Negative electrode active material, method of preparing same, and rechargeable lithium battery including same

Abstract

Disclosed are a negative electrode active material, a method of preparing the same, and a rechargeable lithium battery including the same, in which the negative electrode active material includes a crystalline carbon matrix having a BET specific surface area of less than or equal to about 8 m2 / g and a degree of graphitization of greater than or equal to about 95%, and silicon dispersed in the crystalline carbon matrix.

Description

Technical Field

[0001] One or more aspects of embodiments of the present disclosure relate to a negative electrode active material, a method of preparing the negative electrode active material, and a rechargeable lithium battery including the negative electrode active material. Background Art

[0002] Recently, the rapid spread of battery-based electronic devices (such as mobile phones and / or laptop computers) and the rapid growth of electric vehicles have significantly increased the demand for rechargeable batteries with relatively high energy density and high capacity. As a result, research and development efforts are actively underway to enhance (improve) the performance of rechargeable batteries, particularly rechargeable lithium batteries.

[0003] Rechargeable lithium batteries include positive and negative electrodes, as well as an electrolyte (composed of the positive and negative electrodes and the electrolyte). Both the positive and negative electrodes contain active materials capable of intercalating and deintercalating lithium ions. These rechargeable lithium batteries generate electrical energy through oxidation and reduction reactions when lithium ions are intercalated and deintercalated into and from the positive and negative electrodes. Summary of the Invention

[0004] One or more aspects of the presented embodiments provide a negative electrode active material exhibiting excellent or improved capacity and high or improved input / output characteristics.

[0005] One or more aspects of the presented embodiments provide a method of preparing a negative electrode active material.

[0006] One or more aspects of the presented embodiments provide a rechargeable lithium battery including a negative electrode active material.

[0007] Additional aspects will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the disclosed presented embodiments.

[0008] One or more embodiments provide a negative electrode active material, the negative electrode active material including a material having a molecular weight of less than or equal to about 8 m 2 The present invention relates to a crystalline carbon matrix having a BET (Brunauer-Emmett-Teller) specific surface area of ​​1000 nm / g and a degree of graphitization of about 95% or more, and silicon dispersed in the crystalline carbon matrix.

[0009] One or more embodiments provide a method for preparing a negative electrode active material, the method comprising mixing a hard carbon precursor and a metal catalyst to prepare a mixture; heat-treating the mixture to produce a heat-treated product; removing the metal catalyst from the heat-treated product to produce a crystalline carbon matrix; and loading silicon on the crystalline carbon matrix (e.g., dispersing silicon in the crystalline carbon matrix).

[0010] One or more embodiments provide a rechargeable lithium battery including: a negative electrode including a negative electrode active material; a positive electrode; and a non-aqueous electrolyte.

[0011] The negative electrode active material according to some example embodiments may exhibit excellent or improved cycle-life and high or improved input / output characteristics. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 is a diagram schematically illustrating a negative electrode active material according to one or more embodiments.

[0013] Figure 2 is a diagram illustrating a method of preparing a negative electrode active material according to one or more embodiments.

[0014] Figures 3 to 6 are cross-sectional views each schematically illustrating a rechargeable lithium battery according to one or more embodiments. DETAILED DESCRIPTION

[0015] Hereinafter, embodiments will be described in more detail. However, these embodiments are presented as examples, and the present disclosure is not limited thereto, but is defined by the scope of the claims described in more detail herein.

[0016] As used herein, unless otherwise specifically defined (e.g., when not otherwise specifically defined), it will be understood that if an element such as a layer, film, region, and / or substrate is referred to as being “on” another element (e.g., when an element such as a layer, film, region, and / or substrate is referred to as being “on” another element), the element can be directly on the other element (e.g., without any intervening elements therebetween), or one or more intervening elements may also be present. In contrast, if an element is referred to as being “directly on” another element (e.g., when an element is referred to as being “directly on” another element), there are no intervening elements.

[0017] As used herein, unless otherwise specified (e.g., when no specific definition is provided), the singular may also include the plural. In addition, unless otherwise specified, "A or B" may mean "including A, including B, or including A and B." In the disclosure, unless the context clearly indicates otherwise, the singular forms "a," "an," and "the" are intended to include the plural forms as well. In addition, when describing embodiments of the present disclosure, the use of "may" means "one or more embodiments of the present disclosure."

[0018] As used herein, "combinations thereof" may refer to mixtures, stacks, composites, copolymers, alloys, blends, and / or reaction products of the components.

[0019] As used herein, if no definition is otherwise provided (e.g., when no definition is otherwise provided), the particle size may be an average particle size. The average particle size refers to the average particle size (D50), which refers to the diameter (D50) of particles having a cumulative volume of 50% by volume in a particle size distribution. The average particle size can be measured by any suitable method in the art, for example, it can be measured by a particle size analyzer, or it can be measured by a transmission electron microscope (TEM) image or a scanning electron microscope (SEM) image. In one or more embodiments, the average particle size value can be obtained by performing data analysis using a dynamic light scattering method, counting the number of particles in each particle size range, and thereby calculating the average particle size value. Laser diffraction can also be used. If measured by laser diffraction (more specifically, the particles to be measured are dispersed in a dispersion medium and then introduced into a commercially available laser diffraction particle size measuring apparatus (e.g., MT-3000™ available from Micro-Trak Systems) using ultrasonic waves of about 28 kHz), and after irradiation with an output of 60 W, the average particle size (D50) based on 50% of the particle size distribution in the measuring apparatus can be calculated.

[0020] In this specification, when the particles are spherical, "diameter" refers to the particle size, and when the particles are non-spherical, "diameter" refers to the length of the major axis. In some example embodiments, the average particle size can be measured by one or more suitable methods described above (e.g., by a particle size analyzer).

[0021] In some example embodiments, the thickness may be measured using a scanning electron microscope (SEM) image or a transmission electron microscope (TEM) image of a cross section, but the present disclosure is not limited thereto, and the thickness may be measured using any suitable method known in the art. The thickness may be an average thickness.

[0022] As used herein, soft carbon refers to a graphitizable carbon material that can be graphitized by heat treatment at high temperatures (e.g., 2800° C.), and hard carbon refers to a non-graphitizable carbon material that does not graphitize or is substantially non-graphitizable (substantially resistant to graphitization) by heat treatment. Hard carbon may also be referred to as a non-graphitizable carbon material. The terms soft carbon and hard carbon are well known in the art.

[0023] In some exemplary embodiments, crystalline carbon and amorphous carbon can be classified by X-ray diffraction analysis. Crystalline carbon includes natural graphite and artificial graphite. Natural graphite refers to naturally occurring graphite obtained by separation from minerals and having a d002 of approximately 3.350 Å to approximately 3.360 Å when analyzed by X-ray diffraction. Artificial graphite refers to graphite prepared by graphitization and having a d002 of approximately 3.355 Å to approximately 3.365 Å when analyzed by X-ray diffraction (e.g., when analyzed by X-ray diffraction), amorphous carbon has a d002 of less than or equal to approximately 3.34 Å. X-ray diffraction analysis (XRD) uses CuKα radiation as a target line and uses an X-ray diffraction analyzer (e.g., X'Pert (manufacturer: Malvern Panalytical)). To improve peak intensity resolution, the monochromator device can be removed and measurement performed. X-ray diffraction analysis can be performed using the following conditions: using CuKα radiation as a target line, a wavelength of λ=1.5418±0.02 Å, scanning 2θ=20° to 80°, and a scanning rate of 1° / min to 5° / min.

[0024] The negative electrode active material according to some example embodiments includes: a crystalline carbon matrix having a carbon content of less than or equal to about 8 m 2 / g of BET specific surface area and a degree of graphitization greater than or equal to about 95%; and silicon, dispersed in the crystalline carbon matrix. Figure 1 A negative electrode active material 1 including a crystalline carbon matrix 3 and silicon 5 dispersed in the crystalline carbon matrix 3 according to some example embodiments is schematically illustrated.

[0025] The BET specific surface area of ​​the crystalline carbon matrix according to some example embodiments may be less than or equal to about 8 m 2 / g, about 0.5m 2 / g to about 8m 2 / g or about 1m 2 / g to about 5m 2 / g.

[0026] If the BET specific surface area of ​​the crystalline carbon matrix is ​​less than or equal to about 8 m 2 / g, the reaction area with the electrolyte is minimized or reduced, so there are fewer irreversible reactions during charge / discharge, which can be advantageous in terms of cycle-life characteristics.

[0027] In some example embodiments, the BET specific surface area may be a specific surface area obtained from an adsorption isotherm using a BET (Brunauer, Emmet, Teller) method. In the measurement of the adsorption isotherm, nitrogen may be used as the adsorption gas.

[0028] The crystalline carbon matrix according to some example embodiments may have a degree of graphitization greater than or equal to about 95%, about 95% to about 99%, about 95% to about 98%, or about 97% to about 99%.

[0029] In some exemplary embodiments, the degree of graphitization can be obtained by X-ray diffraction measurement. For example, the degree of graphitization can be obtained by measuring d002 using an X-ray diffraction analyzer (e.g., a Bruker D8 DISCOVER) in accordance with Japanese Industrial Standards (JIS) K0131-1996 or JB / T 4220-2011, and then calculating the value using (0.344 - d002) / (0.344 - 0.3354) × 100%. Here, d002 is the interlayer spacing of the graphite crystal structure expressed in nanometers (nm). X-ray diffraction analysis can be performed using the following conditions: using CuKα radiation as a target line, a wavelength of λ = 1.5418 ± 0.02 Å, scanning from 2θ = 20° to 80°, and a scanning rate of 1° / min to 5° / min.

[0030] In the negative electrode active material according to some example embodiments, the crystalline carbon matrix has a high degree of graphitization greater than or equal to about 95%, and thus high or improved capacity / high density may be achieved and a negative electrode with high or improved energy density may be manufactured.

[0031] The crystalline carbon matrix according to some example embodiments may be porous. If the crystalline carbon matrix is ​​porous, the porous matrix can be used to absorb the volume expansion of silicon that may occur during charging and discharging, thereby preventing or reducing the total volume increase of the negative electrode active material. For example, because the crystalline carbon matrix includes pores, these pores can act as a buffer to absorb volume expansion, so that if the silicon dispersed in the crystalline carbon matrix expands in volume, the expanded volume can be absorbed. As a result, the structure of the negative electrode active material can be well maintained during charging and discharging, and the cycle life characteristics can be further improved.

[0032] Additionally, higher or improved efficiencies and charging rates can be achieved if the crystalline carbon matrix is ​​porous.

[0033] In some example embodiments, the porosity of the crystalline carbon matrix may be from about 1% to about 50%, from about 1% to about 30%, or from about 1% to about 10%. If the porosity of the crystalline carbon matrix is ​​within any of the above ranges, the volume expansion of silicon can be more effectively and sufficiently (or appropriately) absorbed, thereby further improving cycle life characteristics.

[0034] In some exemplary embodiments, porosity can be measured using a general porosity measurement method. For example, porosity can be measured using mercury intrusion porosimetry. In one or more embodiments, porosity can be measured using a Barret-Joyner-Halenda (BJH) method using a N2 adsorption isotherm. For example, a crystalline carbon substrate is heated to 523 K (Kelvin, absolute temperature) at a rate of approximately 10 K / min, then pretreated by maintaining it at this temperature and a pressure of approximately 100 mmHg or less for approximately 2 to 10 hours. Nitrogen is then adsorbed at approximately 32 points in liquid nitrogen adjusted to a relative pressure (P / P0) of approximately 0.01 Torr or less, and then desorbed at approximately 24 points until the relative pressure reaches approximately 0.14 Torr. For a given volume of the crystalline carbon substrate, the porosity can be determined from the N2 content (e.g., amount) measured using the above method.

[0035] In some example embodiments, the crystalline carbon may be artificial graphite, and may be artificial graphite of non-specific (random) shape, plate shape, flake shape, spherical shape, and / or fibrous shape.

[0036] In some example embodiments, silicon is dispersed in a crystalline carbon matrix to be included in the negative electrode active material. Since silicon is dispersed in the crystalline carbon matrix and is not exposed to the outside, side reactions caused by contact between silicon and the electrolyte can be suppressed or reduced.

[0037] Furthermore, because the crystalline carbon matrix can suppress or reduce the volume expansion of silicon during charge and discharge, the highly improved capacity characteristics of silicon can be effectively or appropriately utilized.

[0038] The silicon may be nano-silicon, such as nano-silicon particles. The average size (e.g., average particle size or average particle diameter) of the nano-silicon may be less than or equal to about 50 nm, about 1 nm to about 40 nm, about 1 nm to about 30 nm, about 1 nm to about 20 nm, or about 2 nm to about 15 nm. If the silicon is nano-silicon, in some example embodiments, nano-silicon having the above-mentioned size may have advantages in terms of cycle life characteristics due to small (or insignificant) volume expansion during charging / discharging of a lithium-ion battery.

[0039] In some example embodiments, the amount of silicon may be from about 1 wt % to about 55 wt %, from about 5 wt % to about 55 wt %, from about 10 wt % to about 55 wt %, or from about 27 wt % to about 55 wt %, based on 100 wt % of the negative electrode active material. If the silicon content (e.g., amount) is within any of the above ranges, a higher capacity may be achieved.

[0040] In some example embodiments, silicon may be pure silicon. However, silicon can naturally oxidize and may be present in trace amounts in the negative electrode active material in the form of silicon oxide. Therefore, the negative electrode active material according to some example embodiments may also include trace amounts of oxygen. Based on 100 wt% of the negative electrode active material, the amount of oxygen may be from about 0.5 wt% to about 20 wt%, from about 0.5 wt% to about 10 wt%, or from about 0.5 wt% to about 1 wt%. If the amount of oxygen is a trace amount within any of the above ranges, higher battery efficiency can be achieved because the initial efficiency is appropriately high, the irreversible capacity is very small (for example, there are very few irreversible reactions during charge / discharge), side reactions can be further reduced, and cycle life characteristics can be further improved. In other words, if the oxygen content is within the specified range, the initial efficiency of the battery is high and the irreversible capacity is very small, meaning that there are very few irreversible reactions during charge and discharge.

[0041] In some example embodiments, oxygen content (eg, amount) may be measured by infrared absorption using an oxygen analyzer, and measurement conditions may be appropriately or suitably adjusted within conditions suitable in the art.

[0042] Negative electrode active materials according to some example embodiments may have the advantage of reducing side reactions with the electrolyte by loading silicon within a crystalline carbon matrix (e.g., a porous crystalline carbon matrix) rather than externally. Furthermore, due to their high crystallinity (e.g., due to the overall high crystallinity of the negative electrode active material), they may have (e.g., simultaneously) the high capacity advantages of both silicon and graphite. For example, the negative electrode active materials in some embodiments may reduce or minimize side reactions with the electrolyte by incorporating silicon within the porous crystalline carbon matrix. Due to the high overall crystallinity of the material, this design leverages the high capacity advantages of both graphite and silicon.

[0043] In some example embodiments, the negative electrode active material may further include hard carbon and / or soft carbon. If hard carbon and / or soft carbon are further included, fast charging may be further improved.

[0044] If hard carbon and / or soft carbon are further included, the amount of the hard carbon and / or soft carbon may be greater than about 0 wt % and less than or equal to about 30 wt %, about 2 wt % to about 20 wt %, or about 2 wt % to about 10 wt % based on 100 wt % of the negative electrode active material.

[0045] In the negative electrode active material according to some example embodiments, the amount of the crystalline carbon matrix may be the balance (eg, the amount remaining thereafter) excluding the amounts of silicon, optional oxygen, and hard carbon.

[0046] The pellet density of the negative electrode active material according to some example embodiments may be greater than or equal to about 1.7 g / cc, about 1.7 g / cc to about 2.0 g / cc, or about 1.7 g / cc to about 1.9 g / cc. The fact that the pellet density of the negative electrode active material is greater than or equal to about 1.7 g / cc indicates that the negative electrode active material is soft, for example, meaning that it can be relatively easy to press. If the pellet density of the negative electrode active material according to some example embodiments is greater than or equal to about 1.7 g / cc, a suitably high-density negative electrode can be manufactured, and a suitably high-energy-density negative electrode can be achieved. In addition, the negative electrode active material according to some example embodiments has a pellet density greater than or equal to about 1.7 g / cc, thereby being able to exhibit (have) an excellent or improved charging rate.

[0047] In some exemplary embodiments, the pellet density may be measured by a suitable method in the art. For example, the pellet density may be obtained by measuring the pellet density using a pellet density machine under a certain pressure (eg, 2 tons of pressure).

[0048] In some exemplary embodiments, the pellet density may be a powder pellet density or a slurry pellet density. The powder pellet density is the density measured when pellets are produced using only the negative electrode active material. The powder pellet production process may be performed by placing about 0.5 g to about 1.0 g of the negative electrode active material into a mold and maintaining the mold under a pressure of about 1.0 tons to about 2.0 tons for about 20 seconds to about 30 seconds.

[0049] The slurry pellet density is measured using pellets prepared by mixing a negative electrode active material, a binder, and an optional conductive material to prepare a slurry, drying and pulverizing the slurry, and then applying pressure. The pressure application process can be performed by maintaining the pressure at a pressure of about 1.0 tons to about 6.0 tons for about 20 seconds to about 30 seconds.

[0050] An average particle size (D50) of the negative electrode active material according to some example embodiments may be about 5 μm to about 15 μm.

[0051] Method for preparing negative electrode active material The negative electrode active material according to some example embodiments is prepared by the following steps: mixing a carbon precursor and a metal catalyst to prepare a mixture; heat-treating the mixture to produce a heat-treated product; removing the metal catalyst from the heat-treated product to produce a crystalline carbon matrix; and supporting silicon on the crystalline carbon matrix (e.g., dispersing or inserting silicon into the crystalline carbon matrix). Figure 2 Describe each process.

[0052] A carbon precursor and a metal catalyst are mixed to prepare a mixture. The metal catalyst promotes and / or accelerates graphitization of the carbon precursor. Because some example embodiments heat-treat the carbon precursor with the metal catalyst, amorphous carbon precursors (e.g., hard carbon precursors) that are not graphitizable even when heat-treated at high temperatures can be graphitized. Soft carbon precursors (which are graphitized when heat-treated at temperatures greater than or equal to approximately 3000°C) can also be graphitized even when heat-treated at low temperatures. In other words, because some example embodiments heat-treat the carbon precursor with the metal catalyst, amorphous carbon precursors (e.g., hard carbon precursors) that are not graphitizable even when heat-treated at high temperatures can be graphitized (e.g., their carbon atoms can be rearranged into a crystal structure typical of graphite). Furthermore, soft carbon precursors, which typically require heat treatment at temperatures greater than or equal to approximately 3000°C for graphitization, can be graphitized at lower temperatures.

[0053] In the related art, because a hard carbon precursor forms hard carbon upon heat treatment, the hard carbon does not graphitize even when heat treated at high temperatures. However, because some exemplary embodiments utilize a metal catalyst, heat treatment of the hard carbon precursor graphitizes the precursor, forming crystalline carbon (e.g., graphite). The graphite produced by this process may be artificial graphite.

[0054] The crystalline carbon matrix prepared by the process may be a porous crystalline carbon matrix, for example, a crystalline carbon matrix having pores. Since the pores are spaces where silicon is located (silicon loading process), silicon can be distributed in the crystalline carbon matrix.

[0055] The carbon precursor and the metal catalyst may be mixed in a weight ratio of about 95:5 to about 50:50, about 95:5 to about 60:40, or about 90:10 to about 70:30. If the mixing ratio of the carbon precursor and the metal catalyst is within any of these ranges, the carbon precursor may be sufficiently or appropriately and easily graphitized.

[0056] The metal catalyst can be Fe, Ni, Al, Mg, and / or any suitable combination thereof. The metal catalyst can have an average size (e.g., average particle size or average particle diameter) of about 5 nm to about 200 nm, about 5 nm to about 100 nm, or about 10 nm to about 50 nm. If the metal catalyst is nano-sized, the pores formed during the metal catalyst removal process can be nano-sized. The silicon positioned in the pores can be nano-sized.

[0057] If the metal catalyst has an average size within any of these ranges, silicon can be sufficiently or appropriately supported on the pores formed by the metal catalyst, thus obtaining appropriately high or improved capacity.

[0058] The carbon precursor can be biomass, resin and / or pitch, for example, lignin, polyimide resin, furan resin, phenol resin, polyvinyl alcohol resin, poly(meth)acrylic resin, polyurethane resin, cellulose resin, epoxy resin, polystyrene resin, petroleum pitch, coal pitch, mesophase pitch and / or (e.g., any suitable) combination thereof.

[0059] The mixture may be heat-treated to produce a heat-treated product. The heat-treatment process may be performed at a temperature of about 1300° C. to about 2000° C. or about 1300° C. to about 1800° C. The heat-treatment process may be performed under an inert atmosphere, wherein the inert atmosphere may be N 2 , helium, argon, and / or any suitable combination thereof.

[0060] During the heat treatment process, the carbon precursor is converted into crystalline carbon (e.g., graphite) under the influence of a catalyst, thereby producing a heat-treated product comprising crystalline carbon and a metal catalyst. During the heat treatment process, a portion of the carbon precursor may exist as hard carbon and / or soft carbon.

[0061] Subsequently, the metal catalyst is removed from the heat-treated product to prepare a crystalline carbon matrix. Through the metal catalyst removal process, pores are formed in the crystalline carbon matrix, thereby preparing a porous crystalline carbon matrix.

[0062] The metal catalyst removal process can be performed using an acid. The acid can be hydrochloric acid, nitric acid, sulfuric acid, and / or any suitable combination thereof. The metal catalyst removal process using an acid can be performed by immersing the heat-treated product in an acid.

[0063] A negative electrode active material is prepared by loading (e.g., positioning) silicon in a crystalline carbon matrix. According to this process, silicon can be loaded in the crystalline carbon matrix, for example, silicon can be positioned in pores within the crystalline carbon matrix, thereby preparing a negative electrode active material including silicon distributed in the crystalline carbon matrix.

[0064] The process of loading silicon may be performed by using silane gas and / or a silane compound. The process using silane gas may be performed in a chemical vapor deposition (CVD) method.

[0065] The silane compound may include Si, H, SiH4, and / or any suitable combination thereof. A process using the silane compound may be performed using a chemical vapor deposition (CVD) method. The CVD method may be performed under suitable conditions (e.g., for a suitable time) such that silicon comprises 1 wt% to 55 wt% of the final active material.

[0066] The prepared negative electrode active material may include a portion of the hard carbon and / or soft carbon formed during the heat treatment process.

[0067] Rechargeable lithium battery Some example embodiments provide a rechargeable lithium battery including a negative electrode including a negative electrode active material, a positive electrode, and an electrolyte.

[0068] negative electrode The negative electrode includes a current collector and a negative electrode active material layer formed on the current collector and including a negative electrode active material. The negative electrode active material layer may include a binder and may further include a conductive material.

[0069] For example, the negative electrode active material layer may include about 90 wt % to about 99 wt % of the negative electrode active material and about 1 wt % to about 10 wt % of the binder, or may include about 90 wt % to about 99 wt % of the negative electrode active material, about 0.5 wt % to about 5 wt % of the binder, and about 0.5 wt % to about 5 wt % of the conductive material.

[0070] The binder serves to adhere the negative electrode active material particles to each other and also helps the negative electrode active material adhere to the current collector. The binder can be a non-aqueous binder, an aqueous binder, a dry binder, and / or any suitable combination thereof.

[0071] The non-aqueous binder can be polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, ethylene propylene copolymer, polystyrene, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, polyamideimide, polyimide, and / or (eg, any suitable) combinations thereof.

[0072] The aqueous binder may be styrene-butadiene rubber, (meth)acrylated styrene-butadiene rubber, (meth)acrylonitrile-butadiene rubber, (meth)acrylic rubber, butyl rubber, fluororubber, polyethylene oxide, polyvinyl pyrrolidone, polyepichlorohydrin, polyphosphazene, poly(meth)acrylonitrile, ethylene propylene diene copolymer, polyvinyl pyridine, chlorosulfonated polyethylene, latex, polyester resin, (meth)acrylic resin, phenol resin, epoxy resin, polyvinyl alcohol, and / or (e.g., any suitable) combination thereof.

[0073] The aqueous binder can be a cellulose compound, and the cellulose compound can be used together with the above-mentioned aqueous binder. The cellulose compound can impart viscosity, so it can be a thickener, and because the cellulose compound can serve as a binder, it can also be a binder. Therefore, the amount of the cellulose compound can be appropriately or suitably regulated in the binder content (e.g., amount). As the cellulose compound, one or more of carboxymethyl cellulose, hydroxypropyl methylcellulose, methylcellulose and its alkali metal salt can be used in combination. The alkali metal can be Na, K and / or Li.

[0074] The dry binder may be a polymeric material capable of being in a fibrous form, and may be, for example, polytetrafluoroethylene, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, polyethylene oxide, and / or (eg, any suitable) combinations thereof.

[0075] Conductive materials (e.g., electron conductors) are used to impart conductivity to the electrodes, and any suitable conductive material can be used unless it causes undesirable chemical changes in the battery. Examples of conductive materials include: carbon-based materials such as natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fibers, carbon nanofibers, and / or carbon nanotubes; metal-based materials including copper, nickel, aluminum, and / or silver, in the form of metal powders and / or metal fibers; conductive polymers such as polyphenylene derivatives; and / or (e.g., any suitable) mixtures thereof.

[0076] The negative electrode current collector may include copper foil, nickel foil, stainless steel foil, titanium foil, nickel foam, copper foam, a polymer substrate coated with a conductive metal, and / or (eg, any suitable) combinations thereof.

[0077] positive electrode A positive electrode for a rechargeable lithium battery may include a current collector and a positive electrode active material layer on the current collector. The positive electrode active material layer may include a positive electrode active material and may further include a binder and / or a conductive material.

[0078] For example, the positive electrode may also include an additive that may function as a sacrificial positive electrode.

[0079] Based on 100 wt % of the positive electrode active material layer, the amount of the positive electrode active material may be about 90 wt % to about 99.5 wt %, and the amount of the binder or the conductive material may be about 0.5 wt % to about 5 wt %. In another embodiment, based on 100 wt % of the positive electrode active material layer, the amount of the positive electrode active material may be about 90 wt % to about 99 wt %, and the amount of the binder and the conductive material may each be about 0.5 wt % to about 5 wt %.

[0080] The positive electrode active material may be a compound capable of intercalating and deintercalating lithium (lithiated intercalation compound). For example, a composite oxide of one or more types (species) of lithium and a metal selected from cobalt, manganese, nickel, and / or one or more (e.g., any suitable) combination thereof may be used.

[0081] The composite oxide may be a lithium transition metal composite oxide, and non-limiting examples may include lithium nickel-based oxides, lithium cobalt-based oxides, lithium manganese-based oxides, lithium iron phosphate-based compounds, cobalt-free lithium nickel manganese-based oxides, and / or (eg, any suitable) combinations thereof.

[0082] As an example, a compound represented by any one of the following chemical formulas (eg, selected from 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, 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, 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, 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, 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, 0≤e≤0.1); Li a NiG b O2 (0.90≤a≤1.8, 0.001≤b≤0.1); Li a CoG b O2 (0.90≤a≤1.8, 0.001≤b≤0.1); Li a Mn 1-bG b O2 (0.90≤a≤1.8, 0.001≤b≤0.1); Li a Mn2G b O4 (0.90≤a≤1.8, 0.001≤b≤0.1); Li a Mn 1- g G g PO4 (0.90≤a≤1.8, 0≤g≤0.5); Li (3-f) Fe2(PO4)3 (0≤f≤2); and Li a FePO4 (0.90≤a≤1.8).

[0083] In the above chemical formula, A is Ni, Co, Mn and / or any suitable combination thereof; X is Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, a rare earth element and / or any suitable combination thereof; D is O, F, S, P and / or any suitable combination thereof; G is Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V and / or any suitable combination thereof; and L 1 is Mn, Al, and / or (eg, any suitable) combination thereof.

[0084] For example, the positive electrode active material can be a high nickel-based positive electrode active material having a nickel content (e.g., amount) of 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%, based on 100 mol% of metal other than lithium in the lithium transition metal composite oxide. The high nickel-based positive electrode active material can achieve a suitably high capacity and can be applied to high-capacity, high-density rechargeable lithium batteries.

[0085] The binder is used to effectively or appropriately attach the positive electrode active material particles to each other and also to effectively attach the positive electrode active material to the current collector. Examples of the binder include, but are not limited to, polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, polymers including ethylene oxide, polyvinyl pyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene-butadiene rubber, (meth)acrylated styrene-butadiene rubber, epoxy resin, (meth)acrylic resin, polyester resin, and / or nylon.

[0086] Conductive materials can be used to impart electrical conductivity (e.g., electrical conductivity) to the electrodes. Any suitable material that does not cause chemical changes (e.g., does not cause undesirable chemical changes in rechargeable lithium batteries) and that appropriately conducts electrons can be used in the battery. Examples of conductive materials include: carbon-based materials such as natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fibers, carbon nanofibers, and / or carbon nanotubes; metal-based materials including copper, nickel, aluminum, and / or silver, in the form of metal powders and / or metal fibers; conductive polymers such as polyphenylene derivatives; and / or (e.g., any suitable) mixtures thereof.

[0087] The current collector may include Al, but the present disclosure is not limited thereto.

[0088] electrolyte The electrolyte includes a non-aqueous organic solvent and a lithium salt.

[0089] The non-aqueous organic solvent serves as a medium for transporting ions participating in the electrochemical reaction of the battery.

[0090] The non-aqueous organic solvent may be a carbonate solvent, an ester solvent, an ether solvent, a ketone solvent, an alcohol solvent, an aprotic solvent, and / or (eg, any suitable) combination thereof.

[0091] The carbonate solvent may include dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), methylpropyl carbonate (MPC), ethylpropyl carbonate (EPC), ethylmethyl carbonate (MEC), ethylene carbonate (EC), propylene carbonate (PC) and / or butylene carbonate (BC).

[0092] The ester solvent may include methyl acetate, ethyl acetate, n-propyl acetate, dimethyl acetate, methyl propionate, ethyl propionate, decanoic acid lactone, mevalonolactone, valerolactone, γ-butyrolactone and / or caprolactone, etc.

[0093] Ether solvents may include dibutyl ether, tetraglyme, diglyme, dimethoxyethane, 2-methyltetrahydrofuran, 2,5-dimethyltetrahydrofuran, and / or tetrahydrofuran. Ketone solvents may include cyclohexanone, etc. Alcohol solvents may include ethanol and / or isopropanol, etc. Aprotic solvents may include nitriles such as R—CN (wherein R is a C2 to C20 linear, branched, or cyclic hydrocarbon group, or may include a double bond, an aromatic ring, or an ether group); amides such as dimethylformamide; dioxolanes such as 1,3-dioxolane and / or 1,4-dioxolane; and / or sulfolane.

[0094] The non-aqueous organic solvents may be used alone or in combination of two or more.

[0095] In addition, if a carbonate-based solvent is used, a cyclic carbonate and a chain (eg, linear) carbonate may be used in combination, and the cyclic carbonate and the chain carbonate may be mixed in a volume ratio of about 1:1 to about 1:9.

[0096] Lithium salts dissolved in organic solvents supply lithium ions in the battery, realize or promote the basic operation of rechargeable lithium batteries, and improve the transport of lithium ions between the positive electrode and the negative electrode. Examples of lithium salts may 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, LiN(C F 2x+1 SO2)(C y F 2y+2 SO2) (wherein x and y are integers of 1 to 20), one or more of lithium trifluoromethanesulfonate, lithium tetrafluoroethanesulfonate, lithium difluorobis(oxalato)phosphate (LiDFOP) and lithium di(oxalato)borate (LiBOB).

[0097] diaphragm Depending on the type of battery, the rechargeable lithium battery may further include a separator between the negative electrode and the positive electrode. Examples of suitable separator materials include polyethylene, polypropylene, polyvinylidene fluoride, and multilayers thereof, such as a polyethylene / polypropylene double-layer separator, a polyethylene / polypropylene / polyethylene triple-layer separator, and / or a polypropylene / polyethylene / polypropylene triple-layer separator.

[0098] The separator may include a porous substrate and a coating including an organic material, an inorganic material, and / or (eg, any suitable) combination thereof on one or both (eg, both) surfaces (eg, opposing surfaces) of the porous substrate.

[0099] The porous substrate may be a polymer film formed from any one of a polymer selected from polyolefins (such as polyethylene and / or polypropylene), polyesters (such as polyethylene terephthalate and / or polybutylene terephthalate), polyacetals, polyamides, polyimides, polycarbonates, polyetherketones, polyaryletherketones, polyetherimides, polyamideimides, polybenzimidazoles, polyethersulfones, polyphenylene oxides, cyclic olefin copolymers, polyphenylene sulfide, polyethylene naphthalate, glass fibers and polytetrafluoroethylene (TEFLON™), and copolymers or mixtures of two or more thereof.

[0100] The organic material may include a polyvinylidene fluoride-based polymer and / or a (meth)acrylic polymer.

[0101] The inorganic material 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 / or (e.g., any suitable) combinations thereof, but the present disclosure is not limited thereto.

[0102] An organic material and an inorganic material may be mixed in one coating layer, or a coating layer including an organic material and a coating layer including an inorganic material may be stacked.

[0103] Rechargeable lithium batteries may be classified according to their shape into cylindrical batteries, prismatic batteries, pouch batteries, and / or coin-type (or similar) batteries, etc. Figures 3 to 6 is a schematic diagram illustrating a rechargeable lithium battery according to some example embodiments. Figure 3 shows a cylindrical battery, Figure 4 shows a prismatic cell, Figure 5 and Figure 6 Pouch type battery is shown. Figures 3 to 6 , the rechargeable lithium battery 100 may include an electrode assembly 40 and a case 50, the electrode assembly 40 including a separator 30 between a positive electrode 10 and a negative electrode 20, and the electrode assembly 40 is accommodated in the case 50. The positive electrode 10, the negative electrode 20, and the separator 30 may be impregnated with an electrolyte. Figure 3 As shown in FIG, the rechargeable lithium battery 100 may include a sealing member 60 that seals the housing 50. Figure 4 In the embodiment, the rechargeable lithium battery 100 may include a positive electrode lead tab 11, a positive electrode terminal 12, a negative electrode lead tab 21, and a negative electrode terminal 22. Figure 5 and Figure 6 As shown in FIG, the rechargeable lithium battery 100 includes electrode tabs 70 including a positive electrode tab 71 and a negative electrode tab 72 serving as an electrical path for guiding current formed in the electrode assembly 40 to the outside.

[0104] A rechargeable lithium battery according to some example embodiments may be applied to automobiles, mobile phones, and / or one or more suitable types (kinds) of electronic devices, but the present disclosure is not limited thereto.

[0105] Hereinafter, examples and comparative examples of the present disclosure are described. However, these examples should not be interpreted as limiting the scope of the present disclosure in any sense.

[0106] Example 1 Lignin and Fe (average size (D50): 100 nm) were mixed in a weight ratio of 80:20 to prepare a mixture.

[0107] The mixture was heat-treated at 1500° C. under a N 2 atmosphere to prepare a heat-treated product including Fe and artificial graphite.

[0108] The heat-treated product was immersed in hydrochloric acid to prepare a porous artificial graphite matrix from which Fe was removed. In the porous graphite matrix, the pores had an average size (e.g., average diameter—here, diameter may also refer to the major axis length of the pores) of 80 nm and a porosity of 16%. The porous graphite matrix had a diameter of 6 nm. 2 / g of BET specific surface area (which was obtained from the adsorption isotherm by the BET (Brunauer, Emmet, Teller) method), and a degree of graphitization (which was obtained by measuring d002 using an X-ray diffraction analyzer (Bruker D8 Discover) in accordance with JIS K 0131-1996 to calculate (0.344-d002) / (0.344-0.3354)×100%) of 95%.

[0109] Silicon was loaded (e.g., intercalated) into the prepared porous artificial graphite matrix using a chemical vapor deposition (CVD) method (10 hours). This process produced a negative electrode active material in which silicon was distributed within the porous artificial graphite matrix. The amount of silicon in the prepared negative electrode active material was 30 wt % based on 100 wt % of the negative electrode active material. The prepared negative electrode active material had an average particle size (D50) of 10 μm, as analyzed by a particle size analyzer.

[0110] 98 wt % of a negative electrode active material, 1 wt % of carboxymethyl cellulose, and 1 wt % of styrene butadiene rubber were mixed in a water solvent to prepare a negative electrode active material layer slurry.

[0111] The negative electrode active material layer slurry was coated on a Cu foil current collector, which was then dried and pressed to fabricate a negative electrode.

[0112] A negative electrode, a lithium metal counter electrode, and an electrolyte were used to fabricate a half-cell. The electrolyte was prepared by mixing ethylene carbonate, dimethyl carbonate, and ethyl methyl carbonate (in a volume ratio of 30:40:30) and dissolving 1M LiPF6 in the mixed solvent.

[0113] Specifically, lignin and iron (Fe) particles with an average size of 100 nm were mixed in a weight ratio of 80:20. This mixture was heat-treated at 1500°C under a nitrogen atmosphere to produce a product containing Fe and artificial graphite. The product was then treated with hydrochloric acid to remove the Fe, resulting in a porous artificial graphite matrix with an average diameter of 80 nm and a porosity of 16%. This matrix had a BET surface area of ​​6 m² / g and a degree of graphitization of 95%. Silicon was then incorporated into the porous matrix using chemical vapor deposition (CVD), resulting in a negative electrode active material with 30 wt% silicon and an average particle size of 10 μm. This material was mixed with carboxymethyl cellulose and styrene butadiene rubber to form a slurry, which was then coated onto copper foil, dried, and pressed to produce the negative electrode. This electrode was used to fabricate a half-cell along with a lithium metal counter electrode and an electrolyte: a mixture of ethylene carbonate, dimethyl carbonate, and ethyl methyl carbonate with 1 M LiPF6.

[0114] Example 2 In addition to fabricating Fe with an average size (D50) of 50 nm, 2 A negative electrode active material (average particle size (D50): 10 μm) and a half-cell were manufactured in substantially the same manner as in Example 1, except for a porous artificial graphite matrix having a BET specific surface area of ​​100 μm and a graphitization degree of 95%.

[0115] Example 3 In addition to fabricating Fe with an average size (D50) of 10 nm, 2 A negative electrode active material (average particle size (D50): 10 μm) and a half-cell were manufactured in substantially the same manner as in Example 1, except for a porous artificial graphite matrix having a BET specific surface area of ​​100 μm and a graphitization degree of 95%.

[0116] Example 4 Except for the fabrication of Fe with an average size (D50) of 20 nm and changing the heat treatment temperature to 1600 °C, the Fe 2 A negative electrode active material (average particle size (D50): 10 μm) and a half-cell were manufactured in substantially the same manner as in Example 1, except for a porous artificial graphite matrix having a BET specific surface area of ​​10 μm and a graphitization degree of 99%.

[0117] Example 5 Petroleum pitch and Fe (average size (D50): 80 nm) were mixed in a weight ratio of 70:30 to prepare a mixture.

[0118] The mixture was heat-treated at 1500° C. under a N 2 atmosphere to prepare a heat-treated product including Fe and artificial graphite.

[0119] The heat-treated product was immersed in hydrochloric acid to prepare a porous artificial graphite matrix from which Fe had been removed. The porous artificial graphite matrix had pores with an average size of 43 nm and a porosity of 3%. The porosity was measured by N2 absorption isotherm using the BJH (Barret-Joyner-Halenda) method. The porous artificial graphite matrix had a porosity of 4.5 nm. 2 The material had a BET specific surface area of ​​1.25 mm / s (obtained from an adsorption isotherm by the BET (Brunauer, Emmet, Teller) method) of 1.25 mm / s and a degree of graphitization of 96% (obtained from (0.344-d002) / (0.344-0.3354)×100% by measuring d002 using an X-ray diffraction analyzer (Bruker D8 Discover) in accordance with JIS K 0131-1996).

[0120] Silicon was loaded into the prepared porous artificial graphite matrix using a CVD (chemical vapor deposition) method. This process produced a negative electrode active material in which silicon was distributed within the porous artificial graphite matrix. The prepared negative electrode active material had a silicon content (e.g., amount) of 32 wt% based on 100 wt% of the negative electrode active material. The negative electrode active material had an average particle size (D50) of 10 μm, as analyzed by a particle size analyzer.

[0121] 98 wt % of a negative electrode active material, 1 wt % of carboxymethyl cellulose, and 1 wt % of styrene butadiene rubber were mixed in a water solvent to prepare a negative electrode active material layer slurry.

[0122] The negative electrode active material layer slurry was coated on a Cu foil current collector, which was then dried and pressed to fabricate a negative electrode.

[0123] A negative electrode, a lithium metal counter electrode, and an electrolyte were used to fabricate a half-cell. The electrolyte was prepared by mixing ethylene carbonate, dimethyl carbonate, and ethyl methyl carbonate (in a volume ratio of 30:40:30) and dissolving 1M LiPF6 in the mixed solvent.

[0124] Comparative Example 1 In addition to using Fe with an average size (D50) of 250 nm and shortening the CVD time (8 h), the Fe 2 A negative electrode active material (average particle size (D50): 10 μm) and a half-cell were manufactured in substantially the same manner as in Example 1, except that the porous artificial graphite matrix had a BET specific surface area of ​​100 wt % and a graphitization degree of 95% and the silicon content (e.g., amount) was reduced to 26 wt % based on 100 wt % of the negative electrode active material.

[0125] Comparative Example 2 In addition to preparing the 8m2 A negative electrode active material (average particle size (D50): 10 μm) and a half-cell were manufactured in substantially the same manner as in Example 1, except for a porous artificial graphite matrix having a BET specific surface area of ​​100 μm and a graphitization degree of 94%.

[0126] Comparative Example 3 In addition to preparing Fe with an average size (D50) of 3 nm, 2 A porous artificial graphite matrix having a BET specific surface area of ​​100 wt % and a degree of graphitization of 94% was prepared, except that the silicon content (e.g., amount) was reduced to 10 wt % based on 100 wt % of the negative electrode active material. A negative electrode active material (average particle size (D50): 10 μm) and a half-cell were manufactured in substantially the same manner as in Example 1.

[0127] Experimental Example 1) Evaluation of pellet density 1 g of each of the negative electrode active materials according to Examples 1 to 5 and Comparative Examples 1 to 3 was placed in a mold and then maintained under a pressure of 1.5 tons for 20 seconds to manufacture pellets.

[0128] The density of the pellets was measured and the results are shown in Table 1.

[0129] Experimental Example 2) Evaluation of cycle life The half-cells according to Examples 1 to 5 and Comparative Examples 1 to 3 were each subjected to 500 cycles of charge and discharge at 0.5 C. The ratio of the 500th discharge capacity to the 1st discharge capacity was calculated. The results are shown in Table 1 as capacity retention.

[0130] Experimental Example 3) Evaluation of High-Rate Performance The half-cells according to Examples 1 to 5 and Comparative Examples 1 to 3 were charged and discharged once at 0.1C and once at 2C. The ratio of the 2C discharge capacity to the 0.1C discharge capacity was calculated. The results are shown in Table 1 as high-rate performance.

[0131] Table 1

[0132] As shown in Table 1, the examples 1 to 5 include the ones having a thickness less than or equal to 8 m. 2 Batteries with a porous artificial graphite matrix having a BET specific surface area of ​​1000 nm / g and a graphitization degree of 95% or more all meet the requirements of a capacity retention rate of 81% or more and a high rate performance of 50% or more.

[0133] Instead, including 2The battery of Comparative Example 1, which included a porous artificial graphite matrix with a BET specific surface area of ​​100 nm / g, exhibited a high-rate performance of less than 50% of that of the Example. Furthermore, the batteries according to Comparative Examples 2 and 3, which included a porous artificial graphite matrix with a graphitization degree of 94%, exhibited a capacity retention rate of less than 80% and a high-rate performance of less than 50%, i.e., both exhibited reduced capacity retention and high-rate performance compared to the Example.

[0134] In the context of the present disclosure, unless defined otherwise, the term "use" and variations thereof may be considered synonymous with the term "utilize" and variations thereof, respectively.

[0135] As used herein, expressions such as “at least one of,” “one of,” and “selected from,” when preceding or following a list of elements, modify the entire list of elements and do not modify the individual elements in the list. For example, “at least one selected from a, b, and c,” “at least one of a, b, or c,” and “at least one of a, b, and / or c” may refer to only a, only b, only c, both a and b (e.g., simultaneously), both a and c (e.g., simultaneously), both b and c (e.g., simultaneously), all of a, b, and c, or variations thereof.

[0136] As used herein, the terms "substantially," "approximately," and similar terms are used as terms of approximation rather than terms of degree, and are intended to account for the inherent variations in measured or calculated values ​​that one of ordinary skill in the art would recognize. As used herein, "approximately" or "approximately" are inclusive of the stated value and mean within an acceptable range of deviation for the particular value as determined by one of ordinary skill in the art, taking into account the measurements in question and the errors associated with the measurement of the particular quantity (i.e., the limitations of the measurement system). For example, "approximately" can mean within one or more standard deviations, or within ±30%, ±20%, ±10%, or ±5% of the stated value.

[0137] Any numerical range listed herein is intended to include all subranges of the same numerical precision contained within the listed range. For example, the range of "1.0 to 10.0" is intended to include all subranges between (and including) the listed minimum value of 1.0 and the listed 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 listed herein is intended to include all lower numerical limits contained therein, and any minimum numerical limit listed in this specification is intended to include all higher numerical limits contained therein. Therefore, the applicant reserves the right to amend this specification (including the claims) to explicitly recite any subranges contained within the ranges explicitly recited herein.

[0138] Battery manufacturing equipment, battery management system (BMS) equipment, and / or any other related equipment or components according to embodiments of the present invention described herein can be implemented using any suitable hardware, firmware (e.g., an application-specific integrated circuit), software, or a combination of software, firmware, and hardware. For example, the various components of the equipment can be formed on a single integrated circuit (IC) chip or on separate IC chips. Furthermore, the various components of the equipment can be implemented on a flexible printed circuit film, a tape carrier package (TCP), a printed circuit board (PCB), or formed on a substrate. Furthermore, the various components of the equipment can be processes or threads running on one or more processors in one or more computing devices, executing computer program instructions and interacting with other system components to perform the various functions described herein. The computer program instructions are stored in a memory, which can be implemented in the computing device using a standard memory device such as random access memory (RAM). The computer program instructions can also be stored in other non-transitory computer-readable media such as CD-ROMs, flash drives, and the like. Furthermore, those skilled in the art will recognize that the functionality of various computing devices can be combined or integrated into a single computing device, or the functionality of a particular computing device can be distributed across one or more other computing devices without departing from the scope of this disclosure.

[0139] It will be understood by those skilled in the art that, in view of the overall disclosure, each suitable feature of the various embodiments of the present disclosure may be partially or completely combined or combined with each other, and may be technically interlocked and operated in various suitable manners, and each embodiment may be implemented independently of each other or in combination with each other in any suitable manner, unless otherwise stated or implied.

[0140] While the disclosure has been described in conjunction with what are presently considered to be example embodiments, it should be understood that the disclosure is not limited to the disclosed embodiments, but on the contrary is intended to cover one or more suitable modifications and equivalent arrangements included within the spirit and scope of the appended claims and their equivalents.

Claims

1. A negative electrode active material, comprising: A crystalline carbon matrix having a thickness less than or equal to 8 m 2 / g BET specific surface area and a degree of graphitization greater than or equal to 95%; as well as Silicon is dispersed in the crystalline carbon matrix.

2. The negative electrode active material according to claim 1, wherein The BET specific surface area of ​​the crystalline carbon matrix is ​​0.5 m 2 / g to 8m 2 / g.

3. The negative electrode active material according to claim 1, wherein The silicon is nano-silicon.

4. The negative electrode active material according to claim 3, wherein The average particle size of the nano-silicon is less than or equal to 50 nm.

5. The negative electrode active material according to claim 4, wherein The average particle size of the nano-silicon is 1 nm to 40 nm.

6. The negative electrode active material according to claim 1, wherein The amount of silicon is 1 wt % to 55 wt % based on 100 wt % of the negative electrode active material.

7. The negative electrode active material according to claim 1, wherein The degree of graphitization of the crystalline carbon matrix is ​​95% to 98%.

8. The negative electrode active material according to claim 1, wherein The crystalline carbon matrix is ​​porous.

9. The negative electrode active material according to claim 8, wherein The crystalline carbon matrix has a porosity of 1% to 50%.

10. The negative electrode active material according to claim 1, wherein The negative electrode active material further includes oxygen in an amount of 0.5 wt % to 20 wt % based on 100 wt % of the negative electrode active material.

11. The negative electrode active material according to claim 1, wherein The negative electrode active material has a pellet density greater than or equal to 1.7 g / cc.

12. A method comprising: mixing a carbon precursor and a metal catalyst to prepare a mixture; heat-treating the mixture to produce a heat-treated product; removing the metal catalyst from the thermally treated product to produce a crystalline carbon matrix; as well as supporting silicon on the crystalline carbon matrix, Wherein, the method is a method for preparing negative electrode active material.

13. The method of claim 12, wherein: The metal catalyst is Fe, Ni, Al, Mg or a combination thereof.

14. The method of claim 12, wherein: The carbon precursor is at least one of biomass, resin and pitch.

15. The method of claim 12, wherein: The heat treatment is performed at a temperature of 1300°C to 2000°C.

16. The method of claim 12, wherein: The mixing ratio of the carbon precursor and the metal catalyst is 95:5 to 50:50 by weight.

17. The method of claim 12, wherein: The average particle size of the metal catalyst is 5 nm to 200 nm.

18. The method of claim 12, wherein: The removal of the metal catalyst is performed using an acid.

19. The method of claim 12, wherein: The silicon is loaded using silane gas or a silane compound.

20. A rechargeable lithium battery, comprising: A negative electrode comprising a negative electrode active material according to any one of claims 1 to 11; positive electrode; as well as electrolyte.

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