves the stability, initial resistance characteristics, and charge / discharge efficiency of the cylindrical battery.

[0087] According to another aspect of the invention, the negative electrode contains a silicon-based negative electrode active material with a large capacity, thereby enabling higher energy density.

[0088] According to another aspect of the present invention, the positive electrode includes a load reduction section with a lower loading of positive electrode active material, so that the range of the positive electrode active material section can be increased without worrying about lithium deposition.

[0089] According to another aspect of the present invention, compared with existing batteries having strip electrode tabs, the internal heat generation of the battery can be reduced efficiently, thus improving the thermal safety of the battery.

[0090] It should be noted that the effects that can be obtained by the present invention are not limited to the effects described above. Those skilled in the art can clearly understand other technical effects not mentioned below through the following description of the invention. Attached Figure Description

[0091] The accompanying drawings, which schematically illustrate preferred embodiments of the invention, serve to further explain the technical concept of the invention together with the detailed description of the invention that follows, and should not be construed as limiting the invention to the matters shown in these drawings.

[0092] Figure 1 This is a plan view showing the electrode structure used in existing tabless cylindrical battery cells.

[0093] Figure 2 This is a diagram illustrating the winding process of the electrode assembly contained in a conventional tabless cylindrical battery cell.

[0094] Figure 3 It is shown Figure 2 A diagram showing the process of welding a current collector plate to the bent surface of the uncoated part in the electrode assembly.

[0095] Figure 4 This is a cross-sectional view of an existing tabless cylindrical battery cell cut along its length direction Y.

[0096] Figure 5 This is a diagram showing a portion of the longitudinal section of a cylindrical battery according to an embodiment of the present invention.

[0097] Figure 6This is a diagram showing a portion of the longitudinal section of a cylindrical battery according to another embodiment of the present invention.

[0098] Figure 7 This is a diagram showing a portion of the longitudinal section of a cylindrical battery according to yet another embodiment of the present invention.

[0099] Figure 8 It is used for explanation Figure 3 A diagram of the first current collector contained in a cylindrical battery.

[0100] Figure 9 This is a diagram illustrating a first current collector according to another embodiment of the present invention.

[0101] Figure 10 This is a diagram illustrating a first current collector according to yet another embodiment of the present invention.

[0102] Figure 11 This is a perspective view showing the appearance of a cylindrical battery according to an embodiment of the present invention.

[0103] Figure 12 This is a cross-sectional view showing the internal structure of a cylindrical battery according to an embodiment of the present invention.

[0104] Figure 13 This is a partial cross-sectional view showing the area with a closed partition in the application of the present invention.

[0105] Figure 14 This is a diagram illustrating a closed partition according to an embodiment of the present invention.

[0106] Figure 15 This is a plan view showing the bottom surface of the cylindrical battery of the present invention.

[0107] Figure 16 This is a partial cross-sectional view showing the region where the insulator is applied according to the present invention.

[0108] Figure 17 This is a partial cross-sectional view showing the connection structure of the current collector and electrode tabs of the present invention.

[0109] Figure 18 This is a block diagram illustrating a battery pack according to an embodiment of the present invention.

[0110] Figure 19 This is a concept diagram of a car according to an embodiment of the present invention.

[0111] Figure 20 These are scanning microscope images of carbon nanotubes (currently CNTs), which were previously commonly used.

[0112] Figure 21 These are scanning microscope images of a novel CNT according to an embodiment of the present invention.

[0113] Figure 22 This is a table showing a comparison of the physical properties of existing CNTs and novel CNTs.

[0114] Figures 23 to 26 This is a graph showing the sheet resistance and high-temperature lifetime characteristics of different conductive material ratios when single-particle active material particles are used as the positive electrode active material.

[0115] Figure 27 The comparison shows that the specific surface area of ​​BET is 300m². 2 / g to 500m 2 / g of carbon nanotubes (novel CNTs) and their applications BET at 200m 2 / g or more and less than 300m 2 Table u shows the solid powder content and viscosity of the cathode slurry in the case of / g carbon nanotubes (existing CNTs), as well as the resistance values ​​in the MP coating and MP interface layer.

[0116] Figure 28a This is a SEM image of the positive electrode active material used in Example 2-1 of the present invention.

[0117] Figure 28b These are SEM images of the positive electrode active material used in Examples 2-2 of the present invention.

[0118] Figure 28c This is a SEM image of the positive electrode active material used in Comparative Example 2-2 of this invention.

[0119] Figure 29a This is a graph showing the hot box test results of the 4680 battery cell manufactured according to Embodiment 1 of the present invention.

[0120] Figure 29b This is a graph showing the hot box test results of the 4680 battery cell manufactured according to Comparative Example 1 of the present invention.

[0121] Figure 29c This is a graph showing the hot box test results of Sample 1 of Embodiment 2-1 of the present invention and the 4680 battery cell manufactured by Comparative Example 2-1.

[0122] Figure 29d The graph shows the hot box test results of samples 2 and 3 of Example 2-1, samples 1 and 2 of Example 2-2, and the 4680 battery cell manufactured by Comparative Example 2-2.

[0123] Figure 30a This is a cross-sectional SEM image of the positive electrode manufactured in Embodiment 2-1 of the present invention.

[0124] Figure 30b This is a cross-sectional SEM image of the positive electrode manufactured in Comparative Example 2-1.

[0125] Figure 31a The graph shows the results of measuring the SOC-based resistance characteristics while charging a coin cell including the positive electrode of Embodiments 3-3, Comparative Examples 3-1 and 3-2 according to the present invention to 4.2V.

[0126] Figure 31b The graph shows the measurement results of capacity retention and DCIR increase of the 4680 battery cell obtained by charge-discharge cycle h experiment for the 4680 battery cell of Embodiments 3-1, 3-3 and Comparative Example 3-1 according to the present invention.

[0127] Figure 32 This is a diagram illustrating an electrode assembly according to an embodiment of the present invention.

[0128] Figure 33 It shows along Figure 32 A cross-sectional view of the section cut by the cutting line A-A'.

[0129] Figure 34 as well as Figure 35 This is a diagram illustrating the process of manufacturing a negative electrode according to an embodiment of the present invention.

[0130] Figure 36 This is a perspective view showing the negative electrode according to an embodiment of the present invention.

[0131] Figure 37 as well as Figure 38 This is a diagram illustrating the process of manufacturing a positive electrode according to an embodiment of the present invention.

[0132] Figure 39 This is a perspective view showing the positive electrode according to an embodiment of the present invention.

[0133] Figure 40 This is a diagram illustrating an electrode assembly according to a comparative example of the present invention.

[0134] Figure 41 It shows along Figure 40 A cross-sectional view of the section cut by the cutting line B-B'.

[0135] Figure 42 This is a diagram illustrating the process of manufacturing a negative electrode according to a comparative example of the present invention.

[0136] Figure 43 This is a diagram illustrating the process of manufacturing a positive electrode according to a comparative example of the present invention.

[0137] Figure 44This is a graph showing the change in energy density in a battery that uses a mixture of silicon-based and carbon-based anode active materials as the anode active material, depending on the content of the silicon-based anode active material and whether or not it is coated with silicon-based anode active material. Detailed Implementation

[0138] The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings. Before proceeding, the terms and words used in this specification and claims should not be limited to their ordinary or dictionary meanings. Given the principle that inventors may appropriately define terms and concepts in order to best illustrate their invention, they should be interpreted as conforming to the meaning and concept of the present invention. Therefore, the embodiments described in this specification and the configurations shown in the accompanying drawings are only some of the most preferred embodiments of the present invention and do not represent the entirety of the present invention's technical concept. It should be understood that at the time of filing this application, various equivalents and modifications could exist to replace these.

[0139] Furthermore, to aid in understanding the invention, the accompanying drawings are not shown at actual scale, and sometimes the dimensions of some constituent elements are exaggerated. Also, in different embodiments, the same reference numerals may be used to label the same constituent elements.

[0140] For ease of explanation, the sizes and thicknesses of the components shown in the accompanying drawings are shown arbitrarily, and the present invention is not necessarily limited to the situation shown in the drawings. In the drawings, the thicknesses of multiple layers and regions are shown enlarged to clearly illustrate them. Furthermore, in the drawings, the thicknesses of some layers and regions are exaggerated for ease of explanation.

[0141] Furthermore, when it is described as a part of a layer, film, region, plate, etc., being located "above" or "on top of" other parts, this includes not only the case of being "directly above" other parts, but also the case where there is another part in between. Conversely, when it is described as a part being "directly above" other parts, it means that there is no other part in between. Also, when it is described as being "above" or "on top of" a reference part, it means being above or below the reference part, and does not necessarily mean that it is "above" or "on top of" in the opposite direction of gravity.

[0142] Furthermore, throughout the specification, when a part is described as "including" certain constituent elements, it indicates that other constituent elements may also be included, rather than excluding other constituent elements, unless otherwise specified.

[0143] Furthermore, throughout the instruction manual, when it is described as "on a plane," it indicates the result when the corresponding part is viewed from above; when it is described as "on a cross section," it indicates the result when the corresponding part is viewed from the side through a cross section that has been cut vertically.

[0144] Reference Figure 5 According to an embodiment of the present invention, a cylindrical battery 1 includes an electrode assembly 300, a battery casing 20, a first current collector 30, a cover plate 40, and battery terminals 60. In addition, the cylindrical battery 1 may also include a sealing gasket G1 and / or an insulating gasket G2 and / or a second current collector P and / or an insulator S.

[0145] The electrode assembly 300 described above 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 separation membrane sandwiched between the first electrode and the second electrode. The first electrode is either a negative electrode or a positive electrode, and the second electrode is equivalent to an electrode having the opposite polarity to the first electrode. More specifically, the electrode assembly 300 can be manufactured by winding a laminate formed by sequentially stacking the first electrode, the separation membrane, the second electrode, and the separation membrane at least once. That is, the electrode assembly 300 applied in this invention can be a gel roll type electrode assembly. Such a gel roll type electrode assembly 300 can have a portion formed approximately at its center and along its height direction (with...). Figure 5 The winding center hole H1 extends in the direction parallel to each other in the height direction of the cylindrical battery 1 shown. On the other hand, the outer peripheral surface of the electrode assembly 300 may also have an additional separation membrane to achieve insulation from the battery housing 20.

[0146] The aforementioned first electrode includes a first electrode current collector and a first electrode active material layer coated on one or both sides of the first electrode current collector. The width direction of the aforementioned first electrode current collector (with...) Figure 5 The cylindrical battery 1 shown has an uncoated portion (without the first electrode active material) on one side end. With the first electrode extended, this uncoated portion has a shape extending from one end to the other along the length of the first electrode. This uncoated portion functions as the first electrode tab 11 as described above. The first electrode tab 11 is provided in the height direction (within the parallel direction of the height of the electrode assembly 300 housed within the battery casing 20) of the battery casing 20. Figure 5 The upper part of the cylindrical battery 1 shown (in the direction of parallel alignment along its height). The first electrode tab 11 mentioned above can be, for example, a negative electrode tab.

[0147] The aforementioned second electrode includes a second electrode current collector and a second electrode active material layer coated on one or both sides of the second electrode current collector. The width direction of the aforementioned second electrode current collector (with...) Figure 5 The cylindrical battery 1 shown has an uncoated portion (without the active material of the second electrode) at one end in the height direction (parallel to the other). With the second electrode extended, this uncoated portion has a shape extending from one end to the other along the length of the second electrode. This uncoated portion functions as the second electrode tab 12 as described above. The second electrode tab 12 is located at the lower part of the electrode assembly 300 housed within the battery casing 20 in the height direction. The second electrode tab 12 can be, for example, a positive electrode tab.

[0148] 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.

[0149] It should be noted that the present invention is not limited to the electrode assembly 300 in this manner.

[0150] The battery casing 20 described above is a generally cylindrical housing with an opening on one side, and is made of a conductive metal. The side surface of the battery casing 20 and the underside located opposite the opening (as shown in the image) Figure 5 The lower part (based on the reference point) can be integrally formed. That is, the battery housing 20 can have a shape where the upper end is open and the lower end is blocked in the height direction. The lower part of the battery housing 20 can have a generally flat shape. The battery housing 20 houses the electrode assembly 300 through an opening formed on one side in the height direction. The battery housing 20 can also house the electrolyte through the opening. It should be noted that the present invention does not limit the battery housing 20 to this configuration.

[0151] The battery casing 20 is electrically connected to the electrode assembly 300. The battery casing 20 is connected to the first electrode tab 11 of the electrode assembly 300. Therefore, the battery casing 20 has the same electrical polarity as the first electrode tab 11.

[0152] The battery housing 20 may include a rolled edge portion 21 formed at the end adjacent to the opening and pressed inward. The battery housing 20 may have the rolled edge portion 21 formed at the upper end. The battery housing 20 may also have a wrinkled portion 22 formed on the upper part of the rolled edge portion 21. The rolled edge portion 21 has a shape in which the outer peripheral edge of the battery housing 20 is pressed in to a predetermined depth. The rolled edge portion 21 is formed on the upper part of the electrode assembly 300. The inner diameter of the battery housing 20 in the region where the rolled edge portion 21 is formed is smaller than the diameter of the electrode assembly 300.

[0153] The aforementioned rolled edge portion 21 provides a support surface for placing the cover plate 40. Furthermore, the aforementioned rolled edge portion 21 can provide a support surface for placing and engaging at least a portion of the edge perimeter of the first current collector 30 (described later). That is, at least a portion of the edge perimeter of the first current collector 30 of the present invention and / or the edge perimeter of the cover plate 40 of the present invention can be placed on the aforementioned rolled edge portion 21. Figure 6 as well as Figure 7 As shown, in order to stably support at least a portion of the edge of the first current collector 30 and / or the edge of the cover plate 40, the upper surface of the rolled edge 21 may have a shape in which at least a portion extends in a direction substantially parallel to the lower surface of the battery housing 20, i.e., in a direction substantially perpendicular to the sidewall of the battery housing 20.

[0154] The aforementioned wrinkled portion 22 is formed on the upper part of the rolled edge portion 21. The wrinkled portion 22 has an extending and bending shape that wraps around the edge of the cover plate 40 disposed on the upper part of the rolled edge portion 21. Through the shape of this wrinkled portion 22, the cover plate 40 is fixed to the rolled edge portion 21. Alternatively, this wrinkled portion 22 can be omitted, and the cover plate 40 can be fixed while covering the opening of the battery casing 20 using other fixing structures.

[0155] Secondly, refer to Figure 7 as well as Figure 8 The first current collector 30 according to an embodiment of the present invention will be described in detail.

[0156] First, refer to Figure 7 According to an embodiment of the present invention, a first current collector 30 is housed inside a battery casing 20, electrically connected to an electrode assembly 300, and electrically connected to the battery casing 20. That is, the first current collector 30 enables the electrical connection between the electrode assembly 300 and the battery casing 20.

[0157] The first current collector 30 includes a support portion 31 disposed on one side of the electrode assembly 300, at least one tab connection portion 32 extending from the support portion 31 and engaging with the first electrode tab 11, and at least one housing connection portion 33 extending from the end of the tab connection portion 32 and engaging with the inner side of the battery housing 20, and is located inside the battery housing.

[0158] The aforementioned support portion 31 and at least one tab connection portion 32 may be disposed on the upper part of the electrode assembly 300, and when the battery housing 20 has a rolled edge portion 21, it is located further below the rolled edge portion 21.

[0159] The aforementioned support portion 31 may have a first current collector hole H2 formed at a position corresponding to the winding hole H1 formed at approximately the center of the electrode assembly 300. The winding hole H1 and the first current collector hole H2, which are interconnected, can function as a channel for inserting welding rods for welding between the battery terminal 60 and the second current collector P (described later) or between the battery terminal 60 and the lead tab (not shown), or for irradiating lasers.

[0160] The aforementioned support portion 31 may have a generally circular plate shape. For example, see reference... Figure 8 The aforementioned support portion 31 may have an annular shape with a first collector plate hole H2 at its center.

[0161] The aforementioned at least one tab connection portion 32 may have a shape that extends generally radially from the support portion 31 toward the sidewall of the battery casing 20. For example, multiple tab connection portions 32 may be provided. For example, refer to… Figure 8 Each of the plurality of tab joints 32 can be positioned spaced apart from each other along the edge of the support portion 31. Thus, the cylindrical battery 1 of the present invention has a plurality of tab joints 32, thereby increasing the contact area with the first electrode tab 11. This ensures a strong bond between the first electrode tab 11 and the tab joint 32, reducing resistance.

[0162] The longitudinal end of the aforementioned tab joint 32 may be located inside the innermost part of the rolled edge 21 formed on the battery housing 20. More specifically, the boundary region between the aforementioned tab joint 32 and the housing joint 33 may be located further inside the rolled edge 21 formed on the battery housing 20 in the direction towards the winding hole H1. With this structure, damage to the joint between components that may occur when the first current collector 30 is excessively bent to position the end of the housing joint 33 on the rolled edge 21 can be prevented.

[0163] On the other hand, in order to ensure bonding strength and reduce resistance by increasing the bonding area between the first current collector 30 and the electrode assembly 300, the support portion 31 can also be bonded to the first electrode tab 11 in addition to the tab bonding portion 32. The end of the first electrode tab 11 is shaped into a curved shape parallel to the tab bonding portion 32. When the end of the first electrode tab 11 is shaped in this way and bonded to the tab bonding portion 32 in a parallel state, the bonding area is increased, thereby improving the bonding strength and reducing the resistance. Furthermore, the total height of the electrode assembly 300 is minimized, thereby increasing the energy density.

[0164] The aforementioned housing coupling portion 33 extends from the end of the aforementioned tab coupling portion 32 and is coupled to the inner surface of the aforementioned battery housing 20. For example, the aforementioned housing coupling portion 33 may have a shape that extends from the end of the aforementioned tab coupling portion 32 toward the side wall of the battery housing 20. For example, multiple aforementioned housing coupling portions 33 may be provided. For example, referring to… Figure 8 Each of the multiple housing joints 33 can be positioned spaced apart from each other along the perimeter of the support portion 31. (See reference...) Figure 5 The aforementioned housing joint 33 can be joined to the rolled edge 21 on the inner side of the battery housing 20. For example... Figure 6 as well as Figure 7 As shown, the upper surface of the rolled edge 21 has a shape extending in a direction substantially parallel to the lower surface of the battery casing 20, i.e., substantially perpendicular to the sidewall of the battery casing 20, and the casing joint 33 also has a shape extending in the same direction, so that the casing joint 33 can stably contact the rolled edge 21. Furthermore, this stable contact of the casing joint 33 with the rolled edge 21 allows for smooth welding between the two components, thereby improving the bonding force between the two components and minimizing the increase in resistance at the joint. Moreover, by attaching the first current collector 30 to the rolled edge 21 of the battery casing 20 instead of the cylindrical inner surface of the battery casing 20, the distance between the first current collector 30 and the rolled edge 21 can be reduced. Therefore, the dead angle inside the battery casing 20 is minimized, thereby increasing the energy density of the cylindrical battery 1.

[0165] Reference Figure 7 as well as Figure 8 The aforementioned housing joint 33 includes a contact portion 33a attached to the inner side of the battery housing 20 and a connecting portion 33b connecting the tab joint 32 and the contact portion 33a.

[0166] The aforementioned contact portion 33a is attached to the inner surface of the battery housing 20. When the battery housing 20 has a rolled edge portion 21, the contact portion 33a can be attached to the rolled edge portion 21 as described above. In this case, as described above, for stable contact and attachment, both the rolled edge portion 21 and the contact portion 33a have a shape extending in a direction substantially parallel to the bottom surface of the battery housing 20, that is, substantially perpendicular to the sidewall of the battery housing 20.

[0167] Reference Figure 7The connecting portion 33b may have at least one curved portion B where its extension direction changes between the support portion 31 and the contact portion 33a. That is, the connecting portion 33b may have a spring-like structure or a pleated structure that can extend and retract within a certain range. According to this structure of the connecting portion 33b, even if there is a high degree of dispersion of the electrode assembly 300 within a certain range, the contact portion 33a can be made to fit tightly against the rolled edge portion 21 during the process of accommodating the electrode assembly 300 with the first current collector 30 in the battery housing 20.

[0168] The accompanying drawings of this invention only show the case of having one of the above-mentioned curved portions B, but the invention is not limited to this, and of course, multiple portions may be provided.

[0169] For example, preferably, the vertical distance D between the contact portion 33a and the support portion 31, when no external force is applied to the first current collector 30 and no deformation occurs, is formed to be the same as the vertical distance between the top of the rolled edge portion 21 and the support portion 31 when the electrode assembly 300 with the first current collector 30 attached is placed inside the battery housing 20, or shorter within the elongation range of the connecting portion 33b. When the connecting portion 33b is configured to satisfy such conditions, when the electrode assembly 300 with the first current collector 30 attached is placed inside the battery housing 20, the contact portion 33a can naturally and tightly adhere to the rolled edge portion 21.

[0170] In addition, due to the retractable structure of this connecting part 33b, in the cylindrical battery 1 (refer to...) Figure 5 During use, even if vibration and / or impact occur, causing the electrode assembly 300 to move up and down, the impact caused by the movement of the electrode assembly 300 can still be mitigated within a certain range.

[0171] On the other hand, when the connecting portion 33b has only one bent portion B, unlike the case shown in the figures, the bent portion B can also protrude in the direction toward the winding center of the electrode assembly 300. This bending direction of the connecting portion 33b is used to prevent damage to the joint between the first current collector 30 and the electrode assembly 300, and / or the joint between the first current collector 30 and the battery casing 20, during the sizing process. Sizing is a compression process in the manufacture of the cylindrical battery 1, aimed at reducing the overall height of the cylindrical battery 1 and thus reducing the height occupied by the rolled edge portion 21 area of ​​the battery casing 20. Observing the degree of damage to the welded portion after the sizing process by changing whether the bent portion B is formed and the protruding direction of the bent portion B, it was found that almost no damage occurred in the cylindrical battery 1 with a structure in which the bent connecting portion 33b protrudes in the direction toward the center of the cylindrical battery 1.

[0172] Secondly, refer to Figure 9 This illustrates a first current collector 30 according to another embodiment of the present invention. The first current collector 30 according to another embodiment of the present invention differs from the one described above only in the shape of the contact portion 33a. Figure 8 The first collector board 30 is different, but otherwise, a structure that is substantially the same as the first collector board 30 described above can be applied.

[0173] Reference Figure 9 The contact portion 33a may have a shape in which at least a portion extends along the inner circumferential surface of the battery casing 20. For example, the contact portion 33a may have an arcuate shape extending along the rolled edge portion 21. Furthermore, although not shown in the figures, 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 contact portions 33a of at least one casing joint portion 33 is approximately the same as the inner circumference of the battery casing 20.

[0174] Secondly, refer to Figure 10 This illustrates a first current collector 30 according to yet another embodiment of the present invention. The first current collector 30 according to yet another embodiment of the present invention is similar in shape to the connecting portion 33b. Figure 9 The first collector board 30 is different, but otherwise, a structure that is substantially the same as the first collector board 30 described above can be applied.

[0175] Reference Figure 10 The connecting portion 33b may have a shape in which at least a portion extends along the inner circumferential surface of the battery casing 20. For example, the contact portion 33a may have an arcuate shape extending along the rolled edge portion 21 of the battery casing, and the connecting portion 33b may have an arcuate shape extending along the contact portion 33a. According to this structure, with... Figure 9 Compared to the first collector plate 30 shown, the area of ​​the first collector plate 30 is further increased, so the effect of reducing resistance can be maximized.

[0176] On the other hand, refer to Figure 10 ,and Figure 8 or Figure 9 Unlike the first current collector 30 shown, the first current collector 30 may not have the bent portion B. By omitting the bent portion B, the raw materials required for manufacturing the first current collector 30 can be saved. This reduces the manufacturing cost of the first current collector 30.

[0177] Reference Figure 5The cover plate 40 covers the opening formed on one side of the battery housing 20. When the battery housing 20 of the present invention has a rolled edge portion 21, the cover plate 40 can be placed on the rolled edge portion 21 formed on the battery housing 20. Furthermore, when the battery housing 20 of the present invention has a wrinkled portion 22, the cover plate 40 can be fixed by the wrinkled portion 22. In this case, to improve the fixing force and the sealing of the battery housing 20, a sealing gasket G1 can be sandwiched between the battery housing 20 and the cover plate 40. It should be noted that in the present invention, the cover plate 40 is not a component that needs to function as a current channel. Therefore, if the battery housing 20 and the cover plate 40 can be firmly fixed by welding or by other components to ensure the sealing of the opening of the battery housing 20, it is not necessary to use such a sealing gasket G1.

[0178] To ensure rigidity, the cover plate 40 can be made of metal, for example. In the cylindrical battery 1 of the present invention, the cover plate 40 can be polarized even if it is made of a conductive metal. The absence of polarity means that the cover plate 40 is electrically insulated from the battery casing 20 and the battery terminals 60 described below. Therefore, the cover plate 40 does not function as a positive or negative terminal. Therefore, the cover plate 40 does not need to be electrically connected to the electrode assembly 300 and the battery casing 20, and its material is not necessarily a conductive metal.

[0179] On the other hand, taking the case where the aforementioned sealing gasket G1 is used as an example, the sealing gasket G1 can have a generally annular shape that wraps around the cover plate 40. The sealing gasket G1 can simultaneously cover the top, bottom, and sides of the cover plate 40. The radial length of the portion of the sealing gasket G1 covering the bottom of the cover plate 40 can be shorter or the same as the radial length of the portion of the sealing gasket G1 covering the top of the cover plate 40. If the radial length of the portion of the sealing gasket G1 covering the bottom of the cover plate 40 is too long, during the compression of the battery casing 20, the sealing gasket G1 may press against the first current collector 30, potentially damaging the first current collector 30 or the battery casing 20. Therefore, it is necessary to maintain the radial length of the portion of the sealing gasket G1 covering the bottom of the cover plate 40 at a relatively short level. For example, as Figure 5 As shown, the radial length of the portion of the sealing gasket G1 that covers the area below the cover plate 40 can be made shorter than the radial length of the portion of the sealing gasket G1 that covers the area above the cover plate 40. Alternatively, as... Figure 6 as well as Figure 7 As shown, the radial length of the portion of the sealing gasket G1 that covers the area below the cover plate 40 can be the same as the radial length of the portion of the sealing gasket G1 that covers the area above the cover plate 40.

[0180] On the other hand, the contact portion 33a can be fixed between the rolled edge portion 21 and the sealing gasket G1. That is, the contact portion 33a can be fixed by the wrinkling force of the wrinkled portion 22 while the contact portion 33a is sandwiched between the rolled edge portion 21 and the sealing gasket G1.

[0181] Alternatively, a welded portion can be formed between the rolled edge 21 and the contact portion 33a. For example, sometimes the contact portion 33a cannot be reliably fixed by the wrinkling force alone. Or, if the sealing gasket G1 shrinks due to heat or the wrinkled portion 22 is deformed by external impact, the bonding force between the current collector and the battery casing 20 may be reduced. Therefore, the first current collector 30 can be fixed to the battery casing 20 by welding while the contact portion 33a is placed on the rolled edge 21. Afterwards, the wrinkled portion 22 is formed by placing a cover plate wrapped by the sealing gasket G1 on the upper end of the contact portion 33a, thereby completing the cylindrical battery 1. At this time, welding methods such as laser welding, resistance welding, and ultrasonic welding can be used, but the welding method is not limited to these.

[0182] On the other hand, the cover plate 40 may include a vent 41 to prevent the generation of gas inside the battery casing 20, which could lead to an increase in internal pressure. The vent 41 is formed in a portion of the cover plate 40, corresponding to a structurally weaker area than the surrounding region, making it more susceptible to rupture under internal pressure. The vent 41 may, for example, be a region with a thinner thickness than the surrounding region. Therefore, when the cylindrical battery 1 malfunctions and the internal pressure of the battery casing 20 increases to a certain level, the vent 41 ruptures, allowing the gas generated inside the battery casing 20 to escape. The vent 41 can be formed by locally reducing the thickness of the battery casing 20, for example, by noching one or both sides of the cover plate 40.

[0183] The battery terminal 60 is electrically connected to the second electrode tab 12. The battery terminal 60 can penetrate the battery housing 20 on the opposite side of the open portion of the battery housing 20 and then be electrically connected to the second electrode tab 12 of the electrode assembly 300. The battery terminal 60 can penetrate approximately the center of the lower part of the battery housing 20. A portion of the battery terminal 60 protrudes to the outside of the battery housing 20, while the remaining portion can be located inside the battery housing 20. The battery terminal 60 can be connected, for example, to a second current collector P connected to the second electrode tab 12 (described later) or to a lead tab (not shown) connected to the second electrode tab 12, thereby enabling electrical connection to the electrode assembly 300. Therefore, the battery terminal 60 has the same polarity as the second electrode of the electrode assembly 300 and can function as the second electrode terminal T2. When the second electrode tab 12 is a positive tab, the battery terminal 60 can function as the positive terminal.

[0184] Considering the polarity and function of this battery terminal 60, the battery terminal 60 needs to be kept insulated from the battery casing 20, which has the opposite polarity. For this purpose, an insulating gasket G2 can be used between the battery terminal 60 and the battery casing 20. Alternatively, insulation can be achieved by coating a portion of the surface of the battery terminal 60 with an insulating material. Alternatively, the battery terminal 60 and the battery casing 20 can be spaced apart to prevent contact, and the battery terminal 60 can be structurally and securely fixed. Alternatively, multiple methods described above can be used simultaneously.

[0185] That is, the cylindrical battery 1 of the present invention has a structure in which a pair of electrode terminals 60 and T1 are located in the same direction. Therefore, when multiple cylindrical batteries 1 are electrically connected, electrical connection components such as busbars can be arranged only on one side of the cylindrical battery 1. This simplifies the battery pack structure and increases energy density. Furthermore, the cylindrical battery 1 has a structure in which one side of the battery casing 20, which has a generally flat shape, can be used as the first electrode terminal T1, thereby ensuring a sufficient contact area when electrical connection components such as busbars are joined to the first electrode terminal T1. As a result, the cylindrical battery 1 can ensure sufficient contact strength between the electrical connection components and the first electrode terminal T1, and can reduce the resistance at the contact point to an ideal level.

[0186] On the other hand, when an insulating gasket G2 is used for electrical insulation and riveting is used to fix the battery terminal 60, the insulating gasket G2 deforms together with the battery terminal 60 during riveting, and can be bent towards the inner side of the plug at the upper end of the battery housing 20. When the insulating gasket G2 is made of resin, it can be bonded to the battery housing 20 and the battery terminal 60 by heat fusion. In this case, the airtightness of the interface between the insulating gasket G2 and the battery terminal 60, as well as the interface between the insulating gasket G2 and the battery housing 20, can be enhanced.

[0187] In this invention, the entire surface of the battery casing 20 can function as the first electrode terminal T1. For example, if the first electrode tab 11 is a negative electrode tab, the first electrode terminal T1 can be the negative terminal. According to the cylindrical battery 1 of the invention, a structure is provided in which the battery terminal 60 exposed on the underside opposite to the open portion of the battery casing 20, and the remaining area on the underside of the battery casing 20 excluding the area occupied by the battery terminal 60, are respectively used as the second electrode terminal T2 and the first electrode terminal T1. Therefore, according to the cylindrical battery 1 of the invention, when multiple cylindrical batteries 1 are electrically connected, all positive / negative electrodes can be connected in one direction, simplifying the electrical connection structure. Furthermore, the cylindrical battery 1 of the invention has a structure in which a large portion of the underside opposite to the open portion of the battery casing 20 can be used as an electrode terminal, thus having the advantage of ensuring sufficient area for soldering components used for electrical connections.

[0188] Preferably, the cylindrical battery can be, for example, a cylindrical battery with a shape factor ratio (the value of the diameter of the cylindrical battery divided by the height, i.e., defined as the ratio of the diameter Φ relative to the height H) that is approximately greater than 0.4.

[0189] The shape factor indicates the diameter and height of the cylindrical battery. According to an embodiment of the present invention, the cylindrical battery may be, for example, a 46110 battery, a 48750 battery, a 48110 battery, a 48800 battery, or a 46800 battery. In the shape factor values, the first two digits represent the diameter of the battery, the next two digits represent the height of the battery, and the final digit 0 indicates that the battery has a circular cross-section.

[0190] According to an embodiment of the present invention, the cylindrical battery is a generally cylindrical battery, which may have a diameter of about 46 mm, a height of about 110 mm, and a shape factor ratio of about 0.418.

[0191] According to another embodiment, the cylindrical battery is a generally cylindrical battery, which may have a diameter of about 48 mm, a height of about 75 mm, and a shape factor ratio of about 0.640.

[0192] According to another embodiment, the cylindrical battery is a generally cylindrical battery, which may be a cylindrical battery with a diameter of about 48 mm, a height of about 110 mm, and a shape factor ratio of about 0.418.

[0193] According to another embodiment, the cylindrical battery is a generally cylindrical battery, which may be a cylindrical battery with a diameter of about 48 mm, a height of about 80 mm, and a shape factor ratio of about 0.600.

[0194] According to another embodiment, the cylindrical battery is a generally cylindrical battery, which may be a cylindrical battery with a diameter of about 46 mm, a height of about 80 mm, and a shape factor ratio of about 0.575.

[0195] Previously, cylindrical batteries with a form factor ratio of approximately 0.4 or less were used. Specifically, 18650 and 21700 batteries were used. An 18650 battery has a diameter of approximately 18 mm and a height of approximately 65 mm, with a form factor ratio of 0.277. A 21700 battery has a diameter of approximately 21 mm and a height of approximately 70 mm, with a form factor ratio of 0.300.

[0196] Secondly, refer to Figures 11 to 19 The cylindrical battery 1 described above will be further described in detail below. In the following description, while the same constituent elements as described above are presented, other alternative embodiments may be selectively applicable. Furthermore, there may be partial repetition of content from the above description in the following description.

[0197] Reference Figure 12 , Figure 13 , Figure 16 as well as Figure 17 The electrode assembly 300 includes a first electrode tab 11 and a second electrode tab 12. The first electrode tab 11 is located at the lower part of the electrode assembly 300 housed in the battery casing 20 in the height direction (parallel to the Z-axis). The second electrode tab 12 is located at the upper part of the electrode assembly 300 housed in the battery casing 20 in the height direction (parallel to the Z-axis).

[0198] Reference Figure 11 , Figure 12 , Figure 13 as well as Figure 16 The battery housing 20 can accommodate the electrode assembly 300 through an opening formed at its lower end. The battery housing 20 is a generally cylindrical accommodating body with an opening at its lower end and a blocking portion at its upper end.

[0199] Reference Figure 12 as well as Figure 13The battery housing 20 may have a rolled edge 21 and a wrinkled portion 22 formed at its lower end. The rolled edge 21 may be located below the electrode assembly 300 housed inside the battery housing 20. The rolled edge 21 may be formed by pressing the battery housing 20 into the edge of its outer peripheral surface. The rolled edge 21 reduces the local inner diameter of the battery housing 20, thereby preventing the electrode assembly 300, which may have a size approximately corresponding to the width of the battery housing 20, from falling out through the opening formed at the lower end of the battery housing 20. The rolled edge 21 may also function as a support for the cover plate 40.

[0200] The aforementioned wrinkled portion 22 is formed below the rolled edge portion 21. The aforementioned wrinkled portion 22 may have a shape that extends and bends in such a way that it wraps around the edge of the cover plate 40 while sandwiching the edge of the closed partition 50.

[0201] Reference Figure 12 , Figure 13 as well as Figure 15 The cover plate 40 can cover the opening formed in the battery casing 20. The cover plate 40 can form the bottom of the cylindrical battery 1.

[0202] Reference Figure 13 as well as Figure 15 Preferably, the lower end of the cover plate 40 is located above the lower end of the battery housing 20. In this case, even if the lower end of the battery housing 20 abuts against the ground or the bottom surface of the housing used to form the module or battery pack, the cover plate 40 will not abut against the ground or the bottom surface of the housing. Therefore, it is possible to prevent the pressure at which the vent hole 41 ruptures due to the weight of the cylindrical battery 1 differs from the design value, thereby ensuring the smooth rupture of the vent hole 41.

[0203] On the other hand, the aforementioned vent 41 has, as Figure 13 as well as Figure 15 In the case of the closed-loop shape shown, from the perspective of ease of rupture, the farther the distance from the center of the cover plate 40 to the vent hole 41, the more advantageous it is. This is because when the same ventilation pressure is applied, the farther the distance from the center of the cover plate 40 to the vent hole 41, the greater the force acting on the vent hole 41, and the easier it is to rupture. Furthermore, from the perspective of the ease of gas discharge, the farther the distance from the center of the cover plate 40 to the vent hole 41, the more advantageous it is. From these viewpoints, the vent hole 41 extends downward from the edge region of the cover plate 40 (towards... Figure 15 It is advantageous when the edge of a roughly flat area protrudes (in the direction of downwards) as a reference.

[0204] In the present invention Figure 15The illustration shows the vent 41 being formed continuously in a generally circular manner, but the invention is not limited thereto. The vent 41 can also be formed discontinuously in a generally circular manner on the cover plate 40, or it can be formed in a generally straight line shape or other shapes.

[0205] Reference Figure 12 , Figure 13 as well as Figure 14 The aforementioned sealing partition 50 is configured to prevent movement of the electrode assembly 300 and enhance the sealing of the battery casing 20. The sealing partition 50 may include, for example, an anti-movement portion 51, a sealing portion 52, and a connecting portion 53. The anti-movement portion 51 is sandwiched between the first current collector plate 30 and the cover plate 40. The anti-movement portion 51 may have a height corresponding to the distance between the first current collector plate 30 and the cover plate 40. In this case, the anti-movement portion 51, through the gap formed between the first current collector plate 30 and the cover plate 40, can effectively prevent the electrode assembly 300 from moving within the battery casing 20. Therefore, the anti-movement portion 51 can prevent damage to the joint between the electrode assembly 300 and the first current collector plate 30, and / or the joint between the first current collector plate 30 and the battery casing 20.

[0206] The aforementioned anti-movement portion 51 may be located approximately at the center of one side of the lower end of the electrode assembly 300. The anti-movement portion 51 may include a partition hole H3 formed at a position corresponding to the winding center hole H1 of the electrode assembly 300. Similar to the aforementioned first current collector hole H2, the partition hole H3 can function as an insertion channel for the welding rod or a channel for laser irradiation. Also similar to the aforementioned first current collector hole H2, the partition hole H3 can function as a channel for the electrolyte to smoothly impregnate the interior of the electrode assembly 300 during electrolyte injection.

[0207] The aforementioned sealing portion 52 is sandwiched between the battery housing 20 and the cover plate 40. The sealing portion 52 may have a shape extending along the inner circumferential edge of the battery housing 20. When the battery housing 20 has a wrinkled portion 22, the sealing portion 52 bends along the bending shape of the wrinkled portion 22, thereby covering the edge region of the cover plate 40. In this way, the sealing portion 52 can function as a gasket to improve the fixation of the cover plate 40 and the sealing of the battery housing 20. In the case where the cylindrical battery 1 of the present invention has a sealing separator 50, the sealing portion 52 of the sealing separator 50 can replace... Figures 5 to 7 The sealing gasket G1 is shown.

[0208] The aforementioned connecting portion 53 connects the anti-movement portion 51 and the sealing portion 52. The connecting portion 53 may include, for example, a plurality of extension brackets 53a extending radially from the anti-movement portion 51. With the connecting portion 53 configured in this way, electrolyte can be smoothly injected through the space between adjacent extension brackets 53a, and internal gas can be smoothly discharged when ventilation occurs due to increased internal pressure.

[0209] like Figure 13 as well as Figure 14 As shown, the aforementioned multiple extension brackets 53a can be configured so that they do not contact the remaining portion of the housing joint 33 of the first current collector 30, except for the portion inserted into the crimped portion 22, and / or the cover plate 40. For example, the aforementioned connecting portion 53 can be positioned so that it does not overlap with the housing joint 33 along the height direction of the cylindrical battery 1 (the direction parallel to the Z-axis). In particular, when the aforementioned multiple extension brackets 53a have a shape that extends radially from the anti-movement portion 51, and the aforementioned multiple housing joints 33 have a shape that extends radially from the support portion 31, the multiple extension brackets 53a and the multiple housing joints 33 can be arranged in staggered positions so that they do not overlap with each other in the vertical direction. In this case, even if a vertical compressive force is applied to the aforementioned battery housing 20, causing multiple components to deform, the possibility of interference between the extension brackets 53a and the housing joints 33 can be significantly reduced, thereby significantly reducing the possibility of problems such as damage to the joints between multiple components.

[0210] In this configuration, even if the shape of the sealing separator 50 changes due to a sizing process that compresses the cylindrical battery 1 in the height direction (parallel to the Z-axis) or other reasons, interference between the connecting portion 53 of the sealing separator 50 and the housing joint 33 of the first current collector 30 can be minimized. In particular, when the extension bracket 53a is configured not to contact the cover plate 40, the possibility of shape changes in the extension bracket 53a can be reduced even if the battery housing 20 changes shape due to a sizing process or external impact.

[0211] On the other hand, the constituent elements of the aforementioned closed separator 50 can be integrated. For example, the closed separator 50, in which the anti-movement part 51, the sealing part 52, and the connecting part 53 are integrated, can be manufactured by the aforementioned injection molding process. That is, according to the cylindrical battery 1 of the present invention, by changing the gasket member used to seal the opening of the battery casing 20, the effects of strengthening the sealing of the opening of the battery casing 20 and preventing the electrode assembly 300 from moving can be simultaneously achieved with a single component. Therefore, according to the present invention, it is possible to prevent the complexity of the manufacturing process and the increase in manufacturing costs caused by the application of additional components.

[0212] Reference Figure 12 , Figure 16 as well as Figure 17 The second current collector P is attached to the upper part of the electrode assembly 300. The second current collector P is made of a conductive metal and is attached to the second electrode tab 12. The connection between the second electrode tab 12 and the second current collector P can be achieved, for example, by laser welding. (Refer to...) Figure 13 The second current collector plate P can be bonded to the bonding surface formed by bending the end of the second electrode tab 12 in a direction parallel to the second current collector plate P. The bending direction of the second electrode tab 12 can be, for example, towards the winding center of the electrode assembly 300. When the second electrode tab 12 has such a bent shape, the space occupied by the second electrode tab 12 is reduced, thereby increasing the energy density. Furthermore, due to the increase in the bonding area between the second electrode tab 12 and the second current collector plate P, the bonding force can be improved and the resistance can be reduced. On the other hand, the bonding structure and bonding method between the second electrode tab 12 and the second current collector plate P as described above can also be applied in the same way to the bonding between the first electrode tab 11 and the first current collector plate 30.

[0213] Reference Figure 12 as well as Figure 16 The insulator S is sandwiched between the blocking portion formed on the upper end of the battery housing 20 and the upper end of the electrode assembly 300, or between the blocking portion and the second current collector P. The insulator S can be made of, for example, an insulating resin material. The insulator S prevents contact between the electrode assembly 300 and the battery housing 20, and / or between the electrode assembly 300 and the second current collector P. Therefore, the insulator S can be sandwiched between the second electrode tab 12 and the battery housing 20, and / or between the second current collector P and the battery housing 20. When the insulator S is used, the battery terminal 60 can pass through the insulator S for electrical connection with the second electrode tab 12.

[0214] In addition, the aforementioned insulator S can also be sandwiched between the upper end of the outer peripheral surface of the electrode assembly 300 and the inner surface of the battery housing 20. In this case, it is possible to prevent the second electrode tab 12 of the electrode assembly 300 from contacting the inner surface of the side wall of the battery housing 20 and thus preventing a short circuit.

[0215] The insulator S described above may have a height corresponding to the distance between the plug formed on the upper end of the battery housing 20 and the electrode assembly 300, or the distance between the plug and the second current collector P. In this case, movement of the electrode assembly 300 inside the battery housing 20 can be prevented, thereby significantly reducing the risk of damage to the joints used for electrical connections between components. When both the insulator S and the sealing partition 50 are applied simultaneously, the effect of preventing movement of the electrode assembly 300 can be maximized.

[0216] The aforementioned insulator S may have an opening formed at a position corresponding to the winding center hole H1 of the electrode assembly 300. Through this opening, the battery terminal 60 can directly contact the second current collector P.

[0217] Reference Figure 18 According to an embodiment of the present invention, the battery pack 3 includes the cylindrical battery 1 as described above according to an embodiment of the present invention. In the accompanying drawings of the present invention, for ease of illustration, components such as busbars for electrical connection, cooling units, and power terminals are omitted.

[0218] Reference Figure 19 According to an embodiment of the present invention, the vehicle 5 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 vehicle 5 includes both four-wheeled and two-wheeled vehicles. The vehicle 5 operates by receiving power from the battery pack 3 according to an embodiment of the present invention.

[0219] The following describes an embodiment of the positive electrode active material used in the cylindrical battery according to the present invention.

[0220] In this embodiment, "primary particle" refers to a particle unit that does not exhibit visible grain boundaries when observed using a scanning electron microscope or electron backscatter electron diffraction (EBSD) at a field of view of 5000x to 20000x. "Average particle size of primary particles" refers to the arithmetic mean of the particle sizes of multiple primary particles observed in the scanning electron microscope or EBSD image.

[0221] "Secondary particles" are particles formed by the aggregation of multiple primary particles. In this invention, to distinguish them from existing secondary particles formed by the aggregation of tens to hundreds of primary particles, secondary particles formed by the aggregation of fewer than ten primary particles are referred to as similar single particles.

[0222] In this invention, the "specific surface area" is measured according to the BET method. Specifically, it can be calculated using the BELSORP-mino II from BEL Japan based on the amount of nitrogen adsorbed at liquid nitrogen temperature (77K).

[0223] In this invention, "D" min “D” 50 "and "D max "D" is the particle size value of the volumetric cumulative distribution of the positive electrode active material, measured using the laser diffraction method. Specifically, D min It is the smallest particle size that appears in the volumetric cumulative distribution, D. 50 It is the particle size when the volume accumulation is 50%, D max It represents the maximum particle size exhibited in the volumetric cumulative distribution. When the positive electrode active material is a single particle, D... 50 This represents the average particle size of the primary particles. Furthermore, when the positive electrode active material is similar to a single particle, D... 50 This represents the average particle size of particles formed by the aggregation of multiple primary particles.

[0224] For the particle size value of the above-mentioned volumetric cumulative distribution, for example, after dispersing the positive electrode active material in a dispersion medium, it can be introduced into a commercially available laser diffraction particle size measurement device (e.g., Microtrac MT 3000), irradiated with an ultrasonic wave of about 28 kHz at an output of 60 W, and then the volumetric cumulative particle size distribution curve can be obtained for measurement.

[0225] In this invention, "consist essentially of A" means including component A as well as a variety of unmentioned arbitrary components that do not substantially affect the fundamental and novel features of the invention. The fundamental and novel features of the invention include at least one of minimizing particle cracking during battery manufacturing, minimizing gas generation due to such particle cracking, and minimizing the occurrence of internal cracks. Those skilled in the art will recognize the physical effects of these properties.

[0226] The inventors of this invention, through repeated research in order to develop an electrochemical element positive electrode and an electrochemical element including the same, which achieves high capacity while having good safety, discovered that when using a single particle consisting of a primary particle or an aggregate of ten or fewer primary particles, i.e., a positive electrode active material with a shape similar to a single particle, as the positive electrode active material alone, the safety of large cylindrical batteries can be greatly improved.

[0227] According to one aspect, the positive electrode includes a positive current collector and a positive active material layer formed on at least one side of the positive current collector. The positive active material layer may include a positive active material, and optionally, may include a conductive material and / or an adhesive.

[0228] The positive electrode can be configured to have a positive electrode active material layer formed on at least one or two sides of the elongated positive electrode current collector, and the positive electrode active material layer may include the positive electrode active material and the binder.

[0229] Specifically, the aforementioned positive electrode is manufactured by coating one or both sides of a strip-shaped positive electrode current collector with a positive electrode slurry made by dispersing positive electrode active material, conductive material, and binder in solvents such as dimethyl sulfoxide (DMSO), isopropyl alcohol, N-methylpyrrolidone (NMP), acetone, and water. The solvent in the positive electrode slurry is removed through a drying process, followed by calendering. Alternatively, by leaving a portion of the positive electrode current collector uncoated during the coating process, such as one end of the positive electrode current collector, a positive electrode including an uncoated portion can be manufactured.

[0230] On the other hand, the aforementioned positive electrode active material includes single-particle active material particles. In one embodiment, relative to 100 wt% of the aforementioned positive electrode active material, the single-particle active material particles may be 90 wt% or more, 95 wt% or more, 98 wt% or more, or 99 wt% or more. In a specific embodiment, the aforementioned positive electrode active material is composed solely of the aforementioned single-particle active material particles.

[0231] In this specification, the term "single particle" as referring to active material particles includes single particles, similar single particles, or a combination of single particles and similar single particles. A single particle is a particle composed of a single primary particle, and a similar single particle is an aggregate of ten or fewer primary particles.

[0232] Previously, spherical secondary particles, consisting of tens to hundreds of primary particles aggregated together, were commonly used as the positive electrode active material in lithium batteries. However, this type of positive electrode active material, with its numerous aggregated primary particles, presents several problems during positive electrode manufacturing. These problems include particle cracking due to the shearing process and internal cracking during charging and discharging. The increased contact area with the electrolyte due to particle cracking or internal cracking leads to increased gas production from side reactions with the electrolyte. Increased gas production within a cylindrical battery increases internal pressure, posing a risk of explosion. Furthermore, increasing the volume of the cylindrical battery leads to an increase in the mass of active material, significantly increasing gas production and further escalating the risk of fire and / or explosion.

[0233] In contrast, compared to existing secondary particle-shaped positive electrode active materials composed of tens to hundreds of primary particles, single-particle active materials composed of a single primary particle or fewer than ten primary particles exhibit higher particle strength, thus almost eliminating particle cracking during calendering. Furthermore, the smaller number of primary particles constituting the single-particle active material particles results in less volume expansion and contraction during charging and discharging, significantly reducing internal cracking.

[0234] Therefore, when using single-particle active material particles as in this invention, the amount of gas generated due to particle cracking and internal cracks can be significantly reduced. This results in good safety when applied to large cylindrical batteries.

[0235] On the other hand, based on the total weight of the positive electrode active material contained in the positive electrode, the aforementioned single particles and / or similar single particles contain 95 wt% to 100 wt%, preferably 98 wt% to 100 wt%, more preferably 99 wt% to 100 wt%, and even more preferably 100 wt%.

[0236] When the content of single particles and / or similar single particles meets the above range, sufficient safety can be obtained when applied to large-scale batteries. This is because when the positive electrode active material contains more than 5 wt% of secondary particulate positive electrode active material, the increased dust generated from the secondary particles during electrode manufacturing and charge / discharge processes leads to side reactions with the electrolyte, thereby reducing the effect of suppressing gas generation. Consequently, the effect of improving stability may be reduced when applied to large-scale batteries.

[0237] On the other hand, according to the present invention, D comprises a single-particle and / or similar single-particle positive electrode active material. min The micrometer size can be above 1.0 μm, 1.1 μm, 1.15 μm, 1.2 μm, 1.25 μm, 1.3 μm, or 1.5 μm. This applies to the D-type of the positive electrode active material. min When the particle size is less than 1.0 μm, the pressure of the imprinting line increases during the calendering process of the positive electrode, which can easily cause particle cracking and reduce thermal stability. Therefore, it is not possible to fully ensure thermal safety when it is suitable for large cylindrical batteries.

[0238] On the other hand, considering resistance and output characteristics, the D of the above-mentioned positive electrode active material min It can be below 3μm, below 2.5μm, or below 2μm. If D min If the distance is too large, the diffusion distance of lithium ions within the particles will increase, and the resistance and output characteristics may decrease.

[0239] For example, the D of the above-mentioned positive electrode active material min It can be 1.0μm to 3μm, 1.0μm to 2.5μm, or 1.3μm to 2.0μm.

[0240] On the other hand, the D of the above-mentioned positive electrode active material 50 It can be less than 5μm, less than 4μm, or less than 3μm. For example, it can be from 0.5μm to 5μm, preferably from 1μm to 5μm, and more preferably from 2μm to 5μm.

[0241] In single-particle and / or similarly shaped cathode active materials, there are fewer interfaces between multiple primary particles that serve as diffusion paths for lithium ions within the particle. Therefore, compared to cathode active materials with secondary particle shapes, lithium mobility is poorer, leading to increased resistance. This increase in resistance becomes more severe with increasing particle size, negatively impacting capacity and output characteristics. Therefore, by adjusting the D... 50 By adjusting the size to below 5μm, the diffusion distance of lithium ions inside the positive electrode active material particles is minimized, thereby suppressing the increase in resistance.

[0242] Furthermore, the D of the aforementioned positive electrode active material max The diameter can be from 12 μm to 17 μm, preferably from 12 μm to 16 μm, and more preferably from 12 μm to 15 μm. When the D of the positive electrode active material... max When the above range is met, it exhibits better resistance and capacitance characteristics. When the D of the positive electrode active material... maxWhen the density is too high, aggregation occurs between multiple individual particles. The lithium migration path within these aggregated particles becomes longer, reducing lithium mobility and potentially increasing resistance. On the other hand, when the D of the positive electrode active material... max If the value is too small, it indicates that the crushing process has been overdone. Due to excessive crushing, D... min It is possible for the particle size to become smaller than 1 μm, which could cause particle cracking during calendering and potentially reduce thermal stability.

[0243] On the other hand, the particle size distribution (PSD) of the above-mentioned positive electrode active material, expressed by the following mathematical formula (1), is 3 or less, preferably 2 to 3, and more preferably 2.3 to 3.

[0244] Mathematical formula (1): Particle size distribution (PSD) = (D max –D min ) / D 50

[0245] When the positive electrode active material has the particle size distribution described above, it can properly maintain the electrode density of the positive electrode and effectively suppress particle cracking and resistance increase.

[0246] On the other hand, the average particle size of the primary particles of the aforementioned positive electrode active material can be less than 5 μm, less than 4 μm, less than 3 μm, or less than 2 μm, for example, it can be from 0.5 μm to 5 μm, preferably from 1 μm to 5 μm, and more preferably from 2 μm to 5 μm. When the average particle size of the primary particles meets the above range, positive electrode active materials with good electrochemical properties and / or similar single-particle shapes can be formed. If the average particle size of the primary particles is too small, the number of primary particles forming the positive electrode active material increases, and the effect of suppressing particle cracking decreases during calendering. If the average particle size of the primary particles is too large, the lithium diffusion path inside the primary particles becomes longer, the resistance increases, and the output characteristics may be reduced.

[0247] In this invention, preferably, the aforementioned positive electrode active material has a unimodal particle size distribution. Previously, to increase the electrode density of the positive electrode active material layer, bimodal positive electrode active materials were mostly used, which mixed large-particle-size positive electrode active materials with a larger average particle size and small-particle-size positive electrode active materials with a smaller average particle size. However, if the particle size of the positive electrode active material, or a similar single-particle shape, increases, the lithium migration path becomes longer, significantly increasing the resistance. Therefore, when using a mixture of large-particle-size materials, a decrease in capacity and output characteristics may occur. Therefore, in this invention, a positive electrode active material with a unimodal distribution is used, thereby minimizing the increase in resistance.

[0248] On the other hand, the aforementioned positive electrode active material may comprise a lithium nickel oxide, specifically, based on the total molar percentage of the transition metal, it may comprise a lithium nickel oxide containing 80 mol% or more of Ni. Preferably, the aforementioned lithium nickel oxide may contain 80 mol% or more but less than 100 mol%, 82 mol% or more but less than 100 mol%, or 83 mol% or more but less than 100 mol% of Ni. Using a lithium nickel oxide with a high Ni content as described above enables high capacity.

[0249] More specifically, the above-mentioned positive electrode active material may include lithium nickel oxide represented by the following [Chemical Formula 1].

[0250]

Chemical Formula 1

[0251] Li a Ni b Co c M 1 d M 2 e O2

[0252] In the above chemical formula 1, M 1 It can be Mn, Al, or a combination thereof, preferably Mn or Mn and Al.

[0253] The above M 2 It can be one or more elements selected from the group consisting of Zr, W, Y, Ba, Ca, Ti, Mg, Ta, and Nb. Preferably, it can be one or more elements selected from the group consisting of Zr, Y, Mg, and Ti. More preferably, it can be Zr, Y, or a combination thereof. The M2 element is not mandatory, but when included in an appropriate amount, it can promote particle growth during firing and improve the stability of the crystal structure.

[0254] The term 'a' above represents the molar ratio of lithium in the lithium-nickel oxide, which can be 0.8 ≤ a ≤ 1.2, 0.85 ≤ a ≤ 1.15, or 0.9 ≤ a ≤ 1.2. When the molar ratio of lithium meets the above range, a stable crystalline structure of the lithium-nickel oxide can be formed.

[0255] The 'b' mentioned above represents the molar ratio of nickel in the total metal content (excluding lithium) of the lithium-nickel oxide, which 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 molar ratio of nickel meets the above range, it exhibits high energy density and can achieve high capacity.

[0256] In the above, c represents the molar ratio of cobalt in the total metal other than lithium in the lithium nickel-based oxide, and it can be 0 < c < 0.2, 0 < c < 0.18, 0.01 ≤ c ≤ 0.17, 0.01 ≤ c ≤ 0.15, 0.01 ≤ c ≤ 0.12 or 0.01 ≤ c ≤ 0.10. When the molar ratio of cobalt satisfies the above range, good resistance characteristics and output characteristics can be achieved.

[0257] In the above, d represents M 1 element in the total metal other than lithium in the lithium nickel-based oxide, and it can be 0 < d < 0.2, 0 < d < 0.18, 0.01 ≤ d ≤ 0.17, 0.01 ≤ d ≤ 0.15, 0.01 ≤ d ≤ 0.12 or 0.01 ≤ d ≤ 0.10. When the molar ratio of the M 1 element satisfies the above range, good structural stability of the positive electrode active material is presented.

[0258] In the above, e represents M 2 element in the total metal other than lithium in the lithium nickel-based oxide, and it can be 0 ≤ e ≤ 0.1 or 0 ≤ e ≤ 0.05.

[0259] On the other hand, according to the present invention, the positive electrode active material may further include a coating as needed. The coating contains 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 above lithium nickel-based oxide particles. Preferably, the above coating elements may be Al, B, Co, or a combination thereof.

[0260] When a coating exists on the surface of the lithium nickel-based oxide particles, the contact between the electrolyte and the lithium nickel-based oxide is suppressed by the coating, and thus the effect of reducing the dissolution of transition metals or the generation of gas caused by side reactions with the electrolyte can be obtained.

[0261] With respect to the total weight of the positive electrode active material layer, the above positive electrode active material may be included at 80 wt% to 99 wt%, preferably included at 85 wt% to 99 wt%, and more preferably included at 90 wt% to 99 wt%.

[0262] On the other hand, various positive current collectors used in this technical field can be used as the aforementioned positive current collector. For example, stainless steel, aluminum, nickel, titanium, sintered carbon, or aluminum or stainless steel surfaces treated with carbon, nickel, titanium, silver, etc., can be used as the aforementioned positive current collector. The aforementioned positive current collector can typically have a thickness of 3μm to 500μm, and fine irregularities can be formed on the surface of the aforementioned positive current collector, thereby improving the adhesion of the positive active material. The aforementioned positive current collector can be used in various shapes, such as thin films, sheets, foils, meshes, porous bodies, foams, nonwoven fabrics, etc.

[0263] On the other hand, in one embodiment of the present invention, all or part of the aforementioned plurality of single-particle active material particles may have a core-shell structure in which the particle surface is coated with a conductive coating. The conductive coating may cover at least part or all of the particles. The conductive coating includes conductive nanomaterials.

[0264] The resistivity of the aforementioned single-particle active material particles is higher than that of existing secondary-particle-shaped positive electrode active materials, and the contact area with the conductive material is smaller, resulting in a decrease in conductivity. When excessive conductive material is added to improve conductivity, agglomeration occurs within the positive electrode slurry, increasing viscosity and thus reducing coatability. Therefore, to achieve good coatability, it is necessary to reduce the solid powder content and lower the viscosity of the positive electrode slurry. However, if the solid powder content in the positive electrode slurry is reduced, the active material content decreases, potentially reducing capacity characteristics. To solve this problem, this invention coats conductive nanomaterials onto the surface of the single-particle active material particles, thereby achieving good conductivity even without adding additional conductive material to the positive electrode slurry.

[0265] In one embodiment of the present invention, when a positive electrode active material is used in which conductive nanomaterials are coated on the surface of the aforementioned single-particle active material particles, the positive electrode active material layer may be free of conductive materials except for the conductive coating. This eliminates the need for additional conductive materials that cause agglomeration of the positive electrode slurry, thereby reducing the viscosity of the positive electrode slurry, increasing the solid powder content, and improving the electrode coating processability and electrode adhesion.

[0266] In this invention, the type of conductive nanomaterial is not particularly limited, as long as it is a material with a nanoscale size that can be easily coated onto particles and has conductivity. For example, the conductive nanomaterial can be carbon nanotubes, carbon nanoparticles, etc.

[0267] The aforementioned conductive nanomaterials can have various shapes, such as spherical, scaly, or fibrous.

[0268] On the other hand, the aforementioned conductive coating can be formed by heat treatment after mixing single-particle active material particles (serving as the core) with conductive nanomaterials. In this case, the mixing can be achieved through solid-phase mixing or liquid-phase mixing.

[0269] In one embodiment of the present invention, the aforementioned positive electrode active material layer comprises flake-shaped graphite. When the aforementioned single-particle active material is used as the positive electrode active material, if the positive electrode active material layer comprises flake-shaped graphite, then when the positive electrode active material layer is rolled, the flake-shaped graphite provides a sliding effect to the positive electrode active material, thereby improving the rolling characteristics of the electrode and reducing the electrode porosity to a target level. Therefore, a battery using the positive electrode according to the present invention can improve stability, initial resistance characteristics, and charge / discharge efficiency.

[0270] In one embodiment of the present invention, the above-mentioned flake graphite may be included in 0.1 wt% to 5 wt% of the above-mentioned positive electrode active material layer, and preferably in 0.1 wt% to 3 wt%.

[0271] When the content of flake graphite meets the above range, it improves the calendering characteristics of the positive electrode and can achieve good electrode density. If the content of flake graphite is too low, the effect of improving the calendering characteristics is negligible; if it is too high, it may cause an increase in slurry viscosity and a decrease in stability. Through its combination with conductive materials, the electrode uniformity decreases, which may increase the resistance.

[0272] On the other hand, the average particle size of the flake graphite used in this invention can be from 1 μm to 20 μm, preferably from 2 μm to 10 μm, and more preferably from 3 μm to 5 μm, but is not limited thereto. If the size of the flake graphite is too small, it is difficult to achieve the desired porosity, reducing the current density and potentially reducing the capacity. In this case, the average particle size of the flake graphite can be measured by laser diffraction (ISO 13320).

[0273] Furthermore, the aspect ratio of the aforementioned flake graphite can be from 0.1 to 500, preferably from 1 to 100, and more preferably from 1 to 30. When the aspect ratio of the flake graphite meets the above range, the conductivity is improved, resulting in a reduction in electrode resistance.

[0274] Furthermore, the density of the aforementioned flake graphite can be 2.0 g / cm³. 3 Up to 2.5g / cm 3 The preferred value is 2.1 g / cm³. 3 Up to 2.4 g / cm 3 A more preferred value is 2.2 g / cm³. 3 Up to 2.3 g / cm 3 .

[0275] On the other hand, in this invention, the porosity of the aforementioned positive electrode active material layer can be 15% to 23%, preferably 17% to 23%, and more preferably 18% to 23%. When the porosity of the positive electrode active material layer meets the above range, increasing the electrode density can achieve good capacity and reduce resistance. If the porosity is too low, the electrolyte impregnation decreases, which may lead to lithium deposition due to lack of impregnation in the electrolyte. If it is too high, the contact between the electrodes is poor, thereby increasing resistance and reducing energy density, so the capacity improvement effect is negligible.

[0276] The porosity value of the above-mentioned positive electrode active material layer can be achieved by i) the method of including single-particle active material particles in the above-mentioned positive electrode active material and ii) the method of adding flake graphite to the above-mentioned positive electrode active material.

[0277] When achieving a high-load electrode with a relatively high loading of the positive electrode active material layer, as in this invention, using a single-particle or similar single-particle shape of the positive electrode active material significantly reduces particle cracking of the active material during calendering compared to existing secondary particle-shaped positive electrode active materials, thus reducing damage to the positive electrode current collector (Al Foil). Therefore, calendering can be performed with a relatively high imprint line pressure, thereby reducing the porosity of the positive electrode active material layer to the range described above and improving the energy density.

[0278] Furthermore, in the case where the positive electrode active material layer contains flake graphite as in the present invention, the flake graphite provides a sliding effect during calendering, which can fill the voids in the positive electrode active material layer, so the porosity of the positive electrode active material layer can be reduced to the numerical range described above.

[0279] Furthermore, the loading amount of the aforementioned positive electrode can be 570 mg / 25 cm⁻¹. 2 The above is preferably 600mg / 25cm 2 Up to 800g / 25m 2 A more preferred value is 600mg / 25cm. 2 Up to 750mg / 25cm 2 Specifically, in the lithium secondary battery according to the present invention, by applying single-particle and / or similar single-particle positive electrode active materials and flake graphite, the rolling characteristics of the electrode are improved, so the loading amount of the positive electrode can be ensured at a relatively high level, thereby achieving high capacity characteristics.

[0280] In one embodiment of the present invention, the aforementioned positive electrode active material layer may further include a conductive material. The conductive material is used to impart conductivity to the electrode; any material that does not cause chemical changes within the battery and possesses conductivity can be used without particular limitation. Specific examples include graphite such as natural or artificial graphite; carbon-based materials such as carbon black, acetylene black, Ketjen black, channel black, furnace black, lampblack, carbon fiber, and carbon nanotubes; metal powders or 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 materials may be used alone, or a mixture of two or more may be used. Typically, the conductive material comprises 1 wt% to 30 wt% relative to the total weight of the positive electrode active material layer, preferably 1 wt% to 20 wt%, and more preferably 1 wt% to 10 wt%.

[0281] In one specific embodiment of the present invention, the conductive material may include carbon nanotubes.

[0282] In one embodiment of the present invention, the aforementioned positive electrode active material, as a conductive material, may include multi-walled carbon nanotubes with a high specific surface area and a small number of walls. The multi-walled carbon nanotubes may comprise 50 wt% or more, 70 wt% or more, 90 wt% or more, or 99 wt% or more of the conductive material in a 100 wt% composition. In a specific embodiment of the present invention, the conductive material is composed solely of the aforementioned multi-walled carbon nanotubes.

[0283] In this invention, the BET specific surface area of ​​the aforementioned multi-walled carbon nanotubes is 300 m². 2 / g to 500m 2 / g. To distinguish it from existing technologies, it is called "novel CNT".

[0284] Previously used carbon nanotubes (current CNTs) typically have a BET specific surface area of ​​less than 300 m². 2 / g. The novel CNT used in this invention ( Figure 20 ) and existing CNTs Figure 21 The scanning electron microscope images and the comparison results of physical properties () Figure 22 )as follows.

[0285] As can be seen from the above SEM images, the novel CNTs applicable to this invention are of the bundle type and have a multiwall structure. Compared with existing CNTs, they have a higher BET, a smaller wall number, and a smaller diameter.

[0286] When using secondary particle-shaped positive electrode active materials, sufficient conductivity can be achieved even when using existing CNTs at a level of 0.4wt% to 0.6wt%. However, the resistivity of single-particle or similar single-particle positive electrode active materials is higher than that of existing secondary particle-shaped positive electrode active materials, and the contact area with the conductive material is smaller, resulting in a decrease in conductivity. Therefore, in order to use CNTs with a BET specific surface area of ​​less than 300m², [further considerations are needed]. 2 To achieve sufficient conductivity with existing CNTs, the conductive material content needs to be above 0.9 wt%.

[0287] Figures 23 to 26 It is a graph showing the sheet resistance and high-temperature lifetime characteristics of different proportions of conductive materials when single particles or similar single particles are used as the positive electrode active material.

[0288] The graph above shows that when using single particles or similar single particles as the positive electrode active material, the amount of conductive material used needs to be increased compared to using existing positive electrode active materials with secondary particle shapes.

[0289] However, if the carbon nanotube content increases to above 0.9 wt%, agglomeration occurs in the cathode slurry, increasing viscosity and thus reducing coatability. Therefore, to achieve satisfactory coatability, it is necessary to reduce the solid powder content in the cathode slurry and lower its viscosity. However, if the solid powder content in the cathode slurry is reduced, the content of active material decreases, leading to a decline in capacity characteristics.

[0290] The inventors of this invention, through repeated research to solve this problem, discovered that by using a positive electrode active material that is a single-particle active material particle and a conductive material with a BET specific surface area of ​​300 m², a solution can be achieved. 2 / g to 500m 2 With a carbon nanotube content of / g, sufficient conductivity can be ensured with only a relatively small amount of carbon nanotubes. Thus, even if the solid powder content of the cathode slurry is formed at a high level of 70wt% to 80wt%, the slurry viscosity can be maintained at a low level.

[0291] Specifically, the carbon nanotubes used in this invention can have a BET specific surface area of ​​300 m². 2 / g to 500m 2 / g, preferably 300m 2 / g to 450m 2 / g of multi-walled carbon nanotubes. When the BET specific surface area meets the above range, sufficient conductivity can be ensured even with a small amount of carbon nanotubes.

[0292] Furthermore, the aforementioned carbon nanotubes can be multi-walled carbon nanotubes with a wall number of 2 to 8, preferably 2 to 6, and more preferably 3 to 6.

[0293] Furthermore, the diameter of the aforementioned carbon nanotubes can be 1 nm to 8 nm, preferably 3 nm to 8 nm, and more preferably 3 nm to 6 nm.

[0294] Relative to the total weight of the positive electrode active material layer, the aforementioned carbon nanotubes may contain less than 0.7 wt%, preferably 0.3 wt% to 0.7 wt%, and more preferably 0.4 wt% to 0.6 wt%. When the content of carbon nanotubes meets the above range, sufficient conductivity can be achieved, maintaining a high level of solid powder content in the positive electrode slurry, thereby forming a high content of positive electrode active material in the positive electrode active material layer, thus achieving good capacity characteristics.

[0295] Figure 27 The table shown illustrates the applicable BET specific surface area of ​​300m². 2 / g to 500m 2 / g of carbon nanotubes (novel CNTs) and their applicable BET of 200m 2 / g or more and less than 300m 2 The table above compares the solid content and viscosity of the cathode slurry with a carbon nanotube content of / g (existing CNTs), as well as the resistivity in the MP coating and MP interface layer. The table shows that, with the application of the new CNTs, even with a higher solid content in the cathode slurry compared to existing CNTs, it exhibits lower viscosity and better conductivity.

[0296] The aforementioned adhesive enhances the adhesion between multiple 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), poly(vinylidene fluoride-co-hexafluoropropylene) (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 materials can be used alone, or a mixture of two or more can be used. The adhesive comprises 1 wt% to 30 wt% relative to the total weight of the positive electrode active material layer, preferably 1 wt% to 20 wt%, and more preferably 1 wt% to 10 wt%.

[0297] Another aspect of the present invention relates to an electrode assembly including the above-mentioned 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 described above.

[0298] For example, the electrode assembly can be laminated in a state where a separator is sandwiched between the negative electrode and the positive electrode to form a stacked or stacked / folded structure, or wound to form a gel roll structure. Moreover, when forming the gel roll structure, a separator is additionally disposed on the outside to prevent the negative electrode and the positive electrode from contacting each other.

[0299] 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 can be configured to have a structure in which a negative electrode active material layer is formed on one or both surfaces of a strip-shaped negative electrode current collector, and the negative electrode active material layer can include a negative electrode active material, a conductive material, and an adhesive.

[0300] Specifically, the negative electrode is manufactured by the following method: a negative electrode slurry in which a negative electrode active material, a conductive material, and an adhesive are dispersed in a solvent such as dimethyl sulfoxide (DMSO), isopropyl alcohol, N-methylpyrrolidone (NMP), acetone, water, etc. is coated on one or both surfaces of a strip-shaped negative electrode current collector, the solvent of the negative electrode slurry is removed through a drying process, and then calendering is performed. By a method of not coating the negative electrode slurry in a part of the negative electrode current collector, for example, at one end of the negative electrode current collector, a negative electrode including an uncoated portion can be manufactured.

[0301] The negative electrode active material can use a compound capable of reversible insertion and deintercalation of lithium. Specific examples of the negative electrode active material 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 such as Sn and Al that can be alloyed with lithium; etc., and any one or a mixture of two or more thereof can be used.

[0302] In the present invention, the negative electrode can 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 their combination, preferably SiO y (where, 0 < y < 2). The silicon-based negative electrode active material has a high theoretical capacity, so when the silicon-based negative electrode active material is included, the capacity characteristics can be improved.

[0303] The above-mentioned silicon-based negative electrode active material can be a material coated with M b metal. At this time, the above-mentioned M b metal can be a group I metal element or a group II metal element. Specifically, it can be Li, Mg, etc. Specifically, the above-mentioned silicon-based negative electrode active material can be Si, SiO b coated with M y (where, 0 < y < 2), Si-C composite, etc. In the silicon-based negative electrode active material coated with metal, although the capacity of the active material decreases a little due to the coating element, it has a high efficiency, so a high energy density can be achieved.

[0304] Figure 44 is a graph showing the change in energy density according to the content of the silicon-based negative electrode active material and whether the silicon-based negative electrode active material is coated 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.

[0305] In Figure 44 , Low efficiency SiO means uncoated SiO, and Ultra-High efficiency SiO means SiO coated with Mg / Li. Through Figure 44 it can be known that as the content of the silicon-based negative electrode active material in the overall negative electrode active material increases, the energy density also increases. And it can be known that as the proportion of the coated silicon-based negative electrode active material in the silicon-based negative electrode active material increases, the improvement effect of the energy density is more excellent.

[0306] The above-mentioned silicon-based negative electrode active material may further include a carbon coating on the particle surface. At this time, based on the total weight of the silicon-based negative electrode active material, the amount of the carbon coating can be 20 wt% or less, preferably 1 - 20 wt%. The above-mentioned carbon coating can be formed by dry coating, wet coating, chemical vapor deposition (CVD), physical vapor deposition (PVD), atomic layer deposition (ALD), etc.

[0307] In one embodiment of the present invention, the above-mentioned silicon-based negative electrode active material may have a capacity of 1000 - 4000 mAh / g, and the initial efficiency may be about 60 - 95%.

[0308] In another other embodiment of the present invention, the D 50 of the above-mentioned silicon-based negative electrode active material may be 3 um to 8 um, Dmin ~D max It can be in the range of 0.5um to 30um.

[0309] The aforementioned negative electrode may also include carbon-based negative electrode active materials as needed. These carbon-based negative electrode active materials may include, for example, artificial graphite, natural graphite, graphitized carbon fiber, amorphous carbon, soft carbon, hard carbon, etc., but are not limited to these.

[0310] When a mixture of silicon-based and carbon-based negative electrode active materials is used as the negative electrode active material, the mixing ratio of the silicon-based and carbon-based negative electrode active materials can be 1:99 to 20:80 by weight, preferably 1:99 to 15:85, and more preferably 1:99 to 10:90.

[0311] The negative electrode active material may contain 80 wt% to 99 wt% relative to the total weight of the negative electrode active material layer, preferably 85 wt% to 99 wt%, and more preferably 90 wt% to 99 wt%.

[0312] As needed, the aforementioned negative electrode active material may also include one or more metals selected from lithium metal and metals such as Sn and Al that can be alloyed with lithium.

[0313] The aforementioned negative electrode current collector can be any negative electrode current collector commonly used in this technical field. For example, it can be made of copper, stainless steel, aluminum, nickel, titanium, sintered carbon, or aluminum-cadmium alloys with surface treatments of carbon, nickel, titanium, silver, etc., on the surface of copper or stainless steel. The aforementioned negative electrode current collector typically has a thickness of 3 μm to 500 μm, and similar to the positive electrode current collector, fine irregularities can be formed on its surface to enhance the bonding force of the negative electrode active material. For example, the negative electrode current collector can be used in various shapes such as thin films, sheets, foils, meshes, porous bodies, foams, and nonwoven fabrics.

[0314] The aforementioned conductive materials are used to impart conductivity to the negative electrode. Any material that does not cause chemical changes within the battery and possesses conductivity can be used without particular restriction. Examples of specific conductive materials include graphite such as natural or artificial graphite; carbon-based materials such as carbon black, acetylene black, Ketjen black, channel black, furnace black, lampblack, carbon fiber, and carbon nanotubes; metal powders or 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 materials can be used alone, or a mixture of two or more can be used. Typically, the conductive material comprises 1 wt% to 30 wt% relative to the total weight of the negative electrode active material layer, preferably 1 wt% to 20 wt%, and more preferably 1 wt% to 10 wt%.

[0315] The aforementioned adhesive enhances the adhesion between multiple negative electrode active material particles and the adhesion between the negative electrode active material and the negative electrode current collector. Specific examples of adhesives include polyvinylidene fluoride (PVDF), poly(vinylidene fluoride-co-hexafluoropropylene) (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 adhesives can be used alone or in mixtures of two or more. The adhesive comprises 1 wt% to 30 wt% relative to the total weight of the negative electrode active material layer, preferably 1 wt% to 20 wt%, and more preferably 1 wt% to 10 wt%.

[0316] The electrode assembly also includes a separator membrane disposed within the electrode assembly, sandwiched between the negative and positive electrodes. This separator membrane separates the negative and positive electrodes and provides a pathway for lithium ion movement. Any separator membrane commonly used as a separator in lithium batteries can be used without particular limitation.

[0317] Porous polymer membranes can be used as the separation membranes described above. For example, porous polymer membranes made of polyolefin-based polymers such as ethylene homopolymers, propylene homopolymers, ethylene / butene copolymers, ethylene / hexene copolymers, and ethylene / methacrylic acid copolymers, or laminates of two or more of these polymers, can be used. Alternatively, conventional porous nonwoven fabrics, such as those made of high-melting-point glass fiber or polyethylene terephthalate fiber, can be used. To ensure heat resistance or mechanical strength, coated separation membranes containing ceramic components or polymeric substances can also be used.

[0318] Another aspect of the present invention relates to a battery including the aforementioned electrode assembly. The battery houses the electrode assembly and electrolyte together within a battery case, which can be suitably selected without limitation from commonly used methods in the art, such as a bag or a metal can.

[0319] The electrolyte used in this invention can be any type of electrolyte suitable for lithium batteries, such as organic liquid electrolytes, inorganic liquid electrolytes, solid polymer electrolytes, gel polymer electrolytes, solid inorganic electrolytes, molten inorganic electrolytes, etc., without any particular limitation on its type.

[0320] Specifically, the electrolyte may include organic solvents and lithium salts.

[0321] As the aforementioned organic solvents, any solvent capable of acting as a medium for the movement of multiple ions participating in the electrochemical reaction of the battery can be used without any restrictions. Specifically, ester solvents such as methyl acetate, ethyl acetate, γ-butyrolactone, and ε-caprolactone can be used; ether solvents such as dibutyl ether or tetrahydrofuran; ketone solvents such as cyclohexanone; aromatic hydrocarbon solvents such as benzene and fluorobenzene; dimethyl carbonate (DMC), diethyl carbonate (DEC), methylethyl carbonate (MEC), ethylmethyl carbonate (EMC), ethylene carbonate (EC), and propylene carbonate can be used. Carbonate solvents such as carbonate (PC); alcohol solvents such as ethanol and isopropanol; nitriles such as R-CN (where R is a C2 to C20 straight-chain, branched, or cyclic hydrocarbon group, which may include double bonds, aromatic rings, or ether bonds); amines such as dimethylformamide; dioxolane solvents such as 1,3-dioxolane; or sulfolane solvents. Preferably, carbonate solvents are preferred, and more preferably, mixtures of cyclic carbonates (e.g., ethylene carbonate or propylene carbonate, etc.) with high ionic conductivity and high dielectric constant that can improve the charge and discharge performance of the battery, and low-viscosity linear carbonate compounds (e.g., ethyl methyl carbonate, dimethyl carbonate, or diethyl carbonate, etc.).

[0322] As the aforementioned lithium salt, any compound capable of providing lithium ions for lithium batteries can be used without any limitation. Specifically, the aforementioned lithium salt can be LiPF6, LiClO4, LiAsF6, LiBF4, LiSbF6, LiAlO4, LiAlCl4, LiCF3SO3, LiC4F9SO3, LiN(C2F5SO3)2, LiN(C2F5SO2)2, LiN(CF3SO2)2, LiCl, LiI, or LiB(C2O4)2, etc. Ideally, the concentration of the aforementioned lithium salt is in the range of 0.1M to 5.0M, preferably in the range of 0.1M to 3.0M. If the concentration of the lithium salt is within the above range, the electrolyte has appropriate conductivity and viscosity, thus exhibiting good electrolyte performance, and lithium ions can move efficiently.

[0323] In addition to the constituent components of the electrolyte, the electrolyte may further include additives to improve battery life characteristics, suppress battery capacity reduction, and increase battery discharge capacity. For example, additives may be used alone or in combination with haloalkylene carbonates such as difluoroethylene carbonate, pyridine, triethyl phosphite, triethanolamine, cyclic ethers, ethylenediamine, N-glycol dimethyl ether, hexamethylphosphoric triamine, nitrobenzene derivatives, sulfur, quinone imine dyes, N-substituted oxazolidinones, N,N-substituted imidazolides, ethylene glycol dialkyl ethers, ammonium salts, pyrroles, dimethoxyethanol, or aluminum trichloride, but are not limited thereto. The additives may comprise 0.1 wt% to 10 wt% relative to the total weight of the electrolyte, preferably 0.1 wt% to 5 wt%.

[0324] In another embodiment of the invention, the positive electrode may include a load reduction section where the loading of positive electrode active material is less than that of adjacent regions. If the positive electrode has such a structure, the area of ​​the positive electrode active material section can be increased without concern about lithium deposition. This, in turn, improves the energy density of the electrode assembly.

[0325] Recently, research has focused on increasing battery size to achieve high energy density and reduce costs. Depending on the battery size, the resistance of each cell should decrease as energy increases. To reduce resistance, the current collector of the electrode can be used as an electrode tab instead of attaching electrode tabs to the electrode. However, due to the characteristics of the electrode manufacturing process where electrode paste is coated onto the current collector, a portion with reduced loading occurs at the boundary between the negative electrode active material portion coated with negative electrode paste and the negative electrode current collector. Considering the N / P ratio, lithium metal deposition may occur in the positive electrode active material portion facing the aforementioned portion with reduced loading. The N / P ratio is the value of the negative electrode capacity calculated based on the area and capacity per unit mass of the negative electrode, divided by the positive electrode capacity obtained based on the area and capacity per unit mass of the positive electrode; it is typically greater than 1. That is, it is manufactured to have a higher negative electrode capacity. For reference, if the N / P ratio is less than 1, lithium metal deposition is more likely during charge and discharge, which will drastically deteriorate battery safety during high-rate charge and discharge. In other words, the N / Pratio has a significant impact on battery safety and capacity. As mentioned above, due to concerns about lithium metal deposition, the positive electrode active material portion can be located in the positive electrode portion facing the portion with reduced negative electrode loading. This is a reason why it is impossible to increase the battery's energy density. Therefore, the present invention improves energy density by expanding the range of the positive electrode active material portion.

[0326] Figure 32 This is a diagram illustrating an electrode assembly according to an embodiment of the present invention. Figure 33 It shows along Figure 32 A cross-sectional view of the section cut by the cutting line A-A'.

[0327] Reference Figure 32 as well as Figure 33 According to an embodiment of the present invention, an electrode assembly 300 includes a negative electrode 400, a positive electrode 500, and a separation membrane 600. The separation membrane 600 is located between the negative electrode 400 and the positive electrode 500. The negative electrode 400, the positive electrode 500, and the separation membrane 600 are wound together to form a gel roll structure 300S. The gel roll structure 300S refers to a structure formed by winding the negative electrode 400, the positive electrode 500, and the separation membrane 600. Furthermore, to prevent the negative electrode 400 and the positive electrode 500 from contacting each other when the gel roll structure 300S is formed, it is preferable to additionally arrange the separation membrane 600 on the outer side.

[0328] The negative electrode 400 includes a negative electrode current collector 410 and a negative electrode active material portion 420 formed by coating the negative electrode current collector 410 with a negative electrode active material. In particular, as shown, the negative electrode active material portion 420 can be formed by coating both sides of the negative electrode current collector 410 with a negative electrode active material. Furthermore, the uncoated negative electrode portion 430 in the negative electrode current collector 410 extends in the first direction d1. The uncoated negative electrode portion 430 is continuous along one end of the wound negative electrode 400. Moreover, the uncoated negative electrode portion 430 extends further in the first direction d1 than the separation membrane 600. Therefore, the uncoated negative electrode portion 430 can be exposed at one end of the gel roll structure 300S in the first direction.

[0329] The positive electrode 500 includes a positive electrode current collector 510 and a positive electrode active material portion 520 formed by coating the positive electrode current collector 510 with a positive electrode active material. In particular, as shown, the positive electrode active material portion 520 can be formed by coating both sides of the positive electrode current collector 510 with a positive electrode active material. Furthermore, the uncoated portion 530 of the positive electrode in the positive electrode current collector 510 extends in the second direction d2. The uncoated portion 530 is continuous along one end of the wound positive electrode 500. Moreover, the uncoated portion 530 extends further in the second direction d2 than the separation membrane 600. Therefore, the uncoated portion 530 can be exposed at one end of the gel roll structure 300S in the second direction.

[0330] Wherein, the first direction d1 and the second direction d2 are directions opposite to each other. Furthermore, the first direction d1 and the second direction d2 can be directions parallel to the height direction of the gel roll structure 300S.

[0331] According to this embodiment, the electrode assembly 300 uses the uncoated negative portion 430 of the negative current collector 410 and the uncoated positive portion 530 of the positive current collector 510 as the shape of the electrode tabs themselves, rather than attaching other electrode tabs.

[0332] Although not shown in the accompanying drawings, the uncoated negative electrode portion 430 and / or the uncoated positive electrode portion 530 may have a structure substantially the same as the structure of the uncoated portion of the electrode described above.

[0333] In one embodiment, the positive electrode active material section 520 includes a loading reduction section 500D in which the loading amount of positive electrode active material is less than that of the adjacent region, and the loading reduction section 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 in the loading reduction section 500D can gradually decrease as it moves toward the first direction d1.

[0334] Here, "load amount" refers to the amount of active material coated per unit area. A higher load amount means more negative or positive active material is coated per unit area, resulting in a relatively thicker negative or positive active material section. Conversely, a lower load amount means less negative or positive active material is coated per unit area, resulting in a relatively thinner negative or positive active material section.

[0335] An active material portion can be formed by coating a slurry containing an active material. In this process, a boundary portion with a gradually decreasing loading amount may be formed between the uncoated portion and the active material portion.

[0336] Specifically, the negative electrode active material portion 420 may include a negative electrode boundary portion 420B that forms the boundary between the negative electrode active material portion 420 and the negative electrode uncoated portion 430. The loading amount of the negative electrode boundary portion 420B may decrease in the direction toward the negative electrode uncoated portion 430.

[0337] Similarly, the positive electrode active material portion 520 may include a positive electrode boundary portion 520B that forms the boundary between the positive electrode active material portion 520 and the positive electrode uncoated portion 530. The loading amount of the positive electrode boundary portion 520B may decrease in the direction toward the positive electrode uncoated portion 530.

[0338] As described above, the negative electrode boundary portion 420B or the positive electrode boundary portion 520B, with the loading amount gradually decreasing, naturally appears during the process of coating the negative electrode current collector 410 or the positive electrode current collector 510 with a slurry containing active material.

[0339] At this point, taking the direction perpendicular to the second direction d2 as a reference, in the region corresponding to the positive electrode boundary 520B, the amount of positive electrode active material can be less than the amount of negative electrode active material. This is because the N / P ratio has a value greater than 1, and problems such as lithium metal deposition will not occur.

[0340] The problem lies in the region corresponding to the negative electrode boundary 420B. Taking the direction perpendicular to the first direction d1 as a reference, in the region corresponding to the negative electrode boundary 420B, the amount of negative electrode active material can be less than the amount of positive electrode active material. This is because the N / Pratio has a value less than 1, which may lead to lithium metal deposition.

[0341] Therefore, in this embodiment, a load reduction portion 500D is formed on the positive electrode 500, and the negative electrode active material portion 420 can be located in the portion corresponding to the load reduction portion 500D, with the direction perpendicular to the first direction d1 as a reference. More specifically, the negative electrode boundary portion 420B can be located in the portion corresponding to the load reduction portion 500D, with the direction perpendicular to the first direction d1 as a reference.

[0342] A loading reduction section 500D, where the loading of positive electrode active material is less than that of adjacent regions, is provided at a position corresponding to the negative electrode boundary 420B where the loading gradually decreases. This allows for an increase in the area coated with positive electrode active material without concern about lithium deposition. In particular, the loading reduction section 500D can have a shape where the loading of positive electrode active material gradually decreases towards the first direction d1, corresponding to the shape of the negative electrode boundary 420B where the loading gradually decreases towards the direction of the uncoated negative electrode portion 430. Therefore, the N / P ratio for the negative electrode 400 and the positive electrode 500 in the region where the negative electrode boundary 420B is formed can be maintained at a high level, thereby preventing lithium deposition.

[0343] Below, refer to Figures 34 to 39 A method for manufacturing an electrode assembly according to an embodiment of the present invention will be described in detail.

[0344] Figure 34 as well as Figure 35 This is a diagram illustrating the process of manufacturing a negative electrode according to an embodiment of the present invention. Specifically, Figure 34 This is a plan view of the negative electrode tab from above. Figure 35 View from the front Figure 34 A front view of the negative electrode tab.

[0345] Reference Figure 34 as well as Figure 35 According to an embodiment of the present invention, a method for manufacturing an electrode assembly includes the step of manufacturing a negative electrode tab 400S in such a manner that a negative electrode active material portion 420 coated with a negative electrode active material and a negative electrode uncoated portion 430 uncoated with a negative electrode active material are alternately positioned on a negative electrode current collector 410.

[0346] Specifically, a negative electrode active material portion 420 can be formed by coating a negative electrode active material, making it continuous along a third direction d3. Furthermore, the coating area is separated along a fourth direction d4 perpendicular to the third direction d3, thereby positioning the plurality of negative electrode active material portions 420 separately along the fourth direction d4. That is, the coating process can be performed such that the uncoated negative electrode portion 430 is located between the plurality of negative electrode active material portions 420.

[0347] Among them, the third direction d3 and the fourth direction d4 are directions described with reference to the negative electrode tab 400S, and are directions that are unrelated to the first direction d1 and the second direction d2 in the gel roll structure 300S described above.

[0348] Then, the negative electrode 400 can be manufactured by slitting the uncoated negative electrode portion 430 and the negative electrode active material portion 420. Figure 36 This is a perspective view showing the negative electrode according to an embodiment of the present invention.

[0349] Reference Figures 34 to 36 , such as in Figure 34 as well as Figure 35 The portion indicated by the dashed line represents the area where each of the uncoated negative electrode portion 430 and the active negative electrode portion 420 can be cut along a direction parallel to the third direction d3. This allows for the fabrication of multiple negative electrode tabs 400S. Figure 36 This is the negative electrode 400 shown. That is, Figure 36 The negative electrode 400 is equivalent to for Figure 34 as well as Figure 35 One of a plurality of negative electrodes manufactured by cutting open the negative electrode tab 400S. By cutting out the uncoated negative electrode portion 430 and the active negative electrode portion 420 in the negative electrode tab 400S, a negative electrode 400 with the uncoated negative electrode portion 430 extending to one side can be manufactured.

[0350] When forming the negative electrode active material portion 420, a slurry containing the negative electrode active material can be coated onto the negative electrode current collector 410. During the coating process of this slurry, a negative electrode boundary portion 420B can be formed between the negative electrode active material portion 420 and the negative electrode uncoated portion 430, wherein the loading amount decreases as it moves toward the negative electrode uncoated portion 430.

[0351] Figure 37 as well as Figure 38 This is a diagram illustrating the process of manufacturing a positive electrode according to an embodiment of the present invention. Specifically, Figure 37 This is a plan view of the positive electrode tab from above. Figure 38 View from the front Figure 37 A front view of the positive electrode tab.

[0352] Reference Figure 37 as well as Figure 38 According to an embodiment of the present invention, a method for manufacturing an electrode assembly includes the step of manufacturing a positive electrode tab 500S in such a manner that a positive electrode active material portion 520 coated with a positive electrode active material and a positive electrode uncoated portion 530 uncoated with a positive electrode active material are alternately positioned on a positive electrode current collector 510.

[0353] Specifically, a positive electrode active material can be coated to form a positive electrode active material portion 520, which is continuous along a third direction d3. Furthermore, the coating interval is adjusted along a fourth direction d4 perpendicular to the third direction d3, thereby positioning the multiple positive electrode active material portions 520 separately. That is, the coating process can be performed such that the uncoated positive electrode portion 530 is located between the multiple positive electrode active material portions 520.

[0354] Among them, the third direction d3 and the fourth direction d4 are directions described with reference to the positive electrode tab 500S, and are directions that are unrelated to the first direction d1 and the second direction d2 in the gel roll structure 300S described above.

[0355] Then, the positive electrode 500 can be manufactured by cutting open the uncoated portion 530 and the active material portion 220. Figure 39 This is a perspective view showing a positive electrode 500 according to an embodiment of the present invention.

[0356] Reference Figures 37 to 39 , such as in Figure 37 as well as Figure 38 The portion indicated by the dashed line represents the area where each of the uncoated positive electrode portion 530 and the positive electrode active material portion 520 can be cut along a direction parallel to the third direction d3. This allows for the fabrication of multiple positive electrode tabs 500S. Figure 39 The positive electrode shown is 500. That is, Figure 39 The positive electrode 500 is equivalent to for Figure 37 as well as Figure 38 One of a plurality of positive electrodes manufactured by cutting open the positive electrode tab 500S. By cutting out the uncoated portion 530 and the active material portion 520 of the positive electrode tab 500S respectively, it is possible to manufacture a positive electrode 500 in which the uncoated portion 530 extends to one side.

[0357] When forming the positive electrode active material portion 520, a slurry containing the positive electrode active material can be coated onto the positive electrode current collector 510. During the coating process of this slurry, a positive electrode boundary portion 520B can be formed between the positive electrode active material portion 520 and the positive electrode uncoated portion 530, wherein the loading amount decreases as it moves toward the positive electrode uncoated portion 530.

[0358] Refer to together Figure 32 , Figure 36 as well as Figure 39 The next step is to roll up the manufactured negative electrode 400 and positive electrode 500 together with the separation membrane 600 to form a gel roll structure 300S. In this case, in the gel roll structure 300S, the uncoated portion 430 of the negative electrode can extend in the first direction d1 longer than the separation membrane 600, and the uncoated portion 530 of the positive electrode can extend in the second direction d2 opposite to the first direction d1 longer than the separation membrane 600.

[0359] Refer again Figures 37 to 39In a method for manufacturing an electrode assembly according to an embodiment of the present invention, the positive electrode tab 500S includes a load reduction region 500DA in which the loading amount of the positive electrode active material is less than that of the adjacent region. The method for forming the load reduction region 500DA is not limited in its characteristics; for example, it can be formed by adjusting the degree of slurry coating.

[0360] In the step of manufacturing the above-mentioned positive electrode 500, a loading reduction region 500DA is cut out in the positive electrode active material portion 520. The cut loading reduction region 500DA is formed. Figure 32 as well as Figure 33 The shown gel roll structure 300S has a reduced loading of positive electrode active material in a region 500D where the loading is less than that in adjacent regions.

[0361] Specifically, a load reduction region 500DA is formed in the positive electrode active material portion 520 formed on the positive electrode tab 500S, where the loading amount of the aforementioned positive electrode active material is less than that of the adjacent region. For example... Figure 38 As shown, the load reduction region 500DA can be formed in the center of the positive electrode active material portion 520. On the other hand, the load reduction region 500DA can be configured such that the loading amount of the positive electrode active material gradually decreases towards the center portion 500C of the load reduction region 500DA. By cutting open the center portion 500C of the load reduction region 500DA in the step of manufacturing the positive electrode 500, the load reduction portion 500D according to this embodiment can be formed.

[0362] That is, when coating a slurry containing a positive electrode active material, a load reduction region 500DA is formed, and the central portion 500C of the load reduction region 500DA is cut open, thereby producing multiple positive electrodes 500 with load reduction portions 500D formed thereon.

[0363] Reference Figure 39 One end of the manufactured positive electrode 500 may have a load reduction portion 500D, and the other end of the positive electrode 500 facing the aforementioned one end may have a positive electrode uncoated portion 530.

[0364] Reference Figure 32 as well as Figure 33 When this positive electrode 500 is wound up to form a gel roll structure 300S, the load reduction portion 500D can be located at one end of the positive electrode 500 in the first direction d1, and the uncoated portion 530 of the positive electrode is located at one end of the positive electrode 500 in the second direction d2.

[0365] Furthermore, by cutting open the central portion 500C of the load reduction region 500DA, the loading amount of positive electrode active material in the load reduction portion 500D can be gradually reduced as it moves toward the first direction d1.

[0366] Furthermore, in the gel roll structure 300S, with a reference direction perpendicular to the first direction d1, the negative electrode active material portion 420 may be located in the portion corresponding to the load reduction portion 500D. More specifically, in the gel roll structure 300S, with a reference direction perpendicular to the first direction d1, the negative electrode boundary portion 420B may be located in the portion corresponding to the load reduction portion 500D.

[0367] The corresponding positional relationship between the load reduction section 500D and the negative electrode boundary section 420B is repeated from the above description, so the description is omitted.

[0368] Below, refer to Figures 40 to 43 The electrode assembly according to the comparative example of the present invention will be described, and the advantages of the electrode assembly according to this embodiment compared with the electrode assembly according to the comparative example will be explained.

[0369] Figure 40 This is a diagram illustrating an electrode assembly according to a comparative example of the present invention. Figure 41 It shows along Figure 40 A cross-sectional view of the section cut by the cutting line B-B'.

[0370] Reference Figure 40 as well as Figure 41 According to the comparative example of the present invention, the electrode assembly 600 includes a negative electrode 700, a positive electrode 800, and a separation membrane 900, wherein the negative electrode 700, the positive electrode 800, and the separation membrane 900 are wound up to form a gel roll structure 600S.

[0371] The negative electrode 700 may include a negative electrode current collector 710, a negative electrode active material portion 720, and a negative electrode uncoated portion 730. Furthermore, the negative electrode uncoated portion 730 may extend in a first direction d1, and the negative electrode active material portion 720 may include a negative electrode boundary portion 720B that forms the boundary between the negative electrode active material portion 720 and the negative electrode uncoated portion 730 and whose loading amount gradually decreases.

[0372] Figure 42 This is a diagram illustrating the process of manufacturing the negative electrode 700 according to a comparative example of the present invention.

[0373] Reference Figure 42 A negative electrode tab 700S is manufactured by alternately positioning the negative electrode active material portion 720 and the negative electrode uncoated portion 730 in the fourth direction d4. Then, the negative electrode uncoated portion 730 and the negative electrode active material portion 720 are slitting to manufacture multiple negative electrodes 700.

[0374] On the other hand, refer to again Figure 40 as well as Figure 41The positive electrode 800 may include a positive electrode current collector 810, a positive electrode active material portion 820, and a positive electrode uncoated portion 880. Furthermore, the positive electrode uncoated portion 830 may extend in a second direction d2 opposite to the first direction d1, and the positive electrode active material portion 820 may include a positive electrode boundary portion 820B that forms the boundary between the positive electrode active material portion 820 and the positive electrode uncoated portion 830 and whose loading amount gradually decreases.

[0375] Figure 43 This is a diagram illustrating the process of manufacturing the positive electrode 800 according to a comparative example of the present invention.

[0376] Reference Figure 43 A positive electrode tab 800S is manufactured by alternately positioning the positive electrode active material part 820 and the positive electrode uncoated part 830 in the fourth direction d4. Then, the positive electrode uncoated part 830 and the positive electrode active material part 820 are slitting to manufacture multiple positive electrodes 800.

[0377] The manufactured negative electrode 700 and positive electrode 800 are then wound together with the separation membrane 900 to manufacture the electrode assembly 600 according to the comparative example of the present invention.

[0378] That is, except for the load reduction section 500D (refer to...) Figure 33 In addition, the electrode assembly 600 according to the comparative example of the present invention may have a structure similar to that of the electrode assembly 300 according to this embodiment.

[0379] Reference Figure 40 as well as Figure 41 According to the electrode assembly 600 of this comparative example, with the direction perpendicular to the first direction d1 as a reference, 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 has a lower N / P ratio value, and the possibility of lithium metal deposition is higher. Therefore, in order to prevent lithium deposition, the length of the positive electrode active material portion 820 must be limited. That is, the positive electrode active material portion 820 can only be formed in the region B1 shown, and the positive electrode active material portion 820 cannot be formed in the region B2. This results in a reduction in the length of the positive electrode active material portion 820 due to the negative electrode boundary portion 720B.

[0380] Conversely, refer to Figure 32 as well as Figure 33According to the electrode assembly 300 of this embodiment, with a direction perpendicular to the first direction d1 as a reference, the positive electrode active material portion 520 can be located in the portion corresponding to the negative electrode boundary portion 420B, and in particular, the load reduction portion 500D can be located in the portion corresponding to the negative electrode boundary portion 420B. By forming the load reduction portion 500D, where the load of the positive electrode active material is less than that of the adjacent region, at the position corresponding to the negative electrode boundary portion 420B, the N / Pratio in the corresponding portion can be maintained at a high level, preventing lithium deposition. Thus, the positive electrode active material portion 520 corresponding to region A1 can be formed, and the region A2, where the positive electrode active material portion 520 cannot be formed, can be reduced. As an example, the ratio of the width of the positive electrode 500 in the height direction to the width of the negative electrode 400 in the height direction can be increased to 98% or more.

[0381] contrast Figure 32 as well as Figure 33 The A1 area and Figure 40 as well as Figure 41 In region B1, the electrode assembly 300 according to this embodiment can increase the length of the positive electrode active material portion by an amount equivalent to the load reduction portion 500D, so it can have a higher energy density in a limited space compared to the electrode assembly 600 according to the comparative example.

[0382] Another aspect of the present invention relates to a cylindrical battery, comprising: a gel roll type electrode assembly having a positive electrode, a negative electrode, and a separator sandwiched between the positive and negative electrodes, wound in one direction; a cylindrical battery housing for housing the electrode assembly; and a battery cap disposed on the upper part of the battery housing for sealing the battery housing. The positive electrode is according to the present invention, and the positive electrode active material comprises an average particle size D. 50 The active material consists of single particles smaller than 5 μm. The aforementioned cylindrical battery may also include an electrolyte; details regarding the electrolyte can be found above.

[0383] The electrode assembly described above can have a stacked, stacked / folded, or gel roll-type structure as described above. In a specific embodiment of the present invention, the electrode assembly can be an electrode assembly with a load reduction portion at the positive electrode, as described above.

[0384] In existing cylindrical batteries, the current is concentrated in the strip-shaped electrode tabs, resulting in problems such as high resistance, excessive heat generation, and poor current collection efficiency.

[0385] With the recent development of electric vehicle technology, the demand for high-capacity batteries has increased, necessitating the development of large-volume cylindrical batteries. Previously used small cylindrical batteries, with form factors of 1865 or 2170, did not exhibit significant impacts on battery performance due to their small capacity and the absence of resistance or heat generation. However, directly applying the specifications of these smaller cylindrical batteries to larger cylindrical batteries could potentially lead to serious battery safety issues.

[0386] This is because as the battery size increases, the amount of heat and gas generated inside the battery also increases. This heat and gas cause the internal temperature and pressure to rise, potentially leading to a fire or explosion. To prevent this, the heat and gas inside the battery should be properly vented to the outside. Therefore, the cross-sectional area of ​​the battery, which serves as a channel for venting heat to the outside, needs to increase proportionally to the increase in volume. However, the increase in cross-sectional area usually does not match the increase in volume. Therefore, as batteries become larger, the heat generated inside the battery increases, leading to increased explosion risk and reduced output. Furthermore, during rapid charging at high voltage, a large amount of heat is generated around the electrode tabs in a short time, potentially causing a battery fire. Therefore, this invention discloses a cylindrical battery with a larger volume to achieve high capacity and safety.

[0387] Furthermore, the high-load electrode using the aforementioned single-particle or similar single-particle shaped positive electrode active material can be applied to cylindrical batteries, thus improving the initial resistance characteristics and charging / discharging efficiency of cylindrical batteries.

[0388] The cylindrical battery according to the present invention uses a positive electrode active material with a single particle or similar single particle shape, which significantly reduces the amount of gas generated compared to the past, thereby achieving good safety even in large cylindrical batteries with a shape factor ratio of 0.4 or higher.

[0389] Preferably, the cylindrical battery according to the present invention can be a tabless-less battery without electrode tabs, but it is not limited thereto.

[0390] The aforementioned tabless structure battery can be, for example, the following structure: the positive electrode and the negative electrode each include an uncoated portion without an active material layer, the uncoated positive electrode portion and the uncoated negative electrode portion are located at the upper end and the lower end of the electrode assembly respectively, the current collector is combined with the aforementioned uncoated positive electrode portion and the uncoated negative electrode portion, and the current collector is connected to the electrode terminals.

[0391] When a cylindrical battery is formed into a tabless structure as described above, the current concentration is low compared to existing batteries with electrode tabs, thus efficiently reducing internal heat generation and improving the battery's thermal safety.

[0392] The present invention will now be described in further detail through specific embodiments.

[0393] Example 1

[0394] In N-methylpyrrolidone, a mixture with an average particle size D was prepared at a weight ratio of 97.8:0.6:1.6. 50 The positive electrode active material, Li[Ni], exhibits a single-peak particle size distribution of 3 μm and is a single-particle shape. 0.9 Co 0.06 Mn 0.03 Al 0.01 O2: Carbon nanotubes: PVDF binder, thereby producing a positive electrode slurry. The above positive electrode slurry is coated on one side of an aluminum current collector sheet, then dried at 120°C, and then rolled to produce the positive electrode.

[0395] A negative electrode slurry is prepared by mixing the negative electrode active material (graphite:SiO = 95:5 weight ratio mixture), conductive material (super C), styrene-butadiene rubber (SBR), and carboxymethyl cellulose (CMC) in water at a weight ratio of 96:2:1.5:0.5. This negative electrode slurry is then coated onto one side of a copper current collector sheet, dried at 150°C, and subsequently calendered to produce the negative electrode.

[0396] A separator membrane is sandwiched between the positive and negative electrodes manufactured as described above, and then layered in the order of separator membrane / positive electrode / separator membrane / negative electrode and wound up to produce a gel roll type electrode assembly. The electrode assembly manufactured as described above is inserted into a battery can and then electrolyte is injected to produce a 4680 battery cell.

[0397] Comparative Example 1

[0398] In addition to using a large average particle size D as the positive electrode active material, 50 The average particle size D is 9 μm. 50 Li[Ni] has a bimodal particle size distribution of 4 μm and is a secondary particle shape. 0.9 Co 0.05 Mn 0.04 Al 0.01 Apart from O2, the 4680 battery cell was manufactured using the same method as in Example 1.

[0399] Experimental Example 1

[0400] A hot box test was performed on the 4680 battery cells manufactured using Example 1 and Comparative Example 1.

[0401] Specifically, the 4680 battery cells manufactured using Example 1 and Comparative Example 1 were placed in a hot box chamber at room temperature for evaluation. The temperature was increased to 130°C at a rate of 5°C / min and maintained for 30 minutes. The temperature change of the battery over time was measured. To ensure accurate evaluation, the battery cell from Example 1 underwent two hot box evaluations. Figure 29a as well as Figure 29b The measurement results are shown.

[0402] Figure 29a This is a graph showing the hot box test results of the 4680 battery cell manufactured according to Example 1. Figure 29b This is a graph showing the hot box test results of the 4680 battery cell manufactured using Comparative Example 1.

[0403] pass Figure 29a as well as Figure 29b It can be seen that the lithium secondary battery of Example 1, which uses a single-particle positive electrode active material, maintained stable battery voltage and temperature until 65 minutes. In contrast, the lithium secondary battery of Comparative Example 1 showed a rapid increase in battery temperature after 35 minutes.

[0404] Example 2-1

[0405] Prepared with unimodal particle size distribution and D min =1.78μm, D 50 =4.23μm, D max =13.1μm and mixed with single particles and similar single particles of positive electrode active material (composition: Li [Ni 0.9 Co 0.06 Mn 0.03 Al 0.01 O2). Figure 28a SEM images of the positive electrode active material used in Example 2-1 are shown.

[0406] A positive electrode slurry was prepared by mixing positive electrode active material, carbon nanotubes, and PVDF binder in N-methylpyrrolidone at a weight ratio of 97.8:0.6:1.6. This positive electrode slurry was then coated onto one side of an aluminum current collector sheet, dried at 120°C, and subsequently rolled to produce the positive electrode.

[0407] A negative electrode slurry is prepared by mixing the negative electrode active material (graphite:SiO = 95:5 by weight), conductive material (Super C), styrene-butadiene rubber (SBR), and carboxymethyl cellulose (CMC) in water at a weight ratio of 96:2:1.5:0.5. This negative electrode slurry is then coated onto one side of a copper current collector sheet, dried at 150°C, and subsequently calendered to produce the negative electrode.

[0408] A separator membrane is sandwiched between the positive and negative electrodes manufactured as described above, and then layered in the order of separator membrane / positive electrode / separator membrane / negative electrode and wound up to produce a gel roll type electrode assembly. The electrode assembly manufactured as described above is inserted into a battery can and then electrolyte is injected to produce a 4680 battery cell.

[0409] Example 2-2

[0410] In addition to being used as a positive electrode active material, it also has a unimodal particle size distribution and D min =1.38μm, D 50 =4.69μm, D max =18.5μm and mixed with single particles and similar single particles of positive electrode active material (composition: Li [Ni 0.9 Co 0.06 Mn 0.03 Al 0.01 Apart from O2), the 4680 battery cell was manufactured using the same method as in Example 2-1. Figure 28b SEM images of the positive electrode active material used in Examples 2-2 are shown.

[0411] Comparative Example 2-1

[0412] In addition to being used as a positive electrode active material, it also has an average particle size D with a large particle size. 50 The average particle size D is 9 μm. 50 The positive electrode active material has a bimodal particle size distribution of 4 μm and is a secondary particle shape (composition: Li [Ni 0.9 Co 0.05 Mn 0.04 Al 0.01 Apart from O2), the 4680 battery cell was manufactured using the same method as in Example 2-1.

[0413] Comparative Example 2-2

[0414] In addition to being used as a positive electrode active material, it also has a unimodal particle size distribution and D min =0.892μm, D 50 =3.02μm, D max =11μm and mixed with single particles and similar single particles of positive electrode active material (composition: Li [Ni0.9 Co 0.06 Mn 0.03 Al 0.01 Apart from O2), the 4680 battery cell was manufactured using the same method as in Example 2-1.

[0415] Figure 28c SEM images of the positive electrode active material used in Comparative Example 2-2 are shown.

[0416] Experimental Example 2-1

[0417] Hot box tests were performed on the 4680 battery cells manufactured using Examples 2-1 to 2-2 and Comparative Examples 2-1 to 2-2.

[0418] Specifically, each of the 4680 battery cells manufactured using Example 2-1 and Comparative Example 2-1 was placed in a hot box chamber at room temperature and heated to 130°C at a rate of 5°C / min, then maintained at that temperature for 30 minutes. The temperature change of the battery was then measured. A test without thermal runaway or fire was recorded as "Pass," while a test with thermal runaway and / or fire was recorded as "Fail." Furthermore, to ensure accuracy, the battery cells from Examples 2-1 to 2-2 were tested at least twice.

[0419] Table 1 below and Figure 29c , Figure 29d The test results are shown. Figure 29c This is a graph showing the hot box test results of Sample 1 of Example 2-1 and the 4680 battery cell manufactured by Comparative Example 2-1. Figure 29d The graph shows the hot box test results of samples 2 and 3 of Example 2-1, samples 1 and 2 of Example 2-2, and the 4680 battery cell manufactured by Comparative Example 2-2.

[0420] Table 1

[0421]

[0422] Refer to Table 1 above. Figure 29c as well as Figure 29d It can be seen that using D min In Example 2-1, the 4680 battery cell using a single-particle / similar-particle shape positive electrode active material larger than 1.0 μm stably maintained its voltage and temperature for up to 65 minutes. Conversely, in Comparative Example 2-1, which used secondary particles as the positive electrode active material, and in the example using D… minThe 4680 battery cells of Comparative Example 2-2, which contain single-particle / similar-particle shaped positive electrode active materials smaller than 1.0 μm, exhibited a rapid temperature rise.

[0423] Experimental Example 2-2

[0424] To confirm the degree of cracking of the positive electrode active material particles after rolling in Example 2-1 and Comparative Example 2-1, the cross-section of the positive electrode was photographed using SEM after being cut with an ion milling device. Figure 30a A cross-sectional SEM image of the positive electrode manufactured in Example 2-1 is shown. Figure 30b A cross-sectional SEM image of the positive electrode fabricated in Comparative Example 2-1 is shown.

[0425] pass Figure 30a as well as Figure 30b It can be observed that the cathode of Example 2-1 showed almost no particle cracking of the cathode active material after calendering. In contrast, the cathode of Comparative Example 2-2, which used secondary particles, showed a lot of particle cracking of the cathode active material after calendering.

[0426] Example 3-1

[0427] In N-methylpyrrolidone, a mixture with a unimodal particle size distribution and D was prepared at a weight ratio of 96.3:1.5:0.4:1.8. min =1.78μm, D 50 =4.23μm, D max =13.1μm and mixed with single particles and similar single particles of positive electrode active material powder (composition: Li [Ni 0.9 Co 0.06 Mn 0.03 Al 0.01 A positive electrode slurry was prepared using O2, flake graphite (SFG6L), a conductive material (multi-walled carbon nanotubes), and a PVDF binder. This positive electrode slurry was coated onto one side of an aluminum current collector sheet, dried, and then calendered at an imprinting line pressure of 3.0 ton / cm to produce the positive electrode. The porosity of the positive electrode active material layer of the positive electrode manufactured as described above was measured to be 17.5%.

[0428] Example 3-2

[0429] Except for mixing the positive electrode active material, flake graphite, conductive material, and binder in a weight ratio of 97.2:0.6:0.4:1.8, the positive electrode was manufactured in the same manner as in Example 3-1, and the porosity of the positive electrode active material layer was measured. The porosity of the positive electrode active material layer was measured to be 19%.

[0430] Example 3-3

[0431] Except for mixing the positive electrode active material, flake graphite, conductive material, and binder in a weight ratio of 97.4:0.4:0.4:1.8, the positive electrode was manufactured in the same manner as in Example 3-1, and the porosity of the positive electrode active material layer was measured. The porosity of the positive electrode active material layer was measured to be 20%.

[0432] Examples 3-4

[0433] Except for mixing the positive electrode active material, flake graphite, conductive material, and binder in a weight ratio of 97.6:0.2:0.4:1.8, the positive electrode was manufactured in the same manner as in Example 3-1, and the porosity of the positive electrode active material layer was measured. The porosity of the positive electrode active material layer was measured to be 21%.

[0434] Comparative Example 3-1

[0435] Except for the absence of flake graphite and the preparation of the positive electrode slurry by mixing the positive electrode active material, conductive material, and binder in N-methylpyrrolidone at a weight ratio of 97.8:0.4:1.8, the positive electrode was prepared in the same manner as in Example 3-1, and the porosity of the positive electrode active material layer was measured. The porosity of the above-mentioned positive electrode active material layer was measured to be 24%.

[0436] Comparative Example 3-2

[0437] Except for the absence of flake graphite, the positive electrode slurry was prepared by mixing the positive electrode active material, conductive material, and binder in N-methylpyrrolidone at a weight ratio of 97.8:0.4:1.8, and calendering it at an imprint line pressure of 2.0 ton / cm. The positive electrode was then manufactured in the same manner as in Example 3-1, and the porosity of the positive electrode active material layer was measured. The measured porosity of the positive electrode active material layer was 30%.

[0438] Experimental Example 3-1 - Measurement of Charge / Discharge Capacity and Charge / Discharge Efficiency

[0439] Coin cells comprising the positive electrodes according to Examples 3-1 to 3-4 and Comparative Examples 3-1 and 3-2 were manufactured, charged to 4.25V at a current of 0.2C, and then discharged to 2.5V at a current of 0.2C. The charge capacity (mAh / g) and discharge capacity (mAh / g) of each coin cell were then measured. Table 2 below shows the measurement results.

[0440] Table 2

[0441]

[0442] As can be seen from Table 2, Examples 3-1 to 3-4, which used cathodes with added flake graphite, exhibited lower porosity than Comparative Examples 3-1 to 3-2, and thus showed good capacity characteristics.

[0443] Experiment Example 3-2 - Confirmation of Resistance Characteristics

[0444] The resistance characteristics based on SOC were measured while the coin cell half-cell, including the positive electrode according to Example 3-3, Comparative Example 3-1 and Comparative Example 3-2, was charged to 4.2V. Figure 31a The experimental results are shown.

[0445] Reference Figure 31a It can be seen that, based on a SOC of 10%, the resistance value of Example 3-3, which adds flake graphite to the positive electrode active material layer, is lower than that of Comparative Examples 3-1 and 3-2, which do not contain flake graphite. This indicates that adding flake graphite to the positive electrode active material layer has the effect of improving the resistance characteristics at lower SOCs.

[0446] Experimental Example 3-3 - Measurement of High-Temperature Service Life Characteristics and Resistance Increase Rate

[0447] A gel roll type electrode assembly was manufactured by sandwiching a separator membrane between the positive and negative electrodes according to Examples 3-1, 3-3, and Comparative Example 3-1, and then rolling them up in the order of separator membrane / positive electrode / separator membrane / negative electrode. The electrode assembly manufactured as described above was inserted into a cylindrical battery can and then electrolyte was injected to manufacture a 4680 battery cell.

[0448] At this point, the negative electrode is manufactured by mixing the negative electrode active material (graphite:SiO = 95:5 weight ratio mixture) in water at a weight ratio of 96:2:1.5:0.5, the conductive material (super C), styrene-butadiene rubber (SBR), and carboxymethyl cellulose (CMC) to produce a negative electrode slurry. The negative electrode slurry is then coated onto one side of a copper current collector sheet, dried at 150°C, and then calendered.

[0449] The 4680 battery cells manufactured as described above were charged to 4.2V at 0.5C and then discharged to 2.5V at 0.5C for 50 cycles at 40°C. After that, the capacity retention and DCIR increase were measured. Figure 31b The measurement results are shown.

[0450] Reference Figure 31bCompared with the secondary battery of Comparative Example 3-1, the secondary batteries of Examples 3-1 and 3-3 showed smaller changes in capacity retention based on cycle number and smaller changes in resistance increase rate based on cycle number.

[0451] While the present invention has been described above with limited embodiments and accompanying drawings, it is not limited thereto. Those skilled in the art to which this invention pertains should be able to make various modifications and variations within the technical concept and scope equivalent to the claims.

Claims

1. A cylindrical battery, characterized in that, include: An electrode assembly having a first electrode tab and a second electrode tab; The battery casing houses the electrode assembly through an opening formed on one side; The first current collector is located inside the battery housing and includes: a support portion disposed on one side of the electrode assembly, at least one tab connection portion extending from the support portion and engaging with the first electrode tab, and at least one housing connection portion extending from the end of the tab connection portion and engaging with the inner side of the battery housing. A cover plate that covers the aforementioned open portion; The battery terminal is electrically connected to the aforementioned second electrode tab; and The sealing partition is configured to prevent movement of the aforementioned electrode assembly and enhance the sealing performance of the battery casing. Its features are, The aforementioned enclosed partition includes: The protective moving part is sandwiched between the first current collector and the cover plate; The sealing portion, which is sandwiched between the battery casing and the cover plate; and A connecting part that connects the aforementioned anti-movement part and the aforementioned sealing part.

2. The cylindrical battery according to claim 1, characterized in that, The battery casing includes a rolled edge formed at the end adjacent to the opening and pressed inward. The aforementioned housing joint is attached to the aforementioned rolled edge portion.

3. The cylindrical battery according to claim 1, characterized in that, The battery casing includes a rolled edge formed at the end adjacent to the opening and pressed inward. The aforementioned housing joint includes: The contact portion, which is attached to the aforementioned rolled edge portion; and A connecting portion that connects the aforementioned tab joint portion and the aforementioned contact portion.

4. The cylindrical battery according to claim 3, characterized in that, Also includes: A sealing gasket is disposed between the battery casing and the cover plate.

5. The cylindrical battery according to claim 4, characterized in that, The aforementioned contact portion is sandwiched between the aforementioned rolled edge portion and the aforementioned sealing gasket and is thus secured.

6. The cylindrical battery according to claim 3, characterized in that, A welded portion is formed between the rolled edge and the contact portion of the current collector plate.

7. The cylindrical battery according to claim 1, characterized in that, The battery casing includes a rolled edge formed at the end adjacent to the opening and pressed inward. The boundary region between the aforementioned tab joint and the aforementioned housing joint is located inside the innermost part of the aforementioned rolled edge portion.

8. The cylindrical battery according to claim 1, characterized in that, The aforementioned cylindrical batteries each have multiple aforementioned tab joints and aforementioned casing joints.

9. The cylindrical battery according to claim 3, characterized in that, The aforementioned connecting portion has at least one curved portion that changes the extension direction.

10. The cylindrical battery according to claim 3, characterized in that, The contact portion has an arcuate shape that extends along the rolled edge portion.

11. The cylindrical battery according to claim 10, characterized in that, The connecting portion has an arcuate shape that extends along the contact portion.

12. The cylindrical battery according to claim 1, characterized in that, The aforementioned anti-movement part has a height corresponding to the distance between the aforementioned first collector plate and the aforementioned cover plate.

13. The cylindrical battery according to claim 1, characterized in that, On one side of the aforementioned electrode assembly, the aforementioned anti-movement part is located at the center.

14. The cylindrical battery according to claim 1, characterized in that, The aforementioned anti-movement part has a partition hole formed at a position corresponding to the winding center hole of the aforementioned electrode assembly.

15. The cylindrical battery according to claim 1, characterized in that, The aforementioned closure portion has a shape that extends along the inner circumferential surface of the battery casing.

16. The cylindrical battery according to claim 1, characterized in that, The aforementioned connecting portion includes a plurality of extended brackets extending radially from the aforementioned anti-movement portion.

17. The cylindrical battery according to claim 16, characterized in that, The aforementioned multiple extension brackets are configured to not contact the aforementioned first collector plate.

18. The cylindrical battery according to claim 16, characterized in that, The aforementioned multiple extension brackets are configured to not contact the aforementioned cover plate.

19. The cylindrical battery according to claim 1, characterized in that, The connecting portion is positioned so that it does not overlap with the casing joint portion along the height direction of the cylindrical battery.

20. The cylindrical battery according to claim 1, characterized in that, Also includes: The second collector plate is connected to the aforementioned second electrode tab; as well as An insulator is sandwiched between a blockage formed at the upper end of the battery casing and the second current collector.

21. The cylindrical battery according to claim 20, characterized in that, The insulator has a height corresponding to the distance between the second current collector and the blockage.

22. The cylindrical battery according to claim 1, characterized in that, The active material layer of the second electrode described above includes a positive electrode active material, which includes single particles, similar single particles, or combinations thereof. The smallest particle size D exhibited in the volumetric cumulative distribution of the above-mentioned positive electrode active material min Above 1.0μm, In the above-mentioned volume accumulation distribution of positive electrode active material, the particle size D is 50% when the volume accumulation is 50%. 50 Below 5.0 μm, The largest particle size D observed in the volumetric cumulative distribution of the above-mentioned positive electrode active material is... max It is 12μm to 17μm.

23. The cylindrical battery according to claim 22, characterized in that, The above-mentioned positive electrode active material has a unimodal particle size distribution exhibiting a single peak in the volumetric particle size distribution curve, and the particle size distribution PSD, expressed by the following mathematical formula, is below 3: Particle size distribution PSD = (D max –D min ) / D 50 .

24. The cylindrical battery according to claim 22, characterized in that, Based on the total weight of the positive electrode active material contained in the active material layer of the second electrode, the amount of the above-mentioned single particles, similar single particles, or combinations thereof is 95 wt% to 100 wt%.

25. The cylindrical battery according to claim 22, characterized in that, The aforementioned positive electrode active material includes lithium nickel oxide, which contains more than 80 mol% Ni based on the total molar number of transition metals.

26. The cylindrical battery according to claim 22, characterized in that, The porosity of the active material layer of the second electrode is 15% to 23%. The active material layer of the second electrode contains flake graphite in a weight ratio of 0.05 wt% to 5 wt%.

27. The cylindrical battery according to claim 22, characterized in that, The active material layer of the second electrode also includes carbon nanotubes.

28. The cylindrical battery according to claim 22, characterized in that, The active material layer of the first electrode mentioned above includes silicon-based negative electrode active material and carbon-based negative electrode active material. The above-mentioned silicon-based anode active materials and carbon-based anode active materials are included in a weight ratio of 1:99 to 20:

80.

29. A battery pack, characterized in that, include: The cylindrical battery according to any one of claims 1 to 28.

30. A car, characterized in that, include: The battery pack of claim 29.

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