Cylindrical battery, battery pack including same, and automobile

Abstract

According to an embodiment of the present invention, there is provided a cylindrical battery comprising: an electrode assembly; a battery housing that receives the electrode assembly from an opening; a current collecting plate including a support portion, a plurality of uncoated portion coupling portions coupled to a first uncoated portion, and a plurality of first housing coupling portions extending from the support portion to be coupled to an inner surface of the battery housing; a cap plate that covers the opening; an electrode terminal riveted through a through hole formed in a closing portion of the battery housing provided on an opposite side to the opening and electrically connecting with the second uncoated portion; and an insulating gasket interposed between the electrode terminal and the through hole, wherein the electrode terminal comprises a body portion, an outer flange portion, an inner flange portion, and a flat portion provided on an inner side of the inner flange portion.

Description

[Technical field]

[0001] The present invention relates to a cylindrical battery, a battery pack including the same, and an automobile.

[0002] This application claims priority to Korean Patent Application No. 10-2021-0142182, filed on October 22, 2021, the entire contents of which are incorporated herein by reference in their entirety in the specification and drawings of that application. [Background technology]

[0003] Conventional cylindrical batteries usually have a structure in which the tabs connecting the jelly roll to the external terminals are welded to the foil of the jelly roll. In cylindrical batteries with this structure, the current path is limited and the resistance of the jelly roll itself is very high.

[0004] For this reason, attempts have been made to reduce resistance by increasing the number of tabs connecting the jelly roll to the external terminals, but there is a limit to how much resistance can be reduced to the desired level and how much of a current path can be secured simply by increasing the number of tabs.

[0005] Therefore, in order to reduce the resistance of the jelly roll itself, there is a need to develop a new jelly roll structure and a current collector plate structure suitable for such a jelly roll structure. In particular, the application of such a new jelly roll structure and current collector plate is even more necessary in devices that require high-output / high-capacity battery packs, such as electric vehicles.

[0006] In addition, battery packs applied to electric vehicles and the like are likely to be exposed to vibration and impact when considering the usage environment. Therefore, there is a need to develop a cylindrical battery having a structure that reduces the risk of damage to welded parts even when vibration and external impact are applied, and a current collector structure applicable to such a cylindrical battery.

[0007] Meanwhile, secondary batteries, which can be easily applied to various products and have electrical properties such as high energy density, are widely used not only in portable devices but also in electric vehicles (EVs) and hybrid electric vehicles (HEVs) that are driven by electrical sources.

[0008] Such secondary batteries are attracting attention as a new energy source that not only has the primary advantage of dramatically reducing the use of fossil fuels, but also is environmentally friendly because they do not produce any by-products associated with energy use, and can improve energy efficiency.

[0009] Currently, the types of secondary batteries that are widely used include lithium ion batteries, lithium polymer batteries, nickel cadmium batteries, nickel metal hydride batteries, and nickel zinc batteries. The operating voltage of such a unit secondary battery cell is about 2.5V to 4.5V. Therefore, when a higher output voltage is required, a battery pack is constructed by connecting a plurality of battery cells in series. Also, a battery pack may be constructed by connecting a plurality of battery cells in parallel according to the charge / discharge capacity required for the battery pack. Therefore, the number and electrical connection form of battery cells included in the battery pack can be variously set according to the required output voltage or charge / discharge capacity.

[0010] Meanwhile, cylindrical, prismatic and pouch-type battery cells are known as types of secondary battery cells. In the case of a cylindrical battery cell, a separator, which is an insulator, is interposed between a positive electrode and a negative electrode, and the electrode assembly is wound up to form a jelly-roll-shaped electrode assembly, which is then inserted into a battery housing together with an electrolyte to form a battery. A strip-shaped electrode tab is connected to each uncoated portion of the positive electrode and the negative electrode, and the electrode tab electrically connects the electrode assembly to an electrode terminal exposed to the outside. For reference, the positive electrode terminal is a cap plate of a sealing body that seals an opening of the battery housing, and the negative electrode terminal is the battery housing.

[0011] However, in a conventional cylindrical battery cell having such a structure, current is concentrated in a strip-shaped electrode tab connected to the positive electrode uncoated portion and / or the negative electrode uncoated portion, resulting in high resistance, large heat generation, and poor current collection efficiency.

[0012] Resistance and heat generation are not major issues for small cylindrical battery cells with the form factor of 18650 or 21700. However, when the form factor of cylindrical battery cells is increased to apply them to electric vehicles, a large amount of heat is generated around the electrode tabs during the fast charging process, which can cause the cylindrical battery cell to catch fire.

[0013] To solve these problems, a cylindrical battery cell (so-called tab-less cylindrical battery cell) has been proposed, which is designed to have positive and negative uncoated parts at the upper and lower ends of a jelly roll-type electrode assembly, respectively, and has a structure in which current collecting plates are welded to these uncoated parts to improve current collection efficiency.

[0014] Figures 1 to 4 are diagrams showing the manufacturing process of a tabless cylindrical battery. Figure 1 shows the structure of the electrode, Figure 2 shows the electrode winding process, and Figure 3 shows the process of welding a current collector plate to the bent surface of the non-coated part. Figure 4 is a cross-sectional view of the tabless cylindrical battery cut in the longitudinal direction (Y direction).

[0015] 1 to 4, the positive electrode 210 and the negative electrode 211 have a structure in which an active material 221 is coated on a sheet-shaped current collector 220, and include an uncoated portion 222 on one long side along the winding direction (X direction).

[0016] The electrode assembly A is fabricated by sequentially stacking the positive electrode 210 and the negative electrode 211 together with two separators 212 as shown in Fig. 2, and then winding them in one direction (X direction). At this time, the non-coated portions of the positive electrode 210 and the negative electrode 211 are arranged in opposite directions.

[0017] After the winding process, the non-coated portion 210a of the positive electrode 210 and the non-coated portion 211a of the negative electrode 211 are bent toward the core side. Then, the current collectors 230 and 231 are welded and joined to the non-coated portions 210a and 211a, respectively.

[0018] Since no separate electrode tabs are attached to the positive electrode uncoated portion 210a and the negative electrode uncoated portion 211a, and the current collectors 230 and 231 are connected to external electrode terminals, and a current path is formed with a large cross-sectional area along the winding axis direction of the electrode assembly A (see arrow), there is an advantage in that the resistance of the battery can be reduced. This is because resistance is inversely proportional to the cross-sectional area of ​​the path through which the current flows.

[0019] However, as the form factor of cylindrical batteries increases and the magnitude of the charging current increases during fast charging, heat generation problems also occur in table-less cylindrical batteries.

[0020] Specifically, the conventional tabless cylindrical battery 240 includes a battery housing 241 and a sealing body 242, as shown in Fig. 4. The sealing body 242 includes a cap plate 242a, a sealing gasket 242b, and a connection plate 242c. The sealing gasket 242b surrounds the periphery of the cap plate 242a and is fixed by a crimping portion 243. In addition, the electrode assembly A is fixed in the battery housing 241 by a beading portion 244 to prevent vertical movement.

[0021] Typically, the positive terminal is the cap plate 242a of the sealed body 242, and the negative terminal is the battery housing 241. Thus, the current collector 230 coupled to the non-coated portion 210a of the positive electrode 210 is electrically connected to a connection plate 242c attached to the cap plate 242a via a strip-shaped lead 245. Also, the current collector 231 coupled to the non-coated portion 211a of the negative electrode 211 is electrically connected to the bottom of the battery housing 241. The insulator 246 covers the current collector 230 to prevent the battery housing 241 and the non-coated portion 210a of the positive electrode 210, which have opposite polarities, from coming into contact with each other and causing a short circuit.

[0022] When the current collecting plate 230 is connected to the connection plate 242c, a strip-shaped lead 245 is used. The lead 245 is either attached separately to the current collecting plate 230 or is manufactured integrally with the current collecting plate 230. However, since the lead 245 is in the form of a thin strip and has a small cross-sectional area, a large amount of heat is generated when a fast charging current flows. In addition, the excessive heat generated in the lead 245 is transferred to the electrode assembly A side and causes the separator 212 to shrink, which may cause an internal short circuit, which is a main cause of thermal runaway.

[0023] Furthermore, the leads 245 occupy a considerable amount of installation space within the battery housing 241. Therefore, the cylindrical battery 240 including the leads 245 has low space efficiency and is limited in increasing the energy density.

[0024] Furthermore, in order to connect the conventional table-less cylindrical batteries 240 in series and / or parallel, a bus bar part must be connected to the cap plate 242a of the sealed body 242 and the bottom surface of the battery housing 241, resulting in poor space efficiency. A battery pack mounted on an electric vehicle includes hundreds of cylindrical batteries 240. Therefore, the inefficiency of electrical wiring causes considerable complication in the assembly process of the electric vehicle and the maintenance of the battery pack.

[0025] On the other hand, when an electrode is manufactured using a cathode active material containing conventional secondary particles, cracks in the particles may occur, and the amount of gas generated may increase due to internal cracks during charging and discharging, which may cause problems in battery stability.

[0026] To solve this problem, positive electrode active materials in the form of single particles or pseudo-single particles, in which the primary particles are relatively large, have been developed. However, when the positive electrode active materials in the form of single particles or pseudo-single particles are applied to a high-loading electrode and rolled, there are problems in that the electrode cracks because the porosity of the electrode does not reach a target level, and there are problems in that the resistance characteristics and charge / discharge efficiency of the lithium secondary battery are deteriorated. Summary of the Invention [Problem to be solved by the invention]

[0027] The present invention has been made in light of the background of the prior art described above, and aims to provide a current collector having a structure suitable for an electrode assembly having a low resistance structure, and a cylindrical battery including the same.

[0028] Another object of the present invention is to provide a current collector having a structure that can significantly reduce the possibility of damage occurring at a welded portion with an electrode assembly and / or a welded portion with a battery housing even when vibration and impact are applied, and a cylindrical battery including the same.

[0029] Another object of the present invention is to provide a current collector plate having a structure that improves productivity by increasing the convenience of a welding process for electrically connecting a battery housing and a current collector plate in manufacturing a cylindrical battery, and a cylindrical battery including the same.

[0030] The present invention has been made in light of the background of the prior art described above, and aims to improve the electrode terminal structure of a cylindrical battery to increase space efficiency within a battery housing, thereby reducing the internal resistance of the cylindrical battery and increasing its energy density.

[0031] Another object of the present invention is to improve the electrode terminal structure of a cylindrical battery to increase the cross-sectional area of ​​the current path, thereby alleviating the problem of internal heat generation that occurs during fast charging.

[0032] Another object of the present invention is to provide a cylindrical battery having an improved structure, in which electrical wiring for series and / or parallel connection of cylindrical batteries can be performed on one side of the cylindrical battery.

[0033] Another object of the present invention is to provide a battery pack manufactured using a cylindrical battery having an improved structure, and a vehicle including the battery pack.

[0034] Another object of the present invention is to provide an electrode having excellent thermal stability, high electrical conductivity, and excellent rolling characteristics by using single particles or quasi-single particles as a positive electrode active material, and an electrode assembly including the same.

[0035] Another object of the present invention is to provide an electrode assembly having improved energy density by including a silicon-based negative electrode active material in the negative electrode.

[0036] It is yet another object of the present invention to provide an electrode assembly in which there is no risk of lithium precipitation and the section of a positive electrode active material portion is increased.

[0037] It is yet another object of the present invention to provide a cylindrical battery that exhibits excellent thermal safety even when the volume of the battery increases due to an increase in the form factor.

[0038] However, the technical problems that the present invention aims to solve are not limited to the problems described above, and other problems not mentioned will be clearly understood by those skilled in the art from the description of the invention below. [Means for solving the problem]

[0039] According to one embodiment of the present invention, there is provided a cylindrical battery comprising: an electrode assembly including a first electrode having a first uncoated portion and a second electrode having a second uncoated portion; a battery housing that receives the electrode assembly through an opening formed on one side; a current collecting plate including a support portion disposed on one side of the electrode assembly, a plurality of uncoated portion coupling portions extending from the support portion and coupling with the first uncoated portion, and a plurality of first housing coupling portions extending from the support portion and coupling with an inner surface of the battery housing; a cap plate that covers the opening; an electrode terminal riveted through a through hole formed in a closing portion of the battery housing provided on the opposite side to the opening and electrically connected to the second uncoated portion; and an insulating gasket interposed between the electrode terminal and the through hole, The electrode terminal includes a body portion inserted into the through hole, an external flange portion extending from a periphery of one side of the body portion exposed to an outer surface of the closing portion of the battery housing along the outer surface, an internal flange portion extending from a periphery of the other side of the body portion exposed to an inner surface of the closing portion toward the inner surface, and a flat portion provided on the inside of the internal flange portion.

[0040] The first housing coupling portion may be coupled to a beading portion of the battery housing.

[0041] The first housing coupling portion may include a first contact portion coupled to an inner surface of the battery housing, and a first connecting portion connecting the support portion and the contact portion.

[0042] The first contact portion may have a shape in which at least a portion extends along an inner circumferential surface of the battery housing.

[0043] The first connecting portion may include at least one first bent portion at which an extension direction is changed.

[0044] The current collector plate may further include a second housing coupling portion extending from an end of the non-coated portion coupling portion and coupled to an inner surface of the battery housing.

[0045] The second housing coupling portion may include a second contact portion coupled to an inner surface of the battery housing, and a second connecting portion connecting the support portion and the second contact portion.

[0046] The second contact portion may have a shape in which at least a portion extends along an inner circumferential surface of the battery housing.

[0047] The second connecting portion may include at least one second bent portion at which an extension direction is changed.

[0048] The inner surfaces of the flat portion and the closing portion may be parallel to one another.

[0049] The angle between the inner flange portion and the inner surface of the closing portion may be 0° to 60°.

[0050] Between the internal flange portion and the flat portion dent A section may be provided.

[0051] The above dent The portion may have an asymmetric groove cross-sectional configuration.

[0052] The asymmetric groove may include a sidewall of the flat portion and a sloped surface of the inner flange portion connected to an end of the sidewall.

[0053] The sidewall may be perpendicular to an inner surface of the closure.

[0054] The thickness of the inner flange portion may decrease away from the body portion.

[0055] The insulating gasket includes an external gasket interposed between the external flange portion and an outer surface of the closure portion, and an internal gasket interposed between the internal flange portion and an inner surface of the closure portion, and the internal gasket and the external gasket may have different thicknesses depending on the position.

[0056] In the region of the internal gasket, a thickness of a region interposed between an inner edge of the through hole connected to an inner surface of the closure portion and the internal flange portion may be relatively smaller than that of other regions.

[0057] An inner edge of the through hole may include a facing surface that faces the internal flange portion.

[0058] The internal gasket may extend beyond the internal flange portion.

[0059] The height of the flat portion relative to the inner surface of the closure portion may be greater than or equal to the height of the end portion of the internal gasket.

[0060] The height of the flat portion relative to the inner surface of the closure portion may be greater than or equal to the height of the end of the internal flange portion.

[0061] The active material layer of the second electrode includes a positive electrode active material including a single particle, a pseudo-single particle, or a combination thereof, and has a minimum particle size D represented in a cumulative volume distribution of the positive electrode active material. min is 1.0 μm or more, and D is a particle size when the volume cumulative amount in the volume cumulative distribution of the positive electrode active material is 50%. 50 is 5.0 μm or less, and D is the maximum particle size shown in the volume cumulative distribution of the positive electrode active material. max can be 12 μm to 17 μm.

[0062] In the cylindrical battery, the positive electrode active material may have a unimodal particle size distribution showing a single peak in a volume cumulative particle size distribution graph, and a particle size distribution (PSD) represented by the following formula may be 3 or less. Particle size distribution (PSD)=(D max -D min ) / D 50

[0063] The monoparticles, quasi-monoparticles, or a combination thereof may be included in an amount of 95 wt % to 100 wt % based on the total weight of the positive electrode active material included in the active material layer of the second electrode.

[0064] The positive electrode active material may contain 80 mol % or more of Ni based on the total number of moles of transition metals.

[0065] The active material layer of the second electrode may have a porosity of 15% to 23%, and the active material layer of the second electrode may contain flake graphite at a weight ratio of 0.05 wt % to 5 wt %.

[0066] The second electrode active material layer may further include carbon nanotubes.

[0067] The first electrode active material layer may include a silicon-based negative electrode active material and a carbon-based negative electrode active material in a weight ratio of 1:99 to 20:80.

[0068] A battery pack according to an embodiment of the present invention may include a plurality of cylindrical batteries according to an embodiment of the present invention as described above, and a pack housing that accommodates the plurality of cylindrical batteries.

[0069] A vehicle according to an embodiment of the present invention may include a battery pack according to an embodiment of the present invention as described above. Effect of the Invention

[0070] According to an embodiment of the present invention, the resistance in electrically connecting the electrode assembly and the battery housing can be significantly reduced.

[0071] In addition, according to one embodiment of the present invention, even if vibrations or impacts are applied during use of a secondary battery, the possibility of damage occurring at the welded portion between the current collector and the electrode assembly and / or the welded portion between the current collector and the battery housing can be significantly reduced.

[0072] In addition, according to an embodiment of the present invention, in manufacturing a cylindrical battery, the convenience of a welding process for electrically connecting a battery housing and a current collector plate is improved, thereby improving productivity.

[0073] In addition, according to one aspect of the present invention, the electrode terminal structure of the cylindrical battery cell is improved to increase space efficiency within a battery housing, thereby reducing the internal resistance of the cylindrical battery cell and increasing the energy density.

[0074] According to yet another aspect of the present invention, the problem of internal heat generation occurring during fast charging can be alleviated by improving the electrode terminal structure of a cylindrical battery cell to increase the cross-sectional area of ​​the current path.

[0075] According to yet another aspect of the present invention, electrical wiring for series and / or parallel connection of cylindrical battery cells may be performed on one side of the cylindrical battery cells.

[0076] According to yet another aspect of the present invention, there is provided a battery pack manufactured using a cylindrical battery cell having an improved structure, and a vehicle including the same.

[0077] According to yet another aspect of the present invention, the positive electrode is min By including a positive electrode active material powder having a particle size of 1.0 μm or more, the thermal safety of the battery can be further improved. According to the research of the present invention, it has been shown that even if single particles and / or pseudo single particles are applied to the positive electrode active material, the effect of suppressing particle cracking after rolling and improving thermal safety varies depending on the particle size of the positive electrode active material powder. In particular, when particles having a particle size of less than 1.0 μm are included in the positive electrode active material powder, the linear pressure increases in the rolling process, particle cracking increases, and thermal stability decreases, making it difficult to ensure sufficient thermal safety when applied to a large cylindrical battery. For this reason, in one embodiment of the present invention, min By using positive electrode active material powder with a particle size controlled to 1.0 μm or more, the thermal stability improvement effect is maximized.

[0078] According to yet another aspect of the present invention, the positive electrode is 50 , D max In addition, by containing positive active material powder with an appropriately controlled particle size distribution (PSD), the increase in resistance due to the application of single particles is minimized, thereby achieving excellent capacity and output characteristics.

[0079] According to yet another aspect of the present invention, the positive electrode includes a single-particle positive electrode active material coated with a conductive coating layer, or contains the novel CNT as a conductive material, thereby improving the conductivity of the electrode.

[0080] According to another aspect of the present invention, since the positive electrode active material layer includes flake graphite, when the positive electrode active material layer is rolled, the flake graphite provides a sliding effect to the positive electrode active material, thereby improving the rolling characteristics of the electrode and reducing the porosity of the electrode to a target level, thereby improving the stability, initial resistance characteristics, and charge / discharge efficiency of the cylindrical battery.

[0081] According to yet another aspect of the present invention, the negative electrode contains a silicon-based negative electrode active material with a large capacity, thereby enabling a higher energy density to be achieved.

[0082] According to yet another aspect of the present invention, since the positive electrode includes a reduced loading portion having a small loading amount of the positive electrode active material, the section of the positive electrode active material portion can be increased without the risk of lithium precipitation.

[0083] According to yet another aspect of the present invention, compared with a conventional battery having strip-shaped electrode tabs, the internal heat generation of the battery can be effectively reduced, thereby improving the thermal safety of the battery.

[0084] The following drawings attached to this specification illustrate preferred embodiments of the present invention and, together with the detailed description of the invention, serve to further understand the technical ideas of the present invention. Therefore, the present invention should not be interpreted as being limited to only the matters described in the drawings. [Brief description of the drawings]

[0085] [Figure 1] FIG. 1 is a plan view showing the structure of an electrode used in a conventional tabless cylindrical battery. [Diagram 2] 1A to 1C are diagrams illustrating a winding process of an electrode assembly included in a conventional tabless cylindrical battery. [Diagram 3] 6A to 6C are views showing a process of welding a current collector plate to a bent surface of a non-coated portion in an electrode assembly. [Figure 4] FIG. 1 is a cross-sectional view of a conventional tabless cylindrical battery cut in the longitudinal direction (Y direction). [Diagram 5] 1 is a cross-sectional view showing an internal structure of a cylindrical battery according to an embodiment of the present invention. [Figure 6] FIG. 2 is a diagram showing a current collector plate according to an embodiment of the present invention. [Figure 7] 4A to 4C are diagrams showing various exemplary shapes of a first connection portion of a current collecting plate according to an embodiment of the present invention. [Figure 8] 4A to 4C are diagrams showing various exemplary shapes of a first connection portion of a current collecting plate according to an embodiment of the present invention. [Figure 9] 4A to 4C are diagrams showing various exemplary shapes of a first connection portion of a current collecting plate according to an embodiment of the present invention. [Figure 10] 11A and 11B are diagrams illustrating the shape of a first connection portion according to the height of an electrode assembly. [Figure 11] 11A and 11B are diagrams illustrating the shape of a first connection portion according to the height of an electrode assembly. [Figure 12] FIG. 13 is a diagram showing a current collector plate according to another embodiment of the present invention. [Figure 13] FIG. 13 is a diagram showing a current collector plate according to still another embodiment of the present invention. [Figure 14] 14A to 14C are diagrams showing exemplary configurations of the second connecting portion of the current collector plate shown in FIG. 13. [Figure 15] 1 shows a current collector plate according to an embodiment of the present invention having a different configuration than those described and shown in the previous embodiments. [Figure 16] 1 shows a current collector plate according to an embodiment of the present invention having a different configuration than those described and shown in the previous embodiments. [Figure 17] FIG. 1 illustrates a battery pack according to an embodiment of the present invention. [Figure 18] FIG. 1 illustrates a vehicle according to an embodiment of the present invention. [Figure 19] 4 is a cross-sectional view showing a riveting structure of an electrode terminal according to an embodiment of the present invention; [Figure 20] FIG. 20 is an enlarged cross-sectional view of the portion indicated by the dotted circle in FIG. 19. [Figure 21] 1 is a cross-sectional view of a cylindrical battery cell according to an embodiment of the present invention taken along a longitudinal direction (Y direction). [Figure 22] 1 is a plan view showing an electrode structure according to a preferred embodiment of the present invention; [Figure 23] 1 is a cross-sectional view taken along a longitudinal direction (Y direction) of an electrode assembly in which a segmented structure of an uncoated portion of an electrode according to an embodiment of the present invention is applied to a first electrode and a second electrode. [Figure 24] 4 is a cross-sectional view of an electrode assembly in which a non-coated portion is bent according to an embodiment of the present invention, cut along a longitudinal direction (Y direction). [Diagram 25] 1 is a scanning microscope photograph of a novel CNT according to an embodiment of the present invention. [Figure 26] This is a scanning microscope photograph of a carbon nanotube that has been commonly used up until now (conventional CNT). [Figure 27] 1 is a table showing a comparison of the physical properties of conventional CNTs and new CNTs. [Figure 28] 1 is a graph showing sheet resistance and high-temperature life characteristics for each conductive material ratio when single-particle active material particles are used as a positive electrode active material. [Figure 29] 1 is a graph showing sheet resistance and high-temperature life characteristics for each conductive material ratio when single-particle active material particles are used as a positive electrode active material. [Diagram 30] 1 is a graph showing sheet resistance and high-temperature life characteristics for each conductive material ratio when single-particle active material particles are used as a positive electrode active material. [Diagram 31]1 is a graph showing sheet resistance and high-temperature life characteristics for each conductive material ratio when single-particle active material particles are used as a positive electrode active material. [Diagram 32] 1 is a table comparing the solid content and viscosity of a positive electrode slurry and the resistance values ​​in the MP coating layer and the MP interface layer when carbon nanotubes (new CNTs) having a BET specific surface area of ​​300 m2 / g to 500 m2 / g are used and when carbon nanotubes (conventional CNTs) having a BET of 200 m2 / g or more and less than 300 m2 / g are used. [Diagram 33] 2 is a SEM photograph of the positive electrode active material used in Example 2-1 of the present invention. [Diagram 34] 2 is a SEM photograph of the positive electrode active material used in Example 2-2 of the present invention. [Diagram 35] 1 is a SEM photograph of the positive electrode active material used in Comparative Example 2-2 of the present invention. [Diagram 36] 1 is a graph showing the hot box test results of the 4680 cell manufactured according to Example 1 of the present invention. [Figure 37] 1 is a graph showing the hot box test results of a 4680 cell manufactured according to Comparative Example 1 of the present invention. [Figure 38] 1 is a graph showing the results of a hot box test of 4680 cells manufactured according to Sample 1 of Example 2-1 of the present invention and Comparative Example 2-1. [Figure 39] 1 is a graph showing the results of a hot box test of 4680 cells manufactured according to Samples 2 and 3 of Example 2-1 of the present invention, Samples 1 and 2 of Example 2-2, and Comparative Example 2-2. [Diagram 40] 2 is a cross-sectional SEM photograph of the positive electrode produced in Example 2-1 of the present invention. [Diagram 41] 1 is a cross-sectional SEM photograph of a positive electrode produced in Comparative Example 2-1. [Diagram 42] 13 is a graph showing the results of measuring resistance characteristics according to SOC while charging coin-type half cells including positive electrodes according to Example 3-3, Comparative Example 3-1, and Comparative Example 3-2 up to 4.2 V. [Diagram 43]1 is a graph showing the measurement results of capacity retention and DCIR increase obtained by a charge-discharge cycle experiment on 4680 cells according to Example 3-1, Example 3-3, and Comparative Example 3-1 of the present invention. [Diagram 44] 1 is a diagram illustrating an electrode assembly according to an embodiment of the present invention. [Diagram 45] 45 is a cross-sectional view taken along line AA' in FIG. 44. [Figure 46] 2A to 2C are diagrams illustrating a process for manufacturing a negative electrode according to an embodiment of the present invention. [Figure 47] 2A to 2C are diagrams illustrating a process for manufacturing a negative electrode according to an embodiment of the present invention. [Figure 48] 1 is a perspective view showing a negative electrode according to an embodiment of the present invention; [Figure 49] 2A to 2C are diagrams illustrating a process for manufacturing a positive electrode according to an embodiment of the present invention. [Figure 50] 2A to 2C are diagrams illustrating a process for manufacturing a positive electrode according to an embodiment of the present invention. [Figure 51] FIG. 2 is a perspective view showing a positive electrode according to an embodiment of the present invention. [Figure 52] FIG. 13 is a diagram illustrating an electrode assembly according to a comparative example of the present invention. [Diagram 53] 53 is a cross-sectional view taken along line BB' in FIG. 52. [Figure 54] 4A to 4C are diagrams illustrating a process for producing a negative electrode according to a comparative example of the present invention. [Figure 55] 4A to 4C are diagrams illustrating a process for producing a positive electrode according to a comparative example of the present invention. [Figure 56] 1 is a graph showing a change in energy density depending on the content of a silicon-based negative electrode active material and whether or not the silicon-based negative electrode active material is doped in a battery using a mixture of a silicon-based negative electrode active material and a carbon-based negative electrode active material as a negative electrode active material; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0086] Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the attached drawings. Prior to this, the terms and words used in this specification and claims should not be interpreted as being limited to their ordinary or dictionary meanings, but should be interpreted as being in accordance with the meaning and concept of the technical idea of ​​the present invention, in accordance with the principle that the inventor himself can appropriately define the concept of the term in order to best describe the invention. Therefore, it should be understood that the embodiment described in this specification and the configuration shown in the drawings are only one most preferred embodiment of the present invention, and do not represent the entire technical idea of ​​the present invention, and therefore there may be various equivalents and modifications that can be substituted for them at the time of this application.

[0087] In order to facilitate understanding of the present invention, the accompanying drawings may be drawn not to scale but with some components exaggerated. In addition, the same reference numerals may be used to refer to the same components in different embodiments.

[0088] The size and thickness of each component shown in the drawings are arbitrarily shown for convenience of explanation, and the present invention is not necessarily limited thereto. In the drawings, the thicknesses are enlarged to clearly show the multiple layers and regions. In the drawings, the thicknesses of some layers and regions are exaggerated for convenience of explanation.

[0089] Furthermore, when a part such as a layer, film, region, or plate is said to be "on" or "above" another part, this includes not only the part "directly above" the other part, but also the case where the other part exists between them. Conversely, when a part is said to be "directly above" another part, it means that there is no other part between them. Note that being "on" or "above" a reference part means being located above or below the reference part, and does not necessarily mean "on" or "above" in the opposite direction to gravity.

[0090] Throughout the specification, when a part "comprises" a certain element, it does not mean excluding other elements, but means that the part may further include other elements, unless otherwise specified.

[0091] Additionally, throughout the specification, "planar" refers to the target portion viewed from above, and "cross-sectional" refers to the target portion cut vertically and viewed from the side.

[0092] 5, a cylindrical battery 1 according to an embodiment of the present invention includes an electrode assembly 10, a battery housing 20, a current collecting plate (first current collecting plate) 30, a cap plate 40, and an electrode terminal 50. The cylindrical battery 1 may further include a sealing gasket 60 and / or an insulating gasket 54 and / or a current collecting plate (second current collecting plate) 70 and / or an insulator 80.

[0093] The electrode assembly 10 includes a first electrode having a first non-coated portion (first electrode tab) 11 and a second electrode having a second non-coated portion (second electrode tab) 12. The non-coated electrode portion or non-coated portion referred to below means an electrode tab. The electrode assembly 10 may include a first electrode having a first polarity, a second electrode having a second polarity, and a separator interposed between the first electrode and the second electrode. The electrode assembly 10 may be manufactured by winding up a laminate formed by stacking the first electrode, the separator, and the second electrode in this order at least once. That is, the electrode assembly 10 applied to an embodiment of the present invention may be a jelly roll type electrode assembly. In this case, a separator may be further provided on an outer circumferential surface of the electrode assembly 10 for insulation from the battery housing 20.

[0094] The first electrode includes a first electrode collector and a first electrode active material applied to one or both sides of the first electrode collector. A first non-coated portion 11, where the first electrode active material is not applied, is present at one end of the first electrode collector in a width direction (parallel to the height direction of the cylindrical battery 1 shown in FIG. 5). The first non-coated portion 11 functions as a first electrode tab. The first non-coated portion 11 is provided at an upper portion in a height direction (parallel to the height direction of the cylindrical battery 1 shown in FIG. 5) of the electrode assembly 10 accommodated in the battery housing 20. The first non-coated portion 11 may be, for example, a negative electrode non-coated portion.

[0095] The second electrode includes a second electrode collector and a second electrode active material applied to one or both sides of the second electrode collector. A second non-coated portion 12, where the second electrode active material is not applied, is present at the other end of the second electrode collector in the width direction (parallel to the height direction of the cylindrical battery 1 shown in FIG. 5). The non-coated portion functions as a second electrode tab. The second non-coated portion 12 is provided at a lower portion in the height direction of the electrode assembly 10 accommodated in the battery housing 20. The second non-coated portion 12 may be, for example, a positive electrode non-coated portion.

[0096] In one embodiment of the present invention, the positive electrode active material coated on the positive electrode and the negative electrode active material coated on the negative electrode may be any active material known in the art without any limitations.

[0097] The battery housing 20 is a generally cylindrical container having an opening on one side thereof and is made of a conductive metal material. A side of the battery housing 20 and a closed portion 20a located on the opposite side of the opening (lower side in FIG. 5) are generally formed integrally. That is, the battery housing 20 generally has an open upper end in its height direction and a closed lower end. The lower surface of the battery housing 20 may have a generally flat shape. The battery housing 20 receives the electrode assembly 10 through an opening formed on one side thereof in its height direction. The battery housing 20 may also receive an electrolyte through the opening.

[0098] The battery housing 20 may include a beading portion 21 formed at an upper end thereof. The battery housing 20 may further include a crimping portion 22 formed on the upper portion of the beading portion 21. The beading portion 21 has a shape in which the periphery of the battery housing 20 is pressed in to a predetermined depth. The beading portion 21 is formed on the upper portion of the electrode assembly 10. The inner diameter of the battery housing 20 in the region where the beading portion 21 is formed is smaller than the diameter of the electrode assembly 10.

[0099] The beading portion 21 provides a support surface on which the cap plate 40 is provided. The beading portion 21 may also provide a support surface on which at least a portion of the periphery of the current collecting plate 30 described below is placed and coupled. That is, at least a portion of the edge of the current collecting plate 30 according to an embodiment of the present invention and / or the periphery of the cap plate 40 according to an embodiment of the present invention may be provided on the upper surface of the beading portion 21. In order to stably support at least a portion of the periphery of the current collecting plate 30 and / or the periphery of the cap plate 40, the upper surface of the beading portion 21 may have a shape extending along a direction substantially parallel to the lower surface of the battery housing 20, i.e., along a direction substantially perpendicular to the side wall of the battery housing 20. The beading portion 21 may be omitted, and at least a portion of the periphery of the current collecting plate 30 may be directly attached to the flat side wall of the battery housing 20.

[0100] The crimping portion 22 is formed on the upper part of the beading portion 21. The crimping portion 22 is bent to extend so as to surround the peripheral portion of the cap plate 40 disposed on the upper part of the beading portion 21. The cap plate 40 is fixed to the beading portion 21 by the shape of the crimping portion 22. Of course, instead of the crimping portion 22, the cap plate 40 may be fixed while covering the opening of the battery housing 20 by using another fixing structure.

[0101] Hereinafter, a current collecting plate (first current collecting plate) 30 according to an embodiment of the present invention will be described in detail with reference to FIGS.

[0102] 5 and 6, a current collecting plate 30 according to an embodiment of the present invention is accommodated inside a battery housing 20, electrically connected to the electrode assembly 10, and electrically connected to the battery housing 20. That is, the current collecting plate 30 electrically connects the electrode assembly 10 and the battery housing 20.

[0103] The current collecting plate 30 includes a support portion 31 disposed at approximately the center of one surface of the electrode assembly 10, a plurality of non-coated portion coupling portions 32 extending from the support portion 31 to couple with the first non-coated portion 11, and a plurality of first housing coupling portions 33 extending from the support portion 31 to couple with the inner surface of the battery housing 20. The non-coated portion coupling portions 32 and the first housing coupling portions 33 are indirectly connected to each other via the support portion 31 and are not directly connected to each other. This can minimize the possibility of damage occurring to coupling portions between the current collecting plate 30 and the electrode assembly 10 and the coupling portions between the current collecting plate 30 and the battery housing 20 when an external impact is applied to the cylindrical battery 1 according to an embodiment of the present invention.

[0104] The support portion 31 and the non-coated portion connecting portions 32 are disposed on the upper portion of the electrode assembly 10 and are located below the beading portion 21 when the beading portion 21 is formed on the battery housing 20 .

[0105] The support part 31 has a current collecting plate hole 30a formed at a position corresponding to a winding center hole C formed in the center of the electrode assembly 10. The winding center hole C and the current collecting plate hole 30a, which are in communication with each other, can function as a passage for inserting a welding rod or irradiating a laser for welding an electrode terminal 50 and a current collecting plate (second current collecting plate) 70, which will be described later, or for welding an electrode terminal 50 and a lead tab (not shown).

[0106] The non-coated portion coupling parts 32 may extend radially from the support part 31 of the current collector plate 30 toward the side wall of the battery housing 20. The non-coated portion coupling parts 32 may be spaced apart from each other along the periphery of the support part 31. Meanwhile, in order to ensure a coupling force and reduce electrical resistance by increasing the coupling area between the current collector plate 30 and the electrode assembly 10, not only the non-coated portion coupling parts 32 but also the support part 31 may be coupled to the first non-coated portion 11. An end of the first non-coated portion 11 may be formed in a shape bent in parallel to the non-coated portion coupling parts 32. When the end of the first non-coated portion 11 is formed in this manner and coupled to the non-coated portion coupling parts 32 in a state parallel to the non-coated portion coupling parts 32, the coupling area is increased, thereby improving the coupling force and reducing the electrical resistance, and the total height of the electrode assembly 10 is minimized, thereby improving the energy density.

[0107] The first housing coupling parts 33 may extend radially from the support part 31 of the current collector plate 30 toward the side wall of the battery housing 20. The first housing coupling parts 33 may be spaced apart from each other along the circumference of the support part 31. At least one first housing coupling part 33 may be located between adjacent non-coated part coupling parts 32. The first housing coupling parts 33 may be coupled to, for example, the beading part 21 on the inner surface of the battery housing 20. The first housing coupling part 33 may be coupled to the upper surface of the beading part 21 in particular. When such a structure is applied to the cylindrical battery 1 according to an embodiment of the present invention, the first housing coupling parts 33 may be smoothly attached to the beading part 21 by accommodating the electrode assembly 10 with the current collector plate 30 coupled thereto in the battery housing 20. This allows the welding process of the battery housing 20 and the current collector plate 30 to be easily performed. In addition, the upper surface of the beading portion 21 extends in a direction substantially parallel to the lower surface of the battery housing 20, i.e., in a direction substantially perpendicular to the side wall of the battery housing 20, and the first housing coupling portion 33 also extends in the same direction, so that the first housing coupling portion 33 can stably contact the beading portion 21. In addition, since the first housing coupling portion 33 stably contacts the beading portion 21, the welding between the two parts is smooth, thereby improving the bonding strength between the two parts and minimizing the increase in resistance at the bonding portion.

[0108] Next, referring to Figures 7 to 11, the first housing coupling portion 33 includes a first contact portion 33a that couples to the inner surface of the battery housing 20, and a first connecting portion 33b that connects between the support portion 31 and the first contact portion 33a.

[0109] The first contact portion 33a is coupled to an inner surface of the battery housing 20. In the case where the beading portion 21 is formed on the battery housing 20, the first contact portion 33a may be coupled to the beading portion 21 as described above. In this case, for stable contact and coupling, as described above, both the beading portion 21 and the first contact portion 33a may have a shape extending along a direction substantially parallel to the lower surface of the battery housing 20, i.e., a direction substantially perpendicular to the side wall of the battery housing 20.

[0110] The first connecting portion 33b may have at least one first bent portion B1 where the extension direction is changed between the support portion 31 and the first contact portion 33a. That is, the first connecting portion 33b may have, for example, a spring-like structure or a bellows-like structure that can contract and expand within a certain range. The structure of the first connecting portion 33b allows the first contact portion 33a to be closely attached to the beading portion 21 during the process of housing the electrode assembly 10 coupled with the current collecting plate 30 into the battery housing 20 even if there is a variation in height of the electrode assembly 10 within a certain range.

[0111] For example, it is preferable that the vertical distance D between the first contact portion 33a and the support portion 31 when no external force is applied to the current collecting plate 30 and no deformation is present be the same as the vertical distance between the upper surface of the beading portion 21 and the support portion 31 when the electrode assembly 10 to which the current collecting plate 30 is coupled is installed in the battery housing 20, or be smaller within the extensible range of the first connecting portion 33b. If the first connecting portion 33b is configured to satisfy this condition, the first contact portion 33a can be smoothly and closely attached to the beading portion 21 when the electrode assembly 10 to which the current collecting plate 30 is coupled is installed in the battery housing 20.

[0112] Furthermore, the contractible and expandable structure of the first connecting part 33b reduces, within a certain range, the impact caused by the movement of the electrode assembly 10 even if vibration and / or impact occurs during use of the cylindrical battery 1 (see FIG. 5) and the electrode assembly 10 moves up and down. That is, the contractible and expandable structure of the first connecting part 33b can act as a buffer to prevent impact from being transmitted to the coupling portion between the first contact part 33a and the battery housing 20 and the coupling portion between the uncoated part coupling part 32 and the first uncoated part 11 (see FIGS. 5 to 9).

[0113] Next, referring to Fig. 12, a current collector plate 30 according to another embodiment of the present invention is shown. The current collector plate 30 according to the other embodiment of the present invention differs from the current collector plate 30 described above (the current collector plate described with reference to Fig. 6 as an example) only in the shape of the first contact portion 33a, and otherwise the structure of the current collector plate 30 described above can be substantially the same.

[0114] 5 and 12, the first contact portion 33a may have a shape in which at least a portion thereof extends along the inner circumferential surface of the battery housing 20. In this case, in order to maximize the contact area, the current collecting plate 30 may be configured such that the sum of the extension lengths of the first contact portions 33a of the plurality of first housing coupling portions 33 is substantially equal to the inner circumferential surface of the battery housing 20.

[0115] 13 and 14 together with Fig. 5, a current collecting plate 30 according to still another embodiment of the present invention is shown. The current collecting plate 30 according to still another embodiment of the present invention differs from the current collecting plate 30 according to the above-mentioned embodiment (the current collecting plate exemplarily described with reference to Figs. 6 and 12) only in that a second housing coupling part 34 is further provided, but otherwise the structure of the current collecting plate 30 described above can be substantially the same.

[0116] The second housing coupling portion 34 extends from an end of the non-coated portion coupling portion 32 and is coupled to the inner surface of the battery housing 20. At least one end of the plurality of non-coated portion coupling portions 32 is provided with the second housing coupling portion 34. The second housing coupling portion 34 includes a second contact portion 34a coupled to the inner surface of the battery housing 20, and a second connection portion 34b connecting the support portion 31 and the second contact portion 34a.

[0117] The second contact portion 34a is coupled to an inner surface of the battery housing 20. In the case where a beading portion 21 is formed on the battery housing 20, the second contact portion 34a may be coupled to the beading portion 21 similarly to the first contact portion 33a described above. In this case, as described above, for stable contact and coupling, both the beading portion 21 and the second contact portion 34a may have a shape extending in a direction substantially parallel to the lower surface of the battery housing 20, i.e., in a direction substantially perpendicular to the side wall of the battery housing 20.

[0118] Meanwhile, like the shape of the first contact portion 33a shown in Fig. 12, the second contact portion 34a may also have a shape in which at least a portion thereof extends along the inner circumferential surface of the battery housing 20, although this is not shown. In this case, in order to maximize the contact area between the current collecting plate 30 and the battery housing 20, the sum of the extension lengths of the second contact portions 34a of each of the plurality of second housing coupling portions 34 of the current collecting plate 30 may be configured to be substantially equal to the inner circumferential surface of the battery housing 20.

[0119] The second connecting portion 34b may have at least one second bent portion B2, in which the extension direction of the second connecting portion 34b is changed between the non-coated portion joining portion 32 and the second contact portion 34a, like the first connecting portion 33b described above. Due to the formation of the second bent portion B2, the second connecting portion 34b has a contractible and expandable structure, which provides advantages in the assembly process of the cylindrical battery 1 and a cushioning effect, as described above.

[0120] Although the drawings of the present invention show a case where only one second bending portion B2 is provided, the present invention is not limited thereto, and similar to the first connecting portion 33b described with reference to Figures 8 and 9 as an example, the second bending portion B2 may also be provided in a plurality of pieces.

[0121] Referring to FIG. 5, the cap plate 40 covers the opening formed on one side of the battery housing 20. The cap plate 40 may be fixed by a crimping portion 22 formed on the upper end of the battery housing 20. In this case, a sealing gasket 60 may be interposed between the battery housing 20 and the cap plate 40 and between the current collector 30 and the cap plate 40 in order to improve the fixing force and the sealing property of the battery housing 20. However, in one embodiment of the present invention, the cap plate 40 is not a part that functions as a current path. Therefore, if the sealing property of the opening of the battery housing 20 can be ensured by firmly fixing the battery housing 20 and the cap plate 40 by welding or by applying other parts, the application of such a sealing gasket 60 is not essential.

[0122] When the sealing gasket 60 is applied, the extension length of the portion of the sealing gasket 60 interposed between the current collector plate 30 and the cap plate 40 may be formed shorter than the extension length of the portion interposed between the battery housing 20 and the cap plate 40. If the sealing gasket 60 extends too far toward the center of the cylindrical battery 1 inside the battery housing 20, the current collector plate 30 may be deformed due to interference between the sealing gasket 60 and the current collector plate 30, and thus, a force may be applied to the welded portion between the current collector plate 30 and the battery housing 20 and / or the welded portion between the current collector plate 30 and the first non-coated portion 11, causing a defect. Therefore, by controlling the extension length partially in the sealing gasket 60 as described above, the occurrence of such a defect can be prevented.

[0123] Meanwhile, the cap plate 40 may include a vent portion 41 formed to prevent an increase in internal pressure due to gas generated inside the battery housing 20. The vent portion 41 is formed in a part of the cap plate 40 and is a region structurally weaker than the surrounding region so that it is easily determined when internal pressure is applied. The vent portion 41 may be, for example, a region having a thickness thinner than the surrounding region. The vent portion 41 may be formed, for example, by notching one or both sides of the cap plate 40 to partially reduce the thickness of the battery housing 20.

[0124] The electrode terminal 50 penetrates the closed portion 20a of the battery housing 20 from the opposite side of the open portion of the battery housing 20 to be electrically connected to the second non-coated portion 12 of the electrode assembly 10. The electrode terminal 50 may penetrate approximately the center of the lower surface of the battery housing 20. The electrode terminal 50 may be electrically connected to the electrode assembly 10 by, for example, coupling to a current collector plate (second current collector plate) 70 coupled to the second non-coated portion 12 or by coupling to a lead tab (not shown) coupled to the second non-coated portion 12. Thus, the electrode terminal 50 has the same polarity as the second electrode of the electrode assembly 10 and may function as a second electrode terminal T2. When the second non-coated portion 12 is a positive non-coated portion, the electrode terminal 50 may function as a positive terminal.

[0125] Considering the polarity and function of the electrode terminal 50, the electrode terminal 50 must be insulated from the battery housing 20 having the opposite polarity. For this purpose, an insulating gasket 54 may be applied between the electrode terminal 50 and the battery housing 20. Alternatively, insulation may be achieved by coating a portion of the surface of the electrode terminal 50 with an insulating material.

[0126] For the same reason, the second uncoated portion 12 and / or the current collector plate (second current collector plate) 70 must be kept insulated from the battery housing 20. For this reason, an insulator 80 may be interposed between the second uncoated portion 12 and the battery housing 20 and / or between the current collector plate (second current collector plate) 70 and the battery housing 20. When the insulator 80 is applied, the electrode terminal 50 may penetrate the insulator 80 for electrical connection with the second uncoated portion 12.

[0127] Meanwhile, in one embodiment of the present invention, the closed portion 20a of the battery housing 20 may function as the first electrode terminal T1. When the first non-coated portion 11 is a negative non-coated portion, the first electrode terminal T1 may be a negative terminal. The cylindrical battery 1 according to one embodiment of the present invention has a structure in which the electrode terminal 50 exposed on the lower surface located opposite to the open portion of the battery housing 20 and the remaining area on the lower surface of the battery housing 20 excluding the area occupied by the electrode terminal 50 can be used as the second electrode terminal T2 and the first electrode terminal T1, respectively. As a result, the cylindrical battery 1 according to one embodiment of the present invention can connect the positive and negative electrodes together in one direction when electrically connecting a plurality of cylindrical batteries 1, simplifying the electrical connection structure. In addition, the cylindrical battery 1 according to one embodiment of the present invention has a structure in which most of the lower surface located opposite to the open portion of the battery housing 20 can be used as an electrode terminal, and therefore has an advantage that a sufficient area can be secured for welding parts for electrical connection.

[0128] Referring to FIG. 15, the current collecting plate (first current collecting plate) 30 according to the embodiment of the present invention may have at least one liquid inlet 32a. The liquid inlet 32a may be provided, for example, in the non-coated portion coupling portion 32. When a plurality of non-coated portion coupling portions 32 are provided, the liquid inlet 32a may be provided in at least one non-coated portion coupling portion 32. The liquid inlet 32a may be provided, for example, on one side or both sides of at least one weld line W formed in the non-coated portion coupling portion 32. Referring to FIG. 5 and FIG. 15, in manufacturing the cylindrical battery 1 according to the embodiment of the present invention, an assembly including the electrode assembly 10 and the current collecting plate 30 (first current collecting plate) may be accommodated in the battery housing 20, and then electrolyte may be injected. In this case, the liquid inlet 32a improves the liquid inlet property.

[0129] 16, the first connecting portion 33b of the first housing coupling part 33 and / or the second connecting portion 34b of the second housing coupling part 34 according to an embodiment of the present invention may have a shape bent once, and may have a shape bent in a direction different from that shown in FIG. 7 and FIG. 14. That is, the first bent portion B1 formed in the first connecting part 33b and / or the second bent portion B2 formed in the second connecting part 34b may have a shape protruding toward the center of the cylindrical battery 1 (see FIG. 5). The bending direction of the first connecting part 33b and / or the second connecting part 34b is to prevent damage to the coupling portion between the current collector plate (first current collector plate) 30 and the electrode assembly 10 and / or the coupling portion between the current collector plate (first current collector plate) 30 and the battery housing 20 during a sizing process. Sizing is a compression process for reducing the height occupied by the beading portion 21 area of ​​the battery housing 20 in order to reduce the total height of the cylindrical battery 1 when manufacturing the cylindrical battery 1. As a result of checking the degree of damage to the welded portion after the sizing process by varying the presence or absence of the bent portions B1, B2 and the protruding directions of the bent portions B1, B2, it was confirmed that almost no damage occurred in the cylindrical battery 1 having a structure in which the bent portions B1, B2 protrude toward the center of the cylindrical battery 1.

[0130] Desirably, the cylindrical battery cell may be, for example, a cylindrical battery cell having a form factor ratio (defined as the diameter divided by the height of the cylindrical battery cell, i.e., the ratio of the diameter Φ to the height H) of greater than about 0.4.

[0131] Here, the form factor refers to a value indicating the diameter and height of a cylindrical battery cell. The cylindrical battery cell according to an embodiment of the present invention may be, for example, a 46110 cell, a 48750 cell, a 48110 cell, a 48800 cell, or a 46800 cell. In the value indicating the form factor, the first two digits indicate the diameter of the cell, the next two digits indicate the height of the cell, and the last digit 0 indicates that the cross section of the cell is circular.

[0132] A battery cell according to one embodiment of the present invention may be a cylindrical battery cell that is approximately cylindrical in shape, with a diameter of approximately 46 mm, a height of approximately 110 mm, and a form factor ratio of approximately 0.418.

[0133] Another embodiment of the battery cell may be a cylindrical battery cell that is approximately cylindrical in shape, with a diameter of about 48 mm, a height of about 75 mm, and a form factor ratio of about 0.640.

[0134] In addition, the battery cell according to another embodiment may be a cylindrical battery cell that is approximately cylindrical, with a diameter of about 48 mm, a height of about 110 mm, and a form factor ratio of about 0.436.

[0135] Additionally, the battery cell according to yet another embodiment may be a cylindrical battery cell that is approximately cylindrical in shape, with a diameter of approximately 48 mm, a height of approximately 80 mm, and a form factor ratio of approximately 0.600.

[0136] In yet another embodiment, the battery cell may be a cylindrical battery cell that is approximately cylindrical in shape, with a diameter of about 46 mm, a height of about 80 mm, and a form factor ratio of about 0.575.

[0137] Conventionally, battery cells having a form factor ratio of about 0.4 or less have been used. That is, conventionally, for example, 18650 cells, 21700 cells, etc. have been used. In the case of an 18650 cell, the diameter is about 18 mm, the height is about 65 mm, and the form factor ratio is about 0.277. In the case of a 21700 cell, the diameter is about 21 mm, the height is about 70 mm, and the form factor ratio is about 0.300.

[0138] 17, a battery pack 3 according to an embodiment of the present invention includes a secondary battery assembly in which a plurality of cylindrical batteries 1 according to an embodiment of the present invention are electrically connected as described above, and a pack housing 2 that accommodates the secondary battery assembly. For ease of illustration, components such as bus bars for electrical connections, a cooling unit, and power terminals have been omitted from the drawings of the present invention.

[0139] 18, an automobile 5 according to an embodiment of the present invention is, for example, an electric automobile, a hybrid automobile, or a plug-in hybrid automobile, and includes a battery pack 3 according to an embodiment of the present invention. The automobile 5 includes a four-wheeled automobile and a two-wheeled automobile. The automobile 5 includes a four-wheeled automobile and a two-wheeled automobile. The automobile 5 operates by receiving power from the battery pack 3 according to an embodiment of the present invention.

[0140] Next, the above-mentioned cylindrical battery 1 will be described in more detail with reference to Figs.

[0141] As described above, a cylindrical battery according to an embodiment of the present invention may include electrode terminals riveted to the bottom surface of the battery housing.

[0142] FIG. 19 is a cross-sectional view showing a riveting structure of an electrode terminal 50 according to an embodiment of the present invention, and FIG. 20 is an enlarged cross-sectional view of a portion circled by a dotted line.

[0143] 19 and 20, the riveting structure of the electrode terminal 50 according to the embodiment may include a cylindrical battery housing 20 having one open side, an electrode terminal 50 riveted through a through hole 23 formed in a closing portion 20a of the battery housing 20, and an insulating gasket 54 interposed between the electrode terminal 50 and the through hole 23.

[0144] The battery housing 20 is made of a conductive metal material. In one example, the battery housing 20 may be made of a steel material, but the present invention is not limited thereto.

[0145] The electrode terminal 50 is made of a conductive metal material. In one example, the electrode terminal 50 may be made of aluminum, but the present invention is not limited thereto.

[0146] The insulating gasket 54 may be made of a polymer resin having insulating properties and elasticity. In one example, the insulating gasket 54 may be made of polypropylene, polybutylene terephthalate, polyfluoroethylene, etc., but the present invention is not limited thereto.

[0147] Desirably, the electrode terminal 50 may include a body portion 50a inserted into the through hole 23, an external flange portion 50b extending along the outer surface from the periphery of one side of the body portion 50a exposed to the outer surface of the closure portion 20a of the battery housing 20, an internal flange portion 50c extending toward the inner surface from the periphery of the other side of the body portion 50a exposed to the inner surface of the closure portion 20a of the battery housing 20, and a flat portion 50d provided on the inside of the internal flange portion 50c.

[0148] Desirably, the flat portion 50d and the inner surface of the closure portion 20a of the battery housing 20 may be parallel to each other, where "parallel" means substantially parallel when observed visually.

[0149] According to one aspect of the present invention, the angle θ between the inner flange portion 50c and the inner surface of the closing portion 20a of the battery housing 20 may be 0° to 60°. The size of the angle is determined according to the crimping strength when the electrode terminal 50 is installed in the through hole 23 of the battery housing 20 by a crimping method. In one example, the angle θ may decrease to 0° as the crimping strength increases. If the angle exceeds 60°, the sealing effect of the insulating gasket 54 may be reduced.

[0150] According to another aspect of the invention, between the inner flange portion 50c and the flat portion 50d dent A section 55 may be provided. dent The portion 55 may have an asymmetric groove cross-sectional configuration. In one example, the asymmetric groove may be substantially V-shaped. The asymmetric groove may include a sidewall 55a of the flat portion 50d and an inclined surface 55b of the inner flange portion 50c connected to an end of the sidewall 55a. The sidewall 55a may be substantially perpendicular to the inner surface of the closure portion 20a of the battery housing 20. By "perpendicular" we mean substantially perpendicular when observed visually. dent The portion 55 is formed by the shape of a crimping jig when the electrode terminal 50 is provided in the through hole 23 of the battery housing 20 by a crimping method.

[0151] Desirably, the thickness of the inner flange portion 50c may decrease as it moves away from the main body portion 50a of the electrode terminal 50.

[0152] In accordance with another aspect of the present invention, the insulating gasket 54 may include an outer gasket 54b interposed between the outer flange portion 50b and an outer surface of the closure portion 20a of the battery housing 20, and an inner gasket 54a interposed between the inner flange portion 50c and an inner surface of the closure portion 20a of the battery housing 20.

[0153] The thickness of the outer gasket 54b and the inner gasket 54a may vary depending on the position. Preferably, the thickness of the inner gasket 54a may be relatively small in a region between the inner edge 24 of the through hole 23 connected to the inner surface of the closure part 20a of the battery housing 20 and the inner flange portion 50c. Preferably, a point of minimum thickness may be present in the gasket region between the inner edge 24 of the through hole 23 and the inner flange portion 50c. In addition, the inner edge 24 of the through hole 23 may include an opposing surface 25 facing the inner flange portion 50c.

[0154] Meanwhile, the upper and lower ends of the inner wall of the through hole 23 perpendicular to the closing portion 20a of the battery housing 20 are chamfered (corner cut) to form a surface that tapers toward the electrode terminal 50. However, the upper and / or lower ends of the inner wall of the through hole 23 may be deformed into a soft curved surface having a curvature. In this case, the stress applied to the gasket 54 near the upper and / or lower ends of the inner wall of the through hole 23 may be further alleviated.

[0155] Desirably, the inner gasket 54a forms an angle of between 0° and 60° with the inner surface of the closure portion 20a of the battery housing 20 and may extend beyond the inner flange portion 50c.

[0156] In addition, the height H1 of the flat portion 50d based on the inner surface of the closing portion 20a of the battery housing 20 may be equal to or greater than the height H2 of the end of the internal gasket 54a. Also, the height H1 of the flat portion 50d based on the inner surface of the closing portion 20a of the battery housing 20 may be equal to or greater than the height H3 of the end of the internal flange portion 50c.

[0157] When the height parameters H1, H2, and H3 satisfy the above conditions, the inner flange portion 50c and the inner gasket 54a can be prevented from interfering with other components.

[0158] Furthermore, a radius R1 from the center of the main body 50a of the electrode terminal 50 to the edge of the external flange portion 50b may be 10 to 60% of a radius R2 of the closing portion 20a of the battery housing 20.

[0159] If R1 is small, there is insufficient welding space when welding an electric wiring component (bus bar) to the electrode terminal 50. Also, if R1 is large, there is less welding space when welding an electric wiring component (bus bar) to the outer surface of the closing part 20a of the battery housing 20 excluding the electrode terminal 50.

[0160] By adjusting the ratio R1 / R2 within the range of 10 to 60%, a welding space between the electrode terminal 50 and the outer surface of the closing portion 20a of the battery housing 20 can be appropriately secured.

[0161] Furthermore, a radius R3 from the center of the main body 50a of the electrode terminal 50 to the edge of the flat portion 50d may be 4 to 30% of a radius R2 of the closing portion 20a of the battery housing 20.

[0162] If R3 is small, when welding a current collecting plate (second current collecting plate) (see reference numeral 70 in FIG. 21) to the flat portion 50d of the electrode terminal 50, the welding space becomes insufficient, the welding area of ​​the electrode terminal 50 decreases, and the contact resistance may increase. In addition, R3 is preferably smaller than R1, and if R3 is large, the thickness of the inner flange portion 50c becomes thin, weakening the force with which the inner flange portion 50c compresses the insulating gasket 54, which may reduce the sealing force of the insulating gasket 54.

[0163] By adjusting R3 / R2 within the range of 4% to 30%, the welding area between the flat portion 50d of the electrode terminal 50 and the current collecting plate (see reference numeral 70 in FIG. 21) can be sufficiently secured, which not only facilitates the welding process but also reduces the contact resistance of the welding area, thereby preventing a decrease in the sealing power of the insulating gasket 54.

[0164] According to an embodiment of the present invention, the riveting structure of the electrode terminal 50 may be formed using a vertically movable crimping jig. First, a preform (not shown) of the electrode terminal 50 is inserted into the through hole 23 formed in the closing portion 20a of the battery housing 20 with an insulating gasket 54 interposed therebetween. The preform refers to the electrode terminal before being riveted.

[0165] Next, a crimping jig is inserted into the inner space of the battery housing 20. The crimping jig has grooves and protrusions corresponding to the final shape of the electrode terminal 50 on the surface facing the preform in order to form the electrode terminal 50 by riveting the preform.

[0166] The crimping jig is then moved downward to pressurize the upper portion of the preform to transform the preform into a riveted electrode terminal 50 .

[0167] While the preform is pressurized by the caulking jig, the outer gasket 54b interposed between the outer flange portion 50b and the outer surface of the closing portion 20a of the battery housing 20 is elastically compressed and its thickness is reduced. Also, the portion of the inner gasket 54a interposed between the inner edge 24 of the through hole 23 and the preform is elastically compressed by the inner flange portion 50c and its thickness is reduced more than other regions. In particular, the region where the thickness of the inner gasket 54a is reduced intensively is the portion indicated by the dotted circle in FIG. 20. As a result, the sealing and hermeticity between the riveted electrode terminal 50 and the battery housing 20 is significantly improved.

[0168] Preferably, the insulating gasket 54 is compressed sufficiently to ensure the desired sealing strength without being physically damaged during the preform riveting process.

[0169] In one example, when the insulating gasket 54 is made of polybutylene terephthalate, it is desirable for the insulating gasket 54 to have a compressibility of 50% or more at the point where it is compressed to its minimum thickness. The compressibility is the ratio of the change in thickness before and after compression to the thickness before compression.

[0170] In another example, when insulating gasket 54 is made of polyfluoroethylene, it is desirable for insulating gasket 54 to have a compressibility of 60% or greater at the point where it is compressed to its minimum thickness.

[0171] As yet another example, when the insulating gasket 54 is made of polypropylene, it is desirable for the insulating gasket 54 to have a compressibility of 60% or greater at the point where it is compressed to its minimum thickness.

[0172] Preferably, the crimping jig is moved up and down at least 12 times to perform the pressure molding of the upper part of the preform in stages. That is, the preform can be deformed in several steps by pressure molding in stages. At this time, the stress applied to the crimping jig can be increased in stages. In this way, the stress applied to the preform can be distributed multiple times, thereby preventing damage to the insulation gasket 54 during the crimping process. In particular, when a portion of the inner gasket 54a interposed between the inner edge 24 of the through hole 23 and the preform is compressed in a concentrated manner by the inner flange portion 50c, damage to the gasket is minimized.

[0173] After the preform is pressed using the crimping jig, the crimping jig is separated from the battery housing 20, and the riveting structure of the electrode terminal 50 according to the embodiment of the present invention is obtained as shown in FIG.

[0174] According to the above-mentioned embodiment, the caulking jig presses the upper part of the preform by moving up and down inside the battery housing 20. In some cases, a rotary jig used in the prior art for pressing the preform may be used.

[0175] However, the rotary rotation jig rotates at a certain angle with respect to the central axis of the battery housing 20. As a result, a rotary rotation jig with a large rotation radius may interfere with the inner wall of the battery housing 20. In addition, if the battery housing 20 is deep, the length of the rotary rotation jig also becomes long. In this case, the rotation radius of the end of the rotary rotation jig becomes large, and the preform may not be properly pressurized. As a result, pressurization using a caulking jig is more effective than a method using a rotary rotation jig.

[0176] 21 is a cross-sectional view of a cylindrical battery 1 according to an embodiment of the present invention cut along a longitudinal direction Y. The overall structure of the cylindrical battery 1 has been described above, but hereinafter, the overall structure of the cylindrical battery 1 will be described from a different perspective than that described above.

[0177] Referring to FIG. 21, a cylindrical battery 1 according to an embodiment includes a jelly roll-type electrode assembly 10 in which sheet-like first and second electrodes are wound with a separator interposed therebetween, with an uncoated portion 11 of the first electrode exposed at the bottom and an uncoated portion 12 of the second electrode exposed at the top.

[0178] In some embodiments, the first electrode may be a negative electrode and the second electrode may be a positive electrode, although the opposite is also possible.

[0179] The method of winding the electrode assembly 10 is substantially the same as the method of winding an electrode assembly used in manufacturing a conventional table-less cylindrical battery described with reference to FIGS.

[0180] In illustrating the electrode assembly 10, only the non-coated portions 11 and 12 that are exposed and extend outside the separator are shown in detail, and the winding structure of the first electrode, the second electrode, and the separator are not shown.

[0181] The cylindrical battery 1 includes a cylindrical battery housing 20 that houses the electrode assembly 10 and is electrically connected to the uncoated portion 11 of the first electrode.

[0182] Preferably, one side (lower part) of the battery housing 20 is open. Also, the closed part 20a of the battery housing 20 has a structure in which the electrode terminal 50 is riveted to the through hole 23 by a crimping process.

[0183] Specifically, the electrode terminal 50 may include a main body portion 50a inserted into the through hole 23, an external flange portion 50b extending along the outer surface from the periphery of one side of the main body portion 50a exposed to the outer surface of the closure portion 20a of the battery housing 20, an internal flange portion 50c extending toward the inner surface from the periphery of the other side of the main body portion 50a exposed to the inner surface of the closure portion 20a of the battery housing 20, and a flat portion 50d provided on the inside of the internal flange portion 50c.

[0184] The cylindrical battery 1 may also include an insulating gasket 54 interposed between the electrode terminal 50 and the through hole 23 .

[0185] Furthermore, the cylindrical battery 1 may include a sealing body that seals the open end of the battery housing 20 to be insulated from the battery housing 20. Desirably, the sealing body may include a cap plate 40 having no polarity and a sealing gasket 60 interposed between the periphery of the cap plate 40 and the open end of the battery housing 20.

[0186] The cap plate 40 may be made of a conductive metal material such as aluminum, steel, nickel, etc., and the sealing gasket 60 may be made of insulating and elastic polypropylene, polybutylene terephthalate, polyfluoroethylene, etc. However, the present invention is not limited by the materials of the cap plate 40 and the sealing gasket 60.

[0187] The cap plate 40 may include a vent portion 41 that ruptures when the pressure inside the battery housing 20 exceeds a critical value. The vent portion 41 may be formed on both sides of the cap plate 40. The vent portion 41 may form a continuous or discontinuous circular pattern, linear pattern, or other pattern on the surface of the cap plate 40.

[0188] The battery housing 20 may include a crimping portion 22 that extends inwardly of the battery housing 20 and is bent to surround and secure a periphery of the cap plate 40 with a sealing gasket 60 to secure the seal.

[0189] The battery housing 20 may also include a beading portion 21 press-fitted into the inside of the battery housing 20 in the area adjacent to the open end. The beading portion 21 supports the edges of the seal, particularly the outer circumferential surface of the sealing gasket 60, when the seal is secured by the crimping portion 22.

[0190] The cylindrical battery 1 may further include a first current collecting plate 30 welded to the uncoated portion 11 of the first electrode. The first current collecting plate 30 is made of a conductive metal material such as aluminum, steel, nickel, etc. Preferably, at least a portion of the edge of the first current collecting plate 30 that does not contact the uncoated portion 11 of the first electrode may be interposed between the beading portion 21 and the sealing gasket 60 and fixed by the crimping portion 22. Alternatively, at least a portion of the end of the first current collecting plate 30 may be fixed to the inner circumferential surface of the beading portion 21 adjacent to the crimping portion 22 by welding.

[0191] The cylindrical battery 1 may also include a second current collector 70 welded to the uncoated portion 12 of the second electrode. Desirably, at least a portion of the second current collector 70, for example, a central portion, may be welded to the flat portion 50d of the electrode terminal 50.

[0192] Preferably, when the second current collector 70 is welded, the welding tool is inserted from the winding center hole C present in the core of the electrode assembly 10 and can reach the welding point of the second current collector 70. In addition, when the second current collector 70 is welded to the flat portion 50d of the electrode terminal 50, the electrode terminal 50 supports the welding area of ​​the second current collector 70, so that strong pressure can be applied to the welding area to improve the welding quality. In addition, since the flat portion 50d of the electrode terminal 50 has a wide area, a wide welding area can be secured. This reduces the contact resistance of the welding area, thereby reducing the internal resistance of the cylindrical battery 1. The surface-to-surface welding structure of the riveted electrode terminal 50 and the second current collector 70 is very useful for rapid charging using a high C-rate current. This is because the current density per unit area in the cross section in the direction of current flow can be reduced, so that the amount of heat generated in the current path can be reduced more than before.

[0193] The flat portion 50d of the electrode terminal 50 may be welded to the second current collecting plate 70 by any one of laser welding, ultrasonic welding, spot welding, and resistance welding. The area of ​​the flat portion 50d may be adjusted differently depending on the welding method, and is preferably 2 mm or more for the sake of weld strength and ease of the welding process.

[0194] For example, when the flat portion 50d and the second current collecting plate 70 are welded by a laser in a continuous or discontinuous line in the form of an arc pattern, the diameter of the flat portion 50d is preferably 4 mm or more. When the diameter of the flat portion 50d satisfies this condition, the welding strength can be ensured, and the welding process can be easily performed by inserting a laser welding tool into the winding center hole C of the electrode assembly 10.

[0195] In another example, when the flat portion 50d and the second current collecting plate 70 are ultrasonically welded in a circular pattern, the diameter of the flat portion 50d is preferably 2 mm or more. When the diameter of the flat portion 50d satisfies this condition, the welding strength can be ensured, and the welding process can be easily performed by inserting an ultrasonic welding tool into the winding center hole C of the electrode assembly 10.

[0196] The cylindrical battery 1 may further include an insulator 80. The insulator 80 may be interposed between the second current collecting plate 70 and the inner surface of the closing portion 20a of the battery housing 20, and between the inner peripheral surface of the side wall of the battery housing 20 and the electrode assembly 10. Desirably, the insulator 80 may include an insulator hole 80a that exposes the flat portion 50d of the electrode terminal 50 to the second current collecting plate 70 side, and may cover the surface of the second current collecting plate 70 and an edge portion of one side (upper portion) of the electrode assembly 10.

[0197] Preferably, the uncoated portions 11, 12 of the first electrode and / or second electrode may be bent from the outer periphery side of the electrode assembly 10 toward the core side to form bent surfaces at the upper and lower parts of the electrode assembly 10. In addition, the first current collecting plate 30 may be welded to the bent surface formed by bending the uncoated portion 11 of the first electrode, and the second current collecting plate 70 may be welded to the bent surface formed by bending the uncoated portion 12 of the second electrode.

[0198] In order to relieve the stress generated when the non-coated portions 11, 12 are folded, the first electrode and / or the second electrode may have an improved structure different from the conventional electrodes (see FIG. 1).

[0199] FIG. 22 is a plan view showing the structure of an electrode 90 according to a preferred embodiment of the present invention.

[0200] Referring to FIG. 22, electrode 90 includes a sheet-like current collector 91 made of a foil of a conductive material, an active material layer 92 formed on at least one surface of current collector 91, and an uncoated portion 93 on the long side end of current collector 91 where no active material is coated.

[0201] Preferably, the non-coated portion 93 may include a plurality of segment pieces 93a that are notched. The plurality of segment pieces 93a may be arranged in a plurality of groups, and the segment pieces 93a belonging to each group may have the same height (length in the Y direction) and / or width (length in the X direction) and / or spacing pitch. The number of segment pieces 93a belonging to each group may be more or less than that shown in the figure. The segment pieces 93a may be trapezoidal, or may be deformed into a rectangle, parallelogram, semicircle, or ellipse.

[0202] Preferably, the height of the segment pieces 93a may increase stepwise from the core side to the outer periphery side. Also, the core-side non-coated portion 93' adjacent to the core side may not include the segment pieces 93a, and the height of the core-side non-coated portion 93' may be smaller than the other non-coated areas.

[0203] Optionally, the electrode 90 may include an insulating coating layer 94 covering the boundary between the active material layer 92 and the non-coated portion 93. The insulating coating layer 94 includes a polymer resin having insulating properties, and may optionally further include an inorganic filler. The insulating coating layer 94 prevents the end of the active material layer 92 from contacting the active material layer of the opposite polarity facing the active material layer 92 via the separator, and serves to structurally support the folding of the segment pieces 93a. For this reason, it is preferable that at least a portion of the insulating coating layer 94 is exposed to the outside from the separator when the electrode 90 is wound into an electrode assembly.

[0204] FIG. 23 is a cross-sectional view taken along a longitudinal direction (Y direction) of an electrode assembly 100 in which a segmented structure of a non-coated portion of an electrode 90 according to an embodiment of the present invention is applied to a first electrode and a second electrode.

[0205] 23, the electrode assembly 100 may be manufactured by the winding method described with reference to Figures 1 and 2. For ease of explanation, the protruding structure of the non-coated portions 11 and 12 extending outward from the separator is shown in detail, and the winding structure of the first electrode, second electrode, and separator is omitted. The non-coated portion 11 protruding downward extends from the first electrode, and the non-coated portion 12 protruding upward extends from the second electrode.

[0206] The pattern in which the height of the non-coated portions 11, 12 varies is illustrated diagrammatically. That is, the height of the non-coated portions 11, 12 may vary irregularly depending on where the cross section is cut. In one example, when a side portion of the trapezoidal segment piece 93a is cut, the height of the non-coated portion in the cross section is lower than the height of the segment piece 93a. It will be understood that the height of the non-coated portions 11, 12 illustrated in the drawings showing the cross section of the electrode assembly 100 corresponds to the average height of the non-coated portions included in each winding turn.

[0207] The non-coated portions 11 and 12 may be folded from the outer periphery of the electrode assembly 100 to the core as shown in FIG. 24. In FIG. 23, the folded portion 101 is indicated by a dotted box. When the non-coated portions 11 and 12 are folded, adjacent segments in the radial direction are overlapped with each other in multiple layers, forming folded surfaces 102 at the upper and lower parts of the electrode assembly 100. In this case, the non-coated portion on the core side (reference numeral 93' in FIG. 22) is not folded due to its low height, and the height h of the segment folded at the innermost side is smaller than or equal to the radial length r of the winding region formed by the non-coated portion 93' on the core side that does not have a segment structure. As a result, the winding center hole C located in the core of the electrode assembly 100 is not blocked by the folded segment. If the winding center hole C is not blocked, the electrolyte injection process is not difficult and the electrolyte injection efficiency is improved. In addition, a welding tool can be inserted through the winding center hole C to easily weld the electrode terminal 50 and the second current collecting plate 70 together.

[0208] In the cylindrical battery 1 according to the embodiment of the present invention, the cap plate 40 of the sealed body does not have a polarity. Instead, since the first current collecting plate 30 is connected to the side wall of the battery housing 20, the outer surface of the closing part 20a of the battery housing 20 has the opposite polarity to the electrode terminal 50. As a result, when connecting multiple cells in series and / or in parallel, wiring such as a bus bar connection can be performed at the top of the cylindrical battery 1 using the outer surface of the closing part 20a of the battery housing 20 and the electrode terminal 50. This increases the number of cells that can be mounted in the same space, improving energy density.

[0209] Hereinafter, an example of a positive electrode active material used in a cylindrical battery according to an embodiment of the present invention will be described.

[0210] In the examples, "primary particles" refers to particle units that do not appear to be particles when observed at a magnification of 5,000 to 20,000 times using a scanning electron microscope or electron backscatter diffraction (EBSD). "Average particle size of primary particles" refers to the arithmetic mean value calculated after measuring the particle sizes of primary particles observed from a scanning electron microscope or EBSD image.

[0211] The term "secondary particle" refers to a particle formed by agglomeration of a plurality of primary particles. In the present invention, a secondary particle formed by agglomeration of 10 or less primary particles is called a pseudo-single particle to distinguish it from a conventional secondary particle formed by agglomeration of tens to hundreds of primary particles.

[0212] In the present invention, the "specific surface area" is measured by the BET method, and specifically, can be calculated from the amount of nitrogen gas adsorption at liquid nitrogen temperature (77K) using a BELSORP-mini II manufactured by BEL Japan.

[0213] In the present invention, "D min ", "D 50 " and "D max" is the particle size value of the volume cumulative distribution of the positive electrode active material measured using the laser diffraction method. min is the size of the smallest particle in the cumulative volume distribution, and D 50 is the particle size when the cumulative volume is 50%, and D max is the maximum particle size shown in the volume cumulative distribution. When the positive electrode active material is a single particle, D 50 means the average particle size of the primary particles. In addition, when the positive electrode active material is a pseudo-single particle, D 50 means the average particle size of particles formed by agglomeration of primary particles.

[0214] The particle size value of the volume cumulative distribution can be measured, for example, by dispersing the positive electrode active material in a dispersion medium, introducing the dispersion into a commercially available laser diffraction particle size measuring device (e.g., Microtrac MT 3000), irradiating the dispersion with ultrasonic waves of about 28 kHz at an output of 60 W, and then obtaining a volume cumulative particle size distribution graph.

[0215] In the present invention, "consist essentially of A" means including the component A and any unmentioned components that do not substantially affect the basic and novel characteristics of the present invention. The basic and novel characteristics of the present 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. A person of ordinary skill in the art would recognize the material effects of such characteristics.

[0216] The present inventors have conducted extensive research to develop a positive electrode for an electrochemical device that has high capacity and excellent safety, and an electrochemical device including the same, and as a result, have found that the safety of a large cylindrical battery can be dramatically improved when a single-particle positive electrode active material consisting of one primary particle or a pseudo-single-particle positive electrode active material consisting of an aggregate of 10 or less primary particles is used alone as a positive electrode active material.

[0217] According to one aspect, the positive electrode includes a positive electrode current collector and a positive electrode active material layer formed on at least one surface of the positive electrode current collector, the positive electrode active material layer including a positive electrode active material and may optionally include a conductive material and / or a binder.

[0218] The positive electrode has a structure in which a positive electrode active material layer is formed on at least one surface or both surfaces of a long sheet-shaped positive electrode current collector, and the positive electrode active material layer may include a positive electrode active material and a binder.

[0219] Specifically, the positive electrode may be manufactured by coating one or both sides of a long sheet-shaped positive electrode current collector with a positive electrode slurry prepared by dispersing a positive electrode active material, a conductive material, and a binder in a solvent such as dimethyl sulfoxide (DMSO), isopropyl alcohol, N-methylpyrrolidone (NMP), acetone, water, etc., and then removing the solvent of the positive electrode slurry through a drying process, followed by rolling. Meanwhile, a positive electrode including a non-coated portion may be manufactured by not coating a portion of the positive electrode current collector, for example, one end of the positive electrode current collector, with the positive electrode slurry when coating the positive electrode slurry.

[0220] In another aspect, the positive electrode active material includes single particle active material particles. In one embodiment, 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, based on 100 wt% of the positive electrode active material. In a specific embodiment, the positive electrode active material may be composed only of the single particle active material particles.

[0221] In this specification, the single particle active material particles are referred to as single particles, pseudo-single particles, or both. The single particles are particles consisting of one primary particle, and the pseudo-single particles are aggregates of 10 or less primary particles.

[0222] Conventionally, it has been common to use spherical secondary particles formed by agglomeration of tens to hundreds of primary particles as the positive electrode active material of a lithium battery. However, in the case of a positive electrode active material in the form of secondary particles formed by agglomeration of a large amount of primary particles, there are problems in that particle cracking occurs easily, in which the primary particles fall off during the rolling process during the manufacture of the positive electrode, and cracks occur inside the particles during charging and discharging. When particle cracking or cracks occur inside the particles of the positive electrode active material, the contact area with the electrolyte increases, and there is a problem in that gas generation due to a side reaction with the electrolyte increases. If gas generation increases inside a cylindrical battery, the pressure inside the battery increases, and there is a risk of battery explosion. In particular, when the volume of a cylindrical battery is increased, the amount of active material inside the battery increases as the volume increases, and therefore the amount of gas generation also increases significantly, further increasing the risk of battery fire and / or explosion.

[0223] In contrast, single-particle active material particles consisting of one primary particle or pseudo-single-particle active material particles consisting of 10 or less primary particles have higher particle strength than conventional positive electrode active material in secondary particle form consisting of tens to hundreds of primary particles, so particle cracking hardly occurs during rolling. In addition, in the case of single-particle active material particles, the number of primary particles constituting the particle is small, so there is little change due to volume expansion and contraction of the primary particles during charging and discharging, and therefore the occurrence of cracks inside the particles is significantly reduced.

[0224] Therefore, when using single particle type active material particles as in an embodiment of the present invention, the amount of gas generation due to particle breakage and internal cracks can be significantly reduced, thereby achieving excellent safety when applied to large cylindrical batteries.

[0225] Meanwhile, the monoparticles and / or quasi-monoparticles are preferably contained in an amount of 95 wt% to 100 wt%, preferably 98 wt% to 100 wt%, more preferably 99 wt% to 100 wt%, and more preferably 100 wt%, based on the weight of the total positive electrode active material contained in the positive electrode.

[0226] When the content of the single particles and / or pseudo-single particles is within the above range, sufficient safety can be obtained when applied to a large battery. When the secondary particle type positive electrode active material is contained in an amount exceeding 5 wt% in the total positive electrode active material, fine powder generated from the secondary particles during electrode manufacturing and charging / discharging increases side reactions with the electrolyte, reducing the gas generation suppression effect, which may reduce the stability improvement effect when applied to a large battery.

[0227] Meanwhile, the positive electrode active material including the single particle and / or the pseudo-single particle according to an embodiment of the present invention is D min may be 1.0 μm or more, 1.1 μm or more, 1.15 μm or more, 1.2 μm or more, 1.25 μm or more, 1.3 μm or more, or 1.5 μm or more. min If the thickness is less than 1.0 μm, the line pressure increases during the rolling process of the positive electrode, which makes it easy for particle cracks to occur, and the thermal stability decreases, making it difficult to ensure sufficient thermal safety when applied to large cylindrical batteries.

[0228] On the other hand, considering the resistance and output characteristics, the D min can be 3 μm or less, 2.5 μm or less, or 2 μm or less. min If is too large, the diffusion distance of lithium ions in the particles increases, and the resistance and output characteristics may decrease.

[0229] For example, D of the positive electrode active material min can be 1.0 μm to 3 μm, 1.0 μm to 2.5 μm, or 1.3 μm to 2.0 μm.

[0230] On the other hand, the positive electrode active material is D 50 It may be 5 μm or less, 4 μm or less, or 3 μm or less, for example, 0.5 μm to 5 μm, desirably 1 μm to 5 μm, and more desirably 2 μm to 5 μm.

[0231] A positive electrode active material in the form of a single particle and / or a pseudo-single particle has a problem that it has poorer lithium mobility than a positive electrode active material in the form of a secondary particle because there are fewer interfaces between primary particles that serve as diffusion paths for lithium ions inside the particle, which increases the resistance. This increase in resistance becomes more severe as the particle size increases, and the increased resistance has a negative effect on the capacity and output characteristics. Therefore, the D 50 By adjusting the particle size to 5 μm or less, the diffusion distance of lithium ions inside the particles of the positive electrode active material can be minimized, thereby suppressing an increase in resistance.

[0232] The positive electrode active material is D max The D of the positive electrode active material may be 12 μm to 17 μm, preferably 12 μm to 16 μm, and more preferably 12 μm to 15 μm. max When the D of the positive electrode active material satisfies the above range, the resistance characteristic and the capacity characteristic are more excellent. max If the D of the positive electrode active material is too large, the agglomeration between the individual particles occurs, and the lithium migration path inside the agglomerated particles becomes longer, which deteriorates the lithium mobility and increases the resistance. max If is too small, the crushing process is excessive, and excessive crushing causes D min The grain size can be as small as less than 1 μm, which can induce grain cracking during rolling and reduce thermal stability.

[0233] Meanwhile, the positive electrode active material may have a particle size distribution (PSD) represented by the following formula (1) of 3 or less, preferably 2 to 3, and more preferably 2.3 to 3. Equation (1): Particle size distribution (PSD) = (D max -D min ) / D 50

[0234] When the positive electrode active material has the above particle size distribution, the electrode density of the positive electrode can be appropriately maintained, and particle cracking and an increase in resistance can be effectively suppressed.

[0235] Meanwhile, the positive electrode active material may have an average particle size of 5 μm or less, 4 μm or less, 3 μm or less, or 2 μm or less. For example, it may be 0.5 μm to 5 μm, preferably 1 μm to 5 μm, and more preferably 2 μm to 5 μm. When the average particle size of the primary particles satisfies the above range, a positive electrode active material in the form of a single particle and / or a pseudo single particle having excellent electrochemical properties may be formed. If the average particle size of the primary particles is too small, the number of agglomerates of the primary particles forming the positive electrode active material increases, and the effect of suppressing particle cracking during rolling is inferior. If the average particle size of the primary particles is too large, the lithium diffusion path inside the primary particles becomes long, increasing the resistance and resulting in inferior output characteristics.

[0236] In one embodiment of the present invention, the positive electrode active material preferably has a unimodal particle size distribution. In the past, in order to improve the electrode density of the positive electrode active material layer, a bimodal positive electrode active material has been used in which a positive electrode active material having a large average particle size and a positive electrode active material having a small average particle size are mixed together. However, in the case of a positive electrode active material having a single particle or pseudo single particle form, as the particle size increases, the lithium migration path becomes longer and the resistance increases significantly, so that when large particle size particles are mixed, a problem of reduced capacity and output characteristics may occur. Therefore, in one embodiment of the present invention, a positive electrode active material having a unimodal distribution is used to minimize the increase in resistance.

[0237] Meanwhile, the positive electrode active material may include a lithium nickel-based oxide. Specifically, the positive electrode active material may include a lithium nickel-based oxide containing 80 mol% or more of Ni with respect to the total moles of transition metals. Preferably, the lithium nickel-based oxide may contain 80 mol% or more and less than 100 mol% of Ni, 82 mol% or more and less than 100 mol%, or 83 mol% or more and less than 100 mol% of Ni. When a lithium nickel-based oxide having a high Ni content is used as described above, a high capacity can be achieved.

[0238] More specifically, the positive electrode active material may include a lithium nickel-based oxide represented by the following Chemical Formula 1: [Chemical formula 1] Li a Ni b Co c M 1 d M 2 e O2 In the above Chemical Formula 1, M 1 can be Mn, Al or a combination thereof, preferably Mn or Mn and Al.

[0239] Said M 2 is at least one selected from the group consisting of Zr, W, Y, Ba, Ca, Ti, Mg, Ta and Nb, preferably at least one selected from the group consisting of Zr, Y, Mg and Ti, more preferably Zr, Y or a combination thereof. 2 Although the elements are not essential, when contained in an appropriate amount, they can play a role in promoting grain growth during firing or improving the stability of the crystal structure.

[0240] The a represents the molar ratio of lithium in the lithium nickel-based oxide, and may be 0.8≦a≦1.2, 0.85≦a≦1.15, or 0.9≦a≦1.2. When the lithium molar ratio satisfies this range, the crystal structure of the lithium nickel-based oxide may be stably formed.

[0241] The b indicates the molar ratio of nickel in all metals except lithium in the lithium nickel-based oxide, and may be 0.8≦b<1, 0.82≦b<1, 0.83≦b<1, 0.85≦b<1, 0.88≦b<1, or 0.90≦b<1. When the nickel molar ratio satisfies the above range, a high energy density is exhibited and a high capacity can be realized.

[0242] Said c represents the molar ratio of cobalt in the total metal excluding lithium in the lithium nickel-based oxide, and can be 0 < c < 0.2, 0 < c < 0.18, 0.01 ≤ c ≤ 0.17, 0.01 ≤ c ≤ 0.15, 0.01 ≤ c ≤ 0.12 or 0.01 ≤ c ≤ 0.10. When the molar ratio of cobalt satisfies the above range, good resistance characteristics and output characteristics can be realized.

[0243] Said d represents the molar ratio of element M in the total metal excluding lithium in the lithium nickel-based oxide, and can be 0 < d < 0.2, 0 < d < 0.18, 0.01 ≤ d ≤ 0.17, 0.01 ≤ d ≤ 0.15, 0.01 ≤ d ≤ 0.12, or 0.01 ≤ d ≤ 0.10. 1 When the molar ratio of element M satisfies the above range, the structural stability of the positive electrode active material is excellently shown. 1 Said e represents the molar ratio of element M in the total metal excluding lithium in the lithium nickel-based oxide, and can be 0 ≤ e ≤ 0.1, or 0 ≤ e ≤ 0.05.

[0244] On the other hand, the positive electrode active material according to an embodiment of the present invention may further include a coating layer containing one or more coating elements selected from the group consisting of Al, Ti, W, B, F, P, Mg, Ni, Co, Fe, Cr, V, Cu, Ca, Zn, Zr, Nb, Mo, Sr, Sb, Bi, Si and S on the surface of the lithium nickel-based oxide particles as required. Desirably, the coating element can be Al, B, Co or a combination thereof. 2 When a coating layer exists on the surface of the lithium nickel-based oxide particles, the contact between the electrolyte and the lithium nickel-based oxide is suppressed by the coating layer, and thus the effect of reducing the elution of transition metals and gas generation due to side reactions with the electrolyte can be achieved.

[0245]

[0246]

[0247] ​​The positive electrode active material may be included in an amount of 80 wt % to 99 wt %, preferably 85 wt % to 99 wt %, and more preferably 90 wt % to 99 wt %, based on the total weight of the positive electrode active material layer.

[0248] Meanwhile, various positive electrode current collectors used in technical fields may be used as the positive electrode current collector. For example, the positive electrode current collector may be stainless steel, aluminum, nickel, titanium, calcined carbon, or aluminum or stainless steel surface-treated with carbon, nickel, titanium, silver, etc. The positive electrode current collector usually has a thickness of 3 μm to 500 μm, and fine irregularities may be formed on the surface of the positive electrode current collector to increase the adhesive strength of the positive electrode active material. The positive electrode current collector may be used in various forms, such as a film, sheet, foil, net, porous body, foam, nonwoven fabric, etc.

[0249] Meanwhile, in one embodiment of the present invention, the single particle active material particles may have a core-shell structure in which the particle surface is coated with a conductive coating layer. The conductive coating layer may cover at least a part of the particle. The conductive coating layer may include a conductive nano-material.

[0250] The single particle active material particles have a problem that they have a higher resistance and a smaller contact area with the conductive material than conventional positive active materials in the form of secondary particles, resulting in poor electrical conductivity. When an excessive amount of conductive material is added to improve electrical conductivity, aggregation occurs in the positive electrode slurry, increasing the viscosity, which leads to poor coating properties. Therefore, in order to achieve smooth coating properties, it is necessary to reduce the solid content to reduce the viscosity of the positive electrode slurry, and if the solid content in the positive electrode slurry is reduced, the content of the active material is reduced, which may result in poor capacity characteristics. In order to solve this problem according to an embodiment of the present invention, the surface of the single particle active material particles is coated with a conductive nanomaterial, thereby achieving excellent electrical conductivity without adding a separate conductive material to the positive electrode slurry.

[0251] In one embodiment of the present invention, when a positive electrode active material in which a conductive nano-material is coated on the particle surface of the single particle active material is used, the positive electrode active material layer does not need to use a conductive material in a portion other than the conductive coating layer. Since there is no need to use a conductive material that induces agglomeration of the positive electrode slurry, the viscosity of the positive electrode slurry can be reduced and the solid content can be increased, and the processability of the electrode coating and the electrode adhesion can be improved.

[0252] In one embodiment of the present invention, the conductive nano-material may be a conductive material having a nano-sized size so as to be smoothly coated on the particles, and the type of the conductive nano-material is not particularly limited. For example, the conductive nano-material may be a carbon nanotube, a carbon nanoparticle, etc.

[0253] The conductive nano-materials may have various shapes, such as spherical, scale-like, or fibrous.

[0254] Meanwhile, the conductive coating layer may be formed by mixing the single particle type active material particles, which are the core part, with the conductive nano material and then heat treating the mixture, whereby the mixing may be performed as a solid phase mixing or a liquid phase mixing.

[0255] In one embodiment of the present invention, the positive electrode active material layer includes flake graphite. When the positive electrode active material layer includes flake graphite in using the single particle active material as the positive electrode active material, the flake graphite provides a slipping effect to the positive electrode active material when the positive electrode active material layer is rolled, thereby improving the rolling characteristics of the electrode and reducing the electrode porosity to a target level. As a result, the stability, initial resistance characteristics, and charge / discharge efficiency of a battery using the positive electrode according to one embodiment of the present invention can be improved.

[0256] In one embodiment of the present invention, the flake graphite may be included in an amount of 0.1 wt % to 5 wt %, preferably 0.1 wt % to 3 wt %, based on 100 wt % of the positive electrode active material layer.

[0257] When the content of flake graphite is within the above range, the rolling characteristics of the positive electrode are improved and excellent electrode density can be achieved. If the content of flake graphite is too low, the effect of improving the rolling characteristics is insignificant, and if the content is too high, it may induce an increase in slurry viscosity and a decrease in phase stability, and the resistance may increase due to a decrease in electrode uniformity caused by binding with the conductive material.

[0258] Meanwhile, the flake graphite used in the present invention may have an average particle size of 1 μm to 20 μm, preferably 2 μm to 10 μm, and more preferably 3 μm to 5 μm, although it is not limited thereto. If the size of the flake graphite is too small, it is difficult to achieve a desired porosity, and the current density may be reduced, resulting in a low capacity. In this case, the average particle size of the flake graphite may be measured by a laser diffraction method (ISO 13320).

[0259] In addition, the aspect ratio of the flake graphite may be 0.1 to 500, preferably 1 to 100, and more preferably 1 to 30. When the aspect ratio of the flake graphite satisfies the above range, the effect of improving the conductivity and reducing the electrode resistance is obtained.

[0260] The flake graphite has a density of 2.0 g / cm 3 ~2.5g / cm 3 , preferably 2.1 g / cm 3 ~2.4g / cm 3 , and more preferably 2.2 g / cm 3 ~2.3g / cm 3 It could be.

[0261] Meanwhile, in one embodiment of the present invention, the porosity of the positive electrode active material layer may be 15% to 23%, preferably 17% to 23%, and more preferably 18% to 23%. When the porosity of the positive electrode active material layer is within the above range, the electrode density is increased, excellent capacity is realized, and resistance is reduced. If the porosity is too low, impregnation of the electrolyte is poor, and lithium deposition due to non-impregnation of the electrolyte may occur, and if the porosity is too high, contact between the electrodes is poor, resistance is increased, energy density is reduced, and the effect of improving capacity is negligible.

[0262] The porosity value of the positive electrode active material layer can be achieved by i) the positive electrode active material including single-particle active material particles, and ii) adding flake graphite to the positive electrode active material.

[0263] When a positive electrode active material in the form of a single particle or quasi-single particle is used in order to realize a high loading electrode having a relatively high loading amount of positive electrode active material, as in one embodiment of the present invention, particle cracking of the active material during rolling is significantly reduced and damage to the positive electrode current collector (aluminum foil) is reduced compared to conventional positive electrode active materials in the form of secondary particles, making it possible to roll at a relatively high linear pressure, and the porosity of the positive electrode active material layer is reduced to the above-mentioned numerical range, thereby increasing the energy density.

[0264] In addition, when the positive electrode active material layer contains flake graphite as in one embodiment of the present invention, the flake graphite provides a slipping effect during rolling and 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 above-mentioned numerical range.

[0265] The positive electrode has a loading of 570 mg / 25 cm 2 More than 600mg / 25cm 2 ~800g / 25m 2 , more preferably 600mg / 25cm 2 ~750mg / 25cm 2 Specifically, in the case of the lithium secondary battery according to an embodiment of the present invention, the rolling characteristics of the electrode are improved by using the single particle and / or quasi-single particle positive electrode active material and flake graphite, so that the loading amount of the positive electrode can be secured at a relatively high level, thereby achieving high capacity characteristics.

[0266] In one embodiment of the present invention, the positive electrode active material layer may further include a conductive material. The conductive material is used to impart electrical conductivity to the electrode, and may be used without any particular limitation as long as it has electronic conductivity without undergoing chemical changes inside the battery. Specific examples include graphite such as natural graphite and artificial graphite; carbon-based materials such as carbon black, acetylene black, ketjen black, channel black, furnace black, lamp black, thermal black, carbon fiber, and carbon nanotubes; metal powder or metal fiber such as copper, nickel, aluminum, and silver; conductive whiskers such as zinc oxide and potassium titanate; conductive metal oxides such as titanium oxide; and conductive polymers such as polyphenylene derivatives, and any one of these may be used alone or in combination. The conductive material may be typically included in an amount of 1 wt% to 30 wt%, preferably 1 wt% to 20 wt%, and more preferably 1 wt% to 10 wt% based on the total weight of the positive electrode active material layer.

[0267] In a specific embodiment of the present invention, the conductive material may include carbon nanotubes.

[0268] In one embodiment of the present invention, the positive active material may include multi-walled carbon nanotubes having a high specific surface area and a small wall number as a conductive material. The multi-walled carbon nanotubes may be included in an amount of 50 wt% or more, 70 wt% or more, 90 wt% or more, or 99 wt% or more based on 100 wt% of the conductive material. In a specific embodiment of the present invention, the conductive material may be composed of the multi-walled carbon nanotubes alone.

[0269] In one embodiment of the present invention, the multi-walled carbon nanotubes have a BET specific surface area of ​​300 m 2 / g~500m 2 To distinguish this from the conventional technology, we call it the "new CNT."

[0270] The carbon nanotubes that were commonly used up until now (conventional CNTs) have a BET specific surface area of ​​300 m 2The scanning electron microscope images and physical properties of the novel CNTs used in the present invention (FIG. 25) and conventional CNTs (FIG. 26) are compared (FIG. 27) as follows.

[0271] As can be seen from the SEM image, the novel CNTs applied in one embodiment of the present invention are of a bundle type and have a multiwall structure, but have a higher BET, a smaller number of walls, and a smaller diameter than conventional CNTs.

[0272] When using a secondary particle type positive electrode active material, sufficient electrical conductivity could be achieved even when using conventional CNTs at a level of 0.4wt% to 0.6wt%. However, in the case of single particle or pseudo single particle positive electrode active materials, the resistance is higher than that of conventional secondary particle type positive electrode active materials, and the contact area with the conductive material is smaller, resulting in poor electrical conductivity. 2 In order to achieve sufficient electrical conductivity using conventional CNTs, which have a conductivity of less than 1.0 wt. / g, the content of the conductive material must be 0.9 wt.% or more.

[0273] 28 to 31 are graphs showing sheet resistance and high-temperature life characteristics for each ratio of conductive material when single particles or pseudo-single particles are used as the positive electrode active material.

[0274] From the graph, it can be seen that when single particles or pseudo single particles are used as the positive active material, the amount of conductive material used should be increased compared to when a conventional positive active material in the form of secondary particles is used.

[0275] However, when the carbon nanotube content is increased to 0.9 wt% or more, aggregation occurs in the positive electrode slurry, increasing the viscosity and resulting in poor coating properties. Therefore, in order to achieve smooth coating properties, it is necessary to reduce the solid content in the positive electrode slurry to lower the viscosity of the positive electrode slurry, but if the solid content in the positive electrode slurry is reduced, the content of the active material is reduced, resulting in poor capacity characteristics.

[0276] As a result of extensive research into solving these problems, the inventors have developed a conductive material having a BET specific surface area of ​​300 m2 together with a positive electrode active material, which is a single-particle active material. 2 / g~500m 2 / g, it was confirmed that sufficient electrical conductivity can be ensured even with a relatively small amount of carbon nanotubes, and therefore the viscosity of the slurry can be maintained low even when the solid content of the positive electrode slurry is high at about 70 wt% to 80 wt%.

[0277] Specifically, the carbon nanotubes used in one embodiment of the present invention have a BET specific surface area of ​​300 m 2 / g~500m 2 / g, preferably 300m 2 / g~450m 2 When the BET specific surface area is in the above range, sufficient electrical conductivity can be ensured even with a small amount of carbon nanotubes.

[0278] The carbon nanotube may be a multi-walled carbon nanotube having a wall number of 2-8, preferably 2-6, and more preferably 3-6.

[0279] The carbon nanotubes may have a diameter of 1 nm to 8 nm, preferably 3 nm to 8 nm, and more preferably 3 nm to 6 nm.

[0280] The carbon nanotubes may be included in an amount of 0.7 wt% or less, preferably 0.3 wt% to 0.7 wt%, and more preferably 0.4 wt% to 0.6 wt%, based on the layer weight of the positive electrode active material layer. When the carbon nanotube content satisfies this range, sufficient electrical conductivity can be achieved and the solid content in the positive electrode slurry can be maintained high, so that the positive electrode active material content in the positive electrode active material layer can be increased, thereby achieving excellent capacity characteristics.

[0281] The table in Figure 32 shows the BET specific surface area of ​​300 m 2 / g~500m 2 / g carbon nanotubes (new CNTs) are used, and the BET is 200m 2 / g or more 300m 2 10 shows a comparison of the solid content and viscosity of the positive electrode slurry and the resistance value of the MP coating layer and the MP interface layer when carbon nanotubes (conventional CNTs) with a solid content of less than 10000 / g are used. From the table, it can be seen that when the new CNTs are used, the viscosity is lower and the electrical conductivity is also excellent even when the solid content of the positive electrode slurry is higher than that of the conventional CNTs.

[0282] The binder serves to improve the adhesion between the positive electrode active material particles and the adhesive strength between the positive electrode active material and the positive electrode current collector. Specific examples include polyvinylidene fluoride (PVDF), vinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HFP), polyvinyl alcohol, polyacrylonitrile, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone, polytetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene monomer rubber (EPDM rubber), sulfonated EPDM, styrene butadiene rubber (SBR), fluororubber, or various copolymers thereof, and one of these may be used alone or a mixture of two or more. The binder may be included in an amount of 1 wt% to 30 wt%, preferably 1 wt% to 20 wt%, more preferably 1 wt% to 10 wt%, based on the total weight of the positive electrode active material layer.

[0283] Yet another aspect of the present invention relates to an electrode assembly including the positive electrode, and a battery including the same. The electrode assembly includes a negative electrode and a positive electrode, and the positive electrode has the structural characteristics as described above.

[0284] The electrode assembly can be laminated, for example, with a separator interposed between the negative electrode and the positive electrode to form a laminated or laminated / folded structure, or can be wound to form a jelly roll structure. When forming a jelly roll structure, a separator can be further disposed on the outside to prevent the negative electrode and the positive electrode from contacting each other.

[0285] The negative electrode includes a negative electrode current collector and a negative electrode active material layer formed on at least one surface of the negative electrode current collector. The negative electrode has a structure in which a negative electrode active material layer is formed on one or both surfaces of a long sheet-like negative electrode current collector, and the negative electrode active material layer may include a negative electrode active material, a conductive material, and a binder.

[0286] Specifically, the negative electrode can be manufactured by applying a negative electrode slurry prepared by dispersing a negative electrode active material, a conductive material, and a binder in a solvent such as dimethyl sulfoxide (DMSO), isopropyl alcohol, N-methylpyrrolidone (NMP), acetone, water, etc. on one or both surfaces of a long sheet-like negative electrode current collector, removing the solvent of the negative electrode slurry by a drying process, and then rolling. When applying the negative electrode slurry, a negative electrode including a non-coated portion can be manufactured by a method of not applying the negative electrode slurry to a partial region of the negative electrode current collector, for example, one end portion of the negative electrode current collector.

[0287] As the negative electrode active material, a compound capable of reversible intercalation and deintercalation of lithium can be used. 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 composites, etc.; lithium metal thin films; metal materials capable of alloying with lithium such as Sn, Al, etc. Any one or a mixture of two or more of these can be used.

[0288] In one embodiment of the present invention, the negative electrode may include a silicon-based negative electrode active material. The silicon-based negative electrode active material is 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), a Si-C composite, or a combination thereof, and preferably SiO y (where 0 < y < 2). Since the silicon-based negative electrode active material has a high theoretical capacity, when the silicon-based negative electrode active material is included, the capacity characteristics can be improved.

[0289] The silicon-based negative electrode active material may be doped with M b a metal, and in this case, the 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 silicon-based negative electrode active material may be Si, SiO y (where 0 < y < 2), a Si-C composite, etc. doped with Mb metal. In the case of a metal-doped silicon-based negative electrode active material, the active material capacity decreases somewhat due to the doping element, but since it has high efficiency, a high energy density can be realized.

[0290] FIG. 56 is a graph showing the change in energy density depending on the content of the silicon-based negative electrode active material and the presence or absence of doping of the silicon-based negative electrode active material in a battery using a mixture of the silicon-based negative electrode active material and the carbon-based negative electrode active material as the negative electrode active material.

[0291] In FIG. 56, low efficiency SiO is undoped SiO, and ultra-high efficiency SiO is Mg / Li doped SiO. From FIG. 56, it can be seen that the energy density is improved as the content of silicon-based negative electrode active material in the entire negative electrode active material increases. In addition, it can be seen that the improvement effect of energy density is more excellent as the ratio of doped silicon-based negative electrode active material in the silicon-based negative electrode active material increases.

[0292] The silicon-based negative active material may further include a carbon coating layer on the particle surface. In this case, the amount of the carbon coating may be 20 wt% or less, preferably 1 to 20 wt%, based on the total weight of the silicon-based negative active material. The carbon coating layer may be formed by a method such as dry coating, wet coating, chemical vapor deposition (CVD), physical vapor deposition (PVD), atomic layer deposition (ALD), etc.

[0293] In one embodiment of the present invention, the silicon-based negative electrode active material may have a capacity of 1,000 to 4,000 mAh / g and an initial efficiency of about 60 to 95%.

[0294] In yet another embodiment of the present invention, the silicon-based negative electrode active material D 50 is 3μm to 8μm, and D min ~D max can be in the range of 0.5 μm to 30 μm.

[0295] The negative electrode may further include a carbon-based negative electrode active material as a negative electrode active material, if necessary. Examples of the carbon-based negative electrode active material include, but are not limited to, artificial graphite, natural graphite, graphite carbon fiber, amorphous carbon, soft carbon, and hard carbon.

[0296] When a mixture of a silicon-based negative electrode active material and a carbon-based negative electrode active material is used as the negative electrode active material, the mixing ratio of the silicon-based negative electrode active material and the carbon-based negative electrode active material may be 1:99 to 20:80 by weight, preferably 1:99 to 15:85, and more preferably 1:99 to 10:90.

[0297] The negative electrode active material may be included in an amount of 80 wt % to 99 wt %, preferably 85 wt % to 99 wt %, and more preferably 90 wt % to 99 wt %, based on the total weight of the negative electrode active material layer.

[0298] If necessary, the negative electrode active material may further include at least one selected from lithium metal and metal materials capable of being alloyed with lithium, such as Sn, Al, and the like.

[0299] The negative electrode current collector may be a negative electrode current collector commonly used in the art, such as copper, stainless steel, aluminum, nickel, titanium, calcined carbon, copper or stainless steel surface-treated with carbon, nickel, titanium, silver, or aluminum-cadmium alloy. The negative electrode current collector usually has a thickness of 3 μm to 500 μm, and like the positive electrode current collector, the surface of the current collector may have fine irregularities to strengthen the binding force of the negative electrode active material. For example, the negative electrode current collector may be used in various forms such as a film, sheet, foil, net, porous body, foam, nonwoven fabric, or the like.

[0300] The conductive material is used to impart electrical conductivity to the negative electrode, and may be used without any particular limitation as long as it has electronic conductivity without inducing chemical changes inside the battery. Specific examples of the conductive material include graphite such as natural graphite and artificial graphite; carbon-based materials such as carbon black, acetylene black, ketjen black, channel black, furnace black, lamp black, thermal black, carbon fiber, and carbon nanotubes; metal powder or metal fiber such as copper, nickel, aluminum, and silver; conductive whiskers such as zinc oxide and potassium titanate; conductive metal oxides such as titanium oxide; and conductive polymers such as polyphenylene derivatives, and one of these may be used alone or in combination. The conductive material may be typically included in an amount of 1 wt% to 30 wt%, preferably 1 wt% to 20 wt%, and more preferably 1 wt% to 10 wt% based on the total weight of the negative electrode active material layer.

[0301] The binder plays a role in improving the adhesion between the negative electrode active material particles and the adhesive strength between the negative electrode active material and the negative electrode current collector. Specific examples of the binder include polyvinylidene fluoride (PVDF), vinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HFP), polyvinyl alcohol, polyacrylonitrile, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone, polytetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene monomer rubber (EPDM rubber), sulfonated EPDM, styrene-butadiene rubber (SBR), fluororubber, and various copolymers thereof, and one of these may be used alone or a mixture of two or more of them. The binder may be included in an amount of 1 wt% to 30 wt%, preferably 1 wt% to 20 wt%, more preferably 1 wt% to 10 wt%, based on the total weight of the negative electrode active material layer.

[0302] The electrode assembly further includes a separator disposed between the negative electrode and the positive electrode, and the separator separates the negative electrode and the positive electrode to provide a path for lithium ions to move. Any separator commonly used as a separator in lithium batteries may be used without any particular limitation.

[0303] The separator may be a porous polymer film, for example, a porous polymer film made of a polyolefin polymer such as an ethylene homopolymer, a propylene homopolymer, an ethylene / butene copolymer, an ethylene / hexene copolymer, or an ethylene / methacrylate copolymer, or a laminate structure of two or more layers thereof. Also, a conventional porous nonwoven fabric, for example, a nonwoven fabric made of a high melting point glass fiber, a polyethylene terephthalate fiber, or the like, may be used. Also, a separator coated with a ceramic component or a polymer material may be used to ensure heat resistance or mechanical strength.

[0304] In yet another aspect, the present invention relates to a battery including the electrode assembly, in which the electrode assembly and an electrolyte are housed in a battery case, and the battery case may be a pouch type, a metal can type, or any other type commonly used in the art, and may be appropriately selected without any particular limitation.

[0305] The electrolyte used in the present invention may be any of various electrolytes that can be used in lithium batteries, such as organic liquid electrolytes, inorganic liquid electrolytes, solid polymer electrolytes, gel-type polymer electrolytes, solid inorganic electrolytes, and molten inorganic electrolytes, and the type of electrolyte is not particularly limited.

[0306] Specifically, the electrolyte may include an organic solvent and a lithium salt.

[0307] The organic solvent can be used without any particular limitation as long as it serves as a medium through which ions involved in the electrochemical reaction of the battery can move. Specifically, the organic solvent can be an ester solvent such as methyl acetate, ethyl acetate, γ-butyrolactone, or ε-caprolactone; an ether solvent such as dibutyl ether or tetrahydrofuran; a ketone solvent such as cyclohexanone; an aromatic hydrocarbon solvent such as benzene or fluorobenzene; dimethylcarbonate (DMC), diethylcarbonate (DEC), methylethylcarbonate (MEC), ethylmethylcarbonate (EMC), ethylene carbonate (EC), or propylene carbonate (propylene carbonate). Examples of the solvents that can be used include carbonate-based solvents such as polycarbonate (PC), alcohol-based solvents such as ethyl alcohol and isopropyl alcohol, nitriles such as R-CN (R is a C2-C20 straight-chain, branched or cyclic hydrocarbon group that may contain an aromatic ring or an ether bond of a double bond), amides such as dimethylformamide, dioxolanes such as 1,3-dioxolane, and sulfolanes. Among these, carbonate-based solvents are preferable, and a mixture of a cyclic carbonate (e.g., ethylene carbonate or propylene carbonate) having high ionic conductivity and high dielectric constant that can improve the charge / discharge performance of the battery and a low viscosity linear carbonate-based compound (e.g., ethyl methyl carbonate, dimethyl carbonate or diethyl carbonate) is more preferable.

[0308] Any compound capable of providing lithium ions used in the lithium salt lithium battery may be used without any particular limitation. Specifically, the lithium salt may 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. The concentration of the lithium salt is preferably within a range of 0.1M to 5.0M, preferably 0.1M to 3.0M. When the concentration of the lithium salt is within the above range, the electrolyte has appropriate conductivity and viscosity, so that the electrolyte exhibits excellent electrolyte performance and the lithium ions can be effectively moved.

[0309] In addition to the electrolyte components, the electrolyte may further include additives for improving the life characteristics of the battery, suppressing the decrease in the battery capacity, and improving the discharge capacity of the battery. For example, the additives may be haloalkylene carbonate compounds such as difluoroethylene carbonate, pyridine, triethyl phosphite, triethanolamine, cyclic ethers, ethylenediamine, n-glyme, hexamethylphosphoric triamide, nitrobenzene derivatives, sulfur, quinoneimine dyes, N-substituted oxazolidinones, N,N-substituted imidazolidines, ethylene glycol dialkyl ethers, ammonium salts, pyrrole, 2-methoxyethanol, or aluminum trichloride, which may be used alone or in combination, but are not limited thereto. The additives may be included in an amount of 0.1 wt% to 10 wt%, preferably 0.1 wt% to 5 wt%, based on the total weight of the electrolyte.

[0310] In yet another embodiment of the present invention, the positive electrode may include a loading reduction portion having a lower loading amount of positive active material than an adjacent region. When the positive electrode has such a structure, the section of the positive active material portion may be increased without the risk of lithium precipitation, thereby improving the energy density of the electrode assembly.

[0311] Recently, development is moving towards increasing battery size to achieve high energy density and reduce costs. As energy increases according to battery size, resistance per battery must be reduced. To reduce resistance, a method of using the electrode current collector as an electrode tab, rather than attaching an electrode tab to the electrode, may be used. In this case, due to the characteristics of the electrode manufacturing process in which electrode slurry is applied to the electrode current collector, a portion where the loading amount is reduced occurs at the boundary between the negative electrode active material portion where the negative electrode slurry is applied and the negative electrode current collector. When the N / P ratio is taken into consideration, there is a risk that metallic lithium will be precipitated at the positive electrode active material portion facing the portion where the loading amount is reduced. Here, the N / P ratio is a value obtained by dividing the negative electrode capacity calculated considering the capacity per area and mass of the negative electrode by the positive electrode capacity calculated considering the capacity per area and mass of the positive electrode, and is usually 1 or more. That is, the capacity of the negative electrode is increased. For reference, if the N / P ratio is not 1, metallic lithium is likely to be precipitated during charging and discharging, which acts as a cause of rapid deterioration of the safety of the battery during high-rate charging and discharging. In other words, the N / P ratio has a significant effect on the safety and capacity of the battery. As described above, due to the risk of metallic lithium precipitation, the positive electrode active material part cannot be positioned in the positive electrode part facing the part where the negative electrode loading amount is reduced. This causes the energy density of the battery to be unable to be increased. Therefore, the present invention improves the energy density by increasing the section of the positive electrode active material part.

[0312] FIG. 52 is a view showing an electrode assembly according to an embodiment of the present invention, and FIG. 53 is a cross-sectional view taken along line AA' in FIG.

[0313] 44 and 45, an electrode assembly 300 according to an embodiment of the present invention includes a negative electrode 400, a positive electrode 500, and a separator 600. The separator 600 is located between the negative electrode 400 and the positive electrode 500. The negative electrode 400, the positive electrode 500, and the separator 600 are wound together to form a jelly roll structure 300S. Here, the jelly roll structure 300S refers to a structure formed by winding the negative electrode 400, the positive electrode 500, and the separator 600. In addition, when the jelly roll structure 300S is formed, it is preferable to further dispose a separator 600 on the outside to prevent the negative electrode 400 and the positive electrode 500 from contacting each other.

[0314] The negative electrode 400 includes a negative electrode current collector 410 and a negative electrode active material part 420 formed by applying a negative electrode active material on the negative electrode current collector 410. In particular, as shown in the figure, both sides of the electrode current collector 410 may be applied with a negative electrode active material to form the negative electrode active material part 420. In addition, a negative electrode uncoated part 430 where the negative electrode active material is not applied in the negative electrode current collector 410 extends in a first direction d1. The negative electrode uncoated part 430 extends along one end of the negative electrode 400 to be wound. In addition, the negative electrode uncoated part 430 extends in the first direction d1 beyond the separator 600. As a result, the negative electrode uncoated part 430 may be exposed at one end of the jelly roll structure 300S in the first direction.

[0315] The positive electrode 500 includes a positive electrode current collector 510 and a positive electrode active material part 520 formed by applying a positive electrode active material on the positive electrode current collector 510. In particular, as shown in the figure, the positive electrode active material may be applied to both sides of the positive electrode current collector 510 to form the positive electrode active material part 520. In addition, a positive electrode uncoated part 530, which is not coated with the positive electrode active material, extends in the second direction d2 in the positive electrode current collector 510. The positive electrode uncoated part 530 extends along one end of the positive electrode 500 to be wound. In addition, the positive electrode uncoated part 530 extends in the second direction d2 beyond the separator 600. As a result, the positive electrode uncoated part 530 may be exposed at one end of the jelly roll structure 300S in the second direction.

[0316] Here, the first direction d1 and the second direction d2 are opposite to each other, and may be parallel to the height direction of the jelly roll structure 300S.

[0317] The electrode assembly 300 according to this embodiment is not a type in which a separate electrode tab is attached, but a type in which the negative electrode uncoated portion 430 of the negative electrode collector 410 and the positive electrode uncoated portion 530 of the positive electrode collector 510 are used as electrode tabs to reduce resistance.

[0318] Although not shown, the negative electrode uncoated portion 430 and / or the positive electrode uncoated portion 530 may have substantially the same structure as the uncoated portion of the electrode described above.

[0319] In one embodiment, the positive electrode active material unit 520 includes a loading reduction portion 500D having a smaller loading amount of positive electrode active material than an adjacent region, and the loading reduction portion 500D is located at one end of the positive electrode 500 in the first direction d1. More specifically, the loading reduction portion 500D may have a gradually decreasing loading amount of the positive electrode active material in the first direction d1.

[0320] Here, the loading amount refers to the amount of active material applied per unit area. In a portion with a large loading amount, a large amount of anode active material or cathode active material may be applied per unit area, and the thickness of the anode active material portion or cathode active material portion may be relatively thick. In a portion with a small loading amount, a small amount of anode active material or cathode active material may be applied per unit area, and the thickness of the anode active material portion or cathode active material portion may be relatively thin.

[0321] When the active material portion is formed by applying a slurry containing an active material, a boundary portion where the loading amount is gradually reduced may be formed between the non-coated portion and the active material portion during this process.

[0322] Specifically, the negative electrode active material part 420 may include a negative electrode boundary part 420B that forms a boundary between the negative electrode active material part 420 and the negative electrode uncoated part 430. The loading amount of the negative electrode boundary part 420B may decrease as it advances toward the negative electrode uncoated part 430.

[0323] Similarly, the positive electrode active material unit 520 may include a positive electrode boundary portion 520B that forms a boundary between the positive electrode active material unit 520 and the positive electrode uncoated portion 530. The loading amount of the positive electrode boundary portion 520B may decrease as it advances toward the positive electrode uncoated portion 530.

[0324] The negative electrode boundary portion 420B and the positive electrode boundary portion 520B, in which the loading amount gradually decreases as described above, are naturally generated in the process of applying the slurry containing the active material to the negative electrode current collector 410 and the positive electrode current collector 510.

[0325] In this case, the amount of the positive electrode active material may be less than the amount of the negative electrode active material in the region corresponding to the positive electrode boundary portion 520B with respect to the direction perpendicular to the second direction d2, since the N / P ratio is greater than 1, and thus problems such as precipitation of metallic lithium do not occur.

[0326] The problem is the region corresponding to the negative electrode boundary 420B. In the region corresponding to the negative electrode boundary 420B, the amount of the negative electrode active material may be less than the amount of the positive electrode active material with respect to the direction perpendicular to the first direction d1. This may cause a problem such as the precipitation of metallic lithium because the N / P ratio is less than 1.

[0327] Therefore, in this embodiment, the positive electrode 500 is provided with a loading reduction portion 500D, and the negative electrode active material portion 420 may be located at a portion corresponding to the loading reduction portion 500D in a direction perpendicular to the first direction d1. More specifically, the negative electrode boundary portion 420B may be located at a portion corresponding to the loading reduction portion 500D in a direction perpendicular to the first direction d1.

[0328] A loading reduction portion 500D having a smaller loading amount of the positive active material than the adjacent area is provided at a position corresponding to the negative electrode boundary portion 420B where the loading amount is gradually reduced, thereby increasing the area where the positive active material is applied without the risk of lithium deposition. In particular, the loading reduction portion 500D may have a shape in which the loading amount of the positive active material gradually decreases as it advances in the first direction d1, corresponding to the shape of the negative electrode boundary portion 420B where the loading amount gradually decreases as it advances toward the negative electrode non-coating portion 430. As a result, the N / P ratio of the negative electrode 400 and the positive electrode 500 in the region where the negative electrode boundary portion 420B is formed can be maintained high, and lithium deposition can be prevented.

[0329] Hereinafter, a method for manufacturing an electrode assembly according to an embodiment of the present invention will be described in detail with reference to FIGS.

[0330] Fig. 46 and Fig. 47 are diagrams showing a process for manufacturing a negative electrode according to one embodiment of the present invention. Specifically, Fig. 46 is a plan view of a negative electrode sheet as viewed from above, and Fig. 47 is a front view of the negative electrode sheet of Fig. 46.

[0331] 46 and 47, a method for manufacturing an electrode assembly according to an embodiment of the present invention includes a step of manufacturing a negative electrode sheet 400S such that a negative electrode active material portion 420 coated with a negative electrode active material and a negative electrode non-coated portion 430 not coated with a negative electrode active material are alternately arranged on a negative electrode current collector 410.

[0332] Specifically, the negative electrode active material may be coated along a third direction d3 to form the negative electrode active material part 420. In addition, the coating region may be spaced apart along a fourth direction d4 perpendicular to the third direction d3, such that the negative electrode active material parts 420 are spaced apart from each other along the fourth direction d4. That is, the coating process may be performed such that the negative electrode non-coated part 430 is located between the negative electrode active material parts 420.

[0333] Here, the third direction d3 and the fourth direction d4 are directions for explanation based on the negative electrode sheet 400S, and are directions unrelated to the first direction d1 and the second direction d2 in the above-mentioned jelly roll structure 300S.

[0334] Thereafter, the negative electrode non-coated portion 430 and the negative electrode active material portion 420 may be slit to manufacture the negative electrode 400. Figure 48 is a perspective view showing a negative electrode according to an embodiment of the present invention.

[0335] 46 to 48, as shown by dotted lines in FIGS. 46 and 47, the negative electrode uncoated portion 430 and the negative electrode active material portion 420 may each be slit in a direction parallel to the third direction d3. As a result, a plurality of negative electrodes 400 as shown in FIG. 48 may be manufactured from the negative electrode sheet 400S. That is, the negative electrode 400 in FIG. 48 is one of a plurality of negative electrodes manufactured by slitting the negative electrode sheet 400S in FIGS. 46 and 47. By slitting the negative electrode uncoated portion 430 and the negative electrode active material portion 420 in the negative electrode sheet 400S, a negative electrode 400 having the negative electrode uncoated portion 430 extending to one side may be manufactured.

[0336] When forming the negative electrode active material part 420, if a slurry containing a negative electrode active material is applied onto the negative electrode current collector 410, a negative electrode boundary part 420B may be formed at the boundary between the negative electrode active material part 420 and the negative electrode uncoated part 430 during the slurry application process, where the loading amount decreases toward the negative electrode uncoated part 430.

[0337] 49 and 50 are diagrams showing a process for manufacturing a positive electrode according to one embodiment of the present invention. Specifically, Fig. 49 is a plan view of a positive electrode sheet as seen from above, and Fig. 50 is a front view of the positive electrode sheet of Fig. 49.

[0338] 49 and 50, a method for manufacturing an electrode assembly according to an embodiment of the present invention includes a step of manufacturing a positive electrode sheet 500S such that positive electrode active material parts 520 coated with a positive electrode active material and positive electrode non-coated parts 530 not coated with a positive electrode active material are alternately arranged on a positive electrode current collector 510.

[0339] Specifically, the positive electrode active material may be applied along a third direction d3 to form the positive electrode active material parts 520. In addition, the application interval may be adjusted along a fourth direction d4 perpendicular to the third direction d3 to position the positive electrode active material parts 520 apart from each other. That is, the application process may be performed such that the positive electrode non-coated parts 530 are positioned between the positive electrode active material parts 520.

[0340] Here, the third direction d3 and the fourth direction d4 are directions for explanation based on the positive electrode sheet 500S, and are directions unrelated to the first direction d1 and the second direction d2 in the above-mentioned jelly roll structure 300S.

[0341] Thereafter, the positive electrode non-coated portion 530 and the positive electrode active material portion 520 may be slit to manufacture the positive electrode 500. Figure 51 is a perspective view showing a positive electrode 500 according to an embodiment of the present invention.

[0342] 49 to 51, as shown by dotted lines in FIGS. 49 and 50, the positive electrode non-coated portion 530 and the positive electrode active material portion 520 may each be slit in a direction parallel to the third direction d3. As a result, a plurality of positive electrodes 500 as shown in FIG. 51 may be manufactured from the positive electrode sheet 500S. That is, the positive electrode 500 in FIG. 51 is one of a plurality of positive electrodes manufactured by slitting the positive electrode sheet 500S in FIGS. 49 and 50. By slitting the positive electrode non-coated portion 530 and the positive electrode active material portion 520 of the positive electrode sheet 500S, a positive electrode 500 having the positive electrode non-coated portion 530 extending to one side may be manufactured.

[0343] When forming the positive electrode active material part 520, a slurry containing a positive electrode active material is applied onto the positive electrode current collector 510. During the application of the slurry, a positive electrode boundary part 520B may be formed at the boundary between the positive electrode active material part 520 and the positive electrode non-coated part 530, in which the loading amount decreases toward the positive electrode non-coated part 530.

[0344] 44, 48, and 51, the manufactured negative electrode 400 and positive electrode 500 may be wound together with the separator 600 to form the jelly roll structure 300S. In this case, in the jelly roll structure 300S, the negative electrode uncoated portion 430 may extend beyond the separator 600 in a first direction d1, and the positive electrode uncoated portion 530 may extend beyond the separator 600 in a second direction d2 opposite to the first direction d1.

[0345] 49 to 51, in a method for manufacturing an electrode assembly according to an embodiment of the present invention, a positive electrode sheet 500S includes a reduced loading region 500DA in which the loading amount of the positive electrode active material is less than that of an adjacent region. A method for forming the reduced loading region 500DA is not particularly limited, and in one example, the reduced loading region 500DA may be formed by adjusting the degree of application of a slurry.

[0346] In the step of manufacturing the positive electrode 500, the loading reduction region 500DA of the positive electrode active material part 520 is slit. The slit loading reduction region 500DA forms a loading reduction part 500D having a lower loading amount of the positive electrode active material than an adjacent area in the jelly roll structure 300S shown in FIGS.

[0347] Specifically, a loading reduction region 500DA is formed in a positive electrode active material unit 520 formed in a positive electrode sheet 500S, in which the loading amount of the positive electrode active material is less than that of adjacent regions. As shown in FIG. 50, the loading reduction region 500DA may be formed in the center of the positive electrode active material unit 520. The loading reduction region 500DA may be configured such that the loading amount of the positive electrode active material gradually decreases toward a central portion 500C of the loading reduction region 500DA. In addition, in the step of manufacturing the positive electrode 500, the loading reduction portion 500D according to this embodiment may be provided by slitting the central portion 500C of the loading reduction region 500DA.

[0348] That is, when applying a slurry containing a positive electrode active material, a loading reduction region 500DA is formed, and a central portion 500C of the loading reduction region 500DA is slit, whereby a plurality of positive electrodes 500 each having a loading reduction portion 500D formed therein can be manufactured.

[0349] Referring to FIG. 51, a loading reduction portion 500D may be provided at one end of the manufactured positive electrode 500, and a positive electrode non-coated portion 530 may be provided at the other end of the positive electrode 500 opposite the one end.

[0350] 44 and 45, when such a positive electrode 500 is wound to form a jelly roll structure 300S, the loading reduction portion 500 may be located at one end of the positive electrode 500 in a first direction d1, and the positive electrode uncoated portion 530 may be located at one end of the positive electrode 500 in a second direction d2.

[0351] In addition, by slitting the central portion 500C of the loading reduction region 500DA, the loading amount of the positive active material may gradually decrease in the loading reduction portion 500D in the first direction d1.

[0352] In addition, in the jelly roll structure 300S, the negative electrode active material part 420 may be located at a portion corresponding to the loading reduction part 500D in a direction perpendicular to the first direction d1. More specifically, in the jelly roll structure 300S, the negative electrode boundary part 420B may be located at a portion corresponding to the loading reduction part 500D in a direction perpendicular to the first direction d1.

[0353] The positional relationship between the loading reduction portion 500D and the negative electrode boundary portion 420B is omitted since it overlaps with the above description.

[0354] Hereinafter, an electrode assembly according to a comparative example of the present invention will be described with reference to FIGS. 52 to 55, and advantages of the electrode assembly according to this embodiment compared to the electrode assembly according to the comparative example will be described.

[0355] Fig. 52 is a diagram showing an electrode assembly according to a comparative example of the present invention, and Fig. 53 is a cross-sectional view taken along line BB' in Fig. 52.

[0356] 52 and 53, an electrode assembly 600 according to a comparative example of the present invention includes a negative electrode 700, a positive electrode 800, and a separator 900, and the negative electrode 700, the positive electrode 800, and the separator 900 are wound to form a jelly roll structure 600S.

[0357] The negative electrode 700 may include a negative electrode current collector 710, a negative electrode active material part 720, and a negative electrode uncoated part 730. In addition, the negative electrode uncoated part 730 extends in a first direction d1, and the negative electrode active material part 720 may include a negative electrode boundary part 720B that forms a boundary between the negative electrode active material part 720 and the negative electrode uncoated part 730 and where the loading amount gradually decreases.

[0358] FIG. 54 is a diagram showing a process for producing a negative electrode 700 according to a comparative example of the present invention.

[0359] Referring to FIG. 54, after a negative electrode sheet 700S is manufactured such that the negative electrode active material parts 720 and the negative electrode uncoated parts 730 are alternately positioned along a fourth direction (d4), the negative electrode uncoated parts 730 and the negative electrode active material parts 720 may be slit to manufacture a plurality of negative electrodes 700.

[0360] 52 and 53, a positive electrode 800 may include a positive electrode current collector 810, a positive electrode active material part 820, and a positive electrode uncoated part 880. In addition, a positive electrode uncoated part 830 extends in a second direction d2 opposite to the first direction d1, and the positive electrode active material part 820 may include a positive electrode boundary part 820B that forms a boundary between the positive electrode active material part 820 and the positive electrode uncoated part 830 and in which the loading amount gradually decreases.

[0361] FIG. 55 is a diagram showing a process for producing a positive electrode 800 according to a comparative example of the present invention.

[0362] Referring to FIG. 55, a positive electrode sheet 800S may be manufactured such that the positive electrode active material parts 820 and the positive electrode uncoated parts 830 are alternately positioned along a fourth direction d4, and then the positive electrode uncoated parts 830 and the positive electrode active material parts 820 may be slit to manufacture a plurality of positive electrodes 800.

[0363] Then, the manufactured anode 700 and cathode 800 are wound together with the separator 900 to manufacture the electrode assembly 600 according to the comparative example of the present invention.

[0364] That is, the electrode assembly 600 according to the comparative example of the present invention may have a similar structure to the electrode assembly 300 according to the present embodiment, except for the loading reducer 500D (see FIG. 49).

[0365] 52 and 53, in the case of the electrode assembly 600 according to this comparative example, the positive electrode active material part 820 cannot be located in a portion corresponding to the negative electrode boundary part 720B with respect to a direction perpendicular to the first direction d1. If the positive electrode active material part 820 extends to a portion corresponding to the negative electrode boundary part 720B, the portion will have a low N / P ratio, and metallic lithium is likely to be precipitated. Therefore, in order to prevent lithium precipitation, it is necessary to limit the length of the positive electrode active material part 820. That is, the positive electrode active material part 820 may be formed only in the region B1 shown in the drawings, and the positive electrode active material part 820 may not be formed in the region B2. As a result, the length of the positive electrode active material part 820 is reduced due to the negative electrode boundary part 720B.

[0366] Meanwhile, referring to FIG. 44 and FIG. 45, in the case of the electrode assembly 300 according to the present embodiment, the positive electrode active material part 520, particularly the loading reduction part 500D, may be located in a portion corresponding to the negative electrode boundary part 420B with respect to a direction perpendicular to the first direction d1. Since the loading reduction part 500D, which has a smaller loading amount of the positive electrode active material than the adjacent area, is provided in a position corresponding to the negative electrode boundary part 420B, the N / P ratio in the corresponding portion may be maintained high, and lithium precipitation may be prevented. Thus, the positive electrode active material part 520 may be formed only in the region A1, and the region A2 where the positive electrode active material part 520 cannot be formed may be reduced. In one example, the height width of the positive electrode 500 relative to the height width of the negative electrode 400 may be increased to 98% or more.

[0367] Comparing the area A1 in Figures 44 and 45 with the area B1 in Figures 52 and 53, the electrode assembly 300 according to this embodiment can have a higher energy density in a limited space than the electrode assembly 600 according to the comparative example because the length of the positive electrode active material portion can be extended by the loading reduction portion 500D.

[0368] Another aspect of the present invention relates to a cylindrical battery including a jelly-roll type electrode assembly having a structure in which a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode are wound in one direction, a cylindrical battery housing in which the electrode assembly is housed, and a battery cap that is a sealing body disposed on the upper part of the battery housing and seals the battery housing. Here, the positive electrode is an embodiment of the present invention, and the positive electrode active material has an average particle diameter D 50 The cylindrical battery may further include an electrolyte, and the above-mentioned content may be referred to regarding the electrolyte.

[0369] The electrode assembly may have a stacked type, a stacked / folded type, or a jelly roll type structure as described above. In a specific embodiment of the present invention, the electrode assembly may have a loading reduction portion in the positive electrode as described above.

[0370] In the case of conventional cylindrical batteries, current is concentrated at the strip-shaped electrode tabs, which results in high resistance, large heat generation, and poor current collection efficiency.

[0371] Recently, as the demand for high-capacity batteries increases with the development of electric vehicle technology, there is a need to develop large cylindrical batteries with a large volume. Conventionally, small cylindrical batteries, i.e., cylindrical batteries with 1865 or 2170 form factors, have a small capacity, so resistance and heat generation do not have much of an effect on battery performance. However, if the specifications of conventional small cylindrical batteries are directly applied to large cylindrical batteries, serious problems may occur in battery safety.

[0372] As the size of a battery increases, the amount of heat and gas generated inside the battery also increases, and the temperature and pressure inside the battery increase due to the heat and gas, which may cause the battery to ignite or explode. In order to prevent this, the heat and gas inside the battery must be properly discharged to the outside, and for this purpose, the cross-sectional area of ​​the battery, which serves as a path for discharging heat to the outside of the battery, must increase according to the increase in volume. However, since the increase in cross-sectional area is usually not as large as the increase in volume, the larger the battery, the greater the amount of heat generated inside the battery, which increases the risk of explosion and reduces the output, etc. In addition, when fast charging at a high voltage, a large amount of heat may be generated around the electrode tab in a short time, which may cause the battery to ignite. Therefore, the present invention provides a cylindrical battery that has a large volume to achieve high capacity and is highly safe.

[0373] In addition, since a high loading electrode using the positive electrode active material in the form of single particle or quasi-single particle can be applied to a cylindrical battery, the initial resistance characteristics and charge / discharge efficiency of the cylindrical battery can be improved.

[0374] The cylindrical battery according to an embodiment of the present invention uses a single particle or pseudo single particle type positive electrode active material to significantly reduce the amount of gas generation compared to the conventional battery. As a result, excellent safety can be achieved even in a large cylindrical battery having a form factor ratio of 0.4 or more.

[0375] The cylindrical battery according to an embodiment of the present invention may be preferably a battery having a tabless structure that does not include electrode tabs, but is not limited thereto.

[0376] The tabless-structured battery may have, for example, a structure in which each of a positive electrode and a negative electrode includes an uncoated portion where no active material layer is formed, a positive electrode uncoated portion and a negative electrode uncoated portion are located at an upper end and a lower end of an electrode assembly, respectively, a current collecting plate is bonded to the positive electrode uncoated portion and the negative electrode uncoated portion, and the current collecting plate is connected to an electrode terminal.

[0377] When a cylindrical battery is formed in a tabless structure as described above, current concentration is less likely to occur compared to a conventional battery with electrode tabs, and heat generation inside the battery can be effectively reduced, thereby improving the thermal safety of the battery.

[0378] The present invention will now be described in more detail with reference to specific examples.

[0379] [Example 1] Average particle size D 50 The positive electrode active material Li[Ni(Ni (0.9 Co 0.06 Mn 0.03 Al 0.01 ]O2: carbon nanotubes: PVDF binder were mixed in a weight ratio of 97.8: 0.6: 1.6 in N-methylpyrrolidone to prepare a positive electrode slurry. The positive electrode slurry was applied to one side of an aluminum current collector sheet, dried at 120°C, and rolled to prepare a positive electrode.

[0380] Anode active material (graphite:SiO = 95:5 weight ratio mixture): conductive material (super C): styrene-butadiene rubber (SBR): carboxymethyl cellulose (CMC) were mixed in water in a weight ratio of 96:2:1.5:0.5 to prepare anode slurry. The anode slurry was applied to one side of a copper current collector sheet, dried at 150°C, and rolled to prepare anode.

[0381] The positive and negative electrodes thus prepared were stacked in the order of separator / positive electrode / separator / negative electrode with a separator interposed between them, and then wound up to prepare a jelly roll type electrode assembly. The electrode assembly thus prepared was placed in a cylindrical battery housing, and an electrolyte was injected to prepare a 4680 cell.

[0382] [Comparative Example 1] Large particle size average particle size D for positive electrode active material 50 The average particle size of the small particles is D 50The Li[Ni 0.9 Co 0.05 Mn 0.04 Al 0.01 A 4680 cell was prepared in the same manner as in Example 1, except that ]O2 was used.

[0383] [Experimental Example 1] The 4680 cells manufactured according to Example 1 and Comparative Example 1 were subjected to a hot box test.

[0384] Specifically, the 4680 cells prepared in Example 1 and Comparative Example 1 were placed in a hot box chamber at room temperature, and the cells were heated to 130°C at a rate of 5°C / min and maintained for 30 minutes to perform a hot box evaluation, and the temperature change of the batteries over time was measured. For accurate evaluation, the hot box evaluation was performed twice for the cell of Example 1. The measurement results are shown in Figures 36 and 37.

[0385] FIG. 36 is a graph showing the hot box test results of the 4680 cell manufactured according to Example 1, and FIG. 37 is a graph showing the hot box test results of the 4680 cell manufactured according to Comparative Example 1.

[0386] 36 and 37, it can be seen that in the case of the lithium secondary battery of Example 1 using the single-particle positive electrode active material, the battery voltage and temperature were maintained stably until 65 minutes had elapsed, whereas in the case of the lithium secondary battery of Comparative Example 1, the battery temperature rose sharply after 35 minutes had elapsed.

[0387] [Example 2-1] It has a unimodal particle size distribution, D min = 1.78 μm, D 50 = 4.23 μm, D max = 13.1 μm, and the positive electrode active material is a mixture of single particles and pseudo-single particles (composition: Li[Ni 0.9 Co 0.06 Mn 0.03 Al0.01 ]O2) was prepared. Fig. 33 is a SEM photograph of the positive electrode active material used in Example 2-1.

[0388] A positive electrode slurry was prepared by mixing the positive electrode active material, carbon nanotubes, and PVDF binder in a weight ratio of 97.8:0.6:1.6 in N-methylpyrrolidone, and the positive electrode slurry was applied to one side of an aluminum current collector sheet, dried at 120° C., and then rolled to prepare a positive electrode.

[0389] Anode active material (graphite:SiO = 95:5 weight ratio mixture): conductive material (Super C): styrene-butadiene rubber (SBR): carboxymethyl cellulose (CMC) were mixed in water in a weight ratio of 96:2:1.5:0.5 to prepare anode slurry. The anode slurry was applied to one side of a copper current collector sheet, dried at 150°C, and rolled to prepare anode.

[0390] The positive and negative electrodes thus prepared were stacked in the order of separator / positive electrode / separator / negative electrode with a separator interposed between them, and then wound up to prepare a jelly roll type electrode assembly. The electrode assembly thus prepared was placed in a battery housing, and an electrolyte was injected to prepare a 4680 cell.

[0391] [Example 2-2] The positive electrode active material has a unimodal particle size distribution and is D min = 1.38 μm, D 50 = 4.69 μm, D max = 18.5 μm, and the positive electrode active material is a mixture of single particles and pseudo-single particles (composition: Li[Ni 0.9 Co 0.06 Mn 0.03 Al 0.01 ]O2) was used. A 4680 cell was manufactured in the same manner as in Example 2-1. Figure 34 is a SEM photograph of the positive electrode active material used in Example 2-2.

[0392] [Comparative Example 2-1] As a positive electrode active material, the average particle size of large particles D 50is 9 μm, and the average particle size of small particles D 50 The positive electrode active material (composition: Li[Ni 0.9 Co 0.05 Mn 0.04 Al 0.01 ]O2) was used, a 4680 cell was manufactured in the same manner as in Example 2-1.

[0393] [Comparative Example 2-2] The positive electrode active material has a unimodal particle size distribution and is D min = 0.892 μm, D 50 = 3.02 μm, D max = 11 μm, and the positive electrode active material is a mixture of single particles and pseudo-single particles (composition: Li[Ni 0.9 Co 0.06 Mn 0.03 Al 0.01 ]O2) was used, a 4680 cell was manufactured in the same manner as in Example 2-1.

[0394] FIG. 35 is an SEM photograph of the positive electrode active material used in Comparative Example 2-2.

[0395] [Experimental Example 2-1] A hot box test was carried out on the 4680 cells manufactured in Examples 2-1 to 2-2 and Comparative Examples 2-1 to 2-2.

[0396] Specifically, the 4680 cells manufactured according to Example 2-1 and Comparative Example 2-1 were placed in a hot box chamber at room temperature, and the temperature was raised to 130°C at a heating rate of 5°C / min and maintained for 30 minutes, after which the temperature change of the battery was measured. If no thermal runaway or ignition occurred during the test, it was indicated as Pass, and if thermal runaway and / or ignition occurred, it was indicated as Fail. In addition, for the accuracy of the test, the cells of Examples 2-1 and 2-2 were tested more than twice.

[0397] The measurement results are shown in Table 1 below and Figures 38 and 39. Figure 34 is a graph showing the hot box test results of the 4680 cells manufactured according to Sample 1 of Example 2-1 and Comparative Example 2-1, and Figure 39 is a graph showing the hot box test results of the 4680 cells manufactured according to Samples 2 and 3 of Example 2-1, Samples 1 and 2 of Example 2-2, and Comparative Example 2-2.

[0398] [Table 1]

[0399] Referring to Table 1, FIG. 38 and FIG. 39, D min In the case of the 4680 cell of Example 2-1, in which a positive electrode active material having a single particle / quasi-single particle form with a particle size of 1.0 μm or more is used, the battery voltage and temperature are stably maintained until 65 minutes have elapsed. In contrast, in the case of Comparative Example 2-1 and Comparative Example D, in which secondary particles are used as the positive electrode active material, min It can be seen that the 4680 cell of Comparative Example 2-2, which uses a positive electrode active material having a single particle / quasi-single particle shape with a particle size of less than 1.0 μm, experienced a rapid rise in battery temperature.

[0400] [Experimental Example 2-2] In order to confirm the degree of particle cracking of the positive electrode active material after rolling of the positive electrodes prepared in Example 2-1 and Comparative Example 2-1, the positive electrodes were cut using an ion milling device and the cross sections were photographed using an SEM. Figure 40 is a SEM cross-sectional image of the positive electrode prepared in Example 2-1, and Figure 41 is a SEM cross-sectional image of the positive electrode prepared in Comparative Example 2-1.

[0401] 40 and 41, the positive electrode of Example 2-1 had almost no particle cracks in the positive electrode active material even after rolling, whereas the positive electrode of Comparative Example 2-2, which used secondary particles, had many particle cracks in the positive electrode active material after rolling.

[0402] [Example 3-1] It has a unimodal particle size distribution, D min = 1.78 μm, D 50 = 4.23 μm, D max= 13.1 μm, and the positive electrode active material powder (composition: Li[Ni 0.9 Co 0.06 Mn 0.03 Al 0.01 ]O2), flake graphite (SFG6L), conductive material (multi-walled carbon nanotubes) and PVDF binder were mixed in N-methylpyrrolidone in a weight ratio of 96.3:1.5:0.4:1.8 to prepare a positive electrode slurry. The positive electrode slurry was applied to one side of an aluminum current collector sheet, dried, and rolled at a linear pressure of 3.0 ton / cm to prepare a positive electrode. The porosity of the positive electrode active material layer of the positive electrode prepared as above was measured and found to be 17.5%.

[0403] [Example 3-2] A positive electrode was prepared in the same manner as in Example 3-1, except that the positive electrode active material, flake graphite, conductive material, and binder were mixed in a weight ratio of 97.2:0.6:0.4:1.8, and the porosity of the positive electrode active material layer was measured. The porosity of the positive electrode active material layer was 19%.

[0404] [Example 3-3] A positive electrode was prepared in the same manner as in Example 3-1, except that the positive electrode active material, the flake graphite, the conductive material, and the binder were mixed in a weight ratio of 97.4:0.4:0.4:1.8, and the porosity of the positive electrode active material layer was measured. The porosity of the positive electrode active material layer was 20%.

[0405] [Example 3-4] A positive electrode was prepared in the same manner as in Example 3-1, except that the positive electrode active material, the flake graphite, the conductive material, and the binder were mixed in a weight ratio of 97.6:0.2:0.4:1.8, and the porosity of the positive electrode active material layer was measured. The porosity of the positive electrode active material layer was 21%.

[0406] [Comparative Example 3-1] A positive electrode was prepared in the same manner as in Example 3-1, except that flake graphite was not added and the positive electrode active material, the conductive material, and the binder were mixed in N-methylpyrrolidone in a weight ratio of 97.8:0.4:1.8 to prepare a positive electrode slurry, and the porosity of the positive electrode active material layer was measured. The porosity of the positive electrode active material layer was 24%.

[0407] [Comparative Example 3-2] A positive electrode was manufactured in the same manner as in Example 3-1, except that flake graphite was not added, and the positive electrode active material, conductive material, and binder were mixed in N-methylpyrrolidone in a weight ratio of 97.8:0.4:1.8 to prepare a positive electrode slurry, which was then rolled at a linear pressure of 2.0 ton / cm. The porosity of the positive electrode active material layer was measured. The porosity of the positive electrode active material layer was 30%.

[0408] [Experimental Example 3-1 (Measurement of charge / discharge capacity and charge / discharge efficiency)] Coin-type half cells including the positive electrodes according to Examples 3-1 to 3-4 and Comparative Examples 3-1 and 3-2 were manufactured, and the charge capacity (mAh / g) and discharge capacity (mAh / g) of each coin-type half cell were measured by charging the cells to 4.25 V at a current of 0.2 C and discharging the cells to 2.5 V at a current of 0.2 C. The measurement results are shown in Table 2 below.

[0409] [Table 2]

[0410] From Table 2, it can be seen that in the cases of Examples 3-1 to 3-4 in which a positive electrode containing flake graphite was used, the porosity was lower than in the cases of Comparative Examples 3-1 and 3-2, and excellent capacity characteristics were exhibited.

[0411] [Experimental Example 3-2 (Confirmation of resistance characteristics)] The resistance characteristics according to SOC were measured while charging the coin-type half-cells including the positive electrodes according to Example 3-3, Comparative Example 3-1, and Comparative Example 3-2 up to 4.2 V. The experimental results are shown in FIG.

[0412] 42, it can be seen that the resistance value of Example 3-3, in which flake graphite was added to the positive electrode active material layer, based on an SOC of 10%, was lower than that of Comparative Examples 3-1 and 3-2, which did not contain flake graphite. This shows that the addition of flake graphite to the positive electrode active material layer has the effect of improving the resistance characteristics at a low SOC.

[0413] [Experimental Example 3-3 (Measurement of high-temperature life characteristics and resistance increase rate)] A separator was interposed between the positive and negative electrodes according to Examples 3-1, 3-3, and Comparative Example 3-1, and the separator / positive electrode / negative electrode were laminated and wound in this order to prepare a jelly roll type electrode assembly. The electrode assembly prepared as above was inserted into a cylindrical battery housing, and an electrolyte was injected to prepare a 4680 cell.

[0414] In this case, the negative electrode was prepared by mixing the negative active material (a mixture of graphite:SiO=95:5 by weight), conductive material (super C), styrene-butadiene rubber (SBR), and carboxymethyl cellulose (CMC) in water in a weight ratio of 96:2:1.5:0.5 to prepare a negative electrode slurry, applying the negative electrode slurry to one side of a copper current collector sheet, drying at 150° C., and rolling the sheet.

[0415] The 4680 cell manufactured as described above was charged at 40° C. at 0.5 C to 4.2 V and then discharged at 0.5 C to 2.5 V (each cycle was counted) for 50 charge / discharge cycles, after which the capacity retention and DCIR increase were measured. The measurement results are shown in FIG.

[0416] Referring to FIG. 43, the secondary batteries of Examples 3-1 and 3-3 showed smaller changes in capacity retention rate with the number of cycles and smaller changes in resistance increase rate with the number of cycles than the secondary battery of Comparative Example 3-1.

[0417] In a cylindrical battery according to an embodiment of the present invention, the positive electrode may be the first electrode and the negative electrode may be the second electrode, or conversely, the positive electrode may be the second electrode and the negative electrode may be the first electrode.

[0418] Although the present invention has been described above with reference to limited embodiments and drawings, it goes without saying that the present invention is not limited thereto, and various modifications and variations can be made by those having ordinary skill in the art to which the present invention pertains within the scope of the technical spirit of the present invention and the scope of the claims. [Explanation of symbols]

[0419] 10 Electrode assembly 11 First Uncoated Section 12 No. 2 non-coated section 20 Battery Housing 20a Closure 21 Beading Section 22 Crimping section 23 Through hole 24 Inner Edge 25 Opposite Surface 30 First current collector 30a Collector plate hole 31 Support part 32 Non-coated joint 32a Liquid injection hole 33 First housing joint 33a 1st contact part 33b 1st connection part 34 Second housing joint 34a 2nd contact part 34b 2nd connection part 40 Cap Plate 41 Vent section 50 electrode terminal 50a Main body 50b External flange part 50c Internal flange 50d flat part 54 Insulating gasket 54a Internal gasket 54b External gasket 55 dent Department 55a Sidewall 55b Slope 60 Sealing gasket 70 Second current collector 80 Insulator 80a Insulator hole 90 electrodes 91 Current collector 92 Active material layer 93 Non-coated section 93' Core side non-coated part 93a segmental piece 94 Insulating coating layer

Claims

1. An electrode assembly including a first electrode having a first coating portion including a first active material layer and a first non-coating portion not including an active material layer, and a second electrode having a second coating portion including a second active material layer and a second non-coating portion not including an active material layer; a battery housing that receives the electrode assembly through an opening formed on one side thereof; a current collector plate including a support portion disposed on one surface of the electrode assembly, a plurality of non-coated portion coupling portions extending from the support portion and coupling to the first non-coated portion, and a plurality of first housing coupling portions extending from the support portion and coupling to an inner surface of the battery housing; A cap plate for covering the opening; an electrode terminal that is riveted through a through hole formed in a closing portion of the battery housing provided on the opposite side of the opening and is electrically connected to the second non-coated portion; an insulating gasket interposed between the electrode terminal and the through hole, The electrode terminal is A main body portion inserted into the through hole; an external flange portion extending from a periphery of one side of the body portion exposed to an outer surface of the closing portion of the battery housing along the outer surface; an inner flange portion extending from a peripheral edge of the other side of the main body portion exposed to the inner surface of the closure portion toward the inner surface in a plan view along the inner surface; a flat portion provided on the inside of the inner flange portion.

2. The first housing coupling portion is 2. The cylindrical battery according to claim 1, wherein the cylindrical battery is coupled to a beading portion of the battery housing.

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

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

5. The first connecting portion is At least one first bent portion; The cylindrical battery according to claim 3 , wherein the cylindrical battery has a folded shape at the first folded portion so as to be contractible and expandable.

6. The current collector plate is 3. The cylindrical battery according to claim 1, further comprising a second housing coupling portion extending from an end of the non-coated portion coupling portion and coupling to an inner surface of the battery housing.

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

8. The second contact portion is 8. The cylindrical battery according to claim 7, wherein at least a portion of the cylindrical battery extends along an inner circumferential surface of the battery housing.

9. The second connecting portion is At least one second bent portion is provided; The cylindrical battery according to claim 7, wherein the cylindrical battery has a folded shape at the second folded portion so as to be contractible and expandable.

10. 3. The cylindrical battery according to claim 1 or 2, characterized in that the inner surfaces of the flat portion and the closing portion are parallel to each other.

11. 3. The cylindrical battery according to claim 1, wherein an angle between the inner flange portion and the inner surface of the closure portion is between 0° and 60°.

12. 3. The cylindrical battery according to claim 1 or 2, characterized in that a recess is provided between the inner flange portion and the flat portion.

13. 13. The cylindrical battery according to claim 12, wherein the recess has a cross-sectional structure of an asymmetric groove with respect to a straight line passing through the center of the recess and parallel to the central axis of the cylindrical battery in a cross section passing through the central axis of the cylindrical battery.

14. 14. The cylindrical battery of claim 13, wherein the asymmetric groove includes a sidewall of the flat portion and a sloping surface of the inner flange portion connected to an end of the sidewall.

15. 15. The cylindrical battery of claim 14, wherein the side wall is perpendicular to the inner surface of the closure.

16. 3. The cylindrical battery according to claim 1, wherein the thickness of the inner flange portion decreases as it gets farther from the main body portion.

17. The insulating gasket is an outer gasket interposed between the outer flange portion and an outer surface of the closure portion; an internal gasket interposed between the internal flange portion and an inner surface of the closure portion; The cylindrical battery according to claim 1 or 2, wherein the inner gasket and the outer gasket have different thicknesses depending on the positions.

18. 18. The cylindrical battery according to claim 17, wherein a thickness of a region of the internal gasket interposed between an inner edge of the through hole connected to an inner surface of the closure portion and the internal flange portion is relatively smaller than that of other regions.

19. The cylindrical battery according to claim 18 , wherein an inner edge of the through hole includes an opposing surface facing the inner flange portion.

20. 18. The cylindrical battery according to claim 17, wherein the internal gasket extends beyond the internal flange portion.

21. 18. The cylindrical battery according to claim 17, wherein the height of the flat portion is greater than or equal to the height of the end of the internal gasket, based on the inner surface of the closure portion.

22. 3. The cylindrical battery according to claim 1, wherein the height of the flat portion relative to the inner surface of the closing portion is greater than or equal to the height of the end of the inner flange portion.

23. the second active material layer includes a positive electrode active material including single particles, pseudo-single particles, or a combination thereof; D is the minimum particle size shown in the volume cumulative distribution of the positive electrode active material ｍｉｎ is 1.0 μm or more, D is the particle size when the volume cumulative amount is 50% in the volume cumulative distribution of the positive electrode active material. ５０ is 5.0 μm or less, D is the maximum particle size shown in the volume cumulative distribution of the positive electrode active material ｍａｘ The cylindrical battery according to claim 1 or 2, wherein the thickness is 12 μm to 17 μm.

24. 24. The cylindrical battery according to claim 23, wherein the positive electrode active material has a unimodal particle size distribution exhibiting a single peak in a volume cumulative particle size distribution graph, and a particle size distribution (PSD) represented by the following formula is 3 or less. Particle size distribution (PSD) = (D ｍａｘ -D ｍｉｎ ) / D ５０

25. The cylindrical battery of claim 23, wherein the monoparticle, quasi-monoparticle, or a combination thereof is included in an amount of 95 wt % to 100 wt % based on the total weight of the positive electrode active material included in the second active material layer.

26. The cylindrical battery according to claim 23 , wherein the positive electrode active material comprises a lithium nickel-based oxide containing 80 mol % or more of Ni based on the total mole number of transition metals.

27. the second active material layer has a porosity of 15% to 23%; 24. The cylindrical battery according to claim 23, wherein the second active material layer contains flake graphite at a weight ratio of 0.05 wt % to 5 wt %.

28. 24. The cylindrical battery of claim 23, wherein the second active material layer further comprises carbon nanotubes.

29. the first active material layer includes a silicon-based negative electrode active material and a carbon-based negative electrode active material, The cylindrical battery of claim 23, wherein the silicon-based negative electrode active material and the carbon-based negative electrode active material are contained in a weight ratio of 1:99 to 20:

80.

30. A plurality of cylindrical batteries according to claim 1 or 2; a pack housing that houses a plurality of the cylindrical batteries.

31. 31. A motor vehicle comprising the battery pack of claim 30.

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