Metal digestion and anion regeneration one-pot method for synthesizing CAM precursor

Abstract

An improved method of forming a lithium ion cathode material is provided. The method comprises: dispersing a metal elementary substance in a liquid comprising an acid to form a dispersion, wherein the acid is substoichiometric relative to the metal elementary substance; adding a peroxide and a polycarboxylic acid to the dispersion at a rate sufficient to maintain a temperature of at least 20 DEG C to no more than 70 DEG C to form a precipitated metal salt of the polycarboxylic acid; adding a lithium salt into the liquid; removing the liquid to form a lithium ion cathode material precursor; and calcining the lithium ion cathode material precursor to form the lithium ion cathode material.

Description

Technical Field

[0001] This invention relates to an improved method for forming fine powders, ultrafine powders, and nanoparticles of cathode active materials (CAMs) for batteries. More specifically, this invention relates to, but is not limited to, lithium-ion battery cathodes and efficient methods for preparing CAMs, which have minimal material waste and a reduced number of process steps, some of which are detrimental to sintering and calcination. Background Technology

[0002] The need for battery improvements is ever-present. Batteries have two main applications: stationary and mobile. Both types of applications demand increased storage capacity, extended battery life, faster full charge capability, and lower costs. Lithium-ion batteries, including lithium metal oxide cathodes as CAMs, offer significant advantages for most applications and are favored across a wide range of uses. Nevertheless, improvements are still desired, particularly in the storage capacity, charging time, cost, and storage stability of lithium-ion batteries.

[0003] The fabrication of lithium-ion batteries comprising lithium and transition metal-based cathodes with rock salt crystal forms is described in U.S. patent applications 9,136,534, 9,159,999, and 9,478,807, and U.S. patent applications 2014 / 0271413, 2014 / 0272568, and 2014 / 0272580, all of which are incorporated herein by reference. Cathode materials having rock salt crystal forms have the general formula: LiNi a Mn b X c O2 X is preferably Co or Al, and a+b+c=1. When X is cobalt, for convenience, the cathode material is called NMC; when X is aluminum, for convenience, the cathode material is called NCA.

[0004] Cathode materials with a spinel crystal structure have the general formula: LiNi x Mn y Co z O4 Where x + y + z = 2.

[0005] A recent reported advancement is the formation of CAM (rock salt or spinel) by digesting the metal in oxalic acid with Li₂CO₃ in a molar excess of nitric acid to prepare a mixed oxalate precursor. The mixed oxalate precursor is then calcined to produce CAM. A supply chain for transition metal carbonates has not yet been established, as the supply chain is primarily based on metal sulfates. Metal carbonates are typically produced from metal sulfates.

[0006] Metal sulfates have very low metal content; for example, nickel sulfate contains only 21 wt% nickel. Therefore, the costs associated with the formation of metal carbonates from metal sulfates are significantly lower than the cost-effectiveness associated with the aforementioned oxalate method. In the formation of metal sulfates, transition metals are extracted from their original sources, typically purified to metal, and then redissolved in acid. Therefore, the formation of metal carbonates from metal sulfates generates a Na₂SO₄ waste stream, and the purity of this waste stream is usually insufficient for the formation of CAMs for battery production unless additional, expensive purification steps are used.

[0007] Although waste streams associated with sulfate formation have been improved, the necessity of using excess nitric acid creates supply chain problems related to nitric acid, which become more severe at scale-up production. An improved method for manufacturing lithium-ion cathodes (particularly lithium / manganese / nickel-based cathodes with spinel and rock salt crystal structures) is desired, free from the precursor and reactant supply problems and waste stream issues common in the art. This invention provides such a method. Summary of the Invention

[0008] The purpose of this invention is to provide an improved method for preparing CAM for lithium-ion batteries.

[0009] More specifically, the present invention relates to an improvement in the formation of CAM precursors that eliminates the need to form metal sulfates and the need to convert metal sulfates into metal carbonates, thereby simplifying the production of metal precursors.

[0010] More specifically, the present invention relates to improvements in the formation of CAM precursors, which utilize substoichiometric amounts of acid (particularly nitric acid) and peroxide (preferably hydrogen peroxide), thereby simplifying the manufacturing process and reducing the amount of material that is difficult to process on a large scale.

[0011] The object of this invention is to provide an improved method for forming a metal salt precursor of lithium metal oxide, wherein the metal salt precursor is calcined to form a lithium metal oxide cathode.

[0012] A particular object of the present invention is to provide an improved method for forming a lithium-ion battery comprising a transition metal-based cathode with a spinel crystal structure or a rock salt structure, the transition metal-based cathode preferably being selected from NMC and NCA.

[0013] A particular advantage of the present invention is that it is capable of forming high-nickel CAMs, wherein precursor materials suitable for forming high-nickel CAMs are readily available at a reasonable cost and purity level.

[0014] One embodiment of the present invention provides a method for forming a lithium-ion cathode material, comprising: A metallic element is dispersed in a liquid containing an acid to form a dispersion, wherein the acid is substoichiometric relative to the metallic element. Peroxide and polycarboxylic acid are added to the dispersion at a rate sufficient to maintain a temperature of at least 20°C to no more than 70°C to form a precipitated metal salt of polycarboxylic acid; Add lithium salt to the liquid; Removing liquid to form lithium-ion cathode material precursors; and The lithium-ion cathode material precursor is calcined to form the lithium-ion cathode material. Attached Figure Description

[0015] Figure 1 This is an XRD pattern.

[0016] Figure 2 This is a graphical representation of particle size.

[0017] Figure 3 The diagram illustrates charge / discharge and cycle performance.

[0018] Figure 4 This is an XRD pattern.

[0019] Figure 5 This is a graphical representation of particle size.

[0020] Figure 6 The diagram illustrates charge / discharge and cycle performance.

[0021] Figure 7 This is an XRD pattern.

[0022] Figure 8 This is a graphical representation of particle size.

[0023] Figure 9 The diagram illustrates charge / discharge and cycle performance. Detailed Implementation

[0024] This invention specifically relates to an improved method for preparing lithium-ion batteries (particularly CAMs for lithium-ion batteries). More specifically, this invention relates to an improved method for forming a cathode used in lithium-ion batteries, wherein the cathode is in spinel crystal form or rock salt form, preferably in the form of NMC and NCA materials. Even more specifically, this invention relates to the direct formation of metal salt precursors from elemental metals without the need to form sulfates and carbonates, and reduces the amount of acid (particularly nitric acid) required for CAM formation.

[0025] In a preferred embodiment, the CAM of the present invention comprises a lithium metal compound with a spinel crystal structure as defined by Formula I: LiNi x Mn y Co z E wO4 Formula I Where E is an optional dopant; and x + y + z + w = ​​2, w ≤ 0.2; or Rock salt crystal structure as defined by Equation II: LiNi a Mn b X c G d O2 Formula II Where G is an optional dopant; X is either Co or Al; and Where a+b+c+d=1, d≤0.1.

[0026] In a preferred embodiment, the spinel crystal structure of Formula I has 0.4 ≤ x ≤ 0.6, 1.4 ≤ y ≤ 1.6, and z ≤ 0.2. More preferably, 0.5 ≤ x ≤ 0.55, 1.45 ≤ y ≤ 1.5, and z ≤ 0.05. In a preferred embodiment, neither x nor y is zero. In Formula I, the Mn / Ni ratio is preferably not greater than 4, preferably at least 2.33 to not greater than 3, and most preferably at least 2.6 to less than 3.

[0027] In a preferred embodiment, the rock salt crystal structure of Formula II is high-nickel NMC, where 0.5 ≤ a ≤ 0.95, more preferably 0.58 ≤ a ≤ 0.62, as shown in NMC622, or 0.78 ≤ a ≤ 0.82, as shown in NMC811. In a preferred embodiment, a = b = c, as shown in NMC111. The term NMCxxx is an abbreviation used in the art to represent the nominal relative molar ratio of nickel, manganese, and cobalt. For example, NMC811 represents LiNi. 0.8 Mn 0.1 X 0.1 O2.

[0028] Throughout the formulas in this specification, lithium is stoichiometrically defined as the equilibrium charge, understood to mean that lithium can move between the anode and cathode. Therefore, at any given time, the cathode can be relatively lithium-rich or relatively lithium-poor. In a lithium-poor cathode, lithium will be below stoichiometric equilibrium, while when charged, lithium can be above stoichiometric equilibrium. Similarly, in the formulations listed throughout the specification, metals are expressed in charge balance terms, but it is understood that, since a perfectly balanced stoichiometry cannot be achieved in practice, metals may be slightly rich or slightly poor, as determined by elemental analysis. In this application, for stoichiometric representations, such as in NMC811, the stoichiometric ratio is ±1 mol% due to variations in manufacturing and elemental analysis. As a non-limiting example, NMC811 or its equivalent represents LiNi. 0.8 Mn 0.1 Co0.1 O2 is intended to represent LiNi 0.792-0.808 Mn 0.099-0.101 Co 0.099-0.101 O2, including any dopant, has a total molar amount equal to 1.

[0029] Dopants can be added to enhance oxide properties, such as electronic conductivity and stability. The dopants are preferably added at lattice sites along with the main nickel, manganese, and optionally cobalt or aluminum. The dopants preferably comprise no more than 10 mol% of the oxide, preferably no more than 5 mol%. Preferred dopants include Al, Gd, Ti, Zr, Ca, Sr, Ba, Mg, Cr, Cu, Fe, Zn, V, Bi, Nb, and B, with Al and Gd being particularly preferred. When X is Co, Al will be the dopant. The dopants and coating materials can be suitably added to the reactor in the form of carbonates, oxides, or metals to prepare the desired composition.

[0030] The oxide precursor is formed by dispersing a metal powder (M) and any optional dopant in a dilute acid (preferably nitric acid), wherein the metal is selected from nickel, manganese, cobalt, or aluminum, and wherein the acid is substoichiometric relative to the dispersed metal powder. For the purposes of this disclosure, substoichiometry is defined as less than one mole of acid relative to each mole of dispersed metal powder, preferably less than 0.5 moles of acid relative to each mole of dispersed metal powder, and most preferably 0.1 to 0.3 moles of acid relative to each mole of dispersed metal powder. A peroxide (preferably hydrogen peroxide) and a polycarboxylic acid (preferably oxalic acid) are then added to regenerate the acid, thereby forming a metal oxalate when oxalic acid is used in the reaction represented by reaction (I), and nitric acid when nitric acid is used: (I). As will be recognized, in reaction (I), nitric acid is not consumed, therefore the reaction rate can be controlled by the rates of addition of oxalic acid and hydrogen peroxide as representative additives, with the peroxide being the rate-limiting additive. Metal oxalate precipitation and the consumption of hydrogen peroxide allow the reaction to reach stoichiometric completeness relative to the metal.

[0031] Peroxides and polycarboxylic acids can be added alternately, or they can be combined. Equal portions of peroxides and polycarboxylic acids can be added over time, or they can be added in a continuous stream. The addition rate is determined by the temperature and the heat dissipation capacity of the reaction. Preferably, the addition rate, particularly the rate of peroxide addition, is sufficient to maintain a temperature of at least 20°C. Below about 20°C, the rate of metal digestion decreases, which is detrimental to efficiency and carries the risk of incomplete metal reaction. Above about 70°C, polycarboxylic acids, particularly oxalic acid, can undergo redox reactions with peroxides, resulting in reactant loss. Nitric acid may also react to release nitrous oxide. When nickel is digested, the preferred temperature is 30-50°C, more preferably 30-40°C. In one embodiment, nickel is first digested to complete at 30-40°C, followed by digestion of manganese and / or cobalt at 50-70°C, preferably terminating the addition of peroxides and additional oxalates. Dopants can be added as elemental metals during digestion or as metal compounds (e.g., carbonates) after digestion.

[0032] pH control is not required. During nickel digestion, the pH can be as low as about 1.0 and rise to at least 4.0 to about 8.0 near the end of the synthesis.

[0033] A lithium salt is added, preferably selected from Li₂CO₃ and LiOH. In a particularly preferred embodiment, Li₂CO₃ is added together with the final polycarboxylic acid to raise the pH, thereby ensuring the completion of metal digestion and resulting in a net reaction; for simplicity, hydrogen peroxide, oxalic acid, and lithium carbonate are assumed to be represented by reaction (II): (II).

[0034] The acid is preferably selected from nitric acid or hydrochloric acid, with nitric acid being preferred. The acid is preferably added to the metal as a dilute aqueous solution of up to 5 moles of acid, preferably not more than 1 mole of acid (particularly preferred not more than 1 mole of nitric acid). Increasing the acid concentration provides some advantages; however, handling concentrated acid solutions on a manufacturing scale is undesirable, therefore dilute acid solutions are particularly preferred, especially because the acid is regenerable.

[0035] The peroxide is selected from hydrogen peroxide, organic hydroperoxides and peracids, with hydrogen peroxide being preferred.

[0036] The cathode is formed from an oxide precursor comprising the aforementioned salts of Li, Ni, Mn, Co, and Al, and optional dopants, as will be described more fully herein. The oxide precursor is calcined to form a cathode material in the form of lithium metal oxide.

[0037] The cathode material is optionally and preferably treated with phosphate DPO4, where D is the atom required to balance the charge. D can be a monovalent, divalent, or trivalent atom, and it should be understood that combinations thereof can be used as needed. Particularly preferred is that D is easily removed by washing or evaporation after application. The phosphate is applied to the surface of the metal oxide, wherein the phosphate portion forms MnPO4 on the surface of the metal oxide, or is bound to the surface of the metal oxide. Manganese is preferably predominantly in the +3 oxidation state, and preferably less than 10% of the surface manganese is in the +2 oxidation state, so that manganese on the surface is reduced to Mn by the phosphate. 2+ The reaction is stable. The reaction releases D, which is removed by washing or evaporation. In preferred phosphates, D is selected from NH4. + H + Li + Na + And combinations thereof. Particularly preferred phosphates include (NH4)3PO4, (NH4)2HPO4, (NH4)H2PO4, and H3PO4, because D is easily removed after the formation of surface manganese phosphate. It is preferred that the natural manganese oxide of the calcined oxide precursor reacts with the phosphate, rather than with added manganese or other metals. Therefore, it is preferred that the added phosphate has a relatively low Mn content, more preferably less than 1 wt% manganese impurity content. It is preferred that Mn is not added. +2 It is added together with the phosphate or after the oxide is formed. Preferably, there is no separate manganese phosphate phase (e.g., manganese phosphate) as a distinct phase on the surface. Preferably, the phosphate is coordinated to the surface of the metal oxide.

[0038] Stirring or agitating the reaction is preferred to ensure a continuous reaction. Alternatively, the reaction can be carried out in a horizontal bead mill to increase the reaction rate.

[0039] The timing of lithium addition (preferably in the form of Li₂CO₃) is not particularly critical. If Li₂CO₃ is added early in the process, the lithium salt (e.g., lithium oxalate) is formed through the digestion of the carbonate, and the lithium salt remains. Alternatively, Li₂CO₃ can be added after the transition metal reaction is complete or nearly complete, which is preferred.

[0040] The reaction time depends on temperature and agitation; however, the reaction can continue until completion, indicated by color changes in the slurry or stabilization of the slurry pH. After this step, the slurry must be dried (e.g., by spray drying or drum drying) and then calcined in air and / or O2 as usual, according to the final formulation of CAM.

[0041] In a preferred embodiment, the metal powders are mixed in the desired proportions for the final CAM. As a non-limiting example, if LiNi is to be prepared... 0.8 Mn 0.1 Co 0.1In the case of O2, the metal powder will contain 8 moles of Ni, 1 mole of Mn, and 1 mole of Co, with 1 mole of Li added before calcination. The particle size of the elemental metal raw materials can be adjusted so that the elemental metals react at similar rates. As a non-limiting example, particle size can be inversely proportional to the reaction rate, so that an increase in surface area mitigates the difference in reaction rates. Since the reaction rate follows the general relationship of Co > Mn > Ni, it may be advantageous to use particle size differences to adjust the reaction rate in commonly measured chemistry.

[0042] The concentration of sulfur as an impurity is particularly important for nickel, with higher concentrations increasing the reaction rate. Those skilled in the art will understand that sulfur has an adverse effect on electrical properties and is therefore generally avoided or kept below detectable limits. However, small amounts of impurities are acceptable to balance reaction rate and electrical properties. Sulfur impurities of no more than 0.05 wt% relative to nickel metal can effectively and sufficiently increase the reaction rate with carbonates without significantly reducing electrical properties.

[0043] Divalent metal oxalates, such as NiC₂O₄, MnC₂O₄, CoC₂O₄, and ZnC₂O₄, are highly insoluble, while monovalent metal oxalates (such as Li₂C₂O₄) are slightly soluble, with a solubility of approximately 8 g / 100 mL in water at 25°C. If lithium oxalate must be in solution and uniformly dispersed in a mixed metal oxalate precipitate, it may be ideal to keep the volume of water above the solubility limit of lithium oxalate.

[0044] Polycarboxylic acids contain at least two carboxyl groups. Oxalic acid is particularly preferred, partly because it requires minimal carbon removal during calcination. Other low molecular weight dicarboxylic acids, such as malonic acid, succinic acid, glutaric acid, and adipic acid, can be used. Higher molecular weight dicarboxylic acids, especially those with an even number of carbons and higher solubility, can be used, but the need to remove additional carbon and reduce solubility makes them less desirable. Other acids, such as citric acid, oxaloacetic acid, fumaric acid, maleic acid, and other polycarboxylic acids, can be used, provided they have sufficient solubility to achieve at least a trace stoichiometric excess and sufficient chelating properties. Acids with hydroxyl groups are preferably not used because they have increased hygroscopic properties.

[0045] The dried powder can be transferred to the calcination system in batches or by continuous flow (e.g., by conveyor belt or similar transfer machine). In large-scale production, this transfer can be continuous or batch. The calcination system can be a box furnace, rotary calcination furnace, fluidized bed (co-current or counter-current), rotary tube furnace, and other similar equipment that uses ceramic trays or saggers as containers, but is not limited to these.

[0046] The heating and cooling rates during calcination depend on the type of final product desired. Generally, a heating rate of approximately 50°C per minute is preferred, but typical industrial heating rates are also applicable.

[0047] The resulting final powder is consistent with the teachings in the art. A particular advantage is that the powder does not require the additional crushing, grinding, or milling performed as in current conventional processing. The particles are relatively soft and do not sinter as in conventional processing.

[0048] The final calcined oxide powder is an agglomeration of crystal grains, which is preferably characterized by surface area and particle size through electron microscopy, porosity, elemental chemical analysis, and performance tests required for preferred professional applications.

[0049] The spray dryer collector can be modified to allow the outlet valve to open and close as the sprayed powder is transferred to the calcining furnace. The spray-dried powder in the collector can be transferred in batches to trays or saggers and then into the calcining furnace. Rotary or fluidized bed calcining furnaces can be used to demonstrate the invention. The calcination temperature is determined by the powder composition and the desired final phase purity. For most oxide-type powders, the calcination temperature ranges from as low as 400°C to slightly above 1000°C. After calcination, the powder is sieved because it is soft and unsintered. Calcining oxides does not require long milling times or grading to obtain a narrow particle size distribution.

[0050] The calcined powder contains primary particles, which aggregate to form secondary particles. The average particle size of the primary particles is typically 100 nm to 5 μm, the average primary particle size of Formula I material is typically 1 μm to 5 μm, and the average secondary particle size of Formula II material is typically 100 nm to 1 μm. The average particle size of the secondary particles is typically 10 μm to 30 μm.

[0051] A particular advantage of this invention is the formation of metal chelates of polycarboxylic acids, rather than acetates. In the subsequent calcination of the oxide precursor, acetates act as combustion fuel, requiring additional oxygen for complete combustion. Low molecular weight polycarboxylic acids, especially low molecular weight dicarboxylic acids, and more particularly oxalic acid, decompose at lower temperatures without the introduction of additional oxygen. For example, oxalates decompose at approximately 300°C without additional oxygen, allowing for more precise control of the calcination temperature. This can lower the calcination temperature, thereby promoting disorder. The formation of the spinel crystal structure minimizes the presence of impurity phases, as observed under high-temperature conditions.

[0052] This invention offers significant manufacturing flexibility. The metal digestion step can be performed stepwise, in small quantities, followed by mixing. For example, 10% of all metals can be digested with the appropriate reagent, then precipitated to form a precursor, and this process can be repeated until digestion is complete. Transmission electron microscopy (TEM) images and corresponding energy-dispersive X-ray (EDX) images of the precursors prepared using the aforementioned stoichiometric amounts of nitric acid, both in existing techniques and by the method of this invention, demonstrate a significant improvement in the homogeneity of transition metals in the samples prepared by the method of this invention.

[0053] Using currently available equipment and / or innovations in existing industrial equipment, this method can be easily scaled up to large-scale manufacturing.

[0054] Example

[0055] Representative electrode fabrication:

[0056] A composite electrode was prepared by mixing the active material with 10 wt% conductive carbon black (as a conductive additive) and 5 wt% polyvinylidene fluoride (PVDF) (as a binder) dissolved in N-methyl-2-pyrrolidone (NMP) solvent. The slurry was cast onto graphite-coated aluminum foil and dried overnight under vacuum at 60 °C. The electrode was prepared from a typical loading of 4 mg·cm⁻¹. -2 The electrode sheet was cut with a surface area of ​​1.54 cm². 2 The electrode disk.

[0057] Representative coin cell battery components:

[0058] The coin cell was assembled in an argon-filled glove box. Lithium foil (340 µm) will be used as the counter and reference electrode in the half-cell, and commercial Li₄Ti₅O₂ will be used. 12 The (LTO) composite electrode will be used as both the counter and reference electrode in the full cell. 1 M LiPF6 will be used as the electrolyte in a 7:3 (vol%) ethylene carbonate (EC): diethyl carbonate (DEC) mixture. Electrodes in the half cell will be connected via one or two 25 µm thick Celgard electrodes. ® The electrodes in the full cell are separated by a Celgard membrane.

[0059] Representative loop scheme:

[0060] Using an Arbin Instruments battery tester (model BT 2000), at 25°C, at various C rates (1C rate is equivalent to 146 mAg)... -1The spinel cathode cell was subjected to constant current cycling within a voltage range of 3.5 V to 4.9 V. At the end of the constant current charging step at 1C or higher, the cell was subjected to a 10-minute constant voltage charging step at 4.9 V. Cycling was performed at various C rates (1C rate is equivalent to 200 mAg) at 25°C. -1 The rock salt NMC battery was subjected to constant current cycling within a voltage range of 2.7 V to 4.35 V. At the end of the constant current charging step at 1C or higher, the battery was subjected to a 10-minute constant voltage charging step at 4.35 V.

[0061] Example 1: Spinel LiNi 0.5 Mn 1.5 Synthesis of O4 (LNMO)

[0062] LNMO was prepared on a scale of 200 g. Figure 1 a and Figure 1 b shows the X-ray diffraction (XRD) patterns of the precursor and calcined sample prepared using the method of this invention. There was no significant difference compared to the control LNMO sample. XRD confirmed the formation of the desired crystalline phase and the elimination of most impurities. SEM images of the calcined LNMO sample showed that the primary particles were octahedral in shape, with a size ranging from 1 µm to 4 µm. Figure 2 a and Figure 2 b provides the particle size distributions of the precursor and the sample, respectively. The D50 of the precursor is 14.08 µm, and the D50 of the calcined sample is 18.40 µm. Inductively coupled plasma mass spectrometry (ICP) results confirm that the sample achieves the target Li / Ni / Mn ratio, ensuring that the elemental ratio of the product is not affected by the method of this invention, and that this ratio can be individually controlled by adjusting the stoichiometry of the reactants.

[0063] Figure 3 A shows the charge-discharge curve of the sample from Example 1 during the 20th operating cycle, with a discharge capacity of 136 mAh g. -1 It features three characteristic platforms of LNMO, including Ni at 4.75 V. 2+ / Ni 3+ Redox reaction of Ni at 4.65 V 3 + / Ni 4+ Redox and Mn at approximately 4 V 3+ / Mn 4+ Redox. This electrochemical behavior matches the reference LNMO sample very well, confirming the correct synthesis of the product. Figure 3 B represents the cycling performance of the LNMO sample at 1C, indicating that the sample retains approximately 135 mAh g⁻¹ during 100 charge / discharge cycles. -1 This capacity is greater than the theoretical maximum of 147 mAhg. -1The capacity was reduced by approximately 8%. After 100 charge-discharge cycles, the capacity retention of this LNMO sample was 99.5%.

[0064] Example 2: Synthesis of LNMO using HCl

[0065] LNMO was synthesized on the same scale as in Example 1, using HCl as the digesting acid. Ni digestion remained unchanged, but the addition time of the Mn fraction in oxalic acid was shortened to 15 minutes, and Mn digestion was completed within 4 hours at 80°C. No additional HCl was added for Mn digestion, resulting in a final transition metal to HCl ratio of 1:0.05. SEM images of the calcined product showed that the particles exhibited the same octahedral morphology as in Example 1. The XRD pattern of the HCl precursor was similar to that synthesized using HNO3, with minimal change in peak intensity. Figure 4 The XRD pattern of the calcined product provided is almost identical to that of Example 1. The D50 of the particle size distribution is 14.16 µm, while the D50 of the calcined sample is 26.49 µm.

[0066] The discharge capacity is 135 mAhg -1 Having Ni 2+ / Ni 3+ Redox, Ni 3+ / Ni 4+ Redox and Mn 3+ / Mn 4+ The three inherent discharge plateaus of redox reactions, such as Figure 5 As shown. There is no significant difference compared to Example 1. Figure 6 As shown, the sample achieved an average capacity retention of 99.1% by the 100th cycle.

[0067] Example 3: Synthesis of NMC811

[0068] NMC811 was prepared on a 1 kg scale. Compared to the LNMO synthesis method in Example 1, there were no significant differences except for the different transition metal ratios. Co reacted in a similar manner to Mn, with the final transition metal to HNO3 ratio being approximately 1:0.184. SEM images of the calcined NMC samples showed that the primary particles ranged in size from 0.5 µm to 2 µm and exhibited a spherical morphology. Figure 7 As shown, the XRD pattern of the sample exhibits peaks typically associated with a typical NMC cathode, confirming the correct formation of the crystal phase. The PSDs of the NMC precursor and the sample are shown below. Figure 8 As shown, the D50 of the precursor is 30.64 µm, and the D50 of the calcined sample is 12.05 µm.

[0069] Regarding electrochemical performance, such as Figure 9As shown, the NMC sample reached approximately 211 mAh g at 1 / 10C. -1 The average capacity reaches approximately 194 mAh g at 1C. -1 The average capacity of the material is comparable to that of Ni between 4.3 V and 3.5 V. 2+ / Ni 4+ Co 3+ / Co 4+ and Mn 3+ / Mn 4+ The redox-related tilted discharge curves were obtained. Their capacity retention at 1C was 92.8% at 50 cycles and 88.0% at 100 cycles.

[0070] The present invention has been described with reference to preferred embodiments, but is not limited thereto. Those skilled in the art will be able to implement other embodiments and modifications not specifically described herein but falling within the scope of the invention, as specifically described in the appended claims.

Claims

1. A method for forming a lithium-ion cathode material, comprising: A metallic element is dispersed in a liquid containing an acid to form a dispersion, wherein the acid is substoichiometric relative to the metallic element. Peroxide and polycarboxylic acid are added to the dispersion at a rate sufficient to maintain a temperature of at least 20°C to no more than 70°C to form a precipitated metal salt of the polycarboxylic acid; Add lithium salt to the liquid; Remove the liquid to form a lithium-ion cathode material precursor; and The lithium-ion cathode material precursor is calcined to form the lithium-ion cathode material.

2. The method for forming a lithium-ion cathode material according to claim 1, wherein the liquid comprises less than 1 mole of the acid relative to each mole of the metal.

3. The method for forming a lithium-ion cathode material according to claim 2, wherein the liquid comprises less than 0.5 moles of the acid relative to each mole of the metal.

4. The method of forming a lithium-ion cathode material according to claim 3, wherein the liquid comprises at least 0.1 moles of the acid relative to each mole of the metal and up to 0.3 moles of the acid relative to each mole of the metal.

5. The method for forming a lithium-ion cathode material according to claim 1, wherein the acid is selected from nitric acid and hydrochloric acid.

6. The method for forming a lithium-ion cathode material according to claim 5, wherein the acid is nitric acid.

7. The method for forming a lithium-ion cathode material according to claim 1, wherein the concentration of the acid in the liquid does not exceed 1 mole.

8. The method for forming a lithium-ion cathode material according to claim 1, wherein the peroxide is selected from hydrogen peroxide, organic hydroperoxides, and peracids.

9. The method for forming a lithium-ion cathode material according to claim 8, wherein the peroxide is hydrogen peroxide.

10. The method for forming a lithium-ion cathode material according to claim 1, wherein the peroxide and the polycarboxylic acid are added individually or in combination.

11. The method for forming a lithium-ion cathode material according to claim 1, further comprising adding Li2CO3 to the liquid.

12. The method for forming a lithium-ion cathode material according to claim 11, wherein the Li2CO3 is added after the addition of the peroxide and the polycarboxylic acid.

13. The method for forming a lithium-ion cathode material according to claim 11, wherein the Li2CO3 is added after the addition of the peroxide and the polycarboxylic acid is completed.

14. The method for forming a lithium-ion cathode material according to claim 1, comprising dispersing nickel metal and maintaining a temperature of 30-50°C.

15. The method for forming a lithium-ion cathode material according to claim 14, comprising dispersing at least one of manganese or cobalt metal after dispersing the nickel metal, and maintaining a temperature of 50-70°C.

16. The method for forming a lithium-ion cathode material according to claim 1, comprising adding phosphate after calcination.

17. The method for forming a lithium-ion cathode material according to claim 16, wherein the phosphate is selected from (NH4)3PO4, (NH4)2HPO4, (NH4)H2PO4 and H3PO4.

18. The method for forming a lithium-ion cathode material according to claim 16, wherein the phosphate contains less than 1 wt% manganese impurities.

19. The method for forming a lithium-ion cathode material according to claim 1, wherein the elemental metal comprises at least two metals selected from Mn, Ni, Co and Al.

20. The method for forming a lithium-ion cathode material according to claim 19, wherein the elemental metal comprises at least two metals selected from Mn, Ni, and Co.

21. The method for forming a lithium-ion cathode material according to claim 1, wherein the polycarboxylic acid is selected from oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, citric acid, oxaloacetic acid, fumaric acid, and maleic acid.

22. The method for forming a lithium-ion cathode material according to claim 21, wherein the polycarboxylic acid is oxalic acid.

23. The method for forming a lithium-ion cathode material according to claim 1, wherein the lithium-ion cathode material is defined by formula I: LiNi x Mr y Co z HAVE BEEN e O4 Formula I Where E represents the dopant; x + y + z + e = 2; and 0≤e≤0.2。 24. The method for forming a lithium-ion cathode material according to claim 23, wherein formula I is a spinel crystal.

25. The method for forming a lithium-ion cathode material according to claim 24, wherein the spinel crystal has a grain size of 1-5 μm.

26. The method for forming a lithium-ion cathode material according to claim 23, wherein neither x nor y is zero.

27. The method for forming a lithium-ion cathode material according to claim 26, wherein the lithium-ion cathode material is LiNi. 0.5 Mn 1.5 O4.

28. The method for forming a lithium-ion cathode material according to claim 23, wherein the lithium-ion cathode material is composed of the formula LiNi x Mn y O4 is defined as follows, where 0.4 ≤ x ≤ 0.6 and 1.4 ≤ y ≤ 1.

6.

29. The method for forming a lithium-ion cathode material according to claim 28, wherein 0.5 ≤ x ≤ 0.55 and 1.45 ≤ y ≤ 1.

5.

30. The method for forming a lithium-ion cathode material according to claim 23, wherein the molar ratio of Mn to Ni in the lithium-ion cathode material is not greater than 4.

31. The method for forming a lithium-ion cathode material according to claim 30, wherein the molar ratio of Mn to Ni in the lithium-ion cathode material is at least 2.33 and not more than 3.

32. The method for forming a lithium-ion cathode material according to claim 31, wherein the molar ratio of Mn to Ni in the lithium-ion cathode material is at least 2.64 to less than 3.

33. The method for forming a lithium-ion cathode material according to claim 23, wherein the dopant is selected from Al, Gd, Ti, Zr, Mg, Ca, Sr, Ba, Cr, Fe, Cu, Zn, V, Bi, Nb and B.

34. The method for forming a lithium-ion cathode material according to claim 33, wherein the dopant is selected from Al and Gd.

35. The method for forming a lithium-ion cathode material according to claim 1, wherein the lithium-ion cathode material is defined by formula II: LiNi a Mn b X c G d O2 Formula II Where G is a dopant; X is either Co or Al; Where a+b+c+d=1; and 0≤d≤0.1。 36. The method for forming a lithium-ion cathode material according to claim 35, wherein 0.5 ≤ a ≤ 0.

95.

37. The method for forming a lithium-ion cathode material according to claim 36, wherein 0.58 ≤ a ≤ 0.62 or 0.78 ≤ a ≤ 0.

82.

38. The method for forming a lithium-ion cathode material according to claim 35, wherein a=b=c.

39. The method for forming a lithium-ion cathode material according to claim 35, wherein the grain size of the lithium-ion cathode material is 50-250 nm.

40. The method for forming a lithium-ion cathode material according to claim 39, wherein the grain size of the lithium-ion cathode material is 150-200 nm.

41. The method for forming a lithium-ion cathode material according to claim 1, wherein the lithium salt is lithium carbonate.

42. The method for forming a lithium-ion cathode material according to claim 1, wherein the heating is performed in air.

43. A battery comprising a lithium metal oxide prepared according to the method of claim 1.

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