Use of a material, method of upgrading a material, an upgraded material, a battery anode, and a battery

Abstract

Use of a hydrometallurgically recycled graphite in a battery, for example use of an upgraded hydrometallurgically recycled graphite, and in particular a non-pyrometallurgically upgraded hydrometallurg

Description

Field of the invention The present invention relates to the use of a hydrometallurgically recycled graphite in a battery. The present invention also relates to a method of upgrading a hydrometallurgically recycled graphite as well as an upgraded hydrometallurically recycled graphite perse. The present invention also relates to a battery anode material comprising the recycled graphite material as well as a battery comprising such graphite material or battery anode. The present invention has particular, but not exclusive, application to the sustainable utilisation and recycling of battery materials from recycled batteries (of all chemistries), preferably, but not exclusively, lithium batteries and lithium ion batteries, as well as scrap or waste from battery factories or battery material factories or defective or out of warranty batteries. The present invention has particular, but not exclusive, application to the recycling and manufacture of EV batteries, consumer batteries, and energy stationary storage batteries. The present invention relates to a full circularity model which allows for the re-use of graphite that has already been used in a battery, thereby carrying on the initial imprint of battery properties of the first generation batteries, in a new battery (second generation batteries), thereby significantly improving the environmental impact of using and recycling of batteries. Graphite materials from end-of-life batteries as well as battery factory or battery material factory scrap or waste may be recycled, re-engineered, and upcycled with a reduced carbon footprint and reduced cost compared with virgin materials, such as graphite being imported from across the globe. Background to the invention The need to recycle materials is becoming more important every year with a commitment to develop sustainable green processing technologies for recycling at scale. As the world seeks to defossilize the global energy supply chain in order to meet net-zero goals, the materials that are used to create batteries to power the defossilization of the world’s economy are in ever increasing demand as sourcing of critical minerals and metals become ever more problematic. Although it may continue to be necessary to obtain battery materials from primary sources, it is useful to also obtain battery materials by way of recycling or further processing secondary sources, such as used, defective, out of warranty, or end of life batteries, especially EV batteries. Batteries have a limited lifespan and eventually need to be recycled. The focus of recycling efforts has primarily been in relation to the recovery of metals, such as manganese, cobalt, nickel, and lithium as well as aluminium or copper, from end-of-life batteries since the price of such materials is high and it requires significant amounts of energy to obtain these metals from primary sources, which also generates large amounts of waste. On the other hand, there has been comparatively little focus on the recycling of graphite materials from batteries since such used graphite was unsuitable for re-use in batteries and has instead been used for other purposes, sent to landfill, or burnt for energy recovery. WO2021 / 252433 describes the recycling of spent lithium ion batteries and the treatment of a mixture of anode and cathode materials with sulphuric acid or a mixture of sulphuric acid with another acid at high temperatures, such as 200 to 300°C, to react with any residual aluminium oxide to form aluminium sulphate. The pH of the solution used to treat the mixture of anode and cathode materials must be lower than the pH of the solution which was used to leach metals from the original material obtained from the spent lithium ion batteries, i.e. it must be more acidic. CN111204757 describes washing graphite obtained from a battery with hydrochloric acid and heating to around 200°C for 10 minutes, followed by reaction with a mixture of nitric acid and perchloric acid at 85°C for 120 minutes. CN109678144 describes mixing a residue which includes washing silicon-containing waste graphite with water and subsequently leaching with hydrofluoric acid. Following this, the residue is calcined with sulphuric acid at 250 to 350°C for 6 to 24 hours, and then leached with hydrochloric acid and an oxidizing agents with ultrasonic treatment. The resultant leaching residue is vacuum baked at 1200 to 1800°C. Similarly, CN110828926 describes mixing a mixture of positive active material and negative active material with sulphuric acid at a temperature of 100 to 400°C for 0.5 to 8 hours, and then washing with water. CN11484365 describes a high-temperature acid leaching process which further includes a high-temperature calcination, wet material ball milling, spray drying, and secondary calcination steps. Graphite waste is leached with sulphuric acid and calcined at high temperature to generate high-purity regenerated graphite, which is then mixed with silicon powder, PVP powder, an alcohol, and an NMP reagent. ON 109326843 describes a recycling process for waste battery positive electrode material comprising crushing discharged batteries under an inert gas, removing diaphragm paper by winnowing, carrying out a pyrolysis reaction, then selectively removing iron and aluminium by sorting, crushing again and carrying out a flotation separation, and filtering and drying an anode material. Mixing a dispersant, lithium source powder and water to provide a mixed solution, adding the anode material, steaming and activating at high temperature and pressure, drying and then roasting under oxygen to obtain the regenerated lithium ion battery material. Other techniques rely on calcination of graphite, the use of carbonisation additives to add additional carbon to the graphite, milling, crushing, and microwaving, which all either alter the morphology of the graphite, which is undesirable, or which required large energy inputs over extended periods of time. Whilst existing methods may allow for the recovery of graphite from spent batteries, they use concentrated sulphuric acid as well as high temperatures in excess of 100°C, which increases the amount of energy required in the process and therefore reduces the environmental benefits of recycling. As mentioned, calcination is an energy-intensive process and other existing processes result in a change in the morphology of the graphite, which is undesirable as it is preferable for any recycled graphite to be consistent with primary graphite. There is a need for a simplified less energy-intensive effective purification method to improve the quality and usability of recycled graphite before anode manufacture. The objective is to produce ultra-pure graphite with minimal impurities or contaminants (such as without limitation, without residual metals / metal oxides and other impurities) and without structural changes, suitable for anode for batteries from graphite generated post leaching processes. There is a huge potential for reuse after recycling graphite due to high crystallinity, large specific surface area and good particle size distribution. It is therefore an object of the present invention to mitigate at least some of these problems as well as other known problems with existing methods. Summary of Invention According to a first aspect of the present disclosure, there is provided the use of a hydrometallurgically recycled graphite in a battery. The anode of modern batteries, such as lithium ion batteries, comprises significant amounts of graphite into and from which lithium ions are able to pass during cycling of the battery. The graphite needs to be suitable for such use and it has previously been believed that graphite which has already been used in a battery and recycled is unsuitable for use in a new battery. It has been surprisingly found that this is not the case and that a hydrometallurgically recycled graphite may be used in a battery. The hydrometallurgically recycled graphite may be from any source, but one particular source is described in the Applicant’s co-pending GB application no. GB2401211.4 which describes a suitable material recovery method, the contents of which are hereby incorporated by reference in their entirety. In particular, the Applicant’s co-pending application describes a method of recovering material from a source material comprising one or more target metals, the method including the steps of: a) contacting the source material with water and acid to leach one or more target metals from the source material to form a pregnant leach solution; b) monitoring one or more of: i) foaming, ii) the rate of change of concentration of one or more target metals in the pregnant leach solution, iii) the rate of change of pH, and iv) the initial concentration of one or more target metals to determine when to cease addition of acid such that all target metals have been solubilized and the pH is between 0 and 2.3; c) adding a reducing agent, preferably a peroxide, whilst maintaining the temperature of the pregnant leach solution at 85°C or less and monitoring one or more of: i) foaming, ii) the rate of change of concentration of one or more target metals in the pregnant leach solution, iii) the rate of change of pH, and iv) the initial concentration of one or more target metals in the source material; and the pH is between 1 and 2.3 to determine when to cease addition of reducing agent; d) adding a base to the pregnant leach solution to increase the pH of the pregnant leach solution to around 5 to 5.3 and providing an oxidizing agent to precipitate any intermediary metals or metal compounds, such as copper, aluminium, and iron, from the pregnant leach solution to form a depleted leach solution; e) performing a copper cementation reaction to remove copper from the depleted leach solution if copper is present; and f) recovering one or more target metals from the depleted leach solution to provide a lithium leach solution. Source materials, which preferably contain one or more of manganese, cobalt, nickel, and lithium, such as batteries, mixed hydroxide precipitates, or scrap from battery manufacturing often contain other materials or metals such as aluminium, iron, copper, graphite, and possibly even cadmium. It is desirable to separate these different materials from one another so that the valuable materials may be re-used to form useful materials. Useful materials may include precursors to active electrode materials, cathode or anode active materials for use in batteries, cathode or anode active materials for use in batteries, as well as materials for any other use, such as, for example, speciality and technical material manufacture such as alloys, coatings, composites, alloys, performance additives agrichemical, construction materials, fertilizers, electrical components, and pharmaceutical derivatives. It is possible to leach metals into solution by contacting them with acid. Although a wide variety of acids could be used, for example hydrochloric acid, nitric acid, perchloric acid, hydrobromic acid, organic acids, aqua regia, or mixtures of any thereof, it is preferable to use sulphuric acid due to its availability, price, and suitability for use in a material recovery plant. Preferably, the sulphuric acid is not concentrated sulphuric acid at the point of process. In other words, concentrated sulphuric acid is not what is in contact with the material from which metals are being leached, but dilute acid is instead what is in contact with the material from which metals are being leached. For example the sulphuric acid may be 70% (mass fraction) or less, 60% or less, 50% or less, 40% or less, 30% or less, 20% or less, or 10% or less. In the present context, concentrated sulphuric acid is defined as being greater than 70% (mass fraction). Typical commercially available concentrated sulphuric acid is 96% (mass fraction). Where other acids are used, they will have different parameters for defining whether the acid is concentrated or not. For example, concentrated hydrochloric acid is typically around 20% (mass fraction) or greater. Concentrated typically is defined by the azeotropic minimum water concentration or maximum dissolved in water under reasonably safe manufacturing and transport conditions. The addition of concentrated sulphuric acid leads to the production of hydrogen fluoride gas from fluorinated compounds in the source material, is highly toxic, more volatile, more difficult to handle and more difficult to control in chemical reactions. The amount of acid at the beginning of the leaching step may be around 35%, 30%, 25%, 20%, 15%, 10% (all w / v%) of the acid. As the leaching progresses and uses up the acid, this will drop over time. Staged addition of further acid will at least partially replace any acid which has been used up in the reaction or otherwise lost. It will be appreciated that in step d), the metals may precipitate in metallic form, but not necessarily and may additionally or alternatively precipitate as a compound including the metal. In addition, in step d) some copper may precipitate from solution, although the majority of any copper is removed in a subsequent cementation reaction step. The method includes adding water to the source material and then adding sulphuric acid to leach metals into solution. The addition of water assists in mitigating the amount of HF gas produced. Preferably there is more than 15% (w / v%) water in the various stages of the present disclosure. The disclosure describes an aqueous method of leaching and recovery of materials from a source material. This leaching process generates gases which cause foaming or bubbling, which is indicative of the reaction proceeding. In particular, the reactions generate hydrogen gas which causes bubbling or foaming. Although an anti-foaming agent could be added, it is preferable for one not to be added as this will increase costs, introduce potential contaminants that will ultimately have to be removed, and would also prevent one way of determining when the reaction is complete since no foam would be generated. In steps in which gas is generated which can cause foaming or bubbling, physical countermeasures may be employed. For example, the solution may be recirculated and sprayed on the top of the solution to control the foaming or bubbling. Additionally or alternatively, one or more physical foam breakers, such as a beater or a centrifugal flail, positioned above a liquid line may be used to beat and break any foam on contact. The amount of acid added, preferably sulphuric acid, is preferably greater than the stoichiometric amount required to leach all of the metals from the source material. For example, the amount of sulphuric acid added may be 1.01, 1.02, 1.02, 1.04, 1.05, 1.06, 1.07, 1.08, 1.09, 1.10, 1.11, 1.12, 1.13, 1.14, or 1.15 times the stoichiometric amount. In this way, there is just more than enough acid to leach any valuable metals from the source material, thereby ensuring maximum recovery of the metals. In addition, since it will be necessary to ultimately neutralise the acid, it is desirable to control the amount added in order to avoid unnecessary wastage of acid and neutralisation agent by adding too much acid above the stoichiometric amount. In solution, acid serves as the oxidant for any aluminium, copper, or iron in solution. In the presence of acid, peroxide is a reducing agent for manganese and cobalt oxides, which can then be neutralised by acid. For nickel oxide, the acid serves as a neutralisation agent. The combined acid demand, which is dependent on the chemistry and amount of any leachable species as well as the desired final pH, can be calculated or estimated based on the characteristics of the initial feedstock. By adding slightly more than the stoichiometric amount, it can be assured that all leachable species have been leached into solution. The method includes monitoring the reaction by one or more of foaming, the rate of change of the concentration of one or more target metals in the pregnant leach solution, the rate of change of pH, and the initial concentration of one or more target metals to determine when to cease addition of acid such that all target metals have been solubilized and the pH of the solution is between 0 and 2.3. Since gases are produced when there is an ongoing reaction, monitoring of the foaming can be used to determine when acid addition can be stopped since hydrogen gas will no longer be formed once all of the metals have been leached into solution. Similarly, the method may include monitoring the concentration of one or more target metals, such as manganese, cobalt, nickel, lithium, aluminium, copper, or iron, in the pregnant leach solution since the concentration will increase as long as there is more of the target metal to be leached. Once there is a constant concentration of the metal, taking into account any additional liquid added which would dilute the concentration but not the overall mass of metal in solution, addition of the acid may be ceased. Similarly, since the reaction with any metals will destroy the acid, knowing the rate at which acid is being provided, it is possible to monitor the rate of the change in pH to determine when the acid is no longer being used up in leaching the metals into solution. Furthermore, it is possible to calculate, based on the initial concentration of one or more target metals, how much acid needs to be added and by monitoring the initial concentration of the one or more target metals in a batch, it is possible to ensure that the correct amount of acid is added to leach the metals from the material and to also provide a solution within the given pH range. The method requires that the pH of the pregnant leach solution is between 0 and 2.3 in order to ensure that solubilised metals in solution remain in solution. The method further includes adding a reducing agent, such as a peroxide, preferably hydrogen peroxide or sodium peroxide. Additionally or alternatively, the reducing agent may be sulphur dioxide, or an organic acid, such as oxalic acid, or a mixture of any of the reducing agents mentioned to the pregnant leach solution. Perhaps unexpectedly, the peroxide acts as a reducing agent in this step. Similarly, the sulphur dioxide or organic acid are also selected to serve as reducing agents. The reducing agent is selected so as to be unreactive against the highly acidic environment whilst also limiting the amount of any new or additional metal content into solution. The method includes keeping the temperature at 85°C or less in order to reduce the amount of acid gas, specifically hydrogen fluoride, being produced as this is a dangerous gas and needs to be scrubbed from any waste gas. The method may include keeping the temperature at 75°C or less, 65°C or less, 60°C or less, 55°C or less, 50°C or less, 45°C or less, or less than 50°C. In addition, hydrogen peroxide is susceptible to decomposition at increased temperatures, so using temperatures greater than 85°C would cause the hydrogen peroxide to decompose into oxygen and water without having sufficient time to react and would therefore simply be wasted due to decomposition rather than chemical reaction. The total amount of peroxide added may be calculated as the stoichiometric amount plus a calculated excess. The amount of peroxide, or indeed other reducing agent, added may be 1.01, 1.02, 1.02, 1.04, 1.05, 1.06, 1.07, 1.08, 1.09, 1.10, 1.11, 1.12, 1.13, 1.14, or 1.15 times the stoichiometric amount. It has been found that using a less than stoichiometric amount does not lead to any selectivity regarding target metals and instead causes a loss of efficiency. This step also includes monitoring one or more of foaming, the rate of change of the concentration of one or more target metals in the pregnant leach solution, the rate of change of pH, and the initial concentration of one or more target metals to determine when to cease addition of peroxide / reducing agent. Preferably, the reducing agent, preferably a peroxide, preferably hydrogen peroxide, is added to the solution until the rate of change of pH over time and / or the rate of change of the concentration of one or more target metals tends to a predetermined value, which is preferably zero which indicates that the reaction is complete. The pH must end up between 1 and 2.3 in order to ensure that the metals remains in solution. Acid may be added to control the pH as required. The acid and / or peroxide may be added steadily or in batches. The method is primarily a batch process. The method further includes adding a base subsequent to the completion of the addition of the reducing agent, preferably hydrogen peroxide. The base may be selected from one or more of sodium hydroxide, calcium hydroxide, calcium carbonate, calcium oxide, magnesium carbonate, magnesium oxide, magnesium hydroxide, nickel hydroxide, cobalt hydroxide, manganese hydroxide, lithium hydroxide, mixed hydroxide precipitate, or a combination thereof. Although sodium hydroxide can be used, the base is preferably not sodium hydroxide since this results in the formation of sodium sulphate. Sodium sulphate as a by-product has a number of disadvantages. Firstly, sodium sulphate is in sufficient supply and is a low value by-product since it is generated in excessive quantities in parallel industries, such as a by-product in the manufacture of nylon and this supply is sufficient to meet the needs of sodium sulphate in the washing powder and pulping agent industries, and so the demand of sodium sulphate in the marketplace is already easily met. With ever increasing rates of recycling of battery materials, the supply of sodium sulphate is set to increase further. In addition, sodium sulphate accumulation in the system throughout is hard and expensive to remove. The solubility of sodium sulphate in water is unusually dynamic in that it increases by around ten times as the temperature of water increases from around 0°C up to around 32°C. As the solubility of sodium sulphate is heavily dependent on temperature, having sodium sulphate dissolved in a solution within a recycling process causes issues since the temperature either needs to be controlled and kept above ambient temperature to avoid the sodium sulphate crystallising out of solution at an undetermined step in the process, which can cause blockage of filters, pumps, or pipework in a plant, or the process needs to include an additional step towards the beginning of the process in which a large volume of solution needs to be cooled to knock out the dissolved sodium sulphate, filtered, and then reheated in order for subsequent reactions to take place at an acceptable rate. Both of these options incur high additional costs, which are not offset due to the low value of the sodium sulphate product. As such, the present process seeks to avoid these problems by minimising the production of sodium sulphate. Calcium hydroxide, calcium oxide, and calcium carbonate as well as magnesium hydroxide, magnesium oxide, and magnesium carbonate are suitable as a base for a number of reasons. In addition to being a base, calcium will react with any available fluoride to form calcium fluoride, which are extremely poorly soluble in water and therefore is removed from solution. Magnesium fluoride is also poorly soluble in water, meaning that it can be removed from solution readily. In this way, the method includes a fluorine mitigation or fluoride scrubbing step. This mitigates the risk of hydrogen fluoride gas being released and residual hydrofluoric acid remaining in solution, which is a large risk when battery materials are being recycled due to the presence of fluorinated compounds in batteries. In addition, calcium sulphate is only sparingly soluble in water, unlike sodium sulphate, and therefore is readily removed from solution, such as by filtering, and does not require such rigorous thermal control of the solution. Magnesium sulphate is also poorly soluble in water. Furthermore, calcium sulphate, also known as gypsum, is much more valuable than sodium sulphate. After removal of calcium sulphate from solution, the osmotic pressure of the solution is reduced and so the solution can be concentrated without the risk of precipitation. The method may include one or more filtration steps whenever a solid material needs to be removed. Any known filtration method may be employed and the present invention is not particularly limited by any specific filtration method. For example, graphite may be filtered from solution after the initial leaching step. It is this graphite which may be referred to as a hydrometallurgically recovered graphite. The nickel hydroxide, cobalt hydroxide, and manganese hydroxide, possibly as a mixed metal hydroxide, may be produced at a later stage of the process and may therefore be recycled back into the process to adjust the pH of the pregnant leach solution to precipitate any intermediary metals or materials, such as copper, aluminium, or iron. As such, one or more of the lithium hydroxide, manganese hydroxide, cobalt hydroxide, and nickel hydroxide may be a recycle stream at least partially obtained from the depleted leach solution. An intermediary material or metal is a material or metal other than nickel, cobalt, manganese, and lithium which needs to be removed from solution at some stage of the process. This may include one or more transition group metals. The pH of the pregnant leach solution is adjusted to around 5 to around 5.3, which causes any solubilised iron and aluminium to precipitate out of solution. An oxidising agent, such as air, is provided to assist with precipitation of any aluminium or iron. The process further includes a copper cementation, otherwise known as copper scrubbing, step to remove copper from the depleted leach solution if copper is present. Where the source material includes any batteries or battery-related materials, such as battery manufacture scrap, it is likely that the solution will include copper. In a copper cementation process, a redox reaction between metallic iron and copper in solution results in copper metal precipitating out of solution. In particular, the exemplary reaction may be: Fe(s) + Cu2+ —►Cu(s) + Fe2+ Fe2+ + O2+H2O —► Fe(O)OH Indeed, any metal with a more negative standard electrode potential than copper may be used and the process is not limited to metallic iron. A copper cementation process usually includes an oxidiser, such as air, to oxidise iron, or other metal, in solution, which can precipitate out as iron (III) oxy-hydroxide. The precipitated copper and iron, or other metal used in the cementation step, can be separated from the solution and processed separately. The copper may be recovered by, for example, electrowinning. Following the copper cementation reaction, one or more target metal, such as one or more of manganese, cobalt, and nickel, may be recovered from the depleted leach solution to provide a lithium leach solution. The separation of manganese, cobalt, and nickel from solutions is well-known in the art. As mentioned, the one or more target materials may be manganese, cobalt, and nickel and lithium. These are battery materials that are used in the production of batteries. These metals may be used in the manufacture of cathode active materials. The method may further include precipitating sodium sulphate from the concentrated lithium leach solution, assuming that sodium sulphate is present in solution. This may be done by cooling the concentrated lithium leach solution. The concentrated lithium leach solution may be cooled to around 5°C or less, for example from around 2 to around 4°C. The leach solution may be cooled to from around 0°C to around 6°C, around 1°C to 5°C, or around 2°C to 4°C. The method may further include concentrating the lithium leach solution to form a concentrated lithium leach solution. Since the solution from which the lithium leach solution is derived needed to have sufficient volume to leach and hold the metals from the source material, as the respective metals are selectively removed from the solution, leaving primarily lithium in solution, the concentration of metal ions is decreased. As such, it is advantageous to concentrate the lithium leach solution so that a smaller volume of liquid needs to be handled and a higher extraction efficiency may be accessed. The concentration may be achieved by any method and the invention is not particularly limited by the method selected. Reverse osmosis is one example of a suitable concentration method. The method may further include precipitating lithium carbonate from the concentrated lithium leach solution. The method may include adding one or both of sodium carbonate and ammonium carbonate to the concentrated lithium leach solution. The addition of these carbonate is to convert lithium ions in solution into lithium carbonate. The method may further include precipitating lithium carbonate from the concentrated lithium leach solution. It will be appreciated that the lithium could be precipitated from the lithium leach solution without concentration. Whilst this would mean that there is a large volume of liquid from which to precipitate the lithium carbonate, this would avoid the concentration step, which may be advantageous in simplifying the process. The source material may include one or more of black mass, batteries, preferably lithium-containing batteries, battery factory waste, precursor battery materials, and mixed hydroxide precipitates, or mixtures thereof. Electric vehicle (EV) batteries are an eminently suitable source. As such, the source material may be a mixed source material. In other words, the source materials may be a mixture of materials from different sources rather than a single type of material. Battery factory waste is material which is used to produce batteries and include offcuts, scrap, batteries which have failed quality control, as well as any other materials containing useful battery materials. Indeed, the source material may be a mixed source material, with materials from different sources being processed together. A further advantage is that it is able to accommodate different feedstocks with different metals and different concentrations of metals, in contrast to existing methods which are limited to only particular feedstocks and do not provide the same flexibility to handle a range of feedstocks. Indeed, feedstocks can be blended deliberately to match the incoming metal composition balance with a particular product mix and / or demand plan for the various commercial offtakes. For example NMC111 feedstocks can be recycled alongside other feedstocks which result in an output which has a desired chemistry, for example NMC811. The method may further include, prior to step a), contacting shredded lithium-containing batteries and / or source material with a basic aqueous solution of an alkali metal salt or alkali earth metal salt. The method may include, prior to step a), brine discharging of the source material to dissipate any electrical charge. This may be achieved by submerging any batteries in a brine to electrically discharge them. The batteries may be dry shredded or wet shredded. Preferably the alkali metal salt or alkali earth metal salt is not a chloride. Preferably, the alkali metal is other than sodium. The source material may include materials which retain some electrical charge. By contacting the source materials with a basic solution of an alkali metal salt other than sodium chloride or indeed any other sodium salt, the charge may be dissipated. Preferably, the method does not include thermal discharge of the source material. Thermal discharge is where the material is heated up to a temperature, such as 300°C or higher for a time to remove any electric charge from the materials and / or to burn off certain materials, such as plastic or paper. Since the present invention is intended to be an environmentally-friendly solution, it is undesirable to burn off materials such as plastic or paper. In addition, thermal discharging of the source material requires additional energy to be provided, which increases cost and also energy requirements. Other means of dissipation could be implemented, such as electrical load discharging where a battery is connected to an electrical load to drain the battery, or by puncturing the battery and immersing it in a conductive fluid, such as brine, preferably sodium-free and / or chlorine-free brine. The solution is preferably aqueous, but can comprise an organic solvent if required. In this way, removal of any chloride ions which could otherwise act as a contaminant is not required and a corrosion risk within chemical plant infrastructure designed for sulphuric acid based processes is avoided. In addition, the solution is basic in order to avoid degradation of electrolytes which may be present as these are generally fluorinated compounds, such as LiPF6, lithium hexafluorophosphate, which can release hydrogen fluoride gas, which is extremely hazardous. LiPFe is generally stable, but is susceptible to hydrolysis in acidic media. In addition, it is preferable to avoid the use of sodium salts since these will ultimately become sodium sulphate, which has various undesirable qualities as detailed above. Preferably, chloride salts are avoided since this can attack certain grades of steel and would require a higher grade of steel to be used, which increases costs. Calcium salts are preferable since the calcium can react with any free fluoride to precipitate as calcium fluoride. The method may further include recovering the basic aqueous solution after contacting the basic aqueous solution with the source material. By separating the basic aqueous solution and any remaining solids, the solids can be passed into step a), optionally after being washed, and the basic aqueous solution can be taken away for further processing, if required. The separation can be done by any suitable means, such as filtration or centrifugal separation. The method may include separating out any metallic foils, binders, membranes, separators, or plastics from the basic aqueous solution. Preferably, the metallic foils or plastics are removed prior to step a) to minimise the amount of material which is being processed and to minimise the amount of aluminium which needs to be removed. Batteries include conductive foils, usually aluminium, and whilst these can be removed in step a) by dissolving them in acid, this increases the amount of acid required to leach the valuable battery metals from the source material, increases the amount of hydrogen H2 released during the leach process and also increases the amount of aluminium which subsequently needs to be precipitated from solution. As such, removing any foils ahead of the leaching step, is preferable. The foils may be removed by any known method, for example, eddy current, shaker table separation, sieving or filtration. Similarly, the source material may include various plastics, some of which may be readily removed by, for example, flotation, shaker table separation, sieving or filtration. Preferably, the plastics are moved by a method other than combustion or other thermal removal, such as evaporation or pyrolysis. The method may include adding water in step a) to provide a solid loading within a predetermined range. Since the source material needs to be mixed and transferred, this can be made easier by adding water to allow the source material to move more freely. Water may be added to provide any desired solid loading, such as 10wt% (that is the solid makes up 10% of the total mass of a given volume of the mixture of the source material and water), 15wt%, 20wt%, 25wt%, 30wt% or40wt%. A lower solid loading will make mixing and transfer easier, but will increase the volume of liquid which needs to be handled. The method may further include, adding, in step a) acid in stages or steadily at a rate which controls foaming and spontaneous exothermic processes. The addition of acid, such as sulphuric acid, generates gas and foaming which needs to be kept in control. The reaction generates hydrogen gas, which must be diluted otherwise it results in a danger of explosion. In addition, the addition of sulphuric acid to water causes an increase in temperature, which also needs to be controlled to avoid overheating the solution, which can present a safety hazard and can also result in the generation of unwanted hydrogen fluoride gas. In addition, the addition of sulphuric acid to cathode metal oxides causes an increase in temperature, which also needs to be controlled to avoid overheating the solution, which can present a safety hazard and can also result in the generation of unwanted hydrogen fluoride gas. In addition, it is desirable to keep the temperature below around 85°C since in the next stage hydrogen peroxide will be added, which rapidly decomposes at elevated temperatures. The temperature may be at or below around 80 °C, 75°C, 70°C, 65°C, 60°C, 55°C, 50°C, 45°C, or less than 50 °C .The staged addition of sulphuric acid or the addition of sulphuric acid at a controlled rate avoids these issues. Furthermore, since the total amount of metals in the source material may not be known exactly, given that the method is able to accommodate a whole range of potential source materials, it is preferable to control the addition of sulphuric acid to provide sufficient time for any foaming to be observed to inform on the progress of the reaction. Similarly, controlled addition of sulphuric acid also allows for sampling of the leach solution to measure whether the concentration of one or more target metals is static, which indicates that all of the valuable battery materials have been leached into solution. In addition, it may take some time for the pH to stabilise and it is desirable that at the reasonable completion of the reaction the pH between about 0 and about 2.3 so that there is a slight excess of acid to ensure that all of the valuable battery metals have been leached and that the pH is below the pH at which certain metals begin to precipitate from solution. In step c), the temperature of the solution may be from about 40°C to about 85°C, from about 50°C to about 70°C, from about 55°C to about 65°C, or about 60°C, or about 55°C, or about 50°C, or about 45°C, or less than 50°C. These temperature ranges ensure that the peroxide does not decompose before it can react and also minimises the production of hydrogen fluoride gas. The method may include stirring at any step. It will be appreciated that it is desirable to ensure that the solution and the source materials are mixed so that the process is as efficient as possible. The oxidizing agent in step d) may be oxygen, air, or peroxide, such as hydrogen peroxide. Preferably, the oxidizing agent is oxygen or air. The oxidizing agent may be added by any suitable means, but where it is a gas, it may be bubbled through the solution. The method may include adding zinc to the depleted leach solution after step e) in order to precipitate cadmium from solution. Zinc powder may be used to precipitate cadmium (s) where ZnO is in solution as Zn2+. Cadmium may be a contaminant and, if present, it is desirable to remove this dangerous element from the process. The addition of zinc causes any cadmium to precipitate out of solution, from which it can be removed and disposed of safely. One, two or all of manganese, cobalt, and nickel may be recovered from the depleted leach solution via solvent extraction. Solvent extraction of these elements from solution is known in the art, and the present invention is not particularly limited by the way in which this is achieved. For example, manganese may be removed from solution using Di(2-ethylhexyl)phosphoric acid (DEHPA) and kerosene. Cobalt may be removed from solution using Cyanex 272™ and kerosene. The pH of the solution may be adjusted using an acid, such as sulphuric acid, and one, two, or all of sodium hydroxide, ammonium hydroxide, lithium hydroxide, nickel hydroxide, manganese hydroxide, or cobalt hydroxide, preferably wherein the nickel hydroxide, lithium hydroxide, cobalt hydroxide, and / or manganese hydroxide is a recycle stream at least partially obtained from the depleted leach solution. By using a recycle stream, it is possible to reduce the amount of additional chemicals which need to be used in the process. The pH may be selected such that greater than 50% of a target material is extracted in the solvent extraction step. The solubility of different metals depends on the pH and by adjusting the pH of a solution, it is possible to control which metal is preferably extracted. Nickel may be precipitated from the pregnant leach solution with a mixture of ammonium hydroxide, lithium hydroxide, and / or sodium hydroxide. Whilst it is desirable to minimise the amount of sodium being used in the method, nickel co-ordinates with ammonium hydroxide, so it is preferable to use ammonium hydroxide to precipitate out the nickel alongside one or both of sodium hydroxide and lithium hydroxide. Even so, some ammonium hydroxide can be used to reduce the amount of sodium being introduced. The pH of the depleted leach solution may be increased to about 7 to about 11, to about 8 to about 10, to about 8.5 to 9.5, or to about 9 to 9.5 in order to precipitate nickel. The method may further include combining one or more of any recovered manganese, cobalt, and nickel in a predetermined ratio and precipitating out the one or more of the recovered manganese, cobalt, nickel, and lithium to form a cathode active material precursor precipitate, optionally wherein the method further includes supplementing one or more of the recovered manganese, cobalt, and nickel with additional manganese, cobalt, and / or nickel. By precipitating these metals out of solution together, they are much better mixed that would be the case were they to be mixed as solids. The metals may be precipitated as carbonates. Since the source material may not include these metals in the exact ratio required to produce a cathode active material, supplemental metals can be includes in order to provide the desired ratio. For example, the ratio of manganese, nickel, and cobalt can be adjusted to any required battery chemistry, such as, for example, NMC 111, NMC 622, NMC811, NMC 532, or any intermediary ratio blends. The method may further include converting the cathode active material precursor precipitate into a cathode active material. This may include one or more calcining steps to convert the cathode active material precursor precipitate into a cathode active material. The precipitated Ni, Mn, Co carbonate may be filtered, dried, and milled before undergoing a pre-calcining step. Following pre-calcining, lithium hydroxide may be added, the mixture milled again, followed by final calcining. The method may include incorporating lithium, optionally in the form of lithium hydroxide, after a pre-calcination step. This step forms what is commonly referred to as green body, which is a mixture of lithium hydroxide and oxides of nickel, manganese, and cobalt. This green body can then be calcined at elevated temperatures in oxygen to form the final cathode active material. The method may include one or more mixing, grinding, or milling steps. Whilst such steps may take place at any stage where it is desirable to break down solids into smaller pieces, this step will most likely be conducted after the cathode active material precursor precipitate has been dried, after it has been pre-calcined, and / or after it has been calcined. Any suitable mixing, grinding, or milling process may be used and the present invention is not particularly limited by the method used, for example, dry or wet planetary ball milling, rolling ball milling, high shear milling, air jet milling, and / or impact milling. The method may include one or more filtration steps. The filtration step may take place at any stage where it is desirable to separate a solid from a liquid. Any suitable filtration process may be used and the present invention is not particularly limited by the method used. It will be appreciated that the hydrometallurgically recycled graphite obtained from such a method may be the source of the recycled graphite used in a battery, as described in respect of the present invention. By utilising a hydrometallurgically recycled graphite in a battery, there are significant carbon savings as compared to utilising primary graphite. In particular, it has been calculated that the use of a hydrometallurgically recycled graphite is around 7 times less carbon intensive than the use of primary produced graphite materials. Primary graphite from China has an estimated carbon dioxide equivalent per kilogram of anode material of around 19.4 kg, whereas a recycled graphite material has an estimated carbon dioxide equivalent per kilogram of anode material of only around 2.7 kg. In addition, it has been found that the hydrometallurgically recycled graphite for the second generation of batteries has the same or very similar properties as the primary graphite in the first generation of batteries, meaning that it is eminently suitable for use in a new battery. The hydrometallurgically recycled graphite may be an upgraded hydrometallurgically recycled graphite. By upgraded, it is to be understood that the hydrometallurgically recycled graphite undergoes one or more additional steps to further improve the properties of the graphite, such as, for example, reduction in the amount of any contaminants which are present and improved purity, for high performance anodes. This initial upgrade will lead to improved battery performance such that the second generation of batteries can be akin to the battery properties in the first generation of batteries from the initial imprint of the mixed feed batteries. Further improved performance of the second generation batteries in an upgrade can be tailored into an optimised graphite material for anode (with an optimum selection of active components and their ratios) during processing for improved battery performance, such as, energy density, energy storage capacity and life cycle (number of cycles of discharge that battery can deliver over its lifetime), resistivity, surface area, consolidated density, minimising spring-back for anode calendaring, graphite particle alignment, tap density, removal of surface contaminants and dendrites. The hydrometallurgically recycled graphite may be a non-pyrometallurgically upgraded hydrometallurgically recycled graphite. Pyrometallurgy requires the use of high temperatures, such as over 500°C, over extended periods of time, which may be 6 hours or more, to calcine the material. This is an energy intensive process which therefore reduces the environmental impact associated with recycling materials, and moreover, breaks carbon bonds and removes the battery imprint morphology and characterisation properties from the first generation of batteries, having then to subsequently regenerate a different battery imprint which is inferior to that of the first generation. In addition, the hydrometallurgically recycled graphite does not comprise a repair or carbonisation agent. Repair or carbonisation agents serve to introduce additional carbon into the graphite to repair defects. The recycled graphite may be carbonate-free. The recycled graphite may be provided without the use of ultrasonics, calcination, milling, crushing, and / or microwaving. The graphite may comprise 92 wt% or more graphitic carbon. The graphite may comprise 95wt% or more graphitic carbon, 96 wt% or more graphitic carbon, 97 wt% or more graphitic carbon, 98 wt% or graphitic more carbon, 99 wt% or more graphitic carbon, 99.5wt% or more graphitic carbon 99.9 wt% or more graphitic carbon, or 99.95wt% or more graphitic carbon. As such, it will be appreciated that the amount of non-carbon materials within the hydrometallurgically recycled graphite may correspondingly be 7wt% or less to 0.05wt% or less. Graphitic carbon will be understood to be graphite-like in that it may comprise sp2 hybridised carbon rather than the sp3 carbon observed in non-graphitic carbon. The graphitic carbon may be disordered or aligned with structural ordering. The graphite may comprise 5wt% or less, 4wt% or less, 3wt% or less, 2wt% or less, 1wt% or less, 0.5 wt% or less, 0.1wt% or less, 0.05 wt% or less, or 0.01 wt% or less aluminium oxide. Aluminium oxide may be present as a result of contamination from aluminium foils used in the end-of life battery from which the recycled graphite is obtained. This metallic aluminium may be oxidised during recycling to result in aluminium oxide being present as a contaminant. Alternatively or additionally, aluminium oxide may be intentionally used as a coating of graphite particles to add robustness to the particle and may therefore be present as an intentional coating of at least some of the graphite particles. The graphite may comprise 5wt% or less, 4wt% or less, 3wt% or less, 2wt% or less, 1wt% or less, 0.5 wt% or less, 0.1wt% or less, 0.05 wt% or less, or 0.01 wt% or less lithium nickel oxide. The lithium nickel oxide may be a contaminant from the original battery comprising the graphite which has been recycled. The graphite may comprise 5wt% or less, 4wt% or less, 3wt% or less, 2wt% or less, 1wt% or less, 0.5 wt% or less, 0.1wt% or less, 0.05 wt% or less, or 0.01 wt% or less aluminium (oxy)hydroxide. The graphite may have a minimum Feretdiameterof 5 microns or greater. Feret diameter is also referred to as caliper diameter and relates to an objects size as a measure of the distance between two parallel planes restricting the object perpendicular to such direction. The Feret diameter may be routinely measured using a Malvern Mastersizer which relies on light scattering to measure the dimensions of particles. Malvern Mastersizers are routinely used to measure the dimensions of particles. For second generation battery anodes, upgraded graphite processing can be modified to optimise the desirable properties of the graphite, such as controlling particle size of graphite, surface area, purity and crystallinity; which all significantly impacts performance. Graphite processing can be sufficiently adapted to produce upgraded graphite for optimising the properties of the anode taking into account the many factors affecting performance including the following: Particle size: smaller particles tend to perform better due to reduced lithium (Li) plating and improved intercalation behaviour. Larger particles can lead to Li plating, which affects battery safety and capacity and are typically reserved for use in highly controlled or high energy applications that rely on generally slow charge / discharge rates. Surface area: a higher surface area allows for better interaction between the graphite anode and the electrolyte. Increased surface area enhances the rate of Li intercalation and de-intercalation during charge and discharge cycles. Surface area also correlates with the attainable packing efficiency of the anode powder meaning that different applications can be targeted. Purity and crystallinity: high purity graphite with minimal impurities ensures better electrochemical performance - purity especially transition metal and magnetic fraction content are critical to control recycled materials. Well-ordered crystalline structure promotes efficient Li ion diffusion within the graphite lattice and improves electrochemical characteristics. Tap density: the effect of particle size on its electrochemical properties is manifested in the fact that the particle size of the anode material will directly affect the tap density (the ability of the material to pack and order under mild agitation - tapping) of the material as well as the specific surface area of the material. The size of the attainable tap density will directly affect the bulk energy density of the material and the attainable energy when built into an electrode for assembly into a battery. Consolidated density: this density is the packing efficiency attainable after electrode coating and calendaring. Mainly for optimising the properties of a coated electrode it refers to the density of the anode active material and binder, etc. made into the electrode, after calendaring. The use may be in a battery anode. The battery may be a lithium-ion battery. The battery may be, for example, an electric vehicle (EV) battery, a consumer battery, or a battery energy stationary storage battery, or portions thereof. According to a second aspect of the present disclosure, there is provided a method of upgrading a hydrometallurgically recycled graphite, the method including washing a hydrometallurgically recycled graphite to provide a washed graphite material, and subsequently drying the washed graphite material. By washing the hydrometallurgically recycled graphite, residual soluble contaminants will be removed to thereby increase the purity of the graphite. The washed graphite material may be dried under vacuum. By drying under vacuum, it is not strictly necessary to heat the washed graphite material strongly or even at all to drive off any residual water. The washed graphite may be heated to above 25°C in order to aid drying. The temperature is preferably kept at 90°C or below. By keeping the upper temperature below 100°C, any water is not boiled off, which consumes a very large amount of energy due to the phase change from a liquid to a gas. In addition, where the graphite is washed with water and / or acids other than sulphuric acid, any residual acids will be removed alongside water. In contrast, due to the comparatively high boiling point of sulphuric acid, this is not readily removed under vacuum or at temperature below 90°C, and so remains as a contaminant in the resultant graphite unless multiple washings with water are undertaken. The additional washing require additional time and cost. The washed graphite may be dried at from around 25°C to around 90°C, from around 30°C to around 80°C, from around 40°C to around 70°C, or from around 50°C to around 60°C. The drying may take place under vacuum. As such, in embodiments, the method does not employ temperature of 100°C or more. In other words, the method employs temperatures of less than 100°C, less than 95°C, or 90°C or less. The same temperature limits may be adopted when washing the graphite material. The washing may include multiple washing cycles. Not all of the contaminants may be washed out in a first washing cycle and so any number of washing cycles may be undertaken. For example, there may be three washing cycles undertaken which include washing and drying the graphite material three times. Between washing cycles, the graphite does not need to be fully dried, merely the majority of the free aqueous liquid removed, such as by filtering. The solution used to wash the graphite may be recycled and used multiple times. The solution may additionally or alternatively be recycled to a hydrometallurgical extraction process, such as that described herein, in order to make best use of the water used and to minimise waste water discharge. It will be appreciated that there is a balance between the number of washings and the acceptable levels of contaminants in the graphite. Whilst it may not be possible to remove all of the contaminants, they may be reduced to below a predetermined level which is acceptable for either subsequent processing or use in a new battery. The method may include washing with one or more of water, an acid, and a base. Washing with water serves to remove water-soluble contaminants from the graphite and also serves to wash away any residual acids from the hydrometallurgical recycling process from which the graphite is derived. Washing with acid serves to remove lithium nickel oxide contamination from the graphite. Washing with a base serves to remove aluminium oxide and / or aluminium (oxy)hydroxide from the graphite. Preferably the pH of the washing solution is equal to or higher than the pH of the hydrometallurgical process used to generate the recycled graphite and / or the pH of the hydrometallurgically recycled graphite being upgraded. Since the graphite is intended to be used in a new battery, it needs to be suitable for such use and so avoiding having a very low pH means that less additional processing needs to be undertaken to provide a battery-suitable material. In addition, the first wash is preferably a basic wash in order to reduce the risk of contamination of metal ions, such as sodium metal ions, from the base in the graphite. The acid may be a mineral acid. The acid may be an organic acid. The acid may be a mixture of one or more acids. For example, the acid may be a mixture of a mineral acid and an organic acid. The mineral acids may be selected from one or more of nitric acid, hydrochloric acid, hydrofluoric acid, and sulphuric acid. Nitric acid and hydrochloric acid are preferred due to better ease of handling as compared to hydrofluoric acid and also ease of removal compared to sulphuric acid. As such, in embodiments, the method for upgrading the hydrometallurgically recycled graphite does not use sulphuric acid and / or hydrofluoric acid. This does not mean that the hydrometallurgical recycling process from which the recycled graphite is derived necessarily excludes the use of these acids. In other words, in embodiments, the upgrading method is sulphuric acid and / or hydrofluoric acid free. The concentration of mineral acids may be from around 1M to around 6M, optionally between around 3M and 5M. The organic acid may be one or more of acetic acid, oxalic acid, malic acid, citric acid, malonic acid, and maleic acid. It has been surprisingly found that it is not necessary to use strong mineral acids in order to upgrade hydrometallurgically recycled graphite and that milder organic acids may also serve to remove contaminants from the graphite to generate a purer, and thereby upgraded, graphite material. . Oxalic acid demonstrates the best results for removing aluminium compounds, specifically aluminium oxide, and the others are primarily effective in removing metal oxide compounds, such as lithium nickel oxide. Citric acid, malonic acid, and maleic acid demonstrate the best results overall. The organic acid concentration may be from around 0.5M to around 3M, such as around 1M. The acid washing step may be in the presence of hydrogen peroxide. The acid washing step may be in the absence of hydrogen peroxide. The washing step may be from 1 minute to 24 hours. The washing step may be undertaken for up to 1 hour, up to 2 hours, up to 3 hours, up to 4 hours, up to 5 hours, up to 6 hours, up to 7 hours, up to 8 hours, up to 9 hours, up to 10 hours, up to 11 hours, up to 12 hours, up to 13 hours, up to 14 hours, up to 15 hours, up to 16 hours, up to 17 hours, up to 18 hours, up to 19 hours, up to 20 hours, up to 21 hours, up to 22 hours, up to 23 hours, or up to 24 hours. The washing step may include stirring the mixture to ensure homogeneity and to allow sufficient interaction between the solid and liquid phases. Any stirring speed which is sufficient to mix the solid and liquid phases and which does not cause damage to the graphite, which may be observed by the production of fines (which is a term of the art for small particles). Exemplary stirring speed are from around 50 rpm to around 600 rpm, such as around 400 rpm. The washing step provides for the generation of battery-grade graphite without residual metals or metal oxides and other impurities, such as sulphates, and without structural changes to the graphite. The base may be a metal hydroxide. The metal hydroxide may be an alkali metal hydroxide. The alkali metal hydroxide may be sodium hydroxide. Sodium hydroxide may react with contaminants in the graphite material, particularly aluminium oxide and aluminium (oxy) hydroxide to form soluble sodium aluminium oxide. The reaction schemes may be as follows: i) AI2O3 (s) + 2NaOH (aq) 2NaAIO2 (aq) + 3H2O ii) AIO(OH) (s) + NaOH (aq) NaAIO2 (aq) + H2O As mentioned above, the method may include heating the graphite to from around 25°C to around 90°C to dissolve contaminants. The method may include washing with abase in a first washing cycle, a filtering step to separate solids from the washing liquid, and subsequently washing the separated solids with an acid. The acid washing cycle may serves to remove lithium nickel oxide and the base washing step may serve to remove the aluminium oxide and aluminium (oxy)hydroxide contaminants. The order of such washing cycles may be reversed. Where there is a base washing step, it is useful to have this ahead of an acid washing step in order to reduce the amount of metal ion contaminants from the base, which may be sodium hydroxide. The washing protocols may not remove all of the contaminants from the graphite as it will still be possible to detect trace amounts of the contaminants under a graphite assay. It is possible to reduce contaminants, such as, for example, filtering at temperatures of greater than 50°C to limit precipitation of lithium nickel oxides in the graphite. According to a third aspect of the present disclosure, there is provided an upgraded hydrometallurgically recycled graphite comprising 92wt% or more graphitic carbon. The graphite may comprise 95wt% or more graphitic carbon, 96 wt% or more graphitic carbon, 97 wt% or more graphitic carbon, 98 wt% or more graphitic carbon, 99 wt% or more carbon, 99.5wt% or more graphitic carbon 99.9 wt% or more graphitic carbon, or 99.95wt% or more graphitic carbon. The upgraded hydrometallurgically recycled graphite may comprise crystallites having a minimum Feret diameter of 5 microns or greater. The upgraded hydrometallurgically recycled graphite may comprise 5wt% or less aluminium oxide. The upgraded hydrometallurgically recycled graphite may comprise 4wt% or less, 3wt% or less, 2wt% or less, 1wt% or less, 0.5 wt% or less, 0.1 wt% or less, 0.05 wt% or less, or 0.01 wt% or less aluminium oxide. The upgraded hydrometallurgically recycled graphite may comprise 5wt% or less, 4wt% or less, 3wt% or less, 2wt% or less, 1wt% or less, 0.5 wt% or less, 0.1 wt% or less, 0.05 wt% or less, or 0.01 wt% or less lithium nickel oxide. The upgraded hydrometallurgically recycled graphite may comprise 5wt% or less, 4wt% or less, 3wt% or less, 2wt% or less, 1wt% or less, 0.5 wt% or less, 0.1 wt% or less, 0.05 wt% or less, or 0.01 wt% or less aluminium (oxy)hydroxide. The upgraded hydrometallurgically recycled graphite may have a spherical morphology. The upgraded hydrometallurgically recycled graphite may have an x-ray diffraction peak at 26.5° as measure using a cobalt x-ray source. Such a peak is indicative of graphite and is the same as non-recycled graphite, thereby demonstrating the recycled material’s suitability for use in a new battery. A shift in peak would have indicated a change in interlayer distance, which is not the case, and indicates that the graphite is not adversely affected by the hydrometallurgical recycling process or the upgrading process. The upgraded hydrometallurgically recycled graphite may have a BET surface area of from around 5 to around 11 m2 / g, optionally from around 9 to around 10 m2 / g. Upgraded graphite will be optimised accordingly. Generally, anodes with small graphite particles and high specific surface area have more channels and shorter diffusion paths for lithium ions when formed into an electrode. This graphite type will typically see application in high-rate capability batteries. Generally high surface areas lead to multiplicity in overall electrochemical performance. However, due to the large contact area with the electrolyte, the area to form the SEI film is also large, and the first cycle inefficiency is lower with greater lithium inventory loss within the electrochemical cell. Large particles, on the contrary, have the advantage of greater compaction density. The specific surface area of graphite anode material less than 5 to 6 m2 / g is generally considered appropriate for most applications, although larger surface areas, such as 9 to 10 m2 / g are also useful. The upgraded hydrometallurgically recycled graphite may have a cold free space of from around 22 to around 26 cm3, optionally from around 24 to around 25 cm3, optionally around 24.4 cm3. Cold free space is measured by the equation: Vcs = Vcm - ((ms / ps) x (Tstd / Tbath)), wherein Vcs = calculated cold free space with sample present (standard cm3) Vcm = cold free space measured for the empty tube (standard cm3) ms = mass of sample to be analysed (grams) ps = approximate sample true density (grams / cm3) Tbath = bath temperature (Kelvin) Tstd = standard temperature (273.15 K). The warm free space of the graphite may be from about 8 to around 10 cm3, optionally around 9 cm3. Warm free space may be calculated by the equation: Vws = Vwm - ((ms / ps) x (Tstd / Tamb)), wherein Vws = calculated warm free space with sample present (standard cm3) Vwm = warm free space measured for the empty tube (standard cm3) ms= mass of sample to be analyzed (grams) ps = approximate sample true density (grams / cm3) Tamb = ambient temperature (Kelvin) Tstd = standard temperature (273.15 Kelvin). The hydrometallurgically recycled graphite may be derived from end of life lithium ion batteries, such as EV batteries. According to a fourth aspect of the present disclosure, there is provided a battery anode material comprising the graphite material according to the third aspect of the present disclosure. The battery anode material may have a density of from around 1.4 to around 1.6 g / cm3. The battery anode material may have a capacity of from around 330 to around 360 mAh / g. The battery anode material may comprise around 96-97wt% active material (graphite), with the remainder being binders, such as CMC (carboxymethyl cellulose) and SBR (styrene-butadiene rubber), as well as unavoidable contaminants. In an embodiment, the battery anode comprises 96.5 wt% graphite, 1.5wt% CMC and 2 wt% SBR. According to a fifth aspect of the present disclosure, there is provided a battery comprising the graphite material according to the third aspect of the present disclosure or a battery anode according to the fourth aspect of the present disclosure. The battery may be an EV battery, a consumer battery, or a battery energy stationary storage battery. The use, method, graphite, battery anode, and battery according to the present disclosure allow for the recovery and re-use of graphite from a source material. The conditions used in the present disclosure are benign to graphite and therefore allow for the recovery of graphite from a source material that is particularly suitable for re-use in a battery. The present invention allows for the re-use of greater than 99wt% of graphite materials in the original source material It will be appreciated that features described in respect of one aspect may be combined with any features described in respect of another aspect and all such combinations are expressly considered and disclosed herein. For example, the upgraded hydrometallurgically recycled graphite may have any of the parameters described herein, whether in respect of the third aspect of any other aspect described herein. Brief Description of the Drawings Embodiments of the invention will now be described, by way of example only, with reference to the accompanying schematic drawing in which corresponding reference symbols indicate corresponding parts, and in which: Figure 1 is a schematic depiction of a method according to the present disclosure for upgrading a hydrometallurgically recycled graphite; Figure 2 is a graph depicting the concentration of various contaminants of a hydrometallurgically recycled graphite; Figure 3 is a graph showing the total mass recovered in filter cake was cycles versus leachate; Figure 4 is an XRD trace showing the composition of a hydrometallurgically recycled graphite; Figure 5 is an XRD trace showing the composition of the hydrometallurgically recycled graphite of Figure 4 after treatment with 5M HCI; Figure 6 is an XRD trace showing the composition of the hydrometallurgically recycled graphite of Figure 4 after treatment with 5M nitric acid; Figure 7 is an XRD trace showing the composition of the hydrometallurgically recycled graphite of Figure 4 after treatment with 5M sodium hydroxide; Figure 8 is a micrograph showing the morphology of graphite particles in accordance with the present invention; Figure 9 is an XRD trace of upgraded recycled graphite according to the present invention; Figure 10 is another CRD trace of upgraded recycled graphite according to the present invention; and Figures 11a and 11b provide some estimated climate change impacts in forming an anode material using graphite from primary source (Figure 11a) and from recycled graphite according to the present disclosure (Figure 11b). The features and advantages of the present invention will become more apparent from the detailed description set forth below. Detailed Description Figure 1 is a schematic depiction of a process of upgrading a hydrometallurgically recycled graphite. The method 1 includes a first step of washing hydrometallurgically recycled graphite 2 in an alkali washing step 3. The alkali washing step 3 may use sodium hydroxide solution. The alkali washing step may include heating to around 80°C to dissolve aluminium compounds contaminating the graphite. Following the initial alkali washing step 3, the solution containing the alkali washing solution and the graphite may be filtered in filtration step 4. The resulting solids may be re-washed 5 any number of times until sufficient aluminium has been removed to meet the desired specification. After filtration step 4, the solids may undergo an acid wash to remove further contaminants. The acid wash step 6 may use any suitable acid, although hydrochloric acid and nitric acid are preferred due to their relative ease of handling and ease of subsequent removal. Avoiding using sulphuric acid at this stage removes the need to either have repeated washings with water to remove the sulphuric acid or to tolerate the sulphuric acid contamination. Whilst this may be acceptable in method which heat the graphite to high temperatures, such as over 100°C, or calcine the graphite, which serves to remove the sulphuric acid, this is undesirable due to the high energy burden involved in calcining or other heating processes. The acid washing step 6 may be repeated 7 as many times as necessary. After the acid washing step, the solids may be filtered from the liquids in a filtration step 9. The solids may undergo additional washing stages 8. The solids may undergo a washing step with water at any stage, such as before the first alkali wash step 3, between the alkali wash step 3 and the acid wash step 6, and / or after the acid wash step 6. After filtration step 9, the solids may be dried, such as by heating and / or vacuum drying. It will be appreciated that there may be a preceding acid wash ahead of the alkali wash, but it is preferable for there to be at least one further washing stage after the alkali wash, which may be an acid wash or a water wash, in order to remove metal ions, particularly sodium ions from the graphite. After the acid wash, there does not necessary have to be a further wash as there are no ions which cause issues upon further processing or use in a new battery. In an embodiment, the washing may take place at 40-70°C, such as around 60°C, for 1 to 24 hours, such as 24 hours, at 50-600 rpm, such as 400 rpm. The hydrometallurgical recycling process maintains the morphology and crystallite size of the anode-grade graphite from the end-of-life battery or other waste to the recovered graphite filter cake, making it suitable for re-insertion into an anode manufacturing process without need for fusion steps to increase crystallite size. As such, no fusion steps to increase crystallite size are required. Figure 2 is a graph showing the removal of contaminants from a hydrometallurgically recycled graphite, with the y-axis being the total mass in mg per kg of black mass. The four bars for each element relate to the original leachate, the first wash, the second wash, and the third wash moving from left to right. As can be seen, there is a significant reduction in contaminants as the material is washed. The y-axis is a logarithmic scale showing orders of magnitude difference. Figure 3 is similar to Figure 2 and is a graph which depicts the efficiency of metal recovery through sequential washing steps according to the present disclosure. The y-axis is the total mass recovered in filter cake wash cycles versus leachate (5). There are three bars for each element relating to the first, second, and third washes moving from left to right. As can be seen, the majority of the contaminants are removed in the first wash. Figure 4 is an XRD trace of a hydrometallurgically recycled graphite material. The trace indicates the presence of graphite, lithium nickel oxide, boehmite (aluminium (oxy) hydroxide), and corundum (aluminium oxide). The XRD traces are conducted on an x-ray machine having a cobalt source rather than a copper source, meaning longer x-ray wavelength than copper based systems, which causes peak positions to be systematically different as a result of the source used rather than any difference in material being tested. Figure 5 is an XRD trace of the hydrometallurgically recycled graphite of Figure 4, but which has been treated with 5M HCI at 80°C. As can be seen, the lithium nickel oxide is removed, leaving the aluminium contaminants. It will be appreciated that these could be removed by subsequent washing steps. Figure 6 is similar to Figure 5, albeit using 5M nitric acid instead of hydrochloric acid. Again, the effective removal of lithium nickel oxide is demonstrated. Figure 7 is similar to Figures 5 and 6, albeit using 5M sodium hydroxide. This figure demonstrates the effectiveness of the removal of aluminium oxide from the graphite, which is more readily removed than aluminium (oxy)hydroxide, which is more slowly removed. Figures 8a and 8b depict two SEM micrographs showing the morphology of graphite crystallites in recovered graphite anode for NMC Residual and LFP Residual respectively in accordance with the present disclosure. The micrographs depict essentially spherical like morphology. Figure 9 is an XRD trace of upgraded recycled graphite according to the present invention. This trace demonstrates that the characteristic graphite peak at 26.5° is the same as that of non-recycled graphite (when measured using a cobalt x-ray source). This being the case, the graphite according to the present disclosure is surprisingly suitable for subsequent use in a new battery despite it being already used in a first generation battery. Figure 10 is another CRD trace of upgraded recycled graphite according to the present invention. This trace demonstrates that the present disclosure is able to provide battery-suitable graphite materials from a wide variety of first generation batteries having different chemistries. Figure 11a is a waterfall chart showing the estimated total climate change impact when forming an anode material using primary sourced graphite, i.e. non-recycled graphite. As calculated there is around a 19.4 kg carbon dioxide equivalent per kg of anode, which is primarily made up of the environmental impact of the primary graphite, plus small amounts for additives, such as carbon black, binders, solvent, copper foil, and electricity. On the other hand, Figure 11b is a waterfall chart showing the estimated total climate change impact when forming an anode material using graphite according to the present disclosure. As can be seen, the recycled graphite has a far lower carbon dioxide equivalent per kg of anode, leading to a significant carbon saving for a final anode formed from such a material, even including the electricity required in processing the graphite and the chemicals used. Examples Example 1 In order to demonstrate the effectiveness of the present invention, XRD phase composition data was obtained for three hydrometallurgically recycled graphite samples before and after the upgrading process according to the present disclosure. Table 1 Sample 1 2 3 Prewashing Postwashing Prewashing Post washing Prewashing Postwashing Graphite 90wt% 97wt% 46wt% 93wt% 69wt% 98wt% Lithium nickel oxide 6wt% 0wt% 48wt% 0wt% 27wt% 0wt% Aluminium Oxide 2wt% 1wt% 5wt% 4wt% 3wt% 1wt% Aluminium (oxy) hydroxide 2wt% 2wt% 1wt% 3wt% 1wt% 1wt% In these examples a mixture of nitric acid and hydrochloric acid (aqua regia) was used to treat the graphite samples at 80°C for 24 hours at 400 rpm. As can be seen, in each example all of the lithium nickel oxide was removed in this process. This can then be recovered to an associated hydrometallurgical recycling process in order to maximise yield of lithium and to also make best use of the acid. With regards to Graphite sample 1, there was originally a significant amount of graphite present along with some lithium nickel oxide, aluminium oxide, and aluminium (oxy)hydroxide. The amount of aluminium oxide was reduced from 2wt% to 1wt%. Although it seems that aluminium (oxy)hydroxide was not reduced, this is because the figures are given as wt% and so the removal of around 6wt% of the lithium nickel hydroxide counteracts any reduction in other species. Similarly, for graphite samples 2 and 3, due to the significant amount of lithium nickel oxide in the original samples, the changes in wt% of the aluminium compounds is seemingly small or even an increase even though some is removed. All of these examples show the effectiveness of the removal of such compounds from a graphite sample, independent of how much lithium nickel oxide may be present. Example 2 In order to determine the effectiveness of different compositions for upgrading a hydrometallurgically recycled graphite material, specifically sample 1 above, a number of different compositions were tested. In particular, Graphite 1 was upgraded with i) sodium hydroxide and hydrogen peroxide, ii) citric acid and hydrogen peroxide, iii) maleic acid and hydrogen peroxide, iv) hydrochloric acid and hydrogen peroxide, and v) nitric acid. Each of these reactions was conducted at around 80°C for 24 hours at 400 rpm mixing speed. Each test provided total dissolution of lithium nickel oxide as well as a reduction in the amount of aluminium compounds present. The addition of hydrogen peroxide was not strictly necessary for the dissolution to take place. Table 2 below demonstrates the effectiveness of such washing solutions in upgrading 5 hydrometallurgically recycled graphite. Graphite Lithium Nickel Oxide Aluminium Oxide Aluminium (oxy) hydroxi de NaOH / H2O2 93wt% 2wt% 3wt% 2wt% Citric Acid / H2O2 92wt% N / A 5wt% 3wt% Maleic Acid / H2O2 92wt% N / A 5wt% 3wt% HCI / H2O2 95wt% N / A 3wt% 2wt% Nitric Acid 95wt% 1wt% 2wt% 2wt% It should be noted that the graphite used is pre-washing Sample 1 for each, except for the nitric acid reaction, which used pre-washing Sample 3 from Table 1. Example 3 Table 3 below demonstrates the effectiveness of the upgrading process as well as the 15 composition of the upgraded hydrometallurgically recycled graphite. Element Non-upgraded (wt%) Upgraded (wt%) C 75.6 92.8 Al 4.7 2.61 Ca 0.15 0.22 Co 0.28 0.01 Cu 0.07 0.02 Fe 0.13 0.02 Li 0.07 Not detected Mn 0.07 0.006 Na 0.17 Not detected Ni 0.15 Not detected P 0.03 Not detected Si 0.08 0.13 Other elements Balance Balance These values were determined by inductively coupled plasma optical emission spectrometry (ICP-OES), which is a known analytical technique used to identify elements and their concentration in samples. Again, it can be seen that it is possible to significantly improve the purity of the hydrometallurgically recycled graphite using methods according to the present disclosure, which provided battery-suitable anode material. In summary, the present invention provides for a more energy efficient, low carbon, and environmentally friendly material and method for re-using recycled graphite in new batteries. Surprisingly, it has been found that it is possible to re-use hydrometallurgically recycled graphite in second generation batteries without the need for energy intensive processes such as calcining or other pyrometallurgical processing. The ability to recycle and re-use graphite which has already been used in batteries improves the environmental benefit of using batteries and also serves to secure supplies of this important material. In addition, other processes for recycling use aggressive mixing and mechanical shear of graphite layers which affects surface area. In contrast, the present process does not require aggressive mechanical processing and so provided a good surface area for the graphite. The features and advantages of the present invention will become more apparent from the detailed description set forth below when taken in conjunction with the drawings, in which like reference characters identify corresponding elements throughout. In the drawings, like reference numbers generally indicate identical, functionally similar, and / or structurally similar elements. It will be appreciated that features depicted and described in respect of one aspect of the present disclosure may be combined with any feature described in respect of any other aspect of the present disclosure.

Claims

CLAIMS:

1. A method of upgrading hydrometallurgically recycled graphite, the method including i) hydrometallurgically recycling graphite to provide a hydrometallurgically recycled graphite, and ii) washing a hydrometallurgically recycled graphite with a first acid wash, 5 followed by an alkali wash, followed by a second acid wash to provide a washed graphite material, and subsequently drying the washed graphite material.

2. The method according to claim 1, wherein the washed graphite material is dried under vacuum.

3. The method according to claim 1 or claim 2, wherein the washed graphite is heated to 10 above 25°C to aid drying.

4. The method according to any preceding claim wherein the washed graphite is heated to 90°C or less to aid drying.

5. The method according to any of claims 1 to 4, wherein washing includes multiple washing cycles.15 6. The method according to any preceding claim, wherein the acid is selected from oneor both of a mineral acid and an organic acid.

7. The method according to claim 6, wherein the mineral acid is selected from one or more of nitric acid, hydrochloric acid, hydrofluoric acid, and sulphuric acid.

8. The method according to claim 6, wherein the organic acid is one or more of acetic 20 acid, oxalic acid, malic acid, citric acid, malonic acid, and maleic acid.

9. The method according to any of claims 5 to 8, wherein the graphite is washed with an acid other than sulphuric acid.

10. The method according to claim 5, wherein the base is a metal hydroxide, optionally wherein the metal hydroxide is an alkali metal hydroxide, optionally wherein the alkali 25 metal hydroxide is sodium hydroxide.

11. The method according to any preceding claim, wherein solution used to wash the graphite is recycled, optionally wherein the solution is recycled to a hydrometallurgical extraction process.

12. The method according to any preceding claim, wherein the method includes 30 removing nickel oxide contamination by washing with acid.

13. The method according to any preceding claim, wherein the method includes removing aluminium oxide and / or aluminium (oxy)hydroxide contamination by washing with base.

14. The method of any preceding claim, wherein the pH of the washing solution is equal 35 to or higher than the pH of a hydrometallurgical process from which the22 04hydrometallurgically recycled graphite is provided and / or the pH of the graphite being upgraded.

15. The method according to any of claims 1 to 14, wherein the method includes heating the graphite during washing to from around 40°C to around 90°C to dissolve 5 contaminants.

16. The method according to any of claims 1 to 15, wherein the method includes washing with an acid in a first washing step, a filtering step to separate solids from the washing liquid, and subsequently washing the separated solids with a base.

17. The method according to any preceding claim, wherein during an acid washing step, 10 hydrogen peroxide is provided.

18. The method according to any of claims 1 to 16, wherein during an acid washing step, hydrogen peroxide is absent.

19. The method according to any preceding step, wherein filtering is conducted at temperatures of greater than 50°C.15 20. A non-pyrometallurgically upgraded hydrometallurgically recycled graphitecomprising 93% or more graphitic carbon.

21. The upgraded hydrometallurgically recycled graphite according to claim 20, wherein the graphite comprises crystallites having a minimum feret diameter of 5 microns or greater, and / or wherein the graphite has a spherical morphology.20 22. The upgraded hydrometallurgically recycled graphite according to claim 20 or claim21, wherein graphite comprises 5% or less aluminium oxide, and / or wherein graphite comprises 3% or less lithium nickel oxide.

23. A battery anode material comprising the graphite material according to any of claims 20 to 21.25 24. A battery comprising the graphite material according to any of claims 20 to 22 or abattery anode according to claim 22.

25. The use of a hydrometallurgically recycled graphite in a battery produced from the method of claims 1-19, optionally wherein the use is in a battery anode, optionally wherein the battery is a lithium ion battery, optionally an EV battery.Application No: GB2407081.5Claims searched: 1-7Examiner: Dr Fiona RogersDate of search: 26 July 2024Patents Act 1977: Search Report under Section 17Documents considered to be relevant:Category Relevant to claims Identity of document and passage or figure of particular relevance X 1-7 ACS Sustainable Chemistry &Engineering, vol. 7, no. 24, 2019, Ma Xiaotu et al., High-Performance Graphite Recovered from Spent Lithium-Ion Batteries, pages 19732-19738. See in particular abstract, experimental section, Figure 1, Table SI and Table S3. X 1-7 Waste Management, vol. 85, 2019, Yang Yue et al., A process for combination of recycling lithium and regenerating graphite from spent lithium-ion battery, pages 529-537. See in particular abstract, experimental, Section 3.2, Section 3.4, Figure 1 and Table SI. X 1-7 Journal of Hazardous Materials, vol. 445, 2022, Tian Honghong et al., A facile strategy for reclaiming discarded graphite and harnessing the rate capabilities of graphite anodes, article no. 130607. See in particular abstract, experimental section, Table SI, Table S3 and Table 4. X 1-7 Ionics, vol. 28, no. 5, 2022, Chang Cheng et al., Regeneration of graphite and manganese carbonate from spent lithium-ion batteries for electric vehicles, pages 2239-2246. See in particular abstract, experimental, Figure 2, Table 2, column 1 of page 2244 and conclusions. X 1-7 CN 117163954 A (JINGMEN GREEN ECO MANUFACTURE NEW MATERIAL CO LTD) See in particular EPODOC abstract, WPI abstract accession no. 2023-C9583J and examples. X 1-7 CN 112320794 A (INST PROCESS ENG CAS) See in particular EPODOC abstract, WPI abstract accession no. 2021-15274K, examples and Table 1. X 1-7 Journal of Industrial Ecology, vol. 24, no. 6, 2020, Mohr M et al., Toward a cell-chemistry specific life cycle assessment of lithium-ion battery recycling processes, pages 1310-1322. See in particular abstract, Section 2.2.2 and Figure 3.Categories:____________________________________X Document indicating lack of novelty or inventive A stepY Document indicating lack of inventive step if PDocument indicating technological background and / or state of the art.Document published on or after the declared priority date butcombined with one or more other documents of same category.& Member of the same patent family Ebefore the filing date of this invention.Patent document published on or after, but with priority date earlier than, the filing date of this application.Field of Search:Search of GB, EP. WO &US patent documents classified in the following areas of the UKCX :Worldwide search of patent documents classified in the following areas of the IPC____________HO IM_________________________________________________The following online and other databases have been used in the preparation of this search report SEARCH - NPL, SEARCH - PATENTInternational Classification:Subclass Subgroup Valid From HO IM 0010 / 54 01 / 01 / 2006 C01B 0032 / 215 01 / 01 / 2017 HO IM 0004 / 587 01 / 01 / 2010Application No: GB2407081.5 Examiner: Dr Fiona RogersClaims searched: 8-18 (as filed) / l-21 (as Date of search: 17 December 2024amended)Patents Act 1977Further Search Report under Section 17Documents considered to be relevant:Category Relevant to claims Identity of document and passage or figure of particular relevance X 1-21 WO 2023 / 081979 Al (ECOGRAF LTD) See in particular abstract, Figure 1 and page 3 line 25 to page 5 line 18. X 1-21 CN 115101842 A (UNIV BEIJING TECHNOLOGY) See in particular EPODOC abstract and WPI abstract accession no. 2022-C5432Q. X 1-21 CN 114583315 B (UNIV XIAN JIAOTONG) See in particular EPODOC abstract, WPI abstract accession no. 2022-86145Q. X 1-10, 12-13, 15-16 and 20-21 CN 111072023 A (BEIJING MENGJING GRAPHITE NEW MATERIALS TECH RESEARCH INSTITUTE CO LTD) See in particular EPODOC abstract, WPI abstract accession no. 2020-3846B and example 1. X 1-6, 11-12 and 14-15 CN 114976333 A (HU AT AN TECH DONGGUAN CO LTD) See in particular examples 1-9. X 1-10, 12- 13, 15, 19 and 21 ACS Sustainable Chemistry &Engineering, vol. 7, no. 24, 2019, Ma Xiaotu et al., High-Performance Graphite Recovered from Spent Lithium-Ion Batteries, pages 19732-19738. See in particular abstract, experimental section and Figure 1. X 1-10, 12-13, 15-16, 19 and 21. CN 112320794 A (INST PROCESS ENG CAS) See in particular EPODOC abstract, WPI abstract accession no. 2021-15274K and examples. X 1-6 and 12 CN 117163954 A (JINGMEN GREEN ECO MANUFACTURE NEW MATERIAL CO LTD) See in particular EPODOC abstract, WPI abstract accession no. 2023-C9583J and examples. X 1-6 and 12 Journal of Hazardous Materials, vol. 445, 2022, Tian Honghong et al., A facile strategy for reclaiming discarded graphite and harnessing the rate capabilities of graphite anodes, article no. 130607. See in particular abstract and experimental section.Categories:X Document indicating lack of novelty or inventive step A Document indicating technological background and / or state of the art. Y Document indicating lack of inventive step if P Document published on or after the declared priority date but combined with one or more other documents of same category. before the filing date of this invention. & Member of the same patent family F Patent document published on or after, but with priority date earlier than, the filing date of this application.Field of Search:International Classification:Subclass Subgroup Valid From HO IM 0010 / 54 01 / 01 / 2006 C01B 0032 / 215 01 / 01 / 2017 HO IM 0004 / 587 01 / 01 / 2010

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