Negative electrode material for lithium secondary battery and negative electrode for lithium secondary battery including same

Abstract

A negative electrode material for a lithium secondary battery, according to one embodiment, includes: a core comprising natural graphite particles coated with a coating layer including amorphous carbon; and conductive carbon bound to the core, wherein the negative electrode material satisfies formula 1 below and has a tap density (TD) of 1.10 g / cm3 or higher. (Formula 1) 0.50 ≤ PD-TD ≤ 0.90, where PD is the pellet density (g / cm3) of the negative electrode material and TD is the tap density (g / cm3) of the negative electrode material.

Description

Anode material for lithium secondary batteries and anode for lithium secondary batteries containing the same

[0001] The present invention relates to a negative electrode material for a lithium secondary battery and a negative electrode for a lithium secondary battery including the same, and more particularly, to a negative electrode material for a natural graphite-based lithium secondary battery.

[0002] Among the components that make up a lithium secondary battery, the anode material stores lithium ions during charging and plays a crucial role in determining factors such as charging speed and battery capacity. Carbon-based active materials are representative examples of commercially used anode materials.

[0003] Among carbon-based active materials, natural graphite is highly price competitive and has a higher capacity than artificial graphite, but it has problems such as a large irreversible reaction due to the exposed edge surface, a limited lithium ion diffusion path due to the uniaxial orientation of the graphene layer plane, poor high-rate characteristics, and low electrode density due to the ease of plane orientation on the current collector.

[0004] To solve these problems, a technology is being developed to mechanically process natural graphite into a spherical shape to reduce planar orientation and to cover the edges of natural graphite with a surface carbon coating layer to suppress irreversible reactions. However, this is insufficient to satisfy the market demand for high-rate characteristics.

[0005] According to one embodiment of the present invention, a negative electrode material for a lithium secondary battery having improved high-rate characteristics can be provided.

[0006] The objectives of the present invention are not limited to the above-described scope. Those skilled in the art will have no difficulty understanding the additional objectives of the present invention from the overall content of this specification.

[0007] According to one embodiment of the present invention, a negative electrode material for a lithium secondary battery comprises a core comprising particulate natural graphite coated with a coating layer comprising amorphous carbon and conductive carbon bonded to the core, and satisfies the following formula 1, and is 1.10 g / cm 3 It has a tap density (TD) of above.

[0008] (Formula 1)

[0009] 0.50 ≤ PD-TD ≤ 0.90

[0010] In Equation 1, PD is the pellet density of the negative electrode material (g / cm 3 ) and TD is the tap density of the cathode material (g / cm). 3 )am.

[0011] In one specific example, the cathode material may have a strengthening orientation index of 3.0 or more, as defined by Equation 2 below.

[0012] (Formula 2)

[0013] Strengthening orientation index = [I 110 + I 102 + I 103 ] / [I 002 ] × 100

[0014] I in Equation 2 110 , I 102 , I 103 and I 002 In the X-ray diffraction pattern of the cathode material, the maximum intensities of the (110) plane diffraction peak, the (102) plane diffraction peak, the (103) plane diffraction peak, and the (002) plane diffraction peak are shown.

[0015] In one specific example, the negative electrode material may have a compressibility of 2.0 or less, as defined by Equation 3 below.

[0016] (Formula 3)

[0017] Compression = [(SSA(AM)-SSA(CC)×WT / 100)] / [(1-WT / 100)]

[0018] In Equation 3, SSA(AM) is the specific surface area (m) of the cathode material. 2 / g), and SSA(CC) is the specific surface area of ​​conductive carbon (m 2 / g), and WT is the weight percentage of conductive carbon contained in the negative electrode material based on the total weight of the negative electrode material.

[0019] In one specific example, in a scanning electron microscope image of the negative electrode material at a magnification of 10,000 times, when the center of the longest length crossing the contour of the negative electrode material is set as the center of the contour, and when linear regression analysis of the contour is performed using 36 radial lines with an angle of 10° and the contact points between the contour, a coefficient of determination (R) of 0.95 or more is performed. 2 ) is the sum of the number of contact points belonging to the area of ​​the contour (n) L ) the total number of contact points located on the contour (n) T ) divided by the ratio (n) L / n T *The average of 100% may be greater than 45%.

[0020] In one specific example, the specific surface area of ​​the cathode material is 2.0 m 2 / g to 3.5 m 2 / g may be.

[0021] In one specific example, the cumulative volume-based median diameter (D) of the cathode material 50 ) can be 5 to 25 μm.

[0022] In one specific example, the natural graphite may be in the form of particles in which natural graphite fragments are joined, folded or assembled.

[0023] In one specific example, the cathode material may satisfy the following equation 4.

[0024] (Formula 4)

[0025] I D / I G ≤ 0.70

[0026] In Equation 4, I D is the maximum intensity of the D band peak in the Raman spectrum of the cathode material, and I Gis the maximum intensity of the G band peak in the same Raman spectrum.

[0027] In one specific example, the conductive carbon may include carbon black.

[0028] In one specific example, the carbon black may be at least one selected from the group consisting of acetylene black, ketjen black, channel black, furnace black, lamp black, and thermal black.

[0029] In one specific example, the carbon black can be dispersed and bound to the core by mechanical force.

[0030] In one specific example, the weight ratio of the core:conductive carbon contained in the negative electrode material may be 100:0.1 to 5.0.

[0031] In one specific example, the weight ratio of graphite to amorphous carbon contained in the core may be 100:1 to 10.

[0032] A negative electrode for a lithium secondary battery according to one embodiment of the present invention includes the negative electrode material for a lithium secondary battery described above.

[0033] A lithium secondary battery according to one embodiment of the present invention includes the above-described negative electrode.

[0034] The cathode material according to one specific example may have improved high-rate output characteristics.

[0035] The various advantageous and beneficial effects of the present invention are not limited to the above-described contents, and will be more easily understood in the course of explaining specific embodiments of the present invention.

[0036] Hereinafter, preferred embodiments of the present invention will be described. However, the embodiments of the present invention may be modified in various other forms, and the scope of the present invention is not limited to the embodiments described below.

[0037] In addition, the embodiments of the present invention are provided to more completely explain the present invention to a person having average knowledge in the relevant technical field.

[0038] In describing the embodiments of the present invention, if a detailed description of a known technology related to the present invention is judged to unnecessarily obscure the gist of the present invention, such detailed description will be omitted. In addition, the terms described below are terms defined in consideration of their functions in the present invention, and these may vary depending on the intention or custom of the user or operator. Therefore, the definitions should be made based on the contents throughout this specification. The terminology used in the detailed description is only for the purpose of describing the embodiments of the present invention and should in no way be limiting. Unless clearly defined otherwise, expressions in the singular form include plural meanings.

[0039] In this description, expressions such as "including" or "having" are intended to indicate certain features, numbers, steps, operations, elements, portions or combinations thereof, and should not be construed to exclude the presence or possibility of one or more other features, numbers, steps, operations, elements, portions or combinations thereof other than those described.

[0040] Unless otherwise specified in the specification of the present invention, the % unit means weight %.

[0041] In this specification, terms such as 'top', 'upper part', 'top surface', 'bottom', 'lower part', 'bottom', 'side', etc. may actually vary depending on the direction in which the elements or components are arranged.

[0042] Below, the present invention will be described in detail through each embodiment or example of the present invention. It should be noted that each embodiment or example described in this specification is not limited to a single embodiment or example, but may be combined with other embodiments or examples. Therefore, the citation of a claim in the patent claims is only an example of an embodiment, and the technical concept of the present invention should not be interpreted solely as a combination with the cited claim, and combinations with various claims also fall within the scope of the technical concept of the present invention.

[0043] A negative electrode material for a lithium secondary battery according to the present invention comprises a core including particulate natural graphite coated with a coating layer including amorphous carbon and conductive carbon bonded to the core, and satisfies the following equation 1, and is 1.10 g / cm 3 It has a tap density (TD) of above.

[0044] (Formula 1)

[0045] 0.50 ≤ PD-TD ≤ 0.90

[0046] In Equation 1, PD is the pellet density of the negative electrode material (g / cm 3 ) and TD is the tap density of the cathode material (g / cm). 3 )am.

[0047] In Equation 1, the difference between the PD and TD of the negative electrode material and the tap density (TD) are properties that indicate the degree of deformation during rolling of the negative electrode material. The difference between PD and TD is large, exceeding 0.90, and 1.10 g / cm. 3 For a negative electrode material having a tap density below 1.10 g / cm, even when conductive carbon is bonded to natural graphite coated with amorphous carbon, the property improvement achieved by complexation with the conductive carbon is not damaged by deformation caused by rolling, and the property improvement achieved by complexation can be maintained even within the active material layer. That is, 1.10 g / cm 3When equation 1 is satisfied with the above tap density, deformation during rolling can be suppressed by the densified natural graphite.

[0048] Advantageously, PD-TD may be 0.85 or less, more advantageously 0.80 or less, even more advantageously 0.75 or less, and even more advantageously 0.70 or less, and considering the inherent mechanical properties of natural graphite, PD-TD may be substantially 0.40 or more, more substantially 0.50 or more, and even more substantially 0.55 or more. As a specific example, PD-TD may be 0.40 to 0.90, 0.40 to 0.80, 0.50 to 0.85, 0.50 to 0.80, 0.50 to 0.75, 0.50 to 0.70, 0.55 to 0.85, 0.55 to 0.80, 0.55 to 0.75, or 0.55 to 0.70, but is not necessarily limited to these ranges.

[0049] 1.10 g / cm 3 The above high tap density and the difference between the aforementioned small PD and TD can be secured by suppressing deformation of the negative electrode material when pressed by the core structure in which the negative electrode material is highly dense and tightly bound at high density.

[0050] The tap density (TD) of the cathode material is 1.10 g / cm 3 Above, as a specific example, 1.10 to 1.30 g / cm 3 , or 1.15 to 1.30 g / cm 3 It can be. At this time, the tap density (TD) of the negative electrode material and the tap density (TD') of the particulate natural graphite (or core) coated with the coating layer can be substantially the same. Specifically, |TD-TD'| is 0.15 g / cm 3 Below, 0 to 0.10 g / cm 3 , 0 to 0.05 g / cm 3 , 0 to 0.02 g / cm 3 Or it can be practically zero, i.e. the tap density (TD') of the core is also 1.10 to 1.30 g / cm.3 , or 1.15 to 1.30 g / cm 3 It could be.

[0051] In an advantageous example, the cathode material may have a strengthening orientation index of 3.0 or greater, as defined by Equation 2 below.

[0052] (Formula 2)

[0053] Strengthening orientation index = [I 110 + I 102 + I 103 ] / [I 002 ] × 100

[0054] I in Equation 2 110 , I 102 , I 103 and I 002 In the X-ray diffraction pattern of the cathode material, the maximum intensities of the (110) plane diffraction peak, the (102) plane diffraction peak, the (103) plane diffraction peak, and the (002) plane diffraction peak are shown.

[0055] As is well known, since lithium ions are inserted and deintercalated into the interplanar space of the (002) plane during charge and discharge, only the orientation of the (110) plane, which enables direct diffusion into the interplanar space of the (002) plane, was focused on in relation to the crystallographic isotropy of natural graphite. However, when the negative electrode material coated on a current collector by rolling, etc. is implemented as an active material layer, the lithium ion insertion / deintercalation characteristics of the negative electrode material are greatly affected not only by the degree of orientation of the (110) plane (edge ​​plane) and the (002) or (004) plane (basal plane) in the negative electrode material powder state, but also by the orientation of the (102) plane and (103) plane, which are the interplanes between the basal plane and the edge plane.

[0056] In detail, even when the orientation of the (110) plane is low in the negative electrode material, if the orientations of the (102) plane and (103) plane are high, the insertion / de-insertion of lithium ions in natural graphite within the active material layer is promoted, and more improved high-rate characteristics can be exhibited. Since the orientations of the (110) plane and the orientations of the (102) plane and (103) plane in natural graphite whose shape is artificially controlled are substantially independent of each other, it is advantageous for the negative electrode material to have well-developed not only the (110) plane but also the (102) plane and (103) plane. In this case, the natural graphite whose shape is artificially controlled may mean a particle shape in which natural graphite fragments (natural graphite crystals) are formed by gluing, bending, and / or assembling.

[0057] The reinforcement orientation index according to Equation 2 defines the crystallographic isotropy of the negative electrode material based on the (110), (102), and (103) planes of the negative electrode material, which have a major influence on the diffusion of lithium ions and the insertion / de-insertion of lithium ions when the active material layer is implemented as the negative electrode material. In an advantageous example, the negative electrode material may have a reinforcement orientation index of 3.0 or more, and may substantially have a reinforcement orientation index of 3.0 to 5.0. More advantageously, the reinforcement orientation index of the negative electrode material may be 3.3 to 4.5, and even more advantageously, 3.5 to 4.5.

[0058] In one specific example, the negative electrode material may have a compressibility of 2.0 or less, as defined by Equation 3.

[0059] (Formula 3)

[0060] Compression = [(SSA(AM)-SSA(CC)×WT / 100)] / [(1-WT / 100)]

[0061] In Equation 3, SSA(AM) is the specific surface area (m) of the cathode material. 2 / g), and SSA(CC) is the specific surface area (m) of conductive carbon (conductive carbon itself). 2 / g), and WT is the weight percentage of conductive carbon contained in the negative electrode material based on the total weight of the negative electrode material.

[0062] Specifically, through previous experiments, it was confirmed that the electrochemical properties of the negative electrode material vary depending on the degree of compression of the negative electrode material, even when the same type and content of conductive carbon is bound to the core. That is, the electrochemical properties due to the state of complexation between the core and the conductive carbon (bonding of the conductive carbon to the core) and / or the complexation between the core and the conductive carbon based on the active material layer may vary depending on the degree of compression.

[0063] In a advantageous example, the compressibility of the negative electrode material may be 2.0 or less, more advantageously 1.9 or less, and in a practical example, it may be 1.0 or more, and more advantageously 1.5 or more. In a specific and practical example, the compressibility of the negative electrode material may be from 1.0 to 2.0, and advantageously from 1.5 to 1.9. When the negative electrode material has the aforementioned compressibility, it may exhibit improved high-rate characteristics due to the synergistic effect between the conductive carbon and the core having a dense, high-density, strongly bonded structure. When the negative electrode material has a compressibility exceeding 2.0, there is a risk that the conductive carbon material will be non-homogeneously distributed on the surface of the core, and mainly fill or be trapped in the empty spaces present on the surface of the core (including the openings of the pores and the gaps between the natural graphite flakes).

[0064] In one specific example, the negative electrode material may have a flat surface area. The flat surface area may be defined by linear regression analysis of the contour of the negative electrode material using scanning electron microscope images of the negative electrode material.

[0065] In detail, in the scanning electron microscope observation image of the negative electrode material at 10,000 times magnification, when the center of the longest length crossing the contour of the negative electrode material is set as the center of the contour, and the intersection points (contour points) between 36 radial lines with an angle of 10° are used for linear regression analysis of the contour, the coefficient of determination (R) was 0.95 or more. 2 ), with a coefficient of determination (R) of substantially 0.96 or higher 2), more practically, the sum of the number of contact points belonging to the region of the contour with a coefficient of determination of 0.97 or higher (n L ) the total number of contact points located on the contour (n) T ) divided by the ratio (n) L / n T *100, %) The average value can be more than 45%. Below, if necessary, the ratio in the outline (n) L / n T *100, %) is classified as ratio (I), and the average of ratio (I) is classified as ratio (II).

[0066] The outline of the cathode material in the scanning electron microscope image may be the boundary between the particle region and the particle outer region of a particle (the outermost line of the particle in the image). The longest distance across the outline may correspond to the longest distance between two points within the outline. The center of the longest distance may be the center of the outline, the center of the radial line, or the origin ((0,0)) of the Cartesian coordinates.

[0067] In linear regression analysis, the coefficient of determination (R) is 0.95 or higher. 2 ), with a coefficient of determination (R) of substantially 0.96 or higher 2 ), and more practically, a coefficient of determination (R) of 0.97 or higher 2 ) are points that are located consecutively (points that are located consecutively adjacent to each other) and are points that belong to a group of variables for which a linear correlation is derived during linear regression analysis.

[0068] In the outline, a coefficient of determination (R) of 0.95 or more, substantially 0.96 or more, and more substantially 0.97 or more, defined as a flat surface area. 2 ) may be one or more contour areas to which contact points having the same number of contact points belong, specifically, 1 to 7, more specifically, 1 to 5, but is not necessarily limited thereto.

[0069] Accordingly, ratio (I) may correspond to the ratio of the total length occupied by the contour area(s) corresponding to the flat surface area to the total contour length of the negative electrode material. Ratio (II), which is the average value of ratio (I), may indicate the ratio occupied by the flat surface area on the surface of the negative electrode material.

[0070] In one specific example, the ratio of the flat surface area on the surface of the negative electrode material, i.e., ratio (II), may be 45% to 90%, specifically 50% to 90%, more specifically 50% to 85%, and even more specifically 55% to 85%.

[0071] When the negative electrode material has a ratio (II) of 45% or more as described above, when implemented as an active material layer, current conduction occurs more smoothly and effectively between the negative electrode materials and between the negative electrode material and the current collector by the conductive carbon bonded to the core, and a micro gap can be formed and maintained between the negative electrode materials, which is advantageous for contact with the electrolyte and diffusion of lithium ions.

[0072] In one specific example, the proportion of particles having a flat surface area (FS) among the negative electrode material may be at least 60%, specifically at least 70%, more specifically at least 80%, and even more specifically at least 90%, and may be substantially at most 100%, or even substantially less than 100%.

[0073] In one specific example, the specific surface area of ​​the cathode material is 2.0 m 2 / g to 3.5 m 2 / g, more specifically 2.0 to 3.0 m 2 / g, more specifically 2.0 to 2.7 m 2 / g, more specifically 2.0 to 2.5 m 2 / g. In one specific example, the negative electrode material includes fine conductive carbon, but the specific surface area of ​​the negative electrode material is 2.0 m 2 / g to 3.5 m 2 / g level, more specifically 2.0 to 2.5 m 2 / g may be only. At this time, the specific surface area of ​​the core is 1.3 to 2.0 m 2 / g, specifically 1.4 to 1.8 m 2 / g may be.

[0074] In one specific example, the cumulative volume-based median diameter (D) of the cathode material 50 ) may be 5 to 25 ㎛, specifically 10 to 25 ㎛, more specifically 10 to 20 ㎛, and even more specifically 12 to 18 ㎛. The size of the negative electrode material is a size that is advantageous for high-densityization of the negative electrode, and a size that can prevent the viscosity of the slurry from increasing excessively during the electrode manufacturing process. The span of the negative electrode material may be 0.6 to 1.0, specifically 0.7 to 0.9. The small span value of the negative electrode material of only 0.6 to 1.0 can form a stable and uniformly open pore structure within the active material layer when implemented as an active material layer, and is advantageous in that it enables homogeneous and smooth contact between the negative electrode material and the electrolyte.

[0075] In one specific example, the natural graphite of the core may be in the form of particles in which natural graphite fragments are joined, folded, and / or assembled. Specifically, the particulate natural graphite may be natural graphite particles in which natural graphite fragments are joined and assembled in a cabbage shape, randomly joined, folded, and / or assembled, or joined and assembled in a composite form of a cabbage shape and a random shape. In this case, an example of a composite form may be a form in which the central region of the particle is randomly assembled and the surface region is joined in a cabbage shape.

[0076] In terms of manufacturing method, the particulate natural graphite may be a particle in which natural graphite fragments derived from natural graphite having an anisotropic shape, such as a flake shape, are formed, folded, and / or assembled by mechanical processing (mechanical force) based on shear force, and the formed particle shape is readjusted by a compressive force. In this case, the natural graphite fragments may be primary particles of natural graphite that are formed, folded, and / or assembled as units derived from natural graphite having an anisotropic shape, and may substantially be crystals of natural graphite.

[0077] In one specific embodiment, the core is coated with a coating layer comprising amorphous carbon and may comprise natural graphite particles formed by gluing, folding, and / or assembling natural graphite fragments. The coating layer may cover part or all of the surface of the natural graphite particles. The coating layer containing amorphous carbon can prevent the edges of the natural graphite from being directly exposed to the surface of the negative electrode material, thereby suppressing side reactions caused by the electrolyte and reducing irreversible reactions.

[0078] The coating layer may contain amorphous carbon, and for example, the coating layer may be an amorphous carbon layer. The amorphous carbon may include soft carbon, hard carbon, or a mixture thereof. The weight ratio of graphite to amorphous carbon contained in the core may be, but is not limited to, 100:1 to 10, specifically 100:1 to 6, and more specifically 100:2 to 5.

[0079] In one specific example, the negative electrode material may satisfy the following equation 4.

[0080] (Formula 4)

[0081] I D / I G ≤ 0.70

[0082] In Equation 4, I Dis the maximum intensity of the D band peak in the Raman spectrum of the cathode material, and I G is the maximum intensity of the G band peak in the same Raman spectrum. The D band peak of graphite is known to be at 1345 cm -1 1375 cm inland -1 , specifically 1350 cm -1 1370 cm inland -1 It may be a peak located in the waveband region, and the G band peak of graphite is known to be at 1560 cm -1 1615 cm in height -1 , specifically 1565 cm -1 1610 cm inland -1 It may be a peak located in the waveband region.

[0083] In the Raman spectrum, the D band peak is a peak resulting from the disorder and defects of the graphite structure, such as vacancy defects, substitutional defects, and edges in the hexagonal graphite structure. Since the negative electrode material includes particulate natural graphite coated with a coating layer containing amorphous carbon and a conductive carbon material, the D band peak is a property related to the quality and thickness of the coating layer containing amorphous carbon and the quality and content of the conductive carbon material. Low I of 0.70 or less D / I G The rain means that the natural graphite in the negative electrode material has excellent crystallinity with few defects, the core has a very thin coating layer, and the negative electrode material contains a small amount of conductive carbon. Specifically, the I of the negative electrode material D / I G The ratio may be from 0.20 to 0.70, more specifically from 0.30 to 0.60, and even more specifically from 0.30 to 0.50.

[0084] In one specific example, the conductive carbon may be particulate conductive carbon. In this case, the particulate may mean a particle having an average size of 10 to 500 nm, specifically 30 to 300 nm. As a preferred example, the conductive carbon may include carbon black, and the carbon black may be at least one selected from the group consisting of acetylene black, ketjen black, channel black, furnace black, lamp black, and thermal black, and may advantageously be at least one selected from the group consisting of acetylene black, ketjen black, and furnace black. The carbon black may have a particle size of 10 to 1000 m. 2 / g, in detail, 30 to 350 m 2 It has a high specific surface area of ​​ / g and has a structure in which primary particles of several to several tens of nanometers in size are irregularly aggregated, which is advantageous in that it can improve the electrochemical properties of the negative electrode material in small amounts.

[0085] In one specific embodiment, the conductive carbon can be dispersed and bound to the core by mechanical force. Since the conductive carbon and the core are bound to each other by mechanical force, a separate binder is unnecessary, so that the electrical properties of the conductive carbon are not damaged. In addition, when the conductive carbon is carbon black, the inherent agglomeration of the carbon black is broken up by mechanical force, and even a small amount of carbon black can be uniformly dispersed and bound in the form of islands over the entire surface of the core, which is advantageous. As a practical example, the weight ratio of the core: conductive carbon contained in the negative electrode material, advantageously the core: carbon black, may be 100:0.1 to 5.0, 100:0.3 to 3.0, 100:0.5 to 1.5, but is not limited thereto.

[0086] The present invention includes a method for manufacturing an anode material for a lithium secondary battery. In detailing the manufacturing method, the amorphous carbon, coating layer, particulate natural graphite, core, conductive carbon, and anode material are similar to or identical to those described above for the anode material for a lithium secondary battery. Accordingly, the method for manufacturing an anode material for a lithium secondary battery encompasses all of the above-described anode materials for a lithium secondary battery.

[0087] A method for manufacturing an anode material for a lithium secondary battery according to one specific example may include a step of isotropically pressing spheroidized natural graphite at a pressure of 200 MPa to 500 MPa to manufacture pressed natural graphite (pressurizing step); a step of forming a coating layer including amorphous carbon on the pressed natural graphite to manufacture a core (coating step); and a step of mixing the manufactured core with conductive carbon and applying a mechanical force including a shear force to bind the conductive carbon to the core (binding step). If necessary, the method for manufacturing according to one specific example may further include a step of mechanically processing natural graphite (raw material) having an anisotropic shape to manufacture spheroidized natural graphite having a sphericity of 0.84 to 0.90 (spheroidization step).

[0088] Through the coating step, the aforementioned core can be manufactured. That is, through the spheroidization step, the pressing step, and the coating step, the tap density can be 1.10 to 1.30 g / cm. 3 , specifically 1.15 to 1.30 g / cm 3 , and the specific surface area is 1.3 to 2.0 m 2 / g, specifically 1.4 to 1.8 m 2 / g core can be manufactured. Afterwards, the aforementioned negative electrode material can be manufactured through a bonding step.

[0089] In the spheroidization step, the raw material may be natural graphite particles having an anisotropic shape. The anisotropic shape is defined as the size (length) l in the three axes (x, y, z) directions, with the center of the particle as the origin. x , ly and l z The longest length (e.g., l) x ) is the shortest length (e.g., l z ) can mean a shape with an aspect ratio of 2 or more, specifically 3 or more. At this time, experimentally l x , l y and l z can be measured through conventional scanning electron microscope observation or particle shape analyzer, etc. Representative examples of anisotropic shapes include plate shape and / or flake shape. As a practical example, the raw material may be, but is not limited to, flaky natural graphite that can be easily and densely formed, folded, and / or assembled by mechanical processing.

[0090] In the spheroidization step, mechanical processing may refer to a process of mechanically adjusting the shape of natural graphite (raw material) having an anisotropic shape into a sphere by applying a mechanical force. Spheroidization may be performed by a spheroidization method using mechanical processing commonly known in the secondary battery field. Representative examples of mechanical processing include Air Classifying milling, Spheronizing milling, Grinding milling, Mechanofusion milling, Planetary milling, Hybridization milling, Shape milling, High speed milling, etc., and the mechanical processing may be performed under known conditions, for example, at a rotation speed of 500 to 4000 rpm, and may be performed for 5 to 60 minutes, but is not limited thereto.

[0091] In an advantageous example, the spheroidization step may be batch-processed using the batch-processed spheroidization device described below. Here, batch-processing means that the raw material is introduced, the mechanical processing of the raw material is completed, and the production of spheroidized graphite is completed within the same processing space. In other words, this may mean that the raw material is introduced, spheroidization of the raw material is initiated and completed within the same pre-defined processing space, and spheroidized natural graphite is produced.

[0092] In a batch-type spheroidizing device, a processing space may be defined by a spheroidizing case that divides an inner / outer space, and the inner space of the spheroidizing case may correspond to the processing space. In the processing space where rotary processing using airflow is performed, a processing section may be located, which includes a rotating shaft and a rotating member that is coupled to the rotating shaft and generates a rotating airflow when rotated. The rotating member may include a ring-shaped plate (a hollow circular plate). The rotating shaft may be located at the center of the ring-shaped plate, and the plate and the rotating shaft may be coupled to each other by a plurality of bar-shaped coupling members. Specifically, the rotating member may include a plurality of ring-shaped plates, more specifically, two to three ring-shaped plates, which are positioned spaced apart from each other in the axial direction of the rotating shaft. The ring-shaped plates may include hammers capable of applying a physical impact to natural graphite. Specifically, each of the ring-shaped plates may be provided with a plurality of hammers spaced at regular intervals along the circumferential direction centered on the rotating shaft. The shape of the hammer may be an angular shape or a curved shape based on its cross-section. Representative examples of the angular shape include a cross-section, a triangle, a square, or a pentagon, and representative examples of the curved shape include a cross-section, a circle, a truncated circle, an oval, or a truncated oval, but are not limited thereto. In addition, the rotating shaft may further be provided with a circular plate located below the rotating member. By means of this circular plate, natural graphite can be easily introduced into the space between the rotating member (or hammer) and the inner surface (or liner) of the spheroidizer case. In addition, a plurality of liners spaced apart from each other may be provided on the inner surface of the spheroidizer case located at least outside the processing section. In addition, the processing space may be connected to a dust collector for removing fine particles within the processing space. The dust collector may have a fluid suction function through a typical fluid flow generating device such as a blower, and may suction and remove fine particles within the processing space.As a practical example, the dust collection unit may include a classifier connected to the processing space, and fine particles passing through the classifier may be sucked out of the processing space and removed. The classifier may be an airflow classifier, and the airflow classifier may be a swirling-flow (centrifugal) classifier. As a practical example, the swirling-flow classifier may include a forced vortex classifier. Examples of forced vortex classifiers include, but are not limited to, a turboplex, a super separator, and a micro separator. The spheroidizing step performed as a batch process using a batch spheroidizing device may be performed at a rotation speed of 800 to 3000 rpm, specifically 1500 to 2500 rpm, for 5 to 40 minutes.

[0093] When spheroidizing anisotropic natural graphite through batch processing using the batch spheroidizing device described above, spheroidizing natural graphite can be achieved while minimizing damage to the natural graphite, and at the same time, the strengthening orientation index can be improved, which is advantageous.

[0094] In the pressurizing step, the isotropic pressing may be cold isotropic pressing. In order to densify the graphite structure by removing internal pores of the particles, strongly bond the natural graphite fragments, and readjust the shape of the spheroidized natural graphite to have a macroscopically flat surface, a pressure of 200 MPa to 500 MPa, specifically 250 to 500 MPa, more specifically 300 to 500 MPa, and even more specifically 400 to 500 MPa may be applied during the isotropic pressing for 10 seconds to 2 minutes, specifically 20 seconds to 1 minute.

[0095] After the pressurization step is performed, a disintegration step may be performed to disintegrate the natural graphite particles that have been agglomerated by the pressurization. The disintegration step may be performed by applying a physical impact. As a specific example, the disintegration step may be performed using equipment that utilizes a physical impact, such as a jet mill, an air classifier mill (or air current classification mill), or a roller mill. Specifically, a jet mill disintegrates particles by colliding them with a high-pressure air stream, an air classifier disintegrates particles and classifies them according to specific gravity by using an air stream, and a roller mill disintegrates particles by placing them between two or more rollers that rotate in opposite directions and compressing and crushing them. For effective disintegration, the disintegration step may include a coarse crushing step and a fine crushing step. In detail, the crushing step may include a coarse crushing step of crushing natural graphite lumps agglomerated by isotropic pressing into coarse powder, a fine crushing step of crushing the coarse powder into fine powder, and a step of crushing the fine powder by applying a physical impact. As a practical example, the coarse crushing step may include crushing natural graphite lumps agglomerated by isotropic pressing into a cumulative volume-based median diameter (D) of 10 to 50 mm. 50 ), with a cumulative volume-based median diameter (D) of 10 to 30 mm in detail 50 ) may be a step of grinding into a coarse powder. After the coarse grinding is performed, in the fine grinding step, the coarse powder is ground into a cumulative volume-based median diameter (D 50 ) can be pulverized into fine powder of less than 10 mm, and the fine powder can be pulverized into individual graphite particles (pulverized particles) by applying physical impact. However, this is only a specific pulverization condition for faster and more effective pulverization, and the present invention is not limited to the pulverization method. If necessary, after pulverization, further classification such as air classification and / or sieve classification can be performed to remove unpulverized agglomerated particles or fine particles that may be generated during pulverization.

[0096] After producing pressurized natural graphite, a coating step may be performed to form a coating layer including amorphous carbon on the pressurized natural graphite. Specifically, the coating step may include a step of mixing and heating (carbonization heat treatment) the pressurized natural graphite with a carbon precursor. The carbon precursor may be at least one selected from the group consisting of isotropic pitch, anisotropic pitch, heavy oil, light oil, polyvinyl alcohol (PVA), polyvinyl chloride (PVC), sucrose, phenol resin, furan resin, furfuryl alcohol, polyacrylonitrile, cellulose, styrene, polyimide, epoxy resin, and glucose, but is not limited thereto.

[0097] In the coating step, the mixing between the pressurized natural graphite and the carbon precursor may be mechanical mixing. For example, the mechanical mixing may be at least one selected from the group consisting of ball milling, mechanofusion milling, shaker milling, planetary milling, attritor milling, shape milling, nauta milling, nobilta milling, high speed mixing, paddle mixing, ribbon mixing, Henschel mixing, corn type mixing, homo mixing, and agitator, but is not limited thereto. If necessary, a solvent that dissolves the carbon precursor may be mixed together to perform mechanical mixing, and independently, mechanical mixing may be performed while the carbon precursor is melted or softened by heating. In this case, the heating may include frictional heat generated during mechanical mixing.

[0098] When mixing, the pressurized natural graphite and the carbon precursor may be mixed in a mixing ratio that satisfies the weight ratio of graphite: amorphous carbon in the core obtained by heat treatment for carbonization of the carbon precursor, taking into account the residual carbon content of the carbon precursor, of 100:1 to 10, specifically 100:1 to 6, and more specifically 100:2 to 5. After mixing between the pressurized natural graphite and the carbon precursor is performed, the heat treatment for carbonizing the carbon precursor may be performed at 1000 to 1500°C for 5 to 15 hours in an atmosphere of hydrogen, nitrogen, argon, or a mixed gas thereof, but is not limited thereto.

[0099] The bonding step is a step of bonding conductive carbon to the core, and may be a step of physically bonding the conductive carbon to the core by applying mechanical force to the core and the conductive carbon obtained by the coating step and mixing them. The mixing ratio (weight ratio) of the core: conductive carbon may be 100:0.1 to 5.0, 100:0.3 to 3.0, or 100:0.5 to 1.5. Mixing for bonding can be performed by one or more methods selected from a ball mill, a mechano-fusion, a shaker mill, a planetary mill, an attritor mill, a disk mill, a shape mill, a nauta mixer, a nobilta mill and a high speed mixer, and advantageously, by one or more methods selected from a mechano-fusion, a nobilta mill, a disk mill, an attritor mill and a high speed mixer in which shear force is dominant. The mixing can be performed at a rotation speed of 500 to 2500 rpm, specifically 1500 to 2500 rpm, for 5 to 30 minutes. By such mechanical mixing, the conductive carbon can be uniformly dispersed on the surface of the core and physically bonded thereto.

[0100] The present invention includes a negative electrode for a lithium secondary battery containing a negative electrode material manufactured by the method for manufacturing a negative electrode material for a lithium secondary battery described above.

[0101] The present invention includes a negative electrode for a lithium secondary battery containing the negative electrode material for a lithium secondary battery described above.

[0102] The negative electrode according to the invention is a negative electrode for a lithium secondary battery, and includes a current collector and an active material layer (negative electrode active material layer) located on at least one surface of the current collector and containing the above-described negative electrode material.

[0103] The negative electrode active material layer may include 95 to 99 wt% of the negative electrode active material based on the total weight of the negative electrode active material layer. At this time, the negative electrode active material may contain the above-described negative electrode material alone or a heterogeneous negative electrode material together with the above-described negative electrode material. Examples of the heterogeneous negative electrode material include an artificial graphite-based negative electrode material, a natural graphite-based negative electrode material, and / or a silicon-based (silicon, silicon oxide, silicon-silicon oxide composite, silicon-carbon composite, silicon alloy, etc.) negative electrode material. When the negative electrode active material contains both the above-described negative electrode material and a heterogeneous negative electrode material, the weight ratio of the graphite-based negative electrode material: the heterogeneous negative electrode material may be 100:1 to 100, but is not necessarily limited thereto.

[0104] The negative electrode active material layer may further include an additive including an organic binder together with the negative electrode active material, and if necessary, the additive may further include a conductive material. In order to ensure stable fixation between the negative electrode active materials and between the negative electrode active material and the current collector by the organic binder, and to not damage the conductivity and open pore structure within the negative electrode active material layer, the negative electrode active material layer may contain 1 to 5 wt% of the organic binder, and substantially 1 to 3 wt% of the organic binder. In addition, when the negative electrode active material layer further contains a conductive material, the negative electrode active material layer may contain 0.5 to 3 wt% of the conductive material, and substantially 0.5 to 2 wt% of the conductive material, but is not limited thereto.

[0105] The organic binder may be a polymer binder commonly used in the lithium secondary battery field to bind particulate negative electrode active materials to each other and to bind the negative electrode active materials to a current collector. Practical examples of the organic binder include, but are not limited to, polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, polymers containing ethylene oxide, polyvinyl pyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene-butadiene rubber, acrylated styrene-butadiene rubber, epoxy resin, nylon, or mixtures thereof.

[0106] The conductive agent may be a conductive additive commonly used to improve the conductivity of anodes in the lithium secondary battery field. Specifically, the conductive agent may include a dot-shaped conductive agent, a linear conductive agent, a planar conductive agent, or a mixture thereof. Examples of dot-shaped conductive agents include conductive carbon materials including carbon black, specifically acetylene black, Ketjen black, channel black, paneth black, lamp black, thermal black, etc.; metal particles including copper, nickel, aluminum, silver, etc.; conductive polymer particles; core-shell particles having a non-conductive core and a conductive shell; and examples of linear conductive agents include carbon nanotubes, conductive carbon fibers, metal fibers, or conductive polymer fibers. Examples of planar conductive agents include graphene or reduced graphene oxide, but are not limited thereto. As a practical example, the conductive agent may include carbon black, and as another practical example, the conductive agent may include carbon black and carbon nanotubes.

[0107] The electrode density of the cathode is 1.20 to 1.90 g / cm 3 Level, specifically 1.50 to 1.90 g / cm 3 It may be, but is not limited to,

[0108] The current collector (negative current collector) can be any conductive material commonly used in lithium secondary batteries to ensure smooth current flow to the negative electrode active material layer. The current collector may be, but is not limited to, a foil, a porous foil, a foam, a mesh, a non-woven fabric, a non-conductive material having a conductive coating layer formed thereon, or a combination thereof. The material of the current collector may be any material that has high conductivity without causing chemical changes within the battery. Practical examples of the current collector include, but are not limited to, copper, stainless steel, aluminum, nickel, titanium, or alloys thereof. The current collector may have a conventional thickness, for example, but is not limited to, a thickness of 3 to 500 μm.

[0109] The anode can be manufactured using any method commonly used for manufacturing anodes in the lithium secondary battery field. For example, the anode can be manufactured by applying a slurry containing an anode active material, a binder, a solvent, and, if necessary, a conductive agent to at least one surface of a current collector, followed by drying and rolling, but is not limited thereto.

[0110] In the lithium secondary battery field, the solvent may be any solvent commonly used in forming a slurry for the manufacture of anodes. Examples of solvents include, but are not limited to, dimethyl sulfoxide (DMSO), isopropyl alcohol, N-methylpyrrolidone (NMP), acetone, dimethylformamide (DMF), water, or mixtures thereof.

[0111] The slurry may be applied using any method commonly used to form an active material layer using slurry in the lithium secondary battery field. For example, the slurry may be applied using slot die coating, Meyer bar coating, gravure coating, comma coating, roll coating, blade coating, bar coating, or dipping coating.

[0112] The present invention includes a lithium secondary battery including the above-described negative electrode.

[0113] A lithium secondary battery according to the present invention may include the above-described negative electrode, positive electrode, a separator interposed between the negative electrode and the positive electrode, and an electrolyte. Specifically, the secondary battery may include a positive electrode including a positive electrode current collector and a positive electrode active material layer positioned on at least one surface of the positive electrode current collector, the above-described negative electrode, a separator interposed between the positive electrode and the negative electrode, and an electrolyte that conducts lithium ions. The positive electrode current collector, the positive electrode active material or composition of the positive electrode active material layer, the solvent or electrolyte salt of the separator and the electrolyte, or the concentration of the electrolyte salt, may be any of materials or compositions commonly employed in lithium secondary batteries. In addition, the secondary battery may further include an electrode assembly including a positive electrode, a negative electrode, and a separator, and a sealable battery container in which an electrolyte is stored internally.

[0114] Hereinafter, specific examples of representative positive electrodes, separators, and electrolytes in lithium secondary batteries are described in detail, but the present invention is not limited to the configuration of positive electrodes, separators, and electrolytes.

[0115] The positive electrode may include a positive electrode current collector and a positive electrode active material layer disposed on the positive electrode current collector, and the positive electrode active material layer may include a positive electrode active material. The positive electrode current collector is not particularly limited as long as it is conductive and does not cause a chemical change in the battery, and for example, stainless steel, aluminum, nickel, titanium, calcined carbon, or aluminum or stainless steel surface-treated with carbon, nickel, titanium, silver, etc. may be used. In addition, the positive electrode current collector may typically have a thickness of 3 to 500 ㎛, and fine unevenness may be formed on the surface of the positive electrode current collector to increase the adhesion of the positive electrode active material. For example, it may be used in various forms such as a film, a sheet, a foil, a net, a porous body, a foam, a non-woven fabric, etc.

[0116] A compound capable of reversibly intercalating and deintercalating lithium (a lithiated intercalation compound) can be used as the cathode active material. Specifically, one or more composite oxides of lithium and a metal selected from cobalt, manganese, nickel, and combinations thereof can be used. A specific example of such a compound is a compound represented by one of the following chemical formulas:

[0117] Li a A 1-b B b D2 (in the above formula, 0.90 ≤ a ≤ 1.8, and 0 ≤ b ≤ 0.5); Li a E 1-b B b O 2-c D c (In the above formula, 0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05); LiE 2-b B b O 4-c D c (In the above formula, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05); Li a Ni 1-b-c Co b B c D α (In the above formula, 0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 < α ≤ 2); Li a Ni 1-b-c Co b B c O 2-α T α (In the above formula, 0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 < α < 2); Li a Ni 1-b-c Co b B c O 2-α T2 (in the above formula, 0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 < α < 2); Li a Ni 1-b-c Mnb B c D α (In the above formula, 0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 < α ≤ 2); Li a Ni 1-b-c Mn b B c O 2-α T α (In the above formula, 0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 < α < 2); Li a Ni 1-b-c Mn b B c O 2-α T2 (in the above formula, 0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 < α < 2); Li a Ni b E c G d O2 (in the above formula, 0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.9, 0 ≤ c ≤ 0.5, 0.001 ≤ d ≤ 0.1); Li a Ni b Co c Mn d GeO2 (in the above formula, 0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.9, 0 ≤ c ≤ 0.5, 0 ≤ d ≤ 0.5, 0.001 ≤ e ≤ 0.1); Li a NiG b O2 (in the above formula, 0.90 ≤ a ≤ 1.8, 0.001 ≤ b ≤ 0.1); Li a CoG b O2 (in the above formula, 0.90 ≤ a ≤ 1.8, 0.001 ≤ b ≤ 0.1); Li a MnG b O2 (in the above formula, 0.90 ≤ a ≤ 1.8, 0.001 ≤ b ≤ 0.1); Li a Mn2G bO4 (in the above formula, 0.90 ≤ a ≤ 1.8, 0.001 ≤ b ≤ 0.1); QO2; QS2; LiQS2; V2O5; LiV2O5; LiIO2; LiNiVO4; Li (3-f) J2(PO4)3(0 ≤ f ≤ 2); Li (3-f) Fe2(PO4)3(0 ≤ f ≤ 2); and LiFePO4. In the above chemical formula, A is Ni, Co, Mn or a combination thereof; B is Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, a rare earth element or a combination thereof; D is O, F, S, P or a combination thereof; E is Co, Mn or a combination thereof; T is F, S, P or a combination thereof; G is Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V or a combination thereof; Q is Ti, Mo, Mn or a combination thereof; I is Cr, V, Fe, Sc, Y or a combination thereof; J may be V, Cr, Mn, Co, Ni, Cu or a combination thereof.

[0118] A compound having a coating layer on the surface of the above-mentioned compound or a mixture of the above-mentioned compound and a compound having a coating layer may be used as a cathode active material.

[0119] The coating layer may include at least one coating element compound selected from the group consisting of an oxide of a coating element, a hydroxide of a coating element, an oxyhydroxide of a coating element, an oxycarbonate of a coating element, and a hydroxycarbonate of a coating element. The compounds forming these coating layers may be amorphous or crystalline. The coating elements included in the coating layer may include Mg, Al, Co, K, Na, Ca, Si, Ti, V, Sn, Ge, Ga, B, As, Zr, or mixtures thereof. The coating layer forming process may use any coating method as long as it can coat the compound with these elements by a method (e.g., spray coating, dipping, etc.) that does not adversely affect the physical properties of the positive electrode active material. Since this is well understood by those working in the relevant field, a detailed description thereof will be omitted.

[0120] The positive electrode active material layer may further include a binder (positive electrode binder) and / or a conductive material (positive electrode conductive material) in addition to the positive electrode active material described above.

[0121] The positive electrode binder serves to improve 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, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinyl pyrrolidone, polytetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene monomer rubber (EPDM rubber), sulfonated-EPDM, styrene butadiene rubber (SBR), fluoroelastomer, or various copolymers thereof, and one of these may be used alone or a mixture of two or more thereof, but is not limited thereto. The positive electrode binder may be included in an amount of 1 to 30 wt% based on the total weight of the positive electrode active material layer.

[0122] The cathode conductive material is used to provide conductivity to the electrode, and in the battery to be formed, as long as it does not cause a chemical change and has electronic conductivity, it can be used without any special restrictions. 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, summer black, etc.) and carbon fiber; metal powder or metal fiber such as copper, nickel, aluminum, silver; conductive whiskers such as zinc oxide or potassium titanate; conductive metal oxides such as titanium oxide; or conductive polymers such as polyphenylene derivatives, and the like. One type alone or a mixture of two or more types may be used among these, but the present invention is not limited thereto. The cathode conductive material may typically be included in an amount of 1 to 30 wt% based on the total weight of the cathode active material layer.

[0123] The positive electrode can be manufactured according to a conventional positive electrode manufacturing method. Specifically, the positive electrode can be manufactured by applying a composition for forming a positive electrode active material layer, including a positive electrode active material and optionally a positive electrode binder, a positive electrode conductive material, and / or a solvent, onto a positive electrode current collector, followed by drying and rolling. At this time, the types and contents of the positive electrode active material, positive electrode binder, and positive electrode conductive material are as described above.

[0124] In the composition for forming a positive electrode active material layer, the solvent may be a solvent generally used in the relevant technical field, such as dimethyl sulfoxide (DMSO), isopropyl alcohol, N-methylpyrrolidone (NMP), acetone, dimethylformamide (DMF), or water. One of these may be used alone or a mixture of two or more thereof may be used. The amount of solvent used is sufficient to dissolve or disperse the positive electrode active material, conductive material, and binder, taking into account the coating thickness and manufacturing yield of the slurry, and to have a viscosity that can exhibit excellent thickness uniformity when applied thereafter for manufacturing the positive electrode.

[0125] Alternatively, the positive electrode may be manufactured by casting a composition for forming a positive electrode active material layer on a separate support, then peeling the resulting film from the support and laminating it on a positive electrode current collector.

[0126] A separator separates the positive and negative electrodes and provides a passage for lithium ions. Any separator commonly used in lithium secondary batteries can be used without any particular restrictions. However, a separator having low resistance to ion movement of the electrolyte and excellent electrolyte moisture absorption capacity is preferable. Specifically, a porous polymer film, for example, a porous polymer film made of a polyolefin polymer such as ethylene homopolymer, propylene homopolymer, ethylene / butene copolymer, ethylene / hexene copolymer, and ethylene / methacrylate copolymer, or a laminated structure of two or more layers thereof, may be used. In addition, a conventional porous non-woven fabric, for example, a non-woven fabric made of high-melting-point glass fiber, polyethylene terephthalate fiber, etc. may also be used. In addition, a coated separator containing a ceramic component or polymer material to secure heat resistance or mechanical strength may be used, and may optionally be used in a single-layer or multi-layer structure.

[0127] Electrolytes that can be used in the manufacture of lithium secondary batteries include, but are not limited to, organic liquid electrolytes, inorganic liquid electrolytes, solid polymer electrolytes, gel-type polymer electrolytes, solid inorganic electrolytes, and molten inorganic electrolytes.

[0128] As a specific example, the organic liquid electrolyte may include an organic solvent and a lithium salt.

[0129] Any organic solvent that can serve as a medium through which ions involved in the electrochemical reaction of the battery can move may be used without particular restrictions. Specifically, organic solvents include ester solvents such as methyl acetate, ethyl acetate, γ-butyrolactone, and ε-caprolactone; ether solvents such as dibutyl ether or tetrahydrofuran; ketone solvents such as cyclohexanone; aromatic hydrocarbon solvents such as benzene and fluorobenzene; Carbonate solvents such as dimethylcarbonate (DMC), diethylcarbonate (DEC), methylethylcarbonate (MEC), ethylmethylcarbonate (EMC), ethylene carbonate (EC), and propylene carbonate (PC); alcohol solvents such as ethyl alcohol and isopropyl alcohol; nitriles such as R-CN (wherein R is a C2 to C20 linear, branched, or cyclic hydrocarbon group, and may include a double-bonded aromatic ring or an ether bond); amides such as dimethylformamide; dioxolanes such as 1,3-dioxolane; or sulfolanes can be used. Among these, a carbonate solvent is preferable, and a mixture of a cyclic carbonate (e.g., ethylene carbonate or propylene carbonate, etc.) having high ionic conductivity and high dielectric constant that can improve the charge / discharge performance of the battery and a linear carbonate compound having low viscosity (e.g., ethyl methyl carbonate, dimethyl carbonate, or diethyl carbonate, etc.) is more preferable.In this case, the performance of the electrolyte may be improved when the cyclic carbonate and the chain carbonate are mixed and used in a volume ratio of about 1:1 to about 1:9.

[0130] Lithium salts can be used without any special restrictions as long as they are compounds that can provide lithium ions used in lithium secondary batteries. Specifically, lithium salts include LiPF6, LiClO4, LiAsF6, LiBF4, LiSbF6, LiAl04, LiAlCl4, LiCF3SO3, LiC4F9SO3, LiN(C2F5SO3)2, LiN(C2F5SO2)2, LiN(CF3SO2)2. LiCl, LiI, or LiB(C2O4)2. It is recommended that the concentration of the lithium salt be within the range of 0.1 to 2.0 M. When the concentration of the lithium salt is within the above-mentioned range, the electrolyte can exhibit excellent electrolyte performance because it has appropriate conductivity and viscosity, and lithium ions can move effectively.

[0131] In addition to the aforementioned electrolyte components, the electrolyte may further include one or more additives, such as haloalkylene carbonate compounds such as difluoroethylene carbonate, pyridine, triethylphosphite, triethanolamine, cyclic ethers, ethylene diamine, n-glyme, hexamethylphosphoric acid triamide, nitrobenzene derivatives, sulfur, quinone imine dyes, N-substituted oxazolidinones, N,N-substituted imidazolidines, ethylene glycol dialkyl ethers, ammonium salts, pyrrole, 2-methoxyethanol, or aluminum trichloride, for the purpose of improving the life characteristics of the battery, suppressing battery capacity decline, and improving the discharge capacity of the battery. At this time, the additives may be included in an amount of 0.1 to 5 wt% based on the total weight of the electrolyte.

[0132] A lithium secondary battery may be placed within a battery case. The shape of the battery case may be one or more selected from the group consisting of a cylindrical shape using a can, a square shape, a pouch shape, and a coin shape. However, the shape of the battery case is not limited to this, and may have various shapes used in the relevant industry.

[0133] The present invention includes a battery module in which the secondary battery described above is used as a unit cell, and a plurality of unit cells are connected in series and / or in parallel.

[0134] The present invention includes a battery pack including a plurality of the above-described battery modules.

[0135] The present invention encompasses devices powered by the secondary battery, battery module, or battery pack described above. Representative examples of such devices include electronic and communication devices such as mobile phones, laptops, and PCs, as well as electric vehicles.

[0136] Hereinafter, the present invention will be specifically described through manufacturing examples. However, it should be noted that the manufacturing examples described below are intended only to illustrate and concretize the present invention and are not intended to limit the scope of the invention. This is because the scope of the invention is determined by the matters set forth in the patent claims and matters reasonably inferred therefrom.

[0137] Unless otherwise specified, in the manufacturing example, the mechanical processing of natural graphite was performed using a batch spheroidizing device in which three ring-shaped plates equipped with a plurality of rectangular hammers are fixed to a rotating shaft at a distance from each other, a circular plate is fixed to the lowest point of the rotating shaft relative to the direction of gravity together with the ring-shaped plates, and an air-flow classifier connected to a blower is positioned at the top of the spheroidizing device case for removing fine particles.

[0138] The physical and electrochemical properties described in the detailed description and patent claims are analyzed and measured according to the methods specified in the analysis and measurement methods below.

[0139] Analysis and Measurement Methods

[0140] Median diameter (D 50 ) and span

[0141] 0.01 g of the target substance was suspended in distilled water and mixed with a dispersant (Triton x-100) at a ratio of 100:1 (mass ratio) to prepare a suspension. After sonicating the prepared suspension for 1 minute, the cumulative volume diameter distribution was measured using a laser diffraction particle size distribution measuring device (Microtrac S3500). Cumulative volume-based median diameter D 50 is the diameter at the location where the cumulative volume is 50% in the cumulative volume diameter distribution. The span value is (D 90 -D 10 ) / D 50 is defined as D 10 In the cumulative volume diameter distribution, D means the diameter at the location where the cumulative volume is 10%, and 90 In the cumulative volume diameter distribution, it refers to the diameter at the location where the cumulative volume is 90%.

[0142] Tap Density (TD)

[0143] Tap density was measured using a tap density measuring device (Quantachrome Autotap) based on ASTM B527 by placing 20 g of the target material in a 50 mL container and tapping 3000 times with a stroke length of 1.2 cm (tapping speed = 284 times / min).

[0144] Pellet Density (PD)

[0145] Pellet density of the material to be measured (g / cm) 3) was measured using a density analysis device (Caver Press 4350, Carver Inc.). Specifically, the pellet density was calculated from the measured volume and the mass of the measured material injected into the mold after filling the mold (cylindrical mold with a diameter of 13 mm) with the measured material and pressurizing it with a pressure of 2 tons.

[0146] Strengthening orientation index

[0147] The X-ray diffraction pattern of the target material was obtained using an X-ray diffraction measuring device (BRUKER, D8 Advance) using the θ-2θ method, with Cu Kα rays, a scan step size of 0.02°, a scan speed of 10° / min, and a 2θ range of 10 to 90°.

[0148] XRD measurement (raw) data can be processed by removing noise (baseline) using a standard program equipped with the XRD device as a data processing and analysis program, such as the DIFFRAC.EVA program. The intensity of each of the (110), (102), (103), and (002) peaks is the maximum intensity of the corresponding peak. The (110), (102), (103), and (002) peaks are diffraction peaks of the (110), (102), (103), and (002) planes of the hexagonal phase of graphite, and each peak can be indexed by referring to JCPDS #75-1621 of hexagonal graphite, which is well known as a standard.

[0149] Specific Surface Area (SSA)

[0150] The target material was dried for 12 hours at a temperature of 300°C and a vacuum of 0.1 Torr or less for pretreatment, and then the nitrogen adsorption / desorption isotherm was measured. The nitrogen adsorption / desorption isotherm was measured using a surface area measuring device (Tristar Ⅱ Plus, Micromeritics, USA) at a temperature of 77 K and a relative pressure (P / P0) of 0.05 using nitrogen adsorption gas and liquid nitrogen. The BET specific surface area (m) was calculated from the nitrogen adsorption isotherm using the BET method. 2 / g) was produced.

[0151] Cathode material morphology based on scanning electron microscope images

[0152] Scanning electron microscope images were obtained at an ETH (acceleration voltage) of 3 kV, a WD (working distance) of 3 to 5 mm, and a scan speed of 3 to 6, with a magnification of 10,000 times and a resolution of 200 dpi or higher. Scanning electron microscope images (SEM images) in which particle outlines were analyzed were images in which at least one intact particle was present that was not obscured by other particles in the image.

[0153] In the obtained SEM images, D 50 0.7 D based on 50 1.4 D 50 Particles belonging to the size range of were subject to contour analysis. In other words, D 50 Similar size (0.7 D) 50 1.4 D 50 Contour analysis was performed using SEM images in which particles of size ) were fully observed, and the resolution of the images used for contour analysis was 100 DPI.

[0154] In a complete particle, the boundary inside / outside the particle was defined as the particle contour, and the longest length across the contour was calculated. The line corresponding to the longest length across the contour was set as the x-axis, its center as the origin (0,0), and the line perpendicular to the x-axis was set as the y-axis to establish a Cartesian coordinate system. Afterwards, one radial line was positioned on the x-axis (+ direction), and 36 radial lines extending from the origin (0,0) at 10-degree intervals were set, and the image coordinates of the points where each radial line and the contour line intersect (hereinafter collectively referred to as contour points) were obtained. Afterwards, linear regression analysis was performed using the coordinates of the obtained 36 contour points. Specifically, the linear regression analysis of neighboring points was a simple linear regression analysis (confidence level 95%) using the Ordinary Least Squares (OLS) method. A linear regression analysis on the contour was performed in the following steps, with the group of neighboring contour points used in a single regression analysis as the analysis group: Step 1) At least five neighboring contour points (similar-linear points) that are judged to be similar to a straight line by considering the contour are set as the analysis group. Step 2) A linear regression analysis was performed on the contour points forming the analysis group to obtain the coefficient of determination (R 2) is calculated. Step 3-1) Based on the calculated coefficient of determination, if the coefficient of determination is less than 0.97, the contour point located at the boundary of the analysis group (the contour point located at the end of the contour points belonging to the analysis group considering the contour) is removed and the analysis group is set again. Or, Step 3-2) is performed instead of Step 3-1). Step 3-2) Based on the calculated coefficient of determination, if the coefficient of determination is 0.97 or higher, the analysis group is set again by adding the contour point located adjacent to the boundary of the analysis group. Step 4) The analysis group is reset (Step 3-1) or 3-2)) and the linear regression analysis using the reset analysis group (Step 2)) is repeatedly performed to calculate the analysis group of the largest size with the coefficient of determination of 0.97 or higher. Step 5) The area of ​​the contour by the contour points forming the analysis group of the largest size is defined as one 'flat surface area'. Step 6-1) If, in the same contour, there are 5 or more consecutively located areas that are different from the areas of the contours already set as analysis groups in Step 1) and are judged to be similar to a straight line, the contour points belonging to the area are set as an analysis group, and Steps 2) to 5) are performed again. Step 6-2) If there are no more than 5 consecutively located areas that are judged to be similar to a straight line, the analysis for the contour (one contour) is terminated. At this time, the minimum size of the analysis group was 5 (5 contour points). In addition, if the determination coefficient value was not higher than 0.97 in the minimum size of 5 in consideration of the contour, it was determined that there was no flat surface area in the contour. In addition, the contour analysis was performed so that there were no contour points common to the analysis groups having determination coefficient values ​​higher than 0.97 in the contour, excluding the contour points located at the boundary. The proportion of the flat surface area in the contour (I) is the total number of contour points (n) belonging to the analysis groups with a coefficient of determination value of 0.97 or higher. L ) the total number of points located on the contour (n) T= ratio (n) divided by 36 L / n T *100 (%)) was calculated. The average value of the outline ratio (I) was taken as the ratio (II) of the flat surface area in the negative electrode material. In addition, the number of particle images (flat particles) determined to have a flat surface area in the outline analysis was divided by the total number of analyzed images and multiplied by 100 to calculate the ratio of flat particles (FS, %). There were more than 50 particle images for which outline analysis was performed.

[0155] Raman spectrum

[0156] Raman spectroscopy analysis was performed using a Raman spectrometer (HEDA-SERA), with a laser wavelength of 532 nm and a spectrometer resolution of 2.69 cm. -1 , the detector exposure time was 5 sec × 5 times (accumulation), and the grating was 1200 gr.

[0157] The Raman spectrum was a non-peak deconvoluted spectrum, and the R value was the maximum intensity I of the D band peak in the Raman spectrum. D The maximum intensity of the G-band peak I G It was calculated by dividing by . As is known, the D band peak is 1350 cm -1 1370 cm inland -1 The peak is located in the waveband region, and the G band peak is 1565 cm -1 1610 cm inland -1 It is a peak located in the waveband region.

[0158] Spherical shape

[0159] The sphericity of the target material was measured by ultrasonically dispersing 0.01 g of the target material powder in 5 mL of ethanol and then using a particle size analyzer (Flowcam 8100, Fluid Imaging Technologies).

[0160] Half cell

[0161] Negative electrode material manufactured in the examples or comparative examples: After preparing an aqueous slurry so that the weight ratio of styrene butadiene rubber (SBR) : carboxymethyl cellulose (CMC) is 97.5 : 1.5 : 1.0, the prepared slurry is applied to copper (Cu) foil, and then dried and rolled to form a negative electrode (loading amount 7 mg / cm 2 ) was manufactured.

[0162] A coin-type 2032 half-cell was fabricated using lithium foil as the counter electrode. A porous polypropylene film was used as the separator, and the electrolyte was a solution containing 1.15 M LiPF6 dissolved in a mixed solvent of ethylene carbonate (EC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DMC) in a volume ratio of 3:5:2, and 5% FEC (fluoroethylene carbonate) as an additive.

[0163] The manufactured cathodes and half-cells are also collectively referred to by the same numbers as the examples or comparative examples of the cathode material. For example, a half-cell manufactured using the cathode material manufactured in Example 1 is collectively referred to as the half-cell of Example 1.

[0164] Electrochemical properties

[0165] After half-cell manufacturing, it was aged at 25 ℃ for 48 hours, and the voltage was 0.005 V (vs. Li) at 25 ℃ with a current of 0.1 C-rate. + / Li) was charged with a constant current (CC). Then, charging was terminated when the current reached 0.005 C-rate while maintaining 0.005 V in constant voltage (CV) mode. When discharging, the discharge was performed with a constant current of 0.1 C-rate until the voltage reached 1.5 V. This charging and discharging cycle was repeated three times to complete the formation stage.

[0166] For high-rate power evaluation, the manufactured half-cells were charged in the same CC / CV manner as in the formation stage, but with a voltage range of 0.005 V to 1.5 V and a current of 0.2 C-rate. Subsequently, they were discharged with a current of 0.5 C-rate until the voltage reached 1.5 V. This charge / discharge cycle was repeated three times, and the capacity at the point of transition from CC mode to CV mode (when 0.005 V was reached) in the last charge cycle was recorded as the charge capacity.

[0167] Afterwards, the charge current was changed to 0.5, 1.0, and 2.0 C-rates, and all other conditions, including the discharge current, were kept the same, and charge and discharge cycles were performed three times for each C-rate. Similarly, the charge capacity at this time was recorded as the capacity at the time of switching from CC mode to CV mode.

[0168] The charging output evaluation index was defined as the value obtained by dividing the charging capacity at 2.0 C-rate by the charging capacity at 0.2 C-rate (charging output = (2.0 C / 0.2 C) X 100, %).

[0169] (Manufacturing Example 1)

[0170] Using a batch spheroidizing device, natural graphite (D 50 The raw material (21.4 μm) was spheroidized at 1600 rpm for 12 minutes to obtain spheroidized natural graphite (spheroidization degree 0.91, tap density 0.93 g / cm 3 ) was manufactured.

[0171] Spherical natural graphite was filled into a mold and then cold isostatically pressed at 450 MPa for 30 seconds to produce densified graphite. After cold isostatic pressing, the clumped particles were crushed into a size of 10-50 mm using a coarse crusher, finely crushed into a size of 10 mm or less using a pin mill, and finally crushed into particles using an air classifier to obtain graphite crushed into individual particles.

[0172] 100 parts by weight of crushed graphite and 3 parts by weight of petroleum pitch with a softening point of 250°C were mixed with a stirrer for 10 minutes, and then the mixture was heat-treated at 1200°C for 7 hours in an inert atmosphere to produce a particle core. D of the manufactured core 50 was 15.7 ㎛, the span value was 0.79, and the tap density was 1.16 g / cm 3 and the specific surface area was 1.7 m 2 / g was.

[0173] Super-P (surface area 62 m) with conductive carbon for 99 wt% of core 2 / g) 1 part by weight was added, and mechanically mixed at a rotation speed of 1800 rpm for 10 minutes using a nobilta mill to bind conductive carbon to the core, thereby manufacturing a negative electrode material. D of the manufactured negative electrode material 50 The thickness was 15.5 ㎛, the span value was 0.80, and the specific surface area was 2.35 m 2 / g. In addition, I was calculated from the Raman spectrum of the manufactured cathode material. D / I G The value (R value) was 0.43.

[0174] (Manufacturing Example 2)

[0175] Spheroidized natural graphite was produced by feeding natural graphite in the form of flakes into a spheroidizer in which a plurality of ACM mills were connected in series.

[0176] The manufactured spheroidized natural graphite was filled into a mold and then cold isostatically pressed at 150 MPa for 3 minutes to produce densified graphite. After the cold isostatic pressing was completed, the negative electrode material was manufactured through crushing, core manufacturing using pitch, and mixing of super-p and core in the same manner as in Manufacturing Example 1. The D of the manufactured negative electrode material 50 The thickness was 15.7 ㎛, the span value was 0.80, and the specific surface area was 2.89 m 2 / g was.

[0177] (Manufacturing Example 3)

[0178] After introducing flaky natural graphite into a spheroidizer with multiple ACM mills connected in series to produce spheroidized natural graphite, the spheroidized natural graphite and pitch were mixed and heat-treated in the same manner as in Manufacturing Example 1 without performing cold isostatic pressing to produce a core, and then the super-p and core were mixed in the same manner as in Manufacturing Example 1 to produce a negative electrode material. The D of the manufactured negative electrode material 50 The thickness was 16.17 ㎛, the span value was 0.81, and the specific surface area was 3.10 m 2 / g was.

[0179] Tap density (TD, g / cm) of the negative electrode material manufactured in Manufacturing Examples 1 to 3 3 ), pellet density (PD, g / cm 3 ), difference between PD and TD (PD-TD), 1 wt% WT and 62 m 2 The compressibility calculated using the SSA(CC) value of / g, the strengthening orientation index calculated from the X-ray diffraction pattern of the negative electrode material, the fraction of particles having a flat surface area (FS, %), and the ratio of the flat surface area in the negative electrode material based on a coefficient of determination of 0.97 or higher (II) are summarized in Table 1.

[0180] TDPDPD-TD Compression Strength Strength Orientation Index FS Ratio (II) Manufacturing Example 11.171.860.691.803.6396%69.7% Manufacturing Example 21.161.890.732.291.4872%36.2% Manufacturing Example 31.031.710.622.511.0484%40.3%

[0181] As can be seen from Table 1, the negative electrode material manufactured in Manufacturing Example 1, which has a denser natural graphite structure, has the highest tap density, and has a lower pellet density than the negative electrode material of Manufacturing Example 2 due to small deformation caused by the applied pressure. Compressibility is a property that indirectly indicates the specific surface area of ​​the core in the manufactured negative electrode material, and the specific surface area of ​​the core manufactured in Manufacturing Example 1 is 1.73 m 2 / g, and the specific surface area of ​​the core manufactured in Manufacturing Example 3 is 2.23 m2 Considering that / g, the natural graphite in the negative electrode material is dense and has a small surface roughness, and the smaller the specific surface area of ​​the core, the more similar the compressibility becomes to the specific surface area of ​​the actual core.

[0182] In addition, when examining the reinforcement orientation index values ​​of the negative electrode materials manufactured in Manufacturing Examples 1 to 3 of Table 1, it can be seen that the reinforcement orientation index value increases due to cold isotropic pressing, and in addition, it can be seen that the reinforcement orientation index value is greatly affected by the state of the spheroidized natural graphite before cold isotropic pressing. In the X-ray diffraction pattern of the negative electrode material, when the crystallographic isotropy is considered only by the diffraction peak due to the (110) plane and the diffraction peak due to the (004) plane as in the past, the orientation index (I) of the negative electrode material of Manufacturing Example 1 110 / I 004 ) was 54.7, and the orientation index of the negative electrode material of Manufacturing Example 2 was 57.6, which was higher in Manufacturing Example 2.

[0183] When examining the FS value and ratio (II) value related to the shape of the negative electrode material, the negative electrode material of Manufacturing Example 1 had the highest FS value and the largest ratio (II) value, and the negative electrode material of Manufacturing Example 2 also had a high FS value of up to 72%, but the lowest ratio (II) value. This is because the negative electrode material manufactured in Manufacturing Example 2 had a relatively uneven surface with a mixture of concave and convex curved areas rather than a flat surface. In addition, in the case of the negative electrode material manufactured in Manufacturing Example 3, it can be interpreted that it was spheroidized into a spherical shape pressed by a strong shear force and had a relatively high ratio (II) value.

[0184] Table 2 summarizes the discharge capacity (mAh / g), initial efficiency (%), and high-rate output characteristics (%, 2.0C / 0.2C) of the half-cell equipped with the negative electrode material manufactured in the manufacturing example.

[0185] Discharge capacity, initial efficiency, high-rate output characteristics, manufacturing example 13569337, manufacturing example 23579327, manufacturing example 33559224

[0186] When examining the electrochemical properties of the negative electrode materials manufactured in Manufacturing Examples 1 to 3, the discharge capacity and initial efficiency were similar to each other, but they exhibited significantly different high-rate output characteristics, and the negative electrode material manufactured in Manufacturing Example 1 exhibited significantly higher high-rate output characteristics than artificial graphite. The present invention is not limited to the examples, but can be manufactured in various different forms, and a person skilled in the art to which the present invention pertains will understand that the present invention can be implemented in other specific forms without changing the technical spirit or essential characteristics of the present invention. Therefore, it should be understood that the examples described above are illustrative in all aspects and not restrictive.

Claims

1. A core comprising particulate natural graphite coated with a coating layer containing amorphous carbon and conductive carbon bonded to the core, satisfying the following formula 1, and having a density of 1.10 g / cm 3 A negative electrode material for a lithium secondary battery having a tap density (TD) above. (Formula 1) 0.50 ≤ PD-TD ≤ 0.90 (In Equation 1, PD is the pellet density of the negative electrode material (g / cm 3 ) and TD is the tap density of the cathode material (g / cm). 3 )am) 2. In paragraph 1, The above negative electrode material is a negative electrode material for a lithium secondary battery, having a reinforcement orientation index of 3.0 or more, as defined by the following equation 2. (Formula 2) Strengthening orientation index = [I 110 + I 102 + I 103 ] / [I 002 ] × 100 (I in Equation 2 110 , I 102 , I 103 and I 002 In the X-ray diffraction pattern of the cathode material, the maximum intensities of the (110) plane diffraction peak, the (102) plane diffraction peak, the (103) plane diffraction peak, and the (002) plane diffraction peak) 3. In paragraph 1, A negative electrode material for a lithium secondary battery, having a compression ratio of 2.0 or less, as defined by the following equation 3. (Formula 3) Compression = [(SSA(AM)-SSA(CC)×WT / 100)] / [(1-WT / 100)] (In Equation 3, SSA(AM) is the specific surface area of ​​the cathode material (m 2 / g), and SSA(CC) is the specific surface area of ​​conductive carbon (m 2 / g), and WT is the weight% of conductive carbon contained in the negative electrode material based on the total weight of the negative electrode material.

4. In paragraph 1, In the scanning electron microscope image of the above-mentioned negative electrode material at a magnification of 10,000 times, when the center of the longest length crossing the contour of the negative electrode material is set as the center of the contour, and the contact points between 36 radial lines with an angle of 10° are used for linear regression analysis of the contour, the coefficient of determination (R) is 0.95 or more. 2 ) is the sum of the number of contact points belonging to the area of ​​the contour (n) L ) the total number of contact points located on the contour (n) T ) divided by the ratio (n) L / n T *A negative electrode material for a lithium secondary battery, having an average value of 100% or more.

5. In paragraph 1, The specific surface area of ​​the above cathode material is 2.0 m 2 / g to 3.5 m 2 / g, negative electrode material for lithium secondary batteries.

6. In paragraph 1, The cumulative volume-based median diameter (D) of the above cathode material 50 ) is a negative electrode material for a lithium secondary battery, having a diameter of 5 to 25 μm.

7. In paragraph 1, The above natural graphite is a negative electrode material for a lithium secondary battery, which is a particle in which natural graphite fragments are joined, folded or assembled.

8. In Article 1, The above negative electrode material is a negative electrode material for a lithium secondary battery that satisfies the following equation 4. (Formula 4) I D / I G ≤ 0.70 (In Equation 4, I D is the maximum intensity of the D band peak in the Raman spectrum of the cathode material, and I G is the maximum intensity of the G band peak in the same Raman spectrum) 9. In paragraph 1, The above conductive carbon is a negative electrode material for a lithium secondary battery, which includes carbon black.

10. In paragraph 9, The above carbon black is an anode material for a lithium secondary battery, wherein at least one is selected from the group consisting of acetylene black, ketjen black, channel black, furnace black, lamp black, and thermal black.

11. In paragraph 9, The above carbon black is a negative electrode material for a lithium secondary battery, which is dispersed and bonded to the core by mechanical force.

12. In paragraph 1, A negative electrode material for a lithium secondary battery, wherein the weight ratio of the core contained in the negative electrode material to the conductive carbon is 100:0.1 to 5.

0.

13. In paragraph 1, A negative electrode material for a lithium secondary battery, wherein the weight ratio of graphite to amorphous carbon contained in the core is 100:1 to 10.

14. A negative electrode for a lithium secondary battery comprising a negative electrode material according to any one of claims 1 to 13.

15. A lithium secondary battery comprising a negative electrode according to Article 14.