Field of the Invention

The present invention relates in general to lithium-based electrochemical cells, and in particular to a method of recycling a lithium-based electrochemical cell so as to recover useable products therefrom.

Background of the Invention

The rapid development of personal electronic devices, hybrid and electric vehicles has seen a correspondingly rapid development in battery technology. Perhaps the most widely used battery in such applications are lithium-based electrochemical cells, or as they are more commonly known lithium ion (Li-ion) batteries.

Use of Li-ion batteries is now at an all-time high and it is expected to increase dramatically over the coming years.

However, unlike conventional lead-acid batteries that are effectively and efficiently recycled, Li-ion batteries are not currently widely recycled.

Li-ion batteries are typically made up of an outer casing material, a positive electrode, a negative electrode, electrolyte and a separator.

The outer case may be made of metal such as aluminium or an engineering plastic such as high impact polystyrene.

The negative electrode may comprise carbon, often in the form of graphite or graphene. It may also comprise polymer binder or metal oxide material. The negative electrode may be coated with a metal foil, such as copper foil. The positive electrode may comprise metal oxide materials. It may also comprise polymer binder. The positive electrode may be coated with a metal foil, such as aluminium foil.

The electrolyte typically comprises a mixture of organic carbonates and non-coordinating anion salts such as lithium hexafluorophosphate (LiPF ₆ ), lithium hexafluoroarsenate monohydrate (LiAsF ₆ ), lithium perchlorate (LiCL0 ₄ ), lithium tetrafluorob orate (LiBF ₄ ), and lithium triflate (LiCFiSO,).

The separator is commonly a thin micro-perforated plastic sheet, for example made of polyethylene or polypropylene, which separates the two electrodes and allows ions to pass through.

There is an extremely diverse array of components used in manufacturing Li-ion batteries. The use of different components in such batteries are often characterised by use of acronyms such as:

NCA Li-ion battery for lithium nickel cobalt aluminium oxide (LiNiCoAl0 ₂ )

LCO Li-ion battery for lithium cobalt oxide (LiCo0 ₂ )

NMC Li-ion battery for lithium nickel manganese cobalt (Li[NiMnCo]0 ₂ )

LMO Li-ion battery for lithium manganese oxide (LiMn ₂ 0 ₄ )

LFP Li-ion battery for lithium iron phosphate (LiFeP0 ₄ )

LNO Li-ion battery for lithium nickel oxide (LiNi0 ₂ )

LTO Li-ion battery for lithium titanium oxide (Li ₄ Ti ₅ 0i ₂ )

The sheer complexity and diverse variety of components present in Li-ion batteries has to date presented many challenges in developing an effective and efficient recycling process.

Li-ion batteries typically contain valuable materials such as lithium salts, high-grade metals such as copper and aluminium and transition metals such as cobalt and nickel as well as rare earth metals. Discarded Li-ion batteries therefore represent a potential valuable resource of such materials.

To date, only a very low proportion of discarded Li-ion batteries are recycled, and that recycling often involves manual disassembly of the battery. Manual disassembly of Li-ion batteries adds considerable cost to the process and also exposes workers to potentially hazardous materials contained within the batteries. Accordingly, most discarded Li-ion batteries are currently being disposed of in landfill or stockpiled.

An opportunity therefore remains to develop methodology for effectively and efficiently recycling lithium-based electrochemical cells to address or ameliorate one or more of the disadvantages or shortcomings associated with existing protocol for dealing with the discarded cells.

Summary of the Invention

The present invention therefore provides a method of recycling a lithium-based electrochemical cell, the method comprising:

- comminuting the cell under (i) an inert atmosphere, (ii) reduced pressure, or (iii) a combination thereof, to produce comminuted product;

- separating from the comminuted product (i) magnetic metal, (ii) non-magnetic metal, or (iii) a combination thereof;

- subj ecting the comminuted product to an aqueous extraction process to separate from it aqueous soluble material;

- introducing the metal separated and aqueous extracted comminuted product into a vessel and heating it under an inert atmosphere to (i) liberate volatile organic compounds, and (ii) leave behind non-volatile residue comprising metal salt; and - isolating one or more of the separated metal, the aqueous soluble material, the liberated volatile organic compounds and the non-volatile residue for subsequent use.

By the method of the invention, not only can discarded lithium-based electrochemical cells be disposed of in an efficient and effective manner, but in doing so many valuable components of the cells can be isolated for reuse. The method is readily automated enabling it to be performed with little or no human intervention.

In particular, magnetic and non-magnetic metal components of the cells can be collected, the aqueous extraction process facilitates separation of aqueous soluble material such as aqueous soluble lithium compounds, and the heating step (i) converts plastic/polymer and other organic components of the cell into volatile organic compounds that can be collected and used as a fuel oil, and (ii) provides non-volatile residue comprising valuable metal salt such as lithium, cobalt and nickel salts that can be extracted and reused.

Surprisingly, the combination of steps used in accordance with the method of the invention advantageously enables a high recovery of valuable components contained within lithium- based electrochemical cells. Furthermore, the method can be readily scaled and it is believed to represent an economical viable means for recycling high volumes of discarded lithium- based electrochemical cells.

Without wishing to be limited by theory, it is believed the unique combination of steps performed in the method of the invention synergistically enables a high recovery of valuable components contained within lithium-based electrochemical cells. In particular, comminuting the cell facilitates exposing its components to enhance efficiency of the subsequent steps. Separating from the comminuted product magnetic and non-magnetic metal improves the efficiency of the subsequent heating step. Subj ecting the comminuted product to the aqueous extraction process simplifies isolating valuable electrolyte components of the cell. The heating step itself enables plastic/polymer and other organic components of the cell to be converted into valuable fuel oil. The heating step is also believed to suitably degrade positive and/or negative cathode materials (which can contain polymer binder) to enable valuable metal salts to be leached from the non-volatile residue using, for example acid leaching.

Collectively, the steps in the method of the invention are believed to provide for an unprecedented high recovery of valuable components in lithium-based electrochemical cells.

In one embodiment, before the cell is comminuted it is subjected to a discharge step which depletes any charge remaining in the cell.

In another embodiment, the discharge step comprises submerging the cell in a sodium chloride solution, for example an aqueous solution comprising about l00-200g/l of sodium chloride.

In further embodiment, comminuting the cell produces comminuted product that will pass through a screen mesh having 30mm openings, or 28mm openings, or 26mm openings, or 24mm openings, or 22mm openings, or 20mm openings, or l8mm openings, or l6mm openings, or l4mm openings, or l2mm openings, or lOmm openings.

In another embodiment, magnetic metal is separated from the comminuted product using a magnet, such as a rare-earth magnet.

In a further embodiment, non-magnetic metal is separated from the comminuted product using an eddy current separator.

In another embodiment, magnetic and non-magnetic metal is separated from the comminuted product using an eddy current separator.

The magnetic metal may include steel. The non-magnetic metal may include copper and aluminium.

In one embodiment, the aqueous extraction process comprises submerging the comminuted product in an aqueous liquid having a temperature of at least 40°C, or at least 60°C, or at least 70°C, or at least 80°C, or at least 90°C, or at least 95°C. In another embodiment, the aqueous extraction process comprises subjecting the comminuted product to steam, for example steam stripping. In a further embodiment, the aqueous soluble material comprises aqueous soluble metal salt such as aqueous soluble lithium salt.

In another embodiment, the metal separated and aqueous extracted comminuted product are heated in the vessel to a temperature ranging from about 350°C to 600°C, or from about 350°C to about 500°C, or from about 400°C to about 500°C, or from about 400°C to about 450°C.

In one embodiment, the liberated volatile organic compounds are collected using a condenser.

In a further embodiment, the non-volatile residue is isolated from the vessel and subjected to acid leaching to produce metal salt that is soluble in the acid leachate.

In yet a further embodiment the metal salt soluble in the acid leachate comprises one or more of a cobalt, lithium, or nickel metal salt. In another embodiment, the metal separated and aqueous extracted comminuted product is heated in the vessel using far infrared radiation (FIR).

Further aspects and embodiments of the invention are discussed in more detail below. Detailed Description of the Invention

The present invention relates to a method of recycling a lithium -based electrochemical cell. By the expression“lithium-based electrochemical cell” is intended to mean a cell or battery that may or may not be rechargeable in which lithium ions are transferred between negative and positive electrodes during discharge or recharge. Such cells are more commonly referred to as a lithium-ion battery or a Li-ion battery. For convenience, the expression“lithium -based electrochemical cell” may herein be referred to as a“lithium-ion battery” or“Li-ion battery”.

By“recycling” a Li-ion battery is meant that one or more components that make up the battery are isolated from the battery for subsequent use.

The method according to the invention comprises comminuting the Li-ion battery.

By“comminuting” is meant the Li-ion battery is broken down into smaller parts. The comminuting will generally be achieved by subjecting the Li-ion battery to a mechanical process which breaks it down into smaller parts. Comminution may be achieved using techniques known in the art such as crushing, milling and shredding.

The aim of comminuting the Li-ion battery is to expose its inner components to facilitate their separation from each other during the steps according to the method of the invention.

Provided the inner components of the Li-ion battery are exposed during comminuting, there is no particular limitation concerning the size of the resulting comminuted product. Generally, comminuting produces comminuted product of a size that will pass through a screen mesh having 30mm openings, or 28mm openings, or 26mm openings, or 24mm openings, or 22mm openings, or 20mm openings, or l8mm openings, or l6mm openings, or l4mm openings, or l2mm openings, or lOmm openings.

As those skilled in the art will appreciate, comminuting a Li-ion battery, in particular a Li-ion battery still containing charge, can result in the generation of heat and potentially fire as a result of chemical reactions occurring between components that make up the Li-ion battery.

To minimise or prevent undesirable overheating or fire, comminuting the cell is performed under an inert atmosphere, reduced pressure, or a combination thereof.

By an“inert atmosphere” is meant an atmosphere that does not support combustion. An inert atmosphere can be readily achieved by comminuting the cell under an inert gas. Suitable inert gases include, but are not limited to, nitrogen and argon.

Comminuting the cell may also be conducted under reduced pressure. By“reduced pressure” is intended to mean a pressure lower than atmospheric pressure. Reduced pressure may be achieved using techniques well known in the art, for example application of a vacuum pump.

Reducing the pressure at the site of comminuting the cell can remove flammable gases such as hydrogen that may be produced from chemical reactions of components within the cell. Removing such flammable gases can minimise or prevent a fire.

Comminuting the cell may also be conducted under a combination of an inert atmosphere and reduced pressure. In that case, an inert gas may be fed into the comminuting site of at the same time the site is subjected to reduce pressure.

In one embodiment, the inert atmosphere is provided by an inert gas. The inert gas may be selected from nitrogen, argon and a combination thereof.

In a further embodiment, the reduced pressure is provided by application of a vacuum pump.

If required, the equipment used in comminuting the cell may be cooled to below room temperature to minimise or prevent heat build up generated by chemical reactions between components within the cell. For example, a chilled liquid may be passed through internal components of equipment used to comminute the cell.

To minimise or prevent generation of heat and potentially fire when the cell is comminuted, before comminuting the cell it may be desirable to subject the cell to a discharge step which depletes any charge remaining in the cell. Removing charge from the cell before comminution can be performed by techniques known in the art.

For example, such a discharge step may comprise submerging the cell in a sodium chloride solution. Such a sodium chloride solution may be an aqueous solution comprising from about l00-200g/l of sodium chloride.

In one embodiment, comminuting the cell is achieved using equipment selected from a crusher, mill, shredder and combinations thereof.

Generally, the method of the invention will involve comminuting a plurality of Li-ion batteries to produce comminuted product.

The Li-ion batteries comminuted may be of the same or different type. In that regard, an advantage of the method according to the present invention is that it can accommodate a diverse range of different types of Li-ion batteries.

Following comminuting the Li-ion battery, the resulting comminuted product is subj ected to a step of separating from it magnetic metal, non-magnetic metal or a combination thereof.

Components of a Li-ion battery will generally include one or both of magnetic metal such as steel and non-magnetic metal such as copper and/or aluminium.

It is desirable to separate such metal components from the comminuted material before the comminuted material is subjected to the heating step in accordance with the method of the invention. In particular, excess metal components can adversely interfere with the efficiency of the heating step.

The method according to the invention therefore aims to reduce or minimise the metal components from the Li-ion battery that are present in the comminuted product during the heating step.

Magnetic metal may be separated from the comminuted product using a magnet such as a rare earth magnet.

In one embodiment, magnetic metal is separated from the comminuted product using a magnet.

Non-magnetic metal may be separated from the comminuted product using an eddy current separator.

Separating both magnetic metal and non-magnetic metal from the comminuted product may also be achieved using an eddy current separator.

In one embodiment, magnetic metal and non-magnetic metal is separated from the comminuted product using an eddy current separator.

The method according to the invention also includes subj ecting the comminuted product to an aqueous extraction process to separate from it aqueous soluble material. The aqueous extraction process may be conducted by any suitable means. For example, the comminuted product may be submerged in an aqueous liquid. To promote separation of aqueous soluble material from the comminuted product the aqueous liquid may be provided at a temperature above room temperature. For example, the aqueous liquid used may have a temperature of at least 40°C, or at least 60°C, or at least 70°C, or at least 80°C, or at least 90°C, or at least 95°C.

The aqueous liquid in the aqueous extraction process may consist essentially of water.

The aqueous extraction process may include subjecting the comminuted product to steam stripping. In that case, conventional steam stripping techniques may be employed. Where steam stripping is used, the steam will interact with the comminuted product and solubilise any aqueous soluble material in the comminuted product, with the steam then condensing to produce an aqueous liquid comprising the aqueous soluble material. The aqueous extraction process separates from the comminuted product aqueous soluble material components of the Li-ion battery. There is no particular limitation concerning the nature of the aqueous soluble material that may be separated from the comminuted product during the aqueous extraction process. The type of aqueous soluble material extracted from the comminuted product will of course depend upon the components used in manufacturing Li-ion battery.

For example, some Li-ion batteries are manufactured using aqueous soluble lithium salts such as lithium hexafluorophosphate (LiPF ₆ ), lithium hexafluoroarsenate monohydrate (LiAsF ₆ ), lithium perchlorate (LiCLCL), lithium tetrafluorob orate (LiBF ₄ ), and lithium triflate (LiCF ₃ S0 ₃ ).

Upon undergoing aqueous extraction, such lithium salts may be extracted in a“preserved” form or they may undergo hydrolysis so as to be converted into one or more different compounds. For example, lithium hexafluorophosphate may undergo hydrolysis during the aqueous extraction step to form compounds such as HF, PF ₅ and LiOH.

For avoidance of any doubt, aqueous soluble material extracted during the aqueous extraction step is intended to include not only aqueous soluble material contained in the comminuted product but also any hydrolysis products derived from that aqueous soluble material.

In one embodiment, the aqueous soluble material comprises one or more lithium salts. Such lithium salts may, for example comprise, LiPF ₆ , LiOH, LIBF4, LiCF ₃ S0 ₃ , LiAsF ₆ , L1CLO4, LiF and combinations thereof.

The aqueous extraction process will provide for an aqueous liquid containing the aqueous soluble material. The aqueous soluble material can be isolated from the aqueous liquid by removing the aqueous liquid, for example by evaporation. Alternatively, the aqueous soluble material may be isolated from the aqueous liquid by introducing into the aqueous liquid one or more compounds that react with the aqueous soluble material to render them insoluble in the aqueous liquid.

For example, where the aqueous liquid comprises one or more aqueous soluble lithium salts, sodium or potassium carbonate may be added to the aqueous liquid to promote precipitation of lithium carbonate (Li ₂ C0 ₃ ). The precipitated lithium carbonate can then be separated from the aqueous liquid, for example by filtration or centrifugation, and collected for subsequent use.

In one embodiment, the aqueous extraction process provides for an aqueous liquid comprising aqueous soluble material, wherein one or more compound is introduced into the aqueous liquid to promote precipitation of the aqueous soluble material from the aqueous liquid.

In a further embodiment, the aqueous extraction process provides for an aqueous liquid comprising aqueous soluble lithium salt, and one or more compounds are introduced into the aqueous liquid to promote precipitation of the lithium salt in the aqueous liquid.

The method according to the invention comprises separating from the comminuted product magnetic and/or non-magnetic metal, and subjecting the comminuted product to an aqueous extraction process. The magnetic and non-magnetic metal separation step may be conducted before or after the aqueous extraction process step.

In one embodiment, separating from the comminuted product magnetic metal, non-magnetic metal, or a combination thereof occurs before subjecting the comminuted product to the aqueous extraction process.

After the aqueous extraction process, the extracted comminuted product may need to be separated from excess aqueous liquid used in the extraction process before it is used in the heating step of the method. For example, it may be desirable to centrifuge the comminuted product after the aqueous extraction process.

In one embodiment after the aqueous extraction process the comminuted product is centrifuged to remove excess aqueous liquid.

Having undergone the metal separating step and the aqueous extraction process step, according to the method of the invention the metal separated and aqueous extracted comminuted product is introduced into a vessel where it is heated under an inert atmosphere.

By the“metal separated and aqueous extracted comminuted product” is meant the product resulting after the comminuted product has, according to the method of the invention, undergone:

- separating from the comminuted product (i) magnetic metal, (ii) non-magnetic metal, or (iii) a combination thereof;

- subj ecting the comminuted product to an aqueous extraction process to separate from it aqueous soluble material.

There is no particular limitation on the type of vessel that may be used in accordance with the invention provided it can readily contain the metal separated and aqueous extracted comminuted product and withstand a chemical environment and temperatures experienced during the method.

The vessel may, for example be made from stainless steel or Pyrex™ glass. Those skilled in the art may commonly refer to the vessel as a“pyrolysis reactor”.

The vessel will generally be adapted so as to allow volatile organic compounds liberated from the metal separated and aqueous extracted comminuted product to be collected. For example, the vessel may have at least one outlet port positioned in the head space above the comminuted product designed to allow for the collection of the volatile organic compounds. The volatile organic compounds will generally be a mixture of compounds such as olefins, paraffins and aromatics.

The specific nature of the volatile organic compounds will of course depend upon the type of polymer/plastic and other organic compounds used in the manufacture of the Li-ion batteries.

In addition to being adapted to collect the volatile organic compounds, the vessel may also be adapted to allow removal of the non-volatile residue comprising metal salt. For example, the vessel may also have at least one outlet designed to remove such residue. The vessel may also be fitted with a means for agitating or stirring the metal separated and aqueous extracted comminuted product so as to promote even heating of the product. For example, the vessel may comprise one or more stirring elements which rotate within the vessel and stir the product.

Heating of the metal separated and aqueous extracted comminuted product within the vessel may be conducted by any suitable means. For example, a suitable heat source may be applied to the outside of the vessel, contained within the vessel, or a combination thereof. Suitable heat sources are well known to those skilled in the art.

In one embodiment, the metal separated and aqueous extracted comminuted product located in the vessel is heated using far infrared radiation (FIR). In that case, the FIR promotes heating of the product so as to convert organic material such as polymer/plastic and other organic compounds in the product into volatile organic compounds and leaves behind non-volatile residue comprising metal salt. It has been found that the product can be heated rapidly and in a controlled manner using FIR as a means of heating.

The metal separated and aqueous extracted comminuted product will generally be heated in the vessel to a temperature ranging from about 350°C to 600°C, or from about 350°C to about 500°C, or from about 400°C to about 500°C, or from about 400°C to about 450°C.

The heating step in accordance with the method of the invention is conducted under an inert atmosphere. Means for providing an inert atmosphere are described herein.

The heating step in accordance with the method of the invention is conducted under an inert atmosphere to minimise or prevent combustion of any components contained within the metal separated and aqueous extracted comminuted product and/or to minimise or prevent oxidation of the liberated volatile organic compounds.

In one embodiment, the metal separated and aqueous extracted comminuted product in the vessel is heated under an inert gas atmosphere.

To maximise the amount and quality of volatile organic compounds liberated during the heating step, it is desirable to rapidly heat and control the temperature of the metal separated and aqueous extracted comminuted product.

Using FIR as the heat source has been found to be particularly effective for that purpose and also to reduce the formation of coke within the vessel. Furthermore, using FIR as the heat source has been found to enable volatile organic compounds to be liberated from the comminuted product at relatively low temperatures. Without wishing to be limited by theory, it is believed that relatively low temperatures and short exposure time to such temperatures maximises the formation of volatile organic compounds and also reduces the formation of coke within the vessel.

Heating of the metal separated and aqueous extracted comminuted product by FIR may be conducted by any suitable means. For example, one or more FIR heaters may be located within the vessel. Generally, a plurality of FIR heaters will be positioned within the vessel. The FIR heaters therefore provide an“internal” or“direct” means for heating the product. That being in contrast with“external” or“indirect” means that rely on heating the vessel per se to transfer heat into the product.

Those skilled in the art will appreciate that FIR defines a part of the electromagnetic spectrum that falls between middle infrared radiation and microwave radiation. Far infrared radiation is commonly defined as any radiation within a wavelength of 15 micrometres to lmm (corresponding to a range of about 20 THz to 300 gHz).

Conventional FIR heaters can advantageously be used in accordance with the invention to provide the source of FIR. The FIR heaters will of course be configured to withstand conditions encountered by the method. For example, the FIR heaters may be in the form of ceramic rod elements sheaved with stainless steel sleeves coated with an appropriate emitter compound. The FIR heaters can be positioned within the vessel so as to be in direct contact with the comminuted product and promote efficient and effective heating thereof.

The heating step in accordance with the method of the invention liberates volatile organic compounds from the metal separated and aqueous extracted comminuted product. The volatile organic compounds are derived from organic material contained within the comminuted product. The nature of the organic material in the comminuted product will vary depending upon the components used in manufacturing the Li-ion battery. Such organic material will generally be derived from electrolyte composition and polymer/plastic components used in manufacturing Li-ion batteries.

A wide range of polymer/plastic materials may be used in the manufacture of Li-ion batteries. For example, polymer/plastic may be used as the outer case of the Li-ion battery. Such polymer/plastic materials may include, but are not limited to, polyethylene (PE), polypropylene (PP), acrylonitrile butadiene styrene (ABS), acrylic ester styrene acrylonitrile (ASA), styrene acrylonitrile (SAN), polystyrene (PS), high impact polystyrene (HIPS), polyurethane (PU), epoxy resins (EP), polyvinyl chloride (PVC), polycarbonate (PC), polyamide such as nylon (PA), polyoxymethylene (POM), polyesters such as polybutylene terephthalate (PBT) and polyethylene terephthalate (PET), unsaturated polyester (UP), and combinations or blends thereof.

Of these polymer/plastic materials, styrenic plastics such as ABS, ASA, HIPS, SAN and PS and PE, PP and PC, or blends thereof are more commonly used in the manufacture of Li-ion batteries.

Polymer binders may also be used in the manufacture of positive and/or negative electrodes used in Li-ion batteries. For example, fluorinated polymers such as polyvinyl fluoride (PVF) and polyvinylidene fluoride (PVDF) can be used as polymer binders in the manufacture of electrodes used in Li-ion batteries.

Without wishing to be limited by theory, the presence of such polymer/plastic components in comminuted product produced in accordance with the method of the invention can limit the ability to separate valuable components, such as metal salts, from the comminuted product.

However, the heating step according to the method of the invention has been found to break down or degrade such polymer/plastic material to provide for liberated volatile organic compounds thereby improving the ability to maximise separating valuable components (e.g. cobalt, nickel and lithium compounds) from the comminuted product. Upon liberation of the volatile organic compounds, such valuable components remain in the non-volatile residue and can be more readily isolated from that residue, for example by acid leaching as described in more detail below.

For example, polymer binders such as PVF and PVDF used in the manufacturing electrodes for Li-ion batteries can bind up valuable components of the Li-ion batteries making their extraction difficult. The heating step according to the method of the invention has been found to break down or degrade such polymer binder enabling such valuable components to be more readily extracted from the non-volatile residue left behind after the heating step.

Components used in the manufacture of Li-ion batteries might also include halogenated compounds that can function as a flame retardant or simply form part of the molecular structure of a given polymer/plastic.

The presence of such halogenated compounds can result in the liberation of toxic compounds such as halo acids and halogenated dioxins and furans during the heating step. It can be undesirable for such compounds to be generated during the heating step of the method according to the invention. Such halogenated compounds may be sufficiently volatile to be liberated in combination with other volatile organic compounds.

Where undesirable halogenated compounds are contained within the liberated volatile organic compounds, the collected volatile organic compounds may be subjected to conventional purification techniques such as fractionation and/or scrubbing to remove such undesirable compounds. As an alternative or additional technique for reducing the liberation of halogenated compounds during the heating step of the method according to the invention, additives may be introduced into the vessel with the metal separated and aqueous extracted comminuted product for the purpose of suppressing the liberation of such compounds. For example, a zeolite may be introduced into the vessel.

In one embodiment, a zeolite is introduced in to the vessel along with the metal separated and aqueous extracted comminuted product.

The volatile organic compounds liberated from the heating step according to the method of the invention may be collected by any suitable means. Generally, the vessel will be adapted to comprise a condensing column, for example a reflux column fractionator, such that the collected volatile organic compounds can be condensed and separated from the comminuted product. If desired the collected condensed organic compounds can be further processed by way of fractionation to separate different organic compounds according to their boiling point.

The collected liberated volatile organic compounds produced in accordance with the method of the invention can advantageously be used as a fuel oil.

In addition to liberating volatile organic compounds, the heating step according to the method of the invention also generates and leaves behind non-volatile residue comprising metal salt. The non-volatile residue may also comprise residual components not separated or extracted in previous steps of the method and/or one or more components not capable of being separated or extracted in a previous step of the method.

While the aqueous extraction process according to the method of the invention can extract aqueous soluble materials such as aqueous soluble metal salts from the comminuted product, it may be that such aqueous soluble material is not readily extracted from the comminuted product because it is intimately bound up with polymer/plastic material components of the Li- ion battery. In that case, the heating step according to the method of the invention can degrade such polymer/plastic material to form liberated volatile organic compounds and thereby enable such aqueous soluble material to be more readily separated from the non-volatile residue.

Accordingly, metal salt present within the non-volatile residue may include aqueous soluble metal salt and non-aqueous soluble metal salt.

The non-volatile residue will also generally comprise carbonaceous materials derived from carbonaceous material used in the manufacture of the Li-ion batteries and/or degradation products derived from organic material used in the manufacture of the Li-ion batteries.

The metal salt type and content of the non-volatile residue, together with any other components present, will of course vary depending upon the components used to manufacture the Li-ion battery. For convenience, the non-volatile residue may herein be collectively referred to simply as“pyrolytic residues”.

The vessel will generally be adapted to readily remove the pyrolytic residues by, for example, an outlet valve located at the bottom of the vessel. The pyrolytic residues removed from the vessel may comprise residual organic materials such as non-pyrolysed polymer/plastic and/or “heavy” liberated organic compounds. In that case the now isolated pyrolytic residues may be subjected to a second heating process, for example by being passed through a heat tunnel, whereby any residual organic material present is pyrolysed to yield a relatively free flowing fryable pyrolytic residue powder comprising metal salt.

The pyrolytic residue comprising metal salt can be collected for subsequent use. For example, the metal salt present in the residue may be isolated and purified using conventional isolation/purification techniques. For example, the pyrolytic residue might first be processed in a reverberator furnace and/or processed in a blast furnace and/or processed in an anode furnace to collect any metal components present.

The pyrolytic residue may also be processed by acid leaching to liberate metal salt contained therein. In one embodiment, isolated non-volatile residue from the vessel is subject to acid leaching.

The acid leachate from such an acid leaching process may then be treated with one or more compounds so as to precipitate metal salt from the leachate. The resulting precipitated metal salt may then be isolated from the acid leachate by conventional techniques such as filtration or centrifugation.

The non-volatile residue may, for example, comprise one or more metal salts of lithium, cobalt, and nickel.

For example, the non-volatile residue isolated from the vessel may comprise one or more lithium and/or cobalt salts. Those lithium and/or cobalt salts may be extracted from the residue by acid leaching (e.g. hydrochloric acid leaching), which can then be precipitated from the acid leachate by the addition of sodium hydroxide. The resulting precipitated cobalt and lithium hydroxides can then be isolated from the acid leachate by way of filtration and/or centrifugation.

The method according to the invention may be performed in a continuous, semi -continuous or batch mode.

The method of the invention can advantageously processes a diverse range of Li -ion batteries, making it extremely versatile and commercially attractive. Examples of Li-ion batteries that may be used in the method of the invention include, but are not limited to, lithium nickel cobalt aluminium oxide, lithium cobalt oxide, lithium nickel manganese cobalt, lithium manganese oxide, lithium iron phosphate, lithium nickel oxide, and lithium titanium oxide cells.

Embodiments of the invention are further described with reference to the following non limiting example. Examples

Example 1

Recycling of lithium ion batteries:

Step 1. 10 kg of mixed used lithium-ion batteries were shredded under nitrogen using an 80 kW industrial shredder with twin rotors and a 10 mm exit screen to produce a comminuted product.

Step 2. The comminuted product was passed over rare earth magnets which extracted 4% steel by weight. Step 3. The comminuted product from step 2 was then passed over an Eddy current separator which extracted 4% aluminium and 6% copper by weight.

Step 4. The comminuted product from step 3 was then extracted with hot water (by Soxhlet extraction) where it extracted 15% soluble lithium salts by weight. The aqueous lithium salts were converted to a precipitate of LECCE by addition of sodium carbonate to the liquid.

Step 5. The comminuted product from step 4 was then centrifugally dried and heated in a round bottom Pyrex flask in a furnace for 20 mins at 420 deg.C which led to a weight loss of 15% and the pyrolysis gases were condensed using a dry ice trap. The brown oil in the ice trap was analysed by ATR-IR and found to be a hydrocarbon oil with strong styrenic character and odour. A sample of the brown oil was ignited with a match and it burned quickly with a yellow carbonizing (sooty) flame indicating it can be used as a fuel oil.

Step 6. The non-volatile residue formed in step 5 was then mixed with Hydrochloric acid 36% (1 Molar) and stirred for 10 mins. The solution turned dirty blue indicating formation of cobalt chloride - this liquid was filtered off from the black sludge. Then the filtered solution was mixed with cone. NaOH which gave a precipitate of Cobalt Hydroxide. A Cobalt assay of that solution indicates that the cobalt in the char residue stream was 35 wt.% of the initial weight of the spent batteries. An ICP assay also detected nickel at 4% by weight of the initial weight of batteries used. The process also recovered 6 wt.% soluble lithium salt.

Step 7. The black sludge from step 6 was tested by ICP and found to be an admixture of carbon, manganese, silicon, calcium, titanium, iron and phosphorus. This sludge when dried was calculated to represent 11% by weight of the initially weight of lithium batteries.

The mass balance from the above steps was calculated to provide a component break down (based on the initial weight of the spent batteries) of:

Aluminium 4%

Copper 6%

Iron 4%

Lithium salts 21%

Mixed polymer/plastic/organic material 15%

Cobalt salts 35%

Nickel salts 4%

Other (carbon, manganese, silicon, calcium, titanium, iron and phosphorus) 11%.

The reference in this specification to any prior publication (or information derived from it), or to any matter which is known, is not, and should not be taken as an acknowledgment or admission or any form of suggestion that that prior publication (or information derived from it) or known matter forms part of the common general knowledge in the field of endeavour to which this specification relates.

Throughout this specification and the claims which follow, unless the context requires otherwise, the word "comprise", and variations such as "comprises" and "comprising", will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps.