Cylindrical battery, battery pack including the same, and automobile

Abstract

Provided according to the present application are a cylindrical battery, a battery pack including the cylindrical battery, and a vehicle, the cylindrical battery including: an electrode assembly including a first electrode having a first uncoated portion and a first coated portion, a second electrode having a second uncoated portion and a second coated portion, and a separator film interposed between the first electrode and the second electrode; a battery case accommodating the electrode assembly through an open portion formed on one side and electrically connected to the electrode assembly; a battery terminal penetrating a plug portion of the battery case on the opposite side of the open portion and electrically connected to the electrode assembly; and a cover configured to cover the open portion, wherein the first electrode includes at least one insulating layer configured to simultaneously cover at least a portion of the first uncoated portion and at least a portion of the first coated portion, and at least a portion of the first uncoated portion is used as an electrode tab by itself.

Description

Technical Field

[0001] This invention relates to a cylindrical battery, a battery pack including the cylindrical battery, and an automobile. Background Technology

[0002] In cylindrical batteries, to maximize current collection efficiency, a gel roll-type electrode assembly with a battery casing having positive and negative electrode tabs extending vertically along the height direction can be used.

[0003] In the structure described above, there is a possibility of movement such as the positive or negative electrode shifting. In this case, the end of the positive or negative electrode may be located near the end of the separator membrane. Therefore, when the positive or negative electrode is located at the end of the separator membrane or protrudes outward from the end of the separator membrane due to such movement, electrical contact between the positive and negative electrodes occurs. Alternatively, if the separator membrane is damaged for some reason, electrical contact between the positive and negative electrodes may also occur. As a result, a short circuit may occur inside the battery. If a short circuit occurs inside the battery, it may lead to overheating or explosion of the battery. Therefore, there is a need to provide an insulating component to effectively prevent electrical contact between the positive and negative electrodes.

[0004] Therefore, there is a need to find solutions for cylindrical battery cells, battery packs, and automobiles that can provide low internal resistance and low short-circuit risk.

[0005] When manufacturing battery packs using cylindrical batteries, multiple cylindrical batteries are typically arranged vertically inside a casing. The upper and lower ends of the cylindrical batteries are used as positive and negative terminals, respectively, thereby achieving electrical connection between the multiple cylindrical batteries.

[0006] This is because in a cylindrical battery, the uncoated negative electrode portion of the electrode assembly housed inside the battery casing extends downwards and is electrically connected to the bottom surface of the battery casing, while the uncoated positive electrode portion extends upwards and is electrically connected to the top cover. In other words, in a cylindrical battery, the bottom surface of the battery casing is typically used as the negative terminal, and the top cover covering the upper opening of the battery casing is used as the positive terminal.

[0007] However, when the positive and negative terminals of such a cylindrical battery are located on opposite sides, electrical connection components such as busbars for electrically connecting multiple cylindrical batteries need to be applied to the upper and lower parts of the cylindrical battery. This complicates the electrical connection structure of the battery pack.

[0008] In addition, in such a structure, components for achieving insulation and components for ensuring waterproofing or sealing need to be placed separately at the top and bottom of the battery pack, which leads to an increase in the number of components used and a more complex structure.

[0009] Therefore, there is a need to develop a cylindrical battery with a structure in which the positive and negative terminals are aligned in the same direction, so as to simplify the electrical connection structure of multiple cylindrical batteries.

[0010] In addition, when using existing positive electrode active materials that include secondary particles to manufacture electrodes, particle cracking occurs, and the amount of gas generated by internal cracks during charging and discharging increases, which may cause problems with battery stability.

[0011] 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, electrode cracking occurs when the electrode 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

[0012] Technical problems to be solved

[0013] The present invention was made in view of the above-mentioned problems, and one object is to provide a cylindrical battery structure having a positive terminal and a negative terminal that are oriented in the same direction.

[0014] One object of the present invention is to ensure that sufficient area can be welded for electrical connection components such as busbars used in manufacturing battery packs and electrode terminals of cylindrical batteries when realizing electrical connection of multiple cylindrical batteries in one direction.

[0015] Furthermore, the present invention was made in view of the above-mentioned problems, and its purpose is to reduce the internal resistance of cylindrical batteries while effectively preventing internal short circuits.

[0016] Another technical problem of the present invention is to provide an electrode, and an electrode assembly including the electrode, that uses single particles or similar single particles as positive electrode active materials to achieve good thermal stability, high conductivity and high rolling characteristics.

[0017] 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, thereby improving the energy density.

[0018] Another technical problem of the present invention is to provide an electrode assembly that increases the positive active material region without worrying about lithium deposition.

[0019] 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.

[0020] 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.

[0021] means of solving technical problems

[0022] A cylindrical battery according to an embodiment of the present invention, used to solve the above-mentioned technical problems, includes: an electrode assembly comprising a first electrode having a first uncoated portion and a first coated portion, a second electrode having a second uncoated portion and a second coated portion, and a separation membrane sandwiched between the first electrode and the second electrode; a battery housing housing the electrode assembly through an opening formed on one side and electrically connected to the electrode assembly; a battery terminal penetrating a blocking portion of the battery housing located on the opposite side of the opening and electrically connected to the electrode assembly; and a cover plate configured to cover the opening.

[0023] The first electrode includes at least one insulating layer configured to simultaneously cover at least a portion of the first uncoated portion and at least a portion of the first coated portion.

[0024] At least a portion of the first uncoated portion is used as an electrode tab.

[0025] The battery terminals can be electrically connected to the first uncoated portion having a first polarity, and the battery casing can be electrically connected to the second uncoated portion having a second polarity opposite to the first polarity.

[0026] The battery terminal may include: a terminal protrusion extending outward toward the outside of the battery housing; and a terminal insertion portion penetrating the blocking portion of the battery housing.

[0027] The aforementioned cylindrical battery may further include an insulating pad sandwiched between the battery casing and the battery terminals, thereby achieving insulation between the battery terminals and the battery casing.

[0028] The aforementioned insulating pad may include: a pad protrusion extending toward the outside of the battery housing; and a pad insertion portion penetrating the upper surface of the battery housing.

[0029] The aforementioned battery terminals can be riveted to the inner side of the aforementioned battery casing.

[0030] The cover plate described above can be insulated from the electrode assembly described above and is non-polar.

[0031] The aforementioned insulating layer can be disposed on both sides of the first electrode.

[0032] One end of the aforementioned insulating layer in the direction of the winding axis can be located at the same height as one end of the aforementioned separating membrane in the direction of the winding axis, or outside one end.

[0033] One end of the aforementioned insulating layer in the direction of the winding axis can be located at the same height as one end of the aforementioned separating membrane in the direction of the winding axis.

[0034] The first uncoated portion can protrude further outward from the outer side of the insulating layer.

[0035] The first coated portion mentioned above may not protrude further than the separation membrane in the winding axis direction.

[0036] The first electrode mentioned above can be a positive electrode.

[0037] One end of the second electrode, which is separated from the above-mentioned insulating layer by the above-mentioned separation membrane, may not protrude further outward than one end of the above-mentioned separation membrane.

[0038] The aforementioned first coated portion may include a landslide portion where the thickness of the active material layer is reduced compared to the central region of the aforementioned first coated portion.

[0039] The aforementioned landslide portion can be formed in the boundary region between the first coated portion and the first uncoated portion.

[0040] The aforementioned landslide portion can be respectively provided at one end of the first electrode and the other end of the second electrode.

[0041] The slip portion provided on the first coated portion of the first electrode and the slip portion provided on the second coated portion of the second electrode can be provided in opposite directions.

[0042] The separation membrane may protrude further outward than the other end of the first electrode and one end of the second electrode.

[0043] The aforementioned insulating layer is configured to cover at least a portion of the aforementioned landslide area.

[0044] 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 is 50% of the total volume of the above-mentioned positive electrode active material. 50 The maximum particle size D exhibited in the volumetric cumulative distribution of the above-mentioned positive electrode active material is below 5.0 μm. max It can be from 12μm to 17μm.

[0045] In the aforementioned cylindrical battery, the positive electrode active material can have a unimodal particle size distribution that exhibits a single peak in the volumetric particle size distribution curve, with a particle size distribution (PSD) of three or less, expressed by the following mathematical formula:

[0046] Particle size distribution (PSD) = (D max –D min ) / D 50

[0047] 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.

[0048] 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.

[0049] 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%.

[0050] The active material layer of the first electrode may also include carbon nanotubes.

[0051] 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.

[0052] In addition, according to an embodiment of the present invention, the battery pack includes the above-mentioned cylindrical battery; and the battery pack housing contains a plurality of the above-mentioned cylindrical batteries.

[0053] An automobile according to an embodiment of the present invention includes the above-described battery pack.

[0054] Invention Effects

[0055] According to one aspect of the invention, a cylindrical battery structure is provided having a positive terminal and a negative terminal applied in the same direction, thereby simplifying the electrical connection structure of multiple cylindrical batteries.

[0056] According to another aspect of the invention, the electrode terminals of the cylindrical battery have a sufficient area to be welded to electrical connection components such as busbars, thereby ensuring sufficient bonding strength between the electrode terminals and the electrical connection components, and reducing the resistance at the bonding site between the electrical connection components and the electrode terminals to a preferred level. That is, according to the invention, the internal resistance of the cylindrical battery can be significantly reduced.

[0057] Furthermore, according to the present invention, electrical contact between the positive and negative electrodes of the electrode assembly is prevented, thereby effectively preventing short circuits inside the cylindrical battery.

[0058] 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.

[0059] 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.

[0060] 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.

[0061] 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.

[0062] 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.

[0063] 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.

[0064] 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

[0065] 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.

[0066] Figure 1 This is a diagram illustrating a cylindrical battery according to an embodiment of the present invention.

[0067] Figure 2 yes Figure 1 A longitudinal cross-sectional view of a cylindrical battery.

[0068] Figure 3 It is used for explanation Figure 1 A diagram of the electrode assembly contained in a cylindrical battery.

[0069] Figure 4 It is shown Figure 3 A partial longitudinal cross-sectional view of the electrode assembly.

[0070] Figure 5 This is a diagram illustrating an electrode assembly according to another embodiment of the present invention.

[0071] Figure 6 It is shown Figure 5 A partial longitudinal cross-sectional view of the electrode assembly.

[0072] Figure 7 as well as Figure 8 It is used for explanation Figure 6 A diagram showing a modified example of the electrode assembly.

[0073] Figure 9 This is a comparative diagram used to illustrate the electrode assembly of the present invention.

[0074] Figure 10 It is a graph used to illustrate the power distribution in multiple short circuit scenarios within a secondary battery.

[0075] Figure 11 as well as Figure 12 This is a partial cross-sectional view of the upper structure of a cylindrical battery according to an embodiment of the present invention.

[0076] Figure 13 as well as Figure 14 This is a diagram illustrating the combined structure of the first current collector and electrode assembly applied to the present invention.

[0077] Figure 15 This is a partial cross-sectional view showing the upper structure of a cylindrical battery according to an embodiment of the present invention.

[0078] Figure 16 The following figure illustrates a cylindrical battery according to an embodiment of the present invention.

[0079] Figure 17 This is a diagram showing the second current collector applied to the present invention.

[0080] Figure 18 This is a diagram illustrating the battery pack of the present invention.

[0081] Figure 19 This is a diagram of a car used to illustrate the present invention.

[0082] Figure 20 These are scanning microscope images of carbon nanotubes (currently CNTs), which were previously commonly used.

[0083] Figure 21 These are scanning microscope images of the novel CNT according to an embodiment of the present invention.

[0084] Figure 22 This is a table showing a comparison of the physical properties of existing CNTs and novel CNTs.

[0085] Figures 23 to 26 This is a graph showing the sheet resistance and high-temperature lifetime characteristics of different conductive material ratios when single-particle active material particles are used as the positive electrode active material.

[0086] Figure 27 The comparison shows that the specific surface area of ​​BET is 300m². 2 / g to 500m 2 / g of carbon nanotubes (novel CNTs) and their applications BET at 200m 2 / g or more and less than 300m 2 Table 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.

[0087] Figure 28 This is a SEM image of the positive electrode active material used in Example 2-1 of the present invention.

[0088] Figure 29 These are SEM images of the positive electrode active material used in Examples 2-2 of the present invention.

[0089] Figure 30 This is a SEM image of the positive electrode active material used in Comparative Example 2-2 of this invention.

[0090] Figure 31 This is a graph showing the hot box test results of the 4680 battery cell manufactured according to Embodiment 1 of the present invention.

[0091] Figure 32 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.

[0092] Figure 33 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.

[0093] Figure 34 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.

[0094] Figure 35 This is a cross-sectional SEM image of the positive electrode manufactured in Embodiment 2-1 of the present invention.

[0095] Figure 36 This is a cross-sectional SEM image of the positive electrode manufactured in Comparative Example 2-1.

[0096] Figure 37 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.

[0097] Figure 38 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.

[0098] Figure 39 This is a diagram illustrating an electrode assembly according to an embodiment of the present invention.

[0099] Figure 40 It shows along Figure 39 A cross-sectional view of the section cut by the cutting line A-A'.

[0100] Figure 41 as well as Figure 42 This is a diagram illustrating the process of manufacturing a negative electrode according to an embodiment of the present invention.

[0101] Figure 43 This is a perspective view showing the negative electrode according to an embodiment of the present invention.

[0102] Figure 44 as well as Figure 45 This is a diagram illustrating the process of manufacturing a positive electrode according to an embodiment of the present invention.

[0103] Figure 46 This is a perspective view showing the positive electrode according to an embodiment of the present invention.

[0104] Figure 47 This is a diagram illustrating an electrode assembly according to a comparative example of the present invention.

[0105] Figure 48 It shows along Figure 47 A cross-sectional view of the section cut by the cutting line B-B'.

[0106] Figure 49 This is a diagram illustrating the process of manufacturing a negative electrode according to a comparative example of the present invention.

[0107] Figure 50 This is a diagram illustrating the process of manufacturing a positive electrode according to a comparative example of the present invention.

[0108] Figure 51 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

[0109] 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.

[0110] 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.

[0111] 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.

[0112] Furthermore, when it is described as a part of a layer, film, region, plate, etc., being located "above" or "on the upper surface" 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. Moreover, when it is described as being located "above" or "on the upper surface" of a reference part, it means being above or below the reference part, and does not necessarily mean that it is located "above" or "on the upper surface" in the opposite direction of gravity.

[0113] 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.

[0114] 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.

[0115] Reference Figures 1 to 3 The cylindrical battery 1 described above according to an embodiment of the present invention includes an electrode assembly 10, a battery casing 20, a cover plate 30, and terminals 40.

[0116] In addition to the aforementioned constituent elements, the cylindrical battery 1 may also include a first current collector 50 and / or an insulator 60 and / or an insulating pad 70 and / or a second current collector 80 and / or a sealing pad 90.

[0117] Reference Figures 1 to 3 The electrode assembly 10 includes a first electrode 11 having a first polarity, a second electrode 12 having a second polarity, a separation membrane 13 sandwiched between the first electrode 11 and the second electrode 12, and an insulating layer 14 covering at least a portion of the first electrode 11.

[0118] The first electrode 11 is either a positive or negative electrode, and the second electrode 12 is equivalent to an electrode with the opposite polarity to the first electrode 11. Both the first electrode 11 and the second electrode 12 can have a sheet-like shape. The electrode assembly 10 can have, for example, a jelly-roll shape. That is, the electrode assembly 10 can be manufactured by rolling the first electrode 11, the separation membrane 13, the second electrode 12, and the separation membrane 13 sequentially at least once, with the roll-up center C as a reference. In this case, the outer peripheral surface of the electrode assembly 10 can additionally have a separation membrane 13 to achieve insulation from the battery casing 20.

[0119] The first electrode 11 and the second electrode 12 may include uncoated portions 11a and 12a at their long side ends, where no active material layer is coated. The first electrode 11 and the second electrode 12 may also include coated portions 11b and 12b, where an active material layer is coated, in areas other than the uncoated portions 11a and 12a.

[0120] Specifically, the first electrode 11 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 area on the first electrode current collector coated with the first electrode active material is called the coated portion (first coated portion) 11b of the first electrode 11. An uncoated portion (first uncoated portion) 11a, uncoated with the first electrode active material, may exist at one end of the first electrode current collector in the width direction (the direction parallel to the Z-axis). At least a portion of the uncoated portion 11a itself serves as an electrode tab. That is, the uncoated portion 11a functions as a first electrode tab on the first electrode 11. The uncoated portion 11a of the first electrode 11 is located at the upper part of the electrode assembly 10 housed within the battery casing 20 in the height direction (the direction parallel to the Z-axis).

[0121] The second electrode 12 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 area on the second electrode current collector coated with the second electrode active material is called the coated portion (second coated portion) 12b of the second electrode 12. An uncoated portion (second uncoated portion) 12a, uncoated with the second electrode active material, may exist at the other end of the second electrode current collector in the width direction (the direction parallel to the Z-axis). At least a portion of the uncoated portion 12a itself serves as an electrode tab. That is, the uncoated portion 12a functions as a second electrode tab on the second electrode 12. The uncoated portion 12a of the second electrode 12 is located at the lower part of the electrode assembly 10 housed within the battery casing 20 in the height direction (the direction parallel to the Z-axis).

[0122] The uncoated portion 11a of the first electrode 11 and the uncoated portion 12a of the second electrode 12 may have shapes that protrude in opposite directions. For example, refer to... Figure 3 as well as Figure 4 The uncoated portion 11a of the first electrode 11 protrudes upward in the height direction (parallel to the Z-axis) of the electrode assembly 10, and the uncoated portion 12a of the second electrode 12 protrudes downward in the height direction (parallel to the Z-axis) of the electrode assembly 10. Thus, the uncoated portion 11a of the first electrode and the uncoated portion 12a of the second electrode can be shaped to extend and protrude in opposite directions along the width direction of the electrode assembly 10, i.e., the height direction (parallel to the Z-axis) of the cylindrical battery 1.

[0123] On the other hand, the aforementioned coated portions 11b and 12b may include landslide portions where the thickness of the active material layer is reduced compared to the central region of the aforementioned coated portions 11b and 12b. For example, refer to... Figure 4 Each of the first electrode 11 and the second electrode 12 may have a region at one end or the other end where the thickness of the active material layer is reduced, i.e., a landslide portion.

[0124] The landslide phenomenon refers to the phenomenon where, due to the expansion of the slurry containing electrode active material, less electrode active material is coated in the slurry coating boundary region compared to the area outside the slurry coating boundary region, resulting in a generally sloping shape of the slurry in the coating boundary region. If the entire electrode is dried, the solvent contained in the slurry evaporates, the slurry volume decreases, and thus a more severe landslide phenomenon occurs near the boundary between the coated and uncoated areas.

[0125] The aforementioned landslide portion can be formed in the boundary region between the coated portions 11b and 12b and the uncoated portions 11a and 12a. For example, the landslide portion can be provided at one end of the first electrode 11 and the other end of the second electrode 12, respectively. That is, the landslide portion provided on the coated portion 11b of the first electrode 11 and the landslide portion provided on the coated portion 12b of the second electrode 12 can be provided in opposite directions. For example, referring to... Figure 4 The sloping portion of the first electrode 11 can be formed in the upper part in the winding axis direction (the direction parallel to the Z-axis), and the sloping portion of the second electrode 12 can be formed in the lower part in the opposite direction, that is, in the winding axis direction (the direction parallel to the Z-axis).

[0126] On the other hand, the length of the coated portion 11b of the first electrode 11 in the winding axis direction (the direction parallel to the Z-axis) can be shorter than the length of the coated portion 12b of the second electrode 12 in the winding axis direction (the direction parallel to the Z-axis). Furthermore, the coated portion 11b of the first electrode 11 can be located inside the coated portion 12b of the second electrode 12 in the winding axis direction (the direction parallel to the Z-axis). For example, see... Figure 4 Compared to the length of the coated portion 11b of the first electrode 11 in the winding axis direction (the direction parallel to the Z-axis), the length of the coated portion 12b of the second electrode 12 in the winding axis direction (the direction parallel to the Z-axis) is longer. Furthermore, referring to… Figure 4 The length of the coated portion 11b of the first electrode 11 in the winding axis direction (parallel to the Z-axis) can be made shorter than the length of the coated portion 12b of the second electrode 12 in the winding axis direction (parallel to the Z-axis), excluding the slip portion. This structure is used to prevent the positive / negative electrode NP ratio from decreasing to below 100%, thereby preventing lithium metal deposition.

[0127] On the other hand, the coated portions 11b and 12b may not protrude further than the separation membrane 13 in the winding axis direction (the direction parallel to the Z-axis). That is, if the coated portions 11b and 12b protrude more than the separation membrane 13 in the winding axis direction (the direction parallel to the Z-axis), the possibility of the first electrode 11 contacting the second electrode 12 may increase. If this happens, an internal short circuit may occur in the contact area, potentially increasing the fire hazard. Therefore, it is important that the coated portions 11b and 12b do not protrude further than the separation membrane 13 in the winding axis direction (the direction parallel to the Z-axis). That is, preferably, the coated portions 11b and 12b are located inside the separation membrane 13.

[0128] To minimize the possibility of contact between the first electrode 11 and the second electrode 12, the first electrode 11 of the present invention may include at least one insulating layer 14 that simultaneously covers at least a portion of the uncoated portion and at least a portion of the coated portion. The insulating layer 14 effectively prevents electrical contact between the first electrode 11 and the second electrode 12. More specifically, it effectively prevents electrical contact between the uncoated portion 11a of the first electrode 11 and the coated portion 12b of the second electrode 12.

[0129] The insulating layer 14 can be disposed on at least one side of the first electrode 11. For example, the insulating layer 14 can be disposed on both sides of the first electrode 11. Although in Figure 4 Not shown in, etc. Figure 4In this configuration, the separation membrane 13 is located not only to the right of the first electrode 11 but also to the left, and another second electrode 12 is located to the left of the separation membrane 13 on the left side. Therefore, in order to prevent electrical contact with the second electrodes 12 located on the left and right sides, preferably, the insulating layer 14 is provided on both sides of the first electrode 11.

[0130] The insulating layer 14 can be disposed in the region of the first electrode 11, possibly covering the entire region facing the coated portion 12b of the second electrode 12. For example, one end of the insulating layer 14 in the winding axis direction (the direction parallel to the Z-axis) can be located at the same height as one end of the separation membrane 13 in the winding axis direction (the direction parallel to the Z-axis) or outside one end. More specifically, to Figure 4 Taking an example, one end of the insulating layer 14 in the winding axis direction (parallel to the Z-axis) can be located at the same height as one end of the separation membrane 13 in the winding axis direction. The separation membrane 13 protrudes between the first electrode 11 and the second electrode 12 in the winding axis direction (parallel to the Z-axis), thus preventing electrical contact between the first electrode 11 and the second electrode 12 to a certain extent. However, since the first electrode 11 or the second electrode 12 may move around inside the cylindrical battery 1, the possibility of the second electrode 12 being located near the end of the separation membrane 13 cannot be ruled out. Therefore, if the second electrode 12 is located at the end of the separation membrane 13 due to movement or other similar activities, or if the second electrode 12 protrudes outside the end of the separation membrane 13, electrical contact between the first electrode 11 and the second electrode 12 cannot be avoided. Alternatively, if the separation membrane 13 is damaged for some reason, electrical contact between the first electrode 11 and the second electrode 12 cannot be avoided. Therefore, in order to prevent electrical contact between the first electrode 11 and the second electrode 12 even if this occurs, preferably, the insulating layer 14 of the first electrode 11 extends at least to the same height as one end of the separation membrane 13 or extends to the outside of one end.

[0131] It should be noted that when the insulating layer 14 covers the entire uncoated portion 11a of the first electrode 11, the first electrode 11 cannot function as an electrode. Therefore, the insulating layer 14 should only cover a portion of the uncoated portion 11a of the first electrode 11. That is, the uncoated portion 11a may have a shape that protrudes further outward from the insulating layer 14.

[0132] The aforementioned insulating layer 14 may be an insulating coating or insulating tape disposed on the boundary region between the uncoated portion 11a and the coated portion 11b. It should be noted that the shape of the insulating layer 14 is not limited to this; any shape in which the insulating layer 14 can adhere to the first electrode 11 while ensuring insulation performance can be applied to the present invention. Furthermore, to ensure insulation performance, the aforementioned insulating layer 14 may contain, for example, an oil-based SBR adhesive and aluminum oxide.

[0133] The insulating layer 14 can simultaneously cover at least a portion of the uncoated portion 11a and at least a portion of the coated portion 11b. For example, the insulating layer 14 can be provided on the boundary region between the coated portion 11b and the uncoated portion 11a. For example, the insulating layer 14 can cover at least a portion of the landslide portion.

[0134] For example, in the entire region of the uncoated portion 11a of the first electrode 11, the insulating layer 14 may extend to a location approximately 0.3 to 5 mm from the boundary between the uncoated portion 11a and the coated portion 11b. More preferably, in the entire region of the uncoated portion 11a of the first electrode 11, the insulating layer 14 may extend to a location approximately 1.5 to 3 mm from the boundary between the uncoated portion 11a and the coated portion 11b.

[0135] Without the insulating layer 14, there is a possibility that an internal short circuit may occur due to contact between the first electrode 11 and the second electrode 12. Therefore, preferably, the insulating layer 14 extends to a position that will not cause electrical contact between the first electrode 11 and the second electrode 12.

[0136] On the other hand, in the entire region of the coated portion 11b of the first electrode 11, the insulating layer 14 may extend to a location approximately 0.1 to 3 mm from the boundary between the uncoated portion 11a and the coated portion 11b. More preferably, in the entire region of the coated portion 11b of the first electrode 11, the insulating layer 14 may extend to a location approximately 0.2 to 0.5 mm from the boundary between the uncoated portion 11a and the coated portion 11b.

[0137] When the insulating layer 14 covers a portion of the coated portion 11b of the first electrode 11, a loss of battery capacity occurs, so it is necessary to minimize the length of the coated portion of the insulating layer 14. However, the coated portion 11b of the first electrode 11 may come into contact with the second electrode 12, so in order to prevent contact, the insulating layer 14 must cover at least a portion of the coated portion 11b of the first electrode 11.

[0138] On the other hand, refer to Figure 4 To illustrate, the separation membrane 13 may have a shape that protrudes further outward than the other end of the first electrode 11 and one end of the second electrode 12. For ease of explanation, refer to... Figure 4 Explanation, in Figure 4 One end of the figure represents the end in the upper direction of the winding axis direction (parallel to the Z-axis) in the figure, and the other end represents the end in the lower direction of the winding axis direction (parallel to the Z-axis) in the figure. Therefore, the separation membrane 13 can have a shape that protrudes further outward than the lower end of the first electrode 11 and further outward than the upper end of the second electrode 12. On the other hand, the separation membrane 13 does not protrude further than the upper end of the first electrode 11. This is so that the upper end of the first electrode 11, i.e., the uncoated portion 11a, can function as the uncoated portion 11a provided in the first electrode 11. Similarly, the separation membrane 13 does not protrude further than the lower end of the second electrode 12. This is so that the lower end of the second electrode 12, i.e., the uncoated portion 12a, can function as the uncoated portion 12a provided in the second electrode 12.

[0139] On the other hand, one end of the second electrode 12, which faces the insulating layer 14 and is separated from the separation membrane 13, may have a shape that does not protrude further outward than one end of the separation membrane 13. For example, see... Figure 4 The first electrode 11 has an insulating layer 14 at one end, and the second electrode 12, which faces the insulating layer 14, is positioned further inward than the separation membrane 13. Therefore, even though one end of the first electrode 11 protrudes outward from the separation membrane 13, the possibility of contact between the first electrode 11 and the second electrode 12 is significantly reduced because one end of the second electrode 12 is located inside the separation membrane 13.

[0140] Reference Figure 1 as well as Figure 2 The battery casing 20 is a generally cylindrical housing with an opening at its lower end, and is made of a conductive material such as metal. For example, the material of the battery casing 20 can be aluminum. The bottom of the battery casing 20 with the opening is referred to as the open end. The side surfaces (outer peripheral surfaces) and the upper surface of the battery casing 20 can be integrally formed. The upper surface of the battery casing 20 (the surface parallel to the XY plane) has a generally flat shape. The upper surface located on the opposite side of the open end is referred to as the closed end. The battery casing 20 houses the electrode assembly 10 through the opening formed at the bottom, and also houses the electrolyte.

[0141] The battery casing 20 is electrically connected to the electrode assembly 10. The battery casing 20 can be electrically connected to either the first electrode 11 or the second electrode 12. For example, the battery casing can be electrically connected to the second electrode 12 of the electrode assembly 10. In this case, the battery casing 20 can have the same polarity as the second electrode 12.

[0142] Reference Figure 2 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 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.

[0143] 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 such a way as to wrap around the outer peripheral surface of the cover plate 30 disposed below the rolled edge portion 21 and a portion below the cover plate 30.

[0144] It should be noted that the present invention does not exclude the possibility that the battery casing 20 does not have such a rolled edge portion 21 and / or a press-fit portion 22. That is, in the present invention, when the battery casing 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 sealing of the battery casing 20 can be achieved, for example, by adding a component that can function as a stopper for the electrode assembly 10. Furthermore, if the cylindrical battery 1 of the present invention includes a cover plate 30, the fixing of the electrode assembly 10 and / or the sealing of the battery casing 20 can be achieved, for example, by adding a structure that can accommodate the cover plate 30 and / or by welding the battery casing 20 and the cover plate 30 together. That is, the cover plate 30 can seal the open end of the battery casing.

[0145] The plugged end of the battery casing 20, i.e., the region constituting the upper surface, 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.

[0146] 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.

[0147] 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 end (bottom) and the thickness of the sidewall portion of the battery casing 20, respectively.

[0148] Reference Figure 2 as well as Figure 15 To ensure rigidity, the cover plate 30 can be made of metal, for example. The cover plate 30 can cover the opening formed at the lower end of the battery casing 20. That is, the cover plate 30 forms the lower part 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. Non-polarization means that the cover plate 30 is electrically insulated from the battery casing 20 and the terminals 40. Therefore, the cover plate 30 may not function as either the positive or negative terminal 40. Therefore, the cover plate 30 may or may not be electrically connected to the electrode assembly 10 and the battery casing 20, and its material is not necessarily a conductive metal.

[0149] When the battery casing 20 of the present invention has a rolled edge portion 21, 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 press-fit portion 22, the cover plate 30 can be fixed by the press-fit portion 22. To ensure the airtightness of the battery casing 20, a sealing gasket 90 can be sandwiched between the cover plate 30 and the press-fit 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 a rolled edge portion 21 and / or a press-fit portion 22. In this case, to ensure the airtightness of the battery casing 20, the sealing gasket 90 can be sandwiched between the fixing structure provided on the open side of the battery casing 20 and the cover plate 30.

[0150] Reference Figure 15 as well as Figure 16The 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 ruptures, 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.

[0151] 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 part of the cylindrical battery 1. Figure 15 As shown, preferably, the lower end of the cover plate 30 is located above the lower end of the battery housing 20. In this case, even if the lower end of the battery housing 20 abuts against the ground or the bottom surface of the housing used to form the module or battery pack, the cover plate 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 differs from the design value, thereby ensuring the smooth rupture of the vent hole 31.

[0152] 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 (towards...). Figure 15 It is advantageous when the edge of a roughly flat area protrudes (in the direction of downwards) as a reference.

[0153] 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.

[0154] Reference Figures 1 to 3 as well as Figures 11 to 13 The terminal 40 is made of a conductive metal and extends through a surface located on the opposite side of the open portion formed on the upper surface of the battery casing 20 (the surface parallel to the XY plane). The terminal 40 is electrically connected, for example, to the uncoated portion 11a of the first electrode 11 of the electrode assembly 10. In this case, the terminal 40 has a first polarity. Therefore, the terminal 40 can function as a first electrode terminal in the cylindrical battery 1 of the present invention. With the terminal 40 having a first polarity, the terminal 40 is electrically insulated from the battery casing 20, which has a second polarity. Electrical insulation between the terminal 40 and the battery casing 20 can be achieved in various ways. For example, insulation can be achieved by sandwiching an insulating gasket 70 (described later) between the terminal 40 and the battery casing 20. Alternatively, insulation can be achieved by forming an insulating coating on a portion of the terminal 40. Alternatively, the terminal 40 can be structurally fixed to prevent contact between the terminal 40 and the battery casing 20. Alternatively, various methods described above can be applied.

[0155] The terminal 40 may include a terminal protrusion 41 and a terminal insertion portion 42. The terminal protrusion 41 may protrude outwards from the battery housing 20. The terminal protrusion 41 may be located approximately at the center of the upper surface of the battery housing 20. The maximum width of the terminal protrusion 41 may be larger than the maximum width of the hole formed in the battery housing 20 due to the terminal 40 penetrating through it. The terminal insertion portion 42 may penetrate approximately at the center of the upper surface of the battery housing 20 to electrically connect with the uncoated portion 11a of the first electrode 11. The terminal insertion portion 42 may be riveted to the inner surface of the battery housing 20. That is, the end of the terminal insertion portion 42 may have a shape that bends towards the inner surface of the battery housing 20, thereby allowing the maximum width of the end of the terminal insertion portion 42 to be larger than the maximum width of the hole formed in the battery housing 20 due to the penetration of the terminal insertion portion 42.

[0156] In one embodiment of the present invention, the terminals 40 exposed on the upper surface and the outer side of the battery housing 20 have opposite polarities but can face the same direction. Furthermore, a step can be formed between the terminals 40 and the upper surface of the battery housing 20. Specifically, when the upper surface of the battery housing 20 has a flat shape or a shape that protrudes upward from its center, the exposed portion 41 of the terminals 40 can protrude further upward than the upper surface of the battery housing 20. Conversely, when the upper surface of the battery housing 20 has a shape that is recessed downward from its center, i.e., toward the electrode assembly 10, the upper surface of the battery housing 20 can protrude further upward than the exposed portion 41 of the battery terminals 40.

[0157] On the other hand, if the upper surface of the battery casing 20 has a recessed shape extending downward from its center toward the electrode assembly 10, the upper surface of the battery casing 20 and the upper surface of the exposed terminal portion 41 of the battery terminal 40 can be formed on the same plane, depending on the depth of the recess and the thickness of the exposed terminal portion 41. In this case, no step needs to be formed between the upper surface of the battery casing 20 and the exposed terminal portion 41.

[0158] On the other hand, when the cylindrical battery 1 of the present invention includes a first current collector 50, the central region of the terminal insertion portion 42 can be coupled to the first current collector 50. The central region of the terminal insertion portion 42 can have, for example, a generally cylindrical shape. The diameter of the bottom surface of the central region of the terminal insertion portion 42 can be set to approximately 6.2 mm.

[0159] The connection between the bottom surface of the central region of the terminal insertion part 42 and the first collector plate 50 can be achieved, for example, by laser welding or ultrasonic welding.

[0160] The aforementioned laser welding can be achieved by irradiating a hole formed in the winding center C of the electrode assembly 10 with a laser to form a laser welding line on one side of the first current collector 50. The laser welding line can be formed as a shape that is approximately concentric with the bottom surface of the central region of the terminal insertion portion 42 within one side of the first current collector 50. The welding line can be formed continuously or partially discontinuously.

[0161] The concentric circle-shaped welding line described above can have a diameter of approximately 60% to 80% of the bottom surface diameter of the central region of the terminal insertion portion 42. For example, when the bottom surface diameter of the central region of the terminal insertion portion 42 is approximately 6.2 mm, the diameter of the circle drawn by the welding line is preferably approximately 4.0 mm or more. If the diameter of the circle drawn by the welding line is too small, the welding bond may be insufficient. Conversely, if the diameter of the circle drawn by the welding line is too large, there is a possibility of increased concern about damage to the electrode assembly 10 due to heat and / or welding spatter. The ultrasonic welding can be performed by inserting a welding rod for ultrasonic welding through a hole formed in the coiling center C of the electrode assembly 10. The weld portion formed by the ultrasonic welding is formed within the contact interface between the bottom surface of the central region of the terminal insertion portion 42 and the first current collector 50. The weld portion formed by the ultrasonic welding can be formed within a concentric circle having a diameter of approximately 30% to 80% of the bottom surface diameter of the central region of the terminal insertion portion 42. For example, when the diameter of the bottom surface of the central region of the terminal insertion portion 42 is approximately 6.2 mm, the diameter of the circle drawn by the weld portion formed by ultrasonic welding is preferably approximately 2.0 mm or more. If the diameter of the circle drawn by the weld portion formed by ultrasonic welding is too small, the weld bonding strength may be insufficient. Conversely, if the diameter of the circle drawn by the weld portion formed by ultrasonic welding is too large, there is a possibility that the electrode assembly 10 may be damaged by heat and / or vibration.

[0162] The aforementioned insulating pad 70 is sandwiched between the battery casing 20 and the terminal 40 to prevent the battery casing 20 and the terminal 40, which have opposite polarities, from contacting each other. Thus, the upper surface of the battery casing 20, which has a generally flat shape, functions as the second electrode terminal of the cylindrical battery 1.

[0163] Reference Figure 11 as well as Figure 12 The insulating gasket 70 may include a gasket protrusion 71 and a gasket insertion portion 72. The gasket protrusion 71 is sandwiched between the terminal protrusion 41 of the terminal 40 and the battery housing 20. The gasket insertion portion 72 is sandwiched between the terminal insertion portion 42 of the terminal 40 and the battery housing 20. The gasket insertion portion 72 deforms together with the terminal insertion portion 42 during reveting, thereby allowing it to fit tightly against the inner surface of the battery housing 20. The insulating gasket 70 may, for example, be made of an insulating resin material.

[0164] Reference Figure 12The exposed portion 71 of the insulating gasket 70 may have a shape that extends in a manner that covers the outer peripheral surface of the exposed portion 41 of the terminal 40. When the insulating gasket 70 covers the outer peripheral surface of the terminal 40, short circuits can be prevented during the process of attaching electrical connection components such as busbars to the upper surface of the battery housing 20 and / or the terminal 40. Although not shown in the figures, the exposed portion 71 of the insulating gasket 70 may also have a shape that extends in a manner that covers a portion of the upper surface in addition to the outer peripheral surface of the exposed portion 41 of the terminal.

[0165] When the insulating gasket 70 is made of resin, it can be bonded to the battery housing 20 and the terminal 40 by heat welding. In this case, the airtightness of the interface between the insulating gasket 70 and the terminal 40, as well as the interface between the insulating gasket 70 and the battery housing 20, can be enhanced. On the other hand, when the exposed portion 71 of the insulating gasket 70 has a shape that extends to the upper surface of the exposed portion 41 of the terminal, the terminal 40 can be bonded to the insulating gasket 70 by insert molding.

[0166] According to one embodiment of the present invention, the insulating gasket 70, the insulator 60, and the sealing gasket 90 can be formed of the same material. It should be noted that this is not mandatory. The insulating gasket 70 and the insulator 60 can have the same thickness. It should be noted that this is not mandatory. If their thicknesses are different, the thickness of the insulator 60 can be thinner than the thickness of the insulating gasket 70, and vice versa.

[0167] In the upper surface of the battery casing 20, i.e., the outer surface of the plug 20a, the remaining area excluding the area occupied by the terminal 40 and the insulating pad 70 is entirely equivalent to a second electrode terminal having the opposite polarity to the terminal 40. In contrast, in this invention, when the insulating pad 70 is omitted and an insulating coating is provided on a portion of the terminal 40, the remaining area on the upper surface of the battery casing 20, excluding the area occupied by the terminal 40 with the insulating coating, can function as a second electrode terminal.

[0168] The cylindrical sidewall of the battery housing 20 can be formed as a single piece with the plug 20a, so that there is no discontinuity between it and the second electrode terminal. The connection from the sidewall of the battery housing 20 to the plug 20a can be a gentle curve. It should be noted that the present invention is not limited thereto, and the connection portion may include at least one corner with a predetermined angle.

[0169] Reference Figures 11 to 14The first current collector 50 can be attached to the upper part of the electrode assembly 10. The first current collector 50 is made of a conductive metal material and can be electrically connected to the uncoated portion 11a of the first electrode. Although not shown in the figures, the first current collector 50 may have a plurality of radially formed protrusions and recesses on its underside. With these protrusions and recesses formed, the first current collector 50 can be pressed to press the protrusions and recesses into the uncoated portion 11a of the first electrode.

[0170] Reference Figure 3 as well as Figure 13 The first current collector 50 can be bonded to the uncoated portion 11a end of the first electrode 11. The bonding between the uncoated portion 11a of the first electrode 11 and the first current collector 50 can be achieved, for example, by laser welding. Laser welding can be performed by melting a portion of the base material of the first current collector 50, or with solder sandwiched between the first current collector 50 and the uncoated portion 11a of the first electrode 11. In this case, preferably, the solder has a lower melting point than the first current collector 50 and the uncoated portion 11a of the first electrode.

[0171] Reference Figure 3 as well as Figure 14 The first current collector 50 can be bonded to a bonding surface formed by bending the end of the uncoated portion 11a of the first electrode in a direction parallel to the first current collector 50. The bending direction of the uncoated portion 11a of the first electrode can be, for example, towards the winding center C of the electrode assembly 10. With this bending shape, the space occupied by the uncoated portion 11a of the first electrode is reduced, thereby increasing energy density. Furthermore, due to the increased bonding area between the uncoated portion 11a of the first electrode and the first current collector 50, the bonding force is improved and the resistance is reduced.

[0172] Reference Figure 2 , Figure 3 as well as Figure 11The insulator 60 can be disposed between the upper end of the electrode assembly 10 and the inner side of the battery housing 20, or combined between the first current collector 50 on the upper part of the electrode assembly 10 and the inner side of the battery housing 20. The insulator 60 prevents contact between the uncoated portion 11a of the first electrode 11 and the battery housing 20, and / or contact between the first current collector 50 and the battery housing 20. Alternatively, the insulator 60 can be sandwiched between the upper end of the outer peripheral surface of the electrode assembly 10 and the inner side of the battery housing 20. The first current collector 50 can be a plate extending completely across the upper end of the outer peripheral surface of the electrode assembly 10. It should be noted that the present invention is not limited to this; the first current collector 50 can also be formed by partially extending across the upper end of the outer peripheral surface of the electrode assembly 10.

[0173] In the case where the cylindrical battery 1 according to an embodiment of the present invention has an insulator 60, the terminal insertion portion 42 of the terminal 40 can be connected to the first current collector 50 or the uncoated portion 11a of the first electrode 11 after passing through the insulator 60.

[0174] The insulator 60 may have an opening adjacent to the winding center C. This opening allows the terminal insertion portion 42 of the terminal 40 to directly contact the first current collector 50.

[0175] In one embodiment of the present invention, the planar shape of the terminal insertion portion 42 may be circular, but is not limited thereto. Optionally, the terminal insertion portion 42 may be polygonal, star-shaped, or have a shape with a centrally extending post, etc.

[0176] Reference Figure 2 , Figure 3 as well as Figure 15 The second current collector 80 is attached to the lower part of the electrode assembly 10. The second current collector 80 is made of a conductive metal and can be connected to the uncoated portion 12a of the second electrode 12. Furthermore, the second current collector 80 can be electrically connected to the battery casing 20. Figure 15 As shown, the second current collector 80 can be fixed between the inner side of the battery housing 20 and the sealing gasket 90. Alternatively, the second current collector 80 can also be welded to the inner wall of the battery housing 20.

[0177] Although not shown in the accompanying drawings, the second current collector 80 may have a plurality of protrusions and recesses formed radially on one side thereon. When the protrusions and recesses are formed, the second current collector 80 can be pressed to press the protrusions and recesses into the uncoated portion 12a of the second electrode 12.

[0178] Reference Figure 3 as well as Figure 13The second current collector 80 can be bonded to the end of the uncoated portion 12a of the second electrode 12. The bonding between the uncoated portion 12a of the second electrode 12 and the second current collector 80 can be achieved, for example, by laser welding. Laser welding can be performed by melting a portion of the base material of the second current collector 80, or with solder sandwiched between the second current collector 80 and the uncoated portion 12a of the second electrode 12. In this case, preferably, the solder has a lower melting point than the second current collector 80 and the uncoated portion 12a of the second electrode 12.

[0179] Reference Figure 3 as well as Figure 14 The second current collector 80 can be bonded to a bonding surface formed by bending the uncoated portion 12a of the second electrode 12 in a direction parallel to the second current collector 80. The bending direction of the uncoated portion 12a of the second electrode 12 can be, for example, towards the winding center C of the electrode assembly 10. With this bent shape, the space occupied by the uncoated portion 12a of the second electrode 12 is reduced, thereby increasing the energy density. Furthermore, according to this structure, the bonding area between the uncoated portion 12a of the second electrode 12 and the second current collector 80 is increased, thereby improving the bonding strength and reducing resistance.

[0180] Reference Figure 3 , Figure 15 as well as Figure 17 The aforementioned second current collector 80 may include a plurality of sub-plates 81 extending generally radially from the center and spaced apart from each other. In this case, the plurality of sub-plates 81 may be coupled to the uncoated portion 12a of the second electrode 12 and the battery casing 20, respectively. On the other hand, the ends of the aforementioned second current collector 80, i.e., the ends of the sub-plates 81, may be electrically connected to the inner surface of the sidewall of the battery casing 20, such as... Figure 15 As shown.

[0181] In the case where the second current collector 80 includes a plurality of sub-plates 81 spaced apart from each other, the second current collector 80 covers a portion of the area below the electrode assembly 10. Therefore, it is sufficiently ensured that the gas generated by the electrode assembly 10 can be smoothly discharged downwards into the cylindrical battery 1 through the space where the cover plate 30 can move. On the other hand, as described above, the structure of the second current collector 80 having a plurality of sub-plates 81 can also be applied to the first current collector 50 described above.

[0182] Reference Figure 15The aforementioned sealing gasket 90 may have a generally annular shape that surrounds the cover plate 30. The sealing gasket 90 may simultaneously cover the lower surface, upper surface, and sides of the cover plate 30. The radial length of the portion of the sealing gasket 90 covering the upper surface of the cover plate 30 may be shorter or the same as the radial length of the portion of the sealing gasket 90 covering the lower surface of the cover plate 30. If the radial length of the portion of the sealing gasket 90 covering the upper surface of the cover plate 30 is too long, the sealing gasket 90 may press against the second current collector 80 during the shaping process of compressing the battery casing 20, potentially damaging the second current collector 80 or the battery casing 20. Therefore, it is necessary to maintain the radial length of the portion of the sealing gasket 90 covering the upper surface of the cover plate 30 at a relatively small level.

[0183] Reference Figure 1 as well as Figure 2 According to an embodiment of the present invention, a cylindrical battery 1 has a battery terminal 40 with a first polarity and a blocking portion 20a of a battery casing 20 with a second polarity, electrically insulated from the battery terminal 40, on one side of its length direction (parallel to the Z-axis). That is, the battery terminal 40 functions as a first electrode terminal, and the blocking portion 20a of the battery casing 20 functions as a second electrode terminal. Thus, in the cylindrical battery 1 according to an embodiment of the present invention, a pair of electrode terminals with opposite polarities are located in the same direction, so when multiple cylindrical batteries 1 are electrically connected, electrical connection components such as busbars can be arranged only on one side of the cylindrical battery 1. This simplifies the battery pack structure and increases energy density.

[0184] Furthermore, the cylindrical battery 1 described above has a structure that allows one side of the battery casing 20, which has a generally flat shape, namely the outer surface of the plug portion 20a, to be used as the second electrode terminal, thereby ensuring a sufficient contact area when electrical connection components such as busbars are joined to the second electrode terminal. As a result, the cylindrical battery 1 can ensure sufficient contact strength between the electrical connection components and the second electrode terminal, and can reduce the resistance at the contact point to an ideal level.

[0185] Reference Figure 1 In this invention, the outer surfaces of the battery terminals 40 of the cylindrical battery 1 and the plug portion 20a of the battery casing 20 are respectively connected to a busbar B. In each of the battery terminals 40 and the plug portion 20a, in order to sufficiently ensure the area for connecting the busbar B, the width D1 of the upper surface of the exposed area 41 of the battery terminal 40 that extends outward from the battery casing 20 can be set to approximately 10% to 60% of the width D2 of the upper surface of the plug portion 20a.

[0186] On the other hand, according to Figure 5 The electrode assembly 10 of the embodiment has the above-described... Figure 3 The electrode assembly 10 of the embodiment has a structure in which the uncoated portions 11a and 12a are bent.

[0187] Reference Figure 3 as well as Figure 5 According to another embodiment of the present invention, the electrode assembly 10 may have a structure in which at least a portion of the uncoated portions 11a and 12a bends toward the core. For example, at least a portion of the uncoated portions 11a and 12a may be divided along the circumferential direction of the electrode assembly 10, thereby forming a plurality of slices F. The plurality of slices F may have a structure that bends toward the core and overlaps multiple layers. For example, the plurality of slices may be formed by laser cutting. The slices may be formed by known metal foil cutting processes such as ultrasonic cutting or punching.

[0188] To prevent damage to the active material layer and / or insulating layer 14 during bending of the uncoated portions 11a and 12a, a predetermined gap is preferably maintained between the lower end of the cutting line and the active material layer between the slicing sections. This is because stress concentrates near the lower end of the cutting line when bending the uncoated portions 11a and 12a. Preferably, the gap is 0.2 to 4 mm. If the gap is adjusted within the corresponding range, damage to the active material layer and / or insulating layer 14 near the lower end of the cutting line due to stress generated during bending of the uncoated portions 11a and 12a can be prevented. Furthermore, the gap can prevent damage to the active material layer and / or insulating layer 14 caused by tolerances during slicing or cutting.

[0189] The bending direction of the uncoated portions 11a and 12a can be, for example, towards the winding center C of the electrode assembly 10. When the uncoated portions 11a and 12a have such a bent shape, the space occupied by the uncoated portions 11a and 12a is reduced, thereby increasing the energy density. Furthermore, the uncoated portions 11a and 12a are connected to the current collectors 50 and 80 (see reference 1). Figure 14 The bonding area between the two sides can improve the bonding strength and reduce the resistance.

[0190] Reference Figure 5 as well as Figure 6 The uncoated portion 11a of the first electrode 11 can be bent in one direction. For example, in Figure 6In this configuration, the +X direction can be towards the core side. Thus, if the uncoated portion 11a bends towards the core side, the uncoated portion 11a of the first electrode 11 may extend beyond the separation membrane 13 and approach the second electrode 12. Therefore, preferably, on the side of the uncoated portion 11a of the first electrode 11 facing the core side, the insulating layer 14 extends to the end of the uncoated portion 11a. With this structure, even if the uncoated portion 11a bends towards the core side and extends beyond the separation membrane 13 to approach the second electrode 12, electrical contact between the first electrode 11 and the second electrode 12 can be prevented. Therefore, internal short circuits in the cylindrical battery 1 can be effectively prevented.

[0191] In the case where the uncoated portion 11a described above has multiple slices F, the multiple slices F can be bent along the radial direction and overlap each other. In this case, the insulating layer 14 can be omitted in the area where the multiple slices F overlap (the area indicated by the dashed circle) so that electrical connection can be achieved between the slices F. The structure of omitting the insulating layer in the area where the slices F overlap can also be applied to the remaining embodiments described below.

[0192] On the other hand, refer to Figure 6 In the two surfaces of the uncoated portion 11a, the surface opposite to the one facing the core may have an insulating layer 14 only in a localized area. That is, in the remaining area of ​​the surface opposite to the core, the uncoated portion 11a may be exposed to the outside. Therefore, the uncoated portion 11a exposed on the surface opposite to the core can make electrical contact with the uncoated portion 11a of the adjacent first electrode 11 or the first current collector 50. In other words, the area of ​​the uncoated portion 11a not covered by the insulating layer 14 in its entirety can be electrically bonded to the first current collector 50. Furthermore, the area of ​​the uncoated portion 11a not covered by the insulating layer 14 in its entirety can be bonded to the first current collector 50 by welding. This welding can be, for example, laser welding. The laser welding described above can be achieved by melting a portion of the base material of the first current collector 50, or it can be achieved with solder for welding sandwiched between the first current collector 50 and the uncoated portion 11a. In this case, preferably, the solder has a lower melting point than the first current collector 50 and the uncoated portion 11a. On the other hand, in addition to laser welding, resistance welding, ultrasonic welding, etc., can also be used, but the welding method is not limited to these.

[0193] Reference Figure 7The insulating layer 14 may have a shape that covers the end of the uncoated portion 11a. Specifically, the insulating layer 14 may have a structure that covers the end face of the uncoated portion 11a. For example, if the length of the bent uncoated portion 11a is long, the possibility of contact with the second electrode 12 increases. Moreover, there is a possibility that the bent uncoated portion 11a may be further bent due to movement or external pressure. In this case, the possibility of contact between the end face of the uncoated portion 11a and the second electrode 12 increases. However, according to the structure of the present invention as described above, even if the uncoated portion 11a is further bent or deformed, since the insulating layer 14 covers the end face of the uncoated portion 11a, electrical contact between the first electrode 11 and the second electrode 12 can be prevented.

[0194] Reference Figure 8 On the side opposite to the side facing the core in the two faces of the uncoated portion 11a, the insulating layer 14 can extend to the bend in the uncoated portion 11a. Although not shown in the drawings, Figure 8 Another separation membrane 13 and another second electrode 12 are provided on the left side of the first electrode 11. That is, the first electrode 11 has the possibility of electrical contact with the second electrode 12 located on the right side of the first electrode 11, and also has the possibility of electrical contact with the second electrode 12 located on the left side of the first electrode 11. However, according to the structure of the present invention as described above, electrical contact with the second electrodes 12 located on both sides of the first electrode 11 can be reliably prevented.

[0195] Figure 9 This is a comparative example of the present invention, showing a cross-sectional view of the electrode assembly 10 without the insulating layer 14. (Refer to...) Figure 9 No additional insulating layer 14 is provided at the boundary region between the uncoated portion 11a and the coated portion 11b of the first electrode 11. With this structure, when movement occurs due to the detour of the first electrode 11 or the second electrode 12, the second electrode 12 may be located at the end of the separation membrane 13 or protrude further outward than the end of the separation membrane 13, potentially leading to electrical contact between the first electrode 11 and the second electrode 12. Alternatively, if the separation membrane 13 is damaged for some reason, electrical contact between the first electrode 11 and the second electrode 12 may occur. In this case, when having such... Figure 9 In the electrode assembly 10 of the structure, it is impossible to avoid internal short circuits caused by electrical contact between the first electrode 11 and the second electrode 12. Therefore, the risk of fire is increased.

[0196] Figure 10 This is a graph illustrating the power distribution under multiple short-circuit conditions within the cylindrical battery 1. (Refer to...) Figure 10The possible short circuit scenarios that may occur inside the cylindrical battery 1 can be conceived as the following four types.

[0197] (1) The coated part at the positive electrode is in electrical contact with the coated part at the negative electrode. (2) The coated part at the positive electrode is in electrical contact with the uncoated part at the negative electrode. (3) The coated part at the negative electrode is in electrical contact with the uncoated part at the positive electrode. (4) The uncoated part at the positive electrode is in electrical contact with the uncoated part at the negative electrode.

[0198] Reference Figure 10 It can be seen that the highest power is exhibited in case (3), where the coated part at the negative terminal is in electrical contact with the uncoated part at the positive terminal. That is, case (3) exhibits the highest probability of ignition in case (3), where the coated part at the negative terminal is in electrical contact with the uncoated part at the positive terminal. This is because the resistance is very low, resulting in a large short-circuit current, which in turn causes the temperature to rise rapidly.

[0199] Therefore, considering the structure of the electrode assembly 10 of the present invention, it is necessary to explore a structure that can prevent electrical contact between the coated portion provided on the negative electrode and the uncoated portion provided on the positive electrode.

[0200] Through dedicated research into this technical problem, the inventors of this invention have concluded that as long as an insulating layer 14 is provided in at least a portion of the uncoated portion of the positive electrode, electrical contact with the coated portion of the negative electrode can be effectively prevented, thus completing this invention. That is, the first electrode 11 described above can be a positive electrode. It should be noted that the first electrode 11 is not necessarily limited to a positive electrode; it can also be a negative electrode. Furthermore, in this invention, it is not excluded that the second electrode 12 may have an insulating layer 14. That is, the insulating layer 14 can be provided in both the positive and negative electrodes. In this case, all possible short-circuit situations can be prevented.

[0201] Preferably, the cylindrical battery 1 can be, for example, a cylindrical battery 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 is approximately greater than 0.4.

[0202] The shape factor indicates the diameter and height of the cylindrical battery. According to an embodiment of the present invention, the cylindrical battery may be, for example, a 46110 battery, a 48750 battery, a 48110 battery, a 48800 battery, or a 46800 battery. In the shape factor values, the first two digits represent the diameter of the battery, the next two digits represent the height of the battery, and the final digit 0 indicates that the battery has a circular cross-section.

[0203] According to one embodiment of the present invention, the battery is a generally cylindrical battery, which may be a cylindrical battery with a diameter of about 46 mm, a height of about 110 mm, and a shape factor ratio of about 0.418.

[0204] According to another embodiment, the battery is a generally cylindrical battery, which may be a cylindrical battery with a diameter of about 48 mm, a height of about 75 mm, and a shape factor ratio of about 0.640.

[0205] According to another embodiment, the battery is a generally cylindrical battery, which may be a cylindrical battery with a diameter of about 48 mm, a height of about 110 mm, and a shape factor ratio of about 0.418.

[0206] According to another embodiment, the battery is a generally cylindrical battery, which may be a cylindrical battery with a diameter of about 48 mm, a height of about 80 mm, and a shape factor ratio of about 0.600.

[0207] According to another embodiment, the battery is a generally cylindrical battery, which may be a cylindrical battery with a diameter of about 46 mm, a height of about 80 mm, and a shape factor ratio of about 0.575.

[0208] Previously, batteries with a form factor ratio of approximately 0.4 or less were used. That is, batteries such as the 18650 and 21700 were previously used. An 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. A 21700 battery has a diameter of approximately 21 mm and a height of approximately 70 mm, with a form factor ratio of 0.300.

[0209] Reference Figure 18 According to an embodiment of the present invention, the battery pack 3 includes a 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.

[0210] Reference Figure 19 According to an embodiment of the present invention, the vehicle 5 may be, for example, an electric vehicle, a hybrid vehicle, or a plug-in hybrid vehicle, and includes a battery pack 3 according to an embodiment of the present invention. The vehicle 5 includes both four-wheeled and two-wheeled vehicles. The vehicle 5 operates by receiving power from the battery pack 3 according to an embodiment of the present invention.

[0211] The following describes an embodiment of the positive electrode active material used in the cylindrical battery according to the present invention.

[0212] 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.

[0213] "Secondary particles" are particles formed by the aggregation of multiple primary particles. In this invention, to distinguish them from existing secondary particles formed by the aggregation of tens to hundreds of primary particles, secondary particles formed by the aggregation of fewer than ten primary particles are referred to as similar single particles.

[0214] 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).

[0215] 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.

[0216] 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.

[0217] 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.

[0218] 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.

[0219] 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.

[0220] 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.

[0221] 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.

[0222] 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.

[0223] 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.

[0224] 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 leads to an increase in the mass of active material, significantly increasing gas production and further increasing the risk of fire and / or explosion.

[0225] In contrast, compared to existing secondary particle-shaped positive electrode active materials composed of tens to hundreds of primary particles, single-particle active materials composed of a single primary particle or fewer than ten primary particles exhibit higher particle strength, thus almost eliminating particle cracking during calendering. Furthermore, the smaller number of primary particles constituting the single-particle active material particles results in less volume expansion and contraction during charging and discharging, significantly reducing internal cracking.

[0226] 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.

[0227] On the other hand, based on the total weight of the positive electrode active material contained in the positive electrode, the aforementioned single particles and / or similar single particles contain 95 wt% to 100 wt%, preferably 98 wt% to 100 wt%, more preferably 99 wt% to 100 wt%, and even more preferably 100 wt%.

[0228] 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.

[0229] 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 nanometer 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.

[0230] 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.

[0231] 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.

[0232] 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.

[0233] 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.

[0234] 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... max When 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 Do 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.

[0235] 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.

[0236] Mathematical formula (1): Particle size distribution (PSD) = (D max –D min ) / D 50

[0237] 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.

[0238] 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.

[0239] 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.

[0240] On the other hand, the aforementioned positive electrode active material may comprise a lithium nickel oxide, specifically, based on the total molar percentage of the transition metal, it may comprise a lithium nickel oxide containing 80 mol% or more of Ni. Preferably, the aforementioned lithium nickel oxide may contain 80 mol% or more but less than 100 mol%, 82 mol% or more but less than 100 mol%, or 83 mol% or more but less than 100 mol% of Ni. Using a lithium nickel oxide with a high Ni content as described above enables high capacity.

[0241] More specifically, the above-mentioned positive electrode active material may include lithium nickel oxide represented by the following [Chemical Formula 1].

[0242]

Chemical Formula 1

[0243] Li a Ni b Co c M 1 d M 2 e O2

[0244] In the above chemical formula 1, M 1 It can be Mn, Al, or a combination thereof, preferably Mn or Mn and Al.

[0245] 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.

[0246] The above-mentioned a represents the molar ratio of lithium in the lithium nickel-based oxide, and it can be 0.8 ≤ a ≤ 1.2, 0.85 ≤ a ≤ 1.15, or 0.9 ≤ a ≤ 1.2. When the molar ratio of lithium satisfies the above range, the crystal structure of the lithium nickel-based oxide can be stably formed.

[0247] The above-mentioned b represents the molar ratio of nickel in the overall metal other than lithium in the lithium nickel-based oxide, and it can be 0.8 ≤ b < 1, 0.8 ≤ 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 satisfies the above range, a high energy density is presented, and high capacity can be achieved.

[0248] The above-mentioned c represents the molar ratio of cobalt in the overall metal other than lithium in the lithium nickel-based oxide, and it can be 0 < c < 0.2, 0 < c < 0.18, 0.01 ≤ c ≤ 0.17, 0.01 ≤ c ≤ 0.15, 0.01 ≤ c ≤ 0.12, or 0.01 ≤ c ≤ 0.10. When the molar ratio of cobalt satisfies the above range, good resistance characteristics and output characteristics can be achieved.

[0249] The above-mentioned d represents the molar ratio of element M in the overall metal other than lithium in the lithium nickel-based oxide 1 and it can be 0 < d < 0.2, 0 < d < 0.18, 0.01 ≤ d ≤ 0.17, 0.01 ≤ d ≤ 0.15, 0.01 ≤ d ≤ 0.12, or 0.01 ≤ d ≤ 0.10. When the molar ratio of element M 1 satisfies the above range, good structural stability of the positive electrode active material is presented.

[0250] The above-mentioned e represents the molar ratio of element M in the overall metal other than lithium in the lithium nickel-based oxide 2 and it can be 0 ≤ e ≤ 0.1 or 0 ≤ e ≤ 0.05.

[0251] 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-mentioned lithium nickel-based oxide particles. Preferably, the above-mentioned coating elements may be Al, B, Co, or a combination thereof.

[0252] 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.

[0253] The positive electrode active material layer may contain 80 wt% to 99 wt% of the above-mentioned positive electrode active material relative to the total weight of the positive electrode active material layer, preferably 85 wt% to 99 wt%, and more preferably 90 wt% to 99 wt%.

[0254] 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 with a surface treatment of 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 3 μm to 500 μm, 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.

[0255] On the other hand, in one embodiment of the present invention, all or part of the aforementioned plurality of single-particle active material particles may have a core-shell structure in which the particle surface is coated with a conductive coating. The conductive coating may cover at least a portion or all of the particles. The conductive coating includes conductive nanomaterials.

[0256] 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.

[0257] 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.

[0258] 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.

[0259] The aforementioned conductive nanomaterials can have various shapes, such as spherical, scaly, or fibrous.

[0260] 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.

[0261] 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.

[0262] In one embodiment of the present invention, the above-mentioned flake graphite may be included in 0.1 wt% to 5 wt% of the above-mentioned positive electrode active material layer, and preferably in 0.1 wt% to 3 wt%.

[0263] 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.

[0264] 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 aforementioned flake graphite can be measured by laser diffraction (ISO 13320).

[0265] 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.

[0266] 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 .

[0267] 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.

[0268] 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.

[0269] When achieving a high-load electrode with a relatively high loading of the positive electrode active material layer, as in this invention, using a single-particle or similar single-particle shape of the positive electrode active material significantly reduces particle cracking of the active material during calendering compared to existing secondary particle-shaped positive electrode active materials, thus reducing damage to the positive electrode current collector (Al Foil). Therefore, calendering can be performed with a relatively high imprint line pressure, thereby reducing the porosity of the positive electrode active material layer to the range described above and improving the energy density.

[0270] 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.

[0271] 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 2A 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.

[0272] 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%.

[0273] In one specific embodiment of the present invention, the conductive material may include carbon nanotubes.

[0274] In one embodiment of the present invention, the aforementioned positive electrode active material, as a conductive material, may include multi-walled carbon nanotubes with a high specific surface area and a small number of walls. The multi-walled carbon nanotubes may comprise 50 wt% or more, 70 wt% or more, 90 wt% or more, or 99 wt% or more of the conductive material in a 100 wt% composition. In a specific embodiment of the present invention, the conductive material is composed solely of the aforementioned multi-walled carbon nanotubes.

[0275] In this invention, the BET specific surface area of ​​the aforementioned multi-walled carbon nanotubes is 300 m². 2 / g to 500m 2 / g. To distinguish it from existing technologies, it is called "novel CNT".

[0276] Previously used carbon nanotubes (current CNTs) typically have a BET specific surface area of ​​less than 300 m². 2 / g. The novel CNT used in this invention ( Figure 20 ) and existing CNTs Figure 21 The scanning electron microscope images and the comparison results of physical properties () Figure 22 )as follows.

[0277] 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.

[0278] When using secondary particle-shaped positive electrode active materials, sufficient conductivity can be achieved even when using existing CNTs at a level of 0.4wt% to 0.6wt%. However, the resistivity of single-particle or similar single-particle positive electrode active materials is higher than that of existing secondary particle-shaped positive electrode active materials, and the contact area with the conductive material is smaller, resulting in a decrease in conductivity. Therefore, in order to use CNTs with a BET specific surface area of ​​less than 300m², [further considerations are needed]. 2 To achieve sufficient conductivity with existing CNTs, the conductive material content needs to be above 0.9 wt%.

[0279] Figures 23 to 26 This 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.

[0280] 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.

[0281] 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.

[0282] The inventors of this invention, through repeated research to solve this problem, discovered that by using a positive electrode active material that is a single-particle active material particle and a conductive material with a BET specific surface area of ​​300 m², a solution can be achieved. 2 / g to 500m 2 With a carbon nanotube content of / g, sufficient conductivity can be ensured with only a relatively small amount of carbon nanotubes. Thus, even if the solid powder content of the cathode slurry is formed at a high level of 70wt% to 80wt%, the slurry viscosity can be maintained at a low level.

[0283] 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.

[0284] 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.

[0285] Furthermore, the diameter of the aforementioned carbon nanotubes can be 1 nm to 8 nm, preferably 3 nm to 8 nm, and more preferably 3 nm to 6 nm.

[0286] 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.

[0287] Figure 27 The table shown illustrates the applicable BET specific surface area of ​​300m². 2 / g to 500m 2 / g of carbon nanotubes (novel CNTs) and their applicable BET of 200m 2 / g or more and less than 300m 2 The table above compares the solid content and viscosity of the cathode slurry with a carbon nanotube (CNT) content of / g, as well as the resistivity of the MP coating and MP interface layer. The table shows that, when using the novel CNT, compared to existing CNTs, it exhibits lower viscosity and better conductivity even with a higher solid content in the cathode slurry.

[0288] 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 in mixtures of two or more. 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%.

[0289] Another aspect of the present invention relates to an electrode assembly including the aforementioned positive electrode and a battery including the same. The electrode assembly includes a negative electrode and a positive electrode, the positive electrode having the structural features described above.

[0290] The aforementioned electrode assembly can be stacked, for example, with a separation membrane sandwiched between the negative and positive electrodes to form a stacked or stacked / folded structure, or rolled up to form a gel roll structure. Furthermore, when forming a gel roll structure, a separation membrane is added to the outside to prevent the negative and positive electrodes from contacting each other.

[0291] The aforementioned negative electrode includes a negative current collector and a negative active material layer formed on at least one side of the negative current collector. The aforementioned negative electrode may be configured such that a negative active material layer is formed on one or both sides of the elongated negative current collector, and the negative active material layer may include a negative active material, a conductive material, and an adhesive.

[0292] Specifically, the aforementioned negative electrode is manufactured by coating one or both sides of a strip-shaped negative electrode current collector with a negative electrode slurry prepared by dispersing the negative 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 negative electrode slurry is removed through a drying process, followed by calendering. By leaving a portion of the negative electrode current collector uncoated during the coating process, such as one end of the negative electrode current collector, a negative electrode including an uncoated portion can be manufactured.

[0293] The above-mentioned negative electrode active material can use a compound capable of reversible insertion and extraction of lithium. Specific examples of the negative electrode active material include carbonaceous materials such as artificial graphite, natural graphite, graphitized carbon fiber, and amorphous carbon; silicon-based materials such as Si, Si-Me alloy (where Me is one or more selected from the group consisting of Al, Sn, Mg, Cu, Fe, Pb, Zn, Mn, Cr, Ti, and Ni), SiO y (where 0 < y < 2), Si-C composite, etc.; lithium metal thin film; metal materials such as Sn and Al that can be alloyed with lithium; etc., and any one or a mixture of two or more thereof can be used.

[0294] In the present invention, the above-mentioned negative electrode may include a silicon-based negative electrode active material. The above-mentioned 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 including the silicon-based negative electrode active material, the capacity characteristics can be improved.

[0295] The above-mentioned silicon-based negative electrode active material may be a material coated with M b metal. At this time, the above-mentioned 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-mentioned 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 coated element active material decreases a little, but it has a higher efficiency, so high energy density can be achieved.

[0296] Figure 51 It 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.

[0297] In Figure 51 , Low efficiency SiO means uncoated SiO, and Ultra-High efficiency SiO means SiO coated with Mg / Li. By Figure 51It can be seen that as the content of silicon-based anode active material in the overall anode active material increases, the energy density also increases. Furthermore, it can be seen that as the proportion of coated silicon-based anode active material in the silicon-based anode active material increases, the improvement in energy density is even more significant.

[0298] The aforementioned silicon-based anode active material may also include a carbon coating on the particle surface. In this case, based on the total weight of the silicon-based anode active material, the amount of carbon coating may be less than 20 wt%, preferably 1 to 20 wt%. The aforementioned carbon coating may be formed by dry coating, wet coating, chemical vapor deposition (CVD), physical vapor deposition (PVD), atomic layer deposition (ALD), or other methods.

[0299] In one embodiment of the present invention, the silicon-based negative electrode active material can have a capacity of 1000 to 4000 mAh / g and an initial efficiency of about 60 to 95%.

[0300] In yet another embodiment of the present invention, the D of the above-mentioned silicon-based negative electrode active material 50 It can be 3um to 8um, D min ~D max It can be in the range of 0.5um to 30um.

[0301] 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.

[0302] 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.

[0303] 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%.

[0304] 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.

[0305] The aforementioned negative current collector can be any negative 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 current collector typically has a thickness of 3 μm to 500 μm. Similar to the positive current collector, fine irregularities can be formed on the surface of the current collector to enhance the bonding force of the negative electrode active material. For example, the negative current collector can be used in various shapes such as thin films, sheets, foils, meshes, porous bodies, foams, and nonwoven fabrics.

[0306] 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%.

[0307] The aforementioned adhesive enhances the adhesion between multiple negative electrode active material particles and the adhesion between the negative electrode active material and the negative electrode current collector. Specific examples of adhesives include polyvinylidene fluoride (PVDF), poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-co-HFP), polyvinyl alcohol, polyacrylonitrile, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone, polytetrafluoroethylene, polyethylene, polypropylene, ethylene propylene diene monomer (EPDM) rubber, sulfonated EPDM, styrene-butadiene rubber (SBR), fluororubber, or various copolymers thereof. One of these adhesives can be used alone or in mixtures of two or more. The adhesive comprises 1 wt% to 30 wt% relative to the total weight of the negative electrode active material layer, preferably 1 wt% to 20 wt%, and more preferably 1 wt% to 10 wt%.

[0308] 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.

[0309] 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.

[0310] Another aspect of the present invention relates to a battery including the aforementioned electrode assembly. The battery houses the electrode assembly and electrolyte together within a battery case, which can be appropriately selected without limitation, such as a pouch type or a metal can type, as is commonly used in the art.

[0311] 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.

[0312] Specifically, the electrolyte may include organic solvents and lithium salts.

[0313] 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, the aforementioned organic solvents can include ester solvents such as methyl acetate, ethyl acetate, γ-butyrolactone, and ε-caprolactone; ether solvents such as dibutyl ether or tetrahydrofuran; ketone solvents such as cyclohexanone; aromatic hydrocarbon solvents such as benzene and fluorobenzene; carbonate solvents such as dimethyl carbonate (DMC), diethyl carbonate (DEC), methylethyl carbonate (MEC), ethylmethyl carbonate (EMC), ethylene carbonate (EC), and propylene carbonate (PC); and 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 compounds such as 1,3-dioxolane; or sulfolane compounds, etc. Preferably, carbonate solvents are used, and more preferably, a mixture 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.).

[0314] As the lithium salt mentioned above, any compound that can provide lithium ions for lithium batteries can be used without any limitation. Specifically, the 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 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.

[0315] In addition to the constituent components of the electrolyte, the electrolyte may further include additives to improve battery life characteristics, suppress battery capacity reduction, and increase battery discharge capacity. For example, additives may be used alone or in combination with haloalkylene carbonates such as difluoroethylene carbonate, pyridine, triethyl phosphite, triethanolamine, cyclic ethers, ethylenediamine, N-glycol dimethyl ether, hexamethylphosphoric triamine, nitrobenzene derivatives, sulfur, quinone imine dyes, N-substituted oxazolidinones, N,N-substituted imidazolides, ethylene glycol dialkyl ethers, ammonium salts, pyrroles, dimethoxyethanol, or aluminum trichloride, but are not limited thereto. The additives may comprise 0.1 wt% to 10 wt% relative to the total weight of the electrolyte, preferably 0.1 wt% to 5 wt%.

[0316] 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.

[0317] 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.

[0318] Figure 47 This is a diagram illustrating an electrode assembly according to an embodiment of the present invention. Figure 48 It shows along Figure 47 A cross-sectional view of the section cut by the cutting line A-A'.

[0319] Reference Figure 39 as well as Figure 40 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.

[0320] 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.

[0321] 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.

[0322] 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.

[0323] 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.

[0324] 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.

[0325] 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.

[0326] 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.

[0327] 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.

[0328] 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.

[0329] 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.

[0330] 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.

[0331] 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.

[0332] 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.

[0333] 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.

[0334] 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.

[0335] Below, refer to Figures 41 to 46 A method for manufacturing an electrode assembly according to an embodiment of the present invention will be described in detail.

[0336] Figure 41 as well as Figure 42 This is a diagram illustrating the process of manufacturing a negative electrode according to an embodiment of the present invention. Specifically, Figure 41 This is a plan view of the negative electrode tab from above. Figure 42 View from the front Figure 41 A front view of the negative electrode tab.

[0337] Reference Figure 41 as well as Figure 42 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.

[0338] Specifically, a negative electrode active material portion 420 can be formed by coating a negative electrode active material, making it continuous along a third direction d3. Furthermore, the coating area is separated along a fourth direction d4 perpendicular to the third direction d3, thereby positioning the plurality of negative electrode active material portions 420 separately along the fourth direction d4. That is, the coating process can be performed such that the uncoated negative electrode portion 430 is located between the plurality of negative electrode active material portions 420.

[0339] 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.

[0340] 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 43This is a perspective view showing the negative electrode according to an embodiment of the present invention.

[0341] Reference Figures 41 to 43 , such as in Figure 41 as well as Figure 42 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 43 This is the negative electrode 400 shown. That is, Figure 43 The negative electrode 400 is equivalent to for Figure 41 as well as Figure 42 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.

[0342] 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.

[0343] Figure 44 as well as Figure 45 This is a diagram illustrating the process of manufacturing a positive electrode according to an embodiment of the present invention. Specifically, Figure 44 is a plan view of the positive electrode tab from above. Figure 45 View from the front Figure 44 A front view of the positive electrode tab.

[0344] Reference Figure 44 as well as Figure 45 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.

[0345] Specifically, a positive electrode active material can be coated to form a positive electrode active material portion 520, making it continuous along a third direction d3. Furthermore, the coating interval is adjusted along a fourth direction d4 perpendicular to the third direction d3, thereby positioning the multiple positive electrode active material portions 520 separately. That is, the coating process can be performed such that the uncoated positive electrode portion 530 is located between the multiple positive electrode active material portions 520.

[0346] 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.

[0347] Then, the positive electrode 500 can be manufactured by cutting open the uncoated portion 530 and the active material portion 220. Figure 46 This is a perspective view showing a positive electrode 500 according to an embodiment of the present invention.

[0348] Reference Figures 44 to 46 , such as in Figure 44 as well as Figure 45 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 46 This is the positive electrode shown as 500. That is, Figure 46 The positive electrode 500 is equivalent to for Figure 44 as well as Figure 45 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.

[0349] 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.

[0350] Refer to together Figure 39 , Figure 43 as well as Figure 46 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.

[0351] Refer again Figures 44 to 46In 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.

[0352] 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 39 as well as Figure 40 The shown gel roll structure 300S has a reduced loading portion 500D where the loading of the positive electrode active material is less than that of the adjacent regions.

[0353] 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 45 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.

[0354] 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.

[0355] Reference Figure 46 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.

[0356] Reference Figure 39 as well as Figure 40 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.

[0357] 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 gradually decrease as it moves toward the first direction d1.

[0358] 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.

[0359] 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.

[0360] Below, refer to Figures 47 to 50 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.

[0361] Figure 47 This is a diagram illustrating an electrode assembly according to a comparative example of the present invention. Figure 48 It shows along Figure 47 A cross-sectional view of the section cut by the cutting line B-B'.

[0362] Reference Figure 47 as well as Figure 48 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.

[0363] 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.

[0364] Figure 49 This is a diagram illustrating the process of manufacturing the negative electrode 700 according to a comparative example of the present invention.

[0365] Reference Figure 49 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.

[0366] On the other hand, refer to again Figure 47 as well as Figure 48The 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.

[0367] Figure 50 This is a diagram illustrating the process of manufacturing the positive electrode 800 according to a comparative example of the present invention.

[0368] Reference Figure 50 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.

[0369] 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.

[0370] That is, except for the load reduction section 500D (refer to) Figure 48 In addition, the electrode assembly 600 according to the comparative example of the present invention may have a structure similar to that of the electrode assembly 300 according to this embodiment.

[0371] Reference Figure 47 as well as Figure 48 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.

[0372] Conversely, refer to Figure 39 as well as Figure 40According 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.

[0373] contrast Figure 39 as well as Figure 40 The A1 area and Figure 47 as well as Figure 48 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.

[0374] 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 cover plate 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.

[0375] 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.

[0376] 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.

[0377] 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.

[0378] 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.

[0379] 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.

[0380] 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.

[0381] Preferably, the cylindrical battery according to the present invention can be a tabless-less battery without electrode tabs, but it is not limited thereto.

[0382] 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.

[0383] 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.

[0384] The present invention will now be described in further detail through specific embodiments.

[0385] Example 1

[0386] 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 Li[Ni] is a positive electrode active material with a single-peak particle size distribution of 3 μm and 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.

[0387] 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.

[0388] 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.

[0389] Comparative Example 1

[0390] 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.

[0391] Experimental Example 1

[0392] A hot box test was performed on the 4680 battery cells manufactured using Example 1 and Comparative Example 1.

[0393] 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. For accurate evaluation, the battery cell from Example 1 underwent two hot box evaluations. Figure 31 as well as Figure 32 The measurement results are shown.

[0394] Figure 31 Figure 31 is a graph showing the hot box test results of the 4680 battery cell manufactured by Example 1, and Figure 32 is a graph showing the hot box test results of the 4680 battery cell manufactured by Comparative Example 1.

[0395] pass Figure 31 as well as Figure 32 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.

[0396] Example 2-1

[0397] 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 28 SEM images of the positive electrode active material used in Example 2-1 are shown.

[0398] 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.

[0399] 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.

[0400] 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.

[0401] Example 2-2

[0402] 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 cells were manufactured using the same method as in Example 2-1. Figure 29 SEM images of the positive electrode active material used in Examples 2-2 are shown.

[0403] Comparative Example 2-1

[0404] 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.

[0405] Comparative Example 2-2

[0406] 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.

[0407] Figure 30 SEM images of the positive electrode active material used in Comparative Example 2-2 are shown.

[0408] Experimental Example 2-1

[0409] 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.

[0410] 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.

[0411] Table 1 below and Figure 33 , Figure 34 The test results are shown. Figure 33 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 34 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.

[0412] Table 1

[0413]

[0414] Refer to Table 1 above. Figure 33 as well as Figure 34 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 65 minutes. Conversely, in Comparative Example 2-1, which used secondary particles as the positive electrode active material, and in the example using D…min The 4680 battery cells of Comparative Example 2-2, which contain single-particle / similar-particle shaped positive electrode active materials smaller than 1.0 μm, exhibited a rapid temperature rise.

[0415] Experimental Example 2-2

[0416] To confirm the degree of cracking of the positive electrode active material particles after rolling in Examples 2-1 and Comparative Example 2-1, the cross-sections of the positive electrodes were photographed using SEM after being cut using an ion milling device. Figure 35 shows a cross-sectional SEM image of the positive electrode manufactured in Example 2-1. Figure 36 A cross-sectional SEM image of the positive electrode fabricated in Comparative Example 2-1 is shown.

[0417] pass Figure 35 as well as Figure 36 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.

[0418] Example 3-1

[0419] 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%.

[0420] Example 3-2

[0421] 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%.

[0422] Example 3-3

[0423] 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%.

[0424] Examples 3-4

[0425] 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%.

[0426] Comparative Example 3-1

[0427] 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%.

[0428] Comparative Example 3-2

[0429] 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%.

[0430] Experimental Example 3-1 - Measurement of Charge / Discharge Capacity and Charge / Discharge Efficiency

[0431] 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.

[0432] Table 2

[0433]

[0434] 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.

[0435] Experiment Example 3-2 - Confirmation of Resistance Characteristics

[0436] 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 37 The experimental results are shown.

[0437] Reference Figure 37 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.

[0438] Experimental Example 3-3 - Measurement of High-Temperature Service Life Characteristics and Resistance Increase Rate

[0439] 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.

[0440] At this point, the negative electrode is manufactured by mixing the negative electrode active material (graphite:SiO = 95:5 weight ratio mixture) in water at a weight ratio of 96:2:1.5:0.5, the conductive material (super C), styrene-butadiene rubber (SBR), and carboxymethyl cellulose (CMC) to produce a negative electrode slurry. The negative electrode slurry is then coated onto one side of a copper current collector sheet, dried at 150°C, and then calendered.

[0441] 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 38 The measurement results are shown.

[0442] Reference Figure 38Compared 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.

[0443] 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.

[0444] 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 first coated portion; a second electrode having a second uncoated portion and a second coated portion; and a separation membrane sandwiched between the first electrode and the second electrode. A battery casing that houses the electrode assembly through an opening formed on one side and is electrically connected to the electrode assembly; A battery terminal that passes through a blockage in the battery casing located on the opposite side of the aforementioned open portion and is electrically connected to the aforementioned electrode assembly; A cover plate, configured to cover the aforementioned open portion; and A first current collector is attached to the upper part of the electrode assembly and is electrically connected to the first uncoated portion of the first electrode and the battery terminal. The first electrode mentioned above includes At least one insulating layer is configured to simultaneously cover at least a portion of the first uncoated portion and at least a portion of the first coated portion. In this embodiment, at least a portion of the first uncoated portion is used as an electrode tab. The aforementioned battery terminals serve as the first electrode terminals. The outer surface of the aforementioned blocking portion of the battery casing serves as a second electrode terminal. In this configuration, the end of the first uncoated portion of the first electrode is bent in a direction parallel to the first current collector to form a bonding surface. The first current collector is bonded to the bonding surface. The battery terminals are electrically connected to the first uncoated portion having a first polarity. The battery casing is electrically connected to the second uncoated portion having a second polarity opposite to the first polarity, and The cylindrical battery also includes an insulating pad sandwiched between the battery casing and the battery terminals, thereby achieving insulation between the battery terminals and the battery casing.

2. The cylindrical battery according to claim 1, characterized in that, The aforementioned battery terminals include: The exposed terminal portion extends outward toward the outside of the aforementioned battery casing; and The terminal insertion portion penetrates the aforementioned blocking portion of the battery casing.

3. The cylindrical battery according to claim 1, characterized in that, The aforementioned insulating pads include: The gasket protrudes outward toward the outside of the aforementioned battery casing; and The gasket insertion portion penetrates the upper surface of the battery casing.

4. The cylindrical battery according to claim 1, characterized in that, The aforementioned battery terminals are riveted to the inner side of the aforementioned battery casing.

5. The cylindrical battery according to claim 1, characterized in that, The cover plate is insulated from the electrode assembly and has no polarity.

6. The cylindrical battery according to claim 1, characterized in that, The aforementioned insulating layer is disposed on both sides of the aforementioned first electrode.

7. The cylindrical battery according to claim 1, characterized in that, One end of the aforementioned insulating layer in the direction of the winding axis is located at the same height as one end of the aforementioned separating membrane in the direction of the winding axis, or outside one end of the separating membrane.

8. The cylindrical battery according to claim 1, characterized in that, One end of the aforementioned insulating layer in the direction of the winding axis is located at the same height as one end of the aforementioned separating membrane in the direction of the winding axis.

9. The cylindrical battery according to claim 1, characterized in that, The first uncoated portion protrudes further outward from the outer side of the insulating layer.

10. The cylindrical battery according to claim 1, characterized in that, The first coated portion mentioned above does not protrude further than the separation membrane in the winding axis direction.

11. The cylindrical battery according to claim 1, characterized in that, The first electrode mentioned above is the positive electrode.

12. The cylindrical battery according to claim 1, characterized in that, One end of the second electrode, which is separated from the above-mentioned insulating layer by the above-mentioned separation membrane, does not protrude further outward than one end of the above-mentioned separation membrane.

13. The cylindrical battery according to claim 1, characterized in that, The aforementioned first coated portion includes a landslide portion where the thickness of the active material layer is reduced compared to the central region of the aforementioned first coated portion.

14. The cylindrical battery according to claim 13, characterized in that, The aforementioned landslide portion is formed in the boundary region between the first coated portion and the first uncoated portion.

15. The cylindrical battery according to claim 13, characterized in that, The aforementioned landslide portion is respectively located at one end of the first electrode and the other end of the second electrode.

16. The cylindrical battery according to claim 13, characterized in that, The landslide portion provided on the first coated portion of the first electrode and the landslide portion provided on the second coated portion of the second electrode are provided in opposite directions.

17. The cylindrical battery according to claim 15, characterized in that, The separation membrane protrudes further outward than the other end of the first electrode and one end of the second electrode.

18. The cylindrical battery according to claim 13, characterized in that, The aforementioned insulating layer is configured to cover at least a portion of the aforementioned landslide area.

19. 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 includes single particles, similar single particles, or combinations thereof. The smallest particle size D exhibited in the volumetric cumulative distribution of the above-mentioned positive electrode active material min Above 1.0μm, In the above-mentioned volume accumulation distribution of positive electrode active material, the particle size D is 50% when the volume accumulation is 50%. 50 Below 5.0 μm, The largest particle size D observed in the volumetric cumulative distribution of the above-mentioned positive electrode active material is... max It is 12μm to 17μm.

20. The cylindrical battery according to claim 19, 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 .

21. The cylindrical battery according to claim 19, 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%.

22. The cylindrical battery according to claim 19, 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.

23. The cylindrical battery according to claim 19, 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%.

24. The cylindrical battery according to claim 19, characterized in that, The active material layer of the first electrode also includes carbon nanotubes.

25. The cylindrical battery according to claim 19, 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.

26. A battery pack, characterized in that, include: The cylindrical battery according to any one of claims 1 to 25; as well as The battery pack housing contains multiple of the aforementioned cylindrical batteries.

27. A car, characterized in that, include: The battery pack of claim 26.

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