Process for preparing lithium transition metal oxides from elemental metal feedstocks and products thereof

Abstract

Disclosed herein are methods of preparing lithium transition metal oxide cathode materials for secondary batteries and other applications from elemental feedstocks and products thereof. The methods disclosed herein may include mixing at least one transition metal in elemental form with a lithium source in a dry solid state mixing process followed by a sintering step to form a lithium transition metal oxide cathode material.

Description

Technical Field

[0001] The present disclosure relates to the preparation of lithium transition metal oxide cathode materials for lithium ion batteries. Background Art

[0002] The development of high energy storage systems with lithium-ion (Li-ion) batteries as the main technology is the main driver of transportation electrification. After years of research on different chemical systems to maximize energy storage capacity, recent research has focused more on improving the cycle life and thermal safety of Li-ion batteries. Moreover, as the demand for Li-ion battery cells grows, it is crucial to innovate processes to produce battery materials at lower costs and with a smaller environmental footprint.

[0003] A typical secondary Li-ion battery cell includes a graphite negative electrode, a lithium metal oxide positive electrode, a polymer separator, an organic electrolyte, and a shell. Among them, the lithium metal oxide positive electrode material is a key component that determines the energy storage capacity and battery cost. Among several types of lithium metal oxide materials, lithium nickel manganese cobalt oxide, known as "NMC", is one of the most preferred cathode materials used in commercial battery cells.

[0004] The most common industrial approach for preparing NMC includes multiple lengthy steps. The first step is usually to prepare a mixed metal hydroxide precursor (MH) using a coprecipitation process, which mainly contains metal Ni, Mn, Co and possible dopant A. The molar ratio of the elements is controlled in this step to achieve the desired composition. Typically, aqueous metal salts are precipitated in a NaOH solution in the presence of some chelating agents to obtain a uniform element mix. In the subsequent steps, a large amount of water is introduced to wash the synthesized metal hydroxide precipitate, which is then dried in a high-temperature oven (typically, a production of 6.5 tons / day NMC produces 99,000L of wastewater that needs to be treated and stored). This step consumes a large amount of water and energy alone. The second step uses some mechanical mixing machines to mix the metal hydroxide precursor with a lithium compound (such as LiOH or Li2CO3). The third step is to calcine the above mixture in an atmosphere containing oxygen to form a lithiated metal oxide. The fourth step uses a particle size classifier to collect products within the desired size range. Sometimes, a mill is used to break up agglomerates. The fifth step is a post-processing or finishing step. In this step, the product is washed, dried and re-sintered at high temperature. Washing may include a surface coating step, where the washing solution contains some chemicals that form a protective coating on the cathode surface after drying and re-sintering.

[0005] Atomic mixing of transition metals (TM) can be achieved in MH precursors using a well-known co-precipitation process. Good element mixing is essential for achieving high-performance single-phase NMC materials. However, the co-precipitation process results in the need to treat large amounts of wastewater to meet environmental regulations. In addition, soluble transition metal salts must be used as raw materials in the co-precipitation process. It is worth mentioning that insoluble transition metal compounds (such as oxides, hydroxides, carbonates, or even transition metal powders) are cheaper and easier to obtain. Therefore, alternative methods for producing NMC without using a co-precipitation process are important for the sustainable production of cathode materials.

[0006] In recent years, some studies have proposed some methods for preparing NMC and other cathode materials without using traditional methods.

[0007] WO2021040931A1 application describes a method for preparing lithium nickel manganese cobalt oxide (NMC) particles using a dry solid-state process. Ni compounds, Mn compounds and Co compounds selected from oxides, hydroxides and carbonates are mixed with a Li source (Li2O, LiOH, Li2CO3) by dry impact grinding to form precursor particles before calcination. Ni, Mn and Co in the form of metal powders are not included as raw materials.

[0008] US8591860B2 application discloses a method for producing lithium metal oxides. A raw material mixture is prepared by mixing a lithium compound, elemental Ni or a Ni compound, other TM compounds and a reaction accelerator made of a compound selected from one or more elements, carbonates, sulfates and chlorides, wherein the one or more elements are selected from Na, K, Rb, Cs, Ca, Mg, Sr and Ba. A reaction accelerator is required to improve reactivity during calcination, adjust the surface area, and produce a stable lithium mixed metal oxide under a calcination atmosphere containing a higher concentration of CO2 than in air. The calcination step is carried out in a gas furnace using a flame as a heat source. A mixture of combustion gas and oxygen is used to supply the gas furnace.

[0009] CN1326232A application discloses a method for preparing lithium manganese oxide with a spinel structure. A precursor is prepared by dissolving a mixture of a Li salt and a Mn source from electrolytic manganese dioxide, chemical manganese dioxide or high-purity manganese metal in an organic acid solution (acetic acid and / or oxalic acid and / or citric acid) using a wet high-speed mixing method. After evaporating the above precursor solution to form a gel precursor, it is dried and calcined.

[0010] US20210359300A1 and US20220064019A1: The first application describes "a method for forming a lithium-ion metal oxide and a battery comprising the lithium-ion metal oxide. The method includes reacting at least one metal in elemental form with a carboxylate to form a metal carboxylate, and heating the metal carboxylate to form the lithium-ion metal oxide". The second application provides a "method for forming a lithium-ion cathode material. The method includes reacting an elemental metal with a polycarboxylic acid to form an oxide precursor and heating the oxide precursor to form a lithium-ion cathode material. In a preferred embodiment, the elemental mixture contains at least two of Ni, Mn, Co and Al". Both applications require the use of acid-based compounds, such as oxalic acid, citric acid, carboxylic acid, nitric acid, etc., to form a metal carboxylate complex with a metal in elemental form. The lithium metal oxide precursor slurry is dried to remove the solvent and then sintered in a furnace to form a lithium-ion metal oxide having a layered structure or a spinel structure. Summary of the invention

[0011] Embodiments disclosed herein describe methods for preparing lithium transition metal oxide cathode materials from elemental metal raw materials using a dry solid-state mixing method. Mixed metals and lithium sources in elemental form can be directly converted into lithium transition metal precursors with a wide range of stoichiometric compositions. In addition, a sintering process on the precursor can produce lithium transition metal oxide powders having a single phase without lithium impurities. Embodiments disclosed herein provide a more streamlined, cost-effective, and environmentally friendly method than conventional wet methods used in the manufacture of lithium transition metal oxide materials.

[0012] In some embodiments, the method does not require the addition of any reaction promoter or seed crystal during the mixing process. Only the raw metal raw materials in elemental form are mixed with the Li source, and then sintered at high temperature to form a single-phase lithium transition metal oxide material with good ordered crystallinity.

[0013] Specifically, in some embodiments, the method is used to form a compound having the empirical formula Li 1+x [(Ni n Mn m Co c Al a ) 1-y A y ] 1-x O 2 A lithium transition metal oxide positive electrode material, wherein -0.2≤x≤0.2; n+m+c+a=1; n≥0; m≥0; c≥0; a≥0; A is a metal dopant; and 0≤y≤0.05, the method comprising:

[0014] a) According to the formula Li 1+x[(Ni n Mn m Co c Al a ) 1-y A y ] 1-x O 2 A precursor mixture is prepared by combining stoichiometric amounts of one or more lithium compounds, one or more Ni elements or Ni compounds, one or more Mn elements or Mn compounds, one or more Co elements or Co compounds, one or more Al elements or Al compounds and / or one or more metal dopant elements or metal dopant compounds; wherein:

[0015] - at least one transition metal in elemental form and chosen from Ni, Mn and Co, to form said precursor;

[0016] - The compound of the remaining metal is selected from the group consisting of oxides, hydroxides, oxyhydroxides, carbonates, sulfates, nitrates, acetates and combinations thereof.

[0017] -Li compound is selected from lithium carbonate, lithium oxide, lithium hydroxide, lithium acetate, lithium chloride, lithium fluoride, lithium nitrate, lithium sulfate or a mixture thereof;

[0018] b) heating the precursor to produce a lithium transition metal oxide cathode material having a single-phase structure.

[0019] In some embodiments, at least one metal in elemental form is mixed with other metal compounds (e.g., oxides, carbonates, sulfates, etc.) and a lithium source. This creates a wide range of options for raw material selection based on the cost, availability, and properties of each raw material. Dopants selected from elemental forms of Na, B, Al, Mg, Zr, Nb, Fe, Si, P, Mo, Ba, Sr, Ca, Zn, Cr, V, W, Nd, La, Cs, Ta, Ce, Cu, Eu, Ti, Sn, Sb, Pb, Bi, or Rb, or compounds thereof, can also be added during the mixing process to change the properties of the lithium transition metal oxide.

[0020] The use of metals in elemental form can eliminate the requirement for suppliers to purify metal compounds, thus simplifying the overall manufacturing process. Dry solid state mixing also produces no wastewater and allows the use of Class 2 insoluble feedstocks, making the overall process more efficient.

[0021] During the lithiation step, the lithium source added to the mixing process can be LiOH, LiOH·H 2 O. Li 2 CO 3 , Li 2 O and mixtures thereof, wherein the amount of lithium added is in the stoichiometric formula Li 1+x[(Ni n Mn m Co c Al a ) 1-y A y ] 1-x O 2 Alternatively, the lithium source may be added in a single step mixing process with all transition metal raw materials, or added later after all transition metal raw materials are mixed.

[0022] In the mixing process, dry solid-state mixing can be carried out using mechanical mixing techniques, including but not limited to ball milling, bead milling, impact milling, automatic grinding machine, high-speed mixer, grinding, acoustic mixer, mechanical melting or blending machine. Depending on the particle size of the raw material, impact grinding or ball milling may be required to further reduce the particle size and produce uniform mixing. For ball milling, the selection and size of the medium can be changed based on the allowed metal impurities, material hardness and grinding efficiency. Optionally, wet mixing using a small amount of water or ethanol (liquid byproducts less than at least 90% of conventional processes) is carried out to promote grinding and material combination. In the case of using a small amount of liquid, the weight ratio of solid: liquid is greater than 5: 1, greater than 9: 1, greater than 10: 1, greater than 12: 1, greater than 15: 1, greater than 20: 1. In a preferred embodiment, the amount of liquid is sufficient to produce a gel or slurry, but not enough to cause the solid to be suspended in the liquid.

[0023] The mixed lithium transition metal oxide precursor is calcined in a furnace under pure oxygen, inert gas, dry air, air, or a combination thereof. Calcination can be performed in a single step heating scheme to maximize the temperature, or in multiple steps (with the temperature maintained in between). The calcination temperature including temperature maintenance is 450° C. to 1000° C., with a total sintering time of 10 hours to 100 hours. In the case where the raw materials are dense or large and where the Li source has low reactivity, such as in Li 2 CO 3 In this case, multi-step heating is preferred.

[0024] In some embodiments, post-modification (e.g., reheating) is performed to increase crystallinity, reduce cation mixing, reduce lithium residues, smooth the surface of the lithium transition metal oxide product, or a combination thereof. Reheating can be performed at a temperature greater than 500° C. for greater than 1 hour under pure oxygen, inert gas, dry air, air, or a combination thereof. The choice of atmosphere depends on moisture sensitivity, the amount of impurities, and the stoichiometric composition of the lithium transition metal oxide product.

[0025] The calcined lithium transition metal oxide may contain some particle agglomerates, which can be crushed by an impact mill, a jet mill or a grinder. In at least one embodiment, deagglomeration is performed to increase the uniformity of the particles, produce a unimodal particle size distribution, and reduce the grain boundaries between the particles. This can increase the electrode packaging efficiency and reduce the possibility of battery failure usually caused by cracks between the grain boundaries of the particles.

[0026] The lithium transition metal oxide product can be prepared using elemental metal raw materials with a single-phase structure with high crystallinity. The well-developed crystal structure is represented by the percentage of cation mixing below 6%; the amount of Ni in the Li layer. Since the material with low cation mixing is not prone to phase change and cracking during cycling. When the material is assembled into a battery cell, low cation mixing is beneficial to rate capability and cycle stability.

[0027] The lithium transition metal oxide product can be used as a positive electrode material for secondary batteries for a wide range of commercial applications. Different stoichiometric compositions can impart different energy densities, safety features, and cycle stability suitable for various applications. The conversion of elemental metal raw materials to lithium transition metal oxide products disclosed in the embodiments herein is a dry and simplified process that replaces the complex wet methods used in the cathode material manufacturing industry. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 SEM images of the N6-1 material, the N6-2 material, the N6-3 material, and the N6-4 material of Example 1 are shown.

[0029] Figure 2 XRD patterns of the N6-1 material, the N6-2 material, the N6-3 material, and the N6-4 material of Example 1 are shown.

[0030] Figure 3 a shows the first cycle charge and discharge curve of a button cell made of N6-3 material at C / 20.

[0031] Figure 3 b shows the capacity retention of button cells made of N6-3 material.

[0032] Figure 4 XRD patterns of the N6-5 material and the N6-6 material of Example 2 are shown.

[0033] Figure 5 SEM images of the N8-1 material and the N8-2 material of Example 3 are shown.

[0034] Figure 6 XRD patterns of the N8-1 material and the N8-2 material of Example 3 are shown.

[0035] Figure 7a shows the first cycle charge and discharge curve of a button cell made of N8-1 material at C / 20.

[0036] Figure 7 b shows the first cycle charge and discharge curve of the button cell made of N8-2 material at C / 20.

[0037] Figure 7 c shows the capacity retention of button cells made of N8-1 material.

[0038] Figure 7 d shows the capacity retention of button cells made of N8-2 material.

[0039] Figure 8 a and Figure 8 b shows SEM images of N8-3 material at different magnifications of Example 4.

[0040] Figure 8 c shows the EDX elemental map of Ni of N8-3 material.

[0041] Figure 8 d shows the EDX elemental map of Co of N8-3 material.

[0042] Figure 8 e shows the EDX elemental map of Mn of N8-3 material.

[0043] Figure 8 f shows the EDX elemental map of Al of N8-3 material.

[0044] Fig. 9 The XRD pattern of the N8-3 material of Example 4 is shown.

[0045] Fig.10 a and Fig.10 b shows SEM images of N8-4 material at different magnifications of Example 5.

[0046] Fig.10 c shows the EDX elemental map of Ni of N8-4 material.

[0047] Fig.10 d shows the EDX elemental map of Co of N8-4 material.

[0048] Fig.10 e shows the EDX elemental map of Mn of N8-4 material.

[0049] Fig.11 The XRD pattern of the N8-4 material of Example 5 is shown. DETAILED DESCRIPTION

[0050] Embodiments of the present disclosure may relate to the production of lithium transition metal oxide electrode materials and products thereof. In preferred embodiments, the method is a dry or substantially dry process. The method may allow for the production of lithium transition metal oxide electrode materials with minimal or no solvent or minimal or no wastewater byproducts.

[0051] The production of lithium transition metal oxide electrode materials can be carried out by mixing a precursor mixture in the absence of a solvent and then heating the precursor mixture. The precursor mixture can be a combination of at least two of lithium, nickel, manganese, cobalt, aluminum and a dopant. The mixed and heated precursor mixture generally produces a material having the formula Li 1+x [(Ni n Mn m Co c Al a ) 1-y A y ] 1-x O 2 A lithium transition metal oxide electrode material, wherein: -0.2≤x≤0.2; n+m+c+a=1; n≥0; m≥0; c≥0; a≥0; A is a metal dopant; and 0≤y≤0.05. The dopant of the precursor mixture can be selected from Na, B, Al, Mg, Zr, Nb, Fe, Si, P, Mo, Ba, Sr, Ca, Zn, Cr, V, W, Nd, La, Cs, Ta, Ce, Cu, Eu, Ti, Sn, Sb, Pb, Bi, Rb or a mixture thereof.

[0052] In any embodiment disclosed herein, the metal used can be an elemental metal. In at least one embodiment, the transition metals of Ni, Mn, Co and Al are provided in elemental form. In at least one embodiment, all transition metals are provided in elemental form. The elemental form of the metal can include a metal or its oxide composed of a single chemical element. The elemental form can exclude cationic salts / anionic salts of metal compounds, or compounds containing metals in an oxidized state. In embodiments disclosed herein, the metal in elemental form can be substantially free of other chemical elements.

[0053] The metal in elemental form can include the original elemental metal. In embodiments herein, the elemental metal can be a sufficiently pure or substantially pure metal. The purity of the metal can be at least 50% purity, at least 60% purity, at least 70% purity, at least 80% purity, at least 90% purity, at least 95% purity, or at least 99% purity. The metal can be provided in a sufficiently pure form, such as Class 2 raw materials. The metal can be provided as an insoluble raw material.

[0054] In any of the embodiments disclosed herein, the precursor mixture can be heated with or without holding and with or without post-modification or reheating. Heat treatment of the precursor mixture can be used to oxidize the precursor mixture and produce the structure of the lithium transition metal oxide electrode material. The heating of the precursor mixture can be a high temperature sintering step. The sintering step can be carried out in the presence of oxygen. Alternatively, the sintering step can be carried out in an inert atmosphere, oxygen, a low oxygen partial pressure gas, dry air or air. The inert atmosphere can be composed of an inert gas (e.g., helium, argon, neon) or in nitrogen (N 2 ) is present. The sintering of the lithium precursor can be carried out in a substantially anhydrous environment. The sintering temperature can be increased to a melting temperature exceeding at least one metal in the precursor solution. For example, sintering can be carried out above the melting point of lithium or aluminum. The sintering temperature in any embodiment of this invention can be greater than 500 degrees Celsius, greater than 550 degrees Celsius, greater than 600 degrees Celsius, greater than 650 degrees Celsius, greater than 700 degrees Celsius, greater than 750 degrees Celsius, greater than 800 degrees Celsius, greater than 900 degrees Celsius or greater than 1000 degrees Celsius. The post-modification reheating temperature can also be within the temperature range of more than 500 degrees Celsius disclosed above. The heating of the precursor can be about 1-150 hours, about 5-120 hours, about 10-100 hours, or at least 5 hours.

[0055] In any embodiments disclosed herein, the mixing of the precursor solutions can be carried out in the absence of solvents. The mixing can be carried out in the absence of water, resulting in a mixing process that does not produce wastewater as a byproduct. In any embodiments disclosed herein, the substantially anhydrous environment can be substantially free of liquid water or liquid solvents. The liquid solvent can be a polar solvent or a non-polar solvent, such as an organic solvent. In embodiments herein, the process can also exclude the use of acidic or alkaline solutions.

[0056] Dry mixing can be carried out according to any dry mixing method known in the art, as long as the precursor solution can be mixed in the absence of a liquid solvent. Examples of suitable dry mixing techniques can be ball milling, automatic grinding, impact grinding, high-speed mixing, grinding, acoustic mixing, mechanical fusion or blending. Mixing can be carried out using fluidized or pneumatic processes or combined with fluidized or pneumatic processes. Mixing can also be carried out at high temperatures.

[0057] The various procedures of the methods disclosed in the embodiments herein can be combined together or divided into two different steps. For example, lithium can be added to the precursor solution or transition metal and / or dopant in a single lithiation operation, or the addition of lithium can be performed stepwise in two mixing steps. Lithium can also be added in an amount that exceeds the other metals in the precursor solution. Depending on the stoichiometric ratio, lithium can exceed the other elements by less than 40%, less than 30%, less than 20%, less than 15%, less than 10%, less than 5% or less than 1%.

[0058] The stoichiometric ratios disclosed in any of the embodiments herein may be ratios that are not integers. For example, in at least one embodiment, the stoichiometric ratios may be based on the formula LiNi 0.6 Mn 0.2 Co 0.2 O 2 、LiNi 0.83 Mn 0.06 Co 0.11 O 2 or LiNi 0.8 Mn 0.1 Co 0.1 O 2 To describe the lithium transition metal oxide electrode material produced under the present disclosure, wherein Li and Ni and Mn and Co and O 2 The ratio is not described by an integer, but by a fraction or decimal. In some cases, the subscript of the formula may be multiplied by a value to obtain an integer subscript, but the stoichiometric ratio of the chemical elements in the lithium transition metal oxide electrode material will remain the same.

[0059] The lithium transition metal oxide electrode material in any embodiment disclosed herein can be incorporated into a battery. The battery can be a lithium ion battery, and the lithium transition metal oxide electrode material can be introduced into the cathode of the battery as an active material. The battery can contain additional components, such as liquid or solid electrolytes, membranes, anode active materials, current collectors, and supporting additives (such as binders and conductivity enhancers for anode and cathode materials), as well as structural features, such as battery housings. The battery can be a lithium ion battery. In any embodiment disclosed herein, the battery anode active material can be optimized with a lithium transition metal oxide electrode material to produce the highest electrochemical cell potential. The components of the battery can be substantially pure and optimized to reduce side reactions, such as chemical dendrites, during the charging and discharging process of the electrochemical cell.

[0060] The lithium transition metal oxide electrode material disclosed in any embodiment of the present invention can be introduced into the cathode of the battery as an active material. The lithium transition metal oxide electrode material can be introduced via a dry or wet process. For example, the lithium transition metal oxide electrode material can be applied to the current collector via a binder with or without pressing during the application process.

[0061] The lithium transition metal oxide electrode material disclosed in the embodiments herein can be a single-phase layered O3 phase. The O3 single-phase O3 structure can be free of Li impurities. The advantage of the O3 structure is that it has high conductivity, which is a key property of cathode materials. Electrical conductivity is a measure of how well a material can conduct electricity, and high conductivity is important in the cathode because it allows electrons to flow easily through the material, thereby achieving efficient charge transfer. The O3 structure is also known for structural stability, which enables it to resist damage from external factors (such as heat and stress). This stability allows cathode materials with O3 structures to maintain their performance over long periods of time, even in demanding applications.

[0062] The methods and products described in the embodiments herein are superior to the conventional methods of the prior art. The embodiments described herein provide methods for producing lithium transition metal oxide electrode materials in the absence of solvents, reducing the negative environmental impacts of excessive wastewater and soluble byproducts. In addition, the materials provided in the precursor mixture can be produced from cost-effective materials, such as elemental metals, metal compounds and lithium salts (e.g., lithium carbonate, lithium oxide, lithium hydroxide, lithium acetate, lithium chloride, lithium fluoride, lithium nitrate, lithium sulfate). The wide variety of precursor materials (e.g., elemental materials or chemical salts and compounds) that can be provided in the precursor mixture can make the method for producing lithium transition metal oxide electrode materials more simplified, environmentally friendly and cost-effective.

[0063] The following is exemplary in nature to better illustrate the present invention and is not limiting in scope, application, or use.

[0064] Material characterization

[0065] Scanning electron microscopy (SEM) images and energy dispersive X-ray spectroscopy (EDX) mapping images were taken using a Phenom XL G2 Desktop SEM in backscattered electron mode at an accelerating voltage of 15 kV. The powder samples were prepared by adhering to the sample post using conductive carbon tape.

[0066] The X-ray diffraction (XRD) pattern of the powder was measured by a Bruker D8 Advance diffractometer with a Cu Kα X-ray source and a diffraction beam monochromator. The measured XRD pattern was Rietveld refined using Rietica software to quantify the amount of Ni in the cation mixing:Li layer.

[0067] Cell preparation and electrochemical evaluation

[0068] The electrode slurry was prepared by mixing the active material, carbon black (Imerys / Timcal SuperP) and polyvinylidene fluoride (PVDF, Solvay Solef 5130) in a weight ratio of 0.94:0.04:0.02 in N-methyl-2-pyrrolidone (NMP, Fisher Scientific, 99.9%) using a planetary mixer, with a solid content of 50%. The slurry was coated onto a 15 μm aluminum foil sheet using a doctor blade method and dried in air on a 90°C drying table, and then finally dried overnight in a vacuum oven at 100°C to 120°C. The dried electrode was pressed using a calender roller and punched with a 13.00 mm diameter. The surface active mass loading was about 18-22 mg / cm 2 A CR2032 button-type housing was used with one active electrode, a Li foil counter electrode, two separators (Celgard 2500), and 100 μL of 1.2 M LiPF in a solution of ethylene carbonate:ethylmethyl carbonate:dimethyl carbonate (EC:EMC:DMC (25:5:70 wt %), CapChem) electrolyte. 6 The coin cells were fabricated in an Ar-filled glove box. Galvanostatic cycling tests were performed at a controlled temperature of 25°C using a NOVONIX ultra-high precision coulometric measurement system.

[0069] Example 1. NMC622 made from all elemental metals using a high speed mixer.

[0070] The LiNi 0.6 Mn 0.2 Co 0.2 O 2 Ni powder, Mn powder, Co powder and 5% excess Li 2 CO 3 The LiNi of this example was prepared by mixing at 750 rpm for 1.5 h. 0.6 Mn 0.2 Co 0.2 O 2 (NMC622). The mixed powders were then transferred to an alumina crucible and heated in a tube furnace at different sintering temperatures and atmospheres for 20 h. Table 1 shows the sintering temperatures at 920 °C in O 2 (N6-1), at 940℃ in O 2 (N6-2), at 960℃ in O 2List of samples heated at 600°C (N6-3) and at 940°C in air (N6-4). All samples were heated at 600°C for 3 h before reaching the final sintering temperature, which was held for 20 h and then cooled to room temperature. Heating and cooling rates of 10°C / min and 1°C / min were used, respectively. Figure 1 All samples were shown to have a single crystal morphology with a smooth surface. As the sintering temperature increased, the material became less agglomerated. Samples prepared in air ( Figure 1 d) shows slightly larger particle size and more particle agglomeration. Figure 2 XRD patterns of all samples with pure single-phase layered O3 phase without Li impurities are shown. A clear peak separation between (108) / (110) at 65° can be observed in all samples, indicating a very high degree of well-ordered crystallinity. As listed in Table 1, cation mixing varies between 2.5% and 5.0%. Figure 3 Examples of the electrochemical performance of the N6-3 material are shown. Figure 3 a shows the 2.8V to 4.5Vvs.Li + The first cycle charge-discharge curve tested at C / 20 between 1.5V and 2.5V. A reversible discharge capacity of 189.5mAh / g can be obtained, of which the irreversible capacity is 11.42%. Figure 3 b shows the constant current charge and discharge cycles of the N6-3 half-cell tested at C / 20 for 2 cycles, followed by 25 cycles at C / 5, and 2 cycles at C / 20. After 25 cycles, the C / 5 capacity retention rate was about 85.5%.

[0071] Table 1

[0072] sample Temperature(℃) Time (h) atmosphere %Ni / Li N6-1 920 20 oxygen 5.02 N6-2 940 20 oxygen 4.26 N6-3 960 20 oxygen 2.50 N6-4 940 20 Air 2.65

[0073] Example 2. Post-modification of NMC622 made from all elemental metals using an automated mill.

[0074] In this example, NMC622 was prepared by grinding in an automatic mill with LiNi 0.6 Mn 0.2 Co 0.2 O 2 Ni powder, Mn powder, Co powder and 5% excess LiOH·H 2 O was mixed for 20 min to form a homogeneous mixture. The mixed powder was then transferred to an alumina crucible and heated in a tube furnace at 0 2 The sample was heated at 600°C for 3 h and then at 940°C for 20 h to form N6-5. Sample N6-5 was removed from the tube furnace after cooling to room temperature and ground manually using a mortar and pestle. The sample was heated in the tube furnace for post-modification and quenched at 02 The sintering conditions are listed in Table 2. Figure 4 a shows the XRD of N6-5 after the first heating step. In addition to the O3 lamellar phase, peak broadening and a Li impurity peak at about 33° can be observed, indicating that the material is not a pure phase and the lithiation reaction is incomplete. Figure 4 b shows the XRD of sample N6-6 after reheating at 940°C for 12h. The intensity of the (003) plane at 18° and the (104) plane at 43° increased significantly and the (108) / (110) plane at about 65° was clearly separated without peak broadening, indicating that the N6-6 material became a pure lamellar phase. The cation mixing of the N6-6 material was 4.16%, similar to that of the N6-6 material sintered at the same temperature with Li 2 CO 3 Prepared N6-2 material.

[0075] Table 2

[0076] sample %LiOH·H2O First step heating Step 2 Heating atmosphere %Ni / Li N6-5 Overdose 5% 940C 20h - oxygen - N6-6 Overdose 5% 940C 20h 940C 12h oxygen 4.16

[0077] Example 3. NMC811 made from all elemental metals using an automated grinding machine.

[0078] In this example, NMC811 was prepared by grinding with LiNi in an automatic grinding machine. 0.8 Mn 0.1 Co 0.1 O 2 Ni powder, Mn powder, Co powder and Li 2 CO 3 Mix for 20 min to form a homogenous mixture. 2 CO 3 To form the N8-1 sample, 5% excess Li 2 CO 3 The N8-2 sample was formed as listed in Table 3. The mixed powder was transferred to an alumina crucible and heated in a tube furnace at 600°C for 3 h, 920°C for 20 h, and 870°C for 5 h, and then heated in an O 2 The heating rate and cooling rate were 10℃ / min and 1℃ / min respectively. Figure 5 SEM images of N8-1 and N8-2 are shown, indicating that the synthesized powders have a single crystalline morphology with a smooth surface and clear facets. Figure 6XRD patterns of N8-1 material and N8-2 material are shown. Both samples show a well-developed layered structure with clear (108) / (110) peak separation, indicating very high crystallinity. No lithium impurities were observed. Both N8-1 material and N8-2 material show very small amounts of cation mixing, 1.29% and 1.81%, respectively. Figure 7 a and Figure 7 b shows the N8-1 material and N8-2 material at 2.8V to 4.3V vs. Li / Li + The first cycle charge-discharge curve tested at C / 20. N8-1 and N8-2 can obtain high reversible discharge capacities of 191.1 mAh / g and 190.5 mAh / g, and irreversible capacities of 13.36% and 12.76%, respectively. Both samples also show very small overpotentials during the initial charge process, as well as small voltage hysteresis, indicating that the material impedance is low. Figure 7 c and Figure 7 d shows that the N8-1 half-cell and the N8-2 half-cell were charged at C / 20 for 2 cycles, then at C / 5 for 25 cycles, and then 2 cycles of constant current charge and discharge cycles were checked at C / 20. The C / 5 capacity retention rates after 25 cycles were 93.56% and 93.90%, respectively.

[0079] Table 3

[0080] sample <![CDATA[%Li 2 CO 3 ]]> Temperature(℃) Time (h) atmosphere %Ni / Li N8-1 Overdose 1% 920 20 oxygen 1.29 N8-2 Overdose 5% 920 20 oxygen 1.81

[0081] Example 4. Using an automatic grinding machine to grind Ni elemental metal, Co elemental metal, Mn elemental metal and Al 2 O 3 Made of NMCA.

[0082] Ni powder, Mn powder, Co powder, Al 2 O 3 Powder and 1% excess Li 2 CO 3 Take Li(Ni 0.8 Mn 0.1 Co 0.1 ) 0.99 Al 0.01 O 2 The NMCA powder was synthesized by mixing the stoichiometric ratio of 200 μg / ml in an automatic grinder for 20 min to form a homogeneous mixture. The mixed powder was transferred to an alumina crucible and heated in a tube furnace at 600 °C for 3 h, 920 °C for 20 h, and 870 °C for 5 h, and then at 0 °C for 1 h. 2 The mixture was cooled to room temperature under an atmosphere to form N8-3. Figure 8 a and Figure 8b shows SEM images of N8-3 material at different magnifications. Uniform single crystal morphology is observed without agglomeration. The material has a smooth surface and clear facets. Figure 8 c to Figure 8 f shows EDX elemental mapping images of Ni, Co, Mn and Al, respectively. All elements show uniform elemental distribution in all particles, even with only 1 mol% Al. This confirms the successful synthesis and lithiation of Ni-rich cathodes made from elemental metal feedstocks. Fig. 9 The XRD pattern of the N8-3 material with a pure single layered O3 phase without Li impurities is shown. A clear peak separation between (108) / (110) at 65° can be observed, indicating a very high and well-ordered crystallinity. The cation packing calculated by Rietveld refinement is 1.61%.

[0083] Example 5. NMC811 made of elemental metals mixed with metal compounds (NiO+Mn+Co).

[0084] In this example, NMC811 was prepared by grinding with LiNi in an automatic grinding machine. 0.8 Mn 0.1 Co 0.1 O 2 NiO powder, Mn powder, Co powder and 1% excess Li 2 CO 3 The mixed powder was transferred to an alumina crucible and heated in a tube furnace at 600 °C for 3 h, 920 °C for 20 h, and 870 °C for 5 h, and then at O 2 The mixture was cooled to room temperature under atmosphere to form N8-4. Fig.10 a and Fig.10 b shows SEM images of N8-4 material at different magnifications. A uniform single crystalline morphology is observed without agglomeration or incompletely lithiated particles. The cathode powder exhibits a smooth surface and clear facets. Fig.10 c to Fig.10 e shows the EDX element mapping of Ni, Co and Mn respectively. All elements are evenly distributed throughout the particle. Fig.11 The XRD pattern of the N8-4 material with a pure single layered O3 phase without Li impurities is shown. A clear peak separation between (108) / (110) at 65° can be observed, indicating a very high and well-ordered crystallinity. The cation packing calculated by Rietveld refinement is 1.75%.

[0085] Alternatives

[0086] Therefore, some aspects described herein involve the following numbered alternatives:

[0087] 1. A method for preparing a lithium transition metal oxide positive electrode material for a secondary battery, wherein the lithium transition metal oxide positive electrode material has an empirical formula (1) Li 1+x [(Ni n Mn m Co c Al a ) 1-y A y ] 1-x O 2 ,in:

[0088] -0.2≤x≤0.2;

[0089] n+m+c+a=1;

[0090] n≥0; m≥0; c≥0; a≥0;

[0091] A is a metal dopant;

[0092] 0≤y≤0.05;

[0093] The method comprises:

[0094] (A) preparing a precursor mixture by combining stoichiometric amounts of one or more lithium compounds according to formula (1), wherein:

[0095] - at least one transition metal in elemental form and selected from Ni, Mn and Co to form a precursor mixture;

[0096] - the compound of the remaining metal is selected from oxides, hydroxides, oxyhydroxides, carbonates, sulfates, nitrates, acetates and combinations thereof;

[0097] - the one or more Li compounds are selected from lithium carbonate, lithium oxide, lithium hydroxide, lithium acetate, lithium chloride, lithium fluoride, lithium nitrate, lithium sulfate and mixtures thereof; and

[0098] (B) heating the precursor mixture to produce a lithium transition metal oxide cathode material.

[0099] 2. The method according to alternative 1, wherein the lithium transition metal oxide positive electrode material has a single-phase structure.

[0100] 3. The method of alternative 1 or any one of the preceding alternatives, wherein the lithium transition metal oxide cathode material is a single phase crystal structure.

[0101] 4. The method according to alternative 1 or any one of the preceding alternatives, wherein the lithium transition metal oxide positive electrode material is a single-phase structure without lithium impurities.

[0102] 5. A method according to alternative 1 or any one of the preceding alternatives, wherein the step of preparing the precursor mixture is carried out by dry mixing or wet mixing or a combination thereof, wherein the dry mixing uses a ball mill, an automatic grinder, an impact mill, a high-speed mixer, grinding, an acoustic mixer, a mechanical fusion machine or a blender, and the wet mixing uses wet grinding.

[0103] 6. A method according to alternative 1 or any of the preceding alternatives, wherein the step of preparing the precursor mixture is carried out in two steps, wherein a first mixing step is carried out without the one or more Li compounds and in a second mixing step the one or more Li compounds are added.

[0104] 7. The method of alternative 1 or any of the preceding alternatives, wherein the transition metal of at least one transition metal in the precursor mixture is in elemental form.

[0105] 8. The method of Alternative 1 or any of the preceding alternatives, wherein A is selected from the group consisting of Na, B, Al, Mg, Zr, Nb, Fe, Si, P, Mo, Ba, Sr, Ca, Zn, Cr, V, W, Nd, La, Cs, Ta, Ce, Cu, Eu, Ti, Sn, Sb, Pb, Bi, Rb, and mixtures thereof.

[0106] 9. The method according to alternative 1 or any of the preceding alternatives, wherein the precursor mixture is prepared using raw materials, wherein: the Ni compound does not contain metal elements other than Ni; the Mn compound does not contain metal elements other than Mn; the Co compound does not contain metal elements other than Co; the Al compound does not contain metal elements other than Al;

[0107] 10. The method of Alternative 1 or any of the preceding alternatives wherein y is 0.

[0108] 11. The method of Alternative 1 or any of the preceding alternatives wherein n is 0.

[0109] 12. The method of Alternative 1 or any of the preceding alternatives wherein m is 0.

[0110] 13. The method of alternative 1 or any of the preceding alternatives wherein c is 0.

[0111] 14. The method of Alternative 1 or any of the preceding alternatives wherein a is 0.

[0112] 15. The method of alternative 1 or any of the preceding alternatives wherein y is not 0 and at least one of n, m, c, a is 0.

[0113] 16. The method according to alternative 1 or any of the preceding alternatives, wherein the lithium transition metal oxide is LiNi 0.6 Mn 0.2 Co 0.2 O 2 or LiNi 0.83 Mn 0.06 Co 0.11 O 2 .

[0114] 17. The method according to alternative 1 or any of the preceding alternatives, wherein the lithium transition metal oxide is LiNi 0.8 Mn 0.1 Co 0.1 O 2 .

[0115] 18. The method of alternative 1 or any of the preceding alternatives wherein heating the precursor mixture is performed under an atmosphere of an inert gas, oxygen, a gas with a low oxygen partial pressure, dry air, or air.

[0116] 19. The method of alternative 1 or any of the preceding alternatives wherein the heating temperature is from about 450°C to 1000°C with one or more temperature holds.

[0117] 20. The method of alternative 1 or any of the preceding alternatives wherein the heating temperature is from about 700°C to 1000°C with one or more temperature holds.

[0118] 21. The method of Alternative 1 or any of the preceding Alternatives wherein the heating temperature is from about 450°C to 750°C with one or more temperature holds.

[0119] 22. The method of Alternative 1 or any of the preceding alternatives wherein the total heating time is from about 10 hours to 100 hours.

[0120] 23. The method of Alternative 1 or any of the preceding alternatives wherein the total heating time is from about 50 hours to 100 hours.

[0121] 24. The method of alternative 1 or any of the preceding alternatives wherein the lithium compound is added in an amount not greater than 20% in excess of the stoichiometric amount.

[0122] 25. The method of Alternative 1 or any of the preceding alternatives wherein lithiation is accomplished in one step.

[0123] 26. The method of alternative 1 or any of the preceding alternatives, wherein the lithiation is accomplished in two steps, wherein a first lithiation step is performed with -0.2≤x<0, and a second lithiation step is performed with a residual stoichiometric amount of Li with a total x≤0.20.

[0124] 27. A method according to alternative 1 or any of the preceding alternatives, wherein the lithiation is accomplished in two steps, wherein a first lithiation step is performed with -0.1≤x<0, and a second lithiation step is performed with a residual stoichiometric amount of Li with a total x≤0.10.

[0125] 28. The method according to alternative 1 or any of the preceding alternatives, wherein post-modification is carried out on the lithium transition metal oxide by additional reheating under an atmosphere of inert gas, oxygen, low oxygen partial pressure gas, dry air or air.

[0126] 29. The method of Alternative 1 or any of the preceding Alternatives wherein the reheat temperature is greater than 500°C for greater than 1 hour.

[0127] 30. The method of alternative 1 or any of the preceding alternatives, wherein the percentage of cation mixing in the lithium transition metal oxide product, the amount of Ni in the Li layer, is less than 6.0 mol%.

[0128] 31. The method of Alternative 1 or any of the preceding alternatives wherein combining the precursor mixture comprises mixing the precursor mixture in the absence of a solvent.

[0129] 32. The method of Alternative 1 or any of the preceding alternatives wherein combining the precursor mixture comprises mixing the precursor mixture in a substantially water-free environment.

[0130] 33. The method of Alternative 1 or any of the preceding alternatives wherein the precursor mixture is mixed in a wet process with a solid:liquid weight ratio of at least 5:1.

[0131] 34. The method of Alternative 1 or any of the preceding alternatives, wherein the method is carried out without adding any reaction promoters or seeds during the mixing process.

[0132] 35. The method of Alternative 1 or any of the preceding alternatives wherein the precursor mixture is mixed in the absence of a slurry.

[0133] 36. The method of Alternative 1 or any of the preceding alternatives wherein the precursor mixture is mixed in the absence of an organic solvent.

[0134] 36. The method of Alternative 1 or any of the preceding alternatives wherein the precursor mixture is mixed in the absence of a protic solvent.

[0135] 37. The method of Alternative 1 or any of the preceding alternatives wherein the precursor mixture is mixed in the absence of a polar solvent.

[0136] 38. The method of Alternative 1 or any of the preceding alternatives wherein the precursor mixture is mixed in the absence of a non-polar solvent.

[0137] 39. The method of Alternative 1 or any of the preceding alternatives wherein the precursor mixture is mixed in the absence of an acidic or basic solution.

[0138] 40. The method of Alternative 1 or any of the preceding alternatives wherein the precursor mixture is mixed in a solid state free of solvent residues.

[0139] 41. The method of Alternative 1 or any of the preceding alternatives wherein the mixing step and the heating step are performed in tandem.

[0140] 42. The method of Alternative 1 or any of the preceding alternatives wherein: -0.19≤x≤0.19.

[0141] 43. The method of Alternative 1 or any of the preceding alternatives wherein: -0.18≤x≤0.18.

[0142] 44. The method of Alternative 1 or any of the preceding alternatives wherein: -0.15≤x≤0.15.

[0143] 45. The method of Alternative 1 or any of the preceding alternatives wherein: -0.12 ≤ x ≤ 0.12.

[0144] 46. ​​The method of Alternative 1 or any of the preceding alternatives wherein: -0.1 ≤ x ≤ 0.1.

[0145] 47. The method of Alternative 1 or any of the preceding alternatives wherein: x=0.

[0146] 48. The method of Alternative 1 or any of the preceding alternatives wherein: 0≤y≤0.04.

[0147] 49. The method of Alternative 1 or any of the preceding alternatives wherein: 0≤y≤0.03.

[0148] 50. The method of Alternative 1 or any of the preceding alternatives wherein: 0≤y≤0.02.

[0149] 51. The method of Alternative 1 or any of the preceding alternatives wherein: 0≤y≤0.01.

[0150] 52. The method of alternative 1 or any of the preceding alternatives wherein: 0≤y≤0.001.

[0151] 53. The method of Alternative 1 or any of the preceding alternatives wherein Ni is provided in elemental form.

[0152] 54. The method of Alternative 1 or any of the preceding alternatives wherein Mn is provided in elemental form.

[0153] 55. The method of Alternative 1 or any of the preceding alternatives, wherein Co is provided in its elemental form.

[0154] 56. The method of Alternative 1 or any of the preceding alternatives wherein the combining is a dry solid state mixing that does not produce wastewater.

[0155] 57. A method according to alternative 1 or any of the preceding alternatives, wherein one or more Ni elements or Ni compounds, one or more Mn elements or Mn compounds, one or more Co elements or Co compounds, one or more Al elements or Al compounds and / or one or more metal dopant elements or metal dopant compounds are Class 2 raw materials.

[0156] 58. A method according to alternative 1 or any of the preceding alternatives, wherein one or more Ni elements or Ni compounds, one or more Mn elements or Mn compounds, one or more Co elements or Co compounds, one or more Al elements or Al compounds and / or one or more metal dopant elements or metal dopant compounds are Class 2 insoluble raw materials.

[0157] 59. A method according to alternative 1 or any of the preceding alternatives, wherein one or more Ni elements or Ni compounds, one or more Mn elements or Mn compounds, one or more Co elements or Co compounds, one or more Al elements or Al compounds and / or one or more metal dopant elements or metal dopant compounds are included as raw materials.

[0158] 60. A method according to alternative 1 or any of the preceding alternatives, wherein one or more Ni elements or Ni compounds, one or more Mn elements or Mn compounds, one or more Co elements or Co compounds, one or more Al elements or Al compounds and / or one or more metal dopant elements or metal dopant compounds are contained in powder form.

[0159] 61. A method according to alternative 1 or any of the preceding alternatives, wherein one or more Ni elements or Ni compounds, one or more Mn elements or Mn compounds, one or more Co elements or Co compounds, one or more Al elements or Al compounds and / or one or more metal dopant elements or metal dopant compounds are contained in the form of a powder having a D50 of less than 1000 microns.

[0160] 62. A method according to alternative 1 or any of the preceding alternatives, wherein one or more Ni elements or Ni compounds, one or more Mn elements or Mn compounds, one or more Co elements or Co compounds, one or more Al elements or Al compounds and / or one or more metal dopant elements or metal dopant compounds are contained in the form of a powder having a D50 of less than 500 microns.

[0161] 63. The method of Alternative 1 or any of the preceding alternatives wherein the lithium transition metal oxide cathode material is free of solvent residues.

[0162] 64. The method of Alternative 1 or any of the preceding Alternatives wherein the metals in the precursor mixture, except Li, are in elemental form.

[0163] 65. The method of Alternative 1 or any of the preceding alternatives further comprising comminuting the heated precursor mixture by at least one of impact milling, jet milling, or grinding.

[0164] 66. A secondary battery comprising an electrode material comprising: a lithium transition metal oxide product from the method of Alternative 1.

[0165] 67. The secondary battery of alternative 66, wherein the secondary battery is a lithium ion battery.

[0166] 69. A secondary battery according to any of alternatives 66-68, wherein the secondary battery has a carbon-based anode.

[0167] 70. The secondary battery according to any of alternatives 66-69, wherein the secondary battery has an anode composed of synthetic graphite having a particle size D50 of 5 μm to 30 μm.

[0168] 71. The secondary battery according to any of alternatives 66-70, wherein the secondary battery has secondary particles composed of primary particles having a particle size D50 of 1 μm to 15 μm, wherein the secondary particles have a particle size D50 of 5 μm to 30 μm.

[0169] 72. The secondary battery of any of alternatives 66-71 wherein the secondary battery has an anode material comprised of synthetic graphite and hard carbon, wherein the hard carbon content is about 0.25 wt % to 5 wt % of the anode material.

[0170] Additional Implementation

[0171] In the foregoing description, the present invention has been described with reference to specific embodiments of the present invention. However, it is apparent that various modifications and changes may be made thereto without departing from the broader spirit and scope of the present invention. Therefore, the description and drawings are to be regarded as illustrative rather than restrictive.

[0172] In fact, although the present invention has been disclosed in the context of certain embodiments and examples, it will be understood by those skilled in the art that the present invention extends beyond the specifically disclosed embodiments to other alternative embodiments and / or uses of the present invention and obvious modifications and equivalents thereof. In addition, although several variations of the embodiments of the present invention have been shown and described in detail, other modifications within the scope of the present invention will be apparent to those skilled in the art based on this disclosure. It is also conceivable that various combinations or sub-combinations of the specific features and aspects of the embodiments may be performed, and these combinations or sub-combinations still fall within the scope of the present invention. It should be understood that the various features and aspects of the disclosed embodiments may be combined or substituted with each other to form a variation pattern of the embodiments of the disclosed invention. Any method disclosed herein does not need to be performed in the order described. Therefore, the scope of the present invention disclosed herein should not be limited by the above-mentioned specific embodiments.

[0173] It should be understood that the systems and methods of the present disclosure each have several innovative aspects, no single innovative aspect of which is solely responsible for or required by the desired attributes disclosed herein. The various features and processes described above can be used independently of each other, or can be used in combination in various ways. All possible combinations and sub-combinations are intended to fall within the scope of the present disclosure.

[0174] The ranges disclosed herein also include any and all overlaps, subranges, and combinations thereof. Language such as "at most," "at least," "greater than," "less than," "between," and the like includes the listed numbers. Numbers modified with terms such as "about" or "approximately" include the listed numbers and should be interpreted based on the circumstances (e.g., as accurately as reasonably possible under the circumstances, e.g., ±5%, ±10%, ±15%, etc.). For example, "about 3.5 mm" includes "3.5 mm." Phrases modified with terms such as "substantially" include the listed phrases and should be interpreted based on the circumstances (e.g., as reasonably as possible under the circumstances). For example, "substantially constant" includes "constant." Unless otherwise noted, all measurements are under standard conditions including temperature and pressure.

[0175] As used herein, the phrase "at least one" of a list of items refers to any combination of those items, including single members. As an example, "at least one of A, B, or C" is intended to cover A, B, C, A and B, A and C, B and C, and A, B and C. Unless otherwise specifically stated, conjunction expressions such as the phrase "at least one of X, Y, and Z" are generally understood from the context to indicate that an item, term, etc. can be at least one of X, Y, or Z. Therefore, such conjunction expressions are generally not intended to imply that certain embodiments require at least one of X, at least one of Y, and at least one of Z to exist. The headings provided herein, if any, are for convenience only and do not necessarily affect the scope or meaning of the apparatus and methods disclosed herein.

[0176] Thus, the claims are not intended to limit the embodiments shown herein, but are to be accorded the widest scope consistent with this disclosure, the principles and the novel features disclosed herein.

Claims

1. A method for preparing a lithium transition metal oxide positive electrode material for a secondary battery, wherein the lithium transition metal oxide positive electrode material has an empirical formula (1): Li 1+x [(Ni n Mr m Co c Al a ) 1-y A y ] 1-x O2,(1) in: -0.2≤x≤0.2； n+m+c+a=1; n≥0； m≥0； c≥0； a≥0； A is a metal dopant; as well as 0≤y≤0.05； The method comprises: (A) preparing a precursor mixture by combining stoichiometric amounts of one or more lithium compounds, one or more Ni elements or Ni compounds, one or more Mn elements or Mn compounds, one or more Co elements or Co compounds, one or more Al elements or Al compounds and / or one or more metal dopant elements or metal dopant compounds according to formula (1), wherein: - at least one transition metal in elemental form and selected from Ni, Mn and Co to form the precursor mixture; - the compound of the remaining metal is selected from oxides, hydroxides, oxyhydroxides, carbonates, sulfates, nitrates, acetates and combinations thereof; - the one or more Li compounds are selected from lithium carbonate, lithium oxide, lithium hydroxide, lithium acetate, lithium chloride, lithium fluoride, lithium nitrate, lithium sulfate and mixtures thereof; and (B) heating the precursor mixture to produce the lithium transition metal oxide positive electrode material having a single-phase structure.

2. The method according to claim 1, wherein the step of preparing the precursor mixture is carried out by dry mixing or wet mixing or a combination thereof, wherein the dry mixing uses a ball mill, an automatic grinder, an impact mill, a high-speed mixer, grinding, an acoustic mixer, a mechanical fusion machine or a blender, and the wet mixing uses wet grinding.

3. The method according to claim 1, wherein the step of preparing the precursor mixture is completed in two steps, wherein a first mixing step is performed without the one or more Li compounds, and the one or more Li compounds are added in a second mixing step.

4. The method of claim 1, wherein the transition metal of the at least one transition metal in the precursor mixture is in elemental form.

5. The method of claim 1, wherein A is selected from the group consisting of Na, B, Al, Mg, Zr, Nb, Fe, Si, P, Mo, Ba, Sr, Ca, Zn, Cr, V, W, Nd, La, Cs, Ta, Ce, Cu, Eu, Ti, Sn, Sb, Pb, Bi, Rb, and mixtures thereof.

6. The method of claim 1, wherein said preparation of a precursor mixture uses a raw material, wherein: The Ni compound does not contain any metal element other than Ni; The Mn compound does not contain any metal element other than Mn; The Co compound does not contain any metal element other than Co; and The Al compound does not contain other metal elements except Al. The method of claim 1 , wherein y is 0. The method according to claim 5 , wherein n is 0.

9. The method of claim 5, wherein m is 0.

10. The method of claim 5, wherein c is 0. The method according to claim 5 , wherein a is 0.

12. The method of claim 1, wherein y is not 0 and at least one of n, m, c, a is 0.

13. The method according to claim 1, wherein the lithium transition metal oxide is LiNi 0.6 Mn 0.2 Co 0.2 O2.

14. The method according to claim 1, wherein the lithium transition metal oxide is LiNi 0.8 Mn 0.1 Co 0.1 O2.

15. The method according to claim 1, wherein heating the precursor mixture is performed under an atmosphere of an inert gas, oxygen, a gas with a low oxygen partial pressure, dry air or air.

16. The method of claim 15, wherein the heating temperature is about 450°C to 1000°C, carried out under one or more temperature holds.

17. The method of claim 15, wherein the total heating time is about 10 hours to 100 hours.

18. The method of claim 1, wherein the lithium compound is added in an amount not greater than 20% in excess of the stoichiometric amount.

19. The method of claim 18, wherein lithiation is accomplished in one step.

20. The method of claim 18, wherein lithiation is accomplished in two steps, wherein a first lithiation step is performed with -0.2≤x<0, and a second lithiation step is performed with a residual stoichiometric amount of Li with total x≤0.

20.

21. The method according to claim 1, wherein post-modification is performed on the lithium transition metal oxide by additional reheating under an atmosphere of an inert gas, oxygen, a low oxygen partial pressure gas, dry air or air.

22. The method of claim 21, wherein the reheating temperature is greater than 500°C for greater than 1 hour.

23. The method of claim 1, wherein the percentage of cation mixing in the lithium transition metal oxide product, the amount of Ni in the Li layer, is less than 6.0 mol%.

24. The method of claim 1, wherein the combining of the precursor mixture comprises mixing the precursor mixture in the absence of a solvent.

25. The method of claim 1, further comprising comminuting the heated precursor mixture by at least one of impact milling, jet milling, or grinding.

26. A secondary Li-ion battery comprising an electrode material comprising: the lithium transition metal oxide product from the method of claim 1.

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