WO2014159118A1

WO2014159118A1 - Apparatus and methods for synthesis of battery-active materials

Info

Publication number: WO2014159118A1
Application number: PCT/US2014/022028
Authority: WO
Inventors: Lu Yang; Robert Z. Bachrach; Miaojun WANG; Dongli ZENG
Original assignee: Applied Materials, Inc.
Priority date: 2013-03-14
Filing date: 2014-03-07
Publication date: 2014-10-02
Also published as: TW201440884A

Abstract

A method and apparatus for forming battery active materials is disclosed. A precursor material is exposed to energy in a first energy stage, a second energy stage, and a third energy stage. Each energy stage may expose the material to thermal or non-thermal energy. A precursor material is exposed to energy in the first energy stage to dry the precursor material or partly convert the precursor material. The second energy stage converts particles to battery active material. The third energy stage anneals the battery active material.

Description

[0001] Embodiments described herein relate to manufacturing layered lithium ion batteries. More specifically, methods and apparatus for forming battery active materials by staged processes are disclosed.

BACKGROUND

[0002] Fast-charging, high-capacity energy storage devices, such as SLipercapacitors and lithium (Li) ion batteries, are used in a growing number of applications, including portable electronics, medical devices, transportation, grid- connected large energy storage, renewable energy storage, and uninterruptible power supplies (UPS). In modern rechargeable energy storage devices, the current collector is made of an electric conductor. Examples of materials for the positive current collector (the cathode) include aluminum, stainless steel, and nickel. Examples of materials for the negative current collector (the anode) include copper (Cu), stainless steel, and nickel (Ni), Such collectors can be in the form of a foil, a film, or a thin plate, having a thickness that generally ranges from about 8 to 50 μιη.

[0003] Graphite is usually used as the active electrode material of the negative electrode and can be in the form of a lithium-intercalation meso-carbon micro beads (MCMB) powder made up of MCMBs having a diameter of approximately 10 pm. The lithium-intercalation MCMB powder is dispersed in a polymeric binder matrix. The polymers for the binder matrix are made of thermoplastic polymers including polymers with rubber elasticity. The polymeric binder serves to bind together the MCMB material powders to preclude crack formation and prevent disintegration of the MCMB powder on the surface of the current collector. The quantity of polymeric binder is in the range of 2% to 30% by weight.

[0004] The active electrode material in the positive electrode of a Li-ion battery is typically selected from lithium transition metal oxides, such as LiMn20₄, UC0G₂, Li i0₂, or combinations of Ni, Li, Mn, and Co oxides and includes electroconductive particles, such as carbon or graphite, and binder material. Such positive electrode material is considered to be a lithium-intercalation compound, in which the quantity of conductive material is in the range from 0.1 % to 15% by weight.

[0005] The lithium transition metal oxide, such as LiCoO;?, is one of the more expensive components of traditional Li-ion batteries. UC0G₂ is also toxic and can lead to problems such as runaway overheating and outgassing, making batteries that use it susceptible to fire. LiFeP0 , which does not suffer from the aforementioned deficiencies of UCQO₂, is a compound that has gained increased attention for use in Li-ion batteries. LiFeP04 batteries do not experience the overheating and outgassing problems that LiCo0₂ batteries experience, and as a result, do not require as intense charge monitoring as traditional Li-ion batteries. Further, both phosphorous and iron are abundantly available thus yielding a lower price for raw materials.

[0008J Currently favored processes of making lithium ion batteries spread a layer of paste or slurry containing the battery active material on a substrate, and then dry the material in a thermal process requiring, in some cases, several hours at high temperature in an inert or reductive atmosphere to yield a battery active material in crystal phase. As a result, these procedures often consume large amounts of both time and energy. The slurry or paste is generally made by pulverizing a solid material and mixing with a liquid phase. Particle size of the final material is typically large and widely variable, resulting in short battery life and low capacity.

[0007] Currently favored processes of making battery-active materials includes co-precipitation and solid state reaction. In the co-precipitation process, precursor solutions are mixed in a controlled manner to produce an intermediate material which is subsequently filtered, washed and dried. The intermediate material is then mixed with a lithium compound by grinding, made into pellets, and calcined. The calcined material is ground and made into pellets again for further calcination to promote homogeneity of the material. This process of pelletization, calcination, and grinding can be repeated as needed for complete solid state reaction. When the reaction is done, the materials are ground, sorted or graded if necessary, and packaged. The process is laborious, time-consuming, energy-intensive, and requires a large footprint. Thus a more cost-effective manufacturing process is desired which will reduce the cost of active battery materials significantly.

SUMMARY OF THE INVENTION

[0008] Embodiments described herein provide a method of forming a battery active material by forming a precursor solution of battery active metal salts, exposing the precursor solution to a first energy in a dryer to form an intermediate material, exposing the intermediate material to a second energy in a reactor to form a battery active material, and exposing the battery active material to a third energy in a thermal treatment stage to form an annealed battery active material. Oxygen may be provided at each stage. The precursor solution may comprise standard molar solutions of metal ions in proportions selected to produce battery active materials having a desired composition. Thermally treating the battery active material increases crystallinity of, and removes defects from, the battery active particles.

[0009] Other embodiments described herein describe an apparatus for forming battery active particles, including a precursor source, a first energy stage, a second energy stage, a third energy stage, and a collector. Each energy stage has an energy source coupled thereto, and each energy stage may be a source of thermal, radiant, microwave, RF, or chemical energy. The collector may be a cyclone, electrostatic separator, or other solids collector.

BRIEF DESCRIPTION OF THE DRAWINGS

[G010J So that the manner in which the above-recited features of the present invention can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments of this invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments.

[0011] Figure 1 is a schematic diagram of an apparatus for forming a battery- active material according to one embodiment. [0012] Figure 2 is a flow diagram summarizing a method for forming a battery- active materia! according to another embodiment.

[0013] Figure 3 is a schematic process diagram of an apparatus according to another embodiment.

[0014] To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. It is contemplated that elements disclosed in one embodiment may be beneficially utilized on other embodiments without specific recitation.

DETAILED DESCRIPTION

[0015] The methods and apparatus described herein may be used to form battery-active materials. The methods and apparatus described herein provide staged synthesis of battery-active materials from metal salt precursors, including drying, reacting, and annealing operations. Staged synthesis promotes uniformity of size and composition of particles generated in the synthesis process by providing early stages that may be used to form small nuclei that may be fully and uniformly converted to battery-active material before being over-coated with growth layers of battery-active material. Staged synthesis also provides flexibility regarding the rate at which drying and converting proceed.

[0018J Figure 1 is a schematic diagram of an apparatus 100 according to one embodiment. The apparatus 100 comprises a precursor delivery system 102 coupled to a first energy stage 108 by one or more conduits 104 for delivering a precursor mixture to the first energy stage 108. A first energy source 112 is coupled to the first energy stage 108 by a first energy conduit 1 14. The first energy source

1 12 delivers a first energy to the first energy stage 108 through the first energy conduit 1 14. The first energy is coupled into the precursor mixture in an interior volume 134 of the first energy stage 108. The precursor mixture may be dispersed by a dispersion member 106 into a dispersion pattern 110 in the interior volume 134 of the first energy stage 108 to promote intimate coupling of the first energy to the precursor mixture. The dispersion member 106 may be a nozzle, an atomizer, or a monodisperse droplet generator such as a microfluidic droplet generator, a piezoelectric generator, Rayleigh generator, electrostatic sprayer, and other hydrodynamic or electrohydrodynamic apparatus. The first energy converts the precursor mixture to an intermediate material in the first energy stage 108.

[0017] The precursor mixture is usually a solution of metal salts and optional reaction aids. The metal elements are generally metal elements that can be used to form electrochemical!y active materials, such metals including lithium, manganese, magnesium, cobalt, nickel, iron, and vanadium. Such metal elements may be combined with oxygen to form battery-active materials that are mixed metal oxides having the general structure Μ¹ _αΊ '^!: _α2...Μ^η _αηΟ, wherein "M" signifies an electrochemically active metal, as described above, and the coefficients a1 , a2, ..., an are the stoichiometric coefficients of the bulk material, per atom of oxygen "O". The other metal elements may be included as desired to provide different properties such as increased voltage, current, power performance, and/or stability.

[0018] The metal salts typically contain anions that may be reactive when properly energized. Examples of such anions are lower carboxy!ates, such as acetate, citrate, tartrate, maleate, nitrate, azide, and amide. Nitrate salts such as lithium nitrate, manganese nitrate, nickel nitrate, cobalt nitrate, and iron (II or Mi) nitrate may be used for most embodiments.

[0019] The metal salts may be dissolved in water or other polar or aqueous solvents such as alcohols, ketones, aldehydes, or carboxylic acids. The solvent enables dispersion of the precursor mixture for intimate application of energy to the precursor mixture. Polar solvents are typically used for their ability to dissolve ionic salts. If the metal salts are not dissolved in a solvent, they may be provided to the first energy stage 108 as a solid powder blown by a carrier fluid.

[0020] The precursor mixture is formed in the precursor delivery system 102, which may comprise a plurality of precursor component sources with piping and valves to mix the precursor components. The precursor mixture flows through the one or more conduits 104 to the first energy stage 108. The precursor mixture may be dispersed into the internal volume 134 of the first energy stage 108 by passing through the dispersion member 106, which may have an opening with a diameter much smaller than a diameter of the one or more conduits 104, to form the dispersion pattern 1 10 of diverging particles or droplets. The first energy stage 108 may have one or more conduits disposed within the internal volume 134 of the first energy stage 108 for passing the precursor mixture through the first energy stage 108 at least partly as a liquid.

[0021] The first energy stage 108 couples the first energy, which may be electromagnetic or thermal energy, into the precursor mixture disposed in the internal volume 134. The first energy may be electromagnetic energy such as heat energy (i.e. infrared), microwave energy, RF energy, light, UV, or a mixture thereof, or a thermal energy source such as a hot gas source or heated wall. In one embodiment, the first energy is heat generated at an outer wall of the first energy stage 108 by a resistive or conductive heat jacket disposed around the wall of the first energy stage 108. The first energy source 1 12 may be a source of thermal fluid, a source of electricity, a microwave source, an infrared source, a light source, or an RF source. In a microwave embodiment, the first energy source 1 12 is a magnetron microwave source operating at a frequency between about 300 MHz and about 6 THz, for example about 2.45 GHz. The first energy conduit 1 14 propagates the first energy from the first energy source 112 to the first energy stage 108. The first energy conduit 1 14 is selected based on the type of energy to be propagated. For example, the first energy conduit 1 14 may be any type of waveguide or conductor useful for propagating the energy from the first energy source 1 12. A metal tube may be used for propagating microwave energy, a transparent fiber for light energy, or conductive wires or cables for electric energy. The first conduit 1 14 may be a window in some embodiments, allowing the first energy to propagate into the internal volume 134 through the window.

[0022] The precursor mixture may be provided to the first energy stage 108 as a liquid flowing through the internal volume 134 of the first energy stage 108, or as a dispersed medium, such as an aerosol or droplet dispersion, within the internal volume 134. In Figure 1 , the precursor is depicted as entering the internal volume 134 as a dispersed medium according to the dispersion pattern 1 10. in an embodiment wherein the precursor mixture is provided as a liquid, one or more pipes or conduits may be disposed through the internal volume 134 of the first energy stage 108. The conduits may be coupled to a manifold on the inlet and outlet sides of the first energy stage 108. The conduits may traverse the internal volume 134 in a straight path or in a circuitous path according to specific embodiments.

[0023] The first energy couples with the precursor material disposed in the internal volume 134, causing physical and optionally chemical changes in the precursor material to form an intermediate material. Temperature of the precursor materia! is increased from an ambient temperature to an intermediate temperature, which may be between about 100°C and about 400°C. Oxygen may be provided to the internal volume 134 for reacting with metal salts in the precursor material in the form of oxygen gas (O2), air, or any other oxygen-containing gas having suitable reactivity. The reaction may take place partially in the first energy stage 108, or completely in subsequent processing, if desired. The oxygen may be dispersed throughout the internal volume 134, or may be provided through the conduits containing the precursor material, if such embodiments are used. The first energy may be provided to afford only physical changes to the precursor material, such as drying. In an embodiment in which a liquid precursor mixture is formed into particles in the first energy stage 108, the first energy stage 108 may be a dryer. The first energy may additionally facilitate at least a partial reaction between the metal salts and the oxygen. In an embodiment in which a partial reaction is performed in the first energy stage 108, the first energy stage 108 may be a first reactor. Partially reacting the metal salts with the oxygen in the first energy stage 108 may provide benefits in some embodiments by increasing the uniformity of particles produced by the apparatus 100.

[0024] The intermediate material formed in the first energy stage 108 is typically a solid comprising particles of a material that has not been converted into a battery- active material. The solid particles may have metal salts from the precursor material combined with metal-oxygen materials in domains of salts and oxides or in a pseudo-homogeneous matrix of metals, oxygen, and anions, which may adopt a crystal structure or an amorphous structure to any degree according to the specific composition of the particles.

[0025] The intermediate material is transferred from the first energy stage 108 to a second energy stage 1 16, optionally through an intermediate conduit (not shown). The intermediate material may flow with inert gases provided with the precursor material, the inert gases entraining the particles of intermediate material and transporting them to the second energy stage 1 16. The intermediate material is exposed to a second energy in the second energy stage 1 16 that may be the same as the first energy or different from the first energy. The second energy may be thermal energy or electromagnetic energy such as light, microwave energy, or RF energy, and is provided by a second energy source 1 18 coupled to the second energy stage 1 16 by a second energy conduit 120. Similar to the first energy conduit 1 14, the second energy conduit 120 is selected based on the type of energy to be propagated from the second energy source 1 18 to an internal volume 136 of the second energy stage 1 16.

[0026] The second energy source 118 may also be a source of electromagnetic energy such as heat, light, UV, RF, or microwave, or a source of thermal energy, such as a hot gas source, a hot fluid source, or a source of electricity. The second energy source may be a DC source coupled to a resistive heat jacket disposed around a wall of the second energy stage 116. In another embodiment, the second energy source 1 18 may be a magnetron microwave source operating at a frequency between about 300 MHz and about 6 THz, and the second energy conduit 120 may be a wave guide such as a metal tube or square or rectangular metal duct. In another embodiment, the second energy source 1 18 may be a source of electricity, such as an RF source, and the second energy conduit 120 may be an electrical conductor that couples the electricity to the second energy stage 1 16.

[0027] In one embodiment, the second energy stage 1 16 may be a reactor that converts the particles of the intermediate material from the first energy stage 108 into particles of battery active material, in such an embodiment, the intermediate material flows through the energy field in the second energy stage 1 16, and is converted to a battery active material before exiting the second energy stage 1 16. The second energy stage 1 16 heats the particles to a temperature between about 900°C and about 1 ,G0G°C to activate reaction of the metals with oxygen, along with other reactions involving the other precursors and additives that may be present. The particles emerging from the second energy stage 1 16 may be porous and may have a microcrystalline morphology.

[0028] Oxygen may be added to the second energy stage 1 16 independently from the first energy stage 108, or oxygen not consumed in the first energy stage 108 may be flowed into the second energy stage 116. The oxygen may be added as oxygen gas (O2), air, or other suitable oxygen containing gas. Oxygen combines with the particles of the intermediate material that flow into the second energy stage 1 16 from the first energy stage 108 to form particles of a battery-active material.

[0029] The size and size distribution of particles formed in the second energy stage 1 16 is influenced by the size and size distribution of droplets formed by the dispersion member 106. Particle size using an atomizer, for example, may be between about 1 pm and about 10 μηι, such as between about 2 μιπ and about 5 m. Standard deviation of particle size normalized to average particle size is typically between about 50% and about 500%, depending on the type of dispersion member 106 used. Atomizers will produce a larger standard deviation of particle size while monodisperse droplet generators will produce a smaller standard deviation of particle size.

[0030] The battery-active particles formed in the second energy stage 1 16 flow out of the second energy stage 1 16 into a third energy stage 122. Like the first energy stage 108 and the second energy stage 1 16, the third energy stage 122 is coupled to a third energy source 124 by a third conduit 126. The third energy source 124 and third conduit 126 may be the same as, or different from, the first energy source 1 12 and first energy conduit 114 and the second energy source 1 18 and second conduit 120.

[0031] In the third energy stage 122, the particles of battery-active material formed in the second energy stage 1 16 are subjected to a thermal treatment that reorganizes the structure of the particles, increasing the crystallinity of the particles, coalescing adhesion domains within the particles to prevent fragmentation, and removing defects. In some cases, the thermally treated particles emerging from the third energy stage 122 may be single-crystal particles. The thermal treatment may be an annealing operation or a calcining operation, and is typically performed in the presence of oxygen, which may be added to the third energy stage 122 or flowed from the second energy stage 1 16 to the third energy stage 122. In the third energy stage 122, the particles are typically heated to a temperature between about 1 ,000°C and about 1 ,400°C, such as between about 1 ,000°C and about 1 ,100°C, for example about 1 ,050°C. Residence time in the third energy stage 122 may be between about 1 minute and about 60 minutes, such as between about 5 minutes and about 30 minutes, for example about 30 minutes. The third energy stage 122 may be a rotary kiln or a fluidized bed.

[0032] The particles may optionally be coated in the third energy stage 122 or between the second energy stage 116 and the third energy stage 122 by providing a coating precursor to the gas carrying the particles. A thin ceramic coating may be applied to the particles in the third energy stage by providing a precursor such as a metal alkyl, such as trimethyl aluminum, to the third energy stage. The metal alkyl reacts with oxygen at the particle surface to form a thin ceramic coating around the particles.

[0033] The annealed particles from the third energy stage 122 may flow to a collector 130, in which the particles are separated from the flowing gas stream that carries the particles to the collector 130. The collector 130 discharges the particles in a powder that may be packaged or otherwise arranged for transport. The collector 130 may be a cyclone, an electrostatic precipitator, or other solids collecting apparatus. The powder may also be provided to a coating process (not shown) in which the powder may be deposited on a substrate to form a battery layer.

[0034] Each of the energy sources 1 12, 1 16, and 124 may be, independently, a source of thermal, radiant, microwave, chemical, or RF energy. A source of thermal energy may be an electricity source coupled to a resistive heating jacket surrounding the respective energy stage, or a thermal fluid source coupled to a conductive heating jack surrounding the respective energy source. A source of radiant energy may be an assembly of heat lamps positioned to radiate IR energy through a waveguide. A microwave source may be coupled to a respective energy stage through a microwave waveguide. A source of chemical energy may be a combustible gas mixture ignited and directed to impinge on a respective energy stage (for example, a furnace). A source of RF energy may be a pair of electrodes disposed on opposite sides of an energy stage, with at least one powered by RF energy, or a coil or loop disposed around the energy stage and powered by RF energy to provide inductive coupling.

[0035] In some embodiments, the various energy stages may be thermally integrated by recycling hot gases among the energy stages. For example, a portion of the gas from the third energy stage 122 may be flowed to the second energy stage 1 16 while minimizing heat loss from the gas. In this way, heat rejected from the third energy stage 122 may be used in the second energy stage 1 16. Likewise, a portion of the gas from the second energy stage 1 16 may be flowed to the first energy stage 108. The recycled gas may be added before each respective energy stage to preheat the particles flowing into the stage, if desired. For example, the gas recycled from the third energy stage 122 may be added to the particle stream flowing from the second energy stage 1 16 into the third energy stage 122 Likewise, the gas recycled from the second energy stage 1 16 may be added to the precursor stream flowing into the first energy stage 108. In one embodiment, gas recycled from the second energy stage 1 16 may be used to atomize the precursor liquid flowing through the dispersion member 106. In this way, the apparatus 100 may be substantially heat-integrated.

[003S] The precursor material used with the apparatus of Figure 1 may be a solid, such as a powder, or a liquid, such as a solution, dispersion, suspension, emulsion, or colloid. Metal salts are generally salts of lithium, cobalt, iron, nickel, manganese, magnesium, and may have anions that are organic or inorganic. For example, nitrates, carbonates, sulfates, phosphates, and/or silicates may be used as inorganic salts, while acetates, formates, citrates, tartrates, benzoates, maleates, azides, amides, and other lower carboxylates, may be used as organic anions. Such anions, when exposed to sufficient energy, contribute to the formation of a battery active material by decomposing and reacting with metals and other components, releasing chemical potential energy and facilitating the ongoing reaction. Additives may also be used to facilitate the reaction by coordinating with metal species to lower the decomposition energy thereof, by reducing the reaction energy barrier, by adding energy to the reaction, and by adding carbon to the resulting battery active material to improve electrical properties such as conductivity. Additives may also help adjust dispersion properties by affecting density, viscosity, and surface energy of the precursor. Favorable dispersion of the precursor material may improve porosity and particle size and distribution to optimize capacity and power performance. Alcohols, such as glycols, and sugars may perform all of the above functions in some embodiments. Nitrogen containing organics, such as glycines or ureas, may also be used for many of the above properties.

[0037] The precursor mixture contains metal ions, which may be coordinated or bonded with anions in a solid material dispersed in a gas or liquid dispersion phase, or dissolved, dispersed, coordinated, or suspended in a liquid, which may be a solvent. Reactive anions may be suspended or dissolved along with the metal ions, and may include inorganic or organic species. Examples of inorganic reactive anions include sulfates, carbonates, nitrates, phosphates, and silicates. Examples of organic reactive anions include formates, acetates, citrates, tartrates, butyrates, maleates, benzoates azides, amides, and other lower carboxylates.

[0038] Solvents which are used in some embodiments include polar solvents such as water and various alcohols, for example glycols including ethylene glycol and propylene glycol, or lower alcohols such as methanol, ethanol, and isopropanol, or phenols. Other polar solvents that may be used include carboxylic acids such as formic acid and acetic acid, ketones such as acetone, methyl ethyl ketone, diethyl ketone, and methyl isobutyi ketone, aldehydes such as propionaldehyde and formaldehyde, ethers such as MTBE or diethyl ether, esters such as ethyl acetate vinyl acetate, and other solvents such as tetrahydrofuran, acetonitrile, dimethy!formamide, or dimethylsulfoxide. Most of the polar solvents will typically dissociate the metal ions from their anions to form a solution. Non-polar solvents may also be used in addition to, or instead of, polar solvents. When used in addition to polar solvents, non-polar solvents are typically added up to a miscibility limit, so that the ionic nature of the solution is preserved. In some cases, non-polar solvents may be included beyond the miscibility limit as an emulsion, or may even be used to form a colloid or solid suspension of metal ions as solids.

[0039] Additives may be included with the precursor mixture to add chemical potential energy to the mixture, to reduce the energy required to decompose the metal species, and/or to adjust fluid properties such as viscosity and surface energy for dispersion or particulation performance. Additives such as amines, or other nitrogen containing compounds, may serve as fuels to add energy to the reaction. Exemplary nitrogen containing compounds include glycine and urea, or derivatives thereof. Additives containing carbon may be additionally useful to add carbon to the final battery active material to improve the electrical properties thereof. Carbon containing species provided in excess of carbon-reactive species, such as oxygen, nitrogen, and hydrogen, may form amorphous particles in the reaction that cluster around particles of battery active material, improving carrier mobility within the battery active material.

[0040] As described above, a gas or gas mixture may be provided with the precursor material to aid in dispersion. The gas may be inert, for example nitrogen gas or argon, or may be reactive or contain a reactive component. For example, the gas may contain oxygen or air to drive a combustion or oxidation reaction, which will add energy to the reaction mixture to facilitate conversion of the metal ions into a battery active material. The gas may also contain a fuel, such as propane or natural gas, to further such a combustion reaction.

[0041] Figure 2 is a flow diagram summarizing a method 200 according to another embodiment. The method 200 may be practiced using the apparatus described in connection with Figure 1 above.

[0042] An electrochemical precursor mixture is provided to a drying chamber at 202. The mixture may be dispersed into the chamber or flowed into the chamber. In one embodiment, the mixture is atomized into the drying chamber. A gas or gas mixture may be included with the precursor mixture to aid in dispersion. The gas may be inert, reactive, or a mixture of inert and reactive components. Usable inert gases include nitrogen gas, argon, and carbon dioxide. Reactive gases include hydrocarbons such as methane, natural gas, ethane, propane, butane, and the like, with air or oxygen.

[0043] In one embodiment, standard molar solutions of metal nitrates are mixed to form the electrochemical precursor. Lithium nitrate is usually included. Lithium nitrate is typically provided in slight excess because some lithium may be lost during high temperature processing to form battery active materials. The lithium may be in excess by 5-15%, such as 5-10%, for example about 10%, above an amount of lithium desired in the final battery active material. This may be achieved by using a lithium nitrate solution of molarity 5-15% above the molarity of the other nitrate solutions used to make the electrochemical precursor. For example, a 2.2 M lithium nitrate solution may be blended with a 2 M manganese nitrate solution, a 2 M nickel nitrate solution, and a 2 M cobalt nitrate solution to form the electrochemical precursor. Any of the additives and reaction aids described above may also be included in the electrochemical precursor.

[0044] The electrochemical precursor is exposed to a first energy in the drying chamber to form an intermediate material. Liquid in the precursor is mostly or completely evaporated, so that the intermediate material is substantially dry, with only at most a residual amount of moisture remaining. The intermediate material formed by exposure to energy is typically a powder, which may be formed by evaporating liquid from a dispersion of a liquid precursor or by nucleating particles in a liquid phase of the precursor material to form a suspension and evaporating liquid from the suspension. In some cases, the drying chamber may process the precursor material beyond the drying point, and may partially convert precursors into battery active materials in the first energy stage.

[0045] A temperature of the precursor material is typically increased in the drying chamber to between about 300°C and about 700°C, such as between about 350°C and about 500°C, for example about 400°C. Residence time in the drying chamber may be adjusted to achieve a desired level of dryness or to partially convert metal sons to battery active materials. Typical residence time in the drying chamber is between about 1 sec and about 10 minutes. In some cases, partially converting metal ions to a battery active material in the drying chamber may offer benefits in balancing the various chemical and physical processes in the process. For example, a partial conversion in the drying chamber may allow for solvent in the center of a particle some time to diffuse to the particle surface before the surface is fully converted to a battery active material, increasing the chance that the entire particle will uniformly convert to battery active material in the second energy chamber, described below. In other embodiments, the nucleation of battery active particles in the precursor material to form a liquid intermediate material having a dispersion of battery active particles may improve the uniformity of the final powder by ensuring a fully converted core In each particle around which the rest of the particle eventually forms in subsequent operations.

[0048] The intermediate material is transferred to a reactor at 204. This may be accomplished by flowing of gas through a conduit coupling the drying chamber to the reactor, if the intermediate material is solid, the intermediate material may be fluidized in a gas medium, which may be heated if desired to enhance drying prior to entry to the reactor. In some embodiments, the intermediate material is entrained in an exhaust gas from the drying chamber, which may be partially or fully evacuated to remove excess condensibles and enhance drying. The reactor is similar to the drying chamber in that an enclosure is coupled to an energy source, which may be any of the energy sources described elsewhere herein, and the coupling may be according to any of the means described elsewhere herein.

[0047] Oxygen is typically included in the gas mixture carrying the intermediate material to the reactor. The oxygen may be added to the intermediate material between the drying chamber and the reactor, or sufficient oxygen may be present in the effluent of the drying chamber. A temperature of the intermediate material is typically increased in the reactor to between about 800°C and about 1 ,500°C, for example between about 1 ,000°C and about 1 ,200°C, depending on the type of energy used and the residence time. Residence time in the reactor may be between about 1 second and about 60 minutes. Multiple reactors may be operated in parallel to convert the intermediate material to battery active material.. [0048] The battery active material formed in the reactor is typically a crystalline solid composed of particles having a size from about 0.1 μηπ to about 10 μιη, for example from about 2 m to about 5 μπΊ. Standard deviation of particle size, normalized to average particle size, is typically between about 50% and about 500%, depending on the type of process used. The particles may be mixed metal oxides including, for exampie, lithium ions, manganese ions, nickei ions, and cobait ions, along with oxygen. Proportions of the various metal ions may be controlled by adjusting the proportions of the standard molar solutions of the metal ions in the electrochemical precursor.

[0049] The battery active material formed in the reactor is transferred to an annealing chamber at 208 to form annealed battery active particles. The battery active material formed in the reactor may comprise porous particles having a microcrystalline morphology. In the annealing chamber, the particles are subjected to a temperature between about 1 ,000°C and about 1 ,400°C, such as between about 1 ,050 and about 1 ,200°, for example about 1 ,050 , for a residence time of about 1 minute to about 60 minutes, such as between about 5 minutes and about 30 minutes, for example about 30 minutes. Oxygen is typically provided, either by flowing oxygen into the battery active material flowing from the reactor, or by using excess oxygen from the reactor. The thermal treatment of the annealing chamber increases the crystallinity of the particles and removes defects from the particles. In some cases, the annealed battery active particles may be single-crystal particles.

[0050] The annealed battery active particles are collected at 208, and may be packaged or otherwise prepared for transportation. The particles may be collected using a cyclone, an electrostatic precipitator, or other solids collection apparatus. The particles may also be applied to a substrate to form a battery, if desired. In a typical process, the particles are sprayed onto the substrate, optionally with a binder, such as a styrenic polymer, to promote adhesion.

[0051] Figure 3 is a schematic process diagram of an apparatus 300 according to another embodiment. The apparatus 300 is generally similar to the apparatus 100 and may be used to practice the process 200. A precursor 302, which may be a mixture of precursors, is blended with a solvent stream 304, which may be water, and may include other solvents, liquid additives, and/or reaction aids described above, in a mixer 306. The mixer may be a static mixer, an in-line agitated mixer, or a mixing vessel. The solvent stream 304 may be preheated by thermally exchanging a cool solvent stream 308 with the hot contents of an exit zone 310 of a reaction stage 312 in a heat exchanger 314, which may be a solvent preheater. Mixing the precursor with the solvent stream in the mixer 308 forms a precursor solution 316, which may be stored in a precursor vessel 318.

[0052] The precursor solution 316 may be pumped by pump 320 through a filter 322 to join a dispersion feed stream 324. An oxygen-containing gas stream 326 is pressured through a filter 328 to join the dispersion feed stream 324. The two- phase liquid/gas mixture flows into a drying stage 330 and through a dispersion member 332. The oxygen-containing gas may be oxygen gas, air, or an oxygen- controlled mixture of oxygen gas, air, and/or inert gases that may include nitrogen, carbon dioxide, and/or noble gases. The oxygen-containing gas stream 326 may also contain carbon-containing compounds and nitrogen-containing compounds that may add energy to, or otherwise promote, the reaction performed in the reaction stage 312.

[0053] A drying gas 334, which may be an oxygen-containing gas, a carbon- containing gas, and/or a nitrogen-containing gas, for example air, optionally with oxygen gas and/or inert gases such as nitrogen, carbon dioxide, and/or noble gases, may be filtered through a filter 336 and heated in a furnace 338, or other gas heating means, and provided to a gas distributor 340 in the drying stage 330. The drying gas flows into the drying stage 330 in a substantially axial direction, as indicated by arrows 342. The dispersion member 332 of Figure 3 is depicted as a collection of tubes, pipes, or nozzles that disperse, for example atomize, the dispersion feed stream 324 in a direction counter to the flow direction of the drying gas 334. In this way, the drying stage 330 of Figure 3 is depicted as a counter-current operation. In other embodiments, the drying stage 330 may be a co-current operation with the dispersion member 332 dispersing material along the flow direction of the drying gas 334. The drying stage 330 may also be a vortex dryer if the drying gas 334, the dispersion member 332, or both impart a rotary motion to the material flowing through the drying stage 330. For example, the dispersion member 332 may disperse material in a circumferential manner within the drying stage 330 to impart a rotational motion, if desired.

[0054] Liquid is substantially removed, for example by evaporation or partial conversion, in the drying stage 330 to form particles entrained in a gas. The particles are typically a mixed composition of metals with oxygen, and potentially nitrogen, carbon, and hydrogen. The particles may have a complex structure that may be amorphous or crystalline to varying degrees, depending on the precise thermal history imparted in the drying stage 330. if the particles are dried with more intensity in the drying stage 330, some partial conversion to battery-active material may be accomplished, and some parts of the particles may have a defined crystal structure. As explained above in connection with the apparatus 100 and the method 200, particles are typically heated to a temperature of at least about 300^oC, for example about 400°C, in the drying stage 330.

[0055] The dried particles flow into the reaction stage 312 for conversion to battery-active material. The reaction stage 312 has a wall heater 344, which may be a resistive heat jacket operated electrically or a conductive heat jacket through which steam or another hot fluid, such as hot oil or a hot combustion exhaust gas or hot nitrogen gas, is circulated. The reaction stage 312 raises the temperature of the particles to at least about 900°C, such as between about 900°C and about 1 ,500°C, for example about 1 ,000°C or 1 ,050°C. The particles react with oxygen in the gas to convert to battery-active material. Side reactions of nitrogen, carbon, hydrogen, oxygen, and the metals may also add energy to the overall reaction environment to reduce the need for physical heat input by the wall heater 344. The reaction stage 312 may include reaction zones 348, which may be parallel reactors, and may be defined by tubes 348, that help normalize flow of particles through the reaction stage 312. Distribution of residence time among the particles is reduced, and uniformity of processing improved, resulting in improved uniformity of size, composition, and morphology of battery-active particles.

[0056] The hot gas and particles from the reaction stage 312 flow through the exit zone, exchange heat with the cool solvent stream 308 as described above, and enter a classifier 350. The hot gas and particles may flow through a conduit 352, which may be insulated or heated if desired to maintain temperature of the hot gas and particles. The classifier 350 may be a cyclone or other particle separator. Larger particles are passed to a vessel 354, while smaller particles are passed to a collector 356 and collected in a second vessel 358. Waste gas is removed at 360.

[0057] The particles collected in the vessels 354/358 are provided to respective annealers 382/364. In the annealers 362/364, the particles are subject to a residence time at high temperature, as described above in connection with Figures 1 and 2, to increase crystallinity and remove defects from the particles. Mechanical strength of the particles is also improved by the annealing operation. An oxygen- containing gas 366/368 is provided to each annealer 382/364 and heated in heaters 370/372 to promote a high temperature environment in the annealers 382.364. A product stream 374/376 is withdrawn from each annealer 362/384, from which the final annealed battery-active particles may be collected for packaging and/or transportation or for deposition on a substrate to make a battery.

[0058] Battery-active particles made using methods and apparatus described herein typically have size between about 0.1 m and 100 μιτι, with size variation from the average that is typically no more than about 50%. The particles are substantially free of aggregates. The particles typically contain lithium ions and other metals with oxygen-containing anions such as oxygen itself or phosphate. The most common materials are lithium-nickel-manganese-cobalt oxides, referred to as NMC, materials where the ratio of lithium atoms (ions) to oxygen atoms (ions) is from about 0.45 to about 0.75, typically around 0.5, and the ratio of each of the other metals, nickel, manganese, and cobalt, to lithium is between about 0 and about 1 . The particles have a morphology stable to a crush pressure up to about 10 tons/sq- cm which will enable higher electrode density for lithium ion batteries.

[0059] While the foregoing is directed to embodiments of the invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof.

Claims

What is claimed is:

1 . An apparatus for forming a battery-active material, comprising:

a liquid precursor source;

a dispersion member coupled to the liquid precursor source;

a dryer coupled to the dispersion member;

a reaction stage comprising a plurality of parallel reactors, the reaction stage coupled to the dryer; and

a first annealer coupled to the reaction stage,

2. The apparatus of claim 1 , further comprising a cooling stage coupled to the annealer and the liquid precursor source.

3. The apparatus of claim 1 , wherein the reaction stage further comprises a wall heater.

4. The apparatus of claim 1 , further comprising a furnace coupled to the dryer.

5. The apparatus of claim 1 , further comprising a second annealer coupled to the reaction stage.

8. The apparatus of claim 2, further comprising a furnace coupled to the dryer, wherein the dryer is a counter-current dryer and the reaction stage comprises a wall heater.

7. The apparatus of claim 3, further comprising a mixer coupled to the liquid precursor source and to a solvent source.

8. The apparatus of claim 7, further comprising a solvent preheater between the mixer and the solvent source.

9. The apparatus of claim 8, wherein the solvent preheater is coupled to an exit zone of the reaction stage.

10. The apparatus of claim 5, further comprising a classifier between the reaction stage and the first and second annealers.

1 1 . The apparatus of claim 10, further comprising a vessel between the classifier and the first annealer, and a collector and a vessel between the classifier and the second annealer.

12. An apparatus for forming a battery-active material, comprising:

a liquid precursor source;

a dispersion member coupled to the liquid precursor source;

a dryer coupled to the dispersion member;

a reaction stage comprising a plurality of parallel reactors, the reaction stage coupled to the dryer;

a first annealer coupled to the reaction stage; and

a second annealer coupled to the reaction stage in parallel with the first annealer.

13. The apparatus of claim 12, wherein the dryer is a counter-current dryer and the reaction stage comprises a wall heater.

14. The apparatus of claim 13, further comprising a mixer coupled to the liquid precursor source and a solvent source, and a heat exchanger coupled to the solvent source and an exit zone of the reaction stage.

15. The apparatus of claim 14, further comprising a classifier between the reaction stage and the first and second annealers and a collector between the classifier and the second annealer.