Method for manufacturing a composite material

Abstract

The present invention relates to composite materials and methods for forming said composite materials. The present invention also relates to composite materials obtainable by the methods described herein.

Description

[Technical Field]

[0001] The present invention relates to composite materials and methods for forming said composite materials, which may be fabricated into thin electrode films. The present invention also relates to composite materials obtainable by the methods described herein. [Background technology]

[0002] Conventional batteries, including lithium (Li)-ion batteries, consist of a negative electrode, an electrolyte medium and separator material, and a positive electrode. The negative electrode of most commercially available lithium-ion batteries is copper foil coated with a mixture of graphite powder and a polymer blend such as polyvinylidene fluoride (PVDF). The positive electrode generally contains a mixture of lithium transition metal oxide, PVDF, and carbon black coated on aluminum foil.

[0003] Lithium-ion batteries require two electrodes to function: a positive electrode that stores lithium when the cell is discharged (or in a low-energy state), and a negative electrode that stores lithium when / as the cell is charged. The two electrodes are separated by a porous separator, and the movement of lithium from the negative electrode to the positive electrode in a liquid electrolyte occurs simultaneously with the flow of electrons, providing the battery's power to an external circuit. The reverse occurs when the battery is charged.

[0004] Commercial batteries use particulate anode and cathode materials for ease of fabrication and the need for pores within the electrodes to facilitate electrolyte ingress and localized lithium ion transport. These "active material" particles are typically coated onto sheet metal "current collectors" to support the active material and provide long-distance electron transport from the battery terminals to the entire battery. These current collector sheets are then arranged in a spiral or stack depending on the battery format, e.g., cylindrical, prismatic, or pouch.

[0005] A binder is typically required to adhere the particles to the current collector. Such a binder will generally be required to promote adhesion of the active materials to each other and to the conductive additive, and to allow uniform adhesion of the mixture to the current collector, while not inhibiting lithium ion migration to the surface of the active electrode particles.

[0006] There is no absolute freedom in selecting a binder material. The electrochemical nature of batteries means that any chemical component must meet specific requirements regarding reactivity with the electrochemical system to prevent cell capacity degradation over time. The well-known binder that best meets all of the above requirements is polyvinylidene fluoride (PVDF). It is very commonly used throughout cell manufacturing facilities and academia. NMP (N-methyl-2-pyrrolidone) is typically used as a solvent to dissolve PVDF and form the electrode coating slurry. The electrode coating slurry typically contains PVDF, active material, and conductive material. Once the slurry is coated onto the current collector, the NMP evaporates, adhering the mixture to the current collector. This coating and evaporation process is carried out continuously in industrial-scale cell manufacturing plants.

[0007] However, NMP is toxic, harmful to the environment, and expensive. The manufacturing system that uses, evaporates, and recycles NMP accounts for a significant portion of cell manufacturing costs (10-15%). Methods that utilize NMP must maintain efficiency to mitigate its impact.

[0008] Until now, manufacturers have been willing to sacrifice the cost of using NMP for the benefits that come from using PVDF as a binder. Reducing NMP from coating slurries is a major driver for cell manufacturers, especially as the global need for batteries expands exponentially as humanity transitions to green energy.

[0009] However, reducing the amount of NMP used in cathode coating methods increases the viscosity of the slurry. This reduces the flexibility of options for engineers incorporating high-surface-area carbon materials, which typically require low-viscosity systems (e.g., <1 Pa·s) for proper mixing with particulate cathode materials. A method is needed that can reduce the amount of NMP used in cathode coating methods while facilitating mixing of carbon additives in dispersion solvents with low viscosity.

[0010] The incorporation of high surface area conductive carbon materials into electrodes is desirable due to their favorable electronic properties. However, a potential drawback of known methods for producing conductive carbon-containing electrode composites is that if the carbon is not properly dispersed, separation of the component solids can occur, which can occur using standard mixing techniques. This can lead to uneven distribution of the components within the composite, affecting electrical performance.

[0011] The present invention was conceived with the above in mind. Summary of the Invention

[0012] In a first aspect, there is provided a method of making a composite material comprising an electrode active material, a polymeric binder, and a conductive material, the method comprising: i. providing a first dispersion comprising a dispersion solvent and a polymeric binder dissolved therein; ii. providing a poor solvent in which the polymeric binder is substantially insoluble; at least one of the first dispersion and the poor solvent includes an active material dispersed therein, and at least one of the first dispersion and the poor solvent includes a conductive material dispersed therein; Based on the total weight of the active material, conductive material, and polymeric binder, the active material is present in an amount of 80 to 99.5 wt. %; the conductive material is present in an amount of 0.01 to 15 wt. %; the polymeric binder material is present in an amount of 0.01 to 15 wt %; iii. contacting the first dispersion with an anti-solvent to form a suspension mixture, wherein the volume ratio of dispersion solvent to anti-solvent is from 1:1 to 1:10; contacting the first dispersion with an anti-solvent results in precipitation of the binder in the presence of the active material and the conductive material to form a composite material. A method is provided which includes:

[0013] In another aspect, based on the total weight of the active material, conductive material, and polymeric binder, i) a battery active material in an amount of 80 to 99.5 wt. % ii) a polymeric binder in an amount of 0.01 to 15 wt. % iii) a conductive material in an amount of 0.01 to 15% by weight A composite material is provided comprising:

[0014] In another aspect, there is provided a composite material obtained, obtainable or directly obtained by the method defined herein.

[0015] In another aspect, there is provided a composite slurry comprising a slurry solvent and a composite material as defined herein dispersed within the slurry solvent, wherein the composite material is present in the slurry solvent in an amount of at least 60% solids by weight.

[0016] In another aspect, there is provided the use of the composite slurry as defined herein as an electrode coating slurry.

[0017] In another aspect, there is provided an electrode comprising the composite material defined herein, suitably in the form of a film (i.e., an electrode film) coated on a current collector.

[0018] In another aspect, there is provided a battery comprising an electrode as defined herein. Preferably, the battery is a lithium-ion battery.

[0019] Methods of the Invention The present invention provides a method as defined herein for making a composite material comprising an electrode active material, a polymeric binder, and a conductive material, which method is typically carried out under low viscosity conditions and allows for the incorporation of high surface area carbon materials (e.g., graphene, carbon nanotubes).

[0020] In the method of the present invention, a homogeneous composite material comprising a binder, an active material, and a conductive material is formed in a suspension, which comprises the composite material dispersed in a mixture of a dispersing solvent and an anti-solvent.

[0021] Preferably, the active material is present in an amount of 85 to 99.5 wt %, more preferably 90 to 99 wt %, or most preferably 94 to 98.5 wt %, based on the total weight of the active material, conductive material, and polymeric binder.

[0022] Preferably, the polymeric binder material is present in an amount of 0.1 to 10 wt %, more preferably 0.5 to 6 wt %, and most preferably 1.0 to 2.5 wt %, based on the total weight of the active material, conductive material, and polymeric binder.

[0023] Preferably, the conductive material is present in an amount of 0.05 to 10 wt %, more preferably 0.1 to 6 wt %, and most preferably 1.0 to 2.5 wt %, based on the total weight of the active material, conductive material, and polymeric binder.

[0024] Preferably, the concentration of the polymeric binder in the dispersing solvent is from 0.001% to 10% by weight, more preferably from 0.01 to 5% by weight, or from 0.02 to 1% by weight.

[0025] Preferably, the volume ratio of the dispersing solvent to the anti-solvent is from 1:1 to 1:5, more preferably from 1:1 to 1:4. More preferably, the volume ratio of the dispersing solvent to the anti-solvent is from 1:1.5 to 1:3.

[0026] Preferably there is an excess of anti-solvent relative to the dispersing solvent.

[0027] In the context of the present invention, a dispersing solvent is a solvent in which the binder is at least partially soluble at 25°C and 1 atmosphere. Preferably, the dispersing solvent is a solvent in which the binder is substantially soluble at 25°C and 1 atmosphere.

[0028] The dispersion solvent may be selected from NMP, DMSO, silane, or a combination thereof. Preferably, the dispersion solvent is NMP or DMSO. Most preferably, the dispersion solvent is NMP.

[0029] A poor solvent is a solvent in which the binder is substantially insoluble (i.e., at least 1000 parts by weight of solvent are required to dissolve 1 part by weight of solute at standard operating temperatures (e.g., 25°C and 1 atmosphere).) Preferably, the active material and conductive material are also substantially insoluble in the poor solvent.

[0030] The anti-solvent may comprise one or more of methanol, water, acetone or mixtures thereof. Suitably, the anti-solvent is selected from methanol or a blend of water and acetone.

[0031] Suitably, the anti-solvent comprises no more than 75% by weight of water, for example, if a blend of acetone and water is used as the anti-solvent, it may comprise at least 25% by weight of acetone.

[0032] The blend of water and acetone may contain 10 to 75% water. Preferably, the blend of water and acetone may contain 30 to 70% water. Most preferably, the blend of water and acetone may contain 40 to 60% water.

[0033] Preferably, the viscosity of the first dispersion is 1 Pa·s or less before contacting with the poor solvent.

[0034] Preferably, the viscosity of the suspension mixture is 1 Pa·s or less after adding the anti-solvent to the first dispersion.

[0035] Preferably, the particle size of the active material before adding the anti-solvent has a d90 between 1 μm and 40 μm, more preferably the d90 may be between 10 μm and 30 μm.

[0036] A wide range of particle sizes of the conductive material may be utilized, for example, before adding the anti-solvent, the conductive material may have a d90 between 0.005 μm and 10 μm.

[0037] Further processing of the suspension mixture Preferably, once the composite material has been formed in the suspension, the method further comprises the step of removing a portion of the dispersing solvent and / or anti-solvent.

[0038] In certain embodiments, the method further comprises removing substantially all of the anti-solvent from the suspension. In such embodiments, the method may also comprise removing at least a portion of the dispersion solvent from the suspension.

[0039] In certain embodiments, the method further comprises removing at least a portion of the dispersion medium from the suspension.

[0040] In some embodiments, the method further comprises drying the suspension mixture to remove substantially all of the dispersion solvent and anti-solvent to provide a dried composite material. After removal of the dispersion solvent and anti-solvent, the dried composite material may be in the form of a powder or particulate material.

[0041] The composite material may be suitably dried. Drying may be accomplished, for example, by heating in a vacuum oven. In certain embodiments, substantially all of the dispersion solvent and anti-solvent may be removed during the drying process. The dried composite material may be processed into an electrode film (e.g., by coating on a current collector) or reconstituted into a composite slurry as described herein.

[0042] Preferably, the dried composite material has a d90 particle size of 10 to 5000 microns. More preferably, the composite material has a d90 particle size of 30 to 500 microns.

[0043] Preferably, the dispersing solvent and anti-solvent can be removed by a combination of different methods: The dispersing solvent and anti-solvent can be removed by filtration and / or decantation, The dispersing solvent and anti-solvent can also be removed by drying.

[0044] In some embodiments, substantially all of the anti-solvent is removed, leaving a portion of the dispersing solvent behind to provide a composite slurry.

[0045] The composite material may be dried and redispersed in a slurry solvent to form a composite slurry.

[0046] The process may also include filtering the composite material to remove non-composite material or material with a particle size less than 10 microns.

[0047] Formation of composite slurry In certain embodiments, the composite material formed in the suspension mixture can be incorporated into a composite slurry. The composite slurry preferably comprises the composite material defined herein in an amount of at least 60% solids by weight dispersed in a slurry solvent. Preferably, the binder material in the composite material is at least partially soluble in the slurry solvent under the conditions (e.g., room temperature and pressure) required for coating.

[0048] The slurry solvent can be selected from any solvent suitable for coating or extruding NMP, silane, ethylene carbonate, dimethyl carbonate, diethyl carbonate, propylene carbonate, DMF, or PVDF. Preferably, the slurry solvent is any one of the dispersion solvents described herein. Most preferably, the slurry solvent is NMP.

[0049] In certain embodiments, the suspension mixture containing the composite material can be reformulated to provide a composite slurry as defined herein. For example, if the active material includes NMC, the suspension can be formulated into a composite slurry by removing substantially all of the anti-solvent and, optionally, a portion of the dispersing solvent to provide a composite slurry containing the composite material in an amount of at least 60 wt.% solids dispersed within the dispersing solvent. In such embodiments, the dispersing solvent also serves as the slurry solvent.

[0050] In other embodiments, when the suspension mixture is dried to prepare a dried composite material, the dried composite powder may be redispersed in a slurry solvent to form a composite slurry.

[0051] Preferably, when the active material substantially comprises a lithium transition metal oxide, after reformulating the suspension mixture or dried composite material into a composite slurry, the concentration of the composite material in the composite slurry is between 60% and 99.9% by weight solids. More preferably, the concentration of the composite material in the formed composite slurry is between 60% and 90% by weight solids. Most preferably, the concentration of the composite material in the formed composite slurry is between 70% and 85% by weight solids.

[0052] Electrode thin film components The composite material of the present invention can be used to fabricate thin electrode films, particularly thin positive electrode films. As described herein, the composite material includes an active material, a binder, and a conductive material. These materials, together with any additional additives, can be collectively defined as the thin electrode film components.

[0053] active material The active material in the battery's electrode film is required to store and release cations (typically lithium ions). The active material in the electrode film or composite of the present invention can be any suitable active material known in the art. The selection of the active material preferably depends on whether the electrode film is to be used in a negative electrode or a positive electrode.

[0054] In a preferred embodiment of the present invention, the active material is a positive electrode active material.

[0055] The active material is capable of being intercalated, reacting with, and alloying with ions in a reversible electrochemical reaction. The ions may be selected from one or more of lithium, sodium, potassium, aluminum, magnesium, calcium, beryllium, lead, or nickel ions. Preferably, the ions are lithium ions.

[0056] The reversible electrochemical reaction allows for solid-phase binding and separation of ions, and the associated electron transfer can balance the charge, allowing at least 40% of the ions to return from the active material in the reverse electrochemical reaction.

[0057] The active material may be a lithium active material or a sodium active material.

[0058] The active material may be selected from one or more of the following: · Oxides, nitrides, carbides, sulfides, phosphides, and selenides of silicon, germanium, antimony, tin, lead, bismuth, zinc, aluminum, titanium, iron, nickel, manganese, cobalt, or cadmium, and mixtures thereof, or lithium-containing composite materials; · Transition metal lithium phosphates, e.g., lithium nickel phosphate, lithium cobalt nickel phosphate, lithium iron phosphate, mixed transition metal lithium phosphate; Lithium titanate, lithium manganate, lithium aluminate, lithium-containing titanium oxide; and Lithium transition metal oxides, such as: · NMC (lithium nickel manganese cobalt oxide) and its stoichiometric variants, e.g., 910, 811, 622, 532, 111; · NCA (Lithium Nickel Cobalt Aluminum Oxide) and its stoichiometric variants.

[0059] Preferably, the active material is selected from: LTO (lithium titanate); NMC (lithium nickel manganese cobalt oxide); NCA (lithium nickel cobalt aluminum oxide); LFP (lithium iron phosphate); or Silicon.

[0060] More preferably, the active material is selected from LTO (lithium titanate) or NMC (lithium nickel manganese cobalt oxide), for example NMC 811, NMC 910, NMC 622, NMC 532 or NMC 111, preferably NMC 811 or NMC 622.

[0061] Most preferably, the active material is NMC (lithium nickel manganese cobalt oxide), which may be NMC 811, NMC 910, NMC 622, NMC 532 or NMC 111, preferably NMC 811 or NMC 622.

[0062] Binder material The binder material in a battery exists mainly to adhere an electrode thin film to a substrate such as a current collector, etc. The binder material used in the present invention is a polymer, and may be a flexible polymer.

[0063] Preferably, the polymer binder is selected from the group consisting of polyvinylidene fluoride (PVDF), poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP), polyacrylic acid (PAA) and its alkali metal salts, modified polyacrylic acid (mPAA) and its alkali metal salts, methyl cellulose, carboxymethyl cellulose (CMC), modified carboxymethyl cellulose (mCMC), sodium carboxymethyl cellulose (Na-CMC), polyvinyl alcohol (PVA), alginate and its alkali metal salts, styrene-butadiene rubber (SBR), polyimide, polyethylene glycol (PEO), CMC / SBR blends, PAI (e.g., Torlon® AI-10), chitosan, chitosan sulfate ethylamide glycinamide glycinamide) (CSEG), polyvinylpyrrolidone (PVP), ammonium polyphosphate (APP), sulfonated polyetheretherketone with pendant lithiated fluorinated sulfonic groups (SPEEK-FSA-Li), lithiated poly(perfluoroalkylsulfonyl)imide (PFSILi) ionene, optionally further doped poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS), poly(9,9-dioctylfluorene-co-fluorenone-co-methylbenzoic acid) (PFFOMB), and poly(9,9-dioctylfluorene-co-fluorenone) (PFFO).

[0064] Most preferably, the polymeric binder is PVDF.

[0065] conductive materials Conductive materials (also known as conductive additives) play a key role in the electrochemical performance of lithium-ion batteries. Such materials establish a conductive percolation network that enhances and maintains the electronic conductivity of the electrodes, affecting the rate at which the battery can be charged and discharged, as well as the voltage drop associated with charging and discharging. Additionally, conductive additives act to absorb and retain electrolyte, ultimately helping to maintain intimate contact between the lithium ions and the active material.

[0066] The conductive material may comprise one or more of a two-dimensional layered material or a carbon-based conductive additive. Preferably, the conductive material comprises a conductive carbon material.

[0067] Suitable carbon-based conductive additives include carbon black, acetylene black, ketjen black, graphite, carbon fiber, carbon nanotubes, and graphene, as well as other hard carbons. Graphene (i.e., pristine graphene) can be considered a conductive carbon material and a 2D layered material.

[0068] Suitable two-dimensional (2D) layered materials include graphene-based materials and inorganic layered materials.

[0069] Exemplary two-dimensional (2D) layered materials include: graphene, graphene oxide, reduced graphene oxide, functionalized graphene, partially oxidized graphene (i.e., graphene with an oxygen content of less than 15% not reduced from graphene oxide, or preferably graphene with an oxygen content of less than 10 atomic % not reduced from graphene oxide); Metal oxide nanosheets composed of sheets of edge / corner sharing MO6 octahedra (where M is a transition metal and O is oxygen), the sheets being separated by alkali metal cations, protons, water, solvent, or any combination thereof; Metal double hydroxides consisting of octahedral hydroxide layers of divalent and trivalent metal cations, charge balanced by interlayer anions, with the general formula M 2+ 1-x M 3+ x (OH)2A n- x / n mH2O (where M 2+ =Mg 2+ , Fe 2+ , Co 2+ , Ni 2+ , Zn 2+ etc.;M 3+=Al 3+ , Fe 3+ , Co 3+ etc.; and A = (CO3) 2- , Cl - , (NO3) - , (ClO4) - etc.); · Phosphorene (black phosphorus). 2D chalcogenides: · Hexagonal boron nitride (hBN), fluorographene, boron carbonitride (BCN), SiC, Si2BN, silicene, germanene, stanene, borophene, graphene, plumbene; · Transition metal dichalcogenides of common stoichiometry MX2 (where M is a transition metal atom and X is a chalcogen atom) (e.g., MoS2, WS2, MoTe2, MoSe2, WSe2, etc.); · Other layered 2D materials consisting of fewer than four elements in a compound, fewer than 40 atoms in a simple lattice, covalently bonded in-plane and held out-of-plane by weak intermolecular forces; Layered semiconductors, such as GaSe, GaTe, InSe, Bi2Se3, etc.; 2D oxides; e.g., MnO2, WO3, TiO2, MoO3, V2O5, TaO3, RuO2, NaNbO3, α-Fe2O3, Nb2O5, Co3V2O8, Na 1.08 V3O8, etc. Layered Cu oxide. Perovskite-type, e.g., methylammonium lead halide (CH3NH3PbI3), cesium lead halide (CsPbX3), Bi4Ti3O 12 , Ca2Ta2TiO 10 etc. · Hydroxides, e.g., Ni(OH)2, Eu(OH)2, ZnAl layered double hydroxides (LDH). · Maxine: Sc2C(OH)2, Sc2CO2, Ti2CO2, titanium carbide (Ti3C2).

[0070] Preferably, the 2D layered material is selected from graphene, partially oxidized graphene (i.e., graphene with an oxygen content of less than 15 atomic %, or more preferably, graphene with an oxygen content of less than 10 atomic % that has not been reduced from graphene oxide), halogenated graphene, hexagonal boron nitride (hBN), 2D metal oxides, 2D metal hydroxides, and transition metal dichalcogenides (e.g., MoS2, WS2, MoTe2, MoSe2). Surprisingly and advantageously, the present invention does not require functionalization of the 2D material to form the composite material. Preferably, the 2D material is selected from graphene having less than 15% of its atoms covalently modified, or more preferably, graphene having less than 10% of its atoms covalently modified.

[0071] Preferably, the 2D material is selected from hBN, graphene, or a transition metal dichalcogenide. Preferably, the 2D material is graphene (i.e., pristine graphene) or graphene with an oxygen content of less than 15 atomic %. Preferably, the 2D material is a 60 cm -1 Graphene with a FWHM Raman peak less than 1000 nm.

[0072] In certain preferred embodiments of the present invention, the conductive material comprises one or more conductive carbon materials, such as carbon black, acetylene black, ketjen black, graphite, carbon fiber, carbon nanotubes, and graphene (e.g., pristine graphene), and other hard carbons. Preferably, the conductive material comprises one or more of pristine graphene, carbon black, or carbon nanotubes. More preferably, the conductive material comprises one or more of pristine graphene, carbon black, or carbon nanotubes.

[0073] In certain embodiments, the conductive material comprises a combination of carbon black and at least one of pristine graphene or carbon nanotubes.

[0074] It will be understood that certain conductive materials may have lower loadings than other materials. For example, if the conductive material includes only carbon black, the conductive material may be present in an amount of at least 0.3 wt. %. However, if the conductive material includes only graphene, for example, the conductive material may be present in an amount of at least 0.01 wt. % or 0.1 wt. %.

[0075] Dispersion solvent In a preferred embodiment, the binder of the present invention is completely dissolved in the dispersing solvent prior to forming the composite material.

[0076] Preferably, the dispersion solvent is a solvent with a boiling point above 150°C.

[0077] The dispersing solvent may be selected from any suitable solvent described herein, and the preferred use of one solvent over another depends on the solubility of the binder in the dispersing solvent, conductive material, and active material used in each embodiment.

[0078] Preferably, the dispersion solvent is selected from silane (dihydrolevoglucosenone); DMSO (dimethyl sulfoxide); NMP; butyl lactate; dimethyl isosorbide; triacetin; DMF; 1,2-dichlorobenzene; benzonitrile; pyridine; triethyl citrate; THF, cyclohexanone; cyclopentanone; olefins including pentane, hexane, cyclohexane, heptane, cyclooctane; ethyl acetate; ethyl lactate; furfural; eugenol; isoeugenol; levulinic acid; chloroform; 1,2-dichloromethane; toluene; methyl t-butyl ether; methyl ethyl ketone; trichloroethylene; xylene; IPA; water; acetone; methanol.

[0079] In a preferred embodiment, the dispersion solvent is selected from NMP, DMSO, silane or a mixture thereof. Most preferably, the dispersion solvent is NMP.

[0080] antisolvent Addition of a poor solvent to the dispersion solvent causes the binder to precipitate from the dispersion solvent. By precipitating the binder, the binder particles act as a flocculant that binds the active material and the conductive material. Thus, addition of the poor solvent causes the binder, active material, and conductive material to flocculate, forming a composite material in which the components are bound together. The advantage of applying binder flocculation with a poor solvent over other methods is the relatively rapid immobilization, in which the components in the composite material may not have time to separate.

[0081] A suitable anti-solvent for the binder material depends on the solubility profile of the binder used. The binder is typically substantially insoluble in the anti-solvent.

[0082] Preferably, the anti-solvent is or comprises a water-soluble solvent (including water), more preferably the anti-solvent comprises one or more of methanol, water, acetone or mixtures thereof.

[0083] Preferably, when the binder is PVDF, water alone is not used to precipitate the binder. Preferably, the anti-solvent comprises no more than 75% by weight of water.

[0084] Preferably, the anti-solvent is selected from a mixture of methanol or acetone and water, the ratio of water to acetone may be from 0.25:1 to 4:1, more preferably from 0.5:1 to 2:1, or most preferably from 0.75:1 to 1.25:1.

[0085] In certain embodiments, the dispersion solvent is NMP and the anti-solvent is selected from methanol or a mixture of acetone and water (e.g., a water to acetone ratio of 0.25:1 to 4:1, 0.5:1 to 2:1, or 0.75:1 to 1.25:1).

[0086] Mixing of binder, active material, and conductive material Preferably, in the process of the present invention, the battery active material is added in an amount of 85 to 99.5 wt % based on the total weight of the electrode components. More preferably, the battery active material is present in an amount of 90 to 99 wt % based on the total weight of the electrode components. Most preferably, the battery active material is present in an amount of 94 to 98.5 wt % based on the total weight of the electrode components.

[0087] Preferably, in the process of the present invention, the conductive material is added in an amount of 0.05 to 10 wt % based on the total weight of the electrode components. More preferably, the conductive material is present in an amount of 0.1 to 6 wt % based on the total weight of the electrode components. Most preferably, the conductive material is present in an amount of 1.0 to 2.5 wt % based on the total weight of the electrode components.

[0088] Preferably, in the process of the present invention, the binder is added in an amount of 0.1 to 10 wt % based on the total weight of the electrode components. More preferably, the binder is present in an amount of 0.5 to 6 wt % based on the total weight of the electrode components. Most preferably, the binder is present in an amount of 1.0 to 2.5 wt % based on the total weight of the electrode components.

[0089] The process of the present invention converts smaller sized individual materials (e.g., binder, conductive material, and active material particles) into a larger sized composite material, e.g., the average particle size of the active material before precipitation of the binder is less than 20 microns, and after formation of the composite material including the binder, conductive material, and active material particles, typically increases to 200 microns or more.

[0090] Preferably, substantially all of the electrode components added to the first dispersion are included in the final composite material, however, if any of the individual components remain in uncomplexed form, they may be removed from the suspension mixture, for example, by filtration.

[0091] Preferably, both the active material and the conductive material are present in the first dispersion prior to the formation of the composite by the addition of the anti-solvent. Thus, the first dispersion preferably comprises a dispersion solvent, a polymeric binder dissolved therein, and an active material and a conductive material dispersed therein.

[0092] Preferably, the components are thoroughly mixed in the solvent in which they reside, i.e., the anti-solvent or first dispersion, to achieve a homogeneous distribution of the components.

[0093] Suitably, the components in the first dispersion and the anti-solvent are typically thoroughly mixed to ensure a homogeneous dispersion of the active material and conductive material in the formed composite material.

[0094] After the anti-solvent has contacted the first dispersion, the suspension is also thoroughly mixed.

[0095] Mixing is preferably carried out throughout the process of the present invention to maintain a homogeneous distribution of the components.

[0096] The mixing may comprise one or more of sonication, stirring, planetary mixing, shear mixing, or any of the methods disclosed herein. Preferably, the mixing comprises shear mixing and / or planetary mixing.

[0097] The electrode components can be mixed in the dispersing solvent using standard mixing techniques known in the art, such as sonication, stirring, high shear homogenization, mixing, high pressure homogenization, etc. The binder can be dissolved in the dispersing solvent before or after the addition of the remaining components.

[0098] Preferably, the conductive material, the active material and the further additives are added to the first dispersion or the anti-solvent, and the dispersion of the mixture in the respective solvents to form a homogeneous slurry can be preferably carried out after adding each component to the dispersion solvent or the anti-solvent.

[0099] Mixing can be performed continuously throughout the process, and thus the slurry can be exposed to shear energy (mixing, sonication, etc.) throughout the process of the present invention.

[0100] Composite material of the present invention The present invention also provides a composite material as defined herein.

[0101] As the binder precipitates from the dispersing solvent in the presence of the active material and conductive material, agglomerated particles of solid binder form in the slurry. As the agglomerated particles form in the presence of the remaining electrode components, such as the active material and conductive material, the binder adheres to these components, solidifying and bonding them together, forming a homogeneous composite of the electrode components.

[0102] Composite material of the present invention As discussed above, the present invention provides i) a battery active material in an amount of 80 to 99.5 wt. % ii) a polymeric binder in an amount of 0.01 to 15 wt. % iii) a conductive material in an amount of 0.01 to 15% by weight A composite material comprising:

[0103] Preferably, the binder, active material and conductive material are selected from any of the materials described herein.

[0104] Preferably, the composite material of the present invention comprises the battery active material in an amount of 85 to 99.5 wt%, more preferably 85 to 99 wt%, or most preferably 94 to 98.5 wt%.

[0105] Preferably, the composite material of the present invention comprises the conductive material in an amount of 0.1 to 10 wt %, more preferably 0.5 to 6 wt %, or most preferably 1.0 to 2.5 wt %.

[0106] Preferably, the composite material of the present invention comprises the binder material in an amount of 0.1 to 10 wt%, more preferably 0.5 to 6 wt%, or most preferably 1.0 to 2.5 wt%.

[0107] The composite materials formed in the present invention are typically in the form of solid, coherent agglomerates, such as powders or particulate materials.

[0108] Preferably, the dried composite material has a d90 particle size of 10 to 5000 microns. More preferably, the composite material has a d90 particle size of 30 to 500 microns.

[0109] Composite slurry of the present invention The composite material formed according to the present invention can be mixed in a solvent such as NMP to form a slurry with a relatively high solids content while incorporating high surface area, well-mixed carbon. Providing a high solids slurry means that less NMP may be required during the wet mixing and electrode coating and drying process.

[0110] Accordingly, the present invention provides a composite slurry comprising a slurry solvent and a composite material as defined herein dispersed within the slurry solvent, wherein the composite material is present in an amount of at least 60% solids by weight, and wherein the polymeric binder present in the composite material is soluble in the slurry solvent.

[0111] Preferably, the concentration of the composite material in the formed composite slurry is between 60% and 90% solids by weight, and most preferably, the concentration of the composite material in the formed composite slurry is between 70% and 85% solids by weight.

[0112] Preferably, the slurry solvent is any of the dispersion solvents described herein. Most preferably, the slurry solvent is NMP.

[0113] Preferably, the composite particles in the composite slurry have a smaller d90 than the dried composite powder.

[0114] Preferably, the viscosity of the composite slurry of the present invention is 1 Pa·s or greater. More preferably, the viscosity of the composite slurry is at least 6 Pa·s, e.g., between 6 and 10 Pa·s. Such slurries may be suitable for mass production of coated electrodes, e.g., using slot die coating. Alternative embodiments of the composite slurry may have significantly higher viscosities, e.g., greater than 10 Pa·s or greater than 20 Pa·s. High-viscosity composite slurries may be coated onto surfaces using extrusion techniques, such as twin-screw mixing.

[0115] In some embodiments, the composite slurry defined herein may be used to coat a current collector in the formation of a battery electrode.

[0116] A particular advantage of the present invention is the broad utility of the formed composite in different coating scenarios. While other efforts have focused on the production of entirely dry powders, the option to use a wide range of liquid-based deposition processes (e.g., slot die, reverse comma bar, extrusion) is advantageous due to its compatibility with the existing infrastructure already invested in battery factories around the world.

[0117] The present invention also provides the use of the composite slurry as defined herein as an electrode coating slurry.

[0118] The composite slurry as defined herein may be utilized in wet mixing techniques. Accordingly, there is provided the use of the composite slurry as defined herein in a wet mixing process.

[0119] In one embodiment, the wet mixing method comprises: a) forming or preparing a composite slurry, as defined herein, comprising a composite material and a slurry solvent; b) applying the composite slurry to a substrate; c) applying the composite slurry to the substrate and then removing the slurry solvent to adhere the composite material to the surface of the substrate. Includes:

[0120] The substrate can be a current collector, for example, an aluminum, copper, nickel, titanium, or steel current collector.

[0121] The wet mixing process may suitably be a process for forming an electrode.

[0122] The composite slurry mixture may be applied to the substrate by any conventional wet coating process, preferably selected from the group consisting of screen printing, coating using a roll coater, blade coater, slit coater (slot die coater), comma bar coater, curtain coater, wire coater, sprayer, foam applicator, and brush coater.

[0123] Illustrative Embodiments Exemplary methods for preparing thin electrode films, and subsequently lithium ion batteries, are provided below: 1. NMC 811 (active material) is mixed with suspended graphene sheets (conductive material) in NMP (dispersion solvent). 2. PVDF (binder) is dissolved in NMP (dispersion solvent) and added to the mixture, and shear energy is applied to the mixture to thoroughly mix all the components. 3. An anti-solvent is thoroughly mixed into the mixture to produce a solid composite product. The anti-solvent is a blend of acetone and water (75:25 acetone:water). 4. The solid product is filtered and dried to produce a composite product. 5. The composite product is formed into a composite slurry by mixing in NMP at 61 wt% solids. 6. The composite slurry is coated onto a current collector, dried, and calendered to form a thin electrode film. 7. The current collector is assembled with a separator, counter electrode, and electrolyte in a sealed container to function as a lithium-ion battery.

[0124] For each of the above steps, it is recognized that the associated active materials, conductive materials, dispersing solvents, binders, anti-solvents, and additional solid materials may be substituted with any suitable materials disclosed herein. The associated active materials, conductive materials, dispersing solvents, binders, anti-solvents, and additional solid materials may be present in any of the amounts described herein.

[0125] Similarly, the further processing steps to form the electrode film may be replaced by any suitable process for converting the film into an electrode film and further assembling the film into a battery.

[0126] Battery using the composite material of the present invention Following the formation of an electrode comprising a thin electrode film coated on a current collector, the method of the present invention preferably further comprises the step of assembling a battery comprising the current collector coated with the thin electrode film. Assembling the battery preferably comprises the step of assembling the coated current collector together with a separator, a counter electrode, and an electrolyte in a sealed container. The counter electrode may be either a negative electrode or a positive electrode, as appropriate.

[0127] Counter electrodes for use in batteries may also be prepared according to the methods of the present invention.

[0128] Specific Embodiments of the Invention In one embodiment, the method comprises: i. providing a first dispersion comprising a dispersing solvent and a polymeric binder dissolved therein, the dispersing solvent further comprising an active material and a conductive material dispersed therein, the active material, the conductive material, and the polymeric binder material being present in amounts defined herein; ii. providing an anti-solvent in which the binder is substantially insoluble; iii. contacting the dispersion solvent with an anti-solvent to form a composite material as described herein, wherein the ratio of dispersion solvent to anti-solvent is as defined herein. Includes:

[0129] In certain embodiments, the conductive material comprises a conductive carbon material and the polymer binder is PVDF; a. the dispersion solvent is selected from DMSO, NMP, or silane or a mixture thereof; b. The anti-solvent comprises methanol, dichloromethane, acetone, water, ethanol, or a mixture thereof.

[0130] In certain embodiments, the conductive material comprises a conductive carbon material and the polymer binder is PVDF; a. The dispersion solvent is NMP; b. The anti-solvent comprises methanol, acetone, water or a mixture thereof.

[0131] In certain embodiments, a. the conductive material includes a conductive carbon material; b. the polymeric binder is PVDF; c. The active material is selected from LTO (lithium titanate), NMC (lithium nickel manganese cobalt oxide), NCA (lithium nickel cobalt aluminum oxide), LFP (lithium iron phosphate), or silicon (e.g., 300 mesh silicon chunks); d. the dispersion solvent is selected from DMSO, NMP, or silane or a mixture thereof; e. Anti-solvents include methanol, dichloromethane, acetone, water, ethanol, or mixtures thereof.

[0132] In certain embodiments, a. the conductive material comprises a conductive carbon material selected from one or more of carbon black, carbon nanotubes, and pristine graphene; b. the polymeric binder is PVDF; c. the active material is selected from LTO, NMC, NCA, LFP, or silicon; d. The dispersion solvent is NMP; e. The anti-solvent comprises one or more of methanol, acetone, water or mixtures thereof.

[0133] In certain embodiments, a. the conductive material comprises a conductive carbon material selected from one or more of carbon black, carbon nanotubes, and pristine graphene; b. the polymeric binder is PVDF; c. the active material is selected from LTO or NMC; d. The dispersion solvent is NMP; e. The anti-solvent comprises one or more of methanol, acetone, water or mixtures thereof.

[0134] In embodiments of the process of the present invention, and the composite material of the present invention, the active material, conductive material, and polymeric binder are present in the following relative amounts:

[0135] JPEG2026504696000001.jpg14170

[0136] In embodiments of the process of the present invention, and the composite material of the present invention, the active material, conductive material, and polymeric binder are present in the following relative amounts:

[0137] JPEG2026504696000002.jpg14170

[0138] In embodiments of the process of the present invention, and the composite material of the present invention, the active material, conductive material, and polymeric binder are present in the following relative amounts:

[0139] JPEG2026504696000003.jpg13170

[0140] In embodiments of the process of the present invention and the composite material of the present invention, the viscosity of the first dispersion containing all of the active material, conductive material, and polymer binder, measured immediately before the addition of the poor solvent or any additional materials, is 1 Pa·s or less.

[0141] In embodiments of the process of the present invention and the composite material of the present invention, the viscosity of the composite slurry containing the composite material of the present invention measured immediately prior to coating onto a substrate is greater than 1 Pa·s.

[0142] Embodiments of the present invention are further described below with reference to the accompanying drawings. [Brief explanation of the drawings]

[0143] [Figure 1] The UV / Vis absorbance (solid bars) and extrapolated theoretical supernatant graphene concentration (striped bars) of the composite samples are shown, along with the respective sedimented solid volume reduction relative to the solution (solid dots). The insets 8x and 10x represent the dilution required for UV-Vis data collection. The striped bars were corrected for this dilution. The graphene concentration is labeled "carbon." The numerical notation (UV / Vis absorbance) above the solid bars refers to the exact number of supernatant samples measured in a 1 cm pathlength cuvette. [Figure 2] Figure 1 shows example images of the solid components after 1 hour of settling. IDs, from left to right, are: no binder, no LTO, no graphene, and all components present (control). DETAILED DESCRIPTION OF THE INVENTION

[0144] The present invention provides a process for efficiently producing dry composites containing electrode active materials, polymeric binders, and conductive materials, where the conductive materials are mixed in a low viscosity process (≦1 Pa.s). Such powders can be mixed with a solvent to produce high viscosity, low NMP content electrode coating slurries (i.e., composite slurries).

[0145] Due to the process of the present invention, the components of the composite material of the present invention are strongly bonded within the composite material, which results in a composite material that does not break down into its constituent parts when dispersed in a solvent such as NMP.

[0146] definition The term "slurry" in the context of the present invention is intended to mean a mixture comprising a liquid (e.g., dispersion solvent) and undissolved (active material and conductive material) and / or partially / completely dissolved solid materials. Generally, the term "slurry" can be used interchangeably with the term "dispersion" and with the term "suspension". However, in the context of the present invention, three terms are used to indicate the composition of the slurry obtained at different stages of the process: a. "First dispersion" refers to a slurry mixture of a dispersing solvent, a dissolved binder, and optionally further including an active material and / or a conductive material dispersed within the dispersing solvent. b. "Suspension" or "suspension mixture" refers to the mixture of formed composite material that exists after precipitation of the binder in the presence of an anti-solvent, a dispersing solvent, and an active material and a conductive material to form the composite material. c. "Composite slurry" refers to a mixture that includes a solvent in which the binder material is at least partially soluble and a formed composite material. Preferably, the composite slurry does not include any solvent in which the binder material is insoluble.

[0147] Without wishing to be bound by theory, it is believed that the components of the composite materials of the present invention (i.e., the active material, binder, and conductive material) are attracted to each other in the presence of a polymer such as PVDF as the polymer precipitates.

[0148] Agglomeration is an advantageous step to include in the process because it does not require large amounts of liquid evaporation or other physical means to obtain the product, but instead provides access to large amounts of solvent that can be filtered by coarse filtration or sedimentation. Given that it is often difficult to obtain a good dispersion of 2D materials in solvent, product agglomeration allows for the recycling of large amounts of solvent that may be required when scaling up the production of 2D particulate material composites.

[0149] The interaction between the active material and the conductive material (in the presence of precipitated polymer particles) increases the particle size of the composite relative to the particulate material. This occurs due to the formation of "secondary particles" (aggregates of the composite material) in the dispersing solvent. Therefore, the use of anti-solvent precipitation is advantageous over simple high-shear mixing of particulate and 2D materials, as it can form larger, combined particles. These larger particles are known to have more predictable properties than nano-sized particles (e.g., nano-sized particles can be difficult to stabilize), making the larger particles beneficial for further processing steps.

[0150] In the methods described herein, the addition of an anti-solvent to the binder in the dispersion solvent induces the conductive material and particulate material to aggregate and form a composite. The binder is present in an amount sufficient to induce aggregation. Without wishing to be bound by theory, it is believed that this inducement of aggregation improves the interaction between the 2D material and the particulates. This often results in an increase in particle size due to the interaction between the 2D material and the particulate material. This results in a more efficient process for producing composites of 2D materials than previously demonstrated in the prior art. Before the addition of the anti-solvent, the particle size in the dispersion is expected to be the size at which it was created, e.g., particles of 1 μm or larger. Typically, only small, unagglomerated particles (e.g., less than 10 μm) are observed under a microscope before the addition of the anti-solvent. However, larger particles may be visible depending on the preparation method used to form the dispersion.

[0151] Agglomerated products are advantageous because the formed agglomerated materials are easily separated from the dispersed mixture during agglomeration, allowing for efficient solvent recycling. This also means that relatively large amounts of solvent can be used to disperse the 2D materials, reducing the risk of the 2D materials agglomerating with themselves and ensuring a homogenous mixture of composite materials.

[0152] The term "two-dimensional material" (2D material) can refer to a form of compound that is so thin that it can exhibit different properties than the same compound in bulk. Typically, two-dimensional inorganic compounds are in the form of a single layer or a few layers thick, i.e., up to 10 layers thick. Two-dimensional crystals of layered materials (e.g., inorganic compounds or graphene) are single- or few-layered particles of that material.

[0153] Those skilled in the art will appreciate that a 2D material can be defined as a layered material with an in-plane elastic modulus significantly greater than the interlayer shear modulus. Such materials include, but are not limited to, graphene, WS2, MoS2, and hexagonal boron nitride. Typically, a 2D material contains 1 to 10 molecular layers.

[0154] Although 2D materials do exhibit thickness, their thickness dimension is significantly smaller than the width and length of these materials, hence the name "2D materials."

[0155] The term "few-layer particles" refers to particles that are so thin that they may exhibit different properties than the same compound in bulk. While not all of the compound's properties differ between few-layer particles and bulk compounds, one or more properties may differ. A more convenient definition would be for the term "few-layer" to refer to crystals whose cross-sections are 2 to 9 atomic or molecular layers thick (e.g., 2 to 5 layers thick). For example, graphene crystals with more than 9 molecular layers (i.e., 10 atomic layers, 3.5 nm) generally exhibit properties closer to graphite than graphene. An atomic or molecular layer is the smallest chemically possible thickness for a compound. For boron nitride, one molecular layer is one atom thick. For transition metal dichalcogenides (e.g., MoS2 and WS2), a molecular layer is three atoms thick (one transition metal atom, two chalcogen atoms). Thus, few-layer crystals of 2D materials are generally less than 50 nm thick, preferably less than 20 nm thick, e.g., less than 10 or 5 nm thick, depending on the compound. However, with current top-down manufacturing methods such as ball milling, shear mixing, and liquid-phase exfoliation, the final dispersion consists of a distribution of thicknesses rather than a single, defined thickness.

[0156] The term "inorganic layered compound" refers to a compound composed of two or more elements that forms a layered structure in which the bonds between atoms within the same layer are stronger than the bonds between atoms in different layers. Many examples of inorganic layered compounds have covalent bonds between atoms within a layer, but van der Waals bonds between layers. The term "inorganic layered compound" is not intended to encompass graphene.

[0157] Many inorganic compounds exist in several allotropic forms, some of which are layered and some of which are not: for example, boron nitride can exist in both a layered graphite-like structure and a diamond-like structure in which the boron and nitrogen atoms are tetrahedrally oriented.

[0158] Examples of layered inorganic compounds to which the present invention can be applied include hexagonal boron nitride (h-BN), bismuth strontium calcium copper oxide (BSCCO), transition metal dichalcogenides (TMDC), Sb2Te3, Bi2Te3, and MnO2.

[0159] TMDCs are structured so that each layer of the compound consists of three atomic planes: one layer of transition metal atoms (e.g., Mo, Ta, W) sandwiched between two layers of chalcogen atoms (e.g., S, Se, or Te). Thus, in one embodiment, a TMDC is a compound of one or more of Mo, Ta, and W with one or more of S, Se, and Te. There are strong covalent bonds between atoms within each layer of the transition metal chalcogenide, and predominantly weak van der Waals bonds between adjacent layers. Exemplary TMDCs include NbSe2, WS2, MoS2, TaS2, PtTe2, and VTe2.

[0160] The graphene layers are sp 2 It consists of sheets of hybridized carbon atoms. Each carbon atom is covalently bonded to three neighboring carbon atoms, forming a tessellated hexagonal "honeycomb" network. Carbon nanostructures with more than 10 graphene layers (i.e., 10 atomic layers, 3.5 nm) generally exhibit properties more similar to graphite than single-layer graphene. Thus, throughout this specification, the term graphene refers to carbon nanostructures with up to 10 graphene layers (e.g., 90% of the graphene flakes have a thickness of 2 to 7 layers, or 90% of the graphene flakes have a thickness of 3 to 10 layers). Graphene is the "ultimate" 2D material because it is defined by having a layer / sheet one carbon atom thick, the structural unit of graphite.

[0161] The level of graphene defects in composites can be assessed using Raman spectroscopy in a manner similar to that described by L.G. Cancado et al., 2011, “Quantifying Defects in Graphene via Raman Spectroscopy at Different Excitation Energies,” Nano Letters, incorporated herein by reference. The ratio of the observed D-peak Raman intensity, referred to as I(D), to the intensity of the G-peak Raman intensity, referred to as I(G), indicates the amount of defects present in the graphene. This is referred to as the I(D) / I(G) ratio. The distance between defects is a measure of the amount of disorder. Given that the distance between defects is greater than approximately 4 nm, the lower the I(D) / I(G) ratio, the less disorder there is, due to the longer distance between defects. In addition, the full width at half maximum (FWHM) of the D, G, 2D (2D is also called G'), and D' peaks can be used to assess the level of disorder, as discussed in E.H. Martins Ferreira et al. 2010, "Evolution of the Raman spectra from single-, few-, and many-layer graphene with increasing disorder," PHYSICAL REVIEW B. If the FWHM of the D, G, 2D (2D is also called G'), and D' Raman peaks reaches values ​​of less than 20 cm-1, 20 cm-1, 35 cm-1, and 10 cm-1, respectively, at a laser excitation wavelength of 514.5 nm (2.41 eV), the distance between zero-dimensional point-like defects is expected to be longer than about 4 nm.

[0162] Composite materials comprising graphene formed by the methods of the present invention may have an I(D) / I(G) ratio of less than 0.75, less than 0.6, or preferably less than 0.5 at a laser excitation wavelength of 532 nm (2.33 eV). Thus, composite materials formed by the methods of the present invention may have an I(D) / I(G) ratio of 0.01 to 0.75, 0.02 to 0.65, or 0.04 to 0.55 at a laser excitation wavelength of 532 nm (2.33 eV). Given that the distance between defects is greater than about 4 nm and a laser excitation wavelength of 532 nm (2.33 eV), an I(D) / I(G) ratio of less than 1 indicates defect spacing greater than 9.5 nm.

[0163] Raman spectroscopy can also be used to characterize the nature of graphene defects. Defects in graphene are generally considered to be those that break the symmetry of the infinite carbon hexagonal lattice. These include edges, vacancies, and changes in carbon hybridization (e.g., sp 2 From sp 3 sp 3 The defect is the presence of an additional atom outside the plane of the graphene layer, sp 3 These defects are caused by hybridized or multiple carbon atoms, vacancy defects are caused by one or more missing atoms in the 2D material layer, and edge defects are caused by the graphene sheet not being infinitely large and therefore having edges.

[0164] Partially oxidized graphene and pristine graphene can be distinguished from graphene oxide, functionalized graphene, and reduced graphene oxide using Raman spectroscopy, as discussed herein. Graphene oxide and functionalized graphene contain a large amount of sp 3 Reduced graphene oxide is formed from the reduction of graphene oxide by reducing agents or temperature treatment. Reduced graphene oxide also contains a large amount of vacancy defects as a result of oxygen removal, leaving holes in the hexagonal lattice. As such, graphene oxide and reduced graphene oxide typically have an I(D) / I(G) ratio greater than 0.8 or 70, 70, and 150 cm, respectively. -1The FWHM of the D, G, and 2D (called G' in some literature) peaks exceeds 1000 MPa. Conversely, partially oxidized graphene has fewer oxygen atoms than graphene oxide, but it has not undergone the harsh reduction process of reduced graphene oxide. Therefore, it maintains more of its hexagonal structure and has sp 3 This means fewer defects and voids. The number of defects can be assessed by measuring the I(D) / I(G) ratio or the FWHM of the peaks, as discussed above.

[0165] sp 3 The presence of defects and voids can adversely affect the usefulness of the final composite material. 3 and / or it is desirable to minimize the number of void defects.

[0166] The ratio of the intensities of the Raman D peak, designated I(D), to the Raman D' peak, designated I(D'), indicates the type of defect present in the sample. This is called the I(D) / I(D') ratio. A ratio of less than approximately 3.5 at a laser excitation wavelength of 514.5 nm (2.41 eV) indicates a dominant contribution from edge defects. A ratio of approximately 7 indicates the presence of vacancy defects, while a ratio of approximately 13 or greater indicates sp3 defects.

[0167] The graphene composite material of the present invention exhibits a 70 cm -1 The FWHM-(G) (full width at half maximum of the graphene Raman G peak in the Raman spectrum) may be less than 60 cm at a laser excitation wavelength of 514.5 nm (2.41 eV). -1 More preferably, the FWHM-G is less than 50 cm at a laser excitation wavelength of 514.5 nm (2.41 eV). -1 More preferably, the FWHM-(G) is less than 40 cm at a laser excitation wavelength of 514.5 nm (2.41 eV). -1 Most preferably, the FWHM-(G-) is less than 30 cm at a laser excitation wavelength of 514.5 nm (2.41 eV). -1 is less than.

[0168] The graphene-containing composite material of the present invention exhibits a 100 cm -1 The graphene Raman 2D peak may have a FWHM-(2D) (full width at half maximum) of less than 80 cm at a laser excitation wavelength of 514.5 nm (2.41 eV). -1 More preferably, the FWHM-(2D) is less than 60 cm at a laser excitation wavelength of 514.5 nm (2.41 eV). -1 Even more preferably, the FWHM-(2D) is less than 50 cm at a laser excitation wavelength of 514.5 nm (2.41 eV). -1 The graphene-containing composite materials of the present invention may have an I(D) / I(D') ratio of 0.01 to 7, 0.01 to 4.5, 0.01 to 3.5, or preferably 0.1 to 3.45 at a laser excitation wavelength of 532 nm (2.33 eV). Thus, the composite materials of the present invention preferably have minimal sp3 defects, and more preferably have minimal vacancy defects.

[0169] Graphene oxide typically contains a weight percent of oxygen greater than 15% by weight. Within the scope of the present invention, the term "partially oxidized graphene" may be interpreted as graphene oxide containing only oxygen in an amount of up to 15%, e.g., 5-15% by weight, of the total weight of the graphene. Typically, partially oxidized graphene will contain oxygen in an amount of up to 10% of the total weight of the graphene. As discussed above, the term "pristine graphene" refers to graphene that has not been chemically modified.

[0170] The described process can be performed using graphene that is substantially chemically unmodified, i.e., pristine graphene. Typically, such graphene quality is achieved using liquid-phase exfoliation methods. However, some graphene production methods introduce a degree of oxidation (less than 15%), which can result in partially oxidized graphene as a result of slight oxidation that facilitates faster exfoliation. However, unlike previous studies of graphene oxide, this degree of oxidation does not necessarily enhance the processability of graphene. Preferably, the degree of partial oxidation / defects should be kept as low as possible to reduce its impact on the electrical conductivity of the final composite.

[0171] "Graphene-based" materials refer to 2D layered materials containing a hexagonal carbon skeleton, such as graphene, graphene oxide, reduced graphene oxide, and functionalized graphenes (e.g., fluorinated graphene). Therefore, "non-graphene-based" materials refer to materials that can be called "inorganic layered compounds." The term "inorganic compound" therefore refers to a compound composed of two or more elements that forms a layered structure in which the bonds between atoms within the same layer are stronger than the bonds between atoms in different layers. Many examples of inorganic layered compounds have covalent bonds between atoms within a layer, but van der Waals bonds between layers. The term "inorganic layered compound" is not intended to encompass graphene or graphene derivatives.

[0172] Specific examples of non-graphene-based layered inorganic compounds to which the present invention can be applied include: Graphene-like materials such as hexagonal boron nitride (h-BN), fluorographene, boron carbonitride (BCN), SiC, Si2BN, silicene, germanene, stanene, borophene, graphene, and plumbene. · Phosphorene (black phosphorus). 2D chalcogenides: · Transition metal dichalcogenides (TMDCs) such as MoS2, WS2, MoSe2, and WSe2. Layered semiconductors: GaSe, GaTe, InSe, Bi2Se3, etc. · 2D oxides: MnO2, WO3, TiO2, MoO3, V2O5, TaO3, RuO2, NaNbO3, α-Fe2O3, Nb2O5, Co3V2O8, Na 1.08 V3O8, etc. Layered Cu oxide. Perovskite type: methylammonium lead halide (CH3NH3PbI3), cesium lead halide (CsPbX3), Bi4Ti3O 12 , Ca2Ta2TiO 10 etc. · Hydroxides: Ni(OH)2, Eu(OH)2, ZnAl layered double hydroxides (LDH). · Maxine: Sc2C(OH)2, Sc2CO2, Ti2CO2, titanium carbide (Ti3C2).

[0173] Graphene-like materials have a lattice structure arranged in a honeycomb pattern, with atoms in the sp 2 or sp 3 It is maintained by hybridization.

[0174] The structure of phosphorene consists of sp3 hybridization of phosphorus atoms in a 2D plane. Defect-free phosphorene has a non-zero band gap and high electron mobility.

[0175] Chalcogenides are materials that contain one or more chalcogen elements (e.g., S, Se, Te) as a substantial component. TMDCs are structured so that each layer of the compound consists of three atomic planes: a layer of transition metal atoms (e.g., Mo, Ta, W) sandwiched between two layers of chalcogen atoms (e.g., S, Se, Te). Thus, in one embodiment, a TMDC is a compound of one or more of Mo, Ta, and W with one or more of S, Se, and Te. There are strong covalent bonds between atoms within each layer of a transition metal chalcogenide, and predominantly weak van der Waals bonds between adjacent layers. TMDCs can be semiconducting, metallic, and insulating. For example, semiconducting dichalcogenides are MoTe2, WTe2, ZrS2, ZrSe2, and metallic dichalcogenides include NbSe2, NbS2, TaS2, TiS2, NiSe2.

[0176] All 2D oxide compounds are composed of stacked negatively charged slab, corner- and / or edge-sharing MO6 (M = Ti, Nb, Mn, Ta, W) octahedral units, and alkali metal cations (K+, Rb+, Cs+) occupying the interlayer space. A common feature of these layered oxides is their cation exchange properties involving interlayer alkali metal ions.

[0177] M 2+ M 3+ (OH)·A n- mHO(M 2+ =Mg 2+ , Fe 2+ , 1-xx 2 x / n 2 Co2+, Ni 2+ , Zn 2+ etc. M 3+ =Al 3+ , Fe3+, Co3+, etc.) is the general formula for layered double hydroxides (LDHs). LDHs consist of octahedral brucite-like M(OH)2 layers and charge-balancing anions (An-). The host layer [M 2+ 1-x M 3+ x (OH)2] x+ is M 3+The charge density is determined by the mole fraction x (0.2≦x≦0.33). Furthermore, a new family of layered rare earth hydroxides [RE(OH) 2.5x H2O]·[A n- ] 0.5 / n (RE = Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Y) were synthesized and [RE 3+ (OH) 2.5x H2O] 0.5+ A positively charged layer of and a charge-balancing anion, A, sandwiched between the layers. n- , (Cl, NO3, etc.).

[0178] 2D perovskite is (A') m A n-1 B n X 3n+1 where A' is the inorganic A n-1 B n X 3n+1 It is a cation (m=1 or 2) that is inserted between the sheets (n - the thickness of the inorganic layer).

[0179] Materials belonging to the Maxine group are layered transition metal carbides and carbonitrides. n+1 X n T x where M represents an early transition metal, X represents carbon and / or nitrogen, and T x represents a surface termination (mainly =O, -OH, or -F), and n is usually 1 to 4. Maxine has high conductivity (10,000 to 1,500 Scm -1 ) in combination with a solvent-tunable hydrophilic surface. They are synthesized by removing a monolayer "A" from the ceramic precursor MAX phase (where M represents Ti, Mo, W, Nb, Zr, Hf, V, Cr, Ta, Sc; A represents Al, Si; and X represents C, N).

[0180] TMDCs are structured so that each layer of the compound consists of three atomic planes: a layer of transition metal atoms (e.g., Mo, Ta, W) sandwiched between two layers of chalcogen atoms (e.g., S, Se, Te). Thus, in one embodiment, a TMDC is a compound of one or more of Mo, Ta, and W with one or more of S, Se, and Te. There are strong covalent bonds between atoms within each layer of the transition metal chalcogenide, and predominantly weak van der Waals bonds between adjacent layers. Exemplary TMDCs include NbSe2, WS2, MoS2, TaS2, PtTe2, and VTe2.

[0181] The term "substantially insoluble" in the context of the present invention means that at least 1000 parts by weight of solvent are required to dissolve 1 part by weight of solute at standard operating temperatures (e.g., 25°C and 1 atmosphere pressure). The term "insoluble" in the context of the present invention means that more than 10,000 parts by weight of solvent are required to dissolve 1 part by weight of solute.

[0182] The term "viscosity" in the context of the present invention refers to the viscosity at a temperature of 20°C for 10 seconds. -1 refers to the kinematic viscosity measured at a shear rate of 100 MPa.

[0183] Throughout this description and claims, the words "comprise" and "contain" and variations thereof mean "including but not limited to" and are not intended to, and do not, exclude other moieties, additives, components, integers, or steps. Throughout this description and claims, the singular encompasses the plural unless the context requires otherwise. In particular, where the indefinite article is used, it is to be understood that the specification contemplates the plural as well as the singular, unless the context requires otherwise.

[0184] It is to be understood that any feature, integer, property, compound, chemical moiety, or group described in connection with a particular aspect, embodiment, or example of the invention may be applied to any other aspect, embodiment, or example described herein, unless incompatible therewith. All features disclosed in this specification (including the accompanying claims, abstract, and drawings), and / or all method or process steps so disclosed, may be combined in any combination, except combinations in which at least some of such features and / or steps are mutually exclusive. The invention is not limited to the details of the foregoing embodiments. The invention extends to any novel or novel combination of features disclosed in this specification (including the accompanying claims, abstract, and drawings), or any novel or novel combination of method or process steps so disclosed.

[0185] The reader's attention is directed to all articles and documents related to this application, filed contemporaneously with or prior to this specification, and open to public inspection herewith, the contents of all such documents and documents being incorporated herein by reference. [Example]

[0186] Example 1 - Investigation of the stability of graphene in MeOH vs. NMP background Graphene flakes are known to be difficult to disperse in most solvents. The method of the present invention provides a way to disperse graphene in a graphene-loving solvent, such as NMP, and then form a composite and perform a solvent exchange operation to replace the NMP with another solvent that is easier to handle or remove.

[0187] In this experiment, we directly investigate the relative stability of graphene in alcohol, methanol (MeOH), and NMP (N-methyl-2-pyrrolidone), by measuring UV / Vis absorbance at 660 nm.

[0188] experiment Graphene (G1 Sigma, Levidian) was added to either MeOH or NMP at a loading of 10 g / L. The mixture was subjected to shear mixing at 10k RPM using an IKA Ultra Terrax T25 high-shear mixer equipped with an 18 mm high shear mixing head. To avoid heating and evaporation of the solvent, the solution was kept at room temperature (reference 20 degrees Celsius) during shearing using a water jacket. For measurements, shearing was paused, and a 10 μL aliquot was removed and diluted 300-fold with the respective solvent before measuring the UV-Vis absorbance.

[0189] The data (shown in Figure 1) indicated that the absorbance of the MeOH dispersion was approximately half that of the NMP solution. It is unlikely that the low absorbance was due to low graphene concentration. UV-vis measurements are based on the Beer-Lambert law, which states that the absorbance of a solution is directly proportional to the concentration and path length of the absorbing species in the solution. Therefore, discrepancies between the actual and UV-vis determined concentrations could result from a lack of uniform distribution of the absorbing species within a given volume or their physical / chemical changes. In this case, the discrepancy could be due to graphene aggregates / aggregates, which is consistent with the known behavior of the relative dispersibility of graphene in MeOH and NMP. The absorbance data are shown in Table 1 below.

[0190] JPEG2026504696000004.jpg33170

[0191] Example 2 - Demonstrating PVDF Precipitation in the PVDF Process by Inference background This experiment demonstrates that 1) the binder is responsible for the complexation and 2) the binder is responsible for the formation of dissolved, discrete particles containing graphene, active material, and binder. Recording the height of the settled solids is a method used to indicate that the particles are physically attached, because physically attached particles of this type stack less efficiently than unattached particles. This height of the settled solids is reported as the "apparent reduction in the volume occupied by the particles in the slurry" in percent using the calculation: 100 × (height in the container occupied by the settled solids) divided by (initial height in the container). In this calculation, a higher number indicates better particle stacking, because it represents a greater "reduction" in the volume occupied by the particles. An image showing the settled particle layer is reported in Figure 2. The UV-vis transmittance at 660 nm collected from the supernatant liquid above the settled solids is a method used to indicate the "graphene concentration." However, the relationship of UV-vis (reported as the notation for each measurement in the bar graph in Figure 1) to graphene concentration is such that the graphene concentration is -1 cm -1 This study relies on the assumption that UV-vis absorbance is related to the Beer-Lambert law. This assumes that only graphene is in the supernatant. However, UV-vis readings strongly indicate solids suspended in the liquid, e.g., unincorporated solids at the bottom of the container. As reported in Figure 1, the UV-vis reported from the "no binder" and "graphene only" samples was recorded from supernatants diluted 8- and 10-fold, respectively, due to the high absorbance of the supernatants of these samples. These dilutions were performed because readings from very high absorbance samples are likely to be inaccurate. In this example, LTO and graphene are used as illustrative materials because they are clearly distinguishable in optical images, helping to trivialize inferences about their behavior through optical analysis of the suspension. In Figure 1, graphene is labeled "carbon."

[0192] experiment Graphene pre-dispersed in NMP was obtained from Sixonia GmbH, powdered LTO from Targray (LTO-2S powder), and PVDF from Thermo Fisher (product code 044080.A3). In this experiment, a nominal ratio of 2:4:94 graphene:PVDF:LTO was required for further mixing with NMP as needed to achieve a solids concentration of 125 g / L and a corresponding graphene concentration of 2.5 g / L. The theoretical maximum solids content of 80 ml of this mixture is 10 g. A set of samples was created by omitting one or more components as indicated, while keeping all other components the same.

[0193] The mixture of solids was rapidly stirred in a beaker with magnetic stirring for 1 hour, after which methanol was rapidly added in a 4:1 volume ratio of MeOH:NMP to give 400 ml of solution, which was stirred for an additional 15 minutes and then allowed to settle for 1 hour.

[0194] Images of the settled solution indicate the level of complexation, and UV-Vis of the supernatant indicates the degree of graphene (Gr) present. The results are detailed in Figure 1 and Table 2 below.

[0195] JPEG2026504696000005.jpg255169JPEG2026504696000006.jpg84170

Claims

1. 1. A method of making a composite material comprising an electrode active material, a polymeric binder, and a conductive material, comprising: i. providing a first dispersion comprising a dispersion solvent and a polymeric binder dissolved therein; ii. Providing a poor solvent in which the polymeric binder is substantially insoluble, at least one of the first dispersion and the poor solvent contains an active material dispersed therein, and at least one of the first dispersion and the poor solvent contains a conductive material dispersed therein; based on the total weight of the active material, conductive material, and polymer binder, the active material is present in an amount of 80 to 99.5 wt. %; the conductive material is present in an amount of 0.01 to 15 wt. %; the polymeric binder material is present in an amount of 0.01 to 15 wt. %; iii. contacting the first dispersion with the anti-solvent to form a suspension mixture, wherein the volume ratio of the dispersion solvent to the anti-solvent is from 1:1 to 1:10; contacting the first dispersion with the anti-solvent results in precipitation of the binder in the presence of the active material and conductive material to form a composite material; A method comprising:

2. The method of claim 1 wherein there is an excess of anti-solvent relative to the dispersion solvent.

3. 3. The method of claim 1 or claim 2, wherein the volume ratio of the dispersion solvent to the anti-solvent is from 1:1 to 1:5, such as from 1:1 to 1:4, and optionally the volume ratio of the dispersion solvent to the anti-solvent is from 1:1.5 to 1:

3.

4. 10. The method of any one of the preceding claims, wherein the dispersion solvent comprises a solvent selected from NMP, DMSO, silane or mixtures thereof, optionally wherein the dispersion solvent is NMP.

5. 10. The method of any one of the preceding claims, wherein the anti-solvent comprises one or more of methanol, water, acetone or mixtures thereof, optionally wherein the anti-solvent comprises up to 75% by weight of water.

6. 2. The method of claim 1, wherein the active material is a positive electrode active material.

7. The positive electrode active material is oxides, nitrides, carbides, sulfides, phosphides, and selenides of silicon, germanium, antimony, tin, lead, bismuth, zinc, aluminum, titanium, iron, nickel, manganese, cobalt, or cadmium, and mixtures thereof, or lithium-containing composites; transition metal lithium phosphates, such as lithium nickel phosphate, lithium nickel cobalt phosphate, lithium iron phosphate, mixed transition metal lithium phosphate; Lithium titanate, lithium manganate, lithium aluminate, lithium-containing titanium oxide; and NMC (lithium nickel manganese cobalt oxide) and its stoichiometric variants, for example, 910, 811, 622, 532, 111, NCA (Lithium Nickel Cobalt Aluminum Oxide) and its stoichiometric variants Lithium transition metal oxides such as; is selected from Optionally, the positive electrode active material is selected from one or more of LTO, NMC, NCA, LFP, or silicon (e.g., 300 mesh silicon chunks); 7. The method of claim 6, further optionally, wherein the cathode active material is NMC, e.g., NMC910, NMC811, NMC622, NMC532, or NMC111.

8. 10. The method of claim 1, wherein the polymeric binder is PVDF.

9. 10. The method of claim 1, wherein the conductive material comprises a conductive carbon material.

10. 10. The method of any one of the preceding claims, wherein the conductive carbon material is selected from one or more of carbon black, acetylene black, ketjen black, graphite, carbon fiber, carbon nanotubes and graphene (e.g., pristine graphene), and other hard carbons.

11. 2. The method of claim 1, wherein the conductive material comprises one or more of pristine graphene, carbon black, or carbon nanotubes.

12. 10. The method of any one of the preceding claims, further comprising drying the suspension mixture to provide a dried composite material.

13. 13. The method of claim 12, wherein the dried composite material is redispersed in a slurry solvent in an amount of at least 60 wt% solids to provide a composite slurry, the slurry solvent being selected from any one of the dispersion solvents defined in claim 4.

14. 10. The method of claim 1, further comprising removing at least a portion of the dispersing solvent and anti-solvent from the suspension mixture.

15. 15. The method of claim 14, wherein substantially all of the anti-solvent is removed and a portion of the dispersing solvent is removed.

16. 16. The method of claim 15, wherein after removal of at least a portion of the dispersing solvent and substantially all of the anti-solvent, the composite material is present in the dispersing solvent in an amount of at least 60% solids by weight.

17. 10. A method according to any one of the preceding claims, wherein the active material is present in an amount of from 85 to 99.5 wt%, preferably from 90 to 99 wt%, or more preferably from 94 to 98.5 wt%.

18. 10. A method according to any one of the preceding claims, wherein the binder is present in an amount of from 0.1 to 10% by weight, preferably from 0.5 to 6% by weight, more preferably from 1.0 to 2.5% by weight.

19. 10. A method according to any one of the preceding claims, wherein the conductive material is present in an amount of 0.1 to 10% by weight, preferably 0.5 to 6% by weight, more preferably 1.0 to 2.5% by weight.

20. A composite material obtained, obtainable or directly obtained by the method according to any one of claims 1 to 19.

21. Based on the total weight of the active material, conductive material, and polymeric binder i) a battery active material in an amount of 80 to 99.5 wt. %; ii) a polymeric binder in an amount of 0.01 to 15 wt. %; iii) a conductive material in an amount of 0.01 to 15 wt. %; Composite material including:

22. 22. A composite slurry comprising the composite material of claim 20 or 21, wherein the composite material is dispersed in a slurry solvent in an amount of at least 60% solids by weight, and the polymer binder present in the composite material is soluble in the slurry solvent.

23. a) providing a composite slurry according to claim 22; b) applying the composite slurry to a substrate; c) removing the slurry solvent after applying the composite slurry to the substrate to adhere the composite material to the surface of the substrate; A wet mixing method comprising:

24. 22. An electrode comprising the composite material of claim 20 or 21.

25. 25. A battery comprising the electrode of claim 24, optionally a lithium ion battery.

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