Composite anode material and method for making the same

Abstract

A method (10) for the production of a composite anode material, said method comprising the following method steps: (i) subjecting a graphite material (12) to a coating step (16) in which the graphite material is coated with a carbon matrix (14); (ii) feeding the product of step (i) to a shaping step (20) to produce a shaped composite material; and (iii) heat treating (22) the composite material of step (ii), thereby producing a composite anode material (48) comprising a plurality of graphite particles, the plurality of graphite particles being retained within a carbon matrix and an amorphous carbon shell being provided around the plurality of graphite particles. A composite anode material (48) is also described.

Description

Technical Field

[0001] The present invention relates to composite anode materials and methods for preparing the same. More specifically, the composite anode materials of the present invention are intended for use as anode materials in lithium ion batteries.

[0002] In a highly preferred form, the present invention further relates to a composite anode material comprising a graphite material coated by a carbon matrix around which an outer amorphous carbon shell is provided.

[0003] The present invention still further relates to a method for preparing a composite anode material as described herein. Background Art

[0004] Currently, typical methods for the manufacture of graphite anodes for use in lithium-ion batteries utilize relatively crude graphite materials having a D of, for example, greater than 10 μm. 50 The typical manufacturing process for these materials involves initial spheronization of the particles and subsequent coating. In such cases, both spheronization followed by dry or wet carbon coating methods may be used. However, to date, no industrial process is available for spheronization and dry coating of carbon particles with a D of less than 5 μm. 50 of particles.

[0005] Dry coating typically reduces the cost of production when compared to wet coating techniques (ie, typically using organic solvents).

[0006] The use of such relatively crude graphite material in the production of graphite anodes necessitates the need to reduce the size of the graphite material prior to coating, for example using a grinding step such as that required to reduce flake graphite to a size of 20 μm or less than 10 μm. This in turn increases the cost of the process when compared to processes where the size of the graphite particles would not need to be reduced.

[0007] With a D less than 5μm 50 Smaller graphite particles have previously been used in the manufacture of graphite anodes which are typically amorphous / not particularly crystalline. This characteristic makes such graphite particles generally unsuitable for use in processes for the manufacture of anodes for lithium-ion batteries. Additionally, prior art processes of this type utilize fine powders and produce flake-sized material with the fine powders which then need to be crushed. The final size or grain diameter of such processes is typically 15 to 20 μm.

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

[0009] The composite materials and methods of the present invention have as one of their objects to substantially overcome one or more of the above mentioned problems associated with prior art processes, or at least to provide a useful alternative thereto.

[0010] The foregoing discussion of the background art is intended only to facilitate understanding of the present invention. The discussion is not an acknowledgement or admission that any of the material referred to is or was ever part of the common general knowledge as at the priority date of the present application.

[0011] Throughout the specification and claims, unless the context requires otherwise, the word "comprises" or variations such as "comprises" or "comprising", will be understood to mean the inclusion of a stated integer or groups of integers but not the exclusion of any other integer or groups of integers.

[0012] Throughout the specification and claims, unless the context requires otherwise, the term "softening point" or "bitumen softening point" will be understood to mean the temperature at which bitumen flows a predetermined distance under carefully defined conditions as a result of heating, such as may be measured according to ISO 540-2:2007.

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

[0014] Throughout the specification and claims, it is understood that the term "Cg" refers to carbon in the form of graphite.

[0015] Throughout the specification and claims, unless the context requires otherwise, the term P 80 It is understood to mean the 80% cumulative pass size.

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

[0017] References throughout the specification and claims to particle surface area measurements are to be understood with reference to the BET or Bernauer-Emmett-Teller method or theory, wherein gas adsorption data are evaluated and used to generate a surface area per sample mass (m2 The specific surface area results are expressed in units of 1.1747 W / g.

[0018] It is understood that the ranges provided herein include the stated ranges and any values ​​or sub-ranges within the stated ranges. For example, a range from about 1 micrometer (μm) to about 2 μm should be understood to include not only the explicitly listed limits from 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 from about 1.1 μm to about 1.9 μm, from about 1.25 μm to about 1.75 μm, etc. In addition, when "about" and / or "substantially" are used to describe a value, it is intended to cover minor variations (up to + / - 10%) from the stated value. Summary of the invention

[0019] According to the present invention, there is provided a composite anode material comprising a graphite material coated by a carbon matrix around which an outer amorphous carbon shell is provided.

[0020] Preferably, the graphite material is a graphite material which has been coated with a carbon matrix and subsequently subjected to a shaping step. The shaping step may preferably be a spheronisation step.

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

[0022] In one form, the graphite material further comprises a D having a diameter less than about 10 μm. 50 Highly crystalline graphite.

[0023] The graphite particles are preferably in the form of flake-like crystalline graphite.

[0024] In one form of the invention, the carbon matrix is ​​pitch. The pitch is preferably about 2-15 wt % of the composite anode material.

[0025] Preferably, the composite anode material has the following D 50 :

[0026] a) about 3.5 to 5 μm; or

[0027] b) About 4.7 μm.

[0028] Preferably, the composite anode material has a 2 / g range, for example 4.4m 2 / g surface area (BET).

[0029] In one form of the invention, the purity of the graphite material is:

[0030] a) greater than about 99.92 wt % Cg; or

[0031] b) between about 99.95 and 99.97 wt % Cg.

[0032] In one form of the invention, the graphite material is provided in the form of synthetic graphite. In another form of the invention, the graphite material is provided in the form of natural graphite having a highly crystalline structure. In a further form of the invention, an alloy material may be used as a precursor to the composite anode material of the invention.

[0033] 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.

[0034] The outer layer of amorphous carbon may further include one or more oxides. The one or more oxides may preferably be in the form of 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.

[0035] Preferably, the oxide has a particle size in the range of about 20 nm to 1 μm.

[0036] 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 which may be provided within the amorphous carbon matrix.

[0037] According to the present invention, there is further provided an anode composite comprising the composite anode material as described above.

[0038] According to the present invention, there is further provided a method for producing a composite anode material, the method comprising the following method steps:

[0039] (i) subjecting a graphite material to a coating step, wherein the graphite material is coated with a carbon matrix;

[0040] (ii) sending the product of step (i) to a shaping step to produce a shaped composite material; and

[0041] (iii) heat treating the composite material of step (ii) to produce a composite anode material comprising a plurality of graphite particles held within a carbon matrix and an amorphous carbon shell provided around the plurality of graphite particles.

[0042] Preferably, the graphite material has a D 50 More preferably, the graphite material is provided in the form of graphite particles having a D of less than about 6 μm. 50 Provided in the form of graphite particles.

[0043] In one form of the invention, the carbon substrate is pitch. Preferably, the pitch is about 2-15% by weight.

[0044] Preferably, the agglomeration or coating step (i) is carried out in a mixer.

[0045] Preferably, the composite anode material has the following D 50 :

[0046] a) about 3.5 to 5 μm; or

[0047] b) About 4.7 μm.

[0048] Preferably, the composite anode material has a 2 / g, for example, about 4.4m 2 / g surface area (BET).

[0049] In one form of the invention, the purity of the graphite material is:

[0050] a) greater than about 99.92 wt % Cg; or

[0051] b) between about 99.95 and 99.97 wt % Cg.

[0052] In one form of the invention, the graphite material is provided in the form of synthetic graphite. In another form of the invention, the graphite material is provided in the form of natural graphite having a highly crystalline structure. In a further form of the invention, alloy materials may be added to the composite anode material of the invention.

[0053] 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.

[0054] The outer layer of amorphous carbon may further include one or more oxides. The one or more oxides may preferably be in the form of Al 2 O 3 、TiO 2 、ZrO2 、BaTiO 3 , MgO, CuO, ZnO, Fe 2 O 3 ,GeO 2 , Li 2 O, MnO, NiO, or zeolite, or any combination thereof.

[0055] Preferably, the oxide has a particle size in the range of about 20 nm to 1 μm.

[0056] Preferably, said heat treatment of step (iii) is provided in the form of pyrolysis.

[0057] The method of the present invention may further comprise a classification step, either before the process described above, or after the heat treatment in step (iii).

[0058] Preferably, the graphite material of step (i) is provided in the form of crystalline graphite particles.

[0059] The heat treatment of step (iii) is preferably performed at a temperature in the range of about 850°C to 1100°C.

[0060] Preferably, the heat treatment step (iii) comprises a profile of heating, maintaining at a certain temperature and cooling.

[0061] In one form, the heat treatment step (iii) comprises about 8.5 hours of heating, about 4 hours of holding at 1100° C., and about 5 to 10 hours of cooling. Preferably, once cooled, the composite anode material is at a temperature of about 100° C. More preferably, the heat treatment step (iii) has a total cycle time for the process of heating, holding at a certain temperature and cooling of between about 17 and 22 hours.

[0062] In a further form, the heat treatment step (iii) preferably comprises:

[0063] (i) heating for between about 20 and 60 hours;

[0064] (ii) heating for between about 30 and 60 hours; or

[0065] (iii) About 31.5 hours of heating.

[0066] In this form, the heat treatment step (iii) preferably has the following total cycle time for the process of heating, holding at temperature and cooling:

[0067] (i) between about 34 and 74 hours;

[0068] (ii) between about 44 and 74 hours; or

[0069] (iii) about 45.5 hours.

[0070] In one form of the invention, the heat treatment step (iii) comprises heating at a heating rate of about 2°C / minute. Preferably, the heating rate is applied at least at a temperature between about 300 and 700°C.

[0071] The method for the production of the composite anode material of the present invention may further comprise an initial classification step, wherein the graphite material is classified. In one form of the present invention, the initial classification step is performed using an air classifier.

[0072] Preferably, the graphite material is fractionated into more than one fraction, wherein the fraction below about 1 to 2 μm is cut and the remaining fractions are utilized in step (i).

[0073] More preferably, the remaining fraction is screened to remove particles larger than about 30 μm.

[0074] In one form of the invention, the graphite material is fractionated into three fractions, including a fine fraction, a medium fraction and a coarse fraction, wherein the medium fraction and the fine fraction are utilized in step (i).

[0075] The method for the production of the composite anode material of the present invention may further comprise a final sizing step. The final sizing step preferably removes any composite anode material larger than about 30 μm. BRIEF DESCRIPTION OF THE DRAWINGS

[0076] By way of example only, the invention will now be described with reference to one embodiment thereof and to the accompanying drawings, in which:

[0077] Figure 1 is a conceptual overview of a method for the production of a composite anode material according to the present invention;

[0078] Figure 2 is a schematic diagram of a flow chart of a method for the production of a composite anode material according to the present invention, showing the various process steps that may be employed;

[0079] Figure 3 is a scanning electron microscope (SEM) of the applicant's purified graphite material (99.95 wt. % Cg) at a magnification of x4,000, and its properties include d002 of 3.35, La, and Lc, and used as the graphite material of step (i) in the method of the present invention;

[0080] Figure 4Two scanning electron microscope (SEM) images (x1,000 on the left, x5,000 on the right) depicting a combination of applicant's purified graphite material and pitch as a result of the coating step of the method of the present invention;

[0081] Figure 5 two scanning electron microscope (SEM) images (x1,000 on the left, x5,000 on the right) depicting the product of the forming step of the method of the present invention; and

[0082] Figure 6 Two scanning electron microscope (SEM) images (x1,000 on the left, x10,000 on the right) of the product of the heat treatment step of the method of the present invention are depicted. DETAILED DESCRIPTION

[0083] The present invention provides a composite anode material comprising a graphite material coated by a carbon matrix around which an outer amorphous carbon shell is provided. The graphite material is a graphite material that has first been coated by a carbon matrix and then subjected to a forming step. The forming step may be a spheroidizing step.

[0084] The graphite material has 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 Provided in the form of graphite particles.

[0085] In one form of the invention, the carbon substrate is pitch. The pitch may be in the range of about 2-15 wt%, for example about 8 wt%.

[0086] The composite anode material has the following D 50 ,For example:

[0087] a) about 3.5 to 5 μm; or

[0088] b) About 4.7 μm.

[0089] The composite anode material has a temperature of about 4 to 7 m 2 / g, for example, about 4.4m 2 / g surface area (BET).

[0090] In one form of the invention, the purity of the graphite material is:

[0091] a) greater than about 99.92 wt % Cg; or

[0092] b) between about 99.95 and 99.97 wt % Cg.

[0093] In one form of the invention, the graphite material is provided in the form of synthetic graphite. In another form of the invention, the graphite material is provided in the form of natural graphite having a highly crystalline structure. In a further form of the invention, alloy materials may be added to the composite anode material of the invention.

[0094] It is contemplated that the carbon matrix may be 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.

[0095] The outer layer of amorphous carbon may further include one or more oxides. The one or more oxides may be 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 oxide has a particle size ranging from about 20 nm to 1 μm.

[0096] The composite material possesses a level of elastic properties imparted by the presence of one or more of graphite particles, graphene, few-layer graphene and graphite nanoparticles which may be provided within the amorphous carbon matrix.

[0097] The present invention further provides an anode composite comprising a composite anode material as described hereinbefore.

[0098] The present invention further provides a method for producing a composite anode material, the method comprising the following method steps:

[0099] (i) subjecting a graphite material to a coating step, wherein the graphite material is coated with a carbon matrix;

[0100] (ii) subjecting the product of step (i) to a shaping step to produce a shaped composite material; and

[0101] (iii) heat treating the composite material of step (ii) to produce a composite anode material comprising a plurality of graphite particles held within a carbon matrix and an amorphous carbon shell provided around the plurality of graphite particles.

[0102] The graphite material has 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 Provided in the form of graphite particles.

[0103] In one form of the invention, the carbon substrate is pitch. The pitch may be in the range of 2-15 wt%, for example about 8 wt%.

[0104] The agglomeration or coating step (i) is carried out in a mixer.

[0105] The composite anode material has the following D 50 ,For example:

[0106] a) about 3.5 to 5 μm; or

[0107] b) About 4.7 μm.

[0108] In one form, the composite anode material has a 2 / g, for example, about 4.4m 2 / g surface area (BET).

[0109] In a further form of the invention, the purity of the graphite material is:

[0110] a) greater than about 99.92 wt % Cg; or

[0111] b) between about 99.95 and 99.97 wt % Cg.

[0112] In one form of the invention, the graphite material is provided in the form of synthetic graphite. In another form of the invention, the graphite material is provided in the form of natural graphite having a highly crystalline structure. In a further form of the invention, alloy materials may be added to the composite anode material of the invention.

[0113] 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.

[0114] The outer layer of amorphous carbon may further include one or more oxides. The one or more oxides may be 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 oxide has a particle size in the range of about 20 nm to 1 μm.

[0115] The heat treatment of step (iii) is provided, for example, in the form of pyrolysis.

[0116] The method of the present invention may further comprise a classification step after the heat treatment in step (iii).

[0117] In one form, the graphite material of step (i) is provided in the form of pre-exfoliated graphite particles.

[0118] The heat treatment of step (iii) may be performed at a temperature in the range of about 850°C to 1100°C.

[0119] In one form, the heat treating step (iii) comprises a process of heating, maintaining at a certain temperature and cooling.

[0120] The heat treatment step (iii) includes, for example, about 8.5 hours of heating, about 4 hours of holding at 1100° C., and about 5 to 10 hours of cooling. Once cooled, the composite anode material may be at a temperature of about 100° C., and the heat treatment step (iii) has a total cycle time for the process of heating, holding at a certain temperature, and cooling between about 17 and 22 hours.

[0121] In a further form, the heat treating step (iii) comprises:

[0122] (i) heating for between about 20 and 60 hours;

[0123] (ii) heating for between about 30 and 60 hours; or

[0124] (iii) About 31.5 hours of heating.

[0125] In this further form, the heat treatment step (iii) has the following total cycle time for the process of heating, holding at temperature and cooling:

[0126] (i) between about 34 and 74 hours;

[0127] (ii) between about 44 and 74 hours; or

[0128] (iii) about 45.5 hours.

[0129] In one form of the invention, the heat treatment step (iii) comprises heating at a heating rate of about 2°C / minute. For example, the heating rate is applied at a temperature of at least about 300 to 700°C.

[0130] The method for the production of the composite anode material of the present invention may further comprise an initial classification step, wherein the graphite material is classified. In one form of the present invention, the initial classification step is performed using an air classifier.

[0131] The graphite material is fractionated into, for example, more than one fraction, wherein a fraction below about 1 to 2 μm is cut off and the remaining fraction is utilized in step (i), and the remaining fraction is screened to remove particles larger than about 30 μm.

[0132] In one form of the invention, the graphite material is fractionated into three fractions, including a fine fraction, a medium fraction and a coarse fraction, wherein the medium fraction and the fine fraction are utilized in step (i).

[0133] The method for the production of the composite anode material of the present invention may further comprise a final classification step. The final classification step is intended to remove any composite anode material larger than about 30 μm.

[0134] exist Figure 1 In the embodiment of the present invention, Figure 2 A conceptual overview of the process 10 is shown in FIG. Figure 1 , a graphite material, such as purified graphite 12 having a grade of about 99.92 to 99.95 wt. % Cg, is shown as a starting material (also referred to herein as "Talphite-C"). In an agglomeration or coating step 16, the purified graphite 12 is coated with a carbon matrix, such as pitch 14, thereby providing a carbon-coated graphite material composite 18. The coated graphite material composite 18 is sent to a forming step 20 and a heat treatment step 22, thereby providing a composite anode material 24. The composite anode material 24 has an amorphous carbon shell 26 provided therearound.

[0135] Specific reference Figure 2 If deemed necessary, the purified graphite 12 is sent to an initial classification step (not shown) by which a highly crystalline starting material can be largely ensured. An exemplary composition for the purified graphite is D 10 2.342, D 50 5.441 and D 90 11.55. This initial classification step is carried out, for example, using a machine that utilizes airflow to separate the product into three fractions, namely a fine fraction, a medium fraction and a coarse fraction. The fine fraction, for example below about 1 to 2 μm, is set aside and the coarse fraction, which is in the range of about 2 to 15 μm and has a D of less than about 10 μm and, for example, about 6 μm, is set aside. 50 The intermediate fraction and the coarse fraction are sent to the coating step 16. If any particles of 30 μm or more are present, they are screened out. Through this process, the purity of the fraction sent to the coating step 16 can be improved to about 99.97 wt% Cg.

[0136] The initial classification step can be performed, for example, using a HIPREC classifier HPC-1 Microtrac MT3300EX II commercially available from Powder Systems Co., Ltd.

[0137] exist Figure 3 , a scanning electron microscope (SEM) of a purified graphite material 12 (99.95 wt % Cg) at a magnification of x4,000 is shown, whose properties include d002 of 3.36, La of >1000, and Lc of >1000, and which is used as the graphite material in the coating step 16 just described above.

[0138] In the coating step 16, purified graphite 12 (after classification if necessary) is blended 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 provided in an amount in the range of 2-15 wt %, for example 8 wt %. Applicants understand that a pitch content toward the high end of the range of 2-15 wt % can provide improved high temperature performance for the composite anode material of the present invention.

[0139] The pitch 14 may be ground into a powder, for example, to a P of about 2 μm, before being introduced into the purified graphite 12 in the coating step 16. 80 .

[0140] The coating step 16 can be performed, for example, in a Balance Gran or Eirich mixer such as a BG-25L mixer using a 3.7 kW x 4P (rated 14.2 A) chopper and a 0.4 kW x 4P (rated 2.05 A) scraper.

[0141] Suitable conditions for carrying out the coating step 16 are CCW rpm 1150 / CW 30 rpm / 15 minute residence time / load 3.23 kg, consisting of 3 kg purified graphite 12 and 0.23 kg pitch 14 .

[0142] exist Figure 4 , two scanning electron microscope (SEM) images of a carbon-coated graphite material composite 18 are shown (x1,000 on the left, x5,000 on the right).

[0143] The carbon coated graphite material composite 18 from the coating step 16 is sent to a forming step 20 where the composite 18 is spheronized in a spheronizer such as a Nara, Newman ESSER or similar machine. Compressed air 30 and cooling water 32 are also introduced into the forming step 20. The spheronized product 34 is discharged from the spheronizer under pressure and the exhaust gas laden with the product flows into a cyclone separator where the cyclone separator underflow is discharged into a storage container.

[0144] The forming step 20 may be carried out, for example, first at room temperature in a Nara NHS-3 2L unit. It is contemplated that an NHS-5 unit may be similarly utilized. Suitable conditions for the forming step 20 are 4000 rpm / 800 gram batch / 10 minute residence time. The forming step 20 also produces a proportion of fine waste particles, which are collected in a baghouse. This proportion of fine waste particles may be in the order of 5% of the composite material 18 introduced.

[0145] In one form of the invention, the forming step 20 may be carried out at an elevated temperature. The elevated temperature is at or above the asphalt softening temperature. The asphalt softening temperature is expected to be different for different asphalts. For the asphalts employed by the applicant in test work related to the present invention, the asphalt softening temperature falls between about 110 and 250°C, and for example, 118°C and 250°C.

[0146] exist Figure 5 , two scanning electron microscope (SEM) images (x1,000 on the left, x5,000 on the right) of the spheroidized product 34 of the forming step 20 are shown.

[0147] The spheroidized product 34 is sent to a heat treatment step 22, such as a pyrolysis or carbonization process. Also introduced into the heat treatment step 22 is nitrogen 36 and cooling water 38. After carbonization, the temperature is cooled to provide a composite anode material 24 (also referred to herein as "Talnode-C").

[0148] The carbonization process may, for example, include a process of heating, maintaining at a certain temperature, and cooling. The process may include, for example, about 8.5 hours of heating, about 4 hours of maintaining at 1100° C., and about 5 to 10 hours of cooling. Once cooled, the composite anode material may be at a temperature of about 100° C., and the heat treatment step (iii) has a total cycle time for the process of heating, maintaining at a certain temperature, and cooling between about 17 and 22 hours. The flow of nitrogen 36 is, for example, at about 27 m 3 / h provided.

[0149] exist Figure 6 , two scanning electron microscope (SEM) images (x1,000 on the left, x10,000 on the right) of the composite anode material 24 product of the heat treatment step 22 are shown.

[0150] The final classification step 40 receives the composite anode material 24 from the heat treatment step 22. The final classification step 40 is performed, for example, in a magnetic filter, and compressed air 42 is provided as an input to the final classification step 40. Filtered composite anode material 44 resulting from this step 40 is sent to a packaging step 46, thereby providing a final packaged composite anode material 48.

[0151] The process of the present invention may be better understood with reference to the following non-limiting examples.

[0152] Example

[0153] Table A below provides examples of suitable purified graphite 12 for use in / as used in the process of the present invention, while Table B provides elemental analyses thereof.

[0154] Table A

[0155]

[0156]

[0157] Table B

[0158] C Al Ca Cu Fe K Mg Mn Si S element >99.9％ 3.3 7.4 7.3 26.7 5.7 2.9 0.2 <0.1 37 ppm

[0159] Table C below provides details of tests conducted in relation to the forming step 20 described above, wherein the carbon coated graphite material composite 18 had a particle size in the range of 5.9 to 6.2 μm and a mass of 443 to 503 kg / m 3 The forming step 20 was carried out in a Nara NHS-32L unit at 4000 rpm / 800 gram batch / 10 minute residence time as described above.

[0160] Table C

[0161]

[0162] It was observed that the average particle size of the spheroidized product was about 2 μm smaller than the average particle size of the carbon-coated graphite material composite 18 fed thereto, and the tap density was about 250 to 280 kg / m greater. 3 .

[0163] Additional test work was conducted to determine whether the production capacity of the Nara NHS-3 2L unit could be increased, which would allow a larger volume of material to be processed at any given time. The results indicated that the increased capacity improved spheroidization and increased tap density relative to the tests reported immediately above. These indicative results include the following:

[0164] T-3: Baseline: 800gr-10 minutes. Tap density 827gr / cc

[0165] T-14: 1200 gr - 6.5 minutes. Tap density 843 gr / cc (from Talphite-C grade)

[0166] T-18: 800 gr-7 minutes. Tap density 785 gr / cc (from Talphite-C grade)

[0167] T-19: 800gr-7 minutes. Tap density 759gr / cc

[0168] Table D below provides details of the characteristics of the composite anode materials of the present invention, including capacity testing (conducted at voltages ranging from 0.005 V to 2 V and currents of 0.1 CA).

[0169] Table D

[0170]

[0171] As can be seen from the above description, the composite anode material of the present invention and the method for producing the same are intended to allow the composite anode material to be produced from a starting graphite material of any size. Thus, while the prior art materials and methods utilize relatively coarse materials, the composite anode material of the present invention and the method for producing the same enable graphite starting materials of less than about 10 μm and in particular less than about 6 μm to be utilized. This small size of starting material was not previously considered appropriate because it was not suitable for what is understood to be conventional manufacturing processes.

[0172] Applicants appreciate that coating the graphite starting material with a carbon matrix prior to the forming step is particularly important in achieving the advantages of the present invention. Applicants' testing conducted using purified graphite material less than about 10 μm, where a forming step such as spheroidization was performed prior to the coating step, has shown that the surface area is significantly increased. For example, the surface area increase is about 4-6 m 2 / g to 50m 2 / g. Such an increase in particle surface area is undesirable when preparing anode materials.

[0173] It is contemplated that the method of the present invention allows the synthesized graphite to be a suitable graphite material. Further, it is contemplated that alloy materials, including silicon, SiO, magnesium, antimony, etc., may be introduced into the composite anode material of the present invention.

[0174] Modifications and variations such as would be apparent to a person skilled in the art are deemed to fall within the scope of the present invention.

Claims

1. A composite anode material comprising a graphite material coated by a carbon matrix around which an outer amorphous carbon shell is provided.

2. A composite anode material according to claim 1, wherein the graphite material is a graphite material which has been coated with the carbon matrix and subsequently subjected to a shaping step, the shaping step optionally being a spheroidisation step.

3. The composite anode material according to claim 1 or 2, wherein the graphite material has a D 50 The graphite particles are provided in the form of: (i) less than about 10 μm; or (ii) less than about 6 μm.

4. The composite anode material according to any one of claims 1 to 3, wherein the graphite material further comprises a D 50 Highly crystalline graphite.

5. A composite anode material according to any preceding claim, wherein the graphite particles are in the form of flake-like crystalline graphite.

6. A composite anode material according to any preceding claim, wherein the carbon matrix is ​​pitch.

7. The composite anode material of claim 6, wherein the pitch is about 2-15 wt% of the composite anode material.

8. A composite anode material according to any one of the preceding claims, wherein the composite anode material has a D 50 : (i) about 3.5 to 5 μm; or (ii) About 4.7 μm.

9. A composite anode material according to any one of the preceding claims, wherein the composite anode material has the following surface area (BET): (i) At about 4 to 7 m 2 / g; or (ii) Approximately 4.4m 2 / g.

10. A composite anode material according to any one of the preceding claims, wherein the purity of the graphite material is: (i) greater than about 99.92 wt % Cg; or (ii) between about 99.95 and 99.97 wt % Cg.

11. A composite anode material according to any preceding claim, wherein the graphite material is provided in the form of: (i) synthetic graphite; or (ii) Natural graphite with a highly crystalline structure.

12. A composite anode material according to any one of the preceding claims, wherein the alloy material is used as a precursor to the composite anode material of the invention.

13. A composite anode material according to any one of the preceding claims, wherein the carbon matrix is ​​provided in the form of: (i) an amorphous carbon matrix; (ii) a crystalline carbon matrix; or (iii) A combination of both an amorphous carbon matrix and a crystalline carbon matrix.

14. A composite anode material according to any one of the preceding claims, wherein the outer amorphous carbon shell further comprises include: (i) one or more oxides; or (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.

15. The composite anode material of claim 14, wherein the oxide has a particle size in the range of about 20 nm to 1 μm.

16. A composite anode material according to any preceding claim, wherein the composite material possesses a level of elastic properties imparted by the presence of one or more of graphite particles, graphene, few-layer graphene and graphite nanoparticles provided within the carbon matrix.

17. An anode composite comprising the composite anode material according to any one of claims 1 to 16.

18. A method for the production of a composite anode material, said method comprising the following method steps: (i) subjecting a graphite material to a coating step, wherein the graphite material is coated with a carbon matrix; (ii) sending the product of step (i) to a forming step to produce a formed composite material; and (iii) heat treating the composite material of step (ii) to produce a composite anode material comprising a plurality of graphite particles held within the carbon matrix and an amorphous carbon shell provided around the plurality of graphite particles.

19. The method according to claim 18, wherein the graphite material has a D 50 The graphite particles are provided in the form of: (i) less than about 10 μm; or (ii) less than about 6 μm.

20. The method according to claim 18 or 19, wherein the carbon substrate is: (i) bitumen; or (ii) about 2-10% by weight asphalt.

21. A process according to any one of claims 18 to 20, wherein the agglomeration or coating step (i) is carried out in a mixer.

22. The method according to any one of claims 18 to 21, wherein the composite anode material has a D 50 : (i) about 3.5 to 5 μm; or (ii) About 4.7 μm.

23. The method according to any one of claims 18 to 22, wherein the composite anode material has a surface area (BET): (i) At about 4 to 7 m 2 / g; or (ii) Approximately 4.4m 2 / g.

24. The method according to any one of claims 18 to 23, wherein the purity of the graphite material is: (i) greater than about 99.92 wt % Cg; or (ii) between about 99.95 and 99.97 wt % Cg.

25. The method according to any one of claims 18 to 24, wherein the graphite material is provided in the form of: (i) synthetic graphite; or (ii) Natural graphite with a highly crystalline structure.

26. A method according to any one of claims 18 to 25, wherein an alloying material is added to the composite anode material.

27. The method according to any one of claims 18 to 26, wherein the carbon substrate is provided in the form of: (i) an amorphous carbon matrix; (ii) a crystalline carbon matrix; or (iii) A combination of both an amorphous carbon matrix and a crystalline carbon matrix.

28. The method of any one of claims 18 to 27, wherein the outer amorphous carbon shell further include: (i) one or more oxides; or (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.

29. The method of any one of claims 18 to 28, wherein the oxide has a particle size in the range of about 20 nm to 1 μm.

30. The method according to any one of claims 18 to 29, wherein the heat treatment of step (iii) is provided in the form of pyrolysis.

31. The method of any one of claims 18 to 30, wherein the method further comprises a classification step, optionally performed using an air classifier.

32. The method according to claim 31, wherein the step of grading is provided as follows: (i) before the coating step of step (i); or (ii) after the heat treatment in step (iii).

33. A method according to any one of claims 18 to 32, wherein the graphite material of step (i) is provided in the form of crystalline graphite particles.

34. The method according to any one of claims 18 to 33, wherein the heat treatment of step (iii) is performed at a temperature in the range of about 850°C to 1100°C.

35. The method according to any one of claims 18 to 34, wherein the heat treatment step (iii) comprises a process of heating, maintaining at a certain temperature and cooling.

36. The method of claim 35, wherein the heat treatment step (iii) comprises about 8.5 hours of heating, about 4 hours of holding at 1100°C, and about 5 to 10 hours of cooling.

37. A method according to claim 35 or 36, wherein the heat treatment step (iii) has a total cycle time for the process of heating, holding at temperature and cooling of between about 17 and 22 hours.

38. The method of claim 35, wherein the heat treatment step (iii) include: (i) heating for between about 20 and 60 hours; (ii) heating for between about 30 and 60 hours; or (iii) About 31.5 hours of heating.

39. The method of claim 38, wherein the heat treatment step (iii) has the following total cycle time for heating, holding at temperature and cooling: (i) between about 34 and 74 hours; (ii) between about 44 and 74 hours; or (iii) about 45.5 hours.

40. The method of claim 38 or 39, wherein heat treating step (iii) comprises heating at a heating rate of about 2°C / min.

41. The method of claim 40, wherein a heating rate of about 2°C / min is applied at least at a temperature between about 300 and 700°C.

42. A method according to any one of claims 37 to 41, wherein once cooled, the composite anode material is at a temperature of about 100°C.

43. A method according to any one of claims 31 to 42, wherein the graphite material is fractionated into more than one fraction, wherein the fraction below about 1 to 2 μm is cut off and the remaining fractions are utilized in step (i).

44. The method of claim 43, wherein the remaining fraction is screened to remove particles larger than about 30 μm prior to use in step (i).

45. The method according to any one of claims 31 to 44, wherein the graphite material is fractionated into three fractions, including a fine fraction, a medium fraction and a coarse fraction, the medium fraction and the fine fraction being utilized in step (i).

46. ​​A method according to any one of claims 18 to 45, wherein the method further comprises a final fractionation step.

47. The method of claim 46, wherein the final sizing step removes any composite anode material larger than about 30 μm.

48. A method according to any one of claims 20 to 47, wherein the carbon substrate is pitch, and the pitch: (i) ground into a powder before being introduced into the purified graphite in the coating step; or (ii) milled to a P of about 2 μm before introduction into the purified graphite in the coating step 80 of powder.

Images