Method for preparing lithium nickel manganese cobalt oxide particles

Abstract

An improved method for preparing lithium nickel manganese cobalt oxide particles for use in lithium batteries and other applications is disclosed. The method includes a grinding and heating step that produces single-phase rock salt precursor particles from which lithium nickel manganese cobalt oxide particles can be readily prepared. Advantageously, the grinding step can include a dry, low-energy procedure that takes less time to prepare the precursor particles than conventional methods. Thus, the method can be simpler, faster, and reduce product contamination. Also disclosed is the optional use of novel biphasic precursor particles in the preparation method.

Description

[Technical field]

[0001] FIELD OF THE DISCLOSURE Embodiments disclosed herein relate to improved methods for preparing lithium nickel manganese cobalt oxide particles. The prepared lithium nickel manganese cobalt oxide particles are useful as electrode materials for lithium batteries and other applications. [Background technology]

[0002] The development of rechargeable high energy density batteries, such as Li-ion batteries, is of great technological importance. Typically, commercially available rechargeable Li-ion batteries use lithium transition metal oxide cathodes and graphite anodes. Although batteries based on such materials are approaching the theoretical energy density limits, significant research and development continues to improve other important properties, such as cycle life, efficiency, and cost. Furthermore, significant research and development continues to be done to simplify the manufacturing process and reduce the associated complexity, material amounts, and losses.

[0003] Transition metal oxide cathode materials that are insertion compounds used in lithium rechargeable batteries typically contain lithium, one or more of Ni, Mn or Co, oxygen, and optional metal dopants (e.g., Mg, Al, Ti, Zr, W, Zn, Mo, K, Na, Si, Ta), and such materials can further include other materials (e.g., Al 2 O 3 , ZrO 2 , TiO 2 ) for ease of manufacture. Air-stable types of transition metal oxides are usually employed. Given the large demand for these batteries, it is very important to have large and economical supplies of such materials. Currently, lithium nickel manganese cobalt oxide particles (LiNMC), known commercially as "NMC", are the preferred cathode material for commercial Li-ion batteries.

[0004] "NMC" type materials for use as cathodes in Li-ion batteries can have an O3 layered structure and have the actual general formula Li 1+x [(Ni n Mn m Co c ) 1-a A a ] 1-x O 2 where -0.03≦x≦0.06, n+m+c=1, n≧0.05, m≧0.05, c≧0.05, A is a metal dopant, and 0≦a≦0.05. Particularly desirable in some applications is a single crystal LiNMC lithium transition metal oxide particle material, abbreviated as SC-LiNMC and also known as monolithic "NMC", whose average LiNMC grain size is greater than 1 μm. In some embodiments, the SC-LiNMC particles can be composed of multiple LiNMC grains. In preferred embodiments, the SC-LiNMC particles can each be composed of a single LiNMC grain. In some embodiments, the SC-LiNMC particles can each be composed of multiple LiNMC grains, with the average "NMC" grain size being greater than 20% of the average grain size. In some embodiments of SC-LiNMC, the average grain size (D50) is between 1 μm and 20 μm.

[0005] The method for preparing LiNMC (including SC-LiNMC) is to first prepare mixed metal hydroxide (MMH) or mixed metal carbonate (MMC) precursor particles of Ni, Mn, Co, and optional metal dopant A in respective proportions depending on the desired final LiNMC composition. The MMH or MMC precursor particles are prepared by co-precipitation of metal salts in aqueous solution, followed by a process of filtration, drying, and grinding. The resulting MMH or MMC precursor particles are then mixed with a lithium source (e.g., LiOH, LiOH·H), typically in an amount greater than the desired LiNMC composition. 2 O or Li 2 CO 3) to form a mixture. The mixture is then sintered in air at a temperature ranging from 600 to 1000 °C. A description of the synthesis of LiNMC by this method can be found in Journal of The Electrochemical Society, 165(5)A1038-A1045 (2018). A two-step heating method can also be employed, as described in WO 2019 / 185349. This method can be used because the co-precipitation method produces precursor particles of MMH or MMC with particle sizes greater than 100 nm. Smaller particle sizes lead to problems in handling dust and particles, which increases processing costs. Furthermore, the co-precipitation method can be used because it achieves atomic-scale mixing of the transition metals in the MMH or MMC. Atomic-scale mixing is desirable because transition metals diffuse slowly during sintering, which can lead to the formation of unwanted impurity phases in the LiNMC formed after sintering. Therefore, if atomic mixing is not achieved in the MMH or MMC, long sintering times may be required to convert the MMH or MMC precursor particles to the desired single-phase LiNMC, which can increase costs. Losses of lithium through evaporation also commonly occur during the sintering process, making long sintering times undesirable. Co-precipitation methods also require many steps and can generate large amounts of wastewater. Furthermore, co-precipitation methods require the source of the transition metals to be soluble metal salts, which can be more expensive than insoluble sources of these metals, such as metal oxides, metal hydroxides, and metal carbonate compounds.

[0006] A method for making "NMC" is described in U.S. Patent No. 7,211,237, in which oxides or oxide precursors containing cobalt, manganese, nickel, and lithium are wet-milled together to form a precursor. The precursor is then heated to produce "NMC". This method also has the disadvantage of using water, which must be removed by drying before or during the heating step.

[0007] The Journal of The Electrochemical Society, 159(9)A1543~A1550(2012) 3 ) 2 6H 2 O,Mn(NO 3 ) 2 4H 2 O and Co(NO 3 ) 2 6H 2 O was ball milled together with LiNO 3 and LiCl, then heated to obtain SC-Li 1+0.14 (Ni 0.33 Mn 0.33 Co 0.33 ) 0.86 O 2 A method for producing SCLiNMC particles is described. In this method, LiCl and KCl components are present to form a molten salt, which must be removed by washing after the heating step to obtain SCLiNMC particles. This method requires many steps and can generate a large amount of wastewater.

[0008] As stated in Linden's Handbook of Batteries, 4th Edition, McGraw-Hill Edition (2010), "NMC and NCA materials rely on a homogeneous and uniform distribution of cations in the transition metal layers of the structure. The most common way to ensure this is to use mixed transition metal hydroxide or mixed transition metal carbonate precursors in which the cations are thoroughly mixed on the atomic scale." A useful method of synthesizing such precursors is by co-precipitation. Solid-state reactions have been proposed as an economical method for producing "NMC" lithium transition metal oxide particle materials, in which the precursor is ground and sintered without the co-precipitation step. However, solid-state reactions typically result in non-uniform elemental distribution and small particle size in the lithium transition metal oxide particles, both of which have a detrimental effect on electrochemical performance. Thus, solid-state synthesis methods are generally considered unsuitable as practical synthesis methods for "NMC". For example, the following two citations are noteworthy regarding the solid-state synthesis of "NMC".

[0009] Nano Energy, 31 pp. 247-257 (2017): "Compared with the co-precipitation method, solid-state synthesis is expected to reduce costs and shorten the synthesis time. However, the main disadvantage of solid-state synthesis is the difficulty in controlling the segregation of transition metal elements at the primary particle level, which in turn significantly affects the electrochemical performance of the final cathode material."

[0010] Chemistry of Materials, 29 9923-9936 (2017): "Li-rich layered compounds with various morphologies can be prepared by a wide variety of synthetic routes, including solid-state, molten salt, hydrothermal, and sol-gel, as well as co-precipitation in aqueous media followed by high-temperature synthesis. Among the various possible techniques, the solution-based co-precipitation method (or aqueous sol-gel method) is more practical because it allows atomic-level mixing of the transition metal ions and results in uniformity of the final oxide."

[0011] U.S. Provisional Patent Application Nos. 62 / 893787 and 62 / 946938, both filed on August 29, 2019 and December 11, 2019, respectively, are both by the same applicant and both are entitled "Improved Microgranulation Method and Product Particles Obtained Therefrom," and disclosed in the Examples certain NMC precursor particles prepared using an all-solid-state method. The contents of these two U.S. Provisional Patent Applications are incorporated herein by reference in their entireties.

[0012] The Journal of The Electrochemical Society, (167) 050501 (2020) reported that Ni was synthesized by colloidal synthesis using transition metal acetates. 0.25 Mn 0.25 Co 0.5 The method for preparing O precursor particles is described. 0.25 Mn 0.25 Co 0.5The O precursor particles were nanocrystalline and had a single-phase rock-salt structure. Precursor particles with a single-phase rock-salt structure are desirable in the synthesis of LiNMC because they contain the transition metals in an atomically mixed solid solution. However, the synthesis described in this reference involves the use of a solvent. The precursor particles formed by this method and produced had broad XRD diffraction peaks, which may indicate compositional variation between particles or within the particles themselves.

[0013] US Patent No. 10,651,467 (B2) describes a method for synthesizing precursors for the preparation of the spinel phase Li-Ni-Mn-O. The preparation of the precursor includes ball milling the starting materials followed by heating under a reducing atmosphere. The precursor produced may include a rock salt phase. The starting materials include metal oxides, metal nitrates, metal sulfates, and metal hydroxides, with the metals having various oxidation states, but there is no restriction or guidance as to which oxidation states or combinations of oxidation states are used to prepare the precursor. The precursors described include multi-phase precursors that are not atomically mixed, which, as previously mentioned, is detrimental to the formation of a single-phase cathode material.

[0014] The layered hydroxide phase can be utilized as a precursor to make LiNMC cathodes. LiNMC cathodes are formed from transition metal hydroxide precursors (e.g., Ni, Mn, Co hydroxides) by combining these precursors with a lithium source and heating in air at temperatures above 700°C. Exemplary cathodes are made at temperatures above 800°C. Single crystalline LiNMC (SC-LiNMC) is made when the hydroxide precursor is heated in air with a lithium source to above 900°C. In many cases, an excess of lithium source (up to 20% excess) can be used to promote grain growth and replace lithium lost during the heating step. Hydroxide precursors made by co-precipitation are preferred because they incorporate atomic-scale mixing of the transition metals. Additionally, hydroxide precursors are used because lithium can easily diffuse into the structure and rapidly form NMC during heating with the lithium source. Lithium sources that can be used with hydroxide precursors include Li 2 CO 3 and LiOH H 2 Contains O.

[0015] Dry processing techniques for the production of layered lithium transition metal oxide cathode materials lead to significant cost savings, greater compositional flexibility in the final product, and reduced waste, but typical dry processing steps such as ball milling can result in contamination from the grinding media and the grinding vessel itself. This contamination is typically in the form of iron contamination, which is known to cause capacity fade in layered lithium transition metal oxide cathode material compositions such as LiNMC or LiNCA due to the tendency of Fe to remain in the lithium layer. For this reason, iron contamination is poorly tolerated in these materials. Typically, commercially available LiNMC materials are limited to Fe content less than 100 ppm based on total metal content. Therefore, methods based primarily on thermal processing that minimize or even eliminate both wet and dry processing methods are even more advantageous. Thermal processing methods can be less costly than methods involving wet or dry processing techniques. Furthermore, thermal processing produces little or no waste and results in little or no impurities.

[0016] The main obstacle to using primarily dry processing techniques is the difficulty of obtaining phase-pure mixed transition metal oxide particles with uniform distribution of the transition metal within and between each particle. This is due to the slow diffusion of transition metals during heat treatment. For this reason, precursors in which the transition metals are already atomically mixed are typically prepared prior to heat treatment. For example, lithium mixed transition metal layered oxide cathode materials such as LiNMC and LiNCA are typically prepared by heat treating a mixture of a lithium source (e.g., lithium carbonate or lithium hydroxide) and a precursor transition metal hydroxide made by co-precipitation in which the transition metals are atomically mixed. PCT application WO 2021 / 041296 describes a lithium mixed transition metal oxide (LiNMC) with a crystal grain size of less than 50 nm and the formula (Ni n Mn m Co c ) 1-a A a Li b O 1+b A method is described for producing precursor particles consisting essentially of a single rock salt phase having a crystal size of 0.1 to 0.25 μm. This precursor phase is produced by dry impact milling. Its small grain size facilitates lithiation during heat treatment to form LiNMC. However, the dry impact milling process can introduce impurities due to wear of the milling chamber and milling media. [Prior art documents] [Patent documents]

[0017] [Patent Document 1] International Publication No. 2019 / 185349 Brochure [Patent Document 2] U.S. Patent No. 7,211,237 [Patent Document 3] U.S. Provisional Patent Application No. 62 / 893787 [Patent Document 4] U.S. Provisional Patent Application No. 62 / 946938 [Patent Document 5] U.S. Patent No. 10,651,467(B2) [Patent Document 6] International Publication No. 2021 / 041296 Brochure [Non-patent literature]

[0018] [Non-Patent Document 1] Journal of The Electrochemical Society, 165(5)A1038~A1045(2018) [Non-Patent Document 2] The Journal of The Electrochemical Society, 159(9)A1543~A1550(2012) [Non-Patent Document 3] Linden's Handbook of Batteries, 4th Edition, McGraw-Hill (2010) [Non-Patent Document 4] Nano Energy, 31 247~257(2017) [Non-Patent Document 5] Chemistry of Materials, 29 9923~9936(2017) [Non-Patent Document 6] The Journal of The Electrochemical Society, (167)050501(2020) Summary of the Invention [Problem to be solved by the invention]

[0019] Despite the ongoing and extensive worldwide efforts directed towards developing improved methods of producing such materials, there remains a need for further improvements. Embodiments of the present invention address these needs and provide further advantages as disclosed below. [Means for solving the problem]

[0020] The present disclosure relates to an improved method for preparing lithium nickel manganese cobalt oxide particles for use in lithium batteries and other applications, in which single-phase rock salt precursor particles are first prepared using grinding and heating steps. Advantageously, however, the grinding step can be carried out much faster than in prior art methods using a dry, low-energy grinding procedure. Lithium nickel manganese cobalt oxide particles can then be readily prepared from the precursor particles. Thus, the method can be simpler, faster, and reduce product contamination. Also, embodiments herein relate to the optional use of novel biphasic precursor particles in the preparation method.

[0021] This method uses the formula Li 1+x [(Ni n Mn m Co c ) 1-a A a ] 1-x O 2 where -0.03≦x≦0.06, n+m+c=1, n≧0.05, m≧0.05, c≧0.05, A is a metal dopant, and 0≦a≦0.05. For example, as shown in the examples below, particles can be prepared in which n, m, and c are about 0.6, about 0.2, and about 0.2, respectively.

[0022] This method is a) providing feedstock component particles having a molar ratio of Ni:Mn:Co of n:m:c, the particles comprising nickel-containing particles, manganese-containing particles, cobalt-containing particles, and optional dopant A-containing particles; b) grinding the feed component particles to form a homogeneous feed particle mixture; c) heating the homogenous mixture of raw material particles from b) at a temperature above about 500° C. for a set time of at least about 1 hour, thereby forming a rock salt structure and a crystalline ... n Mn m Co c ) 1-a A a forming precursor particles having O; d) combining a predetermined amount of the precursor particles with a predetermined amount of a lithium source to form a precursor particulate lithium source mixture, the predetermined amount of the lithium source being equal to or greater than the stoichiometric amount required to make the lithium nickel manganese cobalt oxide particles; e) heating the precursor particulate lithium source mixture from d) at a lithiation temperature in an oxygen-containing atmosphere to produce lithium nickel manganese cobalt oxide particles. may include.

[0023] In step a) of the method, the raw material component particles may also contain a flux, which can facilitate diffusion of the transition metal during step c) and improve compositional uniformity. Suitable fluxes are materials that melt during heating step c), in which the oxides of nickel, manganese, and cobalt have some solubility, and whose components are not incorporated into the rock salt phase of the precursor particles (except for oxygen). Examples of suitable fluxes include alkali metal sulfates, e.g., Li 2 SO 4 , Na 2 SO 4 , K 2 SO 4 and combinations thereof, B 2 O 3 , WO 3 , BiO 2 , and MoO 3 In some embodiments, salts that are also soluble in water may be particularly useful, as such fluxes can be removed by washing with water after heating step c).

[0024] In some embodiments, in step b) of the method, the feed grinding procedure may include selecting a feed grinder and a process for the feed grinder, and then grinding the feed component particles for a feed grinding time using the feed grinder and the process for the feed grinder. In some embodiments, the feed grinding procedure produces a multi-phase feed grain mixture that is essentially composed of a nickel-containing grain phase, a manganese-containing grain phase, a cobalt-containing grain phase, and an optional dopant A-containing grain phase in a homogeneous mixture. That is, many of the particles in the feed grain mixture are not ground enough to be chemically reacted to a significant extent. The presence of multiple phases can be easily confirmed by X-ray diffraction analysis.

[0025] In some embodiments, grinding the feed component particles to form a homogenous feed particle mixture includes grinding the feed component particles for a predetermined time determined by obtaining a sample from the feed component particles at one or more time intervals during the grinding step, heating the sample, determining the structure of the heated sample by X-ray diffraction analysis, and determining a feed grinding time based on the time interval that results in the heated sample having a single-phase rock salt structure with an apparent lattice distortion of less than about 0.3%. In some embodiments, the time interval may be a plurality of time intervals.

[0026] In some embodiments in step c) of this method, the heating procedure involves simply heating the homogeneous mixture of raw material particles from step b) at a set temperature for a set time under a suitable heating atmosphere, thereby producing a crystalline crystalline ferromagnetic material having a rock salt structure and the formula (Ni n Mn m Co c ) 1-a A a O, where n, m, c, and a are positive numbers, A is a metal dopant, n+m+c=1, n≧0.05, m≧0.05, c≧0.05, and 0≦a≦0.05. In some embodiments, a suitable representative heating procedure includes heating the homogeneous mixture of raw material particles at 1000° C. for 12 hours under flowing argon.

[0027] In some embodiments in the preparation of the final lithium nickel manganese cobalt oxide particle product, the amount of lithium source employed in step d) is equal to or greater than the stoichiometric amount required to make the lithium nickel manganese cobalt oxide particles.

[0028] In some embodiments, in step b) of this method, the feed grinding time can be a function of the particles used, the feed grinder used, and the process for the feed grinder employed. The grinding time can be empirically determined by a direct method or procedure, or an indirect method or procedure. A direct procedure involves taking one or more samples from the ground feed component particles of b) at any time during the feed grinding procedure, heating the samples according to a representative rock salt heating procedure, determining the structure of the heated samples by X-ray diffraction analysis, and determining that the heated samples have the formula (Ni n Mn m Co c ) 1-a A aand continuing grinding in b) until the rock salt precursor particles having a structure corresponding to O are determined to have a structure corresponding to O, thereby determining the feed grinding time. In other words, the direct method involves determining the appropriate feed grinding time while grinding is in progress. The indirect procedure may involve determining the appropriate feed grinding time in advance. For example, a suitable indirect procedure for determining the feed grinding time includes preparing one or more representative sample mixtures of nickel-containing particles, manganese-containing particles, and cobalt-containing particles, grinding the one or more representative sample mixtures for different times using a representative grinder and a representative process for the representative grinder, heating the representative sample mixtures according to a representative heating procedure, determining the structure of the heated representative sample mixtures by X-ray diffraction analysis, and determining the feed grinding time based on which grinding time interval leads to the heated representative sample mixture having a single-phase rock salt structure with an apparent lattice distortion of less than 0.3%. The appropriate feed grinding time may be a time that has been successfully used under similar circumstances in the past. In some embodiments, the direct method may be omitted or replaced with an indirect method, such as predetermining the grinding time with an indirect method. In some embodiments, the indirect method may be performed on a smaller or fewer batches than the direct method. For example, the indirect method may include preparing one or more representative sample mixtures, grinding one or more representative sample mixtures, heating the representative sample mixtures, and determining the structure of the heated representative samples, but the indirect method is performed on a smaller scale, such as a test batch or pilot batch.

[0029] In some embodiments of the methods disclosed herein, the nickel-containing, manganese-containing, and cobalt-containing particles may be selected from the group consisting of metal oxides, metal hydroxides, metal carbonates, and mixtures thereof. In some embodiments, these particles may be NiO, MnO, and CoO, respectively, all starting with the desired rock salt structure. In some embodiments, n, m, and c are about 0.6, about 0.2, and about 0.2, respectively.

[0030] In embodiments including a predetermined amount of dopant A, the feedstock particles may further include a predetermined amount of dopant A-containing particles. Possible dopants include Mg, Al, Ti, Zr, W, Zn, Fe, Mo, K, Na, Si, Ta, and mixtures thereof. Suitable dopant A-containing particles may be selected from the group consisting of metal oxides, metal hydroxides, metal carbonates, and mixtures thereof. In particular, dopant A-containing particles may include MgO, Al 2 O 3 , TiO, TiO 2 , ZrO 2 , WO 3 , ZnO, FeO, Fe 2 O 3 , Fe 3 O 4 , MoO 3 , K 2 O, Na 2 O, SiO 2 , Ta 2 O 5 , Mg(OH) 2 , Al(OH) 3 , AlO(OH), Zr(OH) 4 , Zn(OH) 2 , Fe(OH) 2 , FeO(OH), Fe(OH) 3 , KOH, and NaOH.

[0031] In some embodiments, the raw material component precursor particles are metal oxides, metal hydroxides, metal carbonates containing two or more metal elements, such as MgAl 2 O 4 , MgMn 2 O 4, CoAl 2 O 4 , NiCoO 2 etc. In some embodiments, the ingredient precursor particles may include water of hydration.

[0032] In some embodiments, the feed mill used in step b) may be for either a "wet" or a "dry" milling process. However, preferably, a dry process is used and the feed mill is a dry mill. Such equipment may comprise an automatic grinder or a mortar and pestle as used in the embodiments disclosed herein. However, for commercial purposes, larger scale equipment for jet milling, ball milling, bead milling, small media milling, stirred ball milling, planetary milling, horizontal ball milling, pebble milling, rod milling, attritor milling, fine grinding, hammer milling, etc., is more suitable and can advantageously reduce production costs.

[0033] In some embodiments, the milling produces a homogenous feedstock particle mixture consisting essentially of a nickel-containing particle phase, a manganese-containing particle phase, a cobalt-containing particle phase, and an optional Dopant A-containing particle phase, and no chemical reactions occur between the nickel-containing particle phase, the manganese-containing particle phase, the cobalt-containing particle phase, and the optional Dopant A-containing particle phase during milling step b).

[0034] Depending on the raw material grinding procedure, a suitable raw material grinding time in step b) may be in the range of about 10 minutes to about 6 days or more. Furthermore, a suitable set temperature in step c) or the heating step after grinding may be in the range of about 500 to about 1600°C. Also, a suitable set time in step c) may be about 1 hour to about 12 hours. Furthermore, a suitable heating atmosphere in the rock salt formation heating procedure in step c) is an inert gas (e.g., argon or nitrogen gas), or a vacuum, or a low oxygen partial pressure gas (i.e., a gas whose equilibrium oxygen partial pressure at a predetermined temperature is lower than the oxygen partial pressure in air, such as CO 2 ) may also be used.

[0035] In another embodiment, the method may further comprise forming the homogeneous mixture of feedstock particles into pellets prior to step c), which can be accomplished using a pellet die and press, or a pelletizer. Forming a homogeneous mixture of feedstock particles facilitates solid diffusion during step c), resulting in improved compositional uniformity of the formed precursor particles.

[0036] In another aspect, the method may further comprise washing the precursor particles with water to remove the flux prior to step d). This washing step may comprise mixing the precursor particles with water to dissolve the flux and then separating the precursor particles from the water / flux solution. Suitable methods for separating the precursor particles from the water / flux solution include filtration or centrifugation. In some embodiments where the feedstock particles comprise a flux, it may be advantageous not to include a washing step prior to step d). In such embodiments, the presence of the flux may aid in the formation of the lithium nickel manganese cobalt oxide particles during step e).

[0037] In another embodiment, the homogeneity of the milled mixture is determined by X-ray diffraction analysis. In another embodiment, the method further comprises forming the precursor particulate lithium source mixture into a pellet prior to step e). In another embodiment, the method further comprises adding a flux to the precursor particulate lithium source mixture prior to step e). In another embodiment, the method further comprises adding a flux to the feed component particles of step a).

[0038] In some embodiments, for lithiation purposes, the lithium source used is lithium carbonate, lithium hydroxide, or lithium oxide, or a mixture thereof, and the amount used may be between about 0 and 30% more than the stoichiometric amount required to make the lithium nickel manganese cobalt oxide particles. In some aspects, the oxygen-containing atmosphere in e) is air or oxygen. Further, the oxygen-containing atmosphere employed in step e) may be air or pure oxygen, and the lithiation temperature used in step e) may range from about 700 to 1000° C. Further, the heating in step e) may be carried out for about 9 hours.

[0039] In some embodiments, the method may optionally include determining the structure of the obtained sample by X-ray diffraction analysis prior to heating the obtained sample to confirm that the obtained sample consists essentially of a nickel-containing particle phase, a manganese-containing particle phase, a cobalt-containing particle phase, and an optional Dopant A-containing particle phase.

[0040] In another embodiment, the method may further comprise forming the precursor particulate lithium source mixture into pellets prior to step e). This can be accomplished using a pellet die and press, or a pelletizer. By forming the precursor particulate lithium source mixture into pellets, lithium loss during heating step e) can be reduced, as opposed to heating the precursor particulate lithium source mixture as a loose powder. Forming the precursor particulate lithium source mixture into pellets also promotes solid-state diffusion, improving the compositional uniformity of the LiNMC product.

[0041] In another embodiment, the method may further comprise the step of adding a flux to the pellets of precursor particulate lithium source mixture prior to step e). The presence of the flux may aid in the formation of lithium nickel manganese cobalt oxide particles during step e). Suitable fluxes are materials that melt during the heating step e), in which nickel, manganese and cobalt oxides have some solubility, and whose components do not become incorporated into the NMC structure (except for lithium and oxygen). Examples of suitable fluxes include alkali metal sulfates, e.g., Li 2 SO 4 , Na 2 SO 4 , K 2 SO 4 and combinations thereof, B 2 O 3 , WO 3 , BiO 2 , and MoO 3 In some embodiments, such fluxes may be removed by washing with water after heating step c), and salts that are further soluble in water may be particularly useful.

[0042] In another embodiment, the method may further comprise, prior to step d), heating the precursor particles in an oxygen-containing atmosphere to convert the precursor particles from particles having a rock salt structure to biphasic particles consisting essentially of a rock salt phase and a cubic spinel phase. Suitable oxygen-containing atmospheres include oxygen, air, or dry air. In particular, the biphasic precursor particles are essentially free of a tetragonal spinel phase.

[0043] As disclosed above, the feedstock grinding time is determined such that the apparent lattice distortion of the single-phase rock salt precursor particles in c) is less than 0.3%. In exemplary embodiments, the feedstock grinding time may also be determined such that the apparent lattice distortion of the single-phase rock salt precursor particles in c) is less than 0.2%, less than 0.1%, or even less.

[0044] In some embodiments, a small amount of additional phase may also be present in the precursor particles in a particular embodiment. For example, the heated precursor particles from step c) may further contain a metallic phase.

[0045] Regarding the specific physical properties of the materials involved, the average crystal grain size of the precursor particles may exceed 100 Å (determined by applying the Scherrer equation to the maximum X-ray diffraction peak of the particles). In some cases, there may be crystal grain sizes larger than those measurable with a typical laboratory X-ray diffractometer (e.g., exceeding 100 nm, exceeding 500 nm, or even exceeding 1 μm). In such cases, the crystal grain size can be determined by direct observation of faceted crystallites with a secondary electron microscope. Similarly, for the novel biphasic precursor particles, each of the existing rock salt phase and spinel phase can have an average crystal grain size exceeding 100 Å, exceeding 200 Å, exceeding 100 nm, exceeding 500 nm, or even exceeding 1 μm.

[0046] In related aspects, the novel biphasic particles have the composition (Ni n Mn m Co c ) 1-a A a O 1+b (where n, m, c, a are positive numbers, A is a metal dopant, n + m + c = 1, n ≥ 0.05, m ≥ 0.05, c ≥ 0.05, 0 ≤ a ≤ 0.05, 0 < b < 0.33), and further consists essentially of a rock salt phase and a cubic spinel phase. In some embodiments, b is about (m + c) / 3. In some aspects, the rock salt phase may be NiO, while the cubic spinel phase may have the chemical formula M 3 O 4 (where M is a mixture of Mn and Co). Further, M may further contain Ni. Additionally, the cubic spinel phase can have a lattice constant in the range of 8.1 Å to 8.4 Å.

[0047] In some aspects, the present disclosure relates to the composition (Ni n Mn m Co c ) 1-a A aO, where n, m, c, and a are positive numbers, A is a metal dopant, and n+m+c=1, n≧0.05, m≧0.05, c≧0.05, and 0≦a≦0.05, consisting essentially of a rock salt phase and having an apparent lattice distortion of less than 0.3%.

[0048] The lithium transition metal oxide particles made according to the methods herein are contemplated for use in a number of commercial applications, including as electrode components in rechargeable batteries, and are particularly suitable for use in the cathode electrodes of rechargeable lithium batteries, e.g., lithium ion batteries. [Brief description of the drawings]

[0049] [Figure 1] 1 is a graph showing an XRD pattern of NiO raw material component particles. [Diagram 2] 1 is a graph showing an XRD pattern of MnO raw material component particles. [Diagram 3] 1 is a graph showing an XRD pattern of CoO raw material component particles. [Figure 4a] 1 is a SEM image of NiO raw material component particles. [Figure 4b] 1 is a SEM image of NiO raw material component particles. [Figure 5a] 1 is a SEM image of MnO raw material component particles. [Figure 5b] 1 is a SEM image of MnO raw material component particles. [Figure 6a] 1 is a SEM image of CoO raw material component particles. [Figure 6b] 1 is a SEM image of CoO raw material component particles. [Figure 7] 1 is a graph showing XRD patterns of RS precursor particles of Comparative Examples 1 to 3 and Examples 1 and 2. [Figure 8] 2 is a graph showing an XRD pattern of the raw material particle mixture of Example 1. [Figure 9] 1 is a graph showing an XRD pattern of the raw material particle mixture of Example 2. [Figure 10a] 1 shows SEM images of the raw particle mixture of Example 1 at different magnifications. [Figure 10b] 1 shows SEM images of the raw particle mixture of Example 1 at different magnifications. [Figure 11a] 1 is a SEM image of the raw particle mixture of Example 2 at different magnifications. [Figure 11b] 1 is a SEM image of the raw particle mixture of Example 2 at different magnifications. [Figure 12] 1 is a graph showing apparent lattice distortion as a function of the automilling time used to prepare RS precursor particles of Comparative Examples 1-3 and Examples 1 and 2. [Figure 13] 1 is a graph showing the XRD pattern of RS precursor particles of Example 3. [Figure 14] 1 is a graph showing the XRD pattern of RS precursor particles of Example 4. [Figure 15a] 1 shows SEM images of RS precursor particles of Example 1 at different magnifications. [Figure 15b] 1 shows SEM images of RS precursor particles of Example 1 at different magnifications. [Figure 16a] 1 shows SEM images of RS precursor particles of Example 2 at different magnifications. [Figure 16b] 1 shows SEM images of RS precursor particles of Example 2 at different magnifications. [Figure 17a] 13A-13C are SEM images of RS precursor particles of Example 3 at different magnifications. [Figure 17b] 13A-13C are SEM images of RS precursor particles of Example 3 at different magnifications. [Figure 18a] 13 shows SEM images of RS precursor particles of Example 4 at different magnifications. [Figure 18b] 13 shows SEM images of RS precursor particles of Example 4 at different magnifications. [Figure 19] 1 is a graph showing XRD patterns of SC-LiNMC particles of Comparative Examples 4 to 6 and Examples 5 and 6. [Figure 20] 1 shows SEM images of SC-LiNMC particles of Comparative Examples 4 to 6 and Examples 5 and 6. [Figure 21]1 is a graph showing voltage curves of the first cycle of SC-LiNMC particles of Comparative Examples 4 to 6 and Examples 5 and 6. [Figure 22] 1 is a plot of discharge capacity versus cycle number for SC-LiNMC particles of Comparative Examples 4-6 and Examples 5 and 6. [Figure 23] 1 is a graph showing the XRD pattern of the SC-LiNMC particles of Example 7. [Figure 24a] 13A-13C are SEM images of the SC-LiNMC particles of Example 7 at different magnifications. [Figure 24b] 13A-13C are SEM images of the SC-LiNMC particles of Example 7 at different magnifications. [Diagram 25] 1 is a graph showing the first cycle voltage curve of the SC-LiNMC particles of Example 7. [Figure 26] 1 is a graph showing the XRD pattern of the SC-LiNMC particles of Example 8. [Figure 27a] 13A-13C are SEM images of the SC-LiNMC particles of Example 8 at different magnifications. [Figure 27b] 13A-13C are SEM images of the SC-LiNMC particles of Example 8 at different magnifications. [Figure 28] 1 is a graph showing the first cycle voltage curve of the SC-LiNMC particles of Example 8. [Figure 29] 1 is a graph showing the XRD pattern of the SC-LiNMC particles of Example 9. [Figure 30a] 13A-13C are SEM images of the SC-LiNMC particles of Example 9 at different magnifications. [Figure 30b] 13A-13C are SEM images of the SC-LiNMC particles of Example 9 at different magnifications. [Diagram 31] 1 is a graph showing the first cycle voltage curve of the SC-LiNMC particles of Example 9. [Diagram 32] 1 is a graph showing the XRD pattern of the SC-LiNMC particles of Example 10. [Diagram 33] 1 is an SEM image of SC-LiNMC particles of Example 10. [Diagram 34]1 is a graph showing the first cycle voltage curve of the SC-LiNMC particles of Example 10. [Diagram 35] 1 is a graph showing the XRD pattern of biphasic precursor particles of Example 11. [Figure 36a] 13 is an SEM image of biphasic precursor particles of Example 11. [Figure 36b] 13 is an SEM image of biphasic precursor particles of Example 11. [Figure 37] 1 is a graph showing the XRD pattern of the SC-LiNMC particles of Example 12. [Figure 38] 1 is an SEM image of SC-LiNMC particles of Example 12. [Figure 39] 1 is a graph showing the first cycle voltage curve of the SC-LiNMC particles of Example 12. [Diagram 40] 1 is a plot of discharge capacity versus cycle number for the SC-LiNMC particles of Examples 10 and 12. [Diagram 41] 1 is a graph showing the XRD pattern of RS precursor particles of Example 13. [Figure 42a] 13 shows SEM images of RS precursor particles of Example 13 at different magnifications. [Figure 42b] 13 shows SEM images of RS precursor particles of Example 13 at different magnifications. [Diagram 43] 1 is a graph showing an XRD pattern of RS precursor particles of Comparative Example 7. [Diagram 44] 1 is a graph showing the XRD pattern of RS precursor particles of Example 14. [Figure 45a] 13 shows SEM images of RS precursor particles of Example 14 at different magnifications. [Figure 45b] 13 shows SEM images of RS precursor particles of Example 14 at different magnifications. [Figure 46] 1 is a graph showing the XRD pattern of RS precursor particles of Example 15. [Figure 47a] 13 shows SEM images of RS precursor particles of Example 15 at different magnifications. [Figure 47b] 13 shows SEM images of RS precursor particles of Example 15 at different magnifications. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0050] Unless the context requires otherwise, throughout this specification and claims, words like "comprise", "comprising" and the like are to be interpreted in an open and inclusive sense. Words like "a", "an" and the like are to be considered as meaning at least one and are not limited to only one.

[0051] The phrases "consisting essentially of" or "consists essentially of" are to be construed as being limited to the specified materials or steps involved (as the context requires), but also to include and not exclude any materials or steps that do not materially affect the basic and novel characteristics of the materials or steps involved. In particular, the phrase "the feedstock grinding procedure produces a homogeneous feedstock particle mixture consisting essentially of a nickel-containing particle phase, a manganese-containing particle phase, a cobalt-containing particle phase, and an optional dopant A-containing particle phase" is to be construed as meaning that the desired end product may contain amounts of other phases that are insignificant with respect to obtaining reasonable purity, regardless of whether such other phases are detectable by x-ray diffraction analysis.

[0052] In this specification, in a related manner, the phrase "essentially the same" is to be interpreted as meaning "the same as," but is to include and not exclude any items or steps that do not materially affect the essential characteristics of the items or steps concerned.

[0053] In related methods, the term "representative" may be used to refer to an item or process that provides essentially the same properties or results for all relevant practical and / or functional purposes related to the representative item or process. For example, in a general method, a particular heating procedure that produces single-phase rock salt precursor particles in step c) from a homogenous mixture of raw material particles in step b) is a "representative" heating procedure even if the set temperature and set time of the particular heating procedure differ from the set temperature and set time of the heating procedure employed in step c).

[0054] As used herein, the term "grinding" is to be given its ordinary meaning as understood by those of skill in the art at the time of the invention, but often refers to a process that includes both grinding and blending.

[0055] As used herein, the term "chemical reaction" is to be given its ordinary meaning as understood by those of skill in the art at the time of the invention, but often refers to the formation or breaking of ionic or covalent bonds between elements within molecules or ions, or between molecules or ions.

[0056] As used herein, the term "stoichiometric" is to be given its ordinary meaning as understood by those of ordinary skill in the art at the time of the invention, but often refers to the ratio of reactants in a chemical equation or formula. For example, H 2 O refers to the ratio of two hydrogen atoms to one oxygen atom in a water molecule, and is expressed by the stoichiometric formula 2H + O ⇔ H 2 O. A stoichiometric value may be a whole number or an integer, or it may be a fraction that can be multiplied by a number to result in a whole number or an integer.

[0057] As used herein, the term "molar ratio" should be given its ordinary meaning as understood by those of skill in the art at the time of the invention, but often refers to the ratio between the molar amounts of any two compounds. One mole of a substance is 6.02214076 x 10 moles of that substance. 23 corresponds to an elementary particle (e.g., atom, molecule, ion, electron).

[0058] In quantitative contexts, the term "about" should be interpreted according to its ordinary meaning as understood by one of ordinary skill in the art at the time of the invention, but generally includes a range of up to plus or minus 1%.

[0059] The term "grain" is to be given its ordinary meaning as understood by those skilled in the art at the time of the invention, but often refers to a crystallite, and the terms are used interchangeably herein.

[0060] "Particulate" is to be given its ordinary meaning as understood by one of ordinary skill in the art at the time of the invention, but will often refer to a plurality of "particles," each of which is made up of one or more grains.

[0061] The term "average particle size" should be given its ordinary meaning as understood by those of skill in the art at the time of the invention, but often refers to the average of the largest dimension of at least 20 random particles observed directly by SEM.

[0062] The term "average grain size" should be given its ordinary meaning as understood by one of ordinary skill in the art at the time of the invention, but often refers to grain size as determined by applying the Scherrer equation to the maximum X-ray diffraction peak of grains of grain size less than 100 nm. For grain sizes of 100 nm or greater, the average grain size refers to the average length of the longest dimension of at least 20 random grains observed directly by SEM.

[0063] The term "single crystal lithium nickel manganese cobalt oxide particles", i.e., SC-LiNMC, should be given its ordinary meaning as understood by one of ordinary skill in the art at the time of the invention, but often refers to lithium nickel manganese cobalt oxide particles whose constituent particles are made up of one or more crystal grains and have an average crystal grain size of at least 1 μm in size.

[0064] The term "phase" is to be given its ordinary meaning as understood by those skilled in the art at the time of the invention, but often refers to a distinct, homogenous form of material separated from other forms of material at a surface.

[0065] The term "rock salt phase" should be given its ordinary meaning as understood by those skilled in the art at the time of the invention, but often refers to an oxide phase having a cubic rock salt crystal structure in which there is no layer order of cations. Such rock salt phases are also known as "disordered rock salt."

[0066] The terms "single-phase rock salt" or "single rock salt phase" should be given their ordinary meaning as understood by those of skill in the art at the time of the invention, but often refer to materials whose XRD patterns are consistent with that of a single rock salt phase, although single-phase rock salt materials can exhibit compositional variations within a single grain or between different grains, which may manifest as peak broadening.

[0067] "Metal dopant" should be given its ordinary meaning as understood by those of skill in the art at the time of the invention, but often refers to the group of metals that can function as dopants in lithium transition metal oxides, including the metals Mg, Al, Ti, Zr, W, Zn, Mo, K, Na, Si, Ta, and mixtures thereof, but excluding the metals Ni, Mn, and Co.

[0068] The terms "metal ion cell" or "metal ion battery" should be given their ordinary meaning as understood by those of ordinary skill in the art at the time of the invention, but often refer to alkali metal ion cells, including, for example, lithium ion cells.

[0069] The term "cathode" should be given its ordinary meaning as understood by those skilled in the art at the time of the invention, but often refers to the electrode where reduction occurs when a metal-ion cell is discharged. In lithium-ion cells, the cathode is the electrode that is lithiated during discharge and delithiated during charge.

[0070] The term "anode" should be given its ordinary meaning as understood by those skilled in the art at the time of the invention, but often refers to the electrode where oxidation occurs when a metal-ion cell is discharged. In lithium-ion cells, the anode is the electrode that is delithiated during discharge and lithiated during charge.

[0071] The term "half-cell" should be given its ordinary meaning as understood by those skilled in the art at the time of the invention, but often refers to a cell having a working electrode and a metallic counter / reference electrode. A lithium half-cell has a working electrode and a lithium metal counter / reference electrode.

[0072] The term "primary particle" should be given its ordinary meaning as understood by those skilled in the art at the time of the invention, but often refers to a particle that is composed of a single crystal grain.

[0073] The term "secondary particle" is to be given its ordinary meaning as understood by those of skill in the art at the time of the invention, but often refers to an aggregate of two or more primary particles.

[0074] The term "apparent lattice strain" should be given its ordinary meaning as understood by those skilled in the art at the time of the invention, but often refers to the results of a Williamson-Hall lattice strain analysis of the XRD pattern of a material. Lattice strain results determined by this method may be due to actual strain in the lattice (normal lattice strain) or peak broadening caused by compositional variations in the sample, or a combination of both.

[0075] The term "flux" should be given its ordinary meaning as understood by those skilled in the art at the time of the invention, but often refers to a substance or mixture of substances that is added during the heating step to aid in a solid state reaction or that melts during the heating step to partially solubilize the material or reactant, or aid in the crystallization of the material or reactant being heated by partially solubilizing a component of the material or reactant, but does not incorporate impurities into the crystal structure of the final product. In other words, the flux remains as a separate phase from the material or reactant being heated and the final product before, during, and after the heating step.

[0076] For the purpose of preparing lithium nickel manganese cobalt oxide particles, a lithium nickel manganese cobalt oxide having a rock salt phase and a formula (Ni n Mn m Co c ) 1 - a A a It has been discovered that desirable phase-pure crystalline precursor particles having O can be produced primarily by mechanical and thermal processing methods, where A is any metal dopant, n, m, c, and a are positive numbers, n+m+c=1, n≧0.05, m≧0.05, c≧0.05, 0≦a≦0.05. The metal dopant A can be Mg, Al, Ti, Zr, W, Zn, Mo, Si, or Ta, or combinations thereof. Furthermore, the crystal grain size of the precursor particles is greater than 20 nm. Such a crystalline rock salt phase in this composition range is not known to have been isolated in a pure form before.

[0077] The synthesis of the precursor particles includes a step of grinding together suitable feed component particles (at least nickel-containing particles, manganese-containing particles, and cobalt-containing particles) to form a homogenous feed particle mixture. Suitable grinding methods include dry grinding and wet grinding methods (e.g., jet milling, ball milling, bead milling, small media milling, stirred ball milling, planetary milling, horizontal ball milling, pebble milling, rod milling, attritor milling, pulverization, hammer milling, mortar grinding). However, dry grinding methods may be preferred because they do not require a subsequent step of separating the feed particle mixture from water and do not generate wastewater. Grinding methods that do not require media, such as jet milling and mortar grinding, are also desirable because they result in less contamination of the feedstock during the grinding process.

[0078] The raw material particles include powdered oxides or hydroxides of nickel, manganese, cobalt, and optionally metal dopant A, e.g., CoO, Co 3 O 4 , Co(OH) 2 , Co(OH) 3 , NiO, Ni(OH) 2 , MnO, Mn 3 O 4 , MnO 2 , Mn(OH) 2 , MgO, TiO, TiO 2 In an exemplary embodiment, the feedstock particles are metal (II) oxides including MnO, CoO, NiO (all having a rock salt structure), and optionally MgO and TiO. In other embodiments, the feedstock particles include metal (III) oxides, or metal (IV) oxides, such as MnO, CoO, NiO, and optionally MgO and TiO. 3 O 4 , MnO 2 , and Co 3 O 4 In some embodiments, the feedstock particles may include metal(II) hydroxides, such as Ni(OH). 2 , Mn(OH) 2 , and Co(OH) 2 , or metal carbonates, such as NiCO 3 , MnCO 3Or CoCO 3 In some embodiments, the feed component particles may be a mixture of one or more metal oxides and one or more metal hydroxides. In some embodiments, the feed component particles may be a mixture of one or more metal (II) oxides and one or more metal (II) hydroxides.

[0079] In some embodiments, the raw material component particles may also include a flux. A suitable flux is one that melts when the raw material component mixture is heated to form the rock salt precursor particles during the rock salt formation heating procedure. However, such a flux should not form impurities in the rock salt precursor particle crystal structure, but rather should coexist as a separate phase with the raw material component mixture or the rock salt precursor particles before, during, and after the rock salt formation heating procedure. Such a flux can promote the diffusion of the transition metal during the rock salt formation heating procedure and increase the compositional uniformity of the resulting rock salt precursor particles. Examples of suitable fluxes include alkali metal sulfates, such as Li 2 SO 4 , Na 2 SO 4 , K 2 SO 4 and combinations thereof, B 2 O 3 , WO 3 , BiO 2 , and MoO 3 In some embodiments, salts that are more soluble in water may be particularly useful, since such fluxes may be removed by washing with water after the rock salt forming heating step.

[0080] Exemplary homogeneous feedstock particle mixtures include those in which all of the feedstock particles are composed of isolated or loosely agglomerated primary particles with an average size of less than 10 μm, less than 1 μm, less than 0.5 μm, or less than 0.2 μm. Generally, homogeneous feedstock particle mixtures are obtained by grinding a mixture of feedstock particles containing secondary particles composed of dense or fused primary particles with an average size of more than 20 μm. Grinding the mixture of feedstock particles is sufficient to obtain feedstock particles composed of isolated or loosely agglomerated primary particles with an average size of less than about 10 μm, less than about 1 μm, or more preferably less than about 0.5 μm, or even smaller, resulting in a suitably homogeneous feedstock particle mixture. The feedstock particle mixture may be considered to be homogeneous on a macroscale, substantially homogeneous on an atomic scale, or sufficiently homogeneous by atomic-level diffusion to produce a lattice distortion of less than about 0.3%.

[0081] The grinding procedure used to prepare a homogenous feedstock particle mixture may include selecting a suitable grinder and process for use with the grinder (e.g., selecting a particular grinding device and a particular operating speed for use with the grinding device) and then grinding the mixture using the device and process for a particular grinding time. Regardless of the grinder and process selected, the grinding step should be performed sufficiently to produce a feedstock particle mixture that is homogenous, has reduced particle size of the feedstock particles, and in which secondary particles composed of dense or fused primary particles are broken down into dispersed or loosely agglomerated primary particles. However, the grinding step of the feedstock particles should not be performed to the extent that chemical reactions occur between the feedstock particles (e.g., two feedstock particles of different chemical compositions combine to produce a third chemical composition) as determined by X-ray diffraction analysis. The occurrence of chemical reactions between the feedstock particles during the grinding step of the feedstock particles is an indication that the grinding step of the feedstock particles is too harsh. Under such harsh conditions, excessive wear on the grinder and media typically results in excessive contamination of the feed particle mixture. The desired results are obtained by using a grinding time long enough to achieve both the desired uniformity and comminution, but not so long as to cause significant chemical reactions.

[0082] Therefore, the determination of the appropriate milling time to prepare a homogeneous raw material particle mixture is particularly important and will vary depending on the raw material particles used, as well as the milling machine and associated process used. Fortunately, the appropriate milling time can be determined using either direct or indirect methods. In either case, testing to determine whether the desired homogeneity and comminution have been achieved involves heating the homogeneous raw material particle mixture or a representative raw material particle mixture using a representative heating procedure and verifying that the desired single-phase rock salt precursor particles having the desired apparent lattice distortion are indeed obtained after heating. An example of a suitable representative heating procedure is heating the homogeneous raw material particle mixture at about 1000° C. for about 12 hours under a flow of argon. In either case, as mentioned above, X-ray diffraction analysis can be used as a test to determine that the milling time is not excessive and no significant chemical reaction has occurred. As shown in the following examples, an advantage of the disclosed method is that the exemplary milling times range from only 10 minutes to 6 days.

[0083] The direct procedure for determining the suitable grinding time simply involves taking one or more samples from the mixture during grinding at any time. Such samples are then heated according to a typical heating procedure, and the structure and apparent lattice distortion of the heated sample are determined by X-ray diffraction analysis. Grinding is continued until the heated sample is determined to have the desired single-phase rock salt structure and apparent lattice distortion, at which point grinding is sufficient, and the time spent grinding thus represents the suitable grinding time. The direct procedure may further include a step of determining the structure of the obtained sample by X-ray diffraction analysis before heating the obtained sample to confirm that the obtained sample essentially consists of a nickel-containing particle phase, a manganese-containing particle phase, a cobalt-containing particle phase, and an optional dopant A-containing particle phase.

[0084] The indirect procedure for determining the suitable grinding time includes predetermining the grinding time. Here, one or more representative sample mixtures of nickel-containing particles, manganese-containing particles, and cobalt-containing particles may be prepared in advance and then ground for different times. As with the direct procedure, the representative sample mixture is then heated according to a representative heating procedure, and the structure and apparent lattice distortion of the heated representative sample mixture are determined by X-ray diffraction analysis, and the suitable grinding time is determined based on which grinding time leads the heated representative sample mixture to have the desired single-phase rock salt structure and apparent lattice distortion. Alternatively, as can be easily understood by those skilled in the art, once a suitable grinding time is determined for a feedstock component particle and grinding method, the suitable grinding time can be used for the same combination of feedstock component particle and method in the future.

[0085] The representative sample mixture, representative grinding machine and associated process, and representative heating procedure used above may, of course, be identical to those used to ultimately actually prepare the desired LiNMC particles, although one skilled in the art will appreciate that "representative" does not require identical. Significant variations in material type, equipment selection, grinding speed (if necessary), heating temperature, etc. are still expected to be sufficiently representative to determine a satisfactory grinding time.

[0086] To complete the synthesis of the desired precursor particles, the homogenous mixture of raw material particles is heated according to a heating procedure that includes heating to a set temperature for a set time under a suitable heating atmosphere. Exemplary suitable heating atmospheres include N 2 In some embodiments, inert gases include CO 2A low oxygen partial pressure gas such as argon may be used. In some embodiments, a vacuum may be used as a suitable heating atmosphere. In some embodiments, the heating atmosphere is an inert gas that is flowed over the sample. In some embodiments, a "getter" may be placed upstream of the homogenous feedstock particle mixture in the inert gas flow of the heating atmosphere. Suitable getters include elements and compounds that reduce the oxygen partial pressure in the heating atmosphere, and include metal particles, metal sponges, and metal oxide particles. Exemplary getters include titanium particles, titanium sponges, and MnO particles.

[0087] Exemplary set temperatures are greater than about 500° C., greater than about 700° C., greater than about 800° C., or greater than about 900° C. In some embodiments, the set temperature for the heating step may be between about 500° C. and about 1600° C., between about 500° C. and about 1200° C., between about 500° C. and about 1100° C., or between about 500° C. and about 900° C. Exemplary set times are greater than about 1 hour, greater than about 2 hours, greater than about 5 hours, or greater than about 10 hours. In some embodiments, the set time for the heating step is between about 1 hour and about 20 hours, between about 1 hour and about 15 hours, or between about 1 hour and about 12 hours. Using such a heating procedure, the homogenous feedstock particle mixture prepared as described above reacts to form a mixture having an XRD pattern characteristic of a single rock salt (RS) phase and having the formula (Ni n Mn m Co c ) 1-a A a Crystalline precursor particles (RS precursor particles) are formed having a crystal grain size of greater than 20 nm and having a diameter of 100 nm. The RS precursor particles are further characterized by the absence of other metal oxide phases as detected by X-ray diffraction analysis (XRD). In some embodiments, the RS precursor particles are formed by heating in an inert or reducing atmosphere to produce Ni 2+The RS precursor particles may contain small amounts of metallic phases such as Ni due to the reduction of LiNMC. In some embodiments, the RS precursor particles may also contain one or more phases due to the presence of flux. If the grinding step is not sufficient to achieve homogeneity of the raw particle mixture, the mixture cannot form rock salt precursor particles by heating in an inert atmosphere. In such a situation, an XRD pattern characteristic of a multiphase mixture of metal oxides may be obtained. Such an XRD pattern includes identifiable peaks of phases that do not have a rock salt structure. Thus, the presence of a multiphase mixture of metal oxides after heating the raw particle mixture in an inert atmosphere is indicative of reduced uniformity of the RS precursor particles, which may lead to reduced uniformity of the final LiNMC product particles and poor electrochemical performance.

[0088] In another aspect, the method may further include forming the homogenous feedstock particle mixture into pellets prior to the rock salt forming heating step. This can be accomplished using a pellet die and press, or a pelletizer. Forming a homogenous feedstock particle mixture facilitates solid diffusion during the rock salt forming heating step, resulting in improved compositional uniformity of the formed precursor particles.

[0089] Exemplary RS precursor particles were found to have low apparent lattice distortion as determined by analysis of XRD patterns by the Williamson-Hall method. Without being bound by theory, in some embodiments, the apparent lattice distortion may be due to distortions in the lattice (normal lattice distortion). It is believed that low normal lattice distortion is indicative of a uniform distribution of metals in the crystal structure of the rock salt precursor particles. In other embodiments, the apparent lattice distortion may be due to the presence of a rock salt phase having a compositional distribution. This distribution may produce an XRD pattern that corresponds to a single-phase RS precursor particle with broadened peaks due to a distribution of lattice constants due to the compositional distribution of the RS precursor particle phase in the sample. The broadening of the XRD peaks in this case may also be quantified as apparent lattice distortion using the Williamson-Hall method. Thus, RS precursor particles with low apparent lattice distortion are consistent with a uniform distribution of metals within the RS precursor particles. In some embodiments, exemplary RS precursor particles have an apparent lattice distortion of less than about 0.3%, less than about 0.2%, or even lower. In some embodiments, RS precursor particles with an apparent lattice distortion of about 0.2% or less, particularly about 0.1% or less, have been found to be particularly useful. Such RS precursor particles have a very high degree of uniformity. LiNMC made from such RS precursor particles can have desirable properties such as high initial coulombic efficiency, low capacity fade, and low voltage polarization.

[0090] It has also been found that heating certain RS precursor particles in air can produce useful novel biphasic precursor particles that consist essentially of two oxide phases, one with a rock salt structure and the other with a cubic spinel structure. The composition of the biphasic precursor particles is (Ni n Mn m Co c ) 1-a A a O b(where n, m, c, and a are positive numbers, A is a metal dopant, n + m + c = 1, n ≥ 0.05, m ≥ 0.05, c ≥ 0.05, 0 ≤ a ≤ 0.05, and 1 < b < 1.33). In some embodiments, b is about n + 4(m + c) / 3. The oxide phase having a rock salt structure may be NiO, while the oxide phase having a cubic spinel structure has the chemical formula M 3 O 4 (where M is a mixture of Mn and Co), which may be a cobalt manganese oxide spinel. In some embodiments, M may further contain Ni. In some embodiments, M may further contain a dopant element. In some embodiments, M may further contain Li. Further, the cubic spinel phase may have a lattice constant in the range of 8.1 Å to 8.4 Å. Exemplary biphasic precursor particles are formed from RS precursor particles having a high degree of uniformity, i.e., RS precursor particles with a lattice strain of less than about 0.3%, less than about 0.2%, less than about 0.1%, or even smaller. In some embodiments, the biphasic precursor particles may also contain one or more phases due to the presence of a flux.

[0091] Exemplary biphasic precursor particles have been found to have narrow XRD peaks corresponding to grain sizes of greater than about 100 Å, or even greater than about 200 Å, as determined by applying the Scherrer equation to the maximum diffraction peaks of each oxide phase. In some cases, the grain size may exceed the size measurable by a typical laboratory X-ray diffractometer. In such cases, the grain size may also be determined by observing the average crystallite size using a SEM. A grain size greater than about 500 Å, about 100 nm, about 500 nm, or even about 1000 nm is desirable. However, a grain size that is too large (e.g., greater than 5000 nm) is undesirable because it may cause too slow lithiation during the LiNMC formation heating procedure, resulting in poor formation of LiNMC. Without being bound by theory, a broader XRD peak may indicate that a mixture of different metal oxide phases with cubic spinel and rock salt structures is formed, each with different metal compositions and different lattice constants. When the XRD pattern of such a multiphase mixture is measured, the individual peaks from each phase associated with a particular Miller index combine to appear as a single broad XRD peak, resulting in a small apparent grain size as determined by the Scherrer equation. Such multiphase mixtures of rock salt oxide and cubic spinel oxide phases have a less uniform distribution of transition metals compared to biphasic precursor particles of the same overall composition. Thus, such precursor particles having a small grain size as determined by the Scherrer equation are less desirable.

[0092] To prepare the final lithium nickel manganese cobalt oxide particles, the precursor particles (RS precursor particles or biphasic precursor particles) are combined with a lithium source obtained in the form of lithium-containing particles by blending or grinding. Suitable lithium-containing particles include Li 2 CO 3 , Li 2 O, LiOH H 2O. The step of combining the predetermined amount of lithium-containing particles can be accomplished by commonly used blending or grinding processes such as V-blending, tumbling, mixing, jet milling, ball milling, bead milling, small media milling, stirred ball milling, planetary milling, horizontal ball milling, pebble milling, rod milling, attritor milling, pulverization, hammer milling, and mortar grinding. Most preferred are dry blending and grinding methods that do not require media, such as jet milling and mortar grinding, because such methods result in less contamination during processing. As mentioned above, the combining step is preferably not carried out to the extent that a chemical reaction occurs between the precursor and the lithium particles. A chemical reaction may indicate that the combining step is too harsh. Under harsh conditions, excessive wear of the mixing equipment and media typically results in excessive contamination of the mixture. To ensure complete lithiation, the amount of lithium-containing particles used is typically equal to or greater than (e.g., about 5% to about 20% more than) the stoichiometric amount required to make lithium nickel manganese cobalt oxide particles.

[0093] In addition to combining the precursor particles (RS precursor particles or biphasic precursor particles) with a lithium source, a flux may be added. A suitable flux is one that melts when the precursor particulate lithium source mixture is heated to form LiNMC during the NMC-forming heating procedure. However, such a flux should not form an impurity in the LiNMC crystal structure, but rather coexist as a separate phase with LiNMC after the NMC-forming heating procedure. In some cases, the flux may combine with the lithium source during the NMC-forming heating procedure to form a lithium-containing flux. For example, BiO 2 is combined with the lithium source during the NMC formation heating step to form Li 7 BiO 6The flux may be used as a flux to form a lithium-containing flux. In such cases, an additional amount of lithium source may be required to account for the lithium forming the lithium-containing flux. Such a flux may facilitate diffusion of the transition metal during the rock salt formation heating procedure and increase the uniformity of the composition of the resulting rock salt precursor particles. Examples of suitable fluxes include alkali metal sulfates, e.g., Li 2 SO 4 , Na 2 SO 4 , K 2 SO 4 and combinations thereof, B 2 O 3 , WO 3 , BiO 2 , and MoO 3 In some embodiments, salts that are more soluble in water may be particularly useful, since such fluxes may be removed by washing with water after the NMC formation heating step.

[0094] After the precursor particles are combined with a predetermined amount of lithium-containing particles, the precursor particulate lithium source mixture is heated in an oxygen-containing gas in a conventional manner known to those skilled in the art to form LiNMC, including SC-LiNMC (NMC formation heating procedure). This heating procedure can be carried out in a box, tube, or other suitable furnace with flowing oxygen-containing gas. Typical oxygen-containing gases include oxygen, air, dry air, or a mixture of oxygen and an inert gas. Furthermore, the NMC formation heating procedure can be carried out in a single heating step or in multiple heating steps using multiple gases and multiple temperatures. Samples can be collected and crushed between heating steps, and additional lithium sources can be added. The lithiation temperature used in this heating procedure can be greater than 700°C, or even greater than 1000°C. However, an exemplary range is about 800-900°C. Furthermore, the heating can be carried out for more than 1 hour, or even for more than 10 hours. However, an exemplary time is about 9 hours. However, heating times greater than 20 hours or temperatures greater than 1200° C. are typically avoided as they can lead to excessive lithium loss.

[0095] In another embodiment, the method may further include forming the precursor particulate lithium source mixture into pellets prior to the lithium nickel manganese cobalt oxide-forming heating step. This can be accomplished using a pellet die and press, or a pelletizer. By forming the precursor particulate lithium source mixture into pellets, lithium loss during the lithium nickel manganese cobalt oxide-forming heating step can be reduced as opposed to heating the precursor particulate lithium source mixture as a loose powder. Forming the precursor particulate lithium source mixture into pellets also promotes solid-state diffusion, improving the compositional uniformity of the LiNMC product.

[0096] For present purposes, SC-LiNMC is defined as LiNMC particles whose constituent particles are composed of one or more grains and have an average grain size of at least 1 μm in size. In some embodiments, the average grain size of the SC-LiNMC may be 2 μm, 5 μm, 10 μm, or larger. However, if the average grain size of the SC-NMC is too large, poor lithium diffusion may occur. Therefore, an SC-LiNMC grain size of less than 20 μm is preferred.

[0097] In some embodiments, the SC-LiNMC particles may be in the form of particles that contain, on average, only a single grain. In other embodiments, the SC-LiNMC particles may include secondary particles that are composed of multiple grains. In the latter case, further processing steps may be used to break the secondary particles into smaller secondary particles, or even into individual grains. Suitable processing steps for this purpose include jet milling, and dry or wet grinding or milling methods, such as bead milling.

[0098] In some cases, it has proven more difficult to form LiNMC with desirable electrochemical properties by heating the precursor particulate lithium source mixture than when using a mixture of lithium source and conventional NMC hydroxide precursors. In such embodiments, heating the precursor particulate lithium source mixture can result in excessive evaporation of lithium, lowering the lithiation level of the final LiNMC, and forming multiple phases. Without being bound by theory, it is believed that the diffusion of lithium during the LiNMC formation heating procedure is much slower within the precursor particles than within the typically used NMC hydroxide precursors. As a result, Li 2 CO 3 and LiOH H 2 Conventionally used lithium sources, such as LiO, may tend to melt and separate from the rock salt precursor particles before full lithiation occurs during the LiNMC formation heating step. Lithium sources that do not melt at the lithiation temperatures used in the embodiments disclosed herein to achieve fully lithiated single-phase LiNMC have been found to be particularly useful. One such exemplary lithium source is Li 2 O is one example.

[0099] In some embodiments, during the LiNMC formation heating step, an additional lithium source may be introduced into the gas stream in the heating zone of the furnace, upstream of the ground precursor / lithium particle mixture. This additional lithium source may be Li 2 O, Li 2 CO 3、 or LiOH H 2 Without being bound by theory, it is believed that the use of an additional lithium source during the LiNMC formation heating step increases the partial pressure of lithium-containing species in the furnace, reduces the evaporation of lithium from the ground precursor / lithium particle mixture during heating, and also increases the level of lithiation in the final LiNMC product.

[0100] It has also been found that the biphasic precursor particles can be lithiated much more efficiently than rock salt precursor particles, thereby avoiding the problem of lithium loss during the heating step to form LiNMC. Without wishing to be bound by theory, it is believed that the conversion of the single-phase rock salt precursor to the biphasic precursor particles creates grain boundaries through which lithium can diffuse more efficiently, making the biphasic precursor particles easier to lithiate. It is further believed that lithium can diffuse more efficiently through the spinel oxide phase compared to the rock salt oxide phase, also making the biphasic precursor particles easier to lithiate.

[0101] Once prepared in the manner described above, the LiNMC particles are generally ready for use in their intended applications as is conventional. For battery applications, electrodes and electrochemical devices employing LiNMC particles can be prepared in a number of ways known to those skilled in the art. For example, there are any number of designs and methods for producing cathode electrodes for rechargeable lithium ion batteries, as well as for producing the batteries themselves, which have been extensively described in the art.

[0102] The disclosed method advantageously includes a dry, low-energy mill and process that takes less time to prepare precursor particles than prior art methods. Thus, the method of the present invention is simple, fast, and reduces contamination of the product particles. For example, despite the results of the methods disclosed in the aforementioned PCT application WO 2021 / 041296, the method of the present invention can achieve the desired results faster using low-energy milling, thus reducing the possibility of impurities being present. The present method differs from the method of WO 2021 / 041296 in that the method of WO 2021 / 041296 causes chemical reactions between particles in the feedstock, whereas the present method does not cause chemical reactions and the multi-phase milled mixture of the original feedstock particles is preserved. Furthermore, the present method involves a step of heating in an inert gas after the milling step.

[0103] Although embodiments have been described herein, those skilled in the art will understand that the embodiments can be combined in various ways to produce a method that is more advantageous than the prior art. Those skilled in the art will appreciate the entire disclosure. Although various benefits and advantages have been described with respect to the individual sub-processes, the methods disclosed herein may provide synergistic effects over the prior art. For example, without wishing to be bound to any embodiment or combination of embodiments, grinding in parallel with pelletizing and flux addition may provide synergistic effects not recognized in the prior art disclosure.

[0104] The following examples illustrate certain aspects of the embodiments disclosed herein and should not be construed as limiting the embodiments in any way. Those skilled in the art will readily appreciate that other variations in the methods used and materials produced herein are possible. EXAMPLES

[0105] Exemplary lithium nickel manganese cobalt oxide particles and precursor particles having a rock salt structure were prepared using dry processing methods according to embodiments herein. For comparative purposes, other precursor particles were also prepared. Various properties of these particles were determined and are presented below. Additionally, electrodes and electrochemical cells were prepared using some of these lithium nickel manganese cobalt oxide particles. Cell performance results obtained from the electrochemical cells are also presented below.

[0106] Material characterization X-ray diffraction (XRD) patterns were collected using a Rigaku Ultima IV diffractometer equipped with a CuKα X-ray source, a diffracted beam graphite monochromator, and a scintillation detector.

[0107] Scanning electron microscope (SEM) images were obtained using a JEOL 840-SEM or a TESCAN MIRA 3 LMU variable pressure Schottky field emission scanning electron microscope (SEM).

[0108] The average particle size was determined from SEM images. The average grain size was determined from SEM images or by applying the Scherrer equation to the full width at half maximum of the XRD peaks. For average particle size or grain size determined from SEM images, these averages were based on the maximum dimension of at least 20 random particles or grains, respectively, observed directly by SEM.

[0109] 1. Preparation of Electrodes Sample electrodes for laboratory testing were prepared from a slurry prepared by mixing 0.920 g of the prepared LiNMC particles, 0.040 g of carbon black (Super C65, Imerys Graphite and Carbon), and 0.040 g of polyvinylidene fluoride binder (PVDF, Kynar HSV 900) with 1.4 g of N-methyl-2-pyrrolidone (NMP, Sigma Aldrich, anhydrous 99.5%) in a mass ratio of LiNMC particles / carbon black / PVDF of 92 / 4 / 4. The slurry was mixed for 15 minutes using a high shear mixer equipped with a Cowles-type blade impeller rotating at 2000 rpm. The resulting slurry was then coated onto aluminum foil (Furukawa Electric Co., Ltd., Japan) using a 0.006 inch gap coating bar. The coating was then dried in air at 120° C. for 1.5 hours, cut into 1.3 cm disks, and then heated under vacuum at 120° C. overnight.

[0110] 1. Preparation of Electrochemical Test Cell To evaluate various materials as electrode materials in Li-ion cells, laboratory test lithium half-cells (also referred to herein as electrochemical test cells) were constructed and tested. Cathode electrodes utilizing the prepared LiNMC particles as active materials were assembled into 2325-type coin-type lithium half-cells with lithium foil (99.9%, Sigma Aldrich) counter / reference electrodes (Note: As known to those skilled in the art, the results of these test lithium half-cells can reliably predict the performance of electrode materials in lithium-ion batteries). Each coin-type lithium half-cell contained two layers of Celgard 2300 separator and one layer of blown microfiber (3M). The electrolyte was 1 M LiPF in a solution of ethylene carbonate, diethyl carbonate, and monofluoroethylene carbonate (volume ratio 3:6:1, all from BASF). 6 (BASF) was used. Cell assembly was performed in an Ar-filled glove box. The cells were galvanostatically cycled at 30.0±0.1°C between 2.5V and 4.3V and at rates of C / 20 (initial cycles) and C / 5 (subsequent cycles) using a Maccor series 4000 automated test system.

[0111] raw material particles In these examples, the feed particles used to prepare the precursor particles included 4.05 g of NiO (Sigma-Aldrich, -325 mesh, 99%), MnO (Aldrich, -60 mesh, 99%), and CoO (Alfa Aesar, 99.7%). Figures 1-3 show the XRD patterns of the NiO, MnO, and CoO feed particles, respectively. All are phase pure and characterized as having a rock salt structure. Figures 4-6 show SEM images of the NiO, MnO, and CoO feed particles, respectively. The NiO feed particles consist of grains of about 0.5 μm that fuse together to form particles of 5-50 μm in size. The MnO feed particles consist of grains of about 5 μm that fuse together to form particles of 100-500 μm in size. The CoO feed particles consist of grains of about 0.5 μm that aggregate to form particles of 5-50 μm in size.

[0112] Comparative Example 1 RS precursor particles prepared by manually grinding raw material component particles Chemical formula Ni 0.6 Mn 0.2 Co 0.2 Comparative Example 1 RS precursor particles with O were prepared by grinding raw material particles of 12.11 g NiO (Sigma-Aldrich, -325 mesh, 99%), 3.84 g MnO (Aldrich, -60 mesh, 99%), and 4.05 g CoO (Alfa Aesar, 99.7%) by manual grinding in a mortar and pestle. The resulting mixture was placed in an alumina crucible and heated in a tube furnace at 1000 °C for 12 h under argon flow. An alumina crucible filled with MnO powder as an oxygen getter was placed upstream of the tube furnace. The resulting RS precursor particles were ground in a mortar and pestle and passed through a 53 μm sieve. Figure 7 shows the XRD pattern of the resulting RS precursor particles, which is characteristic of a phase-pure rock salt structure with a lattice parameter of 4.234 Å. The apparent lattice strain was determined to be 0.413% by the Williamson-Hall method, which exceeds the apparent lattice strain value of 0.3%, indicating poor compositional homogeneity of this sample. The milling and heating conditions, lattice constants, and apparent lattice strain values ​​of this sample are listed in Table 1.

[0113] (Comparative Example 2 and Comparative Example 3) RS precursor particles produced by automatic grinding of raw material component particles in insufficient time Chemical formula Ni 0.6 Mn 0.2 Co 0.2 The RS precursor particles having O in Comparative Examples 2 and 3 were prepared in the same manner as in Comparative Example 1, except that an automatic grinder (Pulverisette 2 Mortar Grinder, Fritsch GmbH) was used as the grinding method for preparing the raw material particle mixture. Furthermore, the grinding times in Comparative Examples 2 and 3 were 0.75 hours and 1.5 hours, respectively.

[0114] Figure 7 shows the XRD patterns of the produced RS precursor particles, characteristic of a phase pure rock salt structure with a lattice constant of 4.237 Å for Comparative Example 2 and 4.239 Å for Comparative Example 3. The apparent lattice distortion was determined by the Williamson-Hall method to be 0.572% for Comparative Example 2 and 0.472% for Comparative Example 3, both of which exceed the apparent lattice distortion value of 0.3%, indicating poor compositional uniformity for these samples. The milling and heating conditions, lattice constants, and apparent lattice distortion values ​​for these samples are listed in Table 1.

[0115] (Examples 1 to 4) RS precursor particles produced by automatic grinding of raw material component particles Chemical formula Ni 0.6 Mn 0.2 Co 0.2 The RS precursor particles of Examples 1-4 having O were prepared in the same manner as Comparative Example 2, except that different milling times by automated milling and, in some cases, different heating temperatures were used. The milling and heating conditions, lattice constants, and apparent lattice strain values ​​of these samples are listed in Table 1.

[0116] 8 and 9 show the XRD patterns of the raw particle mixtures prepared after grinding the raw component particles of Examples 1 and 2, respectively. These XRD patterns are characteristic of a mixture of NiO, MnO, and CoO phases, all with rock salt structure, with no other phases present. That is, no chemical reactions were detected between the three raw particle components, and no impurity phases were detected even after 6 hours of grinding the raw component particles by automated milling.

[0117] Figures 10 and 11 show SEM images of the raw material particle mixture prepared after grinding the raw material component particles of Examples 1 and 2, respectively. The raw material particle mixture is composed of small primary particles with an average size of less than 1 μm, loosely agglomerated into larger secondary particles with sizes of about 5-20 μm.

[0118] 7 shows the XRD patterns of the RS precursor particles of Examples 1 and 2, which are characteristic of a phase-pure rock salt structure with a lattice constant of 4.241 Å for Example 1 and 4.243 Å for Example 2. The apparent lattice distortions were determined by the Williamson-Hall method to be 0.127% for Example 1 and 0.179% for Example 2, indicating excellent compositional uniformity in these samples.

[0119] Figure 12 plots the apparent lattice distortion of the RS precursor particles of Comparative Examples 1 and 2 and Examples 1 and 2 as a function of the grinding time of the raw component particles in their preparation. The figure shows that grinding times of more than 1.5 hours are required under the grinding conditions used to achieve the desired apparent lattice distortion values ​​of less than 0.3%, which corresponds to good compositional homogeneity in the resulting RS precursor particles.

[0120] 13 and 14 show the XRD patterns of the RS precursor particles of Examples 3 and 4, which are characteristic of a phase pure rock salt structure with a lattice constant of 4.234 Å for Example 3 and 4.231 Å for Example 4. The apparent lattice distortions were determined by the Williamson-Hall method to be 0.088% for Example 3 and 0.079% for Example 4, indicating excellent compositional uniformity in these samples.

[0121] 15-18 show SEM images of the RS precursor particles of Examples 1-4. All samples consist of faceted primary crystallites. The average crystal grain sizes of the RS precursor particles of Examples 1-4 are listed in Table 2.

[0122] [Table 1]

[0123] [Table 2]

[0124] Comparative Example 4 Li 2CO 3 SC-LiNMCs prepared with 25% excess Li using a lithium source SC-LiNMC was prepared as follows: 2 g of the RS precursor particles of Comparative Example 1 was dissolved in water with a solution of the formula LiNi 0.6 Mn 0.2 Co 0.2 O 2 Li, which corresponds to a 25% excess lithium content, according to the Li:Ni:Mn:Co ratio expressed by 2 CO 3 The resulting RS precursor particulate lithium source mixture was placed in an alumina crucible and heated in a tube furnace in air at 800° C. for 3 hours and then at 900° C. for 6 hours (these heating at 800° C. and 900° C. constitute the LiNMC formation heating procedure). Finally, the SC-LiNMC product was ground in a mortar and pestle and passed through a 38 μm sieve.

[0125] The XRD pattern of the SC-LiNMC of Comparative Example 4 is shown in FIG. 2 Single-phase LiNi with structure 0.6 Mn 0.2 Co 0.2 O 2 This is a characteristic of

[0126] An SEM image of the SC-LiNMC of Comparative Example 4 is shown in Figure 20. It consists of single crystal grains with an average size of about 3 μm, which aggregate to form secondary particles with a size of about 15 μm.

[0127] An electrode and electrochemical test cell were fabricated from the SC-LiNMC of Comparative Example 4. The first cycle voltage curve of this cell is shown in FIG. 21, and the discharge capacity as a function of cycle number is shown in FIG. 22. The reversible capacity, initial coulombic efficiency, and capacity fade rate of the test cell after 100 cycles are listed in Table 3. SC-LiNMC had relatively low capacity and initial coulombic efficiency for its composition. In addition, the capacity fade rate was high. This is directly related to the heterogeneity of the precursor particles used in the synthesis of this SC-LiNMC, which led to the heterogeneity of the final SC-LiNMC particles.

[0128] [Table 3]

[0129] (Comparative Examples 5 and 6) Li 2 CO 3 SC-LiNMCs prepared with 25% excess Li using a lithium source SC-LiNMC was prepared in the same manner as in Comparative Example 4, except that instead of using the RS precursor particles of Comparative Example 1, the RS precursor particles of Comparative Examples 2 and 3 were utilized, respectively.

[0130] The XRD patterns of the SC-LiNMCs of Comparative Examples 5 and 6 are shown in FIG. 2 Single-phase LiNi with structure 0.6 Mn 0.2 Co 0.2 O 2 This is a characteristic of

[0131] SEM images of the SC-LiNMC of Comparative Examples 5 and 6 are shown in Figure 20. They consist of single crystal grains with an average size of about 3 μm, which aggregate to form secondary particles with a size of about 15 μm.

[0132] Electrodes and electrochemical test cells were fabricated from the SC-LiNMC particles of Comparative Example 5 and Comparative Example 6. The first cycle voltage curves are shown in FIG. 21, and the discharge capacity as a function of cycle number is shown in FIG. 22. The reversible capacity, initial coulombic efficiency, and capacity fade rate of these test cells after 100 cycles are listed in Table 3. These samples of SC-LiNMC had relatively low capacity and initial coulombic efficiency for their composition. In addition, the capacity fade rate was high. This is believed to be directly related to the heterogeneity of the precursor particles used in the synthesis of the SC-LiNMC of Comparative Examples 5 and 6, leading to the heterogeneity of the final SC-LiNMC particles.

[0133] (Examples 5 and 6) Li 2 CO 3 SC-LiNMCs prepared with 25% excess Li using a lithium source SC-LiNMC was prepared in the same manner as in Comparative Example 4, except that instead of using the RS precursor particles of Comparative Example 1, the RS precursor particles of Examples 1 and 2 were utilized, respectively.

[0134] The XRD patterns of the SC-LiNMCs of Examples 5 and 6 are shown in FIG. 2 Single-phase LiNi with structure 0.6 Mn 0.2 Co 0.2 O 2 This is a characteristic of

[0135] SEM images of the SC-LiNMC of Examples 5 and 6 are shown in Figure 20. They consist of single crystal grains with an average size of about 3 μm, which aggregate to form secondary particles with a size of about 15 μm.

[0136] Electrodes and electrochemical test cells were fabricated from the SC-LiNMC particles of Examples 5 and 6. The first cycle voltage curves are shown in FIG. 21, and the discharge capacity as a function of cycle number is shown in FIG. 22. The reversible capacity, initial coulombic efficiency, and capacity fade rate of these test cells after 100 cycles are listed in Table 3. These samples of SC-LiNMC had high capacity and initial coulombic efficiency for their composition. In addition, the capacity fade rate was low. This is believed to be directly related to the uniformity of the composition of the precursor particles used to synthesize the SC-LiNMC of Examples 5 and 6, leading to the uniformity of the final SC-LiNMC particles.

[0137] Example 7 Li 2 CO 3 SC-LiNMCs prepared with 5% excess Li using a lithium source SC-LiNMC was prepared in the same manner as described in Example 6, except that the compound had the formula LiNi 0.6 Mn 0.2 Co 0.2 O 2 Li, which corresponds to a 5% excess lithium content, according to the Li:Ni:Mn:Co ratio expressed by 2 CO 3 (Alfa Aesar, 99%) except that 1.05 g was used.

[0138] The XRD pattern of the SC-LiNMC of Example 7 is shown in FIG. 2 Single-phase LiNi with structure 0.6 Mn 0.2 Co 0.2 O 2 This is a characteristic of

[0139] The SEM image of the SC-LiNMC of Example 7 is shown in Figure 24. It consists of aggregated single crystal grains. The average grain size determined from the SEM image was 1.7±0.5 μm.

[0140] An electrode and cell were prepared from the SC-LiNMC of Example 7, and the first cycle voltage curve of this cell is shown in Figure 25. The first cycle reversible capacity (RC) of this sample was 159 mAh / g, and the ICE was 88%.

[0141] Without being bound by theory, it is believed that the higher ICE of the SC-LiNMC cell of Example 5 compared to Example 7 is due to the larger amount of excess lithium source used in Example 5. In Example 7, Li 2 O 2 It is believed that there was not enough lithium present to fully lithiate the sample due to evaporation of LiNMC to form LiNMC. It was observed that the larger amount of excess lithium source used in Example 5 resulted in more complete lithiation of the sample and a higher ICE.

[0142] Example 8 Li 2 CO 3 SC-LiNMCs formed using a lithium source with 5% excess Li and increasing the lithium partial pressure during the heating process SC-LiNMC was prepared in the same manner as described in Example 7, except that during the heating step to form LiNMC, pure Li was not added. 2 Except that an alumina crucible filled with O powder was placed upstream of the air flow from the sample.

[0143] The XRD pattern of the SC-LiNMC of Example 8 is shown in FIG. 2 Single-phase LiNi with structure 0.6 Mn 0.2 Co 0.2 O 2 This is a characteristic of

[0144] The SEM image of the SC-LiNMC of Example 8 is shown in Figure 27. It consists of aggregated single crystal grains. The average grain size determined from the SEM image was 3.55 ± 1.07 μm.

[0145] An electrode and cell were prepared from the SC-LiNMC of Example 8, and the first cycle voltage curve is shown in Figure 28. The first cycle reversible capacity of this sample was 164 mAh / g, and the ICE was 85%.

[0146] Without being bound by theory, it is believed that the larger grain size, higher RC, and higher ICE of the SC-LiNMC particles in Example 8 compared to Example 7 are due to the Li 2 Due to the presence of O, the lithium partial pressure increases during this heating step to form NMC, and Li 2 O 2 This is believed to be due to the reduced amount of lithium lost through evaporation of Li during the heating process. 2 O 2 It is believed that due to evaporation of Li, there was not enough lithium present to fully lithiate the sample. 2 O 2の It is believed that the reduced lithium loss due to evaporation increased the amount of excess lithium source available during the heating step to form NMC, leading to more complete lithiation of SC-LiNMC.

[0147] Example 9 Li 2 SC-LiNMCs prepared with 5% excess Li using an O lithium source SC-LiNMC was prepared in the same manner as described in Example 8, except that it contained LiNMC equivalent to 5% excess lithium content. 2 Except that 0.42 g of O (Alfa Aesar, 99%) was used as the lithium source.

[0148] The XRD pattern of the SC-LiNMC of Example 9 is shown in FIG. 2 Single-phase LiNi with structure 0.6 Mn 0.2 Co 0.2 O 2 This is a characteristic of

[0149] The SEM image of the SC-LiNMC of Example 9 is shown in Figure 30. It consists of aggregated single crystal grains. The average grain size determined from the SEM image was 1.73 ± 0.63 μm.

[0150] An electrode and cell were prepared from the SC-LiNMC of Example 9, and the first cycle voltage curve is shown in Figure 31. The first cycle reversible capacity of this sample was 169 mAh / g, and the ICE was 87%.

[0151] Without being bound by theory, it is believed that the higher RC and ICE of Example 9 compared to Example 7 is due to the use of Li 2 CO 3 Instead of Li 2 Because O was used, Li 2 O 2の This is believed to be due to the reduced amount of lithium lost through evaporation. In Example 7, Li 2 O 2 It is believed that due to evaporation of Li, there was not enough lithium present to fully lithiate the sample. 2 O 2 It is believed that the reduced lithium loss due to evaporation of LiNMC increased the amount of excess lithium source available during the heating step to form LiNMC, which in turn led to more complete lithiation of the SC-LiNMC of Example 9, which in turn led to the observed higher RC and ICE compared to the SC-LiNMC of Example 7.

[0152] Example 10 Li 2 CO 3 SC-LiNMCs prepared with 5% excess Li using a lithium source SC-LiNMC was prepared as follows: 2 g of the RS precursor particles of Example 1 was dissolved in 100 mL of LiN 0.6 Mn 0.2 Co 0.2 O 2 Li, which corresponds to a 5% excess lithium content, according to the Li:Ni:Mn:Co ratio expressed by 2 CO3 The resulting precursor particulate lithium source mixture was placed in an alumina crucible and heated in a tube furnace in air at 900° C. for 12 hours (this heating at 900° C. constitutes the LiNMC formation heating step). Finally, the SC-LiNMC product was ground in a mortar and pestle and passed through a 38 μm sieve.

[0153] The XRD pattern of the SC-LiNMC of Example 10 is shown in FIG. 2 Single-phase LiNi with structure 0.6 Mn 0.2 Co 0.2 O 2 This is a characteristic of

[0154] The SEM image of the SC-LiNMC of Example 10 is shown in Figure 33. It consists of aggregated single crystal grains. The average grain size determined from the SEM image was 3.8±1.2 μm.

[0155] An electrode and cell were prepared from the SC-LiNMC of Example 10, and the first cycle voltage curve of this cell is shown in Figure 34. The first cycle reversible capacity (RC) of this sample was 161.6 mAh / g, and the ICE was 86.2%.

[0156] Example 11 Biphasic precursor particles Using the same method as in Example 1, a compound of formula Ni 0.6 Mn 0.2 Co 0.2RS precursor particles having O were prepared. The RS precursor particles were then placed in an alumina crucible and heated at 700° C. in air for 5 hours. The XRD pattern of the resulting biphasic precursor particles is shown in FIG. 35. The XRD pattern is characteristic of a phase having a rock salt structure coexisting with a phase having a cubic spinel structure. The lattice parameter of the phase having a rock salt structure is 4.172 Å, which is consistent with NiO. This phase is therefore believed to be NiO or MO, where M is a combination of Ni and small amounts of Mn and / or Co. The grain size of the phase having a rock salt structure is 205 Å according to the result of applying the Scherrer equation to its maximum XRD peak. The phase having a cubic spinel structure has a lattice parameter of 8.2883 Å and a chemical formula of M' 3 O 4 where M' is a combination of Mn, Co, and optionally Ni, such as (Mn 0.5 Co 0.5 ) 3 O 4 The grain size of the phase with a cubic spinel structure is 250 Å according to the Scherrer equation applied to the maximum XRD peak.

[0157] An SEM image of the biphasic precursor particle of Example 12 is shown in Figure 36. It consists of primary particles with sizes between 2-8 μm. This is a completely different morphology compared to the RS precursor particle of Example 1, where the majority of the primary particles are submicron sized. Without being bound by theory, it is believed that the conversion of the RS precursor particle to the biphasic precursor particle involves the fusion of many primary particles, further improving the uniformity of the precursor particle.

[0158] Example 12 Li 2 CO 3 SC-LiNMCs prepared from biphasic precursor particles and 5% excess Li using a lithium source SC-LiNMC was prepared as follows: 2 g of the biphasic precursor particles of Example 11 was dissolved in water with a solution of the formula LiNi 0.6 Mn 0.2 Co 0.2 O 2Li, which corresponds to a 5% excess lithium content, according to the Li:Ni:Mn:Co ratio expressed by 2 CO 3 The resulting precursor particulate lithium source mixture was placed in an alumina crucible and heated in a tube furnace in air at 900° C. for 12 hours (this heating at 900° C. constitutes the LiNMC formation heating step). Finally, the SC-LiNMC product was ground in a mortar and pestle and passed through a 38 μm sieve.

[0159] The XRD pattern of the SC-LiNMC of Example 12 is shown in FIG. 2 Single-phase LiNi with structure 0.6 Mn 0.2 Co 0.2 O 2 This is a characteristic of

[0160] The SEM image of the SC-LiNMC of Example 12 is shown in Figure 38. It consists of aggregated single crystal grains. The average grain size determined from the SEM image was 2.6±0.7 μm.

[0161] An electrode and electrochemical test cell were fabricated from the SC-LiNMC of Example 12, and the first cycle voltage curve is shown in Figure 39. The first cycle reversible capacity of this sample was 165.2 mAh / g, and the ICE was 89.1%.

[0162] A plot of capacity versus cycle number for the cells of Examples 10 and 12 is shown in Figure 40. The cells of Examples 10 and 12 experienced a capacity fade of 33.2% and 16.7%, respectively, over 100 cycles. The higher reversible capacity, ICE, and capacity retention of the SC-LiNMC of Example 12 compared to Example 10 is likely due to the easier lithiation of the biphasic precursor particles used to prepare the SC-LiNMC of Example 12 compared to the RS precursor particles used to prepare the SC-LiNMC of Example 10.

[0163] (Example 13) RS precursor particles made from hydroxide raw component particles Example 13: Formula Ni 0.6 Mn 0.2 Co 0.2 The RS precursor particles with O are Ni(OH) 2 Powder (Sigma-Aldrich, -325 mesh, 99%) 3.02 g, Mn(OH) 2 Powder (City Chemical LLC, -60 mesh, 99%) 0.97 g, and Co(OH) 2 1.01 g of powder (Alfa Aesar, 99.7%) was prepared by grinding for 3 hours using an automatic grinding machine (Pulverisette 2 Mortar Grinder, Fritsch GmbH). The resulting mixture was placed in an alumina crucible and heated in a tube furnace under argon flow at 1000° C. for 12 hours. An alumina crucible filled with MnO powder as an oxygen getter was placed upstream of the tube furnace. The resulting RS precursor particles were ground with a mortar and pestle and passed through a 53 μm sieve. FIG. 41 shows the XRD pattern of the resulting RS precursor particles, which is characteristic of a phase-pure rock salt structure with a lattice parameter of 4.225 Å. The apparent lattice distortion was determined to be 0.146% by the Williamson-Hall method, indicating excellent compositional uniformity of this sample.

[0164] Figures 42a and 42b show SEM images of the RS precursor particles of Example 13. The sample consists of faceted primary crystallites. The average crystallite size determined from the SEM images was 1.5±0.5 μm.

[0165] Comparative Example 7 RS precursor particles made from cold-pressed oxide raw component particles RS precursor particles with the formula Ni0.6Mn0.2Co0.2O of Comparative Example 7 were prepared by grinding 3.03 g NiO (Sigma-Aldrich, -325 mesh, 99%), 0.96 g MnO (Aldrich, -60 mesh, 99%), and 1.01 g CoO (Alfa Aesar, 99.7%) raw material particles in a mortar and pestle by manual grinding. The resulting mixture was pressed into pellets at a pressure of about 56 kg / mm2 using a hardened steel die. The resulting cylindrical pellets with a diameter of 15 mm and a height of about 2-3 mm were then placed in an alumina crucible and heated at 1000 °C for 12 hours in a tube furnace under argon flow. An alumina crucible filled with MnO powder as an oxygen getter was placed upstream of the tube furnace. The resulting RS precursor particles were ground in a mortar and pestle and passed through a 53 μm sieve.

[0166] Figure 43 shows the XRD pattern of the produced RS precursor particles, characteristic of a phase pure rock salt structure with a lattice constant of 4.241 A. The apparent lattice distortion was determined to be 0.398% by the Williamson-Hall method, which is lower than that of the RS precursor particles of Comparative Example 1 (i.e., 0.413%), but exceeds the apparent lattice distortion value of 0.3%, indicating poor compositional uniformity in this sample, which is likely due to an insufficient grinding process.

[0167] Example 14 Cold pressed oxide raw material particles and Na 2 SO 4 RS precursor particles produced from flux Chemical formula Ni 0.6 Mn 0.2 Co 0.2 RS precursor particles of Example 14 having O were prepared using the same method as Comparative Example 7, except that the preparation did not include Na 2 SO 4Except that a flux was used and the raw material particle mixture was heated and then removed by washing. Specifically, the RS precursor particles of Example 14 were prepared by mixing raw material particles of NiO (Sigma-Aldrich, -325 mesh, 99%) 3.03 g, MnO (Aldrich, -60 mesh, 99%) 0.96 g, and CoO (Alfa Aesar, 99.7%) 1.01 g, and Na as a flux (raw material particle / flux ratio = 2). 2 SO 4 (Fisher Scientific, anhydrous, 99%) was prepared by grinding 2.5 g by hand grinding in a mortar and pestle. The resulting mixture was pressed into a hardened steel die at approximately 56 kg / mm 2 The mixture was pressed into pellets at a pressure of 1000°C. The resulting cylindrical pellets, 15 mm in diameter and about 2-3 mm in height, were then placed in an alumina crucible and heated in a tubular furnace at 1000°C for 12 hours under argon flow. An alumina crucible filled with MnO powder as an oxygen getter was placed upstream of the tubular furnace. After grinding in a mortar and pestle, the resulting particles were separated from the residual flux by washing with distilled water and then heated in air at 120°C for 24 hours. The resulting RS precursor particles were ground in a mortar and pestle and passed through a 53 μm sieve.

[0168] Figure 44 shows the XRD pattern of the produced RS precursor particles, characteristic of a phase pure rock salt structure with a lattice parameter of 4.242 Å. The apparent lattice distortion was determined by the Williamson-Hall method to be 0.246%, indicating excellent compositional uniformity for this sample. This is in contrast to Comparative Example 7, which was prepared in an identical manner except that no flux was used in the comparative example, resulting in a higher apparent lattice distortion value of 0.413%.

[0169] Figures 45a and 45b show SEM images of the RS precursor particles of Example 15. The sample consists of faceted primary crystallites. The average crystallite size determined from the SEM images was 2.2±0.8 μm.

[0170] Example 15 Cold pressed oxide raw material particles and MoO 3 RS precursor particles produced from flux Chemical formula Ni 0.6 Mn 0.2 Co 0.2 RS precursor particles of Example 15 having MoO were prepared using the same method as Comparative Example 7, except that the preparation did not contain MoO 3 Specifically, the RS precursor particles of Example 15 were prepared by mixing raw material particles of NiO (Sigma-Aldrich, -325 mesh, 99%) 3.03 g, MnO (Aldrich, -60 mesh, 99%) 0.96 g, and CoO (Alfa Aesar, 99.7%) 1.01 g, and MoO as a flux (raw material particle / flux ratio = 25). 3 A 0.2 g sample (Alfa Aesar, 99.5%) was prepared by grinding with a mortar and pestle by hand grinding. The resulting mixture was then crushed to approximately 56 kg / mm ​​using a hardened steel die. 2 The mixture was pressed into pellets at a pressure of 1000 MPa. The resulting cylindrical pellets, 15 mm in diameter and approximately 2-3 mm in height, were then placed in an alumina crucible and heated in a tube furnace at 1000 °C for 12 h under argon flow. An alumina crucible filled with MnO powder as an oxygen getter was placed upstream of the tube furnace. The resulting particles were crushed in a mortar and pestle and passed through a 53 μm sieve.

[0171] FIG. 46 shows the XRD pattern of the produced precursor particles, which is MoO 3 The sample shows characteristic of a single-phase rock-salt structure with a lattice constant of 4.240 Å, coexisting with flux. The apparent lattice distortion of the rock-salt phase was determined by the Williamson-Hall method to be 0.242%, indicating excellent compositional uniformity for this sample. This is in contrast to Comparative Example 7, which was prepared in an identical manner except that no flux was used in the comparative example, resulting in a higher apparent lattice distortion value of 0.413%.

[0172] Figures 47a and 47b show SEM images of the RS precursor particles of Example 16. The average grain size determined from the SEM images was 3.5±1.3 μm.

[0173] The foregoing examples show that precursor particles in the form of single-phase RS precursor particles with high compositional uniformity, as indicated by an apparent lattice distortion of less than 0.3%, can be synthesized by a method that includes grinding the raw component particles and then heating the resulting precursor particle mixture. The RS precursor particles can be converted to biphasic precursor particles by a heating step in air. The foregoing examples further demonstrate that RS precursor particles with high compositional uniformity, as indicated by an apparent lattice distortion of less than 0.3%, are useful for the synthesis of LiNMC and SC-LiNMC with desirable electrochemical properties of low voltage polarization, low capacity fade, and high initial coulombic efficiency. Even better electrochemical properties can be achieved when RS precursor particles with extremely high compositional uniformity, as indicated by an apparent lattice distortion of less than 0.2% or even lower, are utilized for the synthesis of LiNMC. It is further demonstrated that LiNMC with even better electrochemical properties can be formed by utilizing biphasic particles formed from RS precursor particles with high compositional uniformity, as indicated by an apparent lattice distortion of less than 0.3%. In contrast, LiNMC synthesized from RS precursor particles with less uniform composition, as indicated by apparent lattice distortion of more than 0.3%, has undesirable electrochemical properties of high voltage polarization, large capacity fade, and low initial coulombic efficiency.

[0174] All of the above U.S. patents, U.S. patent applications, foreign patents, foreign patent applications and non-patent publications referred to herein are hereby incorporated by reference in their entireties.

[0175] While particular elements, embodiments, and applications of the present invention have been shown and described, it will of course be understood that the invention is not limited thereto, as modifications may be made by those skilled in the art without departing from the spirit and scope of the present disclosure, particularly in light of the foregoing teachings, and such modifications are intended to be considered within the spirit and scope of the claims appended hereto.

Claims

1. Formula Li １＋ｘ [(Ni ｎ Mn ｍ Co ｃ ) １－ａ A ａ ] １－ｘ O ２ 1. A method for preparing lithium nickel manganese cobalt oxide particles having the formula: wherein -0.03≦x≦0.06, n+m+c=1, n≧0.05, m≧0.05, c≧0.05, A is a metal dopant, and 0≦a≦0.05, comprising the steps of: a) providing feedstock component particles having a molar ratio of Ni:Mn:Co of n:m:c, the feedstock comprising nickel-containing particles, manganese-containing particles, cobalt-containing particles, and optional dopant A-containing particles; b) grinding the feed component particles to form a homogenous feed particle mixture; c) heating the homogenous mixture of raw material particles from b) at a temperature greater than about 500° C. for a set time of at least about 1 hour, thereby forming a rock salt structure and a crystalline ... ｎ Mn ｍ Co ｃ ) １－ａ A ａ forming precursor particles having O; d) combining a predetermined amount of the precursor particles with a predetermined amount of a lithium source to form a precursor particulate lithium source mixture, the predetermined amount of the lithium source being equal to or greater than the stoichiometric amount required to make the lithium nickel manganese cobalt oxide particles; e) heating the precursor particulate lithium source mixture from d) at a lithiation temperature in an oxygen-containing atmosphere to produce lithium nickel manganese cobalt oxide particles; The method includes:

2. grinding the feed component particles to form a uniform feed particle mixture; obtaining samples from the feedstock particles at one or more time intervals during the grinding process; Heating the sample; and determining the structure of the heated sample by X-ray diffraction analysis; determining a feedstock grinding time based on a time interval that results in the heated sample having a single-phase rock salt structure with an apparent lattice distortion of less than about 0.3%; 10. The method of claim 1, comprising grinding the feedstock particles for a predetermined period of time determined by:

3. 10. The method of claim 1, wherein the nickel-containing, manganese-containing, and cobalt-containing particles are selected from the group consisting of metal oxides, metal hydroxides, metal carbonates, and mixtures thereof.

4. 4. The method of claim 3, wherein the nickel-, manganese-, and cobalt-containing particles are selected from the group consisting of NiO, MnO, and CoO.

5. 10. The method of claim 1, wherein the feedstock particles further comprise dopant A-containing particles selected from the group consisting of metal oxides, metal hydroxides, metal carbonates, and mixtures thereof.

6. 2. The method of claim 1, wherein n, m, and c are about 0.6, about 0.2, and about 0.2, respectively.

7. 2. The method according to claim 1, wherein the raw material grinder for grinding in step b) is a dry grinder.

8. 10. The method of claim 1, wherein the feedstock grinding time in step b) ranges from about 10 minutes to about 6 days.

9. 2. The method of claim 1, wherein the set temperature of c) is in the range of about 500°C to about 1600°C.

10. 10. The method of claim 1, wherein the set time of c) ranges from about 1 hour to about 12 hours.

11. 2. The method of claim 1, wherein the heating in step c) is carried out under an atmosphere selected from the group consisting of an inert gas, a low oxygen partial pressure gas, and a vacuum.

12. 2. The method of claim 1, wherein the lithium source is lithium carbonate, lithium hydroxide, or lithium oxide.

13. 10. The method of claim 1, wherein the amount of lithium source is about 0-30% greater than the stoichiometric amount required to make the lithium nickel manganese cobalt oxide particles.

14. 2. The method of claim 1, wherein the oxygen-containing atmosphere in e) is air or oxygen.

15. 2. The method of claim 1, wherein the lithiation temperature in e) is in the range of about 700-1000°C.

16. 3. The method of claim 2, wherein the homogeneity of the ground mixture is determined by X-ray diffraction analysis.

17. 10. The method of claim 1, further comprising the step of forming the precursor particulate lithium source mixture into a pellet prior to step e).

18. 20. The method of claim 17, further comprising the step of adding a flux to the precursor particulate lithium source mixture prior to step e).

19. The method of claim 1 further comprising the step of adding a flux to the feedstock particles of step a).

20. 3. The method of claim 2, further comprising determining the structure of the obtained sample by X-ray diffraction analysis prior to heating the obtained sample to confirm that the obtained sample consists essentially of a nickel-containing grain phase, a manganese-containing grain phase, a cobalt-containing grain phase, and an optional Dopant A-containing grain phase.

21. 10. The method of claim 1, further comprising, prior to step d), heating the precursor particles in an oxygen-containing atmosphere to transform the precursor particles from particles having a rock salt structure to biphasic particles consisting essentially of a rock salt phase and a cubic spinel phase.

22. the milling produces a homogenous feedstock particle mixture consisting essentially of a nickel-containing particle phase, a manganese-containing particle phase, a cobalt-containing particle phase, and an optional dopant A-containing particle phase; 2. The method of claim 1, wherein during the grinding step b), no chemical reaction occurs between the nickel-containing, manganese-containing, cobalt-containing, and optional dopant A-containing particle phases.

23. The method of claim 1 , wherein the precursor particles of step c) further comprise a metal phase.

24. 22. The method of claim 21 , wherein the rock salt and spinel phases of the biphasic precursor particles each have an average grain size greater than 100 Å.

25. Composition (Ni ｎ Mn ｍ Co ｃ ) １－ａ A ａ O １＋ｂ wherein n, m, c, and a are positive numbers; A is a metal dopant; n+m+c=1; n≧0.05; m≧0.05; c≧0.05; 0≦a≦0.05; and 0<b<0.33;

26. 26. The biphasic particle of claim 25, wherein the rock salt phase is NiO.

27. The cubic spinel phase has the chemical formula M ３ O ４ 26. The biphasic particle of claim 25 having the formula: where M is a mixture of Mn and Co.

28. 30. The biphasic particle of claim 27, wherein M further comprises Ni.

29. 26. The biphasic particle of claim 25, wherein the cubic spinel phase has a lattice parameter in the range of 8.1 Å to 8.4 Å.

30. Composition (Ni ｎ Mn ｍ Co ｃ ) １－ａ A ａ 0, wherein n, m, c, and a are positive numbers, A is a metal dopant, n+m+c=1, n≧0.05, m≧0.05, c≧0.05, and 0≦a≦0.05, and the particles essentially consist of a rock salt phase and have an apparent lattice distortion of less than 0.3%.

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