Composition for the production of graphite powder

Abstract

The present invention relates to a composition for the production of graphite powder suitable for producing high-performance lithium-ion battery anodes and other applications. The composition includes biochar, a metal, and graphite. The biochar is typically derived from the pyrolysis of woody biomass. The metal is typically a transition metal derived from the decomposition and reduction of an organometallic or inorganic metal compound. The graphite is highly crystalline and has a wide range of morphologies or structures. To produce the desired composite, the required precursors (biochar and the metal compound) are mixed and subjected to a heat treatment. The resulting well-defined composite is then subjected to other post-processing steps to obtain the final graphite powder. The resulting graphite powder has numerous industrial applications, most notably, but not limited to, in high-performance lithium-ion battery anodes.

Description

[Technical Field]

[0001] The present invention relates to a composition suitable for producing graphite powder, which is suitable for producing high-performance lithium-ion battery anodes and other applications. The composition includes biochar, a metal, and graphite. [Background technology]

[0002] Lithium-ion batteries have become ubiquitous in society, being used in everything from portable electronics to power tools to electric vehicles. The increasing utilization of lithium-ion batteries has driven development efforts to explore new and improved materials of construction to enhance performance. Additionally, certain lithium-ion battery components are in limited supply and will only become increasingly scarce as demand increases with the global transition to an electric rather than fossil fuel-based infrastructure. For these reasons, there is a concerted effort to find alternative sources of raw materials, most appropriately from renewable resources to maintain sustainability. One component in lithium-ion batteries that is in short supply is graphite.

[0003] Graphite is synthesized from petroleum-based precursors or obtained from natural deposits. Some carbon materials (such as coke and mesophase pitch) can be converted to graphite simply by heating; such materials are called graphitizable. Other carbon materials (e.g., char and some carbonized polymers) require the addition of other components to be converted to graphite [1, 2] (Non-Patent Document 1, Non-Patent Document 2). However, very specific requirements must be met for application in lithium-ion batteries. Only graphite materials with a very narrow range of properties can achieve the performance required for modern applications. Countless possibilities exist for arriving at mixtures of graphite, catalyst, and residual char. However, only a limited subset of such mixtures yield compositions suitable for further processing into graphite and ultimate use in lithium-ion batteries. [Prior art documents] [Non-patent literature]

[0004] [Non-Patent Document 1] Mochida, I., Ohtsubo, R., Takeshita, K. and Marsh, H., "Catalytic graphitization of non-graphitizable carbon by chromium and manganese oxides", Carbon, 1980, 18(2), p.117-123 [Non-patent document 2] Oya, A., Yamashita, R. and Otani, S., “Catalytic graphitization of carbons by borons”, Fuel, 1979, 58(7), p.495-500 Summary of the Invention [Problem to be solved by the invention]

[0005] Specifically, the present invention discloses compositions suitable for producing graphite powders suitable for use in commercial high-performance lithium-ion batteries. The disclosure defines the required ranges of elemental composition as well as the required ranges of relative amounts of distinguishable carbon allotropes. Furthermore, properties related to the structure and crystalline state of each of the components can be defined. [Means for solving the problem]

[0006] The present invention provides compositions comprising mixtures of biochar, metals, and graphite. Such mixtures have a unique set of properties that allow them to be processed into high-performance lithium-ion battery anode powders. The mixtures may also be processed into graphite powders for use in other applications. Methods for producing such compositions are also disclosed.

[0007] In one aspect, a composition is provided that includes a mixture of biochar, metals, and graphite. In one embodiment, the mixture has (a) a graphite content of between about 25% and about 65% by weight, (b) a metal content of between about 15% and about 75% by weight, and (c) a biochar content of between 1% and 35% by weight.

[0008] In one embodiment, the graphite has a d-spacing between about 0.3354 nm and about 0.3401 nm. In one embodiment, the electrochemical capacity of the graphite is greater than or equal to 200 mAh / g, more preferably, the electrochemical capacity of the graphite is greater than 300 mAh / g.

[0009] In one embodiment, the specific surface area of ​​the graphite is about 0.2 m 2 / g~about 50m 2 More preferably, the specific surface area of ​​the graphite is between about 20 m / g. 2 / g. In one embodiment, the graphite exhibits a "Coulombic" or first cycle efficiency of greater than 60%, more preferably greater than 80%.

[0010] In one embodiment, the graphite content in the mixture is in particulate form. In one embodiment, the metal content in the mixture is in particulate form. In one embodiment, the biochar fraction in the mixture is in particulate form.

[0011] In one embodiment, the graphite fraction, the metal fraction, and the biochar fraction are all in particulate form. In one embodiment, the mixture is a binary mixture having an elemental composition of between about 25% and about 75% carbon comprised of biochar and graphite, and between about 75% and about 25% selected metals.

[0012] In one embodiment, the biochar is derived from woody biomass heated to a temperature between about 200°C and about 1000°C. In one embodiment, the metal is a transition metal, hi one embodiment, the transition metal is selected from chromium, zirconium, molybdenum, ruthenium, rhodium, palladium, silver, cadmium, zinc, copper, nickel, cobalt, iron, manganese, chromium, vanadium, or any combination thereof.

[0013] In one embodiment, the particle size of the biochar components is less than about 1 mm. In one embodiment, the particle size of the metal component is less than about 1 mm. In one embodiment, the graphite component has a particle size of less than about 1 mm.

[0014] In one embodiment, all components have particle sizes less than 1 mm. In one embodiment, the total graphitic carbon content in the mixture is greater than about 55% by weight. In one embodiment, there is provided a method for producing a mixture as defined above, comprising the steps of: i) heat treating biomass in particulate form at a temperature between 200°C and 1000°C to form granular biochar; ii) combining the resulting biochar with a particulate metal compound in wet or dry form to form a precursor mixture; iii) heating the precursor mixture to between about 400°C and about 3000°C under inert conditions to form a graphite-containing mixture; and iv) sieving the final mixture to a particle size of less than about 1 mm to produce a mixture having (a) between about 25% and about 65% by weight of graphite, (b) between about 15% and about 75% by weight of metals, and (c) between 1% and 35% by weight of biochar.

[0015] In one embodiment, the biomass is heat treated in water in a hydrothermal process. In one embodiment, the biomass is thermally treated under inert conditions in a dry pyrolysis process.

[0016] In one embodiment, the biomass is a logging residue. In one embodiment, the biomass is sawdust. In one embodiment, the biomass is wood chips or any other wood-based material.

[0017] In one embodiment, the particles of the biomass are less than about 10 mm, hi one embodiment, the particles of the biomass are less than about 1 mm. In one embodiment, the particle size of the graphite, the metal, and the biochar are all less than about 1 mm after sieving.

[0018] In one embodiment, the method includes further steps such as, but not limited to, purifying the mixture by acid leaching (or other techniques), and washing and filtering the resulting graphite sample to high purity graphite. Additional steps may include densification or spheroidization, and carbon coating to further improve performance.

[0019] The foregoing and other aspects or advantages of the present invention may become apparent to one skilled in the art using the detailed description, images, analytical results, and performance test results provided herein. [Brief explanation of the drawings]

[0020] [Figure 1] FIG. 1 shows an image of the microwave applicator used to produce the graphite samples described herein. [Figure 2a] FIG. 10 shows an image of the placement of the sample crucible in the microwave applicator. [Figure 2b] FIG. 10 shows an image of the sample crucible at high temperature. [Figure 3] FIG. 1 shows a scanning electron image of the graphite sample produced in Example 1. [Figure 4] 1 is an XRD diffractogram of the graphite sample produced in Example 1. [Figure 5]FIG. 1 shows an image of large graphite "spheres" produced in Example 1 that were removed by sieving. [Figure 6] FIG. 1 shows a scanning electron image of the graphite sample produced in Example 2. [Figure 7] XRD diffractogram of the graphite sample produced in Example 2. [Figure 8] FIG. 1 shows a scanning electron image of the graphite sample produced in Example 3. [Figure 9] 1 is an XRD diffractogram of the graphite sample produced in Example 3. [Figure 10] FIG. 1 is an XRD diffractogram of the graphite sample referred to in Example 4. [Figure 11] FIG. 1 shows the particle size distribution of the graphite samples referred to in Example 4. [Figure 12] FIG. 1 shows the electrochemical behavior of the graphite sample referred to in Example 4. [Figure 13] XRD diffractograms of graphite samples produced in Examples 5 and 6. [Figure 14] Process diagram showing the overall conversion of biomass into graphite anode powder for lithium-ion batteries. DETAILED DESCRIPTION OF THE INVENTION

[0021] The following description sets forth numerous example configurations, parameters, etc. However, it is recognized that such description is not intended to limit the scope of the invention, but is provided as an explanation of example embodiments.

[0022] All references cited in this specification, including patents and patent applications, are hereby incorporated by reference. No admission is made that any reference constitutes prior art, nor does the discussion of any reference constitute an admission that such reference forms part of the general knowledge in the field, in New Zealand, or any other country.

[0023] definition In each instance herein, in the description, embodiments, examples, and claims, the term "comprising," "including," etc., should be read expansively and without limitation. Thus, unless the context clearly dictates otherwise, throughout the specification and claims, the words "comprise," "comprising," etc. should be interpreted in an inclusive sense as opposed to an exclusive sense, i.e., "including but not limited to."

[0024] As used herein, the article "a" or "an" is used to refer to one or to more than one (i.e., to at least one) of the grammatical object of the article. By way of example, "an element" can be interpreted to mean one element or one or more elements.

[0025] The term "about" or "approximately" is used to indicate a broader range centered around a given value, and unless otherwise clear from the context, refers to a broader range around the least significant digit, such as "about 1.1" meaning a range of 1.0 to 1.2. When the least significant digit is unclear, the term "about" refers to a factor of 2, e.g., "about X" means a value in the range of 0.5x to 2x, e.g., about 100 means a value in the range of 50 to 200. Furthermore, all ranges disclosed herein should be understood to encompass any and all subranges subsumed therein. For example, a range "less than 10" can include any and all subranges between (and including) a minimum value of zero and a maximum value of 10, i.e., any and all subranges having a minimum value of zero or greater and a maximum value of 10 or less (e.g., 1 to 4).

[0026] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure pertains. Notwithstanding that the numerical ranges and parameters setting forth broad ranges are approximations, the numerical values ​​set forth in the specific non-limiting examples are reported as precisely as possible. However, any numerical value inherently contains certain errors necessarily resulting from the standard deviation found in their respective testing measurements at the time of writing. Furthermore, unless otherwise clear from the context, numerical values ​​presented herein have an implied precision given by the first significant digit. Thus, the value 1.105 means a value between 1.0 and 1.2, while 1.105 x 10 2 The 110.5 given by means of the value 100 to 120.

[0027] As used herein, the terms "biochar" or "carbonaceous char" or "char" are used interchangeably to mean the material resulting from the pyrolysis of carbonaceous material in an inert atmosphere.

[0028] As used herein, "amorphous" means a material that does not have long- or short-range structural order, in contrast to a crystal, which has atoms arranged in the form of a regular lattice made up of repeating defined unit cells.

[0029] As used herein, "allotrope" refers to materials that have the same elemental composition (e.g., pure carbon) but different morphologies or atomic arrangements (e.g., diamond vs. graphite, or amorphous biochar / char vs. graphite).

[0030] As used herein, "thermally treated" means any heat treatment process applied to biomass at a temperature sufficient to produce biochar, including hydropyrolysis and dry pyrolysis.

[0031] As used herein, "high performance" with respect to lithium ion battery anode powders means a d spacing between 0.3354 nm and 0.3401 nm, which results in an electrochemical capacity of 200 mAh / g or greater, and a d spacing of about 0.2 m, which results in a "coulombic" efficiency or first cycle efficiency of greater than 60%. 2 / g~about 50m 2 / g.

[0032] Biochar, metal, and graphite composite The novel compositions described herein are composed of biochar, metals, and graphite. Biochar is typically derived from the pyrolysis of woody biomass. The metals are typically transition metals derived from the decomposition and reduction of organometallic or inorganic metal compounds. Graphite is highly crystalline and has a wide range of morphologies or structures. To produce the desired composite, the required precursors (biochar and metal compounds) are mixed and subjected to a heat treatment procedure at temperatures between 400°C and 3000°C for soak times between 60 seconds and 20 hours.

[0033] Typically, biochar is produced by pyrolyzing biomass starting material (such as wood chips, sawdust, forest residues or waste, or any plant-derived raw material) under an inert atmosphere (e.g., nitrogen) at temperatures between 200°C and 1000°C for periods ranging from a few seconds ("fast" pyrolysis) to several hours. Alternatively, biomass can be converted to char using a hydrothermal approach, where the char and water are placed in an autoclave at about 360°C and a pressure of about 20 MPa for the same period as pyrolysis, followed by drying. In all cases, the resulting char is composed primarily of elemental carbon, with the so-called fixed carbon content being at least greater than 40%, but more commonly greater than 60%. The remainder is composed of a set of heteroatoms (primarily hydrogen, oxygen, nitrogen, and sulfur). Furthermore, the char may contain volatiles, defined as aliphatic or aromatic hydrocarbons of sufficiently high molecular weight to not evaporate during the heat treatment. The exact composition may depend on the pyrolysis conditions and the biomass starting material selected. Such materials are conventionally referred to as "green" char.

[0034] Any of the biochar materials described can be selected for producing the precursor mixture. In some cases, the raw biomass can be used directly, which is then converted into char during a heat treatment procedure. After subjecting the precursor mixture (biochar and metal compounds) to the heat treatment procedure, the char is transformed in two ways. First, substantially all of the remaining heteroatoms and volatiles are removed, resulting in a material that is essentially carbon and has a fixed carbon content of approximately greater than 99%. Such a material is conventionally referred to as "calcined" or "fully carbonized" char. Second, the mass of carbon is reduced. Carbon acts as a reducing agent for the organometallic or inorganic metal compounds that make up part of the precursor mixture.

[0035] The metal precursor may be any one of a myriad of possible organometallic or inorganic metal compounds. The metal component of the compound is preferably a transition metal (such as, but not limited to, chromium, zirconium, molybdenum, ruthenium, rhodium, palladium, silver, cadmium, zinc, copper, nickel, cobalt, iron, manganese, chromium, vanadium, or any combination thereof). However, the metal component may also be composed of a non-transition metal (such as sodium, magnesium, potassium, calcium, tin, or lead). Upon heat treatment, most organic compounds and some inorganic compounds can decompose to form metal oxides. However, this is not a requirement; the only important prerequisite is that the original compound or the intermediate compound formed be capable of being reduced to its metallic state during the heat treatment process. Reduction is typically accomplished under an inert atmosphere in the presence of the aforementioned carbon (char) component. Such processes result in a reduction of solid mass and particle size (in most cases) due to the loss of nonmetallic elements as gases and an increase in the density of the metal relative to the compound.

[0036] A process of catalytic conversion can occur when elemental metals are exposed to a carbon source (such as char) under inert conditions at temperatures between 400°C and 3000°C. This can convert "fully carbonized" amorphous char to highly crystalline graphite over time. In doing so, it converts one allotrope of pure carbon to another. While the extent and rate of graphite formation are highly dependent on the metal selected, it is relatively insensitive to the initial selection of biomass, primarily because biomass is fully carbonized. The exact mechanism of catalytic conversion remains unclear, but two plausible hypotheses have been proposed: dissolution-precipitation and carbide formation-decomposition. In the former, a carbon source is dissolved in the metal, and graphite spontaneously precipitates due to differences in their free energy or level of structural order. In the latter, an unstable metal carbide is formed, which spontaneously decomposes to yield graphite. The exact formation mechanism is not relevant to the compositions of the present invention.

[0037] Depending on the selected heat treatment temperature and soaking time, varying amounts of char may be converted to graphite. Overall, the novel composition of the present invention can be defined by its elemental composition. Given that the biochar component is fully carbonized and contains approximately greater than 99% carbon, and that graphite is also an allotrope of pure carbon, the composite is a binary mixture with an elemental composition of between 25% and 75% carbon, with the remainder consisting of the selected pure metal (if no alloy is used).

[0038] In a second example, carbon may be subdivided into its two allotropes (i.e., residual char and formed graphite). The relative amount of graphite (as a percentage of carbon present) may be between about 55% and about 99.9% by weight, with residual char making up the remaining about 45% to about 0.1% by weight. For graphitic materials, this percentage is also known as "total graphitic carbon" or "TGC."

[0039] Although the ideal model structure of a graphite crystal is well known, actual graphitic materials rarely achieve such crystalline perfection. An important measure of crystalline imperfection is the so-called "d-spacing," i.e., the distance between the graphene layers that comprise the graphite structure. Rosalind Franklin [3] defined the interlayer spacing of non-graphitic (i.e., amorphous) carbon as 0.3440 nm, and graphite as having an interlayer spacing of 0.3354 nm. Actual graphitic materials fall somewhere in between. Depending on the conditions and the metal precursors selected, the achieved d-spacing can vary. For the new compositions under consideration, the required d-spacing may be specified as 0.3354 nm to 0.3401 nm.

[0040] In addition to the elemental composition and the form or allotrope of each component, the novel composition can be further defined by the structure of each element. During the heat treatment procedure, metal particles tend to aggregate and increase in size. For the compositions of the present invention, it is necessary that the metal particles remain below a certain critical value. Smaller particles have a higher specific surface area and are therefore more suitable for subsequent purification steps. Therefore, it is generally necessary that the particle size of all components in the mixture be less than 1 mm.

[0041] However, under certain conditions, small amounts of very large metal particles (up to several centimeters in extreme cases) may occasionally form. This may be due to factors such as ineffective atmosphere control, the selection of heating rates, and the geometry of the system. These large particles constitute only a small portion of the mixture (less than 10% by weight of the metal components). To remove them, after heat treatment, the entire composite may be screened or sieved to a particle size of 1 mm or less. If the composite contains unusual constituents, they may still be considered to be included in the compositions of the present invention, since they constitute only a small percentage of the overall distribution.

[0042] The following description of methods for preparing the aforementioned mixtures is presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the methods to the precise form disclosed. Modifications and variations are possible in light of the disclosure or may be acquired from practice of these methods.

[0043] The selected biochar and selected metal compound may be milled, if necessary, to ensure uniform distribution. The two precursors (biochar and metal component) are then mixed in a ratio of between about 0.1 wt / wt and about 10 wt / wt. This can be done under wet or dry conditions. The mixture is heated to a temperature between 400°C and 3000°C in a furnace, oven, kiln, reactor, or similar. Heating may be achieved by inductive coupling of a resistive heating element, microwave, or high-frequency electromagnetic field. The selected heating method, however, must ensure uniform heating of the entire mass of material to ensure sufficient conversion and consistent product quality throughout. Therefore, surface heating techniques such as laser or electromagnetic waves, which have limited sample penetration, are excluded. Such techniques may not achieve the high total graphitic carbon (TGC greater than 55 wt%) for the carbon component described herein as a prerequisite for such compositions. The mixture is allowed to soak in an inert atmosphere for a period between 1 minute and 20 hours. After this time, the mixture is cooled, removed from the furnace, and sieved to a particle size of less than 1 mm to produce said mixture with the desired properties.

[0044] The aforementioned properties of the mixture are desirable to achieve a final set of physical properties and performance characteristics, allowing the resulting graphite to be used as a high-performance anode in lithium-ion batteries. The composite can be further processed to enable measurement of some of these properties. One such step is the removal of metal components. The relative amount and size of the metals allow for their rapid removal using acid leaching. Small particles (less than 1 mm) allow for efficient exposure to acid, while the chosen loading of between 25% and 75% by weight ensures that leaching times are not excessive. Very high purities, exceeding 99.5% by weight carbon, can be achieved within a few hours. While rapid leaching is possible if the metal content is reduced, conversion to graphite may be incomplete, thereby compromising other battery anode properties.

[0045] For example, a priority specification for high-performance lithium-ion battery anode materials is the achievable electrochemical capacity. It has been conclusively demonstrated in the academic literature [4, 5] that a decrease in d-spacing results in a decrease in electrochemical capacity. Heat-treated char exhibits lower capacity than graphite [6], and therefore the higher the TGC, the higher the achievable capacity. High-purity, highly crystalline graphite (TGC greater than 55 wt%) derived from blends can achieve graphite capacities in excess of 200 mAh / g, and as high as 372 mAh / g, thus meeting the requirements of lithium-ion batteries.

[0046] The second critical specification for high performance lithium-ion battery anode materials is the so-called "first cycle efficiency" or "Coulombic efficiency." It has been demonstrated that "Coulombic efficiency" is directly correlated to the specific surface area of ​​the graphite powder [5]. The specific surface area depends on a wide range of factors, including the choice of biomass source. The structure and inherent porosity present in the biomass structure can, to a large extent, persist throughout the process to the graphite present in the mixture. 0.2 m 2 / g~50m 2 A graphite surface area range of 0.15 to 0.15 g / g or less is desirable to achieve satisfactory "Coulombic Efficiency." High purity, high density graphite derived from such novel mixture composition composites achieves "Coulombic Efficiency" greater than 60%, and as high as 99%, thereby meeting the requirements for lithium ion batteries.

[0047] example The examples described herein are provided for the purpose of illustrating particular embodiments of the present invention and are not intended to limit the present invention in any way. While the examples described herein are used to explain the method, it is understood that such details are for this purpose only and that variations may be made therein by those skilled in the art without departing from the spirit and scope of the overall process.

[0048] The microwave laboratory setup used to fabricate these samples can be described as follows: A custom-designed microwave applicator is used to heat the samples to temperatures up to 2000 °C at a maximum power input of 3 kW. The applicator arrangement is shown in Figure 1. The microwave generator delivers power to the applicator through a WR340 waveguide automatic matcher, a PTFE window, and a passive coupling element. The microwave generator is a 2.45 GHz YJ1600-based source (Sairem). The sample is placed in a crucible and positioned within the applicator at a specific, predetermined height, usually on a "pillar," or stand, to obtain a specific radiation distribution (see Figure 2a). The unit is sealed and purged with nitrogen gas (99.9% purity) at a high flow rate for approximately 1 hour to establish an inert atmosphere, and then a lower purge flow rate is used to maintain the inert atmosphere. After this, power is gradually applied at a rate of 30 W / min to slowly heat the sample, quickly achieving a steady state at the desired final power. A steady power setting is selected to achieve the desired temperature. The final power level is then held for a specific time period, depending on the desired result. At this point, as shown in Figure 2b, the sample is red-hot, and the crucible surface temperature can be measured through the sight glass using a handheld pyrometer. Because the pyrometer readings showed a high level of variability and uncertainty, temperature zones are reported in the applicable examples below. Power is then maintained constant for a given time frame, after which the generator is turned off and the resulting mixture sample is allowed to cool for removal.

[0049] Example 1 Pine (Pinus radiata) sawdust (50 g) was hydrothermally treated with deionized water in an autoclave at 360°C for 20 minutes. The sample was allowed to cool and then filtered using a Buchner funnel, and the resulting char was dried in a conventional oven. The dried char (17.5 g), with a carbon content of approximately 80%, was combined with 9.4 g of manganese acetate (tetrahydrate). The resulting mixture was placed in a crucible and transferred to a microwave applicator. Inert conditions were established using nitrogen gas as described above, and the power was gradually increased to 1.9 kW at a rate of approximately 30 W / min. The temperature was measured to be between 1700°C and 1900°C. The power was maintained constant for approximately 5–10 minutes, after which the power to the microwave applicator was shut off, producing the resulting mixture. After cooling, the sample was sieved to less than 1 mm to remove any large metal particles in the mixture. At this point, the composition of the mixture can be calculated as shown in Table 1. Graphite was produced by leaching the mixture overnight with 500 mL of concentrated hydrochloric acid, then washing with deionized water and filtering through a Büchner funnel. The resulting graphite was analyzed using XRD (a Bruker D8 Advance diffractometer using a 1 mm high parallel beam from a mirror with cobalt Kα radiation (weighted mean wavelength 0.1709026 nm)) and SEM (a Zeiss Ultra Plus 55 FEGSEM ultra-high-resolution field emission microscope with an in-lens detection system operating at accelerating voltages of 1 kV to 10 kV. Working distances between 1 mm and 5 mm were used, and the powder was lightly placed on carbon tape without any additional sample preparation). The XRD spectrum is shown in Figure 4. The XRD spectrum shows a d spacing of 0.3355 nm, with no peaks other than those of graphite, allowing us to conclude that the sample has a graphite (carbon) purity of over 90 wt%. Furthermore, since the XRD spectrum lacks the broad, low intensity peaks of amorphous carbon at low angles, it is possible to conclude that less than 20% of the carbon is not graphitic. The resulting graphite sample was identified and found to be 26.8 m 2The specific surface area of ​​the graphite was found to be 1 / g. The graphite structure formed is shown in Figure 3, showing large, flaky, anisotropic material with highly ordered graphite crystallites. Such experiments produced several large metal particles in the mixture, an example of which is shown in Figure 5. Table 1 - Example 1 - Composition of the mixture

[0050] [Table 1]

[0051] Based on the XRD results, it can be assumed that 80% of the carbon is graphitic, and therefore the composition of the mixture is as follows: (a) a graphite content of about 66% by weight; (b) about 18% by weight metal content, and (c) Biochar content of approximately 16 wt%.

[0052] Example 2 Pine (Radiata pine) sawdust (50 g) was hydrothermally treated with deionized water in an autoclave at 360°C for 20 minutes. The sample was allowed to cool and then filtered using a Buchner funnel. The resulting char was dried in a conventional oven. 10.1 g of dried char, approximately 80% carbon, was combined with 8.2 g of manganese acetate (tetrahydrate). The resulting mixture was placed in a crucible and transferred to a microwave applicator. Inert conditions were established, and the power was gradually increased to 1.3 kW at a rate of approximately 30 W / min. The temperature was measured to be between 1400°C and 1600°C. The power was maintained constant for approximately 5-10 minutes, after which the power was shut off. After cooling, the sample was sieved to less than 1 mm. At this point, the composition of the mixture can be calculated as shown in Table 2. The graphite was leached overnight in 500 mL of hydrochloric acid, then washed with deionized water and filtered through a Büchner funnel. The resulting graphite was analyzed using XRD (a Bruker D8 Advance diffractometer using a 1 mm high parallel beam from a mirror with cobalt Kα radiation (weighted mean wavelength 0.1709026 nm)) and SEM (a Zeiss Ultra Plus 55 FEGSEM ultra-high-resolution field emission microscope with an in-lens detection system operating at accelerating voltages of 1 kV to 10 kV. Working distances between 1 mm and 5 mm were used, and the powder was lightly placed on carbon tape without any additional sample preparation). The XRD spectrum is shown in Figure 7. The XRD spectrum shows a d spacing of 0.3392 nm, with no peaks other than those of graphite, allowing us to conclude that the sample has a graphite (carbon) purity of over 90 wt%. Furthermore, because the XRD spectrum lacks the broad, low intensity peaks of amorphous carbon at low angles, it is possible to conclude that less than 20% of the carbon is not graphitic. 2 / g。 The graphite structure formed is shown in Figure 6, showing a material with smaller, random crystallites and a more isotropic structure. Table 2 - Example 2 - Composition of the mixture

[0053] [Table 2]

[0054] Based on the XRD results, it can be assumed that 80% of the carbon is graphitic, and therefore the composition of the mixture is as follows: (a) a graphite content of about 60% by weight; (b) about 25% by weight metal content, and (c) Biochar content of approximately 15 wt%.

[0055] Example 3 Pine (Radiata pine) sawdust (50 g) was hydrothermally treated with purified water in an autoclave at 360°C for 20 minutes. The sample was allowed to cool and then filtered using a Buchner funnel. The resulting char was dried in a conventional oven. The dried char (26.7 g), with a carbon content of approximately 80%, was combined with 16.2 g of manganese acetate (tetrahydrate). The resulting mixture was placed in a crucible and transferred to a microwave applicator. Inert conditions were established, and the power was gradually increased to 1.3 kW at a rate of approximately 30 W / min. The temperature was measured to be between 1400°C and 1600°C. The power was maintained constant for approximately 30-40 minutes, after which the power was shut off. After cooling, the sample was sieved to less than 1 mm. At this point, the composition of the mixture can be calculated as shown in Table 3. This was leached overnight in 500 mL of hydrochloric acid, then washed with deionized water and filtered through a Büchner funnel. The resulting graphite was analyzed using XRD (a Bruker D8 Advance diffractometer using a 1 mm high parallel beam from a mirror with cobalt Kα radiation (weighted mean wavelength 0.1709026 nm)) and SEM (a Zeiss Ultra Plus 55 FEGSEM ultra-high-resolution field emission microscope with an in-lens detection system operating at an accelerating voltage of 1 kV to 10 kV. A working distance between 1 mm and 5 mm was used, and the powder was lightly placed on carbon tape without any additional sample preparation). The XRD spectrum is shown in Figure 9. The XRD spectrum showed a d spacing of 0.3360 nm, with no peaks other than those of graphite, allowing us to conclude that the sample had a graphite (carbon) purity of greater than 90 wt%. The graphite sample was identified and measured at 50.2 m. 2 / g。 Furthermore, because the XRD spectrum lacks the broad, low-intensity peaks of amorphous carbon at low angles, it is possible to conclude that less than 20% of the carbon is not graphitic. The structure of the graphite formed is shown in Figure 8 and shows an intermediate between flaky particles and smaller, random crystallites with a more isotropic structure. Table 3 - Example 3 - Composition of the mixture

[0056] [Table 3]

[0057] Based on the XRD results, it can be assumed that 80% of the carbon is graphitic, and therefore the composition of the mixture is as follows: (a) about 64% by weight graphite content; (b) about 20% by weight metal content, and (c) Biochar content of approximately 16 wt%.

[0058] Example 4 Graphite from several run tests under conditions similar to those described in Examples 1-3 was blended together to produce a larger sample for battery testing. This blended sample was analyzed using XRD and found to have a d-spacing of about 0.3378 nm, as shown in Figure 10. The surface area was measured to be 52.85 m 2 The average particle size was 1 / g. The particle size distribution was examined, and the material was found to have an average particle size of 29.22 μm, as demonstrated in Figure 11. The performance of lithium-ion batteries was examined as follows: Graphite was coated onto copper foil using a suitable binder. After drying, circular disks were cut using a punch and mallet. These were combined with metallic lithium foil to form coin cells. An organic electrolyte consisting of LiPF6 and ethylene carbonate was introduced under inert conditions. The coin cells were sealed and tested using a potentiostat. After testing in the CR2016 coin cells, electrochemical data were manually collected and analyzed. Figure 12 shows the first charge-discharge cycle at a constant current rate of C / 20 (C is the theoretical capacity of graphite, which is 372 mAh / g). The specific capacity obtained from the first discharge cycle for CarbonScape graphite in the half cell is 410.87 mAh / g, while the charge capacity is 275 mAh / g. This gives a first cycle efficiency or "Coloumbic" efficiency of 66.46%, thus making the graphite suitable for use in lithium-ion batteries.

[0059] Example 5 Pine (Radiata pine) sawdust (approximately 10 g) was combined with approximately 17.6 g of manganese acetate (tetrahydrate). The resulting mixture was placed in a crucible and heated in a conventional electrically heated furnace (RD WEBB Aircooled Vacuum Furnace, Model RD-G). Inert conditions were established by purging with argon gas (greater than 99.9%), and the temperature was increased at a rate of 10 °C / min. The final temperature was set at 1750 °C. The temperature was maintained constant for 180 minutes, after which the furnace was turned off. After cooling, the sample was sieved to less than 1 mm. At this point, the composition of the mixture could be calculated as shown in Table 4. It was leached overnight with 500 mL of hydrochloric acid, then washed with deionized water and filtered through a Buchner funnel. The resulting graphite was analyzed using XRD (Bruker D8 Advance diffractometer using a 1 mm high parallel beam from a mirror with cobalt Kα radiation (weighted mean wavelength 0.1709026 nm). The XRD spectrum is shown in Figure 13. Since the XRD spectrum shows a d spacing of 0.3358 nm and no peaks other than those of graphite, it can be concluded that the sample has a graphite (carbon) purity of greater than 90 wt%. Using the established correlation between d spacing and discharge capacity [5], it can be estimated that such material has an electrochemical capacity of approximately 351 mAh / g. Furthermore, since the XRD spectrum lacks the broad, low-intensity peak of amorphous carbon at low angles, it can be concluded that less than 20% of the carbon is not graphitic. The graphite sample was identified and had a d spacing of 5.439 nm. 2 / g. Using the established correlation between "Coulombic efficiency" and specific surface area [5], it can be estimated that such materials have a "Coulombic efficiency" of about 85%. Table 4 - Example 5 - Composition of the mixture

[0060] [Table 4]

[0061] Based on the XRD results, it can be assumed that 80% of the carbon is graphitic, and therefore the composition of the mixture is as follows: (a) a graphite content of about 27% by weight; (b) about 66% by weight metal content, and (c) Biochar content of approximately 7 wt.%.

[0062] Example 6 Pyrolyzed hard charcoal (approximately 10 g) from Solid Energy, New Zealand, was crushed and sieved to less than 200 μm. The char, approximately 70% carbon, was combined with approximately 6.6 g of manganese oxide. The resulting mixture was placed in a crucible and heated in a conventional electrically heated furnace (RD WEBB Aircooled Vacuum Furnace, Model RD-G). Inert conditions were established by purging with argon gas (greater than 99.9%), and the temperature was increased at a rate of 10°C / min. The final temperature was set at 1750°C. The temperature was maintained constant for 180 minutes, after which the furnace was turned off. After cooling, the sample was sieved to less than 1 mm. At this point, the composition of the mixture could be calculated as shown in Table 5. It was leached overnight with 500 mL of hydrochloric acid, then washed with deionized water and filtered through a Buchner funnel. The resulting graphite was analyzed using XRD (Bruker D8 Advance diffractometer using a 1 mm high parallel beam from a mirror with cobalt Kα radiation (weighted mean wavelength 0.1709026 nm). The XRD spectrum for the sample is also shown in Figure 13. The XRD spectrum shows a d spacing of 0.3362 nm, with no peaks other than those of graphite, so it can be concluded that the sample has a graphite (carbon) purity of greater than 90 wt%. Using the established correlation between d spacing and discharge capacity [5], it can be estimated that the material has an electrochemical capacity of approximately 346 mAh / g. Furthermore, because the XRD spectrum lacks the broad, low-intensity peak of amorphous carbon at low angles, it can be concluded that less than 20% of the carbon is not graphitic. The graphite sample was identified and only had a d spacing of 0.204 nm. 2 / g. Using the established correlation between "Coulombic efficiency" and specific surface area [5], it can be estimated that such materials have a "Coulombic efficiency" of about 96%. Table 5 - Example 6 - Composition of the mixture

[0063] [Table 5]

[0064] Based on the XRD results, it can be assumed that 80% of the carbon is graphitic, and therefore the composition of the mixture is as follows: (a) a graphite content of about 53% by weight; (b) about 34% by weight metal content, and (c) Biochar content of approximately 13 wt%.

[0065] A general outline of the overall process is shown in Figure 14, where biomass (1) in particulate form is processed to graphite powder (4) suitable for use in battery anodes. Biomass (1) is converted to biochar (2) in particulate form. Biochar (2) is then combined with metal in particulate form and heat treated to form composition (3). Composition (3), a mixture of biochar, graphite, and metal, is then used to form graphite powder (4). Graphite powder (4) is produced by processing mixture (3) as described above in the examples.

[0066] As can be seen from the examples and Figure 14, it is possible to achieve graphite powders with performance suitable for use as high-performance lithium-ion battery anode powders. Compared to conventional natural and synthetic graphites, the resulting anode powders have been found to be unique in terms of their structure and performance due to the unique starting point of the process. As a result, the achieved graphite powders exhibit a distinctive set of performance characteristics and can outperform both natural and synthetic graphite in certain lithium-ion battery applications. Additionally, the graphite of the present invention is the only material with a negative CO2 footprint, making it an environmentally friendly option.

[0067] [Table 6]

Claims

1. 1. A composition comprising a mixture of biochar, a metal, and graphite, the composition having: (a) a graphite content of between about 25% and about 65% by weight; (b) a metal content of between about 15% and about 75% by weight; and (c) a biochar content of between 1% and 35% by weight, wherein the metal is selected from chromium, zirconium, molybdenum, ruthenium, rhodium, palladium, silver, cadmium, zinc, copper, nickel, cobalt, iron, manganese, and vanadium.

2. 10. The composition of claim 1, wherein the graphite has a d-spacing between about 0.3354 nm and about 0.3401 nm.

3. The specific surface area of ​​the graphite is about 0.2 m ２ / g ~ approx. 50m ２ The composition of claim 1, wherein the .alpha.-zinc stearate is between 0.1 and 0.2g.

4. The specific surface area of ​​the graphite is about 0.5 m ２ / g ~ approx. 20m ２ The composition of claim 1, wherein the .alpha.-zinc stearate is between 0.1 and 0.2g.

5. A composition described in any one of claims 1 to 4, wherein the graphite component is in particulate form.

6. A composition described in any one of claims 1 to 5, wherein the metal component is in particulate form.

7. A composition described in any one of claims 1 to 6, wherein the biochar is in particulate form.

8. 5. The composition of claim 1, wherein the graphite fraction, the metal fraction, and the biochar fraction are all in particulate form.

9. 9. The composition of any one of claims 1 to 8, wherein the mixture is a binary mixture having an elemental composition consisting of: i) between about 25% and about 75% by weight of carbon comprised of biochar and graphite; and ii) between about 75% and about 25% by weight of the metal.

10. 10. The composition of any one of claims 1 to 9, wherein the biochar is derived from heat-treated woody biomass.

11. 11. The composition of any one of claims 1 to 10, wherein the particle size of the biochar component is less than about 1 mm.

12. The composition of any one of claims 1 to 11, wherein the particle size of the metal component is less than about 1 mm.

13. 13. The composition of any one of claims 1 to 12, wherein the graphite component has a particle size of less than about 1 mm.

14. A composition according to any one of claims 1 to 10, wherein the particle size of all components is less than 1 mm.

15. The composition of any one of claims 1 to 14, wherein the mixture has a total graphitic carbon content greater than about 55% by weight.

16. A method for producing a composition according to any one of claims 1 to 15, comprising the steps of: i) heat treating biomass in particulate form at a temperature between 200°C and 1000°C to form granular biochar; ii) combining the granular biochar with a particulate metal compound in wet or dry form to form a precursor mixture, the particulate metal compound comprising a metal selected from chromium, zirconium, molybdenum, ruthenium, rhodium, palladium, silver, cadmium, zinc, copper, nickel, cobalt, iron, manganese, and vanadium; iii) heating the precursor mixture to between about 400°C and about 3000°C under inert conditions to form a graphite-containing mixture; and iv) sieving the graphite-containing mixture to a particle size of less than about 1 mm to produce a mixture having: (a) a graphite content of between about 25% and about 65% by weight; (b) a metals content of between about 15% and about 75% by weight; and (c) a biochar content of between 1% and 35% by weight.

17. 17. The method of claim 16, wherein the biomass is heat treated in water in a hydrothermal process.

18. 17. The method of claim 16, wherein the biomass is heat treated under inert conditions in a dry pyrolysis process.

19. 19. The method of any one of claims 16 to 18, wherein the biomass is a forestry residue.

20. The method of any one of claims 16 to 18, wherein the biomass is sawdust, wood chips, or other wood-based material.

21. 21. The method of any one of claims 16 to 20, wherein the particles of biomass are less than about 10 mm.

22. 21. The method of any one of claims 16 to 20, wherein the particles of biomass are less than about 1 mm.

23. (a) a purification step; (b) washing and filtering the graphite obtained; (c) a densification step; (d) a carbon coating step; The method according to any one of claims 16 to 22, comprising one or more steps selected from:

24. 24. The method of claim 23, wherein acid leaching is used in the purification step.

25. 25. The method of claim 23 or 24, wherein spheronization is used in the densification step.

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