Cylindrical lithium-ion rechargeable battery

Abstract

The present invention relates to a cylindrical lithium secondary battery including a jelly-roll type electrode assembly in which a positive electrode plate, a negative electrode plate, and a separator interposed between the positive electrode plate and the negative electrode plate are wound in one direction, a battery can in which the electrode assembly is housed, an electrolyte injected into the battery can, and a sealing body that seals an open end of the battery can, wherein the electrolyte includes a lithium salt, an organic solvent, and additives such as lithium difluorophosphate, vinylene carbonate, and 1,3-propane sultone, and satisfies the following formula (1): Formula (1): 3.5≦W LiDFP / (W VC +W PS )×Φ / H×100≦20

Description

[Technical Field]

[0001] This application claims priority under Korean Patent Application No. 10-2022-0079872 dated June 29, 2022, and all content disclosed in the documents of the said Korean Patent Application is incorporated herein by reference.

[0002] This invention relates to a cylindrical lithium secondary battery. [Background technology]

[0003] With the advancement of technologies such as electric vehicles and portable electronic devices, the demand for lithium-ion batteries as an energy source is rapidly increasing.

[0004] In particular, with the recent advancements in electric vehicle technology, the need for high-capacity batteries has increased, necessitating the development of large, cylindrical batteries with a larger volume. Conventionally, small cylindrical batteries commonly used, such as those with the 1865 or 2170 form factors, did not require high rapid charging performance.

[0005] However, for large cylindrical batteries, rapid charging characteristics are extremely important because they are used in electric vehicles. The increase in the cross-sectional area of ​​a large cylindrical battery is not proportional to the increase in volume. Therefore, as the battery size increases, the amount of heat generated inside the battery increases, leading to problems such as an increased risk of explosion and reduced output. Furthermore, when rapid charging is performed at high voltage, lithium can be deposited from the negative electrode, causing rapid battery degradation. This can also lead to problems such as rapid heat generation around the electrode tabs, causing battery degradation or even ignition.

[0006] Therefore, there is a need to develop cylindrical batteries that have a large volume, excellent lifespan characteristics, and rapid charging characteristics, in order to achieve high capacity. [Overview of the project] [Problems that the invention aims to solve]

[0007] The present invention aims to solve the above-mentioned problems and to provide a large-capacity cylindrical lithium secondary battery that excels in various performance aspects such as output characteristics, lifespan characteristics, and rapid charging characteristics. [Means for solving the problem]

[0008] According to one embodiment, the present invention provides a cylindrical lithium secondary battery comprising a jelly-roll type electrode assembly in which a positive electrode plate, a negative electrode plate, and a separator interposed between the positive electrode plate and the negative electrode plate are wound in one direction; a battery case in which the electrode assembly is housed; an electrolyte poured into the battery case; and a seal that seals the open end of the battery case, wherein the electrolyte comprises a lithium salt, an organic solvent, and as additives, lithium difluorophosphate, vinylene carbonate, and 1,3-propanesultone, and satisfies the following formula (1).

[0009] Formula (1): 3.5≦W LiDFP / (W VC +W PS ) × Φ / H × 100 ≤ 20 In equation (1) above, W LiDFP This is the weight ratio (%) of lithium difluorophosphate to the total electrolyte, W VC This is the weight ratio (%) of vinylene carbonate to the total electrolyte, W PS Φ is the weight ratio (%) of 1,3-propanesultone to the total electrolyte, Φ is the diameter (mm) of the battery can, and H is the height (mm) of the battery can. [Effects of the Invention]

[0010] The cylindrical lithium secondary battery according to the present invention achieves a high capacity compared to conventional cylindrical lithium secondary batteries, requiring the application of a different electrolyte system than that used in conventional 1865 and 2170 cells. Therefore, the cylindrical lithium secondary battery according to the present invention applies an additive ratio based on the increased form factor ratio, resulting in superior high-temperature life characteristics and rapid charging characteristics.

[0011] Specifically, vinylene carbonate and 1,3-propanesultone are additives that function to form organic films on the surfaces of the negative and positive electrodes during the initial activation process, while lithium difluorophosphate is an additive that forms an inorganic film containing F and P on the electrodes during the initial activation process. In this invention, organic and inorganic films are formed according to the form factor, which is related to the size of the cylindrical lithium secondary battery, resulting in excellent high-temperature life characteristics and rapid charging characteristics.

[0012] Furthermore, the cylindrical lithium secondary battery according to the present invention can include a silicon-based negative electrode active material with a large capacity as the negative electrode active material, in which case an even higher energy density can be achieved. [Brief explanation of the drawing]

[0013] [Figure 1] This figure shows the stacked state of the electrode assembly according to the present invention before winding. [Figure 2] This is a cross-sectional view showing the structure of the electrode plate of an electrode assembly according to one embodiment of the present invention. [Figure 3] This is a cross-sectional view showing the structure of a cylindrical battery with a tabless structure according to one embodiment of the present invention. [Figure 4] This is a cross-sectional view showing the structure of a cylindrical battery with a tabless structure according to another embodiment of the present invention. [Figure 5] This is a diagram illustrating the structure of an electrode assembly according to one embodiment of the present invention. [Figure 6] This is a diagram illustrating the battery pack according to the present invention. [Figure 7] This is a diagram illustrating an automobile including a battery pack according to the present invention. [Modes for carrying out the invention]

[0014] The present invention will be described in more detail below.

[0015] The terms and words used herein and in the claims should not be interpreted in a manner limited to their ordinary or dictionary meanings, but rather in a manner consistent with the technical idea of ​​the present invention, in accordance with the principle that inventors may define the concepts of terms as appropriate to best describe their invention.

[0016] In this invention, "primary particle" refers to a particle unit in which no grain boundaries are visible when observed using a scanning electron microscope at a field of view of 5,000x to 20,000x. "Average particle size of primary particles" refers to the arithmetic mean calculated after measuring the particle sizes of primary particles observed from scanning electron microscope images.

[0017] In this invention, 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 are referred to as pseudo-single particles.

[0018] In this invention, "average particle size D 50 This refers to the particle size at the 50% reference point of the volume-cumulative particle size distribution of the positive electrode active material powder, and can be measured using the laser diffraction method. For example, after dispersing the positive electrode active material powder in a dispersion medium, it can be introduced into a commercially available laser diffraction particle size analyzer (e.g., Microtrac MT 3000), irradiated with ultrasound at approximately 28 kHz at an output of 60 W, and after obtaining a volume-cumulative particle size distribution graph, the particle size corresponding to 50% of the volume-cumulative amount can be determined to measure it.

[0019] In the present invention, "consist essentially of A" means that the product contains component A as its main component, for example, that it contains component A in an amount of 95% to 100% by weight, preferably 98% to 100% by weight, and more preferably 99% to 100% by weight.

[0020] The cylindrical lithium secondary battery according to the present invention can include a jelly-roll type electrode assembly having a structure in which a separator interposed between a positive electrode plate and a negative electrode plate is wound in one direction, a battery can in which the electrode assembly is housed, and a sealing body that seals an open end portion of the battery can.

[0021] The electrolyte contained in the cylindrical lithium secondary battery of the present invention contains lithium difluorophosphate, vinylene carbonate, and 1,3-propanesultone as a lithium salt, an organic solvent, and an additive, and is characterized by satisfying the following formula (1).

[0022] Formula (1): 3.5 ≤ W LiDFP / (W VC +W PS ) × Φ / H × 100 ≤ 20

[0023] In the above formula (1), W LiDFP is the weight ratio (%) of lithium difluorophosphate with respect to the whole electrolyte, W VC is the weight ratio (%) of vinylene carbonate with respect to the whole electrolyte, W PS is the weight ratio (%) of 1,3-propanesultone with respect to the whole electrolyte, and the Φ is the diameter (mm) of the battery can, and the H is the height (mm) of the battery can.

[0024] W LiDFP / (W VC +W PS ) × Φ / H × 100 can have a value of 3.5 or more and 20 or less, preferably 5 or more and 15 or less, and more preferably 10 or more and 15 or less.

[0025] Viylene carbonate and 1,3-propanesultone are additives that form organic films on the surfaces of the negative and positive electrodes during the initial activation process, while lithium difluorophosphate is an additive that forms an inorganic film containing F and P on the electrodes during the initial activation process. In this invention, organic and inorganic films are formed according to the form factor, which is related to the size of the cylindrical lithium secondary battery, resulting in excellent high-temperature life characteristics and rapid charging characteristics.

[0026] The electrolyte used in the cylindrical lithium secondary battery of the present invention comprises a lithium salt, an organic solvent, and additives.

[0027] Lithium difluorophosphate (LiPO2F2), used as an additive, is reduced during the initial activation process to form an inorganic film containing F and P on the electrode. This inorganic film provides excellent durability to the SEI layer and suppresses the decomposition of the electrode film even at high temperatures.

[0028] The electrolyte may contain LiPO2F2 in an amount of 0.01 to 1% by weight relative to the total weight of the electrolyte, preferably 0.1 to 1% by weight, and more preferably 0.2 to 0.8% by weight.

[0029] The vinylene carbonate used as an additive is an additive that functions to form a stable organic negative electrode film during the initial activation process when reduced at a low potential.

[0030] The electrolyte may contain vinylene carbonate in an amount of 0.1 to 10% by weight relative to the total weight of the electrolyte, preferably 1 to 5% by weight, and more preferably 2 to 4% by weight.

[0031] 1,3-propanesultone, used as an additive, functions to form a stable S-based organic film on the surfaces of the negative and positive electrodes during the initial activation process.

[0032] The electrolyte may contain 0.1 to 2% by weight of 1,3-propanesultone relative to the total weight of the electrolyte, preferably 0.1 to 1.5% by weight, and more preferably 0.2 to 0.5% by weight.

[0033] The organic solvent may include at least one organic solvent selected from the group consisting of cyclic carbonate organic solvents, linear carbonate organic solvents, linear ester organic solvents, and cyclic ester organic solvents.

[0034] Specifically, the organic solvent may include cyclic carbonate organic solvents, linear carbonate organic solvents, or mixtures thereof.

[0035] The aforementioned cyclic carbonate-based organic solvent is a highly viscous organic solvent with a high dielectric constant that can effectively dissociate lithium salts in the electrolyte. Specific examples include at least one organic solvent selected from the group consisting of ethylene carbonate (EC), propylene carbonate (PC), 1,2-butylene carbonate, 2,3-butylene carbonate, 1,2-pentylene carbonate, 2,3-pentylene carbonate, and vinylene carbonate, and among these, ethylene carbonate may be included.

[0036] The cyclic carbonate, for example, ethylene carbonate, can be present in 15-30% by volume, preferably 15-25% by volume, and most preferably 15-20% by volume, relative to the total amount of the organic solvent. When ethylene carbonate is present in the above range, it can help LiPO2F2 form a uniform SEI layer.

[0037] Furthermore, the linear carbonate-based organic solvent is an organic solvent having low viscosity and low dielectric constant. Typical examples include at least one organic solvent selected from the group consisting of dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate, ethyl methyl carbonate (EMC), methyl propyl carbonate, and ethyl propyl carbonate. Specifically, it may include ethyl methyl carbonate (EMC).

[0038] Furthermore, in order to produce an electrolyte having high ionic conductivity, the organic solvent may further include at least one ester organic solvent selected from the group consisting of linear ester organic solvents and cyclic ester organic solvents, in addition to at least one carbonate organic solvent selected from the group consisting of cyclic carbonate organic solvents and linear carbonate organic solvents.

[0039] Specific examples of such linear ester-based organic solvents include at least one organic solvent selected from the group consisting of methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, and butyl propionate.

[0040] Furthermore, the cyclic ester organic solvents include at least one organic solvent selected from the group consisting of γ-butyrolactone, γ-valerolactone, γ-caprolactone, σ-valerolactone, and ε-caprolactone.

[0041] On the other hand, the organic solvent may be further used without limitation by adding any organic solvents commonly used for non-aqueous electrolytes, as needed. For example, it may further contain at least one or more organic solvents selected from ether-based organic solvents, glyme-based solvents, and nitrile-based organic solvents.

[0042] As the ether-based solvent, one selected from the group consisting of dimethyl ether, diethyl ether, dipropyl ether, methyl ethyl ether, methyl propyl ether, ethyl propyl ether, 1,3-dioxolane (DOL), and 2,2-bis(trifluoromethyl)-1,3-dioxolane (TFDOL), or a mixture of two or more of these, may be used, but is not limited thereto.

[0043] The aforementioned glyme-based solvent has a higher dielectric constant and lower surface tension than linear carbonate-based organic solvents, and has low reactivity with metals. It may include, but is not limited to, at least one selected from the group consisting of dimethoxyethane (Gleim, DME), diethoxyethane, diglyme, triglyme, and tetraglyme (TEGDME).

[0044] The nitrile solvent may be one or more selected from the group consisting of acetonitrile, propionitrile, butyronitrile, valeronitrile, caprylonitrile, heptanenitrile, cyclopentanecarbonile, cyclohexanecarbonile, 2-fluorobenzonitrile, 4-fluorobenzonitrile, difluorobenzonitrile, trifluorobenzonitrile, phenylacetonitrile, 2-fluorophenylacetonitrile, and 4-fluorophenylacetonitrile, but is not limited thereto.

[0045] The lithium salt is used as an electrolyte salt in lithium secondary batteries and as a medium for transferring ions. Typically, lithium salts are used, for example, as cations. + It includes, and as an anion, F - Cl - , Br - , I - NO3 - , N(CN)2 - BF4 - ClO4 - B 10 Cl10 - AlCl4 - AlO2 - PF6 - CF3SO3 - CH3CO2 - CF3CO2 - AsF6 - SbF6 - CH3SO3 - , (CF3CF2SO2)2N - , (CF3SO2)2N - , (FSO2)2N - BF2C2O4 - BC4O8 - PF4C2O4 - PF2C4O8 - (CF3)2PF4 - (CF3)3PF3 - (CF3)4PF2 - (CF3)5PF - (CF3)6P - , C4F9SO3 - CF3CF2SO3 - CF3CF2(CF3)2CO - (CF3SO2) 2CH - CF3(CF2)7SO3 - and SCN - At least one of the following groups can be selected.

[0046] Specifically, the lithium salts are LiCl, LiBr, LiI, LiBF4, LiClO4, and LiB 10 Cl 10The electrolyte may include a single substance or a mixture of two or more substances selected from the group consisting of LiAlCl4, LiAlO2, LiPF6, LiCF3SO3, LiCH3CO2, LiCF3CO2, LiAsF6, LiSbF6, LiCH3SO3, LiN(SO2F)2 (lithium bis(fluorosulfonyl)imide; LiFSI), LiN(SO2CF2CF3)2 (lithium bis(perfluoroethanesulfonyl)imide; LiBETI), and LiN(SO2CF3)2 (lithium bis(trifluoromethanesulfonyl)imide; LiTFSI). In addition, lithium salts commonly used as electrolytes in lithium secondary batteries can be used without limitation.

[0047] The lithium salt can be appropriately changed within a range that is normally usable, but in order to obtain the optimal effect of forming a corrosion-preventive film on the electrode surface, it can be included in the electrolyte at a concentration of 0.1 M to 4.0 M, preferably 0.5 M to 3.0 M, and more preferably 0.8 M to 2.0 M. When the concentration of the lithium salt satisfies the above range, the effect of improving cycle characteristics is sufficient during high-temperature storage of the lithium secondary battery, and the viscosity of the non-aqueous electrolyte is appropriate, thus improving electrolyte impregnation.

[0048] Furthermore, the non-aqueous electrolyte of the present invention may further contain electrolyte additives to prevent the non-aqueous electrolyte from decomposing in high-power environments, which can lead to the collapse of the negative electrode, or to further improve low-temperature high-rate discharge characteristics, high-temperature stability, overcharge prevention, and suppression of battery swelling at high temperatures.

[0049] Typical examples of such electrolyte additives include at least one SEI film-forming additive selected from the group consisting of cyclic carbonate compounds, halogen-substituted carbonate compounds, sultone compounds, sulfate compounds, phosphate compounds, borate compounds, nitrile compounds, benzene compounds, amine compounds, silane compounds, and lithium salt compounds.

[0050] Examples of the aforementioned cyclic carbonate compounds include vinylethylene carbonate.

[0051] Examples of the halogen-substituted carbonate compounds include fluoroethylene carbonate (FEC).

[0052] The sultone compounds include at least one compound selected from the group consisting of 1,4-butanesultone, ethensultone, 1,3-propensultone (PRS), 1,4-butensultone, and 1-methyl-1,3-propensultone.

[0053] Examples of the sulfate compounds include ethylene sulfate (Esa), trimethylene sulfate (TMS), or methyl trimethylene sulfate (MTMS).

[0054] The phosphate compounds include one or more compounds selected from the group consisting of lithium difluoro(bisoxalate) phosphate, lithium difluorophosphate, tetramethyltrimethylsilyl phosphate, trimethylsilyl phosphate, tris(2,2,2-trifluoroethyl) phosphate, and tris(trifluoroethyl) phosphate.

[0055] Examples of the borate compounds include tetraphenyl borate, lithium oxalyl difluoroborate (LiODFB), and lithium bisoxalate borate (LiB(C2O4)2, LiBOB).

[0056] The nitrile compounds include at least one compound selected from the group consisting of succinonitrile, adiponitrile, acetonitrile, propionitrile, butyronitrile, valeronitrile, caprylonitrile, heptanenitrile, cyclopentanecarbonile, cyclohexanecarbonile, 2-fluorobenzonitrile, 4-fluorobenzonitrile, difluorobenzonitrile, trifluorobenzonitrile, phenylacetonitrile, 2-fluorophenylacetonitrile, and 4-fluorophenylacetonitrile.

[0057] Examples of the benzene-based compound include fluorobenzene, examples of the amine-based compound include triethanolamine or ethylenediamine, and examples of the silane-based compound include tetravinylsilane.

[0058] Examples of the lithium salt-based compounds that differ from the lithium salts contained in the non-aqueous electrolyte include LiBF4.

[0059] The electrolyte may further contain compounds selected from the group consisting of succinonitrile, propargyl-1H-imidazole-1-carboxylate, and methyl-prop-2-ynyl carbonate. When such additives are further included, a stronger SEI film can be formed on the surface of the negative electrode during the initial activation process of the secondary battery, suppressing the generation of gases that may be produced by the decomposition of the electrolyte at high temperatures and improving the high-temperature stability of the secondary battery.

[0060] The cylindrical lithium secondary battery according to the present invention can be a large cylindrical battery having a form factor ratio (defined as the ratio of the diameter (Φ) to the height (H) of the cylindrical battery, i.e., the ratio of the diameter (Φ) to the height (H)) of 0.4 or more. Here, the form factor refers to the values ​​indicating the diameter and height of the cylindrical battery.

[0061] The cylindrical battery according to the present invention can be, for example, a 46110 cell (diameter 46 mm, height 110 mm, form factor ratio 0.418), a 4875 cell (diameter 48 mm, height 75 mm, form factor ratio 0.640), a 48110 cell (diameter 48 mm, height 110 mm, form factor ratio 0.436), a 4880 cell (diameter 48 mm, height 80 mm, form factor ratio 0.600), a 4680 cell (diameter 46 mm, height 80 mm, form factor ratio 0.575), or a 4695 cell (diameter 46 mm, height 95 mm, form factor ratio 0.484). In the numerical value indicating the form factor, the first two digits indicate the diameter of the cell, and the next two or three digits indicate the height of the cell.

[0062] The cylindrical lithium secondary battery according to the present invention significantly reduces the amount of gas generated compared to conventional batteries, thereby achieving excellent stability even in large cylindrical batteries with a form factor ratio of 0.4 or higher.

[0063] The electrode assembly included in the cylindrical lithium secondary battery of the present invention is a jelly-roll type electrode assembly having a structure in which a positive electrode plate, a negative electrode plate, and a separator interposed between the positive electrode plate and the negative electrode plate are wound in one direction.

[0064] Figure 1 shows the laminated structure of the electrode assembly according to the present invention before winding, and Figure 2 shows the cross-sectional structure of the electrode plate (positive electrode plate or negative electrode plate) according to the present invention.

[0065] Referring to Figures 1 and 2, the electrode assembly A of the present invention can be manufactured by winding a laminate formed by stacking a separator 12, a positive electrode plate 10, another separator 12, and a negative electrode plate 11 in order at least once, in one direction X.

[0066] Here, the positive electrode plate 10 and the negative electrode plate 11 have a structure in which an active material layer 21 is formed on a long sheet-shaped current collector 20, and the current collector 20 may include a plain portion 22 in which the active material layer 21 is not formed.

[0067] As described above, by using a positive electrode plate 10 and a negative electrode plate 11 that include a blank portion 22, it is possible to realize a tab-less battery structure in which at least a portion of the blank portions of the positive electrode plate 10 and the negative electrode plate 11 defines an electrode tab, without the need for a separate electrode tab.

[0068] Specifically, the blank portion 22 can be formed along the winding direction X at one end of the current collector 20, and a current collector plate can be attached to the blank portion of the positive electrode plate and the blank portion of the negative electrode plate, and the current collector plate can be connected to the electrode terminals to realize a tab-less battery structure.

[0069] For example, a tab-less battery can be manufactured by the following method. First, a separator, a positive electrode plate, a separator, and a negative electrode plate are stacked in order so that the blank portions 22 of the positive electrode plate 10 and the negative electrode plate 11 are positioned in opposite directions, and then wound in one direction to manufacture a jelly-roll type electrode assembly. After that, the blank portions 22 of the positive electrode plate and the negative electrode plate are bent in the direction of the winding center C, and then current collector plates are welded to the blank portions of the positive electrode plate and the negative electrode plate, respectively, and the current collector plates are connected to the electrode terminals to manufacture a tab-less battery. On the other hand, the current collector plate has a larger cross-sectional area than a strip-type electrode tab, and since resistance is inversely proportional to the cross-sectional area of ​​the current-flowing path, the cell resistance can be greatly reduced when a secondary battery is formed with the above structure.

[0070] On the other hand, the plain portions of the positive and negative electrode plates may be processed into a plurality of independently bendable segmented pieces, and at least a portion of the plurality of segmented pieces may be bent toward the winding center C of the electrode assembly.

[0071] The segmented pieces can be formed by processing the current collectors of the positive and negative electrode plates using metal foil cutting processes such as laser cutting, ultrasonic cutting, and punching.

[0072] When the plain areas of the positive and negative electrode plates are processed into the form of multiple segmented pieces, the stress applied to the plain areas during bending can be reduced, preventing deformation and damage to the plain areas, and improving the welding characteristics with the current collector plate.

[0073] The current collector plate and the blank section are generally joined by welding, and to improve welding properties, strong pressure must be applied to the weld area of ​​the blank section to bend it as flat as possible. However, during such bending, the shape of the blank section may be irregularly distorted and deformed, and the deformed area may come into contact with the opposite polarity electrode, causing an internal short circuit, or cause microscopic cracks in the blank section. However, if the blank sections of the positive and negative electrode plates are processed into the form of multiple independently bendable segmented pieces, the stress applied to the blank section during bending can be reduced, minimizing deformation and damage to the blank section.

[0074] Furthermore, if the plain portion is processed into the form of segmented pieces as described above, overlapping occurs between multiple segmented pieces when bent, which increases the welding strength with the current collector plate. This prevents the problem of the laser penetrating into the electrode assembly and melting the separator or active material when using advanced technologies such as laser welding. Preferably, at least a portion of the bent segmented pieces may overlap on the upper and lower ends of the electrode assembly, and the current collector plate can be bonded to the overlapping segmented pieces.

[0075] On the other hand, the cylindrical battery according to the present invention may preferably be a tab-less battery that does not include electrode tabs, but is not limited thereto.

[0076] The aforementioned tab-less battery may have a structure in which, for example, the positive electrode plate and the negative electrode plate each include a blank portion where no active material layer is formed, the blank portions of the positive electrode plate and the negative electrode plate are located at the upper and lower ends of the electrode assembly, a current collector plate is bonded to the blank portions of the positive electrode plate and the negative electrode plate, and the current collector plate is connected to the electrode terminals. The cylindrical lithium secondary battery according to the present invention may have a structure in which the blank portions of the positive electrode plate and the negative electrode plate serve as electrode tabs without forming separate electrode tabs (for example, a tab-less structure). In the case of conventional cylindrical batteries in which electrode tabs are formed, a large amount of current is concentrated on the electrode tabs during charging, generating a large amount of heat around the electrode tabs. In particular, during rapid charging, this phenomenon becomes severe and there is a risk of the battery igniting or exploding. In contrast, the cylindrical lithium secondary battery with a tabless structure according to the present invention can be formed in which blank areas where no active material layer is formed at the ends of the positive electrode plate and the negative electrode plate are formed, and these blank areas are connected to the electrode terminals by welding them to a current collector plate having a wide cross-sectional area. Since such a tabless battery has less current concentration compared to conventional batteries with electrode tabs, heat generation inside the battery can be effectively reduced, thereby improving the thermal stability of the battery and suppressing a decrease in output characteristics.

[0077] Figure 3 shows a cross-sectional view of a cylindrical battery with a tabless structure according to one embodiment of the present invention. The cylindrical battery according to one embodiment of the present invention will be described below with reference to Figure 3. However, Figure 3 is merely an illustration of one embodiment of the present invention, and the structure of the cylindrical battery of the present invention is not limited to the scope disclosed in Figure 3.

[0078] A cylindrical battery 140 according to one embodiment of the present invention includes the jelly-roll type electrode assembly 141 described above, a battery can 142 in which the electrode assembly 141 is housed, and a seal 143 that seals the open end of the battery can 142.

[0079] Here, the positive and negative electrode plates of the electrode assembly may each include a blank portion where no active material layer is formed, and the electrode assembly can be laminated and wound up such that the blank positive and negative electrode portions are located at the upper and lower ends, respectively. Since the electrode assembly has been described in detail, only the remaining components other than the electrode assembly will be described below.

[0080] The battery can 142 is a cylindrical container with an opening formed at the top, and is made of a conductive metal material such as aluminum or steel. The battery can houses the electrode assembly 141 in its inner space through the upper opening, and also houses the electrolyte (not shown).

[0081] The battery casing 142 is electrically connected to the blank portion 146b of the negative electrode plate and functions as a negative electrode terminal, contacting an external power source and transmitting the current applied from the external power source to the negative electrode plate.

[0082] If necessary, a beading portion 147 and a crimping portion 148 may be provided at the upper end of the battery can 142. The beading portion 147 can be formed by press-fitting the periphery of the outer surface of the battery can 142 to a distance D1. The beading portion 147 can function as a support portion on which the seal 143 is placed, preventing the electrode assembly 141 housed inside the battery can 142 from detaching through the upper end opening of the battery can 142.

[0083] The crimping portion 148 can be formed on the upper part of the beading portion 147 and has an extended and folded shape that encloses the outer circumferential surface and a portion of the upper surface of the cap plate 143a which is placed on the beading portion 147.

[0084] Next, the sealing body 143 is for sealing the open end of the battery can 142 and includes a cap plate 143a and a first gasket 143b that provides airtightness and insulation between the cap plate 143a and the battery can 142, and may further include a connecting plate 143c electrically and mechanically coupled to the cap plate 143a as needed. The cap plate 143a can be crimped onto a beading portion 147 formed on the battery can 142 and fixed by a crimping portion 148.

[0085] The cap plate 143a is a component made of a conductive metal material and covers the upper opening of the battery can 142. The cap plate 143a is electrically connected to the positive electrode plate of the electrode assembly 141 and electrically insulated from the battery can 142 via the first gasket 143b. Therefore, the cap plate 143a can function as the positive electrode terminal of the cylindrical secondary battery. The cap plate 143a may have a projection 143d that protrudes upward from its center C, and the projection 143d can come into contact with an external power source so that current can be applied from the external power source.

[0086] A first gasket 143b can be interposed between the cap plate 143a and the crimping portion 148 to ensure airtightness of the battery can 142 and to provide electrical insulation between the battery can 142 and the cap plate 143a.

[0087] On the other hand, the cylindrical battery 140 according to the present invention may further include current collector plates 144 and 145 as needed. The current collector plates are coupled to the blank portion 146a of the positive electrode plate and the blank portion 146b of the negative electrode plate and are connected to the electrode terminals (i.e., the positive electrode terminal and the negative electrode terminal).

[0088] Specifically, the cylindrical battery 140 according to the present invention may include a first current collector plate 144 coupled to the upper part of the electrode assembly 141 and a second current collector plate 145 coupled to the lower part of the electrode assembly 141, and may further include the first current collector plate 144 and / or the second current collector plate 145.

[0089] The first current collector plate 144 is coupled to the upper part of the electrode assembly 141. The first current collector plate 144 is made of a conductive metal material such as aluminum, copper, or nickel, and is electrically connected to the blank portion 146a of the positive electrode plate. A lead 149 can be coupled to the first current collector plate 144. The lead 149 can extend above the electrode assembly 141 and be coupled to the coupling plate 143c, or it can be directly coupled to the lower surface of the cap plate 143a. The lead 149 can be coupled to other components by welding. Preferably, the first current collector plate 144 can be formed integrally with the lead 149. In this case, the lead 149 can have a long plate shape extending outward from the center of the first current collector plate 144.

[0090] On the other hand, the first current collector plate 144 is coupled to the end of the blank portion 146a of the positive electrode plate, and this coupling can be performed by methods such as laser welding, resistance welding, ultrasonic welding, or soldering.

[0091] The second current collector plate 145 is coupled to the lower part of the electrode assembly 141. The second current collector plate 145 is made of a conductive metal material such as aluminum, copper, or nickel, and is electrically connected to the blank portion 146b of the negative electrode plate. One side of the second current collector plate 145 can be coupled to the blank portion 146b of the negative electrode plate, and the opposite side can be coupled to the inner bottom surface of the battery can 142. Here, the coupling can be performed by methods such as laser welding, resistance welding, ultrasonic welding, or soldering.

[0092] On the other hand, the cylindrical battery 140 according to the present invention may further include an insulator 146 as needed. The insulator 146 may be positioned to cover the upper surface of the first current collector plate 144. By covering the first current collector plate 144 with the insulator 146, it is possible to prevent the first current collector plate 144 from directly contacting the inner surface of the battery can 142.

[0093] The insulator 146 is provided with a lead hole 151 to allow a lead 149 extending upward from the first current collector plate 144 to be drawn out. The lead 149 is drawn out upward through the lead hole 151 and coupled to the underside of the coupling plate 143c or the underside of the cap plate 143a.

[0094] The insulator 146 can be made of an insulating polymer resin, such as polyethylene, polypropylene, polyimide, or polybutylene terephthalate.

[0095] On the other hand, the cylindrical battery 140 according to the present invention may further include a venting portion 152 formed on the lower surface of the battery can 142, if necessary. The venting portion 152 corresponds to a region on the lower surface of the battery can 142 that has a thinner thickness than the surrounding region. Because the venting portion 152 is thin, it is structurally more brittle than the surrounding region. Therefore, if the pressure inside the cylindrical battery 140 increases above a predetermined level, the venting portion 152 will rupture, releasing the gas inside the battery can 152 to the outside, thus preventing the battery from exploding.

[0096] Figure 4 shows a cross-sectional view of a cylindrical battery with a tabless structure according to another embodiment of the present invention. The cylindrical battery according to another embodiment of the present invention will be described below with reference to Figure 4. However, Figure 4 shows one embodiment of the present invention, and the structure of the cylindrical battery of the present invention is not limited to the scope disclosed in Figure 4.

[0097] Referring to Figure 4, the cylindrical battery 170 according to another embodiment of the present invention differs from the cylindrical battery 140 shown in Figure 3 in the structure of the battery case and the sealing body, while the electrode assembly and electrolyte configuration are substantially the same.

[0098] Specifically, the cylindrical battery 170 includes a battery case 171 through which a rivet terminal 172 is driven. The rivet terminal 172 is installed on a partially closed closed surface (the top surface in the drawing) at one end of the battery case 171. The rivet terminal 172 is riveted into the through hole (the first opening at the first end) of the battery case 171 with an insulating second gasket 173 interposed between them. The rivet terminal 172 is exposed to the outside in the direction opposite to the direction of gravity.

[0099] The rivet terminal 172 includes a terminal exposure portion 172a and a terminal insertion portion 172b. The terminal exposure portion 172a is exposed to the outside of the closed surface of the battery can 171. The terminal exposure portion 172a can be located approximately in the center of the partially closed surface of the battery can 171. The maximum diameter of the terminal exposure portion 172a can be made larger than the maximum diameter of the through hole formed in the battery can 171. The terminal insertion portion 172b can penetrate approximately in the center of the closed surface of the battery can 171 and be electrically connected to the blank portion 146a of the positive electrode plate. The terminal insertion portion 172b can be rivet-bonded to the inner surface of the battery can 171. That is, the end of the terminal insertion portion 172b can have a shape that is distorted toward the inner surface of the battery can 171. The maximum diameter of the end of the terminal insertion portion 172b can be larger than the maximum diameter of the through hole in the battery can 171.

[0100] The lower end surface of the terminal insertion portion 172b can be welded to the first current collector plate 144, which is connected to the blank portion 146a of the positive electrode plate. An insulating cap 174 made of an insulating material can be interposed between the first current collector plate 144 and the inner surface of the battery can 171. The insulating cap 174 covers the upper part of the first current collector plate 144 and the peripheral portion of the upper end of the electrode assembly 141. This prevents the blank portion B3 on the outer circumference of the electrode assembly 141 from coming into contact with the inner surface of the battery can 171, which has a different polarity, and causing a short circuit. The terminal insertion portion 172b of the rivet terminal 172 can pass through the insulating cap 174 and be welded to the first current collector plate 144.

[0101] The second gasket 173 is interposed between the battery can 171 and the rivet terminal 172 to prevent electrical contact between the battery can 171 and the rivet terminal 172, which have opposite polarities. As a result, the top surface of the battery can 171, which has a nearly flat shape, can function as the positive terminal of the cylindrical battery 170.

[0102] The second gasket 173 includes a gasket exposed portion 173a and a gasket inserted portion 173b. The gasket exposed portion 173a is interposed between the terminal exposed portion 172a of the rivet terminal 172 and the battery can 171. The gasket inserted portion 173b is interposed between the terminal inserted portion 172b of the rivet terminal 172 and the battery can 171. The gasket inserted portion 173b deforms together with the terminal inserted portion 172b during reveting, and can adhere tightly to the inner surface of the battery can 171. The second gasket 173 can be made of, for example, an insulating polymer resin.

[0103] The gasket exposed portion 173a of the second gasket 173 may have an extended shape that covers the outer circumferential surface of the terminal exposed portion 172a of the rivet terminal 172. When the second gasket 173 covers the outer circumferential surface of the rivet terminal 172, it is possible to prevent short circuits from occurring during the process of connecting electrical connecting components such as busbars to the upper surface of the battery can 171 and / or the rivet terminal 172. Although not shown in the drawings, the gasket exposed portion 173a may have an extended shape that covers not only the outer circumferential surface of the terminal exposed portion 172a but also a part of the upper surface.

[0104] When the second gasket 173 is made of a polymer resin, the second gasket 173 can be bonded to the battery can 171 and the rivet terminal 172 by heat fusion. In this case, the airtightness at the bonding interface between the second gasket 173 and the rivet terminal 172 and the bonding interface between the second gasket 173 and the battery can 171 can be enhanced. On the other hand, when the gasket exposed portion 173a of the second gasket 173 extends to the upper surface of the terminal exposed portion 172a, the rivet terminal 172 can be integrally bonded to the second gasket 173 by insert injection.

[0105] The remaining area 175 on the top surface of the battery can 171, excluding the area occupied by the rivet terminal 172 and the second gasket 173, corresponds to the negative terminal having the opposite polarity to the rivet terminal 172.

[0106] The second current collector plate 176 is connected to the lower part of the electrode assembly 141. The second current collector plate 176 is made of a conductive metal material such as aluminum, steel, copper, or nickel, and is electrically connected to the blank portion 146b of the negative electrode plate.

[0107] Preferably, the second current collector plate 176 is electrically connected to the battery can 171. For this purpose, at least a portion of the peripheral edge of the second current collector plate 176 can be interposed and fixed between the inner surface of the battery can 171 and the first gasket 178b. As an example, at least a portion of the peripheral edge of the second current collector plate 176 can be fixed to the beading portion 180 formed at the lower end of the battery can 171 by welding, while being supported by the lower end surface of the beading portion 180. In a modified example, at least a portion of the peripheral edge of the second current collector plate 176 can be directly welded to the inner wall surface of the battery can 171.

[0108] The second current collector plate 176 may have a plurality of radially arranged bumps (not shown) on the surface facing the plain portion 146b. If bumps are formed, the second current collector plate 176 can be pressed to press the bumps into the plain portion 146b.

[0109] Preferably, the end of the second current collector plate 176 and the blank portion 146b can be joined by welding, for example, laser welding.

[0110] The sealing body 178 that seals the lower open end of the battery can 171 includes a cap plate 178a and a first gasket 178b. The first gasket 178b electrically isolates the cap plate 178a from the battery can 171. The crimping portion 181 secures both the periphery of the cap plate 178a and the first gasket 178b. The cap plate 178a is provided with a vent portion 179. The configuration of the vent portion 179 is substantially the same as that of the embodiment described above.

[0111] Preferably, the cap plate 178a is made of a conductive metal material. However, since the first gasket 178b is interposed between the cap plate 178a and the battery can 171, the cap plate 178a does not have electrical polarity. The seal 178 seals the open end at the bottom of the battery can 171 and functions to release gas when the internal pressure of the battery cell 170 increases above a critical value.

[0112] Preferably, the rivet terminal 172 electrically connected to the blank portion 146a of the positive electrode plate is used as the positive electrode terminal. In addition, the portion 175 of the upper surface of the battery can 171, other than the rivet terminal 172, which is electrically connected to the blank portion 146b of the negative electrode plate via the second current collector plate 176, is used as the negative electrode terminal. In this way, when the two electrode terminals are located on the top of the cylindrical battery, electrical connecting components such as busbars can be placed on only one side of the cylindrical battery 170. This can lead to a simplification of the battery pack structure and an improvement in energy density. Furthermore, since the portion 175 used as the negative electrode terminal has a substantially flat shape, a sufficient contact area can be secured when joining electrical connecting components such as busbars. As a result, the cylindrical battery 170 can reduce the resistance at the joint of the electrical connecting components to a desirable level.

[0113] The cylindrical lithium secondary battery of the present invention, as described above, can be used to manufacture a battery pack. Figure 6 schematically illustrates the configuration of a battery pack according to an embodiment of the present invention. Referring to Figure 6, the battery pack 3 according to an embodiment of the present invention includes an assembly of electrically connected cylindrical secondary batteries 1 and a pack housing 2 that houses them. The cylindrical secondary battery 1 is a battery cell according to the embodiment described above. For convenience of illustration, the drawings omit the depiction of components such as busbars for the electrical connection of the cylindrical secondary battery 1, cooling units, and external terminals.

[0114] Battery pack 3 can be installed in a vehicle. The vehicle may, for example, be an electric vehicle, a hybrid vehicle, or a plug-in hybrid vehicle. The vehicle may include four-wheeled vehicles or two-wheeled vehicles.

[0115] Figure 7 is a diagram illustrating the automobile including the battery pack 3 shown in Figure 6.

[0116] Referring to Figure 7, an automobile 5 according to one embodiment of the present invention includes a battery pack 3 according to one embodiment of the present invention and operates by receiving power from the battery pack 3.

[0117] On the other hand, the electrode assembly according to the present invention can be formed in a structure in which an insulating layer 24 is further formed on the positive electrode plate 10, as shown in Figure 5. Specifically, the insulating layer 24 can be formed in a direction parallel to the winding direction of the electrode assembly so as to cover a part of the positive electrode active material layer and a part of the plain area.

[0118] In a tabless battery structure where the blank portion 22c of the positive electrode plate 10 and the blank portion 22a of the negative electrode plate 11 are used as electrode tabs, the electrode assembly is formed so that the positive electrode plate 10 protrudes above the separator 12 and the negative electrode plate 11 protrudes below the separator 12. The protruding positive electrode plate 10 and / or negative electrode plate 11 are then bent and coupled to the current collector plate. However, when the positive electrode plate 10 or negative electrode plate 11 is bent as described above, the current collector of the positive electrode plate 10 or negative electrode plate 11 is positioned to extend beyond the separator and come into close proximity to the electrode of opposite polarity. This can cause the positive and negative electrode plates to make electrical contact and potentially cause an internal short circuit. However, as illustrated in Figure 5, if an insulating layer 24 is formed that covers the positive electrode active material layer and a portion of the blank portion, the insulating layer 24 can prevent the positive electrode plate 10 and negative electrode plate 11 from making electrical contact, thereby preventing a short circuit from occurring inside the battery.

[0119] Preferably, the insulating layer 24 can be provided on at least one surface of the current collector of the positive electrode plate 10, and preferably on both sides of the positive electrode plate 10.

[0120] Furthermore, the insulating layer 24 can be formed in the region of the positive electrode plate 10 that may face the active material layer 21a of the negative electrode plate 11. For example, on the blank portion 22c of the positive electrode plate 10 that faces the negative electrode plate 11 after being bent, the insulating layer 24 can be formed extending to the end of the blank portion 22c. However, on the opposite side of the blank portion that faces the negative electrode plate 11 after being bent, it is preferable that the insulating layer 24 be formed in a portion of the blank portion 22c, for example, before the bending point of the blank portion 22c. This is because if the insulating layer 24 is formed over the entire area of ​​the blank portion on the opposite side of the blank portion that faces the negative electrode plate 11, electrical contact with the current collector plate becomes impossible, and it cannot function as an electrode tab.

[0121] On the other hand, the insulating layer 24 only needs to ensure insulating performance and be able to adhere to the positive electrode plate, and its material and components are not particularly limited. For example, the insulating layer can be an insulating coating layer or an insulating tape, and the insulating coating layer can include an organic binder and inorganic particles. Here, the organic binder can be, for example, styrene-butadiene rubber (SBR), and the inorganic particles can be alumina oxide, but are not limited to these.

[0122] Next, each component of the electrode assembly of the present invention will be described in more detail.

[0123] (1) Positive plate The positive electrode plate may have a structure in which a positive electrode active material layer is formed on one or both sides of a long sheet-shaped positive electrode current collector, and the positive electrode active material layer may include a positive electrode active material, a conductive material, and a binder.

[0124] Specifically, the positive electrode plate can be manufactured by applying a positive electrode slurry, which is prepared by dispersing a positive electrode active material, a conductive material, and a binder in a solvent such as dimethyl sulfoxide (DMSO), isopropyl alcohol, N-methylpyrrolidone (NMP), acetone, or water, to one or both sides of a long sheet-shaped positive electrode current collector, removing the solvent from the positive electrode slurry in a drying process, and then rolling it. On the other hand, a positive electrode plate including a blank 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.

[0125] Various 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 can usually have a thickness of 3 to 500 μm, and fine irregularities can be formed on the surface of the positive electrode current collector to increase the adhesion strength of the positive electrode active material. The positive electrode current collector can be used in various forms, such as film, sheet, foil, mesh, porous material, foam, nonwoven fabric, etc.

[0126] On the other hand, as the positive electrode active material, a positive electrode active material commonly used in the art can be used.

[0127] Preferably, the positive electrode active material may include a lithium nickel-based oxide, specifically a lithium nickel-based oxide containing 85 mol% or more of Ni relative to the total number of moles of the transition metal. Preferably, the lithium nickel-based oxide may contain Ni in amounts of 85 mol% or more but less than 100 mol%, 86 mol% or more but less than 100 mol%, or 88 mol% or more but less than 100 mol%. When a lithium nickel-based oxide with a high Ni content as described above is used, high capacity can be achieved.

[0128] More specifically, the positive electrode active material may include a lithium nickel-based oxide represented by the following [Chemical Formula 1]. [Chemical formula 1] Li a Ni b Co c M 1 d M 2 e O2 In the above chemical formula 1, M 1 This can be Mn, Al, or a combination thereof, preferably Mn or Mn and Al.

[0129] Said M 2 This is one or more selected from the group consisting of Zr, W, Y, Ba, Ca, Ti, Mg, Ta, and Nb, preferably one or more selected from the group consisting of Zr, Y, Mg, and Ti, and more preferably Zr, Y, or a combination thereof. 2 Elements are not always present, but when present in appropriate amounts, they can promote grain growth during firing or improve the stability of the crystal structure.

[0130] The above 'a' represents the molar ratio of lithium in the lithium nickel 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 oxide can be stably formed.

[0131] The aforementioned b represents the molar ratio of nickel to the total metals other than lithium in the lithium nickel oxide, and can be 0.85 ≤ b < 1, 0.86 ≤ b < 1, or 0.88 ≤ b < 1. When the molar ratio of nickel satisfies the above range, a high energy density is observed, enabling the realization of high capacity.

[0132] Said c represents the molar ratio of cobalt among all the metals other than lithium in the lithium nickel-based oxide, and can be 0 < c < 0.15, 0 < c < 0.14, or 0.01 ≤ c ≤ 0.12. When the molar ratio of cobalt satisfies the above range, good resistance characteristics and output characteristics can be realized.

[0133] Said d represents the molar ratio of element M among all the metals other than lithium in the lithium nickel-based oxide, and can be 0 < d < 0.15, 0 < d < 0.14, or 0.01 ≤ d ≤ 0.12. 1 When the molar ratio of element M satisfies the above range, the positive electrode active material exhibits excellent structural stability. 1

[0134] Said e represents the molar ratio of element M among all the metals other than lithium in the lithium nickel-based oxide, and can be 0 ≤ e ≤ 0.1 or 0 ≤ e ≤ 0.05. 2

[0135] On the other hand, the positive electrode active material according to the present invention can further include a coating layer containing one or more coating elements selected from the group consisting of Al, Ti, W, B, F, P, Mg, Ni, Co, Fe, Cr, V, Cu, Ca, Zn, Zr, Nb, Mo, Sr, Sb, Bi, Si, and S on the surface of the lithium nickel-based oxide particles as needed. Preferably, the coating element can be Al, B, Co, or a combination thereof, and most preferably, the coating element can be B.

[0136] When a coating layer exists on the surface of the lithium nickel-based oxide particles, the coating layer suppresses the contact between the electrolyte and the lithium composite transition metal oxide, thereby obtaining the effect of reducing the elution of transition metals and the generation of gas due to the side reaction with the electrolyte.

[0137] The positive electrode active material can be contained in an amount of 80 to 99% by weight, preferably 85 to 99% by weight, and more preferably 90 to 99% by weight based on the total weight of the positive electrode active material layer.

[0138] On the other hand, the positive electrode active material is not particularly limited in its form and can be in the form of secondary particles formed by the aggregation of multiple primary particles, or in the form of a single particle consisting of one primary particle, or a combination of these forms.

[0139] Preferably, the positive electrode active material may include a positive electrode active material consisting of a single particle made up of one primary particle and / or a pseudo-single particle, which is an aggregate of 10 or fewer primary particles. By using a positive electrode active material consisting of a single particle made up of one primary particle and / or a pseudo-single particle, which is an aggregate of 10 or fewer primary particles, a large cylindrical battery with high capacity and excellent stability can be obtained.

[0140] Traditionally, spherical secondary particles, composed of tens to hundreds of primary particles aggregated together, have been commonly used as the positive electrode active material for lithium secondary batteries. However, in the case of positive electrode active materials in the form of secondary particles aggregated from many primary particles, particle cracking, where primary particles detach during the rolling process, is likely to occur during the manufacturing of the positive electrode, and cracks can develop inside the particles during the charge and discharge process. When particle cracking or internal cracks occur 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 pressure inside the battery, potentially causing the battery to explode. In particular, when the volume of a cylindrical battery is increased, the amount of active material inside the battery increases, which significantly increases the amount of gas generated, further increasing the risk of battery ignition and / or explosion.

[0141] In contrast, positive electrode active materials in the form of single particles or pseudo-single particles, where 10 or fewer primary particles are aggregated, have higher particle strength compared to existing positive electrode active materials in the form of secondary particles, where tens to hundreds of primary particles are aggregated. As a result, particle cracking during rolling is almost nonexistent. Furthermore, in the case of single-particle or pseudo-single-particle positive electrode active materials, the small number of primary particles that make up the particle reduces the volume expansion and contraction of the primary particles during charging and discharging, which significantly reduces the occurrence of cracks inside the particle.

[0142] Therefore, when using a positive electrode active material consisting of single particles and / or pseudo-single particles, the amount of gas generated due to particle cracking and internal cracking can be significantly reduced, thereby achieving excellent stability even in large cylindrical batteries.

[0143] On the other hand, the positive electrode active material consisting of single particles and / or pseudo-single particles is preferably included in an amount of 95% to 100% by weight, preferably 98% to 100% by weight, more preferably 99% to 100% by weight, and even more preferably 100% by weight, relative to the total weight of the positive electrode active material contained in the positive electrode active material layer. When the content of single particles and / or pseudo-single particles satisfies the above range, sufficient stability can be obtained when applying to large cylindrical batteries.

[0144] On the other hand, the positive electrode active material in single-particle and / or pseudo-single-particle form according to the present invention has an average particle size D 50 The average particle size D of the positive electrode active material can be 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. 50 When the above range is satisfied, the increase in resistance can be minimized.

[0145] Single-particle and / or pseudo-single-particle cathode active materials have fewer interfaces between primary particles that serve as diffusion pathways for lithium ions within the particles. This results in reduced lithium mobility compared to secondary-particle cathode active materials, leading to increased resistance. This increase in resistance worsens with increasing particle size, and this increased resistance negatively impacts capacitance and power characteristics. Therefore, in this invention, the average particle size D 50 By applying single-particle or pseudo-single-particle cathode active materials with a diameter of 5 μm or less, the increase in resistance is suppressed by minimizing the lithium ion diffusion distance within the particles.

[0146] The positive electrode active material in single-particle and / or pseudo-single-particle form may have an average primary particle size of 5 μm or less, 4 μm or less, 3 μm or less, or 2 μm or less, for example, 0.5 μm to 5 μm, preferably 1 μm to 5 μm, and more preferably 2 μm to 5 μm. When the average primary particle size satisfies the above range, a positive electrode active material in single-particle and / or pseudo-single-particle form with excellent electrochemical properties can be formed. If the average primary particle size is too small, the number of aggregated primary particles forming the positive electrode active material increases, reducing the effect of suppressing particle cracking during rolling. If the average primary particle size is too large, the lithium diffusion path inside the primary particles becomes longer, increasing resistance and potentially degrading the output characteristics.

[0147] In the present invention, it is preferable that the positive electrode active material in single-particle and / or pseudo-single-particle form has a unimodal particle size distribution. Conventionally, in order to improve the electrode density of the positive electrode active material layer, bimodal positive electrode active materials have been widely used, which are made by mixing large-particle positive electrode active material with a large average particle size and small-particle positive electrode active material with a small average particle size. However, in the case of positive electrode active materials in single-particle or pseudo-single-particle form, as the particle size increases, the lithium migration path becomes longer and the resistance increases significantly. Therefore, when large-particle particles are mixed and used, problems may arise in which the capacity and output characteristics deteriorate. Accordingly, in the present invention, the increase in resistance can be minimized by using a positive electrode active material having a unimodal distribution.

[0148] Next, the conductive material is used to impart conductivity to the electrodes and can be used without particular limitations in the battery it is configured in, as long as it does not cause a chemical change and has electronic 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. One of these alone or a mixture of two or more can be used. The conductive material can usually be included in an amount of 1 to 30% by weight, preferably 1 to 20% by weight, and more preferably 1 to 10% by weight, relative to the total weight of the positive electrode active material layer.

[0149] 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), vinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HFP), polyvinyl alcohol, polyacrylonitrile, carboxymethylcellulose (CMC), starch, hydroxypropylcellulose, regenerated cellulose, polyvinylpyrrolidone, polytetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene monomer rubber (EPDM rubber), sulfonated EPDM, styrene-butadiene rubber (SBR), fluororubber, or various copolymers thereof, and one of these alone or a mixture of two or more can be used. The binder may be present in an amount of 1 to 30% by weight, preferably 1 to 20% by weight, and more preferably 1 to 10% by weight, based on the total weight of the positive electrode active material layer.

[0150] On the other hand, an insulating layer that covers a part of the positive electrode active material layer and a part of the non-coated portion can be further formed on the positive electrode plate according to the present invention. The insulating layer can be formed along a direction parallel to the winding direction of the electrode assembly.

[0151] (2) Negative electrode plate The negative electrode plate can have a structure in which a negative electrode active material layer is formed on one or both surfaces of a long sheet-shaped negative electrode current collector. The negative electrode active material layer can contain a negative electrode active material, a conductive material, and a binder.

[0152] Specifically, the negative electrode plate can be manufactured by applying a negative electrode slurry, which is produced by dispersing a negative electrode active material, a conductive material, and a binder in a solvent such as dimethyl sulfoxide (DMSO), isopropyl alcohol, N-methylpyrrolidone (NMP), acetone, or water, on one or both surfaces of a long sheet-shaped negative electrode current collector, removing the solvent of the negative electrode slurry by a drying process, and then rolling it. On the other hand, when applying the negative electrode slurry, a negative electrode plate including a non-coated portion can be manufactured by a method of not applying the negative electrode slurry to a partial region of the negative electrode current collector, for example, one end portion of the negative electrode current collector.

[0153] As the negative electrode active material, a compound capable of reversible intercalation and deintercalation of lithium can be used. Specific examples of the negative electrode active material include carbonaceous materials such as artificial graphite, natural graphite, graphitized carbon fiber, and amorphous carbon; silicon-based materials such as Si, Si-Me alloy (where Me is one or more selected from the group consisting of Al, Sn, Mg, Cu, Fe, Pb, Zn, Mn, Cr, Ti, and Ni), SiO y (where 0 < y < 2), Si-C composite, etc.; lithium metal thin film; metal materials capable of alloying with lithium such as Sn, Al, etc. These can be used alone or in combination of two or more of them.

[0154] Preferably, the negative electrode plate according to the present invention can contain 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), a Si-C composite, or a combination thereof, and preferably, it can be 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.

[0155] On the other hand, the silicon-based negative electrode active material can be doped with an M b metal, where the M b metal can be a Group 1 metal element or a Group 2 metal element, and specifically, it can be Li, Mg, etc. Specifically, the silicon negative electrode active material can be Si, SiO b doped with an M y (where 0 < y < 2), a Si-C composite, etc. In the case of a metal-doped silicon-based negative electrode active material, although the active material capacity decreases somewhat due to the doping element, a high energy density can be realized because it has high efficiency.

[0156] Also, the silicon-based negative electrode active material can further include a carbon coating layer on the surface of the particles. Here, the amount of the carbon coating can be 20% by weight or less, preferably 1 - 20% by weight, based on the total weight of the silicon-based negative electrode active material.

[0157] Also, the negative electrode plate can further contain a carbon-based negative electrode active material as a negative electrode active material as needed. The carbon-based negative electrode active material can be, for example, artificial graphite, natural graphite, graphitized carbon fiber, amorphous carbon, soft carbon, hard carbon, etc., but is not limited thereto.

[0158] On the other hand, 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 can be 1:99 to 20:80 by weight, preferably 1:99 to 15:85, and more preferably 1:99 to 10:90.

[0159] The negative electrode active material may be present in an amount of 80 to 99% by weight, preferably 85 to 99% by weight, and more preferably 90 to 99% by weight, relative to the total weight of the negative electrode active material layer.

[0160] On the other hand, as the negative electrode current collector, a negative electrode current collector commonly used in the art can be used, for example, copper, stainless steel, aluminum, nickel, titanium, calcined carbon, copper or stainless steel with surface treatment using carbon, nickel, titanium, silver, etc., or aluminum-cadmium alloy can be used. The negative electrode current collector can usually have a thickness of 3 to 500 μm, and, similar to the positive electrode current collector, fine irregularities can be formed on the surface of the current collector to strengthen the bonding force of the negative electrode active material. For example, it can be used in various forms such as film, sheet, foil, mesh, porous material, foam, nonwoven fabric.

[0161] The conductive material is used to impart conductivity to the negative electrode and can be used without particular limitations in the battery it is configured to use, as long as it does not cause chemical changes and has electronic 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. One of these alone or a mixture of two or more can be used. The conductive material can usually be contained in an amount of 1 to 30% by weight, preferably 1 to 20% by weight, and more preferably 1 to 10% by weight, relative to the total weight of the negative electrode active material layer.

[0162] The binder plays a role in improving adhesion between negative electrode active material particles and adhesion between the negative electrode active material and the negative electrode current collector. Specific examples include polyvinylidene fluoride (PVDF), vinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HFP), polyvinyl alcohol, polyacrylonitrile, carboxymethylcellulose (CMC), starch, hydroxypropylcellulose, regenerated cellulose, polyvinylpyrrolidone, polytetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene monomer rubber (EPDM rubber), sulfonated EPDM, styrene-butadiene rubber (SBR), fluororubber, or various copolymers thereof, of which one or more can be used. The binder may be present in an amount of 1 to 30% by weight, preferably 1 to 20% by weight, and more preferably 1 to 10% by weight, relative to the total weight of the negative electrode active material layer.

[0163] (3) Separator The separator separates the negative and positive electrodes and provides a passage for lithium ions to move. It can be used without particular limitations as long as it is a separator commonly used in lithium-ion secondary batteries. Specifically, the separator can be a porous polymer film, such as a porous polymer film made from polyolefin polymers like ethylene homopolymer, propylene homopolymer, ethylene / butene copolymer, ethylene / hexene copolymer, and ethylene / methacrylate copolymer, or a laminated structure of two or more layers thereof. Alternatively, a conventional porous nonwoven fabric, such as a nonwoven fabric made from high-melting-point glass fibers or polyethylene terephthalate fibers, can also be used. Furthermore, a coated separator containing ceramic components or polymeric substances may be used to ensure heat resistance or mechanical strength.

[0164] The present invention will be described in more detail below with reference to specific examples.

[0165] Examples Example 1 A non-aqueous solvent was prepared by dissolving LiPF6 in an organic solvent (ethylene carbonate (EC): ethyl methyl carbonate (EMC): dimethyl carbonate (DMC) = 20:5:75 by volume) to a concentration of 1.3 M. An electrolyte was then prepared by adding vinylene carbonate (VC) at a concentration of 3 wt%, 1,3-propanesultone (PS) at 1 wt%, LiPO2F2 at 0.25 wt%, succinonitrile at 0.2 wt%, and propargyl-1H-imidazole-1-carboxylate at 0.3 wt% relative to the total weight of the electrolyte.

[0166] average grain boundary D 50 The positive electrode active material Li[Ni] has a unimodal particle size distribution of 3 μm and is in single-particle form. 0.9 Co 0.06 Mn 0.03 Al 0.01A positive electrode slurry was prepared by mixing O2, carbon nanotubes, and a PVDF binder in a weight ratio of 97.8:0.6:1.6 in N-methylpyrrolidone. The 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 plate.

[0167] A negative electrode slurry was prepared by mixing a negative electrode active material (graphite:SiO=95:5 by weight ratio), 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 plate.

[0168] As described above, a separator was placed between the positive electrode plate and the negative electrode plate, and the plates were stacked in the order of separator / positive electrode plate / separator / negative electrode plate. After this stacking was completed, the assembly was wound up to produce a jelly-roll type electrode assembly. The electrode assembly produced as described above was inserted into a cylindrical battery case with a diameter of 46 mm and a height of 80 mm, and then the electrolyte was injected to produce a cylindrical lithium secondary battery.

[0169] Example 2 A non-aqueous solvent was prepared by dissolving LiPF6 in an organic solvent (ethylene carbonate (EC): ethyl methyl carbonate (EMC): dimethyl carbonate (DMC) = 20:5:75 by volume) to a concentration of 1.3 M. An electrolyte was then prepared by adding vinylene carbonate (VC) at 4% by weight, 1,3-propanesultone (PS) at 1% by weight, LiPO2F2 at 0.5% by weight, succinonitrile at 0.2% by weight, and propargyl-1H-imidazole-1-carboxylate at 0.3% by weight, relative to the total weight of the electrolyte.

[0170] A cylindrical lithium secondary battery was manufactured using the same method as in Example 1, except for the use of this electrolyte.

[0171] Example 3 A non-aqueous solvent was prepared by dissolving LiPF6 in an organic solvent (ethylene carbonate (EC): ethyl methyl carbonate (EMC): dimethyl carbonate (DMC) = 20:5:75 by volume) to a concentration of 1.3 M. An electrolyte was then prepared by adding vinylene carbonate (VC) at 4% by weight, 1,3-propanesultone (PS) at 0.5% by weight, LiPO2F2 at 1% by weight, succinonitrile at 0.2% by weight, and propargyl-1H-imidazole-1-carboxylate at 0.3% by weight, relative to the total weight of the electrolyte.

[0172] A cylindrical lithium secondary battery was manufactured using the same method as in Example 1, except for the use of this electrolyte.

[0173] Example 4 A non-aqueous solvent was prepared by dissolving LiPF6 in an organic solvent (ethylene carbonate (EC): ethyl methyl carbonate (EMC): dimethyl carbonate (DMC) = 20:5:75 by volume) to a concentration of 1.3 M. An electrolyte was then prepared by adding vinylene carbonate (VC) at a concentration of 2% by weight, 1,3-propanesultone (PS) at 0.5% by weight, LiPO2F2 at 0.25% by weight, succinonitrile at 0.2% by weight, and propargyl-1H-imidazole-1-carboxylate at 0.3% by weight, relative to the total weight of the electrolyte.

[0174] A cylindrical lithium secondary battery was manufactured using the same method as in Example 1, except for the use of this electrolyte.

[0175] Comparative Example 1 A non-aqueous solvent was prepared by dissolving LiPF6 in an organic solvent (ethylene carbonate (EC): ethyl methyl carbonate (EMC): dimethyl carbonate (DMC) = 20:5:75 by volume) to a concentration of 1.3 M. The electrolyte was then prepared by adding vinylene carbonate (VC) at a concentration of 2% by weight, 1,3-propanesultone (PS) at 1% by weight, succinonitrile at 0.2% by weight, and propargyl-1H-imidazole-1-carboxylate at 0.3% by weight, relative to the total weight of the electrolyte.

[0176] A cylindrical lithium secondary battery was manufactured using the same method as in Example 1, except for the use of this electrolyte.

[0177] Comparative Example 2 A non-aqueous solvent was prepared by dissolving LiPF6 in an organic solvent (ethylene carbonate (EC): ethyl methyl carbonate (EMC): dimethyl carbonate (DMC) = 20:5:75 by volume) to a concentration of 1.3 M. An electrolyte was then prepared by adding vinylene carbonate (VC) at 5% by weight, 1,3-propanesultone (PS) at 1% by weight, LiPO2F2 at 0.25% by weight, succinonitrile at 0.2% by weight, and propargyl-1H-imidazole-1-carboxylate at 0.3% by weight, relative to the total weight of the electrolyte.

[0178] A cylindrical lithium secondary battery was manufactured using the same method as in Example 1, except for the use of this electrolyte.

[0179] Comparative Example 3 A non-aqueous solvent was prepared by dissolving LiPF6 in an organic solvent (ethylene carbonate (EC): ethyl methyl carbonate (EMC): dimethyl carbonate (DMC) = 20:5:75 by volume) to a concentration of 1.3 M. An electrolyte was then prepared by adding vinylene carbonate (VC) at a concentration of 3.5 wt%, 1,3-propanesultone (PS) at 0.5 wt%, LiPO2F2 at 1.5 wt%, succinonitrile at 0.2 wt%, and propargyl-1H-imidazole-1-carboxylate at 0.3 wt% relative to the total weight of the electrolyte.

[0180] A cylindrical lithium secondary battery was manufactured using the same method as in Example 1, except for the use of this electrolyte.

[0181] Comparative Example 4 A non-aqueous solvent was prepared by dissolving LiPF6 in an organic solvent (ethylene carbonate (EC): ethyl methyl carbonate (EMC): dimethyl carbonate (DMC) = 20:5:75 by volume) to a concentration of 1.3 M. The electrolyte was then prepared by adding vinylene carbonate (VC) at a concentration of 3 wt%, 1,3-propanesultone (PS) at 0.5 wt%, LiPO2F2 at 0.1 wt%, succinonitrile at 0.2 wt%, and propargyl-1H-imidazole-1-carboxylate at 0.3 wt% relative to the total weight of the electrolyte.

[0182] A cylindrical lithium secondary battery was manufactured using the same method as in Example 1, except for the use of this electrolyte.

[0183] Comparative Example 5 An organic solvent (ethylene carbonate (EC): ethyl methyl carbonate (EMC): dimethyl carbonate (DMC) = 20:5:75 by volume ratio) was dissolved with LiPF6 to a concentration of 1.3 M to produce a non-aqueous solvent. To the total weight of the electrolyte, vinylene carbonate (VC) was added at 2 wt%, 1,3-propane sultone (PS) at 0.5 wt%, LiPO2F2 at 1 wt%, succinonitrile at 0.2 wt%, and propargyl-1H-imidazole-1-carboxylate at 0.3 wt% to produce an electrolyte.

[0184] A cylindrical lithium secondary battery was manufactured in the same manner as in Example 1, except that such an electrolyte was used.

[0185] Comparative Example 6 An organic solvent (ethylene carbonate (EC): ethyl methyl carbonate (EMC): dimethyl carbonate (DMC) = 20:5:75 by volume ratio) was dissolved with LiPF6 to a concentration of 1.3 M to produce a non-aqueous solvent. To the total weight of the electrolyte, vinylene carbonate (VC) was added at 3 wt%, 1,3-propane sultone (PS) at 1 wt%, LiPO2F2 at 0.25 wt%, succinonitrile at 0.2 wt%, and propargyl-1H-imidazole-1-carboxylate at 0.3 wt% to produce an electrolyte.

[0186] Average particle size D 50 has a unimodal particle size distribution with an average particle size of 3 μm and is in the form of single particles. The cathode active material Li[Ni 0.9 Co 0.06 Mn 0.03 Al 0.01 O2: carbon nanotubes: PVDF binder were mixed in N-methylpyrrolidone at a weight ratio of 97.8:0.6:1.6 to produce a cathode slurry. The cathode slurry was applied to one side of an aluminum current collector sheet, dried at 120 °C, and then rolled to produce a cathode plate.

[0187] A negative electrode slurry was prepared by mixing a negative electrode active material (graphite:SiO=95:5 by weight ratio), 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 plate.

[0188] As described above, a separator was placed between the positive electrode plate and the negative electrode plate, and the plates were stacked in the order of separator / positive electrode plate / separator / negative electrode plate. After stacking, the assembly was wound up to produce a jelly-roll type electrode assembly. The electrode assembly produced as described above was inserted into a cylindrical battery container with a diameter of 21 mm and a height of 70 mm, and the electrolyte was injected to produce a cylindrical lithium secondary battery.

[0189] Comparative Example 7 A non-aqueous solvent was prepared by dissolving LiPF6 in an organic solvent (ethylene carbonate (EC): ethyl methyl carbonate (EMC): dimethyl carbonate (DMC) = 20:5:75 by volume) to a concentration of 1.3 M. An electrolyte was then prepared by adding vinylene carbonate (VC) at 4% by weight, 1,3-propanesultone (PS) at 1% by weight, LiPO2F2 at 0.5% by weight, succinonitrile at 0.2% by weight, and propargyl-1H-imidazole-1-carboxylate at 0.3% by weight, relative to the total weight of the electrolyte.

[0190] Average particle size D 50 The positive electrode active material Li[Ni] has a unimodal particle size distribution of 3 μm and is in single-particle form. 0.9 Co 0.06 Mn 0.03 Al 0.01 A positive electrode slurry was prepared by mixing O2, carbon nanotubes, and a PVDF binder in a weight ratio of 97.8:0.6:1.6 in N-methylpyrrolidone. The 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 plate.

[0191] Negative electrode active material (mixture of graphite:SiO with a weight ratio of 95:5): conductive material (super C), styrene-butadiene rubber (SBR), 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 side of a copper current collector sheet, it was dried at 150 °C and then rolled to produce a negative electrode plate.

[0192] A separator was interposed between the positive electrode plate and the negative electrode plate manufactured as described above, and they were laminated in the order of separator / positive electrode plate / separator / negative electrode plate, and then wound up to manufacture a jelly-roll type electrode assembly. After inserting the electrode assembly manufactured as described above into a cylindrical battery can with a diameter of 21 mm and a height of 70 mm, the electrolyte was injected to manufacture a cylindrical lithium secondary battery.

[0193] Comparative Example 8 An organic solvent (ethylene carbonate (EC): ethyl methyl carbonate (EMC): dimethyl carbonate (DMC) = 20:5:75 by volume ratio) was dissolved so that LiPF6 became 1.3 M to produce a non-aqueous solvent. With respect to the total weight of the electrolyte, vinylene carbonate (VC) was 3 wt%, 1,3-propane sultone (PS) was 1 wt%, LiPO2F2 was 0.25 wt%, succinonitrile was 0.2 wt%, and propargyl-1H-imidazole-1-carboxylate was 0.3 wt% were added to produce an electrolyte.

[0194] Average particle size D 50 has a unimodal particle size distribution with an average particle size of 3 μm and is in the form of single particles. The positive electrode active material is Li[Ni 0.9 Co 0.06 Mn 0.03 Al 0.01A positive electrode slurry was prepared by mixing O2, carbon nanotubes, and a PVDF binder in a weight ratio of 97.8:0.6:1.6 in N-methylpyrrolidone. The 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 plate.

[0195] A negative electrode slurry was prepared by mixing a negative electrode active material (graphite:SiO=95:5 by weight ratio), 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 plate.

[0196] A separator was placed between the positive electrode plate and the negative electrode plate manufactured as described above, and the plates were stacked in the order of separator / positive electrode plate / separator / negative electrode plate. After this stacking was completed, the assembly was wound up to produce a jelly-roll type electrode assembly. The electrode assembly manufactured as described above was inserted into a cylindrical battery container with a diameter of 18 mm and a height of 65 mm, and the electrolyte was injected to produce a cylindrical lithium secondary battery.

[0197] Comparative Example 9 A non-aqueous solvent was prepared by dissolving LiPF6 in an organic solvent (ethylene carbonate (EC): ethyl methyl carbonate (EMC): dimethyl carbonate (DMC) = 20:5:75 by volume) to a concentration of 1.3 M. An electrolyte was then prepared by adding vinylene carbonate (VC) at 4% by weight, 1,3-propanesultone (PS) at 1% by weight, LiPO2F2 at 0.5% by weight, succinonitrile at 0.2% by weight, and propargyl-1H-imidazole-1-carboxylate at 0.3% by weight, relative to the total weight of the electrolyte.

[0198] Average particle size D 50 The positive electrode active material Li[Ni] has a unimodal particle size distribution of 3 μm and is in single-particle form. 0.9 Co 0.06 Mn0.03 Al 0.01 A positive electrode slurry was prepared by mixing O2, carbon nanotubes, and a PVDF binder in a weight ratio of 97.8:0.6:1.6 in N-methylpyrrolidone. The 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 plate.

[0199] A negative electrode slurry was prepared by mixing a negative electrode active material (graphite:SiO=95:5 by weight ratio), 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 plate.

[0200] A separator was placed between the positive electrode plate and the negative electrode plate manufactured as described above, and the plates were stacked in the order of separator / positive electrode plate / separator / negative electrode plate. After this stacking was completed, the assembly was wound up to produce a jelly-roll type electrode assembly. The electrode assembly manufactured as described above was inserted into a cylindrical battery container with a diameter of 18 mm and a height of 65 mm, and the electrolyte was injected to produce a cylindrical lithium secondary battery.

[0201] Experimental Example 1 - Evaluation of High-Temperature Lifetime Characteristics The high-temperature life characteristics of cylindrical lithium secondary batteries manufactured according to Examples 1-4 and Comparative Examples 1-9 were evaluated.

[0202] Specifically, for each of the cylindrical lithium secondary batteries manufactured according to Examples 1-4 and Comparative Examples 1-9, charging was performed at 45°C at a rate of 0.33C to 4.2V under CC-CV conditions, and discharging was performed at a rate of 0.33C to 2.5V under CC conditions. After performing 200 cycles of this charge-discharge process, the capacity retention rate relative to the initial capacity after 200 cycles was measured. The relative capacity retention rates are shown in Table 1 below, with the capacity retention rate relative to the initial capacity after 200 cycles (expressed as 100) of the cylindrical lithium secondary battery of Comparative Example 1 as the baseline.

[0203] [Table 1]

[0204] As shown in Table 1 above, it was confirmed that the cylindrical lithium secondary batteries of Examples 1 to 4 have superior high-temperature and lifespan characteristics compared to the cylindrical lithium secondary batteries of Comparative Examples 1 to 9.

[0205] Experimental Example 2 - Evaluation of Rapid Charging Characteristics The rapid charging characteristics of the cylindrical lithium secondary batteries manufactured according to Examples 1-4 and Comparative Examples 1-9 were evaluated.

[0206] Specifically, for each of the cylindrical lithium secondary batteries manufactured according to Examples 1-4 and Comparative Examples 1-9, charging was performed at 25°C at a rate of 2C to 4.2V under CC-CV conditions, and discharging was performed at a rate of 0.33C to 2.5V under CC conditions. After performing 100 cycles of this charge-discharge process, the capacity retention rate relative to the initial capacity after 100 cycles was measured. The relative capacity retention rates are shown in Table 2 below, with the capacity retention rate relative to the initial capacity after 100 cycles (expressed as 100) of the cylindrical lithium secondary battery of Comparative Example 1 as the baseline.

[0207] [Table 2]

[0208] As shown in Table 2 above, it was confirmed that the cylindrical lithium secondary batteries of Examples 1 to 4 have superior rapid charging characteristics compared to the cylindrical lithium secondary batteries of Comparative Examples 1 to 9.

Claims

1. A cylindrical lithium secondary battery comprising a positive electrode plate, a negative electrode plate, a jelly-roll type electrode assembly in which a separator interposed between the positive and negative electrode plates is wound in one direction, a battery case in which the electrode assembly is housed, an electrolyte poured into the battery case, and a seal that seals the open end of the battery case, The form factor ratio is 0.4 or higher. The electrolyte comprises a lithium salt, an organic solvent, and, as an additive, a compound selected from the group consisting of lithium difluorophosphate, vinylene carbonate, and 1,3-propanesultone, succinonitrile, propargyl-1H-imidazole-1-carboxylate, and methyl-prop-2-inyl carbonate. A cylindrical lithium secondary battery that satisfies the following equation (1). Equation (1): 3.5≦W ＬｉＤＦＰ / (W) ＶＣ +W ＰＳ )×Φ / H×100≦20 In the above formula (1), W ＬｉＤＦＰ This is the weight ratio (%) of lithium difluorophosphate to the total electrolyte, W ＶＣ This is the weight ratio (%) of vinylene carbonate to the total electrolyte, W ＰＳ Φ is the weight ratio (%) of 1,3-propanesultone to the total electrolyte, Φ is the diameter (mm) of the battery can, and H is the height (mm) of the battery can.

2. The cylindrical lithium secondary battery according to claim 1, wherein the positive electrode plate and the negative electrode plate each include a blank portion on which no active material layer is formed, and at least a portion of the blank portion of the positive electrode plate or the blank portion of the negative electrode plate has a structure that defines an electrode tab.

3. The cylindrical lithium secondary battery according to claim 1, wherein the electrolyte contains lithium difluorophosphate in an amount of 0.01% by weight or more and 3% by weight or less relative to the total weight of the electrolyte.

4. The cylindrical lithium secondary battery according to claim 1, wherein the electrolyte contains vinylene carbonate in an amount of 0.1% by weight or more and 10% by weight or less relative to the total weight of the electrolyte.

5. The cylindrical lithium secondary battery according to claim 1, wherein the electrolyte contains 0.1% by weight or more and 2% by weight or less of 1,3-propanesultone based on the total weight of the electrolyte.

6. The cylindrical lithium secondary battery according to claim 1, wherein the organic solvent comprises ethylene carbonate.

7. The cylindrical lithium secondary battery according to claim 6, wherein the ethylene carbonate is contained in an amount of 15% or more and 30% or less by volume relative to the total amount of the organic solvent.

8. The cylindrical lithium secondary battery according to claim 1, wherein the concentration of the total lithium salt contained in the electrolyte is 0.8 M or more and 2 M or less.

9. The cylindrical lithium secondary battery according to claim 1, wherein the electrolyte comprises succinonitrile and propargyl-1H-imidazole-1-carboxylate.

10. The cylindrical lithium secondary battery according to claim 1, wherein the positive electrode plate contains a positive electrode active material in which Ni has a content of 85 atm% or more among transition metals other than lithium.

11. The cylindrical lithium secondary battery according to claim 10, wherein the positive electrode active material is a lithium nickel-based oxide represented by the following [Chemical Formula 1]. [Chemical formula 1] Li ａ Ni ｂ Co ｃ M １ ｄ M ２ ｅ O ２ In the above chemical formula 1, M １ M is Mn, Al, or a combination thereof. ２ is one or more elements selected from the group consisting of Zr, W, Y, Ba, Ca, Ti, Mg, Ta, and Nb, and satisfies the following conditions: 0.8 ≤ a ≤ 1.2, 0.85 ≤ b < 1, 0 < c < 0.15, 0 < d < 0.15, and 0 ≤ e ≤ 0.

1.

12. The cylindrical lithium secondary battery according to claim 11, wherein the positive electrode active material is formed on the surface of the lithium nickel oxide and includes a coating layer containing B (boron).

13. The cylindrical lithium secondary battery according to claim 1, wherein the positive electrode plate comprises a positive electrode active material consisting of single particles, pseudo-single particles, or a combination thereof.

14. The cylindrical lithium secondary battery according to claim 1, wherein the negative electrode plate comprises a silicon-based negative electrode active material and a carbon-based negative electrode active material.

15. The cylindrical lithium secondary battery according to claim 14, 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.

16. The cylindrical lithium secondary battery according to any one of claims 1 to 15, wherein the cylindrical lithium secondary battery is a 46110-cell, 4875-cell, 48110-cell, 4880-cell, 4680-cell, or 4695-cell battery.

Images