Cylindrical battery, battery pack including the same, and automobile

Abstract

The present application provides a cylindrical battery, a battery pack including the cylindrical battery, and a vehicle, the cylindrical battery including: an electrode assembly including a first electrode having a first uncoated portion and a second electrode having a second uncoated portion; a battery case accommodating the electrode assembly through an open portion formed on one side; a current collector plate including a support portion disposed at a substantially central portion of one face of the electrode assembly, at least one uncoated portion coupling portion extending from the support portion and coupled to the first uncoated portion, and at least one case coupling portion extending from an end portion of the uncoated portion coupling portion and coupled to an inner side surface of the battery case; a cover plate covering the open portion; an electrode terminal riveted through a through hole formed in a plug portion of the battery case and electrically connected to the second uncoated portion, wherein the plug portion is provided on an opposite side of the open portion; and an insulating gasket interposed between the electrode terminal and the through hole, the electrode terminal including: a main body portion; an outer flange portion; an inner flange portion; and a flat portion.

Description

Technical Field

[0001] This invention relates to cylindrical batteries, battery packs including the cylindrical batteries, and automobiles. Background Technology

[0002] Previous cylindrical batteries typically had a structure in which tabs connecting the gel roll and external terminals were soldered to foil on the gel roll to achieve the connection. This structure limited the current path of the cylindrical battery, and the gel roll itself had very high resistance.

[0003] Therefore, an attempt was made to reduce the resistance by increasing the number of tabs connecting the gel roll 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.

[0004] Therefore, in order to reduce the resistance of the gel roll itself, it is necessary to develop new gel roll structures and current collector structures suitable for such gel roll structures. In particular, the application of such new gel roll and current collector structures is even more necessary in devices such as electric vehicles that require battery packs with high output / high capacity.

[0005] Furthermore, considering the operating environment, battery packs used in electric vehicles and similar applications are inevitably exposed to vibration and shock frequently. Therefore, there is a need to develop cylindrical batteries with a structure that minimizes the risk of damage to welded parts even when subjected to vibration and external impact, as well as current collector structures for such cylindrical batteries.

[0006] On the other hand, 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.

[0007] 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.

[0008] 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 battery cells are connected in series to form a battery pack. Furthermore, depending on the required charge / discharge capacity of the battery pack, sometimes multiple battery cells are connected in parallel to form a battery pack. Therefore, depending on the required output voltage and / or charge / discharge capacity, the number of battery cells included in the battery pack and the electrical connection method can be designed in various ways.

[0009] On the other hand, as types of secondary battery cells, cylindrical, square, and pouch battery cells are disclosed. The cylindrical battery cell has a separator membrane, serving as an insulator, sandwiched between the positive and negative electrodes, and is rolled up to form a gel-roll-shaped electrode assembly. This assembly, along with the electrolyte, is inserted into the battery casing to form a 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.

[0010] However, according to existing cylindrical battery cells 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.

[0011] Resistance and heat generation are not major issues for small cylindrical battery cells with form factors of 18650 or 21700. However, when the form factor is increased to make the cylindrical battery cells suitable for electric vehicles, a lot of heat is generated around the electrode tabs during fast charging, which may lead to the cylindrical battery cells catching fire.

[0012] To address this issue, a cylindrical battery cell with an improved current-collecting efficiency (a so-called tabless cylindrical battery cell) 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 the current-collecting plate welded to such uncoated portions.

[0013] Figures 1 to 4 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.

[0014] Reference Figures 1 to 4 The positive electrode 210 and the negative electrode 211 have a structure in which an active material 221 is coated on a sheet current collector 220, and an uncoated portion 222 is included on one long side along the winding direction X.

[0015] like Figure 12 As shown, electrode assembly A is manufactured by sequentially stacking positive electrode 210 and negative electrode 211 together with two separation membranes 212 and then winding them in one direction X. At this time, the uncoated portions of positive electrode 210 and negative electrode 211 are arranged in opposite directions.

[0016] After the winding process, the uncoated portion 210a of the positive electrode 210 and the uncoated portion 211a of the negative electrode 211 are bent toward the core. Then, the current collectors 230 and 231 are welded to the uncoated portions 10a and 11a respectively to achieve bonding.

[0017] The uncoated positive electrode portion 210a and the uncoated negative electrode portion 211a are not connected to any other electrode tabs. The current collectors 230 and 231 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 A (refer to the arrow). Therefore, they have the advantage of reducing battery resistance. This is because resistance is inversely proportional to the cross-sectional area of ​​the current flow path.

[0018] 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.

[0019] Specifically, such as Figure 14 As shown, the existing tabless cylindrical battery 240 includes a battery housing 241 and a seal 242. The seal 242 includes a cover plate 242a, a sealing gasket 242b, and a connecting plate 242c. The sealing gasket 242b covers the edge of the cover plate 242a and is fixed by a crimping portion 243. Furthermore, to prevent vertical movement, the electrode assembly A is fixed inside the battery housing 241 by a rolled edge portion 244.

[0020] Typically, the positive terminal is the cover plate 242a of the seal 242, and the negative terminal is the battery casing 241. Therefore, the current collector 230, which is attached to the uncoated portion 210a of the positive electrode 210, is electrically connected to the connecting plate 242c attached to the cover plate 242a via a strip lead 245. Furthermore, the current collector 231, which is attached to the uncoated portion 211a of the negative electrode 211, is electrically connected to the bottom surface of the battery casing 241. An insulator 246 covers the current collector 230 to prevent short circuits caused by contact between the battery casing 241 and the uncoated portion 210a of the positive electrode 210, which have different polarities.

[0021] When the current collector 230 is connected to the connecting plate 242c, a strip lead 245 is used. The lead 245 is either separately attached to the current collector 230 or integrally formed with the current collector 230. However, the lead 245 is a thin strip, so its cross-sectional area is small, resulting in more heat being generated when the current flows through it during rapid charging. Furthermore, the excessive heat generated in the lead 245 is transferred to the electrode assembly A side, shrinking the separation membrane 212, which may cause an internal short circuit, a major cause of thermal runaway.

[0022] The lead wire 245 occupies a significant amount of space within the battery casing 241. Therefore, the cylindrical battery 240, including the lead wire 245, has low space efficiency, thus limiting its ability to increase energy density.

[0023] In addition, to connect the existing tabless cylindrical batteries 240 in series and / or parallel, busbar components need to be connected to the cover plate 242a of the seal 242 and the bottom surface of the battery casing 241, thus reducing space efficiency. Battery packs in electric vehicles comprise hundreds of cylindrical batteries 240. Therefore, the inefficiency of electrical wiring causes considerable trouble for the assembly process of electric vehicles and the maintenance of the battery pack.

[0024] On the other hand, when using existing positive electrode active materials that include secondary particles to manufacture electrodes, battery stability may be affected due to particle cracking and increased gas generation caused by internal cracks during charging and discharging.

[0025] 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

[0026] Technical problems to be solved

[0027] This invention was made against the background of the above-mentioned prior art, and its purpose is to improve the structure of the electrode terminals of the cylindrical battery cell, improve the space efficiency within the battery casing, thereby reducing the internal resistance of the cylindrical battery cell and increasing the energy density.

[0028] Another technical objective of this invention is to improve the electrode terminal structure of the cylindrical battery cell and increase the cross-sectional area of ​​the current path, thereby improving the internal heat generation problem that occurs during fast charging.

[0029] Another technical problem of the present invention is to provide a cylindrical battery cell with an improved structure that enables electrical wiring operations for series and / or parallel connection of the cylindrical battery cells to be performed on one side of the cylindrical battery cell.

[0030] Another technical problem of the present invention is to provide a battery pack manufactured using cylindrical battery cells with improved structure, and an automobile including the same.

[0031] Furthermore, 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.

[0032] Furthermore, an object of the present invention is to provide a current collector having a structure capable of improving the bonding force at the joint between the current collector and the battery casing, and a cylindrical battery including the same.

[0033] 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.

[0034] Furthermore, the present invention aims to provide a current collector plate and a cylindrical battery including the same, wherein the current collector plate has a structure that improves the convenience of the welding process for realizing the electrical connection between the battery casing and the current collector plate when manufacturing the cylindrical battery, thereby improving productivity.

[0035] 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.

[0036] 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.

[0037] Another technical problem of the present invention is to provide an electrode assembly that increases the positive active material region without worrying about lithium deposition.

[0038] 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.

[0039] 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.

[0040] means of solving technical problems

[0041] A cylindrical battery according to an embodiment of the present invention for solving the above-mentioned technical problems includes: an electrode assembly including a first electrode having a first uncoated portion and a second electrode having a second uncoated portion; a battery casing housing the electrode assembly through an opening formed on one side; a current collector including a support portion disposed at approximately the center of one side of the electrode assembly, at least one uncoated portion joining portion extending from the support portion and joined to the first uncoated portion, and at least one casing joining portion extending from the end of the uncoated portion joining portion and joined to the inner side of the battery casing; a cover plate covering the opening; an electrode terminal riveted through a through hole formed in a plug portion of the battery casing and electrically connected to the second uncoated portion, wherein the plug portion is provided on the opposite side of the opening; and an insulating gasket sandwiched between the electrode terminal and the through hole.

[0042] The electrode terminal includes: a main body portion inserted into the through hole; an outer flange portion extending along the outer surface from one side of the main body portion exposed through the outer surface of the blocking portion; an inner flange portion extending toward the inner surface from the other side of the main body portion exposed through the inner surface of the blocking portion; and a flattening portion provided inside the inner flange portion.

[0043] The aforementioned housing joint can be attached to the rolled edge of the aforementioned battery housing.

[0044] The aforementioned housing joint may include: a contact portion, which is attached to the rolled edge portion of the battery housing; and a connecting portion, which connects the uncoated portion joint and the contact portion.

[0045] The cylindrical battery may include a sealing gasket disposed between the battery casing and the cover plate.

[0046] The aforementioned contact portion can be fixed between the rolled edge of the battery casing and the aforementioned sealing gasket.

[0047] A welded portion may be formed between the rolled edge of the battery casing and the contact portion of the current collector plate.

[0048] The boundary region between the uncoated portion and the housing portion can be located inside the innermost part of the rolled edge portion formed on the battery housing.

[0049] The aforementioned cylindrical batteries each have multiple uncoated portion joints and housing joints.

[0050] The aforementioned connecting portion may have at least one curved portion that changes the extension direction.

[0051] The contact portion may have an arcuate shape extending along the rolled edge of the battery casing.

[0052] The connecting portion may have an arcuate shape extending along the contact portion.

[0053] The inner surfaces of the aforementioned flattened portion and the aforementioned blocking portion can be parallel to each other.

[0054] The angle between the inner surface of the aforementioned internal flange and the inner surface of the aforementioned plug can be between 0 degrees and less than 60 degrees.

[0055] There may be a recess between the aforementioned internal flange portion and the aforementioned flat portion.

[0056] The aforementioned recessed portion can have an asymmetrical groove cross-sectional structure.

[0057] The aforementioned asymmetrical groove may include the sidewall of the aforementioned flat portion and the inclined surface of the aforementioned internal flange portion connected to the end of the aforementioned sidewall.

[0058] The aforementioned sidewall may be perpendicular to the inner surface of the aforementioned blockage.

[0059] The thickness of the aforementioned internal flange portion can decrease as it moves away from the aforementioned main body portion.

[0060] The aforementioned insulating gasket may include: an outer gasket sandwiched between the outer flange and the outer surface of the plug; and an inner gasket sandwiched between the inner flange and the inner surface of the plug, wherein the thickness of the inner gasket and the outer gasket is different depending on their positions.

[0061] In the region of the aforementioned internal gasket, the thickness of the area between the inner edge of the through hole connected to the inner surface of the aforementioned plug and the aforementioned internal flange can be relatively smaller than that of other areas.

[0062] The inner edge of the aforementioned through hole may include a surface opposite to the aforementioned inner flange.

[0063] The aforementioned internal gasket can extend to a length greater than the aforementioned internal flange.

[0064] Based on the inner surface of the aforementioned blocking portion, the height of the aforementioned flat portion may be the same as or higher than the end height of the aforementioned internal gasket.

[0065] Based on the inner surface of the aforementioned blocking portion, the height of the aforementioned flat portion may be the same as or higher than the end height of the aforementioned inner flange portion.

[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... minThe particle size D can be above 1.0 μm, and it is 50% of the total volume of the above-mentioned positive electrode active material. 50 The maximum particle size D exhibited in the volumetric cumulative distribution of the above-mentioned positive electrode active material is below 5.0 μm. max It can be from 12μm to 17μm.

[0067] In the aforementioned cylindrical battery, the positive electrode active material can have a unimodal particle size distribution that exhibits a single peak in the volumetric particle size distribution curve, with a particle size distribution (PSD) of three or less, expressed by the following mathematical formula:

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

[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 a 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] On the other hand, 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; and a battery pack housing that houses a plurality of the above-described cylindrical batteries.

[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 one aspect of the present invention, by improving the electrode terminal structure of the cylindrical battery cell and increasing the space efficiency within the battery casing, it is possible to reduce the internal resistance of the cylindrical battery cell and increase the energy density.

[0078] According to another aspect of the invention, by improving the electrode terminal structure of the cylindrical battery cell and increasing the cross-sectional area of ​​the current path, the internal heat generation problem during fast charging can be improved.

[0079] According to another aspect of the invention, electrical wiring operations for connecting the cylindrical battery cells in series and / or in parallel can be performed on one side of the cylindrical battery cell.

[0080] According to another aspect of the invention, it is possible to provide a battery pack manufactured using a cylindrical battery cell having an improved structure and an automobile including the same.

[0081] Furthermore, according to the present invention, resistance can be significantly reduced when realizing the electrical connection between the electrode assembly and the battery casing.

[0082] Furthermore, according to the present invention, the bonding force at the joint between the current collector and the battery casing can be improved.

[0083] Moreover, according to the present invention, the energy density of cylindrical batteries can be increased.

[0084] 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.

[0085] 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.

[0086] According to another aspect of the invention, the positive electrode contains D 50 D maxThe 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.

[0087] According to another aspect of the 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.

[0088] 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.

[0089] 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.

[0090] 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.

[0091] 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.

[0092] 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

[0093] 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.

[0094] Figure 1 This is a plan view showing the electrode structure used in existing tabless cylindrical battery cells.

[0095] Figure 2 This is a diagram illustrating the winding process of the electrode assembly contained in a conventional tabless cylindrical battery cell.

[0096] Figure 3 It is shown Figure 10 A diagram showing the process of welding a current collector plate to the bent surface of the uncoated part in the electrode assembly.

[0097] Figure 4 This is a cross-sectional view of an existing tabless cylindrical battery cell cut along its length direction Y.

[0098] Figure 5 This is a partial longitudinal cross-sectional view of a cylindrical battery according to an embodiment of the present invention.

[0099] Figure 6 This is a partial longitudinal cross-sectional view of a cylindrical battery according to another embodiment of the present invention.

[0100] Figure 7 This is a partial longitudinal cross-sectional view of a cylindrical battery according to yet another embodiment of the present invention.

[0101] Figure 8 It is used for explanation Figure 3 A diagram of the current collector contained in a cylindrical battery.

[0102] Figure 9 This is a diagram illustrating a current collector according to another embodiment of the present invention.

[0103] Figure 10 This is a diagram illustrating a current collector according to yet another embodiment of the present invention.

[0104] Figure 11 This is a diagram illustrating the battery pack included in a cylindrical battery according to an embodiment of the present invention.

[0105] Figure 12 It is used to illustrate including Figure 11 A picture of a car with a battery pack.

[0106] Figure 13 This is a cross-sectional view showing the riveting structure of the electrode terminals according to an embodiment of the present invention.

[0107] Figure 14 yes Figure 13 Enlarged cross-sectional view of the part represented by the dashed circle.

[0108] Figure 15 This is a cross-sectional view of a cylindrical battery cell cut along the length Y direction according to an embodiment of the present invention.

[0109] Figure 16 This is a plan view illustrating an electrode structure according to a preferred embodiment of the present invention.

[0110] Figure 17 This is a cross-sectional view of an electrode assembly in which a slit structure of the uncoated portion of the electrode according to an embodiment of the present invention is applied to the first electrode and the second electrode by cutting along the length direction Y.

[0111] Figure 18This is a cross-sectional view of an electrode assembly with the uncoated portion bent according to an embodiment of the present invention, cut along the length direction Y.

[0112] Figure 19 These are scanning microscope images of carbon nanotubes (currently CNTs), which were previously commonly used.

[0113] Figure 20 These are scanning microscope images of the new CNT according to an embodiment of the present invention.

[0114] Figure 21 This is a table showing a comparison of the physical properties of existing CNTs and new CNTs.

[0115] Figures 22 to 25 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.

[0116] Figure 26 The comparison shows that the specific surface area of ​​BET is 300m². 2 / g to 500m 2 / g of carbon nanotubes (new CNTs) status and applications BET at 200m 2 / g or more and less than 300m 2 Table of solid powder content and viscosity of positive electrode slurry with / g carbon nanotubes (existing CNTs), and resistance values ​​in MP coating and MP interface layer.

[0117] Figure 27 This is a SEM image of the positive electrode active material used in Example 2-1 of the present invention.

[0118] Figure 28 These are SEM images of the positive electrode active material used in Examples 2-2 of the present invention.

[0119] Figure 29 This is a SEM image of the positive electrode active material used in Comparative Example 2-2 of this invention.

[0120] Figure 30 This is a graph showing the hot box test results of the 4680 battery cell manufactured according to Embodiment 1 of the present invention.

[0121] Figure 31 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.

[0122] Figure 32 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.

[0123] Figure 33 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.

[0124] Figure 34 This is a cross-sectional SEM image of the positive electrode manufactured in Embodiment 2-1 of the present invention.

[0125] Figure 35 This is a cross-sectional SEM image of the positive electrode manufactured in Comparative Example 2-1.

[0126] Figure 36 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.

[0127] Figure 37 The graph shows the measurement results of capacity retention and DCIR increase of the 4680 battery cell obtained by charge-discharge cycle experiments for the present invention, according to Embodiments 3-1, 3-3 and Comparative Example 3-1.

[0128] Figure 38 This is a diagram illustrating an electrode assembly according to an embodiment of the present invention.

[0129] Figure 39 It shows along Figure 38 A cross-sectional view of the section cut by the cutting line A-A'.

[0130] Figure 40 as well as Figure 41 This is a diagram illustrating the process of manufacturing a negative electrode according to an embodiment of the present invention.

[0131] Figure 42 This is a perspective view showing the negative electrode according to an embodiment of the present invention.

[0132] Figure 43 as well as Figure 44 This is a diagram illustrating the process of manufacturing a positive electrode according to an embodiment of the present invention.

[0133] Figure 45 This is a perspective view showing the positive electrode according to an embodiment of the present invention.

[0134] Figure 46 This is a diagram illustrating an electrode assembly according to a comparative example of the present invention.

[0135] Figure 47 It shows along Figure 46A cross-sectional view of the section cut by the cutting line B-B'.

[0136] Figure 48 This is a diagram illustrating the process of manufacturing a negative electrode according to a comparative example of the present invention.

[0137] Figure 49 This is a diagram illustrating the process of manufacturing a positive electrode according to a comparative example of the present invention.

[0138] Figure 50 This 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

[0139] 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.

[0140] 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.

[0141] 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.

[0142] 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.

[0143] 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.

[0144] 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.

[0145] Reference Figure 5 According to an embodiment of the present invention, a cylindrical battery 1 includes an electrode assembly 10, a battery casing 20, a current collector (first current collector) 30, a cover plate 40, and electrode terminals 50. In addition, the cylindrical battery 1 may also include a sealing gasket 60 and / or an insulating gasket 54 and / or a current collector (second current collector) 70 and / or an insulator 80.

[0146] The electrode assembly 10 includes a first electrode having a first uncoated portion (first electrode tab) 11 and a second electrode having a second uncoated portion (second electrode tab) 12. The term "electrode uncoated portion" or "uncoated portion" mentioned below refers to an electrode tab. The electrode assembly 10 can be manufactured by rolling up 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 10 used in this invention can be a gel roll type electrode assembly. In this case, an additional separation membrane can be provided on the outer peripheral surface of the electrode assembly 10 to achieve insulation from the battery casing 20.

[0147] The aforementioned first electrode includes a first electrode current collector and a first electrode active material 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 a first uncoated portion 11, which is not coated with the first electrode active material, on one side of its height (parallel to the other side). This first uncoated portion 11 functions as a first electrode tab. The first uncoated portion 11 is provided in the height direction (parallel to the other side) of the electrode assembly 10 housed within the battery casing 20. Figure 5 The upper part of the cylindrical battery 1 shown (in the direction of parallel alignment in the height direction). The first uncoated portion 11 mentioned above can be, for example, a negative electrode sheet.

[0148] The aforementioned second electrode includes a second electrode current collector and a second electrode active material coated on one or both sides of the second electrode current collector. The width direction of the aforementioned second electrode current collector (with...) Figure 5On one side of the cylindrical battery 1 shown (in the direction parallel to each other in the height direction), there is a second uncoated portion 12 that is not coated with the second electrode active material. This second uncoated portion 12 functions as a second electrode tab. The second uncoated portion 12 is located at the lower part of the electrode assembly 10 housed within the battery casing 20 in the height direction. The second uncoated portion 12 can be, for example, a positive electrode tab.

[0149] In this invention, the positive electrode active material coated on the positive electrode and the negative electrode active material coated on the negative electrode can be any active material known in the art, without any limitation.

[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 on the opposite side of the opening (as shown in the image)... Figure 5 The blocking portion (based on the lower side) is typically integrally formed. That is, the battery housing 20 generally has a shape with its upper end open in the height direction and its lower end closed. The lower surface of the battery housing 20 may have a generally flat shape. The battery housing 20 houses the electrode assembly 10 through an opening formed on one side in the height direction. The battery housing 20 can also house the electrolyte through the opening.

[0151] The battery casing 20 may have a rolled edge portion 21 formed at its upper end. The battery casing 20 may also have a pressing portion 22 formed on the upper part of the rolled edge portion 21. The rolled edge portion 21 has a shape in which the periphery of the outer peripheral surface of the battery casing 20 is pressed in to a predetermined depth. The rolled edge portion 21 is formed on the upper part of the electrode assembly 10. The inner diameter of the battery casing 20 in the region where the rolled edge portion 21 is formed is smaller than the diameter of the electrode assembly 10.

[0152] 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 surrounding the current collector plate 30 (described later). That is, at least a portion of the edge surrounding the current collector plate 30 of the present invention and / or the edge surrounding the cover plate 40 of the present invention can be placed on the upper surface of 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 current collector 30 and / or the edge of the cover plate 40, the upper surface of the rolled edge 21 may also 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.

[0153] The aforementioned crimping portion 22 is formed on the upper part of the rolled edge portion 21. The crimping portion 22 has a shape that extends and bends to wrap around the edge of the cover plate 40 disposed on the upper part of the rolled edge portion 21. Through this shape of the crimping portion 22, the cover plate 40 is fixed to the rolled edge portion 21. Alternatively, this crimping portion 22 can be omitted, and the cover plate 40 can be covered and fixed by other fixing structures.

[0154] Secondly, refer to Figure 7 as well as Figure 8 The current collector (first current collector) 30 according to an embodiment of the present invention will be described in detail.

[0155] First, refer to Figure 7 According to an embodiment of the present invention, the current collector 30 is housed inside the battery casing 20, electrically connected to the electrode assembly 10, and electrically connected to the battery casing 20. That is, the current collector 30 realizes the electrical connection between the electrode assembly 10 and the battery casing 20.

[0156] The aforementioned current collector 30 includes a support portion 31 disposed at approximately the center of one side of the electrode assembly 10, at least one uncoated portion joint portion 32 extending from the support portion 31 and joined to the first uncoated portion 11, and at least one housing joint portion 33 extending from the end of the uncoated portion joint portion 32 and joined to the inner side of the battery housing 20.

[0157] The aforementioned support portion 31 and at least one uncoated portion joint portion 32 are disposed on the upper part of the electrode assembly 10, and may be located on the lower part of the rolled edge portion 21 when the battery housing 20 has a rolled edge portion 21.

[0158] The aforementioned support portion 31 has a current collector hole 30a formed at a position corresponding to the winding hole C formed at the center of the electrode assembly 10. The winding hole C and the current collector hole 30a, which are interconnected, can function as a channel for inserting welding rods for welding between the electrode terminal 50 and the current collector (second current collector) 70 (described later) or between the electrode terminal 50 and the lead tab (not shown), or for irradiating lasers.

[0159] 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 plate shape with a current collector hole 30a at its center.

[0160] The aforementioned at least one uncoated portion joint 32 may have a shape that extends generally radially toward the sidewall of the battery casing 20 from the support portion 31 of the current collector 30. For example, multiple uncoated portion joints 32 may be provided. For example, refer to… Figure 8Each of the plurality of uncoated portion joints 32 can be positioned separately from each other along the edge of the support portion 31. Thus, the cylindrical battery 1 of the present invention has a plurality of uncoated portion joints 32, thereby increasing the contact area with the first uncoated portion 11. This ensures the bonding force between the first uncoated portion 11 and the uncoated portion joints 32, reducing resistance.

[0161] The end of the uncoated portion joint 32 in the longitudinal direction can be located inside the innermost side of the rolled edge portion 21 formed on the battery housing 20. More specifically, in the direction toward the winding hole C, the boundary region between the uncoated portion joint 32 and the housing joint 33 can be located inside the innermost side of the rolled edge portion 21 formed on the battery housing 20. With this structure, damage to the joint between components that may occur when the current collector plate 30 is excessively bent so that the end of the housing joint 33 is located on the rolled edge portion 21 can be prevented.

[0162] On the other hand, in order to ensure bonding strength and reduce resistance by increasing the bonding area between the current collector 30 and the electrode assembly 10, the support portion 31 can also be bonded to the first uncoated portion 11 in addition to the uncoated portion bonding portion 32. The end of the first uncoated portion 11 can be formed into a curved shape that is parallel to the uncoated portion bonding portion 32. When the first uncoated portion 11 is bonded to the uncoated portion bonding portion 32 in such a state where the end of the first uncoated portion 11 is formed and parallel to the uncoated portion bonding portion 32, the bonding area is increased, thereby improving the bonding strength and reducing the resistance, and minimizing the total height of the electrode assembly 10, thereby improving the energy density.

[0163] At least one housing joint 33 can extend from the end of the uncoated joint 32 and be attached to the inner side of the battery housing 20. For example, the at least one housing joint 33 may have a shape extending from the end of the uncoated joint 32 toward the sidewall of the battery housing 20. Multiple housing joints 33 may be provided, for example. 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 multiple housing joints 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 7As shown, the top of the rolled edge 21 extends in a direction substantially parallel to the bottom of the battery casing 20, i.e., substantially perpendicular to the sidewall of the battery casing 20. The casing joint 33 also extends in the same direction, allowing the casing joint 33 to stably contact the rolled edge 21. Furthermore, with the casing joint 33 stably contacting the rolled edge 21, welding between the two components can be performed smoothly, thereby increasing the bonding strength between the two components and minimizing the increase in resistance at the joint. Moreover, by attaching the current collector 30 to the rolled edge 21 of the battery casing 20 instead of the inner surface of the cylindrical body of the battery casing 20, the distance between the current collector 30 and the rolled edge 21 can be reduced. Therefore, dead corners inside the battery casing 20 are minimized, thereby increasing the energy density of the cylindrical battery 1.

[0164] Reference Figure 6 as well as Figure 7 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 uncoated part joint 32 and the contact portion 33a.

[0165] The contact portion 33a is attached to the inner side surface of the battery housing 20. When the battery housing 20 has a rolled edge portion 21, as described above, the contact portion 33a can be attached to the rolled edge portion 21. In this case, as described above, to achieve stable contact and attachment, both the rolled edge portion 21 and the contact portion 33a can have a shape extending in a direction substantially parallel to the bottom surface of the battery housing 20, that is, in a direction substantially perpendicular to the sidewall of the battery housing 20.

[0166] Reference Figure 7 The connecting portion 33b may have at least one curved portion B that changes its extension direction between the support portion 31 and the contact portion 33a. That is, the connecting portion 33b may have a spring-like structure or a telescopic 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 10 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 10 with the current collector plate 30 in the battery housing 20.

[0167] The accompanying drawings of this invention only show the case of having one of the above-described curved portions B; however, the invention is not limited to this, and of course, multiple portions may be provided.

[0168] For example, preferably, the vertical distance D between the contact portion 33a and the support portion 31, when the current collector plate 30 is not deformed without external force applied, is formed to be the same as or smaller than the vertical distance between the top of the rolled edge portion 21 and the support portion 31 when the electrode assembly 10 with the current collector plate 30 attached is placed inside the battery housing 20. When the connection portion 33b is configured to satisfy this condition, the contact portion 33a can naturally and tightly adhere to the rolled edge portion 21 when the electrode assembly 10 with the current collector plate 30 attached is placed inside the battery housing 20.

[0169] 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 cause the electrode assembly 10 to move up and down, within a certain range, the impact caused by the movement of the electrode assembly 10 can still be mitigated.

[0170] On the other hand, when the connecting portion 33b has only one bent portion B, unlike the case shown in the attached drawings, the bent portion B can also protrude towards the winding center of the electrode assembly 10. This bending direction of the connecting portion 33b is to prevent damage to the joint between the current collector plate (first current collector plate) 30 and the electrode assembly 10, and / or the joint between the current collector plate (first current collector plate) 30 and the battery casing 20, during the sizing process. The sizing process is a compression process that reduces the height occupied by the rolled edge portion 21 area of ​​the battery casing 20 in order to reduce the overall height of the cylindrical battery 1 during manufacturing. By changing whether the bent portion B is formed and the protruding direction of the bent portion B, and confirming the degree of damage to the welded portion after the sizing process, it was found that almost no damage occurred in the cylindrical battery 1 with a structure in which the bent connecting portion 33b protrudes towards the center of the cylindrical battery 1.

[0171] Secondly, refer to Figure 9 The image shows a current collector 30 according to another embodiment of the present invention. (The last sentence appears to be incomplete and possibly refers to something similar to the description above.) Figure 8 Compared to the current collector 30 described above, the current collector 30 according to another embodiment of the present invention differs only in the shape of the contact portion 33a. Otherwise, it can adopt a structure that is substantially the same as that of the current collector 30 described above.

[0172] Reference Figure 9The 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 of the battery casing 20. Furthermore, although not shown in the figures, in order to maximize the contact area, the current collector 30 may also be configured such that the sum of the extension lengths of the contact portions 33a of at least one casing joint 33 is approximately the same as the inner circumference of the battery casing 20. This allows for the improvement of bonding strength and the reduction of resistance resulting from the maximization of the bonding area.

[0173] Secondly, refer to Figure 10 This illustrates a current collector 30 according to yet another embodiment of the present invention. Figure 9 Compared to the current collector 30 described above, the current collector 30 according to another embodiment of the present invention differs only in the shape of the connecting portion 33b. Otherwise, it can adopt a structure that is substantially the same as that of the current collector 30 described above.

[0174] 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 of the battery casing 20, and the connecting portion 33b may have an arcuate shape extending along the contact portion 33a. According to this structure, with... Figure 5 Compared to the current collector 30 shown, the area of ​​the current collector 30 is further increased, so the resistance reduction effect can be maximized.

[0175] On the other hand, refer to Figure 10 ,and Figure 8 or Figure 9 Unlike the current collector 30 shown, the current collector 30 may not have the bent portion B. Without the bent portion B, the amount of raw materials required to manufacture the current collector 30 can be reduced. This reduces the manufacturing cost of the current collector 30.

[0176] Reference Figure 5 The cover plate 40 covers the opening formed on one side of the battery housing 20. The cover plate 40 can be fixed by a crimping portion 22 formed on the upper end of the battery housing 20. In this case, to improve the fixing force and the sealing of the battery housing 20, a sealing gasket 60 can be sandwiched between the battery housing 20 and the cover plate 40. It should be noted that in this invention, the cover plate 40 is not a component that needs to function as a current channel. Therefore, as long as the battery housing 20 and the cover plate 40 can be firmly fixed by welding or using other components to ensure the sealing of the opening of the battery housing 20, the sealing gasket 60 is not necessary.

[0177] On the other hand, taking the application of the aforementioned sealing gasket 60 as an example, the sealing gasket 60 can have a generally annular shape that wraps around the cover plate 40. The sealing gasket 60 can simultaneously cover the top, bottom, and sides of the cover plate 40. The radial length of the portion of the sealing gasket 60 covering the bottom of the cover plate 40 can be smaller or the same as the radial length of the portion of the sealing gasket 60 covering the top of the cover plate 40. If the radial length of the portion of the sealing gasket 60 covering the bottom of the cover plate 40 is too long, the sealing gasket 60 may press against the current collector 30 during the compression of the battery casing 20, potentially damaging the current collector 30 or the battery casing 20. Therefore, the radial length of the portion of the sealing gasket 60 covering the bottom of the cover plate 40 needs to be kept relatively short. For example, as... Figure 5 As shown, the radial length of the portion of the sealing gasket 60 that covers the lower part of the cover plate 40 can be the same as the radial length of the portion of the sealing gasket 60 that covers the upper part of 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 60 that covers the lower part of the cover plate 40 can be made smaller than the radial length of the portion of the sealing gasket 60 that covers the upper part of the cover plate 40.

[0178] On the other hand, the contact portion 33a can be fixed by being sandwiched between the rolled edge portion 21 of the battery casing 20 and the sealing gasket 60. That is, with the contact portion 33a sandwiched between the rolled edge portion 21 of the battery casing 20 and the sealing gasket 60, the contact portion 33a can be fixed by the pressing force of the pressing portion 22.

[0179] Alternatively, a welded portion can be formed between the rolled edge 21 of the battery casing 20 and the contact portion 33a of the current collector plate. For example, sometimes the contact portion 33a cannot be reliably fixed by pressing force alone. Or, when the sealing gasket 60 shrinks due to heat or the pressing portion 22 is deformed by external impact, the bonding force between the current collector plate and the battery casing 20 may decrease. Therefore, with the contact portion 33a placed on the rolled edge 21 of the battery casing 20, the current collector plate 30 can be fixed to the battery casing 20 by welding. Then, a cover plate wrapped by the sealing gasket 60 is placed on the upper end of the contact portion 33a to form the pressing portion 22, 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 methods are not limited to these.

[0180] On the other hand, the cover plate 40 may include a vent 41 formed to prevent gas buildup inside the battery casing 20 from causing 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, so that it is easily ruptured when internal pressure is applied. The vent 41 may, for example, be a region with a thinner thickness than the surrounding region. 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.

[0181] The aforementioned electrode terminal 50 penetrates the blocking portion of the battery housing 20 on the opposite side of the open portion, thereby electrically connecting to the second uncoated portion 12 of the electrode assembly 10. The aforementioned electrode terminal 50 may penetrate approximately the center portion below the battery housing 20. The aforementioned electrode terminal 50 may be connected, for example, to a current collector plate (second current collector plate) 70 attached to the second uncoated portion 12 or to a lead tab (not shown) attached to the second uncoated portion 12, thereby electrically connecting to the electrode assembly 10. Therefore, the aforementioned electrode terminal 50 has the same polarity as the second electrode of the electrode assembly 10, and can function as the second electrode terminal T2. When the aforementioned second uncoated portion 12 is a positive uncoated portion, the electrode terminal 50 can function as a positive terminal.

[0182] Considering the polarity and function of this electrode terminal 50, the electrode terminal 50 needs to be kept insulated from the battery housing 20, which has the opposite polarity. For this purpose, an insulating gasket 54 can be used between the electrode terminal 50 and the battery housing 20. Alternatively, insulation can be achieved by coating a portion of the surface of the electrode terminal 50 with an insulating material.

[0183] For the same reason, the second uncoated portion 12 and / or the current collector (second current collector) 70 need to be kept insulated from the battery casing 20. Therefore, an insulator 80 can be sandwiched between the second uncoated portion 12 and the battery casing 20, and / or between the current collector (second current collector) 70 and the battery casing 20. When the insulator 80 is used, the electrode terminal 50 can penetrate the insulator 80 to achieve electrical connection with the second uncoated portion 12.

[0184] On the other hand, in this invention, the blocking portion 20a of the battery casing 20 can function as the first electrode terminal T1. For example, if the first uncoated portion 11 is a negative uncoated portion, the first electrode terminal T1 can be the negative terminal. The cylindrical battery 1 according to the invention has a structure in which the electrode terminal 50 exposed to the outside of the blocking portion 20a located opposite to the open portion of the battery casing 20, and the remaining area on the outer surface of the blocking portion 20a of the battery casing 20, excluding the area occupied by the electrode terminal 50, can be used as the second electrode terminal T2 and the first electrode terminal T1, respectively. 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 according to the invention has a structure in which a large portion of the outer surface of the blocking portion 20a located 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.

[0185] Preferably, the cylindrical battery cell can be, for example, a cylindrical battery cell with a shape factor ratio (the value of the diameter of the cylindrical battery cell divided by the height, i.e., defined as the ratio of the diameter Φ relative to the height H) that can be approximately greater than 0.4.

[0186] The shape factor indicates the diameter and height of the cylindrical battery cell. According to an embodiment of the present invention, the cylindrical battery cell can be, for example, a 46110 battery cell, a 48750 battery cell, a 48110 battery cell, a 48800 battery cell, or a 46800 battery cell. In the shape factor values, the first two digits represent the diameter of the battery cell, the next two digits represent the height of the battery cell, and the final digit 0 indicates that the cross-section of the battery cell is circular.

[0187] According to one embodiment of the present invention, the battery cell is a generally cylindrical battery cell, which may be a cylindrical battery cell with a diameter of about 46 mm, a height of about 110 mm, and a shape factor ratio of about 0.418.

[0188] According to another embodiment, the battery cell is a generally cylindrical battery cell, which may be a cylindrical battery cell with a diameter of about 48 mm, a height of about 75 mm, and a shape factor ratio of about 0.640.

[0189] According to another embodiment, the battery cell is a generally cylindrical battery cell, which may be a cylindrical battery cell with a diameter of about 48 mm, a height of about 110 mm, and a shape factor ratio of about 0.418.

[0190] According to another embodiment, the battery cell is a generally cylindrical battery cell, which may be a cylindrical battery cell with a diameter of about 48 mm, a height of about 80 mm, and a shape factor ratio of about 0.600.

[0191] According to another embodiment, the battery cell is a generally cylindrical battery cell, which may be a cylindrical battery cell with a diameter of about 46 mm, a height of about 80 mm, and a shape factor ratio of about 0.575.

[0192] Previously, battery cells with a form factor ratio of approximately 0.4 or less were used. That is, previously, cells such as the 18650 and 21700 were used. The 18650 battery cell has a diameter of approximately 18 mm and a height of approximately 65 mm, with a form factor ratio of 0.277. The 21700 battery cell has a diameter of approximately 21 mm and a height of approximately 70 mm, with a form factor ratio of 0.300.

[0193] On the other hand, refer to Figure 11 According to an embodiment of the present invention, the battery pack 3 includes a secondary battery assembly consisting of a plurality of cylindrical batteries 1 electrically connected as described above, and a battery pack housing 2 housing the assembly. In the accompanying drawings of the present invention, for ease of illustration, components such as busbars, cooling units, and power terminals used for electrical connection are omitted.

[0194] Reference Figure 12 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 receives power from the battery pack 3 according to an embodiment of the present invention for operation.

[0195] Secondly, refer to Figures 13 to 18 A more detailed explanation will be given regarding the cylindrical battery 1 described above.

[0196] As described above, a cylindrical battery according to an embodiment of the present invention may include electrode terminals riveted to a plug portion 20a of the battery casing.

[0197] Figure 13 This is a cross-sectional view showing the riveting structure of the electrode terminal 50 according to an embodiment of the present invention. Figure 14 This is an enlarged cross-sectional view of the part represented by the dashed circle.

[0198] Reference Figure 13 as well as Figure 14According to the embodiment, the riveting structure of the electrode terminal 50 may include a cylindrical battery housing 20 with an open side, an electrode terminal 50 riveted through a through hole 23 formed in the plug portion 20a of the battery housing 20, and an insulating gasket 54 sandwiched between the electrode terminal 50 and the through hole 23.

[0199] The battery casing 20 is made of a conductive metal. In one example, the battery casing 20 may be made of steel, but the invention is not limited thereto.

[0200] The electrode terminal 50 is made of a conductive metal. In one example, the electrode terminal 50 may be made of aluminum, but the invention is not limited thereto.

[0201] The insulating gasket 54 can be made of a polymer resin that has both insulating and elastic properties. In one example, the insulating gasket 54 can be made of polypropylene, polybutylene terephthalate, polyvinyl fluoride, etc., but the present invention is not limited thereto.

[0202] Preferably, the electrode terminal 50 may include a main body portion 50a inserted into the through hole 23, an outer flange portion 50b extending along the outer surface of one side of the main body portion 50a exposed through the outer surface of the plug portion 20a of the battery housing 20, an inner flange portion 50c extending toward the inner surface of the other side of the main body portion 50a exposed through the inner surface of the plug portion 20a of the battery housing 20, and a flat portion 50d provided inside the inner flange portion 50c.

[0203] Preferably, the inner surfaces of the flattened portion 50d and the plug portion 20a of the battery casing 20 can be parallel to each other. Here, "parallel" means that they are substantially parallel when viewed with the naked eye.

[0204] According to one aspect, the angle θ between the inner flange portion 50c and the inner surface of the plug portion 20a of the battery housing 20 can be from 0 degrees to less than 60 degrees. When the electrode terminal 50 is provided in the through hole 23 of the battery housing 20 by a gap-filling process, the angle is determined based on the gap-filling strength. In one example, as the gap-filling strength increases, the angle θ can decrease to 0 degrees. If the angle exceeds 60 degrees, the sealing effect of the insulating gasket 54 may decrease.

[0205] According to another aspect, a recess 55 may be provided between the inner flange 50c and the flattened portion 50d. The recess 55 may have an asymmetrical groove cross-sectional structure. In one example, the asymmetrical groove may be approximately V-shaped. The asymmetrical groove may include a sidewall 55a of the flattened portion 50d and a slope 55b of the inner flange 50c connected to the end of the sidewall 55a. The sidewall 55a may be substantially perpendicular to the inner surface of the plug portion 20a of the battery housing 20. "Perpendicular" means substantially perpendicular when viewed with the naked eye. When the electrode terminal 50 is provided in the through hole 23 of the battery housing 20 by a gap-filling process, the recess 55 is formed based on the shape of the gap-filling fixture.

[0206] Preferably, the thickness of the inner flange portion 50c can be reduced as the body portion 50a moves away from the electrode terminal 50.

[0207] According to another aspect, the insulating gasket 54 may include an outer gasket 54a sandwiched between the outer flange portion 50b and the outer surface of the plug portion 20a of the battery housing 20, and an inner gasket 54b sandwiched between the inner flange portion 50c and the inner surface of the plug portion 20a of the battery housing 20.

[0208] The thicknesses of the outer gasket 54a and the inner gasket 54b can vary depending on their location. Preferably, in the region of the inner gasket 54b, the thickness of the area sandwiched between the inner edge 24 of the through hole 23 connected to the inner surface of the plug portion 20a of the battery housing 20 and the inner flange portion 50c can be relatively small. Preferably, there can be a point of minimum thickness in the gasket region sandwiched between the inner edge 24 of the through hole 23 and the inner flange portion 50c. Furthermore, the inner edge 24 of the through hole 23 may include an opposing surface 25 facing the inner flange portion 50c.

[0209] On the other hand, the upper and lower ends of the inner wall of the through hole 23, which is perpendicular to the blocking portion 20a of the battery housing 20, are corner-cut to form a tapered surface toward the electrode terminal 50. However, the upper and / or lower ends of the inner wall of the through hole 23 can also be deformed into a gently curving surface. In this case, the pressure applied to the gasket 54 can be further relieved near the upper and / or lower ends of the inner wall of the through hole 23.

[0210] Preferably, the inner gasket 54b forms an angle of 0 to 60 degrees with the inner surface of the plug portion 20a of the battery housing 20, and extends longer than the inner flange portion 50c.

[0211] According to another aspect, based on the inner surface of the plug portion 20a of the battery housing 20, the height H1 of the flattening portion 50d can be the same as or higher than the end height H2 of the inner gasket 54b. Furthermore, based on the inner surface of the plug portion 20a of the battery housing 20, the height H1 of the flattening portion 50d can be the same as or higher than the end height H3 of the inner flange portion 50c.

[0212] If the height parameters H1, H2, and H3 meet the above conditions, it is possible to prevent the internal flange 50c and the internal gasket 54b from interfering with other components.

[0213] According to another aspect, the radius R1 from the center of the main body 50a of the electrode terminal 50 to the edge of the outer flange 50b can be 10 to 60% based on the radius R2 of the plug portion 20a of the battery casing 20.

[0214] If R1 is small, there will be insufficient space for welding electrical wiring components (busbars) when welding them to the electrode terminals 50. Conversely, if R1 is large, there will be less space for welding electrical wiring components (busbars) to the outer surface of the blockage portion 20a of the battery casing 20, in addition to the electrode terminals 50.

[0215] If the ratio R1 / R2 is adjusted between 10% and 60%, the welding space for the electrode terminal 50 and the outer surface of the plug portion 20a of the battery housing 20 can be properly ensured.

[0216] Furthermore, the radius R3 from the center of the main body 50a of the electrode terminal 50 to the edge of the flat part 50d can be 4 to 30% based on the radius R2 of the blocking part 20a of the battery casing 20.

[0217] If R3 becomes smaller, then a current collector (second current collector) is welded to the flat portion 50d of electrode terminal 50 (refer to...). Figure 15 If the welding space is insufficient (70%), the welding area of ​​the electrode terminal 50 will be reduced, which may increase the contact resistance. Furthermore, R3 should be less than R1. If R3 is larger, the thickness of the inner flange 50c will be thinner, and the force with which the inner flange 50c compresses the insulating gasket 54 will be weaker, which may reduce the sealing ability of the insulating gasket 54.

[0218] If R3 / R2 is adjusted between 4% and 30%, then by ensuring that the flat portion 50d of the electrode terminal 50 is sufficiently aligned with the current collector plate ( Figure 15 The welding area of ​​70% makes the welding process easier. In addition, it can reduce the contact resistance of the welding area and prevent the sealing ability of the insulating gasket 54 from decreasing.

[0219] According to an embodiment of the present invention, the riveting structure of the electrode terminal 50 can be formed using a vertically movable gap-filling jig. First, the insulating gasket 54 is positioned in the through hole 23 formed in the plug portion 20a of the battery housing 20, and a preform (not shown) of the electrode terminal 50 is inserted. The preform refers to the electrode terminal before riveting.

[0220] Next, the gap-filling jig is inserted into the inner space of the battery housing 20. In order to form the electrode terminal 50 after riveting the preform, the gap-filling jig has grooves and protrusions on the side facing the preform that correspond to the final shape of the electrode terminal 50.

[0221] Next, the filling fixture is moved downwards to pressurize the upper part of the preform, causing the preform to deform into the riveted electrode terminal 50.

[0222] During the pressurization of the preform by the filling fixture, the outer gasket 54a, sandwiched between the outer flange 50b and the outer surface of the plug 20a of the battery casing 20, is elastically compressed, reducing its thickness. Furthermore, the portion of the inner gasket 54b sandwiched between the inner edge 24 of the through hole 23 and the preform is elastically compressed by the inner flange 50c, further reducing its thickness compared to other areas. In particular, the area where the thickness of the inner gasket 54b is concentrated is... Figure 14 The portion indicated by the dashed circle. This significantly improves the sealing and airtightness between the riveted electrode terminals 50 and the battery casing 20.

[0223] Preferably, the insulating gasket 54 is sufficiently compressed to ensure the desired sealing strength without physical damage during the riveting of the preform.

[0224] In one example, where the insulating gasket 54 is made of polybutylene terephthalate, preferably, the insulating gasket 54 has a compression ratio of 50% or more at the point where it is compressed to its minimum thickness. The compression ratio is the proportion of the thickness change before and after compression relative to the thickness before compression.

[0225] In another example, where the insulating gasket 54 is made of polyvinyl fluoride, preferably, the insulating gasket 54 has a compression ratio of more than 60% at the point where it is compressed to its minimum thickness.

[0226] In yet another example, where the insulating gasket 54 is made of polypropylene, preferably, the insulating gasket 54 has a compression ratio of 60% or more at the point where it is compressed to its minimum thickness.

[0227] Preferably, the up-and-down movement of the filling fixture can be performed at least twelve times to perform staged pressure forming of the upper part of the preform. That is, the preform can be staged and deformed multiple times. At this time, the pressure applied to the filling fixture can be increased in stages. If this is done, the stress applied to the preform is distributed multiple times, thereby preventing damage to the insulating gasket 54 during the filling process. In particular, damage to the gasket is minimized when the inner gasket 54b portion sandwiched between the inner edge 24 of the through hole 23 and the preform is concentratedly compressed by the inner flange portion 50c.

[0228] After the preform is pressurized using the gap-filling fixture, the gap-filling fixture is separated from the battery casing 20, thus obtaining the riveting structure of the electrode terminal 50 according to an embodiment of the present invention, such as... Figure 14 As shown.

[0229] According to the above embodiment, the gap-filling fixture pressurizes and shapes the upper part of the preform by moving up and down inside the battery housing 20. A rotary fixture, as used in the prior art, can sometimes also be used to pressurize and shape the preform.

[0230] It should be noted that the rotary jig rotates at a predetermined angle with respect to the central axis of the battery housing 20. Therefore, a rotary jig with a large radius of rotation may interfere with the inner wall of the battery housing 20. Furthermore, when the battery housing 20 is deep, the length of the rotary jig also increases accordingly. In this case, the radius of rotation at the end of the rotary jig becomes larger, sometimes making it impossible to properly pressurize the preform. Therefore, pressurizing using a gap-filling jig is more efficient than using a rotary jig.

[0231] Figure 15 This is a cross-sectional view of a cylindrical battery 1 cut along the length direction Y according to an embodiment of the present invention. The overall structure of the cylindrical battery 1 has been described above; the following description will explain the overall structure of the cylindrical battery 1 from a different perspective.

[0232] Reference Figure 15 According to an embodiment, the cylindrical battery 1 includes a gel roll type electrode assembly 10. In the gel roll type electrode assembly 10, a sheet-shaped first electrode and a second electrode are wound up with a separation membrane sandwiched between them. The lower part exposes the uncoated portion 11 of the first electrode, and the upper part exposes the uncoated portion 12 of the second electrode.

[0233] In this embodiment, the first electrode can be the negative electrode and the second electrode can be the positive electrode. Of course, it can also be the opposite.

[0234] Method and reference for winding electrode assembly 10 Figure 1 as well as Figure 2 The described method is substantially the same as the method of winding the electrode assembly used in the manufacture of tabless cylindrical batteries according to the prior art.

[0235] When showing the electrode assembly 10, only the uncoated portions 11 and 12 extending outwards from the separation membrane are shown in detail; the first electrode, the second electrode, and the winding structure of the separation membrane are omitted.

[0236] The cylindrical battery 1 also includes a cylindrical battery housing 20 that houses the electrode assembly 10 and is electrically connected to the uncoated portion 11 of the first electrode.

[0237] Preferably, one side (lower part) of the battery housing 20 is open. Furthermore, the blocking portion 20a of the battery housing 20 has a structure in which the electrode terminals 50 are riveted to the through hole 23 by a gap-filling process.

[0238] Specifically, the electrode terminal 50 may include a main body portion 50a inserted into the through hole 23, an outer flange portion 50b extending along the outer surface of one side of the main body portion 50a exposed through the outer surface of the plug portion 20a of the battery housing 20, an inner flange portion 50c extending toward the inner surface of the other side of the main body portion 50a exposed through the inner surface of the plug portion 20a of the battery housing 20, and a flat portion 50d provided inside the inner flange portion 50c.

[0239] The cylindrical battery 1 may also include an insulating pad 54 sandwiched between the electrode terminal 50 and the through hole 23.

[0240] The cylindrical battery 1 may further include a sealing element that seals the open end of the battery casing 20 to achieve insulation from the battery casing 20. Preferably, the sealing element may include a non-polar cover plate 40 and a sealing gasket 60 sandwiched between the edge of the cover plate 40 and the open end of the battery casing 20.

[0241] The cover plate 40 can be made of conductive metals such as aluminum, steel, or nickel. Furthermore, the sealing gasket 60 can be made of insulating and elastic materials such as polypropylene, polybutylene terephthalate, or polyvinyl fluoride. However, the present invention is not limited to the materials of the cover plate 40 and the sealing gasket 60.

[0242] The cover plate 40 may include a vent 41 that ruptures when the internal pressure of the battery casing 20 exceeds a threshold. The vent 41 may be formed on both sides of the cover plate 40. The vent 41 may be formed on the surface of the cover plate 40 with a continuous or discontinuous circular pattern, a straight line pattern, or other patterns.

[0243] The battery housing 20 may include a crimping portion 22, which extends toward the inside of the battery housing 20 and is bent to secure the sealant, and together with the sealing gasket 60, wraps around the edge of the cover plate 40 for fixation.

[0244] The battery housing 20 may also include a rolled edge 21 pressed inward toward the inside of the battery housing 20 in the region adjacent to the open end. When the seal is secured by the crimping part 22, the rolled edge 21 supports the edge of the seal, especially the outer peripheral surface of the sealing gasket 60.

[0245] The cylindrical battery 1 may further include a first current collector 30 welded to the uncoated portion 11 of the first electrode. The first current collector 30 is made of a conductive metal such as aluminum, steel, or nickel. Preferably, at least a portion of the edge of the first current collector 30 that does not contact the uncoated portion 11 of the first electrode can be sandwiched between the rolled edge portion 21 and the sealing gasket 60 and fixed by the crimping portion 22. Optionally, at least a portion of the edge of the first current collector 30 can be fixed by welding to the inner circumferential surface of the rolled edge portion 21 adjacent to the crimping portion 22.

[0246] The cylindrical battery 1 may also include a second current collector 70 welded to the uncoated portion 12 of the second electrode. Preferably, at least a portion of the second current collector 70, such as the central portion, may be welded to the flat portion 50d of the electrode terminal 50.

[0247] Preferably, when welding the second current collector 70, the welding tool can be inserted through the take-up center hole C in the core of the electrode assembly 10 to reach the welding point of the second current collector 70. Furthermore, when welding the second current collector 70 to the flat portion 50d of the electrode terminal 50, the electrode terminal 50 supports the welding area of ​​the second current collector 70, thus applying stronger pressure to the welding area and improving welding quality. Moreover, the flat portion 50d of the electrode terminal 50 has a large area, ensuring a wide welding area. This reduces the contact resistance of the welding area, thereby reducing the internal resistance of the cylindrical battery 1. The face-to-face welding structure of the riveted electrode terminal 50 and the second current collector 70 is highly advantageous for rapid charging using a high charge rate (c-rate) current. This is because the cross-section in the direction of current flow can reduce the current density per unit area, thus reducing the heat generated in the current path compared to before.

[0248] When welding the flat portion 50d of the electrode terminal 50 and the second current collector 70, any one of laser welding, ultrasonic welding, spot welding, and resistance welding can be used. The area of ​​the flat portion 50d can be adjusted according to the welding method, but for the sake of welding strength and the convenience of the welding process, it is preferably 2 mm or more.

[0249] In one example, when the flattened portion 50d and the second collector plate 70 are laser welded into a continuous or discontinuous line in the shape of an arc pattern, preferably, the diameter of the flattened portion 50d is 4 mm or more. When the diameter of the flattened portion 50d meets the corresponding condition, the weld strength can be ensured, and there is no difficulty in inserting the laser welding tool into the take-up center hole C of the electrode assembly 10 to perform the welding process.

[0250] In another example, where the flattened portion 50d and the second collector plate 70 are ultrasonically welded into a circular pattern, preferably, the diameter of the flattened portion 50d is 2 mm or more. When the diameter of the flattened portion 50d meets the corresponding condition, the weld strength can be ensured, and there is no difficulty in inserting the ultrasonic welding tool into the take-up center hole C of the electrode assembly 10 to perform the welding process.

[0251] The cylindrical battery 1 may further include an insulator 80. The insulator 80 may be sandwiched between the inner surface of the second current collector 70 and the blocking portion 20a of the battery housing 20, and between the inner peripheral surface of the sidewall of the battery housing 20 and the electrode assembly 10. Preferably, the insulator 80 includes an insulator hole 80a that exposes the flat portion 50d of the electrode terminal 50 toward the second current collector 70, and may cover the surface of the second current collector 70 and one side (upper) edge of the electrode assembly 10.

[0252] Preferably, the uncoated portions 11 and 12 of the first electrode and / or the second electrode are bent from the outer periphery of the electrode assembly 10 toward the core, thereby forming bent surfaces on the upper and lower parts of the electrode assembly 10. Furthermore, the first current collector 30 can be welded to the bent surface formed when the uncoated portion 11 of the first electrode is bent, and the second current collector 70 can be welded to the bent surface formed when the uncoated portion 12 of the second electrode is bent.

[0253] To alleviate the stress generated when the uncoated portions 11 and 12 are bent, the first electrode and / or the second electrode may have the same characteristics as existing electrodes (see reference). Figure 1 Different improved structures.

[0254] Figure 16 This is a plan view illustrating the structure of electrode 90 according to a preferred embodiment of the present invention.

[0255] Reference Figure 16 The electrode 90 includes a sheet-shaped current collector 91 made of a conductive foil, an active material layer 92 formed on at least one side of the current collector 91, and an uncoated portion 93 at the long side end of the current collector 91 where no active material is coated.

[0256] Preferably, the uncoated portion 93 may include multiple cut-out slices 93a. The multiple slices 93a form multiple groups, and the height (length in the Y direction) and / or width (length in the X direction) and / or spacing of the multiple slices 93a belonging to each group may be the same. The number of multiple slices 93a belonging to each group may be increased or decreased compared to the number shown in the figures. The slices 93a may be trapezoidal in shape, and may also be modified into quadrilaterals, parallelograms, semicircles, or semi-ellipses.

[0257] Preferably, the height of the slice 93a can be increased in stages from the core side toward the outer periphery. Furthermore, the uncoated portion 93' on the core side adjacent to the core side may not include the slice 93a, and the height of the uncoated portion 93' on the core side may be lower than that of other uncoated portion areas.

[0258] Optionally, electrode 90 may include an insulating coating 94 covering the boundary between the active material layer 92 and the uncoated portion 93. The insulating coating 94 comprises an insulating polymer resin and may optionally include inorganic fillers. The insulating coating 94 serves to prevent the ends of the active material layer 92 from contacting the oppositely polar active material layer facing away from the separation membrane, structurally supporting the bending of the segment 93a. Therefore, preferably, when electrode 90 is wound into an electrode assembly, at least a portion of the insulating coating 94 is exposed to the outside from the separation membrane.

[0259] Figure 17 This is a cross-sectional view of an electrode assembly 100 cut along the length direction Y, in which the slit structure of the uncoated portion of the electrode 90 according to an embodiment of the present invention is applied to the first electrode and the second electrode.

[0260] Reference Figure 17 The electrode assembly 100 can be referenced Figure 1 as well as Figure 2 The winding process described herein. For ease of explanation, the protruding structures of the uncoated portions 11 and 12 extending beyond the separation membrane are shown in detail, while the winding structures of the first electrode, the second electrode, and the separation membrane are omitted. The downward-protruding uncoated portion 11 extends from the first electrode, and the upward-protruding uncoated portion 12 extends from the second electrode.

[0261] The pattern of height variation of the uncoated portions 11 and 12 is briefly illustrated. That is, the height of the uncoated portions 11 and 12 can vary irregularly depending on the location of the cut section. As an example, if the side portion of the trapezoidal slice 93a is cut, the height of the uncoated portion in the section is lower than the height of the slice 93a. Therefore, it should be understood that the heights of the uncoated portions 11 and 12 shown in the drawings illustrating the cross-section of the electrode assembly 100 correspond to the average height of the uncoated portions included in each winding pattern.

[0262] like Figure 18 As shown, the uncoated portions 11 and 12 can be bent from the outer periphery of the electrode assembly 100 toward the core side. Figure 17 In the diagram, the bent portion 101 is indicated by a dashed box. When the uncoated portions 11 and 12 are bent, multiple adjacent slices in the radial direction overlap each other in multiple layers, thereby forming a bent surface 102 on the upper and lower parts of the electrode assembly 100. At this time, the uncoated portion on the core side ( Figure 16 Because of its low height, the 93' section will not bend. The height h of the innermost bent section is the same as or smaller than the radial length r of the winding area formed by the uncoated portion 93' of the core without the section structure. Therefore, the winding center hole C located in the core of the electrode assembly 100 will not be closed by the multiple bent sections. If the winding center hole C is not closed, there is no difficulty in the electrolyte injection process, improving the electrolyte injection efficiency. Furthermore, by inserting a welding tool through the winding center hole C, the electrode terminal 50 can be easily welded to the second current collector 70.

[0263] According to an embodiment of the present invention, the cover plate 40 of the sealing member of the cylindrical battery 1 is not polarized. However, since the first current collector 30 is connected to the side wall of the battery housing 20, the outer surface of the blocking portion 20a of the battery housing 20 has a polarity opposite to that of the electrode terminals 50. Therefore, when it is necessary to connect multiple battery cells in series and / or in parallel, wiring such as busbar connection can be performed on the upper part of the cylindrical battery 1 using the outer surface of the blocking portion 20a of the battery housing 20 and the electrode terminals 50. As a result, the number of battery cells that can be mounted in the same space can be increased, thereby improving the energy density.

[0264] The following describes an embodiment of the positive electrode active material used in the cylindrical battery according to the present invention.

[0265] 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.

[0266] "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.

[0267] 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).

[0268] 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.

[0269] 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.

[0270] 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.

[0271] 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.

[0272] 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.

[0273] 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.

[0274] 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.

[0275] 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.

[0276] 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.

[0277] 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.

[0278] 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.

[0279] 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.

[0280] 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%.

[0281] 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 particle-shaped positive electrode active material, the increased side reactions with the electrolyte due to the increased microparticles generated from the secondary particles during electrode manufacturing and charge / discharge processes reduce the effect of suppressing gas generation, which may reduce the effect of improving stability when applied to large-scale batteries.

[0282] 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.

[0283] 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.

[0284] 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.

[0285] 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.

[0286] 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.

[0287] 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 unlocking process is too short, it indicates that excessive unlocking procedures have been performed. Due to this excessive unlocking, 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.

[0288] 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.

[0289] Mathematical formula (1): Particle size distribution (PSD) = (D max –D min ) / D 50

[0290] 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.

[0291] 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.

[0292] 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.

[0293] 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.

[0294] More specifically, the above-mentioned positive electrode active material may include lithium nickel oxide represented by the following [Chemical Formula 1].

[0295] [Chemical Formula 1]

[0296] Li a Ni b Co c M 1 d M 2 e O2

[0297] In the above chemical formula 1, M 1 It can be Mn, Al, or a combination thereof, preferably Mn or Mn and Al.

[0298] 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.

[0299] 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.

[0300] 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.

[0301] The above c represents the molar ratio of cobalt in the total metals other than lithium in the lithium-nickel-based oxide, which 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.

[0302] The above d represents M in the total metals other than lithium in the lithium-nickel-based oxide 1 the molar ratio of the element 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 M 1 when the molar ratio of the element satisfies the above range, good structural stability of the positive electrode active material can be achieved.

[0303] The above e represents M in the total metals other than lithium in the lithium-nickel-based oxide 2 the molar ratio of the element can be 0≤e≤0.1 or 0≤e≤0.05.

[0304] On the other hand, the positive electrode active material according to the present invention may further optionally comprise a coating, wherein the coating comprises one or more coating elements selected from the group consisting of Al, Ti, W, B, F, P, Mg, Ni, Co, Fe, Cr, V, Cu, Ca, Zn, Zr, Nb, Mo, Sr, Sb, Bi, Si and S on the surface of the lithium-nickel-based oxide particles. Preferably, the coating element can be Al, B, Co or a combination thereof.

[0305] In the case where a coating is present on the surface of the lithium-nickel-based oxide particles, the coating inhibits the contact between the electrolyte and the lithium-nickel-based oxide, thereby achieving the effect of reducing the elution of transition metals or gas generation caused by side reactions with the electrolyte.

[0306] Based on the total weight of the positive electrode active material layer, the positive electrode active material may be comprised in an amount of 80 wt% to 99 wt%, preferably 85 wt% to 99 wt%, more preferably 90 wt% to 99 wt%.

[0307] 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.

[0308] 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.

[0309] 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.

[0310] 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.

[0311] 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.

[0312] The aforementioned conductive nanomaterials can have various shapes, such as spherical, scaly, or fibrous.

[0313] 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.

[0314] 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.

[0315] 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%.

[0316] 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.

[0317] 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).

[0318] 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.

[0319] 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 .

[0320] 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.

[0321] 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.

[0322] 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.

[0323] 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.

[0324] 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.

[0325] 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%.

[0326] In one specific embodiment of the present invention, the conductive material may include carbon nanotubes.

[0327] 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.

[0328] 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 "new CNT".

[0329] Previously used carbon nanotubes (current CNTs) typically have a BET specific surface area of ​​less than 300 m². 2 / g. The novel CNTs used in this invention ( Figure 19 ) and existing CNTs Figure 20 The scanning electron microscope images and the comparison results of physical properties () Figure 21 )as follows.

[0330] The SEM images above show that the new CNTs applicable to this invention are bundle-like and have a multiwall structure. Compared with existing CNTs, they have a higher BET, a smaller wall number, and a smaller diameter.

[0331] 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%.

[0332] Figures 22 to 25 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.

[0333] 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.

[0334] 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.

[0335] 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.

[0336] 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.

[0337] 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.

[0338] 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.

[0339] 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.

[0340] Figure 26 The table shown illustrates the applicable BET specific surface area of ​​300m². 2 / g to 500m 2 / g of carbon nanotubes (new CNTs) and 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 (CNT) content of / g, as well as the resistivity in the MP coating and MP interface layer. The table shows that, with the new CNT, compared to existing CNTs, even with a higher solid content in the cathode slurry, it exhibits lower viscosity and better conductivity.

[0341] 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%.

[0342] Another aspect of the present invention relates to an electrode assembly including the above positive electrode and a battery including the same. The electrode assembly includes a negative electrode and a positive electrode, and the positive electrode has the structural features as described above.

[0343] For example, the above electrode assembly may be laminated with a separator interposed between the negative electrode and the positive electrode to form a stacked or stacked / folded structure, or wound to form a jelly-roll structure. Moreover, when forming a jelly-roll structure, a separator is additionally disposed on the outer side to prevent the negative electrode and the positive electrode from contacting each other.

[0344] The above negative electrode includes a negative electrode current collector; and a negative active material layer formed on at least one side surface of the negative electrode current collector. The negative electrode may be configured as a structure in which a negative active material layer is formed on one or both sides of an elongated negative electrode current collector, and the negative active material layer may include a negative active material, a conductive material and an adhesive.

[0345] Specifically, the above negative electrode is manufactured by the following method: coating one or both sides of an elongated negative electrode current collector with a negative electrode slurry prepared by dispersing a negative active material, a conductive material and an adhesive in a solvent such as dimethyl sulfoxide (DMSO), isopropyl alcohol, N-methylpyrrolidone (NMP), acetone, water, etc., removing the solvent of the negative electrode slurry through a drying process, and then performing calendering. A negative electrode including an uncoated portion can be manufactured by not coating the negative electrode slurry on a partial region of the negative electrode current collector, for example, one end of the negative electrode current collector when coating the negative electrode slurry.

[0346] As the above negative active material, a compound capable of reversible intercalation and deintercalation of lithium can be used. Specific examples of negative active materials include carbonaceous materials such as artificial graphite, natural graphite, graphitized carbon fibers, and amorphous carbon; Si, Si-Me alloys (wherein Me is at least one selected from the group consisting of Al, Sn, Mg, Cu, Fe, Pb, Zn, Mn, Cr, Ti and Ni), SiO y (wherein 0<y<2), silicon-based materials such as Si-C composites; lithium metal thin films; metal materials such as Sn and Al that can be alloyed with lithium; any one of the above or a mixture of two or more thereof can be used.

[0347] In the present invention, the above negative electrode may include a silicon-based negative active material. The silicon-based negative active material may be Si, a Si-Me alloy (wherein Me is at least one selected from the group consisting of Al, Sn, Mg, Cu, Fe, Pb, Zn, Mn, Cr, Ti and Ni), SiO y(wherein 0<y<2), Si-C composite or a combination thereof, preferably SiO y (wherein 0<y<2). Silicon-based negative electrode active materials have high theoretical capacity, so when a silicon-based negative electrode active material is comprised, capacity characteristics can be improved.

[0348] The above-mentioned silicon-based negative electrode active material may be coated with M b a metal, in this case, the above M b metal may be a group I metal element or a group II metal element, specifically, may be Li, Mg or the like. Specifically, the above-mentioned silicon-based negative electrode active material may be M-coated b metal Si, SiO y (wherein 0<y<2), Si-C composite, and the like. In a metal-coated silicon-based negative electrode active material, although the capacity of the active material decreases slightly due to the coating element, it has high efficiency, so high energy density can be achieved.

[0349] Figure 50 is a graph showing changes 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 a silicon-based negative electrode active material and a carbon-based negative electrode active material as the negative electrode active material.

[0350] In Figure 50 , Low efficiency SiO represents uncoated SiO, and Ultra-High efficiency SiO represents Mg / Li-coated SiO. It can be known from Figure 50 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. Furthermore, it can be known that as the proportion of coated silicon-based negative electrode active material in the silicon-based negative electrode active material increases, the improvement effect on energy density is more excellent.

[0351] The above-mentioned silicon-based negative electrode active material may further comprise a carbon coating on the particle surface. In this case, based on the total weight of the silicon-based negative electrode active material, the above-mentioned carbon coating amount may be 20 wt% or less, preferably 1 to 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) and other methods.

[0352] In one embodiment of the present invention, the above-mentioned silicon-based negative electrode active material may have a capacity of 1000 to 4000 mAh / g, and the initial efficiency may be about 60 to 95%.

[0353] In still another embodiment of the present invention, D of the above-mentioned silicon-based negative electrode active material 50 may be 3 µm to 8 µm, Dmin ~D max It can be in the range of 0.5um to 30um.

[0354] 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.

[0355] 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.

[0356] 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%.

[0357] 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.

[0358] 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.

[0359] 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%.

[0360] 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%.

[0361] 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.

[0362] 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.

[0363] 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 appropriately selected without limitation, such as a pouch type or a metal can type, as is commonly used in the art.

[0364] 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.

[0365] Specifically, the electrolyte may include organic solvents and lithium salts.

[0366] 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.).

[0367] 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.

[0368] 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%.

[0369] In another embodiment of the invention, the positive electrode may include a load reduction section where the loading of the positive electrode active material is less than that of the 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.

[0370] 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 / P ratio 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.

[0371] Figure 46 This is a diagram illustrating an electrode assembly according to an embodiment of the present invention. Figure 47 It shows along Figure 46 A cross-sectional view of the section cut by the cutting line A-A'.

[0372] Reference Figure 38 as well as Figure 39 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.

[0373] 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.

[0374] 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.

[0375] 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.

[0376] 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.

[0377] 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.

[0378] 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.

[0379] 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.

[0380] 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.

[0381] 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.

[0382] 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.

[0383] 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.

[0384] 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.

[0385] 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.

[0386] 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.

[0387] 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.

[0388] Below, refer to Figures 40 to 45 A method for manufacturing an electrode assembly according to an embodiment of the present invention will be described in detail.

[0389] Figure 40 as well as Figure 41 This is a diagram illustrating the process of manufacturing a negative electrode according to an embodiment of the present invention. Specifically, Figure 40 This is a plan view of the negative electrode plate from above. Figure 41 View from the front Figure 40 A front view of the negative electrode plate.

[0390] Reference Figure 40 as well as Figure 41 According to an embodiment of the present invention, a method for manufacturing an electrode assembly includes the step of manufacturing a negative electrode sheet 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.

[0391] 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.

[0392] Among them, the third direction d3 and the fourth direction d4 are directions described with reference to the negative electrode sheet 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.

[0393] 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 42 This is a perspective view showing the negative electrode according to an embodiment of the present invention.

[0394] Reference Figures 40 to 42 , such as in Figure 40 as well as Figure 41 The portion indicated by the dashed line represents the area where each of the uncoated negative electrode portion 430 and the negative electrode active material portion 420 can be cut along a direction parallel to the third direction d3. This allows for the fabrication of multiple negative electrode sheets 400S, such as... Figure 42 This is the negative electrode 400 shown. That is, Figure 42 The negative electrode 400 is equivalent to for Figure 40 as well as Figure 41 One of a plurality of negative electrodes manufactured by cutting open the negative electrode sheet 400S. By cutting out the uncoated negative electrode portion 430 and the active negative electrode portion 420 in the negative electrode sheet 400S, it is possible to manufacture a negative electrode 400 in which the uncoated negative electrode portion 430 extends to one side.

[0395] 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.

[0396] Figure 43 as well as Figure 44 This is a diagram illustrating the process of manufacturing a positive electrode according to an embodiment of the present invention. Specifically, Figure 43 This is a plan view of the positive electrode tab from above. Figure 44 View from the front Figure 43 A front view of the positive electrode tab.

[0397] Reference Figure 43 as well as Figure 44 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.

[0398] 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.

[0399] 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.

[0400] Then, the positive electrode 500 can be manufactured by cutting open the uncoated portion 530 and the active material portion 220. Figure 45 This is a perspective view showing a positive electrode 500 according to an embodiment of the present invention.

[0401] Reference Figures 43 to 45 , such as in Figure 43 as well as Figure 44 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 45 This is the positive electrode shown as 500. That is, Figure 45 The positive electrode 500 is equivalent to for Figure 43 as well as Figure 44 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.

[0402] 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.

[0403] Refer to together Figure 38 , Figure 42 as well as Figure 45 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.

[0404] Refer again Figures 43 to 45 In 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.

[0405] 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 38 as well as Figure 39 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.

[0406] 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 44 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.

[0407] 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.

[0408] Reference Figure 45 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.

[0409] Reference Figure 38 as well as Figure 39 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.

[0410] 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.

[0411] 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.

[0412] 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.

[0413] Below, refer to Figures 46 to 49 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.

[0414] Figure 46 This is a diagram illustrating an electrode assembly according to a comparative example of the present invention. Figure 47 It shows along Figure 46 A cross-sectional view of the section cut by the cutting line B-B'.

[0415] Reference Figure 46 as well as Figure 47 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.

[0416] 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.

[0417] Figure 48 This is a diagram illustrating the process of manufacturing the negative electrode 700 according to a comparative example of the present invention.

[0418] Reference Figure 48 A negative electrode sheet 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.

[0419] On the other hand, refer to again Figure 46 as well as Figure 47 The 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.

[0420] Figure 49This is a diagram illustrating the process of manufacturing the positive electrode 800 according to a comparative example of the present invention.

[0421] Reference Figure 49 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.

[0422] 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.

[0423] That is, except for the load reduction section 500D (refer to...) Figure 43 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.

[0424] Reference Figure 46 as well as Figure 47 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.

[0425] Conversely, refer to Figure 38 as well as Figure 39 According 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.

[0426] contrast Figure 38 as well as Figure 39 The A1 area and Figure 46 as well as Figure 47 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.

[0427] 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.

[0428] 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.

[0429] 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.

[0430] 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.

[0431] 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.

[0432] 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.

[0433] 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.

[0434] Preferably, the cylindrical battery according to the present invention can be a tabless-less battery without electrode tabs, but it is not limited thereto.

[0435] 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.

[0436] 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.

[0437] The present invention will now be described in further detail through specific embodiments.

[0438] Example 1

[0439] In N-methylpyrrolidone, a mixture with an average particle size D was prepared at a weight ratio of 97.8:0.6:1.6. 50The 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.

[0440] 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.

[0441] 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 cylindrical battery casing, and then electrolyte is injected to manufacture a 4680 battery cell.

[0442] Comparative Example 1

[0443] 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.

[0444] Experimental Example 1

[0445] A hot box test was performed on the 4680 battery cells manufactured using Example 1 and Comparative Example 1.

[0446] 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 30 as well as Figure 31The measurement results are shown.

[0447] Figure 30 This is a graph showing the hot box test results of the 4680 battery cell manufactured according to Example 1. Figure 31 This is a graph showing the hot box test results of the 4680 battery cell manufactured using Comparative Example 1.

[0448] pass Figure 30 as well as Figure 31 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.

[0449] Example 2-1

[0450] 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 27 SEM images of the positive electrode active material used in Example 2-1 are shown.

[0451] 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.

[0452] 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.

[0453] 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 the battery casing, and then electrolyte is injected to manufacture a 4680 battery cell.

[0454] Example 2-2

[0455] 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 28 SEM images of the positive electrode active material used in Examples 2-2 are shown.

[0456] Comparative Example 2-1

[0457] 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.

[0458] Comparative Example 2-2

[0459] 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 [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.

[0460] Figure 29 SEM images of the positive electrode active material used in Comparative Example 2-2 are shown.

[0461] Experimental Example 2-1

[0462] 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.

[0463] Specifically, each of the 4680 battery cells manufactured according to 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 heating 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 more than twice.

[0464] Table 1 below and Figure 32 , Figure 33 The test results are shown. Figure 28 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 33 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.

[0465] Table 1

[0466]

[0467] Refer to Table 1 above. Figure 32 as well as Figure 33 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… min The 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.

[0468] Experimental Example 2-2

[0469] 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 34 A cross-sectional SEM image of the positive electrode manufactured in Example 2-1 is shown. Figure 35 A cross-sectional SEM image of the positive electrode fabricated in Comparative Example 2-1 is shown.

[0470] pass Figure 34 as well as Figure 35It 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.

[0471] Example 3-1

[0472] 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%.

[0473] Example 3-2

[0474] 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%.

[0475] Example 3-3

[0476] 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%.

[0477] Examples 3-4

[0478] 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%.

[0479] Comparative Example 3-1

[0480] 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%.

[0481] Comparative Example 3-2

[0482] 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%.

[0483] Experimental Example 3-1 - Measurement of Charge / Discharge Capacity and Charge / Discharge Efficiency

[0484] 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.

[0485] Table 2

[0486]

[0487]

[0488] 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.

[0489] Experiment Example 3-2 - Confirmation of Resistance Characteristics

[0490] 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 36 The experimental results are shown.

[0491] Reference Figure 36It 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.

[0492] Experimental Example 3-3 - Measurement of High-Temperature Service Life Characteristics and Resistance Increase Rate

[0493] 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 casing, and then electrolyte was injected to manufacture a 4680 battery cell.

[0494] 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.

[0495] 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 37 The measurement results are shown.

[0496] Reference Figure 37 Compared 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.

[0497] In the cylindrical battery of the present invention, as described above, the positive electrode can be the first electrode and the negative electrode can be the second electrode. Furthermore, conversely, the positive electrode can be the second electrode and the negative electrode can be the first electrode.

[0498] 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 includes a first electrode having a first uncoated portion and a second electrode having a second uncoated portion; The battery casing houses the electrode assembly through an opening formed on one side; The current collector includes a support portion disposed at the center of one side of the electrode assembly, at least one uncoated portion joint portion extending from the support portion and joined to the first uncoated portion, and at least one housing joint portion extending from the end of the uncoated portion joint portion and joined to the inner side of the battery housing. A cover plate that covers the aforementioned open portion; Electrode terminals, which are riveted through through holes formed in the plug portion of the battery casing and electrically connected to the second uncoated portion, wherein the plug portion is located on the opposite side of the open portion; and An insulating pad is sandwiched between the electrode terminal and the through hole. The aforementioned electrode terminals include: The main body is inserted into the aforementioned through hole; An external flange extends along the outer surface of the main body portion, which is exposed from the outer surface of the aforementioned plug portion. An internal flange portion extends toward the inner surface from the other side of the main body portion exposed through the inner surface of the aforementioned plug portion; and A leveling portion is provided inside the aforementioned inner flange portion, and The angle between the inner flange and the inner surface of the plug is between 0 and 60 degrees.

2. The cylindrical battery according to claim 1, characterized in that, The aforementioned housing joint is attached to the rolled edge of the aforementioned battery housing.

3. The cylindrical battery according to claim 1, characterized in that, The aforementioned housing joint includes: The contact portion is attached to the rolled edge of the aforementioned battery casing; and A connecting portion that connects the uncoated portion to the contact portion.

4. The cylindrical battery according to claim 3, characterized in that, The aforementioned cylindrical battery includes a sealing gasket 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 secured by being sandwiched between the rolled edge portion of the battery casing and the aforementioned sealing gasket.

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

7. The cylindrical battery according to claim 1, characterized in that, The boundary area between the uncoated portion and the housing portion is located inside the innermost part of the rolled edge portion of the battery housing.

8. The cylindrical battery according to claim 1, characterized in that, The aforementioned cylindrical batteries each have multiple uncoated portion joints and housing 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 of the battery casing.

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 inner surfaces of the aforementioned flattened portion and the aforementioned blocking portion are parallel to each other.

13. The cylindrical battery according to claim 1, characterized in that, There is a recess between the aforementioned internal flange portion and the aforementioned flat portion.

14. The cylindrical battery according to claim 13, characterized in that, The aforementioned recessed portion has an asymmetrical groove cross-sectional structure.

15. The cylindrical battery according to claim 14, characterized in that, The aforementioned asymmetrical groove includes the sidewall of the aforementioned flat portion and the inclined surface of the aforementioned internal flange portion connected to the end of the aforementioned sidewall.

16. The cylindrical battery according to claim 15, characterized in that, The aforementioned sidewall is perpendicular to the inner surface of the aforementioned blockage.

17. The cylindrical battery according to claim 1, characterized in that, The thickness of the aforementioned internal flange decreases as it moves further away from the aforementioned main body.

18. The cylindrical battery according to claim 1, characterized in that, The aforementioned insulating pads include: An external gasket, sandwiched between the outer surface of the external flange and the outer surface of the plug; and An internal gasket is sandwiched between the inner surface of the aforementioned internal flange and the inner surface of the aforementioned plug. The thickness of the inner gasket and the outer gasket varies depending on their location.

19. The cylindrical battery according to claim 18, characterized in that, In the region of the aforementioned internal gasket, the thickness of the area between the inner edge of the through hole connected to the inner surface of the aforementioned plug and the aforementioned internal flange is relatively smaller than that of other areas.

20. The cylindrical battery according to claim 19, characterized in that, The inner edge of the aforementioned through hole includes a face opposite to the aforementioned inner flange.

21. The cylindrical battery according to claim 18, characterized in that, The aforementioned internal gasket extends to a length greater than the aforementioned internal flange.

22. The cylindrical battery according to claim 18, characterized in that, Based on the inner surface of the aforementioned blocking portion, the height of the aforementioned flat portion is the same as or higher than the end height of the aforementioned internal gasket.

23. The cylindrical battery according to claim 1, characterized in that, Based on the inner surface of the aforementioned blocking portion, the height of the aforementioned flat portion is the same as or higher than the end height of the aforementioned inner flange portion.

24. The cylindrical battery according to claim 1, characterized in that, The active material layer of the second electrode described above comprises positive electrode active materials including 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.

25. The cylindrical battery according to claim 24, 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. The particle size distribution, expressed by the following mathematical formula, is that the PSD is below 3: Particle size distribution (PSD) = (D max –D min ) / D 50 .

26. The cylindrical battery according to claim 24, 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%.

27. The cylindrical battery according to claim 24, characterized in that, The aforementioned positive electrode active material includes a lithium nickel oxide, which contains more than 80 mol% Ni based on the total molar number of transition metals.

28. The cylindrical battery according to claim 24, 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%.

29. The cylindrical battery according to claim 24, characterized in that, The active material layer of the second electrode also includes carbon nanotubes.

30. The cylindrical battery according to claim 24, 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.

31. A battery pack, characterized in that, include: Cylindrical battery according to any one of claims 1 to 30; as well as The battery pack housing contains multiple of the aforementioned cylindrical batteries.

32. A car, characterized in that, include: The battery pack according to claim 31.

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