Cylindrical battery, battery pack including the same, and automobile

Abstract

A cylindrical battery according to an embodiment of the present invention includes an electrode assembly in which a first electrode, a second electrode, and a separator interposed between the first electrode and the second electrode are wound. The first electrode and the second electrode each include a first uncoated portion and a second uncoated portion along a winding direction. At least one of the first uncoated portion and the second uncoated portion is defined as an electrode tab and includes a core-side uncoated portion, an outer periphery uncoated portion, and a middle uncoated portion interposed between the core-side uncoated portion and the outer periphery uncoated portion. At least one of the core-side uncoated portion and the outer periphery uncoated portion has a lower height in a winding axial direction than the middle uncoated portion. The cylindrical battery includes a battery housing that accommodates the electrode assembly, a first current collector coupled to the first uncoated portion, a cap plate that covers the opening, a spacer disposed between the cap plate and the electrode assembly to seal the battery housing, and an external terminal that is electrically connected to the second uncoated 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 based on Korean Patent Application No. 10-2021-0142186, filed on October 22, 2021, and the entire contents disclosed in the specification and drawings of that application are incorporated herein by reference. [Background technology]

[0003] In cylindrical batteries, a jelly roll may be used in which positive and negative electrode uncoated regions extend vertically along the height of the battery housing to maximize current collection efficiency. In cylindrical batteries using such a jelly roll, a current collector plate may be used as an intermediate medium for connecting the positive and negative electrode uncoated regions to external terminals and the battery housing, respectively.

[0004] In this case, for example, the positive electrode current collector may be coupled to the positive electrode uncoated portion while covering one side of the jelly roll, and the negative electrode current collector may be coupled to the negative electrode uncoated portion while covering the other side of the jelly roll. Also, the positive electrode current collector may be electrically connected to an external terminal, and the negative electrode current collector may be electrically connected to the battery housing.

[0005] In a cylindrical battery having the above-described structure, a relatively large empty space may be formed between the positive current collector and the cap plate, and also between the negative current collector and the bottom surface of the battery housing opposite the cap plate.

[0006] Such empty spaces can cause the jelly roll to swing up and down inside the battery housing, particularly in the vertical direction of the cylindrical battery. When the jelly roll moves up and down in this manner, damage can occur to the connection between the current collector plate and the electrode tab, as well as to the connection between the current collector plate and the battery housing and the connection between the current collector plate and the external terminal.

[0007] Therefore, it is necessary to minimize the space required for the jelly roll to move. Also, if additional parts are added to reduce the space required for the jelly roll to move, the process becomes more complex and the manufacturing cost increases. Therefore, it is necessary to solve this problem by utilizing parts that have already been used in the past.

[0008] Meanwhile, batteries (secondary batteries) that are highly applicable to each product group, have electrical properties such as high energy density, and can be repeatedly charged and discharged are commonly used not only in portable devices but also in electric vehicles (EVs) and hybrid electric vehicles (HEVs) that are driven by electrical sources.

[0009] Such batteries not only have the primary advantage of dramatically reducing the use of fossil fuels, but are also environmentally friendly as they do not produce any by-products from energy use, and are attracting attention as a new energy source for improving energy efficiency.

[0010] Hereinafter, the term "battery" refers to a secondary battery that can be repeatedly charged and discharged.

[0011] Currently, batteries such as lithium-ion batteries, lithium polymer batteries, nickel-cadmium batteries, nickel-metal hydride batteries, and nickel-zinc batteries are widely used. The operating voltage of a unit battery is approximately 2.5V to 4.5V. Therefore, if a higher output voltage is required, a battery pack is constructed by connecting multiple batteries in series. Alternatively, a battery pack may be constructed by connecting multiple batteries in parallel depending on the required charge / discharge capacity of the battery pack. Therefore, the number of batteries included in the battery pack and the electrical connection configuration can be variously set depending on the required output voltage and / or charge / discharge capacity.

[0012] Meanwhile, known types of unit batteries include cylindrical, prismatic, and pouch-type batteries. In cylindrical batteries, a separator, which is an insulator, is interposed between a positive electrode and a negative electrode, and the separator is wound up to form a jelly-roll-type electrode assembly. This assembly is then inserted into a battery housing to complete the battery. Strip-shaped electrode tabs are connected to the uncoated portions of the positive and negative electrodes, respectively, and the electrode tabs electrically connect the electrode assembly to terminals exposed to the outside. For reference, the positive electrode terminal is a cap plate of a sealing body that seals the opening of the battery housing, and the negative electrode terminal is the battery housing. However, conventional cylindrical batteries with this structure suffer from problems such as high resistance, excessive heat generation, and poor current collection efficiency due to current concentration at the strip-shaped electrode tabs connected to the positive electrode uncoated portion and / or the negative electrode uncoated portion.

[0013] Resistance and heat generation are not major issues with small cylindrical batteries with form factors such as 1865 and 2170. However, when the form factor of cylindrical batteries is increased to be used in electric vehicles, a large amount of heat is generated around the electrode tabs during the fast charging process, which can cause the cylindrical battery to catch fire.

[0014] To solve this problem, a cylindrical battery (so-called tab-less cylindrical battery) has been proposed, which has a structure in which positive and negative electrode uncoated areas are located at the top and bottom of a jelly-roll type electrode assembly, respectively, and current collector plates are welded to these uncoated areas to improve current collection efficiency.

[0015] Figures 1 to 3 show 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 uncoated portion.

[0016] 1 to 3, the positive electrode 10 and the negative electrode 11 have a structure in which an active material 21 is coated on a sheet-shaped current collector 20, and include a plain portion 22 on one long side along the winding direction (X axis).

[0017] The electrode assembly A is fabricated by stacking a positive electrode 10 and a negative electrode 11 together with two separators 12 in order, as shown in Fig. 2, and then winding them in one direction (X-axis direction). At this time, the uncoated portion of the positive electrode 10 and the uncoated portion of the negative electrode 11 are arranged in opposite directions.

[0018] After the winding process, the uncoated portion 10a of the positive electrode 10 and the uncoated portion 11a of the negative electrode 11 are bent toward the core. Thereafter, the current collector plates 30 and 31 are welded to the uncoated portions 10a and 11a, respectively.

[0019] No separate electrode tabs are attached to the positive electrode uncoated region 10a and the negative electrode uncoated region 11a, and current collector plates 30 and 31 are connected to external electrode terminals, forming a current path with a large cross-sectional area along the winding axis direction of electrode assembly A (see arrow), which has the advantage of reducing battery resistance, since resistance is inversely proportional to the cross-sectional area of ​​the path through which current flows.

[0020] In a tabless cylindrical battery, in order to improve the welding characteristics between the uncoated portions 10a, 11a and the current collector plates 30, 31, strong pressure must be applied to the welding points of the uncoated portions 10a, 11a to bend the uncoated portions 10a, 11a as flat as possible.

[0021] However, when the welded points of the non-coated portions 10a, 11a are bent, the patterns of the non-coated portions 10a, 11a may become irregularly distorted and deformed. In this case, the deformed portion may come into contact with an electrode of the opposite polarity, causing an internal short circuit, or microcracks may be formed in the non-coated portions 10a, 11a. Furthermore, as the non-coated portion 32 adjacent to the core of the electrode assembly A is bent, it may block all or a significant portion of the cavity 33 in the core of the electrode assembly A. This creates a problem during the electrolyte injection process. The cavity 33 in the core of the electrode assembly A serves as a passage through which the electrolyte is injected. However, if this passage is blocked, it is difficult to inject the electrolyte. Furthermore, when an electrolyte injector is inserted into the cavity 33, it may interfere with the non-coated portion 32 near the core, causing the non-coated portion 32 to tear.

[0022] In addition, the bent portions of the plain portions 10a and 11a where the current collector plates 30 and 31 are welded must be overlapped with no open spaces (gaps), which ensures sufficient welding strength and prevents the laser from penetrating into the electrode assembly A and melting the separator or active material when using cutting-edge technology such as laser welding.

[0023] In a conventional table-less cylindrical battery, a positive electrode uncoated region 10a is formed over the entire top of the electrode assembly A. Therefore, when the outer periphery of the upper end of the battery housing is pressed inward to form a beading portion, the upper peripheral region 34 of the electrode assembly A is compressed by the battery housing. This compression partially deforms the electrode assembly A, which can cause the separator 12 to break and an internal short circuit. An internal short circuit in the battery can lead to overheating or explosion of the battery.

[0024] On the other hand, when an electrode is manufactured using a cathode active material containing conventional secondary particles, particle cracking occurs, and internal cracks that occur during charging and discharging can increase gas generation, which can lead to problems with battery stability.

[0025] 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, the electrode cracks before the porosity of the electrode reaches a target level, resulting in poor resistance characteristics and charge / discharge efficiency of the lithium secondary battery. Summary of the Invention [Problem to be solved by the invention]

[0026] SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and aims to prevent damage to electrical connections caused by movement of a jelly roll within a battery housing.

[0027] Another object of the present invention is to prevent the movement of a jelly roll by utilizing components that have been conventionally applied in the manufacture of cylindrical batteries, thereby preventing the complication of the manufacturing process and the increase in manufacturing costs that would occur due to the application of additional components.

[0028] Another object of the present invention is to provide an electrode assembly having an improved uncoated portion structure that can reduce stress applied to the uncoated portions exposed at both ends of the electrode assembly when the uncoated portions are bent.

[0029] It is yet another object of the present invention to provide an electrode assembly in which the electrolyte injection passage is not blocked even when the non-coating portion is folded.

[0030] Another object of the present invention is to provide an electrode assembly including a structure capable of preventing contact between the periphery of the upper end of the electrode assembly and the inner surface of the battery housing when the upper end of the battery housing is beaded.

[0031] Another object of the present invention is to provide an electrode assembly having improved energy density and reduced resistance.

[0032] It is yet another object of the present invention to provide a cylindrical battery including an electrode assembly of an improved structure, a battery pack including the same, and a vehicle including the battery pack.

[0033] Another object of the present invention is to provide an electrode for an electrochemical device that can achieve excellent thermal stability by using single particles or pseudo-single particles as a positive electrode active material, and has high electrical conductivity and excellent rolling characteristics, and an electrode assembly for an electrochemical device including the same.

[0034] Another object of the present invention is to provide an electrode assembly with improved energy density by using a silicon-based negative electrode active material in the negative electrode.

[0035] Another object of the present invention is to provide an electrode assembly in which the section of the positive electrode active material portion is increased without the risk of lithium deposition.

[0036] Another object of the present invention is to provide a cylindrical battery that can exhibit excellent thermal stability even when its volume is increased.

[0037] The technical problems that the present invention aims to solve are not limited to the above-mentioned problems, and other problems will be clearly understood by those skilled in the art from the following description of the invention. [Means for solving the problem]

[0038] To solve the above-mentioned problems, a cylindrical battery according to one aspect of the present invention includes an electrode assembly in which a core and an outer circumferential surface are defined by winding a first electrode, a second electrode, and a separator interposed between the first electrode and the second electrode around a winding shaft.

[0039] The first electrode and the second electrode each include a first uncoated portion and a second uncoated portion along the winding direction where an active material layer is not coated.

[0040] At least one of the first uncoated portion and the second uncoated portion is defined as an electrode tab, and includes a core-side uncoated portion adjacent to the core of the electrode assembly, an outer-side uncoated portion adjacent to the outer surface of the electrode assembly, and an intermediate uncoated portion interposed between the core-side uncoated portion and the outer-side uncoated portion, and at least one of the core-side uncoated portion and the outer-side uncoated portion has a relatively lower height in the winding axis direction than the intermediate uncoated portion.

[0041] The cylindrical battery includes a battery housing that receives the electrode assembly through an opening formed at a bottom end thereof, a first current collecting plate that is coupled to the first uncoated portion and positioned within the battery housing, a cap plate that covers the opening, a spacer that is disposed between the cap plate and the electrode assembly to fix the electrode assembly and seal the battery housing, and an external terminal that is electrically connected to the second uncoated portion.

[0042] The spacer may include a movement prevention portion interposed between the first current collecting plate and the cap plate, a sealing portion interposed between the battery housing and the cap plate, and a connecting portion connecting the movement prevention portion and the sealing portion.

[0043] The movement prevention portion may have a height corresponding to the distance between the first current collecting plate and the cap plate.

[0044] The movement prevention portion may be located at the center of an end portion of the electrode assembly in the winding axis direction.

[0045] The movement prevention portion may include a spacer hole formed at a position corresponding to a winding center hole of the electrode assembly.

[0046] The sealing portion may extend along an inner circumferential surface of the battery housing.

[0047] The battery housing may include a beading portion formed by pressing around an outer periphery, and a crimping portion whose end defining the opening below the beading portion extends and is bent to wrap around the periphery of the cap plate.

[0048] The sealing portion may be bent along the crimping portion to enclose the periphery of the cap plate.

[0049] The linkage may include a plurality of extension legs extending from the motion prevention portion in a radial, cross-like, or combination thereof configuration.

[0050] The extension legs may be configured to not contact the cap plate.

[0051] The first current collector plate may include a support portion located at the center of an end portion of the electrode assembly in the winding axis direction, a non-coating portion coupling portion extending from the support portion and coupled to the first non-coating portion, and a housing contact portion extending from the support portion or from an end portion of the non-coating portion coupling portion and interposed between the battery housing and the sealing portion.

[0052] The housing contact portion may contact one surface of the beading portion facing the cap plate.

[0053] The sealing portion may be configured to be bent along the crimping portion to enclose a periphery of the cap plate and fill a gap between the housing contact portion and the cap plate.

[0054] The cap plate may be configured to be non-polarizable.

[0055] The movement prevention portion may cover the support portion so that the support portion is not exposed to the outside of the movement prevention portion.

[0056] The connecting portion may be positioned so as not to overlap the housing contact portion along the winding axis direction.

[0057] The cylindrical battery may further include a second current collecting plate coupled to the second uncoated portion, and an insulator interposed between a closing portion formed at an upper end of the battery housing and the second current collecting plate.

[0058] The external terminal may be electrically connected to the second uncoated portion through the insulator.

[0059] The external terminal may be a rivet terminal that is insulatively attached to a through hole formed in the center of the closing portion and has a peripheral edge of the end opposite the second plain portion riveted toward the inner surface of the closing portion.

[0060] The end of the external terminal may be welded to the second current collector plate.

[0061] At least a portion of the intermediate plain portion may include a plurality of independently foldable segments.

[0062] At least one of the height in the winding axis direction and the width in the winding direction of the plurality of segments may increase stepwise from the core side to the outer periphery side, individually or for each group.

[0063] The plurality of segments form a plurality of segment groups from the core side toward the outer periphery, and segments belonging to the same segment group may have at least one of the width in the winding direction, the height in the winding axial direction, and the spacing pitch in the winding direction that is the same as each other.

[0064] The segments belonging to the same segment group may have at least one of a width in the winding direction, a height in the winding axial direction, and a spacing pitch in the winding direction that increases stepwise from the core side to the outer periphery side.

[0065] The plurality of split pieces may be folded toward the core and overlap each other along the winding axis direction.

[0066] The length R of the core-side uncoated portion in the radial direction and the bent length H of the innermost segment of the intermediate uncoated portion can satisfy the relation "H≦R".

[0067] A gap may be provided between the lower end of the cutting line of the divided piece and the active material layer.

[0068] The first electrode may include a first sliding portion where the thickness of the active material layer is reduced in a boundary region between the ground portion and the uncoated portion, and the second electrode may include a second sliding portion where the thickness of the active material layer is reduced in a boundary region between the ground portion and the uncoated portion, the first sliding portion and the second sliding portion being positioned in opposite directions in the winding axis direction.

[0069] The ground portion of the first electrode may include a loading reduction portion where a loading amount of the active material is reduced, and a position of the loading reduction portion may correspond to a position of the second sliding portion.

[0070] The active material layer of the first electrode may include a positive electrode active material including single particles, quasi-single particles, or a combination thereof.

[0071] The minimum particle size D appearing in the volume cumulative distribution of the positive electrode active material min can be 1.0 μm or greater.

[0072] The particle size D when the volume cumulative amount is 50% in the volume cumulative distribution of the positive electrode active material 50 can be 5.0 μm or less.

[0073] The maximum particle size D appearing in the volume cumulative distribution of the positive electrode active material max can be 12 μm to 17 μm.

[0074] The positive electrode active material may have a unimodal particle size distribution in which a single peak appears in a volume cumulative particle size distribution graph, and a particle size distribution (PSD) represented by the following Equation 1 may be 3 or less:

[0075] [Formula 1] Particle size distribution (PSD)=(D max -D min ) / D 50

[0076] The single particles, quasi-single particles, 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 first electrode.

[0077] The positive electrode active material may include a lithium nickel-based oxide containing 80 mol % or more of Ni based on the total number of moles of transition metals.

[0078] The active material layer of the first electrode may have a porosity of 15% to 23%.

[0079] The active material layer of the first electrode may contain flake graphite at a weight ratio of 0.05 wt % to 5 wt %.

[0080] The active material layer of the first electrode may further include carbon nanotubes (CNTs).

[0081] The active material layer of the second electrode may include a silicon-based negative electrode active material and a carbon-based negative electrode active material.

[0082] The silicon-based negative electrode active material and the carbon-based negative electrode active material may be contained in the active material layer of the second electrode in a weight ratio of 1:99 to 20:80.

[0083] A battery pack according to another aspect of the present invention includes a plurality of cylindrical batteries having at least one of the above-described features, and a pack housing that houses the batteries.

[0084] A motor vehicle according to yet another aspect of the present invention includes the battery pack described above. [Effects of the Invention]

[0085] According to one aspect of the present invention, movement of the jelly roll within the battery housing is minimized to prevent damage to electrical connections.

[0086] According to one aspect of the present invention, instead of applying additional parts to prevent the jelly roll from moving, conventionally applied parts are utilized, thereby preventing the manufacturing process from becoming complicated and the manufacturing costs from increasing.

[0087] In addition, according to one aspect of the present invention, the uncoated portions protruding from the upper and lower sides of the electrode assembly themselves are used as electrode tabs, thereby reducing the internal resistance of the battery and increasing the energy density.

[0088] In addition, according to one aspect of the present invention, by improving the structure of the uncoated portion of the electrode assembly, interference between the electrode assembly and the inner surface of the battery housing does not occur during the process of forming the beading portion of the battery housing, thereby preventing internal short circuits in cylindrical batteries due to partial deformation of the electrode assembly.

[0089] In addition, according to one aspect of the present invention, by improving the structure of the uncoated portion of the electrode assembly, it is possible to prevent the uncoated portion from tearing when being bent, and to sufficiently increase the number of overlapping layers of the uncoated portion, thereby improving the welding strength.

[0090] In addition, according to one aspect of the present invention, by improving the structure of the uncoated portion adjacent to the core of the electrode assembly, it is possible to prevent the cavity in the core of the electrode assembly from being blocked when the uncoated portion is bent, and it is possible to easily perform the electrolyte injection process and the welding process of the battery housing and the current collector plate.

[0091] According to another aspect of the present invention, a cylindrical battery having a structure in which internal resistance is low, internal short circuits are prevented, and welding strength between the current collector plate and the uncoated portion is improved, and a battery pack and a vehicle including the same can be provided.

[0092] According to another aspect of the present invention, D minBy incorporating a positive electrode active material powder having a particle size of 1.0 μm or more into the positive electrode, the thermal stability of the battery can be further improved. Research by the present inventors has confirmed that even when single particles and / or pseudo-single particles are used as the positive electrode active material, the effects of suppressing particle breakage after rolling and improving thermal stability vary depending on the particle size of the positive electrode active material powder. In particular, when particles with a particle size of less than 1.0 μm are included in the positive electrode active material powder, the increase in linear pressure during the rolling process increases particle cracking, reducing thermal stability, and making it impossible to ensure sufficient thermal stability when applied to large cylindrical batteries. Therefore, in the present invention, a minimum particle size D min By using positive electrode active material powder with particle size controlled to 1.0 μm or more, the thermal stability improvement effect can be maximized.

[0093] According to another aspect of the present invention, D 50 , D max By incorporating positive electrode active material powder with an appropriately controlled particle size distribution (PSD) into the positive electrode, the increase in resistance due to the application of single particles can be minimized, thereby achieving excellent capacity and output characteristics.

[0094] Furthermore, according to one aspect of the present invention, the conductivity of the electrode can be improved by including a single-particle positive electrode active material coated with a conductive coating layer or by including the novel CNT as a conductive material.

[0095] In addition, according to one aspect of the present invention, since the positive electrode active material layer contains flake graphite, when the positive electrode active material layer is rolled, the flake graphite provides a sliding effect to the positive electrode active material, improving the rolling characteristics of the electrode and reducing the electrode porosity to a target level, thereby improving the stability, initial resistance characteristics, and charge / discharge efficiency of the cylindrical battery.

[0096] Furthermore, according to one embodiment of the present invention, a silicon-based negative electrode active material with a large capacity is contained in the negative electrode, whereby a higher energy density can be achieved.

[0097] Furthermore, according to one aspect of the present invention, since the positive electrode includes a reduced loading portion where the loading amount of the positive electrode active material is small, the section of the positive electrode active material portion can be increased without worrying about lithium deposition.

[0098] Furthermore, according to one aspect of the present invention, the internal heat generation of the battery can be effectively reduced compared to conventional batteries with strip-shaped electrode tabs, thereby improving the thermal stability of the battery.

[0099] The present invention also provides various other effects, which will be described later with reference to the embodiments, but explanations of effects that can be easily inferred by ordinary skilled artisans will be omitted.

[0100] 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 concept of the present invention. Therefore, the present invention should not be interpreted as being limited to only the matters described in the drawings. [Brief explanation of the drawings]

[0101] [Figure 1] 1 is a plan view showing the structure of an electrode used in manufacturing a conventional tabless cylindrical battery. [Figure 2] 1 is a diagram showing the electrode winding process of a conventional tabless cylindrical battery. [Figure 3] 10A and 10B are diagrams illustrating a process of welding a current collector plate to a bent surface of a non-coating portion in a conventional tabless cylindrical battery. [Figure 4] 1 is a perspective view showing the appearance of a cylindrical battery according to an embodiment of the present invention; [Figure 5] 1 is a cross-sectional view showing the internal structure of a cylindrical battery according to an embodiment of the present invention. [Figure 6] 1 is a perspective view showing a current collecting plate according to an embodiment of the present invention; [Figure 7] 1 is a partial cross-sectional view showing an area where an integrated spacer is applied according to an embodiment of the present invention; [Figure 8] FIG. 1 is a perspective view of a one-piece spacer according to one embodiment of the present invention. [Figure 9] FIG. 2 is a bottom view of a cylindrical battery according to one embodiment of the present invention. [Figure 10] 1 is a partial cross-sectional view showing an area where an insulator is applied according to an embodiment of the present invention. [Figure 11] 2 is a partial cross-sectional view schematically illustrating a coupling structure between an electrode assembly and a current collector plate according to an embodiment of the present invention; [Figure 12] 1 is a schematic diagram illustrating a battery pack according to an embodiment of the present invention. [Figure 13] 1 is a schematic diagram illustrating a vehicle according to an embodiment of the present invention; [Figure 14] FIG. 1 is a plan view showing the structure of an electrode according to a first embodiment of the present invention. [Figure 15] FIG. 10 is a plan view showing the structure of an electrode according to a second embodiment of the present invention. [Figure 16] FIG. 10 is a plan view showing the structure of an electrode according to a third embodiment of the present invention. [Figure 17] FIG. 10 is a plan view showing the structure of an electrode according to a fourth embodiment of the present invention. [Figure 18] 10 is a diagram illustrating definitions of width, height, and spacing pitch of segments according to an embodiment of the present invention. [Figure 19] FIG. 10 is a plan view showing the structure of an electrode according to a fifth embodiment of the present invention. [Figure 20] 10 is a diagram illustrating definitions of width, height, and spacing pitch of segments according to another embodiment of the present invention. [Figure 21] FIG. 1 is a cross-sectional view of a jelly-roll type electrode assembly in which the electrodes of the first embodiment are applied to a first electrode (positive electrode) and a second electrode (negative electrode), taken along the Y-axis direction (winding axis direction). [Figure 22] FIG. 10 is a cross-sectional view of a jelly-roll type electrode assembly in which the electrodes of the second embodiment are applied to a first electrode (positive electrode) and a second electrode (negative electrode), taken along the Y-axis direction (winding axis direction). [Figure 23]FIG. 10 is a cross-sectional view of a jelly-roll type electrode assembly in which any one of the electrodes of the third to fifth embodiments (modifications thereof) is used as the first electrode (positive electrode) and the second electrode (negative electrode) taken along the Y-axis direction (winding axis direction). [Figure 24] 10 is a cross-sectional view of an electrode assembly according to yet another embodiment of the present invention, taken along the Y-axis direction (winding axis direction). [Figure 25] 10 is a cross-sectional view of an electrode assembly according to yet another embodiment of the present invention, taken along the Y-axis direction (winding axis direction). [Figure 26] 10 is a cross-sectional view of an electrode assembly according to yet another embodiment of the present invention, taken along the Y-axis direction (winding axis direction). [Figure 27] 1 is a cross-sectional view of a cylindrical battery according to an embodiment of the present invention taken along the Y-axis direction. [Figure 28] 4 is a cross-sectional view of a cylindrical battery according to another embodiment of the present invention taken along the Y-axis direction. FIG. [Figure 29] 10 is a cross-sectional view of a cylindrical battery according to yet another embodiment of the present invention, taken along the Y-axis direction. [Figure 30] 10 is a cross-sectional view of a cylindrical battery according to yet another embodiment of the present invention, taken along the Y-axis direction. [Figure 31] 10 is a cross-sectional view of a cylindrical battery according to yet another embodiment of the present invention, taken along the Y-axis direction. [Figure 32] 10 is a cross-sectional view of a cylindrical battery according to yet another embodiment of the present invention, taken along the Y-axis direction. [Figure 33] 10 is a cross-sectional view of a cylindrical battery according to yet another embodiment of the present invention, taken along the Y-axis direction. [Figure 34] 10 is a cross-sectional view of a cylindrical battery according to yet another embodiment of the present invention, taken along the Y-axis direction. [Figure 35] 10 is a cross-sectional view of a cylindrical battery according to yet another embodiment of the present invention, taken along the Y-axis direction. [Figure 36]1 is a scanning electron microscope (SEM) photograph of a novel CNT according to one embodiment of the present invention. [Figure 37] This is a scanning electron microscope (SEM) photograph of a commonly used conventional carbon nanotube (conventional CNT). [Figure 38] 1 is a table comparing the physical properties of conventional CNTs and the physical properties of new CNTs. [Figure 39] 10 is a graph showing the surface resistance depending on the ratio of the conductive material when single-particle active material particles are used as the positive electrode active material. [Figure 40] 10 is a graph showing high-temperature life characteristics depending on the ratio of conductive material when single-particle active material particles are used as the positive electrode active material. [Figure 41] 10 is a graph showing high-temperature life characteristics depending on the ratio of conductive material when single-particle active material particles are used as the positive electrode active material. [Figure 42] 10 is a graph showing high-temperature life characteristics depending on the ratio of conductive material when single-particle active material particles are used as the positive electrode active material. [Figure 43] 10 is a table comparing the solid content and viscosity of the positive electrode slurry, the resistance value in the MP coating layer, and the resistance value in 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 specific surface area of ​​200 m2 / g or more and less than 300 m2 / g are used. [Figure 44a] 2 is a SEM photograph of the positive electrode active material used in Example 2-1 of the present invention. [Figure 44b] 2 is a SEM photograph of the positive electrode active material used in Example 2-2 of the present invention. [Figure 44c] 1 is a SEM photograph of the positive electrode active material used in Comparative Example 2-2 of the present invention. [Figure 45a] 1 is a graph showing the results of a hot box test on a 4680 cell manufactured according to Example 1 of the present invention. [Figure 45b] 1 is a graph showing the results of a hot box test for a 4680 cell manufactured according to Comparative Example 1 of the present invention. [Figure 45c] 1 is a graph showing the results of a hot box test for 4680 cells manufactured according to Sample 1 of Example 2-1 of the present invention and Comparative Example 2-1. [Figure 45d] 1 is a graph showing the results of a hot box test for 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. [Figure 46a] 2 is a cross-sectional SEM photograph of a positive electrode produced in Example 2-1 of the present invention. [Figure 46b] 1 is a cross-sectional SEM photograph of a positive electrode produced in Comparative Example 2-1. [Figure 47a] 10 is a graph showing the results of measuring the resistance characteristics according to the SOC while charging coin-type half cells including the positive electrodes according to Example 3-3 of the present invention, Comparative Example 3-1, and Comparative Example 3-2 up to 4.2 V. [Figure 47b] 1 is a graph showing the measurement results of capacity retention and resistance increase rate obtained through charge-discharge cycle experiments on 4680 cells according to Example 3-1, Example 3-3, and Comparative Example 3-1 of the present invention. [Figure 48] 1 is a diagram illustrating an electrode assembly according to an embodiment of the present invention. [Figure 49] FIG. 49 is a cross-sectional view taken along line AA' in FIG. 48. [Figure 50] 1A to 1C are diagrams illustrating a process for manufacturing a negative electrode according to an embodiment of the present invention. [Figure 51] 1A to 1C are diagrams illustrating a process for manufacturing a negative electrode according to an embodiment of the present invention. [Figure 52] 1 is a perspective view showing a negative electrode according to an embodiment of the present invention. [Figure 53] 1A to 1C are diagrams illustrating a process for manufacturing a positive electrode according to one embodiment of the present invention. [Figure 54] 1A to 1C are diagrams illustrating a process for manufacturing a positive electrode according to one embodiment of the present invention. [Figure 55] FIG. 1 is a perspective view showing a positive electrode according to one embodiment of the present invention. [Figure 56]10 is a diagram illustrating an electrode assembly according to a comparative example of the present invention. [Figure 57] FIG. 57 is a cross-sectional view taken along line BB' in FIG. 56. [Figure 58] 1 is a diagram showing a process for producing a negative electrode according to a comparative embodiment of the present invention. [Figure 59] FIG. 1 is a diagram showing a process for producing a positive electrode according to a comparative embodiment of the present invention. [Figure 60] 1 is a graph showing changes in energy density depending on the content of 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 INVENTION

[0102] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Prior to this, the terms and words used in this specification and claims should not be construed as being limited to their ordinary and dictionary meanings, but should be construed as having meanings and concepts corresponding to the technical ideas of the present invention, based on the principle that the inventor himself can appropriately define the concepts of terms in order to best describe the invention. Therefore, it should be understood that the embodiment described in this specification and the configurations shown in the drawings are merely the most preferred embodiment of the present invention and do not represent the entire technical ideas of the present invention, and therefore various equivalents and modifications that can be substituted therefor may exist at the time of filing this application.

[0103] In addition, to facilitate understanding of the invention, the accompanying drawings may not be drawn to scale, and the dimensions of some components may be exaggerated. In addition, the same reference numerals may be used to refer to the same components in different embodiments.

[0104] The size and thickness of each component shown in the drawings are arbitrarily shown for the convenience of explanation, and the present invention is not necessarily limited by the drawings. In the drawings, thicknesses are exaggerated to clearly show many layers and regions. Also, in the drawings, thicknesses of some layers and regions are exaggerated for the convenience of explanation.

[0105] Furthermore, when a layer, film, region, plate, or other part is said to be "on" or "above" another part, this includes not only the case where it is "directly above" that part, but also the case where there is another part in between. Conversely, when a part is said to be "directly above" another part, it means that there is no other part in between. Furthermore, being "on" or "above" a reference part means being located above or below the reference part, and does not necessarily mean being located "on" or "above" the direction opposite to gravity.

[0106] Furthermore, throughout the specification, when a part "comprises" another component, it does not mean that the other component is excluded, but that the part may further include the other component, unless otherwise specified.

[0107] Furthermore, throughout the specification, a "plan view" means a view of the target part viewed from above, and a "cross-sectional view" means a view of the target part cut vertically from the side.

[0108] FIG. 4 is a perspective view showing the appearance of a cylindrical battery according to an embodiment of the present invention, and FIG. 5 is a cross-sectional view showing the internal structure of the cylindrical battery according to an embodiment of the present invention.

[0109] 4 and 5, a cylindrical battery 1 according to one embodiment of the present invention includes an electrode assembly A, a battery housing BH, a first current collector 35, a cap plate 40, a spacer 50, and an external terminal 60. In addition to the above-mentioned components, the cylindrical battery 1 may further include an insulating gasket G and / or a second current collector 36 and / or an insulator 80.

[0110] 5, 7, 10, and 11, the electrode assembly A includes a first electrode tab 13 and a second electrode tab 14. The electrode assembly A includes a first electrode having a first polarity, a second electrode having a second polarity, and a separator interposed between the first and second electrodes. The first electrode is a negative or positive electrode, and the second electrode has the opposite polarity to the first electrode.

[0111] The electrode assembly A may have, for example, a jelly-roll structure. That is, the electrode assembly A may be manufactured by stacking a first electrode, a separator, and a second electrode in sequence at least once and winding the stack. Such a jelly-roll type electrode assembly A may have a winding center hole C formed in its center and extending along the height direction (Z-axis direction). Meanwhile, a separator may be further provided on the outer periphery of the electrode assembly A to insulate it from the battery housing BH.

[0112] The first electrode includes a first electrode collector and a first electrode active material layer formed by coating one or both surfaces of the first electrode collector. One end of the first electrode collector in the width direction (Z-axis direction) has an uncoated portion (first uncoated portion) of the first electrode where the first electrode active material is not coated. The first uncoated portion extends from one end to the other end along the length of the first electrode when the first electrode is unfolded. The first uncoated portion functions as the first electrode tab 13 described above. The first electrode tab 13 is provided on one surface of the electrode assembly A. More specifically, the first electrode tab 13 is provided at the lower portion in the height direction (Z-axis direction) of the electrode assembly A housed in the battery housing BH.

[0113] The second electrode includes a second electrode current collector and a second electrode active material layer formed by coating one or both sides of the second electrode current collector. An uncoated portion (second uncoated portion) of the second electrode, where the second electrode active material is not coated, is present at the other end of the second electrode current collector in the width direction (Z-axis direction). The second uncoated portion extends from one end to the other end along the length of the second electrode when the second electrode is unfolded. The second uncoated portion functions as the second electrode tab 14 described above. The second electrode tab 14 is provided on the other side of the electrode assembly A. More specifically, the second electrode tab 14 is provided at the upper portion in the height direction (Z-axis direction) of the electrode assembly A housed in the battery housing BH.

[0114] That is, the first electrode tab 13 and the second electrode tab 14 extend and protrude in opposite directions along the height direction (Z-axis direction) of the electrode assembly A, ie, the height direction of the cylindrical battery 1.

[0115] 4, 5, 7, and 10, the battery housing BH accommodates the electrode assembly A through an opening formed at its bottom. The battery housing BH is a generally cylindrical container having an opening formed at its bottom and a closed portion formed at its top. The battery housing BH may be made of a conductive material such as metal. The material of the battery housing BH may be, for example, aluminum. The side (outer periphery) and top of the battery housing BH may be integrally formed. The top (surface parallel to the XY plane) of the battery housing BH may have a generally flat shape. The battery housing BH accommodates the electrode assembly A and an electrolyte through an opening formed at its bottom.

[0116] The battery housing BH is electrically connected to the electrode assembly A. The battery housing BH is connected to the first electrode tab 13 of the electrode assembly A. Therefore, the battery housing BH has the same electrical polarity as the first electrode tab 13.

[0117] 5 and 7, the battery housing BH may include a beading portion 23 and a crimping portion 24 formed at its lower end. The beading portion 23 is located below the electrode assembly A housed inside the battery housing BH. The beading portion 23 is formed by pressing in on the outer periphery of the battery housing BH. The beading portion 23 partially reduces the inner diameter of the battery housing BH, thereby preventing the electrode assembly A, which has a size approximately corresponding to the width of the battery housing BH, from slipping out of the opening formed at the lower end of the battery housing BH. The beading portion 23 may also function as a support on which the cap plate 40 is placed.

[0118] The crimping portion 24 is formed below the beading portion 23. The crimping portion 24 is extended and bent to enclose the peripheral portion of the cap plate 40 with the peripheral portion of the spacer 50 interposed therebetween.

[0119] 5 to 7 and 11, the first current collecting plate 35 is coupled to the first electrode tab 13 of the electrode assembly A and positioned within the battery housing BH. The first current collecting plate 35 covers at least a portion of the lower surface of the electrode assembly A. The combined assembly including the electrode assembly A and the first current collecting plate 35 can be inserted into the battery housing BH through an opening formed in the lower end of the battery housing BH. The first current collecting plate 35 is electrically connected to the battery housing BH. That is, the first current collecting plate 35 can function as a medium for electrical connection between the electrode assembly A and the battery housing BH.

[0120] 6, the first current collecting plate 35 may include, for example, a support portion 35a, a non-coating portion coupling portion 35b, and a housing contact portion 35c. The support portion 35a is located at the center of one surface formed at the lower end of the electrode assembly A. The support portion 35a may have a first current collecting plate hole H1 formed at a position corresponding to the winding center hole C of the electrode assembly A. The first current collecting plate hole H1 may function as a passage for inserting a welding rod or irradiating a laser to connect the external terminal 60 and the second current collecting plate 36, which will be described later. In addition, the first current collecting plate hole H1 may also function as a passage for smoothly impregnating the interior of the electrode assembly A with electrolyte when the electrolyte is injected.

[0121] The non-coating portion coupling portion 35b extends from the support portion 35a and couples with the first electrode tab 13. For example, a plurality of non-coating portion coupling portions 35b may be provided. In this case, each of the non-coating portion coupling portions 35b may extend radially from the support portion 35a. The housing contact portion 35c may extend from the support portion 35a as shown in FIG. 6, or may extend from an end of the non-coating portion coupling portion 35b, as shown in FIG. 6. An end of the housing contact portion 35c is interposed between a sealing portion 52 of a spacer 50 (described below) and the battery housing BH to contact the battery housing BH, thereby electrically connecting the battery housing BH and the first current collector plate 35.

[0122] For example, a plurality of housing contact portions 35c may be provided. In this case, the plurality of housing contact portions 35c may extend radially from the support portion 35a, as shown in Fig. 6, and at least one housing contact portion 35c may be located between adjacent non-coating portion coupling portions 35b. Alternatively, the plurality of housing contact portions 35c may extend from respective ends of the plurality of non-coating portion coupling portions 35b, unlike Fig. 6.

[0123] 5, 7, and 9, the cap plate 40 covers an opening formed in the battery housing BH. The cap plate 40 may be made of, for example, a metal material to ensure rigidity. The cap plate 40 forms the bottom surface of the cylindrical battery 1. In a cylindrical battery 1 according to one embodiment of the present invention, the cap plate 40 has no polarity even when made of a conductive metal material. "No polarity" means that the cap plate 40 is electrically insulated from the battery housing BH and the terminal 60. Therefore, the cap plate 40 does not function as a positive or negative terminal. Therefore, the cap plate 40 does not need to be electrically connected to the electrode assembly A and the battery housing BH, and its material does not necessarily need to be a conductive metal.

[0124] When the battery housing BH according to an embodiment of the present invention includes a beading portion 23, the cap plate 40 may be placed on the beading portion 23 formed on the battery housing BH. When the battery housing BH according to an embodiment of the present invention includes a crimping portion 24, the cap plate 40 is fixed by the crimping portion 24. A peripheral portion of a spacer 50 is interposed between the cap plate 40 and the crimping portion 24 of the battery housing BH to ensure airtightness of the battery housing BH.

[0125] 7 and 9, the cap plate 40 may further include a vent 41 formed to prevent the internal pressure of the battery housing BH from increasing beyond a predetermined value due to gas generated inside the battery housing BH. The vent 41 corresponds to a region of the cap plate 40 that is thinner than the surrounding region. The vent 41 is structurally weaker than the surrounding region. Therefore, if an abnormality occurs in the cylindrical battery 1 and the internal pressure of the battery housing BH increases above a certain level, the vent 41 ruptures, allowing the gas generated inside the battery housing BH to be discharged. The vent 41 may be formed, for example, by notching one or both surfaces of the cap plate 40 to partially reduce the thickness of the battery housing BH.

[0126] 7, it is preferable that the lower end of the cap plate 40 is located higher than the lower end of the battery housing BH. In this case, even if the lower end of the battery housing BH contacts the ground or the bottom of a housing for configuring a module or pack, the cap plate 40 does not contact the ground or the bottom of the pack housing. This prevents the pressure required to break the venting portion 41 from varying from the designed value due to the weight of the cylindrical battery 1, thereby ensuring smooth breaking of the venting portion 41.

[0127] On the other hand, when the venting portion 41 has a closed loop shape as shown in Figures 7 and 9, the greater the distance from the center of the cap plate 40 to the venting portion 41, the greater the force acting on the venting portion 41 when the same venting pressure is applied, making it easier to rupture. Furthermore, the greater the distance from the center of the cap plate 40 to the venting portion 41, the greater the ease of discharge of venting gas. From this perspective, it is advantageous for the venting portion 41 to be formed along the periphery of a substantially flat region that protrudes downward (downward in Figure 7) from the peripheral region of the cap plate 40.

[0128] 7 shows the venting portion 41 formed continuously in a substantially circular shape, but the present invention is not limited thereto. The venting portion 41 may be formed discontinuously in a substantially circular shape on the cap plate 40, or may be formed in a substantially linear shape or other shapes.

[0129] 5, 7, and 8, the spacer 50 is configured to prevent movement of the electrode assembly A and strengthen the sealing force of the battery housing BH. The spacer 50 may include, for example, a movement prevention portion 51, a sealing portion 52, and a connecting portion 53. The movement prevention portion 51 is interposed between the first current collecting plate 35 and the cap plate 40. The movement prevention portion 51 may have a height corresponding to the distance between the first current collecting plate 35 and the cap plate 40. In this case, the movement prevention portion 51 can effectively prevent the electrode assembly A from moving within the battery housing BH due to the clearance formed between the first current collecting plate 35 and the cap plate 40. Therefore, the movement prevention portion 51 can prevent damage to the connection portion between the electrode assembly A and the first current collecting plate 35 and / or the connection portion between the first current collecting plate 35 and the battery housing BH.

[0130] The movement prevention portion 51 may be located approximately at the center of the underside of the electrode assembly A. The movement prevention portion 51 may include a spacer hole H2 formed at a position corresponding to the winding center hole C of the electrode assembly A. Similar to the first current collecting plate hole H1 described above, the spacer hole H2 may function as a passage for inserting a welding rod or a passage for laser irradiation. Similar to the first current collecting plate hole H1 described above, the spacer hole H2 may also function as a passage for smoothly impregnating the interior of the electrode assembly A with electrolyte when the electrolyte is injected.

[0131] The sealing portion 52 is interposed between the battery housing BH and the cap plate 40. The sealing portion 52 may extend along the inner circumferential surface of the battery housing BH. If the battery housing BH includes the crimping portion 24, the sealing portion 52 may be folded along the bent shape of the crimping portion 24 to enclose the peripheral region of the cap plate 40. In this manner, the sealing portion 52 may function as a gasket to improve the fixing strength of the cap plate 40 and the sealing strength of the battery housing BH.

[0132] The connecting portion 53 connects the movement prevention portion 51 and the sealing portion 52. The connecting portion 53 may include, for example, a plurality of extension legs 53a extending radially from the movement prevention portion 51. When the connecting portion 53 is configured in this manner, the electrolyte can be smoothly injected through the spaces between the adjacent extension legs 53a, and the internal gas can be smoothly discharged when venting occurs due to an increase in internal pressure.

[0133] As shown in FIG. 7 , the extension legs 53a may be configured not to contact the cap plate 40 and / or other portions of the housing contact portions 35c of the first current collecting plate 35 except for the portion inserted into the crimping portion 24. For example, the connecting portion 53 may be positioned so as not to overlap the housing contact portions 35c along the height direction (Z-axis direction) of the cylindrical battery 1. In particular, if the extension legs 53a extend radially from the movement preventing portion 51 and the housing contact portions 35c extend radially from the support portion 35a, the extension legs 53a and the housing contact portions 35c may be alternately positioned so as not to overlap each other in the vertical direction. In this case, even if a compressive force is applied to the battery housing BH in the vertical direction, causing deformation of the components, interference between the extension legs 53a and the housing contact portions 35c is significantly reduced, thereby significantly reducing the possibility of problems such as damage to the connection between the components.

[0134] In this case, even if the spacer 50 is deformed due to a sizing process that compresses the cylindrical battery 1 along the height direction (Z-axis direction) or other reasons, interference between the connection portion 53 of the spacer 50 and the housing contact portion 35c of the first current collecting plate 35 can be minimized. In particular, if the extension leg 53a is configured not to come into contact with the cap plate 40, the possibility of deformation of the extension leg 53a can be reduced even if deformation occurs in the battery housing BH due to the sizing process or external impact.

[0135] Meanwhile, the components constituting the spacer 50 may be integrally formed. For example, the spacer 50 may be manufactured by injection molding, with the movement-preventing portion 51, the sealing portion 52, and the connecting portion 53 integrated into one piece. That is, the cylindrical battery 1 according to an embodiment of the present invention can achieve both an enhanced sealing force for the opening of the battery housing BH and movement prevention effects for the electrode assembly A as a single component by modifying and manufacturing the gasket component used to seal the opening of the battery housing BH. Therefore, according to one embodiment of the present invention, it is possible to prevent the complication of the manufacturing process and the increase in manufacturing costs that would occur due to the use of additional components.

[0136] 4, 5, and 10, the external terminal 60 is electrically connected to the second electrode tab 14 of the electrode assembly A. The external terminal 60 may, for example, pass through approximately the center of a closure formed at the upper end of the battery housing BH. A portion of the external terminal 60 may be exposed to the upper side of the battery housing BH, and the remaining portion may be located inside the battery housing BH. The peripheral portion of the lower end of the external terminal 60 may be fixed to the inner surface of the closure of the battery housing BH by, for example, riveting. Riveting is achieved by fastening the peripheral portion of the lower end of the external terminal 60 with a crimping tool, thereby plastically deforming the peripheral portion of the lower end.

[0137] As described above, in the embodiment of the present invention, the battery housing BH is electrically connected to the first electrode tab 13 of the electrode assembly A, so that the closed portion formed at the upper end of the battery housing BH can function as the first electrode terminal E1 having the first polarity. Meanwhile, the external terminal 60 is electrically connected to the second electrode tab 14 of the electrode assembly A, so that the external terminal 60 exposed to the outside of the battery housing BH can function as the second electrode terminal E2.

[0138] That is, a cylindrical battery 1 according to one embodiment of the present invention has a structure in which a pair of electrode terminals (first electrode terminal E1, second electrode terminal E2) are positioned in the same direction. Therefore, when electrically connecting multiple cylindrical batteries 1, an electrical connection component such as a bus bar can be disposed on only one side of the cylindrical batteries 1. This simplifies the battery pack structure and improves energy density. Furthermore, the cylindrical battery 1 has a structure in which one surface of the battery housing BH, which has a substantially flat shape, can be used as the first electrode terminal E1, thereby ensuring a sufficient bonding area when bonding an electrical connection component such as a bus bar to the first electrode terminal E1. As a result, the cylindrical battery 1 can ensure sufficient bonding strength between the electrical connection component and the first electrode terminal E1 and reduce resistance at the bonding site to a desirable level.

[0139] As described above, when the external terminal 60 functions as the second electrode terminal E2, the external terminal 60 is electrically insulated from the battery housing BH having the first polarity. Electrical insulation between the battery housing BH and the external terminal 60 can be achieved in various ways. For example, insulation can be achieved by interposing an insulating gasket G between the external terminal 60 and the battery housing BH. Alternatively, insulation can be achieved by forming an insulating coating layer on a portion of the external terminal 60. Alternatively, a method can be used in which the external terminal 60 and the battery housing BH are spaced apart to prevent contact therebetween and the external terminal 60 is structurally firmly fixed. Alternatively, a combination of the above-mentioned methods can be used.

[0140] Meanwhile, when an insulating gasket G is used for electrical insulation and riveting is used to secure the external terminal 60, the insulating gasket G may be deformed together with the external terminal 60 when riveting, and bend toward the inner surface of the upper closure of the battery housing BH, as shown in Fig. 10. When the insulating gasket G is made of a resin material, the insulating gasket G may be joined to the battery housing BH and the external terminal 60 by thermal fusion. In this case, the airtightness at the joining interface between the insulating gasket G and the external terminal 60 and the joining interface between the insulating gasket G and the battery housing BH is enhanced.

[0141] 5, 10, and 11, the second current collecting plate 36 is coupled to the upper portion of the electrode assembly A. The second current collecting plate 36 is made of a conductive metal material and is coupled to the second electrode tab 14. The coupling between the second electrode tab 14 and the second current collecting plate 36 may be performed, for example, by laser welding. Referring to FIG. 11, the second current collecting plate 36 may be coupled to a coupling surface formed by bending an end of the second electrode tab 14 in a direction parallel to the second current collecting plate 36. The bending direction of the second electrode tab 14 may be, for example, toward the winding center of the electrode assembly A. When the second electrode tab 14 has such a bent shape, the space occupied by the second electrode tab 14 is reduced, thereby improving energy density. Furthermore, the increased coupling area between the second electrode tab 14 and the second current collecting plate 36 may improve coupling strength and reduce resistance. Meanwhile, the above-described coupling structure and coupling method between the second electrode tab 14 and the second current collecting plate 36 can be similarly applied to the coupling between the first electrode tab 13 and the first current collecting plate 35 .

[0142] 5 and 10, an insulator 80 is interposed between a closing portion formed at the upper end of the battery housing BH and the upper end of the electrode assembly A, or between the closing portion and the second current collecting plate 36. The insulator 80 may be made of, for example, an insulating resin material. The insulator 80 prevents contact between the electrode assembly A and the battery housing BH and / or between the second current collecting plate 36 and the battery housing BH.

[0143] The insulator 80 may also be interposed between the upper end of the outer periphery of the electrode assembly A and the inner surface of the battery housing BH. In this case, it is possible to prevent the second electrode tab 14 of the electrode assembly A from coming into contact with the inner surface of the side wall of the battery housing BH, thereby preventing a short circuit from occurring.

[0144] The insulator 80 may have a height corresponding to the distance between the electrode assembly A and a closing portion formed at the upper end of the battery housing BH or the distance between the closing portion and the second current collecting plate 36. In this case, the electrode assembly A can be prevented from moving inside the battery housing BH, thereby significantly reducing the possibility of damage to the coupling portions for electrical connection between components. When the insulator 80 is used together with the spacer 50 described above, the effect of preventing movement of the electrode assembly A can be maximized.

[0145] The insulator 80 may have an opening formed at a position corresponding to the winding center hole C of the electrode assembly A. The external terminal 60 can be in direct contact with the second current collector plate 36 through the opening.

[0146] Preferably, the cylindrical battery may be, for example, a cylindrical battery having a form factor ratio (defined as the diameter of a cylindrical battery divided by its height, i.e., the ratio of height (H) to diameter (Φ)) greater than about 0.4.

[0147] Here, form factor refers to a value indicating the diameter and height of a cylindrical battery. A cylindrical battery according to an embodiment of the present invention may be, for example, a 46110 battery, a 4875 battery, a 48110 battery, a 4880 battery, or a 4680 battery. In the form factor number, the first two digits indicate the cell diameter, and the remaining digits indicate the battery height.

[0148] A battery according to one embodiment of the present invention may be a generally cylindrical battery having a diameter of about 46 mm, a height of about 110 mm, and a form factor ratio of about 0.418.

[0149] Another embodiment of the battery may be a generally cylindrical battery having a diameter of about 48 mm, a height of about 75 mm, and a form factor ratio of about 0.640.

[0150] In yet another embodiment, the battery may be a generally cylindrical battery having a diameter of about 48 mm, a height of about 110 mm, and a form factor ratio of about 0.436.

[0151] In yet another embodiment, the battery may be a generally cylindrical battery having a diameter of about 48 mm, a height of about 80 mm, and a form factor ratio of about 0.600.

[0152] In yet another embodiment, the battery may be a generally cylindrical battery having a diameter of about 46 mm, a height of about 80 mm, and a form factor ratio of about 0.575.

[0153] Conventionally, batteries with a form factor ratio of approximately 0.4 or less have been used. For example, 1865 batteries and 2170 batteries have been used. 1865 batteries have a diameter of approximately 18 mm and a height of approximately 65 mm, resulting in a form factor ratio of approximately 0.277. 2170 batteries have a diameter of approximately 21 mm and a height of approximately 70 mm, resulting in a form factor ratio of approximately 0.300.

[0154] 12, a battery pack 3 according to one embodiment of the present invention includes a battery assembly in which a plurality of cylindrical batteries 1 according to one embodiment of the present invention are electrically connected as described above, and a pack housing 2 that accommodates the battery assembly. For convenience of illustration, components such as bus bars for electrical connection, a cooling unit, and power terminals are not shown.

[0155] 13, an automobile 5 according to an embodiment of the present invention may be, 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 or a two-wheeled automobile. The automobile 5 operates by receiving a supply of power from the battery pack 3 according to an embodiment of the present invention.

[0156] Hereinafter, various embodiments of an electrode plate, an electrode assembly, and a cylindrical battery will be described with reference to FIGS.

[0157] First, an electrode assembly according to an embodiment of the present invention will be described. The electrode assembly is a jelly-roll type electrode assembly having a structure in which a sheet-like first electrode, a sheet-like second electrode, and a separator interposed between the first and second electrodes are wound in one direction.

[0158] Preferably, at least one of the first and second electrodes includes an uncoated portion on a long side edge in the winding direction where no active material is coated. At least a portion of the uncoated portion itself is used as an electrode tab. The uncoated portions include a core-side uncoated portion adjacent to the core of the electrode assembly, an outer-side uncoated portion adjacent to the outer peripheral surface of the electrode assembly, and an intermediate uncoated portion interposed between the core-side uncoated portion and the outer-side uncoated portion.

[0159] Preferably, the height of at least one of the core-side uncoated portion and the outer-periphery-side uncoated portion is relatively lower than that of the intermediate uncoated portion.

[0160] FIG. 14 is a plan view showing the structure of an electrode 60a according to the first embodiment of the present invention.

[0161] Referring to FIG. 14, the electrode 60a of the first embodiment includes a current collector 61 made of metal foil and an active material layer 62. The metal foil may be aluminum or copper, and is appropriately selected depending on the polarity of the electrode 60a. The active material layer 62 is formed on at least one surface of the current collector 61 and includes a plain portion 63 at the long edge in the winding direction (X-axis). The plain portion 63 is an area where no active material is coated. An insulating coating layer 64 may be formed at the boundary between the active material layer 62 and the plain portion 63. The insulating coating layer 64 is formed so that at least a portion of the insulating coating layer 64 overlaps the boundary between the active material layer 62 and the plain portion 63. The insulating coating layer 64 includes a polymer resin and may also include an inorganic filler such as Al2O3.

[0162] The uncoated portion 63 includes a core-side uncoated portion B1 adjacent to the core side of the electrode assembly, an outer-periphery-side uncoated portion B3 adjacent to the outer-periphery side of the electrode assembly, and an intermediate uncoated portion B2 interposed between the core-side uncoated portion B1 and the outer-periphery-side uncoated portion B3.

[0163] When the electrode 60a is wound into a jelly-roll-type electrode assembly, the core-side uncoated region B1, the outer-periphery uncoated region B3, and the intermediate uncoated region B2 may be defined as the uncoated region adjacent to the core side, the uncoated region adjacent to the outer periphery, and the uncoated region excluding these, respectively. The boundary between the core-side uncoated region B1 and the intermediate uncoated region B2 may be appropriately defined as a point where the height (or change pattern) of the uncoated region substantially changes from the core side to the outer periphery of the electrode assembly, or as a predetermined percentage point based on the radius of the electrode assembly (e.g., 5%, 10%, 15% of the radius). The boundary between the intermediate uncoated region B2 and the outer-periphery uncoated region B3 may be defined as a point where the height (or change pattern) of the uncoated region substantially changes from the outer periphery to the core side of the electrode assembly, or as a predetermined percentage point based on the radius of the electrode assembly (e.g., 85%, 90%, 95% of the radius). Once the boundaries between the core-side uncoated area B1 and the intermediate uncoated area B2 and the boundaries between the intermediate uncoated area B2 and the outer-side uncoated area B3 are identified, the intermediate uncoated area B2 can be automatically identified. If only the boundaries between the core-side uncoated area B1 and the intermediate uncoated area B2 are identified, the boundary between the intermediate uncoated area B2 and the outer-side uncoated area B3 can be appropriately selected as a point near the outer periphery of the electrode assembly. Conversely, if only the boundaries between the intermediate uncoated area B2 and the outer-side uncoated area B3 are identified, the boundary between the core-side uncoated area B1 and the intermediate uncoated area B2 can be appropriately selected as a point near the core side of the electrode assembly. In the first embodiment, the height of the uncoated area 63 is not constant but varies relatively in the winding direction (X-axis direction). That is, the height (length in the Y-axis direction) of the outer-side uncoated area B3 is relatively lower than the core-side uncoated area B1 and the intermediate uncoated area B2.

[0164] FIG. 15 is a plan view showing the structure of an electrode 60b according to the second embodiment of the present invention.

[0165] Referring to FIG. 15, the electrode 60b of the second embodiment is substantially the same in configuration as the first embodiment except that the height of the outer periphery uncoated portion B3 gradually decreases toward the outer periphery.

[0166] In one modified embodiment, the outer peripheral uncoated portion B3 can be deformed into a staircase shape (see dotted lines) in which the height decreases stepwise.

[0167] FIG. 16 is a plan view showing the structure of an electrode 60c according to a third embodiment of the present invention.

[0168] 16, in the electrode 60c of the third embodiment, the heights of the core-side uncoated portion B1 and the outer-side uncoated portion B3 are relatively lower than the intermediate uncoated portion B2. The heights of the core-side uncoated portion B1 and the outer-side uncoated portion B3 may be the same or different.

[0169] Preferably, the height of the middle uncoated portion B2 may be in a stepped shape that increases stepwise from the core side toward the outer periphery side.

[0170] Patterns 1 to 7 are obtained by dividing the intermediate plain portion B2 around the positions where the height of the plain portion 63 changes. Preferably, the number of patterns, and the height (length in the Y-axis direction) and width (length in the X-axis direction) of each pattern can be adjusted to maximize stress dispersion during the folding process of the plain portion 63. Dispersion of stress is intended to prevent tearing of the plain portion 63.

[0171] Width d of the core side plain area B1 B1 is designed so that the cavity in the core of the electrode assembly is not blocked when the pattern of the middle plain portion B2 is bent toward the core.

[0172] In one example, the width d of the core-side uncoated portion B1 B1 may increase in proportion to the bending length of the pattern 1. The bending length corresponds to the height of the pattern based on the bending point of the pattern.

[0173] In a specific example, when the electrode 60c is used to manufacture an electrode assembly for a cylindrical battery with a form factor of 4680, the width d of the core-side uncoated portion B1 is B1 can be set to 180 mm to 350 mm depending on the diameter of the core of the electrode assembly.

[0174] In one example, the width of each pattern can be designed to form the same winding turn of the electrode assembly.

[0175] In another example, the height of the middle uncoated portion B2 may have a step shape that increases and then decreases from the core side toward the outer periphery.

[0176] In yet another example, the outer circumferential uncoated portion B3 may be modified to have the same structure as that of the second embodiment.

[0177] In yet another example, the pattern structure applied to the middle solid portion B2 may be extended to the outer solid portion B3 (see dotted lines).

[0178] FIG. 17 is a plan view showing the structure of an electrode 60d according to a fourth embodiment of the present invention.

[0179] 17, in the electrode 60d of the fourth embodiment, the heights of the core-side uncoated portion B1 and the outer-side uncoated portion B3 are relatively lower than the height of the intermediate uncoated portion B2. The heights of the core-side uncoated portion B1 and the outer-side uncoated portion B3 may be the same or different.

[0180] Preferably, at least a portion of the intermediate uncoated portion B2 may include a plurality of minute segments P. The height of the plurality of minute segments P may increase stepwise from the core side toward the outer periphery side.

[0181] The section P may be laser notched. The section P may be formed by known metal foil cutting processes such as ultrasonic cutting or punching.

[0182] In the fourth embodiment, to prevent damage to the active material layer 62 and / or the insulating coating layer 64 during the folding process of the uncoated portion 63, a predetermined gap is preferably provided between the lower end of the cutting line between the divided pieces P and the active material layer 62. This is because stress is concentrated near the lower end of the cutting line when the uncoated portion 63 is folded. The gap is preferably 0.2 mm to 4 mm. By adjusting the gap within the above numerical range, damage to the active material layer 62 and / or the insulating coating layer 64 near the lower end of the cutting line due to stress generated during the folding process of the uncoated portion 63 can be prevented. In addition, the gap can prevent damage to the active material layer 62 and / or the insulating coating layer 64 due to tolerances during notching or cutting of the divided pieces P. Preferably, when the electrode 60d is wound into an electrode assembly, at least a portion of the insulating coating layer 64 may be exposed to the outside of the separator. In this case, the insulating coating layer 64 can support the folding point when the divided pieces P are folded.

[0183] The plurality of segment pieces P may be arranged into a plurality of segment piece groups from the core side toward the outer periphery side. The width, height, and spacing pitch of the segment pieces belonging to the same segment piece group may be substantially the same.

[0184] FIG. 18 is a diagram illustrating definitions of the width, height, and spacing pitch of the segment P according to an embodiment of the present invention.

[0185] 18, the width C1, height C2, and spacing pitch C3 of the divided pieces P are designed to prevent tearing of the plain portion 63 during bending and to improve weld strength by sufficiently increasing the number of overlapping layers of the plain portion 63 while preventing abnormal deformation of the plain portion 63. Abnormal deformation refers to the plain portion below the bending point C4 collapsing and deforming irregularly, instead of maintaining a straight line.

[0186] Preferably, the width C1 of the segment P can be adjusted within a range of 1 mm to 6 mm. If C1 is less than 1 mm, when the segment P is bent toward the core, a non-overlapping region or an open space (gap) that is insufficient to ensure sufficient welding strength will be generated. On the other hand, if C1 exceeds 6 mm, the uncoated portion 63 near the bending point C4 may be torn by stress when the segment P is bent toward the core. Furthermore, the height of the segment P can be adjusted within a range of 2 mm to 10 mm. If C2 is less than 2 mm, when the segment P is bent toward the core, a non-overlapping region or an open space (gap) that is insufficient to ensure sufficient welding strength will be generated. On the other hand, if C2 exceeds 10 mm, it is difficult to manufacture an electrode while maintaining uniform flatness of the uncoated portion in the winding direction X. In other words, the uncoated portion becomes higher, resulting in swell. Furthermore, the spacing pitch C3 of the segment P can be adjusted within a range of 0.05 mm to 1 mm. If C3 is less than 0.05 mm, the uncoated portion 63 near the bending point C4 may be torn by stress when the divided piece P is bent. On the other hand, if C3 exceeds 1 mm, the divided pieces P may not overlap enough to ensure sufficient welding strength when bent, or an empty space (gap) may be generated.

[0187] Referring further to FIG. 17, the width d of the core-side uncoated portion B1 B1 is designed so that when the segment P of the middle plain portion B2 is bent toward the core, the cavity of the core of the electrode assembly is not blocked.

[0188] In one example, the width d of the core-side uncoated portion B1 B1 can increase in proportion to the bending length of the segment P of group 1. The bending length corresponds to the height of the segment P based on the bending point (C4 in FIG. 18).

[0189] In a specific example, when the electrode 60d is used to manufacture an electrode assembly for a cylindrical battery with a form factor of 4680, the width d of the core-side uncoated portion B1 is B1 can be set to 180 mm to 350 mm depending on the diameter of the core of the electrode assembly.

[0190] In one example, the width of each segment group can be designed to form the same winding turn of the electrode assembly.

[0191] In another example, the width and / or height and / or spacing pitch of the segments P belonging to the same segment group may increase or decrease gradually and / or stepwise and / or irregularly within the group.

[0192] Groups 1 to 7 are merely examples of segment groups. The number of groups and the number of segment P included in each group can be adjusted so that the segment P overlaps multiple times to maximize stress distribution during the bending process of the plain portion 63 and ensure sufficient welding strength.

[0193] In yet another example, the height of the outer plain portion B3 may decrease gradually or in steps, as in the first and second embodiments. The divided structure of the intermediate plain portion B2 may extend to the outer plain portion B3 (see dotted lines). In this case, the outer plain portion B3 may also include multiple divided segments, similar to the intermediate plain portion B2. In this case, the divided segments of the outer plain portion B3 may have a greater width and / or height and / or spacing pitch than the intermediate plain portion B2.

[0194] In a specific example, when electrode 60d is used to manufacture an electrode assembly for a cylindrical battery with a form factor of 4680, the segments may be formed in eight groups. In this case, the segments of groups 1 to 7 may be formed in the middle uncoated portion B2, and the segment of group 8 may be formed in the outer uncoated portion B3 as in the example described above.

[0195] In a specific example, the width d of the core-side uncoated portion B1 B1The width of Group 1 may be 35% to 40% of the width of core-side plain portion B1. The width of Group 2 may be 130% to 150% of the width of Group 1. The width of Group 3 may be 120% to 135% of the width of Group 2. The width of Group 4 may be 85% to 90% of the width of Group 3. The width of Group 5 may be 120% to 130% of the width of Group 4. The width of Group 6 may be 100% to 120% of the width of Group 5. The width of Group 7 may be 90% to 120% of the width of Group 6. The width of Group 8 may be 115% to 130% of the width of Group 7.

[0196] The reason why the widths of Groups 1 to 8 do not show a constant increase or decrease pattern is that although the width of the segments gradually increases from Group 1 to Group 8, the number of segments included in a group is limited to an integer. Therefore, the number of segments may decrease in a particular segment group. Therefore, the width of the group may show an irregular change pattern from the core side to the outer periphery side, as shown in the example above.

[0197] That is, when the winding direction widths of three adjacent segment groups in the radial direction of the electrode assembly are W1, W2, and W3, respectively, the electrode assembly may include a combination of segment groups in which W3 / W2 is smaller than W2 / W1.

[0198] In the specific example described above, this applies to groups 4 to 6. The width ratio of group 5 to group 4 is 120% to 130%, and the width ratio of group 6 to group 5 is 100% to 120%, which is smaller than 120% to 130%.

[0199] FIG. 19 is a plan view showing the structure of an electrode 60e according to a fifth embodiment of the present invention.

[0200] Referring to Figure 19, the electrode 60e of the fifth embodiment is substantially identical in configuration to the fourth embodiment (or modified form), except that the shape of the segment P' is changed from a square to a trapezoid, compared to the fourth embodiment.

[0201] FIG. 20 is a diagram showing the definitions of the width, height, and separation pitch of the trapezoidal segment P'.

[0202] Referring to FIG. 20, the width D1, height D2, and spacing pitch D3 of the divided piece P' are designed to prevent tearing of the uncoated portion 63 near the bending point D4 during bending and to ensure sufficient welding strength by sufficiently increasing the number of overlapping layers of the uncoated portion 63 while preventing abnormal deformation of the uncoated portion 63.

[0203] Preferably, the width D1 of the segment P' can be adjusted in the range of 1 mm to 6 mm. If D1 is less than 1 mm, when the segment P' is bent toward the core, there is a risk of an area where the segment P' does not overlap to an extent that sufficient welding strength can be ensured, or an empty space (gap) will be generated. On the other hand, if D1 exceeds 6 mm, there is a risk of the uncoated portion 63 near the bending point D4 being torn by stress when the segment P' is bent. Furthermore, the height of the segment P' can be adjusted in the range of 2 mm to 10 mm. If D2 is less than 2 mm, there is a risk of an area where the segment P' does not overlap to an extent that sufficient welding strength can be ensured, or an empty space (gap) will be generated when the segment P' is bent toward the core. On the other hand, if D2 exceeds 10 mm, it is difficult to manufacture an electrode while maintaining uniform flatness of the uncoated portion 63 in the winding direction. Furthermore, the spacing pitch D3 of the divided segments P' can be adjusted within a range of 0.05 mm to 1 mm. If D3 is less than 0.05 mm, stress may be applied when the divided segments P' are bent, causing the uncoated portion 63 near the bending point D4 to break. On the other hand, if D3 exceeds 1 mm, there is a risk that when the divided segments P' are bent, there may be an area or an empty space (gap) where the divided segments P' do not overlap enough to ensure sufficient welding strength.

[0204] In the fifth embodiment, the lower interior angle θ of the trapezoid of each of the plurality of segments P' may increase from the core side toward the outer periphery. As the radius of the electrode assembly A increases, the curvature decreases. If the lower interior angle θ of each segment P' increases with the radius of the electrode assembly, stresses occurring in the radial and circumferential directions when the segment P' is bent can be alleviated. Furthermore, as the lower interior angle θ increases, the overlapping area and number of overlapping layers with the inner segment P' increase when the segment P' is bent, ensuring uniform welding strength in the radial and circumferential directions and enabling the bent surface to be formed flat.

[0205] In one example, when electrode 60e is used to manufacture an electrode assembly for a cylindrical battery with a form factor of 4680, the interior angle of segment P' may increase stepwise in the range of 60° to 85° as the radius of electrode assembly A increases from 4 mm to 22 mm.

[0206] In another example, the height of the outer plain portion B3 may decrease gradually or in steps, as in the first and second embodiments. The divided structure of the intermediate plain portion B2 may extend to the outer plain portion B3 (see dotted lines). In this case, the outer plain portion B3 may also include multiple divided segments, similar to the intermediate plain portion B2. In this case, the divided segments of the outer plain portion B3 may have a greater width and / or height and / or spacing pitch than the intermediate plain portion B2.

[0207] When the intermediate plain portion B2 includes multiple segments P, P' as in the fourth and fifth embodiments, the shape of each segment P, P' can be changed to a triangle, semicircle, semi-ellipse, parallelogram, etc.

[0208] It is also possible to change the shape of the segments P, P' for each region of the intermediate plain portion B2. For example, a round shape (e.g., semicircular, semi-elliptical, etc.) that is advantageous for stress dispersion may be applied to the section where stress is concentrated, and a polygonal shape (e.g., square, trapezoid, parallelogram, etc.) with the largest possible area may be applied to the section where stress is relatively low.

[0209] In the fourth and fifth embodiments, the division structure of the middle uncoated portion B2 can also be applied to the core-side uncoated portion B1. However, if a division structure is applied to the core-side uncoated portion B1, there is a risk of reverse forming, in which the ends of the core-side uncoated portion B1 bend toward the outer periphery when the division segments P, P' of the middle uncoated portion B2 are bent due to the radius of curvature of the core. Therefore, it is preferable not to apply a division structure to the core-side uncoated portion B1, or even if a division structure is applied, to adjust the width, height, and / or spacing of the division segments P, P' to a level that does not cause reverse forming, taking into account the radius of curvature of the core.

[0210] The electrode structure of the above-described embodiment (variant) may be applied to at least one of the first electrode and the second electrode having different polarities included in the jelly roll-type electrode assembly A. Furthermore, when the electrode structure of the embodiment (variant) is applied to one of the first electrode and the second electrode, a conventional electrode structure may be applied to the other. Furthermore, the electrode structures applied to the first electrode and the second electrode may not be the same, but may be different.

[0211] As an example, when the first electrode and the second electrode are positive and negative electrodes, respectively, any one of the embodiments (variants) may be applied to the first electrode, and a conventional electrode structure (see FIG. 1) may be applied to the second electrode.

[0212] As another example, when the first electrode and the second electrode are positive and negative electrodes, respectively, any one of the embodiments (variants) may be selectively applied to the first electrode, and any one of the embodiments (variants) may be selectively applied to the second electrode.

[0213] Hereinafter, the structure of an electrode assembly according to an embodiment of the present invention will be described in detail.

[0214] FIG. 21 is a cross-sectional view of a jelly roll-type electrode assembly A1 in which the electrode 60a of the first embodiment is applied to the first electrode (positive electrode) and the second electrode (negative electrode), taken along the Y-axis direction (winding axis direction).

[0215] The electrode assembly A1 can be manufactured by the winding method described with reference to Figure 2. For ease of explanation, the protruding structure of the uncoated portions 43a and 43b extending outward from the separator is shown in detail, and the winding structure of the first electrode, second electrode, and separator is not shown. The uncoated portion 43a protruding upward extends from the first electrode, and the uncoated portion 43b protruding downward extends from the second electrode.

[0216] The varying heights of the uncoated portions 43a, 43b are shown only schematically. That is, the heights of the uncoated portions 43a, 43b may vary irregularly depending on the cutting position of the cross section. For example, if the sides of the trapezoidal segments P, P' are cut, the height of the uncoated portions in the cross section will be lower than the height of the segments P, P'. Therefore, it should be understood that the heights of the uncoated portions 43a, 43b shown in the cross-sectional views of the electrode assembly correspond to the average height of the uncoated portions included in each winding turn (C2 in FIG. 18, D2 in FIG. 20).

[0217] Referring to Figure 21, the uncoated portion 43a of the first electrode includes a core-side uncoated portion B1 adjacent to the core of the electrode assembly A1, an outer-periphery-side uncoated portion B3 adjacent to the outer peripheral surface of the electrode assembly A1, and an intermediate uncoated portion B2 interposed between the core-side uncoated portion B1 and the outer-periphery-side uncoated portion B3.

[0218] The height (length in the Y-axis direction) of the outer uncoated portion B3 is relatively shorter than the height of the middle uncoated portion B2, which prevents the outer uncoated portion B3 from being pressed against the beading portion of the battery housing, thereby preventing an internal short circuit.

[0219] The lower uncoated portion 43b has the same structure as the upper uncoated portion 43a. In one modified embodiment, the lower uncoated portion 43b may have a conventional electrode structure or an electrode structure of another embodiment (modified embodiment).

[0220] The ends 81 of the upper uncoated portion 43a and the lower uncoated portion 43b may be bent from the outer periphery of the electrode assembly A1 toward the core, and the outer periphery uncoated portion B3 may not be substantially bent.

[0221] FIG. 22 is a cross-sectional view of a jelly roll-type electrode assembly A2 in which the electrode 60b of the second embodiment is applied to the first electrode (positive electrode) and the second electrode (negative electrode), taken along the Y-axis direction (winding axis direction).

[0222] Referring to Figure 22, the uncoated portion 43a of the first electrode includes a core-side uncoated portion B1 adjacent to the core of the electrode assembly A2, an outer-periphery-side uncoated portion B3 adjacent to the outer peripheral surface of the electrode assembly A2, and an intermediate uncoated portion B2 interposed between the core-side uncoated portion B1 and the outer-periphery-side uncoated portion B3.

[0223] The height of the outer uncoated portion B3 is relatively lower than the height of the middle uncoated portion B2, and decreases gradually or in steps from the core side to the outer periphery, thereby preventing the outer uncoated portion B3 from being pressed against the beading of the battery housing, which could cause an internal short circuit.

[0224] The lower uncoated portion 43b has the same structure as the upper uncoated portion 43a. In one modified embodiment, the lower uncoated portion 43b may have a conventional electrode structure or an electrode structure of another embodiment (modified embodiment).

[0225] The ends 91 of the upper uncoated portion 43a and the lower uncoated portion 43b may be bent from the outer periphery of the electrode assembly A2 toward the core, while the outermost portion 92 of the outer periphery uncoated portion B3 may not be substantially bent.

[0226] Figure 23 is a cross-sectional view of a jelly roll-type electrode assembly A3 in which any one of the electrodes 60c, 60d, and 60e of the third to fifth embodiments (modifications thereof) is applied to the first electrode (positive electrode) and the second electrode (negative electrode) along the Y-axis direction (winding axis direction).

[0227] Referring to Figure 23, the uncoated portion 43a of the first electrode includes a core-side uncoated portion B1 adjacent to the core of the electrode assembly A3, an outer-periphery-side uncoated portion B3 adjacent to the outer peripheral surface of the electrode assembly A3, and an intermediate uncoated portion B2 interposed between the core-side uncoated portion B1 and the outer-periphery-side uncoated portion B3.

[0228] The height of the core-side uncoated portion B1 is relatively lower than the height of the intermediate uncoated portion B2. The folding length of the innermost uncoated portion 43a in the intermediate uncoated portion B2 is equal to or shorter than the radial length R of the core-side uncoated portion B1. The folding length H corresponds to the height of the uncoated portion 43a based on the point where the uncoated portion 43a is folded (C4 in FIG. 18, D4 in FIG. 20).

[0229] Therefore, even if the middle uncoated portion B2 is bent, the bent portion does not block the cavity 102 of the core of the electrode assembly A3. If the cavity 102 is not blocked, the electrolyte injection process can be performed without any problems, improving the efficiency of the electrolyte injection. In addition, a welding jig can be inserted through the cavity 102 to easily perform the welding process between the negative electrode current collector plate and the battery housing.

[0230] The height of the outer uncoated portion B3 is relatively lower than the height of the middle uncoated portion B2, which prevents the outer uncoated portion B3 from being pressed against the beading of the battery housing, thereby preventing an internal short circuit.

[0231] In one modified embodiment, the height of the outer circumferential plain area B3 may decrease gradually or in steps, unlike in Fig. 23. Also, while the height of the intermediate plain area B2 is uniform over a portion of the outer circumferential side in Fig. 23, the height of the intermediate plain area B2 may increase gradually or in steps from the boundary between the core-side plain area B1 and the intermediate plain area B2 to the boundary between the intermediate plain area B2 and the outer circumferential plain area B3.

[0232] The lower uncoated portion 43b has the same structure as the upper uncoated portion 43a. In one modified embodiment, the lower uncoated portion 43b may have a conventional electrode structure or an electrode structure of another embodiment (modified embodiment).

[0233] The ends 101 of the upper uncoated portion 43a and the lower uncoated portion 43b may be bent from the outer periphery of the electrode assembly A3 to the core side, while the core-side uncoated portion B1 and the outer periphery-side uncoated portion B3 are not substantially bent.

[0234] When the intermediate plain portion B2 includes multiple segments, bending stress is alleviated, preventing tearing or abnormal deformation of the plain portion 43a near the bending point. Furthermore, when the width and / or height and / or spacing pitch of the segments are adjusted within the numerical ranges of the above-mentioned embodiment, the segments overlap each other to an extent that sufficient welding strength is ensured as they are bent toward the core, and no open spaces (gaps) are formed on the bending surface (surface viewed from the Y-axis direction).

[0235] FIG. 24 is a cross-sectional view of an electrode assembly A4 according to yet another embodiment of the present invention, taken along the Y-axis direction (winding axis direction).

[0236] Referring to Figure 24, electrode assembly A4 is substantially identical in configuration to electrode assembly A3 of Figure 23, except that the height of outer uncoated portion B3 is substantially the same as the height of the outermost portion of intermediate uncoated portion B2.

[0237] The outer circumferential plain portion B3 may include a plurality of segmented pieces. The configuration of the plurality of segmented pieces is similarly described in the fourth and fifth embodiments (variations).

[0238] In the electrode assembly A4, the height of the core-side uncoated region B1 is relatively lower than the height of the intermediate uncoated region B2. The bending length H of the innermost uncoated region in the intermediate uncoated region B2 is equal to or shorter than the radial length R of the core-side uncoated region B1.

[0239] Therefore, even if the middle uncoated portion B2 is bent, the bent portion does not block the cavity 112 of the electrode assembly A4 core. The unblocked cavity 112 facilitates the electrolyte injection process, improving the efficiency of the electrolyte injection process. Furthermore, a welding jig can be inserted through the cavity 112 to easily perform the welding process between the negative electrode current collector plate and the battery housing.

[0240] In one modified embodiment, the structure in which the height of the intermediate uncoated portion B2 increases gradually or in steps from the core side to the outer periphery side may be extended to the outer periphery side uncoated portion B3. In this case, the height of the uncoated portion 43a may increase gradually or in steps from the boundary between the core side uncoated portion B1 and the intermediate uncoated portion B2 to the outermost surface of the electrode assembly A4.

[0241] The lower uncoated portion 43b has the same structure as the upper uncoated portion 43a. In one modified embodiment, the lower uncoated portion 43b may have a conventional electrode structure or an electrode structure of another embodiment (modified embodiment).

[0242] The ends 111 of the upper uncoated portion 43a and the lower uncoated portion 43b may be bent from the outer periphery of the electrode assembly A4 toward the core, with the core-side uncoated portion B1 not being substantially bent.

[0243] When the middle uncoated region B2 and the outer uncoated region B3 include multiple segments, bending stress is alleviated, preventing tearing or abnormal deformation of the uncoated regions 43a, 43b near the bending points. Furthermore, when the width and / or height and / or spacing pitch of the segments are adjusted within the ranges of the above-described embodiments, the segments overlap each other to an extent that sufficient welding strength is ensured as they are bent toward the core, and no open spaces (gaps) are formed on the bending surface (surface viewed from the Y-axis direction).

[0244] FIG. 25 is a cross-sectional view of an electrode assembly A5 according to yet another embodiment of the present invention, taken along the Y-axis direction (winding axis direction).

[0245] Referring to Figure 25, electrode assembly A5 differs from electrode assembly A3 of Figure 23 only in that the height of the intermediate plain portion B2 has a pattern in which it gradually or stepwise increases and then decreases, but the other configurations are substantially identical.

[0246] Such a change in the height of the middle plain portion B2 can be achieved by adjusting the height of the staircase pattern (see FIG. 16) or the divided pieces (see FIG. 17 or 19) included in the middle plain portion B2.

[0247] In electrode assembly A5, the height of core-side uncoated region B1 is relatively lower than the height of intermediate uncoated region B2. The bending length H of the innermost uncoated region in intermediate uncoated region B2 is equal to or shorter than the radial length R of core-side uncoated region B1.

[0248] Therefore, even if the middle uncoated portion B2 is bent toward the core, the bent portion does not block the cavity 122 of the electrode assembly A5 core. If the cavity 122 is not blocked, the electrolyte injection process can be performed without any problems, improving the efficiency of the electrolyte injection process. Furthermore, a welding jig can be inserted through the cavity 122 to easily perform the welding process between the negative electrode current collector plate and the battery housing.

[0249] In addition, the height of the outer uncoated portion B3 is relatively lower than the height of the middle uncoated portion B2. This prevents the outer uncoated portion B3 from being pressed against the beading of the battery housing, which could cause an internal short circuit. In one modified embodiment, the height of the outer uncoated portion B3 may decrease gradually or in stages toward the outer periphery.

[0250] The lower uncoated portion 43b has the same structure as the upper uncoated portion 43a. In a modified embodiment, the lower uncoated portion 43b may have a conventional electrode structure or an electrode structure of another embodiment (modified embodiment).

[0251] The ends 121 of the upper uncoated portion 43a and the lower uncoated portion 43b may be bent from the outer periphery of the electrode assembly A5 to the core side, while the core-side uncoated portion B1 and the outer periphery-side uncoated portion B3 are not substantially bent.

[0252] When the middle plain portion B2 includes multiple segments, bending stress is alleviated, preventing tearing or abnormal deformation of the plain portions 43a, 43b. Furthermore, when the width and / or height and / or spacing pitch of the segments are adjusted within the ranges of the above-described embodiments, the segments overlap each other to an extent that sufficient welding strength is ensured when they are bent toward the core, and no open spaces (gaps) are formed on the bent surfaces (surfaces viewed from the Y-axis direction).

[0253] FIG. 26 is a cross-sectional view of an electrode assembly A6 according to yet another embodiment of the present invention, taken along the Y-axis direction (winding axis direction).

[0254] Referring to Figure 26, electrode assembly A6 differs from electrode assembly A5 of Figure 25 in that the height of outer uncoated portion B3 gradually or stepwise decreases from the boundary between outer uncoated portion B3 and intermediate uncoated portion B2 toward the outermost surface of electrode assembly A6; other configurations are substantially identical.

[0255] This height variation of the outer uncoated portion B3 can be achieved by extending the staircase pattern (see FIG. 16) included in the intermediate uncoated portion B2 to the outer uncoated portion B3 and gradually or stepwise decreasing the height of the pattern toward the outer periphery. In another modified embodiment, the height variation of the outer uncoated portion B3 can be achieved by extending the segmented structure of the intermediate uncoated portion B2 to the outer periphery uncoated portion B3 and gradually or stepwise decreasing the height of the segmented structure toward the outer periphery.

[0256] In electrode assembly A6, the height of core-side uncoated portion B1 is relatively lower than the height of intermediate uncoated portion B2. The bending length H of the innermost uncoated portion in intermediate uncoated portion B2 is equal to or shorter than the radial length R of core-side uncoated portion B1.

[0257] Therefore, even if the middle uncoated portion B2 is bent toward the core, the bent portion does not block the cavity 132 of the electrode assembly A5 core. If the cavity 132 is not blocked, the electrolyte injection process can be performed without any problems, improving the efficiency of the electrolyte injection process. Furthermore, a welding jig can be inserted through the cavity 132 to easily perform the welding process between the negative electrode current collector plate and the battery housing.

[0258] The lower uncoated portion 43b has the same structure as the upper uncoated portion 43a. In one modified embodiment, the lower uncoated portion 43b may have a conventional electrode structure or an electrode structure of another embodiment (modified embodiment).

[0259] The ends 131 of the upper uncoated portion 43a and the lower uncoated portion 43b may be bent from the outer periphery of the electrode assembly A6 toward the core, with the core-side uncoated portion B1 not being substantially bent.

[0260] When the middle uncoated region B2 and the outer uncoated region B3 include multiple segments, bending stress is alleviated, preventing tearing or abnormal deformation of the uncoated regions 43a, 43b near the bending points. Furthermore, when the width and / or height and / or spacing pitch of the segments are adjusted within the ranges of the above-described embodiments, the segments overlap each other to an extent that sufficient welding strength is ensured as they are bent toward the core, and no open spaces (gaps) are formed on the bending surface (surface viewed from the Y-axis direction).

[0261] Various electrode assembly structures according to embodiments of the present invention are applicable to jelly-roll type cylindrical batteries.

[0262] Preferably, the cylindrical battery may be, for example, a cylindrical battery having a form factor ratio (defined as the diameter of a cylindrical battery divided by its height, i.e., the ratio of height (H) to diameter (Φ)) greater than about 0.4.

[0263] A cylindrical battery according to an embodiment of the present invention may be, for example, a 46110 battery, a 4875 battery, a 48110 battery, a 4880 battery, or a 4680 battery.

[0264] When an electrode assembly having a tabless structure is applied to a cylindrical battery with a form factor ratio exceeding 0.4, the uncoated portion is easily torn due to the large radial stress applied when the uncoated portion is bent. Furthermore, when welding a current collector plate to the bent surface of the uncoated portion, the number of overlapping layers of the uncoated portion must be increased to ensure sufficient welding strength and reduce resistance. These requirements can be met by the electrode and electrode assembly according to an embodiment (variant) of the present invention.

[0265] Hereinafter, a cylindrical battery according to an embodiment of the present invention will be described in detail.

[0266] FIG. 27 is a cross-sectional view of a cylindrical battery 140 according to an embodiment of the present invention taken along the Y-axis direction.

[0267] Referring to FIG. 27, a cylindrical battery 140 according to one embodiment of the present invention includes an electrode assembly 141 including a first electrode, a separator, and a second electrode, a battery housing 142 that houses the electrode assembly 141, and a seal 143 that seals the open end of the battery housing 142.

[0268] The battery housing 142 is a cylindrical container with an opening at the top. The battery housing 142 is made of a conductive metal material such as aluminum or steel. The battery housing 142 accommodates the electrode assembly 141 in the inner space through the opening at the top, along with the electrolyte.

[0269] The electrode assembly 141 may have a jelly roll structure. As shown in FIG. 2, the electrode assembly 141 may be manufactured by stacking a lower separator, a first electrode, an upper separator, and a second electrode in order at least once, and winding the stack around a winding center C.

[0270] The first electrode and the second electrode have opposite polarities. That is, one has a positive polarity and the other has a negative polarity. At least one of the first electrode and the second electrode may have an electrode structure according to the above-described embodiment (variant). The other of the first electrode and the second electrode may have a conventional electrode structure or an electrode structure according to the embodiment (variant).

[0271] An uncoated portion 146a of the first electrode and an uncoated portion 146b of the second electrode protrude from the top and bottom of the electrode assembly 141, respectively. The first electrode has the electrode structure of the first embodiment (variant). Therefore, the height of the uncoated portion 146a of the first electrode, the outer uncoated portion B3, is lower than the height of the uncoated portions of other parts. The outer uncoated portion B3 is spaced a predetermined distance from the inner circumferential surface of the battery housing 142, particularly the beading portion 147. Therefore, the outer uncoated portion B3 of the first electrode does not contact the battery housing 142, which is electrically connected to the second electrode, preventing an internal short circuit in the battery 140.

[0272] The uncoated portions 146b of the second electrode have the same height. In a variant, the uncoated portions 146b of the second electrode may have the same structure as the uncoated portions 146a of the first electrode. In another variant, the uncoated portions 146b of the second electrode may selectively have the structure of the uncoated portions of the electrodes according to the embodiment (variant).

[0273] The sealing body 143 may include a cap plate 143a, a first gasket 143b having insulating properties and providing airtightness between the cap plate 143a and the battery housing 142, and a connecting plate 143c electrically and mechanically connected to the cap plate 143a.

[0274] The cap plate 143a is a component made of a conductive metal material and covers the upper opening of the battery housing 142. The cap plate 143a is electrically connected to the uncoated portion 146a of the first electrode and is electrically insulated from the battery housing 142 via a first gasket 143b. Therefore, the cap plate 143a can function as a first electrode terminal of the cylindrical battery 140.

[0275] The cap plate 143a is placed on a beading portion 147 formed on the battery housing 142 and fixed by a crimping portion 148. A first gasket 143b may be interposed between the cap plate 143a and the crimping portion 148 to ensure airtightness of the battery housing 142 and to provide electrical insulation between the battery housing 142 and the cap plate 143a. The cap plate 143a may have a protrusion 143d formed to protrude upward from the center thereof.

[0276] The battery housing 142 is electrically connected to the uncoated portion 146b of the second electrode. Therefore, the battery housing 142 has the same polarity as the second electrode. If the second electrode has a negative polarity, the battery housing 142 also has a negative polarity.

[0277] The battery housing 142 has a beading portion 147 and a crimping portion 148 at its upper end. The beading portion 147 is formed by pressing in around the outer periphery of the battery housing 142. The beading portion 147 prevents the electrode assembly 141 housed inside the battery housing 142 from slipping out of the upper opening of the battery housing 142, and can also function as a support on which the sealing body 143 is placed.

[0278] The inner circumferential surface of the beading portion 147 is spaced a predetermined distance from the outer uncoated portion B3 of the first electrode. More specifically, the lower end of the inner circumferential surface of the beading portion 147 is spaced a predetermined distance from the outer uncoated portion B3 of the first electrode. Furthermore, because the height of the outer uncoated portion B3 is low, the outer uncoated portion B3 is substantially unaffected when the battery housing 142 is pressed in from the outside to form the beading portion 147. Therefore, the outer uncoated portion B3 is not pressed by other components such as the beading portion 147, which prevents partial deformation of the electrode assembly 141 and internal short circuits in the cylindrical battery 140.

[0279] Preferably, the relationship "D1≦D2" is satisfied, where D1 is the pressing depth of the beading portion 147 and D2 is the radial distance from the inner circumferential surface of the battery housing 142 to the boundary between the outer uncoated portion B3 and the intermediate uncoated portion B2. In this case, damage to the outer uncoated portion B3 is substantially prevented when the battery housing 142 is pressed in to form the beading portion 147.

[0280] The crimping portion 148 is formed on the upper portion of the beading portion 147. The crimping portion 148 is extended and bent to enclose the outer circumferential surface of the cap plate 143a disposed on the beading portion 147 and a portion of the upper surface of the cap plate 143a.

[0281] The cylindrical battery 140 may further include a first current collector 144 and / or a second current collector 145 and / or an insulator 146 .

[0282] The first current collecting plate 144 is coupled to the upper part of the electrode assembly 141. The first current collecting plate 144 is made of a conductive metal material such as aluminum, copper, or nickel, and is electrically connected to the uncoated portion 146a of the first electrode. A lead 149 may be connected to the first current collecting plate 144. The lead 149 may extend above the electrode assembly 141 and be coupled to the connection plate 143c, or may be directly coupled to the lower surface of the cap plate 143a. The lead 149 may be coupled to other components by welding.

[0283] Preferably, the first current collector 144 may be integrally formed with the lead 149. In this case, the lead 149 may be in the form of a long plate extending outward from the center of the first current collector 144.

[0284] The first current collecting plate 144 may have a plurality of radially formed concaves and convexes (not shown) on its lower surface. When the radial concaves and convexes are provided, the first current collecting plate 144 may be pressed against the concaves and convexes to press the uncoated portion 146a of the first electrode into the concaves and convexes.

[0285] The first current collecting plate 144 is coupled to an end of the uncoated portion 146a of the first electrode. The uncoated portion 146a and the first current collecting plate 144 may be coupled by, for example, laser welding. Laser welding may be performed by partially melting the base material of the current collecting plate. In a modified embodiment, the first current collecting plate 144 and the uncoated portion 146a may be welded to each other using solder. In this case, the solder may have a lower melting point than the first current collecting plate 144 and the uncoated portion 146a. Laser welding may be replaced by resistance welding, ultrasonic welding, or the like.

[0286] A second current collecting plate 145 may be coupled to the bottom surface of the electrode assembly 141. One surface of the second current collecting plate 145 may be coupled to the uncoated portion 146b of the second electrode by welding, and the other surface may be coupled to the inner bottom surface of the battery housing 142 by welding. The coupling structure between the second current collecting plate 145 and the uncoated portion 146b of the second electrode may be substantially the same as the coupling structure between the first current collecting plate 144 and the uncoated portion 146a of the first electrode.

[0287] The uncoated portions (first uncoated portion 146a, second uncoated portion 146b) are not limited to the structures shown in the drawings. Therefore, the uncoated portions 146a, 146b may selectively have the structure of an uncoated portion of an electrode according to an embodiment (variant) as well as the structure of a conventional uncoated portion.

[0288] The insulator 146 may cover the first current collector 144. By covering the first current collector 144 on the upper surface of the first current collector 144, the insulator 146 can prevent direct contact between the first current collector 144 and the inner circumferential surface of the battery housing 142.

[0289] The insulator 146 has a lead hole 151 through which the lead 149 extending upward from the first current collector plate 144 is drawn out. The lead 149 is drawn out upward through the lead hole 151 and is coupled to the lower surface of the connecting plate 143c or the lower surface of the cap plate 143a.

[0290] The peripheral region of the insulator 146 may be interposed between the first current collecting plate 144 and the beading portion 147 to fix the combination of the electrode assembly 141 and the first current collecting plate 144. This limits the movement of the combination of the electrode assembly 141 and the first current collecting plate 144 in the height direction of the battery 140, thereby improving the assembly stability of the battery 140.

[0291] The insulator 146 may be made of an insulating polymer resin. For example, the insulator 146 may be made of polyethylene, polypropylene, polyimide, or polybutylene terephthalate.

[0292] The battery housing 142 may further include a vent 152 formed on its bottom surface. The vent 152 corresponds to a region on the bottom surface of the battery housing 142 that is thinner than the surrounding region. The vent 152 is structurally weaker than the surrounding region. Therefore, if an abnormality occurs in the cylindrical battery 140 and the internal pressure increases above a certain level, the vent 152 may burst, causing gas generated inside the battery housing 142 to be released to the outside.

[0293] The vents 152 may be formed continuously or discontinuously in a circle on the underside of the battery housing 142. In a variant, the vents 152 may be formed in a linear pattern or other patterns.

[0294] FIG. 28 is a cross-sectional view of a cylindrical battery 150 according to another embodiment of the present invention, taken along the Y-axis direction.

[0295] Referring to FIG. 28, the cylindrical battery 150 is substantially identical in configuration to the cylindrical battery 140 of FIG. 27 except that the electrode structure of the second embodiment (variant) is adopted for the uncoated portion 146a of the first electrode.

[0296] 28, the uncoated portion 146a of the first electrode may have a shape in which the height of the outer uncoated portion B3 gradually or stepwise decreases toward the inner circumferential surface of the battery housing 142. Preferably, an imaginary line connecting the uppermost ends of the outer uncoated portions B3 may have the same or similar shape as the inner circumferential surface of the beading portion 147.

[0297] The outer uncoated portion B3 has an inclined surface, which prevents the outer uncoated portion B3 from being pressed and damaged by the beading portion 147 when the battery housing 142 is pressed in to form the beading portion 147. This also prevents the outer uncoated portion B3 from coming into contact with the battery housing 142 of the opposite polarity, which could cause an internal short circuit.

[0298] Other configurations of the cylindrical battery 150 are substantially the same as those of the above-described embodiment (variant).

[0299] The uncoated portions (first uncoated portion 146a, second uncoated portion 146b) are not limited to the structures shown in the drawings. Therefore, the uncoated portions 146a, 146b may selectively have the structure of an uncoated portion of an electrode according to an embodiment (variant) as well as the structure of a conventional uncoated portion.

[0300] FIG. 29 is a cross-sectional view of a cylindrical battery 160 according to yet another embodiment of the present invention, taken along the Y-axis direction.

[0301] Referring to FIG. 29, the cylindrical battery 160 is substantially identical in configuration to the cylindrical batteries 140 and 150 described above, except that the lead 149 connected to the first current collector 144 is directly connected to the cap plate 143a of the sealing body 143 through the lead hole 151 of the insulator 146, and the insulator 146 and the first current collector 144 are closely attached to the underside of the cap plate 143a.

[0302] In the cylindrical battery 160, the diameter of the first current collector 144 and the outermost diameter of the middle uncoated portion B2 are smaller than the smallest inner diameter of the battery housing 142. In addition, the diameter of the first current collector 144 may be the same as or larger than the outermost diameter of the middle uncoated portion B2.

[0303] Specifically, the minimum inner diameter of the battery housing 142 may correspond to the inner diameter of the battery housing 142 at the position where the beading portion 147 is formed. In this case, the outermost diameters of the first current collecting plate 144 and the middle uncoated portion B2 are smaller than the inner diameter of the battery housing 142 at the position where the beading portion 147 is formed. In addition, the diameter of the first current collecting plate 144 may be the same as or larger than the outermost diameter of the middle uncoated portion B2. The peripheral region of the insulator 146 may be bent downward and interposed between the outer uncoated portion B3 and the beading portion 147 to fix the combination of the electrode assembly 141 and the first current collecting plate 144.

[0304] Preferably, the insulator 146 includes a portion covering the outer uncoated portion B3 and a portion covering the first current collecting plate 144, and the portion connecting these two portions may be curved together to correspond to the curved shape of the beading portion 147. The insulator 146 may insulate the outer uncoated portion B3 from the inner circumferential surface of the beading portion 147, and may also insulate the first current collecting plate 144 from the inner circumferential surface of the beading portion 147.

[0305] The first current collecting plate 144 may be positioned higher than the lower end of the beading portion 147 and may be coupled to the core-side uncoated portion B1 and the middle uncoated portion B2. In this case, the pressing depth D1 of the beading portion 147 is equal to or smaller than the distance D2 from the inner circumferential surface of the battery housing 142 to the boundary between the outer-side uncoated portion B3 and the middle uncoated portion B2. Therefore, the core-side uncoated portion B1 and the middle uncoated portion B2, and the first current collecting plate 144 coupled thereto, may be positioned higher than the lower end of the beading portion 147. The lower end of the beading portion 147 refers to the bending point B between the beading portion 147 and the portion of the battery housing 142 that houses the electrode assembly 141.

[0306] Because the core-side uncoated region B1 and the middle uncoated region B2 occupy the radially inner space of the beading region 147, the empty space between the electrode assembly 141 and the cap plate 143a is minimized. Furthermore, the connecting plate 143c, which was previously located in the empty space between the electrode assembly 141 and the cap plate 143a, is eliminated. Therefore, the lead 149 of the first current collector 144 can be directly coupled to the underside of the cap plate 143a. This structure reduces the empty space within the battery, allowing the energy density to be maximized by the reduced empty space.

[0307] In the cylindrical battery 160, the first current collector plate 144 and the second current collector plate 145 may be welded to the ends of the first uncoated portion 146a and the second uncoated portion 146b, respectively, similar to the above-described embodiment.

[0308] The uncoated portions 146a and 146b are not limited to the illustrated structure, and may selectively have the structure of an uncoated portion of an electrode according to an embodiment (variant) as well as the structure of a conventional uncoated portion.

[0309] FIG. 30 is a cross-sectional view of a cylindrical battery 170 according to yet another embodiment of the present invention, taken along the Y-axis direction.

[0310] Referring to FIG. 30, the cylindrical battery 170 differs from the cylindrical battery 140 shown in FIG. 27 in that the structure of the electrode assembly is substantially the same, but other structures except for the electrode assembly have been changed.

[0311] Specifically, the cylindrical battery 170 includes a battery housing 171 through which an external terminal 172 is inserted. The external terminal 172 is attached to the closed surface (top surface in the drawing) of the battery housing 171. The external terminal 172 is riveted into a through-hole in the battery housing 171 with an insulating second gasket 173 interposed therebetween. The external terminal 172 is exposed to the outside in the direction opposite to the direction of gravity.

[0312] The external terminal 172 includes a terminal exposing portion 172a and a terminal inserting portion 172b. The terminal exposing portion 172a is exposed to the outside of the closed surface of the battery housing 171. The terminal exposing portion 172a may be located approximately at the center of the closed surface of the battery housing 171. The maximum diameter of the terminal exposing portion 172a may be larger than the maximum diameter of the through-hole formed in the battery housing 171. The terminal inserting portion 172b may penetrate approximately the center of the closed surface of the battery housing 171 to be electrically connected to the uncoated portion 146a of the first electrode. The terminal inserting portion 172b may be rivet-connected to the inner surface of the battery housing 171. That is, the lower edge of the terminal inserting portion 172b may be bent toward the inner surface of the battery housing 171. The maximum diameter of the lower portion of the terminal inserting portion 172b may be larger than the maximum diameter of the through-hole in the battery housing 171.

[0313] The lower end surface of the terminal insertion portion 172b may be welded to the first current collecting plate 144 connected to the uncoated portion 146a of the first electrode. An insulator 174 made of an insulating material may be interposed between the first current collecting plate 144 and the inner surface of the battery housing 171. The insulator 174 covers the upper portion of the first current collecting plate 144 and the upper peripheral edge of the electrode assembly 141. This prevents the outer uncoated portion B3 of the electrode assembly 141 from coming into contact with the inner surface of the battery housing 171 having the opposite polarity, causing a short circuit. The terminal insertion portion 172b of the external terminal 172 may be welded to the first current collecting plate 144 by passing through the insulator 174.

[0314] The second gasket 173 is interposed between the battery housing 171 and the external terminal 172 to prevent electrical contact between the battery housing 171 and the external terminal 172, which have opposite polarities. This allows the upper surface of the battery housing 171, which has a substantially flat shape, to function as the second electrode terminal of the cylindrical battery 170.

[0315] The second gasket 173 includes a gasket exposing portion 173a and a gasket inserting portion 173b. The gasket exposing portion 173a is interposed between the terminal exposing portion 172a of the external terminal 172 and the battery housing 171. The gasket inserting portion 173b is interposed between the terminal inserting portion 172b of the external terminal 172 and the battery housing 171. The gasket inserting portion 173b may be deformed when the terminal inserting portion 172b is riveted, thereby adhering closely to the inner surface of the battery housing 171. The second gasket 173 may be made of, for example, an insulating polymer resin.

[0316] The gasket exposing portion 173a of the second gasket 173 may extend to cover the outer peripheral surface of the terminal exposing portion 172a of the external terminal 172. When the second gasket 173 covers the outer peripheral surface of the external terminal 172, it is possible to prevent a short circuit from occurring during the process of connecting an electrical connection component such as a bus bar to the upper surface of the battery housing 171 and / or the external terminal 172. Although not shown, the gasket exposing portion 173a may extend to cover not only the outer peripheral surface of the terminal exposing portion 172a but also a portion of the upper surface.

[0317] When the second gasket 173 is made of a polymer resin, the second gasket 173 may be joined to the battery housing 171 and the external terminal 172 by heat sealing. In this case, the airtightness at the joining interface between the second gasket 173 and the external terminal 172 and at the joining interface between the second gasket 173 and the battery housing 171 is strengthened. Meanwhile, when the gasket exposing portion 173a of the second gasket 173 extends to the upper surface of the terminal exposing portion 172a, the external terminal 172 may be joined integrally with the second gasket 173 by insert injection.

[0318] A region 175 on the upper surface of the battery housing 171 excluding the region occupied by the external terminal 172 and the second gasket 173 corresponds to a second electrode terminal having a polarity opposite to that of the external terminal 172 .

[0319] The second current collecting plate 176 is coupled to the lower part of the electrode assembly 141. The second current collecting plate 176 is made of a conductive metal material such as aluminum, steel, copper, or nickel, and is electrically connected to the uncoated portion 146b of the second electrode.

[0320] Preferably, the second current collecting plate 176 is electrically connected to the battery housing 171. Therefore, the second current collecting plate 176 may be fixed with at least a portion of its peripheral edge interposed between the inner surface of the battery housing 171 and the first gasket 178b. In one example, at least a portion of the peripheral edge of the second current collecting plate 176 may be fixed to the beading portion 180 by welding while being supported on a lower end surface of the beading portion 180 formed at the lower end of the battery housing 171. In a modified example, at least a portion of the peripheral edge of the second current collecting plate 176 may be directly welded to the inner wall surface of the battery housing 171.

[0321] The second current collecting plate 176 may have a plurality of projections and recesses (not shown) formed radially on the surface facing the non-coated portion 146b. When the projections and recesses are formed, the second current collecting plate 176 may be pressed against the projections and recesses to press the non-coated portion 146b into the projections and recesses.

[0322] Preferably, the second current collector plate 176 and the end of the non-coating portion 146b can be joined by welding, for example, laser welding.

[0323] The sealing body 178 that seals the lower open end of the battery housing 171 includes a cap plate 178a and a first gasket 178b. The first gasket 178b electrically isolates the cap plate 178a from the battery housing 171. A crimping portion 181 secures the periphery of the cap plate 178a and the first gasket 178b together. The cap plate 178a is provided with a vent portion 179. The configuration of the vent portion 179 is substantially the same as in the above-described embodiment (variant).

[0324] Preferably, the cap plate 178a is made of a conductive metal material. However, the cap plate 178a does not have electrical polarity because the first gasket 178b is interposed between the cap plate 178a and the battery housing 171. The seal 178 seals the lower open end of the battery housing 171 and functions to release gas when the internal pressure of the battery 170 exceeds a critical value.

[0325] Preferably, the external terminal 172 electrically connected to the uncoated portion 146a of the first electrode is used as the first electrode terminal. Furthermore, a portion 175 of the upper surface of the battery housing 171, excluding the external terminal 172, electrically connected to the uncoated portion 146b of the second electrode via the second current collector 176 is used as a second electrode terminal having the opposite polarity to the first electrode terminal. When two electrode terminals are located on the upper portion of the cylindrical battery 170, electrical connection components such as bus bars can be disposed on only one side of the cylindrical battery 170. This simplifies the battery pack structure and improves energy density. Furthermore, the portion 175 used as the second electrode terminal has a substantially flat shape, ensuring a sufficient contact area when connecting electrical connection components such as bus bars. This allows the cylindrical battery 170 to reduce resistance at the contact points of the electrical connection components to a desirable level.

[0326] The structure of the electrode assembly 141 and the structure of the uncoated portion are not limited to those shown in the drawings, and may be replaced with the structures of the above-described embodiments (variations).

[0327] FIG. 31 is a cross-sectional view of a cylindrical battery 180 according to yet another embodiment of the present invention, taken along the Y-axis direction.

[0328] Referring to FIG. 31, the cylindrical battery 180 has substantially the same structure as the cylindrical battery 150 shown in FIG. 28 in terms of the electrode assembly 141, and other configurations except for the electrode assembly 141 are substantially the same as the cylindrical battery 170 shown in FIG. 30.

[0329] Therefore, the configurations of the embodiments (variations) of the cylindrical batteries 150 and 170 can be similarly applied to the cylindrical battery 180.

[0330] Furthermore, the structure of the electrode assembly 141 and the structure of the uncoated portion are not limited to those shown in the drawings, and may be replaced with the structures of the above-described embodiments (variations).

[0331] FIG. 32 is a cross-sectional view of a cylindrical battery 190 according to yet another embodiment of the present invention, taken along the Y-axis direction.

[0332] Referring to FIG. 32, a cylindrical battery 190 includes the electrode assembly A4 shown in FIG. 24, and other configurations except for the electrode assembly A4 are substantially the same as the cylindrical battery 140 shown in FIG.

[0333] 32, uncoated portions 146a and 146b of electrode assembly A4 are bent from the outer periphery toward the core. At this time, core-side uncoated portion B1 is not substantially bent because it is lower than the other portions. First current collecting plate 144 may be welded to the bent surface of uncoated portion 146a, and second current collecting plate 145 may be welded to the bent surface of uncoated portion 146b. When uncoated portions 146a and 146b are bent, the bent surfaces may overlap in multiple directions along the Y-axis, forming the upper and lower portions of electrode assembly A4.

[0334] In electrode assembly A4, the height of core-side uncoated region B1 is relatively lower than the other regions. Also, as shown in Figure 24, the bending length H of the innermost uncoated region in intermediate uncoated region B2 is equal to or shorter than the radial length R of core-side uncoated region B1.

[0335] Therefore, even if the non-coating portion 146a is bent toward the core side, the cavity 112 in the core of the electrode assembly A4 is not closed, but can be open at the top (see the dashed-dotted circle).

[0336] If the cavity 112 is not blocked, the electrolyte injection process can be carried out without any problems, improving the efficiency of the electrolyte injection. In addition, a welding jig can be inserted through the cavity 112 to easily weld the second current collector plate 145 and the battery housing 142 together.

[0337] When the plain portions 146a, 146b have a divided structure, if the width and / or height and / or spacing pitch of the divided pieces are adjusted to satisfy the numerical range of the above-mentioned embodiment, when the divided pieces are bent, the divided pieces overlap each other to an extent that sufficient welding strength can be ensured, and no open space (gap) is formed on the bent surface.

[0338] The structure of the uncoated portions 146a, 146b may be modified without limitation to the structure according to the above-described embodiment (variant), and there is no restriction on applying a conventional uncoated portion structure to either one of the uncoated portions 146a, 146b.

[0339] FIG. 33 is a cross-sectional view of a cylindrical battery 200 according to yet another embodiment of the present invention, taken along the Y-axis direction.

[0340] Referring to FIG. 33, a cylindrical battery 200 includes the electrode assembly A4 shown in FIG. 24, and other configurations except for the electrode assembly A4 are substantially the same as the cylindrical battery 180 shown in FIG.

[0341] 33, uncoated portions 146a and 146b of electrode assembly A4 are bent from the outer periphery toward the core. At this time, core-side uncoated portion B1 is not substantially bent because its height is lower than the other portions. First current collector 144 may be welded to the bent surface of uncoated portion 146a, and second current collector 176 may be welded to the bent surface of uncoated portion 146b.

[0342] In electrode assembly A4, the height of core-side uncoated region B1 is relatively lower than the other regions. Also, as shown in Figure 24, the bending length H of the innermost uncoated region in intermediate uncoated region B2 is equal to or shorter than the radial length R of core-side uncoated region B1.

[0343] Therefore, even if the uncoated portions 146a and 146b are bent toward the core side, the cavity 112 in the core of the electrode assembly A4 is not closed and can be open at the top (see the dotted circle).

[0344] If the cavity 112 is not blocked, the electrolyte injection process can be carried out without any problems, improving the efficiency of the electrolyte injection. In addition, a welding jig can be inserted through the cavity 112 to easily perform the welding process between the second current collector plate 176 and the battery housing 171.

[0345] When the plain portions 146a, 146b have a divided structure, if the width and / or height and / or spacing pitch of the divided pieces are adjusted to satisfy the numerical range of the above-mentioned embodiment, when the divided pieces are bent, the divided pieces overlap each other to an extent that sufficient welding strength can be ensured, and no open space (gap) is formed on the bent surface.

[0346] The structure of the uncoated portions 146a, 146b may be modified without limitation to the structure according to the above-described embodiment (variant), and there is no restriction on applying a conventional uncoated portion structure to either one of the uncoated portions 146a, 146b.

[0347] FIG. 34 is a cross-sectional view of a cylindrical battery 210 according to yet another embodiment of the present invention, taken along the Y-axis direction.

[0348] Referring to FIG. 34, a cylindrical battery 210 includes the electrode assembly A3 shown in FIG. 23, and other configurations except for the electrode assembly A3 are substantially the same as the cylindrical battery 140 shown in FIG.

[0349] Preferably, the uncoated portions 146a and 146b of the electrode assembly A3 are bent from the outer periphery toward the core. At this time, the core-side uncoated portion B1 and the outer periphery-side uncoated portion B3 of the uncoated portion 146a are not substantially bent because they are lower in height than the other portions. The same applies to the uncoated portion 146b. The first current collecting plate 144 may be welded to the bent surface of the uncoated portion 146a, and the second current collecting plate 145 may be welded to the bent surface of the uncoated portion 146b.

[0350] The height of the core-side uncoated area B1 is relatively lower than that of the intermediate uncoated area B2. Also, as shown in Figure 23, the bending length H of the innermost uncoated area in the intermediate uncoated area B2 is equal to or shorter than the radial length R of the core-side uncoated area B1.

[0351] Therefore, even if the uncoated portions 146a and 146b are bent toward the core side, the cavity 102 in the core of the electrode assembly A3 is not closed, but can be open at the top (see the dotted circle).

[0352] If the cavity 102 is not blocked, the electrolyte injection process can be performed without any problems, improving the efficiency of the electrolyte injection process. In addition, a welding jig can be inserted through the cavity to easily perform the welding process between the second current collector plate 145 and the battery housing 142.

[0353] In addition, the height of outer uncoated portion B3 is relatively lower than that of intermediate uncoated portion B2. Therefore, when uncoated portion 146a is bent, outer uncoated portion B3 is not substantially bent. In addition, outer uncoated portion B3 is sufficiently spaced apart from beading portion 147, which solves the problem of outer uncoated portion B3 being damaged when beading portion 147 is pressed in.

[0354] When the plain portions 146a, 146b have a divided structure, if the width and / or height and / or spacing pitch of the divided pieces are adjusted to satisfy the numerical range of the above-mentioned embodiment, when the divided pieces are bent, the divided pieces overlap each other to an extent that sufficient welding strength can be ensured, and no open space (gap) is formed on the bent surface.

[0355] The structure of the uncoated portions 146a, 146b may be modified without limitation to the structure according to the above-described embodiment (variant), and there is no restriction on applying a conventional uncoated portion structure to either one of the uncoated portions 146a, 146b.

[0356] FIG. 35 is a cross-sectional view of a cylindrical battery 220 according to yet another embodiment of the present invention, taken along the Y-axis direction.

[0357] 35, a cylindrical battery 220 includes the electrode assembly A3 shown in FIG. 23, and other configurations except for the electrode assembly A3 are substantially the same as the cylindrical battery 180 shown in FIG.

[0358] Preferably, the uncoated portions 146a and 146b of the electrode assembly A3 are bent from the outer periphery toward the core. At this time, the core-side uncoated portion B1 of the uncoated portion 146a is not substantially bent because its height is lower than the other portions. The same applies to the uncoated portion 146b. The first current collecting plate 144 may be welded to the bent surface of the uncoated portion 146a, and the second current collecting plate 176 may be welded to the bent surface of the uncoated portion 146b.

[0359] In electrode assembly A3, the height of core-side uncoated region B1 is relatively lower than that of intermediate uncoated region B2. Also, as shown in Figure 23, the bending length H of the innermost uncoated region in intermediate uncoated region B2 is equal to or shorter than the radial length R of core-side uncoated region B1.

[0360] Therefore, even if the non-coating portion 146a is bent toward the core side, the cavity 102 in the core of the electrode assembly A3 is not closed, and can be open at the top (see the dotted circle).

[0361] If the cavity 102 is not blocked, the electrolyte injection process can be carried out without any problems, improving the efficiency of the electrolyte injection. In addition, a welding jig can be inserted through the cavity 102 to easily perform the welding process between the second current collector plate 176 and the battery housing 171.

[0362] Furthermore, the height of outer uncoated portion B3 of uncoated portion 146a is relatively lower than that of intermediate uncoated portion B2. Therefore, when uncoated portion 146a is folded, outer uncoated portion B3 is not substantially folded. The same applies to uncoated portion 146b.

[0363] When the plain portions 146a, 146b have a divided structure, if the width and / or height and / or spacing pitch of the divided pieces are adjusted to satisfy the numerical range of the above-mentioned embodiment, when the divided pieces are bent, the divided pieces overlap each other to an extent that sufficient welding strength can be ensured, and no open space (gap) is formed on the bent surface.

[0364] The structure of the uncoated portions 146a, 146b may be modified without limitation to the structure according to the above-described embodiment (variant), and there is no restriction on applying a conventional uncoated portion structure to either one of the uncoated portions 146a, 146b.

[0365] Although not shown, the spacer 50 of Fig. 5 may be provided below the electrode assemblies shown in Figs. 30, 31, 33, and 35. In this case, the lower structure of the cylindrical batteries 170, 180, 200, and 220 may be replaced with the structure shown in Fig. 5. Also, the structure of the current collecting plate 35 shown in Fig. 6 may be applied to the second current collecting plate 176, and the first gasket 178b may be replaced with the sealing portion 52 of the spacer 50.

[0366] The cylindrical battery according to the above-described embodiment (variant) can be used to manufacture a battery pack (see FIG. 12), and the battery pack can be mounted in a vehicle (see FIG. 13).

[0367] According to an embodiment of the present invention, the uncoated portions protruding from the upper and lower sides of the electrode assembly are used as electrode tabs, thereby reducing the internal resistance of the cylindrical battery and increasing the energy density.

[0368] Furthermore, according to an embodiment of the present invention, by improving the structure of the uncoated portion of the electrode assembly, the electrode assembly and the inner surface of the battery housing do not interfere with each other during the process of forming the beading portion of the battery housing, thereby preventing an internal short circuit in a cylindrical battery due to partial deformation of the electrode assembly.

[0369] Furthermore, according to an embodiment of the present invention, the structure of the uncoated portion of the electrode assembly is improved to prevent the uncoated portion from tearing near the bending point when the uncoated portion is bent, and the number of overlapping layers of the uncoated portion is sufficiently increased to improve weld strength.

[0370] Furthermore, according to an embodiment of the present invention, the structure of the uncoated portion adjacent to the core of the electrode assembly is improved to prevent the cavity in the core of the electrode assembly from being blocked when the uncoated portion is bent, facilitating the electrolyte injection process and the welding process of the battery housing and the current collector plate.

[0371] Furthermore, according to an embodiment of the present invention, it is possible to provide a cylindrical battery having a structure in which internal resistance is low, internal short circuits are prevented, and welding strength between the current collector plate and the uncoated portion is improved, as well as a battery pack and a vehicle including the same.

[0372] Hereinafter, an embodiment of a positive electrode active material used in a cylindrical battery according to an embodiment of the present invention will be described.

[0373] In the embodiments, the term "primary particle" refers to a particle unit that does not appear to have grain boundaries when observed at a magnification of 5,000 to 20,000 times using a scanning electron microscope (SEM) or an electron backscatter diffraction (EBSD) pattern analyzer. The term "average particle size of primary particles" refers to the arithmetic mean value calculated after measuring the particle sizes of primary particles observed in an SEM or EBSD image. The term "secondary particle" refers to a particle formed by the aggregation of multiple primary particles. In the present invention, a secondary particle formed by the aggregation of 10 or fewer primary particles is referred to as a "quasi-single particle" to distinguish it from conventional secondary particles formed by the aggregation of tens to hundreds of primary particles.

[0374] 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 adsorbed at liquid nitrogen temperature (77 K) using a Belsorp-mini II manufactured by Bel Japan.

[0375] 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 a laser diffraction method. Specifically, D min is the minimum particle size in the volume cumulative distribution, and D 50 is the particle size when the cumulative volume is 50%, and D max is the maximum particle size 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. When the positive electrode active material is a quasi-single particle, D 50 means the average particle size of particles formed by aggregation of primary particles.

[0376] 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 it into a commercially available laser diffraction particle size measuring device (e.g., MT3000 manufactured by Microtrac), irradiating it with ultrasonic waves of about 28 kHz at an output of 60 W, and then obtaining a volume cumulative particle size distribution graph.

[0377] In the present invention, "consist essentially of A" means including 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 fabrication, minimizing gas generation due to such particle cracking, and minimizing the occurrence of internal cracks. Those of ordinary skill in the art will recognize the material effects of such characteristics.

[0378] The present inventors have conducted extensive research to develop a cathode for an electrochemical device that achieves high capacity while also having excellent safety, and an electrochemical device including the same. As a result, they have found that the safety of large cylindrical batteries can be dramatically improved when a single-particle cathode active material consisting of one primary particle or a pseudo-single-particle cathode active material that is an aggregate of 10 or fewer primary particles is used alone as the cathode active material.

[0379] According to one embodiment, the positive electrode includes a positive electrode current collector and a positive electrode active material layer formed on at least one side of the positive electrode current collector. The positive electrode active material layer may include a positive electrode active material and may optionally include a conductive material and / or a binder.

[0380] The positive electrode may have 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.

[0381] 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, or water, and then drying the cathode slurry to remove the solvent, 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 during coating.

[0382] In another embodiment, the positive electrode active material includes single-particle active material particles. In one embodiment, the single-particle active material particles may be included in an amount of 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 solely of the single-particle active material particles.

[0383] In this specification, the single-particle active material particles refer to 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.

[0384] Conventionally, the positive electrode active material used in lithium batteries has generally been spherical secondary particles formed by agglomeration of tens to hundreds of primary particles. However, such positive electrode active materials in the form of secondary particles, formed by agglomeration of many primary particles, are prone to particle cracking due to separation of the primary particles during the rolling process used in positive electrode production, leading to problems such as internal cracking during charge and discharge. When particle cracking or internal cracking occurs in the positive electrode active material, the contact area with the electrolyte increases, resulting in increased gas generation due to side reactions with the electrolyte. Increased gas generation within a cylindrical battery increases the internal pressure of the battery, potentially leading to battery explosion. In particular, increasing the volume of a cylindrical battery increases the amount of active material within the battery, which significantly increases the amount of gas generation, further increasing the risk of battery fire and / or explosion.

[0385] On the other hand, single-particle active material particles, which are single particles consisting of one primary particle or pseudo-single-particle particles consisting of an aggregation of 10 or fewer primary particles, have higher particle strength than conventional positive electrode active materials in the form of secondary particles, which are aggregations of tens to hundreds of primary particles, and therefore hardly ever undergo particle cracking during rolling. Furthermore, in the case of single-particle active material particles, because the number of primary particles constituting the particle is small, there is little change due to volume expansion and contraction of the primary particles during charge and discharge, which significantly reduces the occurrence of cracks inside the particles.

[0386] Therefore, when single particle active material particles are used as in one embodiment of the present invention, the amount of gas generated due to particle cracking and internal cracking can be significantly reduced, thereby achieving excellent safety when applied to large cylindrical batteries.

[0387] On the other hand, the single particles and / or pseudo-single particles 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 even more preferably 100 wt%, based on the weight of the entire positive electrode active material contained in the positive electrode.

[0388] When the content of the monoparticles and / or quasi-monoparticles satisfies the above range, sufficient safety can be obtained when applied to large-scale batteries. If the secondary particle-form positive electrode active material is contained in an amount exceeding 5 wt% of the total positive electrode active material, fine powder generated from the secondary particles during electrode fabrication and charge / discharge increases side reactions with the electrolyte, reducing the effect of suppressing gas generation, and therefore reducing the effect of improving stability when applied to large-scale batteries.

[0389] Meanwhile, the positive electrode active material including the single particle and / or the quasi-single particle according to an embodiment of the present invention is D min The D of the positive electrode active material 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 linear pressure increases during the rolling process of the positive electrode, which makes it easy for particle cracking to occur, and the thermal stability decreases, making it impossible to ensure sufficient thermal stability when applied to large cylindrical batteries.

[0390] 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 the value is too large, the diffusion distance of lithium ions within the particles increases, which may result in a decrease in resistance and output characteristics.

[0391] For example, D of the positive electrode active material min The thickness may be 1.0 μm to 3 μm, 1.0 μm to 2.5 μm, or 1.3 μm to 2.0 μm.

[0392] On the other hand, the positive electrode active material is D 50 The thickness may be 5 μm or less, 4 μm or less, or 3 μm or less, for example, 0.5 μm to 5 μm, preferably 1 μm to 5 μm, and more preferably 2 μm to 5 μm.

[0393] Positive electrode active materials in the form of single particles and / or quasi-single particles have fewer interfaces between primary particles, which act as diffusion paths for lithium ions within the particles, resulting in lower lithium mobility than positive electrode active materials in the form of secondary particles, which leads to increased resistance. This increase in resistance becomes more severe as the particle size increases, and the increased resistance adversely affects 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.

[0394] The positive electrode active material is D max The D of the positive electrode active material can be 12 μm to 17 μm, preferably 12 μm to 16 μm, and more preferably 12 μm to 15 μm. max If the D of the positive electrode active material satisfies the above range, the resistance characteristic and the capacitance characteristic are further improved. max If the D is too large, aggregation occurs between individual particles, and the lithium migration path inside the aggregated particles becomes longer, which may reduce the lithium mobility and increase the resistance. max If is too small, excessive crushing has occurred, and excessive crushing has resulted in D min The grain size may be as small as less than 1 μm, which may induce particle cracking during rolling and reduce thermal stability.

[0395] Meanwhile, the positive electrode active material may have a particle size distribution (PSD) represented by the following mathematical formula 1 of 3 or less, preferably 2 to 3, and more preferably 2.3 to 3.

[0396] [Formula 1] Particle size distribution (PSD)=(D max -D min ) / D 50

[0397] 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.

[0398] Meanwhile, the positive electrode active material may have an average primary particle size of 5 μm or less, 4 μm or less, 3 μm or less, or 2 μm or less, for example, 0.5 μm to 5 μm, preferably 1 μm to 5 μm, and more preferably 2 μm to 5 μm. When the average primary particle size satisfies the above range, a positive electrode active material in the form of a single particle and / or a quasi-single particle with excellent electrochemical properties can be formed. If the average primary particle size is too small, the number of agglomerates of the primary particles forming the positive electrode active material increases, which may reduce the effect of suppressing particle cracking during rolling. Furthermore, if the average primary particle size is too large, the lithium diffusion path within the primary particles may become longer, increasing resistance and potentially reducing output characteristics.

[0399] In one embodiment of the present invention, the positive electrode active material preferably has a unimodal particle size distribution. Conventionally, bimodal positive electrode active materials, which combine a large-particle positive electrode active material with a small-particle positive electrode active material, have been widely used to improve the electrode density of the positive electrode active material layer. However, in the case of single-particle or quasi-single-particle positive electrode active materials, increasing particle size significantly increases the lithium migration path, resulting in a significant increase in resistance. Therefore, when large-particle particles are mixed, the capacity and output characteristics may be reduced. Therefore, the present invention uses a positive electrode active material with a unimodal distribution to minimize the increase in resistance.

[0400] Meanwhile, the positive electrode active material may include a lithium nickel-based oxide, specifically, a lithium nickel-based oxide containing 80 mol% or more of Ni based on the total number of moles of transition metals. Preferably, the lithium nickel-based oxide may contain 80 mol% or more but less than 100 mol%, 82 mol% or more but less than 100 mol%, or 83 mol% or more but less than 100 mol% of Ni. When a lithium nickel-based oxide with a high Ni content is used as described above, a high capacity can be achieved.

[0401] More specifically, the positive electrode active material may include a lithium nickel-based oxide represented by the following Chemical Formula 1:

[0402] [Chemical formula 1] Li a Ni b Co c M 1 d M 2 e O2

[0403] In Chemical Formula 1, the M 1 may be Mn, Al or a combination thereof, preferably Mn, or Mn and Al.

[0404] 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 particle growth during firing or improving the stability of the crystal structure.

[0405] The a represents the lithium molar ratio 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 the above range, the crystalline structure of the lithium nickel-based oxide can be stably formed.

[0406] The b represents the molar ratio of nickel to all metals excluding 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 molar ratio of nickel satisfies the above range, high energy density and high capacity can be achieved.

[0407] The 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.

[0408] The d represents the molar ratio of the M 1 element 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. When the molar ratio of the M 1 element satisfies the above range, the structure stability of the positive electrode active material is excellent.

[0409] The e represents the molar ratio of the M 2 element in the total metal excluding lithium in the lithium nickel-based oxide, and can be 0 ≤ e ≤ 0.1 or 0 ≤ e ≤ 0.05.

[0410] 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. Preferably, the coating element can be Al, B, Co, or a combination thereof.

[0411] 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 or gas generation due to side reactions with the electrolyte can be obtained.

[0412] The positive electrode active material may be contained 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.

[0413] Meanwhile, various positive electrode current collectors used in the art 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, or the like. The positive electrode current collector may typically have a thickness of 3 μm to 500 μm, and the surface of the positive electrode current collector may be micro-irregularized to enhance adhesion 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 material, foam, or nonwoven fabric.

[0414] Meanwhile, in one embodiment of the present invention, all or some of the single-particle active material particles may have a core-shell structure in which the surfaces of the particles are coated with a conductive coating layer. The conductive coating layer may cover at least some or all of the particles. The conductive coating layer may include a conductive nanomaterial.

[0415] Compared to conventional secondary particle-type positive electrode active materials, the single particle-type active material particles have higher resistance and a smaller contact area with the conductive material, resulting in reduced electrical conductivity. Adding an excessive amount of conductive material to improve electrical conductivity can cause aggregation in the positive electrode slurry, increasing viscosity and resulting in reduced coating properties. Therefore, to achieve smooth coating properties, the solid content must be reduced to lower the viscosity of the positive electrode slurry. However, reducing the solid content in the positive electrode slurry reduces the active material content, resulting in reduced capacity characteristics. To address this issue, the present invention coats the surfaces of single particle-type active material particles with a conductive nanomaterial, thereby achieving excellent electrical conductivity without adding a separate conductive material to the positive electrode slurry.

[0416] In an embodiment of the present invention, when a cathode active material in which the surfaces of the single-particle active material particles are coated with a conductive nanomaterial is used, the cathode active material layer may not include a conductive material in a portion other than the conductive coating layer. Since there is no need to use an additional conductive material that induces aggregation of the cathode slurry, the viscosity of the cathode slurry may be reduced, the solid content may be increased, and the processability of the electrode coating and the electrode adhesion may be improved.

[0417] In one embodiment of the present invention, the conductive nano-material may be a material having nano-sized dimensions to be smoothly coated on particles and having conductivity, 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.

[0418] The conductive nano-materials may have various shapes, such as spherical, scale-like, or fibrous shapes.

[0419] The conductive coating layer may be formed by mixing the core particles of the single-particle active material with the conductive nanomaterial, followed by heat treatment. The mixing may be performed in a solid phase or liquid phase.

[0420] In one embodiment of the present invention, the positive electrode active material layer includes flake graphite. When the single particle active material is used as the positive electrode active material, if the positive electrode active material layer includes flake graphite, the flake graphite provides a slipping effect to the positive electrode active material when the positive electrode active material layer is rolled, improving the rolling characteristics of the electrode and reducing the porosity of the electrode to a desired level. As a result, a battery using a positive electrode according to an embodiment of the present invention can have improved stability, initial resistance characteristics, and charge / discharge efficiency.

[0421] In one embodiment of the present invention, the flake graphite may be contained in an amount of 0.1 wt % to 5 wt %, preferably 0.1 wt % to 3 wt %, relative to 100 wt % of the positive electrode active material layer.

[0422] When the content of flake graphite satisfies the above range, the rolling characteristics of the positive electrode are improved, resulting in excellent electrode density. If the content of flake graphite is too low, the effect of improving the rolling characteristics is low, while if the content is too high, it may cause an increase in slurry viscosity and a decrease in phase stability, and may cause a decrease in electrode uniformity and an increase in resistance due to bonding with the conductive material.

[0423] 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, but is not limited thereto. If the flake graphite is too small, it may be difficult to achieve the desired porosity, which may lower the current density and result in a decrease in capacity. In this case, the average particle size of the flake graphite may be measured by a laser diffraction method (ISO 13320).

[0424] The flake graphite may have an aspect ratio of 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, it has the effect of improving the conductivity and reducing the electrode resistance.

[0425] 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 , more preferably 2.2 g / cm 3 ~2.3g / cm 3 It could be.

[0426] 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 satisfies the above range, the electrode density increases, excellent capacity can be achieved, and resistance is reduced. If the porosity is too low, the electrolyte impregnation property may be reduced, which may cause lithium deposition due to insufficient electrolyte impregnation. If the porosity is too high, poor contact between the electrodes may result in increased resistance, reduced energy density, and a low capacity improvement effect.

[0427] 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.

[0428] When realizing a high-loading electrode having a relatively high loading amount of the positive electrode active material layer, the use of a positive electrode active material in the form of a single particle or quasi-single particle as in one embodiment of the present invention significantly reduces particle cracking of the active material during rolling compared to conventional positive electrode active materials in the form of secondary particles, and reduces damage to the positive electrode current collector (Al foil). This makes it possible to roll at a relatively high linear pressure, and the porosity of the positive electrode active material layer can be reduced to the above-mentioned numerical range, thereby increasing the energy density.

[0429] Furthermore, when flake graphite is included in the positive electrode active material layer according to an embodiment of the present invention, the flake graphite provides a slipping effect during rolling and can fill voids in the positive electrode active material layer, thereby reducing the porosity of the positive electrode active material layer to the above-mentioned numerical range.

[0430] The positive electrode has a loading of 570 mg / 25 cm 2 More than 600mg / 25cm 2 ~800g / 25m 2 , more preferably 600 mg / 25 cm 2 ~750mg / 25cm 2 Specifically, in the case of a lithium secondary battery according to an embodiment of the present invention, the rolling characteristics of the electrode are improved by using a positive electrode active material and flake graphite in the form of a single particle and / or a quasi-single particle, and therefore the loading amount of the positive electrode can be secured at a relatively high level, thereby achieving high capacity characteristics.

[0431] 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 conductivity to the electrode and may be any material that is electrically conductive and does not cause chemical changes inside the battery. Specific examples include graphite such as natural graphite or 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. These materials may be used alone or in combination. The conductive material may typically be present in an amount of 1 wt% to 30 wt%, preferably 1 wt% to 20 wt%, and more preferably 1 wt% to 10 wt% of the total weight of the positive electrode active material layer.

[0432] In a specific embodiment according to an embodiment of the present invention, the conductive material may include carbon nanotubes.

[0433] In one embodiment of the present invention, the positive electrode active material may include, as a conductive material, multi-walled carbon nanotubes having a high specific surface area and a small wall number. 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 relative to 100 wt% of the conductive material. In a specific embodiment of the present invention, the conductive material may consist solely of the multi-walled carbon nanotubes.

[0434] In one embodiment of the present invention, the multi-walled carbon nanotubes are 300 mm or less. 2 / g~500m 2 / g. To distinguish it from conventional technology, we refer to it as the "new CNT."

[0435] Conventionally, commonly used carbon nanotubes (conventional CNTs) have a BET specific surface area of ​​300m 2The scanning electron microscope images and physical properties (FIG. 38) of the novel CNT used in the present invention (FIG. 36) and the conventional CNT (FIG. 37) are compared as follows:

[0436] As can be seen from the SEM image, the novel CNTs used in one embodiment of the present invention are bundled type with a multi-wall structure, but have a higher BET, number of walls, and a smaller diameter than conventional CNTs.

[0437] When using a secondary particle type positive electrode active material, sufficient electrical conductivity can be achieved even when using conventional CNTs at about 0.4 wt% to 0.6 wt%. However, in the case of a single particle or pseudo-single particle type positive electrode active material, 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 lower electrical conductivity. Therefore, when using a single particle or pseudo-single particle type positive electrode active material, the BET specific surface area is 300 m 2 To achieve sufficient electrical conductivity using conventional CNTs with less than 1 / g, the content of the conductive material must be 0.9 wt% or more.

[0438] 39 to 42 are graphs showing the sheet resistance and high-temperature life characteristics depending on the ratio of the conductive material when single particles or pseudo-single particles are used as the positive electrode active material.

[0439] From the graph, it can be seen that when single particles or pseudo-single particles are used as the positive electrode active material, the amount of conductive material used needs to be increased compared to when a conventional positive electrode active material in the form of secondary particles is used.

[0440] However, if the carbon nanotube content is increased to 0.9 wt% or more, aggregation occurs in the positive electrode slurry, increasing viscosity and resulting in poor coating properties. Therefore, to achieve smooth coating properties, the solid content in the positive electrode slurry must be reduced to lower the viscosity of the positive electrode slurry. However, if the solid content in the positive electrode slurry is reduced, the active material content decreases, resulting in poor capacity characteristics.

[0441] As a result of extensive research into solving these problems, the inventors of the present invention have discovered a conductive material having a BET specific surface area of ​​300 m2, in addition to a positive electrode active material that is a single particle active material particle. 2 / g~500m 2 / g, sufficient electrical conductivity can be ensured even with a relatively small amount of carbon nanotubes, and as a result, it was confirmed that the slurry viscosity can be maintained low even when the solid content of the positive electrode slurry is formed as high as 70 wt% to 80 wt%.

[0442] Specifically, the carbon nanotubes used in 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 satisfies the above range, sufficient electrical conductivity can be ensured even with a small amount of carbon nanotubes.

[0443] The carbon nanotubes may be multi-wall carbon nanotubes having a wall number of 2 to 8, preferably 2 to 6, and more preferably 3 to 6.

[0444] 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.

[0445] The carbon nanotubes may be contained 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 total 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, thereby enabling the positive electrode active material content to be high in the positive electrode active material layer and thereby achieving excellent capacity characteristics.

[0446] The table shown in Figure 43 shows the BET specific surface area of ​​300 m 2 / g~500m2 / g of carbon nanotubes (new CNTs) and a BET specific surface area of ​​200m 2 / g or more 300m 2 The table compares the solid content, viscosity, resistance of the MP coating layer, and resistance of the MP interface layer of the positive electrode slurry when carbon nanotubes (conventional CNTs) of less than 1 / g are used. The table shows that when the new CNTs are used, the viscosity is lower and electrical conductivity is superior, even when the solid content of the positive electrode slurry is higher than that of conventional CNTs.

[0447] The binder improves adhesion between positive electrode active material particles and between 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 (EPDM) rubber, sulfonated EPDM, styrene-butadiene rubber (SBR), fluororubber, and various copolymers thereof. These may be used alone or in combination. The binder may be present 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.

[0448] Another embodiment 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 described above.

[0449] 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-type structure. When forming a jelly roll-type structure, a separator can be further disposed on the outside to prevent contact between the negative electrode and the positive electrode.

[0450] The negative electrode includes a negative electrode current collector and a negative electrode active material layer formed on at least one surface of the negative electrode current collector. The negative electrode can have 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 can include a negative electrode active material, a conductive material, and a binder.

[0451] 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 through a drying process, and then rolling. When applying the negative electrode slurry, a negative electrode without a coating 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.

[0452] As the negative electrode active material, a compound capable of reversible insertion (intercalation) and deintercalation of lithium can be used. Specific examples 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.; and the like. One or a mixture of two or more of these can be used.

[0453] 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 may be Si, Si-Me alloy (where Me is one or more selected from the group consisting of Al, Sn, Mg, Cu, Fe, Pb, Zn, Mn, Cr, Ti, and Ni), SiO y (where 0 < y < 2), a Si-C composite, or a combination thereof, 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.

[0454] The silicon-based negative electrode active material may be doped with M b metal. At this time, the M b metal may be a Group 1 metal element or a Group 2 metal element, specifically, Li, Mg, etc. Specifically, the silicon-based negative electrode active material may be Si doped with M b metal, SiO y (where 0 < y < 2), a Si-C composite, etc. In the case of a metal-doped silicon-based negative electrode active material, although the active material capacity decreases somewhat due to the doping element, it has high efficiency, so a high energy density can be realized.

[0455] FIG. 60 is a graph showing the change in energy density according to 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.

[0456] In FIG. 60, the low-efficiency SiO is undoped SiO, and the ultra-high-efficiency SiO means Mg / Li-doped SiO. From FIG. 60, it can be confirmed that the energy density improves as the content of the silicon-based negative electrode active material in the total negative electrode active material increases. Also, it can be confirmed that the improvement effect of the energy density is more excellent as the ratio of the doped silicon-based negative electrode active material in the silicon-based negative electrode active material increases.

[0457] The silicon-based negative electrode active material may further include a carbon coating layer on the surface of the particles. 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 electrode active material. The carbon coating layer may be formed by dry coating, wet coating, chemical vapor deposition (CVD), physical vapor deposition (PVD), atomic layer deposition (ALD), or the like.

[0458] 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%.

[0459] In another embodiment of the present invention, D of the silicon-based negative electrode active material 50 can be 3 μm to 8 μm, and D min ~D max can be in the range of 0.5 μm to 30 μm.

[0460] The negative electrode may further include a carbon-based negative electrode active material, as needed, such as, but not limited to, artificial graphite, natural graphite, graphitized carbon fiber, amorphous carbon, soft carbon, or hard carbon.

[0461] 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 to 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.

[0462] The negative electrode active material may be contained 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.

[0463] If necessary, the negative electrode active material may further include at least one selected from lithium metal and metallic materials that can be alloyed with lithium, such as Sn and Al.

[0464] 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 the like, or an aluminum-cadmium alloy. The negative electrode current collector typically has a thickness of 3 μm to 500 μm, and, like the positive electrode current collector, the surface of the current collector may be formed with 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 material, foam, or nonwoven fabric.

[0465] The conductive material is used to impart conductivity to the negative electrode and can be any material that is electrically conductive and does not cause chemical changes inside the battery. Specific examples of conductive materials include graphite, such as natural graphite or 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 powders or fibers, such as copper, nickel, aluminum, and silver; conductive whiskers, such as zinc oxide and potassium titanate; conductive metal oxides, such as titanium oxide; and conductive polymers, such as polyphenylene derivatives. These materials may be used alone or in combination. The conductive material is typically present in an amount of 1 wt% to 30 wt%, preferably 1 wt% to 20 wt%, and more preferably 1 wt% to 10 wt% of the total weight of the negative electrode active material layer.

[0466] The binder serves to improve adhesion between negative electrode active material particles and between the negative electrode active material and the negative electrode current collector. Specific examples of binders 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 (EPDM) rubber, sulfonated EPDM, styrene-butadiene rubber (SBR), fluororubber, and various copolymers thereof. These may be used alone or in combination. The binder may be included in an amount of 1 wt% to 30 wt%, preferably 1 wt% to 20 wt%, and more preferably 1 wt% to 10 wt% of the total weight of the negative electrode active material layer.

[0467] The electrode assembly further includes a separator disposed between the negative electrode and the positive electrode, which separates the negative electrode from the positive electrode and provides a path for lithium ions to move. Any separator commonly used as a separator in lithium batteries can be used without any particular limitation.

[0468] The separator may be a porous polymer film, such as 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. Conventional porous nonwoven fabrics, such as nonwoven fabrics made of high-melting-point glass fibers or polyethylene terephthalate fibers, may also be used. To ensure heat resistance or mechanical strength, a separator coated with a ceramic component or a polymer material may also be used.

[0469] Another embodiment of the present invention relates to a battery including the electrode assembly. The battery includes an electrode assembly and an electrolyte housed in a battery case. The battery case may be a pouch-type or metal can-type battery case, and may be appropriately selected without particular limitation, as long as it is commonly used in the art.

[0470] The electrolyte used in the present invention is not particularly limited, and 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.

[0471] Specifically, the electrolyte may include an organic solvent and a lithium salt.

[0472] The organic solvent may be any organic solvent that can act as a medium through which ions involved in the electrochemical reaction of the battery can move. Specific examples of the organic solvent that can be used include ester solvents such as methyl acetate, ethyl acetate, γ-butyrolactone, and ε-caprolactone; ether solvents such as dibutyl ether and tetrahydrofuran; ketone solvents such as cyclohexanone; aromatic hydrocarbon solvents such as benzene, benzene, and fluorobenzene; carbonate solvents such as dimethyl carbonate (DMC), diethyl carbonate (DEC), methyl ethyl carbonate (MEC), ethyl methyl carbonate (EMC), ethylene carbonate (EC), and propylene carbonate (PC); alcohol solvents such as ethyl alcohol and isopropyl alcohol; nitriles such as R-CN (R is a C2-C20 linear, branched, or cyclic hydrocarbon group that may contain a double-bonded aromatic ring or an ether bond); amides such as dimethylformamide; dioxolanes such as 1,3-dioxolane; and sulfolanes. Among these, carbonate-based solvents are preferred, and mixtures of cyclic carbonates (e.g., ethylene carbonate or propylene carbonate) having high ionic conductivity and high dielectric constant, which can improve the charge / discharge performance of batteries, with low-viscosity linear carbonate-based compounds (e.g., ethyl methyl carbonate, dimethyl carbonate, or diethyl carbonate) are more preferred.

[0473] The lithium salt may be any compound capable of providing lithium ions used in lithium batteries. Specifically, the lithium salt may be LiPF, LiClO, LiAsF, LiBF, LiSbF, LiAlO, LiAlCl, LiCF, SO, LiCF, SO, LiN(C, F, SO), LiN(C, F, SO), LiN(CF, SO), LiCl, LiI, or LiB(C, O) . The concentration of the lithium salt may be 0.1 to 5.0 M, preferably 0.1 to 3.0 M. When the lithium salt concentration is within the above range, the electrolyte has appropriate conductivity and viscosity, exhibiting excellent electrolyte performance and allowing for effective lithium ion migration.

[0474] In addition to the electrolyte components described above, the electrolyte may further contain additives for purposes such as improving battery life characteristics, suppressing battery capacity loss, and improving battery discharge capacity. Examples of additives include, but are not limited to, 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, and aluminum trichloride, which may be used alone or in combination. The additives may be present 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.

[0475] In yet another embodiment of the present invention, the positive electrode may include a reduced loading 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 can be increased without worrying about lithium deposition, thereby improving the energy density of the electrode assembly.

[0476] In recent years, battery development has focused on increasing battery size to achieve high energy density and reduce costs. As energy increases with battery size, the resistance per battery must decrease. To reduce resistance, a method using the electrode current collector as the electrode tab, rather than attaching an electrode tab to the electrode, can be used. However, due to the nature of the electrode manufacturing process, in which electrode slurry is applied to the electrode current collector, a region of reduced loading occurs at the interface between the negative electrode active material portion coated with the negative electrode slurry and the negative electrode current collector. Considering the N / P ratio, metallic lithium may be deposited in the positive electrode active material portion facing the region of reduced loading. The N / P ratio, defined as the negative electrode capacity calculated based on the negative electrode capacity per area and mass divided by the positive electrode capacity calculated based on the positive electrode capacity per area and mass, is typically greater than 1. This increases the negative electrode capacity. For reference, if the N / P ratio is not 1, metallic lithium is likely to precipitate during charge and discharge, which can rapidly deteriorate battery safety during high-rate charge and discharge. In other words, the N / P ratio has a significant impact on battery safety and capacity. Due to the risk of metallic lithium precipitation, the positive electrode active material section cannot be positioned in the positive electrode section facing the negative electrode where the loading amount decreases. This makes it difficult to increase the battery's energy density. Therefore, the present invention improves energy density by increasing the section of the positive electrode active material section.

[0477] FIG. 48 is a view showing an electrode assembly according to one embodiment of the present invention, and FIG. 49 is a cross-sectional view taken along line AA' in FIG.

[0478] 48 and 49, 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. When the jelly roll structure 300S is formed, it is preferable that a separator 600 be further disposed on the outside to prevent the negative electrode 400 and the positive electrode 500 from contacting each other.

[0479] The negative electrode 400 includes a negative electrode current collector 410 and a negative electrode active material portion 420 formed by coating a negative electrode active material on the negative electrode current collector 410. In particular, as shown in the figure, the negative electrode active material portion 420 may be formed by coating both surfaces of the negative electrode current collector 410 with a negative electrode active material. In addition, a negative electrode uncoated portion 430, where the negative electrode active material is not coated, extends in a first direction d1 on the negative electrode current collector 410. The negative electrode uncoated portion 430 extends along one end of the wound negative electrode 400. The negative electrode uncoated portion 430 extends in the first direction d1 longer than the separator 600. As a result, the negative electrode uncoated portion 430 may be exposed at one end of the jelly roll structure 300S in the first direction.

[0480] The positive electrode 500 includes a positive electrode current collector 510 and a positive electrode active material portion 520 formed by coating a positive electrode active material on the positive electrode current collector 510. In particular, as shown in the figure, the positive electrode active material portion 520 may be formed by coating both surfaces of the positive electrode current collector 510 with a positive electrode active material. In addition, a positive electrode uncoated portion 530, where the positive electrode active material is not coated, extends in the second direction d2 on the positive electrode current collector 510. The positive electrode uncoated portion 530 extends along one end of the wound positive electrode 500. In addition, the positive electrode uncoated portion 530 extends in the second direction d2 longer than the separator 600. As a result, the positive electrode uncoated portion 530 may be exposed at one end of the jelly roll structure 300S in the second direction.

[0481] Here, the first direction d1 and the second direction d2 are opposite directions. The first direction d1 and the second direction d2 may be parallel to the height direction of the jelly roll structure 300S. The electrode assembly 300 according to this embodiment does not have separate electrode tabs attached, but instead uses the negative electrode uncoated portion 430 of the negative electrode current collector 410 and the positive electrode uncoated portion 530 of the positive electrode current collector 510 as electrode tabs to reduce resistance.

[0482] 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.

[0483] In one embodiment, the positive electrode active material unit 520 includes a loading reduction portion 500D having a lower 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 amount of the positive electrode active material in the loading reduction portion 500D may gradually decrease in the first direction d1.

[0484] Here, the term "loading amount" refers to the amount of active material applied per unit area. In a region with a high loading amount, a large amount of negative or positive active material may be applied per unit area, resulting in a relatively thick negative or positive active material portion. In a region with a low loading amount, a small amount of negative or positive active material may be applied per unit area, resulting in a relatively thin negative or positive active material portion.

[0485] The active material portion is formed by applying a slurry containing an active material. During this process, a boundary portion where the loading amount gradually decreases may be formed between the non-coated portion and the active material portion.

[0486] 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 gradually decrease toward the negative electrode uncoated part 430.

[0487] Similarly, the positive electrode active material portion 520 may include a positive electrode boundary portion 520B that forms a boundary between the positive electrode active material portion 520 and the positive electrode uncoated portion 530. The loading amount of the positive electrode boundary portion 520B may gradually decrease toward the positive electrode uncoated portion 530.

[0488] The negative electrode boundary 420B and the positive electrode boundary 520B, where the loading amount gradually decreases, are naturally generated during the process of applying the slurry containing the active material to the negative electrode current collector 410 and the positive electrode current collector 510.

[0489] At this time, with respect to the direction perpendicular to second direction d2 as the reference, the amount of positive electrode active material is less than the amount of negative electrode active material in the region corresponding to positive electrode boundary 520B, which results in an N / P ratio greater than 1, preventing problems such as the deposition of metallic lithium.

[0490] However, a problem occurs in the region corresponding to the negative electrode boundary 420B. In the region corresponding to the negative electrode boundary 420B, the amount of negative electrode active material is less than the amount of positive electrode active material in the direction perpendicular to the first direction d1. This results in an N / P ratio less than 1, which may cause a problem of metallic lithium precipitation.

[0491] Therefore, in this embodiment, a loading reduction portion 500D is provided in the positive electrode 500, and the negative electrode active material portion 420 is 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.

[0492] By providing a loading reduction portion 500D, in which the loading amount of the positive electrode active material is less than that of the adjacent region, at a position corresponding to the negative electrode boundary portion 420B where the loading amount gradually decreases, it is possible to increase the area where the positive electrode active material is applied without worrying about lithium deposition. In particular, the loading reduction portion 500D may have a shape in which the loading amount of the positive electrode active material gradually decreases in the first direction d1, corresponding to the shape of the negative electrode boundary portion 420B where the loading amount gradually decreases toward the negative electrode uncoated portion 430. Therefore, it is possible to maintain a high N / P ratio between the negative electrode 400 and the positive electrode 500 in the region where the negative electrode boundary portion 420B is formed, and to prevent lithium deposition.

[0493] 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.

[0494] 50 and 51 are views showing a process for manufacturing a negative electrode according to one embodiment of the present invention. Specifically, Fig. 50 is a top view of a negative electrode sheet, and Fig. 51 is a front view of the negative electrode sheet of Fig. 50.

[0495] 50 and 51, a method for manufacturing an electrode assembly according to an embodiment of the present invention includes manufacturing a negative electrode sheet 400S on a negative electrode current collector 410 such that negative electrode active material portions 420 coated with a negative electrode active material and negative electrode uncoated portions 430 not coated with a negative electrode active material are alternately arranged.

[0496] Specifically, the negative electrode active material may be applied to extend in the third direction d3 to form the negative electrode active material portion 420. In addition, the applied regions may be spaced apart along a fourth direction d4 perpendicular to the third direction d3, so that the negative electrode active material portions 420 may be spaced apart along the fourth direction d4. That is, the application process may be performed such that the negative electrode uncoated portion 430 is positioned between the negative electrode active material portions 420.

[0497] 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.

[0498] Thereafter, the negative electrode uncoated portion 430 and the negative electrode active material portion 420 may be slit to manufacture the negative electrode 400. Figure 52 is a perspective view showing a negative electrode according to an embodiment of the present invention.

[0499] 50 to 52, as shown by dotted lines in FIGS. 50 and 51, 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. This allows a plurality of negative electrodes 400, such as those shown in FIG. 52, to be manufactured from the negative electrode sheet 400S. That is, the negative electrode 400 in FIG. 52 corresponds to one of a plurality of negative electrodes manufactured by slitting the negative electrode sheet 400S in FIGS. 50 and 51. 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.

[0500] When forming the negative electrode active material part 420, a slurry containing the negative electrode active material is applied onto the negative electrode current collector 410. During this slurry application process, 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, where the loading amount gradually decreases toward the negative electrode uncoated part 430.

[0501] 53 and 54 are diagrams illustrating a process for manufacturing a positive electrode according to one embodiment of the present invention. Specifically, Fig. 53 is a top view of a positive electrode sheet, and Fig. 54 is a front view of the positive electrode sheet of Fig. 53.

[0502] 53 and 54, a method for manufacturing an electrode assembly according to an embodiment of the present invention includes manufacturing a positive electrode sheet 500S on a positive electrode current collector 510 such that positive electrode active material portions 520 coated with a positive electrode active material and positive electrode uncoated portions 530 not coated with a positive electrode active material are alternately arranged.

[0503] Specifically, the positive electrode active material may be applied to extend in the third direction d3 to form the positive electrode active material units 520. In addition, the application interval may be adjusted along a fourth direction d4 perpendicular to the third direction d3 to space the positive electrode active material units 520 apart from each other. That is, the application process may be performed such that the positive electrode uncoated portions 530 are positioned between the positive electrode active material units 520.

[0504] 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.

[0505] Thereafter, the positive electrode uncoated portion 530 and the positive electrode active material portion 520 may be slit to manufacture the positive electrode 500. Figure 55 is a perspective view showing a positive electrode 500 according to one embodiment of the present invention.

[0506] 53 to 55, as shown by the dotted lines in FIGS. 53 and 54, the positive electrode uncoated portion 530 and the positive electrode active material portion 520 may each be slit in a direction parallel to the third direction d3. This allows a plurality of positive electrodes 500, such as those shown in FIG. 55, to be manufactured from the positive electrode sheet 500S. That is, the positive electrode 500 in FIG. 55 corresponds to one of a plurality of positive electrodes manufactured by slitting the positive electrode sheet 500S in FIGS. 53 and 54. By slitting the positive electrode uncoated portion 530 and the positive electrode active material portion 520 in the positive electrode sheet 500S, a positive electrode 500 having the positive electrode uncoated portion 530 extending to one side may be manufactured.

[0507] 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 this slurry application process, a positive electrode boundary part 520B may be formed at the boundary between the positive electrode active material part 520 and the positive electrode uncoated part 530, where the loading amount gradually decreases toward the positive electrode uncoated part 530.

[0508] 48, 52, and 55, the fabricated negative electrode 400 and positive electrode 500 may be subsequently wound together with a separator 600 to form a jelly roll structure 300S. In this case, in the jelly roll structure 300S, the negative electrode uncoated region 430 may extend longer than the separator 600 in a first direction d1, and the positive electrode uncoated region 530 may extend longer than the separator 600 in a second direction d2 opposite to the first direction d1.

[0509] 53 to 55, 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. The method for forming the reduced loading region 500DA is not particularly limited, and for example, the reduced loading region 500DA may be formed by adjusting the degree of application of the slurry.

[0510] In the step of manufacturing the positive electrode 500, the loading reduction region 500DA is slit from the positive electrode active material part 520. The slit loading reduction region 500DA forms a loading reduction part 500D in the jelly roll structure 300S shown in FIGS. 48 and 49, in which the loading amount of the positive electrode active material is less than that of the adjacent region.

[0511] Specifically, a loading reduction region 500DA, in which the loading amount of the positive electrode active material is less than that of an adjacent region, is formed in a positive electrode active material portion 520 formed in a positive electrode sheet 500S. As shown in Fig. 54, the loading reduction region 500DA may be formed in the center of the positive electrode active material portion 520. Meanwhile, the loading reduction region 500DA may be configured so that the loading amount of the positive electrode active material gradually decreases toward a central portion 500C of the loading reduction region 500DA. In the step of manufacturing the positive electrode 500, the loading reduction region 500D according to this embodiment may be formed by slitting the central portion 500C of the loading reduction region 500DA.

[0512] That is, a loading reduction region 500DA is formed by applying a slurry containing a positive electrode active material, and a central portion 500C of the loading reduction region 500DA is slit, thereby manufacturing a plurality of positive electrodes 500 each having a loading reduction portion 500D formed therein.

[0513] Referring to FIG. 55, a loading reducing portion 500D may be provided at one end of the manufactured positive electrode 500, and a positive electrode uncoated portion 530 may be provided at the other end of the positive electrode 500 opposite the one end.

[0514] 48 and 49, when such a positive electrode 500 is wound to form a jelly roll structure 300S, the loading reduction portion 500D may be located at one end of the positive electrode 500 in the first direction d1, and the positive electrode uncoated portion 530 may be located at one end of the positive electrode 500 in the second direction d2.

[0515] In addition, by slitting the central portion 500C of the loading reduction region 500DA, the loading amount of the positive electrode active material may gradually decrease in the loading reduction portion 500D in the first direction d1.

[0516] In addition, the negative electrode active material part 420 may be located in a portion of the jelly roll structure 300S corresponding to the loading reducer 500D in a direction perpendicular to the first direction d1. More specifically, the negative electrode boundary part 420B may be located in a portion of the jelly roll structure 300S corresponding to the loading reducer 500D in a direction perpendicular to the first direction d1.

[0517] The corresponding positional relationship between the loading reduction portion 500D and the negative electrode boundary portion 420B is the same as that described above, and therefore will not be repeated.

[0518] Hereinafter, an electrode assembly according to a comparative example of the present invention will be described with reference to FIGS. 56 to 59, and advantages of the electrode assembly according to the embodiment of the present invention compared to the comparative example will be described.

[0519] FIG. 56 shows an electrode assembly according to a comparative example of the present invention, and FIG. 57 is a cross-sectional view taken along line BB' in FIG.

[0520] 56 and 57, 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.

[0521] The negative electrode 700 may include a negative electrode current collector 710, a negative electrode active material portion 720, and a negative electrode uncoated portion 730. The negative electrode uncoated portion 730 may extend in a first direction d1, and the negative electrode active material portion 720 may include a negative electrode boundary portion 720B that forms a boundary between the negative electrode active material portion 720 and the negative electrode uncoated portion 730 and in which the loading amount gradually decreases.

[0522] FIG. 58 is a diagram showing a process for manufacturing a negative electrode 700 according to a comparative embodiment of the present invention.

[0523] Referring to FIG. 58, after a negative electrode sheet 700S is manufactured so that the negative electrode active material parts 720 and the negative electrode uncoated parts 730 are alternately positioned along the fourth direction d4, the negative electrode uncoated parts 730 and the negative electrode active material parts 720 are slit to manufacture a plurality of negative electrodes 700.

[0524] 56 and 57, a positive electrode 800 may include a positive electrode current collector 810, a positive electrode active material portion 820, and a positive electrode uncoated portion 830. The positive electrode uncoated portion 830 may extend in a second direction d2 opposite to the first direction d1, and the positive electrode active material portion 820 may include a positive electrode boundary portion 820B that forms a boundary between the positive electrode active material portion 820 and the positive electrode uncoated portion 830 and in which the loading amount gradually decreases.

[0525] FIG. 59 is a diagram showing the steps of manufacturing a positive electrode 800 according to a comparative embodiment of the present invention.

[0526] Referring to FIG. 59, a positive electrode sheet 800S is manufactured so that the positive electrode active material portions 820 and the positive electrode uncoated portions 830 are alternately positioned along the fourth direction d4, and then the positive electrode uncoated portions 830 and the positive electrode active material portions 820 are slit to manufacture a plurality of positive electrodes 800.

[0527] Then, the manufactured anode 700 and cathode 800 are wound together with a separator 900 to manufacture an electrode assembly 600 according to a comparative example of the present invention.

[0528] 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 embodiment of the present invention, except for the loading reduction portion 500D (see FIG. 49).

[0529] 56 and 57, in the comparative electrode assembly 600, the positive electrode active material part 820 cannot be positioned in a portion corresponding to the negative electrode boundary part 720B in a direction perpendicular to the first direction d1. If the positive electrode active material part 820 extended to the portion corresponding to the negative electrode boundary part 720B, the corresponding portion would have a low N / P ratio, making it more likely that metallic lithium would precipitate. Therefore, the only way to prevent lithium precipitation is to limit the length of the positive electrode active material part 820. That is, the positive electrode active material part 820 can be formed only in the B1 region shown in the figure, and cannot be formed in the B2 region, resulting in the length of the positive electrode active material part 820 being reduced by the negative electrode boundary part 720B.

[0530] 48 and 49, in the electrode assembly 300 according to an embodiment of the present invention, 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 in a direction perpendicular to the first direction d1. The loading reduction part 500D, which has a lower loading amount of positive electrode active material than adjacent regions, is provided in the portion corresponding to the negative electrode boundary part 420B, thereby maintaining a high N / P ratio in the corresponding portion and preventing lithium precipitation. This allows the positive electrode active material part 520 to be formed over the A1 region, thereby reducing the A2 region where the positive electrode active material part 520 cannot be formed. For example, the width of the positive electrode 500 in the height direction relative to the width of the negative electrode 400 in the height direction may be increased to 98% or more.

[0531] Comparing the A1 region in Figures 48 and 49 with the B1 region in Figures 56 and 57, the electrode assembly 300 according to this embodiment can increase the length of the positive electrode active material portion by the loading reduction portion 500D, thereby achieving a higher energy density in a limited space than the electrode assembly 600 according to the comparative example.

[0532] Another embodiment of the present invention relates to a cylindrical battery including a jelly-roll type electrode assembly having a positive electrode, a negative electrode, and a separator interposed between the positive and negative electrodes wound in one direction, a cylindrical battery housing containing the electrode assembly, and a battery cap disposed on top of the battery housing to seal the battery housing. The positive electrode is an embodiment of the present invention, and the positive electrode active material has an average particle size D 50 The cylindrical battery may further include an electrolyte, and the above description of the electrolyte can be referred to.

[0533] The electrode assembly may have a stacked, stacked / folded, or jelly roll 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.

[0534] Conventional cylindrical batteries have problems with current being concentrated on the strip-shaped electrode tabs, resulting in high resistance, large amounts of heat generation, and poor current collection efficiency.

[0535] In recent years, with the advancement of electric vehicle-related technologies, the demand for high-capacity batteries has increased, necessitating the development of large-volume cylindrical batteries. Conventionally used small cylindrical batteries, i.e., cylindrical batteries with 1865 or 2170 form factors, have small capacities, so resistance and heat generation do not seriously affect battery performance. However, if the specifications of conventional small cylindrical batteries are applied directly to large cylindrical batteries, serious battery safety issues may arise.

[0536] As a battery becomes larger, the amount of heat and gas generated inside the battery also increases. This heat and gas can increase the temperature and pressure inside the battery, potentially leading to battery fire or explosion. To prevent this, the heat and gas inside the battery must be properly discharged to the outside. To achieve this, the cross-sectional area of ​​the battery, which serves as a path for heat discharge to the outside of the battery, must increase in accordance with the increase in volume. However, because the increase in cross-sectional area typically does not match 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 output power. Furthermore, when fast charging at high voltage, a large amount of heat is generated around the electrode tabs in a short period of time, which can lead to battery fire. Therefore, the present invention proposes a cylindrical battery that has a large volume to achieve high capacity while maintaining high safety.

[0537] In addition, since a high-loading electrode using the single particle or quasi-single particle positive electrode active material is applied to a cylindrical battery, the initial resistance characteristics and charge / discharge efficiency of the cylindrical battery can be improved.

[0538] The cylindrical battery according to an embodiment of the present invention significantly reduces the amount of gas generation compared to conventional batteries by applying a positive electrode active material in the form of a single particle or pseudo-single particle, thereby achieving excellent safety even in large cylindrical batteries with a form factor ratio of 0.4 or more.

[0539] The cylindrical battery according to an embodiment of the present invention is preferably a battery with a tabless structure that does not include electrode tabs, but is not limited thereto.

[0540] The tabless-structured battery may have a structure in which, for example, the positive electrode and the negative electrode each include an uncoated portion where no active material layer is formed, the positive electrode uncoated portion and the negative electrode uncoated portion are located at the upper end and the lower end of the electrode assembly, respectively, current collector plates are bonded to the positive electrode uncoated portion and the negative electrode uncoated portion, and the current collector plates are connected to electrode terminals.

[0541] When a cylindrical battery is formed with a tabless structure as described above, current concentration is reduced compared to conventional batteries with electrode tabs, which effectively reduces heat generation inside the battery, thereby improving the thermal stability of the battery.

[0542] The present invention will be described in more detail below with reference to specific examples.

[0543] Example 1 Average particle size D 50 The positive electrode active material Li[Ni 0.9 Co 0.06 Mn 0.03 Al 0.01 A cathode slurry was prepared by mixing O2, carbon nanotubes, and a PVDF binder in a weight ratio of 97.8:0.6:1.6 in N-methylpyrrolidone. The cathode slurry was applied to one side of an aluminum current collector sheet, dried at 120°C, and rolled to prepare a cathode.

[0544] Anode active material (graphite:SiO = 95:5 (weight ratio) mixture), conductive material (Super C), styrene-butadiene rubber (SBR), and 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 anodes.

[0545] The prepared positive and negative electrodes 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 prepared electrode assembly was inserted into a cylindrical battery can, and an electrolyte was injected to prepare a 4680 cell.

[0546] <Comparative Example 1> As a positive electrode active material, large particle size average particle size D 50 is 9 μm, and the small particle average particle size D 50 It has a bimodal particle size distribution with a particle size of 4 μm, and is in the form of secondary particles, Li[Ni 0.9Co 0.05 Mn 0.04 Al 0.01 4680 cells were fabricated in the same manner as in Example 1, except that ]O2 was used.

[0547] <Experimental Example 1> A hot box test was carried out on the 4680 cells manufactured according to Example 1 and Comparative Example 1.

[0548] Specifically, the 4680 cells prepared in Example 1 and Comparative Example 1 were placed in a hot box chamber at room temperature, heated to 130°C at a rate of 5°C / min, and maintained at that temperature for 30 minutes. The hot box evaluation was then performed to measure the temperature change over time. For accurate evaluation, the cell of Example 1 was subjected to two hot box evaluations. The measurement results are shown in Figures 45a and 45b.

[0549] 45a is a graph showing the results of a hot box test for the 4680 cell manufactured according to Example 1, and FIG. 45b is a graph showing the results of a hot box test for the 4680 cell manufactured according to Comparative Example 1. As shown in FIG.

[0550] 45a and 45b show 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 remained stable 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.

[0551] <Example 2-1> Unimodal particle size distribution min = 1.78 μm, D 50 = 4.23 μm, D max = 13.1 μm, and the positive electrode active material (composition: Li[Ni 0.9 Co 0.06 Mn 0.03 Al 0.01 ]O2) was prepared. Figure 44a shows an SEM photograph of the positive electrode active material used in Example 2-1.

[0552] The positive electrode active material, carbon nanotubes, and PVDF binder were mixed in N-methylpyrrolidone in a weight ratio of 97.8:0.6:1.6 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.

[0553] Anode active material (graphite:SiO = 95:5 (weight ratio) mixture), conductive material (Super C), styrene-butadiene rubber (SBR), and 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 anodes.

[0554] The prepared positive and negative electrodes 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 prepared electrode assembly was inserted into a battery can and an electrolyte was injected to prepare a 4680 cell.

[0555] <Example 2-2> As a positive electrode active material, D min = 1.38 μm, D 50 = 4.69 μm, D max = 18.5 μm, and the positive electrode active material (composition: Li[Ni 0.9 Co 0.06 Mn 0.03 Al 0.01 4680 cells were fabricated in the same manner as in Example 2-1, except that ]O2) was used. Figure 44b shows an SEM image of the positive electrode active material used in Example 2-2.

[0556] <Comparative Example 2-1> Large particle size average particle size D 50 is 9 μm, and the small particle average particle size D 50 The positive electrode active material (composition: Li[Ni 0.9Co 0.05 Mn 0.04 Al 0.01 ]O2) was used, a 4680 cell was produced in the same manner as in Example 2-1.

[0557] <Comparative Example 2-2> Unimodal particle size distribution min =0.892μm, D 50 = 3.02 μm, D max = 11 μm, and the positive electrode active material (composition: Li[Ni 0.9 Co 0.06 Mn 0.03 Al 0.01 ]O2) was used, a 4680 cell was produced in the same manner as in Example 2-1.

[0558] FIG. 44c shows an SEM photograph of the positive electrode active material used in Comparative Example 2-2.

[0559] <Experimental Example 2-1> A hot box test was carried out on the 4680 cells manufactured in Examples 2-1 and 2-2 and Comparative Examples 2-1 and 2-2.

[0560] Specifically, the 4680 cells prepared in Example 2-1 and Comparative Example 2-1 were placed in a hot box chamber at room temperature, heated to 130°C at a rate of 5°C / min, and maintained at that temperature for 30 minutes, after which the temperature change of the battery was measured. A case in which no thermal runaway or ignition occurred during the test was indicated as "pass," and a case in which thermal runaway and / or ignition occurred was indicated as "fail." To ensure test accuracy, the cells of Examples 2-1 and 2-2 were tested more than twice.

[0561] The measurement results are shown in Table 1 below and Figures 45c and 45d. Figure 45c is a graph showing the results of a hot box test for 4680 cells fabricated according to Sample 1 of Example 2-1 and Comparative Example 2-1, and Figure 45d is a graph showing the results of a hot box test for 4680 cells fabricated according to Samples 2 and 3 of Example 2-1, Samples 1 and 2 of Example 2-2, and Comparative Example 2-2.

[0562] [Table 1]

[0563] Referring to Table 1, Figures 45c and 45d, D min In the case of the 4680 cell of Example 2-1, which uses a positive electrode active material in the form of a single particle / quasi-single particle having a particle size of 1.0 μm or more, the battery voltage and temperature are maintained stable until 65 minutes have elapsed. min It can be seen that the 4680 cell of Comparative Example 2-2, which used a positive electrode active material in the form of a single particle / quasi-single particle having a particle size of less than 1.0 μm, experienced a rapid rise in battery temperature.

[0564] <Experimental Example 2-2> To check the degree of cracking of the positive electrode active material particles after rolling for the positive electrodes prepared in Example 2-1 and Comparative Example 2-1, the positive electrodes were cut using an ion milling machine and the cross sections were photographed using an SEM. Figure 46a shows an SEM cross-sectional image of the positive electrode prepared in Example 2-1, and Figure 46b shows an SEM cross-sectional image of the positive electrode prepared in Comparative Example 2-1.

[0565] 46a and 46b show that the positive electrode of Example 2-1 has almost no particle cracks in the positive electrode active material even after rolling, whereas the positive electrode of Comparative Example 2-2, which uses secondary particles, has many particle cracks in the positive electrode active material after rolling.

[0566] <Example 3-1> Unimodal particle size distribution 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 prepared positive electrode was measured. The porosity was 17.5%.

[0567] <Example 3-2> A positive electrode was manufactured 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 was 19%.

[0568] <Example 3-3> A positive electrode was manufactured 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 97.4:0.4:0.4:1.8, and the porosity of the positive electrode active material layer was measured. The porosity was 20%.

[0569] <Example 3-4> A positive electrode was manufactured 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 97.6:0.2:0.4:1.8, and the porosity of the positive electrode active material layer was measured. The porosity was 21%.

[0570] <Comparative Example 3-1> 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 at 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 was 24%.

[0571] <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, and the slurry was rolled at a linear pressure of 2.0 ton / cm. The porosity of the positive electrode active material layer was measured and found to be 30%.

[0572] <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 cells were charged to 4.25 V at a current of 0.2 C, and then discharged to 2.5 V at a current of 0.2 C to measure the charge capacity (mAh / g) and discharge capacity (mAh / g) of each coin-type half cell. The measurement results are shown in Table 2 below.

[0573] [Table 2]

[0574] It can be seen from Table 2 that Examples 3-1 to 3-4, which used positive electrodes containing flake graphite, exhibit lower porosity and superior capacity characteristics than Comparative Examples 3-1 and 3-2.

[0575] <Experimental Example 3-2. Confirmation of resistance characteristics> The resistance characteristics as a function of SOC were measured while charging 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. 47a.

[0576] 47a, 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, was lower than that of Comparative Examples 3-1 and 3-2, which did not contain flake graphite, based on an SOC of 10%. This indicates that adding flake graphite to the positive electrode active material layer has the effect of improving the resistance characteristics at low SOC.

[0577] <Experimental Example 3-3. Measurement of high-temperature life characteristics and resistance increase rate> A separator was interposed between the positive and negative electrodes of Examples 3-1, 3-3, and Comparative Example 3-1, and the positive and negative electrodes were stacked in this order of separator / positive electrode / separator / negative electrode and then wound up to prepare a jelly roll-type electrode assembly. The prepared electrode assembly was inserted into a cylindrical battery can, and an electrolyte was injected to prepare a 4680 cell.

[0578] The negative electrode was prepared by mixing a negative electrode active material (graphite:SiO = 95:5 (weight ratio) mixture), a 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, which was then applied to one side of a copper current collector sheet, dried at 150°C, and rolled.

[0579] The 4680 cell thus fabricated was subjected to 50 charge-discharge cycles, with one cycle consisting of charging to 4.2 V at 0.5 C at 40°C and discharging to 2.5 V at 0.5 C, and then the capacity retention and the rate of increase in resistance (DCIR) were measured. The measurement results are shown in Figure 47b.

[0580] Referring to Figure 47b, it can be seen that in the secondary batteries of Examples 3-1 and 3-3, the change in capacity retention rate according to the number of cycles is smaller than in the secondary battery of Comparative Example 3-1, and the change in resistance increase rate according to the number of cycles is also smaller.

[0581] As described above, the present invention has been described using limited embodiments and drawings, but the present invention is not limited thereto, and it goes without saying that various modifications and variations can be made by a person having ordinary knowledge in the technical field to which the present invention pertains within the technical spirit of the present invention and the equivalent scope of the claims. [Explanation of symbols]

[0582] 1 cylindrical battery 2-pack housing 3 Battery Pack 10 positive electrode 10a Positive electrode uncoated area 11 Negative electrode 11a Negative electrode uncoated area 12 Separation membrane 13 First electrode tab 14 Second electrode tab 20 Current collector 21 Active material 22 Plain area 23 Beading section 24 Crimping section 30 Current collector plate 31 Current collector plate 32 Plain area 33 Cavity 34 Peripheral Areas 35 First current collector plate 35a Support part 35b Plain part joining part 35c Housing contact 36 Second current collecting plate 40 Cap Plate 41 Venting section 43a Upper plain part 43b Lower plain part 50 spacer 51 Anti-movement part 52 Sealing part 53 Connecting part 53a extension leg 60 terminals 60 External terminal 61 Current collector 62 Active material layer 63 Plain area 64 insulating coating layer 80 Insulator 140 Cylindrical Battery 141 Electrode assembly 142 Battery Housing 143 Sealed body 143a Cap Plate 143b First gasket 143c connecting plate 143d Protrusion 144 First current collector plate 145 Second current collector plate 146 Insulators 146a First plain section 146b Second plain section 147 Beading section 148 Crimping section 149 leads 150 Cylindrical Battery 151 Lead hole 152 Venting section 160 Cylindrical Battery 170 Cylindrical Battery 171 Battery Housing 172 External terminal 172a Exposed terminal part 172b Terminal insertion part 173 Second gasket 173a Exposed gasket 173b Gasket insert 174 Insulators 176 Second current collector plate 178 Sealed body 178a Cap Plate 178b First gasket 179 Vent 180 Cylindrical Battery 181 Crimping section 190 Cylindrical Battery 200 Cylindrical Battery 210 Cylindrical Battery 220 cylindrical battery 300 electrode assembly 400 negative electrode 410 Negative electrode current collector 420 Negative electrode active material section 430 Negative electrode uncoated area 500 positive electrode 510 Positive electrode current collector 520 Cathode active material section 530 Positive electrode uncoated area 600 Separation membrane 700 negative electrode 710 Negative electrode current collector 720 Negative electrode active material section 730 Negative electrode uncoated area 800 positive electrode 810 Positive electrode current collector 820 Cathode active material section 830 Positive electrode uncoated area 900 Separation membrane

Claims

1. an electrode assembly in which a core and an outer circumferential surface are defined by winding a first electrode, a second electrode, and a separator interposed between the first and second electrodes around a winding shaft, the first electrode and the second electrode respectively including a first uncoated portion and a second uncoated portion that are not coated with an active material layer along the winding direction, at least one of the first uncoated portion and the second uncoated portion being defined as an electrode tab, the electrode assembly including a core-side uncoated portion adjacent to the core of the electrode assembly, an outer-circumferential uncoated portion adjacent to the outer surface of the electrode assembly, and an intermediate uncoated portion interposed between the core-side uncoated portion and the outer-circumferential uncoated portion, and at least one of the core-side uncoated portion and the outer-circumferential uncoated portion being relatively lower in height in the winding axis direction than the intermediate uncoated portion; a battery housing that accommodates the electrode assembly through an opening formed at a bottom end thereof; a first current collecting plate coupled to the first uncoated portion and positioned within the battery housing; a cap plate for covering the opening; a spacer disposed between the cap plate and the electrode assembly to fix the electrode assembly and seal the battery housing; an external terminal electrically connected to the second uncoated portion; Including, The spacer is a movement prevention portion interposed between the first current collecting plate and the cap plate; a sealing portion interposed between the battery housing and the cap plate to seal the battery housing; Including, Cylindrical battery.

2. The spacer further includes a connecting portion connecting the movement prevention portion and the sealing portion.

10. The cylindrical battery of claim 1.

3. The movement prevention portion has a height corresponding to the distance between the first current collecting plate and the cap plate.

3. The cylindrical battery according to claim 2.

4. The movement prevention portion is located at the center of the end portion of the electrode assembly in the winding axis direction.

3. The cylindrical battery according to claim 2.

5. the movement prevention portion includes a spacer hole formed at a position corresponding to a winding center hole of the electrode assembly; 3. The cylindrical battery according to claim 2.

6. The sealing portion has a shape extending along the periphery of the inner circumferential surface of the battery housing.

3. The cylindrical battery according to claim 2.

7. The battery housing includes: a beading portion formed by pressing in the periphery of the outer circumferential surface; a crimping portion whose end defines the opening below the beading portion and is bent to wrap around the periphery of the cap plate; The sealing portion is bent along the crimping portion to surround the periphery of the cap plate.

7. The cylindrical battery according to claim 6.

8. the connecting portion includes a plurality of extension legs extending from the motion prevention portion in a radial, cross, or combination thereof shape; the plurality of extension legs do not contact the cap plate; 3. The cylindrical battery according to claim 2.

9. The first current collector plate is a support portion located at the center of an end portion of the electrode assembly in the winding axis direction; a non-coating portion connecting portion extending from the support portion and connected to the first non-coating portion; a housing contact portion extending from the support portion or from an end of the plain portion coupling portion and interposed between the battery housing and the sealing portion, the housing contact portion contacts one surface of the beading portion facing the cap plate; The sealing portion is configured to be bent along the crimping portion to enclose the periphery of the cap plate and fill the gap between the housing contact portion and the cap plate.

8. The cylindrical battery of claim 7.

10. The cap plate is non-polar; 10. The cylindrical battery of claim 9.

11. The movement prevention portion covers the support portion so that the support portion is not exposed to the outside of the movement prevention portion.

10. The cylindrical battery of claim 9.

12. The connecting portion is positioned so as not to overlap with the housing contact portion along the winding axis direction.

10. The cylindrical battery of claim 9.

13. a second current collecting plate coupled to the second uncoated portion; an insulator interposed between a closing portion formed at an upper end of the battery housing and the second current collecting plate, the external terminal is electrically connected to the second uncoated portion through the insulator.

10. The cylindrical battery of claim 1.

14. the external terminal is a rivet terminal insulatively attached to a through hole formed in a center portion of the closing portion, and a peripheral edge of an end portion facing the second uncoated portion is riveted toward an inner surface of the closing portion, The end of the external terminal is welded to the second current collector plate.

14. The cylindrical battery of claim 13.

15. At least a portion of the intermediate plain portion includes a plurality of independently foldable segments. The cylindrical battery according to any one of claims 1 to 14.

16. At least one of the height in the winding axial direction and the width in the winding direction of the plurality of segments increases stepwise from the core side to the outer periphery side individually or for each group.

16. The cylindrical battery of claim 15.

17. The plurality of segment pieces form a plurality of segment piece groups from the core side toward the outer periphery side, and the segment pieces belonging to the same segment piece group are identical to each other in at least one of the width in the winding direction, the height in the winding axial direction, and the separation pitch in the winding direction.

16. The cylindrical battery of claim 15.

18. The segments belonging to the same segment group have at least one of a width in the winding direction, a height in the winding axial direction, and a separation pitch in the winding direction that increases stepwise from the core side to the outer periphery side.

18. The cylindrical battery of claim 17.

19. The plurality of segments are folded toward the core and overlap each other along the winding axis direction.

16. The cylindrical battery of claim 15.

20. An electrode assembly in which a core and an outer peripheral surface are defined by winding a first electrode, a second electrode, and a separation membrane interposed between the first and second electrodes around a winding shaft, wherein the first and second electrodes respectively include a first uncoated portion and a second uncoated portion that are not coated with an active material layer along the winding direction, at least one of the first uncoated portion and the second uncoated portion being defined as an electrode tab, and including a core-side uncoated portion adjacent to the core of the electrode assembly, an outer-side uncoated portion adjacent to the outer peripheral surface of the electrode assembly, and an intermediate uncoated portion interposed between the core-side uncoated portion and the outer-side uncoated portion, and at least one of the core-side uncoated portion and the outer-side uncoated portion having a height in the winding axis direction that is relatively lower than that of the intermediate uncoated portion. a battery housing that accommodates the electrode assembly through an opening formed at a bottom end thereof; a first current collecting plate coupled to the first uncoated portion and positioned within the battery housing; a cap plate for covering the opening; a spacer disposed between the cap plate and the electrode assembly to fix the electrode assembly and seal the battery housing; an external terminal electrically connected to the second uncoated portion; Including, At least a portion of the intermediate plain portion includes a plurality of independently foldable segments, The plurality of segments are folded toward the core and overlap each other along the winding axis direction, a radial length R of the core-side uncoated portion and a bending length H of the innermost segment of the intermediate uncoated portion satisfy the relational expression "H≦R"; Cylindrical battery.

21. a gap is provided between the lower end of the cutting line of the divided piece and the active material layer; 16. The cylindrical battery of claim 15.

22. a first sliding portion in which the thickness of the active material layer is reduced in a boundary region between the coated portion and the uncoated portion of the first electrode; a second sliding portion in which the thickness of the active material layer is reduced in a boundary region between the coated portion and the uncoated portion of the second electrode; The first sliding portion and the second sliding portion are located in opposite directions in the winding axis direction. The cylindrical battery according to any one of claims 1 to 14.

23. the land portion of the first electrode includes a loading reduction portion where a loading amount of an active material is reduced, The position of the loading reduction portion corresponds to the position of the second sliding portion.

23. The cylindrical battery of claim 22.

24. the active material layer of the first electrode includes a positive electrode active material including a single particle, a quasi-single particle, or a combination thereof; The minimum particle size D appearing in the volume cumulative distribution of the positive electrode active material ｍｉｎ is 1.0 μm or more, The particle size D when the cumulative volume is 50% in the cumulative volume distribution of the positive electrode active material ５０ is 5.0 μm or less, The maximum particle size D appearing in the volume cumulative distribution of the positive electrode active material ｍａｘ is 12 μm to 17 μm, The cylindrical battery according to any one of claims 1 to 14.

25. The positive electrode active material has a unimodal particle size distribution in which a single peak appears in a volume cumulative particle size distribution graph, and is represented by the following equation 1: [Formula 1] Particle size distribution (PSD) = (D ｍａｘ -D ｍｉｎ ) / D ５０ The particle size distribution (PSD) represented by is 3 or less, 25. The cylindrical battery of claim 24.

26. The single particles, quasi-single particles, or a combination thereof are 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 first electrode.

25. The cylindrical battery of claim 24.

27. The positive electrode active material includes a lithium nickel-based oxide containing Ni in an amount of 80 mol% or more based on the total number of moles of transition metals.

25. The cylindrical battery of claim 24.

28. the porosity of the active material layer of the first electrode is 15% to 23%; the active material layer of the first electrode contains flake graphite at a weight ratio of 0.05 wt % to 5 wt %; 25. The cylindrical battery of claim 24.

29. the active material layer of the first electrode further contains carbon nanotubes; 25. The cylindrical battery of claim 24.

30. the active material layer of the second electrode includes a silicon-based negative electrode active material and a carbon-based negative electrode active material, 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.

25. The cylindrical battery of claim 24.

31. A battery pack comprising a plurality of cylindrical batteries according to any one of claims 1 to 14.

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

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