Cylindrical battery, battery pack including the same, and automobile

Abstract

According to the present invention, a cylindrical battery, a battery pack including the cylindrical battery, and an automobile are provided. The cylindrical battery includes: an electrode assembly including a first electrode having a first uncoated portion and a second electrode having a second uncoated portion; a battery housing that houses the electrode assembly through an opening formed on one side and is electrically connected to the second uncoated portion; a cover plate that is configured to seal the opening of the battery housing; a current collector having an edge portion, an uncoated portion joining portion extending inward from the edge portion and joining with the first uncoated portion, and a terminal joining portion separately disposed from the uncoated portion joining portion; an electrode terminal that is riveted through a through hole formed in a plug portion of the battery housing and joined to the terminal joining portion, the plug portion being disposed on the opposite side of the opening portion; and an insulating gasket sandwiched between the upper electrode terminal and the through hole, wherein the electrode terminal includes: a body portion; an outer flange portion; an inner flange portion; and a flat portion.

Description

[0001] This application is a divisional application of Chinese invention patent application No. 202211272054.4, filed on October 18, 2022, entitled "Cylindrical Battery, Battery Pack Including the Cylindrical Battery and Automobile". Technical Field

[0002] This invention relates to a cylindrical battery, a battery pack including the cylindrical battery, and an automobile. Background Technology

[0003] Secondary batteries have a wide range of applications. Among them, battery packs used in devices such as electric vehicles require large capacity and high output. Furthermore, battery packs with such large capacity and high output, as unit cells, can include, for example, cylindrical batteries.

[0004] To improve current collection efficiency, cylindrical batteries with high capacity and high output characteristics have electrode tabs covering the entire area on both sides of the gel roll, and current collectors can be attached to both sides of the gel roll. By applying this structure, the contact area between the electrode tabs and the current collectors is maximized, thereby minimizing the resistance generated at the connection points between components.

[0005] As mentioned above, when cylindrical batteries are used in devices such as automobiles, they may be frequently subjected to external impacts and vibrations during use, which could cause damage to the joints used for electrical connections between components. Such damage to the joints leads to product defects.

[0006] Alternatively, even if the electrical connection is not completely blocked due to damage to the joint used for the electrical connection, if part of the welded area is damaged, resulting in a reduction in the joint area between the components, there may still be problems such as excessive heat due to increased resistance or internal short circuits due to component deformation.

[0007] Therefore, there is a need to develop cylindrical batteries with a structure that can prevent force concentration at the joints between components even when external impacts and / or vibrations are applied during use.

[0008] 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.

[0009] 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.

[0010] 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.

[0011] On the other hand, as types of secondary battery cells, cylindrical, square, and pouch-shaped 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 sealing the opening of the battery casing, and the negative electrode terminal is the battery casing itself.

[0012] 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.

[0013] 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.

[0014] 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.

[0015] 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 2The 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.

[0016] 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.

[0017] 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.

[0018] 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.

[0019] 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.

[0020] 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.

[0021] 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.

[0022] 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 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.

[0023] 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.

[0024] 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.

[0025] 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 the electrical wiring causes considerable trouble for the assembly process of electric vehicles and the maintenance of the battery pack.

[0026] 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.

[0027] 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

[0028] Technical problems to be solved

[0029] The present invention was made in view of the above-mentioned problems. One object is to disperse the impact and / or vibration even when an external impact and / or vibration is applied during the use of a secondary battery, rather than concentrating it in a specific area, thereby preventing damage to the joints between components.

[0030] On the other hand, another objective of the present invention is that, even without adding a current-blocking component, the current can be quickly blocked when an overcurrent occurs due to a short circuit, thereby ensuring the safety of the secondary battery.

[0031] This invention was made against the background of the prior art described above. By improving the electrode terminal structure of the cylindrical battery cell, the space efficiency within the battery casing is increased, thereby reducing the internal resistance of the cylindrical battery cell and increasing the energy density.

[0032] Another technical objective of this invention is to improve the internal heat generation problem that occurs during fast charging by improving the electrode terminal structure of the cylindrical battery cell and increasing the cross-sectional area of ​​the current path.

[0033] Another technical problem of the present invention is to provide a cylindrical battery cell with an improved structure, which allows for electrical wiring operations on one side of the cylindrical battery cell to realize series and / or parallel connections of the cylindrical battery cells.

[0034] Another technical problem of the present invention is to provide a battery pack manufactured using a cylindrical battery cell having an improved structure and an automobile including the same.

[0035] 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.

[0036] Another technical problem of the present invention is to provide an electrode assembly that increases the positive electrode active material region without worrying about lithium deposition.

[0037] 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.

[0038] 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.

[0039] means of solving technical problems

[0040] 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 and electrically connected to the second uncoated portion; a cover plate configured to seal the opening of the battery casing; a current collector having an edge portion, an uncoated portion joining portion extending inward from the edge portion and joined to the first uncoated portion, and a terminal joining portion separately disposed from the uncoated portion joining portion; an electrode terminal riveted through a through hole formed in a plug portion of the battery casing and joined to the terminal joining 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. The electrode terminal includes: a main body portion inserted into the through hole; an outer flange portion extending along the outer surface of the blockage portion from one side of the main body portion exposed through the outer surface of the blockage portion of the battery housing; 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 blockage portion; and a flat portion provided inside the inner flange portion and engaged with the terminal engagement portion.

[0041] The aforementioned uncoated portion and the aforementioned terminal portion can be electrically connected through the aforementioned edge portion.

[0042] The aforementioned terminal joint may be located at the center of the inner space of the aforementioned edge portion.

[0043] The aforementioned current collector may further include a connecting portion that extends inward from the aforementioned edge portion and connects to the aforementioned terminal junction portion.

[0044] The aforementioned connecting portion may have a cut-off portion formed to reduce the width of the connecting portion.

[0045] The aforementioned uncoated portion can be joined to the joint surface formed by bending the end of the first uncoated portion in a direction parallel to the current collector.

[0046] The cover plate may not be electrically connected to the electrode assembly, thus it is not polar.

[0047] The inner surfaces of the aforementioned flattened portion and the aforementioned blocking portion can be parallel to each other.

[0048] 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.

[0049] There may be a recess between the aforementioned internal flange portion and the aforementioned flat portion.

[0050] The aforementioned recessed portion can have an asymmetrical groove cross-sectional structure.

[0051] 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.

[0052] The aforementioned sidewall may be perpendicular to the inner surface of the aforementioned blockage.

[0053] The thickness of the aforementioned internal flange portion can decrease as it moves away from the aforementioned main body portion.

[0054] 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.

[0055] 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.

[0056] The inner edge of the aforementioned through hole may include a surface opposite to the aforementioned inner flange.

[0057] The aforementioned internal gasket may be extended to be longer than the aforementioned internal flange.

[0058] 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.

[0059] 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.

[0060] The active material layer of the first electrode may comprise positive electrode active material including single particles, similar single particles, or combinations thereof, wherein the minimum particle size D exhibited in the volumetric cumulative distribution of the positive electrode active material is... min The particle size D can be above 1.0 μm, and it accounts for 50% of the volume accumulation in the volume accumulation distribution 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.

[0061] 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 cumulative particle size distribution curve, with a particle size distribution (PSD) of three or less, expressed by the following mathematical formula: Particle size distribution (PSD) = (Dmax –D min ) / D 50 Based on the total weight of the positive electrode active material contained in the active material layer of the first electrode, it may contain 95 wt% to 100 wt% of the above-mentioned single particles, similar single particles, or combinations thereof.

[0062] Based on the total molar number of transition metals, the above-mentioned positive electrode active material may include lithium nickel oxide containing more than 80 mol% Ni.

[0063] The porosity of the active material layer of the first electrode can be from 15% to 23%, and the active material layer of the first electrode contains flake graphite in a weight ratio of 0.05wt% to 5wt%.

[0064] The active material layer of the first electrode may also include carbon nanotubes.

[0065] The active material layer of the second 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.

[0066] 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.

[0067] 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.

[0068] Invention Effects

[0069] According to one aspect of the invention, even if an external impact and / or vibration is applied during the use of the secondary battery, the impact and / or vibration is dispersed rather than concentrated in a specific part, thereby preventing damage to the joints between components.

[0070] On the other hand, according to another aspect of the present invention, even without the addition of a current-blocking component, the current collector itself can perform the function of blocking current, thereby rapidly blocking the current when an overcurrent caused by a short circuit or the like occurs, ensuring the safety of the secondary battery.

[0071] 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.

[0072] 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.

[0073] 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.

[0074] 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.

[0075] 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.

[0076] According to another aspect of the invention, the positive electrode contains D 50 D max The positive electrode active material powder with an appropriate particle size distribution (PSD) can minimize the increase in resistance caused by using single particles, thereby achieving good capacity and output characteristics.

[0077] According to another aspect of the present invention, the positive electrode comprises a single-particle positive electrode active material covered with a conductive coating or comprises novel CNTs as a conductive material, thereby improving the conductivity of the electrode.

[0078] 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.

[0079] 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.

[0080] 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.

[0081] 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. Attached Figure Description

[0082] 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.

[0083] Figure 1 This is a plan view showing the electrode structure used in existing tabless cylindrical batteries.

[0084] Figure 2 This is a diagram illustrating the winding process of the electrode assembly contained in a conventional tabless cylindrical battery.

[0085] Figure 3 It is shown Figure 12 A diagram showing the process of welding a current collector plate to the bent surface of the uncoated part in the electrode assembly.

[0086] Figure 4 This is a cross-sectional view of an existing tabless cylindrical battery cut along its length Y direction.

[0087] Figure 5 This is a perspective view showing a cylindrical battery and a busbar for electrical connection of a plurality of cylindrical batteries according to an embodiment of the present invention.

[0088] Figure 6 This is a cross-sectional view showing the upper structure of a cylindrical battery according to an embodiment of the present invention.

[0089] Figure 7 This is a partial cross-sectional view showing a cylindrical battery according to an embodiment of the present invention.

[0090] Figure 8 This is a diagram showing the combination of the electrode assembly and the current collector (first current collector) of the present invention.

[0091] Figures 9 to 12 This is a diagram illustrating various configurations of a current collector (first current collector) according to an embodiment of the present invention.

[0092] Figure 13 as well as Figure 14This is a diagram illustrating various configurations of a current collector (first current collector) according to another embodiment of the present invention.

[0093] Figure 15 This is a partial cross-sectional view showing the lower structure of a cylindrical battery according to an embodiment of the present invention.

[0094] Figure 16 The following figure illustrates a cylindrical battery according to an embodiment of the present invention.

[0095] Figure 17 This is a block diagram illustrating a battery pack according to an embodiment of the present invention.

[0096] Figure 18 This is a diagram illustrating a car according to an embodiment of the present invention.

[0097] Figure 19 This is a cross-sectional view showing the riveting structure of the electrode terminals according to an embodiment of the present invention.

[0098] Figure 20 yes Figure 19 Enlarged cross-sectional view of the part represented by the dashed circle.

[0099] Figure 21 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.

[0100] Figure 22 This is a plan view illustrating an electrode structure according to a preferred embodiment of the present invention.

[0101] Figure 23 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.

[0102] Figure 24 This 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.

[0103] Figure 25 These are scanning microscope images of carbon nanotubes (currently CNTs), which were previously commonly used.

[0104] Figure 26 These are scanning microscope images of a novel CNT according to an embodiment of the present invention.

[0105] Figure 27 This is a table showing a comparison of the physical properties of existing CNTs and novel CNTs.

[0106] Figures 28 to 31 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.

[0107] Figure 32 The comparison shows that the specific surface area of ​​BET is 300m². 2 / g to 500m 2 / g of carbon nanotubes (novel CNTs) and their applications BET at 200m 2 / g or more and less than 300m 2 Table 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.

[0108] Figure 33 This is a SEM image of the positive electrode active material used in Example 2-1 of the present invention.

[0109] Figure 34 These are SEM images of the positive electrode active material used in Examples 2-2 of the present invention.

[0110] Figure 35 This is a SEM image of the positive electrode active material used in Comparative Example 2-2 of this invention.

[0111] Figure 36 This is a graph showing the hot box test results of the 4680 battery cell manufactured according to Embodiment 1 of the present invention.

[0112] Figure 37 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.

[0113] Figure 38 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.

[0114] Figure 39 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.

[0115] Figure 40 This is a cross-sectional SEM image of the positive electrode manufactured in Embodiment 2-1 of the present invention.

[0116] Figure 41 This is a cross-sectional SEM image of the positive electrode manufactured in Comparative Example 2-1.

[0117] Figure 42 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.

[0118] Figure 43 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 embodiments 3-1, 3-3 and Comparative Example 3-1 according to the present invention.

[0119] Figure 44 This is a diagram illustrating an electrode assembly according to an embodiment of the present invention.

[0120] Figure 45 It shows along Figure 44 A cross-sectional view of the section cut by the cutting line A-A'.

[0121] Figure 46 as well as Figure 47 This is a diagram illustrating the process of manufacturing a negative electrode according to an embodiment of the present invention.

[0122] Figure 48 This is a perspective view showing the negative electrode according to an embodiment of the present invention.

[0123] Figure 49 as well as Figure 50 This is a diagram illustrating the process of manufacturing a positive electrode according to an embodiment of the present invention.

[0124] Figure 51 This is a perspective view showing the positive electrode according to an embodiment of the present invention.

[0125] Figure 52 This is a diagram illustrating an electrode assembly according to a comparative example of the present invention.

[0126] Figure 53 It shows along Figure 52 A cross-sectional view of the section cut by the cutting line B-B'.

[0127] Figure 54 This is a diagram illustrating the process of manufacturing a negative electrode according to a comparative example of the present invention.

[0128] Figure 55 This is a diagram illustrating the process of manufacturing a positive electrode according to a comparative example of the present invention.

[0129] Figure 56 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

[0130] 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.

[0131] 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.

[0132] 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.

[0133] 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.

[0134] 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.

[0135] 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.

[0136] Reference Figure 5 as well as Figure 6According to an embodiment of the present invention, a cylindrical battery 1 includes an electrode assembly 10, a battery casing 20, a cover plate 30, a current collector (first current collector) 40, and electrode terminals 50. In addition to the above-described constituent elements, the cylindrical battery 1 may further include a sealing gasket 80 and / or an insulating gasket 54 and / or an insulator 60 and / or a second current collector 70.

[0137] The electrode assembly 10 described above 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 may include a first electrode having a first polarity, a second electrode having a second polarity, and a separation membrane sandwiched between the first and second electrodes. The electrode assembly 10 can be manufactured by rolling up a laminate formed by sequentially stacking the first electrode, the separation membrane, and the second electrode 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 may be provided on the outer peripheral surface of the electrode assembly 10 to achieve insulation from the battery casing 20.

[0138] 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 6 A first uncoated portion 11, uncoated with the first electrode active material, is located on one side of the cylindrical battery 1 (alongside it in the height direction). This first uncoated portion 11 functions as a first electrode tab. The first uncoated portion 11 is provided in the height direction (alongside it in the height direction) of the electrode assembly 10 housed within the battery casing 20. Figure 6 The upper part of the cylindrical battery 1 shown (in the direction of parallel alignment in the height direction). The first uncoated part 11 mentioned above can be, for example, the positive electrode uncoated part.

[0139] 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 6 On 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 uncoated portion 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 negative electrode uncoated portion.

[0140] 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.

[0141] The battery casing 20 is a generally cylindrical housing with an opening at the bottom, and is made of a conductive material such as metal. For example, the battery casing 20 may be made of aluminum. The battery casing 20 has an opening at its lower end and a blocking portion 20a at its upper end. The battery casing 20 houses the electrode assembly 10 through the opening at the bottom, and also houses the electrolyte.

[0142] The battery casing 20 is electrically connected to the electrode assembly 10. For example, the battery casing 20 is electrically connected to the second uncoated portion 12 of the electrode assembly 10. Therefore, the battery casing 20 can have the same polarity as the second uncoated portion 12.

[0143] Reference Figure 6 as well as Figure 15 The battery housing 20 may include a rolled edge portion 21 and a pressing portion 22 formed at its lower end. The rolled edge portion 21 is located at the lower part of the electrode assembly 10. The rolled edge portion 21 is formed by pressing into the edge of the outer peripheral surface of the battery housing 20. The rolled edge portion 21 prevents the electrode assembly 10, which may have a size approximately corresponding to the width of the battery housing 20, from falling off through the opening formed at the lower end of the battery housing 20, and can function as a support portion for placing the cover plate 30.

[0144] The aforementioned crimping portion 22 is formed on the lower part of the rolled edge portion 21. The aforementioned crimping portion 22 has a shape that extends and bends in a manner that wraps around the outer peripheral surface of the cover plate 30 disposed below the rolled edge portion 21 and a portion of the lower surface of the cover plate 30.

[0145] It should be noted that the present invention does not exclude the possibility that the battery housing 20 does not have such a rolled edge portion 21 and / or a press-fit portion 22. In the present invention, when the battery housing 20 does not have a rolled edge portion 21 and / or a press-fit portion 22, the fixing of the electrode assembly 10 and / or the fixing of the cover plate 30 and / or the sealing of the battery housing 20 can be achieved, for example, by adding a component that can function as a stopper for the electrode assembly 10 and / or adding a structure that can house the cover plate 30 and / or by welding the battery housing 20 and the cover plate 30.

[0146] The plugged end of the battery casing 20, i.e., the region constituting it, can have a thickness ranging from about 0.5 mm to 1.0 mm, more preferably from about 0.6 mm to 0.8 mm. The sidewall portion constituting the outer peripheral surface of the battery casing 20 can have a thickness ranging from about 0.3 mm to 0.8 mm, more preferably from about 0.40 mm to 0.60 mm. According to an embodiment of the present invention, the battery casing 20 can be formed with a gold plating layer. In this case, the gold plating layer can include, for example, nickel (Ni). The thickness of the gold plating layer can range from about 1.5 µm to 6.0 µm.

[0147] The thinner the battery casing 20, the larger the internal space, thereby increasing the energy density and enabling the manufacture of a cylindrical battery 1 with a large capacity. Conversely, a thicker casing prevents the flame from being continuously transmitted to adjacent battery cells during an explosion test, thus providing a greater safety advantage.

[0148] The thinner the gold plating layer, the easier it is to corrode; the thicker the plating layer, the more difficult the manufacturing process becomes, or the greater the possibility of gold plating peeling. These conditions need to be considered to determine the optimal thickness of the battery casing 20 and the optimal thickness of the gold plating layer. Furthermore, these conditions need to be considered to control the thickness of the plug portion 20a and the sidewall portion of the battery casing 20, respectively.

[0149] Reference Figure 6 as well as Figure 15 To ensure rigidity, the cover plate 30 can be made of metal, for example. The cover plate 30 seals the opening formed at the lower end of the battery casing 20. That is, the cover plate 30 constitutes the lower surface of the cylindrical battery 1. In the cylindrical battery 1 of the present invention, the cover plate 30 may be non-polarized if it is made of a conductive metal. The non-polarity of the cover plate 30 indicates that the cover plate 30 is electrically insulated from the battery casing 20 and the electrode terminals 50. Thus, the cover plate 30 may be non-polarized, and its material does not necessarily have to be a conductive metal.

[0150] When the battery casing 20 of the present invention has a rolled edge portion, the cover plate 30 can be placed on the rolled edge portion 21 formed on the battery casing 20. Furthermore, when the battery casing 20 of the present invention has a crimping portion 22, the cover plate 30 can be fixed by the crimping portion 22. To ensure the airtightness of the battery casing 20, a sealing gasket 80 can be sandwiched between the cover plate 30 and the crimping portion 22 of the battery casing 20. On the other hand, as explained above, the battery casing 20 of the present invention may not have the rolled edge portion 21 and / or the crimping portion 22. In this case, to ensure the airtightness of the battery casing 20, the sealing gasket 80 can be sandwiched between the fixing structure provided on the open side of the battery casing 20 and the cover plate 30.

[0151] Reference Figure 15 as well as Figure 16 The cover plate 30 may also include a vent 31, which prevents the internal pressure from exceeding a predetermined value due to gas generated inside the battery casing 20. The vent 31 corresponds to a region in the cover plate 30 that is thinner than the surrounding area. The vent 31 is structurally more fragile than the surrounding area. Therefore, if the cylindrical battery 1 malfunctions and the internal pressure of the battery casing 20 increases to a certain level, the vent 31 will rupture, releasing the gas generated inside the battery casing 20. The vent 31 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 30.

[0152] According to an embodiment of the cylindrical battery 1 of the present invention, as will be described later, it has a structure in which both the positive and negative terminals are located in the upper part, thus the upper structure is more complex than the lower structure. Therefore, in order to smoothly discharge the gas generated inside the battery casing 20, a vent 31 can be formed in the cover plate 30 constituting the lower surface of the cylindrical battery 1. Figure 15 As shown, preferably, the lower end of the cover plate 30 is positioned above the lower end of the battery housing 20. In this case, even if the lower end of the battery housing 20 abuts against the ground or the bottom surface of the housing used to form the module or battery pack, the cover plate 30 will not abut against the ground or the bottom surface of the housing used to form the module or battery pack. Therefore, it is possible to prevent the pressure at which the vent hole 31 ruptures due to the weight of the cylindrical battery 1 from differing from the design value, thereby ensuring the smooth rupture of the vent hole 31.

[0153] On the other hand, the aforementioned vent 31 has such Figure 15 as well as Figure 16 In the case of the closed-loop shape shown, from the perspective of ease of rupture, the farther the distance from the center of the cover plate 30 to the vent hole 31, the more advantageous it is. This is because when the same ventilation pressure is applied, the farther the distance from the center of the cover plate 30 to the vent hole 31, the greater the force acting on the vent hole 31, and the easier it is to rupture. Furthermore, from the perspective of ease of gas discharge, the farther the distance from the center of the cover plate 30 to the vent hole 31, the more advantageous it is. Based on these points, the vent hole 31 extends downwards from the edge region of the cover plate 30 (within...) Figure 15 It is advantageous when the edge of a roughly flat area protrudes (in the direction of downwards) as a reference.

[0154] In the present invention Figure 16The illustration shows the vent 31 being continuously formed in a generally circular manner on the cover plate 30, but the present invention is not limited thereto. The vent 31 may also be formed discontinuously in a generally circular manner on the cover plate 30, or may be formed in a generally straight line shape or other shapes.

[0155] Reference Figures 6 to 8 The aforementioned current collector plate (first current collector plate) 40 is attached to the upper part of the electrode assembly 10. The aforementioned current collector plate 40 is made of a conductive metal material and is connected to the first uncoated portion 11.

[0156] Reference Figure 8 The aforementioned current collector 40 can be bonded to a bonding surface formed by bending the end of the first uncoated portion 11 in a direction parallel to the current collector 40. The bending direction of the first uncoated portion 11 can be, for example, towards the winding center hole C of the electrode assembly 10. With such a bent shape, the space occupied by the first uncoated portion 11 is reduced, thereby increasing the energy density. Furthermore, due to the increased bonding area between the first uncoated portion 11 and the current collector 40, the bonding strength is improved, and the resistance is reduced.

[0157] and Figures 6 to 8 Refer to together Figures 9 to 12 The aforementioned current collector 40 includes an edge portion 41, an uncoated portion joint portion 42, and a terminal joint portion 43. The edge portion 41 may have a generally circular (rim) shape with a central empty space S. The accompanying drawings only show the case where the edge portion 41 has a generally circular (rim) shape, but the invention is not limited to this. The edge portion 41 may also be a generally quadrilateral (rim) shape or other shapes, different from those shown in the drawings.

[0158] The uncoated portion 42 extends inward from the edge portion 41 and is connected to the first uncoated portion 11. The terminal portion 43 is spaced apart from the uncoated portion 42 and is located inside the edge portion 41. The terminal portion 43 can be welded to the electrode terminal 50 described later. The terminal portion 43 can, for example, be located at the center of the inner space of the edge portion 41. The terminal portion 43 can be positioned corresponding to the take-up center hole C of the electrode assembly 10.

[0159] The uncoated portion joint 42 and the terminal joint 43 are configured to be spaced apart from each other and not directly connected, but are electrically connected via the edge portion 41. Thus, the current collector 40 according to an embodiment of the present invention has a structure in which the uncoated portion joint 42 and the terminal joint 43 are not directly connected but connected via the edge portion 41. This allows for the dispersion of impacts applied to the joint between the uncoated portion joint 42 and the first uncoated portion 11, and the joint between the terminal joint 43 and the electrode terminal 50, in the event of impact and / or vibration in the cylindrical battery 1. Therefore, the current collector 40 of the present invention can minimize or prevent damage to the welded joints caused by external impacts. The current collector 40 of the present invention has a structure that allows stress to be concentrated at the connection between the edge portion 41 and the terminal joint 43 when an external impact is applied. However, this connection is not a welded portion for achieving the connection between components, thus preventing product defects caused by welded portion damage due to external impacts.

[0160] The aforementioned current collector 40 may further include a connecting portion 44 extending inward from the edge portion 41 and connecting to the terminal joint portion 43. The connecting portion 44 may be formed such that at least a portion of its width is narrower than the width of the uncoated joint portion 42. In this case, the resistance of the connecting portion 44 increases, resulting in a greater resistance than other portions when current flows through it. Consequently, in the event of an overcurrent, a portion of the connecting portion 44 breaks, thereby blocking the overcurrent. The width of the connecting portion 44 can be adjusted to an appropriate level to accommodate this overcurrent blocking function.

[0161] The connecting portion 44 may have a tapered portion 44a whose width gradually narrows along the direction from the inner side of the edge portion 41 toward the terminal joint portion 43. With the tapered portion 44a, the rigidity of the component can be improved at the connection between the connecting portion 44 and the edge portion 41.

[0162] Multiple uncoated joint portions 42 may be provided. These multiple uncoated joint portions 42 may be arranged at equal intervals along the extending direction of the edge portion 41. The extending length of each of the multiple uncoated joint portions 42 may be the same. The terminal joint portion 43 may be configured to be surrounded by the multiple uncoated joint portions 42. The connecting portion 44 may be located between a pair of adjacent uncoated joint portions 42. In this case, the distance from the connecting portion 44 along the extending direction of the edge portion 41 to any one of the pair of uncoated joint portions 42 may be the same as the distance from the connecting portion 44 along the extending direction of the edge portion 41 to the remaining one of the pair of uncoated joint portions 42.

[0163] Multiple connecting portions 44 may be provided. Each of the multiple connecting portions 44 may be disposed between a pair of adjacent uncoated portion joints 42. The multiple connecting portions 44 may be disposed at the same intervals from each other along the extending direction of the edge portion 41.

[0164] As described above, when multiple uncoated joint portions 42 and / or connecting portions 44 are provided, if the distance between the multiple uncoated joint portions 42 and / or the distance between the multiple connecting portions 44 and / or the distance between the uncoated joint portions 42 and the connecting portion 44 is formed to be uniform, the flow of current from the uncoated joint portion 42 toward the connecting portion 44 or from the connecting portion 44 toward the uncoated joint portion 42 can be smoothly formed.

[0165] Reference Figure 13 as well as Figure 14 The aforementioned connecting portion 44 may include a cut-off portion N formed to partially reduce the width of the connecting portion 44. When the cut-off portion N is provided, the resistance in the region where the cut-off portion N is formed increases, thereby enabling the current to be quickly blocked when an overcurrent occurs.

[0166] When the connecting portion 44 has a tapered portion 44a, the cut-off portion N can be positioned closer to the tapered portion 44a than the terminal connection portion 43. In this case, due to the tapered portion 44a structure whose width gradually narrows towards the center of the current collector plate 40, the cut-off portion N is located in a region adjacent to the area with higher heat generation, thereby blocking overcurrent more quickly.

[0167] Reference Figures 5 to 7 as well as Figure 9 The electrode terminal 50 is made of a conductive metal and is coupled to the terminal connection portion 43 of the current collector plate (first current collector plate) 40. The electrode terminal 50 may be configured to pass through the blocking portion 20a located on the side opposite to the open portion of the battery casing 20. In the case where the cylindrical battery 1 of the present invention includes an insulator 60, the electrode terminal 50 is configured to pass through the insulator 60 and then be coupled to the terminal connection portion 43 of the current collector plate 40.

[0168] Thus, the aforementioned electrode terminal 50 is electrically connected to the first uncoated portion 11 of the electrode assembly 10 via the current collector 40, thereby possessing a first polarity. Therefore, the aforementioned electrode terminal 50 can function as the first electrode terminal of the cylindrical battery 1 of the present invention. Furthermore, in the cylindrical battery 1 of the present invention, the generally flat surface formed on the side of the plug portion 20a of the battery casing 20, which has a second polarity, can function as a second electrode terminal. (Refer to...) Figure 1The first electrode terminal 50 and the second electrode terminal of the cylindrical battery 1 of the present invention are respectively connected to a busbar B. In each of the first electrode terminal 50 and the second electrode terminal, in order to ensure sufficient contact area for contact with the busbar B, the width D1 of the area exposed to the outside of the battery housing 20 in the first electrode terminal 50 can be set to be approximately 10% to 60% of the width D2 on the second electrode terminal, i.e., on the battery housing 20.

[0169] In the case where the electrode terminal 50 has a first polarity, the electrode terminal 50 is electrically insulated from the battery casing 20, which has a second polarity. Insulation between the electrode terminal 50 and the battery casing 20 can be achieved in various ways. For example, insulation can be achieved by sandwiching an insulating gasket 54 between the electrode terminal 50 and the battery casing 20. The insulating gasket 54 can be made of, for example, an insulating resin material.

[0170] In contrast, insulation can also be achieved by forming an insulating coating on a portion of the electrode terminal 50. Alternatively, the electrode terminal 50 can be structurally secured to prevent it from contacting the battery casing 20. Alternatively, various methods described above can be applied.

[0171] Reference Figure 6 as well as Figure 7 Also refer to Figure 9 The insulator 60 can be disposed between the current collector plate (first current collector plate) 40 and the inner side surface of the battery housing 20. The insulator 60 prevents contact between the current collector plate 40 and the battery housing 20. The insulator 60 can also be sandwiched between the upper end of the outer peripheral surface of the electrode assembly 10 and the inner side surface of the battery housing 20. This is to prevent contact between the first uncoated portion 11 extending toward the blockage portion 20a of the battery housing 20 and the inner peripheral surface of the battery housing 20.

[0172] In the case where the cylindrical battery 1 of the present invention includes an insulator 60, the electrode terminal 50 is connected to the current collector plate 40 after passing through the insulator 60. In order to allow the electrode terminal 50 to pass through, the insulator 60 may have an opening formed at a position corresponding to the terminal connection portion 43 of the current collector plate 40.

[0173] Reference Figure 15The aforementioned current collector plate (second current collector plate) 70 is attached to the lower part of the electrode assembly 10. The current collector plate 70 is made of a conductive metal and is attached to the second uncoated portion 12. Furthermore, the current collector plate 70 is electrically connected to the battery housing 20. The edge region of the current collector plate 70 can be fixed between the inner side of the battery housing 20 and the sealing gasket 80. In this case, the current collector plate 70 can also be welded to the placement surface formed by the rolled edge portion 21 of the battery housing 20.

[0174] Reference Figure 8 The aforementioned current collector 70 can be bonded to a bonding surface formed by bending the end of the second uncoated portion 12 in a direction parallel to the current collector 70. The bending direction of the second uncoated portion 12 can be, for example, towards the winding center hole C of the electrode assembly 10. With the second uncoated portion 12 having such a bent shape, the space occupied by the second uncoated portion 12 is reduced, thereby increasing the energy density. Furthermore, according to this embodiment, it is possible to achieve both increased bonding strength between the second uncoated portion 12 and the current collector 70 and reduced resistance.

[0175] 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 greater than 0.4.

[0176] 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.

[0177] 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.

[0178] 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.

[0179] 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.

[0180] 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.

[0181] 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.

[0182] 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.

[0183] Reference Figure 17 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.

[0184] Reference Figure 18 According to an embodiment of the present invention, the vehicle 5 may be, for example, an electric vehicle, a hybrid vehicle, or a plug-in hybrid vehicle, and includes a battery pack 3 according to an embodiment of the present invention. The vehicle 5 includes both four-wheeled and two-wheeled vehicles. The vehicle 5 operates by receiving power from the battery pack 3 according to an embodiment of the present invention.

[0185] Secondly, refer to Figures 19 to 24 A more detailed explanation will be given regarding the cylindrical battery 1 described above.

[0186] As described above, a cylindrical battery according to an embodiment of the present invention may include electrode terminals riveted to the bottom of the battery casing.

[0187] Figure 19 This is a cross-sectional view showing the riveting structure of the electrode terminal 50 according to an embodiment of the present invention. Figure 20 This is an enlarged cross-sectional view of the part represented by the dashed circle.

[0188] Reference Figure 19 as well as Figure 20According 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.

[0189] 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.

[0190] 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.

[0191] 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.

[0192] 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.

[0193] 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.

[0194] 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.

[0195] 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.

[0196] Preferably, the thickness of the inner flange portion 50c can be reduced as the body portion 50a moves away from the electrode terminal 50.

[0197] 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.

[0198] 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.

[0199] 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.

[0200] 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.

[0201] 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.

[0202] 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.

[0203] 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.

[0204] 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.

[0205] 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.

[0206] 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.

[0207] If R3 becomes smaller, then the current collector (first current collector) is welded to the flat portion 50d of the electrode terminal 50 (refer to...). Figure 21 If the welding space is insufficient (40), 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 increases, the thickness of the inner flange 50c will become thinner, and the force by which the inner flange 50c compresses the insulating gasket 54 will weaken, which may reduce the sealing ability of the insulating gasket 54.

[0208] 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 ( Figure 21 The welding area of ​​40) 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.

[0209] 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.

[0210] 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.

[0211] 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.

[0212] 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 20 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.

[0213] Preferably, the insulating gasket 54 is sufficiently compressed to ensure the desired sealing strength without physical damage during the riveting of the preform.

[0214] In one example, where the insulating gasket 54 is made of polybutylene terephthalate, preferably, the insulating gasket 54 achieves 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.

[0215] 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.

[0216] 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.

[0217] 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.

[0218] 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 20 As shown.

[0219] 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.

[0220] 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.

[0221] Figure 21 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.

[0222] Reference Figure 21 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 rolled up with a separation membrane sandwiched between them. The upper part exposes the uncoated portion 11 of the first electrode, and the lower part exposes the uncoated portion 12 of the second electrode.

[0223] 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.

[0224] 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.

[0225] 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.

[0226] 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 12 of the second electrode.

[0227] 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.

[0228] 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.

[0229] The cylindrical battery 1 may also include an insulating pad 54 sandwiched between the electrode terminal 50 and the through hole 23.

[0230] The cylindrical battery 1 may also include a seal that seals the open end of the battery casing 20 to achieve insulation from the battery casing 20. Preferably, the seal may include a non-polar cover plate 30 and a sealing gasket 80 sandwiched between the edge of the cover plate 30 and the open end of the battery casing 20.

[0231] The cover plate 30 can be made of conductive metals such as aluminum, steel, or nickel. Furthermore, the sealing gasket 80 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 30 and the sealing gasket 80.

[0232] The cover plate 30 may include a vent 31 that ruptures when the internal pressure of the battery casing 20 exceeds a threshold. The vent 31 may be formed on both sides of the cover plate 30. The vent 31 may be formed on the surface of the cover plate 30 with a continuous or discontinuous circular pattern, a straight line pattern, or other patterns.

[0233] 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 80, wraps around the edge of the cover plate 430 for fixation.

[0234] 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 80.

[0235] The cylindrical battery 1 may further include a second current collector 70 welded to the uncoated portion 12 of the second electrode. The second current collector 70 is made of a conductive metal such as aluminum, steel, or nickel. Preferably, at least a portion of the edge of the second current collector 70 that does not contact the uncoated portion 12 of the second electrode can be sandwiched between the rolled edge 21 and the sealing gasket 80 and fixed by the crimping portion 22. Optionally, at least a portion of the edge of the second current collector 70 can be fixed by welding to the inner circumferential surface of the rolled edge 21 adjacent to the crimping portion 22.

[0236] The cylindrical battery 1 may also include a first current collector 40 welded to the uncoated portion 11 of the first electrode. Preferably, at least a portion of the first current collector 40, such as the central portion, may be welded to the flat portion 50d of the electrode terminal 50.

[0237] Preferably, when welding the first current collector 40, 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 first current collector 40. Furthermore, when welding the first current collector 40 to the flat portion 50d of the electrode terminal 50, the electrode terminal 50 supports the welding area of ​​the first current collector 40, 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 first current collector 40 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.

[0238] When welding the flat portion 50d of the electrode terminal 50 and the first current collector 40, 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.

[0239] In one example, when the flattened portion 50d and the first current collector 40 are laser welded into a continuous or discontinuous line in an arc pattern, the diameter of the flattened portion 50d is preferably 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.

[0240] In another example, where the flattened portion 50d and the first current collector 40 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.

[0241] The cylindrical battery 1 may further include an insulator 60. The insulator 60 may be sandwiched between the inner surface of the first current collector 40 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 60 includes an insulator hole 60a that exposes the flat portion 50d of the electrode terminal 50 toward the first current collector 40, and may cover the surface of the first current collector 40 and one side (upper) edge of the electrode assembly 10.

[0242] 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 second current collector 70 can be welded to the bent surface formed when the uncoated portion 12 of the second electrode is bent, and the first current collector 40 can be welded to the bent surface formed when the uncoated portion 11 of the first electrode is bent.

[0243] 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.

[0244] Figure 22 This is a plan view illustrating the structure of electrode 90 according to a preferred embodiment of the present invention.

[0245] Reference Figure 22 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.

[0246] 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.

[0247] 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.

[0248] 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.

[0249] Figure 23 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.

[0250] Reference Figure 23 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 upward-protruding uncoated portion 11 extends from the first electrode, and the downward-protruding uncoated portion 12 extends from the second electrode.

[0251] 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.

[0252] like Figure 24 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 23 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 22 Because of its low height, the innermost bent slab (93') will not bend. The height h of the innermost bent slab is the same as or less than the radial length r of the winding area formed by the uncoated portion 93' of the core without the slab structure. Therefore, the winding center hole C located in the core of the electrode assembly 100 will not be closed by the multiple bent slabs. 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 first current collector 40.

[0253] According to an embodiment of the present invention, the cover plate 30 of the sealing member of the cylindrical battery 1 is not polarized. However, since the second current collector 70 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.

[0254] The following describes an embodiment of the positive electrode active material used in the cylindrical battery according to the present invention.

[0255] 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.

[0256] "Secondary particles" are particles formed by the aggregation of multiple primary particles. In this invention, in order 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.

[0257] 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).

[0258] 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.

[0259] 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.

[0260] 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.

[0261] 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.

[0262] 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.

[0263] 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.

[0264] 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 by a drying process, followed by calendering. Alternatively, by leaving a portion of the positive electrode current collector, such as one end, uncoated during the coating process, a positive electrode including an uncoated portion can be manufactured.

[0265] 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.

[0266] 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.

[0267] 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-ion 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 increases the mass of the active material, significantly increasing gas production and further escalating the risk of fire and / or explosion.

[0268] 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 results in less volume expansion and contraction of multiple primary particles during charging and discharging, significantly reducing internal cracking.

[0269] 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.

[0270] On the other hand, based on the total weight of the positive electrode active material contained in the positive electrode, the above-mentioned single particles and / or similar single particles contain 95wt% to 100wt%, preferably 98wt% to 100wt%, more preferably 99wt% to 100wt%, and even more preferably 100wt%.

[0271] When the content of single particles and / or similar single particles meets the above range, sufficient safety can be obtained when applied to large-scale batteries. This is because when the positive electrode active material contains more than 5 wt% of secondary particulate positive electrode active material, the increased dust generated from the secondary particles during electrode manufacturing and charge / discharge processes leads to side reactions with the electrolyte, thereby reducing the effect of suppressing gas generation. Consequently, the effect of improving stability may be reduced when applied to large-scale batteries.

[0272] 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.

[0273] 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.

[0274] 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.

[0275] 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.

[0276] 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.

[0277] Furthermore, the D of the aforementioned positive electrode active material max The diameter can be from 12 μm to 17 μm, preferably from 12 μm to 16 μm, and more preferably from 12 μm to 15 μm. When the D of the positive electrode active material... max When the above range is met, it exhibits better resistance and capacitance characteristics. When the D of the positive electrode active material... maxWhen the density is too high, aggregation occurs between multiple individual particles. The lithium migration path within these aggregated particles becomes longer, reducing lithium mobility and potentially increasing resistance. On the other hand, when the D of the positive electrode active material... max If the value is too small, it indicates that the crushing process has been overdone. Due to excessive crushing, D... min It is possible for the particle size to become smaller than 1 μm, which could cause particle cracking during calendering and potentially reduce thermal stability.

[0278] 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.

[0279] Mathematical formula (1): Particle size distribution (PSD) = (D max –D min ) / D 50

[0280] 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.

[0281] 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.

[0282] 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.

[0283] 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 at least 80 mol% Ni. Preferably, the aforementioned lithium nickel oxide may contain at least 80 mol% and less than 100 mol%, at least 82 mol% and less than 100 mol%, or at least 83 mol% and less than 100 mol% Ni. Using a lithium nickel oxide with a high Ni content as described above enables high capacity.

[0284] More specifically, the above-mentioned positive electrode active material may include lithium nickel oxide represented by the following [Chemical Formula 1].

[0285] [Chemical Formula 1]

[0286] Li a Ni b Co c M 1 d M 2 e O2

[0287] In the above chemical formula 1, M 1 It can be Mn, Al, or a combination thereof, preferably Mn or Mn and Al.

[0288] 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.

[0289] 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.

[0290] 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.

[0291] In the above, c represents the molar ratio of cobalt in the total metal other than lithium in the lithium nickel-based oxide, and can be 0 < c < 0.2, 0 < c < 0.18, 0.01 ≤ c ≤ 0.17, 0.01 ≤ c ≤ 0.15, 0.01 ≤ c ≤ 0.12 or 0.01 ≤ c ≤ 0.10. When the molar ratio of cobalt satisfies the above range, good resistance characteristics and output characteristics can be achieved.

[0292] In the above, d represents M in the total metal other than lithium in the lithium nickel-based oxide 1 The molar ratio of the element, and can be 0 < d < 0.2, 0 < d < 0.18, 0.01 ≤ d ≤ 0.17, 0.01 ≤ d ≤ 0.15, 0.01 ≤ d ≤ 0.12 or 0.01 ≤ d ≤ 0.10. When the molar ratio of the M 1 The element satisfies the above range, and good structural stability of the positive electrode active material is exhibited.

[0293] In the above, e represents M in the total metal other than lithium in the lithium nickel-based oxide 2 The molar ratio of the element, and can be 0 ≤ e ≤ 0.1 or 0 ≤ e ≤ 0.05.

[0294] On the other hand, according to the present invention, the positive electrode active material may further include a coating as needed. The coating contains one or more coating elements selected from the group consisting of Al, Ti, W, B, F, P, Mg, Ni, Co, Fe, Cr, V, Cu, Ca, Zn, Zr, Nb, Mo, Sr, Sb, Bi, Si, and S on the surface of the above lithium nickel-based oxide particles. Preferably, the above coating elements may be Al, B, Co, or a combination thereof.

[0295] When there is a coating on the surface of the lithium nickel-based oxide particles, the contact between the electrolyte and the lithium nickel-based oxide is suppressed by the coating, and thus the effect of reducing the dissolution of transition metals or the generation of gas caused by side reactions with the electrolyte can be obtained.

[0296] Relative to the total weight of the positive electrode active material layer, 80 wt% to 99 wt% of the above positive electrode active material may be included, preferably 85 wt% to 99 wt%, and more preferably 90 wt% to 99 wt%.

[0297] 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.

[0298] 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 with a conductive coating on the particle surface. The conductive coating may cover at least part or all of the particles. The conductive coating includes conductive nanomaterials.

[0299] 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.

[0300] 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.

[0301] 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.

[0302] The aforementioned conductive nanomaterials can have various shapes, such as spherical, scaly, or fibrous.

[0303] 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.

[0304] 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.

[0305] In one embodiment of the present invention, the above-mentioned flake graphite may be included in 0.1wt% to 5wt% of the above-mentioned positive electrode active material layer relative to 100wt%, preferably 0.1wt% to 3wt%.

[0306] 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.

[0307] 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).

[0308] 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.

[0309] 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 .

[0310] 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.

[0311] 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.

[0312] 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, and reduces 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 value range described above and improving the energy density.

[0313] 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.

[0314] 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.

[0315] 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%.

[0316] In one specific embodiment of the present invention, the conductive material may include carbon nanotubes.

[0317] 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 aforementioned 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 aforementioned conductive material is composed solely of the aforementioned multi-walled carbon nanotubes.

[0318] 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 termed "new CNT".

[0319] Previously used carbon nanotubes (current CNTs) typically have a BET specific surface area of ​​less than 300 m². 2 / g. The novel CNT used in this invention ( Figure 25 ) and existing CNT ( Figure 26 The scanning electron microscope images and the results of the comparison of physical properties () Figure 27 )as follows.

[0320] The SEM images above show that the novel CNTs applicable to this invention are bundle-shaped and have a multiwall structure. Compared with existing CNTs, they have a higher BET, a smaller wall number, and a smaller diameter.

[0321] 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 decreased 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 0.9wt%.

[0322] Figures 28 to 31 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.

[0323] 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.

[0324] 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.

[0325] 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%~80wt%, the slurry viscosity can be maintained at a low level.

[0326] 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.

[0327] 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.

[0328] Furthermore, the diameter of the aforementioned carbon nanotubes can be 1nm to 8nm, preferably 3nm to 8nm, and more preferably 3nm to 6nm.

[0329] 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.

[0330] Figure 32 The table shown illustrates the applicable BET specific surface area of ​​300m². 2 / g to 500m 2 / g of carbon nanotubes (novel CNTs) and their applicable BET of 200m 2 / g or more and less than 300m 2 The table above compares the solid content and viscosity of the cathode slurry with a carbon nanotube content of / g (existing CNTs), as well as the resistivity in the MP coating and MP interface layer. The table shows that, with the application of the new CNTs, even with a higher solid content in the cathode slurry compared to existing CNTs, it exhibits lower viscosity and better conductivity.

[0331] 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%.

[0332] Another aspect of the present invention relates to an electrode assembly including the above-mentioned positive electrode and a battery including the same. The electrode assembly includes a negative electrode and a positive electrode, and the positive electrode has the structural features as described above.

[0333] For example, the electrode assembly may be laminated in a state where a separator is sandwiched between the negative electrode and the positive electrode to form a stacked or stacked / folded structure, or wound to form a gel roll structure. Moreover, when forming the gel roll structure, in order to prevent the negative electrode and the positive electrode from contacting each other, a separator is additionally disposed on the outside.

[0334] The negative electrode includes a negative electrode current collector; and a negative electrode active material layer formed on at least one surface of the negative electrode current collector. The negative electrode may be configured to have a structure in which a negative electrode active material layer is formed on one or both surfaces of a strip-shaped negative electrode current collector, and the negative electrode active material layer may include a negative electrode active material, a conductive material, and a binder.

[0335] Specifically, the negative electrode is manufactured by the following method: a negative electrode paste in which a negative electrode active material, a conductive material, and a binder are dispersed in a solvent such as dimethyl sulfoxide (DMSO), isopropyl alcohol, N-methylpyrrolidone (NMP), acetone, or water is coated on one or both surfaces of a strip-shaped negative electrode current collector, the solvent of the negative electrode paste is removed through a drying process, and then calendering is performed. By a method of not coating the negative electrode paste on a part of the negative electrode current collector, for example, one end of the negative electrode current collector, a negative electrode including an uncoated portion can be manufactured.

[0336] The negative electrode active material may be a compound capable of reversibly inserting and extracting lithium. Specific examples of the negative electrode active material include carbonaceous materials such as artificial graphite, natural graphite, graphitized carbon fiber, and amorphous carbon; silicon-based materials such as Si, Si-Me alloy (where Me is one or more selected from the group consisting of Al, Sn, Mg, Cu, Fe, Pb, Zn, Mn, Cr, Ti, and Ni), SiO y (where 0 < y < 2), Si-C composite, etc.; lithium metal thin film; metal materials such as Sn and Al that can be alloyed with lithium; etc., and any one or a mixture of two or more thereof can be used.

[0337] In the present invention, the negative electrode may include a silicon-based negative electrode active material. The silicon-based negative electrode active material may be Si, Si-Me alloy (where Me is one or more selected from the group consisting of Al, Sn, Mg, Cu, Fe, Pb, Zn, Mn, Cr, Ti, and Ni), SiO y(where 0 < y < 2), Si-C composite, or a combination thereof, preferably SiO y (where 0 < y < 2). The silicon-based negative electrode active material has a high theoretical capacity, so when the silicon-based negative electrode active material is included, the capacity characteristics can be improved.

[0338] The above silicon-based negative electrode active material may be a material coated with M b metal. In this case, the above M b metal may be a Group I metal element or a Group II metal element. Specifically, it may be Li, Mg, etc. Specifically, the above silicon-based negative electrode active material may be Si, SiO b coated with M y (where 0 < y < 2), Si-C composite, etc. In the silicon-based negative electrode active material coated with metal, although the capacity of the active material decreases slightly due to the coating element, it has a high efficiency, so a high energy density can be achieved.

[0339] Figure 56 is a graph showing the change in energy density according to the content of the silicon-based negative electrode active material and whether the silicon-based negative electrode active material is coated in a battery using a mixture of the silicon-based negative electrode active material and the carbon-based negative electrode active material as the negative electrode active material.

[0340] In Figure 56 it, Low efficiency SiO means uncoated SiO, and Ultra-High efficiency SiO means SiO coated with Mg / Li. By Figure 56 it can be seen that as the content of the silicon-based negative electrode active material in the overall negative electrode active material increases, the energy density also increases. And it can be seen that as the proportion of the coated silicon-based negative electrode active material in the silicon-based negative electrode active material increases, the improvement effect of the energy density is more excellent.

[0341] The above silicon-based negative electrode active material may also include a carbon coating on the particle surface. In this case, based on the total weight of the silicon-based negative electrode active material, the carbon coating amount may be 20 wt% or less, preferably 1 - 20 wt%. The above carbon coating can be formed by dry coating, wet coating, chemical vapor deposition (CVD), physical vapor deposition (PVD), atomic layer deposition (ALD), etc.

[0342] In one embodiment of the present invention, the above silicon-based negative electrode active material may have a capacity of 1000 - 4000 mAh / g, and the initial efficiency may be about 60 - 95%.

[0343] In another other embodiment of the present invention, the D 50 of the above silicon-based negative electrode active material may be 3 um to 8 um, Dmin ~D max It can be in the range of 0.5um to 30um.

[0344] 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.

[0345] 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.

[0346] 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%.

[0347] 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.

[0348] 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.

[0349] 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% of the total weight of the negative electrode active material layer, preferably 1 wt% to 20 wt%, and more preferably 1 wt% to 10 wt%.

[0350] 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% of the total weight of the negative electrode active material layer, preferably 1 wt% to 20 wt%, and more preferably 1 wt% to 10 wt%.

[0351] 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.

[0352] 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.

[0353] 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, in a bag-like or metal can-like form, or other manner commonly used in the art.

[0354] 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.

[0355] Specifically, the electrolyte may include organic solvents and lithium salts.

[0356] 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.).

[0357] 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.

[0358] In addition to the constituent components of the electrolyte, the electrolyte may further include additives for the purpose of improving battery life characteristics, suppressing battery capacity reduction, and increasing 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%.

[0359] 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.

[0360] 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.

[0361] Figure 52 This is a diagram illustrating an electrode assembly according to an embodiment of the present invention. Figure 53 It shows along Figure 52 A cross-sectional view of the section cut by the cutting line A-A'.

[0362] Reference Figure 44 as well as Figure 45 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.

[0363] 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.

[0364] 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.

[0365] 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.

[0366] 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.

[0367] 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.

[0368] 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.

[0369] 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.

[0370] 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.

[0371] 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.

[0372] 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.

[0373] 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.

[0374] 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.

[0375] 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.

[0376] 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.

[0377] 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.

[0378] Below, refer to Figures 46 to 51 A method for manufacturing an electrode assembly according to an embodiment of the present invention will be described in detail.

[0379] Figure 46 as well as Figure 47 This is a diagram illustrating the process of manufacturing a negative electrode according to an embodiment of the present invention. Specifically, Figure 46 This is a plan view of the negative electrode tab from above. Figure 47 View from the front Figure 46 A front view of the negative electrode tab.

[0380] Reference Figure 46 as well as Figure 47 According to an embodiment of the present invention, a method for manufacturing an electrode assembly includes the step of manufacturing a negative electrode tab 400S in such a manner that a negative electrode active material portion 420 coated with a negative electrode active material and a negative electrode uncoated portion 430 uncoated with a negative electrode active material are alternately positioned on a negative electrode current collector 410.

[0381] Specifically, a negative electrode active material portion 420 can be formed by coating a negative electrode active material, making it continuous along the third direction d3. Furthermore, the coating area is separated along a fourth direction d4 perpendicular to the third direction d3, thereby separating the multiple negative electrode active material portions 420 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 multiple negative electrode active material portions 420.

[0382] Among them, the third direction d3 and the fourth direction d4 are directions described with reference to the negative electrode tab 400S, and are directions that are unrelated to the first direction d1 and the second direction d2 in the gel roll structure 300S described above.

[0383] 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 48 This is a perspective view showing the negative electrode according to an embodiment of the present invention.

[0384] Reference Figures 46 to 48 , such as in Figure 46 as well as Figure 47 The portion indicated by the dashed line represents the area where each of the uncoated negative electrode portion 430 and the active negative electrode portion 420 can be cut along a direction parallel to the third direction d3. This allows for the fabrication of multiple negative electrode tabs 400S. Figure 48 This is the negative electrode 400 shown. That is, Figure 48 The negative electrode 400 is equivalent to for Figure 46 as well as Figure 47 One of a plurality of negative electrodes manufactured by cutting open the negative electrode tab 400S. By cutting out the uncoated negative electrode portion 430 and the active negative electrode portion 420 in the negative electrode tab 400S, a negative electrode 400 with the uncoated negative electrode portion 430 extending to one side can be manufactured.

[0385] 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.

[0386] Figure 49 as well as Figure 50 This is a diagram illustrating the process of manufacturing a positive electrode according to an embodiment of the present invention. Specifically, Figure 49 This is a plan view of the positive electrode tab from above. Figure 50 View from the front Figure 49 A front view of the positive electrode tab.

[0387] Reference Figure 49 as well as Figure 50 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.

[0388] 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 separating the multiple positive electrode active material portions 520. 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.

[0389] 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.

[0390] Then, the positive electrode 500 can be manufactured by cutting open the uncoated portion 530 and the active material portion 220. Figure 51 This is a perspective view showing a positive electrode 500 according to an embodiment of the present invention.

[0391] Reference Figures 49 to 51 , such as in Figure 49 as well as Figure 50 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 51 The positive electrode shown is 500. That is, Figure 51 The positive electrode 500 is equivalent to for Figure 49 as well as Figure 50 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.

[0392] 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.

[0393] Refer to together Figure 44 , Figure 48 as well as Figure 51 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.

[0394] Refer again Figures 49 to 51In 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.

[0395] 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 44 as well as Figure 45 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.

[0396] 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 50 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.

[0397] 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.

[0398] Reference Figure 51 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.

[0399] Reference Figure 44 as well as Figure 45 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.

[0400] 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.

[0401] 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.

[0402] 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.

[0403] Below, refer to Figures 52 to 55 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.

[0404] Figure 52 This is a diagram illustrating an electrode assembly according to a comparative example of the present invention. Figure 53 It shows along Figure 52 A cross-sectional view of the section cut by the cutting line B-B'.

[0405] Reference Figure 52 as well as Figure 53 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.

[0406] 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.

[0407] Figure 54 This is a diagram illustrating the process of manufacturing the negative electrode 700 according to a comparative example of the present invention.

[0408] Reference Figure 54 A negative electrode tab 700S is manufactured by alternately positioning the negative electrode active material portion 720 and the negative electrode uncoated portion 730 in the fourth direction d4. Then, the negative electrode uncoated portion 730 and the negative electrode active material portion 720 are slitting to manufacture multiple negative electrodes 700.

[0409] On the other hand, refer to again Figure 52 as well as Figure 53The 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.

[0410] Figure 55 This is a diagram illustrating the process of manufacturing the positive electrode 800 according to a comparative example of the present invention.

[0411] Reference Figure 55 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.

[0412] 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.

[0413] That is, except for the load reduction section 500D (refer to...) Figure 49 In addition to the above, 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.

[0414] Reference Figure 52 as well as Figure 53 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.

[0415] Conversely, refer to Figure 44 as well as Figure 45According 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.

[0416] contrast Figure 44 as well as Figure 45 The A1 area and Figure 52 as well as Figure 53 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.

[0417] 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.

[0418] 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.

[0419] 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.

[0420] 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.

[0421] 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.

[0422] 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.

[0423] 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.

[0424] Preferably, the cylindrical battery according to the present invention can be a tabless-less battery without electrode tabs, but it is not limited thereto.

[0425] 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.

[0426] 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.

[0427] The present invention will now be described in further detail through specific embodiments.

[0428] Example 1

[0429] In N-methylpyrrolidone, a mixture with an average particle size D was prepared at a weight ratio of 97.8:0.6:1.6. 50 The positive electrode active material, Li[Ni], exhibits a single-peak particle size distribution of 3 μm and is a single-particle shape. 0.9 Co 0.06 Mn 0.03 Al 0.01 O2: Carbon nanotubes: PVDF binder, thereby producing a positive electrode slurry. The above positive electrode slurry is coated on one side of an aluminum current collector sheet, then dried at 120°C, and then rolled to produce the positive electrode.

[0430] 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.

[0431] 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.

[0432] Comparative Example 1

[0433] 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.

[0434] Experimental Example 1

[0435] A hot box test was performed on the 4680 battery cells manufactured using Example 1 and Comparative Example 1.

[0436] 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 36 as well as Figure 37 The measurement results are shown.

[0437] Figure 36 This is a graph showing the hot box test results of the 4680 battery cell manufactured according to Example 1. Figure 37 This is a graph showing the hot box test results of the 4680 battery cell manufactured using Comparative Example 1.

[0438] pass Figure 36 as well as Figure 37 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.

[0439] Example 2-1

[0440] 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 33 SEM images of the positive electrode active material used in Example 2-1 are shown.

[0441] 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.

[0442] 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.

[0443] 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.

[0444] Example 2-2

[0445] 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 34 SEM images of the positive electrode active material used in Examples 2-2 are shown.

[0446] Comparative Example 2-1

[0447] 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.

[0448] Comparative Example 2-2

[0449] 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.

[0450] Figure 35 SEM images of the positive electrode active material used in Comparative Example 2-2 are shown.

[0451] Experimental Example 2-1

[0452] 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.

[0453] Specifically, each of the 4680 battery cells manufactured in Example 2-1 and Comparative Example 2-1 was placed in a hot box chamber at room temperature and heated to 130°C at a rate of 5°C / min, then maintained at that temperature for 30 minutes. The temperature change of the battery was then measured. A test without thermal runaway or fire was recorded as "Pass," while a test with thermal runaway and / or fire was recorded as "Fail." Furthermore, to ensure accuracy, the battery cells from Examples 2-1 to 2-2 were tested more than twice.

[0454] Table 1 below and Figure 38 , Figure 39 The test results are shown. Figure 34 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 39 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.

[0455] Table 1

[0456] Refer to Table 1 above. Figure 38 as well as Figure 39 It can be seen that using D min In Example 2-1, the 4680 battery cell using a single-particle / similar-particle shape positive electrode active material larger than 1.0 μm stably maintained its voltage and temperature for up to 65 minutes. Conversely, in Comparative Example 2-1, which used secondary particles as the positive electrode active material, and in the example using D… minThe 4680 battery cells of Comparative Example 2-2, which contain single-particle / similar-particle shaped positive electrode active materials smaller than 1.0 μm, exhibited a rapid temperature rise.

[0457] Experimental Example 2-2

[0458] 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 40 A cross-sectional SEM image of the positive electrode manufactured in Example 2-1 is shown. Figure 41 A cross-sectional SEM image of the positive electrode fabricated in Comparative Example 2-1 is shown.

[0459] pass Figure 40 as well as Figure 41 It can be observed that the cathode of Example 2-1 showed almost no particle cracking of the cathode active material after calendering. In contrast, the cathode of Comparative Example 2-2, which used secondary particles, showed a lot of particle cracking of the cathode active material after calendering.

[0460] Example 3-1

[0461] 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%.

[0462] Example 3-2

[0463] 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%.

[0464] Example 3-3

[0465] 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%.

[0466] Examples 3-4

[0467] 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%.

[0468] Comparative Example 3-1

[0469] 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%.

[0470] Comparative Example 3-2

[0471] 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%.

[0472] Experimental Example 3-1 - Measurement of Charge / Discharge Capacity and Charge / Discharge Efficiency

[0473] 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.

[0474] Table 2

[0475] 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.

[0476] Experiment Example 3-2 - Confirmation of Resistance Characteristics

[0477] 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 42 The experimental results are shown.

[0478] Reference Figure 42 It can be seen that, based on a SOC of 10%, the resistance value of Example 3-3, which adds flake graphite to the positive electrode active material layer, is lower than that of Comparative Examples 3-1 and 3-2, which do not contain flake graphite. This indicates that adding flake graphite to the positive electrode active material layer has the effect of improving the resistance characteristics at lower SOCs.

[0479] Experimental Example 3-3 - Measurement of High-Temperature Service Life Characteristics and Resistance Increase Rate

[0480] 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.

[0481] At this point, the negative electrode is manufactured 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 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.

[0482] 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 43 The measurement results are shown.

[0483] Reference Figure 43Compared 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.

[0484] 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.

[0485] 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 and is electrically connected to the second uncoated portion. A cover plate, configured to seal the opening of the aforementioned battery casing; A current collector has an edge portion, an uncoated portion bonding portion extending inward from the edge portion and bonding with the first uncoated portion, and a terminal bonding portion disposed separately from the uncoated portion bonding portion. The electrode terminal is riveted through a through hole formed in the plug and is coupled to the terminal joint, wherein the plug is located on the opposite side of the open portion of the battery housing; as well as 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 portion extends along the outer surface of the main body portion, which is exposed from the outer surface of the plug portion of the battery housing. 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 flattening portion is provided on the inner side of the aforementioned inner flange portion and is engaged with the aforementioned terminal engagement portion.

2. The cylindrical battery according to claim 1, characterized in that, The uncoated portion and the terminal portion are electrically connected via the edge portion.

3. The cylindrical battery according to claim 1, characterized in that, The aforementioned terminal joint is located at the center of the inner space of the aforementioned edge portion.

4. The cylindrical battery according to claim 1, characterized in that, The aforementioned current collector also includes a connecting portion that extends inward from the aforementioned edge portion and connects to the aforementioned terminal junction portion.

5. The cylindrical battery according to claim 4, characterized in that, The aforementioned connecting portion has a cut-off portion formed to reduce the width of the connecting portion.

6. The cylindrical battery according to claim 1, characterized in that, The aforementioned uncoated portion is joined to the joint surface formed by bending the end of the first uncoated portion in a direction parallel to the current collector.

7. The cylindrical battery according to claim 1, characterized in that, The cover plate is not electrically connected to the electrode assembly and therefore does not have polarity.

8. 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.

9. The cylindrical battery according to claim 1, characterized in that, The angle between the inner surface of the aforementioned internal flange and the inner surface of the aforementioned plug is between 0 degrees and 60 degrees or less.

10. 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.

11. The cylindrical battery according to claim 10, characterized in that, The aforementioned recessed portion has an asymmetrical groove cross-sectional structure.

12. The cylindrical battery according to claim 11, 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.

13. The cylindrical battery according to claim 12, characterized in that, The aforementioned sidewall is perpendicular to the inner surface of the aforementioned blockage.

14. 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.

15. 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.

16. The cylindrical battery according to claim 15, 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.

17. The cylindrical battery according to claim 16, characterized in that, The inner edge of the aforementioned through hole includes a face opposite to the aforementioned inner flange.

18. The cylindrical battery according to claim 15, characterized in that, The aforementioned internal gasket extends to be longer than the aforementioned internal flange.

19. The cylindrical battery according to claim 15, 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.

20. 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.

21. The cylindrical battery according to claim 1, characterized in that, The active material layer of the first electrode described above includes a positive electrode active material, which comprises 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.

22. The cylindrical battery according to claim 21, characterized in that, The above-mentioned positive electrode active material has a unimodal particle size distribution exhibiting a single peak in the volumetric particle size distribution curve, and the particle size distribution (PSD) expressed by the following mathematical formula is below 3: Particle size distribution (PSD) = (D max –D min ) / D 50 .

23. The cylindrical battery according to claim 21, characterized in that, Based on the total weight of the positive electrode active material contained in the active material layer of the first electrode, the amount of the above-mentioned single particles, similar single particles, or combinations thereof is 95 wt% to 100 wt%.

24. The cylindrical battery according to claim 21, characterized in that, The aforementioned positive electrode active material includes lithium nickel oxide, which contains more than 80 mol% Ni based on the total molar number of transition metals.

25. The cylindrical battery according to claim 21, characterized in that, The porosity of the active material layer of the first electrode is 15% to 23%. The active material layer of the first electrode contains flake graphite in a weight ratio of 0.05 wt% to 5 wt%.

26. The cylindrical battery according to claim 21, characterized in that, The active material layer of the first electrode also includes carbon nanotubes.

27. The cylindrical battery according to claim 21, characterized in that, The active material layer of the aforementioned second electrode 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.

28. A battery pack, characterized in that, include: Cylindrical battery according to any one of claims 1 to 27; as well as The battery pack housing contains multiple of the aforementioned cylindrical batteries.

29. A car, characterized in that, include: The battery pack of claim 28.

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