Negative electrode plate for rechargeable lithium battery and rechargeable lithium battery comprising negative electrode plate

Abstract

A negative electrode plate for a rechargeable lithium battery and a rechargeable lithium battery are provided. The negative electrode plate for a rechargeable lithium battery can include a negative electrode active material, which can include a first negative electrode active material, a second negative electrode active material, and a third negative electrode active material. The first negative electrode active material can include natural graphite and a coating layer. The natural graphite can include secondary particles. The secondary particles can include an aggregate of primary particles. The coating layer can include amorphous carbon and surround the secondary particles of the natural graphite. The first negative electrode active material can have an orientation degree of 90 or less and can have a d002 in a range of about 3.356 Å to about 3.360 Å. The second negative electrode active material can include graphite. The third negative electrode active material can have a sphericity of about 0.9 to about 1.0 and can include silicon nanoparticles and an amorphous carbon coating layer disposed on a surface of the silicon nanoparticles.

Description

[0001] This application claims priority and benefit to Korean Patent Application No. 10-2024-0175708, filed on November 29, 2024, with the Korean Intellectual Property Office, and Korean Patent Application No. 10-2024-0175710, filed on November 29, 2024, the entire disclosure of which is incorporated herein by reference. Technical Field

[0002] The present invention relates to a negative electrode plate for a rechargeable lithium battery and a rechargeable lithium battery including the negative electrode plate. Background Technology

[0003] Recently, with the rapid proliferation of battery-powered electronic devices such as mobile phones, laptops, and electric vehicles, the demand for rechargeable batteries with high energy density and high capacity is increasing rapidly. Therefore, research and development to improve the performance of rechargeable lithium batteries is actively underway.

[0004] A rechargeable lithium battery is a battery that includes a positive electrode and a negative electrode, both containing active materials capable of inserting and deintercalating lithium ions, and generates electrical energy through a redox reaction when lithium ions are deintercalated from the positive electrode and inserted into the negative electrode or deintercalated from the negative electrode and inserted into the positive electrode. Summary of the Invention

[0005] This invention relates to a negative electrode plate for rechargeable lithium batteries that exhibits high energy density and boost charging and provides long cycle life for rechargeable lithium batteries.

[0006] The present invention also relates to providing a negative electrode plate for a rechargeable lithium battery that exhibits improved expansion characteristics.

[0007] The present invention also relates to providing a rechargeable lithium battery including a negative electrode plate.

[0008] A negative electrode plate for a rechargeable lithium-ion battery according to some embodiments of this disclosure may include a negative electrode active material. The negative electrode active material may include a first negative electrode active material, a second negative electrode active material, and a third negative electrode active material. The first negative electrode active material may include natural graphite and a first coating layer. The natural graphite may include secondary particles. The secondary particles may be aggregates of primary particles. The first coating layer may include amorphous carbon. The first coating layer may surround each of the secondary particles. The first negative electrode active material may have an orientation degree of 90 or less and may have a d002 in the range of about 3.356 Å to about 3.360 Å. The second negative electrode active material may include graphite. The third negative electrode active material may have a sphericity of about 0.9 to about 1.0. The third negative electrode active material may include silicon nanoparticles and a second coating layer comprising amorphous carbon. The second coating layer may surround each of the silicon nanoparticles.

[0009] In some embodiments, the first negative electrode active material may have an Hg accumulation pore volume of about 0.01 mL / g to about 0.06 mL / g.

[0010] In some embodiments, the first negative electrode active material may have a particle density of about 1.60 g / cc to about 1.80 g / cc.

[0011] In some embodiments, the first negative electrode active material may have a sphericity greater than or equal to 0.85.

[0012] In some embodiments, the ratio of the major axis length of the primary particles to the average particle size D50 of the secondary particles can be from about 2 to about 10.

[0013] In some embodiments, each of the primary particles may have a sheet-like geometry, and each of the secondary particles may have a substantially spherical geometry.

[0014] In some embodiments, the major axis length of each of the primary particles is in the range of about 10 μm to about 200 μm.

[0015] In some embodiments, the average particle size D50 of the secondary particles may be less than or equal to about 30 μm.

[0016] In some embodiments, the first negative electrode active material may further include a third coating layer comprising amorphous carbon, the third coating layer surrounding each of the primary particles.

[0017] In some embodiments, amorphous carbon may include soft carbon, hard carbon, mesophase pitch carbide, or calcined coke.

[0018] In some embodiments, the weight ratio of natural graphite to amorphous carbon in the first negative electrode active material is about 90:10 to about 75:25 relative to the total 100 parts by weight of natural graphite and amorphous carbon in the first negative electrode active material.

[0019] In some embodiments, the third negative electrode active material may have pores including mesopores.

[0020] In some embodiments, the percentage of the mesopore volume to the total pore volume of the third negative electrode active material can be from about 30% to about 70%.

[0021] In some embodiments, the span value can be expressed by the following equation: Span = (D90 - D10) / D50. D10 can be the particle size of particles representing approximately 10% by volume of the third negative electrode active material in the particle size distribution. D50 can be the average particle size of particles representing approximately 50% by volume of the third negative electrode active material in the particle size distribution. D90 can be the particle size of particles representing approximately 90% by volume of the third negative electrode active material in the particle size distribution. The third negative electrode active material can have a span value of approximately 1.1 to approximately 1.6.

[0022] In some embodiments, the third negative electrode active material may comprise about 55 wt% to about 64 wt% of silicon nanoparticles relative to 100 wt% of the total third negative electrode active material. The third negative electrode active material may comprise about 36 wt% to about 45 wt% of amorphous carbon relative to 100 wt% of the total third negative electrode active material.

[0023] In some embodiments, the third negative electrode active material may further include a polymer layer surrounding the second coating layer.

[0024] In some embodiments, the polymer layer may comprise a copolymer of polyvinyl alcohol and polyacrylic acid.

[0025] In some embodiments, the negative electrode active material may include a first negative electrode active material in an amount of about 20 wt% to about 75 wt%, a second negative electrode active material in an amount of about 20 wt% to about 75 wt%, and a third negative electrode active material in an amount of about 1 wt% to about 20 wt%.

[0026] In some embodiments, the graphite of the second negative electrode active material may have an average particle size D50 of about 10 μm to about 20 μm, a particle density of about 1.1 g / cc to about 1.6 g / cc, and a particle size of less than or equal to about 10 μm. 2 Artificial graphite with a specific surface area of ​​ / g and an orientation degree greater than or equal to about 90.

[0027] In some embodiments, the negative electrode plate may also include a conductive material.

[0028] In some embodiments, the conductive material may include carbon nanotubes.

[0029] In some embodiments, the negative electrode plate may include about 0.01 wt% to about 5 wt% of a conductive material.

[0030] A rechargeable lithium battery according to some embodiments of the present disclosure may include a positive electrode and a negative electrode plate as described above.

[0031] The negative electrode plate for a rechargeable lithium battery according to some embodiments of the present disclosure can simultaneously achieve high energy density, long cycle life, boost charging effect, and improved expansion characteristics, as well as excellent performance for rechargeable lithium batteries. Attached Figure Description

[0032] The accompanying drawings illustrate embodiments of the present disclosure, and together with the detailed description of the present disclosure, aspects and features of the present disclosure are further described. Therefore, the present disclosure should not be construed as limited to the drawings.

[0033] Figure 1 This is a schematic diagram of the first negative electrode active material according to some embodiments of the present disclosure.

[0034] Figure 2 This is a schematic diagram illustrating a rechargeable lithium battery according to some embodiments of the present disclosure.

[0035] Figure 3 This is a schematic cross-sectional view of a rechargeable lithium battery according to some embodiments of the present disclosure.

[0036] Figure 4 This is a schematic diagram illustrating a rechargeable lithium battery according to some embodiments of the present disclosure.

[0037] Figure 5 This is a schematic diagram illustrating a rechargeable lithium battery according to some embodiments of the present disclosure. Detailed Implementation

[0038] In the following, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. The terms or words used in this specification and claims should not be construed as limited to their ordinary or dictionary meanings, but should be interpreted as meanings and concepts consistent with the technical spirit of the present disclosure, based on the principle that the inventor, as his / her own lexicographer, can appropriately define the concepts of the terms to best interpret his / her invention.

[0039] The embodiments described in this specification and the constructions shown in the accompanying drawings are merely some embodiments of this disclosure and do not represent all technical concepts, aspects, and features of this disclosure. Therefore, it should be understood that various equivalents and modifications may exist to replace or modify the embodiments described herein at the time of filing this application.

[0040] It will be understood that when a layer or element is referred to as being "between" two layers, the layer or element may be the only layer between the two layers, or one or more intermediary layers may exist. It will be understood that when an element or layer is referred to as being "on" another element or layer, "connected to," or "bonded to" another element or layer, the element or layer may be directly on, directly connected to, or directly bonded to the other element or layer, or one or more intermediary elements or layers may exist. When an element or layer is referred to as being "directly on" another element or layer, "directly connected to," or "directly bonded to" another element or layer, no intermediary element or layer exists. For example, when a first element is described as being "bonded" or "connected" to a second element, the first element may be directly bonded to or directly connected to the second element, or the first element may be indirectly bonded to or indirectly connected to the second element via one or more intermediary elements.

[0041] In the accompanying drawings, the dimensions of various elements, layers, etc., may be exaggerated for clarity. The same reference numerals denote the same elements. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items. Furthermore, in describing embodiments of this disclosure, the use of "may" refers to "one or more embodiments of this disclosure." Expressions such as "at least one of..." and "any one of..." modify the entire list of elements, not individual elements within that list. When phrases such as "at least one of A, B, and C," "at least one of A, B, or C," "at least one selected from the group of A, B, and C," or "at least one selected from A, B, and C" are used to specify a list of elements A, B, and C, the phrase may refer to any suitable combination or subset of A, B, and C, and all suitable combinations or subsets, such as A, B, C, A and B, A and C, B and C, or A and B and C. As used herein, the term "use" and its variations may be considered synonymous with the term "utilize" and its variations, respectively. As used herein, the terms "substantially," "about (approximately)," and similar terms are used as approximate terms rather than as terms of degree, and are intended to account for inherent biases in measurements or calculations that will be recognized by one of ordinary skill in the art.

[0042] It will be understood that although the terms first, second, third, etc., may be used herein to describe various elements, components, regions, layers, and / or portions, these elements, components, regions, layers, and / or portions should not be limited by these terms. These terms are used to distinguish one element, component, region, layer, or portion from another element, component, region, layer, or portion. Therefore, without departing from the teachings of the exemplary embodiments, the first element, first component, first region, first layer, or first portion discussed below may be referred to as a second element, second component, second region, second layer, or second portion.

[0043] For ease of description, spatial relative terms such as “below,” “under,” “down,” “above,” “above,” etc., may be used herein to describe the relationship between one element or feature as shown in the accompanying drawings and another element(s). It will be understood that, in addition to the orientations depicted in the drawings, the spatial relative terms are also intended to cover different orientations of the device in use or operation. For example, if the device in the drawings is flipped, an element described as “below” or “under” other elements or features will subsequently be oriented “above” or “above” said other elements or features. Thus, the term “below” can encompass both above and below orientations. The device may be otherwise oriented (rotated 90 degrees or in other orientations), and the spatial relative descriptive terms used herein should be interpreted accordingly.

[0044] The terminology used herein is for the purpose of describing embodiments of this disclosure and is not intended to limit the disclosure. As used herein, unless the context clearly indicates otherwise, the singular forms “a” and “an” are also intended to include the plural forms. It will also be understood that when the terms “comprising,” “including,” and / or variations thereof are used in this specification, it indicates the presence of the stated features, integrals, steps, operations, elements, and / or components, but does not preclude the presence or addition of one or more other features, integrals, steps, operations, elements, components, and / or groups thereof.

[0045] Furthermore, any numerical range disclosed and / or described herein is intended to include all subranges containing the same numerical precision within the described range. For example, the range “1.0 to 10.0” is intended to include all subranges between the described minimum value of 1.0 and the described maximum value of 10.0 (and includes both the described minimum value of 1.0 and the described maximum value of 10.0), i.e., having a minimum value equal to or greater than 1.0 and a maximum value equal to or less than 10.0, such as 2.4 to 7.6. Any maximum numerical limit described herein is intended to include all lower numerical limits contained therein, and any minimum numerical limit described in this specification is intended to include all higher numerical limits contained therein. Therefore, the applicant reserves the right to amend this specification and the claims to expressly describe any subranges contained within the range expressly described herein. All such ranges are inherently described in this specification such that amendments to expressly describe any such subranges will be required.

[0046] Referring to two compared elements, features, etc., as “identical” can mean that they are “substantially identical.” Therefore, the phrase “substantially identical” can include cases with a deviation considered low in the art (e.g., 5% or less). Additionally, when a parameter is said to be uniform in a given region, it can mean that it is uniform in terms of its mean.

[0047] Throughout this specification, unless otherwise stated, each element may be singular or plural.

[0048] Arranging any element "above (or below)" or "on (below)" an element can mean that the arbitrary element can be configured to contact the upper (or lower) surface of the element, and another element can be placed between the element and the arbitrary element disposed on (or below) the element.

[0049] Additionally, it will be understood that when a component is referred to as “linked,” “combined,” or “connected” to another component, these components can be directly “combined,” “linked,” or “connected” to each other, or another component can be “placed” between these components.

[0050] Throughout this specification, when “A and / or B” is stated, it means A, B, or A and B, unless otherwise stated. That is, “and / or” includes any or all combinations of the listed items. When “C to D” is stated, it means C or greater and D or less, unless otherwise stated.

[0051] Unless otherwise stated herein, when a component such as a layer, film, region, or plate is referred to as being “on” another component, it includes not only the case where it is “directly on” the other component, but also the case where another component is present in between.

[0052] The phrase “their combination” can mean mixtures of components, laminates, complexes, copolymers, alloys, blends, and reaction products.

[0053] Unless otherwise defined herein, particle size can be the average particle diameter (or average particle size). Alternatively, particle size refers to the average particle size D50, which is the diameter of particles that constitute 50% of the cumulative volume in the particle size distribution. The average particle size D50 can be measured using methods known to those skilled in the art (e.g., using a particle size analyzer, transmission electron microscopy, or scanning electron microscopy). Alternatively, the average particle size can be measured using a measuring device that utilizes dynamic light scattering, and the average particle size D50 value can be obtained by performing data analysis, counting the number of particles in each particle size range, and then calculating the D50 value. Optionally, the average particle size can be measured using laser diffraction. When measuring the average particle size using laser diffraction, more specifically, the average particle size D50 can be calculated based on a 50% particle size distribution after dispersing the target particles in a dispersion medium, introducing the particles into a commercially available laser diffraction particle size measuring device (such as the MT 3000 from Microtrac), and irradiating the particles with ultrasound at an output of approximately 60W at approximately 28 kHz.

[0054] When the particles are spherical, size can mean diameter.

[0055] In this manual, "dimension" refers to the diameter when the cross-section of the object being measured is circular, and the length of the longest axis of the cross-section when the cross-section of the object being measured is not circular.

[0056] In this specification, particle size "D10" refers to the particle size of particles having a cumulative volume of 10% by volume in the particle size distribution. In this specification, particle size "D90" refers to the particle size of particles having a cumulative volume of 90% by volume in the particle size distribution. Both "D10" and "D90" can be obtained using the method described above for measuring the D50 value.

[0057] Particle size can be evaluated using a particle size analyzer (Beckman Coulter, LS 13 320 XR).

[0058] The terminology used in this specification is for describing embodiments of this disclosure and is not intended to limit the scope of the disclosure.

[0059] According to some embodiments, the negative electrode plate for rechargeable lithium batteries can simultaneously provide long cycle life, high energy density, boost charging performance, and improved expansion characteristics.

[0060] The term “orientation degree” as used herein can refer to the ratio of the diffraction peak intensity I(002) of the (002) plane to the diffraction peak intensity I(110) of the (110) plane, as measured by X-ray diffraction analysis using CuKα radiation.

[0061] As used herein, “d002” can refer to the interplanar spacing of the (002) plane of the first negative electrode active material, as measured by X-ray diffraction analysis using CuKα radiation.

[0062] A negative electrode plate for a rechargeable lithium battery according to some embodiments includes a negative electrode active material. The negative electrode active material may include a mixture of a first negative electrode active material, a second negative electrode active material, and a third negative electrode active material. The first negative electrode active material may include natural graphite comprising secondary particles in which primary particles are aggregated, and a coating layer surrounding the secondary particles and comprising amorphous carbon, and has an orientation degree of about 90 or less and a d002 in the range of about 3.356 Å to about 3.360 Å. The second negative electrode active material may be graphite, and the third negative electrode active material may include silicon nanoparticles and an amorphous carbon coating layer disposed on the surface of the silicon nanoparticles, and may have a sphericity of about 0.9 to about 1.0.

[0063] The negative electrode plate for rechargeable lithium batteries may include this mixture as the negative electrode active material, thereby providing high capacity retention, high energy density, boost charging effect, enhanced fast charging cycle life and low swelling rate.

[0064] In some embodiments, the mixture may be included in the negative electrode plate in an amount of 95 wt% or more (e.g., 95 wt% to about 100 wt%, about 99 wt% to about 100 wt%, or about 100 wt%) of the total negative electrode active material. Within the above range, the above-described effects of the negative electrode plate can be achieved.

[0065] In some embodiments, the negative electrode active material may be included in an amount of, for example, from about 90 wt% to about 99.5 wt% (e.g., from about 95 wt% to about 99.5 wt%, from about 90 wt% to about 99 wt%) of the negative electrode plate. Improved battery capacity can be achieved within the above range.

[0066] When the first negative electrode active material is absent in the mixture, it may be difficult to achieve a battery cell with high energy density due to the low density of the negative electrode plate, and the boost charging effect may deteriorate.

[0067] When the mixture does not contain a second negative electrode active material, the long cycle life effect may be reduced under high temperature conditions.

[0068] When the mixture does not contain a third negative electrode active material, the increase in capacity per volume may be reduced.

[0069] In some embodiments, the mixture of the first negative electrode active material, the second negative electrode active material, and the third negative electrode active material may contain approximately 20 wt% to approximately 75 wt% (e.g., 20 wt%, 21 wt%, 22 wt%, 23 wt%, 24 wt%, 25 wt%, 26 wt%, 27 wt%, 28 wt%, 29 wt%, 30 wt%, 31 wt%, 32 wt%, 33 wt%, 34 wt%, 35 wt%, 36 wt%, 37 wt%, 38 wt%, 39 wt%, 40 wt%, 41 wt%, 42 wt%, 43 wt%, 44 wt%, 45 wt%). 46wt%, 47wt%, 48wt%, 49wt%, 50wt%, 51wt%, 52wt%, 53wt%, 54wt%, 55wt%, 56wt%, 57wt%, 58wt%, 59wt%, 60wt%, 61wt%, 62wt%, 63wt%, 64wt%, 65wt%, 66wt%, 67wt%, 68wt%, 69wt%, 70wt%, 71wt%, 72wt%, 73wt%, 74wt%, or 75wt%, or for example, about 20wt% to about 65wt%, about 20wt% to about 60wt%, or about 23wt%. The first negative electrode active material may be included in approximately 20 wt% to approximately 75 wt% (e.g., 20 wt%, 21 wt%, 22 wt%, 23 wt%, 24 wt%, 25 wt%, 26 wt%, 27 wt%, 28 wt%, 29 wt%, 30 wt%, 31 wt%, 32 wt%, 33 wt%, 34 wt%, 35 wt%, 36 wt%, 37 wt%, 38 wt%, 39 wt%, 40 wt%, 41 wt%, 42 wt%, 43 wt%, 44 wt%, 45 wt%, 46 wt%, 47 wt%, 48 wt%, 49 wt%). 50wt%, 51wt%, 52wt%, 53wt%, 54wt%, 55wt%, 56wt%, 57wt%, 58wt%, 59wt%, 60wt%, 61wt%, 62wt%, 63wt%, 64wt%, 65wt%, 66wt%, 67wt%, 68wt%, 69wt%, 70wt%, 71wt%, 72wt%, 73wt%, 74wt% or 75wt%, or for example, about 20wt% to about 65wt%, about 20wt% to about 60wt%, or about 23wt% to about 75wt%) including a second negative electrode active material;The third negative electrode active material may be included in amounts from about 1 wt% to about 20 wt% (e.g., 1 wt%, 2 wt%, 3 wt%, 4 wt%, 5 wt%, 6 wt%, 7 wt%, 8 wt%, 9 wt%, 10 wt%, 11 wt%, 12 wt%, 13 wt%, 14 wt%, 15 wt%, 16 wt%, 17 wt%, 18 wt%, 19 wt%, or 20 wt%, or for example, about 1 wt% to about 15 wt%, about 1 wt% to about 14 wt%, about 1 wt% to about 10 wt%, or about 5 wt% to about 7 wt%). Within these ranges, high energy density and boost charging performance can be provided, and fast charging cycle life can be further improved.

[0070] In some embodiments, the total amount of the first negative electrode active material and the second negative electrode active material in the mixture can be from about 85 wt% to about 99 wt% (e.g., 85 wt%, 86 wt%, 87 wt%, 88 wt%, 89 wt%, 90 wt%, 91 wt%, 92 wt%, 93 wt%, 94 wt%, 95 wt%, 96 wt%, 97 wt%, 98 wt%, or 99 wt%, or for example, about 86 wt% to about 99 wt%, or about 90 wt% to about 99 wt%), and the third negative electrode active material can be from about 1 wt% to about 15 wt% (e.g., 1 wt%, 2 wt%, 3 wt%, 4 wt%, 5 wt%, 6 wt%, 7 wt%, 8 wt%, 9 wt%, 10 wt%, 11 wt%, 12 wt%, 13 wt%, 14 wt%, or 15 wt%, or for example, about 1 wt% to about 14 wt%, or about 1 wt% to about 10 wt%). Within the above ranges, boost charging effect and fast charging cycle life improvement effect can be achieved.

[0071] In some embodiments, a third negative electrode active material with a specific capacity of about 500 mAh / g or less may be included.

[0072] Based on a total of 100 parts by weight of the first negative electrode active material and the second negative electrode active material, the weight ratio of the first negative electrode active material to the second negative electrode active material can be from about 10:90 to about 90:10 (e.g., from about 25:75 to about 75:25, from about 40:60 to about 60:40, or about 50:50). Within the above range, boost charging effect and / or improved fast charging cycle life effect can be achieved.

[0073] In some embodiments, the density of the negative electrode plate can be from about 1.3 g / cc to about 1.7 g / cc (e.g., from about 1.3 g / cc to about 1.68 g / cc). Within this range, high energy density can be achieved, and boost charging can be facilitated.

[0074] First negative electrode active material The first negative electrode active material may include natural graphite containing secondary particles in which primary particles are aggregated, and a coating layer surrounding the secondary particles and containing amorphous carbon, and the first negative electrode active material may have an orientation degree of about 90 or less and a d002 of about 3.356 Å to about 3.360 Å.

[0075] Natural graphite is generally advantageous as a negative electrode active material in batteries, but its high resistivity leads to poor charging characteristics. Furthermore, due to the numerous internal pores in natural graphite, side reactions can adversely affect extended cycle life and expansion rate.

[0076] The first negative electrode active material can be prepared by significantly reducing the average particle size of the secondary particles of natural graphite into fine particles to provide low resistance. In order to offset the efficiency reduction caused by the increase in the specific surface area of ​​the secondary particles, the first negative electrode active material is calcined at the following temperature to reduce the specific surface area of ​​the first negative electrode active material and at the same time provide high efficiency for the first negative electrode active material.

[0077] The first negative electrode active material comprises natural graphite, amorphous carbon, and a coating layer, and satisfies the above-mentioned orientation degree and d002. Therefore, the first negative electrode active material improves the battery capacity and significantly increases the charging C-rate, thereby enhancing the boost charging performance of the rechargeable lithium battery. Although the first negative electrode active material includes natural graphite, it can significantly reduce resistance, provide high energy density, suppress side reactions with the electrolyte, and improve lifespan.

[0078] As the orientation degree decreases, the edge planes of natural graphite become oriented in random directions, thereby increasing the random orientation of the first negative electrode active material. This promotes lithium-ion insertion into and extraction from the natural graphite secondary particles, thus improving the capacity characteristics of the rechargeable lithium battery. The orientation degree can be about 80 or less (e.g., about 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 5). The orientation degree can be obtained by adjusting the average particle size D50 of the secondary particles and the long axis length of the primary particles. In the first negative electrode active material, the average particle size D50 of the secondary particles can be significantly reduced to lower the high resistivity of natural graphite.

[0079] The average particle size D50 of the secondary particles in the first negative electrode active material is significantly smaller than the long axis length of the primary particles. Secondary particles can be generated by wrinkling the primary particles. The first negative electrode active material may include amorphous carbon and can be manufactured by heat treatment at 2500°C or higher as described below, thereby achieving a high degree of graphitization. A high degree of graphitization can help improve the capacity of the first negative electrode active material and prevent efficiency reduction caused by the decrease in the average particle size of the secondary particles and the increase in specific surface area. The d002 of the first negative electrode active material is from about 3.356 Å to about 3.360 Å. Within this range, the decrease in battery efficiency caused by the increase in specific surface area of ​​the first negative electrode active material, which includes secondary particles with a relatively small average particle size D50, can be offset, and high capacity can be provided. d002 can be 3.356 Å, 3.3561 Å, 3.3562 Å, 3.3563 Å, 3.3564 Å, 3.3565 Å, 3.3566 Å, 3.3567 Å, ​​3.3568 Å, 3.3569 Å, 3.357 Å, 3.3571 Å, 3.3572 Å, 3.3573 Å, 3.3574 Å, 3.3575 Å, 3.3576 Å, 3.3577 Å, 3.3578 Å, 3.3579 Å. 3.358Å, 3.3581Å, 3.3582Å, 3.3583Å, 3.3584Å, 3.3585Å, 3.3586Å, 3.3587Å, 3.3588Å, 3.3589Å, 3.359Å, 3.3591Å, 3.3592Å, 3.3593Å, 3.3594Å, 3.3595Å, 3.3596Å, 3.3597Å, 3.3598Å, 3.3599Å, or 3.360Å.

[0080] According to some embodiments, the first negative electrode active material can have an Hg cumulative pore volume of about 0.01 mL / g to about 0.06 mL / g (e.g., 0.01 mL / g, 0.02 mL / g, 0.03 mL / g, 0.04 mL / g, 0.05 mL / g, or 0.06 mL / g, or for example, about 0.02 mL / g to about 0.06 mL / g, or about 0.03 mL / g to about 0.06 mL / g). Within the above range, a significantly greater negative electrode active material efficiency can be achieved due to the small pores (i.e., voids) in the first negative electrode active material and the appropriate amount of amorphous carbon in the first negative electrode active material. In addition, the internal area of ​​the first negative electrode active material that reacts with the electrolyte is not too large, and a sufficient density is maintained to allow for good impregnation of the electrolyte, thereby ensuring an appropriate lifetime without excessive side reactions. The Hg cumulative pore volume can be a characteristic of the first negative electrode active material prepared by the preparation method described below, to reduce the specific surface area while including small particles of natural graphite.

[0081] According to some embodiments, the first negative electrode active material can have a sphericity (S) of 0.85 or greater, according to Equation 1 below: [Equation 1] Sphericity (S) = 4π × A / B 2 .

[0082] In Equation 1, A is the area of ​​the active material of the first negative electrode, and B is the perimeter of the active material of the first negative electrode.

[0083] In some embodiments, B may be the perimeter of the actual geometry of the first negative electrode active material.

[0084] The sphericity of the active material of the first negative electrode can be a value obtained when a three-dimensional particle is projected onto a two-dimensional plane. Sphericity can be the ratio of the outline of the real particle to the outline of a circle with the same area as the real particle.

[0085] In Equation 1, area A represents the area of ​​a circle having the same perimeter B as the actual perimeter B of the particle obtained from the SEM image of the electrode profile, calculated from the cross-sectional image using a pressure-controlled scanning electron microscope (CP-SEM) and the ImageJ program. In some embodiments, the actual perimeter may refer not only to the perimeter when the particle has a perfectly spherical geometry, but also to the length obtained along the perimeter even when the particle is not perfectly spherical and has non-uniform regions.

[0086] The sphericity of the active material of the first negative electrode can be 0.85, 0.86, 0.87, 0.88, 0.89, 0.90, 0.91, 0.92, 0.93, 0.94, 0.95, 0.96, 0.97, 0.98, 0.99, 1.0, about 0.90 to about 1.0, about 0.90 to about 0.98, or about 0.90 to about 0.95. When the sphericity falls within the above range, the expansion rate during charging and discharging can be suppressed more effectively.

[0087] The first negative electrode active material can have a particle density of about 1.60 g / cc to about 1.80 g / cc. Within this range, the internal pores of the first negative electrode active material and side reactions with the electrolyte can be reduced, thereby improving lifetime characteristics. The particle density can be about 1.60 g / cc, 1.61 g / cc, 1.62 g / cc, 1.63 g / cc, 1.64 g / cc, 1.65 g / cc, 1.66 g / cc, 1.67 g / cc, 1.68 g / cc, 1.69 g / cc, 1.70 g / cc, 1.71 g / cc, 1.72 g / cc, 1.73 g / cc, 1.74 g / cc, 1.75 g / cc, 1.76 g / cc, 1.77 g / cc, 1.78 g / cc, 1.79 g / cc, 1.80 g / cc, or, for example, about 1.70 g / cc to about 1.80 g / cc.

[0088] The active material of the first negative electrode can have a concentration of approximately 0.75 g / cc to approximately 1.20 g / cc (e.g., 0.75 g / cc, 0.76 g / cc, 0.77 g / cc, 0.78 g / cc, 0.79 g / cc, 0.80 g / cc, 0.81 g / cc, 0.82 g / cc, 0.83 g / cc, 0.84 g / cc, 0.85 g / cc, 0.86 g / cc, 0.87 g / cc, 0.88 g / cc, 0.89 g / cc, 0.90 g / cc, 0.91 g / cc, 0.92 g / cc, 0.93 g / cc, 0.94 g / cc, 0.95 g / cc, 0.96 g / cc, 0.97 g / cc, 0.98 g / cc). c. Tap densities of 0.99 g / cc, 1.00 g / cc, 1.01 g / cc, 1.02 g / cc, 1.03 g / cc, 1.04 g / cc, 1.05 g / cc, 1.06 g / cc, 1.07 g / cc, 1.08 g / cc, 1.09 g / cc, 1.10 g / cc, 1.11 g / cc, 1.12 g / cc, 1.13 g / cc, 1.14 g / cc, 1.15 g / cc, 1.16 g / cc, 1.17 g / cc, 1.18 g / cc, 1.19 g / cc, 1.20 g / cc, or for example, about 0.75 g / cc to about 1.0 g / cc or about 0.95 g / cc to about 1.20 g / cc. Within these ranges, the internal pores of the first negative electrode active material and side reactions with the electrolyte can be reduced, and lifetime characteristics can be improved. Tap density can be determined by using a conversion factor of 0.2907 cm⁻¹. 3 The values ​​were obtained by calculating the average of three treatments with a pressure of 108 N applied to a GeoPyc 1360 micromeritics bottle with a chamber diameter of 19.1 mm and a chamber diameter of 19.1 mm.

[0089] The active material of the first negative electrode can have 10m 2 / g or less (e.g., 1m) 2 / g, 1.5m 2 / g、2m 2 / g, 2.5m 2 / g、3m 2 / g, 3.5m 2 / g、4m 2 / g, 4.5m 2 / g、5m 2 / g, 5.5m 2 / g、6m 2 / g, 6.5m 2 / g、7m 2 / g, 7.5m 2 / g、8m 2 / g, 8.5m 2 / g、9m 2 / g, 9.5m 2 / g, 10m 2 / g, approximately 1m 2 / g to approximately 10m 2 The specific surface area ( / g) can be considered. Within this range, the side reactions between the internal pores of the first negative electrode active material and the electrolyte can be reduced, and lifetime characteristics can be improved. Specific surface area can be the BET specific surface area. The BET specific surface area can be measured using a Macsorb HM model-1208 (MOUNTECH).

[0090] The internal porosity of the first negative electrode active material can be about 2% or less (e.g., 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1.0%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, or 2%, or for example, about 1.8% or less, about 1.5% or less, about 1.0% to about 1.5%, or about 1.0% to about 1.3%). Within these ranges, side reactions between the first negative electrode active material and the electrolyte can be suppressed, thereby improving the lifespan of the rechargeable lithium battery. The total pore volume and mesopore volume can be quantitatively measured using a Barrett-Joyner-Halenda (BJH) analytical instrument.

[0091] The first negative electrode active material includes: natural graphite, comprising secondary particles in which primary particles are aggregated; and a coating layer surrounding the secondary particles and comprising amorphous carbon.

[0092] Natural graphite can be in the form of flakes (i.e., having needle-like or scaly geometry).

[0093] Primary particles can have a size from about 10 μm to about 200 μm (e.g., about 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, 55 μm, 60 μm, 65 μm, 70 μm, 75 μm, 80 μm, 85 μm, 90 μm, 95 μm, 100 μm, 105 μm, 110 μm, 115 μm, 120 μm, etc.). The major axis length can be 125 μm, 130 μm, 135 μm, 140 μm, 145 μm, 150 μm, 155 μm, 160 μm, 165 μm, 170 μm, 175 μm, 180 μm, 185 μm, 190 μm, 195 μm, or 200 μm, or for example, about 10 μm to about 100 μm, about 30 μm to about 60 μm, or about 20 μm to about 50 μm. Within the above ranges, aggregation into secondary particles can be readily achieved, and the ratios of the secondary particles can be readily realized as described below.

[0094] "Major axis length" refers to the length of the longest axis between the facing edges when primary particles are formed in the geometry of a plate.

[0095] In some embodiments, the primary particles may be formed in the geometry of a plate, but the invention is not limited thereto.

[0096] The average particle size D50 of the secondary particles can be about 30 μm or less. Within this range, the secondary particles can easily achieve the ratios described below. The average particle size D50 of the secondary particles can be about 5 μm to about 10 μm (e.g., about 5 μm, 6 μm, 7 μm, 8 μm, 9 μm or 10 μm, or for example, about 6 μm to about 8 μm). Within this range, the secondary particles can easily achieve the above-mentioned orientation and sphericity.

[0097] The secondary particles can be spherical, but the invention is not limited thereto.

[0098] In some embodiments, the ratio of the major axis length of the primary particles to the average particle size D50 of the secondary particles can be greater than 2 and 10 or less. Within this range, the resistance of the first negative electrode active material does not increase, and the boost charging performance does not decrease. This ratio can be 2.1, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9, 9.5, 10, 3 to 6, 4 to 6, or 5 to 6. Within this range, the secondary particles can easily achieve the above-mentioned orientation and sphericity.

[0099] Amorphous carbon can be incorporated into a coating layer surrounding the surface of the secondary particles. Amorphous carbon can reduce the internal porosity of the first negative electrode active material and suppress side reactions between the first negative electrode active material and the electrolyte, thereby improving charge and discharge rate characteristics.

[0100] The thickness of the coating layer containing amorphous carbon can be from 5 to 50 nm (e.g., 5 nm, 6 nm, 7 nm, 8 nm, 9 nm, 10 nm, 11 nm, 12 nm, 13 nm, 14 nm, 15 nm, 16 nm, 17 nm, 18 nm, 19 nm, 20 nm, 21 nm, 22 nm, 23 nm, 24 nm, 25 nm, 26 nm, 27 nm, 28 nm, 29 nm, 30 nm, 31 nm, 32 nm, 33 nm, 34 nm, 35 nm, 36 nm, 37 nm, 38 nm, 39 nm, 40 nm, 41 nm, 42 nm, 43 nm, 44 nm, 45 nm, 46 nm, 47 nm, 48 nm, 49 nm, 50 nm, about 10 nm to about 50 nm, or about 20 nm to about 50 nm). Within this range, side reactions with the electrolyte can be suppressed, and charge and discharge rate characteristics can be improved.

[0101] Amorphous carbon can be one or more of soft carbon, hard carbon, mesophase pitch carbides, and calcined coke.

[0102] Amorphous carbon can even exist separately on the surface of primary particles.

[0103] The natural graphite and amorphous carbon in the first negative electrode active material can be included in a weight ratio of about 90:10 to about 75:25 (e.g., about 90:10 to about 80:20, about 90:10 to about 85:15, or about 90:10 to about 88:12) relative to 100 parts by weight of the total natural graphite and amorphous carbon. Within the above range, side reactions with the electrolyte can be suppressed, and charge and discharge rate characteristics can be improved.

[0104] Primary particles with the aforementioned long axis length are obtained by grinding natural graphite raw materials with an average particle size D50 of about 120 μm or greater. In some embodiments, the natural graphite raw materials can be ground by applying an air jet milling method. Air jet milling may include grinding at 5 to 20 kg / cm² at room temperature. 2 Grinding natural graphite raw materials under certain conditions.

[0105] Primary particles are aggregated into secondary particles using spheroidizing equipment.

[0106] Agglomeration is a process to achieve a sphericity of 0.85 or greater, and can be achieved using a high-intensity mixer equipped with a high-speed rotating rotor and stator. In the spheroidization process, the average particle size D50 of the secondary particles can be adjusted by changing the pressure or shear rate.

[0107] (3) Mix the prepared secondary particles with the amorphous carbon precursor.

[0108] There are no particular restrictions on amorphous carbon precursors, as long as they are materials that form carbides. Amorphous carbon precursors may include one or more of the following: phenolic resins, furan resins, epoxy resins, polyacrylonitrile resins, polyamide resins, polyimide resins, polyamide-imide resins, synthetic bitumen, petroleum bitumen, coal tar, and coal tar.

[0109] During mixing, natural graphite and amorphous carbon in the final product (i.e., the first negative electrode active material) can be added in the weight ratio described above.

[0110] (4) The first negative electrode active material is obtained by calcination and heat treatment of the mixture obtained by mixing.

[0111] The heat treatment can be performed at 2500°C or higher (e.g., about 2500°C to about 3500°C, for example, about 2500°C to about 3000°C). Within the above range, the first negative electrode active material, including secondary particles that meet the above ratios, can easily achieve the above orientation, d002, and sphericity.

[0112] The heat treatment can be maintained for about 1 hour to about 5 hours, for example, about 1 hour to about 4 hours, about 1 hour to about 3 hours, or about 2 hours to about 3 hours.

[0113] Figure 1 This is a schematic diagram of the first negative electrode active material according to some embodiments of the present disclosure.

[0114] Reference Figure 1 The first negative electrode active material includes: natural graphite, including secondary particles 3 in which a plurality of primary particles 1 are aggregated; amorphous carbon 5, present on the surface of the primary particles; and a coating layer 7, surrounding the secondary particles 3 and including the amorphous carbon 5. (See reference...) Figure 1 Since the secondary particles 3 are aggregated by shaping the spherical primary particles 1 into a curved geometry, natural graphite has a smaller size and a denser internal structure, which minimizes internal pores, reduces side reactions with electrolytes, and improves cycle life.

[0115] Second negative electrode active material The second negative electrode active material can be graphite. In some embodiments, the second negative electrode active material can be one or more of natural graphite and artificial graphite. In some embodiments, the second negative electrode active material is preferably artificial graphite.

[0116] Artificial graphite can have an average particle size D50 of about 10 μm to about 20 μm (e.g., about 13 μm to about 18 μm or about 15 μm to about 20 μm). Within this range, since the specific surface area does not increase significantly, side reactions with the electrolyte do not increase, and boost charging performance does not decrease.

[0117] Artificial graphite can have a maximum particle size of about 30 μm to about 40 μm.

[0118] In some embodiments, the artificial graphite has a particle density lower than that of the first negative electrode active material, for example, having a particle density of about 1.1 g / cc to about 1.6 g / cc or about 1.1 g / cc to about 1.5 g / cc.

[0119] In some embodiments, the artificial graphite may have a tap density that is smaller than that of the first negative electrode active material, for example, a tap density of about 0.5 g / cc to about 1.0 g / cc or about 0.5 g / cc to about 0.9 g / cc.

[0120] In some embodiments, artificial graphite may have a thickness of approximately 10 μm. 2 / g or less (e.g., about 1m) 2 / g to approximately 10m 2 The specific surface area is ( / g). Specific surface area can be the BET specific surface area.

[0121] In some embodiments, the artificial graphite may have an orientation degree of about 90 or greater (e.g., about 90 to about 100). The orientation degree can be measured by the methods described above.

[0122] Artificial graphite can have, but is not limited to, spherical geometry.

[0123] Artificial graphite may include one or more of single particles, primary particles, secondary particles in which primary particles are aggregated, and tertiary particles in which secondary particles are aggregated.

[0124] In some embodiments, the secondary particles, on which the primary particles are aggregated, may further include a coating layer containing amorphous carbon on their surface.

[0125] Third negative electrode active material The third negative electrode active material includes silicon nanoparticles and an amorphous carbon coating layer disposed on the surface of the silicon nanoparticles.

[0126] In some embodiments, the third negative electrode active material is spherical, thus allowing for good dispersion throughout the negative electrode plate. This reduces the expansion rate of the negative electrode plate during charging and discharging. Furthermore, when the third negative electrode active material is mixed with crystalline carbon (i.e., the first negative electrode active material), the spherical third negative electrode active material can more easily insert into the crystalline carbon, thus facilitating dispersion throughout the negative electrode.

[0127] The sphericity (S) of the third negative electrode active material, as expressed by Equation 1, can be from about 0.9 to about 1.0. Within the above range, the expansion rate of the negative electrode plate during charging and discharging can be easily reduced.

[0128] According to some embodiments, the sphericity of the third negative electrode active material can be from about 0.92 to about 0.98 or from about 0.92 to about 0.95. When the sphericity of the third negative electrode active material falls within this range, the expansion rate of the negative electrode plate during charging and discharging can be suppressed more effectively.

[0129] The third negative electrode active material can have pores, and these pores can include mesopores. Mesopores can refer to pores with a diameter of approximately 2 nm to approximately 50 nm. Because the third negative electrode active material has mesopores, the effect of the negative electrode plate can be significant.

[0130] When the third negative electrode active material with spherical shape and central hole is mixed with the first negative electrode active material and the second negative electrode active material, it is easy to simultaneously provide long cycle life, high energy density and boost charging effect.

[0131] In some embodiments, the third negative electrode active material may also include macropores with a pore size greater than about 50 nm. When the pore size exceeds 50 nm, the pore is classified as a macropore, and there is no limit to the maximum value of the macropore, but the pore size can be up to 500 nm. It is desirable to include such macropores at 1 volume% or less (such as even about 0 volume%) relative to the total pore volume, indicating that macropores may be substantially absent in the third negative electrode active material.

[0132] In some embodiments, the third negative electrode active material may further include micropores with a pore size of about 0 nm to about 2 nm. Based on the volume percentage of total pores, the micropores in the third negative electrode active material may correspond to pores other than mesopores. Furthermore, based on the volume percentage of total pores, the micropores in the third negative electrode active material may correspond to pores other than mesopores and macropores.

[0133] As used herein, “aperture” refers to the diameter of the hole when its cross-section is circular, or the length of the longest major axis of the hole’s cross-section when its cross-section is not circular.

[0134] In some embodiments, the ratio of the mesopore volume of the third negative electrode active material to the total pore volume of the third negative electrode active material ([mesopore volume / total pore volume]×100) can be from about 30% to about 70%. Within this range, long cycle life, high energy density, and boost charging performance can be improved. This ratio can be from about 30% to about 68%.

[0135] The total pore volume can be the total volume including the mesopores and the pores that can be formed in the third negative electrode active material, regardless of the pore size. In some embodiments, the total pore volume can be 0.001 cm³. 3 / g to approximately 0.05cm 3 / g, approximately 0.001cm 3 / g to approximately 0.01cm 3 / g or approximately 0.005cm 3 / g to approximately 0.05cm 3 / g.

[0136] Each of the total pore volume and mesopore volume can be quantitatively measured using the Barrett-Joyner-Halenda (BJH) analytical apparatus.

[0137] The third negative electrode active material can have a range value of about 1.1 to about 1.6, expressed by Equation 2 below: [Equation 2] Span = (D90 - D10) / D50.

[0138] In Equation 2, D10 is the particle size of the third negative electrode active material with a cumulative volume of about 10 vol% in the particle size distribution, D50 is the particle size of the third negative electrode active material with a cumulative volume of about 50 vol% in the particle size distribution, and D90 is the particle size of the third negative electrode active material with a cumulative volume of about 90 vol% in the particle size distribution.

[0139] The detailed methods for measuring D10, D50, and D90 are the same as those described above.

[0140] In some embodiments, the span value may be about 1.1 to about 1.55 or about 1.1 to about 1.5.

[0141] When the range of the third negative electrode active material falls within the above range, it means that the third negative electrode active material substantially does not contain fine particles. Since the third negative electrode active material contains almost no fine particles with a size of about 1 μm or smaller and is typically amorphous, it can exhibit a small surface area, thereby reducing side reactions with the electrolyte and improving the cycle life of rechargeable lithium batteries.

[0142] In some embodiments, the third negative electrode active material has a small specific surface area, and the specific surface area may also be about 0.5 m². 2 / g to approximately 2m 2 / g, approximately 0.8m 2 / g to approximately 2m 2 / g, or approximately 0.8m 2 / g to approximately 1.5m 2 / g. Specific surface area can be less than approximately 3m². 2 The value of / g, 3m 2 / g is the specific surface area of ​​a conventional silicon-carbon composite used as the negative electrode active material. Specific surface area can be the BET specific surface area.

[0143] The particle size of silicon nanoparticles can range from about 10 nm to about 1,000 nm, and in some embodiments, it can be from about 10 nm to about 200 nm, or from about 20 nm to about 150 nm. When the particle size of silicon nanoparticles falls within the above range, excessive volume expansion during charging and discharging can be suppressed, and interruption of the conductive path caused by particle fragmentation during charging and discharging can be prevented.

[0144] Silicon nanoparticles can aggregate into secondary silicon particles. According to some embodiments, the average particle size D50 of the secondary silicon particles can be from about 1 μm to about 15 μm. The average particle size D50 of the secondary silicon particles can be from about 1 μm to about 10 μm (e.g., from about 6 μm to about 8 μm).

[0145] In the amorphous carbon coating, the amorphous carbon can be soft carbon or hard carbon, mesophase pitch carbide, calcined coke, or a combination thereof.

[0146] The thickness of the amorphous carbon coating can be from about 1 nm to about 2 μm, from about 1 nm to about 500 nm, from about 10 nm to about 300 nm, or from about 20 nm to about 200 nm. When the thickness of the amorphous carbon coating is within the above range, silicon volume expansion during charging and discharging can be well suppressed.

[0147] In the third negative electrode active material, the amount of silicon nanoparticles can be approximately 55 wt% to approximately 64 wt% or approximately 58 wt% to approximately 62 wt% relative to 100 wt% of the total amount of the third negative electrode active material. The amount of amorphous carbon coating layer can be approximately 36 wt% to approximately 45 wt% or approximately 38 wt% to approximately 42 wt% relative to 100 wt% of the total amount of the third negative electrode active material. Within these ranges, the capacity of the negative electrode plate can be improved, and particle stability can be increased.

[0148] The third negative electrode active material may also include a polymer layer located on (or around) the amorphous carbon coating.

[0149] The polymer layer may include a copolymer of polyvinyl alcohol and polyacrylic acid. The copolymer may be a cross-linked copolymer of polyvinyl alcohol and polyacrylic acid. When the third negative electrode active material also includes a polymer layer, the volume expansion of the third negative electrode active material during charging and discharging can be more effectively suppressed.

[0150] Since the polymer layer comprises polyvinyl alcohol and polyacrylic acid, it is possible to prevent the electrolyte from penetrating into the third negative electrode active material during charging and discharging, specifically into the empty spaces (e.g., pores) of the third negative electrode active material, thereby more effectively suppressing the side reactions between the third negative electrode active material and the electrolyte.

[0151] Polyvinyl alcohol and polyacrylic acid are water-based polymers and environmentally friendly polymers.

[0152] In some embodiments, the polymer layer may include a copolymer of polyvinyl alcohol and polyacrylic acid, and polyvinyl alcohol and polyacrylic acid may be included as crosslinking polymers or crosslinking copolymers. The polymer of the polymer layer may be a crosslinked polymer of polyvinyl alcohol and polyacrylic acid. When polyvinyl alcohol and polyacrylic acid are crosslinked in the polymer layer as crosslinking polymers, the crosslinked polymer is insoluble in solvents (particularly water) used during the manufacture of the negative electrode active material layer. These properties of the crosslinked polymer allow the polymer layer to be retained.

[0153] In the third negative electrode active material, when the entire silicon nanoparticle and amorphous carbon coating are referred to as a silicon-carbon composite, the amount of the polymer layer relative to 100 parts by weight of the silicon-carbon composite can be from about 0.01 parts by weight to about 3 parts by weight or from about 1.2 parts by weight to about 2.1 parts by weight. When the amount of the polymer layer falls within the above range, better effects caused by the formation of the polymer layer can be achieved.

[0154] In the polymer layer, the mixing ratio of polyvinyl alcohol and polyacrylic acid can be from about 3:97 to about 40:60, from about 6:94 to about 40:60, or from about 6:94 to about 20:80 by weight. When the mixing ratio of polyvinyl alcohol and polyacrylic acid can be included in the above ranges, and the amount of polyacrylic acid can be greater than the amount of polyvinyl alcohol, the life characteristics of the rechargeable lithium battery can be further improved.

[0155] In some embodiments, the ratio of functional groups in polyvinyl alcohol and polyacrylic acid included in the polymer layer can also be appropriately adjusted. More specifically, the molar ratio of OH groups in polyvinyl alcohol to COOH groups in polyacrylic acid can be from about 5:95 to about 50:50 or from about 10:90 to about 30:70. When the molar ratio of functional groups meets the above ranges, the effects achieved by forming the polymer layer can be further improved, and the lifespan characteristics can be further improved.

[0156] According to some embodiments, the third negative electrode active material can be prepared by the following process.

[0157] Nanoscale silicon primary particles are prepared by grinding micron-sized silicon particles. The grinding process can be carried out using conventional processes such as ball milling. A dispersant can be used in the grinding process. Stearic acid, boron nitride (BN), MgS, polyvinylpyrrolidone (PVP), or combinations thereof can be used as dispersants. The amount of dispersant used is sufficient to carry out the silicon particle grinding process, but the invention is not limited thereto.

[0158] The particle size of primary silicon particles can be from about 1 nm to about 1000 nm, from about 10 nm to about 200 nm, or from about 20 nm to about 150 nm.

[0159] Drying is performed on the mixture obtained after the grinding process. The drying process can be carried out using spray drying. Spray drying can form a dried product containing spherical particles with a more uniform particle size, or it can form secondary particles in which primary particles aggregate. When the dried product is spherical particles with a uniform particle size, the subsequently formed amorphous carbon layer can be formed more uniformly across the entire surface of the dried product.

[0160] The dried product and the amorphous carbon precursor are mixed.

[0161] As a precursor for amorphous carbon, petroleum coke, coal coke, petroleum pitch, coal pitch, raw coke, or combinations thereof can be used.

[0162] The resulting mixture can then be subjected to compression molding.

[0163] Compression molding can be performed to reduce the pores in the active material of the third negative electrode, thereby effectively suppressing side reactions.

[0164] Compression molding can be performed at pressures sufficient to maintain the spherical geometry of the resulting product (specifically, the negative electrode active material as the final product). These pressures are approximately 0 MPa to 30 MPa, 0 MPa to 20 MPa, or 5 MPa to 20 MPa.

[0165] Compression molding can be performed using cold isostatic pressing (CIP). When compression molding is performed within the above pressure range, the spherical geometry of the third negative electrode active material can be maintained, and pores can be appropriately reduced without producing fine particles.

[0166] The resulting compression-molded product is then carbonized. The carbonization process can be carried out at approximately 600°C to approximately 1,000°C. During the carbonization process, the dispersant can be removed. Alternatively, the carbonization process can be carried out in an N2 atmosphere, a helium atmosphere, or a combination thereof. Through the carbonization process, the amorphous carbon precursor can be converted into amorphous carbon to surround the surface of the compression-molded product, thereby producing an amorphous carbon coating layer.

[0167] When the carbonization process is performed within the aforementioned temperature range, excessive growth of silicon (Si) particles and the formation of SiC can be suppressed, and the conductivity of amorphous carbon can be improved. Furthermore, some of the amorphous carbon can be introduced into the pores formed between the primary particles and can exist on the surface of the primary particles, thus surrounding that surface. When the atmosphere of the carbonization process meets the above conditions, silicon oxidation and SiC formation can be suppressed, and amorphous carbon can be effectively formed, thereby reducing the resistance of the active material of the third negative electrode.

[0168] A vapor-phase coating process using dried products and amorphous carbon precursor gases can be used instead of a process involving mixing dried products and amorphous carbon precursors. An amorphous carbon coating layer can be formed on the product surface without a separate carbonization process. Therefore, a compression process can be performed after the vapor-phase coating process. The conditions for the compression process are as described above.

[0169] When the negative electrode active material layer according to some embodiments further includes a polymer layer, the prepared negative electrode active material (silicon-carbon composite) and polymer solution are mixed, dried, and then heat-treated.

[0170] The polymer solution can be prepared by mixing polyvinyl alcohol and polyacrylic acid in a solvent, and the solvent can be water, ethanol, or a combination thereof.

[0171] The mixing ratio of silicon-carbon composite and polymer solution can be appropriately adjusted to achieve the above-mentioned polymer amount and mixing ratio of polyvinyl alcohol and polyacrylic acid in the prepared third negative electrode active material.

[0172] According to the heat treatment process, polyvinyl alcohol and polyacrylic acid crosslink through the condensation between the OH groups of polyvinyl alcohol and the COOH groups of polyacrylic acid, thereby forming a crosslinked polymer.

[0173] The heat treatment process can be carried out at approximately 150°C to approximately 200°C. When the heat treatment process is carried out within the above temperature range, the condensation reaction and crosslinking reaction can occur smoothly to form a crosslinked polymer.

[0174] Subsequently, the obtained heat-treated product is subjected to a classification process. The classification process can be carried out using a sieve such that the span value (defined by Equation 2) of the third negative electrode active material will be 1.1 to 1.6. The classification process can be carried out to obtain an active material having a particle size such that the span value of the active material obtained from D10, D50, and D90 is about 1.1 to about 1.6.

[0175] The negative electrode plate may further include a negative electrode active material (fourth negative electrode active material) different from the above-described first negative electrode active material, second negative electrode active material, and third negative electrode active material.

[0176] The fourth negative electrode active material may further include a material capable of reversibly inserting / extracting lithium ions, lithium metal, a lithium-metal alloy, a material capable of doping and dedoping lithium, or a transition metal oxide.

[0177] The material capable of reversibly inserting / extracting lithium ions may be a carbon-based negative electrode active material (e.g., crystalline carbon, amorphous carbon, or a combination thereof). The crystalline carbon may be graphite having an amorphous, plate-like, flaky, or spherical geometry, and the graphite may be fibrous natural graphite or artificial graphite. The amorphous carbon may be soft carbon, hard carbon, mesophase pitch carbide, or calcined coke.

[0178] The lithium-metal alloy may include lithium and a metal selected from Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Si, Sb, Pb, In, Zn, Ba, Ra, Ge, Al, and Sn.

[0179] A silicon-based negative electrode active material or a Sn-based negative electrode active material may be used as a material capable of doping and dedoping lithium. The silicon-based negative electrode active material may be Si, a silicon-carbon composite, SiO x (0 < x ≤ 2), a Si-Q alloy (where Q is selected from alkali metals, alkaline earth metals, Group 13 elements, Group 14 elements [excluding Si], Group 15 elements, Group 16 elements, transition metals, rare earth elements, and combinations thereof), or a combination thereof. The Sn-based negative electrode active material may be Sn, SnO2, a Sn-based alloy, or a combination thereof.

[0180] The silicon-carbon composite may be a composite of silicon and amorphous carbon. According to some embodiments, the silicon-carbon composite may be silicon particles whose surfaces are coated with amorphous carbon. The silicon-carbon composite may include secondary particles (cores) in which silicon primary particles are aggregated and an amorphous carbon coating layer (shells) provided on the surfaces of the secondary particles. The amorphous carbon may be located between the silicon primary particles such that the silicon primary particles are coated with amorphous carbon. The secondary particles may be dispersed in an amorphous carbon matrix.

[0181] Silicon-carbon composites may also include crystalline carbon. A silicon-carbon composite may include a core comprising crystalline carbon and silicon particles, and an amorphous carbon coating layer disposed on the surface of the core of the silicon-carbon composite.

[0182] Silicon-based or Sn-based negative electrode active materials can be mixed with carbon-based negative electrode active materials.

[0183] adhesive The negative electrode plate used in rechargeable lithium batteries may also include an adhesive.

[0184] The binder may be included in the negative electrode plate at a rate of about 0.5 wt% to about 5 wt%.

[0185] The binder can effectively adhere the particles of the negative electrode active material to each other and to the current collector. Non-aqueous binders, aqueous binders, dry binders, or combinations thereof can be used.

[0186] Non-aqueous adhesives may be polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, ethylene-propylene copolymer, polystyrene, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, polyamide-imide, polyimide, or combinations thereof.

[0187] Waterborne adhesives may be selected from styrene-butadiene rubber, (meth)acrylated styrene-butadiene rubber, (meth)acrylonitrile-butadiene rubber, (meth)acrylic rubber, butyl rubber, fluorinated elastomers, polyethylene oxide, polyvinylpyrrolidone, polyepoxychloropropane, polyphosphazene, poly(meth)acrylonitrile, ethylene propylene diene copolymer, polyvinylpyridine, chlorosulfonated polyethylene, latex, polyester resin, (meth)acrylic resin, phenolic resin, epoxy resin, polyvinyl alcohol, and combinations thereof.

[0188] When using an aqueous binder as the negative electrode binder, it may also include a cellulose compound that imparts viscosity. As a cellulose compound, one or more of carboxymethyl cellulose, hydroxypropyl methyl cellulose, methyl cellulose, and their alkali metal salts may be used. Na, K, or Li may be used as the alkali metal.

[0189] Dry adhesives are fibrous polymeric materials and can be, for example, polytetrafluoroethylene, polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer, polyethylene oxide, or combinations thereof.

[0190] conductive materials The negative electrode active material layer may also include conductive materials.

[0191] The negative electrode plate may contain conductive material in a proportion of about 0 wt% to about 5 wt%.

[0192] Conductive materials are used to impart conductivity to the electrodes, and any electronically conductive material that will not cause chemical changes in the resulting battery cell can be used. In some embodiments, the conductive material may be: carbon-based materials, such as natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fibers, carbon nanofibers, or carbon nanotubes; metal powder or metal fiber-based metallic materials; conductive polymers, such as polyphenylene derivatives; or mixtures thereof.

[0193] A negative electrode plate for a rechargeable lithium battery according to some embodiments includes a negative electrode active material and a conductive material, wherein the negative electrode active material includes a mixture of a first negative electrode active material, a second negative electrode active material, and a third negative electrode active material. The first negative electrode active material may include natural graphite, which includes secondary particles in which primary particles are aggregated and an amorphous carbon coating layer surrounding the secondary particles. The first negative electrode active material may have an orientation degree of about 90 or less and a d002 of about 3.356 Å to about 3.360 Å. The second negative electrode active material includes graphite. The third negative electrode active material may include silicon nanoparticles and an amorphous carbon coating layer disposed on the surface of the silicon nanoparticles and may have a sphericity of about 0.9 to about 1.0. The conductive material may include carbon nanotubes.

[0194] The negative electrode plate for rechargeable lithium batteries may include the above-mentioned mixture as the negative electrode active material and carbon nanotubes as the conductive material, thereby providing silicon-based active materials with high capacity retention, high energy density, boost charging effect, improved fast charging cycle life and low expansion rate (swelling).

[0195] The negative electrode plate can include carbon nanotubes as a conductive material, thereby reducing fast charging time, extending the cycle life of silicon-based active materials, and reducing the expansion of silicon-based active materials, thus increasing the energy density of silicon-based active materials.

[0196] When carbon nanotubes are included as the conductive material, the negative electrode plate may include a mixture of negative electrode active materials, thereby enhancing the effect of reducing fast charging time and extending the cycle life of silicon-based active materials.

[0197] Carbon nanotubes, as conductive materials, possess a one-dimensional structure and form a conductive network. This network maintains the connection between active materials during battery charging and discharging, thus suppressing battery degradation. Furthermore, carbon nanotubes can reduce fast-charging time, extend the cycle life of silicon-based active materials, and reduce the expansion of the second negative electrode active material, thereby increasing the energy density of rechargeable lithium-ion batteries.

[0198] Carbon nanotubes can have an average diameter of about 0.5 nm to about 3 nm (e.g., about 1 nm to about 5 nm); an average length of about 5 μm or less (e.g., about 1 μm to about 2 μm); and a maximum length of about 20 μm or less. Within these ranges, it is possible to achieve reduced fast charging time, extended cycle life of silicon-based active materials, and reduced expansion of silicon-based active materials.

[0199] "Average diameter" refers to the average diameter of carbon nanotubes. "Diameter of carbon nanotube" refers to the diameter of a carbon nanotube with a circular cross-section, and also to the maximum length of the cross-section when the carbon nanotube cross-section is, for example, amorphous or non-circular.

[0200] Carbon nanotubes can have a diameter of approximately 30,000 m. 2 / g to approximately 100,000m 2 / g (e.g., approximately 50,000 mcg) 2 / g to approximately 100,000m 2 The specific surface area (SSA) is 1 / g. Within the above range, a negative electrode with high conductivity can be manufactured by reducing the powder resistance of the slurry for the negative electrode, which includes a mixture of negative electrode active materials.

[0201] SSA is used as a standard to determine whether a negative electrode slurry prepared using a conductive material dispersion can provide low powder resistance, the conductive material dispersion being prepared using carbon nanotubes having a specific surface area as described below. While SSA measurement can be straightforward for carbon nanotubes, measuring the SSA of the dispersed carbon nanotubes within a conductive material dispersion containing carbon nanotubes is challenging.

[0202] The SSA of carbon nanotube dispersions can be calculated using the Malvern particle size analyzer.

[0203] Carbon nanotubes can be one or a mixture of single-walled carbon nanotubes and multi-walled carbon nanotubes. Single-walled carbon nanotubes are preferred.

[0204] Carbon nanotubes can have a diameter of approximately 240 m. 2 / g to approximately 280m 2 The specific surface area per g. Within the above range, the conductivity of the slurry containing the negative electrode active material can be increased.

[0205] In some embodiments, carbon nanotubes may be included in an amount of about 95 wt% or more (e.g., about 95 wt% to about 100 wt%) of the conductive material.

[0206] Relative to 100 parts by weight of the negative electrode plate, a conductive material (e.g., carbon nanotubes) may be included in approximately 0.01 parts by weight to approximately 5 parts by weight (e.g., approximately 0.01 parts by weight to approximately 0.2 parts by weight, or approximately 0.03 parts by weight to approximately 0.05 parts by weight). Within these ranges, it is possible to achieve reduced fast charging time, extended cycle life of silicon-based active materials, and reduced expansion of silicon-based active materials.

[0207] Conductive material can be included in the negative electrode plate at a concentration of about 0.01 wt% to about 5 wt% (e.g., about 0.01 wt% to about 0.2 wt%). Within this range, increased energy density and improved boost charging characteristics can be achieved, as well as extended cycle life and reduced expansion of silicon-based active materials. Conductive material (e.g., carbon nanotubes) can be included in the negative electrode plate at a concentration of about 0.03 wt% to about 0.05 wt%. Since the amount of active material is not reduced within this range, the battery capacity does not need to be reduced.

[0208] The negative electrode current collector can also be stacked on at least one surface of the negative electrode plate.

[0209] As a negative electrode current collector, any one of copper foil, nickel foil, stainless steel foil, titanium foil, nickel foam, copper foam, polymer substrate coated with conductive metal, and combinations thereof can be used.

[0210] Some embodiments provide a rechargeable lithium battery including a negative electrode plate for a rechargeable lithium battery.

[0211] A rechargeable lithium battery may include a negative electrode plate and a positive electrode for use in a rechargeable lithium battery. The negative electrode plate may be substantially the same as described above.

[0212] positive electrode The positive electrode for a rechargeable lithium-ion battery may include a positive electrode current collector and a layer of positive electrode active material on the positive electrode current collector. The positive electrode active material layer may include positive electrode active material and may also include a binder and / or a conductive material. The positive electrode may also include additives that can be used as a sacrificial positive electrode.

[0213] Positive electrode active material The positive electrode active material may include compounds capable of intercalating and deintercalating lithium (lithium-intercalating compounds). Specifically, at least one of the composite oxides of lithium and metals selected from cobalt, manganese, nickel, and combinations thereof may be used.

[0214] The composite oxide can be a lithium transition metal composite oxide. Specific examples of composite oxides may include lithium nickel oxides, lithium cobalt oxides, lithium manganese oxides, lithium iron phosphate compounds, cobalt-free lithium nickel manganese oxides, or combinations thereof.

[0215] The following compounds, represented by any of the following chemical formulas, can be used: Li a A 1-b X b O 2-c D c (0.90≤a≤1.8, 0≤b≤0.5, and 0≤c≤0.05); Li a Mn 2-b X b O 4-c D c (0.90≤a≤1.8, 0≤b≤0.5, and 0≤c≤0.05); Li a Ni 1-b-c Co b X c O 2-α D α (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.5, and 0<α<2); Li a Ni 1-b- c Mn b X c O 2-α D α (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.5, and 0<α<2); Li a Ni b Co c L 1 d G e O2 (0.90≤a≤1.8, 0≤b≤0.9, 0≤c≤0.5, 0≤d≤0.5, and 0≤e≤0.1); Li a NiG b O2 (0.90≤a≤1.8 and 0.001≤b≤0.1); Li a CoG b O2 (0.90≤a≤1.8 and 0.001≤b≤0.1); Li a Mn 1-b G b O2 (0.90≤a≤1.8 and 0.001≤b≤0.1); Li a Mn2G b O4 (0.90≤a≤1.8 and 0.001≤b≤0.1); Li a Mn 1-g G g PO4 (0.90≤a≤1.8 and 0≤g≤0.5); Li (3-f) Fe2(PO4)3 (0≤f≤2); and Li aFePO4 (0.90≤a≤1.8).

[0216] In the above chemical formulas, A is Ni, Co, Mn, or a combination thereof; X is Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, rare earth elements, or a combination thereof; D is O, F, S, P, or a combination thereof; G is Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V, or a combination thereof; and L 1 It is Mn, Al, or a combination thereof.

[0217] The positive electrode active material can be, for example, a high-nickel positive electrode active material, based on 100 mol% of metals other than lithium in a lithium transition metal complex oxide. The high-nickel positive electrode active material has a nickel content greater than or equal to about 80 mol%, greater than or equal to about 85 mol%, greater than or equal to about 90 mol%, greater than or equal to about 91 mol%, or greater than or equal to about 94 mol% and less than or equal to about 99 mol%. High-nickel positive electrode active materials can achieve high capacity and can be applied to high-capacity, high-density rechargeable lithium batteries.

[0218] Based on a 100wt% positive electrode active material layer, the amount of positive electrode active material can be from about 90wt% to about 99.5wt%. Based on the 100wt% positive electrode active material layer, the amounts of binder and conductive material can be from about 0.5wt% to about 5wt%, respectively.

[0219] The binder is used to ensure good adhesion between the positive electrode active material particles and also to ensure good adhesion of the positive electrode active material to the current collector. As a non-limiting example, examples of binders may include polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, polymers containing ethylene oxide, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene-butadiene rubber, (meth)acrylated styrene-butadiene rubber, epoxy resin, (meth)acrylate resin, polyester resin, and nylon.

[0220] Conductive materials can be used to impart conductivity (e.g., electrical conductivity) to electrodes. Any material that does not cause chemical changes (e.g., does not cause undesirable chemical changes in rechargeable lithium batteries) and conducts electrons can be used in batteries. Examples of conductive materials can include: carbon-based materials such as natural graphite, synthetic graphite, carbon black, acetylene black, Ketjen black, carbon fibers, carbon nanofibers, and carbon nanotubes; metallic materials containing copper, nickel, aluminum, or silver, in the form of metal powders or metal fibers; conductive polymers such as polyphenylene derivatives; or mixtures thereof.

[0221] Al can be used as a current collector, but current collectors are not limited to this.

[0222] Rechargeable lithium batteries may also include an electrolyte.

[0223] electrolyte Electrolytes used in rechargeable lithium batteries may include non-aqueous organic solvents and lithium salts.

[0224] Non-aqueous organic solvents can be used as media for transporting ions that participate in the electrochemical reactions of a battery.

[0225] Non-aqueous organic solvents can be carbonate solvents, ester solvents, ether solvents, ketone solvents, alcohol solvents, aprotic solvents, or combinations thereof.

[0226] Carbonate solvents can include dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), methyl ethyl carbonate (MEC), ethylene carbonate (EC), propylene carbonate (PC), and butyl carbonate (BC).

[0227] Ester solvents may include methyl acetate, ethyl acetate, n-propyl acetate, dimethyl acetate, methyl propionate, ethyl propionate, decanoic acid lactone, mevalonate lactone, valonate lactone, and caprolactone.

[0228] Ether solvents may include dibutyl ether, tetraethylene glycol dimethyl ether, diethylene glycol dimethyl ether, dimethoxyethane, 2-methyltetrahydrofuran, 2,5-dimethyltetrahydrofuran, and tetrahydrofuran. Ketone solvents may include cyclohexanone. Alcohol solvents may include ethanol and / or isopropanol. Aprotic solvents may include: nitriles, such as R-CN (wherein R is a C2 to C20 straight-chain, branched, or cyclic hydrocarbon group, and may include double bonds, aromatic rings, or ether bonds); amides, such as dimethylformamide; dioxolane, such as 1,3-dioxolane or 1,4-dioxolane; or sulfolane.

[0229] Non-aqueous organic solvents can be used alone or in combination of two or more non-aqueous organic solvents.

[0230] In addition, when using carbonate solvents, cyclic carbonates and chain carbonates can be mixed, and cyclic carbonates and chain carbonates can be mixed in a volume ratio of about 1:1 to about 1:9.

[0231] Lithium salts dissolved in organic solvents supply lithium ions in batteries, enabling basic operation of rechargeable lithium batteries and improving lithium ion transport between the positive and negative electrodes. Examples of lithium salts include those selected from LiPF6, LiBF4, LiSbF6, LiAsF6, LiClO4, LiAlO2, LiAlCl4, LiPO2F2, LiCl, LiI, LiN(SO3C2F5)2, Li(FSO2)2N (lithium bis(fluorosulfonyl)imide, LiFSI), LiC4F9SO3, and LiN(C x F 2x+1 SO2)(C y F 2y+1 At least one of the following: (SO2) (where x and y are integers from 1 to 20), lithium trifluoromethanesulfonate, lithium tetrafluoroethanesulfonate, lithium difluorobis(oxalate)phosphate (LiDFBOP), and lithium bis(oxalate)borate (LiBOB).

[0232] Rechargeable lithium batteries may also include a separator.

[0233] diaphragm Depending on the type of rechargeable lithium battery, a separator may be present between the positive and negative electrodes. The separator may include polyethylene, polypropylene, polyvinylidene fluoride, or multilayer films of two or more layers thereof (e.g., mixed multilayer films such as polyethylene / polypropylene bilayer separators, polyethylene / polypropylene / polypropylene trilayer separators, or polypropylene / polypropylene / polypropylene quadlayer separators).

[0234] The membrane may include a porous substrate and a coating layer on one or both surfaces of the porous substrate, comprising organic materials, inorganic materials, or combinations thereof.

[0235] Porous substrates can be polymer membranes formed from copolymers or mixtures of any one or more of the following polymers: polyolefins, such as polyethylene and polypropylene; polyesters, such as polyethylene terephthalate and polybutylene terephthalate; polyacetal; polyamide; polyimide; polycarbonate; polyetherketone; polyaryletherketone; polyetherimide; polyamideimide; polybenzimidazole; polyethersulfone; polyphenylene ether; cyclic olefin copolymers; polyphenylene sulfide; polyethylene naphthalate; glass fiber; and polytetrafluoroethylene (e.g., TEFLON). ® ).

[0236] Organic materials may include polyvinylidene fluoride polymers or (meth)acrylic acid polymers.

[0237] Inorganic materials may include inorganic particles selected from Al2O3, SiO2, TiO2, SnO2, CeO2, MgO, NiO, CaO, GaO, ZnO, ZrO2, Y2O3, SrTiO3, BaTiO3, Mg(OH)2, boehmite and combinations thereof, but inorganic materials are not limited to these.

[0238] Organic and inorganic materials can be mixed in a coating layer, or a coating layer containing organic materials and a coating layer containing inorganic materials can be stacked.

[0239] Rechargeable lithium batteries Rechargeable lithium batteries can be classified according to their geometry as cylindrical, prismatic, pouch, or coin-shaped batteries.

[0240] Figures 2 to 5 The diagram illustrates a rechargeable lithium battery according to some embodiments of the present disclosure. Figure 2 A cylindrical battery is shown. Figure 3 A prismatic battery is shown. Figure 4 and Figure 5 A pouch-type battery is shown. The rechargeable lithium battery 100 may include an electrode assembly 40 and a housing 50. The electrode assembly 40 includes a separator 30 between a positive electrode 10 and a negative electrode 20, and is included within the housing 50. The positive electrode 10, negative electrode 20, and separator 30 may be impregnated with an electrolyte (not shown). Figure 2 As shown, the rechargeable lithium battery 100 may include a seal 60 of the sealed housing 50. Figure 3 In this context, the rechargeable lithium battery 100 may include a positive electrode lead connector 11, a positive electrode terminal 12, a negative electrode lead connector 21, and a negative electrode terminal 22. For example... Figure 4 and Figure 5 As shown, the rechargeable lithium battery 100 may include electrode terminals 70, which may be positive electrode terminal 71 and negative electrode terminal 72 used as electrical paths for guiding current formed in the electrode assembly 40 to the outside.

[0241] As a non-limiting example, rechargeable lithium batteries according to some embodiments can be used in automobiles, mobile phones and / or various types of electronic devices.

[0242] Electronic devices may include rechargeable lithium batteries.

[0243] Examples and comparative examples of the invention will be described below. However, the following embodiments are merely exemplary, and the invention is not limited thereto.

[0244] Example 1 Preparation of the active material for the first negative electrode Thin flakes of natural graphite with an average particle size (D50) of approximately 120 μm were ground into primary particles with a plate-like geometry and a major axis length of approximately 30 μm using an air jet milling method. The primary particles were then aggregated into secondary particles using a spherical milling apparatus. The secondary particles were spherical and had an average particle size (D50) of approximately 7 μm. Petroleum pitch was added to the secondary particles, mixed, and heat-treated at approximately 3000 °C for 2 hours to prepare the first negative electrode active material. The addition of petroleum pitch resulted in a weight ratio of natural graphite to amorphous carbon of approximately 90:10 in the first negative electrode active material.

[0245] Second negative electrode active material Artificial graphite (spherical, average particle size D50: 15μm, particle density: 1.5g / cc, tap density: 0.9g / cc, specific surface area BET: 1.5m²) was used. 2 / g, orientation degree: 100) as the active material for the second negative electrode. Artificial graphite is a secondary particle in which primary particles are aggregated.

[0246] Preparation of the active material for the third negative electrode Primary particles with an average particle size D50 of about 100 nm were prepared by ball milling silicon particles with an average particle size of about 8 μm. The primary particles and stearic acid were mixed at a weight ratio of about 20:80, and the mixture was spray-dried to prepare secondary particles with an average particle size D50 of about 7 μm and pores.

[0247] The prepared secondary particles and petroleum asphalt were mixed at a weight ratio of approximately 60:40, and the mixture was compressed into shape by cold isostatic pressing at a pressure of 10 MPa. Subsequently, the resulting compression-molded product was carbonized in a nitrogen atmosphere at a temperature of approximately 1,000 °C.

[0248] The carbonization products were then sorted using a sieve to achieve a span value of approximately 1.1 according to Equation 2, and the following material was prepared: a negative electrode active material coated with soft carbon to a thickness of approximately 30 nm (which is a Si-C composite comprising secondary particles with an average particle size D50 of approximately 7 μm [in which primary Si particles with an average particle size D50 of approximately 100 nm are aggregated]) and a soft carbon coating layer coated with the secondary particles. The amount of Si nanoparticles was approximately 60 wt% and the amount of soft carbon was approximately 40 wt% relative to the total weight of the negative electrode active material. Furthermore, the D10, D50, and D90 of the negative electrode active material were measured using a particle size analyzer (product name: LS 13 320, manufacturer: Beckman Coulter), thereby allowing the span value to be calculated according to Equation 2.

[0249] Furthermore, the sphericity obtained from the cross-sectional image obtained using the Image J program via CP-SEM was approximately 0.98. Additionally, the total pore volume and mesopore volume of the prepared negative electrode active material were measured using a BJH analytical apparatus.

[0250] BJH measurements were performed using a BJH instrument (model name: ASAP 2020, manufacturer: Micromeritics) to measure the change in adsorption / desorption on a sample as a function of pressure by using nitrogen gas at a liquid nitrogen temperature (-198°C) to change the pressure from approximately 0 mmHg to approximately 950 mmHg.

[0251] The prepared third negative electrode active material (C-1) has a sphericity of approximately 0.98, a mesopore volume / total pore volume ratio of approximately 68%, and a micropore size of approximately 0.8 μm. 2 Specific surface area per g, approximately 0.007 cm² 3 / g of total pore volume as determined by BJH, D10 of approximately 4.7 μm, D50 of approximately 8.2 μm and D90 of approximately 13.7 μm.

[0252] Mixture of negative electrode active materials Based on a mixture of 100 parts by weight of negative electrode active material, a mixture of negative electrode active material is prepared by mixing 47 parts by weight of a first negative electrode active material, 47 parts by weight of a second negative electrode active material, and 6 parts by weight of a third negative electrode active material.

[0253] A negative electrode active material slurry was prepared by mixing approximately 97.5 wt% of the prepared negative electrode active material, approximately 1.5 wt% of styrene-butadiene rubber as a binder, and approximately 1.0 wt% of carboxymethyl cellulose as an additive in distilled water.

[0254] A negative electrode plate is manufactured by coating a copper current collector with a slurry of negative electrode active material, drying it, and then rolling it.

[0255] A half-cell is constructed using a negative electrode plate, a lithium metal counter electrode, and an electrolyte. The electrolyte is a mixed solvent of ethylene carbonate and dimethyl carbonate (3:7 volume ratio) in which 1 M LiPF6 is dissolved.

[0256] Example 2 Except for changing the spheroidization conditions in Example 1, the first negative electrode active material was prepared in the same manner as in Example 1. Using the prepared first negative electrode active material, a negative electrode plate and a half-cell were fabricated in the same manner as in Example 1.

[0257] Example 3 Except for changing the spheroidization conditions in Example 1, the first negative electrode active material was prepared in the same manner as in Example 1. Using the prepared first negative electrode active material, a negative electrode plate and a half-cell were fabricated in the same manner as in Example 1.

[0258] Example 4 and Example 5 The negative electrode plate and half cell were manufactured in the same manner as in Example 1, except that the weight ratios of the components in Example 1 were changed as shown in Table 1 below.

[0259] Comparison Example 1 Except that petroleum asphalt is not added in the preparation of the first negative electrode active material in Example 1, the first negative electrode active material is prepared in the same manner as in Example 1. Using the prepared first negative electrode active material, a negative electrode plate and a half cell are manufactured in the same manner as in Example 1.

[0260] Comparison Example 2 Natural graphite raw material with an average particle size D50 of approximately 120 μm or larger was ground into primary particles with an elongation length of approximately 120 μm using an air jet milling method. The primary particles were then aggregated into secondary particles with an average particle size of approximately 20 μm using a spheroidizing device. The first negative electrode active material was prepared by adding petroleum pitch to the secondary particles, mixing them, and then heat-treating the resulting mixture at approximately 1200 °C for approximately 2 hours. The addition of petroleum pitch resulted in a weight ratio of natural graphite to amorphous carbon of approximately 90:10 in the first negative electrode active material.

[0261] Using the prepared first negative electrode active material, a negative electrode plate and a half cell are manufactured in the same manner as in Example 1.

[0262] Compare Example 3 Except that silicon oxide (C-2) is used instead of the third negative electrode active material in Example 1, the negative electrode plate and half cell are manufactured in the same manner as in Example 1.

[0263] Experimental Example 1: Evaluation of the active material of the first negative electrode Particle density (unit: g / cc) Particle density was measured using a Carver 4350.L (CARVER) particle density meter. After adding 1.0 g of the first negative electrode active material from both the example and comparative examples to the mold, the powder density was measured while the mold was held under a pressure of approximately 2.0 tons for approximately 30 seconds.

[0264] Orientation degree: Orientation was measured using an XRD analyzer X'Pert Pro (PANalytical). The ratio of the diffraction peak intensity I(002) to the diffraction peak intensity I(110) of the (002) plane of each first negative electrode active material in the example and comparative examples was measured by X-ray diffraction analysis of CuKα radiation.

[0265] d002 (unit: Å) d002 was measured using an XRD analyzer X'Pert Pro (PANalytical). The interplanar spacing of the (002) planes of the individual first negative electrode active materials in the example and comparative examples was measured by X-ray diffraction analysis using CuKα radiation.

[0266] Sphericity: Sphericity was measured using a Morphologi 4 (Malvern) sphericity analyzer. For each first negative electrode active material in the example and comparative examples, values ​​A and B in Equation 1 were obtained, and then sphericity was calculated according to Equation 1.

[0267] Hg cumulative pore volume (unit: mL / g) The cumulative Hg pore volume of each first negative electrode active material in the example and comparative examples was measured using an AutoPore V (Micromeritics) Hg intrusion porosimetry method. The negative electrode active material was placed in a dedicated sample cup, surrounded by mercury, and pressure was applied in the range of approximately 0.2 psi to approximately 60,000 psi to intrude the mercury into the negative electrode active material. Mercury porosity was then measured by monitoring changes in mercury volume in the capillary rod reservoir. Pore sizes ranging from approximately 0.01 μm to approximately 100 μm can be measured using the above method; typically, pores with sizes from approximately 0.01 μm to approximately 5 μm are consistent with the pore size of the active material in the negative electrode active material.

[0268] Experimental Example 2: Evaluation of Battery Characteristics Capacity (unit: mAh / g) and charge rate (unit: %) The charge and discharge capacities were measured by charging and discharging the manufactured half-cells at 0.1C. The measured discharge capacities are shown in Table 1 below, and the coulombic efficiency (discharge capacity / charge capacity × 100%) was measured.

[0269] The manufactured half-cell was subjected to one cycle of 0.2C constant current (CC) / constant voltage (CV) charging and 0.2C discharging, one cycle of 0.5C CC charging and 0.2C discharging, one cycle of 1C CC charging and 0.2C discharging, and one cycle of 2C CC charging and 0.2C discharging, and then the charging characteristics were calculated. Charging conditions were a 10mV cutoff for the CC phase and a 15-hour cutoff for the CV phase, and a 1.5V cutoff for discharging. Charging characteristics were measured at each C rate. The charging characteristics were expressed as the ratio of the 2C CC charging capacity to the 0.2C CC charging capacity.

[0270] Energy density (unit: Wh / L) (Battery cell capacity (Ah) × Average battery cell voltage (V)) / Battery cell volume (L) Energy density is a value obtained by dividing the product of the discharge capacity obtained by discharging at a C-rate of 0.1C to 1C within the operating voltage range of the battery cell and the average voltage of the corresponding battery cell by the volume of the battery cell.

[0271] Efficiency (unit: %) Efficiency is measured in the same way as capacity and SoC characteristics. Efficiency is calculated as (first cycle discharge capacity / first cycle charge capacity × 100) (formation discharge / formation charge × 100).

[0272] Swelling rate (unit: %) The expansion rate was measured using a thickness monitoring system (TMS).

[0273] Individual battery cells manufactured according to the example and comparative examples were evaluated by charging and discharging at approximately 45°C (0.5C / 0.5C) under conditions including a charging voltage of 4.35V and a discharging voltage of 2.8V, while continuously monitoring the cell thickness in real time during the charge and discharge cycles. The expansion rate was evaluated by comparing the thickness increase after 50 cycles with the thickness after one cycle.

[0274] Expansion rate = (cell thickness after 50 cycles - cell thickness after 1 cycle) / cell thickness after 1 cycle × 100 Table 1:

[0275] In Table 1, C-1 is silicon-carbon composite, C-2 is silicon oxide, and the weight ratio is expressed as [first negative electrode active material]: [second negative electrode active material]: [third negative electrode active material] based on 100 parts by weight of negative electrode active material.

[0276] As shown in Table 1, the example negative electrode plate for rechargeable lithium batteries simultaneously offers high energy density, long cycle life, boost charging performance, and improved expansion characteristics, thus exhibiting excellent rechargeable lithium battery performance. In particular, the example negative electrode plate has a significantly low expansion rate. On the other hand, the negative electrode plate of the comparative example, which does not have a first or third negative electrode active material, has a significantly high expansion rate.

[0277] Example 6 Preparation of the active material for the first negative electrode Flake-shaped natural graphite raw material with an average particle size D50 of approximately 120 μm was ground into primary particles with a plate-like geometry and a major axis length of approximately 30 μm using an air jet milling method. The primary particles were then aggregated into spherical secondary particles with an average particle size D50 of approximately 7 μm using a spheroidizing device. Petroleum pitch was added to the secondary particles, mixed, and heat-treated at approximately 3000 °C for 2 hours to prepare the first negative electrode active material. Carbon pitch was added to achieve a weight ratio of natural graphite to amorphous carbon of approximately 90:10 in the first negative electrode active material.

[0278] Second negative electrode active material Artificial graphite (spherical, average particle size D50 of 15 μm, particle density of 1.5 g / cc, tap density of 0.9 g / cc, specific surface area BET of 1.5 m²) was used. 2 / g, with an orientation degree of 100) is used as the active material for the second negative electrode. Artificial graphite consists of secondary particles in which primary particles are aggregated.

[0279] Preparation of the active material for the third negative electrode Primary particles with an average particle size D50 of approximately 100 nm were prepared by ball milling silicon particles with an average particle size of approximately 8 μm. The primary particles and stearic acid were mixed at a weight ratio of approximately 20:80, and the mixture was spray-dried to prepare secondary particles with an average particle size D50 of approximately 7 μm and pores.

[0280] The prepared secondary particles and petroleum asphalt were mixed at a weight ratio of approximately 60:40, and the mixture was compressed into shape by cold isostatic pressing at a pressure of 10 MPa. Subsequently, the resulting compression-molded product was carbonized in a nitrogen atmosphere at a temperature of approximately 1,000 °C.

[0281] The carbonization products were then sorted using a sieve to achieve a span value of 1.1 in Equation 2, and the following material was prepared: a negative electrode active material coated with soft carbon to a thickness of approximately 30 nm (which is a Si-C composite containing secondary particles with an average particle size D50 of approximately 7 μm [in which primary Si particles with an average particle size D50 of approximately 100 nm are aggregated]) and a soft carbon coating layer coated with the secondary particles. The amount of Si nanoparticles was approximately 60 wt% and the amount of soft carbon was approximately 40 wt% relative to the total weight of the negative electrode active material. Furthermore, the D10, D50, and D90 of the negative electrode active material were measured using a particle size analyzer (product name: LS 13 320, manufacturer: Beckman Coulter), and the span value was obtained according to Equation 2.

[0282] In addition, a sphericity value of 0.98 was obtained from the cross-sectional images of the secondary particles using the Image J program via CP-SEM. Furthermore, the total pore volume and mesopore volume of the prepared negative electrode active material were measured using a BJH analytical apparatus.

[0283] BJH measurements were performed using a BJH instrument (model name: ASAP 2020, manufacturer: Micromeritics) to measure the change in adsorption / desorption on a sample as a function of pressure by using nitrogen gas at a liquid nitrogen temperature (-198°C) to change the pressure from approximately 0 mmHg to approximately 950 mmHg.

[0284] The prepared third negative electrode active material has a sphericity of approximately 0.98, a mesopore volume / total pore volume ratio of approximately 68%, and a micropore size of approximately 0.8 μm. 2 Specific surface area per g, approximately 0.007 cm² 3 The total pore volume per g (as determined by BJH), D10 of approximately 4.7 μm, D50 of approximately 8.2 μm, and D90 of approximately 13.7 μm.

[0285] Mixture of negative electrode active materials A mixture of negative electrode active materials was prepared by mixing 47 parts by weight of a first negative electrode active material, 47 parts by weight of a second negative electrode active material, and 6 parts by weight of a third negative electrode active material, based on 100 parts by weight of the negative electrode active material mixture.

[0286] A negative electrode active material slurry was prepared by mixing approximately 97.5 wt% of the prepared negative electrode active material mixture, approximately 0.04 wt% of single-walled carbon nanotubes (SWCNTs) (D-1) as a conductive material, and approximately 2.46 wt% of styrene-butadiene rubber as a binder in distilled water.

[0287] A negative electrode plate is manufactured by coating a copper current collector with a slurry of negative electrode active material, drying it, and then rolling it.

[0288] A half-cell is constructed using a negative electrode plate, a lithium metal counter electrode, and an electrolyte. The electrolyte is a mixed solvent (3:7 volume ratio) of ethylene carbonate and dimethyl carbonate in which 1 M LiPF6 is dissolved.

[0289] Example 7 Except for changing the spheroidization conditions in Example 6, the first negative electrode active material was prepared in the same manner as in Example 6. Using the prepared first negative electrode active material, a negative electrode plate and a half-cell were fabricated in the same manner as in Example 6.

[0290] Example 8 Except for changing the spheroidization conditions in Example 6, the first negative electrode active material was prepared in the same manner as in Example 6. Using the prepared first negative electrode active material, a negative electrode plate and a half-cell were fabricated in the same manner as in Example 6.

[0291] Examples 9 and 10 Except for changing the weight ratio of the components in Example 6 as shown in Table 2 below, the negative electrode plate and half cell are manufactured in the same manner as in Example 6.

[0292] Example 11 The negative electrode plate and half cell were fabricated in the same manner as in Example 6, except that denka black (carbon black) (D-2) was used instead of single-walled carbon nanotubes as the conductive material.

[0293] Experimental Example 3: Evaluation of the Active Material of the First Negative Electrode Particle density (g / cc), orientation, d002 (Å), sphericity, and Hg cumulative pore volume (mL / g) were evaluated in the same manner as in Experimental Example 1.

[0294] Experimental Example 4: Evaluation of Battery Characteristics Capacity (unit: mAh / g) and charge rate (unit: %) The charge and discharge capacities were measured by charging and discharging the manufactured half-cells at 0.1C. The measured discharge capacities are shown in Table 1, and the coulombic efficiency (discharge capacity / charge capacity × 100%) was measured.

[0295] The manufactured half-cell was subjected to one cycle of 0.2C constant current (CC) / constant voltage (CV) charging and 0.2C discharging, one cycle of 0.5C CC charging and 0.2C discharging, one cycle of 1C CC charging and 0.2C discharging, and one cycle of 2C CC charging and 0.2C discharging, and then the charging characteristics were calculated. Charging conditions were a 10mV cutoff for the CC phase and a 15-hour cutoff for the CV phase, and a 1.5V cutoff for discharging. Charging characteristics were measured at each C rate. The charging characteristics were expressed as the ratio of the 2C CC charging capacity to the 0.2C CC charging capacity.

[0296] Fast charging time (unit: s): Fast charging time refers to the time required to charge a battery from approximately 8% to approximately 80% using constant current charging, and is evaluated by identifying charging modes that do not reach the upper limit voltage of 4.2V during charging.

[0297] Fast charging cycle life (unit: number of times): A cycle is defined as charging the State of Charge (SOC) from about 8% to about 80% and discharging it at a constant current of about 0.33C to about 2.8V based on a defined fast charging time, and evaluating fast charging cycle life by cycling until the State of Health (SOH) is about 80%.

[0298] Swelling rate (unit: %) The expansion rate was measured using a thickness monitoring system (TMS).

[0299] Individual cells manufactured according to the example and comparative examples were evaluated by charging and discharging at approximately 45°C (0.5C / 0.5C) under conditions including a charging voltage of 4.35V and a discharging voltage of 2.8V, while continuously monitoring the cell thickness in real time during the charge and discharge cycles. The expansion rate was evaluated by comparing the thickness increase after 50 cycles with the thickness after one cycle.

[0300] Expansion rate = (cell thickness after 50 cycles - cell thickness after 1 cycle) / cell thickness after 1 cycle × 100 Table 2:

[0301] In Table 2, C-1 represents silicon-carbon composite, D-1 represents single-arm carbon nanotube, D-2 represents Denka black (carbon black), and the weight ratio based on 100 parts by weight of negative electrode active material is expressed as [first negative electrode active material]: [second negative electrode active material]: [third negative electrode active material].

[0302] As shown in Table 2, the example negative electrode plate for rechargeable lithium batteries has high capacity, high SOC, short fast charging time, low expansion rate and long fast charging life, thus exhibiting high energy density, high rate charging characteristics and improved electrode expansion properties.

[0303] Although preferred embodiments of the present invention have been described above, the present invention is not limited thereto, and various modifications can be made to the embodiments shown in the above embodiments and the accompanying drawings.

Claims

1. A negative electrode plate for a rechargeable lithium battery, the negative electrode plate comprising a negative electrode active material, the negative electrode active material comprising: A first negative electrode active material, comprising: natural graphite including secondary particles, said secondary particles being aggregates of primary particles; and a first coating layer comprising amorphous carbon, the first coating layer surrounding each of said secondary particles, the first negative electrode active material having an orientation degree of 90 or less and having d002 in the range of 3.356 Å to 3.360 Å. The second negative electrode active material includes graphite; and A third negative electrode active material having a sphericity of 0.9 to 1.0, the third negative electrode active material comprising: silicon nanoparticles; and a second coating layer comprising amorphous carbon, the second coating layer surrounding each of the silicon nanoparticles.

2. The negative electrode plate according to claim 1, wherein, The first negative electrode active material has an Hg cumulative pore volume of 0.01 mL / g to 0.06 mL / g.

3. The negative electrode plate according to claim 1, wherein, The first negative electrode active material has a particle density of 1.60 g / cc to 1.80 g / cc.

4. The negative electrode plate according to claim 1, wherein, The first negative electrode active material has a sphericity greater than or equal to 0.

85.

5. The negative electrode plate according to claim 1, wherein, The ratio of the major axis length of the primary particles to the average particle size D50 of the secondary particles is 2 to 10.

6. The negative electrode plate according to claim 1, wherein, Each of the primary particles has a sheet-like geometry, and Each of the secondary particles has a spherical geometry.

7. The negative electrode plate according to claim 1, wherein, The major axis length of each of the primary particles is in the range of 10 μm to 200 μm.

8. The negative electrode plate according to claim 1, wherein, The average particle size D50 of the secondary particles is less than or equal to 30 μm.

9. The negative electrode plate according to claim 1, wherein, The first negative electrode active material also includes a third coating layer comprising amorphous carbon, the third coating layer surrounding each of the primary particles.

10. The negative electrode plate according to claim 1, wherein, The amorphous carbon includes soft carbon, hard carbon, mesophase pitch carbides, or calcined coke.

11. The negative electrode plate according to claim 9, wherein, The weight ratio of natural graphite to amorphous carbon in the first negative electrode active material is 90:10 to 75:25, relative to the total 100 parts by weight of natural graphite and amorphous carbon in the first negative electrode active material.

12. The negative electrode plate according to claim 1, wherein, The third negative electrode active material has pores including mesopores.

13. The negative electrode plate according to claim 12, wherein, The mesopore volume of the active material of the third negative electrode is 30% to 70% of the total pore volume.

14. The negative electrode plate according to claim 1, wherein, The span value is expressed by the following equation: Span = (D90 - D10) / D50 Wherein, D10 is the particle size of the third negative electrode active material particles that accumulate to 10% of the total volume in the particle size distribution of the third negative electrode active material. Wherein, D50 is the average particle size of the third negative electrode active material particles that accumulate to 50% of the total volume in the particle size distribution. Wherein, D90 is the particle size of the third negative electrode active material particles that accumulate to 90% of the total volume in the particle size distribution, and The active material of the third negative electrode has a value ranging from 1.1 to 1.

6.

15. The negative electrode plate according to claim 1, wherein, Relative to the total 100wt% of the third negative electrode active material, the third negative electrode active material comprises 55wt% to 64wt% of the silicon nanoparticles, and Of which, relative to the total 100wt% of the third negative electrode active material, the third negative electrode active material includes 36wt% to 45wt% of amorphous carbon.

16. The negative electrode plate according to claim 1, wherein, The third negative electrode active material also includes a polymer layer surrounding the second coating layer.

17. The negative electrode plate according to claim 16, wherein, The polymer layer comprises a copolymer of polyvinyl alcohol and polyacrylic acid.

18. The negative electrode plate according to claim 1, wherein, The negative electrode active material includes 20 wt% to 75 wt% of the first negative electrode active material, 20 wt% to 75 wt% of the second negative electrode active material, and 1 wt% to 20 wt% of the third negative electrode active material.

19. The negative electrode plate according to claim 1, wherein, The graphite in the second negative electrode active material is artificial graphite, which has an average particle size D50 of 10 μm to 20 μm, a particle density of 1.1 g / cc to 1.6 g / cc, and a particle size of less than or equal to 10 μm. 2 Specific surface area per g and orientation degree greater than or equal to 90.

20. The negative electrode plate according to claim 1, wherein the negative electrode plate further comprises a conductive material.

21. The negative electrode plate according to claim 20, wherein, The conductive material includes carbon nanotubes.

22. The negative electrode plate according to claim 20, wherein, The negative electrode plate comprises 0.01 wt% to 5 wt% of the conductive material.

23. A rechargeable lithium battery, said rechargeable lithium battery comprising: The negative electrode plate according to any one of claims 1 to 22; as well as Positive electrode.

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