Cylindrical battery, battery pack including the same, and automobile

Abstract

A cylindrical battery according to one embodiment of the present invention includes an electrode assembly, a battery housing that receives the electrode assembly through an opening, a first current collecting plate located within the battery housing, the first current collecting plate including a support disposed on the electrode assembly, at least one tab connecting portion extending from the support portion, and at least one housing connecting portion extending from an end of the tab connecting portion and connected to an inner surface of the battery housing, a cap plate that covers the opening, a terminal that penetrates the battery housing from the opposite side of the opening, and a sealing spacer configured to prevent movement of the electrode assembly and strengthen the sealing force of the battery housing.

Description

[Technical Field]

[0001] The present invention relates to a cylindrical battery and a current collector plate applied thereto, a battery pack including such a cylindrical battery, and an automobile.

[0002] More specifically, one embodiment of the present invention relates to a cylindrical battery having a structure that prevents stress from concentrating on welded portions between components even when external impacts or vibrations are applied during use of the battery, a current collector plate applied thereto, and a battery pack and a vehicle including the same.

[0003] Another embodiment of the present invention relates to a positive electrode for an electrochemical device having improved electrochemical properties and an electrode assembly including the positive electrode.

[0004] This application claims priority based on Korean Patent Application No. 10-2021-0142184, 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]

[0005] Secondary batteries, which have high applicability to each product group and electrical properties such as high energy density, 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.

[0006] These secondary 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.

[0007] Currently, secondary 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 such unit secondary battery cells is approximately 2.5V to 4.5V. Therefore, when 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.

[0008] Meanwhile, known types of secondary battery cells include cylindrical, prismatic, and pouch-type batteries. In the case of cylindrical batteries, a separator, which is an insulator, is interposed between the positive and negative electrodes and wound up to form a jelly-roll-type electrode assembly. This is then inserted into a battery housing together with an electrolyte to form a battery. Strip-shaped electrode tabs are connected to the uncoated portions of each of the positive and negative electrodes, electrically connecting the electrode assembly to the electrode terminals exposed to the outside. For reference, the positive terminal is a cap plate of a sealed body that seals the opening of the battery housing, and the negative terminal is the battery housing.

[0009] However, conventional cylindrical batteries having such a structure have problems such as high resistance, excessive heat generation, and poor current collection efficiency because current is concentrated in the strip-shaped electrode tabs connected to the positive electrode uncoated region and / or the negative electrode uncoated region.

[0010] Resistance and heat generation are not major issues with small cylindrical batteries with form factors such as 18650 and 21700. 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.

[0011] 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.

[0012] The conventional cylindrical battery will be described in more detail with reference to FIGS.

[0013] 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 folded surface of the uncoated portion. Figure 4 is a cross-sectional view of the tabless cylindrical battery cut in the longitudinal direction (Y axis).

[0014] 1 to 4, the positive electrode 500 includes a positive electrode active material part 520 on a positive electrode sheet 500S, and a positive electrode uncoated part 530 on one long side along the winding direction. The negative electrode 400 includes a negative electrode active material part 420 on a negative electrode sheet 400S, and a negative electrode uncoated part 430 on one long side along the winding direction. The electrode assembly 300 is fabricated by stacking the positive electrode 500 and the negative electrode 400 together with two separators 600 in order as shown in FIG. 2, and then winding them in one direction (the X-axis direction). The uncoated part 530 of the positive electrode 500 and the uncoated part 430 of the negative electrode 400 are arranged in opposite directions.

[0015] After the winding process, the uncoated portion 530 of the positive electrode 500 and the uncoated portion 430 of the negative electrode 400 are bent toward the core, and then the current collector plates P and 30 are welded to the uncoated portions 530 and 430, respectively.

[0016] No separate electrode tabs are attached to the positive electrode uncoated region 530 and the negative electrode uncoated region 430, and the current collector plate P, 30 is connected to an external electrode terminal, forming a current path with a large cross-sectional area along the winding axis direction of the electrode assembly 300 (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.

[0017] However, as the form factor of cylindrical batteries increases and the charging current during fast charging increases, the heat generation problem reoccurs in tableless cylindrical batteries.

[0018] Specifically, as shown in Figure 4, a conventional tabless cylindrical battery 1 includes a battery housing 20 and a sealing body A. The sealing body A includes a cap plate 40, a sealing gasket G1, and a connecting plate C1. The sealing gasket G1 covers the periphery of the cap plate 40 and is fixed by a crimping portion 22. In addition, the electrode assembly 300 is fixed in the battery housing 20 by a beading portion 21 to prevent vertical movement.

[0019] Typically, the positive electrode terminal is the cap plate 40 of the sealed body A, and the negative electrode terminal is the battery housing 20. Therefore, the second current collecting plate P coupled to the uncoated portion 530 of the positive electrode 500 is electrically connected to the connecting plate C1 attached to the cap plate 40 through a strip-shaped lead L. Also, the first current collecting plate 30 coupled to the uncoated portion 430 of the negative electrode 400 is electrically connected to the bottom of the battery housing 20. An insulator S covers the second current collecting plate P to prevent contact between the battery housing 20 and the uncoated portion 530 of the positive electrode 500, which have opposite polarities, and causing a short circuit.

[0020] A strip-shaped lead L is used when the second current collector P is connected to the connecting plate C1. The lead L is either separately attached to the second current collector P or manufactured integrally with the second current collector P. However, because the lead L is a thin strip, its cross-sectional area is small, and a large amount of heat is generated when a fast charging current flows. In addition, the excessive heat generated in the lead L is transferred to the electrode assembly 300, causing the separator 600 to contract, which can lead to an internal short circuit, a major cause of thermal runaway.

[0021] The leads L also occupy a considerable amount of installation space within the battery housing 20. Therefore, the cylindrical battery 1 including the leads L has low space efficiency and is limited in increasing the energy density.

[0022] Furthermore, connecting conventional tableless cylindrical batteries 1 in series and / or parallel requires connecting busbar components to the cap plate 40 of the sealed body A and the bottom of the battery housing 20, resulting in reduced space efficiency. A battery pack installed in an electric vehicle contains hundreds of cylindrical batteries 1. Therefore, inefficiencies in electrical wiring cause considerable inconvenience during the electric vehicle assembly process and battery pack maintenance. Therefore, there is a need for the development of a cylindrical battery with a structure in which positive and negative terminals are applied in the same direction, which simplifies the electrical connection structure of multiple cylindrical batteries.

[0023] In a cylindrical battery having the above-described structure, a relatively large empty space may be formed between the negative electrode current collector and the cap plate, and an empty space may also be formed between the bottom surface of the battery housing opposite the cap plate and the positive electrode current collector.

[0024] Such empty spaces can cause the jelly-roll-type electrode assembly to swing up and down inside the battery housing, particularly in the vertical direction of the cylindrical battery. Such vertical movement of the electrode assembly can damage the connection between the current collector plate and the electrode tab, and can also damage the connection between the current collector plate and the battery housing, and the connection between the current collector plate and the battery terminal.

[0025] Therefore, it is necessary to minimize the space required for the electrode assembly to move. Furthermore, if additional components are added to reduce the space required for the electrode assembly to move, the process becomes more complicated and the manufacturing cost increases. Therefore, it is necessary to solve these problems by utilizing components that are already in use.

[0026] Meanwhile, conventional cylindrical batteries generally have a structure in which tabs connecting an electrode assembly to an external terminal are welded to the foil of the electrode assembly. However, cylindrical batteries with this structure have a limited current path, which inevitably leads to an excessive increase in the self-resistance of the electrode assembly.

[0027] Therefore, attempts have been made to reduce the resistance by increasing the number of tabs connecting the electrode assembly and the external terminals, but there are limitations to reducing the resistance to a desired level and ensuring a sufficient current path simply by increasing the number of tabs.

[0028] Therefore, in order to reduce the self-resistance of the electrode assembly, it is necessary to develop a new electrode assembly structure and a current collector plate structure suitable for such an electrode assembly structure. In particular, the need for such new electrode assemblies and current collector plates is even greater in applications to devices that require high-output / high-capacity battery packs, such as electric vehicles.

[0029] There is also a need to develop a cylindrical battery having a structure that maintains an improved bonding strength between the current collector plate and the battery housing, and a current collector plate structure that can be applied to such a cylindrical battery.

[0030] On the other hand, when an electrode is manufactured using a conventional cathode active material containing 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.

[0031] 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]

[0032] The present invention has been made in consideration of the above-mentioned problems, and aims to provide a current collector plate having a structure suitable for an electrode assembly having a low resistance structure, and a cylindrical battery including the same.

[0033] Another object of the present invention is to provide a current collector having a structure capable of improving the bonding strength at the bonding portion between the current collector and the battery housing, and a cylindrical battery including the same.

[0034] Yet another object is to prevent damage to electrical connections caused by movement of the jelly roll within the battery housing.

[0035] Another object of the present invention is to prevent movement of an electrode assembly by utilizing components that are already applied in manufacturing a cylindrical battery, thereby preventing the complication of manufacturing processes and the increase in manufacturing costs that would occur due to the application of additional components.

[0036] Another object of the present invention is to provide a current collector having a structure capable of improving the energy density of a cylindrical battery, and a cylindrical battery including the same.

[0037] Another object of the present invention is to provide a current collector plate having a structure that can improve the convenience of a welding process for electrically connecting a battery housing and a current collector plate in manufacturing a cylindrical battery, thereby improving productivity, and a cylindrical battery including the same.

[0038] 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.

[0039] Another object of the present invention is to provide an electrode and an electrode assembly including the same, which can achieve excellent thermal stability by using single particles or pseudo-single particles as a positive electrode active material, and have high electrical conductivity and excellent rolling characteristics.

[0040] 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.

[0041] 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.

[0042] Another object of the present invention is to provide a cylindrical battery that can exhibit excellent thermal stability even when the volume of the battery increases due to an increase in the form factor.

[0043] 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]

[0044] In order to solve the above-mentioned problems, one aspect of the present invention provides a cylindrical battery including: an electrode assembly having a first electrode tab and a second electrode tab; a battery housing that receives the electrode assembly through an opening formed on one side; a support disposed on one side of the electrode assembly; at least one tab connecting portion extending from the support and connected to the first electrode tab; and at least one housing connecting portion extending from an end of the tab connecting portion and connected to an inner surface of the battery housing; a first current collecting plate located within the battery housing; a cap plate that covers the opening; a battery terminal that penetrates the battery housing from the opposite side of the opening and is electrically connected to the second electrode tab; and a sealing spacer configured to prevent movement of the electrode assembly and strengthen the sealing force of the battery housing.

[0045] The battery housing may include a beading portion formed on a peripheral edge adjacent to the opening and pressed inward.

[0046] The housing coupling portion may be coupled onto the beading portion.

[0047] The housing coupling portion may include a contact portion coupled onto the beading portion, and a coupling portion connecting the tab coupling portion and the contact portion.

[0048] The cylindrical battery may include a sealing gasket disposed between the battery housing and the cap plate.

[0049] The contact portion may be interposed and fixed between a beading portion of the battery housing and the sealing gasket.

[0050] In the cylindrical battery, a weld may be formed between the beading portion of the battery housing and the contact portion of the current collector plate.

[0051] In the cylindrical battery, a boundary region between the tab connecting portion and the housing connecting portion may be located inside an innermost portion of the beading portion.

[0052] The cylindrical battery may include a plurality of tab coupling portions and a plurality of housing coupling portions.

[0053] The connecting portion may include at least one bent portion where an extending direction is changed.

[0054] The contact portion may have an arc shape extending along the beading portion of the battery housing.

[0055] The connecting portion may have an arc shape extending along the contact portion.

[0056] The sealing 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.

[0057] The movement prevention portion may have a height corresponding to the distance between the first current collecting plate and the cap plate.

[0058] The movement prevention portion may be located at a center portion on one surface of the electrode assembly.

[0059] The movement prevention portion may include a spacer hole formed at a position corresponding to a winding center hole of the electrode assembly.

[0060] The sealing portion may extend along an inner circumferential surface of the battery housing.

[0061] The linkage may include a plurality of extension legs extending radially from the motion prevention portion.

[0062] The extension legs may be configured not to contact the first current collector plate.

[0063] The extension legs may be configured to not contact the cap plate.

[0064] The connecting portion may be positioned so as not to overlap with the housing connecting portion along a height direction of the cylindrical battery.

[0065] The cylindrical battery may further include a second current collector plate coupled to the second electrode tab, and an insulator interposed between a closing portion formed at an upper end of the battery housing and the second current collector plate.

[0066] The insulator may have a height corresponding to the distance between the second current collector and the closure.

[0067] The active material layer of the second electrode includes a positive electrode active material including a single particle, a quasi-single particle, or a combination thereof, and the positive electrode active material has a minimum particle size D min is 1.0 μm or more, and the particle size D when the volume cumulative amount is 50% in the volume cumulative distribution of the positive electrode active material 50 is 5.0 μm or less, and the maximum particle size D appearing in the volume cumulative distribution of the positive electrode active material is max can be 12 μm to 17 μm.

[0068] 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:

[0069] [Formula 1] Particle size distribution (PSD)=(D max -D min ) / D 50 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 second electrode.

[0070] 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.

[0071] The active material layer of the second electrode may have a porosity of 15% to 23%, and may contain flake graphite at a weight ratio of 0.05 wt % to 5 wt %.

[0072] The active material layer of the second electrode may further include carbon nanotubes (CNTs).

[0073] The first electrode active material layer may include a silicon-based negative electrode active material and a carbon-based negative electrode active material, and the silicon-based negative electrode active material and the carbon-based negative electrode active material may be included in a weight ratio of 1:99 to 20:80.

[0074] A battery pack according to another aspect of the present invention includes the cylindrical battery according to the above-described aspect of the present invention.

[0075] A motor vehicle according to yet another aspect of the present invention includes the battery pack according to the above-described aspect of the present invention. [Effects of the Invention]

[0076] According to one aspect of the present invention, the resistance in the electrical connection between the electrode assembly and the battery housing can be significantly reduced.

[0077] Furthermore, according to one aspect of the present invention, the bonding strength of the bonding portion between the current collector plate and the battery housing can be improved.

[0078] Furthermore, according to one embodiment of the present invention, the energy density of a cylindrical battery can be improved.

[0079] Furthermore, according to one aspect of the present invention, in manufacturing a cylindrical battery, the convenience of a welding process for electrically connecting a battery housing and a current collector plate can be improved, thereby improving productivity.

[0080] Furthermore, according to one aspect of the present invention, movement of the jelly roll within the battery housing is minimized, thereby preventing damage to electrical connections.

[0081] Furthermore, according to one aspect of the present invention, instead of applying additional parts to prevent the jelly roll from moving, the parts that are already applied can be utilized, thereby preventing the manufacturing process from becoming more complicated and the manufacturing costs from increasing.

[0082] According to another aspect of the present invention, D min By 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.

[0083] 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.

[0084] 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.

[0085] 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.

[0086] 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.

[0087] 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.

[0088] 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.

[0089] The effects of the present invention are not limited to those described above, and other effects not mentioned will be clearly understood by those skilled in the art from the following description of the invention.

[0090] 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]

[0091] [Figure 1]1 is a plan view showing the structure of an electrode used in a conventional tabless cylindrical battery cell. [Figure 2] 1A and 1B are views showing a winding process of an electrode assembly included in a conventional tabless cylindrical battery cell. [Figure 3] 3 is a view showing a process of welding a current collector plate to a bent surface of an uncoated portion in the electrode assembly of FIG. 2. FIG. [Figure 4] FIG. 1 is a cross-sectional view of a conventional tabless cylindrical battery cell cut in the longitudinal direction (Y axis). [Figure 5] 1 is a longitudinal cross-sectional view showing a portion of a cylindrical battery according to an embodiment of the present invention. [Figure 6] 10 is a longitudinal cross-sectional view showing a portion of a cylindrical battery according to another embodiment of the present invention. [Figure 7] 10 is a longitudinal cross-sectional view showing a portion of a cylindrical battery according to yet another embodiment of the present invention. [Figure 8] 8 is a view illustrating a first current collecting plate included in the cylindrical battery of FIG. 7. FIG. [Figure 9] FIG. 6 is a view illustrating a first current collecting plate according to another embodiment of the present invention. [Figure 10] FIG. 10 is a view illustrating a first current collecting plate according to still another embodiment of the present invention. [Figure 11] 1 is a perspective view showing the appearance of a cylindrical battery according to an embodiment of the present invention; [Figure 12] 1 is a cross-sectional view showing the internal structure of a cylindrical battery according to an embodiment of the present invention. [Figure 13] 4 is a partial cross-sectional view showing an area where a sealing spacer is applied according to an embodiment of the present invention; [Figure 14] 1A and 1B are views illustrating a sealing spacer according to an embodiment of the present invention; [Figure 15] 1 is a plan view showing the bottom surface of a cylindrical battery according to an embodiment of the present invention; [Figure 16] 1 is a partial cross-sectional view showing an area where an insulator is applied according to an embodiment of the present invention; [Figure 17]3 is a partial cross-sectional view showing a coupling structure between a current collecting plate and an electrode tab according to an embodiment of the present invention; [Figure 18] 1 is a schematic diagram illustrating a battery pack according to an embodiment of the present invention. [Figure 19] 1 is a conceptual diagram showing a vehicle according to an embodiment of the present invention; [Figure 20] 1 is a scanning electron microscope (SEM) photograph of a novel CNT according to one embodiment of the present invention. [Figure 21] This is a scanning electron microscope (SEM) photograph of a commonly used conventional carbon nanotube (conventional CNT). [Figure 22] 1 is a table comparing the physical properties of conventional CNTs and the physical properties of new CNTs. [Figure 23] 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 24] 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 25] 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 26] 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 27] 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 28a] 2 is a SEM photograph of the positive electrode active material used in Example 2-1 of the present invention. [Figure 28b] 2 is a SEM photograph of the positive electrode active material used in Example 2-2 of the present invention. [Figure 28c]1 is a SEM photograph of the positive electrode active material used in Comparative Example 2-2 of the present invention. [Figure 29a] 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 29b] 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 29c] 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 29d] 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 30a] 2 is a cross-sectional SEM photograph of a positive electrode produced in Example 2-1 of the present invention. [Figure 30b] 1 is a cross-sectional SEM photograph of a positive electrode produced in Comparative Example 2-1. [Figure 31a] 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 31b] 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 32] 1 is a diagram illustrating an electrode assembly according to an embodiment of the present invention. [Figure 33] FIG. 33 is a cross-sectional view taken along line AA' in FIG. 32. [Figure 34] 1A to 1C are diagrams illustrating a process for manufacturing a negative electrode according to an embodiment of the present invention. [Figure 35] 1A to 1C are diagrams illustrating a process for manufacturing a negative electrode according to an embodiment of the present invention. [Figure 36] 1 is a perspective view showing a negative electrode according to an embodiment of the present invention. [Figure 37] 1A to 1C are diagrams illustrating a process for manufacturing a positive electrode according to one embodiment of the present invention. [Figure 38] 1A to 1C are diagrams illustrating a process for manufacturing a positive electrode according to one embodiment of the present invention. [Figure 39] FIG. 1 is a perspective view showing a positive electrode according to one embodiment of the present invention. [Figure 40] 10 is a diagram illustrating an electrode assembly according to a comparative example of the present invention. [Figure 41] FIG. 41 is a cross-sectional view taken along the line BB' in FIG. 40. [Figure 42] 1 is a diagram showing a process for producing a negative electrode according to a comparative embodiment of the present invention. [Figure 43] FIG. 1 is a diagram showing a process for producing a positive electrode according to a comparative embodiment of the present invention. [Figure 44] 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

[0092] 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.

[0093] 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.

[0094] 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.

[0095] 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.

[0096] 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.

[0097] 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.

[0098] 5, a cylindrical battery 1 according to an embodiment of the present invention includes an electrode assembly 300, a battery housing 20, a first current collector 30, a cap plate 40, and a battery terminal 60. The cylindrical battery 1 may further include a sealing gasket G1 and / or an insulating gasket G2 and / or a second current collector P and / or an insulator S.

[0099] The electrode assembly 300 includes a first electrode tab 11 and a second electrode tab 12. The electrode assembly 300 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 is an electrode having the opposite polarity to the first electrode. More specifically, the electrode assembly 300 may be manufactured by winding up a stack formed by sequentially stacking a first electrode, a separator, a second electrode, and a separator at least once. That is, the electrode assembly 300 used in the present embodiment may be a jelly-roll type electrode assembly. Such a jelly-roll type electrode assembly 300 may include a winding center hole H1 formed approximately at its center and extending along the height direction (a direction parallel to the height direction of the cylindrical battery 1 shown in FIG. 5). Meanwhile, a separator may be further provided on the outer periphery of the electrode assembly 300 for insulation from the battery housing 20.

[0100] The first electrode includes a first electrode current collector and a first electrode active material layer coated on one or both sides of the first electrode current collector. An uncoated portion where the first electrode active material is not coated is present at one end of the first electrode current collector in the width direction (parallel to the height direction of the cylindrical battery 1 shown in FIG. 5). The uncoated portion of the first electrode extends from one end to the other end along the length of the first electrode when the first electrode is unfolded. The uncoated portion of the first electrode functions as the first electrode tab 11 described above. The first electrode tab 11 is provided at the upper portion of the electrode assembly 300 in the height direction (parallel to the height direction of the cylindrical battery 1 shown in FIG. 5) housed within the battery housing 20. The first electrode tab 11 may be, for example, a negative electrode tab.

[0101] The second electrode includes a second electrode current collector and a second electrode active material layer coated on one or both sides of the second electrode current collector. An uncoated portion, where the second electrode active material is not coated, exists at the other end of the second electrode current collector in the width direction (a direction parallel to the height direction of the cylindrical battery 1 shown in FIG. 5). The uncoated portion of the second electrode extends from one end to the other end along the length of the second electrode when the second electrode is unfolded. The uncoated portion of the second electrode functions as the second electrode tab 12 described above. The second electrode tab 12 is provided at the lower portion in the height direction of the electrode assembly 300 housed in the battery housing 20. The second electrode tab 12 may be, for example, a positive electrode tab.

[0102] That is, the first electrode tab 11 and the second electrode tab 12 extend in opposite directions along the height direction of the cylindrical battery 1 and protrude.

[0103] However, the present invention is not limited to this form of the electrode assembly 300.

[0104] The battery housing 20 is a generally cylindrical container having an opening on one side and is made of a conductive metal material. The side surface and the bottom surface (bottom surface in FIG. 5 ) of the battery housing 20 opposite the opening may be integrally formed. That is, the battery housing 20 may have an open upper end in its height direction and a closed lower end. The bottom surface of the battery housing 20 may have a generally flat shape. The battery housing 20 accommodates the electrode assembly 300 through an opening formed on one side in its height direction. The battery housing 20 may also accommodate an electrolyte through the opening. However, the present invention is not limited to this shape of the battery housing 20.

[0105] The battery housing 20 is electrically connected to the electrode assembly 300. The battery housing 20 is connected to the first electrode tab 11 of the electrode assembly 300. Therefore, the battery housing 20 has the same electrical polarity as the first electrode tab 11.

[0106] The battery housing 20 may include a beading portion 21 formed on a peripheral edge adjacent to the opening and pressed inward. The battery housing 20 may have the beading portion 21 formed on an upper end portion. The battery housing 20 may further include a crimping portion 22 formed above the beading portion 21. The beading portion 21 has a shape in which the periphery of the battery housing 20 is pressed to a predetermined depth. The beading portion 21 is formed on the upper portion of the electrode assembly 300. The inner diameter of the battery housing 20 in the region where the beading portion 21 is formed is smaller than the diameter of the electrode assembly 300.

[0107] The beading portion 21 provides a support surface on which the cap plate 40 is placed. The beading portion 21 may also provide a support surface on which at least a portion of the periphery of the first current collecting plate 30 (described later) is placed and coupled. That is, at least a portion of the periphery of the first current collecting plate 30 according to an embodiment of the present invention and / or the periphery of the cap plate 40 according to an embodiment of the present invention may be placed on an upper surface of the beading portion 21. As shown in FIGS. 6 and 7 , at least a portion of the upper surface of the beading portion 21 may extend in a direction substantially parallel to the lower surface of the battery housing 20, i.e., in a direction substantially perpendicular to the sidewall of the battery housing 20, so as to stably support at least a portion of the periphery of the first current collecting plate 30 and / or the periphery of the cap plate 40.

[0108] The crimping portion 22 is formed on the beading portion 21. The crimping portion 22 is extended and bent to enclose the periphery of the cap plate 40 disposed on the beading portion 21. The shape of the crimping portion 22 allows the cap plate 40 to be fixed onto the beading portion 21. Of course, the crimping portion 22 may be omitted, and the cap plate 40 may be fixed while covering the opening of the battery housing 20 using another fixing structure.

[0109] Hereinafter, the first current collecting plate 30 according to an embodiment of the present invention will be described in detail with reference to FIGS.

[0110] 7, a first current collecting plate 30 according to an embodiment of the present invention is accommodated inside the battery housing 20 and is electrically connected to the electrode assembly 300 and the battery housing 20. That is, the first current collecting plate 30 electrically connects the electrode assembly 300 and the battery housing 20.

[0111] The first current collector plate 30 includes a support portion 31 disposed on one side of the electrode assembly 300, at least one tab coupling portion 32 extending from the support portion 31 and coupled to the first electrode tab 11, and at least one housing coupling portion 33 extending from an end of the tab coupling portion 32 and coupled to the inner surface of the battery housing 20, and is positioned within the battery housing.

[0112] The support portion 31 and the at least one tab coupling portion 32 are disposed on the upper portion of the electrode assembly 300, and may be located below the beading portion 21 if the beading portion 21 is formed on the battery housing 20.

[0113] The support part 31 may have a first current collecting plate hole H2 formed at a position corresponding to a winding center hole H1 formed at approximately the center of the electrode assembly 300. The winding center hole H1 and the first current collecting plate hole H2, which are connected to each other, may function as a passage for inserting a welding rod or irradiating a laser for welding a battery terminal 60 and a second current collecting plate P, or for welding the battery terminal 60 and a lead tab (not shown), which will be described later.

[0114] The support part 31 may be in the form of a substantially circular plate. For example, referring to Fig. 8, the support part 31 may be in the form of a ring-shaped plate having a first current collecting plate hole H2 at its center.

[0115] The at least one tab coupling portion 32 may extend radially from the support portion 31 toward the side wall of the battery housing 20. For example, a plurality of tab coupling portions 32 may be provided. For example, referring to FIG. 8, the plurality of tab coupling portions 32 may be spaced apart from one another along the circumference of the support portion 31. As such, the cylindrical battery 1 according to an embodiment of the present invention includes a plurality of tab coupling portions 32, thereby increasing the coupling area with the first electrode tab 11. This ensures a strong coupling force between the first electrode tab 11 and the tab coupling portions 32 and reduces electrical resistance.

[0116] The longitudinal end of the tab coupling portion 32 may be located more inward than the innermost portion of the beading portion 21 formed on the battery housing 20. More specifically, the boundary region between the tab coupling portion 32 and the housing coupling portion 33 may be located more inward toward the winding center hole H1 than the innermost portion of the beading portion 21 formed on the battery housing 20. This structure prevents damage to the coupling portions between components that may be caused by excessively bending the first current collecting plate 30 to position the end of the housing coupling portion 33 on the beading portion 21.

[0117] Meanwhile, in order to secure a bonding strength and reduce electrical resistance by increasing the bonding area between the first current collector plate 30 and the electrode assembly 300, not only the tab coupling portion 32 but also the support portion 31 may be coupled to the first electrode tab 11. The end of the first electrode tab 11 may be formed in a shape that is bent parallel to the tab coupling portion 32. When the end of the first electrode tab 11 is shaped in this way and coupled to the tab coupling portion 32 in a state that is parallel to the tab coupling portion 32, the bonding area is increased, thereby improving the bonding strength and reducing the electrical resistance, and the overall height of the electrode assembly 300 is minimized, thereby improving the energy density.

[0118] The housing coupling portion 33 may extend from an end of the tab coupling portion 32 and be coupled to the inner surface of the battery housing 20. For example, the housing coupling portion 33 may extend from an end of the tab coupling portion 32 toward a sidewall of the battery housing 20. For example, a plurality of housing coupling portions 33 may be provided. For example, referring to FIG. 8, the plurality of housing coupling portions 33 may be spaced apart from one another around the support portion 31. Referring to FIG. 5, the housing coupling portion 33 may be coupled to a beading portion 21 on the inner surface of the battery housing 20. As shown in FIGS. 6 and 7, the upper surface of the beading portion 21 extends in a direction substantially parallel to the lower surface of the battery housing 20, i.e., in a direction substantially perpendicular to the sidewall of the battery housing 20, and the housing coupling portion 33 also extends in the same direction, allowing the housing coupling portion 33 to stably contact the beading portion 21. In addition, since the housing coupling portion 33 is in stable contact with the beading portion 21, welding between the two components is performed smoothly, thereby improving the coupling strength between the two components and minimizing resistance at the coupling portion. Also, since the first current collecting plate 30 is coupled to the beading portion 21 of the battery housing 20 rather than to the inner surface of the cylindrical portion of the battery housing 20, the distance between the first current collecting plate 30 and the beading portion 21 is reduced. Therefore, dead space inside the battery housing 20 is minimized, and the energy density of the cylindrical battery 1 can be improved.

[0119] 7 and 8, the housing coupling part 33 includes a contact part 33a coupled to the inner surface of the battery housing 20, and a coupling part 33b connecting the tab coupling part 32 and the contact part 33a.

[0120] The contact portion 33a is coupled to the inner surface of the battery housing 20. When the beading portion 21 is formed on the battery housing 20, the contact portion 33a may be coupled to the beading portion 21 as described above. In this case, as described above, for stable contact and coupling, the beading portion 21 and the contact portion 33a may all extend in a direction substantially parallel to the bottom surface of the battery housing 20, i.e., in a direction substantially perpendicular to the side wall of the battery housing 20.

[0121] 7, the connecting portion 33b may have at least one bent portion B where its extending direction is changed between the support portion 31 and the contact portion 33a. That is, the connecting portion 33b may have, for example, a spring-like or bellows-like structure that can contract and expand within a certain range. This structure of the connecting portion 33b allows the contact portion 33a to be tightly attached to the beading portion 21 during the process of inserting the electrode assembly 300, to which the first current collecting plate 30 is coupled, into the battery housing 20, even if the height of the electrode assembly 300 varies within a certain range.

[0122] Although one bent portion B is provided in the drawing, the present invention is not limited to this illustration, and it goes without saying that a plurality of bent portions B may be provided.

[0123] For example, it is preferable that the vertical distance (D) between the contact portion 33a and the support portion 31 when no external force is applied to the first current collecting plate 30 and no deformation is present be the same as the vertical distance between the upper surface of the beading portion 21 and the support portion 31 when the electrode assembly 300 to which the first current collecting plate 30 is coupled is placed in the battery housing 20, or be smaller within the extensible range of the connecting portion 33b. If the connecting portion 33b is configured to satisfy this condition, the contact portion 33a will naturally adhere to the beading portion 21 when the electrode assembly 300 to which the first current collecting plate 30 is coupled is placed in the battery housing 20.

[0124] Furthermore, the structure of the connecting part 33b, which can be contracted and expanded in this manner, can mitigate the impact caused by the movement of the electrode assembly 300 within a certain range, even if vibrations and / or impacts occur during use of the cylindrical battery 1 (see Figure 5) and the electrode assembly 300 moves up and down.

[0125] Meanwhile, when the connecting portion 33b has only one bent portion B, the bent portion B may protrude in a direction toward the winding center of the electrode assembly 300, unlike the illustration. The purpose of bending the connecting portion 33b in this manner is to prevent damage to the connection portion between the first current collector plate 30 and the electrode assembly 300 and / or the connection portion between the first current collector plate 30 and the battery housing 20 during a sizing process. The sizing process is a compression process in manufacturing a cylindrical battery 1, in which the height occupied by the beading portion 21 area of ​​the battery housing 20 is reduced to reduce the overall height of the cylindrical battery 1. The formation and protruding direction of the bent portion B were varied to confirm the extent of damage to the welded joint after the sizing process. It was found that a cylindrical battery 1 having a structure in which the connecting portion 33b is bent so that the bent portion B protrudes toward the center of the cylindrical battery 1 experienced almost no damage.

[0126] 9, a first current collecting plate 30 according to another embodiment of the present invention is shown. The first current collecting plate 30 according to this embodiment of the present invention differs from the first current collecting plate 30 of FIG. 8 described above only in the shape of the contact portion 33a, and otherwise the structure of the first current collecting plate 30 described above can be applied in substantially the same manner.

[0127] 9, the contact portion 33a may have a shape in which at least a portion thereof extends along the inner circumferential surface of the battery housing 20. For example, the contact portion 33a may have an arc shape extending along the beading portion 21. Although not shown, in order to maximize the contact area, the sum of the extension lengths of the contact portions 33a of the respective housing coupling portions 33 of the first current collecting plate 30 may be configured to be substantially the same as the inner circumferential surface of the battery housing 20. This maximizes the coupling area, thereby improving coupling strength and reducing electrical resistance.

[0128] 10, a first current collecting plate 30 according to yet another embodiment of the present invention is shown. The first current collecting plate 30 according to this embodiment of the present invention differs from the first current collecting plate 30 of FIG. 9 only in the shape of the connecting portion 33b, and otherwise the structure of the first current collecting plate 30 described above can be applied in substantially the same manner.

[0129] 10, the connecting portion 33b may have a shape in which at least a portion thereof extends along the inner circumferential surface of the battery housing 20. For example, the contact portion 33a may have an arc shape extending along the beading portion 21 of the battery housing, and the connecting portion 33b may have an arc shape extending along the contact portion 33a. With this structure, the area of ​​the first current collecting plate 30 is further increased compared to the first current collecting plate 30 shown in FIG. 9, thereby maximizing the effect of reducing electrical resistance.

[0130] 10, the first current collecting plate 30 may not have a bent portion B, unlike the first current collecting plate 30 shown in FIG. 8 or 9. If the bent portion B is not provided, it is possible to reduce raw materials required for manufacturing the first current collecting plate 30, thereby reducing the manufacturing cost of the first current collecting plate 30.

[0131] 5, the cap plate 40 covers the opening formed on one side of the battery housing 20. If the battery housing 20 according to the present embodiment includes a beading portion 21, the cap plate 40 may be placed on the beading portion 21 formed on the battery housing 20. If the battery housing 20 according to the present embodiment includes a crimping portion 22, the cap plate 40 may be fixed by the crimping portion 22. In this case, a sealing gasket G1 may be interposed between the battery housing 20 and the cap plate 40 to improve fixing strength and sealability of the battery housing 20. However, in the present embodiment, the cap plate 40 does not function as a current path. Therefore, the use of the sealing gasket G1 is not necessary as long as the battery housing 20 and the cap plate 40 can be firmly fixed together by welding or by using other parts to ensure sealability of the opening of the battery housing 20.

[0132] The cap plate 40 may be made of, for example, a metal material to ensure rigidity. In the 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 20 and the battery terminal 60 (described later). 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 300 and the battery housing 20, and its material does not necessarily need to be a conductive metal.

[0133] Meanwhile, in the case where the sealing gasket G1 is applied, the sealing gasket G1 may be substantially ring-shaped and surround the cap plate 40. The sealing gasket G1 may simultaneously cover the upper, lower, and side surfaces of the cap plate 40. The radial length of the portion of the sealing gasket G1 covering the lower surface of the cap plate 40 may be shorter or equal to the radial length of the portion of the sealing gasket G1 covering the upper surface of the cap plate 40. If the radial length of the portion of the sealing gasket G1 covering the lower surface of the cap plate 40 is too long, the sealing gasket G1 may press against the first current collecting plate 30 during the process of vertically compressing the battery housing 20, which may damage the first current collecting plate 30 or the battery housing 20. Therefore, it is necessary to maintain the radial length of the portion of the sealing gasket G1 covering the lower surface of the cap plate 40 at a small predetermined level. 5, the radial length of the portion of the sealing gasket G1 that covers the lower surface of the cap plate 40 may be smaller than the radial length of the portion of the sealing gasket G1 that covers the upper surface of the cap plate 40. Alternatively, as shown in FIGS. 6 and 7, the radial length of the portion of the sealing gasket G1 that covers the lower surface of the cap plate 40 may be the same as the radial length of the portion of the sealing gasket G1 that covers the upper surface of the cap plate 40.

[0134] Meanwhile, the contact portion 33a may be interposed and fixed between the beading portion 21 and the sealing gasket G1. That is, in a state where the contact portion 33a is interposed between the beading portion 21 and the sealing gasket G1, the contact portion 33a may be fixed by the crimping force of the crimping portion 22.

[0135] Alternatively, a weld may be formed between the beading portion 21 and the contact portion 33a. For example, the contact portion 33a may not be securely fixed by crimping alone. Furthermore, if the sealing gasket G1 shrinks due to heat or the crimping portion 22 is deformed due to external impact, the bonding strength between the current collecting plate and the battery housing 20 may be reduced. Therefore, with the contact portion 33a placed on the beading portion 21, the first current collecting plate 30 may be fixed to the battery housing 20 by welding. Then, a cap plate covered with the sealing gasket G1 is placed on the contact portion 33a, and the crimping portion 22 is formed, completing the cylindrical battery 1. Examples of welding methods that may be used include, but are not limited to, laser welding, resistance welding, and ultrasonic welding.

[0136] Meanwhile, the cap plate 40 may include a venting portion 41 formed to prevent an increase in internal pressure due to gas generated inside the battery housing 20. The venting portion 41 is formed in a portion of the cap plate 40 and corresponds to a region structurally weaker than the surrounding region so that it is easily broken when pressure is applied. The venting portion 41 may be a region thinner than the surrounding region. Therefore, if an abnormality occurs in the cylindrical battery 1 and the internal pressure of the battery housing 20 increases above a certain level, the venting portion 41 breaks, thereby discharging the gas generated inside the battery housing 20. The venting portion 41 may be formed by, for example, notching one or both surfaces of the cap plate 40 to partially reduce the thickness of the battery housing 20.

[0137] The battery terminal 60 is electrically connected to the second electrode tab 12. The battery terminal 60 may penetrate the battery housing 20 from the side opposite the opening of the battery housing 20 to be electrically connected to the second electrode tab 12 of the electrode assembly 300. The battery terminal 60 may penetrate approximately the center of the bottom surface of the battery housing 20. A portion of the battery terminal 60 may be exposed to the outside of the battery housing 20, and the remaining portion may be located inside the battery housing 20. The battery terminal 60 may be electrically connected to the electrode assembly 300 by being coupled to a second current collecting plate P coupled to the second electrode tab 12 (described below) or by being coupled to a lead tab (not shown) coupled to the second electrode tab 12. Therefore, the battery terminal 60 has the same polarity as the second electrode of the electrode assembly 300 and can function as a second electrode terminal T2. When the second electrode tab 12 is a positive electrode tab, the battery terminal 60 functions as a positive electrode terminal.

[0138] Considering the polarity and function of the battery terminal 60, the battery terminal 60 must maintain an insulated state from the battery housing 20, which has the opposite polarity. For this reason, an insulating gasket G2 may be applied between the battery terminal 60 and the battery housing 20. Alternatively, insulation may be achieved by coating a portion of the surface of the battery terminal 60 with an insulating material. Alternatively, the battery terminal 60 may be spaced apart from the battery housing 20 to prevent contact therebetween, and the battery terminal 60 may be structurally firmly fixed. Alternatively, a combination of the above-mentioned methods may be applied.

[0139] That is, the cylindrical battery 1 according to one embodiment of the present invention has a structure in which a pair of electrode terminals (battery terminal 60, first electrode terminal T1) 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 battery 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 20, which has a substantially flat shape, can be used as the first electrode terminal T1, thereby ensuring a sufficient bonding area when bonding an electrical connection component such as a bus bar to the first electrode terminal T1. As a result, the cylindrical battery 1 can ensure sufficient bonding strength between the electrical connection component and the first electrode terminal T1 and reduce resistance at the bonding site to a desirable level.

[0140] Meanwhile, when an insulating gasket G2 is applied for electrical insulation and riveting is applied to fix the battery terminal 60, the insulating gasket G2 may be deformed together with the battery terminal 60 when riveting the battery terminal 60, and bend toward the inner surface of the upper closure of the battery housing 20. When the insulating gasket G2 is made of a resin material, the insulating gasket G2 may be joined to the battery housing 20 and the battery terminal 60 by heat sealing. In this case, the airtightness at the joining interface between the insulating gasket G2 and the battery terminal 60 and at the joining interface between the insulating gasket G2 and the battery housing 20 is enhanced.

[0141] In one embodiment of the present invention, the entire surface of the battery housing 20 can function as the first electrode terminal T1. For example, if the first electrode tab 11 is a negative electrode tab, the first electrode terminal T1 can be the negative electrode terminal. The cylindrical battery 1 according to this embodiment of the present invention is structured such that the battery terminal 60 exposed on the bottom surface opposite the opening of the battery housing 20 is used as the second electrode terminal T2, and the remaining area of ​​the bottom surface of the battery housing 20, excluding the area occupied by the battery terminal 60, is used as the first electrode terminal T1. Therefore, when electrically connecting multiple cylindrical batteries 1, the cylindrical battery 1 according to this embodiment of the present invention can connect all positive and negative electrodes in one direction, simplifying the electrical connection structure. Furthermore, the cylindrical battery 1 according to this embodiment of the present invention has a structure in which most of the bottom surface opposite the opening of the battery housing 20 can be used as an electrode terminal, thereby providing an advantage of ensuring a sufficient area for welding components for electrical connection.

[0142] 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.

[0143] Here, form factor refers to a value indicating the diameter and height of a cylindrical battery. Cylindrical batteries according to an embodiment of the present invention may be, for example, a 46110 battery, a 48750 battery, a 48110 battery, a 48800 battery, or a 46800 battery. In the form factor number, the first two digits indicate the diameter of the battery, the next two digits indicate the height of the battery, and the final digit, 0, indicates that the cross section of the battery is circular.

[0144] 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.

[0145] 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.

[0146] 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 0.418.

[0147] 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.

[0148] 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.

[0149] Conventionally, batteries with a form factor ratio of approximately 0.4 or less have been used. For example, 18650 batteries and 21700 batteries have been used. 18650 batteries have a diameter of approximately 18 mm, a height of approximately 65 mm, and a form factor ratio of approximately 0.277. 21700 batteries have a diameter of approximately 21 mm, a height of approximately 70 mm, and a form factor ratio of approximately 0.300.

[0150] The cylindrical battery 1 described above will be described in more detail below with reference to Figures 11 to 19. In the following description, there may be other embodiments that can be selectively applied to the same components as those described above. Also, in the following description, some descriptions may overlap with those described above.

[0151] 12, 13, 16, and 17, the electrode assembly 300 includes a first electrode tab 11 and a second electrode tab 12. The first electrode tab 11 is provided at a lower portion in the height direction (Z-axis direction) of the electrode assembly 300 housed in the battery housing 20. The second electrode tab 12 is provided at an upper portion in the height direction (Z-axis direction) of the electrode assembly 300 housed in the battery housing 20.

[0152] 11, 12, 13, and 16, the battery housing 20 can accommodate the electrode assembly 300 through an opening formed at its lower end. The battery housing 20 is a generally cylindrical container having an opening formed at its lower end and a closed portion formed at its upper end.

[0153] 12 and 13, the battery housing 20 may include a beading portion 21 and a crimping portion 22 formed at its lower end. The beading portion 21 may be located below the electrode assembly 300 accommodated inside the battery housing 20. The beading portion 21 may be formed by pressing around the outer periphery of the battery housing 20. The beading portion 21 partially reduces the inner diameter of the battery housing 20, thereby preventing the electrode assembly 300, which has a size substantially corresponding to the width of the battery housing 20, from slipping out of an opening formed at the lower end of the battery housing 20, and may also function as a support on which the cap plate 40 is placed.

[0154] The crimping portion 22 is formed below the beading portion 21. The crimping portion 22 may be extended and bent to enclose the peripheral portion of the cap plate 40 with the peripheral portion of the sealing spacer 50 interposed therebetween.

[0155] 12, 13 and 15, the cap plate 40 may cover an opening formed in the battery housing 20. The cap plate 40 may form the lower surface of the cylindrical battery 1.

[0156] 13 and 15, the lower end of the cap plate 40 is preferably located higher than the lower end of the battery housing 20. In this case, even if the lower end of the battery housing 20 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 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.

[0157] On the other hand, when the venting portion 41 has a closed loop shape as shown in Figures 13 and 15, 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 15) from the peripheral region of the cap plate 40.

[0158] 15 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.

[0159] 12, 13, and 14, the sealing spacer 50 is configured to prevent movement of the electrode assembly 300 and strengthen the sealing force of the battery housing 20. The sealing 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 30 and the cap plate 40. The movement prevention portion 51 may have a height corresponding to the distance between the first current collecting plate 30 and the cap plate 40. In this case, the movement prevention portion 51 can effectively prevent the electrode assembly 300 from moving within the battery housing 20 due to a clearance formed between the first current collecting plate 30 and the cap plate 40. Therefore, the movement prevention portion 51 can prevent damage to the coupling portion between the electrode assembly 300 and the first current collecting plate 30 and / or the coupling portion between the first current collecting plate 30 and the battery housing 20.

[0160] The movement prevention portion 51 may be located approximately at the center of the lower surface of the electrode assembly 300. The movement prevention portion 51 may include a spacer hole H3 formed at a position corresponding to the winding center hole H1 of the electrode assembly 300. The spacer hole H3 may function as a passage for inserting a welding rod or a passage for laser irradiation, similar to the first current collecting plate hole H2 described above. The spacer hole H3 may also function as a passage for smoothly impregnating the inside of the electrode assembly 300 with electrolyte, similar to the first current collecting plate hole H2 described above.

[0161] The sealing portion 52 is interposed between the battery housing 20 and the cap plate 40. The sealing portion 52 may extend along the inner circumferential surface of the battery housing 20. If the battery housing 20 includes the crimping portion 22, the sealing portion 52 may be folded along the bent shape of the crimping portion 22 to enclose the peripheral region of the cap plate 40. As such, the sealing portion 52 may function as a gasket for improving the fixing strength of the cap plate 40 and the sealing strength of the battery housing 20. As such, if the cylindrical battery 1 according to an embodiment of the present invention includes the sealing spacer 50, the sealing portion 52 of the sealing spacer 50 may replace the sealing gasket G1 shown in FIGS. 5 to 7.

[0162] 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.

[0163] 13 and 14, the extension legs 53a may be configured not to contact the cap plate 40 and / or other portions of the housing coupling portion 33 of the first current collector plate 30 except for the portion inserted into the crimping portion 22. For example, the connecting portion 53 may be positioned so as not to overlap the housing coupling portion 33 along the height direction (Z-axis direction) of the cylindrical battery 1. In particular, if the extension legs 53a extend radially from the movement prevention portion 51 and the housing coupling portions 33 extend radially from the support portion 31, the extension legs 53a and the housing coupling portions 33 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 20 in the vertical direction, causing deformation of the components, interference between the extension legs 53a and the housing coupling portion 33 is significantly reduced, thereby significantly reducing the possibility of problems such as damage to the coupling portions between the components.

[0164] In this case, even if the sealing spacer 50 is deformed due to a sizing process that compresses the cylindrical battery 1 in the height direction (Z-axis direction) or other reasons, interference between the connection portion 53 of the sealing spacer 50 and the housing coupling portion 33 of the first current collecting plate 30 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 the extension leg 53a being deformed can be reduced even if deformation occurs in the battery housing 20 due to the sizing process or external impact.

[0165] Meanwhile, the components constituting the sealing spacer 50 may be integrally formed. For example, the sealing spacer 50 may be manufactured by injection molding, with the movement prevention portion 51, the sealing portion 52, and the connecting portion 53 integrated into one unit. 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 20 and movement prevention for the electrode assembly 300 through a single component by modifying and manufacturing a gasket component used to seal the opening of the battery housing 20. Therefore, according to an 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.

[0166] 12, 16, and 17, the second current collector plate P is coupled to the upper portion of the electrode assembly 300. The second current collector plate P is made of a conductive metal material and is coupled to the second electrode tab 12. The coupling between the second electrode tab 12 and the second current collector plate P may be performed, for example, by laser welding. Referring to FIG. 13, the second current collector plate P may be coupled to a coupling surface formed by bending an end of the second electrode tab 12 in a direction parallel to the second current collector plate P. The bending direction of the second electrode tab 12 may be, for example, toward the winding center of the electrode assembly 300. When the second electrode tab 12 has such a bent shape, the space occupied by the second electrode tab 12 is reduced, thereby improving energy density. Furthermore, the increased coupling area between the second electrode tab 12 and the second current collector plate P may improve coupling strength and reduce resistance. Meanwhile, the above-described coupling structure and coupling method between the second electrode tab 12 and the second current collector plate P can be similarly applied to the coupling between the first electrode tab 11 and the first current collector plate 30.

[0167] 12 and 16, the insulator S is interposed between a closing portion formed at the upper end of the battery housing 20 and the upper end of the electrode assembly 300, or between the closing portion and the second current collecting plate P. The insulator S may be made of, for example, an insulating resin material. The insulator S prevents contact between the electrode assembly 300 and the battery housing 20 and / or between the electrode assembly 300 and the second current collecting plate P. To this end, the insulator S may be interposed between the second electrode tab 12 and the battery housing 20 and / or between the second current collecting plate P and the battery housing 20. When the insulator S is used, the battery terminal 60 may penetrate the insulator S for electrical connection with the second electrode tab 12.

[0168] The insulator S may also be interposed between the upper end of the outer periphery of the electrode assembly 300 and the inner surface of the battery housing 20. In this case, it is possible to prevent the second electrode tab 12 of the electrode assembly 300 from coming into contact with the inner surface of the side wall of the battery housing 20, thereby preventing a short circuit from occurring.

[0169] The insulator S may have a height corresponding to the distance between a closing portion formed at the upper end of the battery housing 20 and the electrode assembly 300 or the distance between the closing portion and the second current collecting plate P. In this case, the electrode assembly 300 can be prevented from moving inside the battery housing 20, thereby significantly reducing the risk of damage to coupling portions for electrical connection between components. When the insulator S is used together with the above-mentioned sealing spacer 50, the effect of preventing movement of the electrode assembly 300 can be maximized.

[0170] The insulator S may have an opening formed at a position corresponding to the winding center hole H1 of the electrode assembly 300. The battery terminal 60 may be in direct contact with the second current collector plate P through the opening.

[0171] 18, a battery pack 3 according to an embodiment of the present invention includes the cylindrical battery 1 according to an embodiment of the present invention as described above. For convenience of illustration, components such as bus bars for electrical connections, a cooling unit, and power terminals are not shown.

[0172] 19, 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 and 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.

[0173] 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.

[0174] In the embodiments, the term "primary particles" refers to particle units that do 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.

[0175] "Secondary particles" are particles formed by agglomeration of multiple primary particles. In the present invention, secondary particles formed by agglomeration of 10 or less primary particles are referred to as pseudo-single particles to distinguish them from conventional secondary particles formed by agglomeration of tens to hundreds of primary particles.

[0176] 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.

[0177] In the present invention, "D min "," "D50 " 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.

[0178] 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.

[0179] 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.

[0180] 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.

[0181] 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.

[0182] 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.

[0183] 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.

[0184] 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.

[0185] 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.

[0186] 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.

[0187] 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.

[0188] 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.

[0189] 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.

[0190] 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.

[0191] 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.

[0192] 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.

[0193] 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.

[0194] 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.

[0195] 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.

[0196] 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.

[0197] 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.

[0198] [Formula 1] Particle size distribution (PSD)=(D max -D min ) / D 50 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.

[0199] 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.

[0200] 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.

[0201] 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.

[0202] More specifically, the positive electrode active material may include a lithium nickel-based oxide represented by the following Chemical Formula 1:

[0203] [Chemical formula 1] Li a Ni b Co c M 1 d M 2 e O2 In Chemical Formula 1, the M 1 may be Mn, Al or a combination thereof, preferably Mn, or Mn and Al.

[0204] 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.

[0205] 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.

[0206] 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.

[0207] The said c represents the molar ratio of cobalt in the total metal excluding lithium in the lithium nickel-based oxide, and can be 0 < c < 0.2, 0 < c < 0.18, 0.01 ≤ c ≤ 0.17, 0.01 ≤ c ≤ 0.15, 0.01 ≤ c ≤ 0.12, or 0.01 ≤ c ≤ 0.10. When the molar ratio of cobalt satisfies the above range, good resistance characteristics and output characteristics can be realized.

[0208] The said d represents the molar ratio of element M in the total metal excluding lithium in the lithium nickel-based oxide 1 and can be 0 < d < 0.2, 0 < d < 0.18, 0.01 ≤ d ≤ 0.17, 0.01 ≤ d ≤ 0.15, 0.01 ≤ d ≤ 0.1, or 0.01 ≤ d ≤ 0.10. When the molar ratio of element M satisfies the above range, the structural stability of the positive electrode active material is excellent. 1 The said e represents the molar ratio of element M in the total metal excluding lithium in the lithium nickel-based oxide

[0209] and can be 0 ≤ e ≤ 0.1 or 0 ≤ e ≤ 0.05. 2

[0210] [[ID=十七]] 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 needed. Preferably, the coating element can be Al, B, Co, or a combination thereof.

[0211] 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.

[0212] 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.

[0213] 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.

[0214] 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.

[0215] 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.

[0216] 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.

[0217] 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.

[0218] The conductive nano-materials may have various shapes, such as spherical, scale-like, or fibrous shapes.

[0219] 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.

[0220] 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.

[0221] 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.

[0222] 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.

[0223] 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).

[0224] 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.

[0225] 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.

[0226] 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.

[0227] 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.

[0228] 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.

[0229] 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.

[0230] 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.

[0231] 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.

[0232] In a specific embodiment according to an embodiment of the present invention, the conductive material may include carbon nanotubes.

[0233] 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.

[0234] 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."

[0235] Conventionally, commonly used carbon nanotubes (conventional CNTs) have a BET specific surface area of ​​300m 2The scanning electron microscope images and physical properties (FIG. 22) of the novel CNT used in the present invention (FIG. 20) and the conventional CNT (FIG. 21) are compared as follows:

[0236] 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.

[0237] 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.

[0238] 23 to 26 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.

[0239] 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.

[0240] 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.

[0241] 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%.

[0242] 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.

[0243] 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.

[0244] 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.

[0245] 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.

[0246] The table shown in Figure 27 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.

[0247] 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.

[0248] 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.

[0249] The electrode assembly may 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 may be wound to form a jelly roll type structure. When forming a jelly roll type structure, a separator may be further disposed on the outside to prevent contact between the negative electrode and the positive electrode.

[0250] The negative electrode includes a negative electrode current collector and a negative electrode active material layer formed on at least one surface of the negative electrode current collector. The negative electrode may 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 may include a negative electrode active material, a conductive material, and a binder.

[0251] <​​​​​​​​​​In one embodiment of the present invention, the negative electrode may contain a silicon-based negative electrode active material. The silicon-based negative electrode active material may be Si, Si-Me alloy (where Me is one or more selected from the group consisting of Al, Sn, Mg, Cu, Fe, Pb, Zn, Mn, Cr, Ti, and Ni), SiO y (where 0 < y < 2), Si-C composite, or a combination thereof, preferably SiO y (where 0 < y < 2). 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.

[0254] 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), 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.

[0255] Figure 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.

[0256] In Figure , low-efficiency SiO is undoped SiO, and ultra-high-efficiency SiO means Mg / Li-doped SiO. From Figure <JSON.stringify(0001020)>, 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.

[0257] 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.

[0258] 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%.

[0259] 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.

[0260] 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.

[0261] 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.

[0262] 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.

[0263] 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.

[0264] 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.

[0265] 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.

[0266] 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.

[0267] 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.

[0268] 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.

[0269] 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.

[0270] 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.

[0271] Specifically, the electrolyte may include an organic solvent and a lithium salt.

[0272] 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.

[0273] 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.

[0274] 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.

[0275] 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.

[0276] 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.

[0277] FIG. 32 is a view showing an electrode assembly according to an embodiment of the present invention, and FIG. 33 is a cross-sectional view taken along line AA' in FIG.

[0278] 32 and 33, 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.

[0279] 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.

[0280] 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.

[0281] Here, the first direction d1 and the second direction d2 are opposite directions, and may be parallel to the height direction of the jelly roll structure 300S.

[0282] The electrode assembly 300 according to this embodiment does not have a separate electrode tab attached, but rather 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.

[0283] 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.

[0284] 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.

[0285] 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.

[0286] 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.

[0287] 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.

[0288] 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.

[0289] 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.

[0290] 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.

[0291] 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.

[0292] 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.

[0293] 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.

[0294] 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.

[0295] 34 and 35 are views illustrating a process for manufacturing a negative electrode according to one embodiment of the present invention. Specifically, FIG. 34 is a top view of a negative electrode sheet, and FIG. 35 is a front view of the negative electrode sheet of FIG.

[0296] 34 and 35, 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.

[0297] 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.

[0298] 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.

[0299] 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 36 is a perspective view showing a negative electrode according to an embodiment of the present invention.

[0300] 34 to 36, as shown by dotted lines in FIGS. 34 and 35, 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. 36, to be manufactured from the negative electrode sheet 400S. That is, the negative electrode 400 in FIG. 36 corresponds to one of a plurality of negative electrodes manufactured by slitting the negative electrode sheet 400S in FIGS. 34 and 35. 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.

[0301] 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.

[0302] 37 and 38 are diagrams illustrating a process for manufacturing a positive electrode according to one embodiment of the present invention. Specifically, Fig. 37 is a top view of a positive electrode sheet, and Fig. 38 is a front view of the positive electrode sheet of Fig. 37.

[0303] 37 and 38, 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.

[0304] 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.

[0305] 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.

[0306] 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 39 is a perspective view showing a positive electrode 500 according to one embodiment of the present invention.

[0307] 37 to 39, as shown by the dotted lines in FIGS. 37 and 38, 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. 39, to be manufactured from the positive electrode sheet 500S. That is, the positive electrode 500 in FIG. 39 corresponds to one of a plurality of positive electrodes manufactured by slitting the positive electrode sheet 500S in FIGS. 37 and 38. 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.

[0308] 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.

[0309] 32, 36, and 39, 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.

[0310] 37 to 39, 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.

[0311] In the step of manufacturing the positive electrode 500, a loading reduction region 500DA is slit from the positive electrode active material portion 520. The slit loading reduction region 500DA forms a loading reduction portion 500D in the jelly roll structure 300S shown in FIGS. 32 and 33, in which the loading amount of the positive electrode active material is less than that of the adjacent region.

[0312] 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. 38, 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.

[0313] 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.

[0314] Referring to FIG. 39, 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.

[0315] 32 and 33, 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.

[0316] 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.

[0317] 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.

[0318] 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.

[0319] Hereinafter, an electrode assembly according to a comparative example of the present invention will be described with reference to FIGS. 40 to 43, and advantages of the electrode assembly according to the embodiment of the present invention compared to the comparative example will be described.

[0320] FIG. 40 shows an electrode assembly according to a comparative example of the present invention, and FIG. 41 is a cross-sectional view taken along line BB' in FIG.

[0321] 40 and 41, 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.

[0322] 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.

[0323] FIG. 42 is a diagram showing a process for manufacturing a negative electrode 700 according to a comparative embodiment of the present invention.

[0324] Referring to FIG. 42, after a negative electrode sheet 700S is manufactured such that the negative electrode active material parts 720 and the negative electrode uncoated parts 730 are alternately positioned along 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.

[0325] 40 and 41 , 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.

[0326] FIG. 43 is a diagram showing the steps of manufacturing a positive electrode 800 according to a comparative embodiment of the present invention.

[0327] Referring to FIG. 43, 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.

[0328] 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.

[0329] 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. 33).

[0330] 40 and 41, 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.

[0331] 32 and 33, 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 the adjacent region, 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.

[0332] Comparing the A1 region in Figures 32 and 33 with the B1 region in Figures 40 and 41, 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.

[0333] 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.

[0334] 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.

[0335] 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.

[0336] 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.

[0337] 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.

[0338] 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.

[0339] 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.

[0340] 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.

[0341] 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.

[0342] 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.

[0343] The present invention will be described in more detail below with reference to specific examples.

[0344] 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.

[0345] 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.

[0346] 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.

[0347] <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.

[0348] <Experimental Example 1> A hot box test was carried out on the 4680 cells manufactured according to Example 1 and Comparative Example 1.

[0349] 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 29a and 29b.

[0350] 29a is a graph showing the results of a hot box test for the 4680 cell manufactured according to Example 1, and FIG. 29b 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.

[0351] 29a and 29b 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.

[0352] <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 28a shows an SEM photograph of the positive electrode active material used in Example 2-1.

[0353] 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.

[0354] 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.

[0355] 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.

[0356] <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 ]O2) was used. A 4680 cell was fabricated in the same manner as in Example 2-1. Figure 28b shows an SEM image of the positive electrode active material used in Example 2-2.

[0357] <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.

[0358] <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.

[0359] FIG. 28c shows an SEM photograph of the positive electrode active material used in Comparative Example 2-2.

[0360] <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.

[0361] 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.

[0362] The measurement results are shown in Table 1 below and Figures 29c and 29d. Figure 29c is a graph showing the results of the hot box test for the 4680 cells fabricated according to Sample 1 of Example 2-1 and Comparative Example 2-1, and Figure 29d is a graph showing the results of the hot box test for the 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.

[0363] [Table 1]

[0364] Referring to Table 1, Figures 29c and 29d, 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.

[0365] <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 30a shows an SEM cross-sectional image of the positive electrode prepared in Example 2-1, and Figure 30b shows an SEM cross-sectional image of the positive electrode prepared in Comparative Example 2-1.

[0366] 30a and 30b, the positive electrode of Example 2-1 had almost no particle cracks in the positive electrode active material even after rolling, whereas the positive electrode of Comparative Example 2-2, which used secondary particles, had many particle cracks in the positive electrode active material after rolling.

[0367] <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%.

[0368] <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%.

[0369] <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%.

[0370] <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%.

[0371] <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%.

[0372] <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%.

[0373] <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.

[0374] [Table 2]

[0375] 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.

[0376] <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.

[0377] 31a, 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.

[0378] <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.

[0379] 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.

[0380] The 4680 cell thus fabricated was subjected to 50 charge-discharge cycles, where one cycle was charging at 0.5 C to 4.2 V and discharging at 0.5 C to 2.5 V at 40°C, and then the capacity retention and the rate of increase in resistance (DCIR) were measured. The measurement results are shown in Figure 31b.

[0381] Referring to FIG. 31b, it can be seen that the secondary batteries of Examples 3-1 and 3-3 have smaller changes in capacity retention rate according to the number of cycles and smaller changes in resistance increase rate according to the number of cycles than the secondary battery of Comparative Example 3-1.

[0382] 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]

[0383] 1 cylindrical battery 11 First electrode tab 12 Second electrode tab 20 Battery Housing 21 Beading section 22 Crimping section 30 First current collector plate 31 Support part 32 Tab joint 33 Housing joint 33a Contact part 33b Connection part 40 Cap Plate 41 Venting section 50 Sealing Spacer 51 Anti-movement part 52 Sealing part 53 Connecting part 53a extension leg 60 Battery terminal 300 electrode assembly 400 negative electrode 410 Negative electrode current collector 420 Negative electrode active material section 430 Negative electrode uncoated area 430 Plain section 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 including a first electrode tab and a second electrode tab; a battery housing that accommodates the electrode assembly through an opening formed on one side thereof; a first current collecting plate positioned within the battery housing, the first current collecting plate including: a support portion disposed on one surface of the electrode assembly; at least one tab connecting portion extending from the support portion and connected to the first electrode tab; and at least one housing connecting portion extending from an end of the tab connecting portion and electrically connected to an inner surface of the battery housing; a cap plate for covering the opening; a battery terminal electrically connected to the second electrode tab; a sealing spacer configured to prevent movement of the electrode assembly and strengthen the sealing force of the battery housing; The cylindrical battery, wherein the sealing spacer includes a sealing portion interposed between the battery housing and the cap plate.

2. the battery housing includes a beading portion formed on a peripheral edge portion adjacent to the opening and pressed inward, The cylindrical battery according to claim 1 , wherein the housing joint portion is joined onto the beading portion.

3. the battery housing includes a beading portion formed on a peripheral edge portion adjacent to the opening and pressed inward, The housing coupling portion is a contact portion bonded onto the beading portion; The cylindrical battery according to claim 1 , further comprising: a connecting portion connecting between the tab connecting portion and the contact portion.

4. The cylindrical battery according to claim 3 , further comprising a sealing gasket provided between the battery housing and the cap plate.

5. The cylindrical battery according to claim 4 , wherein the contact portion is interposed and fixed between the beading portion and the sealing gasket.

6. The cylindrical battery according to claim 3 , wherein a weld is formed between the beading portion and the contact portion of the first current collector plate.

7. the battery housing includes a beading portion formed on a peripheral edge portion adjacent to the opening and pressed inward, The cylindrical battery according to claim 1 , wherein a boundary region between the tab joint portion and the housing joint portion is located inside an innermost portion of the beading portion.

8. The cylindrical battery according to claim 1 , wherein the cylindrical battery includes a plurality of the tab joints and a plurality of the housing joints.

9. The cylindrical battery according to claim 3 , wherein the connecting portion has at least one bent portion where an extending direction is changed.

10. The cylindrical battery according to claim 3 , wherein the contact portion has an arc shape extending along the beading portion.

11. The cylindrical battery according to claim 10 , wherein the connecting portion has an arc shape extending along the contact portion.

12. The sealing spacer is a movement prevention portion interposed between the first current collecting plate and the cap plate; The cylindrical battery according to any one of claims 1 to 11, further comprising: a connecting portion that connects the movement prevention portion and the sealing portion.

13. The cylindrical battery according to claim 12 , wherein the movement prevention portion has a height corresponding to the distance between the first current collector plate and the cap plate.

14. An electrode assembly having a first electrode tab and a second electrode tab; a battery housing that accommodates the electrode assembly through an opening formed on one side thereof; a first current collecting plate positioned within the battery housing, the first current collecting plate including: a support portion disposed on one surface of the electrode assembly; at least one tab connecting portion extending from the support portion and connected to the first electrode tab; and at least one housing connecting portion extending from an end of the tab connecting portion and connected to an inner surface of the battery housing; a cap plate for covering the opening; a battery terminal electrically connected to the second electrode tab; a sealing spacer configured to prevent movement of the electrode assembly and strengthen the sealing force of the battery housing; The sealing 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, A cylindrical battery, wherein the movement prevention portion is located at the center on one surface of the electrode assembly.

15. An electrode assembly having a first electrode tab and a second electrode tab; a battery housing that accommodates the electrode assembly through an opening formed on one side thereof; a first current collecting plate positioned within the battery housing, the first current collecting plate including: a support portion disposed on one surface of the electrode assembly; at least one tab connecting portion extending from the support portion and connected to the first electrode tab; and at least one housing connecting portion extending from an end of the tab connecting portion and connected to an inner surface of the battery housing; a cap plate for covering the opening; a battery terminal electrically connected to the second electrode tab; a sealing spacer configured to prevent movement of the electrode assembly and strengthen the sealing force of the battery housing; The sealing 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, The movement prevention portion includes a spacer hole formed at a position corresponding to a winding center hole of the electrode assembly.

16. The cylindrical battery according to claim 1 , wherein the sealing portion extends along the inner circumferential surface of the battery housing.

17. An electrode assembly having a first electrode tab and a second electrode tab; a battery housing that accommodates the electrode assembly through an opening formed on one side thereof; a first current collecting plate positioned within the battery housing, the first current collecting plate including: a support portion disposed on one surface of the electrode assembly; at least one tab connecting portion extending from the support portion and connected to the first electrode tab; and at least one housing connecting portion extending from an end of the tab connecting portion and connected to an inner surface of the battery housing; a cap plate for covering the opening; a battery terminal electrically connected to the second electrode tab; a sealing spacer configured to prevent movement of the electrode assembly and strengthen the sealing force of the battery housing; The sealing 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; a connecting portion connecting the movement prevention portion and the sealing portion, A cylindrical battery, wherein the connecting portion includes a plurality of extension legs extending radially from the motion prevention portion.

18. 18. The cylindrical battery according to claim 17, wherein the plurality of extension legs are configured not to contact the first current collector plate.

19. 18. The cylindrical battery of claim 17, wherein the plurality of extension legs are configured not to contact the cap plate.

20. The cylindrical battery according to claim 12 , wherein the connecting portion is positioned so as not to overlap the housing connecting portion along a height direction of the cylindrical battery.

21. The cylindrical battery comprises: a second current collecting plate coupled to the second electrode tab; The cylindrical battery according to claim 1 , further comprising: an insulator interposed between a closing portion formed at an upper end of the battery housing and the second current collector plate.

22. 22. The cylindrical battery of claim 21, wherein the insulator has a height corresponding to the distance between the second current collector and the closure.

23. An electrode assembly having a first electrode tab and a second electrode tab; a battery housing that accommodates the electrode assembly through an opening formed on one side thereof; a first current collecting plate positioned within the battery housing, the first current collecting plate including: a support portion disposed on one surface of the electrode assembly; at least one tab connecting portion extending from the support portion and connected to the first electrode tab; and at least one housing connecting portion extending from an end of the tab connecting portion and connected to an inner surface of the battery housing; a cap plate for covering the opening; a battery terminal electrically connected to the second electrode tab; a sealing spacer configured to prevent movement of the electrode assembly and strengthen the sealing force of the battery housing; the sealing spacer includes a sealing portion interposed between the battery housing and the cap plate; the active material layer of the second electrode includes a positive electrode active material including single particles, pseudo-single particles, 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 A cylindrical battery having a thickness of 12 μm to 17 μm.

24. 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 24. The cylindrical battery of claim 23, wherein the particle size distribution (PSD) expressed as:

25. 24. The cylindrical battery of claim 23, wherein 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 second electrode.

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

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

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

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

80.

30. A battery pack comprising the cylindrical battery according to any one of claims 1 to 11.

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

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