Cylindrical batteries, battery packs containing them, and automobiles

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 and is connected to a first electrode tab, a first current collecting plate including a support portion disposed on the electrode assembly, at least one first tab connecting portion extending from the support portion, and at least one housing connecting portion extending from an end of the first tab connecting portion, a second current collecting plate including a peripheral portion disposed on the electrode assembly, a second tab connecting portion extending inward from the peripheral portion, and a terminal connecting portion spaced apart from the second tab connecting portion, a cap plate configured to seal the opening, and a battery terminal connected to the terminal connecting portion.

Description

[Technical Field]

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

[0002] More specifically, one embodiment of the present invention relates to a cylindrical battery having a structure that prevents force from concentrating at the welded joints between components even when subjected to external shocks or vibrations during the battery's use, a battery pack including the same, and an automobile.

[0003] Furthermore, one embodiment of the present invention relates to a positive electrode for an electrochemical element with improved electrochemical properties and an electrode assembly including the positive electrode.

[0004] This application claims priority based on Korean Patent Application No. 10-2021-0142187, filed on 22 October 2021, and all content disclosed in the specification and drawings of said application is incorporated herein. [Background technology]

[0005] Rechargeable batteries, which offer high applicability across different product groups and possess electrical characteristics such as high energy density, are commonly used not only in portable devices but also in electric vehicles (EVs) and hybrid electric vehicles (HEVs) powered by electric drive sources.

[0006] Such secondary batteries are attracting attention not only for their primary benefit of dramatically reducing the use of fossil fuels, but also because they are environmentally friendly in that they produce no by-products from energy use, making them a promising new energy source for improving energy efficiency.

[0007] Currently, rechargeable 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 a single rechargeable battery cell is approximately 2.5V to 4.5V. Therefore, when a higher output voltage is required, multiple batteries are connected in series to form a battery pack. Alternatively, multiple batteries may be connected in parallel to form a battery pack, depending on the required charge and discharge capacity. Thus, the number of batteries included in a battery pack and the electrical connection configuration can be set in various ways depending on the required output voltage and / or charge and discharge capacity.

[0008] On the other hand, known types of secondary battery cells include cylindrical, prismatic, and pouch-type batteries. In the case of a cylindrical battery, an insulating separator membrane is interposed between the positive and negative electrodes, and this is wound up to form a jelly-roll type electrode assembly, which is then inserted into the battery housing along with the electrolyte to constitute the battery. In addition, strip-shaped electrode tabs are connected to the plain parts of the positive and negative electrodes, and these electrode tabs electrically connect the electrode assembly to the electrode terminals exposed on the outside. For reference, the positive electrode terminal is the cap plate of the sealing body that seals the opening of the battery housing, and the negative electrode terminal is the battery housing.

[0009] However, conventional cylindrical batteries with this structure have the problem that current is concentrated on the strip-shaped electrode tabs connected to the blank positive electrode portion and / or the blank negative electrode portion, resulting in high resistance, excessive heat generation, and poor current collection efficiency.

[0010] In small cylindrical batteries with form factors like 18650 or 21700, resistance and heat generation are not much of a problem. However, when increasing the form factor of cylindrical batteries for use in electric vehicles, a problem can arise where the cylindrical battery catches fire during the rapid charging process due to the large amount of heat generated around the electrode tabs.

[0011] To solve these problems, a cylindrical battery (a so-called tab-less cylindrical battery) has been proposed in which a blank positive electrode section and a blank negative electrode section are located at the upper and lower ends of a jelly roll-type electrode assembly, respectively, and current collection plates are welded to these blank sections to improve current collection efficiency.

[0012] Refer to Figures 1 to 4 for a more detailed explanation of conventional cylindrical batteries.

[0013] Figures 1 to 3 illustrate the manufacturing process of a tablet cylindrical battery. Figure 1 shows the electrode structure, Figure 2 shows the electrode winding process, and Figure 3 shows the process of welding the current collector plate to the curved surface of the blank section. Figure 4 is a cross-sectional view of the tablet cylindrical battery cut along its longitudinal direction (Y-axis).

[0014] Referring to Figures 1 to 4, the positive electrode 500 has a structure on a positive electrode sheet 500S that includes a positive electrode active material portion 520 and a positive electrode blank portion 530 provided on one long side along the winding direction. The negative electrode 400 also has a structure on a negative electrode sheet 400S that includes a negative electrode active material portion 420 and a negative electrode blank portion 430 provided on one long side along the winding direction. The electrode assembly 300 is manufactured by sequentially stacking the positive electrode 500 and the negative electrode 400 together with two separation membranes 600 as shown in Figure 2, and then winding them in one direction (X-axis direction). At this time, the blank portion 530 of the positive electrode 500 and the blank portion 430 of the negative electrode 400 are arranged in opposite directions.

[0015] After the winding process, the plain portion 530 of the positive electrode 500 and the plain portion 430 of the negative electrode 400 are bent toward the core. Then, the current collector plates 50 and 30 are welded to the plain portions 530 and 430, respectively, to join them.

[0016] The blank positive electrode section 530 and the blank negative electrode section 430 do not have separate electrode tabs attached, and the current collector plates 50 and 30 are connected to external electrode terminals. As a result, the current path is formed with a large cross-sectional area along the winding axis direction of the electrode assembly 300 (see arrow), which has the advantage of reducing the battery's resistance. This is because resistance is inversely proportional to the cross-sectional area of ​​the path through which the current flows.

[0017] However, as the form factor of cylindrical batteries increases and the charging current during rapid charging increases, the heat generation problem reappears even in tablet-type cylindrical batteries.

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

[0019] Typically, the positive terminal is the cap plate 40 of the sealed body A, and the negative terminal is the battery housing 20. Therefore, the second current collector plate 50, which is coupled to the blank portion 530 of the positive electrode 500, is electrically connected to the connecting plate C1 attached to the cap plate 40 via a strip-shaped lead L. Also, the first current collector plate 30, which is coupled to the blank portion 430 of the negative electrode 400, is electrically connected to the bottom of the battery housing 20. The insulator S covers the second current collector plate 50 to prevent a short circuit from occurring due to contact between the battery housing 20 and the blank portion 530 of the positive electrode 500, which have different polarities.

[0020] When the second current collector plate 50 is connected to the connecting plate C1, a strip-shaped lead L is used. The lead L is either attached separately to the second current collector plate 50 or manufactured integrally with the second current collector plate 50. 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 rapid charging current flows through it. Furthermore, the excessive heat generated in the lead L is transferred to the electrode assembly 300, causing the separator membrane 600 to contract, which can lead to an internal short circuit, a major cause of thermal runaway.

[0021] The lead L also occupies a considerable amount of installation space within the battery housing 20. Therefore, the cylindrical battery 1 containing the lead L has low space efficiency and limitations in increasing energy density.

[0022] Furthermore, connecting conventional 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 surface of the battery housing 20, which reduces space efficiency. Battery packs installed in electric vehicles contain hundreds of cylindrical batteries 1. Therefore, the inefficiency of electrical wiring causes considerable inconvenience during the assembly process of electric vehicles and during maintenance of the battery pack. Accordingly, there is a need to develop a cylindrical battery with a structure in which the positive and negative terminals are applied in the same direction, so as to simplify the electrical connection structure of multiple cylindrical batteries.

[0023] On the other hand, conventional cylindrical batteries generally have a structure in which tabs connecting the electrode assembly and external terminals are welded to the foil of the electrode assembly. However, in cylindrical batteries with such a structure, the current path is limited, and an excessive increase in the resistance of the electrode assembly itself is unavoidable.

[0024] Therefore, attempts were made to reduce resistance by increasing the number of tabs connecting the electrode assembly and the external terminals. However, simply increasing the number of tabs in this way has limitations in reducing resistance to the desired level and ensuring a sufficient current path.

[0025] Therefore, in order to reduce the resistance of the electrode assembly itself, it is necessary to develop new electrode assembly structures and current collector plate structures suitable for such electrode assembly structures. In particular, the need for such new electrode assemblies and current collector plates is even greater when applied to devices that require high-power / high-capacity battery packs, such as electric vehicles.

[0026] Furthermore, it is necessary to develop a cylindrical battery having a structure that maintains an improved coupling force between the current collector plate and the battery housing, as well as a structure for the current collector plate applied to said cylindrical battery.

[0027] Furthermore, when the current collector plate and the battery housing are coupled, there is a need for a cylindrical battery that improves the energy density of the cylindrical battery by minimizing the dead space within the battery housing.

[0028] On the other hand, the application areas of batteries are extremely diverse. In particular, battery packs used in devices such as electric vehicles require high capacity and high output. Furthermore, such high-capacity and high-output battery packs may include, for example, cylindrical batteries as unit cells.

[0029] In the case of cylindrical batteries with high capacity and high output characteristics, electrode tabs may be provided across the entire surface of both sides of the jelly roll to improve current collection efficiency, and current collector plates may be bonded to each side of the jelly roll. By applying such a structure, the contact area between the electrode tabs and the current collector plates can be maximized, thereby minimizing the resistance generated at the connection points between components.

[0030] As mentioned above, when cylindrical batteries are applied to devices such as automobiles, they are frequently subjected to external shocks and vibrations during use, which can damage the coupling points for electrical connections between components. Such damage to coupling points can lead to product defects.

[0031] Furthermore, even if damage to the coupling points for electrical connection does not result in a complete disruption of the electrical connection, damage to some welded areas can reduce the bonding area between parts, potentially leading to excessive heat due to increased resistance or internal short circuits due to deformation of the parts.

[0032] Therefore, there is a need to develop a cylindrical battery with a structure that prevents force from concentrating at the joints between components even when subjected to external shocks and / or vibrations during use.

[0033] On the other hand, when electrodes are manufactured using conventional positive electrode active materials containing secondary particles, particle cracking may occur, and internal cracks generated during charging and discharging may increase gas generation, potentially leading to battery stability problems.

[0034] To address this, positive electrode active materials in the form of single particles or pseudo-single particles with relatively large primary particle sizes have been developed. However, when these single-particle or pseudo-single-particle positive electrode active materials are applied to high-loading electrodes and rolled, the electrodes crack before the porosity reaches the target level, resulting in poor resistance characteristics and charge / discharge efficiency of the lithium secondary battery. [Overview of the project] [Problems that the invention aims to solve]

[0035] The present invention has been made in view of the above-mentioned problems, and one objective is 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.

[0036] Another objective of the present invention is to provide a current collector plate having a structure that can improve the bonding force at the connection point between the current collector plate and the battery housing, and a cylindrical battery including the same.

[0037] Furthermore, another objective of the present invention is to provide a current collector plate having a structure that can improve the energy density of a cylindrical battery, and a cylindrical battery including the same.

[0038] Furthermore, the present invention aims to provide a current collector plate having a structure that enhances the convenience of the welding process for electrical connection between the battery housing and the current collector plate in the manufacture of a cylindrical battery, thereby improving productivity, and a cylindrical battery including the same.

[0039] Furthermore, one objective is to prevent damage to the joints between components by distributing external shocks and / or vibrations rather than concentrating them on specific parts, even if the battery is subjected to such shocks and / or vibrations during use.

[0040] On the other hand, another objective of the present invention is to ensure safety in battery use by having the current collection plate itself perform the current interruption function without the need to provide an additional current interruption member, thereby quickly interrupting the current when an overcurrent occurs due to a short circuit or the like.

[0041] Furthermore, another objective of the present invention is to provide an electrode and an electrode assembly containing the same, which can achieve excellent thermal stability by applying single particles or pseudo-single particles as the positive electrode active material, and which has high electrical conductivity and high rolling properties.

[0042] Furthermore, another objective of the present invention is to provide an electrode assembly with improved energy density by applying a silicon-based negative electrode active material to the negative electrode.

[0043] Furthermore, another objective of the present invention is to provide an electrode assembly in which the positive electrode active material portion has been increased without the concern of lithium deposition.

[0044] Furthermore, another objective of the present invention is to provide a cylindrical battery that can exhibit excellent thermal stability even when the battery volume increases due to an increase in form factor.

[0045] Finally, another objective of the present invention is to provide a cylindrical lithium secondary battery that can exhibit excellent thermal stability even when its volume is increased.

[0046] The technical problems that this invention aims to solve are not limited to those described above, 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]

[0047] To solve the above-mentioned problems, a cylindrical battery according to one aspect of the present invention includes: an electrode assembly having a first electrode tab and a second electrode tab; a battery housing that houses the electrode assembly through an opening formed on one side and is electrically connected to the first electrode tab; a first current collector plate including a support portion disposed on one side of the electrode assembly, at least one first tab coupling portion extending from the support portion and coupled to the first electrode tab, and at least one housing coupling portion extending from the end of the first tab coupling portion and coupled to the inner surface of the battery housing; a second current collector plate having a peripheral portion disposed on the other side opposite to the one side of the electrode assembly, a second tab coupling portion extending inward from the peripheral portion and coupled to the second electrode tab, and a terminal coupling portion located apart from the second tab coupling portion; a cap plate configured to seal the opening of the battery housing; and a battery terminal that is electrically connected to the second electrode tab by coupling with the terminal coupling portion.

[0048] The battery housing may include a beading portion formed on the peripheral edge adjacent to the opening and pushed inward.

[0049] The housing coupling portion may be coupled onto the beading portion of the battery housing.

[0050] The housing coupling portion may include a contact portion coupled onto the beading portion of the battery housing, and a first coupling portion connecting the first tab coupling portion and the contact portion.

[0051] The cylindrical battery may include a sealing gasket provided between the battery housing and the cap plate.

[0052] The contact portion can be interposed and fixed between the beading portion of the battery housing and the sealing gasket.

[0053] A welded portion may be formed between the beading portion of the battery housing and the contact portion of the first current collector plate.

[0054] The first tab coupling portion may be positioned inside the region whose periphery is the circumference of the electrode assembly.

[0055] The cylindrical battery may be provided with a plurality of the first tab coupling portion and the housing coupling portion.

[0056] The first connecting portion may include at least one bent portion whose direction of extension is reversed.

[0057] The contact portion may have an arc shape that extends along the beading portion of the battery housing.

[0058] The first connecting portion may have an arc shape extending along the contact portion.

[0059] The aforementioned peripheral portion may have a rim shape with a hollow center.

[0060] The second tab coupling portion and the terminal coupling portion can be electrically connected by the peripheral portion.

[0061] The terminal coupling portion may be located in the center of the inner space of the peripheral portion.

[0062] The second current collector plate may further include a second connecting portion that extends inward from the peripheral edge and is connected to the terminal coupling portion.

[0063] The second connecting portion may be formed with a narrower width than the second tab connecting portion, at least in part.

[0064] The second connecting portion may include a tapered portion whose width gradually narrows from the inner surface of the peripheral edge toward the terminal connecting portion.

[0065] Multiple of the second tab connectors may be provided.

[0066] Multiple of the second tab joints can be arranged at equal intervals from one another along the extending direction of the peripheral portion.

[0067] The extended lengths of each of the multiple second tab joints can be formed to be the same.

[0068] The terminal coupling portion may be arranged so as to be surrounded by a plurality of the second tab coupling portions.

[0069] The second connecting portion is located between a pair of adjacent second tab connecting portions, and the distance from the second connecting portion to one of the pair of second tab connecting portions along the extending direction of the peripheral portion may be the same as the distance from the second connecting portion to the other of the pair of second tab connecting portions along the extending direction of the peripheral portion.

[0070] Multiple of the aforementioned second connecting parts may be provided.

[0071] Each of the multiple second connecting sections may be positioned between a pair of adjacent second tab connecting sections.

[0072] Multiple of the second connecting portions may be arranged at equal intervals from one another along the extending direction of the peripheral portion.

[0073] The second connecting portion may include a notch formed by narrowing the width of the second connecting portion.

[0074] The second connecting portion includes a notch formed by narrowing the width of the second connecting portion, and the notch may be located even closer to the tapered portion than the terminal connecting portion.

[0075] The terminal coupling portion may be positioned in a location corresponding to a hole formed in the winding center of the electrode assembly.

[0076] The second electrode tab may extend toward a closed portion located opposite the open portion of the battery housing.

[0077] The second tab coupling portion can be coupled onto a coupling surface formed by bending the end of the second electrode tab in a direction parallel to the second current collector plate.

[0078] The cap plate may be configured not to be connected to the electrode assembly and to be non-polar.

[0079] The battery terminals can pass through the closed portion located on the opposite side of the open portion of the battery housing.

[0080] The cylindrical battery may further include an insulator interposed between the closing portion and the second current collector plate.

[0081] The battery terminal can pass through the insulator and be connected to the terminal coupling portion of the second current collector plate.

[0082] On the other hand, a second current collector plate according to one embodiment of the present invention is interposed between the battery housing closure portion and the electrode assembly of a cylindrical battery and coupled to one surface of the electrode assembly. The second current collector plate includes a peripheral portion, a second tab coupling portion extending inward from the peripheral portion and coupled to a second polarity electrode tab provided on the electrode assembly, and a terminal coupling portion located spaced apart from the second tab coupling portion.

[0083] The active material layer of the second electrode comprises a positive electrode active material containing single particles, pseudo-single particles, or a combination thereof, wherein the minimum particle size D appearing in the volume cumulative distribution of the positive electrode active material is min The particle size D is 1.0 μm or larger, and the volume cumulative amount in the volume cumulative distribution of the positive electrode active material is 50%.50 The size is 5.0 μm or less, and the maximum particle size D that appears in the volume cumulative distribution of the positive electrode active material is 5.0 μm or less. max This can range from 12 μm to 17 μm.

[0084] The positive electrode active material has a unimodal particle size distribution in which a single peak appears in the volume cumulative particle size distribution graph, and the particle size distribution (PSD) represented by the following formula 1 may be 3 or less.

[0085] [Formula 1] Particle size distribution (PSD)=(D max -D min ) / D 50

[0086] The single particles, pseudo-single particles, or combinations thereof may be present in an amount of 95 wt% to 100 wt% based on the total weight of the positive electrode active material contained in the active material layer of the second electrode.

[0087] 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 the transition metal.

[0088] The active material layer of the second electrode has a porosity of 15% to 23%, and may contain flaky graphite in a weight ratio of 0.05 wt% to 5 wt%.

[0089] The active material layer of the second electrode may further contain carbon nanotubes (CNTs).

[0090] The active material layer of the first electrode comprises a silicon-based anode active material and a carbon-based anode active material, and the silicon-based anode active material and the carbon-based anode active material may be present in a weight ratio of 1:99 to 20:80.

[0091] A battery pack according to another aspect of the present invention includes a cylindrical battery according to the above-described aspect of the present invention.

[0092] An automobile according to yet another aspect of the present invention includes a battery pack according to the above-described aspect of the present invention. [Effects of the Invention]

[0093] 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.

[0094] Furthermore, according to one aspect of the present invention, the bonding force at the connection point between the current collector plate and the battery housing can be improved.

[0095] Furthermore, according to one aspect of the present invention, the energy density of a cylindrical battery can be improved.

[0096] Furthermore, according to one aspect of the present invention, in the manufacture of a cylindrical battery, the convenience of the welding process for electrical connection between the battery housing and the current collector plate can be improved, thereby increasing productivity.

[0097] Furthermore, according to one aspect of the present invention, even if external shocks and / or vibrations are applied during the battery's use, the shocks and / or vibrations are dispersed rather than concentrated on specific parts, thereby preventing damage to the joints between components.

[0098] Furthermore, according to one aspect of the present invention, even without providing an additional current interruption member, the current collection plate itself can perform the current interruption function, thereby ensuring safety in battery use by quickly interrupting the current when an overcurrent occurs due to a short circuit or the like.

[0099] Furthermore, according to one aspect of the present invention, D minBy including a positive electrode active material powder having a particle size of 1.0 μm or more in the positive electrode, the thermal stability of the battery can be further improved. According to the research of the present inventors, even when single particles and / or pseudo single particles are applied as the positive electrode active material, it has been confirmed that the effect of suppressing particle breakage after rolling and improving thermal stability varies depending on the particle size of the positive electrode active material powder. In particular, when particles having a particle size of less than 1.0 μm are included in the positive electrode active material powder, an increase in the linear pressure in the rolling process increases particle cracking and reduces thermal stability, and sufficient thermal stability could not be ensured when applied to a large cylindrical battery. Therefore, in the present invention, by using a positive electrode active material powder in which the minimum particle size D min is controlled to be 1.0 μm or more, the effect of improving thermal stability can be maximized.

[0100] Further, according to one aspect of the present invention, by including in the positive electrode a positive electrode active material powder in which D 50 , D max , and the particle size distribution (PSD) are appropriately adjusted, an increase in resistance due to the application of single particles can be minimized, and thus excellent capacity characteristics and output characteristics can be realized.

[0101] Further, according to one aspect of the present invention, the conductivity of the electrode can be improved by including a single-particle-based positive electrode active material coated with a conductive coating layer in the positive electrode or by including a novel CNT as a conductive material.

[0102] Further, according to one aspect of the present invention, since the positive electrode active material layer contains flaky graphite, when the positive electrode active material layer is rolled, the flaky 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, the stability, initial resistance characteristics, and charge / discharge efficiency of the cylindrical battery are improved.

[0103] Further, according to one aspect of the present invention, by including a silicon-based negative electrode active material having a large capacity in the negative electrode, a higher energy density can be realized.

[0104] Furthermore, according to one aspect of the present invention, since the positive electrode includes a loading reduction section where the loading amount of positive electrode active material is small, the length of the positive electrode active material section can be increased without worrying about lithium deposition.

[0105] Furthermore, according to one aspect of the present invention, compared to conventional batteries equipped with strip-shaped electrode tabs, the internal heat generation of the battery can be effectively reduced, thereby improving the thermal stability of the battery.

[0106] 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 description of the invention described later.

[0107] The following drawings accompanying this specification illustrate preferred embodiments of the invention and, together with the detailed description of the invention, are intended to further illustrate the technical idea of ​​the invention; therefore, the invention shall not be construed as being limited solely to what is shown in the drawings. [Brief explanation of the drawing]

[0108] [Figure 1] This is a plan view showing the structure of electrodes used in conventional tablet-type cylindrical battery cells. [Figure 2] This diagram shows the winding process of the electrode assembly included in a conventional cylindrical battery cell. [Figure 3] Figure 2 shows the process of welding the current collector plate to the curved surface of the plain section of the electrode assembly. [Figure 4] This is a cross-sectional view of a conventional tablet-type cylindrical battery cell cut along its longitudinal direction (Y-axis). [Figure 5] This is a longitudinal cross-sectional view showing a part of a cylindrical battery according to one embodiment of the present invention. [Figure 6] This is a longitudinal cross-sectional view showing a part of a cylindrical battery according to another embodiment of the present invention. [Figure 7] This is a longitudinal cross-sectional view showing a part of a cylindrical battery according to yet another embodiment of the present invention. [Figure 8] This diagram illustrates the first current collector plate included in the cylindrical battery shown in Figure 7. [Figure 9] This is a diagram illustrating a first current collector plate according to another embodiment of the present invention. [Figure 10] This is a diagram illustrating a first current collector plate according to yet another embodiment of the present invention. [Figure 11] This is a perspective view showing a cylindrical battery according to one embodiment of the present invention, and a busbar for the electrical connection of multiple cylindrical batteries. [Figure 12] This is a cross-sectional view showing the upper structure of a cylindrical battery according to one embodiment of the present invention. [Figure 13] This is a partial cross-sectional view showing a cylindrical battery according to one embodiment of the present invention. [Figure 14] This figure shows how the electrode assembly of the present invention and the second current collector plate are connected. [Figure 15] This figure shows the configuration of a second current collector according to one embodiment of the present invention. [Figure 16] This figure shows the configuration of a second current collector according to one embodiment of the present invention. [Figure 17] This figure shows the configuration of a second current collector according to one embodiment of the present invention. [Figure 18] This figure shows the configuration of a second current collector according to one embodiment of the present invention. [Figure 19] This figure shows a configuration of a second current collector according to another embodiment of the present invention. [Figure 20] This figure shows a configuration of a second current collector according to another embodiment of the present invention. [Figure 21] This is a partial cross-sectional view showing the lower structure of a cylindrical battery according to one embodiment of the present invention. [Figure 22] This diagram shows the underside of a cylindrical battery according to one embodiment of the present invention. [Figure 23] This is a schematic diagram showing a battery pack according to one embodiment of the present invention. [Figure 24] This diagram shows an automobile based on one embodiment of the present invention. [Figure 25] This is a scanning electron microscope (SEM) image of a novel CNT according to one embodiment of the present invention. [Figure 26] This is a scanning electron microscope (SEM) image of a conventional carbon nanotube (conventional CNT) that is commonly used. [Figure 27] This table compares the physical properties of conventional carbon nanotubes (CNTs) with those of novel CNTs. [Figure 28] This graph shows the surface resistance according to the ratio of conductive material when single-particle active material particles are used as the positive electrode active material. [Figure 29] This graph shows the high-temperature lifetime characteristics according to the ratio of conductive material when single-particle active material particles are used as the positive electrode active material. [Figure 30] This graph shows the high-temperature lifetime characteristics according to the ratio of conductive material when single-particle active material particles are used as the positive electrode active material. [Figure 31] This graph shows the high-temperature lifetime characteristics according to the ratio of conductive material when single-particle active material particles are used as the positive electrode active material. [Figure 32] This table compares the solid content, viscosity, resistance value in the MP coating layer, and resistance value in the MP interface layer of the positive electrode slurry when using carbon nanotubes (novel CNTs) with a BET specific surface area of ​​300 m² / g to 500 m² / g, and when using carbon nanotubes (conventional CNTs) with a BET specific surface area of ​​200 m² / g or more and less than 300 m² / g. [Figure 33a] This is an SEM image of the positive electrode active material used in Example 2-1 of the present invention. [Figure 33b] This is an SEM image of the positive electrode active material used in Example 2-2 of the present invention. [Figure 33c] This is an SEM image of the positive electrode active material used in Comparative Example 2-2 of the present invention. [Figure 34a] This graph shows the results of a hotbox test on 4680 cells manufactured according to Example 1 of the present invention. [Figure 34b]This graph shows the results of a hotbox test on 4680 cells manufactured according to Comparative Example 1 of the present invention. [Figure 34c] This graph shows the results of a hotbox test on 4680 cells produced by Sample 1 of Example 2-1 and Comparative Example 2-1 of the present invention. [Figure 34d] This graph shows the results of a hotbox test on 4680 cells produced by Samples 2 and 3 of Example 2-1, Samples 1 and 2 of Example 2-2, and Comparative Example 2-2 of the present invention. [Figure 35a] This is a cross-sectional SEM image of the positive electrode manufactured in Example 2-1 of the present invention. [Figure 35b] This is a cross-sectional SEM image of the positive electrode manufactured in Comparative Example 2-1. [Figure 36a] This graph shows the results of measuring the resistance characteristics according to the State of Charge (SOC) while charging a coin-type half-cell containing a positive electrode according to Example 3-3, Comparative Example 3-1, and Comparative Example 3-2 of the present invention to 4.2V. [Figure 36b] This graph shows the measurement results of capacity retention rate 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 37] This figure shows an electrode assembly according to one embodiment of the present invention. [Figure 38] This is a cross-sectional view taken along the line A-A' in Figure 37. [Figure 39] This diagram shows the process for manufacturing a negative electrode using one embodiment of the present invention. [Figure 40] This diagram shows the process for manufacturing a negative electrode using one embodiment of the present invention. [Figure 41] This is a perspective view showing the negative electrode according to one embodiment of the present invention. [Figure 42] This diagram shows the process for manufacturing a positive electrode according to one embodiment of the present invention. [Figure 43] This diagram shows the process for manufacturing a positive electrode according to one embodiment of the present invention. [Figure 44]This is a perspective view showing the positive electrode according to one embodiment of the present invention. [Figure 45] This figure shows an electrode assembly according to a comparative embodiment of the present invention. [Figure 46] This is a cross-sectional view taken along the line B-B' in Figure 45. [Figure 47] This figure shows the process for manufacturing a negative electrode according to a comparative embodiment of the present invention. [Figure 48] This figure shows the process for manufacturing a positive electrode according to a comparative embodiment of the present invention. [Figure 49] This graph shows the change in energy density in a battery using a mixture of silicon-based and carbon-based anode active materials as the anode active material, depending on the content of the silicon-based anode active material and whether or not the silicon-based anode active material is doped. [Modes for carrying out the invention]

[0109] Preferred embodiments of the present invention will now be described in detail with reference to the attached drawings. Prior to this, terms and words used herein and in the claims shall not be interpreted in their usual and dictionary sense, but in accordance with the principle that the inventor himself may appropriately define the concepts of terms in order to best describe the invention, and shall be interpreted in a sense and concept corresponding to the technical idea of ​​the present invention. Accordingly, the embodiments described herein and the configurations shown in the drawings represent only one of the most preferred embodiments of the present invention and do not represent the entire technical idea of ​​the present invention, and it should be understood that there may be a variety of equivalents and modifications that can be substituted therein at the time of this application.

[0110] Furthermore, to aid in understanding the invention, the accompanying drawings are not shown to actual scale, and the dimensions of some components may be exaggerated. Also, the same component in different embodiments may be assigned the same reference numeral.

[0111] The dimensions and thicknesses of each component shown in the illustrations are arbitrary for illustrative purposes, and the present invention is not necessarily limited by the illustrations. In the drawings, thicknesses are shown enlarged to clearly illustrate many layers and regions. Also, in the drawings, the thicknesses of some layers and regions are shown exaggerated for illustrative purposes.

[0112] Furthermore, when a part such as a layer, membrane, region, or plate is said to be "on top of" or "above" another part, this includes not only the case where it is "directly above" the other part, but also the case where there is yet 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. Also, being "on top of" or "above" a reference part means being located above or below the reference part, and does not necessarily mean being located "above" or "above" in the opposite direction to gravity.

[0113] Furthermore, throughout the specification, when a part "includes" other components, unless otherwise specified, it means that it may include other components, rather than excluding them.

[0114] Furthermore, throughout the specification, "plan view" refers to a view of the subject area from above, and "section view" refers to a view of a cross-section of the subject area cut vertically, viewed from the side.

[0115] Referring to Figure 5, a cylindrical battery 1 according to one embodiment of the present invention includes an electrode assembly 300, a battery housing 20, a first current collector plate 30, a cap plate 40, and battery terminals 60. The cylindrical battery 1 may further include a sealing gasket G1 and / or an insulating gasket G2 and / or a second current collector plate 50 and / or an insulator S.

[0116] The electrode assembly 300 comprises 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 membrane interposed between the first electrode and the second electrode. The first electrode is either 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 can be manufactured by winding up a laminate formed by stacking the first electrode, separator membrane, second electrode, and separator membrane in sequence at least once. That is, the electrode assembly 300 applied to embodiments of the present invention may be a jelly roll type electrode assembly. Such a jelly roll type electrode assembly 300 may have a winding center hole H1 formed substantially in its center and extending along the height direction (a direction parallel to the height direction of the cylindrical battery 1 shown in Figure 5). On the other hand, a separator membrane may be further provided on the outer circumferential surface of the electrode assembly 300 for insulation from the battery housing 20.

[0117] 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. 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 Figure 5), there is a plain area where the first electrode active material is not coated. The plain area of ​​the first electrode extends from one end to the other along the longitudinal direction of the first electrode, relative to the first electrode in its unfolded state. The plain area of ​​the first electrode functions as the first electrode tab 11 as described above. The first electrode tab 11 is provided at the top of the electrode assembly 300 housed in the battery housing 20 in the height direction (parallel to the height direction of the cylindrical battery 1 shown in Figure 5). The first electrode tab 11 may be, for example, a negative electrode tab.

[0118] 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. At the other end of the second electrode current collector in the width direction (parallel to the height direction of the cylindrical battery 1 shown in Figure 5), there is a plain area where the second electrode active material is not coated. The plain area of ​​the second electrode extends from one end to the other along the longitudinal direction of the second electrode, relative to the second electrode in its unfolded state. The plain area of ​​the second electrode functions as a second electrode tab 12 as described above. The second electrode tab 12 is located at the lower, height-direction, of the electrode assembly 300 housed within the battery housing 20. The second electrode tab 12 may, for example, be a positive electrode tab.

[0119] In other words, the first electrode tab 11 and the second electrode tab 12 extend and protrude in opposite directions along the height direction of the cylindrical battery 1.

[0120] However, the present invention is not limited to such forms of the electrode assembly 300.

[0121] The battery housing 20 is a substantially cylindrical housing with an open portion formed on one side, and is made of a conductive metal material. The side surface of the battery housing 20 and the bottom surface located opposite the open portion (the bottom surface with reference to Figure 5) can be formed integrally. That is, the battery housing 20 may have an open upper end in the height direction and a closed lower end. The bottom surface of the battery housing 20 may have a substantially flat shape. The battery housing 20 houses the electrode assembly 300 through the open portion formed on one side in the height direction. The battery housing 20 may also house the electrolyte through the open portion. However, the present invention is not limited to such a form of the battery housing 20.

[0122] 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 polarity as the first electrode tab 11.

[0123] The battery housing 20 may include a beading portion 21 formed on the peripheral edge adjacent to the opening and pushed inward. The battery housing 20 may have a beading portion 21 formed at the upper end. The battery housing 20 may further have a crimping portion 22 formed above the beading portion 21. The beading portion 21 has a form in which the outer peripheral surface of the battery housing 20 is pushed in to a predetermined depth. The beading portion 21 is formed on the upper part of the electrode assembly 300. The inner diameter of the battery housing 20 in the region where the beading portion 21 is formed is formed to be smaller than the diameter of the electrode assembly 300.

[0124] The beading portion 21 provides a support surface on which the cap plate 40 is placed. The beading portion 21 can also provide a support surface on which at least a portion of the periphery of the first current collector plate 30, which will be described later, is placed and joined. That is, at least a portion of the periphery of the first current collector 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 can be placed on the upper surface of the beading portion 21. As shown in Figures 6 and 7, the upper surface of the beading portion 21 may have a form in which at least a portion extends along a direction substantially parallel to the lower surface of the battery housing 20, that is, along a direction substantially perpendicular to the side wall of the battery housing 20, so that at least a portion of the periphery of the first current collector plate 30 and / or the periphery of the cap plate 40 can be stably supported.

[0125] The crimping portion 22 is formed on the upper part of the beading portion 21. The crimping portion 22 has a shape that extends and bends to cover and wrap around the periphery of the cap plate 40 which is positioned on the upper part of the beading portion 21. Due to the shape of the crimping portion 22, the cap plate 40 is fixed onto the beading portion 21. Of course, such a crimping portion 22 may be omitted, and the cap plate 40 may be fixed to cover the open part of the battery housing 20 through other fixing structures.

[0126] The first current collector plate 30 according to one embodiment of the present invention will be described in detail below with reference to Figures 7 and 8.

[0127] First, referring to Figure 7, the first current collector plate 30 according to one embodiment of the present invention is housed inside the battery housing 20 and is electrically connected to the electrode assembly 300 and also electrically connected to the battery housing 20. That is, the first current collector plate 30 electrically connects the electrode assembly 300 and the battery housing 20.

[0128] The first current collector plate 30 includes a support portion 31 positioned on one surface of the electrode assembly 300, at least one first 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 the end of the first tab coupling portion 32 and coupled to the inner surface of the battery housing 20, and is located within the battery housing.

[0129] The support portion 31 and at least one first tab coupling portion 32 are positioned on the upper part of the electrode assembly 300 and may be located below the beading portion 21 if the beading portion 21 is formed in the battery housing 20.

[0130] The support portion 31 may include a first current collector hole H2 formed at a position corresponding to a winding center hole H1 formed in approximately the center of the electrode assembly 300. The winding center hole H1 and the first current collector hole H2, which are in communication with each other, can function as passages for inserting welding rods for welding the battery terminal 60 and the second current collector plate 50 or welding the battery terminal 60 and lead tabs (not shown), or for irradiating with a laser.

[0131] The support portion 31 may be in the shape of a substantially circular plate. For example, referring to Figure 8, the support portion 31 may be in the shape of an annular plate with a first current collector hole H2 at its center.

[0132] The at least one first tab coupling portion 32 may have a configuration that extends substantially radially from the support portion 31 toward the side wall of the battery housing 20. There may be, for example, multiple first tab coupling portions 32. Referring to Figure 8, for example, the multiple first tab coupling portions 32 may be located spaced apart from each other along the periphery of the support portion 31. By providing the cylindrical battery 1 according to this embodiment of the present invention with multiple first tab coupling portions 32, the bonding area with the first electrode tab 11 can be increased. This ensures a bonding force between the first electrode tab 11 and the first tab coupling portion 32, and reduces electrical resistance.

[0133] The longitudinal end of the first tab coupling portion 32 may be located inside the innermost part of the beading portion 21 formed in the battery housing 20. More specifically, the boundary region between the first tab coupling portion 32 and the housing coupling portion 33 may be located inside the innermost part of the beading portion 21 formed in the battery housing 20, on the winding center hole H1 side. With such a structure, damage to the coupling portion between components that may occur due to excessive bending of the first current collector plate 30 in order to position the end of the housing coupling portion 33 on the beading portion 21 can be prevented.

[0134] On the other hand, in order to ensure bonding force and reduce electrical resistance by increasing the bonding area between the first current collector plate 30 and the electrode assembly 300, not only the first tab bonding portion 32 but also the support portion 31 can be bonded to the first electrode tab 11. The end of the first electrode tab 11 can be formed in a shape that is bent parallel to the first tab bonding portion 32. When the end of the first electrode tab 11 is formed in this way and bonded to the first tab bonding portion 32 in a state parallel to the first tab bonding portion 32, the bonding area is increased, resulting in improved bonding force and reduced electrical resistance, and the overall height of the electrode assembly 300 is minimized, resulting in improved energy density.

[0135] The housing coupling portion 33 may extend from the end of the first tab coupling portion 32 and be coupled to the inner surface of the battery housing 20. For example, the housing coupling portion 33 may have a form that extends from the end of the first tab coupling portion 32 toward the side wall of the battery housing 20. There may be multiple housing coupling portions 33. For example, referring to Figure 8, the multiple housing coupling portions 33 may be located spaced apart from each other along the support portion 31. Referring to Figure 5, the housing coupling portion 33 may be coupled to the beading portion 21 on the inner surface of the battery housing 20. As shown in Figures 6 and 7, the upper surface of the beading portion 21 has a form that extends in a direction substantially parallel to the lower surface of the battery housing 20, i.e., in a direction substantially perpendicular to the side wall of the battery housing 20, and the housing coupling portion 33 also has a form that extends in the same direction, so that the housing coupling portion 33 can make stable contact with the beading portion 21. Furthermore, the stable contact of the housing coupling portion 33 on the beading portion 21 allows for smooth welding between the two parts, thereby improving the bonding force between the two parts and minimizing the increase in resistance at the coupling point. In addition, the structure in which the first current collector plate 30 is coupled to the beading portion 21 of the battery housing 20 rather than the inner surface of the cylindrical portion of the battery housing 20 reduces the distance between the first current collector plate 30 and the beading portion 21. Consequently, the dead space inside the battery housing 20 is minimized, and the energy density of the cylindrical battery 1 can be improved.

[0136] Referring to Figures 7 and 8, the housing coupling portion 33 includes a contact portion 33a that is coupled to the inner surface of the battery housing 20, and a first connecting portion 33b that connects the first tab coupling portion 32 and the contact portion 33a.

[0137] The contact portion 33a is coupled to the inner surface of the battery housing 20. When a 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, both the beading portion 21 and the contact portion 33a may have a form that extends in a direction substantially parallel to the lower surface of the battery housing 20, that is, in a direction substantially perpendicular to the side wall of the battery housing 20.

[0138] Referring to Figure 7, the first connecting portion 33b may have at least one bent portion B whose direction of extension is changed between the support portion 31 and the contact portion 33a. That is, the first connecting portion 33b may have a structure similar to a spring or a bellows, which can be contracted and extended within a certain range. Such a structure of the first connecting portion 33b allows the contact portion 33a to be brought into close contact with the beading portion 21 during the process of housing the electrode assembly 300 to which the first current collector plate 30 is connected inside the battery housing 20, even if the height of the electrode assembly 300 varies within a certain range.

[0139] Although the drawing shows one bent portion B, the present invention is not limited to this illustration, and of course, it may be provided with multiple bent portions B.

[0140] For example, when no external force is applied to the first current collector plate 30 and it is not deformed, the vertical distance (D) between the contact portion 33a and the support portion 31 is preferably 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 with the first current collector plate 30 attached is placed inside the battery housing 20, or it is preferably formed to be even smaller within the extendable range of the first connecting portion 33b. When the first connecting portion 33b is configured to satisfy these conditions, when the electrode assembly 300 with the first current collector plate 30 attached is placed inside the battery housing 20, the contact portion 33a naturally comes into close contact with the beading portion 21.

[0141] Furthermore, the structure of the first connecting portion 33b, which can be contracted and extended in this manner, can mitigate the impact caused by the movement of the electrode assembly 300 within a certain range, even if vibration and / or shock occur during the use of the cylindrical battery 1 (see Figure 5) and the electrode assembly 300 moves up and down.

[0142] On the other hand, when the first 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, as shown in the figure. The bending direction of the first connecting portion 33b is to prevent damage to the joint between the first current collector plate 30 and the electrode assembly 300 and / or the joint between the first current collector plate 30 and the battery housing 20 during the sizing process. The sizing process is a compression process in the manufacture of the cylindrical battery 1 that reduces the height occupied by the beading portion 21 area of ​​the battery housing 20, thereby reducing the overall height of the cylindrical battery 1. As a result of checking the degree of damage to the welded part after the sizing process by changing the formation of the bent portion B and the protrusion direction of the bent portion B, it was confirmed that almost no damage occurred in the cylindrical battery 1 having a structure in which the first connecting portion 33b is bent so that the bent portion B protrudes toward the center of the cylindrical battery 1.

[0143] Next, referring to Figure 9, a first current collector plate 30 according to another embodiment of the present invention is shown. The first current collector plate 30 according to the other embodiment of the present invention differs from the first current collector plate 30 in Figure 8 above only in the shape of the contact portion 33a, and otherwise the structure of the first current collector plate 30 described above can be applied substantially the same way.

[0144] Referring to Figure 9, the contact portion 33a may have a form in which at least a part extends along the inner circumferential surface of the battery housing 20. For example, the contact portion 33a may be an arc shape extending along the beading portion 21. Although not shown, in order to maximize the contact area, the first current collector plate 30 may be configured such that the sum of the extending lengths of the contact portions 33a of each housing coupling portion 33 is approximately the same as the inner circumference of the battery housing 20. This results in improved coupling force and reduced electrical resistance due to the maximization of the coupling area.

[0145] Next, referring to Figure 10, a first current collector plate 30 according to yet another embodiment of the present invention is shown. The first current collector plate 30 according to yet another embodiment of the present invention differs from the first current collector plate 30 in Figure 9 only in the shape of the first connecting portion 33b, and otherwise the structure of the first current collector plate 30 described above can be applied substantially in the same way.

[0146] Referring to Figure 10, the first connecting portion 33b may have a form in which at least a part extends along the inner circumferential surface of the battery housing 20. For example, the contact portion 33a may be an arc shape extending along the beading portion 21 of the battery housing, and the first connecting portion 33b may be an arc shape extending along the contact portion 33a. With such a structure, the area of ​​the first current collector plate 30 is further increased compared to the first current collector plate 30 shown in Figure 9, thereby maximizing the effect of reducing electrical resistance.

[0147] On the other hand, referring to Figure 10, the first current collector plate 30 differs from the first current collector plate 30 shown in Figure 8 or Figure 9 in that it does not need to have a bent portion B. If the bent portion B is not provided, the raw materials required for manufacturing the first current collector plate 30 can be reduced. This reduces the manufacturing cost of the first current collector plate 30.

[0148] The first current collector plate 30 may have a plurality of radially formed irregularities (not shown) on the surface facing the first electrode tab 11. If irregularities are formed, the first current collector plate 30 can be pressed against the irregularities to push the first electrode tab 11 into them. The ends of the first current collector plate 30 and the first electrode tab 11 can be joined by welding, for example, laser welding.

[0149] Referring to Figure 5, the cap plate 40 covers the opening formed on one side of the battery housing 20. If the battery housing 20 according to an embodiment of the present invention includes a beading portion 21, the cap plate 40 can be placed on the beading portion 21 formed on the battery housing 20. Also, if the battery housing 20 according to an embodiment of the present invention includes a crimping portion 22, the cap plate 40 can be fixed by the crimping portion 22. In this case, a sealing gasket G1 can be interposed between the battery housing 20 and the cap plate 40 to improve the fixing force and the airtightness of the battery housing 20. However, in the embodiment of the present invention, the cap plate 40 is not a component that functions as a current passage. Therefore, if the battery housing 20 and the cap plate 40 can be firmly fixed through welding or the application of other components to ensure the airtightness of the opening of the battery housing 20, the application of a sealing gasket G1 is not essential. On the other hand, as described above, the battery housing 20 according to one embodiment of the present invention does not need to have a beading portion 21 and / or a crimping portion 22. In this case, the sealing gasket G1 may be interposed between a fixing structure provided on the open side of the battery housing 20 and the cap plate 40 in order to ensure the airtightness of the battery housing 20.

[0150] The cap plate 40 may be made of a metal material, for example, to ensure rigidity. In a cylindrical battery 1 according to one embodiment of the present invention, the cap plate 40 has no polarity even if it is made of a conductive metal material. Having no polarity means that the cap plate 40 is electrically insulated from the battery housing 20 and the battery terminals 60 described later. Therefore, the cap plate 40 does not function as a positive or negative terminal. Consequently, 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.

[0151] On the other hand, regarding the case in which the sealing gasket G1 is applied, the sealing gasket G1 may be substantially ring-shaped and cover the cap plate 40. The sealing gasket G1 may cover the top, bottom, and sides of the cap plate 40 simultaneously. The radial length of the portion of the sealing gasket G1 that covers the bottom surface of the cap plate 40 may be shorter than or the same as the radial length of the portion of the sealing gasket G1 that covers the top surface of the cap plate 40. If the radial length of the portion of the sealing gasket G1 that covers the bottom surface of the cap plate 40 is too long, the sealing gasket G1 may press against the first current collector plate 30 during the process of compressing the battery housing 20 vertically, potentially damaging the first current collector plate 30 or the battery housing 20. Therefore, it is necessary to keep the radial length of the portion of the sealing gasket G1 that covers the bottom surface of the cap plate 40 small at a certain level. For example, as shown in Figure 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 Figures 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.

[0152] On the other hand, the contact portion 33a can be interposed and fixed between the beading portion 21 and the sealing gasket G1. That is, with the contact portion 33a interposed between the beading portion 21 and the sealing gasket G1, the contact portion 33a can be fixed by the crimping force of the crimping portion 22.

[0153] 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 clamping force alone. Or, if the sealing gasket G1 shrinks due to heat, or if the crimping portion 22 is deformed by an external impact, the bonding force between the current collector plate and the battery housing 20 may decrease. Therefore, with the contact portion 33a placed on the beading portion 21, the first current collector plate 30 can be fixed to the battery housing 20 by welding. After that, the cylindrical battery 1 is completed by placing the cap plate covered with the sealing gasket G1 on the contact portion 33a and forming the crimping portion 22. At this time, the welding method may be, for example, laser welding, resistance welding, ultrasonic welding, etc., but the welding method is not limited to these.

[0154] On the other hand, the cap plate 40 may be provided with 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 on a part of the cap plate 40 and corresponds to a structurally weaker area than the surrounding area so that it easily breaks when pressure is applied. The venting portion 41 may be a thinner area than the surrounding area. 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 will break and the gas generated inside the battery housing 20 will be discharged. The venting portion 41 can be formed, for example, by notching on one surface or both surfaces of the cap plate 40 to partially reduce the thickness of the battery housing 20.

[0155] The battery terminal 60 is electrically connected to the second electrode tab 12. The battery terminal 60 may be electrically connected to the second electrode tab 12 of the electrode assembly 300 by passing through the battery housing 20 from the opposite side of the opening of the battery housing 20. The battery terminal 60 may pass through approximately the center of the lower surface of the battery housing 20. The battery terminal 60 may include a terminal exposure portion 60a and a terminal insertion portion 60b. The terminal exposure portion 60a is exposed to the outside of the closed surface of the battery housing 20. The terminal exposure portion 60a may be located approximately the center of the closed surface of the battery housing 20. The maximum diameter of the terminal exposure portion 60a may be larger than the maximum diameter of the through hole formed in the battery housing 20. The terminal insertion portion 60b may be electrically connected to the second electrode tab 12 by passing through approximately the center of the closed surface of the battery housing 20. The terminal insertion portion 60b may be rivet-connected to the inner surface of the battery housing 20. That is, the end of the terminal insertion portion 60b may have a shape that is bent toward the inner surface of the battery housing 20. The maximum diameter of the end of the terminal insertion portion 60b may be larger than the maximum diameter of the through hole in the battery housing 20. Part of the battery terminal 60 may be exposed to the outside of the battery housing 20, and the remaining part may be located inside the battery housing 20. The battery terminal 60 may be electrically connected to the electrode assembly 300 by being connected, for example, to a second current collector plate 50 which is connected to a second electrode tab 12, or by being connected to a lead tab (not shown) which is connected to the second electrode tab 12. The inner surface of the terminal insertion portion 60b may be welded to the second current collector plate 50 which is connected to the second electrode tab 12. An insulator S, which will be described later, may be interposed between the second current collector plate 50 and the inner surface of the battery housing 20.

[0156] Considering the polarity and function of such a battery terminal 60, the battery terminal 60 must maintain an insulating 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. Or, the battery terminal 60 and the battery housing 20 may be positioned separately so that they cannot come into contact, and the battery terminal 60 may be structurally fixed firmly. Or, a combination of several of the above methods may be applied.

[0157] The insulating gasket G2 includes an exposed gasket portion G2a and a inserted gasket portion G2b. The exposed gasket portion G2a is interposed between the exposed terminal portion 60a of the battery terminal 60 and the battery housing 20. The inserted gasket portion G2b is interposed between the inserted terminal portion 60b of the rivet terminal 60 and the battery housing 20. The inserted gasket portion G2b can be deformed together with the inserted terminal portion 60b during reveting and can adhere tightly to the inner surface of the battery housing 20. The insulating gasket G2 may be made of, for example, an insulating polymer resin.

[0158] The gasket exposed portion G2a of the insulating gasket G2 may have a form that extends to cover the outer circumferential surface of the terminal exposed portion 60a of the rivet terminal 60. When the insulating gasket G2 covers the outer circumferential surface of the rivet terminal 60, it is possible to prevent short circuits from occurring during the process of connecting electrical connection components such as busbars to the outer surface of the battery housing 20 and / or the rivet terminal 60. Although not shown, the gasket exposed portion G2a may have a form that extends to cover not only the outer circumferential surface of the terminal exposed portion 60a but also a part of the outer surface.

[0159] When the insulating gasket G2 is made of a polymer resin, the insulating gasket G2 can be bonded to the battery housing 20 and the battery terminal 60 by heat fusion. In this case, the airtightness at the bonding interface between the insulating gasket G2 and the battery terminal 60 and the bonding interface between the insulating gasket G2 and the battery housing 20 is enhanced. On the other hand, when the gasket exposed portion G2a of the insulating gasket G2 extends to the upper surface of the terminal exposed portion 60a, the battery terminal 60 can be integrally bonded to the insulating gasket G2 by insert injection.

[0160] On the outer surface of the battery housing 20, the area excluding the area occupied by the rivet terminal 60 and the insulating gasket G2 corresponds to the negative terminal having the opposite polarity to the rivet terminal 60.

[0161] In other words, a 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 located in the same direction. Therefore, when multiple cylindrical batteries 1 are electrically connected, electrical connection components such as busbars can be placed on only one side of the cylindrical battery 1. This can lead to a simplification of the battery pack structure and an improvement in 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 joining electrical connection components such as busbars to the first electrode terminal T1. As a result, the cylindrical battery 1 can ensure sufficient bonding strength between the electrical connection components and the first electrode terminal T1, and the resistance at the bonding site can be reduced to a desirable level.

[0162] On the other hand, if an insulating gasket G2 is applied for electrical insulation and riveting is applied to secure the battery terminals 60, the insulating gasket G2 may deform together with the riveting of the battery terminals 60 and bend toward the inner surface of the upper closing portion of the battery housing 20. If the insulating gasket G2 is made of a resin material, the insulating gasket G2 may be bonded to the battery housing 20 and the battery terminals 60 by heat fusion. In this case, the airtightness at the bonding interface between the insulating gasket G2 and the battery terminals 60 and the bonding interface between the insulating gasket G2 and the battery housing 20 is enhanced.

[0163] In one embodiment of the present invention, the entire surface of the battery housing 20 can function as a first electrode terminal T1. For example, if the first electrode tab 11 is a negative electrode tab, the first electrode terminal T1 can be a negative electrode terminal. The cylindrical battery 1 according to an embodiment of the present invention has a structure in which a battery terminal 60 exposed on the lower surface located opposite the opening of the battery housing 20 is used as a second electrode terminal T2, and the area of ​​the lower 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 multiple cylindrical batteries 1 are electrically connected, the cylindrical battery 1 according to an embodiment of the present invention can connect all positive and negative electrodes in one direction, simplifying the electrical connection structure. Furthermore, since the cylindrical battery 1 according to an embodiment of the present invention has a structure in which most of the lower surface located opposite the opening of the battery housing 20 can be used as an electrode terminal, it has the advantage of being able to secure a sufficient area for welding components for electrical connection.

[0164] The cylindrical battery 1 described above will be explained in more detail below with reference to Figures 11 to 24. In the following description, there may be other embodiments that can be selectively applied to the same components as described above. Also, there may be some overlap in the following description with the description above.

[0165] Referring to Figures 11 and 12, a cylindrical battery 1 according to one embodiment of the present invention includes an electrode assembly 300, a battery housing 20, a cap plate 40, a second current collector plate 50, and battery terminals 60. In addition to the components described above, the cylindrical battery 1 may further include a sealing gasket G1 and / or an insulating gasket G2 and / or an insulator S and / or a first current collector plate 30.

[0166] The electrode assembly 300 includes a first electrode tab 11 and a second electrode tab 12. The second electrode tab 12 may be located at the top of the electrode assembly 300 in the height direction (Z-axis direction) when housed in the battery housing 20. The first electrode tab 11 may be located at the bottom of the electrode assembly 300 in the height direction (Z-axis direction) when housed in the battery housing 20.

[0167] The second electrode tab 12 and the first electrode tab 11 may extend in opposite directions along the width direction of the electrode assembly 300, i.e., along the height direction (Z-axis direction) of the cylindrical battery 1. The second electrode tab 12 may extend toward the closed portion of the battery housing 20, and the first electrode tab 11 may extend toward the open portion of the battery housing 20.

[0168] The battery housing 20 is a substantially cylindrical housing with an opening at the bottom, and is made of a conductive material such as metal. An opening may be formed at the lower end in the height direction of the battery housing 20, and a closed portion may be formed at the upper end. The battery housing 20 can house the electrode assembly 300 through the opening at the bottom, and the electrolyte may also be housed together with it.

[0169] Referring to Figures 12 and 21, 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. The beading portion 21 is formed by pressing around the outer circumferential surface of the battery housing 20. The beading portion 21 prevents the electrode assembly 300, which has a size substantially corresponding to the width of the battery housing 20, from coming out of the opening formed at the lower end of the battery housing 20, and can function as a support on which the cap plate 40 is placed.

[0170] The crimping portion 22 may be formed at the lower part of the beading portion 21. The crimping portion 22 has a shape that extends and bends to wrap around the outer circumferential surface of the cap plate 40, which is positioned below the beading portion 21, and a portion of the lower surface of the cap plate 40.

[0171] However, the present invention does not exclude cases where the battery housing 20 does not have such beading portion 21 and / or crimping portion 22. In one embodiment of the present invention, if the battery housing 20 does not have beading portion 21 and / or crimping portion 22, fixing the electrode assembly 300 and / or fixing the cap plate 40 and / or sealing the battery housing 20 can be achieved, for example, by the additional application of a component that can function as a stopper for the electrode assembly 300 and / or the additional application of a structure on which the cap plate 40 can be mounted and / or welding the battery housing 20 and the cap plate 40.

[0172] The battery housing 20 may have a thickness of approximately 0.5 mm to 1.0 mm in the region constituting its closed end, more preferably in the range of approximately 0.6 mm to 0.8 mm. The battery housing 20 may have a thickness of approximately 0.3 mm to 0.8 mm in the side wall portion constituting its outer circumferential surface, more preferably in the range of approximately 0.30 mm to 0.60 mm. According to one embodiment of the present invention, a plating layer may be formed on the battery housing 20. In this case, the plating layer may contain, for example, nickel (Ni). The thickness of the plating layer may be approximately 1.5 μm to 6.0 μm.

[0173] The thinner the battery housing 20, the larger the internal space, which improves energy density and allows for the manufacture of a cylindrical battery 1 with a large capacity. On the other hand, the thicker the housing, the less likely there is to be a chain reaction of flame propagation to adjacent cells during explosion tests, which is advantageous in terms of safety.

[0174] The thinner the plating layer, the more vulnerable it is to corrosion; conversely, the thicker the layer, the more difficult the manufacturing process becomes or the higher the likelihood of plating peeling. Considering all these factors, it is necessary to determine the optimal thickness of the battery housing 20 and the optimal thickness of the plating layer. Furthermore, considering all these factors, it is necessary to control the thickness of the closing section and the side walls of the battery housing 20, respectively.

[0175] Referring to Figures 12 and 21, the cap plate 40 can seal the opening formed at the lower end of the battery housing 20. That is, the cap plate 40 can form the lower surface of the cylindrical battery 1.

[0176] As described above, the cylindrical battery 1 according to one embodiment of the present invention has a structure in which both the positive and negative electrode terminals are located at the top, making the upper structure more complex than the lower structure. Therefore, a venting portion 41 may be formed on the cap plate 40 that constitutes the lower surface of the cylindrical battery 1 in order to smoothly discharge gas generated inside the battery housing 20. As shown in Figure 19, it is preferable that the lower end of the cap plate 40 is positioned above the lower end of the battery housing 20. In this case, even if the lower end of the battery housing 20 is in contact with the ground or the bottom surface of a housing for the configuration of a module or pack, the cap plate 40 will not be in contact with the ground or the bottom surface of a housing for the configuration of a module or pack. Therefore, it is possible to prevent the pressure required for the rupture of the venting portion 41 from changing from the design value due to the weight of the cylindrical battery 1, thereby ensuring smooth rupture of the venting portion 41.

[0177] On the other hand, if the venting portion 41 has a closed-loop configuration as shown in Figures 21 and 22, a greater distance from the center of the cap plate 40 to the venting portion 41 is advantageous in terms of ease of breakage. This is because, when the same venting pressure is applied, 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, making it easier to break. Furthermore, a greater distance from the center of the cap plate 40 to the venting portion 41 is also advantageous in terms of smooth discharge of venting gas. From this viewpoint, it is advantageous for the venting portion 41 to be formed along the periphery of a substantially flat region that protrudes downward (downward with reference to Figure 19) from the peripheral region of the cap plate 40.

[0178] Figure 22 shows a case where the venting portion 41 is formed continuously on the cap plate 40 in a substantially circular shape, but this does not limit the present invention. The venting portion 41 may be formed discontinuously on the cap plate 40 in a substantially circular shape, or it may be formed in a substantially linear shape or other shape.

[0179] Referring to Figures 12 to 14, the second current collector plate 50 is coupled to the upper part of the electrode assembly 300. The second current collector plate 50 is made of a conductive metal material and is connected to the second electrode tab 12.

[0180] Referring to Figure 14, the second current collector plate 50 can be bonded to a bonding surface formed by bending the end of the second electrode tab 12 in a direction parallel to the second current collector plate 50. The bending direction of the second electrode tab 12 may be, for example, toward the winding central hole H1 of the electrode assembly 300. When the second electrode tab 12 has such a bent form, the space occupied by the second electrode tab 12 is reduced, which can improve the energy density. In addition, the increase in the bonding area between the second electrode tab 12 and the second current collector plate 50 can improve the bonding force and reduce resistance.

[0181] Referring to Figures 15 to 18 along with Figures 12 to 14, the second current collector plate 50 includes a peripheral edge 51, a second tab coupling portion 52, and a terminal coupling portion 53. The peripheral edge 51 may have a substantially rim shape with an open space E formed in the center. Although the drawings only show the case where the peripheral edge 51 has a substantially circular rim shape, this does not limit the present invention. The peripheral edge 51 may have a substantially square rim shape or other shape, contrary to the figures shown.

[0182] The second tab coupling portion 52 extends inward from the peripheral portion 51 and is coupled to the second electrode tab 12. The terminal coupling portion 53 is located inside the peripheral portion 51, spaced apart from the second tab coupling portion 52. The terminal coupling portion 53 can be coupled to the battery terminal 60 by welding. The terminal coupling portion 53 may be located, for example, in the center of the inner space of the peripheral portion 51. The terminal coupling portion 53 may be positioned in a location corresponding to the winding center hole H1 of the electrode assembly 300.

[0183] The second tab coupling portion 52 and the terminal coupling portion 53 are not directly connected, but are arranged at a distance from each other and electrically connected by the peripheral portion 51. Thus, the second current collector plate 50 according to one embodiment of the present invention has a structure in which the second tab coupling portion 52 and the terminal coupling portion 53 are not directly connected but are connected through the peripheral portion 51. When shock and / or vibration occurs in the cylindrical battery 1, the shock applied to the coupling portion between the second tab coupling portion 52 and the second electrode tab 12 and the coupling portion between the terminal coupling portion 53 and the battery terminal 60 can be dispersed. Therefore, the second current collector plate 50 according to the embodiment of the present invention can minimize or prevent damage to the welded portion due to external shock. The second current collector plate 50 according to the embodiment of the present invention has a structure in which stress is concentrated at the coupling portion between the peripheral portion 51 and the terminal coupling portion 53 when an external shock is applied. However, since such a coupling portion is not a portion where a welded portion is formed for joining parts, it is possible to prevent product defects from occurring due to damage to the welded portion due to external shock.

[0184] The second current collector plate 50 may further include a second connecting portion 54 that extends inward from the peripheral portion 51 and connects to the terminal connecting portion 53. At least a portion of the second connecting portion 54 may be formed to be narrower in width than the second tab connecting portion 52. In this case, the electrical resistance increases in the second connecting portion 54, and when current flows through the second connecting portion 54, a larger resistance is generated compared to other parts, so that when an overcurrent occurs, a portion of the second connecting portion 54 breaks and the overcurrent is interrupted. The width of the second connecting portion 54 may be adjusted to an appropriate level considering such an overcurrent interruption function.

[0185] The second connecting portion 54 may have a tapered portion 54a whose width gradually narrows from the inner surface of the peripheral portion 51 toward the terminal connecting portion 53. When the tapered portion 54a is provided, the rigidity of the component is improved at the connection point between the second connecting portion 54 and the peripheral portion 51.

[0186] Multiple second tab connectors 52 may be provided. Multiple second tab connectors 52 may be arranged at equal intervals from one another along the extending direction of the peripheral portion 51. The extending lengths of each second tab connector 52 may be the same. The terminal connector 53 may be arranged to be surrounded by multiple second tab connectors 52. The second connecting portion 54 may be located between an adjacent pair of second tab connectors 52. In this case, the distance from the second connecting portion 54 to one of the pair of second tab connectors 52 along the extending direction of the peripheral portion 51 may be the same as the distance from the second connecting portion 54 to the other of the pair of second tab connectors 52 along the extending direction of the peripheral portion 51.

[0187] Multiple second connecting portions 54 may be provided. Each of the multiple second connecting portions 54 may be positioned between an adjacent pair of second tab connecting portions 52. The multiple second connecting portions 54 may be positioned at equal intervals from one another along the extending direction of the peripheral portion 51.

[0188] As described above, when multiple second tab connectors 52 and / or second connecting parts 54 are provided, if the distance between the second tab connectors 52 and / or the distance between the second connecting parts 54 and / or the distance between the second tab connectors 52 and the second connecting part 54 is kept constant, then a smooth flow of current from the second tab connector 52 to the second connecting part 54 or from the second connecting part 54 to the second tab connector 52 can be formed.

[0189] Referring to Figures 19 and 20, the second connecting portion 54 may have a notch N formed by partially narrowing the width of the second connecting portion 54. When the notch N is provided, the electrical resistance in the region where the notch N is formed increases, which enables rapid current interruption when an overcurrent occurs.

[0190] When the second connecting portion 54 includes a tapered portion 54a, the notch N may be located even closer to the tapered portion 54a than the terminal connecting portion 53. In this case, the structure of the tapered portion 54a, which gradually narrows in width, positions the notch N adjacent to a region with high heat generation, enabling even faster overcurrent interruption.

[0191] The second current collector plate 50 may have a plurality of radially formed irregularities (not shown) on the surface facing the second electrode tab 12. If irregularities are formed, the second current collector plate 50 can be pressed against the irregularities to push the second electrode tab 12 into them. The ends of the second current collector plate 50 and the second electrode tab 12 can be joined by welding, for example, laser welding.

[0192] Referring to Figures 11 to 13 and Figure 15, the battery terminal 60 is made of a conductive metal material and is connected to the terminal coupling portion 53 of the second current collector plate 50. The battery terminal 60 may be configured to penetrate a closed portion located on the opposite side of the open portion of the battery housing 20. When the cylindrical battery 1 according to an embodiment of the present invention is equipped with an insulator S, which will be described later, the battery terminal 60 is configured to pass through the insulator S and connect to the terminal coupling portion 53 of the second current collector plate 50.

[0193] Thus, the battery terminal 60 is electrically connected to the second electrode tab 12 of the electrode assembly 300 through the second current collector plate 50, thereby having a second polarity. Therefore, the battery terminal 60 can function as the second electrode terminal of the cylindrical battery 1 according to an embodiment of the present invention. In addition, in the cylindrical battery 1 according to one embodiment of the present invention, a substantially flat surface formed on the closed side of the battery housing 20 having a first polarity can function as the first electrode terminal T1. Referring to Figure 11, a busbar U is connected to the second electrode terminal T2 and the first electrode terminal T1, respectively, of the cylindrical battery 1 according to an embodiment of the present invention. In order to ensure a sufficient coupling area for coupling with the busbar U at each of the second electrode terminal T2 and the first electrode terminal T1, the width D1 of the region of the second electrode terminal T2 that is exposed to the outside of the battery housing 20 can be set to about 10% to 60% of the width D2 of the first electrode terminal T1, i.e., the upper surface of the battery housing 20.

[0194] Referring to Figures 12, 13, and 15, the insulator S may be provided between the second current collector plate 50 and the inner surface of the battery housing 20. The insulator S prevents contact between the second current collector plate 50 and the battery housing 20. The insulator S covers the upper surface of the second current collector plate 50 and the peripheral edge of the upper end of the electrode assembly 300. This prevents the plain outer surface of the electrode assembly 300 from contacting the inner surface of the battery housing 20, which has opposite polarity, and causing a short circuit. The insulator S may also be interposed between the upper end of the outer surface of the electrode assembly 300 and the inner surface of the battery housing 20. This is to prevent contact between the second electrode tab 12, which extends toward the closing portion of the battery housing 20, and the inner surface of the battery housing 20.

[0195] When the cylindrical battery 1 according to an embodiment of the present invention is equipped with an insulator S, the battery terminals 60 pass through the insulator S and are connected to the second current collector plate 50. In order to allow the battery terminals 60 to pass through in this way, the insulator S may be equipped with an opening formed at a position corresponding to the terminal connection portion 53 of the second current collector plate 50.

[0196] Referring to Figure 19, the first current collector plate 30 may be coupled to the lower part of the electrode assembly 300. The first current collector plate 30 is made of a conductive metallic material and is coupled to the first electrode tab 11. The first current collector plate 30 is also electrically connected to the battery housing 20. The first current collector plate 30 may be fixed by having its peripheral region interposed between the inner surface of the battery housing 20 and the sealing gasket G1. In this case, the first current collector plate 30 may be welded onto the mounting surface formed by the beading portion 21 of the battery housing 20.

[0197] Referring to Figure 14, the first current collector plate 30 can be bonded to a bonding surface formed by bending the end of the first electrode tab 11 in a direction parallel to the first current collector plate 30. The bending direction of the first electrode tab 11 may be, for example, toward the winding central hole H1 of the electrode assembly 300. When the first electrode tab 11 has such a bent form, the space occupied by the first electrode tab 11 is reduced, which can improve the energy density. In addition, it can improve the bonding force between the first electrode tab 11 and the first current collector plate 30 and reduce resistance.

[0198] Preferably, the cylindrical battery may be a cylindrical battery in which the form factor ratio (defined as the ratio of the diameter of the cylindrical battery to its height, i.e., the ratio of height (H) to relative diameter (Φ)) is greater than about 0.4.

[0199] Here, form factor refers to a value indicating the diameter and height of a cylindrical battery. A cylindrical battery according to one 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 numerical value indicating the form factor, the first two digits indicate the diameter of the battery, the next two digits indicate the height of the battery, and the last digit 0 indicates that the cross-section of the battery is circular.

[0200] A battery according to one embodiment of the present invention may be a cylindrical battery that is substantially cylindrical in shape, with a diameter of approximately 46 mm, a height of approximately 110 mm, and a form factor ratio of approximately 0.418.

[0201] A battery according to another embodiment may be a cylindrical battery that is substantially cylindrical in shape, with a diameter of approximately 48 mm, a height of approximately 75 mm, and a form factor ratio of approximately 0.640.

[0202] Furthermore, a battery according to another embodiment may be a cylindrical battery that is substantially cylindrical in shape, with a diameter of approximately 48 mm, a height of approximately 110 mm, and a form factor ratio of approximately 0.418.

[0203] Furthermore, a battery according to another embodiment may be a cylindrical battery that is substantially cylindrical in shape, with a diameter of approximately 48 mm, a height of approximately 80 mm, and a form factor ratio of approximately 0.600.

[0204] Furthermore, another embodiment of the battery may be a cylindrical battery that is substantially cylindrical in shape, with a diameter of approximately 46 mm, a height of approximately 80 mm, and a form factor ratio of approximately 0.575.

[0205] Traditionally, batteries with a form factor ratio of approximately 0.4 or less have been used. Specifically, conventionally, 18650 batteries and 21700 batteries have been used. For example, an 18650 battery has a diameter of approximately 18mm, a height of approximately 65mm, and a form factor ratio of approximately 0.277. For a 21700 battery, the diameter is approximately 21mm, the height is approximately 70mm, and a form factor ratio of approximately 0.300.

[0206] Referring to Figure 23, a battery pack 3 according to one embodiment of the present invention includes a cylindrical battery 1 according to one embodiment of the present invention as described above. For illustrative purposes, components such as busbars for electrical connections, cooling units, and power terminals are not shown.

[0207] Referring to Figure 24, the automobile 5 according to one embodiment of the present invention may be, for example, an electric vehicle, a hybrid vehicle, or a plug-in hybrid vehicle, and includes a battery pack 3 according to one embodiment of the present invention. The automobile 5 includes four-wheeled vehicles and two-wheeled vehicles. The automobile 5 operates by receiving power from the battery pack 3 according to one embodiment of the present invention.

[0208] The following describes an embodiment of the positive electrode active material used in a cylindrical battery according to one embodiment of the present invention.

[0209] In embodiments, "primary particle" refers to a particle unit that, when observed at a field of view of 5,000x to 20,000x using a scanning electron microscope (SEM) or electron backscatter diffraction (EBSD) pattern analyzer, does not appear to have a grain boundary. "Average particle size of primary particles" refers to the arithmetic mean calculated after measuring the particle sizes of primary particles observed in SEM or EBSD images.

[0210] A "secondary particle" is a particle formed by the aggregation of multiple primary particles. In this invention, in order to distinguish it from conventional secondary particles formed by the aggregation of tens to hundreds of primary particles, secondary particles formed by the aggregation of 10 or fewer primary particles will be referred to as pseudo-single particles.

[0211] In this 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 (77K) using Belsorp-mini II manufactured by Bel Corporation of Japan.

[0212] In the present invention, "D min "D 50 " and "D max " is the particle size value of the volume cumulative distribution of the positive electrode active material measured using laser diffraction. Specifically, D min D is the smallest particle size in the volume cumulative distribution. 50 D is the particle size when the cumulative volume is 50%. max This is the maximum particle size in the volume cumulative distribution. When the positive electrode active material is a single particle, D 50 This refers to the average particle size of the primary particles. Also, if the positive electrode active material is a pseudo-single particle, D 50 This refers to the average particle size of particles formed by the aggregation of primary particles.

[0213] The particle size value of the volume cumulative distribution can be measured, for example, after 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.

[0214] In the present invention, "consisting essentially of A" means including the A component and any component not mentioned that does not substantially affect the basic and novel features of the present invention. The basic and novel features of the present invention include at least one of minimizing particle cracking during battery manufacturing, minimizing the gas generated by such particle cracking, and minimizing the occurrence of internal cracks. A person of ordinary skill in the art can recognize the physical effects of such characteristics.

[0215] As a result of repeated research to develop a positive electrode for an electrochemical device and an electrochemical device including the same, which are excellent in safety while achieving a high capacity, the inventors have confirmed that when a positive electrode active material in the form of a single particle composed of one primary particle or an aggregate of 10 or fewer primary particles (pseudo-single particle form) is used alone as the positive electrode active material, the safety of a large cylindrical battery can be improved epochally.

[0216] According to one form, the positive electrode includes a positive electrode current collector and a positive electrode active material layer formed on at least one side surface of the positive electrode current collector. The positive electrode active material layer may include a positive electrode active material and optionally may include a conductive material and / or a binder.

[0217] 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-like positive electrode current collector. The positive electrode active material layer may include a positive electrode active material and a binder.

[0218] Specifically, the positive electrode can be manufactured by applying a positive electrode slurry, prepared by dispersing a positive electrode active material, conductive material, and binder in a solvent such as dimethyl sulfoxide (DMSO), isopropyl alcohol, N-methylpyrrolidone (NMP), acetone, or water, to one or both sides of a long sheet-like positive electrode current collector, removing the solvent from the positive electrode slurry through a drying process, and then rolling it. Alternatively, a positive electrode including a plain area (uncoated area) can be manufactured by not applying the positive electrode slurry to a part of the positive electrode current collector, for example, one end of the positive electrode current collector.

[0219] In other embodiments, the positive electrode active material includes single-particle active material particles. In one embodiment, the single-particle active material particles may be present in an amount of 90 wt% or more, 95 wt% or more, 98 wt% or more, or 99 wt% or more relative to 100 wt% of the positive electrode active material. In a specific embodiment, the positive electrode active material may consist solely of the single-particle active material particles.

[0220] In this specification, the single-particle active material particles refer to single particles, pseudo-single particles, or all of the above. A single particle is a particle consisting of one primary particle, and a pseudo-single particle is an aggregate of 10 or fewer primary particles.

[0221] Conventionally, lithium batteries generally use spherical secondary particles, which are aggregates of tens to hundreds of primary particles, as the positive electrode active material. However, with positive electrode active materials in this form of secondary particles, the primary particles tend to separate and fall off during the rolling process in manufacturing the positive electrode, leading to particle cracking. This can cause cracks to form inside the particles during the charging and discharging process. When particle cracking or internal cracking occurs in the positive electrode active material, the contact area with the electrolyte increases, leading to increased gas generation due to side reactions with the electrolyte. Increased gas generation inside a cylindrical battery increases the internal pressure, posing a risk of the battery exploding. In particular, when the volume of a cylindrical battery is increased, the amount of active material inside the battery increases, which significantly increases gas generation, further increasing the risk of battery ignition and / or explosion.

[0222] On the other hand, single-particle active material particles, which consist of a single primary particle or a pseudo-single-particle form in which 10 or fewer primary particles are aggregated, have higher particle strength compared to conventional cathode active materials with secondary particle forms in which tens to hundreds of primary particles are aggregated, resulting in almost no 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 less change due to volume expansion and contraction of the primary particles during charging and discharging, which significantly reduces the occurrence of cracks inside the particle.

[0223] Therefore, when using single-particle active material particles as in one embodiment of the present invention, the amount of gas generated due to particle cracking and internal cracking can be significantly reduced. This enables superior safety when applied to large cylindrical batteries.

[0224] On the other hand, the single particles and / or pseudo-single particles are preferably included in an amount of 95 wt% to 100 wt%, more 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 total positive electrode active material contained in the positive electrode.

[0225] When the content of single particles and / or pseudo-single particles satisfies the above range, sufficient safety can be obtained when applied to large batteries. This is because if the amount of positive electrode active material in the form of secondary particles exceeds 5 wt% of the total positive electrode active material, the fine powder generated from the secondary particles during electrode manufacturing and charging / discharging increases side reactions with the electrolyte, reducing the effect of suppressing gas generation, and thus reducing the effect of improving stability when applied to large batteries.

[0226] On the other hand, a positive electrode active material containing single particles and / or pseudo-single particles according to one embodiment of the present invention is D min The diameter may be 1.0 μm or larger, 1.1 μm or larger, 1.15 μm or larger, 1.2 μm or larger, 1.25 μm or larger, 1.3 μm or larger, or 1.5 μm or larger. D of the positive electrode active material minIf the particle size is less than 1.0 μm, the linear pressure increases during the positive electrode rolling process, making particle cracking more likely. This reduces thermal stability, making it impossible to ensure sufficient thermal stability when applied to large cylindrical batteries.

[0227] On the other hand, considering the resistance and output characteristics, the D of the positive electrode active material min This can be 3 μm or less, 2.5 μm or less, or 2 μm or less. min If the value is too large, the lithium ion diffusion distance within the particle increases, which may lead to a decrease in resistance and power characteristics.

[0228] For example, the D of the positive electrode active material min The particle size can be 1.0 μm to 3 μm, 1.0 μm to 2.5 μm, or 1.3 μm to 2.0 μm.

[0229] On the other hand, the positive electrode active material is D 50 The particle size can 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.

[0230] Single-particle and / or pseudo-single-particle positive electrode active materials have fewer interfaces between primary particles that serve as diffusion pathways for lithium ions within the particle. This results in reduced lithium mobility compared to secondary-particle positive electrode active materials, leading to increased resistance. This increase in resistance becomes more pronounced as the particle size increases, and this increased resistance negatively impacts capacitance and power characteristics. Therefore, the D of positive electrode active materials is a problem. 50 By adjusting the particle size to 5 μm or less, the lithium ion diffusion distance within the positive electrode active material particles can be minimized, thereby suppressing the increase in resistance.

[0231] Furthermore, the positive electrode active material is D max The diameter may be 12 μm to 17 μm, preferably 12 μm to 16 μm, and more preferably 12 μm to 15 μm. D of the positive electrode active material max If the above range is satisfied, the resistance and capacitance characteristics will be even better. D of the positive electrode active material maxIf the value is too large, aggregation may occur between individual particles, and the lithium migration path within the aggregated particles will become longer, reducing lithium mobility and potentially increasing resistance. On the other hand, the D of the positive electrode active material max If it is too small, it means that excessive crushing has occurred, and excessive crushing has caused D min Because the particle size can become smaller than 1 μm, particle cracking may be induced during rolling, potentially leading to a decrease in thermal stability.

[0232] On the other hand, the positive electrode active material may have a particle size distribution (PSD) of 3 or less, preferably 2 to 3, and more preferably 2.3 to 3, as represented by the following formula 1.

[0233] [Formula 1] Particle size distribution (PSD)=(D max -D min ) / D 50

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

[0235] On the other hand, the positive electrode active material may have an average particle size of primary particles 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 particle size of the primary particles satisfies the above range, it is possible to form a positive electrode active material in the form of single particles and / or pseudo-single particles with excellent electrochemical properties. If the average particle size of the primary particles is too small, the number of aggregated primary particles forming the positive electrode active material will increase, which may reduce the effect of suppressing particle cracking during rolling. Also, if the average particle size of the primary particles is too large, the lithium diffusion path inside the primary particles will become longer, increasing resistance and potentially reducing the output characteristics.

[0236] In one embodiment of the present invention, the positive electrode active material preferably has a unimodal particle size distribution. Conventionally, in order to improve the electrode density of the positive electrode active material layer, a bimodal positive electrode active material obtained by mixing a large particle size positive electrode active material having a large average particle size and a small particle size positive electrode active material having a small average particle size has been widely used. However, in the case of a positive electrode active material in the form of single particles or pseudo single particles, if the particle size increases, the lithium migration path becomes longer and the resistance increases significantly. Therefore, when using a mixture of large particle size particles, there is a risk that the capacity and output characteristics may deteriorate. Therefore, in the present invention, by using a positive electrode active material having a unimodal distribution, an increase in resistance can be minimized.

[0237] On the other hand, the positive electrode active material may contain a lithium nickel-based oxide. Specifically, it may contain a lithium nickel-based oxide containing Ni at 80 mol% or more based on the total number of moles of transition metals. Preferably, the lithium nickel-based oxide may contain Ni at 80 mol% or more and less than 100 mol%, 82 mol% or more and less than 100 mol%, or 83 mol% or more and less than 100 mol%. When using a lithium nickel-based oxide with a high Ni content as described above, a high capacity can be realized.

[0238] More specifically, the positive electrode active material may contain a lithium nickel-based oxide represented by the following Chemical Formula 1.

[0239] [Chemical Formula 1] Li a Ni b Co c M 1 d M 2 e O2

[0240] In Chemical Formula 1, the M 1 may be Mn, Al, or a combination thereof, and preferably may be Mn, or Mn and Al.

[0241] The M 2is one or more selected from the group consisting of Zr, W, Y, Ba, Ca, Ti, Mg, Ta, and Nb, and may preferably be one or more selected from the group consisting of Zr, Y, Mg and Ti, and more preferably may be Zr, Y or a combination thereof. M 2 The element is not necessarily included, but when included in an appropriate amount, it can play a role in promoting particle growth during firing or improving the stability of the crystal structure.

[0242] Said a represents the molar ratio of lithium in the lithium nickel-based oxide, and can be 0.8 ≦ a ≦ 1.2, 0.85 ≦ a ≦ 1.15, or 0.9 ≦ a ≦ 1.2. When the molar ratio of lithium satisfies the above range, the crystal structure of the lithium nickel-based oxide can be stably formed.

[0243] Said b represents the molar ratio of nickel in the total metal excluding lithium in the lithium nickel-based oxide, and can be 0.8 ≦ b < 1, 0.82 ≦ b < 1, 0.83 ≦ b < 1, 0.85 ≦ b < 1, 0.88 ≦ b < 1, or 0.90 ≦ b < 1. When the molar ratio of nickel satisfies the above range, it can exhibit a high energy density and achieve a high capacity.

[0244] 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.

[0245] Said d represents the molar ratio of the M 1 element in the total metal excluding lithium in the lithium nickel-based oxide, and can be 0 < d < 0.2, 0 < d < 0.18, 0.01 ≦ d ≦ 0.17, 0.01 ≦ d ≦ 0.15, 0.01 ≦ d ≦ 0.12, or 0.01 ≦ d ≦ 0.10. M 1 When the molar ratio of the element satisfies the above range, the structure stability of the positive electrode active material is excellent.

[0246] The aforementioned e is M in the total metal excluding lithium in lithium nickel oxides. 2 This indicates the molar ratio of elements, and can be either 0 ≤ e ≤ 0.1 or 0 ≤ e ≤ 0.05.

[0247] On the other hand, the positive electrode active material according to one embodiment of the present invention may further include, if necessary, a coating layer on the surface of the lithium nickel oxide particles, which contains one or more coating elements selected from the group consisting of Al, Ti, W, B, F, P, Mg, Ni, Co, Fe, Cr, V, Cu, Ca, Zn, Zr, Nb, Mo, Sr, Sb, Bi, Si, and S. Preferably, the coating element may be Al, B, Co, or a combination thereof.

[0248] When a coating layer is present on the surface of lithium nickel oxide particles, the coating layer suppresses contact between the electrolyte and the lithium nickel oxide, thereby reducing the elution of transition metals or gas generation due to side reactions with the electrolyte.

[0249] The positive electrode active material may be present in an amount of 80 wt% to 99 wt%, preferably 85 wt% to 99 wt%, and more preferably 90 wt% to 99 wt%, relative to the total weight of the positive electrode active material layer.

[0250] On the other hand, a variety of positive electrode current collectors used in the art can be used as the positive electrode current collector. For example, the positive electrode current collector can be made of stainless steel, aluminum, nickel, titanium, calcined carbon, or aluminum or stainless steel with a surface treatment of carbon, nickel, titanium, silver, etc. The positive electrode current collector may typically have a thickness of 3 μm to 500 μm, and fine irregularities may be formed on the surface of the positive electrode current collector to enhance the adhesion of the positive electrode active material. The positive electrode current collector can be used in a variety of forms, such as film, sheet, foil, net, porous material, foam, or nonwoven fabric.

[0251] On the other hand, in one embodiment of the present invention, all or part of the single-particle active material particles may have a core-shell structure in which the surface of the particles is covered with a conductive coating layer. The conductive coating layer may cover at least part or all of the particles. The conductive coating layer contains conductive nanomaterials.

[0252] In the case of the aforementioned single-particle active material particles, there is a problem that the electrical conductivity decreases because the resistance is higher and the contact area with the conductive material is smaller compared to conventional secondary-particle positive electrode active materials. If an excessive amount of conductive material is added to improve electrical conductivity, aggregation occurs in the positive electrode slurry, increasing viscosity and causing a problem of reduced coating performance. Therefore, in order to achieve smooth coating performance, it is necessary to reduce the viscosity of the positive electrode slurry by reducing the solid content, but if the solid content in the positive electrode slurry decreases, the active material content decreases, which leads to a problem of reduced capacity characteristics. To solve these problems, the present invention makes it possible to achieve excellent electrical conductivity without adding a separate conductive material to the positive electrode slurry by coating the surface of the single-particle active material particles with a conductive nanomaterial.

[0253] In embodiments of the present invention, when a positive electrode active material is applied in which a conductive nanomaterial is coated on the surface of the single-particle active material particles, the positive electrode active material layer does not need to use a conductive material in the portion excluding the conductive coating layer. In this way, it is not necessary to use an additional conductive material that induces aggregation of the positive electrode slurry, so the viscosity of the positive electrode slurry decreases and the solid content increases, which improves the processability of the electrode coating and the electrode adhesion strength.

[0254] In one embodiment of the present invention, the conductive nanomaterial may be any material that has a nano-size so as to be able to smoothly coat the particles and is conductive, and its type is not particularly limited. For example, the conductive nanomaterial may be a carbon nanotube, a carbon nanoparticle, or the like.

[0255] The conductive nanomaterial may have various forms, such as spherical, flaky, or fibrous.

[0256] On the other hand, the conductive coating layer can be formed by mixing single-particle active material particles, which constitute the core, with conductive nanomaterials, followed by heat treatment. In this case, the mixing can be carried out by solid-phase or liquid-phase mixing.

[0257] In one embodiment of the present invention, the positive electrode active material layer contains flake graphite. When the single-particle active material is used as the positive electrode active material, if 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 allowing the porosity of the electrode to be reduced to a target level. As a result, a battery to which the positive electrode according to one embodiment of the present invention is applied can have improved stability, initial resistance characteristics, and charge / discharge efficiency.

[0258] In one embodiment of the present invention, the flake-like graphite may be present 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.

[0259] When the flake graphite content satisfies the above range, the rolling characteristics of the positive electrode are improved, and excellent electrode density can be achieved. If the flake graphite content is low, the improvement in rolling characteristics is small, and if it is excessive, it may induce an increase in slurry viscosity and a decrease in phase stability, and the bonding with the conductive material may reduce electrode uniformity and increase resistance.

[0260] On the other hand, 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 reduce the current density and decrease the capacity. In this case, the average particle size of the flake graphite can be measured by laser diffraction (ISO 13320).

[0261] Furthermore, the flake-like 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-like graphite satisfies the above range, it has the effect of improving conductivity and lowering electrode resistance.

[0262] Furthermore, the aforementioned flake-like graphite has a density of 2.0 g / cm³. 3 ~2.5g / cm 3 Preferably 2.1 g / cm³ 3 ~2.4g / cm 3 , more preferably 2.2 g / cm³ 3 ~2.3g / cm 3 It is possible.

[0263] On the other hand, 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 decreases. If the porosity is too low, the electrolyte impregnation ability decreases, and lithium deposition may occur due to insufficient electrolyte impregnation. If the porosity is too high, contact between electrodes is poor, resistance increases, energy density decreases, and the effect of capacity improvement is low.

[0264] The porosity value of the positive electrode active material layer can be achieved by i) the positive electrode active material containing single-particle active material particles, and ii) the addition of flake graphite to the positive electrode active material.

[0265] When realizing a high-loading electrode with a relatively high loading amount of positive electrode active material layer, using a positive electrode active material in the form of a single particle or pseudo-single particle, as in one embodiment of the present invention, significantly reduces particle cracking of the active material during rolling compared to conventional secondary particle positive electrode active materials. This reduces damage to the positive electrode current collector (Al foil), allowing rolling at a relatively higher linear pressure, and reducing the porosity of the positive electrode active material layer to the above-mentioned numerical range, thereby increasing the energy density.

[0266] Furthermore, if the positive electrode active material layer contains flake graphite as in one embodiment of the present invention, the flake graphite provides a sliding effect during rolling and can fill the voids in the positive electrode active material layer, thereby reducing the porosity of the positive electrode active material layer to the numerical range described above.

[0267] Furthermore, the positive electrode has a loading amount of 570 mg / 25 cm³. 2 Preferably 600 mg / 25 cm 2 ~800g / 25m 2 More preferably 600 mg / 25 cm 2 ~750mg / 25cm 2 This is possible. Specifically, in the case of a lithium secondary battery according to one embodiment of the present invention, the rolling characteristics of the electrode are improved by applying a positive electrode active material in the form of single particles and / or pseudo-single particles and flake graphite, so that the loading amount of the positive electrode can be secured at a relatively high level, thereby realizing high capacity characteristics.

[0268] In one embodiment of the present invention, the positive electrode active material layer may further contain a conductive material. The conductive material is used to impart conductivity to the electrode and can be used without particular limitations as long as it does not cause a chemical change inside the battery and has electrical conductivity. 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 powders or metal fibers such as copper, nickel, aluminum, and silver; conductive whiskers such as zinc oxide and potassium titanate; conductive metal oxides such as titanium oxide; or conductive polymers such as polyphenylene derivatives, and one of these alone or a mixture of two or more can be used. The conductive material is usually included in an amount of 1 wt% to 30 wt%, preferably 1 wt% to 20 wt%, and more preferably 1 wt% to 10 wt%, relative to the total weight of the positive electrode active material layer.

[0269] In one specific embodiment according to one example of the present invention, the conductive material may include carbon nanotubes.

[0270] In one embodiment of the present invention, the positive electrode active material may include multi-walled carbon nanotubes having a high specific surface area and a small wall number as a conductive material. The multi-walled carbon nanotubes may be included in an amount of 50 wt% or more, 70 wt% or more, 90 wt% or more, or 99 wt% or more 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.

[0271] In one embodiment of the present invention, the multilayer carbon nanotube is 300m 2 / g~500m 2 It has a BET specific surface area of ​​1 / g. To distinguish it from the conventional technology, it is called "novel CNT".

[0272] Conventionally, commonly used carbon nanotubes (conventional CNTs) have a BET specific surface area of ​​300 m². 2 The value is less than / g. A comparison of scanning electron microscope images and physical properties (Figure 27) of the novel CNT used in the present invention (Figure 25) and conventional CNT (Figure 26) is as follows.

[0273] As can be seen from the SEM image, the novel CNT applied to one embodiment of the present invention is of the bundled type and has a multi-wall structure, but has a higher BET and smaller number of layers and diameter compared to conventional CNTs.

[0274] When using a secondary particle form of positive electrode active material, sufficient electrical conductivity can be achieved even when using approximately 0.4 wt% to 0.6 wt% of conventional CNTs. However, in the case of a single particle or pseudo-single particle form of positive electrode active material, the resistance is higher compared to conventional secondary particle form positive electrode active material, and the contact area with the conductive material is smaller, resulting in reduced electrical conductivity. Therefore, the BET specific surface area is 300 m². 2 In order to achieve sufficient electrical conductivity using conventional CNTs with a density of less than 0.9 wt%, the conductive material content must be 0.9 wt% or more.

[0275] Figures 28 to 31 are graphs showing the surface resistance and high-temperature lifetime characteristics according to the ratio of conductive material when single particles or pseudo-single particles are applied as the positive electrode active material.

[0276] The graph shows that when using single particles or pseudo-single particles as the positive electrode active material, it is necessary to increase the amount of conductive material used compared to when using conventional secondary particle-type positive electrode active materials.

[0277] However, if the carbon nanotube content increases to 0.9 wt% or more, aggregation occurs in the cathode slurry, increasing viscosity and thus reducing coating performance. Therefore, in order to achieve smooth coating performance, the solid content in the cathode slurry must be reduced to lower its viscosity. However, reducing the solid content in the cathode slurry leads to a decrease in the active material content, which in turn reduces the capacity characteristics.

[0278] To solve these problems, the inventors conducted extensive research and found that, along with the positive electrode active material which is a single-particle active material, a conductive material with a BET specific surface area of ​​300 m² is available. 2 / g~500m 2 When using carbon nanotubes at a concentration of / g, we confirmed that sufficient electrical conductivity can be ensured even with a relatively small amount of carbon nanotubes, and that this allows the slurry viscosity to be kept low even when the solid content of the cathode slurry is formed to a high level of approximately 70wt% to 80wt%.

[0279] Specifically, the carbon nanotube used in the present invention has a BET specific surface area of ​​300 m². 2 / g~500m 2 / g, preferably 300m 2 / g~450m 2 This could be a multi-walled carbon nanotube with a specific surface area of ​​ / g. If the BET specific surface area satisfies the above range, sufficient electrical conductivity can be ensured even with a small amount of carbon nanotube.

[0280] Furthermore, the carbon nanotube may be a multi-walled carbon nanotube having 2 to 8 wall numbers, preferably 2 to 6, and more preferably 3 to 6.

[0281] Furthermore, 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.

[0282] The carbon nanotubes may be present 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%, relative to the total weight of the positive electrode active material layer. When the carbon nanotube content satisfies the above range, sufficient electrical conductivity can be achieved, and a high solid content can be maintained in the positive electrode slurry. This allows for the formation of a high content of positive electrode active material in the positive electrode active material layer, thereby achieving excellent capacity characteristics.

[0283] The table shown in Figure 32 shows that the BET specific surface area is 300 m². 2 / g~500m 2 When carbon nanotubes (novel CNTs) with a value of / g are applied and the BET specific surface area is 200m² 2 / g or more 300m 2 This 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) with a solid content of less than 1g / g are used. The table shows that when the new CNTs are used, the viscosity is lower even when the solid content of the positive electrode slurry is higher compared to conventional CNTs, and the electrical conductivity is also superior.

[0284] The binder plays a role in improving the adhesion between positive electrode active material particles and the adhesion between the positive electrode active material and the positive electrode current collector. Specific examples include polyvinylidene fluoride (PVDF), polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HFP), polyvinyl alcohol, polyacrylonitrile, carboxymethylcellulose (CMC), starch, hydroxypropylcellulose, regenerated cellulose, polyvinylpyrrolidone, polytetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene monomer (EPDM) rubber, sulfonated EPDM, styrene-butadiene rubber (SBR), fluororubber, or various copolymers thereof, and one of these alone or a mixture of two or more may be used. 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%, based on the total weight of the positive electrode active material layer.

[0285] 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, the positive electrode having the constituent features described above.

[0286] The electrode assemblies can be formed by stacking, for example, a separation membrane interposed between the negative electrode and the positive electrode to form a stacked or stacked / folded structure, or by winding them up to form a jelly roll structure. When a jelly roll structure is formed, a separation membrane may be further arranged on the outside to prevent contact between the negative electrode and the positive electrode.

[0287] 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.

[0288] Specifically, the negative electrode can be manufactured by applying a negative electrode slurry, in which a negative electrode active material, a conductive material, and a binder are dispersed in a solvent such as dimethyl sulfoxide (DMSO), isopropyl alcohol, N-methylpyrrolidone (NMP), acetone, water, etc., onto one or both surfaces of a long sheet-shaped negative electrode current collector, and after removing the solvent of the negative electrode slurry through a drying process, rolling it. When applying the negative electrode slurry, a negative electrode including a plain part can be manufactured by a method of not applying the negative electrode slurry to a partial area of the negative electrode current collector, for example, one end of the negative electrode current collector.

[0289] As the negative electrode active material, a compound capable of reversible insertion (intercalation) and deintercalation of lithium can be used. Specific examples include carbonaceous materials such as artificial graphite, natural graphite, graphitized carbon fiber, and amorphous carbon; silicon-based materials such as Si, Si-Me alloy (where Me is one or more selected from the group consisting of Al, Sn, Mg, Cu, Fe, Pb, Zn, Mn, Cr, Ti, and Ni), SiO y (where 0 < y < 2), Si-C composites, etc.; lithium metal thin films; metal materials capable of alloying with lithium such as Sn, Al, etc. Among these, any one or a mixture of two or more of them can be used.

[0290] In one embodiment of the present invention, the negative electrode may include a silicon-based negative electrode active material. The silicon-based negative electrode active material can 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, and preferably SiO y (where 0 < y < 2). Since the silicon-based negative electrode active material has a high theoretical capacity, when the silicon-based negative electrode active material is included, the capacity characteristics can be improved.

[0291] The silicon-based negative electrode active material may be doped with M b metal, and at this time, the M bThe metal can be a Group 1 metal element or a Group 2 metal element, specifically, it can be Li, Mg, etc. Specifically, the silicon-based negative electrode active material is M b Si doped with metal, SiO y (where 0 < y < 2), and can be a Si-C composite, etc. In the case of a metal-doped silicon-based negative electrode active material, although the active material capacity decreases somewhat depending on the doping element, it has high efficiency, so a high energy density can be realized.

[0292] Figure 49 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.

[0293] In Figure 49, low-efficiency SiO is undoped SiO, and ultra-high-efficiency SiO means Mg / Li-doped SiO. From Figure 49, 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 becomes more excellent as the ratio of the doped silicon-based negative electrode active material in the silicon-based negative electrode active material increases.

[0294] The silicon-based negative electrode active material may further include a carbon coating layer on the surface of the particles. At this time, the carbon coating amount 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 can be formed through methods such as dry coating, wet coating, chemical vapor deposition (CVD), physical vapor deposition (PVD), and atomic layer deposition (ALD).

[0295] 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%.

[0296] In another embodiment of the present invention, the D of the silicon-based negative electrode active material 50It can be 3 μm to 8 μm, D min ~D max This can fall within the range of 0.5 μm to 30 μm.

[0297] The anode may further include a carbon-based anode active material as an anode active material, if necessary. The carbon-based anode active material may be, but is not limited to, artificial graphite, natural graphite, graphitized carbon fiber, amorphous carbon, soft carbon, hard carbon, etc.

[0298] When a mixture of silicon-based and carbon-based anode active materials is used as the anode active material, the mixing ratio of the silicon-based and carbon-based anode active materials may be 1:99 to 20:80 by weight, preferably 1:99 to 15:85, and more preferably 1:99 to 10:90.

[0299] The negative electrode active material may be present in an amount of 80 wt% to 99 wt%, preferably 85 wt% to 99 wt%, and more preferably 90 wt% to 99 wt%, relative to the total weight of the negative electrode active material layer.

[0300] If necessary, the negative electrode active material may further include one or more selected from lithium metal and metallic substances that can alloy with lithium, such as Sn and Al.

[0301] As the negative electrode current collector, a negative electrode current collector commonly used in the art may be used, for example, copper, stainless steel, aluminum, nickel, titanium, calcined carbon, copper or stainless steel surface-treated with carbon, nickel, titanium, silver, etc., or aluminum-cadmium alloy. The negative electrode current collector may typically have a thickness of 3 μm to 500 μm, and, similar to the positive electrode current collector, fine irregularities may be formed on the surface of the current collector to strengthen the bonding force of the negative electrode active material. For example, the negative electrode current collector can be used in a variety of forms such as film, sheet, foil, net, porous material, foam, or nonwoven fabric.

[0302] The conductive material is used to impart conductivity to the negative electrode and can be used without particular limitations as long as it does not cause chemical changes inside the battery and has electrical conductivity. 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 metal fibers such as copper, nickel, aluminum, and silver; conductive whiskers such as zinc oxide and potassium titanate; conductive metal oxides such as titanium oxide; or conductive polymers such as polyphenylene derivatives. One of these may be used alone or in mixtures of two or more. The conductive material is usually included in an amount of 1 wt% to 30 wt%, preferably 1 wt% to 20 wt%, and more preferably 1 wt% to 10 wt%, relative to the total weight of the negative electrode active material layer.

[0303] The binder plays a role in improving the adhesion between negative electrode active material particles and the adhesion between the negative electrode active material and the negative electrode current collector. Specific examples of binders include polyvinylidene fluoride (PVDF), polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HFP), polyvinyl alcohol, polyacrylonitrile, carboxymethylcellulose (CMC), starch, hydroxypropylcellulose, regenerated cellulose, polyvinylpyrrolidone, polytetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene monomer (EPDM) rubber, sulfonated EPDM, styrene-butadiene rubber (SBR), fluororubber, or various copolymers thereof, and one or more of these may be used. 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%, relative to the total weight of the negative electrode active material layer.

[0304] The electrode assembly further includes a separation membrane, which is arranged within the electrode assembly so as to be interposed between the negative electrode and the positive electrode. The separation membrane separates the negative electrode and the positive electrode and provides a passage for lithium ions to move, and can be used without particular limitations as long as it is the type of membrane normally used as a separator in lithium batteries.

[0305] As the separation membrane, porous polymer films, such as porous polymer films made from polyolefin polymers such as ethylene homopolymer, propylene homopolymer, ethylene / butene copolymer, ethylene / hexene copolymer, and ethylene / methacrylate copolymer, or laminated structures of two or more layers thereof, may be used. Alternatively, ordinary porous nonwoven fabrics, such as nonwoven fabrics made of high-melting-point glass fibers or polyethylene terephthalate fibers, may be used. Furthermore, to ensure heat resistance or mechanical strength, a coated separation membrane containing ceramic components or polymeric substances may be used.

[0306] Yet another embodiment of the present invention relates to a battery including the electrode assembly. The battery comprises an electrode assembly and an electrolyte housed together in a battery case. The battery case can be any suitable one that is commonly used in the art, such as a pouch type or a metal can type, and is not particularly limited.

[0307] The electrolyte used in this invention can be a variety of electrolytes usable in lithium batteries, such as organic liquid electrolytes, inorganic liquid electrolytes, solid polymer electrolytes, gel-type polymer electrolytes, solid inorganic electrolytes, and molten inorganic electrolytes, and the type is not particularly limited.

[0308] Specifically, the electrolyte may include an organic solvent and a lithium salt.

[0309] The aforementioned organic solvent can be used without particular limitations, as long as it can act as a medium through which ions involved in the electrochemical reaction of the battery can move. Specifically, the organic solvents that can be used include ester solvents such as methyl acetate, ethyl acetate, γ-butyrolactone, and ε-caprolactone; ether solvents such as dibutyl ether or tetrahydrofuran; ketone solvents such as cyclohexanone; aromatic hydrocarbon solvents such as benzene, 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 (where R is a C2-C20 linear, branched, or cyclic hydrocarbon group, and may include a double-bonded aromatic ring or ether bond); amides such as dimethylformamide; dioxolanes such as 1,3-dioxolane; or sulfolanes. Among these, carbonate-based solvents are preferred, and more preferably are mixtures of cyclic carbonates (e.g., ethylene carbonate or propylene carbonate) having high ionic conductivity and high dielectric constant that can improve the charge and discharge performance of batteries, and low-viscosity linear carbonate compounds (e.g., ethyl methyl carbonate, dimethyl carbonate or diethyl carbonate).

[0310] The lithium salt can be used without particular limitation as long as it is a compound capable of providing lithium ions for use in lithium batteries. Specifically, the lithium salt can be LiPF6, LiClO4, LiAsF6, LiBF4, LiSbF6, LiAlO4, LiAlCl4, LiCF3SO3, LiC4F9SO3, LiN(C2F5SO3)2, LiN(C2F5SO2)2, LiN(CF3SO2)2, LiCl, LiI, or LiB(C2O4)2, etc. The concentration of the lithium salt may be in the range of 0.1 to 5.0 M, preferably 0.1 M to 3.0 M. If the concentration of the lithium salt falls within the above range, the electrolyte will have appropriate conductivity and viscosity, exhibiting excellent electrolyte performance and allowing lithium ions to move effectively.

[0311] The electrolyte may further contain additives in addition to the electrolyte components described above, for the purpose of improving battery life characteristics, suppressing battery capacity reduction, and improving battery discharge capacity. For example, the additives may be, but are not limited to, haloalkylene carbonate compounds such as difluoroethylene carbonate, pyridine, triethyl phosphite, triethanolamine, cyclic ethers, ethylenediamine, n-glyme, hexamethyl phosphate triamide, nitrobenzene derivatives, sulfur, quinone imine dyes, N-substituted oxazolidinone, N,N-substituted imidazolidine, ethylene glycol dialkyl ether, ammonium salts, pyrrole, 2-methoxyethanol, or aluminum trichloride, either 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%, relative to the total weight of the electrolyte.

[0312] In yet another embodiment of the present invention, the positive electrode may include a loading reduction region where the loading amount of positive electrode active material is less than in the adjacent region. Having such a structure in the positive electrode allows for an increase in the area of ​​positive electrode active material without the concern of lithium deposition. This improves the energy density of the electrode assembly.

[0313] In recent years, development has been progressing in the direction of increasing battery size in order to achieve high energy density and reduce costs. As the energy increases with battery size, the resistance per battery must decrease. To reduce resistance, it is possible to use a method in which the current collector of the electrode is used as the electrode tab, rather than attaching electrode tabs to the electrode. In this case, due to the characteristics of the electrode manufacturing process in which electrode slurry is applied to the electrode current collector, a portion where the loading amount decreases occurs at the boundary between the negative electrode active material portion to which the negative electrode slurry is applied and the negative electrode current collector. Considering the N / P ratio, there is a risk that metallic lithium will be deposited on the positive electrode active material portion facing the portion where the loading amount decreases. Here, the N / P ratio is the value obtained by dividing the capacity of the negative electrode, calculated based on the capacity per unit area and mass of the negative electrode, by the capacity of the positive electrode, obtained based on the capacity per unit area and mass of the positive electrode, and it generally has a value of 1 or more. In other words, the capacity of the negative electrode is manufactured to be larger. For reference, if the N / P ratio is not 1, metallic lithium is likely to precipitate during charging and discharging, which rapidly degrades the safety of the battery during high-rate charging and discharging. In other words, the N / P ratio has a significant impact on the safety and capacity of the battery. Due to this risk of metallic lithium deposition, the positive electrode active material cannot be positioned in the positive electrode portion facing the portion where the loading amount of the negative electrode decreases. This prevents the battery's energy density from being increased. Therefore, this invention improves energy density by increasing the length of the positive electrode active material portion.

[0314] Figure 37 shows an electrode assembly according to one embodiment of the present invention, and Figure 38 is a cross-sectional view taken along the line A-A' in Figure 37.

[0315] Referring to Figures 37 and 38, an electrode assembly 300 according to one embodiment of the present invention includes a negative electrode 400, a positive electrode 500, and a separation membrane 600. The separation membrane 600 is located between the negative electrode 400 and the positive electrode 500. The negative electrode 400, the positive electrode 500, and the separation membrane 600 are wound together to form a 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 separation membrane 600. Furthermore, when the jelly roll structure 300S is formed, it is preferable to further arrange the separation membrane 600 on the outside to prevent the negative electrode 400 and the positive electrode 500 from coming into contact.

[0316] The negative electrode 400 includes a negative electrode current collector 410 and a negative electrode active material portion 420 formed by coating the negative electrode current collector 410 with negative electrode active material. In particular, as shown in the figure, the negative electrode active material portion 420 can be formed by coating both sides of the negative electrode current collector 410 with negative electrode active material. In addition, a negative electrode blank portion 430 on the negative electrode current collector 410, on which the negative electrode active material is not coated, extends in the first direction d1. The negative electrode blank portion 430 extends along one end of the wound negative electrode 400. Furthermore, the negative electrode blank portion 430 extends longer than the separation film 600 in the first direction d1. As a result, the negative electrode blank portion 430 can be exposed at one end of the jelly roll structure 300S in the first direction.

[0317] The positive electrode 500 includes a positive electrode current collector 510 and a positive electrode active material portion 520 formed by coating the positive electrode active material on the positive electrode current collector 510. In particular, as shown in the figure, the positive electrode active material portion 520 can be formed by coating both sides of the positive electrode current collector 510 with positive electrode active material. In addition, a blank positive electrode portion 530, on the positive electrode current collector 510, where positive electrode active material is not coated, extends in the second direction d2. The blank positive electrode portion 530 extends along one end of the winding positive electrode 500. Furthermore, the blank positive electrode portion 530 extends longer than the separation film 600 in the second direction d2. As a result, the blank positive electrode portion 530 can be exposed at one end of the jelly roll structure 300S in the second direction.

[0318] Here, the first direction d1 and the second direction d2 are opposite directions. Also, the first direction d1 and the second direction d2 may be parallel to the height direction of the jelly roll structure 300S.

[0319] The electrode assembly 300 according to this embodiment does not have separate electrode tabs attached, but rather utilizes the blank negative portion 430 of the negative electrode current collector 410 and the blank positive portion 530 of the positive electrode current collector 510 themselves as electrode tabs to reduce resistance.

[0320] Although not shown in the figures, the negative electrode blank portion 430 and / or the positive electrode blank portion 530 may have substantially the same structure as the blank portion of the electrode described above.

[0321] In one embodiment, the positive electrode active material portion 520 includes a loading reduction portion 500D in which the loading amount of positive electrode active material is less than that of the adjacent region, and the loading reduction portion 500D is located at one end of the positive electrode 500 in a first direction d1. More specifically, the loading reduction portion 500D may have a gradually decreasing loading amount of positive electrode active material toward the first direction d1.

[0322] Here, loading amount refers to the amount of active material coated per unit area. In areas with a high loading amount, a large amount of negative electrode active material or positive electrode active material is coated per unit area, which can result in a relatively thicker negative electrode active material portion or positive electrode active material portion. In areas with a low loading amount, a small amount of negative electrode active material or positive electrode active material is coated per unit area, which can result in a relatively thinner negative electrode active material portion or positive electrode active material portion.

[0323] The active material portion is formed by applying a slurry containing the active material, but in this process, a boundary area may be formed between the plain area and the active material portion where the loading amount gradually decreases.

[0324] Specifically, the negative electrode active material portion 420 may include a negative electrode boundary portion 420B that forms a boundary between the negative electrode active material portion 420 and the negative electrode blank portion 430. The loading amount of the negative electrode boundary portion 420B may gradually decrease in the direction in which the negative electrode blank portion 430 is located.

[0325] 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 blank portion 530. The loading amount of the positive electrode boundary portion 520B may gradually decrease in the direction in which the positive electrode blank portion 530 is located.

[0326] The negative electrode boundary 420B and positive electrode boundary 520B, where the loading amount gradually decreases, occur naturally 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.

[0327] In this case, using the direction perpendicular to the second direction d2 as a reference, the amount of positive electrode active material in the region corresponding to the positive electrode boundary 520B becomes less than the amount of negative electrode active material. As a result, the N / P ratio becomes greater than 1, so problems such as the deposition of metallic lithium do not occur.

[0328] However, there is a problem in the region corresponding to the negative electrode boundary 420B. Using the direction perpendicular to the first direction d1 as a reference, the amount of negative electrode active material in the region corresponding to the negative electrode boundary 420B is less than the amount of positive electrode active material. As a result, the N / P ratio becomes less than 1, which may lead to the deposition of metallic lithium.

[0329] Therefore, in this embodiment, a loading reduction portion 500D is provided on the positive electrode 500, and the negative electrode active material portion 420 is positioned in a portion corresponding to the loading reduction portion 500D, with reference to a direction perpendicular to the first direction d1. More specifically, the negative electrode boundary portion 420B may be positioned in a portion corresponding to the loading reduction portion 500D, with reference to a direction perpendicular to the first direction d1.

[0330] By providing a loading reduction section 500D at a position corresponding to the negative electrode boundary section 420B where the loading amount gradually decreases, where the loading amount of positive electrode active material is less than in the adjacent region, the area coated with positive electrode active material can be increased without worrying about lithium deposition. In particular, the loading reduction section 500D may have a shape in which the loading amount of positive electrode active material gradually decreases toward the first direction d1, corresponding to the shape of the negative electrode boundary section 420B where the loading amount gradually decreases toward the negative electrode blank section 430. Therefore, the N / P ratio between the negative electrode 400 and the positive electrode 500 in the region where the negative electrode boundary section 420B is formed can be maintained at a high level, and lithium deposition can be prevented.

[0331] The method for manufacturing an electrode assembly according to one embodiment of the present invention will be described in detail below with reference to Figures 39 to 44.

[0332] Figures 39 and 40 illustrate the process of manufacturing a negative electrode according to one embodiment of the present invention. Specifically, Figure 39 is a top view of the negative electrode sheet, and Figure 40 is a front view of the negative electrode sheet of Figure 39.

[0333] Referring to Figures 39 and 40, a method for manufacturing an electrode assembly according to one embodiment of the present invention includes the step of manufacturing a negative electrode sheet 400S such that negative electrode active material portions 420, on which negative electrode active material is coated, and negative electrode plain portions 430, on which negative electrode active material is not coated, are alternately positioned on a negative electrode current collector 410.

[0334] Specifically, the negative electrode active material can be applied so as to extend in a third direction d3 to form the negative electrode active material portion 420. Furthermore, by separating the applied areas along a fourth direction d4 perpendicular to the third direction d3, multiple negative electrode active material portions 420 can be positioned at intervals along the fourth direction d4. That is, the application process can be carried out so that the negative electrode blank portions 430 are positioned between multiple negative electrode active material portions 420.

[0335] Here, the third direction d3 and the fourth direction d4 are directions used for explanation with reference to the negative electrode sheet 400S, and are unrelated to the first direction d1 and the second direction d2 in the jelly roll structure 300S described above.

[0336] The process may then include the step of manufacturing the negative electrode 400 by slitting the negative electrode blank portion 430 and the negative electrode active material portion 420. Figure 41 is a perspective view showing a negative electrode according to one embodiment of the present invention.

[0337] Referring to Figures 39 to 41, slitting can be performed on the plain negative electrode portion 430 and the negative electrode active material portion 420 in a direction parallel to the third direction d3, as shown by the dotted lines in Figures 39 and 40. This allows for the production of multiple negative electrodes 400 as shown in Figure 41 from the negative electrode sheet 400S. That is, the negative electrode 400 in Figure 41 corresponds to one of multiple negative electrodes produced by slitting the negative electrode sheet 400S in Figures 39 and 40. By slitting the plain negative electrode portion 430 and the negative electrode active material portion 420 in the negative electrode sheet 400S, a negative electrode 400 can be produced in which the plain negative electrode portion 430 extends to one side.

[0338] When forming the negative electrode active material portion 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 portion 420B can be formed at the boundary between the negative electrode active material portion 420 and the negative electrode blank portion 430, where the loading amount gradually decreases in the direction of the negative electrode blank portion 430.

[0339] Figures 42 and 43 illustrate the process of manufacturing a positive electrode according to one embodiment of the present invention. Specifically, Figure 42 is a top view of the positive electrode sheet, and Figure 43 is a front view of the positive electrode sheet of Figure 42.

[0340] Referring to Figures 42 and 43, a method for manufacturing an electrode assembly according to one embodiment of the present invention includes the step of manufacturing a positive electrode sheet 500S such that positive electrode active material portions 520, on which positive electrode active material is coated, and positive electrode plain portions 530, on which positive electrode active material is not coated, are alternately positioned on a positive electrode current collector 510.

[0341] Specifically, the positive electrode active material can be applied so as to extend in a third direction d3 to form the positive electrode active material portion 520. Furthermore, by adjusting the application interval along a fourth direction d4 perpendicular to the third direction d3, multiple positive electrode active material portions 520 can be positioned at a distance from each other. In other words, the application process can be carried out so that the blank positive electrode portion 530 is positioned between multiple positive electrode active material portions 520.

[0342] Here, the third direction d3 and the fourth direction d4 are directions used for explanation with respect to the positive electrode sheet 500S, and are unrelated to the first direction d1 and the second direction d2 in the jelly roll structure 300S described above.

[0343] The process may then include the step of manufacturing the positive electrode 500 by slitting the blank positive electrode portion 530 and the positive electrode active material portion 520. Figure 44 is a perspective view showing the positive electrode 500 according to one embodiment of the present invention.

[0344] Referring to Figures 42 to 44, as shown by the dotted lines in Figures 42 and 43, slitting can be performed on the blank positive electrode portion 530 and the positive electrode active material portion 520 in a direction parallel to the third direction d3. This allows for the production of multiple positive electrodes 500 as shown in Figure 44 from the positive electrode sheet 500S. That is, the positive electrode 500 in Figure 44 corresponds to one of several positive electrodes produced by slitting the positive electrode sheet 500S in Figures 42 and 43. By slitting the blank positive electrode portion 530 and the positive electrode active material portion 520 in the positive electrode sheet 500S, a positive electrode 500 can be produced in which the blank positive electrode portion 530 extends to one side.

[0345] When forming the positive electrode active material portion 520, a slurry containing the positive electrode active material is applied onto the positive electrode current collector 510. During this slurry application process, a positive electrode boundary portion 520B can be formed at the boundary between the positive electrode active material portion 520 and the positive electrode blank portion 530, where the loading amount gradually decreases in the direction of the positive electrode blank portion 530.

[0346] Referring to Figures 37, 41, and 44, the next step may be to wind the manufactured negative electrode 400 and positive electrode 500 together with the separation membrane 600 to form a jelly roll structure 300S. In this case, the plain negative electrode portion 430 may extend longer than the separation membrane 600 in the first direction d1, and the plain positive electrode portion 530 may extend longer than the separation membrane 600 in the second direction d2 opposite to the first direction d1.

[0347] Referring further to Figures 42 to 44, in a method for manufacturing an electrode assembly according to one embodiment of the present invention, the positive electrode sheet 500S includes a loading reduction region 500DA in which the loading amount of the positive electrode active material is less than in the adjacent region. There are no particular restrictions on the method for forming the loading reduction region 500DA, and as an example, it can be formed by adjusting the degree to which the slurry is applied.

[0348] In the manufacturing stage of 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 Figures 37 and 38, in which the amount of positive electrode active material loaded is less than in adjacent regions.

[0349] Specifically, a loading reduction region 500DA is formed in the positive electrode active material portion 520 formed on the positive electrode sheet 500S, where the loading amount of the positive electrode active material is less than in adjacent regions. As shown in Figure 43, the loading reduction region 500DA may be formed in the center of the positive electrode active material portion 520. On the other hand, the loading reduction region 500DA may be configured such that the loading amount of the positive electrode active material gradually decreases toward the central portion 500C of the loading reduction region 500DA, and the loading reduction region 500D according to this embodiment can be formed by slitting the central portion 500C of the loading reduction region 500DA during the manufacturing stage of the positive electrode 500.

[0350] In other words, by applying a slurry containing positive electrode active material, a loading reduction region 500DA is formed, and by slitting the central part 500C of the loading reduction region 500DA, multiple positive electrodes 500 in which a loading reduction portion 500D is formed can be manufactured.

[0351] Referring to Figure 44, a loading reduction portion 500D may be provided at one end of the manufactured positive electrode 500, and a blank positive electrode portion 530 may be provided at the other end of the positive electrode 500 opposite to the one end.

[0352] Referring to Figures 37 and 38, when such a positive electrode 500 is wound up 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 blank portion 530 of the positive electrode may be located at one end of the positive electrode 500 in the second direction d2.

[0353] Furthermore, by slitting the central part 500C of the loading reduction region 500DA, the loading reduction portion 500D can be made to gradually decrease the amount of positive electrode active material loaded in the first direction d1.

[0354] Furthermore, in the jelly roll structure 300S, the negative electrode active material portion 420 may be located in a portion corresponding to the loading reduction portion 500D, with reference to a direction perpendicular to the first direction d1. More specifically, in the jelly roll structure 300S, the negative electrode boundary portion 420B may be located in a portion corresponding to the loading reduction portion 500D, with reference to a direction perpendicular to the first direction d1.

[0355] The corresponding positional relationship between the loading reduction section 500D and the negative electrode boundary section 420B is the same as described above and will therefore be omitted.

[0356] Hereinafter, an electrode assembly according to a comparative embodiment of the present invention will be described with reference to Figures 45 to 48, and the advantages of the electrode assembly according to the embodiment of the present invention compared to the electrode assembly according to the comparative embodiment will be explained.

[0357] Figure 45 shows an electrode assembly according to a comparative embodiment of the present invention, and Figure 46 is a cross-sectional view taken along the line B-B' in Figure 45.

[0358] Referring to Figures 45 and 46, the electrode assembly 600 according to a comparative embodiment of the present invention includes a negative electrode 700, a positive electrode 800, and a separation membrane 900, and the negative electrode 700, positive electrode 800, and separation membrane 900 are wound up to form a jelly roll structure 600S.

[0359] The negative electrode 700 may include a negative electrode current collector 710, a negative electrode active material portion 720, and a negative electrode blank portion 730. The negative electrode blank 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 blank portion 730, while the loading amount gradually decreases.

[0360] Figure 47 shows the process for manufacturing the negative electrode 700 according to a comparative embodiment of the present invention.

[0361] Referring to Figure 47, after the negative electrode sheet 700S is manufactured such that the negative electrode active material portion 720 and the negative electrode plain portion 730 are alternately positioned along the fourth direction d4, the negative electrode plain portion 730 and the negative electrode active material portion 720 can be slit to manufacture a plurality of negative electrodes 700.

[0362] On the other hand, referring further to Figures 45 and 46, the positive electrode 800 may include a positive electrode current collector 810, a positive electrode active material portion 820, and a positive electrode blank portion 830. The positive electrode blank portion 830 may extend toward 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 in which the loading amount gradually decreases while forming a boundary between the positive electrode active material portion 820 and the positive electrode blank portion 830.

[0363] Figure 48 shows the process for manufacturing the positive electrode 800 according to a comparative embodiment of the present invention.

[0364] Referring to Figure 48, after manufacturing a positive electrode sheet 800S such that the positive electrode active material portion 820 and the positive electrode blank portion 830 are alternately positioned along the fourth direction d4, multiple positive electrodes 800 can be manufactured by slitting the positive electrode blank portion 830 and the positive electrode active material portion 820.

[0365] Subsequently, the manufactured negative electrode 700 and positive electrode 800 can be wound together with the separation membrane 900 to produce an electrode assembly 600 according to a comparative embodiment of the present invention.

[0366] In other words, the electrode assembly 600 according to the comparative embodiment of the present invention may have a structure similar to the electrode assembly 300 according to the embodiment of the present invention, except for the loading reduction section 500D (see Figure 38).

[0367] Referring to Figures 45 and 46, in the case of the electrode assembly 600 in the comparative configuration, the positive electrode active material portion 820 cannot be located in the portion corresponding to the negative electrode boundary portion 720B, with reference to the direction perpendicular to the first direction d1. If the positive electrode active material portion 820 extends to the portion corresponding to the negative electrode boundary portion 720B, that portion will have a low N / P ratio, and there is a high possibility that metallic lithium will be deposited. Therefore, in order to prevent lithium deposition, the length of the positive electrode active material portion 820 must be limited. That is, the positive electrode active material portion 820 can be formed only in the illustrated B1 region, and the positive electrode active material portion 820 cannot be formed in the B2 region, resulting in the negative electrode boundary portion 720B reducing the length of the positive electrode active material portion 820.

[0368] On the other hand, referring to Figures 37 and 38, in the case of the electrode assembly 300 according to an embodiment of the present invention, the positive electrode active material portion 520, particularly the loading reduction portion 500D, can be located in a portion corresponding to the negative electrode boundary portion 420B, with reference to a direction perpendicular to the first direction d1. Since the loading reduction portion 500D, in which the loading amount of positive electrode active material is less than in the adjacent region, is provided in a position corresponding to the negative electrode boundary portion 420B, the N / P ratio in that portion can be kept high, and lithium deposition can be prevented. As a result, the positive electrode active material portion 520 can be formed over the A1 region, and the A2 region in which the positive electrode active material portion 520 cannot be formed can be reduced. As an 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 can be increased to 98% or more.

[0369] Comparing the A1 region in Figures 37 and 38 with the B1 region in Figures 45 and 46, 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, thus enabling it to achieve an even higher energy density in a limited space than the electrode assembly 600 according to the comparative configuration.

[0370] A further embodiment of the present invention relates to a cylindrical battery comprising a jelly roll-type electrode assembly having a structure in which a positive electrode, a negative electrode, and a separation membrane interposed between the positive electrode and the negative electrode are wound in one direction; a cylindrical battery housing in which the electrode assembly is housed; and a battery cap which is a seal placed on the top of the battery housing and sealing the battery housing. Herein, the positive electrode is according to one embodiment of the present invention, and the positive electrode active material has an average particle size D 50 The battery contains single-particle active material particles with a size of 5 μm or less. The cylindrical battery may further contain an electrolyte, and the above description can be found for details regarding the electrolyte.

[0371] The electrode assembly may have a laminated, laminated / folded, or jelly roll structure as described above. In one specific embodiment of the present invention, the electrode assembly may have a positive electrode with a loading reduction portion as described above.

[0372] Conventional cylindrical batteries have the problem that current is concentrated in the strip-shaped electrode tabs, resulting in high resistance, generating a large amount of heat, and poor current collection efficiency.

[0373] In recent years, with the advancement of electric vehicle-related technologies, the demand for high-capacity batteries has increased, necessitating the development of large, cylindrical batteries with greater volume. Conventional small cylindrical batteries, such as those with the 1865 or 2170 form factors, have small capacities, so resistance and heat generation do not significantly affect battery performance. However, applying the specifications of conventional small cylindrical batteries directly to large cylindrical batteries could lead to serious battery safety issues.

[0374] As batteries become larger, the amount of heat and gas generated inside them also increases. This heat and gas can raise the temperature and pressure inside the battery, potentially causing it to ignite or explode. To prevent this, the heat and gas inside the battery must be properly dissipated to the outside. For this to happen, the cross-sectional area of ​​the battery, which serves as a passage for heat to escape, needs to increase in proportion to the increase in volume. However, usually, the increase in cross-sectional area does not match the increase in volume. Therefore, as batteries become larger, the amount of heat generated inside the battery increases, leading to problems such as a greater risk of explosion and a decrease in output. Furthermore, when performing rapid charging at high voltage, there is a risk of the battery igniting due to the generation of a large amount of heat around the electrode tabs in a short period of time. Therefore, the present invention proposes a cylindrical battery that has a large volume to achieve high capacity while maintaining high safety.

[0375] Furthermore, since the high-loading electrode to which the positive electrode active material in the form of a single particle or pseudo-single particle is applied is applied to a cylindrical battery, the initial resistance characteristics and charge / discharge efficiency of the cylindrical battery can be improved.

[0376] A cylindrical battery according to one embodiment of the present invention significantly reduces 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 higher.

[0377] A cylindrical battery according to one embodiment of the present invention is preferably a tabless battery that does not include electrode tabs, but is not limited thereto.

[0378] The aforementioned tablet-like battery may have a structure in which, for example, the positive electrode and the negative electrode each include blank portions on which no active material layer is formed, the positive electrode blank portion and the negative electrode blank portion are located at the upper and lower ends of the electrode assembly, a current collector plate is coupled to the positive electrode blank portion and the negative electrode blank portion, and the current collector plate is connected to the electrode terminals.

[0379] When a cylindrical battery is formed in the tabless structure as described above, compared with a conventional battery provided with an electrode tab, current concentration is reduced, so heat generation inside the battery can be effectively decreased, and thereby the effect of improving the thermal stability of the battery can be achieved.

[0380] Hereinafter, the present invention will be described in more detail with specific examples.

[0381] <Example 1> Average particle diameter D 50 having a unimodal particle size distribution with an average particle diameter of 3 μm and being in the form of single particles, the positive electrode active material Li[Ni 0.9 Co 0.06 Mn 0.03 Al 0.01 O2, carbon nanotubes, and a PVDF binder were mixed in N-methylpyrrolidone at a weight ratio of 97.8:0.6:1.6 to produce a positive electrode slurry. After applying the positive electrode slurry to one surface of an aluminum current collector sheet, it was dried at 120 °C and then rolled to produce a positive electrode.

[0382] 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) were mixed in water at a weight ratio of 96:2:1.5:0.5 to produce a negative electrode slurry. After applying the negative electrode slurry to one surface of a copper current collector sheet, it was dried at 150 °C and then rolled to produce a negative electrode.

[0383] After a separator was interposed between the produced positive electrode and negative electrode and laminated in the order of separator / positive electrode / separator / negative electrode, it was wound to produce a jelly roll type electrode assembly. After inserting the electrode assembly produced as described above into a cylindrical battery can, an electrolytic solution was injected to produce a 4680 cell.

[0384] [[ID=3又は]]<Comparative Example 1> '

[0385] As the positive electrode active material, the large particle size average particle diameter D 50 [[ID=]] 50It has a bimodal particle size distribution with a size of 4 μm and is in the form of secondary particles, and Li[Ni 0.9 Co 0.05 Mn 0.04 Al 0.01 O2 was used, and a 4680 cell was manufactured in the same manner as in Example 1 except for this.

[0386] <Experimental Example 1> A hot box test was performed on the 4680 cells manufactured according to Example 1 and Comparative Example 1.

[0387] [[ID=We specifically placed the 4680 cells manufactured according to Example 1 and Comparative Example 1 in a hot box chamber at room temperature, heated them to 130 °C at a heating rate of 5 °C / min, and then maintained them for 30 minutes to conduct a hot box evaluation, and measured the temperature change of the battery over time. For accurate evaluation, the cells of Example 1 were subjected to two hot box evaluations. The measurement results are shown in FIGS. 34a and 34b.

[0388] FIG. 34a is a graph showing the results of the hot box test for the 4680 cells manufactured according to Example 1, and FIG. 34b is a graph showing the results of the hot box test for the 4680 cells manufactured according to Comparative Example 1.

[0389] From FIGS. 34a and 34b, in the case of the lithium secondary battery of Example 1 using a single-particle form of the positive electrode active material, the voltage and temperature of the battery were stably maintained until 65 minutes passed, while it was confirmed that the battery temperature of the lithium secondary battery of Comparative Example 1 rapidly increased after 35 minutes passed. ;

[0390] <Example 2-1> It has a unimodal particle size distribution with D 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 0.01O2) was prepared. Figure 33a shows an SEM image of the positive electrode active material used in Example 2-1.

[0391] A positive electrode slurry was prepared by mixing a positive electrode active material, carbon nanotubes, and a PVDF binder in N-methylpyrrolidone in a weight ratio of 97.8:0.6:1.6. The positive electrode slurry was applied to one surface of an aluminum current collector sheet, dried at 120°C, and then rolled to produce a positive electrode.

[0392] A negative electrode slurry was prepared by mixing a negative electrode active material (graphite:SiO=95:5 (by weight ratio) mixture), a conductive material (Super C), styrene-butadiene rubber (SBR), and carboxymethylcellulose (CMC) in water in a weight ratio of 96:2:1.5:0.5. After applying the negative electrode slurry to one surface of a copper current collector sheet, it was dried at 150°C and then rolled to produce a negative electrode.

[0393] A separator membrane was placed between the manufactured positive and negative electrodes, and the electrodes were stacked in the order of separator membrane / positive electrode / separator membrane / negative electrode. After this, the assembly was wound up to produce a jelly roll-type electrode assembly. After inserting the electrode assembly manufactured as described above into a battery case, electrolyte was injected to produce a 4680 cell.

[0394] <Example 2-2> As the positive electrode active material, D has a unimodal particle size distribution. min =1.38μm, D 50 =4.69μm, D max =18.5μm, and the positive electrode active material (composition: Li[Ni 0.9 Co 0.06 Mn 0.03 Al 0.01 A 4680 cell was manufactured in the same manner as in Example 2-1, except that O2 was used. Figure 33b shows an SEM image of the cathode active material used in Example 2-2.

[0395] <Comparative Example 2-1> Large particle size average particle size D 50 The small particle size is 9 μm, and the average particle size D 50The positive electrode active material (composition: Li[Ni) has a bimodal particle size distribution of 4 μm and is in the form of secondary particles. 0.9 Co 0.05 Mn 0.04 Al 0.01 4680 cells were manufactured in the same manner as in Example 2-1, except that ]O2) was used.

[0396] <Comparative Example 2-2> Having a unimodal particle size distribution D min =0.892μm, D 50 =3.02μm, D max =11μm, and the positive electrode active material (composition: Li[Ni 0.9 Co 0.06 Mn 0.03 Al 0.01 4680 cells were manufactured in the same manner as in Example 2-1, except that ]O2) was used.

[0397] Figure 33c shows an SEM image of the positive electrode active material used in Comparative Example 2-2.

[0398] <Experimental Example 2-1> A hot box test was performed on 4680 cells produced according to Examples 2-1, 2-2 and Comparative Examples 2-1, 2-2.

[0399] Specifically, the 4680 cells manufactured 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 heating rate of 5°C / min, maintained at that temperature for 30 minutes, and then the temperature change of the battery was measured. A "pass" was indicated if no thermal runaway or ignition occurred during the test, and a "fail" was indicated if thermal runaway and / or ignition occurred. Furthermore, for accuracy, the cells in Examples 2-1 and 2-2 were tested more than twice.

[0400] The measurement results are shown in Table 1 and Figures 34c and 34d below. Figure 34c is a graph showing the results of the hot box test on 4680 cells produced by Sample 1 of Example 2-1 and Comparative Example 2-1, and Figure 34d is a graph showing the results of the hot box test on 4680 cells produced by Samples 2 and 3 of Example 2-1, Samples 1 and 2 of Example 2-2 and Comparative Example 2-2.

[0401] [Table 1]

[0402] Referring to Table 1, Figures 34c and 34d, 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 / pseudo-single particle with a diameter of 1.0 μm or more, the battery voltage and temperature are stably maintained until 65 minutes have elapsed, whereas in Comparative Examples 2-1 and D, which use secondary particles as the positive electrode active material, the voltage and temperature of the battery are stably maintained until 65 minutes have elapsed. min In Comparative Example 2-2, a 4680 cell using a positive electrode active material in single-particle / pseudo-single-particle form with a particle size of less than 1.0 μm was observed to experience a rapid increase in battery temperature.

[0403] <Experimental Example 2-2> To confirm the degree of cracking of the positive electrode active material particles after rolling, the positive electrodes manufactured in Example 2-1 and Comparative Example 2-1 were cut using an ion milling apparatus, and the cross-sections were photographed with a scanning electron microscope (SEM). Figure 35a shows a cross-sectional SEM image of the positive electrode manufactured in Example 2-1, and Figure 35b shows a cross-sectional SEM image of the positive electrode manufactured in Comparative Example 2-1.

[0404] Figures 35a and 35b show that the positive electrode of Example 2-1 shows almost no particle cracking of the positive electrode active material after rolling, while the positive electrode of Comparative Example 2-2, which uses secondary particles, shows numerous particle cracks of the positive electrode active material after rolling.

[0405] <Example 3-1> Having a unimodal particle size distribution D min =1.78μm, D 50 =4.23μm, D max=13.1μm, and the positive electrode active material powder (composition: Li[Ni 0.9 Co 0.06 Mn 0.03 Al 0.01 A positive electrode slurry was prepared by mixing oxyoxyl (O2), flake graphite (SFG6L), a conductive material (multilayer carbon nanotube), and a PVDF binder in N-methylpyrrolidone in a weight ratio of 96.3:1.5:0.4:1.8. The positive electrode slurry was applied to one surface of an aluminum current collector sheet, dried, and rolled at a linear pressure of 3.0 ton / cm to produce a positive electrode. The porosity of the positive electrode active material layer of the produced positive electrode was measured. The porosity was 17.5%.

[0406] <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%.

[0407] <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%.

[0408] <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%.

[0409] <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 slurry was prepared by mixing the positive electrode active material, conductive material, and binder in N-methylpyrrolidone in a weight ratio of 97.8:0.4:1.8. The porosity of the positive electrode active material layer was measured. The porosity was 24%.

[0410] <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 slurry was prepared by mixing the positive electrode active material, conductive material, and binder in N-methylpyrrolidone in a weight ratio of 97.8:0.4:1.8, and then rolling it at a linear pressure of 2.0 ton / cm. The porosity of the positive electrode active material layer was then measured. The porosity was 30%.

[0411] <Experimental Example 3-1. Measurement of Charge / Discharge Capacity and Charge / Discharge Efficiency> Coin-type half-cells containing positive electrodes were manufactured according to Examples 3-1 to 3-4 and Comparative Examples 3-1 and 3-2. These were charged to 4.25V under a 0.2C current condition, and then discharged to 2.5V under the same 0.2C current condition. The charging capacity (mAh / g) and discharging capacity (mAh / g) of each coin-type half-cell were measured. The measurement results are shown in Table 2 below.

[0412] [Table 2]

[0413] Table 2 shows that Examples 3-1 to 3-4, which use a cathode with added flake graphite, exhibit lower porosity and superior capacitance characteristics compared to Comparative Examples 3-1 and 3-2.

[0414] <Experimental Example 3-2. Confirmation of Resistivity Characteristics> The resistance characteristics corresponding to the State of Charge (SOC) were measured while charging coin-type half-cells containing the positive electrode according to Example 3-3, Comparative Example 3-1, and Comparative Example 3-2 to 4.2V. The experimental results are shown in Figure 36a.

[0415] Referring to Figure 36a, it can be seen that, using a SOC of 10%, the resistance value of Example 3-3, in which flake graphite is added to the positive electrode active material layer, is lower than that of Comparative Examples 3-1 and 3-2, which do not contain flake graphite. This indicates that adding flake graphite to the positive electrode active material layer has the effect of improving the resistance characteristics at low SOCs.

[0416] <Experimental Example 3-3. Measurement of High-Temperature Life Characteristics and Resistivity Increase Rate> In Examples 3-1, 3-3, and Comparative Example 3-1, a separation membrane was interposed between the positive and negative electrodes, and the electrodes were stacked in the order of separation membrane / positive electrode / separation membrane / negative electrode. The assembly was then wound up to produce a jelly roll-type electrode assembly. After inserting the manufactured electrode assembly into a cylindrical battery case, an electrolyte solution was injected to produce a 4680 cell.

[0417] In this case, the negative electrode was manufactured by first mixing a negative electrode active material (graphite:SiO=95:5 (by weight ratio) mixture), a conductive material (Super C), styrene-butadiene rubber (SBR), and carboxymethylcellulose (CMC) in water in a weight ratio of 96:2:1.5:0.5 to produce a negative electrode slurry, then applying the negative electrode slurry to one surface of a copper current collector sheet, drying it at 150°C, and then rolling it.

[0418] The 4680 cells manufactured in this manner were charged to 4.2V at 40°C with a current of 0.5C, and then discharged to 2.5V at 0.5C for 50 charge-discharge cycles. After these cycles, the capacity retention rate and resistance (DCIR) increase rate were measured. The measurement results are shown in Figure 36b.

[0419] Referring to Figure 36b, it can be seen that in the case of the secondary batteries of Examples 3-1 and 3-3, the change in capacity retention rate with respect to the number of cycles is smaller, and the change in resistance increase rate with respect to the number of cycles is also smaller, compared to the secondary battery of Comparative Example 3-1.

[0420] As described above, the present invention has been explained with limited embodiments and drawings, but the present invention is not limited thereto, and it goes without saying that various modifications and variations are possible within the equivalent scope of the technical concept and claims of the present invention by persons with ordinary skill in the art to which the present invention pertains. [Explanation of symbols]

[0421] 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 First tab joint 33 Housing joint 33a Contact part 33b 1st connection part 40 Cap Plates 41 Venting section 50 Second current collector plate 51 Peripheral area 52 Second tab joint 53 Terminal connection part 54 2nd connection part 54a Tapered section 60 Battery terminals 60a Exposed terminal portion 60b Terminal insertion section 300 electrode assembly 400 negative electrode 410 Negative electrode current collector 420 Negative electrode active material section 430 Negative electrode blank area 500 positive electrode 510 Positive electrode current collector 520 Cathode active material section 530 Positive electrode blank area 600 Separation membrane 700 negative electrode 710 Negative electrode current collector 720 Negative electrode active material section 730 Negative electrode blank area 800 positive electrode 810 Positive electrode current collector 820 Cathode active material section 830 Positive electrode blank area 900 Separation membrane

Claims

1. An electrode assembly comprising a first electrode tab and a second electrode tab, A battery housing that houses the electrode assembly through an opening formed on one side and is electrically connected to the first electrode tab, A first current collector plate including a support portion disposed on one surface of the electrode assembly, at least one first tab coupling portion extending from the support portion and coupled to the first electrode tab, and at least one housing coupling portion extending from the end of the first tab coupling portion and coupled to the inner surface of the battery housing, A second current collector plate comprising a peripheral portion located on the other side opposite to one side of the electrode assembly, a second tab coupling portion extending inward from the peripheral portion and coupled to the second electrode tab, and a terminal coupling portion located spaced apart from the second tab coupling portion, A cap plate configured to seal the opening of the battery housing, The battery terminal includes a battery terminal that penetrates the battery housing and is electrically connected to the second electrode tab by connecting to the terminal coupling portion, The battery housing includes a beading portion formed on the peripheral edge adjacent to the opening and pushed inward. The housing joint portion is A contact portion bonded to the beading portion, A cylindrical battery, comprising a first connecting portion that connects the first tab connecting portion and the contact portion.

2. The battery housing includes a beading portion formed on the peripheral edge adjacent to the opening and pushed inward. The cylindrical battery according to claim 1, wherein the housing coupling portion is coupled to the beading portion.

3. The cylindrical battery according to claim 1, wherein the cylindrical battery includes a sealing gasket provided between the battery housing and the cap plate.

4. The cylindrical battery according to claim 3, wherein the contact portion is interposed and fixed between the beading portion and the sealing gasket.

5. A cylindrical battery according to claim 1, wherein a welded portion is formed between the beading portion and the contact portion of the first current collector plate.

6. An electrode assembly comprising a first electrode tab and a second electrode tab, A battery housing that houses the electrode assembly through an opening formed on one side and is electrically connected to the first electrode tab, A first current collector plate including a support portion disposed on one surface of the electrode assembly, at least one first tab coupling portion extending from the support portion and coupled to the first electrode tab, and at least one housing coupling portion extending from the end of the first tab coupling portion and coupled to the inner surface of the battery housing, A second current collector plate comprising a peripheral portion located on the other side opposite to one side of the electrode assembly, a second tab coupling portion extending inward from the peripheral portion and coupled to the second electrode tab, and a terminal coupling portion located spaced apart from the second tab coupling portion, A cap plate configured to seal the opening of the battery housing, The battery terminal includes a terminal coupling portion which is electrically connected to the second electrode tab, The battery housing includes a beading portion formed on the peripheral edge adjacent to the opening and pushed inward. A cylindrical battery in which the boundary region between the first tab joint and the housing joint is located inside the innermost part of the beading portion.

7. The cylindrical battery according to any one of claims 1 to 6, wherein the cylindrical battery comprises a plurality of the first tab coupling portion and the housing coupling portion.

8. The cylindrical battery according to claim 1, wherein the first connecting portion comprises at least one bent portion whose direction of extension is changed.

9. The cylindrical battery according to claim 1, wherein the contact portion has an arc shape extending along the beading portion.

10. The cylindrical battery according to claim 9, wherein the first connecting portion has an arc shape extending along the contact portion.

11. The cylindrical battery according to any one of claims 1 to 6, wherein the peripheral portion has a rim shape with a hollow center.

12. The cylindrical battery according to any one of claims 1 to 6, wherein the second tab coupling portion and the terminal coupling portion are electrically connected by the peripheral portion.

13. The cylindrical battery according to any one of claims 1 to 6, wherein the terminal coupling portion is located in the center of the inner space of the peripheral portion.

14. The cylindrical battery according to any one of claims 1 to 6, wherein the second current collector plate further includes a second connecting portion that extends inward from the peripheral edge and is connected to the terminal coupling portion.

15. The cylindrical battery according to claim 14, wherein the width of at least a portion of the second connecting portion is formed to be narrower than that of the second tab connecting portion.

16. The cylindrical battery according to claim 14, wherein the second connecting portion has a tapered portion whose width gradually narrows from the inner surface of the peripheral portion toward the terminal connecting portion.

17. The cylindrical battery according to claim 14, wherein a plurality of the second tab coupling portions are provided.

18. The cylindrical battery according to claim 17, wherein the plurality of second tab coupling portions are arranged at equal intervals from one another along the extending direction of the peripheral portion.

19. The cylindrical battery according to claim 17, wherein the plurality of the second tab coupling portions have the same extended length.

20. The cylindrical battery according to claim 17, wherein the terminal coupling portion is arranged to be surrounded by a plurality of the second tab coupling portions.

21. The second connecting portion is located between a pair of adjacent second tab connecting portions. The cylindrical battery according to claim 17, wherein the distance from the second connecting portion to one of the pair of second tab connecting portions along the extending direction of the peripheral portion is the same as the distance from the second connecting portion to the other of the pair of second tab connecting portions along the extending direction of the peripheral portion.

22. The cylindrical battery according to claim 17, wherein the second connecting portion is provided in multiple locations.

23. The cylindrical battery according to claim 22, wherein each of the plurality of second connecting portions is positioned between a pair of adjacent second tab connecting portions.

24. The cylindrical battery according to claim 22, wherein the plurality of second connecting portions are arranged at equal intervals from one another along the extending direction of the peripheral portion.

25. The cylindrical battery according to claim 14, wherein the second connecting portion includes a notch formed by narrowing the width of the second connecting portion.

26. The second connecting portion includes a notch formed by narrowing the width of the second connecting portion, The cylindrical battery according to claim 16, wherein the notch is located even closer to the tapered portion than the terminal coupling portion.

27. The cylindrical battery according to any one of claims 1 to 6, wherein the terminal coupling portion is positioned in a location corresponding to a hole formed in the winding center of the electrode assembly.

28. The cylindrical battery according to any one of claims 1 to 6, wherein the second electrode tab extends toward a closed portion located opposite the open portion of the battery housing.

29. The cylindrical battery according to claim 28, wherein the second tab coupling portion is coupled to a coupling surface formed by bending the end of the second electrode tab in a direction parallel to the second current collector plate.

30. An electrode assembly comprising a first electrode tab and a second electrode tab, A battery housing that houses the electrode assembly through an opening formed on one side and is electrically connected to the first electrode tab, A first current collector plate including a support portion disposed on one surface of the electrode assembly, at least one first tab coupling portion extending from the support portion and coupled to the first electrode tab, and at least one housing coupling portion extending from the end of the first tab coupling portion and coupled to the inner surface of the battery housing, A second current collector plate comprising a peripheral portion located on the other side opposite to one side of the electrode assembly, a second tab coupling portion extending inward from the peripheral portion and coupled to the second electrode tab, and a terminal coupling portion located spaced apart from the second tab coupling portion, A cap plate configured to seal the opening of the battery housing, The battery terminal includes a battery terminal that penetrates the battery housing and is electrically connected to the second electrode tab by connecting to the terminal coupling portion, The cap plate is not connected to the electrode assembly and is a cylindrical battery without polarity.

31. The cylindrical battery according to any one of claims 1 to 6, wherein the battery terminals penetrate a closed portion located on the opposite side of the open portion of the battery housing.

32. The cylindrical battery according to claim 31, further comprising an insulator interposed between the closing portion and the second current collector plate.

33. The cylindrical battery according to claim 32, wherein the battery terminals are connected to the terminal coupling portion of the second current collector plate by passing through the insulator.

34. The active material layer of the second electrode contains a positive electrode active material comprising single particles, pseudo-single particles, or a combination thereof. The minimum particle size Dmin that appears in the volume cumulative distribution of the positive electrode active material is 1.0 μm or larger. In the volume cumulative distribution of the positive electrode active material, the particle size D50 when the volume cumulative amount is 50% is 5.0 μm or less. The cylindrical battery according to any one of claims 1 to 6, wherein the maximum particle size Dmax appearing in the volume cumulative distribution of the positive electrode active material is 12 μm to 17 μm.

35. The positive electrode active material has a unimodal particle size distribution in which a single peak appears in the volume cumulative particle size distribution graph, and is expressed by the following equation 1: [Formula 1] Particle size distribution (PSD) = (Dmax-Dmin) / D50 The cylindrical battery according to claim 34, wherein the particle size distribution (PSD) represented by is 3 or less.

36. The cylindrical battery according to claim 34, wherein the single particle, pseudo-single particle, or combination thereof is included in an amount of 95 wt% to 100 wt% based on the total weight of the positive electrode active material contained in the active material layer of the second electrode.

37. The cylindrical battery according to claim 34, wherein the positive electrode active material contains a lithium nickel-based oxide containing 80 mol% or more of Ni based on the total number of moles of the transition metal.

38. The active material layer of the second electrode has a porosity of 15% to 23%. The cylindrical battery according to claim 34, wherein the active material layer of the second electrode contains flaky graphite in a weight ratio of 0.05 wt% to 5 wt%.

39. The cylindrical battery according to claim 34, wherein the active material layer of the second electrode further comprises carbon nanotubes (CNTs).

40. 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 according to claim 34, wherein the silicon-based anode active material and the carbon-based anode active material are contained in a weight ratio of 1:99 to 20:

80.

41. A battery pack comprising a cylindrical battery according to any one of claims 1 to 6.

42. An automobile comprising the battery pack described in claim 41.

Images