Method for producing metal-containing compounds

Abstract

A method for producing a carbon-coated metal-containing compound, the method comprising the steps of: a) forming a mixture comprising: i) one or more carbon- containing polymer(s); ii) one or more alkali metal precursor compound(s); and iii) one or more metal precursor compound(s) comprising one or more metals selected from transition metals, non-transition metals and metalloids, wherein the metal in each metal precursor compound has an initial average oxidation state; and b) heating the mixture to produce a reaction product comprising the carbon-coated metal-containing compound; wherein during heating step b) the initial average oxidation state of the one or more metals in the metal precursor compound is reduced; and wherein at least a portion of the carbon coating comprises sp2 carbons. In addition to the use of a polymer in a carbothermal reduction reaction of a metal precursor compound to produce a carbon coated metal- containing compound, wherein at least a portion of the carbon coating comprises sp2 carbons and the use of a halogenated polymer in a carbothermal reduction reaction of a metal precursor compound to produce a carbon-coated halogen doped metal-containing compound, wherein at least a portion of the carbon coating comprises sp2 carbons. Further, an electrode active material made according to the method; a composition comprising LiFePO4 in particulate form prepared according to the method, wherein the particles are at least partially coated with a carbon coating, and wherein at least a portion of the carbon coating comprises sp2 carbons; and a battery comprising an electrode comprising a carbon-coated metal-containing compound produced according to the method, optionally wherein the battery is a rechargeable battery, optionally wherein the battery is an alkali metal ion battery, such as a lithium ion battery.

Description

[0001]METHOD FOR PRODUCING METAL-CONTAINING COMPOUNDS CROSS-REFERENCE TO RELATED APPLICATIONThe present application claims the priority of United Kingdom Patent Application No.2409903.8, filed on 8 July 2024, the entirety of which is herein incorporated by reference. FIELD OF THE INVENTIONThe present invention relates to methods for producing metal-containing compounds whichcan be used as electrode materials for batteries, capacitors, or other energy storagedevices. BACKGROUNDMetal-containing compounds, such as alkali metal phosphates, have attracted considerableattention in recent years due to their high capacity, good rate performance, and improved stability as electrode materials for various energy storage devices.One well-established approach for synthesizing electrode materials is the carbothermalreduction (CTR) process. In this process, a metal precursor compound (e.g. Fe2O3, Fe3O4,and FePO4) is heated at elevated temperature in the presence of an alkali metal precursorcompound and an excess of particulate carbon under an inert or reducing atmosphere toform a compound containing a reduced metal or metal alloy (e.g. Fe2+) and carbonmonoxide or carbon dioxide as by-products. As shown in Figure 1, the excess particulatecarbon forms an electrically conductive matrix (103) between the particles of metal-containing compounds (101) in the product. The reaction temperature, time, andatmosphere can be adjusted to control the size, morphology, composition, and phasepurity of the product.Prior art disclosures of the CTR process can be found, for example, in US6528033,US6702961, US6716372, US6730281, US6794084, US6960331, US7060206,US7276218, and US8163430 which are incorporated herein by reference, andUS10050271B2, which is also incorporated herein by reference and which describesmethods for performing carbothermal reduction of metal precursor compounds in thepresence of elemental phosphorus.However, a problem associated with the use of particulate carbons in the CTR process isthat they do not coat the individual LiFePO4particles but rather provide point contactsbetween adjacent particles and agglomerates. This can lead to poor utilization of the activematerial during battery operation. There is therefore a need for a method of producingcarbon-coated metal-containing compounds which have desirable properties that renderthem useful as electroactive materials in energy storage applications. SUMMARY OF THE INVENTION In accordance with a first aspect of this invention, there is provided a method for producing a carbon-coated metal-containing compound, the method comprising the steps of: a) forming a mixture comprising: i) one or more carbon-containing polymer(s); ii) one or more alkali metal precursor compound(s); and iii) one or more metal precursor compound(s) comprising one or more metals selected from transition metals, non-transition metals and metalloids, wherein the metal in each metal precursor compound has aninitial average oxidation state; and b) heating the mixture to produce a reaction product comprising the carbon-coated metal-containing compound; wherein during heating step b) the initial average oxidation state of the one ormore metals in the metal precursor compound is reduced.The carbon-coated metal-containing compound comprises a carbon coating, wherein at least a portion of the carbon coating comprises sp2carbons.In the method, the carbon-containing polymer, alkali metal precursor compound, andmetal precursor compound react to form particles of a carbon-coated alkali metal-metalcomposite product. The carbon-containing polymer forms a coating on the particles ofprecursor material. During heating, the precursor materials react to form a reduced metal-containing compound, without full reduction of the metal to an elemental state, and thecarbon-containing polymer is decomposed in an inert atmosphere (pyrolyzed) to form acarbon coating on the particles. Some of the polymer also forms an electrically conductive carbon matrix between the carbon-coated metal particles, resulting in a highly electrically conductive composite material which has advantageous properties when used to form anelectrode, such as a cathode, of a battery, capacitor, or other energy storage device.The metal-containing compound produced by the method may have the formula: AaMb(XcYd)eZfFormula (I) wherein: A is an alkali metal selected from one or more of lithium, sodium and potassium; M comprises one or more metals selected from transition metals, non-transition metals, and metalloids; (XcYd)e is at least one first anion; and Z is at least one second anion; wherein a ≥0; b >0; c >0; d ≥0; e >0 and f ≥0; wherein a, b, c, d, e and f are chosen to maintain electroneutrality; wherein X comprises one or more elements selected from titanium, vanadium, chromium, arsenic, molybdenum, tungsten, niobium, manganese, aluminium, selenium, boron, oxygen, carbon, silicon, phosphorus, nitrogen, sulfur, fluorine, chlorine, bromine and iodine; and wherein Y is selected from one or more halides, sulfur-containing groups, oxygen- containing groups and mixtures thereof. Compounds of this formula are ideally suitable for use as electrode materials, andparticularly as cathode materials, in alkali metal batteries, such as Li-ion, Na-ion and K-ion batteries.In the above formula, M may be a metal selected from one or more of titanium, vanadium, niobium, tantalum, hafnium, chromium, molybdenum, tungsten, manganese, iron, osmium, cobalt, nickel, palladium, platinum, copper, silver, gold, zinc, cadmium, aluminium, scandium, yttrium, zirconium, technetium, rhenium, ruthenium, rhodium, iridium, mercury, gallium, indium, tin, lead, bismuth, magnesium, calcium, beryllium, strontium and barium, boron, silicon, germanium, arsenic, antimony and tellurium.Z may be selected from one or more halides, hydroxide-containing groups and mixturesthereof. X may comprise phosphorus.(XcYd)e may be a PO4 and / or P2O7 moiety.The metal-containing compound produced by the method may be selected from one ormore of the group consisting of LiFePO4, LiMnPO4, LiCoPO4, LiNiPO4, NaFePO4, NaMnPO4, NaCoPO4, NaNiPO4, LiMn0.5Fe0.2Mg0.3PO4, Li3V2(PO4)3, Na4Fe3(PO4)2P2O7, Na3V2(PO4)3, 3, The metal-containing compound produced by the method may have the formula: LiMPO4,where M is a metal selected from one or more of manganese, iron, cobalt, nickel, copper, zinc, magnesium, calcium and combinations thereof.The metal-containing compound produced by the method may be selected from LiFePO4,LiFe1-xMnxPO4, LiFe1-xMgxPO4and LiFe1-x-yMnxMgyPO4. In the latter two compounds, Mg maybe present in <10 wt%, preferably <5 wt%.The metal precursor compound may comprise Fe. The metal precursor compound may be selected from one or more of FeCO3, Fe2O3, Fe3O4, FeOOH, FePO4.xH2O, FePO4, Fe3(PO4)2, FeSO4.xH2O, Fe(NO3)3, Fe(CH3CO2)2, C6H8O7xFe3+.yNH3(ammonium iron (III) citrate), C6H5FeO7 (iron (III) citrate) and Fe(C5H7O2)3 (iron (III) 2,4-pentanedionate), wherein x, y are ≥0.The mixture may comprise one or more compounds or hydrates thereof selected fromLiH2PO4, Li3PO4, LiPO3, Li2CO3, Li2SO4, Lithium citrate, Li2HPO4, LiOH, H3PO4, (NH4)2HPO4and (NH4)H2PO4, preferably LiH2PO4 or Li2CO3.The heating step b) may include heating the mixture at a temperature proximate to orabove the melting point of the carbon-containing polymer. This may permit the polymerto melt over and coat the metal particles prior to conversion of the polymer to carbon by pyrolysis. The heating step b) may comprise heating at a first temperature sufficient to melt the carbon-containing polymer and heating at a second temperature sufficient to convert the carbon-containing polymer to carbon, optionally wherein the first temperature is in the range of 50 °C to 250 °C and wherein the second temperature is in the range of 300 °C to 1500 °C. Improved coating of the metal particles may be achieved by having a two- step heating process, wherein the particles are coated with molten polymer in the first heating step, and then the polymer coating is pyrolyzed to form a carbon coating on the particles in the second step. The temperature of the first step may be selected to correspond to the melting point of the polymer, and the temperature of the second step may be selected to correspond to the temperature of pyrolysis.The first temperature may be maintained for a period of 1 to 100 minutes and the secondtemperature may be maintained for a period of 1 to 500 minutes.At least part of the carbon-containing polymer may be converted to elemental carbonduring heating at the second temperature. Optionally, at least part of the carbon-containing polymer may be converted to sp2 hybridized carbon. Conversion of the polymerto sp2carbon may result in graphitisation of the carbon, which may enhance electricalconnectivity. Fe compounds advantageously catalyse the graphitisation reaction. In orderto obtain as high a conductivity as possible with as minimal an amount of carbon as possible, at least 5%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, or 95%, or a range between any two of the aforementioned values, of the carbon atoms in the carbon coating may be sp2hybridized carbon. In step a), the mixture may further comprise particulate carbon. The particulate carbonmay connect the metal particles together into an electrically connected network or matrix.The particulate carbon may be present in an amount of greater than 0% to 50% by weight,or from 2% to 50%, or 5% to 20%, based on the combined weight of the polymer andparticulate carbon. The particulate carbon may enhance the tap density and / orcompressibility of the carbon-coated metal-containing compound without (substantial) loss of specific capacity. The carbon-coated metal-containing compound produced by the method may have a total carbon content of from 1 to 5% by weight carbon. The carbon-containing polymer may be selected from the group consisting of polyethylene (PE), HMPE (high modulus PE), HDPE (high density PE), LDPE (low density polyethylene) polypropylene (PP), HMPP (high modulus PP), HDPP (high density PP), LDPP (low density polypropylene), polyvinylchloride (PVC), polyethylene terephthalate (PET), polystyrene (PS), polyethylene glycol (PEG), polyvinylidene fluoride (PVdF), poly(vinylidene fluoride- co-hexafluoropropylene) (PVdF-HFP), polyacrylonitrile (PAN), polyvinyl alcohol (PVA), polytetrafluoroethylene (PTFE), polycarbonates, nylon, and combinations thereof. Preferably, the polymer has a high carbon content, such as polyethylene and polypropylene. Optionally, the polymer may be in particulate form. Optionally the polymermay be waste polymer, such as recycled plastic waste.The carbon-containing polymer may be an elastomer obtained from rubber. Optionally, therubber may be tyre rubber, such as de-vulcanized tyre rubber. Tyre rubber also contains particulate carbon in the form of carbon black.The carbon-containing polymer may be soluble in a polar solvent. Optionally, the solventmay be acetone or water (or another polar solvent). Optionally, the method may comprisemixing the polymer in the solvent and evaporating the solvent prior to or during heating.The solvent may improve mixing of the precursors and the polymer. The carbon-containing polymer may comprise a halogen selected from Cl, Br, F, or I. For example, the carbon-containing polymer may be selected from the group consisting of PVdF, PVdF-HFP, poly(chlorotrifluoroethylene), poly(tetrafluoroethylene), and PVC. The halogen may dope the carbon-coated metal compound and thereby enhance its electrical performance. The polymer in the mixture may be in particulate form, preferably, wherein the average particle size diameter is less than 20 µm as measured by laser diffraction analyser. The quantity of polymer used in the method may be sufficient to provide a stoichiometric molar excess of carbon with respect to the metal precursor compound.The method may further comprise contacting the mixture with a reducing gas duringheating step b). Optionally, the reducing gas may be selected from CO, H2, andcombinations thereof. The reducing gas may assist in reducing the metal precursorcompound and thereby accelerate the reaction. Advantageously, the reducing gas may begenerated in situ during pyrolysis of the polymer. Alternatively, the reducing gas may beadded to the reaction mixture prior to or during heating.In accordance with a second aspect of this invention, there is provided a use of a polymerin a carbothermal reduction reaction of a metal precursor compound to produce a carboncoated metal-containing compound. The carbon-coated metal-containing compoundcomprises a carbon coating, wherein at least a portion of the carbon coating comprises sp2carbons. In accordance with a third aspect of this invention, there is provided a use of a halogenatedpolymer in a carbothermal reduction reaction of a metal precursor compound to producea carbon-coated halogen doped metal-containing compound. The carbon-coated metal- containing compound comprises a carbon coating, wherein at least a portion of the carbon coating comprises sp2carbons.In accordance with a fourth aspect of this invention, there is provided a use of a carbon-containing polymer and particulate carbon in a carbothermal reduction reaction of a metalprecursor compound to produce a carbon-coated metal-containing compound. The carbon-coated metal-containing compound comprises a carbon coating, wherein at least a portion of the carbon coating comprises sp2carbons.The advantages of the second, third and fourth aspects may correspond to those of thefirst aspect.The halogenated polymer may be selected from the group consisting of PVdF, PVdF-HFPand PVC. In accordance with a fifth aspect of this invention, there is provided an electrode active material made according to the above method.In accordance with a sixth aspect of this invention, there is provided a compositioncomprising LiFePO4in particulate form prepared according to the above method, wherein the particles are at least partially coated with a graphitic coating. In accordance with a seventh aspect of this invention, there is provided a battery comprising an electrode comprising a carbon-coated metal-containing compound producedaccording to the above method. Optionally, the battery may be a rechargeable battery.Optionally, the battery may be an alkali metal ion battery, such as a lithium-ion battery ora sodium-ion battery.In accordance with an eighth aspect of this invention, there is provided a use of a carbon-coated metal-containing compound produced according to the above method as an electrode in a rechargeable battery. Optionally, the battery may be an alkali metal ionbattery, such as a lithium-ion battery or a sodium-ion battery.Unless otherwise stated, each of the integers described may be used in combination with any other integer as would be understood by the person skilled in the art. Further, althoughall aspects of the invention preferably “comprise” the features described in relation to thataspect, it is specifically envisaged that they may “consist” or “consist essentially” of thosefeatures outlined in the claims. In addition, all terms, unless specifically defined herein, are intended to be given their commonly understood meaning in the art. As used herein and in the accompanying claims, unless the context requires otherwise,“comprise” or variations such as “comprises” or “comprising” will be understood to implythe inclusion of a stated integer or group of integers but not the exclusion of any other integer or group of integers. The term “consist(s) / (ing) essentially of”, with respect to the components of a composition or mixture, means the composition or mixture contains the indicated components and may contain minor additional components in an amount less than 1 wt% based on the total weight of the composition or mixture, and provided that the additional components do not substantially alter the reactivity of the composition or mixture. Further, in the discussion of the invention, unless stated to the contrary, the disclosure of alternative values for the upper or lower limit of the permitted range of a parameter, is to be construed as an implied statement that each intermediate value of said parameter, lying between the smaller and greater of the alternatives, is itself also disclosed as a possible value for the parameter. In addition, unless otherwise stated, all numerical values appearing in this application are to be understood as being modified by the term “about”. As used herein, the term “about” means that the stated value can vary by ± 10%. For example, about 90 wt% means 90±9 wt%, and about 0.1 wt% means 0.1±0.01 wt%. When used with reference to a range, the term “about” applies to all values in the range. As used herein, the term “carbon-coated” will be understood to refer to a layer of carbondeposited on the surface of a particle or agglomerate of the metal-containing compound.The carbon coating covers >50%, preferably >80%, more preferably >90%, and mostpreferably >99% of the surface area of the particle or agglomerate. The % coverage canbe determined visually by transmission electron microscopy. “Metal-containing compound” refers to a compound, composite, salt, or complex which contains one or more metals. The metal may be in ionic form or neutral form. “Alkali metal precursor compound” refers to a compound, composite, salt, or complex which contains one or more alkali metals and which is used as a starting material for the reaction of the method. The metal may be in ionic form or neutral form and may beselected from Li, Na, K, Rb, Cs or Fr, preferably, Li, K or Na. The alkali metal precursorcompound contributes an alkali metal atom to the metal-containing compound producedby the method. The present invention will be better understood in light of the following examples and the accompanying figures, which are given in an illustrative manner only and should not be interpreted in a restrictive manner. BRIEF DESCRIPTION OF THE FIGURES In the accompanying Figures: Figure 1 shows a TEM image of an LiFePO4 particle (101), which is not according tothe present invention, surrounded by a matrix of particulate carbon (103).Figure 2 shows a TEM image of an LiFePO4 particle (201) according to the present invention which comprises a carbon coating (203).Figure 3 shows a Raman spectrum of carbon-coated LiFePO4 particles of the samecomposition as the particle of Figure 2. Figure 4 is an XRD diagram of a sample prepared according to Comparative Example 1.Figure 5 shows the constant current data for the LiFePO4 cathode active materialof Comparative Example 1 (made using LiH2PO4, Fe2O3 and C65 particulate carbon).Figure 5 shows the voltage profile (electrode potential versus specific capacity) for cycle 2. The current density was set to an equivalent rate of C / 10 assuming a reversible specific capacity of 150 mAh / g for the active material (where a 1 C rateis a rate equivalent to a 1-hour charge and a 1-hour discharge).Figure 6 is an XRD diagram of a sample prepared according to Example 1.Figure 7 shows the Electrochemical Voltage Spectroscopy (EVS) voltage profile forthe LiFePO4 cathode active material of Example 1 (made using Li2CO3, FePO4 andHDPE). Figure 8 shows the differential capacity data for the LiFePO4sample of Example 1.Figure 9 is an XRD diagram of a sample prepared according to Example 2.Figure 10 shows the EVS voltage profile for the LiFePO4 cathode active material ofExample 2 (made using LiH2PO4, FeOOH and HMPE).Figure 11 shows the differential capacity data for the LiFePO4 sample of Example 2. Figure 12 is an XRD diagram of a sample prepared according to Example 3. Figure 13 shows the EVS voltage profile for the LiFePO4 cathode active material of Example 3 (made using Li2CO3 / anhydrous FePO4 / C65 particulate carbon / polyethylene). Figure 14 shows the differential capacity data for the LiFePO4 sample of Example 3. Figure 15 is an XRD diagram of a sample prepared according to Example 4. Figure 16 shows the EVS voltage profile for the LiFePO4cathode active material ofExample 4 (made using Li2CO3 / anhydrous FePO4 / C65 particulatecarbon / polyethylene). Figure 17 shows the differential capacity data for the LiFePO4 sample of Example 4. Figure 18 is an XRD diagram of a prepared according to Example 5. Figure 19 shows the EVS voltage profile for the LiFePO4cathode active material of Example 5 (made using Li2CO3 / anhydrous FePO4 / PS). Figure 20 shows the differential capacity data for the LiFePO4 sample of Example 5. Figure 21 is an XRD diagram of a sample prepared according to Example 6. Figure 22 shows the EVS voltage profile for the LiFePO4cathode active material of Example 6 (made using Li2CO3 / anhydrous FePO4 / PET). Figure 23 shows the differential capacity data for the LiFePO4 sample of Example 6. Figure 24 is an XRD diagram of a sample prepared according to Example 7. Figure 25 shows the EVS voltage profile for the LiFePO4 cathode active material of Example 7 (made using Li2CO3 / anhydrous FePO4 / devulcanized tyre rubber). Figure 26 is an XRD diagram of a sample prepared according to Example 8. Figure 27 shows the EVS voltage profile for the LiFePO4cathode active material of Example 8 (made using Li2CO3 / anhydrous FePO4 / PP).Figure 28 shows X-ray diffraction patterns for LiFePO4 (HMPE plus particulatecarbon, 50% excess), where particulate carbon proportions are 0%, 2.5%, 5%,10% and 20%.Figure 29 shows a graph of 0.1C 2nd cycle discharge specific capacity versus %particulate carbon for LiFePO4 (HMPE, 50% excess), where particulate carbon hasbeen added in proportions of 0%, 2.5%, 5%, 10% and 20%.Figure 30 shows a graph of tap density versus % particulate carbon for LiFePO4(HMPE 50% excess), where particulate carbon has been added in proportions of0%, 2.5%, 5%, 10% and 20%.Figure 31 shows a graph of compression density versus % particulate carbon forLiFePO4 (HMPE 50% excess), where particulate carbon has been added inproportions of 0%, 2.5%, 5%, 10% and 20%.Figure 32 shows the X-ray diffraction patterns for LiFePO4 (PA-6 plus particulatecarbon, 50% excess), where particulate carbon proportions are 0%, 2.5%, 5%, 10%, 20%, 50%. Figure 33 shows LiFePO4 (PA-6 plus particulate carbon, 50% excess) 0.1C 2nd cycledischarge specific capacity. Figure 34 shows LiFePO4 (PA-6 plus particulate carbon, 50% excess) tap densitywhere particulate carbon proportions are 0%, 2.5%, 5%, 10%, 20%, 50%. Figure 35 shows LiFePO4 (PA-6 plus particulate carbon, 50% excess) compresseddensity where particulate carbon proportions are 0%, 2.5%, 5%, 10%, 20%, 50%. Figure 36 shows a graph comparing the tap density versus the 0.1C 2nd cycledischarge capacity for the LiFePO4: HMPE (plus particulate carbon) 50% excess andPA-6 (plus particulate carbon) 50% excess samples.DETAILED DESCRIPTION The present invention provides a new, scalable method for producing a carbon-coated metal-containing compound which can be used as an electrode material for various types of batteries, such as alkali metal-ion batteries (e.g. lithium-ion batteries and sodium-ionbatteries). The method uses carbothermal reduction (CTR) of precursor compounds in thepresence of polymers. It has been discovered that suitable polymers are especially usefulas the carbon source for the CTR method. During heating, the polymer initially flows(above or close to its melt temperature) and coats the metal precursor particles and isthen decomposed in situ to elemental carbon. Advantageously, the polymer may alsoproduce reducing gases (such as CH4, H2and combinations thereof) during decomposition.The reducing gases may be useful for reducing the metals in the metal precursorcompounds (for example, reducing Fe3+to Fe2+). The method involves forming a mixture of one or more carbon-containing polymers, one or more alkali metal precursor compounds, and one or more metal precursor compounds, and heating the mixture to produce a product comprising the carbon-coated metal-containing compound. During the heating process, the initial average oxidation stateof the metal in the metal precursor compound is reduced. The carbon-containing polymerserves as both a carbon source and a reducing agent for the metal precursor compoundand also forms a carbon coating on the surface of the metal-containing compound produced by the method, which can improve the conductivity, stability, and performanceof the material when used as an electrode material. The carbon is believed to act as areducing agent and is itself oxidized to form CO and CO2in varying proportions. As shown in Figure 2, the carbon coating (203) forms a thin layer over the particles of the metal-containing compound LiFePO4 (201). Advantageously, the polymer also assists incompaction / pelletization of the mixture prior to heating by acting as a binder. Thisenhanced compaction minimises gaps between the reactant particles, aids the kinetics ofthe solid-state CTR reaction, and generally improves product formation.The carbon-containing polymer used in the method of the invention can be any polymerthat contains carbon atoms in its backbone or side chains and that can decompose underheat to form carbon and volatile products. Examples of suitable carbon-containing polymers include, but are not limited to, polyethylene (PE), HMPE (high modulus PE), HDPE (high density PE), LDPE (low density polyethylene) polypropylene (PP), HMPP (high modulus PP), HDPP (high density PP), LDPP (low density polyethylene), polyvinylchloride (PVC), polyethylene terephthalate (PET), polystyrene (PS), polyethylene glycol (PEG), polyvinylidene fluoride (PVdF), poly(vinylidene fluoride-co-hexafluoropropylene) (PVdF- HFP), polyacrylonitrile (PAN), polyvinyl alcohol (PVA), polytetrafluoroethylene (PTFE),polycarbonates, nylon, rubber, natural rubber (polyisoprene), synthetic rubber,devulcanized rubber, or any combination thereof. The carbon-containing polymer can be used in any form, such as powder, granule, pellet, film, fiber, fabric, or foam. The carbon- containing polymer(s) can be derived from various sources, such as virgin polymer materials, recycled polymer materials, waste polymer materials, or biomass-derived polymer materials. In some embodiments, the carbon-containing polymer(s) can bederived from waste polymer materials, such as plastic waste (e.g. waste PET, PS, PE, PPetc collected from waste products), packaging waste, textile waste, or tyre waste, whichcan reduce the cost and environmental impact of the method of the invention. The polymercan be prepared by cryomilling. The polymer can be in particulate (powder) form. For example, the polymer can be in powder form in which the average particle size diameter, as measured by laser diffraction analyser, is less than 100 µm, less than 75 µm, less than 50 µm, less than 20 µm, less than 10 µm, or in a range between any two of the aforementioned values. Preferably the particle size diameter is less than 20 µm. Due to the relative low cost of polymers with respect to particulate carbon, the overall costs of the present method can be lower than CTR processes. In some embodiments, the carbon-containing polymer can be an elastomer. An elastomer is a polymer that exhibits elastic properties and can be stretched or deformed and return to its original shape. Examples of elastomers include, but are not limited to, natural rubber, synthetic rubber, silicone, and polyurethane. An advantage of using an elastomer as the carbon-containing polymer is that it can form a conformal and uniform coating on the metal precursor particles due to its flexibility and viscosity. Moreover, an elastomer candecompose under heat to form carbon and volatile products that can assist in the reductionof the metal precursor compounds. The elastomer can compromise rubber, which is a natural or synthetic material that contains polymers of isoprene or other dienes. Rubber can pose a significant environmental problem due to its non-biodegradability and accumulation in landfills. Therefore, using rubber as the carbon-containing polymer can provide a beneficial way of recycling and reusing waste rubber materials, such as discarded tyres, and converting them into valuable electrode materials. The rubber can be tyre rubber, which is a type of rubber that is used for making tyres for vehicles. Tyre rubber typically comprises natural or synthetic rubber, carbon black, sulphur, and other additives. By containing a combination of elastomer and carbon black, tyre rubber provides a useful input material as it contains both a meltable polymer and particulate carbon. The tyre rubber can be de-vulcanized prior to or during the heating process. Vulcanization is a chemical process that involves cross-linking the rubber molecules with sulphur or other agents to improve the strength and durability of the rubber. De-vulcanization is a process that reverses vulcanization and breaks the cross-links between the rubber molecules,resulting in a softer and more flexible rubber product. De-vulcanization can be achievedby various known methods, such as thermal, mechanical, chemical, or biological methods, or any combination thereof. By using de-vulcanized tyre rubber as the carbon-containing polymer, the method of the invention can reduce the amount of sulphur and other impurities in the final product and thereby enhance its electrical performance.A carbon-containing polymer comprising a halogen selected from Cl, Br, F, or I can provideadditional benefits for the method of the invention. For example, the halogen atoms can be incorporated into the metal-containing compound as dopants or intercalants, which can modify the electrochemical properties of the metal-containing compound and improve its performance as an electrode material. For example, fluorine or chlorine doping or intercalation can increase the specific capacity, rate capability, and cycling stability of metal precursor materials. Additionally, the halogen atoms can react with other elements in themetal precursor compound or the carbon-containing polymer to form volatile compounds,such as hydrogen halides or carbon halides, that can be removed from the system during the heating process. This can reduce the amount of impurities and byproducts in the final product. The carbon-containing polymer comprising a halogen can be any polymer that contains one or more of Cl, Br, F, or I atoms in its backbone or side chains. Examples include, but are not limited to, polyvinylchloride (PVC), polyvinylidene fluoride (PVdF), poly(vinylidene fluoride-co-hexafluoropropylene) (PVdF-HFP), poly(chlorotrifluoroethylene) (PCTFE), poly(tetrafluoroethylene) (PTFE), poly(vinyl fluoride) (PVF), poly(vinylidene chloride) (PVDC), poly(vinyl bromide) (PVB), poly(vinylidene bromide) (PVDB), poly(ethylene-co- tetrafluoroethylene) (ETFE), poly(fluoroethylene propylene) (FEP), poly(ethylene chlorotrifluoroethylene) (ECTFE), poly(tetrafluoroethylene-co-perfluoromethyl vinyl ether) (MFA), poly(tetrafluoroethylene-co-perfluoropropyl vinyl ether) (PFA), polyperfluoroalkoxy alkanes (PFAAs), perfluoropolyether (PFPE), polyhexafluoropropylene (PHFP), polytrifluorochloroethylene (PTFCE), polyvinylidene fluoride-co-trifluoroethylene (PVDF- TrFE), polychloroprene, polybromostyrene, poly(fluoroalkyl acrylate), poly(fluoroalkylmethacrylate), poly(chloroalkyl acrylate), poly(chloroalkyl methacrylate), poly(bromoalkylacrylate), poly(bromoalkyl methacrylate), or any combination thereof. In some embodiments, the carbone-containing polymer comprising a halogen can be selected from PVdF, PVdF-HFP, poly(chlorotrifluoroethylene), poly(tetrafluoroethylene), PVC, and combinations thereof. Some carbon-containing polymers, such as PEG, PVA, and PS, are soluble in polar solvents, such as acetone or water. The method can include a step of dissolving the carbon- containing polymer in a polar solvent to facilitate the dispersion and mixing of the polymer with the metal precursor particles. The solvent can be evaporated prior to or during the heating process, leaving behind a heterogeneous mixture of the polymer and the metal precursor particles. The evaporation of the solvent can also generate gas that can assist in the reduction of the metal precursor compounds and contribute to the formation of the carbon coating. The use of a polar solvent can improve the quality and uniformity of the electrode material produced by the method of the invention. In some embodiments, including a step of dissolving the carbon-containing polymer in a polar solvent can result in a carbon-coated metal-containing compound which when used as an electrode material, produces a higher specific capacitance and lower resistance than electrode material prepared without the dissolution step. The quantity of polymer used in the method can be sufficient to provide a stoichiometric molar excess of carbon with respect to the metal precursor compound. This is so thatsufficient carbon is present to act as a agent for the metal precursor compound and provide a carbon coating. The molar equivalents of carbon can be calculated based on the weight per gram-mole of carbon atoms. For elemental carbons such as carbon black, graphite, and so on, the equivalent weight can be about 12 g / equivalent, whereas for carbon-containing polymers, the equivalent weight per gram-mole of carbon atoms is higher. For example, polymers containing predominantly or entirely carbon and hydrogen in the polymer chain have an equivalent weight of about 14 g / equivalent. Depending on the degree of unsaturation and non-carbon atoms, the equivalent weight of the polymer may be slightly above or below 14.The alkali metal precursor compound used in the method can be any compound thatcontains one or more alkali metals, such as lithium, sodium, potassium, rubidium,caesium, or francium, preferably, lithium or sodium. Examples of suitable alkali metal precursor compounds include, but are not limited to, alkali metal salts, alkali metal phosphates, alkali metal oxides, alkali metal hydroxides, alkali metal carbonates, alkali metal bicarbonates, alkali metal sulfates, alkali metal hydroxides, alkali metal nitrates, alkali metal nitrides, alkali metal halides, alkali metal organometallic compounds, or anycombination thereof. In some embodiments, the alkali metal precursor compound can beselected based on the type of the battery to be produced, such as lithium-containing precursor compounds for lithium-ion batteries, sodium-containing precursor compounds for sodium-ion batteries, potassium-containing precursor compounds for potassium-ion batteries, or other alkali metal precursor compounds for other alkali metal-ion batteries.The alkali metal precursor compound can comprise one or more compound(s) orhydrate(s) thereof selected from LiH2PO4, Li3PO4, LiPO3, Li2CO3, Li2SO4, Lithium citrate,Li2HPO4, LiOH, H3PO4, optionally in combination with (NH4)2HPO4and / or (NH4)H2PO4.Preferably the alkali metal precursor compound is LiH2PO4 or Li2CO3.The metal precursor compound(s) used in the method of the invention can be anycompound that contains one or more metals, such as transition metals, non-transitionmetals, or metalloids, in their chemical structure. The metal in the metal precursorcompound can have an initial average oxidation state, which can be zero or a positiveinteger. Examples of suitable metal precursor compounds include, but are not limited to, metal salts, metal oxides, metal hydroxides, metal sulfates, metal nitrates, metal nitrides, metal halides, metal sulfides, metal phosphates, metal phosphides, metal carbonates, metal bicarbonates, metal carboxylates, metal organometallic compounds, or anycombination thereof. The metal precursor compound can provide the metal element forthe metal-containing compound produced by the method, which can act as an activematerial for the electrode material. In some embodiments, the metal precursor compound(s) can be selected based on the desired properties and performance of the electrode material, such as the capacity, the voltage, the rate capability, the cycle life, the safety, or the compatibility with the electrolyte and the current collector. The metal-containing compound produced by the method can have the formula: AaMb(XcYd)eZfformula (I) wherein: A is an alkali metal selected from one or more of lithium, sodium and potassium; M comprises one or more metals selected from transition metals, non-transition metals, and metalloids; (XcYd)e is at least one first anion; and Z is at least one second anion; wherein a ≥0; b >0; c >0; d ≥0; e >0 and f ≥0; wherein a, b, c, d, e and f are chosen to maintain electroneutrality; wherein X comprises one or more elements selected from titanium, vanadium, chromium, arsenic, molybdenum, tungsten, niobium, manganese, aluminium, selenium, boron, oxygen, carbon, silicon, phosphorus, nitrogen, sulfur, fluorine, chlorine, bromine and iodine; and wherein Y is selected from one or more halides, sulfur-containing groups, oxygen- containing groups and mixtures thereof. Examples of suitable metals for M in the above formula include a metal selected from the group consisting of titanium, vanadium, niobium, tantalum, hafnium, chromium, molybdenum, tungsten, manganese, iron, osmium, cobalt, nickel, palladium, platinum, copper, silver, gold, zinc, cadmium, aluminium, scandium, yttrium, zirconium, technetium, rhenium, ruthenium, rhodium, iridium, mercury, gallium, indium, tin, lead, bismuth, magnesium, calcium, beryllium, strontium and barium, boron, silicon, germanium, arsenic,antimony and tellurium or any combination thereof.The metal-containing compound produced by the method can be selected from one or2, 2, Na8−2xFe4+x(P2O7)4, Na8−2xMn4+x(P2O7)4, Na2MnP2O7, Na2FeP2O7, Na2CoP2O7, Na4Mn3(PO4)2P2O7, Na4Co3(PO4)2P2O7, Na4Ni3(PO4)2P2O7, NaFeSO4F, LiFeSO4F, NaMnSO4F, LiMnSO4F, Na2Fe2(SO4)3, Li2Fe2(SO4)3, Li2Fe(SO4)2, Na2FePO4F, Na2MnPO4F, Na2CoPO4F, Na2NiPO4F, Na3V2(PO4)2F3, KVPO4F, KVOPO4, K3V2(PO4)3, K3V2(PO4)2F3, KFePO4, andKCoPO4. In some embodiments, the metal containing compound can be selected from oneor more of LiFePO4, LiFe1-xMnxPO4, LiFe1-xMgxPO4and LiFe1-x-yMnxMgyPO4, wherein in the latter two compounds, Mg is present in an amount of less than 10%, or less than 5%.In some embodiments, the metal-containing compound can have the formula: LiMPO4,where M is a metal selected from one or more of manganese, iron, cobalt, nickel, copper, zinc, magnesium, calcium and combinations thereof. In some preferred embodiments, themetal containing compound is LiFePO4.In some embodiments, the metal precursor compound can be selected from one or moreof Fe2O3, Fe3O4, FeOOH, FePO4.xH2O, FePO4, Fe3(PO4)2, FeSO4.xH2O, Fe(NO3)3, Fe(CH3CO2)2, C6H8O7xFe3+.yNH3(ammonium iron (III) citrate), C6H5FeO7(iron (III) citrate) and Fe(C5H7O2)3(iron (III) 2,4-pentanedionate), wherein x, y are ≥0. In some embodiments, Z can be selected from one or more halides, hydroxide-containing groups and mixtures thereof. In other embodiments, Z may not be present in the metal- containing compound (i.e. where f = 0). In some embodiments, X can comprise phosphorus. For example, (XcYd)e can be a PO4 and / or P2O7moiety.In some embodiments, the polymer may be replaced or supplemented in the mixture byphytic acid (C6H18O24P6, also referred to as inositol hexaphosphate, inositolhexakisphosphate (IP6) or inositol polyphosphate), which may act as both a phosphorusand carbon source. The phytic acid may be pyrolyzed to form a carbon coating on theparticles and agglomerates of the metal compound in the same manner as the polymer.In some embodiments, the alkali metal precursor compound may comprise an organicmoiety, such as lithium / sodium / potassium citrate, which may provide both a source ofalkali metal and carbon. In these embodiments, the organic moiety may replace orsupplement the polymer in the method.The heating step b) of the method can include heating the mixture at a temperature proximate to or above the melting point of the carbon-containing polymer. This can facilitate coating of the particles of the material as the polymer melts. The temperature proximate to or above the melting point of the carbon-containing polymer can vary depending on the type and composition of the polymer used. For example, if the carbon-containing polymer is a polyethylene (PE), the temperature can be in the range of 120 °C to 130 °C. If the carbon-containing polymer is a polyethylene glycol (PEG), the temperature can be in the range of 50 °C to 70 °C, depending on the length of the polymer). If the carbon-containing polymer is a polypropylene (PP), the temperature canbe in the range of 160 °C to 171 °C. If the carbon-containing polymer is a polyvinyl alcohol(PVA), the temperature can be in the range of 150 °C to 200 °C. The temperature of thisaspect of the heating step can be in the range of 50 °C to 250 °C. The heating step b) can be performed in one or more stages. For example, the mixture can be heated at a first temperature that is sufficient to melt the carbon-containing polymer and coat the particles of the precursor material. This can ensure a uniform distribution of the polymer on the surface of the particles and prevent agglomeration. Optionally, the first temperature can be in the range of 50 °C to 250 °C, preferably 100 °C to 200 °C, depending on the type and composition of the carbon-containing polymer. The duration of heating at the first temperature can vary depending on the amount and size of the mixture, but can be in the range of 1 to 100 minutes, such as 10 to 90 minutes, 20 to 80 minutes, 30 to 70 minutes, 40 to 60 minutes, or in a range constituted by any two of the aforementioned minute values. After heating at the first temperature, the mixture can be heated at a second temperature that is sufficient to convert the carbon-containing polymer to carbon (i.e. pyrolysis). This can result in the formation of a carbon layer on the surface of the particles, which can improve the electrical conductivity and stability of the electrode material. Optionally, the second temperature can be in the range of 300 °C to 1500 °C, depending on the type and composition of the polymer and precursor material. In some embodiments, the temperature range may be from 300 °C to 1200 °C, from 300 °C to 900 °C, from 500 °C to 800 °C, from 600 °C to 800 °C, or in a range constituted by any two of the aforementioned temperature values. The heating may comprise a ramped increase intemperature, for example, at a heating rate of 1 °C to 10 °C / min, 2 °C to 8 °C / min, 3 °Cto 7 °C / min, 4 °C to 6 °C / min, or about 5 °C / min. The temperature may be ramped untilthe desired temperature is reached, after which the heating may be maintained at thattemperature. The duration of heating at the second temperature can vary depending onthe amount and size of the particles in the mixture but can be in the range of 1 to 500minutes, such as 10 to 450 minutes, 50 to 400 minutes, 100 to 350 minutes, 200 to 350minutes, 250 to 350 minutes, or in a range constituted by any two of the aforementionedminute values. In some embodiments, the first heating temperature may be dispensed with and themixture heated at the second heating temperature, or ramped temperature, only.At least part of the carbon-containing polymer is converted to elemental carbon duringheating at the second temperature. For example, at least part of the carbon-containing polymer is converted to sp2hybridized carbon, which can have a higher electrical conductivity and a lower resistance than other forms of carbon. The conversion of the carbon-containing polymer to sp2carbon can be influenced by the temperature and duration of heating at the second temperature. At least part of the sp2carbon can be graphitic, in which it can be described as “graphitic sp2hybridised carbon” or “networkedsp2 hybridised carbon". Graphitic carbon encompasses forms of carbon which includegraphene, carbon nanotubes, graphite, graphene char, and other forms of carbon in whichregions of honeycomb arrangements of sp2carbon atoms exist. At least part of the polymercan be converted to a graphene-like honeycomb network. The sp2 carbon, and degree ofconversion thereto, can be detected by Raman spectroscopy. As shown in Figure 3, the characteristic peak signals occur at around 1300-1375 cm-1(depending on incident Ramanlaser wavelength) (the “D peak”) and ~1590 cm-1 (the “G peak”). The existence, energy,width and relative intensities of these peaks permit an analysis of the presence and natureof the sp2 carbon in the material. The G peak arises from an asymmetric stretch in sp2bonded carbon networks (such as bonds in graphite) and the D peak arises from a breathing vibration of a graphitic hexagonal ring. As such, their presence in Ramantogether evidence the formation of graphitic sp2 carbon. The D / G ratio can be used toqualitatively indicate the amount of disorder. The width of the G peak is another indicator of disorder (narrower = less disorder) that correlates with higher conductive carbons. After carbothermal reduction with a polymer, the presence of strong D and G peaks indicatesconversion of the polymer carbon to graphitic sp2 carbon. An analytical method that canbe used to detect sp2 carbons by Raman spectroscopy has been published in Ferrari et al,Raman spectroscopy as a versatile tool for studying the properties of graphene, NatureNanotech 8, 235–246 (2013), and Ferrari et al, Interpretation of Raman spectra ofdisordered and amorphous carbon, Phys. Rev. B 61, 14095 (2000), both of which areincorporated herein by reference. The thickness of the coating on the particles or agglomerates of metal compound may be less than 100 nm, less than 75 nm, less than 50 nm, less than 20 nm, less than 10 nm, or in a range between any two of the aforementioned values. Preferably the coating has athickness of less than 10 nm. Measurement of the thickness can be performed bytransmission electron microscopy (TEM), analysis of a TEM image.The mixture may further comprise particulate carbon in addition to the carbon-containingpolymer. The particulate carbon may be any form of carbon that has a small size and a high surface area, such as carbon black, activated carbon, carbon nanotubes, graphene, or a combination thereof. The particulate carbon may have an average particle size, asmeasured by laser diffraction analyser, of less than 1 μm, such as less than 500 nm, lessthan 200 nm, less than 100 nm, or less than 50 nm. The particulate carbon may have aBrunauer-Emmett-Teller (BET) surface area of greater than 5 m2 / g, such as greater than10 m2 / g, 50 m2 / g, greater than 100 m2 / g, greater than 200 m2 / g, greater than 500 m2 / g,greater than 1000 m2 / g, or a combination thereof, or in a range between any two of theaforementioned values. The particulate carbon may be C65, which has a surface area ofaround 65 m2 / g, or C45, which has a surface area of around 45 m2 / g. Brunauer-Emmett-Teller (BET) surface area analysis is a multi-point measurement of an analyte's specific surface area (m2 / g) through gas adsorption analysis, where an inert gas such as nitrogen is continuously flowed over a solid sample, or the solid sample is suspended in a defined gaseous volume. The particulate carbon may be added to the mixture before, during, or after the addition of the carbon-containing polymer. The amount of the particulate carbonmay range from 0.1 wt% to 50 wt%, such as 2% to 50%, 2.5% to 50%, 5% to 50%,2.5% to 20%, 0.1 wt% to 20 wt%, 0.5 wt% to 15 wt%, 1 wt% to 10 wt%, 2 wt% to 8 wt%, 3 wt% to 6 wt%, 4 wt% to 5 wt%, or in a range constituted by any two of the aforementioned weight percentages, based on the combined weight of the polymer and particulate carbon. Preferably, the amount of particulate carbon is from 2.5% to 20%,more preferably from 5% to 20%, based on the combined weight of the polymer andparticulate carbon. The particulate carbon can act as a conductive filler that enhances the electrical conductivity and stability of the electrode material. The particulate carbon can connect the metal particles together into an interconnected network that facilitates the transport of electrons within the material. The particulate carbon can also improve the mechanical strength and integrity of the electrode material by bridging the gaps between the metal particles and reducing stress concentration. The particulate carbon can furtherincrease the specific capacity and rate performance of the electrode material. Importantly,the particulate carbon can improve the tap density and compressibility of the carbon-coated metal-containing compound, as shown in Figures 29 to 26. Higher tap density andhigher compressibility are desirable properties because they produce electrode material ofa higher energy density. It is unexpected that the addition of particulate carbon to thepolymer mixture would enhance tap density or compressibility because particulate carbon has a high surface area and low density. For example, the bulk density of particulate carbonis typically in the range of about 0.05 to 0.25 g / cc. Therefore, it is unexpected that thecombination of such a light material with dense material such as a polymer would produce a higher tap density. Furthermore, a large increase in tap density is usuallyassociated with a reduction in specific capacity. Therefore, it is also advantageouslyunexpected that the combination of a polymer and particulate carbon in the coating wouldresult in a high increase in tap density without a significant reduction in specific capacity(as shown in Figures 29 and 30, and in Figures 33 and 34). The optimum quantity ofparticulate carbon in the coating is from 10% to 30%, from 15% to 25%, or about 20%, based on the combined weight of the polymer and particulate carbon. Without wishing tobe bound by theory, a possible explanation for this “sweet spot” may be that it is the pointat which nucleation is optimised. At lower quantities of particulate carbon, there may beinsufficient nucleation sites to which the polymer can attach, whereas at higher quantitiesof particulate carbon there may be insufficient polymer to nucleate around the carbonparticles. The method may use a stoichiometric excess of carbon in the reaction with respect to the metal precursor compound(s). The carbon may originate from the polymer and / or from other carbon sources such as the particulate carbon. The excess carbon may be based onthe assumption of a C --> CO carbothermal reaction. The method may provide a carbon-coated metal-containing compound having a total carbon content of from 0.5 to 10 %, 0.5 to 5 %, 1 to 5%, 1 to 4%, or 3 to 4% by weight carbon (with the remaining wt% made up of the metal-containing compound). Preferably, the carbon-coated metal-containing compound has a total carbon content of from 1 to 5% by weight carbon. The present invention extends to an electrode active material containing the carbon-coated metal-containing compound made according to the above method. The electrode active material can form a cathode of a battery, such as a secondary or rechargeable battery. The battery can preferably be an alkali metal ion battery, such as a lithium-ion battery or a sodium-ion battery. Rechargeable batteries typically comprise an anode, a cathode, a separator, and anelectrolyte. The anode is the negative electrode that releases electrons to an externalcircuit during discharge and the cathode is the positive electrode that receives electronsfrom the external circuit during discharge. The separator is typically a porous membranethat prevents direct contact between the anode and the cathode while allowing the passageof ions therebetween. The electrolyte is a liquid, solid, or gel medium that facilitates thetransport of ions between the anode and the cathode. The cathode material can be applied to a current collector to form a cathode layer. The current collector can be any electrically material that can collect the electrons from the cathode and deliver them to the external circuit. Examples of suitable current collectors include, but are not limited to, aluminium, nickel, stainless steel, copper, carbon, or a combination thereof. The current collector can have any shape or form, such as a foil, a sheet, a mesh, a wire, a rod, or a tube. The cathode layer can be coated, laminated, pressed, or bonded to the current collector by any suitable method, such as spray coating, dip coating, slot-die coating, doctor blade coating, roll-to-roll coating, electroplating, sputtering, thermal evaporation, chemical vapor deposition, physical vapor deposition, or a combination thereof. The thickness of the cathode layer can vary depending on the desired capacity and power density of the battery, and can range from 1 μm to 500 μm, such as 5 μm to 200 μm, 10 μm to 100 μm, 20 μm to 80 μm, 30 μm to 60 μm, 40 μm to 50 μm, or in a range constituted by any two of the aforementioned values. Similarly, the anode material can be applied to a current collector to form an anode layer. The current collector can be any electrically conductive material that can collect the electrons from the external circuit and deliver them to the anode. Examples of suitable current collectors include, but are not limited to, copper, nickel, stainless steel, aluminium, carbon, or a combination thereof. The current collector can have any shape or form, such as a foil, a sheet, a mesh, a wire, a rod, or a tube. The anode layer can be coated, laminated, pressed, or bonded to the current collector by any suitable method, such as spray coating, dip coating, slot-die coating, doctor blade coating, roll-to-roll coating, electroplating, sputtering, thermal evaporation, chemical vapor deposition, physical vapor deposition, or a combination thereof. The thickness of the anode layer can vary depending on the desired capacity and power density of the battery, and can range from 1 μm to 500 μm, such as 5 μm to 200 μm, 10 μm to 100 μm, 20 μm to 80 μm, 30 μm to 60 μm, 40 μm to 50 μm, or in a range constituted by any two of the aforementioned values. The electrolyte can comprise a solvent, a salt, and optionally an additive. The solvent can be any organic or inorganic compound that can dissolve the salt and provide sufficient conductivity and stability for the battery operation. Examples of suitable solvents include, but are not limited to, ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, gamma-butyrolactone, tetrahydrofuran, 2- methyltetrahydrofuran, dimethoxyethane, diethoxyethane, sulfolane, acetonitrile, dimethylformamide, dimethylsulfoxide, water, or a combination thereof. The salt can be any alkali metal salt that can provide the cations for the battery operation. Examples of suitable salts include, but are not limited to, lithium hexafluorophosphate, lithium perchlorate, lithium tetrafluoroborate, lithium bis(trifluoromethanesulfonyl)imide, lithium triflate, lithium bis(oxalato)borate, lithium hexafluoroarsenate, lithium iodide, sodium hexafluorophosphate, sodium sodium tetrafluoroborate, sodium bis(trifluoromethanesulfonyl)imide, sodium triflate, sodium bis(oxalato)borate, sodium hexafluoroarsenate, sodium iodide, or a combination thereof. The additive can be any compound that can improve the performance and safety of the battery, such as by enhancing the conductivity, stability, and compatibility of the electrolyte, or by forming a protective layer on the electrode surface. The amount of the solvent, the salt, and the additive can vary depending on the desired viscosity, conductivity, and electrochemicalproperties of the electrolyte.The invention will now be described in further detail with reference to the following non- limiting examples. EXAMPLES Synthesis General Method 1. The starting materials are intimately mixed in the correct stoichiometric proportionsand pressed into a pellet. 2. The resulting pelletized mixture is placed in a crucible that is then placed inside afurnace under an inert atmosphere at a furnace temperature of between 300°C and 900°C until a product is formed. 3. The product is allowed to cool under an inert atmosphere before grinding to apowder. Abbreviationsxs = excess over the stoichiometric reactionRMM = relative molecular mass Product Analysis using powder X-ray Diffraction (XRD) Analysis by XRD was conducted using a Bruker D2 Phaser powder XRD diffractometer to confirm that the desired target materials had been prepared, to establish the phase purity of the product, and to determine the type of impurities that may be present. The XRD operating conditions are as follows: X-ray source: CuKα X-ray wavelength: 1.5418 ÂTypical 2θ range: 2θ = 10 to 65o with a 0.0202 degrees 2θ step sizeTap and Compressed DensityFor tap density measurements, the volume of a ~3.5 g sample was measured after 200taps in a 10 mL cylinder. The exact sample mass was divided by the volume.For compressed density measurement, the volume of a ~2.5 g pellet formed under2500psi in a 20 mm die was measured after the die pressure was removed. The exactpellet mass was divided by the pellet volume. Electrochemical Results The target materials were tested in metallic lithium half cells which can be made using thefollowing procedure. The materials synthesized (active materials) were made into positiveelectrodes. The positive electrode was prepared by solvent casting a slurry of the activematerial, conductive carbon, binder and binder solvent. The conductive carbon used wasC65 (Imerys). PVdF-HFP co-polymer (Sigma-Aldrich) was used as the binder and acetonewas employed as the binder solvent. The slurry was then cast into a glass plate and a free-standing electrode was formed as the solvent evaporates. The electrode was then driedfurther at 80oC in an oven in an air atmosphere. The dried positive electrode composition comprised 80 % active material, 8 % C65 carbon and 12 % PVdF-HFP binder. Optionally an aluminium current collector or a carbon coated aluminium current collector may be used as the contact to the active material. Metallic lithium was used as the negative electrode material. Optionally a copper current collector may be used as the contact to the lithium material. The electrolyte comprises a battery grade 1M solution of LiPF6 in ethylene carbonate (EC) and diethyl carbonate (DEC) in a weight ratio of 1:1. Alternatively an electrolyte may comprise a battery grade 1M solution of LiPF6 in ethylene carbonate (EC) and propylene carbonate (PC). There may also be electrolyte additives. A glass fibre separator (Whatman GF / A grade) or a porous polypropylene or porous polyethylene (e.g., Celgard 2400) wetted by the electrolyte, was interposed between the positive and negative electrodes. The cells were tested as follows. The cells were tested at room temperature. For constant current cycling, the cell was cycled at a given (low rate) current density between pre-setvoltage limits (five constant current 0.1C cycles followed by five constant current 1Ccycles, with all cycles between 2.5-4.2 V). A commercial battery cycler was used (forexample, from Neware®, China). On charge, lithium ions were extracted from the cathode active material while on subsequent discharge lithium ions were re-inserted into thecathode active material. This method provided a voltage (versus the Li reference potential)versus specific capacity profile for the active material under investigation. This approach may be extended over multiple charge-discharge cycles to provide a long-term cycle stability test. Alternatively, the cells were tested using the electrochemical voltage spectroscopy (EVS) technique, as described in (1) Barker et al, Acta, vol. 41, No. 16, pp. 2639-2646, 1996; (2) Barker et al, Synthetic Metals, 28 (1989), D127-D134, and (3) Barker,Electrochimica Acta, vol. 40, no. 11, pp. 1603-1608, 1995, all of which are incorporatedherein by reference. EVS is a voltage step method which provides a high-resolution approximation to the open circuit voltage curve (versus the Li reference potential) for the electrochemical system under investigation. Similarly to the constant current testing, thisEVS method provided a voltage (versus the Li reference potential) versus specific capacityprofile for the active material under investigation. The complementary differential capacitydata had been demonstrated to allow effective characterisation of polarization, order-disorder and structural ordering phenomena in intercalation systems. The EVS testing was carried out using custom software and commercial voltage generator (Advantest) and current monitoring equipment (Hewlett Packard). Raman SpectroscopyThe incident laser wavelength was 785 nm. The laser power was 3 mW. 25 spectra werecollected over an area 80x80 µm at points spaced by 20 µm in x and y (the map of points)using a Renishaw Raman spectrometer. The intensity ratio of D and G peaks (D / G) was calculated for each Raman spectrum by first identifying D and G peak maxima by a localmaximum finding algorithm. The average and standard deviation of D / G for all points inthe map was reported. COMPARATIVE EXAMPLE 1 Using Particulate Carbon only (C65). LiH2PO4 / Fe2O3 / C65 particulate carbon Synthesis Number: R1001 Material Synthesis Synthesis Stoichiometric Reaction:LiH PO + 0.5 Fe O + 0.5 24 2 3 0.5 CO2Synthesis Precursor Recipe: LiH2PO4 [RMM = 103.9 g / mol] (g): 1.039 g Fe2O3[RMM = 159.7 g / mol] (g): 0.7985 g Carbon: C65; 0.12 g Mixing Conditions: McCrone Micronizer, 20 mins Agate Media; Sample pelletized. Furnace Ramp rate, Temperature, Dwell, Ambient gas: 5oC / min, 725oC, 5 hours, N2 By design an excess of the carbon source (in this case, particulate carbon C65) was used to ensure that a composite material product was formed comprising the active material and the excess carbon.Figure 4 shows the XRD data for the sample of Comparative Example 1. From inspectionwe detected that the sample was close to phase pure LiFePO4.Figure 5 shows the constant current data for the LiFePO4cathode active material of Comparative Example 1. As shown in Figure 5, during the charge process (lithium extraction from the LiFePO4) a charge equivalent to 115 mAh / g was obtained for the cathode active material. The subsequent discharge process (lithium re-insertion into theLiFePO4) corresponded to a reversible material specific capacity of 107 mAh / g, indicatinga reasonable lithium insertion / extraction cycle. The theoretical specific capacity for LiFePO4is approximately 170 mAh / g (assuming cycling of one lithium ion per LiFePO4formula unit). The 107 mAh / g corresponds to (107 / 170) x 100 % (i.e. an active material utilization of about 63 %). This represents a reasonable overall performance for this LiFePO4 active material. EXAMPLE 1 Using HMPE only (HMPE = high modulus polyethylene powder). Li2CO3 / Anhydrous FePO4 / HDPE / 750oC Synthesis Number: R1053 Material Synthesis Synthesis Stoichiometric Reaction:0.5 Li2CO3 + FePO4 + 0.5 0.5 CO2 + 0.5 COSynthesis Precursor Recipe: RMM = Relative Molecular Mass Li2CO3[RMM = 73.9 g / mol] (g): 0.37 gAnhydrous FePO4 TSAKER NE-GR-6 [RMM = 150.8 g / mol] (g): 1.508 gHMPE Powder: 0.14 g. No particulate carbonMixing Conditions: e.g., McCrone Micronizer, 30 mins Agate Media; Sample pelletized.HMPE Powder = 0.209 g. Pellet mix 4.5 g: Li2CO3= 0.798 g, FePO4= 3.252 g, HDPE = 0.451 g Furnace Ramp rate, Temperature, Dwell, Ambient gas: 5oC / min, 750oC, 8 hours, N2Figure 6 shows the XRD data for the sample R1053. From inspection we detected that thesample was close to phase pure LiFePO4. There were no XRD reflections from extraneous impurities.Figures 7 and 8 show the Electrochemical Voltage Spectroscopy data for the LiFePO4sample R1053. Figure 7 shows the EVS voltage profile for the LiFePO4cathode active material R1053 (made using Li2CO3, FePO4and HDPE). Figure 7 shows the EVS voltage profile (electrode potential versus specific capacity) for cycle 3. The current density cut-off at each EVSvoltage step was set so that the EVS cycle was equivalent to a constant current cycle rateof approximately C / 10 assuming a reversible specific capacity of 150 mAh / g for the activematerial (where a 1 C rate is a rate equivalent to a 1-hour charge and a 1-hour discharge).Referring to Figure 7, during the charge process (lithium extraction from the LiFePO4) a charge equivalent to 180 mAh / g was obtained for the cathode active material. This is in excess of the theoretical specific capacity for LiFePO4 and this phenomenon was due to some electrolyte degradation (oxidation) processes during cell charge. The subsequentdischarge process (lithium re-insertion into the LiFePO4) corresponded to a reversiblematerial specific capacity of 152 mAh / g, indicating an excellent lithium insertion / extraction cycle. The theoretical specific capacity for LiFePO4 is approximately 170 mAh / g (assuming cycling of one lithium ion per LiFePO4 formula unit). Thus the 152 mAh / g corresponds to (152 / 170) x 100 % (i.e. an active material utilization of about 89 %). This represents excellent overall performance for this LiFePO4active material. Referring to Figure 8 we denote the differential capacity data for LiFePO4 sample R1053. The generally symmetrical nature of the differential capacity data on charge (above the x axis) and the corresponding differential capacity data on discharge (below the x axis) indicates the excellent reversibility of the lithium extraction / insertion behaviour in this LiFePO4 material. EXAMPLE 2Using HMPE only (HMPE = high modulus polyethylene powder).LiH2PO4 / FeOOH / excess HMPE / 725°CSynthesis Number: R1092 Material Synthesis Synthesis Stoichiometric LiH2PO4 + 1.0 FeOOH + 0.5 C ^ LiFePO4 + 2.0 H2O + 0.5 CONo particulate carbon LiH2PO4[RMM = 103.9 g / mol] = 2.284 g,FeOOH [RMM = 88.9 g / mol] = 1.954 g,HMPE Powder = 0.383 gMixing Conditions: MM500, 30 Hz, 30 mins; Sample pelletized. Polyethylene Powder HMPE35A (Goonvean) (HMPE = 86 w / o carbon = 1.0 x (0.12 / 0.86) = 0.1744 g. Furnace Ramp rate, Temperature, Dwell, Ambient gas: 5o / min, 725oC, 8 hours, N2Figure 9 shows the XRD data for the sample R1092. From inspection we detected that thesample was close to phase pure LiFePO4. There were no XRD reflections from extraneous impurities. Figures 10 and 11 show the Electrochemical Voltage Spectroscopy data for the LiFePO4sample R1092. Figure 10 shows the EVS voltage profile for the LiFePO4 cathode active material R1092 (made using LiH2PO4, FeOOH and HMPE). Figure 10 shows the EVS voltage profile (electrode potential versus specific capacity) for cycle 2. The current density cut-off ateach EVS voltage step was set so that the EVS cycle was equivalent to a constant currentcycle rate of approximately C / 10 assuming a reversible specific capacity of 150 mAh / g forthe active material (where a 1 C rate is a rate equivalent to a 1-hour charge and a 1 hourdischarge). As shown in Figure 10, during the charge process (lithium extraction from the LiFePO4) a charge equivalent to 156 mAh / g was obtained for the cathode active material.The subsequent discharge process (lithium re-insertion into the LiFePO4) corresponded toa reversible material specific capacity of 152 mAh / g, indicating an excellent lithium insertion / extraction cycle. The theoretical specific capacity for LiFePO4 is approximately 170 mAh / g (assuming cycling of one lithium ion per LiFePO4 formula unit). Thus the 152 mAh / g corresponds to (152 / 170) x 100 % (i.e. an active material utilization of about 89 %). This represents excellent overall performance for this LiFePO4active material. Referring to Figure 11 we denote the differential capacity data for LiFePO4 sample R1053. The generally symmetrical nature of the differential capacity data on charge (above the x axis) and the corresponding differential capacity data on discharge (below the x axis) indicates the excellent reversibility of the lithium extraction / insertion behaviour in this LiFePO4material. EXAMPLE 3Using HMPE (HMPE = high modulus polyethylene powder) and a particulate carbon.Ensaco250G is a particulate carbon fromLi2CO3 / anhydrous FePO4 / ENSACO 250G / HMPE (A mix of polymer + particulate carbon).Synthesis Number: R1100 Material Synthesis Synthesis Stoichiometric Reaction:0.5 Li2CO3 + FePO4 + 0.5 C ^ LiFePO4 + 0.5 CO2 + 0.5 COTarget amount = 0.01 mol Li2CO3[RMM = 73.9 g / mol] (g): 0.37 g Anhydrous FePO4 TSAKER NE-GR-6. [RMM = 150.8 g / mol] (g): 1.508 g Carbon [RMM = 12 g / mol] (% mass excess = 100%) CARBON 1: ENSACO 250G: 0.06 gCARBON 2: HMPE35A (Goonvean): (PE = 86 w / o carbon = 0.5 x (0.12 / 0.86) = 0.0698 g Mixing Conditions: MM500, 30 mins, 30 Hz; Sample pelletized. Furnace Ramp rate, Temperature, Dwell, Ambient gas: 5o / min, 725oC, 5 hours, N2 Figure 12 shows the XRD data for the sample R1100. From inspection we detect that the sample is close to phase pure LiFePO4. There are no XRD reflections from extraneous impurities. Figures 13 and 14 show the Electrochemical Voltage Spectroscopy data for the LiFePO4sample R1100. Referring to Figure 13, during the charge process (lithium extraction from the LiFePO4) a charge equivalent to 176 mAh / g was obtained for the cathode active material. This is in excess of the theoretical specific capacity for LiFePO4 and this phenomenon is due to some electrolyte degradation (oxidation) processes during cell charge. The subsequent discharge process (lithium re-insertion into the LiFePO4) corresponds to a reversible material specific capacity of 160 mAh / g, indicating an excellent lithium insertion / extractioncycle. The theoretical specific capacity for LiFePO4 is approximately 170 mAh / g (assumingcycling of one lithium ion per LiFePO4 formula unit). Thus the 160 mAh / g corresponds to (160 / 170) x 100 % (i.e. an active material utilization of about 93 %). This represents excellent overall performance for this LiFePO4active material.Referring to Figure 14, we denote the differential capacity data for LiFePO4 sample R1100.The generally symmetrical nature of the differential capacity data on charge (above the x axis) and the corresponding differential capacity data on discharge (below the x axis) indicates the excellent reversibility of the lithium extraction / insertion behaviour in this LiFePO4material. EXAMPLE 4Using HMPE (HMPE = high modulus polyethylene powder) and a particulate carbon. Ensaco250G is a particulate carbon from IMERYSLi2CO3 / Anhydrous FePO4 / ENSACO 250G / HMPESynthesis Number: R1110 Material Synthesis Synthesis Stoichiometric Reaction:0.5 Li2CO3 + FePO4 + 0.5 ^ + 0.5 CO2 + 0.5 CO Target amount = 0.01 mol Li2CO3 [RMM = 73.9 g / mol] (g): 0.37 g Anhydrous FePO4 TSAKER NE-GR-6. [RMM = 150.8 g / mol] (g): 1.508 g Carbon [RMM = 12 g / mol] (% mass excess = 100%) CARBON 1: ENSACO 250G: 0.06 gCARBON 2: HMPE35A (Goonvean): (PE = 86 w / o carbon = 0.5 x (0.12 / 0.86) = 0.0698 g Mixing Conditions: MM500, 30 mins, 30 Hz; Sample pelletized. Pellet mix 4.5 g: Li2CO3= 0.825 g, FePO4= 3.363 g, ENSACO = 0.134 G, PE = 0.1556 g Furnace Ramp rate, Temperature, Dwell, Ambient gas: 5o / min, 725oC, 5 hours, N2 Figure 15 shows the XRD data for the sample R1110. From inspection we detect that the sample is close to phase pure LiFePO4. There are no XRD reflections from extraneous impurities. Figures 16 and 17 show the Electrochemical Voltage Spectroscopy data for the LiFePO4sample R1110. Referring to Figure 16, during the charge process (lithium extraction from the LiFePO4) a charge equivalent to 170 mAh / g was obtained for the cathode active material. This is the theoretical specific capacity for LiFePO4. The subsequent discharge process (lithium re- insertion into the LiFePO4) corresponds to a reversible material specific capacity of 160 mAh / g, indicating an excellent lithium insertion / extraction cycle. The theoretical specific capacity for LiFePO4 is approximately 170 mAh / g (assuming cycling of one lithium ion perLiFePO4 formula unit). Thus the 160 mAh / g corresponded to (160 / 170) x 100 % (i.e. anactive material utilization of about 93 %). This represents excellent overall performance for this LiFePO4active material. Referring to Figure 17 we denote the differential capacity data for LiFePO4sample R1110. The generally symmetrical nature of the differential capacity data on charge (above the x axis) and the corresponding differential capacity data on discharge (below the x axis) indicates the excellent reversibility of the lithium extraction / insertion behaviour in this LiFePO4material. EXAMPLE 5 Using expanded polystyrene (PS) waste material only as the carbon source. Taken from packing material. We have also done this be dissolving the PS in acetone. Li2CO3 / Anhydrous FePO4 / xsPS / 725oC Synthesis Number: R1083 Material SynthesisSynthesis Stoichiometric Reaction: 0.5 Li2CO3 + FePO4 + 0.5 ^ LiFePO4 + 0.5 CO2 +0.5CO Target amount = 0.01 mol Li2CO3 [RMM = 73.9 g / mol] (g): 0.37 g Anhydrous FePO4TSAKER NE-GR-6. [RMM = 150.8 g / mol] (g):1.508 gPolystyrene (PS) (waste expanded PS packaging material): 0.133 g (see below).No particulate carbon Mixing Conditions: MM50015 mins 25 Hz. Waste Polystyrene (Expanded) (PS = 90 w / o carbon = (0.12 / 0.90) = 0.200 g. (150 % excess carbon) Pellet mix 4.5 g: Li2CO3 = 0.825 g, FePO4 = 3.363 g, PS = 0.450 g Furnace Ramp rate, Temperature, Dwell, Ambient gas: 5o / min, 725oC, 5 hours, N2 Figure 18 shows the XRD data for the sample R1083. From inspection we detect that the sample is close to phase pure LiFePO4. There are no XRD reflections from extraneous impurities. Figures 19 and 20 show the Electrochemical Voltage Spectroscopy data for the LiFePO4sample R1083. Referring to Figure 19, during the charge process (lithium extraction from the LiFePO4) a charge equivalent to 166 mAh / g was obtained for the cathode active material. This is the theoretical specific capacity for LiFePO4. The subsequent discharge process (lithium re- insertion into the LiFePO4) corresponds to reversible material specific capacity of 148 mAh / g, indicating an excellent lithium insertion / extraction cycle. The theoretical specific capacity for LiFePO4 is approximately 170 mAh / g (assuming cycling of one lithium ion per LiFePO4 formula unit). Thus the 148 mAh / g corresponds to (148 / 170) x 100 % (i.e. an active material utilization of about 87 %). This represents excellent overall performance for this LiFePO4active material.Referring to Figure 20, we denote the differential capacity data for LiFePO4 sample R1083.The generally symmetrical nature of the differential capacity data on charge (above the x axis) and the corresponding differential capacity data on discharge (below the x axis) indicates the excellent reversibility of the lithium extraction / insertion behaviour in this LiFePO4 material. EXAMPLE 6 Using PET (polyethylene terephthalate) powder material only as the carbon source. PET may be a waste material from e.g. waste water bottles. Li2CO3 / Anhydrous FePO4 / xsPET / 725oC Synthesis Number: R1087 Material Synthesis Synthesis Stoichiometric Reaction:0.5 Li2CO3 + FePO4 + 0.5 C ^ LiFePO4 + 0.5 CO2 + 0.5COLi2CO3[RMM = 73.9 g / mol] (g): 0.37 g Anhydrous FePO4TSAKER NE-GR-6. [RMM = 150.8 g / mol] (g): 1.508 g Polyester (PET) powder: 0.29 g (see below). No particulate carbon Mixing Conditions: MM500 ZrO2media 30 mins at 30 Hz TWO H Polyester (PET) Powder TCP5010 (PET = 62.5 w / o carbon = (0.18 / 0.625) = 0.29 g. Pellet mix 4.5 g: Li2CO3 = 0.805 g, FePO4 = 3.281 g, PET(TWO-H) = 0.620 g Furnace Ramp rate, Temperature, Dwell, Ambient gas: 5o / min, 725oC, 5 hours, N2Figure 21 shows the XRD data for the sample R1087. From inspection we detected thatthe sample was close to phase pure LiFePO4. There were no XRD reflections from extraneous impurities. Figures 22 and 23 show the Electrochemical Voltage Spectroscopy data for the LiFePO4sample R1087.Referring to Figure 22, during the charge process (lithium extraction from the LiFePO4) acharge equivalent to 170 mAh / g was obtained for the cathode active material. This is the theoretical specific capacity for LiFePO4. The subsequent discharge process (lithium re- insertion into the LiFePO4) corresponds to a reversible material specific capacity of 145 mAh / g, indicating an excellent lithium insertion / extraction cycle. The theoretical specific capacity for LiFePO4is approximately 170 mAh / g (assuming cycling of one lithium ion per LiFePO4 formula unit). Thus the 145 mAh / g corresponds to (145 / 170) x 100 % (i.e. an active material utilization of about 85 %). This represents excellent overall performance for this LiFePO4active material. Referring to Figure 23 we denote the differential capacity data for LiFePO4 sample R1087. The generally symmetrical nature of the differential capacity data on charge (above the x axis) and the corresponding differential capacity data on discharge (below the x axis) indicates the excellent reversibility of the lithium extraction / insertion behaviour in this LiFePO4material. EXAMPLE 7 Using devulcanized type rubber waste powder material only as the carbon source. Li2CO3 / Anhydrous FePO4 / Tyre Rubber Synthesis Number: R1119 Material Synthesis Synthesis Stoichiometric Reaction:0.5 Li2CO3 + FePO4 + 0.5 0.5 CO2 + 0.5COLi2CO3[RMM = 73.9 g / mol] (g): 0.37 g Anhydrous FePO4TSAKER NE-GR-6. [RMM = 150.8 g / mol] (g): 1.508 g Recycled De-vulcanized Tyre Rubber Powder: 0.24 g (see below). No particulate carbon Mixing Conditions: New zirconia mill, 15 mins, 30 Hz; Sample pelletized Tyre Rubber Powder (Rubber = approx. 50 w / o carbon = (0.12 / 0.5) = 0.24 gPellet mix 4.5 g: Li2CO3 = 0.825 g, FePO4 = 3.363 g, Tyre rubber powder = 0.535 gFurnace Ramp rate, Temperature, Dwell, Ambient gas: 5o / min, 725oC, 5 hours, N2Figure 24 shows the XRD data for the sample R1119. From inspection we detected thatthe sample was close to phase pure LiFePO4. Figure 25 shows the constant current data for the LiFePO4cathode active material R1119 (made using waste type rubber). Figure 25 shows the voltage profile (electrode potential versus specific capacity) for cycle 2. The current density was set to an equivalent rate of C / 10 assuming a reversible specific capacity of 150 mAh / g for the active material (wherea 1 C rate is a rate equivalent to a 1-hour charge and an hour discharge).Referring to Figure 25, during the charge process (lithium extraction from the LiFePO4) a charge equivalent to 140 mAh / g was obtained for the cathode active material. The subsequent discharge process (lithium re-insertion into the LiFePO4) corresponds to a reversible material specific capacity of 120 mAh / g, indicating a reasonable lithium insertion / extraction cycle. The theoretical specific capacity for LiFePO4is approximately 170 mAh / g (assuming cycling of one lithium ion per LiFePO4 formula unit). This the 120 mAh / g corresponds to (107 / 170) x 100 % (i.e. an active material utilization of about 71 %). This represents reasonable overall performance for this LiFePO4 active material. EXAMPLE 8 Using polypropylene (PP) powder material only as the carbon source. Polypropylene maybe derived from waste sources such as waste milk containers.Li2CO3 / Anhydrous FePO4 / PP Synthesis Number: R1035 Material Synthesis Synthesis Stoichiometric Reaction:0.5 Li2CO3 + FePO4 + 0.5 0.5 CO2 + 0.5COLi2CO3 [RMM = 73.9 g / mol] (g): 0.37 g Anhydrous FePO4TSAKER NE-GY-6. [RMM = 150.8 g / mol] (g): 1.508 g Polypropylene powder: 0.14 g (see below). 100% excess carbon. Mixing Conditions: e.g., McCrone Micronizer, 30 mins Agate Media; Sample pelletized. Polypropylene Powder TWO-H PP (PP = 86 w / o carbon = (0.12 / 0.86) = 0.14 g. Pellet mix 4.5 g: Li2CO3 = 0.825 g, FePO4 = 3.363 g, PP = 0.312 g Furnace Ramp rate, Temperature, Dwell, Ambient gas: 5o / min, 725oC, 5 hours, N2Figure 26 shows the XRD data for the sample R1035. From inspection we detect that the sample is close to phase pure LiFePO4. Figure 27 shows the constant current data for the LiFePO4cathode active material R1035 (made using polypropylene powder). 27 shows the voltage profile (electrode potential versus specific capacity) for cycle 2. The current density was set to an equivalent rate of C / 10 assuming a reversible specific capacity of 150 mAh / g for the active material(where a 1 C rate is a rate equivalent to a 1-hour charge and an hour discharge).Referring to Figure 27, during the charge process (lithium extraction from the LiFePO4) a charge equivalent to 139 mAh / g was obtained for the cathode active material. The subsequent discharge process (lithium re-insertion into the LiFePO4) corresponds to a reversible material specific capacity of 126 mAh / g, indicating a reasonable lithium insertion / extraction cycle. The theoretical specific capacity for LiFePO4 is approximately 170 mAh / g (assuming cycling of one lithium ion per LiFePO4formula unit). This the 126 mAh / g corresponds to (126 / 170) x 100 % (i.e. an active material utilization of about 74 %). This represents reasonable overall performance for this LiFePO4 active material. EXAMPLE 9Lithium iron (II) phosphate (LFP) was synthesised from iron (III) oxide and lithium dihydrogen phosphate with polymer and particulate carbon sources according to the following reaction scheme: 0.5 Fe2O3 + 1 LiH2PO4 + N C → LiFePO4 + H2O + 0.5 COwhere N is 0.75 (50% excess carbon).Samples with blends of polymer and particulate carbon (SuperP, Imreys) were prepared as follows: Polymer Excess Polymer proportion [%] Particulate carboncarbon proportion [%] [%] HMPE 50 100, 97.5, 95, 90, 80 0, 2.5, 5, 10, 20PA-6 50 100, 97.5, 95, 90, 90, 50 0, 2.5, 5, 10, 20, 50where HMPE is high modulus polyethylene; PA-6 is polyamide-6. The following steps were carried out: (1) Pre-mix reactants in the following proportions:0.50 mol Fe2O3 79.85 g1.00 mol LiH2PO4 103.93 g0.75 mol C* 9.01 g*where 1.17 g HMPE yields 1.00 g C; 1.57 g PA-6 yields 1.00 g C.(2) Pelletise the powder mixture.(3) Heat the pellet to 725°C at a rate of 5°C / min under N2 atmosphere, then dwell for5 hours.(4) The material is then cooled at a rate of 2°C / min to room temperature.(5) The cooked pellet is then pulverised.Results HMPE, 50% excess: As noted above, Figure 3 illustrates the characteristic peak signals which occur at around 1300-1375 cm-1(the “D peak”) and ~1590 cm-1(the “G peak”), enabling a D / G ratio to be calculated. The D / G ratio for the comparative example (particulate carbon only as setout above) was calculated as 1.48 ± 0.05. For the compositions of Example 9, the D / Gratio was calculated as 1.28 ± 0.02. The strong D and G peaks shown in Figure 3, togetherwith a reduced D / G ratio for example 9 versus the comparative example is a strongindicator of high levels of conversion to sp2carbon.From a visual inspection of Figure 28, the XRD pattern shows a phase pure product. Figure29 shows that the 0.1C 2ndcycle discharge specific capacity for 0% particulate carbonaddition was 160.6 mAh / g. The 2.5% to 20% particulate carbon samples were within arange of 140 to 160 mAh / g in 0.1C 2nd cycle specific discharge capacity indicating nosubstantial loss in specific capacity over the sample without particulate carbon. Figure 30 shows that tap density increased by particulate carbon addition up to 20% particulatecarbon, from 1.18 g / cc (0% particulate carbon) to 1.26 g / cc at 10% and 20% particulatecarbon. Figure 31 shows that the compressed density of the samples was higher for all samples containing particulate carbon than the sample without particulate carbon. Polyamide-6 (PA-6), 50% excess:Figure 32 shows that the LFP produced according to the above method is phase pure.Figure 33 shows that the 0.1C 2nd cycle discharge specific capacity shows that there is nosubstantial loss in specific capacity when particulate carbon is combined with the polymer. Figures 34 and 35 show that, as with the HMPE polymer, the addition of particulate carbon results in an improvement in tap density and compressed density is a mostly linear trend. Figure 36 provides a visual comparison of the samples containing (i) HMPE and particulatecarbon, and (ii) PA-6 and particulate carbon. The HMPE samples have a higher differentialcapacity, but a lower tap density than the PC-6 samples. Other Materials The above synthesis methods may also be used to prepare the following specific compounds: LiFe0.1Mn0.9PO4, LiFe0.2Mn0.8PO4, LiFe0.3Mn0.7PO4, LiFe0.4Mn0.6PO4, LiFe0.5Mn0.5PO4,

Claims

CLAIMS1. A method for producing a carbon-coated metal-containing compound, the methodcomprising the steps of: a) forming a mixture comprising: i) one or more carbon-containing polymer(s); ii) one or more alkali metal precursor compound(s); and iii) one or more metal precursor compound(s) comprising one or moremetals selected from transition metals, non-transition metals and metalloids, wherein the metal in each metal precursor compound has aninitial average oxidation state; and b) heating the mixture to produce a reaction product comprising the carbon-coatedmetal-containing compound; wherein during heating step b) the initial average oxidation state of the one or more metalsin the metal precursor compound is reduced; andwherein at least a portion of the carbon coating comprises sp2 carbons.

2. The method according to claim 1, wherein the metal-containing compound has theformula: AaMb(XcYd)eZf wherein: A is an alkali metal selected from one or more of lithium and potassium; M comprises one or more metals selected from transition metals, non-transition metals, and metalloids; (XcYd)eis at least one first anion; and Z is at least one second anion; wherein a ≥0; b >0; c >0; d ≥0; e >0 and f ≥0; wherein a, b, c, d, e and f are chosen to maintain electroneutrality; wherein X comprises one or more elements selected from titanium, vanadium, chromium, arsenic, molybdenum, tungsten, niobium, manganese, aluminium, selenium, boron, oxygen, carbon, silicon, phosphorus, nitrogen, sulfur, fluorine, chlorine, bromine and iodine; and wherein Y is selected from one or more halides, sulfur-containing groups, oxygen- containing groups and mixtures thereof.

3. The method according to any preceding claim, wherein M is a metal selected from oneor more of titanium, vanadium, niobium, tantalum, hafnium, chromium, molybdenum, tungsten, manganese, iron, osmium, cobalt, nickel, palladium, platinum, copper, silver, gold, zinc, cadmium, aluminium, scandium, yttrium, zirconium, technetium, rhenium, ruthenium, rhodium, iridium, mercury, gallium, indium, tin, lead, bismuth, magnesium, calcium, beryllium, strontium and barium, boron, silicon, germanium, arsenic, antimony and tellurium.

4. The method according to any preceding claim, wherein Z is selected from one or morehalides, hydroxide-containing groups and mixtures thereof.

5. The method according to any preceding claim, wherein X comprises phosphorus.

6. The method according to any preceding claim, wherein (XcYd)e is a PO4 and / or P2O7moiety.

7. The method according to any preceding claim, wherein the metal-containing compoundis selected from one or more of the group consisting of LiFePO4, LiMnPO4, LiCoPO4, LiNiPO4, LiMn0.5Fe0.2Mg0.3PO4, Li3V2(PO4)3, LiMn0.5Fe0.5PO4, LiVPO4F, Li3V(PO4)2, LiVP2O7, LiVOPO4, LiV2O5, VPO4, MoP2O7, MoOPO4, Fe3(PO4)2, LiFeSO4F, LiMnSO4F, Li2Fe2(SO4)3, Li2Fe(SO4)2, KVPO4F, KVOPO4, K3V2(PO4)3, K3V2(PO4)2F3, KFePO4, and KCoPO4.

8. The method according to any of claims 1 to 6, wherein the metal-containing compoundhas the formula: LiMPO4, where M is a metal selected from one or more of manganese, iron, cobalt, nickel, copper, zinc, magnesium, calcium and combinations thereof.

9. The method according to any of claims 1 to 6, wherein the metal-containing compoundis selected from LiFePO4, LiFe1-xMnxPO4, LiFe1-xMgxPO4and LiFe1-x-yMnxMgyPO4. 10.The method according to any of claims 1 to 6, wherein the metal precursor compound is selected from one or more of Fe2O3, Fe3O4, FeOOH, FePO4.xH2O, FePO4, Fe3(PO4)2, FeSO4.xH2O, Fe(NO3)3, Fe(CH3CO2)2, C6H8O7xFe3+.yNH3(ammonium iron (III) citrate), C6H5FeO7(iron (III) citrate) and Fe(C5H7O2)3(iron (III) 2,4-pentanedionate), wherein x, y are ≥0.11.The method according to any preceding claim, wherein the mixture comprises one ormore compounds selected from LiH2PO4, Li3PO4, LiPO3, Li2CO3, Li2SO4, Lithium citrate,Li2HPO4, LiOH, H3PO4, (NH4)2HPO4 and (NH4)H2PO4, preferably LiH2PO4 or Li2CO3, or ahydrate thereof.12.The method according to any preceding claim, wherein the mixture in a) furthercomprises particulate carbon, preferably in an amount of from 2.5% to 50%, or 5% to 20%, based on the combined weight of polymer and particulate carbon.13.The method according to any preceding claim, wherein the heating step b) includesheating the mixture a temperature proximate to or above the melting point of thecarbon-containing polymer. 14.The method according to any preceding claim, wherein the heating step b) comprises heating at a first temperature sufficient to melt the carbon-containing polymer and heating at a second temperature sufficient to convert the carbon-containing polymer to carbon, optionally wherein the first temperature is in the range of 50 °C to 250 °Cand wherein the second temperature is in the range of 300 °C to 1500 °C.15.The method according to claim 14, wherein the first temperature is maintained for aperiod of 1 to 100 minutes and the second temperature is maintained for a period of 1to 500 minutes.16.The method according to claim 14 or 15, wherein at least part of the carbon-containingpolymer is converted to elemental carbon during heating at the second temperature,optionally, wherein at least part of the carbon-containing polymer is converted to sp2carbon. 17.The method according to any preceding claim, wherein the carbon-containing polymer is selected from the group consisting of PE, PP, HMPE, HDPE, LDPE (low densitypolyethylene), HMPP, HDPP, LDPP, PVC, PET, PS, PEG, PVdF, PVdF-HFP, PAN(polyacrylonitrile), PVA, PTFE, polycarbonates, nylon, and combinations thereof,optionally wherein the polymer is in particulate form, optionally wherein the polymeris waste polymer.

18. The method according to any one of claims 1 to 16, wherein the carbon-containingpolymer is an elastomer obtained from rubber, optionally wherein the rubber is tyre rubber, such as de-vulcanized tyre rubber.19.The method according to any preceding claim, wherein the carbon-containing polymeris soluble in a polar solvent, optionally wherein the solvent is acetone or water, optionally wherein the method comprises mixing the polymer in a solvent, followed by evaporating the solvent prior to or during heating.20.The method according to any preceding claim, wherein the carbon-containing polymercomprises a halogen selected from Cl, Br, F, or I. 21.The method according to claim 20, where the carbon-containing polymer is selected from the group consisting of PVdF, PVdF-HFP, poly(chlorotrifluoroethylene), poly(tetrafluoroethylene), and PVC.22.The method according to any preceding claim, further comprising contacting themixture with a reducing gas during heating step b), optionally wherein the reducinggas is selected from CO, H2, and combinations thereof. 23.The method according to any preceding claim, wherein the polymer in the mixture is in particulate form, preferably, wherein the average particle size diameter is less than 20 µm as measured by laser diffraction analyser.24.The method according to any preceding claim, wherein the carbon-coated metal- containing compound has a total carbon content of from 1 to 5% by weight carbon. 25.Use of a polymer in a carbothermal reduction reaction of a metal precursor compound to produce a carbon coated metal-containing compound, wherein at least a portion of the carbon coating comprises sp2carbons.26.Use of a halogenated polymer in a carbothermal reduction reaction of a metal precursorcompound to produce a carbon-coated halogen doped metal-containing compound,wherein at least a portion of the carbon coating comprises sp2carbons.27.The use according to claim 26, where the halogenated polymer is selected from thegroup consisting of PVdF, PVdF-HFP and PVC.28.The use according to any of claims 25 to 27, further comprising using particulatecarbon in the carbothermal reduction reaction.An electrode active material made according to the method of any one of claims 1 to24. A composition comprising LiFePO4 in particulate form prepared according to the method of any one of claims 1 to 24, wherein the particles are at least partially coated with a carbon coating, and wherein at least a portion of the carbon coating comprises sp2carbons. A battery comprising an electrode comprising a carbon-coated metal-containing compound produced according to the method of any one of claims 1 to 24, optionally wherein the battery is a rechargeable battery, optionally wherein the battery is an alkali metal ion battery, such as a lithium ion battery. Use of a carbon-coated metal-containing compound produced according to the method of any one of claims 1 to 24 as an electrode in a rechargeable battery, optionallywherein the battery is an alkali metal ion battery, optionally wherein the battery is alithium ion battery.

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