Composite negative electrode material and method for producing the same

Abstract

A method (10) for the manufacture of a composite negative electrode material, the method comprising: (i) providing a graphitic material (12) to a coating step (16) in which the graphitic material is coated by a carbon matrix (14); (ii) passing the product of step (i) to a shaping step (20) in order to produce a shaped composite material; and (iii) producing a composite negative electrode material (48) comprising a plurality of graphitic particles retained within the carbon matrix and provided with an amorphous carbon shell therearound by heat treating (22) the composite of step (ii). The composite negative electrode material (48) will also be described.

Description

Technical Field

[0001] The present invention relates to a composite negative electrode material and a method for manufacturing the same. More specifically, the composite negative electrode material of the present invention is intended for use as a negative electrode material in a lithium-ion battery.

[0002] In a very preferred embodiment, the present invention further relates to a composite negative electrode material comprising a graphite material coated with a carbon matrix and provided with an outer amorphous carbon shell around it.

[0003] The present invention further relates to a method for manufacturing the composite negative electrode material described herein.

Background Art

[0004] Currently, a typical manufacturing method for a graphite negative electrode for use in a lithium-ion battery utilizes a relatively coarse graphite material having, for example, a D 50 greater than 10 μm. A typical manufacturing process for such a material involves an initial spheroidization and subsequent coating of the particles. In such a case, a dry or wet carbon coating method can be used after spheroidization. However, to date, there is no industrial method for spheroidizing particles with a D 50 less than 5 μm and coating them dry.

[0005] Dry coating generally allows for a reduction in manufacturing costs compared to wet coating techniques (i.e., generally using organic solvents).

[0006] In the manufacture of graphite negative electrodes, using such relatively coarse graphite materials requires reducing the size of the graphite material before coating. For example, a grinding step is required to reduce flaky graphite to less than 20 μm or 10 μm. Therefore, the process cost is still higher compared to a process where it is not necessary to reduce the size of the graphite particles.

[0007] D 50Smaller graphite particles with a size of less than 5 μm have conventionally been used in the production of graphite negative electrodes, but these are generally amorphous and not particularly highly crystalline. Due to this property, such graphite particles are generally not suitable for use in the manufacturing process of negative electrodes for lithium-ion batteries. Furthermore, in this type of prior art process, fine powders are utilized, and materials of flake size that require crushing together with the fine powders are produced. The final size or particle size of such a method is typically 15 - 20 μm.

[0008] It would be advantageous if graphite materials of any particle size could be utilized as starting materials for the production of composite negative electrode materials.

[0009] One of the objectives of the composite materials and methods of the present invention is to substantially overcome one or more of the above problems associated with prior art processes or at least provide a useful alternative thereto.

[0010] The above discussion regarding the background art is only intended to facilitate the understanding of the present invention. This consideration does not admit that any of the materials mentioned was or was part of common general knowledge at the priority date of this application.

[0011] Throughout this specification and the claims, unless the context requires otherwise, the word "comprise" or variations such as "comprises" or "comprising" are understood to mean including the stated integers or groups of integers but not to mean excluding other integers or groups of integers.

[0012] Throughout this specification and the claims, unless otherwise specified in the context, the term "softening point" or "pitch softening point" is understood to refer to the temperature at which the pitch flows a predetermined distance under carefully defined conditions as a result of heating, as can be measured in accordance with ISO 540 - 2:2007.

[0013] Throughout this specification and the claims, unless otherwise specified in the context, D50 And its variations such as Dv50 are understood to refer to the median of the particle size distribution. In other words, it is the value of the particle diameter at 50% of the cumulative distribution. For example, if the D 50 of a sample is the value X, then 50% of the particles in that sample are smaller than the value X, and 50% of the particles in that sample are larger than the value X. Similarly, D 10 is the value of the particle diameter at 10% of the cumulative distribution, and D 90 is the value of the particle diameter at 90% of the cumulative distribution.

[0014] Throughout this specification and the claims, it should be understood that the term "Cg" refers to carbon in a graphitic form.

[0015] Throughout this specification and the claims, unless the context otherwise requires, the term P 80 should be understood to mean the 80% cumulative passing particle size.

[0016] As used herein with respect to the features of the present invention, the terms "relative" or "comparative" are intended to indicate a comparison with that feature in the prior art and a comparison with the typical characteristics of that feature in the prior art, unless the context clearly indicates otherwise or requires otherwise.

[0017] Throughout this specification and the claims, references to particle surface area measurements should be understood with reference to the BET method or the Brunauer-Emmett-Teller method or theory, in which gas adsorption data is evaluated and used to generate results of specific surface area expressed in units of area per mass of sample (m 2 / g).

[0018] It should be understood that the ranges provided herein include the recited range and any value or sub-range within the recited range. For example, a range of about 1 μm (micrometer) to about 2 μm includes not only the explicitly recited limits of about 1 μm to about 2 μm, but also individual values such as about 1.2 μm, about 1.5 μm, about 1.8 μm, etc., and sub-ranges such as about 1.1 μm to about 1.9 μm, about 1.25 μm to about 1.75 μm. Further, when "about" and / or "substantially" are used to describe a value, they are meant to encompass a slight variation (up to ±10%) from the recited value. Summary of the Invention Means for Solving the Problems

[0019] Disclosure of the Invention According to the present invention, there is provided a composite negative electrode material including a graphite material coated with a carbon matrix and provided with an amorphous carbon shell therearound.

[0020] Preferably, the graphite material is a graphite material coated with a carbon matrix and then subjected to a forming step. The forming step is preferably a spheroidizing step.

[0021] Preferably, the graphite material is provided in the form of graphite particles having a D of less than about 10 μm 50 More preferably, the graphite material is provided in the form of graphite particles having a D of less than about 6 μm 50

[0022] In one aspect, the graphite material further includes highly crystalline graphite having a D of less than about 10 μm 50

[0023] The graphite particles are preferably in the form of flaky crystalline graphite.

[0024] In one aspect of the present invention, the carbon matrix is pitch. The pitch is preferably about 2 to 15 wt% of the composite negative electrode material.

[0025] Preferably, the composite negative electrode material has the following D 50 . a) about 3.5 to 5 μm, or b) about 4.7 μm.

[0026] Preferably, the composite negative electrode material has a surface area (BET) in the range of about 4 to 7 m 2 / g (for example, 4.4 m 2 / g).

[0027] In one aspect of the present invention, the purity of the graphite material is as follows. a) greater than about 99.92 wt% Cg, or b) about 99.95 to 99.97 wt% Cg.

[0028] In one aspect of the present invention, the graphite material is provided in the form of artificial graphite. In another aspect of the present invention, the graphite material is provided in the form of natural graphite having a highly crystalline structure. In a further aspect of the present invention, an alloy material can be used as a precursor for the composite negative electrode material of the present invention.

[0029] Preferably, the carbon matrix is provided in the form of an amorphous carbon matrix, a crystalline carbon matrix, or a combination of both an amorphous carbon matrix and a crystalline carbon matrix.

[0030] The outer layer of the amorphous carbon may further contain one or more oxides. The one or more oxides can preferably be present in the form of Al2O3, TiO2, ZrO2, BaTiO3, MgO, CuO, ZnO, Fe2O3, GeO2, Li2O, MnO, NiO, or zeolite, or any combination thereof.

[0031] Preferably, the oxide has a particle size in the range of about 20 nm to 1 μm.

[0032] Preferably, the composite material has a level of elastic properties imparted by the presence of one or more of graphite particles, graphene, few-layer graphene, and graphite nanoparticles that can be provided inside the amorphous carbon matrix.

[0033] In accordance with the present invention, there is further provided a negative electrode composite including the above-described composite negative electrode material of the present specification.

[0034] In accordance with the present invention, there is further provided a method for manufacturing a composite negative electrode material, the method including the following method steps. (i) A step of providing a graphitic material to a coating step in which the graphitic material is coated with a carbon matrix, (ii) A step of passing the product of step (i) to a forming step to produce a formed composite, and (iii) A step of generating a composite negative electrode material including a plurality of graphitic particles retained inside the carbon matrix and provided with an amorphous carbon shell around it by heat-treating the composite of step (ii).

[0035] Preferably, the graphitic material is provided in the form of graphite particles having a D of less than about 10 μm 50 More preferably, the graphitic material is provided in the form of graphite particles having a D of less than about 6 μm 50

[0036] In one aspect of the present invention, the carbon matrix is pitch. Preferably, the pitch is about 2 to 15 wt%.

[0037] Preferably, the aggregation or coating step (i) is carried out in a mixer.

[0038] Preferably, the composite negative electrode material has the following D 50 a) about 3.5 to 5 μm, or b) about 4.7 μm.

[0039] Preferably, the composite negative electrode material is about 4 to 7 m 2 ​​ / g (for example, about 4.4 m 2 has a surface area (BET) within the range of / g).

[0040] In one embodiment of the present invention, the purity of the graphite material is as follows. a) greater than about 99.92 wt% Cg, or b) about 99.95 - 99.97 wt% Cg.

[0041] In one embodiment of the present invention, the graphite material is provided in the form of artificial graphite. In another embodiment of the present invention, the graphite material is provided in the form of natural graphite having a highly crystalline structure. In a further embodiment of the present invention, an alloy material can be added to the composite negative electrode material of the present invention.

[0042] Preferably, the carbon matrix is provided in the form of an amorphous carbon matrix, a crystalline carbon matrix, or a combination of both an amorphous carbon matrix and a crystalline carbon matrix.

[0043] The outer layer of amorphous carbon may further contain one or more oxides. The one or more oxides may preferably be present in the form of Al2O3, TiO2, ZrO2, BaTiO3, MgO, CuO, ZnO, Fe2O3, GeO2, Li2O, MnO, NiO, or zeolite, or any combination thereof.

[0044] Preferably, the oxide has a particle size within the range of about 20 nm to 1 μm.

[0045] Preferably, the heat treatment in step (iii) is provided in the form of thermal decomposition.

[0046] The method of the present invention may further include a classification step before the above steps or after the heat treatment in step (iii).

[0047] Preferably, the graphite material in step (i) is provided in the form of crystalline graphite particles.

[0048] Preferably, the heat treatment in step (iii) is carried out at a temperature in the range of about 850 °C to 1100 °C.

[0049] Preferably, the heat treatment step (iii) includes heating, temperature holding, and cooling profiles.

[0050] In one aspect, the heat treatment step (iii) includes heating for about 8.5 hours, holding at about 1100 °C for about 4 hours, and cooling for about 5 to 10 hours. Preferably, the composite negative electrode material once cooled is at a temperature of about 100 °C. More preferably, the heat treatment step (iii) has a total cycle time of about 17 to 22 hours for the heating, temperature holding, and cooling profiles.

[0051] In a further aspect, the heat treatment step (iii) preferably includes the following. (i) Heating for about 20 to 60 hours, (ii) Heating for about 30 to 60 hours, or (iii) Heating for about 31.5 hours.

[0052] In this aspect, the heat treatment step (iii) preferably has a total cycle time for the following heating, temperature holding, and cooling profiles. (i) About 34 to 74 hours, (ii) About 44 to 74 hours, or (iii) About 45.5 hours.

[0053] In one aspect of the present invention, the heat treatment step (iii) includes heating carried out at a heating rate of about 2 °C / min. Preferably, this heating rate is applied at a temperature of at least about 300 to 700 °C.

[0054] The method for manufacturing the composite negative electrode material of the present invention may further include an initial classification step of classifying the graphite material. In one aspect of the present invention, the initial classification step is carried out using an air classifier.

[0055] Preferably, the graphite material is classified into a plurality of fractions, the fraction less than about 1 to 2 μm is removed, and the remaining fractions are utilized in step (i).

[0056] More preferably, the remaining fractions are sieved to remove particles larger than about 30 μm.

[0057] In one embodiment of the present invention, the graphite material is classified into three fractions including a fine fraction, a medium fraction, and a coarse fraction, and the medium fraction and the fine fraction are utilized in step (i).

[0058] The method for manufacturing the composite negative electrode material of the present invention may further include a final classification step. The final classification step preferably removes the composite negative electrode material larger than about 30 μm.

Brief Description of the Drawings

[0059] Hereinafter, the present invention will be described only by way of example with reference to one embodiment thereof and the accompanying drawings.

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Mode for Carrying Out the Invention

[0060] Best Mode for Carrying Out the Invention The present invention provides a composite negative electrode material containing a graphite material coated with a carbon matrix, and an outer amorphous carbon shell is provided around it. The graphite material is first coated with a carbon matrix and then the graphite material is subjected to a shaping step. The shaping step may be a spheroidization step.

[0061] The graphite material may be provided in the form of graphite particles having a D of less than about 10 μm 50 For example, the graphite material is provided in the form of graphite particles having a D of less than about 6 μm 50 For example, the graphite material is provided in the form of graphite particles having a D of less than about 6 μm.

[0062] In one aspect of the present invention, the carbon matrix is pitch. The pitch may be in the range of about 2 to 15 wt%, for example, about 8 wt%.

[0063] The composite negative electrode material has, for example, the following D 50 For example, the composite negative electrode material has the following D a) about 3.5 to 5 μm, or b) about 4.7 μm.

[0064] The composite negative electrode material has a surface area (BET) in the range of about 4 to 7 m 2 / g, for example, about 4.4 m 2 / g.

[0065] In one aspect of the present invention, the purity of the graphite material is as follows. a) greater than about 99.92 wt% Cg, or b) Approximately 99.95 - 99.97 wt% Cg.

[0066] In one aspect of the present invention, the graphite material is provided in the form of artificial graphite. In another aspect of the present invention, the graphite material is provided in the form of natural graphite having a highly crystalline structure. In a further aspect of the present invention, an alloy material may be added to the composite negative electrode material of the present invention.

[0067] It is envisioned that the carbon matrix is provided in the form of an amorphous carbon matrix, a crystalline carbon matrix, or a combination of both an amorphous carbon matrix and a crystalline carbon matrix.

[0068] The outer layer of amorphous carbon may further contain one or more oxides. The one or more oxides can be present in the form of Al2O3, TiO2, ZrO2, BaTiO3, MgO, CuO, ZnO, Fe2O3, GeO2, Li2O, MnO, NiO, or zeolite, or any combination thereof. The oxide has a particle size in the range of about 20 nm to 1 μm.

[0069] The composite material has a level of elastic properties imparted by the presence of one or more of graphite particles, graphene, few-layer graphene, and graphite nanoparticles that can be provided inside the amorphous carbon matrix.

[0070] The present invention further provides a negative electrode composite including the composite negative electrode material as described above herein.

[0071] The present invention further provides a method for manufacturing a composite negative electrode material, the method including the following method steps. (i) A step of providing a graphite material to a coating step in which the graphite material is coated with a carbon matrix, (ii) A step of passing the product of step (i) to a shaping step to produce a shaped composite, and (iii) By heat-treating the composite in step (ii), a composite negative electrode material is produced that contains a plurality of graphite particles retained inside the carbon matrix and is provided with an amorphous carbon shell around it.

[0072] The graphite material is provided in the form of graphite particles having a D of less than about 10 μm. 50 For example, the graphite material is provided in the form of graphite particles having a D of less than about 6 μm. 50 For example, the graphite material is provided in the form of graphite particles having a D of less than about 6 μm.

[0073] In one aspect of the present invention, the carbon matrix is pitch. The pitch may be in the range of 2 to 15 wt%, for example, about 8 wt%.

[0074] The aggregation or coating step (i) is carried out in a mixer.

[0075] The composite negative electrode material has, for example, the following D. 50 For example, the composite negative electrode material has the following D. a) About 3.5 to 5 μm, or b) About 4.7 μm.

[0076] In one aspect, the composite negative electrode material has a surface area (BET) in the range of about 4 to 7 m 2 / g, for example, about 4.4 m 2 / g.

[0077] In a further aspect of the present invention, the purity of the graphite material is as follows. a) Greater than about 99.92 wt% Cg, or b) About 99.95 to 99.97 wt% Cg.

[0078] In one aspect of the present invention, the graphite material is provided in the form of artificial graphite. In another aspect of the present invention, the graphite material is provided in the form of natural graphite having a highly crystalline structure. In a further aspect of the present invention, an alloy material may be added to the composite negative electrode material of the present invention.

[0079] The carbon matrix is provided, for example, in the form of an amorphous carbon matrix, a crystalline carbon matrix, or a combination of both an amorphous carbon matrix and a crystalline carbon matrix.

[0080] The outer layer of amorphous carbon may further contain one or more oxides. The one or more oxides can exist in the form of Al2O3, TiO2, ZrO2, BaTiO3, MgO, CuO, ZnO, Fe2O3, GeO2, Li2O, MnO, NiO, or zeolite, or any combination thereof. The oxides have a particle size in the range of about 20 nm to 1 μm.

[0081] The heat treatment in step (iii) is provided, for example, in the form of pyrolysis.

[0082] The method of the present invention may further include a classification step following the heat treatment in step (iii).

[0083] In one aspect, the graphite material in step (i) is provided in the form of pre-exfoliated graphite particles.

[0084] The heat treatment in step (iii) may be carried out at a temperature in the range of about 850 °C to 1100 °C.

[0085] In one aspect, the heat treatment step (iii) includes a heating, temperature holding, and cooling profile.

[0086] The heat treatment step (iii) includes, for example, heating for about 8.5 hours, holding at about 1100 °C for about 4 hours, and cooling for about 5 to 10 hours. The composite negative electrode material once cooled may be at a temperature of about 100 °C, and the heat treatment step (iii) has a total cycle time of about 17 to 22 hours for the heating, temperature holding, and cooling profile.

[0087] In a further aspect, the heat treatment step (iii) includes the following. (i) Heating for about 20 to 60 hours, (ii) Heating for about 30 to 60 hours, or (iii) Heating for about 31.5 hours.

[0088] In this further aspect, the heat treatment step (iii) has the following total cycle times for the heating, temperature holding, and cooling profiles. (i) About 34 - 74 hours, (ii) About 44 - 74 hours, or (iii) About 45.5 hours.

[0089] In one aspect of the present invention, the heat treatment step (iii) includes heating carried out at a heating rate of about 2 °C / min. For example, this heating rate is applied at a temperature of at least about 300 - 700 °C.

[0090] The method for manufacturing the composite negative electrode material of the present invention may further include an initial classification step of classifying the graphite material. In one aspect of the present invention, the initial classification step is carried out using an air classifier.

[0091] The graphite material is classified, for example, into a plurality of fractions, the fraction less than about 1 - 2 μm is removed, the remaining fraction is utilized in step (i), and the remaining fraction is sieved to remove particles larger than about 30 μm.

[0092] In one aspect of the present invention, the graphite material is classified into three fractions including a fine fraction, a medium fraction, and a coarse fraction, and the medium fraction and the fine fraction are utilized in step (i).

[0093] The method for manufacturing the composite negative electrode material of the present invention may further include a final classification step. The final classification step is intended to remove any composite negative electrode material exceeding about 30 μm.

[0094] Figure 1 shows a conceptual overview of process 10 shown in Figure 2 according to the present invention. Figure 1 shows a graphite material as a starting material, for example, purified graphite 12 having a grade of about 99.92 to 99.95 wt% Cg (also referred to herein as "Talphite-C"). The purified graphite 12 is coated with a carbon matrix (e.g., pitch 14) in an agglomeration or coating step 16 to provide a graphite material composite 18 coated with carbon. The coated graphite composite 18 is passed through a shaping step 20 and a heat treatment step 22 to provide a composite negative electrode material 24. The composite negative electrode material 24 has an amorphous carbon shell 26 provided around it.

[0095] Referring to Figure 2, the purified graphite 12 is passed through an initial classification step (not shown) if considered necessary, thereby generally ensuring a starting material with high crystallinity. An exemplary composite of purified graphite has a D of 2.342 10 and a D of 5.441 50 and a D of 11.55 90 . This initial classification step divides the product into three fractions: a fine fraction, a medium fraction, and a coarse fraction, for example, using a machine that utilizes an air stream. For example, the fine fraction of about 1 to 2 μm or less is set aside, and the medium fraction and the coarse fraction are within the range of about 2 to 15 μm and have a D of about 10 μm or less (e.g., about 6 μm) 50 and are passed to the coating step 16. If particles of 30 μm or more are present, they are screened out. The purity of the fraction passed to the coating step 16 can be improved to about 99.97 wt% Cg through this step.

[0096] The initial classification step can be carried out, for example, using a HIPREC classifier (HPC-1 Microtrac MT3300EX II) commercially available from Powder Systems Co., Ltd.

[0097] Figure 3 shows a scanning electron microscope photograph (SEM) of the purified graphite material 12 at a magnification of ×4,000. Its characteristics include a d002 of 3.36, La greater than 1,000, and Lc greater than 1,000, and it is used as a graphite material in the coating step 16 described above.

[0098] In the coating step 16, if necessary, the purified graphite 12 after classification is mixed with a carbon matrix (such as pitch 14) in a mixer. Cooling water 28 is also introduced into the coating step 16. The pitch 14 is supplied in an amount within the range of 2 to 15 wt% (for example, 8 wt%). The applicant understands that a higher pitch content in the range of 2 to 15 wt% may result in improved high-temperature performance of the composite negative electrode material of the present invention.

[0099] The pitch 14 may be pulverized into a powder of, for example, about 2 μm of P 80 before being introduced into the purified graphite 12 in the coating step 16.

[0100] The coating step 16 can be carried out in a balance granulator or an Ehrlich mixer such as a BG-25L mixer using, for example, a chopper of 3.7 kW × 4P (rated 14.2 A) and a scraper of 0.4 kW × 4P (rated 2.05 A).

[0101] Suitable conditions for the coating step 16 are a CCW rotation speed of 1150 / a CW rotation speed of 30 / a residence time of 15 minutes / a load of 3.23 kg, and it is composed of 3 kg of purified graphite 12 and 0.23 kg of pitch 14.

[0102] Figure 4 shows two scanning electron microscope photograph (SEM) images (left is 1,000 times, right is 5,000 times) of the graphite material composite 18 coated with carbon.

[0103] The graphite material composite 18 coated with carbon from the coating step 16 is passed to the shaping step 20, where the composite 18 is spheroidized with a spheroidizing device (e.g., Nara, Newman ESSER or such devices). Compressed air 30 and cooling water 32 are also introduced into the shaping step 20. The spheroidized product 34 is discharged from the spheroidizing device under pressure, and the exhaust gas carrying the product flows into a cyclone, and the underflow of the cyclone is discharged into a storage container.

[0104] The shaping step 20 is initially carried out at room temperature, for example, in a Nara NHS-3 2L unit. It is assumed that the NHS-5 unit can also be used in the same way. The preferred conditions for the shaping step 20 are 4000 rpm / 800 gr batch / residence time 10 minutes. In the shaping step 20, a portion of fine waste particles that are recovered by a baghouse is also generated. This portion of the fine waste particles is about 5% of the introduced composite 18.

[0105] In one aspect of the present invention, the shaping step 20 can be carried out at a high temperature. The high temperature is above the pitch softening temperature. The pitch softening temperature is expected to vary depending on the pitch. In the test work related to the present invention, the pitch softening temperatures of the pitch adopted by the present applicants are about 110 - 250 °C, for example, 118 °C and 250 °C.

[0106] Figure 5 shows two scanning electron microscope (SEM) images (left is 1,000 times, right is 5,000 times) of the spheroidized product 34 in the shaping step 20.

[0107] The spheroidized product 34 is passed to a heat treatment step 22, for example, a pyrolysis or carbonization step. Nitrogen gas 36 and cooling water 38 are also introduced into the heat treatment step 22. After carbonization, the temperature is cooled, and the composite negative electrode material 24 (also referred to as "Talnode-C" in this specification) is obtained.

[0108] The carbonization process may include, for example, heating, temperature holding, and cooling profiles. This profile may include, for example, heating for about 8.5 hours, holding at about 1100 °C for about 4 hours, and cooling for about 5 - 10 hours. The composite negative electrode material once cooled may be at a temperature of about 100 °C, and the heat treatment step (iii) has a total cycle time of about 17 - 22 hours for the heating, temperature holding, and cooling profiles. The flow rate of nitrogen gas 36 is supplied, for example, at about 27 m 3 / h.

[0109] Figure 6 shows two scanning electron microscope (SEM) images (left at 1,000 times magnification and right at 10,000 times magnification) of the product of the composite negative electrode material 24 in the heat treatment step 22.

[0110] The final classification step 40 receives the composite negative electrode material 24 from the heat treatment step 22. The final classification step 40 is carried out, for example, in a magnetic filter, and compressed air 42 is supplied as an input to the final classification step 40. The filtered composite negative electrode material 44 is generated from this step 40 and passed to the packaging step 46, thereby obtaining the finally packaged composite negative electrode material 48.

[0111] The process of the present invention can be better understood by referring to the following non - limiting examples.

[0112] Examples Table A below provides an example of suitable purified graphite 12 used in / used as in the method of the present invention, and Table B provides its elemental analysis. [Table 1] [Table 2]

[0113] Table C below shows the details of the tests carried out for the shaping step 20 described in this specification. The graphite-based material composite 18 coated with carbon has a particle size in the range of 5.9 to 6.2 μm and a tap density of 443 to 503 kg / m 3 and is spheroidized. As described above, the shaping step 20 is carried out in a Nara NHS-3 2L unit at 4000 rpm / 800 gr batch / residence time 10 minutes.

Table 3

[0114] The average particle size of the spheroidized product is about 2 μm smaller than the average particle size of the supplied graphite-based material composite 18 coated with carbon, and the tap density is observed to be about 250 - 280 kg / m 3 greater.

[0115] Furthermore, additional tests were carried out to determine whether the processing capacity of the Nara NHS-3 2L unit could be increased, which enables processing a larger volume of material in any given period. As a result, it was shown that increasing the processing capacity compared to the tests described above improves spheroidization and increases the tap density. The resulting indicators are as follows. T-3: Basic line: 800 gr - 10 minutes. Tap density of 827 gr / cc T-14: 1200 gr - 6.5 minutes. Tap density of 843 gr / cc (from Talphite-C classification) T-18: 800 gr - 7 minutes. Tap density of 785 gr / cc (from Talphite-C classification) T-19: 800 gr - 7 minutes. Tap density of 759 gr / cc

[0116] Table D below shows the details of the characteristics of the composite negative electrode material of the present invention, including a capacity test (performed at a voltage of 0.005 V to 2 V and a current of 0.1 CA).

Table 4

[0117] As can be seen from the above description, the composite negative electrode material and its manufacturing method of the present invention are intended to enable the production of a composite negative electrode material from starting graphite materials of any size. Therefore, while coarser materials were used in the prior art materials and methods, the composite negative electrode material and its manufacturing method of the present invention can utilize graphite starting materials of less than about 10 μm, particularly less than about 6 μm. Starting materials of such a small size are not suitable for conventional manufacturing processes and have not been considered appropriate heretofore.

[0118] The applicant understands that coating the graphite starting material with a carbon matrix prior to the shaping step is particularly important in realizing the advantages of the present invention. Tests by the applicant using purified graphite materials of less than about 10 μm have shown that, for example, when a shaping step such as spheroidization is carried out prior to the coating step, the surface area increases dramatically. For example, this increase in surface area is on the order of 4 - 6 m 2 / g to 50 m 2 / g. Such an increase in particle surface area is undesirable when preparing the negative electrode material.

[0119] The method of the present invention assumes that artificial graphite is a suitable graphite material. Further, it is assumed that alloy materials containing silicon, SiO, magnesium, antimony, etc. can be incorporated into the composite negative electrode material of the present invention.

[0120] Modifications and variations as will be apparent to those skilled in the art are considered to be within the scope of the present invention.

Claims

1. A composite negative electrode material comprising graphite particles coated with a carbon matrix in the form of an outer amorphous carbon shell, The aforementioned composite negative electrode material has a diameter of approximately 3.5 to 5 μm. ５０ It has, The aforementioned graphite particles are in the form of flake-shaped crystalline graphite. Composite anode material.

2. The graphite particles are a graphite material coated with the carbon matrix and then subjected to a molding step. The molding step may optionally be a spheroidizing step. The composite anode material according to claim 1.

3. The carbon matrix is ​​pitch. The composite anode material according to claim 1.

4. The pitch is approximately 2 to 15 wt% of the composite negative electrode material. The composite anode material according to claim 3.

5. The aforementioned composite negative electrode material has a diameter of approximately 4.7 μm. ５０ Having, The composite anode material according to claim 1.

6. The aforementioned composite negative electrode material is (i) Approximately 4-7m ２ Within the range of / g, or (ii) Approximately 4.4m ２ / g Having a surface area (BET), The composite anode material according to claim 1.

7. The purity of the aforementioned graphite particles is (i) greater than approximately 99.92 wt% Cg, (ii) Approximately 99.95–99.97 wt% Cg The composite anode material according to claim 1.

8. The aforementioned outer amorphous carbon shell is further, (i) One or more oxides, (ii) Al ２ O ３ , TiO ２ , ZrO ２ , BaTiO ３ , MgO, CuO, ZnO, Fe ２ O ３ , GeO ２ , Li ２ O, MnO, NiO, or zeolite, or any combination thereof, The composite anode material according to claim 1.

9. The oxide has a particle size in the range of approximately 20 nm to 1 μm. The composite anode material according to claim 8.

10. The composite material has elastic properties of a level imparted by the presence of one or more of the graphite particles, graphene, multi-layer graphene, and graphite nanoparticles provided within the carbon matrix. The composite anode material according to claim 1.

11. A composite negative electrode material comprising the material described in any one of claims 1 to 10, Anode composite.

12. A method for manufacturing composite anode materials, The aforementioned method, (i) A coating step in which a graphite material in the form of flake-shaped crystalline graphite particles is coated with a carbon matrix, comprising the step of providing the graphite material, (ii) A step of passing the product of step (i) to a molding step in order to produce a molded composite, (iii) The step of heat-treating the composite from step (ii) to produce a composite anode material comprising a plurality of graphite particles coated with a carbon matrix in the form of amorphous carbon shells, The aforementioned composite negative electrode material has a diameter of approximately 3.5 to 5 μm. ５０ Having, method.

13. The aforementioned graphite material is (i) less than approximately 10 μm, (ii) Less than approximately 6 μm D ５０ Provided in the form of flake-like crystalline graphite particles having, The method according to claim 12.

14. The carbon matrix has a pitch of approximately 2 to 10 wt%. The method according to claim 12.

15. The coating step (i) is performed in a mixer. The method according to claim 12.

16. The aforementioned composite negative electrode material is (i) Approximately 4-7m ２ Within the range of / g, or (ii) Approximately 4.4m ２ / g Having a surface area (BET), The method according to claim 12.

17. The purity of the aforementioned graphite material is (i) greater than approximately 99.92 wt% Cg, (ii) Approximately 99.95–99.97 wt% Cg The method according to claim 12.

18. The aforementioned outer amorphous carbon shell is further, (i) One or more oxides, (ii) Al ２ O ３ , TiO ２ , ZrO ２ , BaTiO ３ , MgO, CuO, ZnO, Fe ２ O ３ , GeO ２ Li ２ It is preferable to include O, MnO, NiO, or zeolite, or any combination thereof. The oxide has a particle size in the range of approximately 20 nm to 1 μm. The method according to claim 12.

19. The heat treatment in step (iii) is provided in the form of thermal decomposition. The method according to claim 12.

20. The heat treatment in step (iii) is carried out at a temperature in the range of approximately 850°C to 1100°C. The method according to claim 12.

21. The heat treatment step (iii) includes a profile of heating, temperature holding, and cooling, The method according to claim 12.

22. The heat treatment step (iii) includes heating for about 8.5 hours, holding at about 1100°C for about 4 hours, and cooling for about 5 to 10 hours. The method according to claim 21.

23. The heat treatment step (iii) is: (i) Heating for approximately 20 to 60 hours, (ii) Heating for approximately 30 to 60 hours, or (iii) Including heating for approximately 31.5 hours, The method according to claim 21.

24. The heat treatment step (iii) is the profile of heating, temperature holding, and cooling (i) Approximately 34 to 74 hours, (ii) Approximately 44 to 74 hours, (iii) Approximately 45.5 hours Having a total cycle time, The method according to claim 22.

25. The graphite material is classified into multiple fractions, fractions smaller than approximately 1-2 μm are removed, and the remaining fraction is used in step (i). The method according to claim 12.

26. The carbon matrix is ​​pitch, The aforementioned pitch is (i) Before being introduced into the refined graphite in the coating step, the graphite is pulverized into a powder, or (ii) Before being introduced into the purified graphite in the coating step, approximately 2 μm of P ８０ It is ground into a powder having the following properties: The method according to claim 12.

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