CN114744175A

CN114744175A - Composition, graphite powder, anode powder and production method thereof

Info

Publication number: CN114744175A
Application number: CN202210417077.3A
Authority: CN
Inventors: 海因里希·巴登霍斯特
Original assignee: Carbonscape Ltd
Current assignee: Carbonscape Ltd
Priority date: 2021-04-21
Filing date: 2022-04-20
Publication date: 2022-07-12
Also published as: US20220340427A1; KR20240042582A; IL307893A; MX2023012502A; EP4079686A1; US20230017630A1; CA3214830A1; AU2021441476A1; US11518679B2; BR112023021619A2; US20240199429A1; JP2024515117A

Abstract

The invention relates to a composition, a graphite powder, an anode powder and a production method thereof. The present invention relates to a composition of matter comprising a mixture of biochar, metal, and graphite having (a) a graphite content of between about 25 and 65 weight percent, (b) a metal content of between about 15 and 75 weight percent, and (c) a biochar content of between 1 and 35 weight percent. The invention also relates to graphite powder produced from the mixture, high performance lithium ion battery anode powder produced from the mixture, and a method of producing the mixture. The invention also relates to the graphite powder produced by the method and the high-performance lithium ion battery anode powder produced by the method.

Description

Composition, graphite powder, anode powder and production method thereof

Technical Field

The invention relates to a composition, a graphite powder, an anode powder and a production method thereof. The present invention relates to compositions of matter suitable for producing graphite powder, for making high performance lithium ion battery anodes, and other applications. The composition of matter includes biochar, metal, and graphite.

Background

Lithium ion batteries have become ubiquitous in society and are used in anything from portable electronic devices to power tools to electric vehicles. The growth in utilization of lithium ion batteries has driven development to explore new and improved materials of construction to increase performance. Furthermore, certain lithium ion battery components are in limited supply and will only increase in shortage as the global demand for transition to electrical infrastructure rather than fossil fuel-based infrastructure grows. For this reason, there is a consistent effort to find alternative sources of raw materials, most suitably from renewable resources to ensure sustainability. One of the lithium ion battery components that is in short supply is graphite.

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, and such materials are referred to as graphitizable. Other carbon materials, such as carbon and some carbonised polymers, require the addition of other components to facilitate conversion to graphite [1,2 ]. For application in lithium ion batteries, however, very specific requirements have to be met. Only graphite materials with a very narrow range of properties are able to deliver the necessary properties for modern applications. There are countless possibilities to obtain a mixture of graphite, catalyst and residual char. However, only a small subset of such mixtures produce compositions of matter suitable for further processing into graphite and ultimately for use in lithium ion batteries.

The present invention specifically discloses compositions of matter suitable for producing graphite powders suitable for use in commercial, high performance lithium ion batteries. This disclosure specifies the desired ranges of relative amounts of carbon allotropes that are not only elemental compositions, but also discernible. In addition, characteristics related to the structure and crystalline state of each component are definable.

Disclosure of Invention

The present disclosure provides a composition of matter comprising a mixture of biochar, a metal, and graphite. The mixture has a unique set of characteristics that enable it to be processed into high performance lithium ion battery anode powders. The mixture can also be processed into graphite powder for other applications. Also disclosed is a process for producing the composition of matter.

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

In one embodiment, the graphite has a d-spacing of between about 0.3354 to about 0.3401 nm.

In one embodiment, the graphite has an electrochemical capacity of at least 200mAh/g, more preferably the graphite has an electrochemical capacity of greater than 300 mAh/g.

In one embodiment, the specific surface area of the graphite is from about 0.2 to about 50m²Between/g. More preferably, the specific surface area of the graphite is less than about 20m²/g。

In one embodiment, the graphite exhibits a "coulombic" or first cycle efficiency of greater than 60%, more preferably greater than 80%.

In one embodiment, the graphite content of the mixture is in particulate form.

In one embodiment, the metal content of the mixture is in the form of particles.

In one embodiment, the biochar content in the mixture is in the form of particles.

In one embodiment, the graphite, metal and biochar contents are all in particulate form.

In one embodiment, the mixture is a binary mixture having between about 25 and 75 percent carbon consisting of biochar and graphite and between about 75 and 25 percent elements of the selected metal.

In one embodiment, the biochar content is derived from woody biomass heated to a temperature between about 200 and 1000 degrees celsius.

In one embodiment, the metal is a transition metal. In 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.

In one embodiment, the biochar component has a particle size of less than about 1 millimeter.

In one embodiment, the particle size of the metal component is less than about 1 millimeter.

In one embodiment, the particle size of the graphite component is less than about 1 millimeter.

In one embodiment, all of the components have a particle size of less than 1 millimeter.

In one embodiment, the total graphitic carbon content of the mixture is greater than about 55% wt.

In one aspect, there is a method of producing a mixture as defined above, the method comprising the steps of:

i) thermally treating the biomass in particulate form at a temperature between 200 and 1000 degrees celsius to form particulate biochar;

ii) combining the resulting biochar with a particulate metal compound in wet or dry form to produce a precursor mixture;

iii) heating the precursor mixture under inert conditions to between about 400 to about 3000 degrees Celsius to form a graphite-containing mixture;

iv) sieving the final mixture to a particle size below about 1mm to produce a mixture having (a) a graphite content between about 25 to 65 weight percent, (b) a metal content between about 15 to 75 weight percent, and (c) a biochar content between 1 to 35 weight percent.

In one embodiment, the biomass is thermally treated in water in a hydrothermal step.

In one embodiment, the biomass is thermally treated under inert conditions in a dry pyrolysis step.

In one embodiment, the biomass is forestry residue.

In one embodiment, the forestry residues are sawdust.

In one embodiment, the biomass is wood chips or any other wood-based material.

In one embodiment, the biomass particles (particles) are less than about 10 mm. In one embodiment, the biomass particles are less than about 1 mm.

In one embodiment, the particle size of the graphite, metal and biochar is less than about 1 millimeter after sieving.

In one embodiment, the method includes additional steps such as, but not limited to, purification by acid leaching the mixture (or other means), washing and filtering the resulting graphite sample to high purity graphite. Additional steps may include densification or spheronization and carbon coating to further increase performance.

The foregoing and other aspects or advantages of the present invention will be apparent to those skilled in the art using the detailed description, images, analysis results, and performance test results provided in the present specification.

Drawings

Fig. 1 shows an image of a microwave applicator (microwave applicator) used to produce the graphite samples described in this specification.

Figure 2a shows an image of the sample crucible placement in the microwave applicator. Figure 2b shows an image of the sample crucible at high temperature.

Fig. 3 shows a scanning electron image of the graphite sample produced in example 1.

Figure 4 shows the XRD diffractogram of the graphite sample produced in example 1.

Figure 5 shows an image of the large graphite "balls" removed by sieving produced in example 1.

Fig. 6 shows a scanning electron image of the graphite sample produced in example 2.

Figure 7 shows the XRD diffractogram of the graphite sample produced in example 2.

Fig. 8 shows a scanning electron image of the graphite sample produced in example 3.

Figure 9 shows the XRD diffractogram of the graphite sample produced in example 3.

Fig. 10 shows an XRD diffractogram of the graphite sample referred to in example 4.

Fig. 11 shows the particle size distribution of the graphite sample referred to in example 4.

Fig. 12 shows the electrochemical behavior of the graphite sample referred to in example 4.

Figure 13 shows XRD diffractograms of the graphite samples produced in examples 5 and 6.

Fig. 14 is a process diagram showing the overall conversion of biomass to graphite anode powder for lithium ion batteries.

101 gas port

102 waveguide feed with PTFE window

103 sight glass port

104 resonant cavity

105 hinge door

106 door flange with seal

Detailed Description

The following description sets forth various exemplary configurations, parameters, and the like. It should be recognized, however, that such description is not intended as a limitation on the scope of the present invention, but is instead provided as a description of exemplary embodiments.

All references, including patents and patent applications, cited in this specification are hereby incorporated by reference. No admission is made that any reference constitutes prior art. The discussion of any reference does not constitute an admission that such reference forms part of the common general knowledge in the art, in new zealand or in any other country.

Definition of

In each case herein, the terms "comprising", "including" and the like in the specification, embodiments, examples and claims should be read expansively and without limitation. Thus, unless the context clearly requires otherwise, throughout the description and the claims, the words "comprise", "comprising", and the like are to be construed in an inclusive sense as opposed to an exclusive sense, i.e., in a sense that "includes but is not limited to".

As used herein, the articles "a" and "an" are used to refer to one or to more than one (i.e., to at least one) of the grammatical object of the article. For example, "an element" may be considered to mean one element or more than one element.

The term "about" or "approximately" is used to indicate a broad range centered at a given value, and unless otherwise clear from context, implies a broad range around the least significant bit, such as "about 1.1" implies a range from 1.0 to 1.2. The term "about" implies twice if the least significant bit is unclear, e.g., "about X" implies a value in the range of 0.5X to 2X, e.g., about 100 implies a value in the range of 50 to 200. Moreover, all ranges disclosed herein are to be understood to encompass any and all subranges subsumed therein. For example, a range of "less than 10" can include any and all subranges between (and including) the minimum value of zero and the maximum value of 10, i.e., any and all subranges having a minimum value equal to or greater than zero and a maximum value of equal to or less than 10 (e.g., 1 to 4).

Unless defined otherwise, scientific and technical terms and nomenclature used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs.

Notwithstanding that the numerical ranges and parameters setting forth the broad scope are approximations, the numerical values set forth in the specific non-limiting examples are reported as precisely as possible. Any numerical value, however, inherently contains certain errors necessarily resulting from the standard deviation found in their respective testing measurements at the time of such writing. Furthermore, unless otherwise clear from the context, the numerical values presented herein have the implied precision given by the first significant digit. Thus, a value of 1.105 means a value from 1.0 to 1.2, and from 1.105x10²A given 110.5 means a value from 100 to 120.

As used herein, the terms "biochar" or "carbonaceous char" or "char" are used interchangeably to mean a material resulting from the thermal decomposition of a carbonaceous material in an inert atmosphere.

As used herein, the term "amorphous" means a material without long-range or short-range structural ordering, as opposed to a crystal having a regular lattice form with an atomic arrangement composed of repeats defining a unit cell.

As used herein, the term "allotrope" means a material having the same elemental composition, such as pure carbon, for example, but with a different form or atomic configuration, e.g., diamond and graphite or amorphous biochar/char and graphite.

As used herein, the term "thermal treatment" means any thermal treatment process applied to biomass at a temperature sufficient to produce biochar, including hydrothermal and dry pyrolysis.

As used herein, the term "high performance" with respect to a lithium ion battery anode powder means a graphite powder having a d-spacing between 0.3354 to 0.3401nm, which results in an electrochemical capacity of at least 200mAh/g and about 0.2 to 50m²A specific surface area between/g, which results in a "coulomb" or first cycle efficiency of more than 60%.

Composite material of biochar, metal and graphite

The novel composition of matter described in this specification is comprised of biochar, metal, and graphite. Biochar is typically derived from the pyrolysis of woody biomass. The metal is generally a transition metal derived from the decomposition and reduction of an organic or inorganic metal compound. Graphite is highly crystalline and has a wide range of morphologies or structures. For the production of the composite material of interest, the desired precursors (biochar and metal compound) are mixed and subjected to a heat treatment procedure at a temperature between 400 and 3000 degrees celsius for a soaking period of between 60 seconds and 20 hours.

Typically, biochar is produced by pyrolyzing biomass starting materials, such as wood chips, sawdust, forestry residues or waste, or any plant-derived feedstock, under an inert atmosphere (e.g., nitrogen) at temperatures between 200 and 1000 degrees celsius for a period of time ranging from a few seconds ("fast" pyrolysis) to several hours. Alternatively, hydrothermal processes can be used to convert biomass into char. Here, the char and water may be placed in an autoclave at about 360 degrees celsius and a pressure of about 200 bar for the same period of time as pyrolysis, followed by drying. In all cases, the resulting char consists essentially of elemental carbon, with a so-called fixed carbon content of greater than at least 40%, but more typically greater than 60%. The remainder is made up of a group of heteroatoms, primarily hydrogen, oxygen, nitrogen and sulfur. Furthermore, the char may contain volatile substances defined as aliphatic or aromatic hydrocarbons, which have a sufficiently high molecular weight to not be vaporized during the heat treatment. The exact composition will depend on the pyrolysis conditions and biomass starting material selected. This material is conventionally referred to as "green" carbon.

Any of the described biochar materials can be selected for use in producing the aforementioned precursor mixtures. It is even possible to use the raw biomass directly, which is then converted into char during the heat treatment procedure. After subjecting the precursor mixture (biochar and metal compound) to the described heat treatment procedure, the carbon is changed in two ways. First, almost all residual heteroatoms and volatile species are removed, resulting in a material that is almost entirely carbon and has a fixed carbon content of over-99%. This material is conventionally referred to as "calcined" or "fully carbonized" carbon. Second, the carbon mass has decreased. The carbon acts as a reducing agent for the organic or inorganic metal compounds that form part of the precursor mixture.

The metal precursor can be any of a myriad of possible organic 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 non-transition metals, such as: sodium, magnesium, potassium, calcium, tin, lead, and others. After heat treatment, most organic compounds and some inorganic compounds will undergo decomposition to form metal oxides. However, this is not a requirement, but rather the only key prerequisite is that the original compound or one or more of the formed intermediate compounds can be reduced to its metallic state during the heat treatment process. The reduction is usually effected in the presence of the aforementioned carbon (char) component under an inert atmosphere. This process results in a reduction in the solid mass and particle size due to the loss of non-metallic elements as a gas and the increase in the density of the metal relative to the compound (in most cases).

The process of catalytic conversion will occur when elemental metal is exposed to a carbon source such as carbon at temperatures between 400 and 3000 degrees celsius under inert conditions. In this way, "fully carbonized" amorphous carbon will convert over time to highly crystalline graphite. In doing so, one allotrope of pure carbon is converted to another. The extent and rate of formation of graphite is highly dependent on the metal selected but is relatively insensitive to the original choice of biomass, primarily because the biomass is fully carbonized. The exact mechanism of catalytic conversion is still unknown, but two plausible theories have been proposed, namely dissolution-precipitation and carbide formation-decomposition. In the former, due to differences in their levels of free energy or structural ordering, the carbon source dissolves in the metal and graphite precipitates spontaneously. In the latter, unstable metal carbides are formed, which spontaneously decompose to produce graphite. The exact mechanism of formation is not relevant to the present composition of matter.

Depending on the selected heat treatment temperature and soaking time, different amounts of carbon will be converted to graphite. In general, the novel compositions of matter may be defined in terms of their elemental compositions. In view of the fact that the biocarbon component is fully carbonized to contain over-99% carbon and that graphite is also an allotrope of pure carbon, the composite material is a binary mixture having a carbon between 25 and 75 percent and a distinct elemental composition consisting of the selected pure metal (when no alloy is used).

In the second case, carbon can be subdivided into its two allotropes, namely carbon residue and formed graphite. The relative amount of graphite (as a percentage of carbon present) can be between about 55 to about 99.9% wt with carbon residue constituting the remainder, about 45% to about 0.1% wt. For graphite materials, this percentage is also referred to as "total graphitic carbon" or "TGC".

While the ideal model structure of graphite crystals is well known, true graphite materials rarely achieve such crystalline integrity. A key indicator of crystalline defects is the so-called "d-spacing" or interlayer distance of graphene layers comprising graphite structures. Rosaled Franklin [3] defines a non-graphitic (i.e., amorphous) carbon with an interlayer spacing of 0.3440nm and graphite with an interlayer spacing of 0.3354 nm. The actual graphite material falls somewhere in between. Depending on the conditions chosen and the metal precursor chosen, the d-spacing obtained will vary. For the novel compositions of matter under consideration, the required d-spacing may be specified as 0.3354nm to 0.3401 nm.

In addition to the elemental composition and the form or allotrope of the various components, the novel composition of matter may be further defined in terms of the structure of the various elements. During the heat treatment procedure, the metal particles tend to agglomerate and increase in size. For the present compositions of matter, it is necessary that these remain below a certain critical value. Due to the higher specific surface area, smaller particles are more suitable for the subsequent purification step. Thus, generally, the particle size of all components in the mixture needs to be less than 1 mm.

However, under certain conditions, small amounts of very large metal particles, in extreme cases up to several centimeters, can sometimes be formed. This may be due to factors such as inefficient atmospheric control, selection of heating rates, system geometry, etc. These large particles constitute only a very small fraction (< 10% wt of metal components) of the mixture. To remove this, the entire composite material may be screened or sieved after heat treatment to a particle size of 1mm or less. If the composite includes these abnormal formations, it will still be considered to fall within the present composition of matter, as they constitute only a small fraction of the overall distribution.

The following description of the process for producing the above mixture is presented for purposes of illustration and description. It is not exhaustive and does not limit the process to the precise form disclosed. Modifications and variations are possible in light of the present disclosure or may be acquired from practice of the methods.

The selected biochar and the selected metal compound may be milled (if desired) to ensure uniform distribution. The two precursors (biochar and metal components) are then mixed in a ratio between about 0.1 and about 10 wt/wt. This can be done under wet or dry conditions. The mixture is heated in a furnace, oven, kiln, reactor vessel or the like to a temperature between 400 and 3000 degrees celsius. Heating may be achieved by electrical resistance heating elements, inductive coupling of microwaves or high frequency electromagnetic fields. However, the heating method chosen must ensure uniform heating of the bulk material mass to ensure adequate conversion and consistent product quality throughout the process. Thus, surface heating techniques such as lasers or electromagnetic waves with limited sample penetration are excluded. Such a technique would not achieve high total graphitic carbon for the carbon component (TGC > 55% wt), which is specified herein as a requirement for the composition of matter. The mixture is soaked under an inert atmosphere for a period of time between 1 minute and 20 hours. After this time, the mixture was cooled, removed from the furnace and sieved to a particle size of less than 1mm to produce the mixture with the desired characteristics.

The characteristics of the aforementioned mixtures are desirable to obtain a final set of physical and performance characteristics such that the resulting graphite is used as a high performance anode in lithium ion batteries. The composite material may be further processed to enable some of these characteristics to be measured. One such step is the removal of the metal component. The relative amount and size of the metal allows for its rapid removal using acid leaching. Small particles (<1mm) enable efficient exposure to acid, while a selective substance loading between 25 and 75% wt ensures that the leaching time does not become excessive. Very high purity in excess of 99.5% wt carbon can be achieved within hours. If the metal content is reduced, rapid leaching is also possible, but conversion to graphite will be insufficient, thus compromising other battery anode characteristics.

For example, a preferred specification for high performance lithium ion battery anode materials is the achievable electrochemical capacity. It has been confirmed in academic documents [4,5] that a decrease in d-spacing leads to a decrease in electrochemical capacity. Thermally treated carbons exhibit lower capacities than graphite [6], so the higher the TGC, the higher the capacity achieved. High purity, highly crystalline graphite derived from the mixture (TGC > 55% wt) can achieve graphite capacities in excess of 200mAh/g and up to 372mAh/g, thus meeting the demand for lithium ion batteries.

A second key specification for high performance lithium ion battery anode materials is the so-called "first cycle efficiency" or "coulombic efficiency". It has been demonstrated that "Coulomb efficiency"directly related to the specific surface area of graphite powder [5]. The specific surface area depends on a wide range of factors, including the choice of the source of the biomass. The structure and inherent porosity present in the biomass structure will, to a large extent, persist throughout the process until graphite is present in the mixture. 0.2 to 50m²Graphite surface area ranges of/g or less are desirable to achieve acceptable "coulombic efficiency". The high purity, high density graphite derived from the novel mixture composition of matter composites has achieved "coulombic efficiencies" of greater than 60% and up to 99%, thus meeting the requirements of lithium ion batteries.

Examples

The examples described herein are provided for the purpose of illustrating specific embodiments of the invention and are not intended to limit the invention in any way. Although the embodiments described herein have been used to describe methods, it is understood that such detail is solely for that purpose and that variations can be made therein by those skilled in the art without departing from the spirit and scope of the overall method.

The microwave laboratory setup used to produce these samples can be described as follows. The samples were heated to a temperature of up to 2000 ℃ using a custom designed microwave applicator with a maximum power input of 3 kW. The applicator assembly is shown in fig. 1. The microwave generator delivers power to the applicator through the WR340 waveguide autotuner, PTFE window and passive coupling element. The microwave generator was a 2.45GHz YJ1600 base source (Sairem). The sample is placed in the crucible and positioned in an applicator, typically on a "column" or rack, at a predetermined height to obtain a specific radiation profile (see fig. 2 a). The unit was sealed and purged with nitrogen (99.9% pure) at a high flow rate for approximately 1 hour to establish an inert atmosphere, and then maintained using a lower purge flow rate. After this, power was applied gradually at a rate of 30W/min to slowly warm the sample and quickly reach steady state for the desired final power. The stable power setting is selected to achieve the desired temperature. The final power level is then maintained for a specified time depending on the desired result. At this time, the sample emitted red light, and the crucible surface temperature was measured through a sight glass using a hand-held pyrometer, as shown in FIG. 2 b. The pyrometer readings demonstrate high levels of fluctuation and uncertainty, and therefore, the temperature bands are reported in the examples applicable below. The power was then maintained steady for a given time frame, after which the generator was turned off and the resulting mixture sample was allowed to cool for removal.

Example 1

Sawdust (50g) from pine tree (pinus radiata) was hydrothermally treated with deionized water in an autoclave at a temperature of 360 degrees celsius for 20 min. The sample was allowed to cool and then filtered using a Buchner funnel (Buchner tunnel); the resulting char was dried in a conventional oven. Dry charcoal (17.5g) having a carbon content of about 80% was combined with 9.4g of manganese acetate (tetrahydrate). The resulting mixture was placed in a crucible and transferred to a microwave applicator. Inert conditions were established using nitrogen as described above and the power was gradually increased to 1.9kW at a rate of approximately 30W/min. The measurement temperature is between 1700-1900 degrees celsius. The power is maintained steady for about 5 to 10 minutes, after which the microwave applicator is powered off to produce the resulting mixture. Once cooled, the sample was sieved below 1mm to remove some large metal particles in the mixture, at which point the mixture composition can be calculated as shown in table 1. It was then leached overnight with 500ml of concentrated hydrochloric acid, followed by washing with deionized water and filtration on a buchner funnel to yield graphite. The resulting graphite was analyzed using: XRD (Bruker D8 Advance diffractometer using a 1mm highly parallel cobalt K alpha radiation beam with a mirror source (mirror-derived), weighted average wavelength of 1.709026 angstroms) and SEM (using an Ultra-high resolution field emission microscope: Zeiss Ultra Plus 55FEGSEM, equipped with an in-lens detection system, operating at an accelerating voltage of 1 to 10 kV. use a working distance of between 1 and 5mm and deposit the powder gently on carbon tape without any further sample preparation). The XRD spectrum is shown in fig. 4 and shows a d-spacing of 0.3355nm, and in addition, since there are no other peaks than those of graphite, it can be concluded that the sample has a graphite (carbon) purity of more than 90% wt. Furthermore, because the XRD spectrum lacks a broad, low intensity peak of amorphous carbon at low angles, it can be concluded that less than 20% of the carbon is not graphitic. Of the obtained graphiteThe sample was characterized and found to have a thickness of 26.8m²Specific surface area in g. The structure of the formed graphite is shown in fig. 3, showing a large flake-like anisotropic material with highly ordered graphite crystals. This experiment produced some large metal particles in the mixture, an example of which is shown in fig. 5.

TABLE 1 example 1 mixture composition

Based on XRD results, it can be considered that 80% of the carbon is graphitic, and therefore, the composition of the mixture can be expressed as:

(a) a graphite content of about 66 weight percent,

(b) a metal content of about 18 weight percent, and

(c) a biochar content of about 16 weight percent.

Example 2

Sawdust (50g) from pine (radiata pine) was hydrothermally treated with deionized water in an autoclave at a temperature of 360 degrees celsius for 20 min. The sample was allowed to cool and then filtered using a buchner funnel; the resulting char was dried in a conventional oven. Dry charcoal (10.1g) with a carbon content of about 80% was combined with 8.2g 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 1.3kW at a rate of approximately 30W/min. The measurement temperature is between 1400 ℃ and 1600 ℃. The power is maintained steady for about 5 to 10 minutes, after which the power supply is switched off. Once cooled, the sample was sieved below 1mm, at which time the mixture composition can be calculated as shown in table 2. It was then leached with 500ml hydrochloric acid overnight, then washed with deionized water and filtered with a buchner funnel. The resulting graphite was analyzed using: XRD (Bruker D8 Advance diffractometer using a 1mm highly parallel cobalt K alpha radiation beam with a mirror source, weighted average wavelength 1.709026 angstroms) and SEM (using an Ultra high resolution field emission microscope: Zeiss Ultra Plus 55FEGSEM equipped with an in-lens detection system operating at an accelerating voltage of 1 to 10 kV. use 1To a working distance of 5mm and the powder was gently deposited on the carbon ribbon without any additional sample preparation). The XRD spectrum is shown in fig. 7 and shows a d-spacing of 0.3392nm, and in addition, since there are no other peaks than those of graphite, it can be concluded that the sample has a graphite (carbon) purity of more than 90% wt. Furthermore, because the XRD spectrum lacks a broad, low intensity peak of amorphous carbon at low angles, it can be concluded that less than 20% of the carbon is not graphitic. A sample of graphite was characterized and found to have a thickness of 74.0m²Surface area in g. The structure of the formed graphite is shown in fig. 6, showing a material with smaller random crystallites and a more isotropic structure.

TABLE 2 example 2 mixture composition

Based on XRD results, 80% of the carbon can be considered to be graphitic, and thus the composition of the mixture can be expressed as

(a) A graphite content of about 60 weight percent,

(b) a metal content of about 25 weight percent, and

(c) a biochar content of about 15 weight percent.

Example 3

Sawdust (50g) from pine (radiata pine) was hydrothermally treated with pure water in an autoclave at a temperature of 360 degrees celsius for 20 min. The sample was allowed to cool and then filtered using a buchner funnel; the resulting char was dried in a conventional oven. Dry charcoal (26.7g) having a carbon content of about 80% was combined with 16.2g 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 1.3kW at a rate of approximately 30W/min. The measurement temperature is between 1400 ℃ and 1600 ℃. The power is maintained steady for about 30 to 40 minutes, after which the power supply is switched off. Once cooled, the sample was sieved to below 1mm at which time the mixture composition can be calculated as shown in table 3. It is then leached overnight with 500ml hydrochloric acid and subsequently deionizedWater washed and filtered with buchner funnel. The resulting graphite was analyzed using: XRD (Bruker D8 Advance diffractometer using a 1mm highly parallel cobalt K.alpha.radiation beam of a mirror source with a weighted average wavelength of 1.709026 angstroms) and SEM (using an Ultra high resolution field emission microscope: Zeiss Ultra Plus 55FEGSEM equipped with an in-lens detection system operating at an accelerating voltage of 1 to 10 kV. working distances between 1 and 5mm were used and the powder was gently deposited on carbon tape without any further sample preparation). The XRD spectrum is shown in fig. 9 and shows that the d-spacing is 0.3360nm, and in addition, since there are no other peaks except those of graphite, it can be concluded that the sample has a graphite (carbon) purity of more than 90% wt. A sample of graphite was characterized and found to have a thickness of 50.2m²Surface area in g. Furthermore, because the XRD spectrum lacks a 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 structure of the formed graphite is shown in fig. 8, showing the intermediate between the flake-like particles and the smaller random crystallites with a more isotropic structure.

TABLE 3 example 3 mixture composition

(a) a graphite content of about 64 weight percent,

(b) a metal content of about 20 weight percent, and

(c) a biochar content of about 16 weight percent.

Example 4

Graphite from several test runs under similar conditions as those described in examples 1 to 3 were mixed together to produce large samples for battery testing. The mixed samples were analyzed using XRD and found to have a d-spacing of about 0.3378nm as shown in fig. 10. The surface area was measured as 52.85m²(ii) in terms of/g. Verify the particle size distribution and find that the material has the properties as demonstrated in FIG. 1129.22 micron. The lithium ion battery performance was verified as follows: graphite is coated on the copper foil using a suitable binder. After drying, the disc was cut using a punch and mallet. It was combined with lithium metal foil to form a coin cell. Introduced by LiPF under inert conditions₆And ethylene carbonate. The button cell units were sealed and tested using a potentiostat. After testing in CR2016 coin cells, electrochemical data were collected and manually analyzed. FIG. 12 shows the first charge and discharge cycle at C/20(C is the theoretical capacity of graphite 372mAh/g) at constant current rate. The specific capacity obtained from the first discharge cycle of carboncscape graphite in the half cell was 410.87mAh/g, while the charge capacity was 275 mAh/g. This resulted in a first cycle or "coulombic" efficiency of 66.46%, and thus, the graphite showed characteristics suitable for use in lithium ion batteries.

Example 5

Sawdust (-10 g) from pine (radiata pine) was combined with about 17.6g of manganese acetate (tetrahydrate). The resulting mixture was placed in a crucible and heated in a conventional electric heating furnace (RD WEBB air-cooled vacuum furnace model RD-G). By using argon gas (>99.9%) purge establishes inert conditions and increases temperature at a ramp rate of 10 degrees per minute. The final temperature was set to 1750 degrees celsius. The temperature was maintained stable for 180 minutes, after which the furnace was shut down. Once cooled, the sample was sieved to below 1mm at which time the mixture composition can be calculated as shown in table 4. It was then leached with 500ml hydrochloric acid overnight, then washed with deionized water and filtered with a buchner funnel. The resulting graphite was analyzed using XRD (Bruker D8 Advance diffractometer using a 1mm highly parallel cobalt ka radiation beam from a mirror source with a weighted average wavelength of 1.709026 angstroms). The XRD spectrum is shown in fig. 13 and shows that the d-spacing is 0.3358nm, and furthermore, since there are no other peaks than those of graphite, it can be concluded that the sample has a graphite (carbon) purity of more than 90% wt. Using the established correlation between d-spacing and discharge Capacity [5]The material can be estimated to have an electrochemical capacity of about 351 mAh/g. Furthermore, because the XRD spectrum lacks a broad, low intensity peak of amorphous carbon at low angles, it can beTo conclude that less than 20% of the carbon is not graphitic. A sample of graphite was characterized and found to have 5.439m²Unexpectedly low surface area per gram. Using the established correlation between "coulombic efficiency" and specific surface area [5]The material can be estimated to have a "coulombic efficiency" of about 85%.

TABLE 4 example 5 mixture composition

(a) a graphite content of about 27 weight percent,

(b) a metal content of about 66 weight percent, and

(c) a biochar content of about 7 weight percent.

Example 6

Pyrolytic hard charcoal (10 g) obtained from the "Solid Energy" of new zealand was ground and sieved to below 200 microns. Carbon having a carbon content of about 70% was combined with about 6.6g of manganese oxide. The resulting mixture was placed in a crucible and heated in a conventional electric heating furnace (RD WEBB air-cooled vacuum furnace model RD-G). By using argon gas (>99.9%) purge establishes inert conditions and increases temperature at a ramp rate of 10 degrees per minute. The final temperature was set to 1750 degrees celsius. The temperature was maintained stable for 180 minutes, after which the furnace was shut down. Once cooled, the sample was sieved to below 1mm at which time the mixture composition can be calculated as shown in table 5. It was then leached with 500ml hydrochloric acid overnight, then washed with deionized water and filtered with a buchner funnel. The resulting graphite was analyzed using XRD (Bruker D8 Advance diffractometer using a 1mm highly collimated cobalt ka radiation beam with a mirror source, weighted average wavelength 1.709026 angstroms). The XRD spectrum of this sample is also shown in fig. 13 and shows that the d-spacing is 0.3362nm, and furthermore, since there are no other peaks than those of graphite, it can be concluded that the sample has a graphite (carbon) purity of more than 90% wt. Using establishedCorrelation between d-spacing and discharge Capacity [5]The material can be estimated to have an electrochemical capacity of about 346 mAh/g. Furthermore, because the XRD spectrum lacks a broad, low intensity peak of amorphous carbon at low angles, it can be concluded that less than 20% of the carbon is not graphitic. A sample of graphite was characterized and found to have only 0.204m²Extremely low surface area in g. Using the established correlation between "coulombic efficiency" and specific surface area [5]The material can be estimated to have a "coulombic efficiency" of about 96%.

TABLE 5 example 6 mixture composition

(a) a graphite content of about 53 weight percent,

(b) a metal content of about 34 weight percent, and

(c) a biochar content of about 13 weight percent.

A schematic sketch of the overall process is shown in fig. 14, where biomass in particle form (1) is processed into graphite powder (4) suitable for use in battery anodes. Biomass (1) is converted into biochar (2) in particulate form. The biochar (2) is then combined with a metal in particulate form and heat treated to form a composition of matter (3). A composition (3) of a mixture of biochar, graphite and metal is then used to form a graphite powder (4). The graphite powder (4) is produced by processing the mixture (3) as described above in the examples.

As can be seen from the examples and fig. 14, graphite powder having characteristics suitable for use as anode powder for high-performance lithium ion batteries can be obtained. Due to the unique starting point of this process, the resulting anode powder was found to be unique in its structure and performance compared to conventional natural and synthetic graphite. Thus, the resulting graphite powder exhibits a unique set of performance characteristics and can outperform natural and natural sources in particular lithium ion battery applicationsBoth graphite were synthesized. In addition, the graphite has negative CO₂Discharging the unique material of the footprint. This makes it an environmentally friendly option.

Reference to the literature

[1]Mochida,I.,Ohtsubo,R.,Takeshita,K.and Marsh,H.,1980.Catalytic graphitization of non-graphitizable carbon by chromium and manganese oxides.Carbon,18(2),pp.117-123.

[2]

A.,Yamashita,R.and

S.,1979.Catalytic graphitization of carbons by borons.Fuel,58(7),pp.495-500.

[3]Franklin,R.E.,1951.The structure of graphitic carbons.Acta crystallographica,4(3),pp.253-261.

[4]Tatsumi,K.,Iwashita,N.,Sakaebe,H.,Shioyama,H.,Higuchi,S.,Mabuchi,A.and Fujimoto,H.,1995.The influence of the graphitic structure on the electrochemical characteristics for the anode of secondary lithium batteries.Journal of the Electrochemical Society,142(3),p.716.

[5]Nishida,T.,2009.Trends in carbon material as an anode in lithium-ion battery.In Lithium-ion batteries(pp.329-341).Springer,New York,NY.

[6]Dahn,J.R.,Zheng,T.,Liu,Y.and Xue,J.S.,1995.Mechanisms for lithium insertion in carbonaceous materials.Science,270(5236),pp.590-593。

Claims

1. A composition of matter comprising a mixture of biochar, metal, and graphite having (a) a graphite content of between about 25 and 65 weight percent, (b) a metal content of between about 15 and 75 weight percent, and (c) a biochar content of between 1 and 35 weight percent.

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

3. The composition of claim 1, wherein the graphite has an electrochemical capacity of at least 200 mAh/g.

4. The composition of claim 1, wherein the graphite has an electrochemical capacity of at least 300 mAh/g.

5. The composition of claim 1, wherein the specific surface area of the graphite is about 0.2 to 50m²Between/g.

6. The composition of claim 1, wherein the specific surface area of the graphite is about 0.5 to 20m²Between/g.

7. The composition of claim 1, wherein the graphite exhibits a "coulombic" or first cycle efficiency of greater than 60%.

8. The composition of claim 1, wherein the graphite exhibits a "coulombic" or first cycle efficiency of greater than 80%.

9. The composition of any one of claims 1 to 8, wherein the graphite content in the mixture is in particulate form.

10. The composition of any one of claims 1 to 9, wherein the metal content in the mixture is in particulate form.

11. The composition of any one of claims 1 to 10, wherein the biochar content in the mixture is in particulate form.

12. The composition of any one of claims 1 to 8, wherein the graphite, metal and biochar content are all in particulate form.

13. The composition of any one of claims 1 to 12, wherein the mixture is a binary mixture having between about 25 to 75 percent carbon consisting of biochar and graphite and between about 75 to 25 percent elements of the selected metal.

14. The composition of any one of claims 1 to 13, wherein the biochar content is derived from woody biomass heated to a temperature between about 200 to 1000 degrees celsius.

15. The composition of any one of claims 1 to 14, wherein the metal is a transition metal.

16. The composition of claim 15, wherein 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.

17. The composition of any one of claims 1 to 16, wherein the biochar component has a particle size of less than about 1 millimeter.

18. The composition of any one of claims 1 to 17, wherein the particle size of the metal component is less than about 1 millimeter.

19. The composition of any one of claims 1 to 18, wherein the particle size of the graphite component is less than about 1 millimeter.

20. The composition of any one of claims 1 to 16, wherein all components have a particle size of less than 1 millimeter.

21. The composition of any one of claims 1 to 20, wherein the mixture has a total graphitic carbon content greater than about 55% wt.

22. A graphite powder produced from the mixture of any one of claims 1 to 21.

23. A high performance lithium ion battery anode powder produced from the mixture of any of claims 1 to 21.

24. A method of producing the mixture of any one of claims 1 to 23; the method comprises the following steps:

iv) sieving the final mixture to a particle size of less than about 1mm to produce a mixture having (a) a graphite content of between about 25 to 65 weight percent, (b) a metal content of between about 15 to 75 weight percent, and (c) a biochar content of between 1 to 35 weight percent.

25. The method of claim 24, wherein the biomass is thermally treated in water in a hydrothermal step.

26. The method of claim 24, wherein the biomass is thermally treated under inert conditions in the dry pyrolysis step.

27. The method of any one of claims 24 to 26, wherein the biomass is a forestry residue.

28. The method of any one of claims 24 to 26, wherein the biomass is sawdust, wood chips, or other wood-based material.

29. The method of any one of claims 24 to 28, wherein the biomass particles are less than about 10 mm.

30. The method of any one of claims 24 to 28, wherein the biomass particles are less than about 1 mm.

31. The method according to any one of claims 24 to 30, wherein the method comprises one or more steps selected from:

(a) purifying;

(b) washing and filtering the obtained graphite;

(c) densifying; and

(d) and (4) coating with carbon.

32. The process of claim 31, wherein acid leaching is used in the purification step.

33. The method of claim 31 or claim 32, wherein spheroidisation is used in the densification step.

34. A graphite powder produced by the method of any one of claims 24 to 33.

35. A high performance lithium ion battery anode powder produced by the method of any of claims 24 to 33.