A method of recycling

Abstract

A method of separating an electrode active material for recycling comprises (a) providing an electrode active material, wherein the electrode active material comprises carbon black and an active compo

Description

The present description relates to methods of separating electrode active materials for recycling. BACKGROUND Battery manufacturing is environmentally costly in terms of material and energy usage. Direct recycling of electrode active materials is the recovery, regeneration, and reuse of electrode active materials without breaking down their chemical structure. The direct recycling of electrode active materials enables significant savings in greenhouse gas emissions, the time to process materials, and cost. There are increased incentives to move towards circular and sustainable resource consumption, in view of climate change and resource scarcity. Electrode active materials typically comprise an active component and carbon black. There is a need to improve the processes used to recover components of electrode active materials. Commonly used purification methods involve hydrometallurgy, for example leaching with strong acids. The disposal of leaching acids and byproducts presents an environmental hazard. There is a need for an electrode active material recycling method that produces high purity products, particularly at a sufficient purity level to avoid the use of further refinement. Further there is a need to be able to separate an electrode active material into different components for reuse. The present invention seeks to alleviate one or more of the problems detailed herein. SUMMARY OF THE INVENTION In a first aspect, there is provided a method of separating an electrode active material for recycling comprising: a) providing an electrode active material, wherein the electrode active material comprises carbon black and an active component; b) mixing the electrode active material with a solvent to form a feed stream; c) filtering the feed stream in a first filtration system to produce a permeate and a retentate, wherein the first filtration system comprises a first filter unit, wherein the permeate comprises carbon black and solvent, and wherein the retentate comprises active component and solvent. In a second aspect, there is provided method of filtering an electrode active material, wherein the electrode active material comprises carbon black and an active component, the method comprising: a) providing an electrode active material, wherein the electrode active material comprises carbon black and an active component; b) mixing the electrode active material with a solvent to form a feed stream; c) filtering the feed stream in a first filtration system to produce a permeate and a retentate, wherein the first filtration system comprises a first filter unit, wherein the permeate comprises carbon black and solvent, and wherein the retentate comprises active component and solvent. In a third aspect, there is provided a use of a filter to separate carbon black from an electrode active material, wherein the electrode active material comprises carbon black and an active component, the method comprising: a) providing an electrode active material, wherein the electrode active material comprises carbon black and an active component; b) mixing the electrode active material with a solvent to form a feed stream; c) filtering the feed stream in a first filtration system to produce a permeate and a retentate, wherein the first filtration system comprises a first filter unit, wherein the permeate comprises carbon black and solvent, and wherein the retentate comprises active component and solvent. In a fourth aspect, there is provided an apparatus for use in a method according to any of the first to third aspects, comprising a tangential flow filtration system and / or a cross-flow filtration system. In a fifth aspect, there is provided, a method comprising: i) providing an active component produced according to the first aspect; ii) mixing the active material with a second binder and a second solvent to form a slurry; iii) coating a metal layer with the slurry to form a coated metal; iv) drying the coated metal to form an electrode. In a sixth aspect, there is provided a method of producing an electrode for a cell, the method comprising: i) providing an active component and providing carbon black, wherein the carbon black is produced according to the first aspect; ii) mixing the active material with carbon black, a second binder and a second solvent to form a slurry; iii) coating a metal layer with the slurry to form a coated metal; iv) drying the coated metal to form an electrode. In a seventh aspect, there is provided a method of producing an electrode for a cell, the method comprising: i) providing an active component and providing carbon black; ii) mixing the active material with carbon black, a second binder and a second solvent to form a slurry, wherein the binder is produced according to the second aspect iii) coating a metal layer with the slurry to form a coated metal; iv) drying the coated metal to form an electrode. In an eighth aspect, there is provided an electrode produced by the method of the seventh aspect. In a ninth aspect, there is provided a method of producing a cell comprising assembling the electrode produced by the method according to any of the fifth to seventh aspects, or an electrode according to the eighth aspect into a cell. In a tenth aspect, there is provided a cell produced by the method of the ninth aspect. In an eleventh aspect, there is provided an active component obtainable by the method of the first or second aspect. DESCRIPTION OF THE DRAWINGS The present invention will now be described by way of example with reference to the accompanying drawings. In the drawings: Figure 1 shows a flow chart of a filtration system Figure 2 shows a flow chart of a filtration system and a permeate ultrafiltration system Figure 3 shows an apparatus for use Figure 4 shows the retentate and permeate of a filtered pre-mixed battery-grade slurry Figures 5a and 5b show scanning electron microscope images of filtered graphite Figure 6a and 6b show scanning electron microscope images of filtered LFP Figure 7 shows galvanostatic cyclability of recycled graphite half cells Figure 8 shows galvanostatic cyclability of recycled LFP half cells DETAILED DESCRIPTION The following description is presented to enable any person skilled in the art to make and use the invention and is provided in the context of a particular application. Various modifications to the disclosed embodiments will be apparent to those skilled in the art. The general principles defined herein may be applied to other embodiments and applications without departing from the present invention. Embodiments are described by way of example only. In a first aspect of the invention, there is provided a method of separating an electrode active material for recycling comprising: a) providing an electrode active material, wherein the electrode active material comprises carbon black and an active component; b) mixing the electrode active material with a solvent to form a feed stream; c) filtering the feed stream in a first filtration system to produce a permeate and a retentate, wherein the first filtration system comprises a first filter unit, wherein the permeate comprises carbon black and solvent, and wherein the retentate comprises active component and solvent. The method allows the separation of materials in an electrode active material by filtration, particularly the separation of carbon black from an active component. Electrode active materials typically comprise carbon black and an active material. When a battery is made, it is important to know the relative amounts of each component of the electrode active material to produce electrodes such as anodes and cathodes with the desired properties. This means that it is advantageous to split an electrode active material into component parts so that these can each be recycled into new electrode active materials in known amounts. Carbon black used in electrode active materials may have D50 particle size of less than about 200 nm, preferably about 5 nm to about 200 nm. It can therefore be difficult to separate carbon black from other components of the electrode active material due to its small size. Surprisingly, the carbon black can be separated from an active material by filtration. This allows carbon black to pass through a filter with solvent as the permeate. The active material typically has a larger particle size and will be the retentate with solvent. It will be appreciated that a first portion of the solvent will pass through the first filter unit as part of the permeate and a second portion of the solvent will be part of the retentate. It is a particular advantage of the invention that solvent is present in both the permeate and the retentate as this aids the separation of the carbon black from the feed stream as this helps prevent the carbon black from settling onto the active component. It is an advantage that the carbon black and active component do not require acid treatment, which can damage the structure of these. It is an advantage that the carbon black and active component do not require the application of substantial heat to be separated, which can damage the structure of these components. This means that the carbon black and active component can be recycled and used to make batteries with confidence that the properties of these is known. Preferably, the permeate is fluid. It is an advantage that the carbon black passes through a filter in the first filter unit, together with solvent as this helps wash the carbon black through the filter. Preferably the retentate is fluid. It is an advantage that the active component is conveyed out of the first filter unit together with solvent as this helps prevent the carbon black from settling on to the active component. Preferably, the retentate comprises a first portion of the solvent and the permeate comprises a second portion of the solvent. It will be appreciated that there is solvent present in both the permeate and the retentate. Preferably, the method does not comprise the use of acid, preferably the method does not comprise the use of an acid with a pH of less than about 3, preferably, the method does not comprise the use of citric acid or sulphuric acid. Preferably, the pH of the feed stream is greater than about 3, preferably greater than about 5, preferably greater than about 6, preferably greater than about 7, preferably greater than about 8. It is an advantage of the invention that acids are not needed in the recycling process. Use of an acid can damage the structure of an active component and therefore the recycling process is improved by not needing to use an acid. Further, this is more environmentally friendly. Preferably, the first filtration system comprises a continuous flow filtration system. This allows the carbon black to be washed out of the feed stream and to pass through the first filter unit as the permeate. This continuous process increases the amount of carbon black that passes through the first filter unit as the permeate. Preferably, the first filtration system comprises a tangential flow filtration system. This allows the carbon black and solvent to pass through the first filter unit as the permeate, while retaining the active component as a retentate. The feed stream typically flows along the first filter unit and the permeate can pass through the first filter unit substantially perpendicular to the direction of the feed stream. Preferably, wherein the first filtration system comprises a cross-flow filtration system. This allows the feed stream to pass through the first filter unit substantially parallel to the filter in the first filter unit. This aids the separation of the carbon black as the permeate. Preferably, the first filter unit comprises a flow path and a filter, wherein the filter extends along the flow path, wherein the feed stream enters the flow path and is filtered to produce the retentate which follows the flow path and the permeate which passes through the filter. The flow of the retentate through the filter means that the carbon black does not have the opportunity to settle onto the active component, but can pass through the filter as the permeate. This aids the filtration process. Preferably, the first filter unit is substantially cylindrical. Preferably, the first filter unit comprises a bore through a filter, wherein the flow path is along the bore and wherein the permeate passes through the filter. Preferably the first filter unit comprises a cylindrical filter. This is a suitable arrangement to maintain the flow through the filter and the separation of the carbon black from the active component. Preferably, a further solvent is added to the feed stream, preferably wherein the further solvent comprises the same solvent as the solvent of step (b). The addition of further solvent aids the flow of the feed stream through the first filter unit as some of the solvent and carbon black passes through a filter in the first filter unit. It is particularly useful to use the same solvent so that there is only one solvent system present for ease of recycling. Preferably, step (c) further comprises recirculating the retentate through the first filtration system. This allows further carbon black to pass through the filter in the first filter unit as the permeate. It will be appreciated that the first pass of the feed stream may not remove all of the carbon black from the retentate, and that by recirculating the retentate, further carbon black can be removed from the retentate. Preferably, the retentate from step (c) is filtered through a further filtration system. Preferably the further filtration system comprises any of the features of the first filtration system. It will be appreciated that the first pass of the feed stream may not remove all of the carbon black from the retentate, and that by filtering the retentate through a further filtration system, further carbon black can be removed from the retentate. Preferably, step (c) further comprises recirculating the retentate through the further filtration system. This can remove further carbon black from the retentate into the permeate. Preferably, the method further comprises deagglomerating the electrode active material, preferably prior to step (a) and / or after step (b). Preferably deagglomerating the electrode active material comprises using ultrasound, high shear mixing, heating, adding a surfactant or a combination of two or more thereof. If required, a deagglomeration step can be carried out to deagglomerate the electrode active material. Such a step aids the filtration processes by deagglomerating the electrode active material prior to the filtration step. Preferably, the method comprises analysing the amount of carbon black present in the retentate and if the retentate comprises more than a predetermined level of carbon black, recirculating the retentate through the first filtration system and / or filtering the retentate through a further filtration system, preferably wherein the predetermined level of carbon black is less than about 1 wt% of the carbon black on a dry weight basis, preferably less than about 0.1 wt% of the carbon black on a dry weight basis, preferably less than about 0.01 wt% of the carbon black on a dry weight basis, preferably substantially no carbon black. Such an analysis step allows the user to determine how much carbon black remains in the retentate, and if this is more than the predetermined amount, the retentate can be further filtered to remove more carbon black. Preferably, the first filtration system comprises a microfilter, preferably wherein the microfilter has a pore size of less than about 10 pm, preferably less than about 5 pm, preferably less than about 1 pm, preferably less than about 0.5 pm, preferably in the range of about 0.1 pm to about 5 pm, preferably in the range of about 0.5 pm to about 2 pm. Such a microfilter is suitably sized to allow carbon black to pass through the microfilter in the permeate while retaining active component in the retentate. Preferably, the first filtration system comprises an ultrafilter, preferably wherein the ultrafilter has a pore size of less than 0.1 pm, preferably less than 0.05 pm, preferably in the range of about 0.01 pm to about 0.05 pm. Such an ultrafilter is suitably sized to allow carbon black to pass through the microfilter in the permeate while retaining active component in the retentate. Preferably, the first filtration system comprises a microfilter as described herein and a further filtration system comprises an ultrafilter as described herein. This arrangement allows the retentate to be filtered through a finer filter to aid the removal of carbon black from the retentate. Put another way, the retentate of the first filtration system is passed through a finer filter. Preferably, sequential filtering steps are performed with finer filters to minimise clogging of each filter and to produce a higher yield of carbon black in the permeate. Preferably the first filtration system comprises a membrane. This allows high precision removal of the carbon black from the feed stream and retentate. Preferably, the first filtration system is under vacuum. This helps the permeate pass through the filter in the first filter unit as the permeate is drawn through the filter under vacuum. Preferably there is a pressure difference across the filter in the first filter unit, preferably the pressure is higher inside the filter than outside the filter. Preferably the pressure is higher on the incident flow side and lower once passed through the filter, put another way, the pressure is lower downstream of the filter. This aids the filtration process by drawing the permeate through the filter. Preferably, the retentate comprises less than about 1 wt% of the carbon black on a dry weight basis, preferably less than about 0.1 wt% of the carbon black on a dry weight basis, preferably less than about 0.01 wt% of the carbon black on a dry weight basis, preferably substantially no carbon black. It is an advantage of the invention that carbon black can be removed from the feed stream, such that the retentate comprises such low amounts, or substantially no carbon black. It will be appreciated that the retentate may be recirculated through the first filtration system and / or a further filtration system to achieve the desired removal of carbon black. Preferably, the permeate comprises less than about 1 wt% of the active component on a dry weight basis, preferably less than about 0.1 wt% of the active component on a dry weight basis, preferably less than about 0.01 wt% of the active component on a dry weight basis, preferably substantially no active component. It is desirable for the permeate to comprise low levels of active component, or substantially no active component. Typically, the active component has a larger particle size and therefore does not pass through the filter as the permeate. Preferably, the method further comprises: d) drying the retentate to form a dried retentate, wherein the dried retentate comprises the active component, preferably wherein the dried retentate comprises less than about 1 wt% of the carbon black on a dry weight basis, preferably less than about 0.1 wt% of the carbon black on a dry weight basis, preferably less than about 0.01 of the wt% carbon black on a dry weight basis, preferably substantially no carbon black; and / or e) drying the permeate to form a dried permeate, wherein the dried permeate comprises the carbon black, preferably wherein the dried permeate comprises less than about 1 wt% of the active component on a dry weight basis, preferably less than about 0.1 wt% of the active component on a dry weight basis, preferably less than about 0.01 wt% of the active component on a dry weight basis, preferably substantially no active component. It is advantageous to dry the retentate and / or the permeate to remove the solvent and isolate the solid matter. This allows the carbon black in the permeate to be recycled. This allows the active component in the retentate to be recycled. Preferably, “dried” means comprises less than about 5 wt% solvent, preferably less than about 1 wt% of the solvent, preferably less than about 0.1 wt% of the solvent, preferably less than about 0.01 wt% of the solvent, preferably substantially no solvent. Preferably, the temperature used in step (d) and / or step (e) is in the range of about 40°C to about 150°C, preferably in the range of about 60°C to about 120°C. Such temperatures are suitable for removing the solvent. Preferably the temperature used in step (d) and / or (e) is below about 300°C. Preferably, step (d) and / or step (e) comprise drying at less than atmospheric pressure, preferably under vacuum. This aids the removal of the solvent. Preferably, step (d) and / or step (e) comprise drying at atmospheric pressure. The drying step may be carried at atmospheric pressure to reduce costs associated with working at lower or higher pressures. Preferably, the active component separated from the electrode active material by any of the methods described herein is of substantially the same form as the active component used to form the electrode active material. Preferably the separated active component has a particle size within ± 10% of the particle size of the active component before the method of separation is performed, preferably within ± 5%, preferably within ± 2%. For example, graphite filtered and dried from the retentate has a morphology and / or size substantially the same as the morphology and size of graphite prior to filtration. For example, the morphology of pristine graphite is substantially spherical and the graphite, having been processed by the method of separating, is substantially spherical. Advantageously, the method of separating an active component permits the collection of said active component in a suitable form for reuse in a battery. Preferably, the separated active component does not require further processing before reuse. Preferably, the electrode active material further comprises a binder, preferably wherein the permeate further comprises binder. A binder may be present in an electrode active material and it is preferable to be able to recycle the binder, such as by further processing the permeate. The binder preferably passes through the filter into the permeate due to the particle size of the binder. Preferably, the binder passes through the filter into the permeate by dissolving in the solvent. Preferably, the electrode active material comprises about 0.5 wt% to about 5 wt% carbon black, about 85 wt% to about 95 wt% active component and about 0.1 wt% to about 5 wt% binder, on a dry weight basis. Such amounts are typically used in electrode active materials. Preferably, the binder comprises carboxymethyl cellulose (CMC), styrene-butadiene rubber (SBR), polyacrylic acid (PAA), polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), or a combination of two or more thereof, preferably styrene-butadiene rubber / carboxymethyl cellulose (SBR / CMC), PVDF ora combination of two or more thereof. Such binders are commonly used in electrode active materials to make electrodes. Preferably, the method further comprises filtering the permeate by a permeate ultrafiltration system to produce an ultrafiltration retentate and an ultrafiltration permeate, wherein the ultrafiltration retentate comprises carbon black and solvent and wherein the ultrafiltration permeate comprises binder and solvent. It is an advantage of the invention that the permeate can be further filtered by ultrafiltration to separate the carbon black and the binder. Preferably, the method further comprises drying the ultrafiltration retentate, wherein the dried ultrafiltration retentate comprises carbon black, preferably wherein the dried ultrafiltration permeate comprises less than about 1 wt% of the binder on a dry weight basis, preferably less than about 0.1 wt% of the binder on a dry weight basis, preferably less than about 0.01 wt% of the binder on a dry weight basis, preferably substantially no binder. It is advantageous to dry the ultrafiltration retentate to remove the solvent and isolate the solid matter. Preferably, the method further comprises drying the ultrafiltration permeate, wherein the dried ultrafiltration permeate comprises binder, preferably wherein the dried ultrafiltration permeate comprises less than about 1 wt% of the carbon black on a dry weight basis, preferably less than about 0.1 wt% of the carbon black on a dry weight basis, preferably less than about 0.01 wt% of the carbon black on a dry weight basis, preferably substantially no carbon black. It is advantageous to dry the ultrafiltration permeate to remove the solvent and isolate the solid matter. Preferably the method comprises using reverse osmosis to remove binder from the ultrafiltration permeate. This allows the binder to be isolated and reused, further the solvent can be isolated and reused. Preferably, wherein the method comprises recycling the solvent. Preferably, the electrode active material comprises the active component, the carbon black and the binder, wherein the method comprises separating the active component, the carbon black and the binder. It is an advantage of the invention that three components of the electrode active material can be separated, recycled and reused, such as in the production of electrodes for batteries. Preferably the method comprises separating the active component, the carbon black, the binder and at least part of the solvent. It is an advantage of the invention that three components of the electrode active material and the solvent can be separated, recycled and reused, such as in the production of electrodes for batteries. Preferably, the active component comprises a cathode active component. Preferably, the active component comprises an anode active component. Such materials are suitable for recycling. Preferably, the anode active component comprises graphite, niobium oxide, titanium niobium oxide, lithium titanium oxide, graphene, sodium titanium oxide, sodium titanium phosphate oxide, sodium titanium phosphate, sodium metatitanate powder, hard carbon, silicon or a combination of two or more thereof; preferably graphite. Such materials are typically used in anodes and can be separated from carbon black as described herein. Preferably, cathode active component comprises lithium iron phosphate (LFP), lithium manganese iron phosphate (LMFP), nickel manganese cobalt (NMC), lithium nickel cobalt aluminium oxide (NCA), lithium cobalt oxide (LCO), lithium manganese oxide (LMO), lithium manganese nickel oxide (LMNO), lithium nickel oxide (LNO), sodium chromium oxide, sodium cobalt oxide, sodium manganese oxide, sodium cobalt phosphate, sodium nickel phosphate, sodium iron phosphate, sodium manganese phosphate, sodium iron hexacyanoferrate, sodium manganese hexacyanoferrate, sodium vanadium phosphate, sulphur, or a combination of two or more thereof, preferably NMC, LFP or a combination thereof. Such materials are typically used in cathodes and can be separated from carbon black as described herein. Preferably, the carbon black is particulate, preferably wherein the carbon black has an D50 particle size of less than about 200 nm, preferably about 5 nm to about 200 nm. Preferably the D50 particle size is measured by laser diffraction or sieving, preferably by laser diffraction. Carbon black typically has this particle size when used in the manufacture of electrodes. This particle size can be separated from the active component which typically has a much larger particle size. Preferably, the solvent comprises at least one of water, methyl ethyl ketone (MEK), N-Methyl-2-pyrrolidone (NMP), tetrahydrofuran (THF), chloroform, xylene, toluene, N,N-dimethylformamide (DMF), Dimethylsulfoxide (DMSO), Dimethylacetamide (DMAc) or acetone, or a combination of two or more thereof, preferably water and / or NMP, preferably water. Such solvents can suspend the carbon black and active material in the feed stream. Further, where a binder is present it can be dissolved in the solvent. A suitable solvent can be chosen for a binder system. Preferably, the carbon black is substantially insoluble in the solvent. Preferably the active component is substantially insoluble in the solvent. This allows the carbon black and active component to be separated by filtration. Preferably, the binder is substantially soluble in the solvent. Typically, the binder is dissolved in the solvent during the production of electrodes and this facilitates the separation of the binder from the carbon black. Preferably, the liquid to solid ratio in the feed stream is at least about 2:1, preferably about 2:1 to about 50:1, preferably about 5:1 to about 20:1. This level of solvent helps wash the carbon black through the filter. Preferably, the active component comprises graphite, the binder comprises styrene butadiene rubber (SBR) and / or carboxymethyl cellulose (CMC), and the solvent comprises water. This is a common system used in the production of electrodes, particularly anodes. The SBR and / or CMC binder is substantially soluble in water and preferably passes through the filter with the carbon black. Preferably, the active component comprises LFP, the binder comprises styrene butadiene rubber (SBR) and / or carboxymethyl cellulose (CMC), and the solvent comprises water. This is a common system used in the production of electrodes, particularly cathodes. The SBR and / or CMC binder is substantially soluble in water and preferably passes through the filter with the carbon black. Preferably, the active component comprises NMC, the binder comprises PVDF, and the solvent comprises N-methylpyrrolidone (NMP). This is a common system used in the production of electrodes, particularly cathodes. The PVDF binder is substantially soluble in NMP and preferably passes through the filter with the carbon black. Preferably, the active component is particulate, preferably wherein the active component has an D90 particle size in the range of about 1 pm to about 50 pm. Such particle sizes can be separated from the carbon black which typically has a much smaller particle size. Such particle sizes are suitable for use in the production of electrodes. Preferably, the electrode active material is comprised in an electrode active material slurry, preferably an uncured electrode active material slurry. The (uncured) electrode active material slurry preferably comprises carbon black, an active component, a slurry solvent and an optional binder, wherein the slurry solvent preferably comprises the same solvent as the solvent described herein. In battery manufacture, there may be waste electrode active material slurry due to the production process due to excess slurry or slurry not meeting the required specification. Typically, this slurry is a waste material. It is an advantage that this can be separated into different components to be reused. It is an advantage for the slurry solvent to be the same as the solvent described herein for ease of processing. Preferably, the electrode active material comprises a cured electrode active material, preferably a solid cured electrode active material. It is an advantage of the invention that cured electrode active material can also be separated into different components. Preferably, the temperature of the mixture in step (b) and step (c) is each independently in the range of about 10 °C to about 80 °C, preferably about 20 °C to about 60 °C, preferably about 20 °C to about 40 °C, preferably about 20 °C to about 25 °C, preferably about room temperature. It is an advantage of the invention that it can be carried out at a range of temperatures. It is particularly advantageous to carry out the invention at ambient temperature such as room temperature. Preferably, the weight ratio of the active component to the carbon black in the electrode active material is in the range of about 20:1 to about 120:1, preferably in the range of about 25:1 to about 100:1. These levels are typical for amounts of carbon black and active component used in the manufacture of electrodes. Preferably, the permeate is heated to a temperature of at least about 300 °C to produce a heat treated permeate, preferably in the range of about 350 °C to about 490 °C, wherein in the heat treated permeate preferably comprises at least 90 wt% carbon black, preferably at least 95 wt% carbon black, preferably at least 99 wt% carbon black, preferably substantially all carbon black. Heating the permeate has the function of removing solvent and binder, if present, to leave carbon black in the heat treated permeate. While the solvent may be removed at lower temperatures, the binder typically needs to be heated to the described temperatures to be removed. Preferably, the retentate is heated to a temperature of at least about 300 °C to produce a heat treated retentate, preferably in the range of about 350 °C to about 490 °C, wherein in the heat treated permeate preferably comprises at least 90 wt% active component, preferably at least 95 wt% active component, preferably at least 99 wt% active component, preferably substantially all active component. Heating the retentate has the function of removing solvent and binder, if present, to leave active component in the heat treated retentate. While the solvent may be removed at lower temperatures, the binder typically needs to be heated to the described temperatures to be removed. It will be appreciated that the majority of the binder will be part of the permeate. Should there be any further binder present, this can be removed by heat treatment as described herein. Preferably, the ultrafiltration retentate is heated to a temperature of at least about 300 °C to produce a heat treated ultrafiltration retentate, preferably in the range of about 350 °C to about 490 °C, wherein in the heat treated ultrafiltration retentate preferably comprises at least 90 wt% carbon black, preferably at least 95 wt% carbon black, preferably at least 99 wt% carbon black, preferably substantially all carbon black. It will be appreciated that the ultrafiltration retentate has already been through the ultrafiltration process to separate it from binder present. Should there be any further binder present, this can be removed by heat treatment as described herein. It is preferable to have carried out the ultrafiltration step as this allows binder to be removed from the permeate and recycled, with only residual binder heated to be removed. Preferably, the ultrafiltration permeate is not heated to a temperature of at least about 300 °C as this would remove the binder and the solvent. In a further aspect, there is described a method of filtering an electrode active material, wherein the electrode active material comprises carbon black and an active component, the method comprising: a) providing an electrode active material, wherein the electrode active material comprises carbon black and an active component; b) mixing the electrode active material with a solvent to form a feed stream; c) filtering the feed stream in a first filtration system to produce a permeate and a retentate, wherein the first filtration system comprises a first filter unit, wherein the permeate comprises carbon black and solvent, and wherein the retentate comprises active component and solvent. This method can be used to separate carbon black and the active component as described herein. It will be appreciated that the features of the method of separating an electrode active material for recycling also apply to the method of filtering an electrode active material. In a further aspect, there is described a use of a filter to separate carbon black from an electrode active material, wherein the electrode active material comprises carbon black and an active component, the method comprising: a. providing an electrode active material, wherein the electrode active material comprises carbon black and an active component; b. mixing the electrode active material with a solvent to form a feed stream; c. filtering the feed stream in a first filtration system to produce a permeate and a retentate, wherein the first filtration system comprises a first filter unit, wherein the permeate comprises carbon black and solvent, and wherein the retentate comprises active component and solvent. It will be appreciated that the features of the method of separating an electrode active material for recycling also apply to the use described herein. Preferably, the electrode active material further comprises binder and wherein a permeate ultrafiltration system is used to separate the binder from the electrode active material. The use may therefore allow the carbon black, active component and binder to be separated. These can then be recycled into a battery. In a further aspect, there is described an apparatus for use in a method according to any preceding claim, comprising a tangential flow filtration system and / or a cross-flow filtration system. In a further aspect, there is described an apparatus comprising a first container for an electrode active material, and a second container for a solvent, wherein the first container and second container are in fluid communication with a third container for mixing the electrode active material and the solvent to form a feed stream, wherein the third container is in fluid communication with a first filtration system for filtering the feed stream, wherein the first filtration system comprises a loop through a first filter unit, wherein the first filter unit is in fluid communication with: A. a fourth container for receiving a permeate from the first filter unit, B. a fifth container for receiving a retentate from the first filter unit, and C. a recirculation loop for directing the retentate back into the first filter unit. Preferably, the apparatus comprises a pump, preferably wherein the pump pumps fluid through the first filtration system. Such an apparatus is suitable for use in the method described herein. In a further aspect, there is described a method of producing an electrode for a cell, the method comprising: i) providing an active component produced as described herein; ii) mixing the active material with a second binder and a second solvent to form a slurry; iii) coating a metal layer with the slurry to form a coated metal; iv) drying the coated metal to form an electrode. Preferably, the method of producing an electrode for a cell further comprises providing carbon black produced as described herein, wherein step ii) comprises mixing the active material with the carbon black, a second binder and a second solvent to form a slurry. Preferably the second binder has any of the features of the binder described herein. Preferably the second solvent has any of the features of the solvent described herein. Preferably, the method of producing an electrode for a cell, wherein the second binder comprises binder produced as described herein. In a further aspect, there is described a method of producing an electrode for a cell, the method comprising: i) providing an active component and providing carbon black, wherein the carbon black is produced according as described herein; ii) mixing the active material with carbon black, a second binder and a second solvent to form a slurry; iii) coating a metal layer with the slurry to form a coated metal; iv) drying the coated metal to form an electrode. Preferably, the method of producing an electrode for a cell, wherein the second binder comprises binder produced as described herein. In a further aspect, there is described a method of producing an electrode for a cell, the method comprising: i) providing an active component and providing carbon black; ii) mixing the active material with carbon black, a second binder and a second solvent to form a slurry, wherein the binder is produced as described herein; iii) coating a metal layer with the slurry to form a coated metal; iv) drying the coated metal to form an electrode. Preferably, wherein step iv) comprises curing the binder. Preferably, the active component comprises graphite, wherein the second binder comprises CMC and / or SBR, and wherein the metal layer comprises copper. Preferably, the active component comprises LFP, wherein the second binder comprises CMC and / or SBR, and wherein the metal layer comprises aluminium. Preferably, the active component comprises NMC, wherein the second binder comprises PVDF, and wherein the metal layer comprises aluminium. In a further aspect, there is described an electrode produced by the method described herein. In a further aspect, there is described a method of producing a cell comprising assembling the electrode produced by the method described herein, or an electrode described herein into a cell. In a further aspect, there is described a cell produced by the method described herein. In a further aspect, there is described an active component obtainable by the method of separating described herein. Preferably the active component comprises a cathode active component and / or an anode active component. Preferably the cathode active component comprises LFP Preferably the anode active component comprises graphite. Preferably the active component obtainable by the method of separating has a purity greater than about 90 wt%, preferably greater than about 95 wt%, preferably about 99 wt%. It is an advantage of the present invention that the active component can be obtained with such levels of purity. Advantageously the method may be used to obtain active material at a suitable purity for reuse in an electrode. The purity may be determined by known techniques such as Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES). The active component may be obtained by the method of separating described herein. DETAILED DESCRIPTION OF DRAWINGS Figure 1 shows a flow chart of the filtration system with the following features: Afeed stream comprising an electrode active material and a solvent, wherein the electrode active material comprises carbon black and an active component passes into a first filtration system. The output from the first filtration system is a permeate comprising carbon black and solvent, and a retentate comprising active component and solvent. The permeate can then be dried to isolate carbon black from the solvent. It is preferable that the permeate does not comprise substantially any active component. This is due to the particle size of the active component inhibiting the active component from passing through the first filtration system as a permeate. The retentate may still comprise some carbon black, for example if some of the carbon black has not yet passed through the filtration system as the permeate, but instead remains in the retentate. The retentate can be filtered again to remove further carbon black, such as by recirculating the retentate back through the first filtration system. Alternatively, the retentate can be filtered through a further filtration system. The output from the further filtration system is a permeate comprising carbon black and solvent, and a retentate comprising active component and solvent. The retentate can be filtered one or more times in one or more filtration systems to remove the carbon black. The retentate can be analysed for the presence of carbon black to determine if further filtering is required. Preferably, the retentate can follow one of three routes: 1) retentate can be dried to give active component 2) retentate can be recirculated through the first filtration system 3) retentate can be directed to a further filtration system In option 1), the retentate can then be dried to isolate active material from the solvent. In options 2) and 3), the retentate can be further filtered to remove further carbon black. It will be appreciated that eventually, the permeate from the first filtration system and / or the further filtration system may not comprise any further carbon black as it has already been removed by a previous filtering step. The permeate from the system as a whole will comprise carbon black and solvent. The permeate may be heat treated to dry it and to remove any impurities, such as binder. The retentate may be heat treated to dry it and to remove any impurities, such as binder. Preferably, further solvent can be added to the first filtration system. This aids the filtration process as solvent is removed from the feed stream as part of the permeate. Figure 2 shows a flow chart of the filtration system and a permeate ultrafiltration system with the following features: A feed stream comprising an electrode active material, a binder and a solvent, wherein the electrode active material comprises carbon black and an active component passes into a first filtration system. The output from the first filtration system is a permeate comprising carbon black, binder and solvent, and a retentate comprising active component and solvent. The retentate could then be further filtered to remove carbon black by recirculation through the first filtration system (not shown) and / or a further filtration system (not shown) as described for figure 1. The retentate can then be dried to isolate active material from the solvent. The permeate can then pass through a permeate ultrafiltration system. The output from the permeate ultrafiltration system is an ultrafiltration permeate comprising binder and solvent, and an ultrafiltration retentate comprising carbon black and solvent. The ultrafiltration retentate may be recirculated filtered through the permeate ultrafiltration system (not shown) or further filtered through a further permeate ultrafiltration system (not shown). This further filtration of the ultrafiltration retentate can remove further binder from the ultrafiltration retentate. It will be appreciated that eventually, the ultrafiltration permeate from the first filtration system and / or the further permeate ultrafiltration system may not comprise any further binder as it has already been removed by a previous filtering step. The ultrafiltration permeate from the system as a whole will comprise binder and solvent. The ultrafiltration permeate may be heat treated to dry it and to remove any impurities. Reverse osmosis may be used to separate binder and solvent in the ultrafiltration permeate. The ultrafiltration retentate may be heat treated to dry it and to remove any impurities, such as binder, if the binder has not all been removed. It will be appreciated that further solvent can be added to the permeate ultrafiltration system. This aids the ultrafiltration process as solvent is removed from the feed stream as part of the ultrafiltration permeate. Figure 3 shows an apparatus for separating an electrode active material for recycling. A first container 1, comprises the electrode active material, preferably as a slurry. A second container 2 comprises solvent. The electrode active material and solvent are mixed in a third container 3 to form a feed stream which passes into a first filtration system 4. The first filtration system 4 is shown as a flow path 6 in the form of a loop with a pump 5. The feed stream passes through the first filter unit 7 which extends along the flow path. The permeate passes from the first filter unit 7 into a fourth container 8. The retentate continues along the flow path and can either be recirculated though the first filter unit 7, or directed into a fifth container 9. The apparatus can be used to separate carbon black from the active component. EXAMPLES Example 1 A pre-mixed battery-grade slurry comprising graphite, carbon black, a SBR / CMC binder and water was provided. The slurry was mixed with water to form a feed stream. The feed stream was passed through a filtration system. Figure 4 shows the permeate 12 and the retentate 14 from the filtration system. As shown, the permeate 12 comprises solvent and carbon black as shown by the substantially opaque suspension. The permeate further comprises the binder. The retentate 14 comprises graphite and solvent and is shown as a suspension which is substantially more transparent than the permeate 12. This shows that the filtration system has separated active material, namely graphite, from the carbon black. Example 2 A slurry comprising battery-grade (ABP-200) graphite, carbon black, a binder and a solvent was provided. The ABP-200 graphite had a D10 particle size of 10.26 pm, a D50 particle size of 17.13 pm, a D90 particle size of 27.24 pm, as measured by laser diffraction using a Mastersizer 3000 made by Malvern Panalytical. The slurry was mixed with a solvent to form a feed stream. The feed stream was passed through a filtration system, according to the method described herein. The retentate comprising graphite and solvent was separated from the permeate. The retentate was dried to remove the solvent. The dried graphite was sized using the Mastersizer 3000. The graphite had a D10 particle size of 10.96 pm, a D50 particle size of 18.37 pm, a D90 particle size of 28.93 pm. This shows that the particle sizes of processed graphite, separated from a slurry by the filtration method described herein, are within 10% of the size of pristine, ABP-200 graphite. The graphite separated from the slurry is suitable for reuse in a further slurry for an electrode. The mass of graphite recovered after filtration was greater than 90% of the mass of graphite used to prepare the slurry, indicating a yield of greater than 90%. Figures 5a and 5b show SEM images of the processed (filtered and dried) graphite. Figure 5a is atx500 magnification. Figure 5b is atx5000 magnification. It is seen that the graphite is substantially free of carbon black, i.e. the carbon black has been removed from the graphite. It is seen that the graphite has a substantially spherical morphology. It is seen that the surface of the graphite is substantially smooth, which indicates that the process of filtration does not substantially roughen the surface of the graphite. As seen in Figures 5a and 5b, the graphite particles have a rounded morphology. The rounded morphology of the graphite may be used to characterise the method of separation as not involving substantial heat. If graphite is processed using substantial heat (e.g. greater than about 300 °C) then the graphite morphology may not be rounded. Graphite processed by a method involving substantial heat may not be suitable for reuse in an electrode because the morphology is not rounded. The electrochemical performance of the pristine ABP-200 graphite and the processed (recycled) graphite were compared. The electrochemical properties and results are shown in Table 1. The retention of recycled graphite at 100 cycles is higher than the retention of pristine graphite. Table 1 Property ABP-200 graphite Recycled graphite Capacity at 1C (mAh / g) 367 ±3 317 ±4 Retention at 100 cycles (%) 95.0 ±0.3 98.8 ±0.3 Voltage hysteresis (V) 0.11 0.10 Example 3 A slurry comprising battery-grade lithium iron phosphate (LFP), carbon black, a binder and a solvent was provided. The slurry was mixed with a solvent to form a feed stream. The feed stream was passed through a filtration system, according to the method described herein. The retentate comprising LFP and solvent was separated from the permeate. The retentate was dried to remove the solvent. Figures 6a and 6b show SEM images of the processed (filtered and dried) LFP. Figure 6a is at x2500 magnification. Figure 6b is at x5000 magnification. It is seen that the LFP is substantially free of carbon black, i.e. the carbon black has been removed from the LFP. It is seen that the LFP is in the form of discrete particles. The surface structure seen in the SEM images has a high surface roughness which indicates that the LFP has been processed without substantial heat. The application of high temperature (e.g. greater than about 300 °C) to LFP may cause a change in oxidation state of the LFP and / or agglomeration of particles. LFP processed by a method involving substantial heat may not be suitable for reuse in an electrode. Without being bound by theory, it is theorised that a change in oxidation state of LFP due to exposure to high temperature may make the LFP unusable as electrode material. Example 4 Half cells were produced and tested to assess the electrochemical performance of the recycled active material in respective electrodes. The galvanostatic cyclability of recycled graphite half cells is shown in figure 7. The galvanostatic cyclability of recycled LFP half cells is shown in figure 8. The width of each layer in the coin cells is 1.2 cm. Anode preparation will be described. Graphite was separated from an electrode active material, comprising carbon black and graphite as the active component by mixing the electrode active material with a solvent to form a feed stream and filtering the feed stream in a first filtration system to produce a permeate and a retentate, wherein the first filtration system comprises a first filter unit, wherein the permeate comprises carbon black and solvent, and wherein the retentate comprises active component and solvent. The graphite was dried for 12 hours at 120°C under vacuum to produce a graphite powder. The graphite powder was transferred to an argon filed glovebox for coin cell assembly. An anode slurry was prepared by mixing 90 wt% graphite powder with 5 wt% PVDF binder (Arkema), 5 wt% carbon black (Imerys Super P™ Li), and NMP solvent. The slurry was mixed for 30 minutes at 2000 rpm in a Thinky mixer (Intertronics). The slurry was cast on copper foil, 50 pm thickness, 99.9% purity (Advent RM), to form an anode. The anode was dried for 12 hours at 120°C under vacuum. The resulting anode thickness was 65 pm and mass was 50.6 mg. The electrode was assembled into a coin cell with a glass microfibre separator (Whatman™), having a thickness of 0.26 mm, a lithium layer having a thickness of 0.38 mm and mass of 16 mg. An electrolyte was applied to the layers of the cell, the electrolyte being 1 M LiPF6 in ethylene carbonate (EC) / ethyl methyl carbonate (EMC) 3:7 wt% with 2 wt% vinylene carbonate (VC). The electrolyte bottle was opened four months prior to cell assembly. Cathode preparation will be described. Lithium iron phosphate (LFP) was separated from an electrode active material, comprising carbon black and LFP as the active component by mixing the electrode active material with a solvent to form a feed stream and filtering the feed stream in a first filtration system to produce a permeate and a retentate, wherein the first filtration system comprises a first filter unit, wherein the permeate comprises carbon black and solvent, and wherein the retentate comprises active component and solvent. The LFP was dried for 12 hours at 120°C under vacuum to produce an LFP powder. The LFP powder was transferred to an argon filed glovebox for coin cell assembly. A cathode slurry was prepared by mixing 90 wt% LFP powder with 5 wt% PVDF binder (Arkema), 5 wt% carbon black (Imerys Super P™ Li), and NMP solvent. The slurry was mixed for 30 minutes at 2000 rpm in a Thinky mixer (Intertronics). The slurry was cast on aluminium foil, 50 pm thickness, 99.9% purity (Advent RM), to form a cathode. The cathode was dried for 12 hours at 120°C under vacuum. The resulting cathode thickness was 60 pm and mass was 50.5 mg. The electrode was assembled into a coin cell with a glass microfibre separator (Celgard™), having a thickness of 0.25 pm, a lithium layer having a thickness of 0.38 mm and mass of 16 mg. An electrolyte was applied to the layers of the cell, the electrolyte being 1 M LiPF6 in ethylene carbonate (EC) / ethyl methyl carbonate (EMC) 3:7 wt% with 2 wt% vinylene carbonate (VC). The electrolyte bottle was opened four months prior to cell assembly. Half cell testing will be described. The coin cell comprising a recycled graphite anode was galvanostatically cycled at 0.05 C rate for two cycles followed by 1 C rate for 100 cycles, with a voltage delta, AV, 0.005 - 1.5 V. The coin cell comprising a recycled LFP cathode was galvanostatically cycled at 0.1 C rate for three cycles followed by 1 C rate for 100 cycles, with a AV 2.8 - 4.2 V. The cycling tests were performed inside a temperature controlled atmosphere of 25°C. After 100 galvanostatic charge / discharge cycles, figures 7 and 8 show that the respective recycled material maintains high capacity retention. Figure 7 shows the galvanostatic cyclability of five coin cells containing a recycled graphite electrode. Each cell was cycled at 0.05 C rate for two cycles, then 1 C rate for 100 cycles with a voltage delta 0.005 - 1.5 V. The initial specific capacity of each of the five cells is between 310 and 330 mAh / g. The specific capacity is seen to substantially stabilise above 5 cycles and gradually reduce with a greater number of cycles. It was determined from the cycling data that the cell capacity of recycled graphite was 317 mAh / g ± 4. The cell capacity of the recycled graphite electrode is comparable to a cell containing an electrode made using commercially available pristine graphite. Figure 8 shows the galvanostatic cyclability of five coin cells containing a recycled LFP electrode. Each cell was cycled at 0.1 C rate for three cycles, then 1 C rate for 100 cycles with a voltage delta 2.8 - 4.2 V. The initial specific capacity is between 110 and 155 mAh / g. The specific capacity is seen to substantially stabilise above 5 cycles and gradually reduce with a greater number of cycles. It was determined from the cycling data that the cell capacity of recycled LFP was 120 mAh / g ± 7. The cell capacity of the recycled LFP electrode is comparable to electrodes made with commercially available LFP, showing that the recycled LFP has comparable performance to pristine LFP. Example 5 Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES) was performed on samples of active material separated according to the method of the first aspect. A sample of LFP active material was tested. The percentage purity of LFP detected by ICP-OES was 99.58 wt%. The percentage impurity was 0.42 wt%. ICP-OES was performed on a second sample of active material separated according to the method of the first aspect. The second sample was determined to have a purity of 99.99 wt% graphite. Within this specification, the term "about" means plus or minus 20%, more preferably plus or minus 10%, even more preferably plus or minus 5%, most preferably plus or minus 2%. Within this specification, the term "comprises" encompasses the terms "consists essentially of' and “consists of.” Thus, the term "comprising" encompasses "including" as well as “consisting essentially of” and "consisting of'. Within this specification, the term "substantially" means a deviation of plus or minus 20%, more preferably plus or minus 10%, even more preferably plus or minus 5%, most preferably plus or minus 2%. Substantially insoluble, preferably means a solubility of less than about 0.1 g per 100 mL of solvent at 25 °C, preferably less than about 0.01 g per 100 mL of solvent at 25 °C, preferably less than about 0.001 g per 100 mL of solvent at 25 °C. Substantially soluble, preferably means a solubility of more than about 0.1 g per 100 mL of solvent at 25 °C, preferably more than about 1 g per 100 mL of solvent at 25 °C, preferably more than about 10 g per 100 mL of solvent at 25 °C. Within this specification, reference to “substantially” includes reference to “completely” and / or “exactly.” That is, where the word substantially is included, it will be appreciated that this also includes reference to the particular sentence without the word substantially. It should be understood that various changes and modifications to the presently preferred embodiments described herein will be apparent to those skilled in the art. Such changes and modifications can be made without departing from the spirit and scope of the present invention and without diminishing its attendant advantages. It is therefore intended that such changes and modifications are covered by the appended claims. In this disclosure, when the subject of a phase is described as being "configured to" or “arranged to”, followed by a term defining a condition or function, this is used to indicate that the subject of the phrase is in a state in which it has that condition, or is able to perform that function, without the subject being modified or further configured. Some implementations may be described using the expressions “one / an embodiment” or “one / an example,” along with their derivatives. These terms mean that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment. Moreover, unless otherwise noted the features described above are recognized to be usable together in any combination. Thus, any features discussed separately may be employed in combination with each other unless it is noted that the features are incompatible with each other. The foregoing description of example embodiments has been presented for the purposes of illustration and description. It is not intended to be exhaustive or to limit the present disclosure to the precise forms disclosed. Many modifications and variations are possible in light of this disclosure. It is intended that the scope of the present disclosure be limited not by this detailed description, but rather by the claims appended hereto. Future filed applications claiming priority to this application may claim the disclosed subject matter in a different manner and may generally include any set of one or more limitations as variously disclosed or otherwise demonstrated herein. Within this specification embodiments have been described in a way which enables a clear and concise specification to be written, but it is intended and will be appreciated that embodiments may be variously combined or separated without parting from the invention. For example, it will be appreciated that all preferred features described herein are applicable to all aspects of the invention described herein and vice versa. Disclosed herein are the following clauses: 1. A method of separating an electrode active material for recycling comprising: a) providing an electrode active material, wherein the electrode active material comprises carbon black and an active component; b) mixing the electrode active material with a solvent to form a feed stream; c) filtering the feed stream in a first filtration system to produce a permeate and a retentate, wherein the first filtration system comprises a first filter unit, wherein the permeate comprises carbon black and solvent, and wherein the retentate comprises active component and solvent. 2. A method according to clause 1, wherein the retentate and / or the permeate are fluid. 3. A method according to clause 1 or clause 2, wherein the retentate comprises a first portion of the solvent and the permeate comprises a second portion of the solvent. 4. A method according to any preceding clause, wherein the first filtration system comprises a continuous flow filtration system. 5. A method according to any preceding clause, wherein the first filtration system comprises a tangential flow filtration system. 6. A method according to any preceding clause, wherein the first filtration system comprises a cross-flow filtration system. 7. A method according to any preceding clause, wherein the first filter unit comprises a flow path and a filter, wherein the filter extends along the flow path, wherein the feed stream enters the flow path and is filtered to produce the retentate which follows the flow path and the permeate which passes through the filter. 8. A method according to clause 7, wherein the first filter unit is substantially cylindrical, preferably wherein the first filter unit comprises a bore through a filter, wherein the flow path is along the bore and wherein the permeate passes through the filter, preferably wherein the first filter unit comprises a cylindrical filter. 9. A method according to any preceding clause, wherein a further solvent is added to the feed stream, preferably wherein the further solvent comprises the same solvent as the solvent of step (b). 10. A method according to any preceding clause, wherein step (c) further comprises recirculating the retentate through the first filtration system. 11. A method according to any preceding clause, wherein the retentate from step (c) is filtered through a further filtration system, preferably step (c) further comprises recirculating the retentate through the further filtration system. 12. A method according to any preceding clause, comprising analysing the amount of carbon black present in the retentate and if the retentate comprises more than a predetermined level of carbon black, recirculating the retentate through the first filtration system and / or filtering the retentate through a further filtration system, preferably wherein the predetermined level of carbon black is less than about 1 wt% of the carbon black on a dry weight basis, preferably less than about 0.1 wt% of the carbon black on a dry weight basis, preferably less than about 0.01 wt% of the carbon black on a dry weight basis, preferably substantially no carbon black. 13. A method according to any preceding clause, wherein the first filtration system comprises a microfilter, preferably wherein the microfilter has a pore size of less than about 10 pm, preferably less than about 5 pm, preferably less than about 1 pm, preferably less than about 0.5 pm, preferably in the range of about 0.1 pm to about 5 pm, preferably in the range of about 0.5 pm to about 2 pm. 14. A method according to any of clauses 1 to 12, wherein the first filtration system comprises an ultrafilter, preferably wherein the ultrafilter has a pore size of less than 0.1 pm, preferably less than 0.05 pm, preferably in the range of about 0.01 pm to about 0.05 pm. 15. A method according to clause 13 or clause 14, wherein the first filtration system comprises a microfilter and a further filtration system comprises an ultrafilter. 16. A method according to any preceding clause, wherein the retentate comprises less than about 1 wt% of the carbon black on a dry weight basis, preferably less than about 0.1 wt% of the carbon black on a dry weight basis, preferably less than about 0.01 wt% of the carbon black on a dry weight basis, preferably substantially no carbon black. 17. A method according to any preceding clause, wherein the permeate comprises less than about 1 wt% of the active component on a dry weight basis, preferably less than about 0.1 wt% of the active component on a dry weight basis, preferably less than about 0.01 wt% of the active component on a dry weight basis, preferably substantially no active component. 18. A method according to any preceding clause, further comprising d. drying the retentate to form a dried retentate, wherein the dried retentate comprises the active component, preferably wherein the dried retentate comprises less than about 1 wt% of the carbon black on a dry weight basis, preferably less than about 0.1 wt% of the carbon black on a dry weight basis, preferably less than about 0.01 of the wt% carbon black on a dry weight basis, preferably substantially no carbon black; and / or e. drying the permeate to form a dried permeate, wherein the dried permeate comprises the carbon black, preferably wherein the dried permeate comprises less than about 1 wt% of the active component on a dry weight basis, preferably less than about 0.1 wt% of the active component on a dry weight basis, preferably less than about 0.01 wt% of the active component on a dry weight basis, preferably substantially no active component. 19. A method according to any preceding clause, wherein the electrode active material further comprises a binder, preferably wherein the permeate further comprises binder. 20. A method according to clause 19, wherein the electrode active material comprises about 0.5 wt% to about 5 wt% carbon black, about 85 wt% to about 95 wt% active component and about 0.1 wt% to about 5 wt% binder, on a dry weight basis. 21. A method according to clause 19 or clause 20, wherein the binder comprises carboxymethyl cellulose (CMC), styrene-butadiene rubber (SBR), polyacrylic acid (PAA), polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), or a combination of two or more thereof, preferably styrene-butadiene rubber I carboxymethyl cellulose (SBR / CMC), PVDF or a combination of two or more thereof. 22. A method according to any of clauses 19 to 21, further comprising filtering the permeate by a permeate ultrafiltration system to produce an ultrafiltration retentate and an ultrafiltration permeate, wherein the ultrafiltration retentate comprises carbon black and solvent and wherein the ultrafiltration permeate comprises binder and solvent. 23. A method according to clause 22, further comprising drying the ultrafiltration retentate, wherein the dried ultrafiltration retentate comprises carbon black, preferably wherein the dried ultrafiltration permeate comprises less than about 1 wt% of the binder on a dry weight basis, preferably less than about 0.1 wt% of the binder on a dry weight basis, preferably less than about 0.01 wt% of the binder on a dry weight basis, preferably substantially no binder. 24. A method according to clause 22 or clause 23, further comprising drying the ultrafiltration permeate, wherein the dried ultrafiltration permeate comprises binder, preferably wherein the dried ultrafiltration permeate comprises less than about 1 wt% of the carbon black on a dry weight basis, preferably less than about 0.1 wt% of the carbon black on a dry weight basis, preferably less than about 0.01 wt% of the carbon black on a dry weight basis, preferably substantially no carbon black. 25. A method according to clause 22 or clause 23, comprising using reverse osmosis to remove binder from the ultrafiltration permeate. 26. A method according to any of clauses 19 to 25, wherein the electrode active material comprises the active component, the carbon black and the binder, wherein the method comprises separating the active component, the carbon black and the binder, preferably the method comprises separating the active component, the carbon black, the binder and at least part of the solvent. 27. A method according to any preceding clause, wherein the active component comprises a cathode active component and / or an anode active component. 28. A method according to clause 22, wherein the anode active component comprises graphite, niobium oxide, titanium niobium oxide, lithium titanium oxide, graphene, sodium titanium oxide, sodium titanium phosphate oxide, sodium titanium phosphate, sodium metatitanate powder, hard carbon, silicon or a combination of two or more thereof; preferably graphite and / or wherein the cathode active component comprises lithium iron phosphate (LFP), lithium manganese iron phosphate (LMFP), nickel manganese cobalt (NMC), lithium nickel cobalt aluminium oxide (NCA), lithium cobalt oxide (LCO), lithium manganese oxide (LMO), lithium manganese nickel oxide (LMNO), lithium nickel oxide (LNO), sodium chromium oxide, sodium cobalt oxide, sodium manganese oxide, sodium cobalt phosphate, sodium nickel phosphate, sodium iron phosphate, sodium manganese phosphate, sodium iron hexacyanoferrate, sodium manganese hexacyanoferrate, sodium vanadium phosphate, sulphur, or a combination of two or more thereof, preferably NMC, LFP or a combination thereof. 29. A method according to any preceding clause, wherein the carbon black is particulate, preferably wherein the carbon black has an D50 particle size of less than about 200 nm, preferably about 5 nm to about 200 nm. 30. A method according to any preceding clause, wherein the solvent comprises at least one of water, methyl ethyl ketone (MEK), N-Methyl-2-pyrrolidone (NMP), tetrahydrofuran (THF), chloroform, xylene, toluene, N,N-dimethylformamide (DMF), Dimethylsulfoxide (DMSO), Dimethylacetamide (DMAc) or acetone, or a combination of two or more thereof, preferably water and / or NMP, preferably water. 31. A method according to any preceding clause, wherein the liquid to solid ratio in the feed stream is at least about 2:1, preferably about 2:1 to about 50:1, preferably about 5:1 to about 20:1. 32. A method according to any preceding clause, wherein the active component comprises graphite or LFP, the binder comprises styrene butadiene rubber (SBR) and / or carboxymethyl cellulose (CMC), and the solvent comprises water. 33. A method according to any preceding clause, wherein the active component comprises NMC, the binder comprises PVDF, and the solvent comprises N-methylpyrrolidone (NMP). 34. A method according to any preceding clause, wherein the active component is particulate, preferably wherein the active component has an D90 particle size in the range of about 1 pm to about 50 pm. 35. A method according to any preceding clause, wherein the electrode active material comprises an electrode active material slurry, preferably an uncured electrode active material slurry. 36. A method according to any preceding clause, wherein the electrode active material comprises a cured electrode active material, preferably a solid cured electrode active material. 37. A method according to any preceding clause, wherein the temperature of the mixture in step (b) and step (c) is each independently in the range of about 10 °C to about 80 °C, preferably about 20 °C to about 60 °C, preferably about 20 °C to about 40 °C, preferably about 20°C to about 25 °C, preferably about room temperature. 38. A method according to any preceding clause, wherein the weight ratio of the active component to the carbon black in the electrode active material is in the range of about 20:1 to about 120:1, preferably in the range of about 25:1 to about 100:1. 39. A method according to any preceding clause, wherein the permeate is heated to a temperature of at least about 300 °C to produce a heat treated permeate, preferably in the range of about 350 °C to about 490°C, wherein in the heat treated permeate preferably comprises at least 90 wt% carbon black, preferably at least 95 wt% carbon black, preferably at least 99 wt% carbon black, preferably substantially all carbon black; and / or wherein the ultrafiltration retentate is heated to a temperature of at least about 300 °C to produce a heat treated ultrafiltration retentate, preferably in the range of about 350 °C to about 490°C, wherein in the heat treated ultrafiltration retentate preferably comprises at least 90 wt% carbon black, preferably at least 95 wt% carbon black, preferably at least 99 wt% carbon black, preferably substantially all carbon black. 40. A method according to any preceding clause, further comprising deagglomerating the electrode active material, preferably prior to step (a) and / or after step (b), preferably wherein deagglomerating the electrode active material comprises using ultrasound, high shear mixing, heating, adding a surfactant or a combination of two or more thereof. 41. A method of filtering an electrode active material, wherein the electrode active material comprises carbon black and an active component, the method comprising: a) providing an electrode active material, wherein the electrode active material comprises carbon black and an active component; b) mixing the electrode active material with a solvent to form a feed stream; c) filtering the feed stream in a first filtration system to produce a permeate and a retentate, wherein the first filtration system comprises a first filter unit, wherein the permeate comprises carbon black and solvent, and wherein the retentate comprises active component and solvent. 42. Use of a filter to separate carbon black from an electrode active material, wherein the electrode active material comprises carbon black and an active component, the method comprising: a) providing an electrode active material, wherein the electrode active material comprises carbon black and an active component; b) mixing the electrode active material with a solvent to form a feed stream; c) filtering the feed stream in a first filtration system to produce a permeate and a retentate, wherein the first filtration system comprises a first filter unit, wherein the permeate comprises carbon black and solvent, and wherein the retentate comprises active component and solvent. 43. Use according to clause 42, wherein the electrode active material further comprises binder and wherein a permeate ultrafiltration system is used to separate the binder from the electrode active material. 44. An apparatus for use in a method according to any preceding clause, comprising a tangential flow filtration system and / or a cross-flow filtration system. 45. An apparatus according to clause 44, wherein the apparatus comprises a first container for an electrode active material, and a second container for a solvent, wherein the first container and second container are in fluid communication with a third container for mixing the electrode active material and the solvent to form a feed stream, wherein the third container is in fluid communication with a first filtration system for filtering the feed stream, wherein the first filtration system comprises a loop through a first filter unit, wherein the first filter unit is in fluid communication with: A. a fourth container for receiving a permeate from the first filter unit, B. a fifth container for receiving a retentate from the first filter unit, and C. a recirculation loop for directing the retentate back into the first filter unit. 46. A method of producing an electrode for a cell, the method comprising: i) providing an active component produced according to any of clauses 1 to 40; ii) mixing the active material with a second binder and a second solvent to form a slurry; iii) coating a metal layer with the slurry to form a coated metal; iv) drying the coated metal to form an electrode. 47. The method according to clause 46, further comprising providing carbon black produced according to any of clauses 1 to 40, wherein step ii) comprises mixing the active material with the carbon black, a second binder and a second solvent to form a slurry. 48. A method of producing an electrode for a cell, the method comprising: i) providing an active component and providing carbon black, wherein the carbon black is produced according to any of clause 1 to 40; ii) mixing the active material with carbon black, a second binder and a second solvent to form a slurry; iii) coating a metal layer with the slurry to form a coated metal; iv) drying the coated metal to form an electrode. 49. The method according to any of clauses 36 to 48, wherein the second binder comprises binder produced according to any of clauses 19 to 40. 50. A method of producing an electrode for a cell, the method comprising: i) providing an active component and providing carbon black; ii) mixing the active material with carbon black, a second binder and a second solvent to form a slurry, wherein the binder is produced according to any of clauses 19 to 40; iii) coating a metal layer with the slurry to form a coated metal; iv) drying the coated metal to form an electrode. 51. The method of any of clauses 46 to 50, wherein step iv) comprises curing the binder. 52. The method of any of clauses 46 to 51, wherein the active component comprises graphite, wherein the second binder comprises CMC and / or SBR, and wherein the metal layer comprises copper. 53. The method of any of clauses 46 to 51, wherein the active component comprises NMC, wherein the second binder comprises PVDF, and wherein the metal layer comprises aluminium; and / or wherein the active component comprises LFP, wherein the second binder comprises CMC and / or SBR, and wherein the metal layer comprises aluminium. 54. An electrode produced by the method of any of clauses 46 to 53. 55. A method of producing a cell comprising assembling the electrode produced by the method according to any of clauses 46 to 53, or an electrode according to clause 54 into a cell. 56. A cell produced by the method of clause 55. 57. A method according to any of clauses 41, 45-53 or 55, an apparatus according to clause 44 or clause 45, a use according to clause 42 or clause 43, an electrode according to clause 54 or a cell according to clause 56, further comprising the feature of any of clauses 1 to 40. 58. An active component obtainable by the method of any of clauses 1 to 41. 59. The active component of clause 58, wherein the active component is an anode active component and / or a cathode active component. 60. The active component of clause 59, wherein the anode active component is graphite and / or the cathode active component is lithium iron phosphate (LFP). 61. Graphite obtainable by the method of any of clauses 1 to 41. 62. Graphite obtained by the method of any of clauses 1 to 41. 63. Lithium iron phosphate obtainable by the method of any of clauses 1 to 41. 64. Lithium iron phosphate obtained by the method of any of clauses 1 to 41.

Claims

1. A method of separating an electrode active material for recycling comprising:a) providing an electrode active material, wherein the electrode active material comprises carbon black and an active component;b) mixing the electrode active material with a solvent to form a feed stream;c) filtering the feed stream in a first filtration system to produce a permeate and a retentate, wherein the first filtration system comprises a first filter unit, wherein the permeate comprises carbon black and solvent, and wherein the retentate comprises active component and solvent.

2. A method according to any preceding claim, wherein the first filtration system comprises a continuous flow filtration system; and / orwherein the first filtration system comprises a tangential flow filtration system; and / orwherein the first filtration system comprises a cross-flow filtration system.

3. A method according to any preceding claim, wherein the first filter unit comprises a flow path and a filter, wherein the filter extends along the flow path,wherein the feed stream enters the flow path and is filtered to produce the retentate which follows the flow path and the permeate which passes through the filter; preferably wherein the first filter unit is substantially cylindrical, preferably wherein the first filter unit comprises a bore through a filter, wherein the flow path is along the bore and wherein the permeate passes through the filter, preferably wherein the first filter unit comprises a cylindrical filter.

4. A method according to any preceding claim, wherein a further solvent is added to the feed stream, preferably wherein the further solvent comprises the same solvent as the solvent of step (b).

5. A method according to any preceding claim, wherein step (c) further comprises recirculating the retentate through the first filtration system; and / orwherein the retentate from step (c) is filtered through a further filtration system, preferably step (c) further comprises recirculating the retentate through the further filtration system.

6. A method according to any preceding claim, wherein the first filtration system comprises a microfilter, preferably wherein the microfilter has a pore size of less than about 10 pm, preferably less than about 5 pm, preferably less than about 1 pm,preferably less than about 0.5 pm, preferably in the range of about 0.1 pm to about 5 pm, preferably in the range of about 0.5 pm to about 2 pm; orwherein the first filtration system comprises an ultrafilter, preferably wherein the ultrafilter has a pore size of less than 0.1 pm, preferably less than 0.05 pm, preferably in the range of about 0.01 pm to about 0.05 pm.

7. A method according to any preceding claim, further comprisingd) drying the retentate to form a dried retentate, wherein the dried retentate comprises the active component, preferably wherein the dried retentate comprises less than about 1 wt% of the carbon black on a dry weight basis, preferably less than about 0.1 wt% of the carbon black on a dry weight basis, preferably less than about 0.01 of the wt% carbon black on a dry weight basis, preferably substantially no carbon black; and / ore) drying the permeate to form a dried permeate, wherein the dried permeate comprises the carbon black, preferably wherein the dried permeate comprises less than about 1 wt% of the active component on a dry weight basis, preferably less than about 0.1 wt% of the active component on a dry weight basis, preferably less than about 0.01 wt% of the active component on a dry weight basis, preferably substantially no active component.

8. A method according to any preceding claim, wherein the electrode active material further comprises a binder, preferably wherein the permeate further comprises binder, preferably wherein the binder comprises carboxymethyl cellulose (CMC), styrenebutadiene rubber (SBR), polyacrylic acid (PAA), polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), or a combination of two or more thereof, preferably styrene-butadiene rubber I carboxymethyl cellulose (SBR / CMC), PVDF or a combination of two or more thereof.

9. A method according to claim 8, further comprising filtering the permeate by a permeate ultrafiltration system to produce an ultrafiltration retentate and an ultrafiltration permeate, wherein the ultrafiltration retentate comprises carbon black and solvent and wherein the ultrafiltration permeate comprises binder and solvent; preferably further comprising drying the ultrafiltration retentate, wherein the dried ultrafiltration retentate comprises carbon black, preferably wherein the dried ultrafiltration permeate comprises less than about 1 wt% of the binder on a dry weight basis, preferably less than about 0.1 wt% of the binder on a dry weight basis, preferably less than about 0.01 wt% of the binder on a dry weight basis, preferably substantially no binder; and / orfurther comprising drying the ultrafiltration permeate, wherein the dried ultrafiltration permeate comprises binder, preferably wherein the dried ultrafiltration permeate comprises less than about 1 wt% of the carbon black on a dry weight basis, preferably less than about 0.1 wt% of the carbon black on a dry weight basis, preferably less than about 0.01 wt% of the carbon black on a dry weight basis, preferably substantially no carbon black; and / orusing reverse osmosis to remove binder from the ultrafiltration permeate.

10. A method according to any preceding claim, wherein the active component comprises a cathode active component and / or an anode active component;preferably wherein the anode active component comprises graphite, niobium oxide, titanium niobium oxide, lithium titanium oxide, graphene, sodium titanium oxide, sodium titanium phosphate oxide, sodium titanium phosphate, sodium metatitanate powder, hard carbon, silicon or a combination of two or more thereof; preferably graphite; and / orwherein the cathode active component comprises lithium iron phosphate (LFP), lithium manganese iron phosphate (LMFP), nickel manganese cobalt (NMC), lithium nickel cobalt aluminium oxide (NCA), lithium cobalt oxide (LCO), lithium manganese oxide (LMO), lithium manganese nickel oxide (LMNO), lithium nickel oxide (LNO), sodium chromium oxide, sodium cobalt oxide, sodium manganese oxide, sodium cobalt phosphate, sodium nickel phosphate, sodium iron phosphate, sodium manganese phosphate, sodium iron hexacyanoferrate, sodium manganese hexacyanoferrate, sodium vanadium phosphate, sulphur, or a combination of two or more thereof, preferably NMC, LFP or a combination thereof.

11. A method according to any preceding claim, wherein the carbon black is particulate, preferably wherein the carbon black has an D50 particle size of less than about 200 nm, preferably about 5 nm to about 200 nm.

12. A method according to any preceding claim, wherein the solvent comprises at least one of water, methyl ethyl ketone (MEK), N-Methyl-2-pyrrolidone (NMP), tetrahydrofuran (THF), chloroform, xylene, toluene, N,N-dimethylformamide (DMF), Dimethylsulfoxide (DMSO), Dimethylacetamide (DMAc) or acetone, or a combination of two or more thereof, preferably water and / or NMP, preferably water; and / orwherein the liquid to solid ratio in the feed stream is at least about 2:1, preferably about 2:1 to about 50:1, preferably about 5:1 to about 20:1.

13. A method according to any preceding claim, wherein the active component comprises graphite or LFP, the binder comprises styrene butadiene rubber (SBR) and / or carboxymethyl cellulose (CMC), and the solvent comprises water; orwherein the active component comprises NMC, the binder comprises PVDF, and the solvent comprises N-methylpyrrolidone (NMP).

14. A method according to any preceding claim, wherein the active component is particulate, preferably wherein the active component has an D90 particle size in the range of about 1 pm to about 50 pm.

15. A method of filtering an electrode active material, wherein the electrode active material comprises carbon black and an active component, the method comprising:a) providing an electrode active material, wherein the electrode active material comprises carbon black and an active component;b) mixing the electrode active material with a solvent to form a feed stream;c) filtering the feed stream in a first filtration system to produce a permeate and a retentate, wherein the first filtration system comprises a first filter unit, wherein the permeate comprises carbon black and solvent, and wherein the retentate comprises active component and solvent.

16. Use of a filter to separate carbon black from an electrode active material, wherein the electrode active material comprises carbon black and an active component, the method comprising:a) providing an electrode active material, wherein the electrode active material comprises carbon black and an active component;b) mixing the electrode active material with a solvent to form a feed stream;c) filtering the feed stream in a first filtration system to produce a permeate and a retentate, wherein the first filtration system comprises a first filter unit, wherein the permeate comprises carbon black and solvent, and wherein the retentate comprises active component and solvent.

17. An apparatus for use in a method according to any preceding claim, comprising a tangential flow filtration system and / or a cross-flow filtration system.

18. An apparatus according to claim 17, wherein the apparatus comprises a first container for an electrode active material, and a second container for a solvent, wherein the first container and second container are in fluid communication with a third container for mixing the electrode active material and the solvent to form a feed stream, wherein the third container is in fluid communication with a first filtration system for filtering the feedstream, wherein the first filtration system comprises a loop through a first filter unit, wherein the first filter unit is in fluid communication with:A. a fourth container for receiving a permeate from the first filter unit,B. a fifth container for receiving a retentate from the first filter unit, andC. a recirculation loop for directing the retentate back into the first filter unit.

19. A method of producing an electrode for a cell, the method comprising:i) providing an active component produced according to any of claims 1 to 14;ii) mixing the active material with a second binder and a second solvent to form a slurry;iii) coating a metal layer with the slurry to form a coated metal;iv) drying the coated metal to form an electrode, and optionallyfurther comprising providing carbon black produced according to any of claims 1 to 14, wherein step ii) comprises mixing the active material with the carbon black, a second binder and a second solvent to form a slurry.

20. A method of producing an electrode for a cell, the method comprising:i) providing an active component and providing carbon black, wherein the carbon black is produced according to any of claims 1 to 14;ii) mixing the active material with carbon black, a second binder and a second solvent to form a slurry;iii) coating a metal layer with the slurry to form a coated metal;iv) drying the coated metal to form an electrode.

21. A method of producing an electrode for a cell, the method comprising:i) providing an active component and providing carbon black;ii) mixing the active material with carbon black, a second binder and a second solvent to form a slurry, wherein the binder is produced according to any of claims 8 to 14;iii) coating a metal layer with the slurry to form a coated metal;iv) drying the coated metal to form an electrode.

22. The method of any of claims 19 to 21, wherein the active component comprises graphite, wherein the second binder comprises CMC and / or SBR, and wherein the metal layer comprises copper; orwherein the active component comprises NMC, wherein the second binder comprises PVDF, and wherein the metal layer comprises aluminium; and / or wherein the active component comprises LFP, wherein the second binder comprises CMC and / or SBR, and wherein the metal layer comprises aluminium.

23. An electrode produced by the method of any of claims 19 to 22.

24. A method of producing a cell comprising assembling the electrode produced by the method according to any of claims 19 to 22, or an electrode according to claim 23 into a cell.

25. An active component obtainable by the method of any of claims 1 to 15.T +44(0)30 0300 2000A

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