Method for producing cathode material for lithium-ion batteries

Abstract

This invention provides an environmentally friendly method for producing high-capacity cathode materials for use in lithium-ion batteries. [Solution] Conventional methods for producing lithium mixed metal oxide cathode materials typically generate a large amount of effluent, which must be treated before discharge. In this process, mixed metals are used as raw materials in a wet chemical reaction with an oxidizing agent to produce a high-quality metal hydroxide precursor that can be used to prepare a high-quality cathode material after lithiumization. A key feature is that in the precursor preparation process, most of the aqueous solution used in the wet chemical reaction can be returned to the reactor and recycled, resulting in little to no effluent generation during the production of the cathode precursor material throughout the entire process.

Description

[Technical Field]

[0001] This invention relates to a method for producing cathode materials for lithium-ion batteries. In particular, this method produces less wastewater compared to existing industrial methods. [Background technology]

[0002] Rechargeable lithium-ion batteries have been used as energy storage components in many devices. These devices include mobile phones, portable computers, rechargeable power tools, hybrid vehicles, and electric vehicles. In recent years, the demand for high-power lithium-ion batteries has increased dramatically, particularly with the rapid market growth of electric vehicles. The main components of a lithium-ion battery include the anode, cathode, and electrolyte. During charge-discharge cycles, lithium ions travel back and forth between the anode and cathode active material via the electrolyte. Due to its low specific capacity and high raw material and production costs, the cathode active material is usually the most expensive material in a lithium-ion battery. Therefore, the selection of the cathode active material is crucial for improving the performance and reducing the cost of lithium-ion batteries. This is especially true for automotive applications, given the phenomenal growth expected in the next 20 years.

[0003] Currently, lithium mixed metal oxides, primarily containing nickel, cobalt, manganese, and / or aluminum along with other necessary dopants, are the main components used in the production of high-performance cathode active materials. The demand for and production of such materials continues to increase significantly.

[0004] Current industrial methods for producing these high-performance cathode materials, such as lithium mixed metal oxides, involve two main steps: a precursor production step and a lithiation step. In current methods, the precursor production step begins with the use of a mixed metal sulfate that dissolves in water to form an aqueous solution. This solution is then mixed in a stirred reactor with an alkaline solution, usually consisting almost entirely of sodium hydroxide solution, to carry out a coprecipitation reaction. This reaction is represented by the following chemical formula: Me(SO4) 1+x / 2 + (2+x)NaOH → Me(OH) 2+x + (1+x / 2)Na2SO4(1) (Here, Me(OH) 2+x (where x is the desired solid precursor in the reaction system, Me represents a mixed metal ion with varying valencies, and x is the factor that brings about charge balance between the anion and the cation.) It can be expressed as follows.

[0005] Typically, a filtration process is performed to separate the solid from the liquid. The resulting solid precursor is then mixed with a lithium-containing compound, and the mixture is calcined in a furnace to produce the final lithium-mixed metal oxide material used as a cathode active material.

[0006] However, Me(SO4) 1+x / 2 Furthermore, due to the poor solubility of sodium hydroxide, these coprecipitation steps typically generate a considerable amount of sodium sulfate-containing solution after the removal of solids by filtration. Because the recovered solution contains sodium sulfate, it cannot be reused in the reaction system and must be treated as effluent.

[0007] Furthermore, to help impart the correct physical properties to the precursor material, ammonia is generally added to the reaction system as a chelating agent. As a result, the effluent may contain ammonia, ammonium, dissolved heavy metals, and small solid particles, in addition to salts (e.g., sodium sulfate in most cases). Typically, this effluent must be treated to remove ammonia and sodium sulfate, after which it can be discharged into the environment or recycled back into the reaction system. This effluent treatment is very costly and involves a considerable amount of energy consumption. Moreover, because sodium sulfate has limited industrial uses and demand, it is generally considered solid waste after effluent treatment and therefore provides little to no added value.

[0008] Currently, several methods have been proposed to avoid the generation of leaked liquid. For example, Chinese Patent No. 104409723, granted in 2016, discloses an electrochemical preparation method using lithium mixed metal oxides for the production of cathode active materials in lithium-ion batteries. According to this method, pure nickel, cobalt, and manganese metals are used as raw materials, and nickel, cobalt, and manganese salt compounds are synthesized using electrolysis (at room temperature and atmospheric pressure) with a green electrochemical synthesis method. x Co y Mn z O2, (wherein x is greater than 0 and less than 1, y is greater than 0 and less than 0.8, z is greater than 0 and less than 1, and x + y + z is equal to 1)) can be obtained after a lithium addition reaction, spray drying of the mixture, and high-temperature treatment. According to the description of this patent, the disclosed electrochemical preparation method can be used to reduce raw material costs and energy consumption, simplify the process, reduce environmental pollution, and improve product performance compared to conventional methods.

[0009] Thus, the electrochemical synthesis technique employed by this method is intended to provide an environmentally friendly chemical process. In this method, pure metal (without introduced impurities) is used as the anode material, and as a result, the controllability of nickel ions, cobalt ions, and manganese ions, as well as high purity, can be substantially guaranteed. Furthermore, zero emissions of wastewater into the environment are claimed, and a continuous large-scale production method with little to no wastewater can be realized. However, since organic acids, such as acetic acid and citric acid, are used in this method, a considerable amount of carbon dioxide is generated during the calcination operation, which may be a problem for the quality of the final product (e.g., product density). In addition, considerable energy consumption is expected to be required during the spray drying operation to evaporate the water present in the system.

[0010] A similar method can be found in the specification of Chinese Patent Application Publication No. 102219265 (2011), where nitric acid is used instead of the organic acid, and thermal decomposition is carried out at a high temperature in a controllable atmosphere.

[0011] Another method for producing lithium mixed metal oxides for lithium-ion batteries without significant effluent generation is the "sol-gel" method described by Ching-Hsiang Chen et al. in their paper in the Journal of Power Sources 146; 626-629 (2005). In this approach, layered LiNi x Co 1-2x Mn x O2 powder is synthesized by the sol-gel method using citric acid as a chelating agent. Stoichiometric amounts of lithium acetate, manganese acetate, and nickel acetate and cobalt nitrate are selected as the starting materials used to prepare the precursor. All salts are dissolved in an appropriate amount of distilled water, and citric acid is added dropwise while continuously stirring. After all salts are dissolved, the temperature of the solution is raised to 80-90 °C and stirring is continued until a transparent viscous gel is formed. Such a gel is vacuum dried at 120 °C for 2 hours to obtain a precursor powder. The precursor powder is decomposed in an oxygen stream at 450 °C for 4 hours, pulverized into fine powder, and fired at 900 °C for 12 hours under oxygen flow conditions. The heating and cooling rates are maintained at 2 °C per minute.

[0012] In this method, a significant amount of water needs to be evaporated. In addition, since the organic acid and / or nitrate is involved in the firing and must be decomposed during firing, the energy consumption is large and the density of the final material is expected to be low.

[0013] Furthermore, Huaquan Lu et al. also describe in Solid State Ionics; 249-250, (2013), 105-111 a method for producing lithium mixed metal oxides by the sol-gel method using only nitrates instead of a mixture of organic salts and nitrates. However, this method has substantially the same problems as the previous sol-gel methods.

[0014] To address these challenges, it is advantageous and an object of the present invention to provide a method for producing cathode materials for batteries, particularly lithium-ion batteries, that improves and / or solves the aforementioned effluent problems arising from currently known methods for producing lithium mixed metal oxides. Thus, it is desirable to provide a preferred method that generates little to no effluent. That is, according to this preferred method, substantially the entire liquid from the reaction is completely recycled into the reaction system or a system that can be recycled without any significant treatment. Furthermore, in this preferred method, there is little to no need to evaporate water and / or decompose organic matter or nitrates during the final high-temperature treatment / calcination step. [Overview of the project]

[0015] The advantages described above, as well as other purposes and objectives inherent therein, are provided at least partially or completely by the method of the present invention, as described below.

[0016] In a first aspect, the present invention provides a chemical process for producing a lithium mixed metal oxide as a cathode active material for use in lithium-ion secondary batteries. Such a process comprises two main steps: a wet process for producing a precursor, and a solid-phase reaction called "lithiation" for producing the final cathode material.

[0017] In the method of the present invention, a raw material, preferably mostly metallic, is introduced into an aqueous reaction system. At least one oxidizing agent, such as oxygen, a nitrate, or nitric acid, is introduced into the aqueous reaction system to react with the metal and thereby form a metal hydroxide.

[0018] In the operation, the reaction system usually includes at least one stirring and mixing tank and / or reactor, in which an aqueous slurry of reactants and the resulting product is mixed. A part of the slurry is taken out, and preferably, the unreacted raw metal is taken out from the slurry and recycled to the reactor. In this regard, in order to take out and recycle the unreacted metal raw material from the oxidized metal hydroxide, a separation device such as a magnetic separation device can be installed in the tank or reactor if necessary. After recycling the unreacted metal, a solid-liquid separation operation is performed on the remaining slurry. The filtrate after filtration is preferably recycled to the reaction system for further reaction. The solid is recovered as the precursor material. Then, the recovered precursor material is subjected to a lithiation step.

[0019] It should be noted that in order to start the reaction system, preferably, an artificial "seed" having a desired metal hydroxide composition substantially the same or similar to the recovered precursor material can be prepared and used for starting the reaction.

[0020] Also, an artificial solution having the same or similar composition as the desired filtrate can be prepared and used for starting the reaction until a suitable filtrate is generated from the filtration system.

[0021] In the lithiation step, the solid precursor material produced above is mixed with a lithium-containing compound and optionally other dopants, and then subjected to a firing treatment to obtain the final cathode active material. Thereafter, additional surface treatment and any additional firing treatment (if desired) can be performed if necessary.

[0022] Therefore, in its preferred form, the present invention provides a process for producing a lithium mixed metal oxide as a cathode active material for use in the production of lithium ion batteries, the process comprising the following two main steps, namely, a precursor preparation step and a lithiation step. A) In the precursor preparation step, a solid metal is added to a stirred reaction system which is a reactor containing an aqueous solution containing at least one oxidizing agent, preferably selected from oxygen, metal nitrates and nitric acid, or a combination thereof, and optionally seed-mixed metal hydroxide particles, and the metal is oxidized under alkaline conditions. The overall oxidation reaction is represented by the following equation: xMe + yMe'(NO3) n + zHNO3+ (0.25xm-2yn-2z)O2+ (0.5xm+2yn+z)H2O → Me x Me' y (OH) (xm+yn) + (yn+z)NH3 (Here, Me represents at least one metal selected from the group consisting of nickel, manganese, cobalt, aluminum, and magnesium. Me' represents an ion of at least one metal selected from the group consisting of nickel, manganese, cobalt, aluminum, magnesium, zirconium, yttrium, titanium, vanadium, and molybdenum. Me x Me' y (OH) (xm+yn) represents a precursor, x and y are the mole fractions of Me and Me', respectively; m is the molar-weighted average valency of Me in the precursor; n is the molar-weighted average valency of Me' in the reactants; and z is the mole fraction of HNO3 introduced into the reaction system. xm ≥ 8yn + 8z, x + y = 1, 1 ≥ x > 0, y ≥ 0, z ≥ 0. Represented by, The synthesized slurry from the oxidation reaction is removed from the reactor, unreacted metals are removed from the slurry and recycled back into the reaction system, then solid-liquid separation is performed, the recovered solid is used as a recovered precursor, and the liquid is preferably recycled back into the reaction system directly without any further treatment, and B) In the lithiation process, the recovered precursor is mixed with a lithium-containing compound and, if necessary, other dopants to produce a final mixture, which is then calcined to obtain a cathode active material.

[0023] As a result, the present invention provides a process for producing lithium mixed metal oxides with little to no effluent generation. That is, the present invention provides a system that allows substantially the entire liquid from the reaction to be completely recycled into the reaction system, or can be recycled, without any effluent treatment.

[0024] Furthermore, there is little to no need to evaporate water and / or decompose organic acids or nitrates during the final high-temperature treatment and / or calcination process.

[0025] In terms of additional features, it can be noted that while the process of the present invention can be carried out as a batch process, such a process is particularly well suited to being carried out as a substantially continuous process.

[0026] In a second aspect, the present invention also provides cathode material precursors, where preferred cathode material precursors of the present invention are produced by the above process, and in particular, these particles are produced by the method described in the specification, preferably in a continuous process, preferably in a one-step reaction system. The present invention also provides a final cathode active material, when produced by the process described in the specification, and the cathode produced therefrom.

[0027] In a third aspect, the present invention also provides a battery, wherein the cathode of such a battery is produced by the method described above in relation to the present invention.

[0028] The process of the present invention will be described only as an example, with reference to the accompanying drawings. [Brief explanation of the drawing]

[0029] [Figure 1]Figure 1 is an SEM image of a precursor material produced using the process of the present invention. [Figure 2] Figure 2 shows the XRD spectrum of the precursor material produced using the process of the present invention. [Figure 3] Figure 3 shows a graph of the charge-discharge curve in a half-cell test of the final cathode active material produced using the process of the present invention. [Figure 4] Figure 4 is a process block diagram illustrating a preferred embodiment of the process of the present invention. In the drawings, similar reference numerals represent similar elements. [Modes for carrying out the invention]

[0030] It is well known that metal oxides or hydroxides can be formed by corrosion processes such as the oxidation of metals in aqueous solutions or under humid conditions. This principle is used in the first step of the present invention to produce a precursor hydroxide material from a pure metal, in which a metal corrosion / oxidation reaction and a coprecipitation reaction occur simultaneously, preferably in the same reactor. The overall reaction is given by the following equation: xMe + yMe'(NO3) n + zHNO3+ (0.25xm-2yn-2z)O2+ (0.5xm+2yn+z)H2O → Me x Me' y (OH) (xm+yn) + (yn+z)NH3 (Here, Me represents at least one metal, preferably solid, selected from the group consisting of nickel, manganese, cobalt, aluminum, and magnesium. Me' represents at least one metal selected from the group consisting of nickel, manganese, cobalt, aluminum, magnesium, zirconium, yttrium, titanium, vanadium, and molybdenum, preferably an ion. Me x Me' y (OH) (xm+yn) represents a precursor, x and y are the mole fractions of Me and Me', respectively; m is the molar-weighted average valency of Me in the precursor; n is the molar-weighted average valency of Me' in the reactants; and z is the mole fraction of HNO3 introduced into the reaction system. xm ≥ 8yn + 8z, x + y = 1, 1 ≥ x > 0, y ≥ 0, z ≥ 0. This is shown.

[0031] Oxygen is preferred as an oxidizing agent because, when used, it typically does not produce any significant byproducts during the reaction. Oxygen can be supplied from a pure oxygen source and / or from other gases, such as oxygen in the air.

[0032] Some metal nitrates may be included as oxidizing agents for metal elements that do not readily react with oxygen, or for metal elements that do not readily react during stirring for homogeneous mixing or during processing operations such as magnetic separation of metals.

[0033] Nitric acid can be used as an additional oxidizing agent to control the coprecipitation reaction of metal nitrates. When nitrates and nitric acid are used, ammonia is the only byproduct. However, since the ammonia produced in such a reaction is a gas, it does not remain in the reaction system during the operation. Therefore, in the wet process described above for producing precursors, no additional or new chemicals are added to the liquid after solid-liquid separation has occurred. In this way, the liquid can be directly recycled into the reaction system by at least 75%, more preferably at least 90%, and even more preferably 100%, without adversely affecting the overall reaction.

[0034] The generated ammonia can be recovered as a useful chemical or precursor for other industries, such as the fertilizer industry.

[0035] Other oxidizing agents may be used depending on the reactor conditions.

[0036] To obtain high-quality products with consistent properties, it is preferable to operate the reactions described herein in continuous mode, in which case the reaction reaches steady-state conditions. This allows for better control of the resulting composition. In one preferred approach, an artificial solution having the same or similar composition as the liquids in the reaction system is prepared and used to initiate the reaction, and this is continued until the liquids resulting from the solid-liquid separation operation are similar to the artificial solution.

[0037] The pH of the reaction slurry is preferably 7.5 to 13, more preferably 8 to 12. Preferably, the pH of the solution can be adjusted by adding an acid selected from sulfuric acid, nitric acid, or acetic acid, and / or by adding an alkaline substance selected from lithium hydroxide or lithium oxide, sodium hydroxide or sodium oxide, potassium hydroxide or potassium oxide, or ammonia. Preferably, the pH is adjusted by adding an acid, such as sulfuric acid or nitric acid, to the reaction mixture, and / or by adding an alkaline substance, such as lithium hydroxide or sodium hydroxide. Generally, it should be noted that a low pH value may lead to poor quality coprecipitation products, while a high pH value may cause metal passivation during the corrosion reaction.

[0038] A preferred reaction temperature is 20°C to the boiling point of the reaction slurry, more preferably 20°C to 100°C. Even more preferably, the reaction temperature is 30°C to 80°C.

[0039] Maintaining an acceptable conductivity of the reaction system can also be important for controlling corrosion / oxidation reactions. Therefore, the reaction slurry preferably also contains dissolved salts to form an electrolyte for conductivity. These salts may include salts with cations selected from sodium, lithium, potassium, and ammonium, such as sulfates, acetates, nitrates, and chlorates. Such salts are usually, and preferably, reusable in the recirculated liquid recovered after liquid-solid separation.

[0040] The reaction slurry may also contain dissolved complexing agents, such as a mixture of ammonia and ammonium, which can form chelates with metal ions in aqueous solution. The overall function of these complexing agents or chelating agents is preferably to control the properties of the coprecipitation product and / or to make the metal more active for corrosion reactions.

[0041] A method for producing cathode material may include a step that allows for the "reactivation" of unreacted raw material metals recovered from the slurry by, for example, a magnetic separation step. This may include milling and / or washing these materials with a liquid, usually with a lower pH, obtained in a liquid-solid separation step.

[0042] Furthermore, such a method may also include the step of introducing solid particles having the same or similar composition as the precursor but with a smaller particle size than the precursor into the reaction system at the beginning and / or during the reaction.

[0043] Therefore, preferably, the process of the present invention can be used to produce cathode material precursor particles that are compositionally similar to those of the prior art, having a uniform elemental distribution within each particle, in which the metal is added in a steady-state continuous process in a one-step reaction system. However, the process can also be applied to produce particles having a non-uniform elemental distribution within each particle, for example, cathode material precursor particles with a compositional gradient or layered structure in a multi-step reaction system, by adding different metals at different times. In such a multi-step system, each step can deposit layers of material having different compositions for each function. For example, the core region of the cathode material particle may be nickel-rich for higher capacity, while the surface region may be manganese, magnesium, or aluminum-rich for a stable interface with the electrolyte found in lithium-ion batteries.

[0044] Therefore, such a process provides a system for either continuously adding metal at the same ratio at all times to produce a precursor having a uniform elemental distribution in each particle, or continuously adding metal at different ratios over time to produce a precursor having a heterogeneous elemental distribution in each particle.

[0045] The final cathode active material produced in the present invention is therefore ultimately obtained by mixing a precursor compound with a lithium-containing compound and carrying out a calcination reaction, after which surface treatment can be performed as needed. This process is usually called lithiation, and this lithiation process is usually carried out as a solid-phase reaction at preferably 600°C to 1100°C, depending on the composition of the final material. Oxidation conditions may also be required as part of the lithiation reaction step. Preferably, air, oxygen, and nitrates are used as oxidizing agents.

[0046] For most applications, lithium hydroxide with or without crystal water, and lithium carbonate are preferably used as lithium sources.

[0047] After lithiation, light crushing / milling may be required in a size reduction operation to break up coarse aggregates formed during the lithiation process. Subsequently, surface treatment as needed, such as washing to remove excess lithium hydroxide / lithium carbonate and other impurities, and coating may be required or desired to stabilize the surface of the material. Thus, the cathode material may be subjected to further processing after firing, such further processing including washing to remove excess lithium and other unwanted impurities, and coating the cathode material to improve the performance of the cathode material during battery production and / or battery use. Further firing steps may be performed if necessary or desired.

[0048] Novel features that are considered characteristic of the present invention, with respect to its structure, configuration, use, and operation, along with their further objectives and advantages, will be better understood from the following examples, and preferred embodiments of the present invention will be described hereby only as examples.

[0049] However, it should be clearly understood that the examples and drawings are for illustrative and explanatory purposes only and are not intended to define the scope of the invention. Furthermore, unless otherwise specified, all features described in the specification may be combined in any combination with any of the aspects described above. [Examples]

[0050] In accordance with preferred embodiments of the present invention, the process of the present invention and the properties of the resulting substance are described in the following examples.

[0051] Example 1 Following the production process outlined as 10 in Figure 4, a 1.1 L aqueous solution was prepared and transferred to a 2 L reaction vessel equipped with a stirring system and a heating system. This aqueous solution contained 1 mole of sodium sulfate as the electrolyte and 50 mL of 28% ammonia solution as a complexing agent. This solution was heated to 60°C and stirred at approximately 750 rpm. Approximately 150 g of mixed metal hydroxide powder was added to the reaction vessel as a seed component. Here, the metal hydroxide powder mainly contained nickel hydroxide and a very small amount of cobalt hydroxide (less than 5% cobalt by metal molar weight).

[0052] The pH of the aqueous solution was adjusted to 10.5 by adding ammonia and sodium hydroxide to the reaction vessel. 87 g of nickel metal powder and 13 g of cobalt metal powder were also added to the reaction vessel. After about 60 minutes, approximately 7.2 g of nickel powder and 1.08 g of cobalt powder were further added to the reaction vessel every 60 minutes. This formed the raw materials for this reaction.

[0053] In addition, oxygen was continuously introduced into the reaction vessel at a rate of approximately 26.5 mL per minute as an oxidizing agent.

[0054] Approximately 50 mL of slurry was collected from the reaction vessel every hour, and this collected slurry was subjected to a magnetic separation process to separate the unreacted magnetic raw material metal from the metal hydroxide. The separated unreacted magnetic raw material metal was returned to the reaction vessel. Then, the non-magnetic solids were filtered from the remaining slurry and washed with water. All of the remaining filtrate, along with the washing water, was returned to the reaction vessel.

[0055] Next, the solid obtained in the filtration process was dried at approximately 100°C for approximately 5 hours to be used as a precursor for use in the present invention.

[0056] The above procedure was repeated continuously for 100 hours. After reaching steady-state conditions, the dried solid material from the last 24 hours of operation was collected as a good precursor material sample. The particle size D50 of the collected precursor material was approximately 10 μm. The tap density of the collected precursor material was approximately 2.1 g / cm³. 3 The scanning electron microscope (SEM) image, as shown in Figure 1, revealed spherical particles containing fine primary particles.

[0057] The analysis results showed that the product composition eventually reached a steady state with the target elemental molar ratio of Ni:Co = 0.87:0.13.

[0058] Cross-sectional analysis of the recovered material using energy-dispersive scanning electron microscopy (SEM / EDX) revealed that all target metal elements were uniformly distributed within each precursor particle. As shown in Figure 2, the X-ray diffraction (XRD) spectrum also indicated that the resulting product was a single phase.

[0059] Example 2 Similar to Example 1, approximately 1.2 L of aqueous solution was prepared and transferred to a 2 L reaction vessel. This aqueous solution contained approximately 1 M ammonium nitrate and 0.5 M sodium nitrate. The solution was heated to approximately 60°C while being stirred at approximately 700 rpm. The temperature was maintained by a temperature controller and a heating mantle integrated with a J-type thermocouple. Ammonia was then added to the reaction vessel to adjust the pH of the aqueous solution to approximately 10.0 at 60°C.

[0060] Approximately 135 g of nickel metal powder and 15 g of metallic cobalt powder were added to the reaction vessel. Furthermore, approximately 150 g of mixed metal hydroxide powder was also added to the reaction vessel as nickel hydroxide and cobalt hydroxide. Here, the mixed metal hydroxide powder contains nickel and cobalt in an atomic ratio of approximately 0.9:0.1.

[0061] After approximately 60 minutes, 7.2 g of nickel metal powder and 0.8 g of cobalt metal powder were added to the reaction vessel every hour. Furthermore, approximately 2% aluminum was added in the form of aluminum nitrate, prepared by dissolving aluminum hydroxide in 68% nitric acid. Nitric acid and oxygen were also simultaneously introduced into the reaction vessel at rates of 0.04 ml / min and 18 ml / min, respectively.

[0062] Sample collection was performed every 3 hours by collecting 100 ml of slurry sample. Magnetic separation was performed, and the magnetic portion was returned to the reaction vessel. The non-magnetic portion was filtered, washed with distilled water, and the filtrate was returned to the reaction vessel along with all the washing water.

[0063] The filtered solid cake was dried as a precursor at approximately 100°C for about 6 hours.

[0064] The above sampling procedure was repeated continuously for 100 hours, and the dried solid recovered from the last 24 hours of operation was used as a good sample of the precursor material. The analytical results showed that the product composition reached a steady state with the target atomic ratio of Ni:Co:Al = 0.865:0.097:0.038.

[0065] Example 3 Approximately 6 g of lithium hydroxide monohydrate was selected and manually granulated using a mortar and pestle to reduce the particle size. Next, approximately 1 g of this granulated lithium hydroxide monohydrate was mixed with 2 g of the precursor material recovered in Example 1, and the mixture was transferred to an alumina crucible. The mixture was calcined in a tubular furnace. During calcination, oxygen was continuously supplied to the tubular furnace at a rate of approximately 220 mL per minute.

[0066] The temperature was increased at a rate of 10°C per minute to 800°C. It was held at 800°C for 10 hours, and then the temperature was decreased at approximately 5°C per minute. The solid recovered after the calcination process was manually granulated to break up agglomeration, and this material was then placed in a beaker containing approximately 30 mL of cold water at approximately 5°C. After stirring for approximately 2 minutes, the mixture was quickly filtered, and the recovered solid was placed in an alumina crucible and calcined again in a tubular furnace at approximately 710°C for 5 hours. The resulting calcined solid composition was recovered as the final cathode-activated product.

[0067] Example 4 In Example 3, the final cathode activation product recovered was used as the cathode active material, and lithium metal foil was used as the anode active material for a coin-type battery half-cell test. The cathode electrode was prepared using a component consisting of 90% final cathode activation product, 6% carbon black, and 4% polyvinylidene fluoride (PVDF). The electrolyte used in the test was 1M LiPF6 with ethylene carbonate (EC) / diethyl carbonate (DEC) / ethyl methyl carbonate (EMC) (EC / DEC / EMC volume ratio of 1:1:1) as the solvent. The voltage during the first charge and first discharge was 3V to 4.3V at 0.05C (1C = 150mAh / g).

[0068] Figure 3 shows the charge-discharge curve for the first cycle of the test. The capacity after the first discharge was approximately 192 mAh / g, with a Coulomb efficiency of approximately 88%.

[0069] Therefore, it is clear that the present invention provides processes, products, and batteries that fully satisfy the above-mentioned objectives, purposes, and advantages. While specific aspects of the present invention have been described, it will be understood that alternatives, modifications, and variations thereof can be suggested to those skilled in the art, and that this specification is intended to encompass all alternatives, modifications, and variations that fall within the scope of the claims.

Claims

1. A process for producing lithium mixed metal oxides as cathode active materials for use in the production of lithium-ion batteries, the process comprising the following two main steps: a precursor preparation step and a lithiation step. A) In the precursor preparation step, a solid metal is added to a stirred reaction system which is a reactor containing an aqueous solution containing at least one oxidizing agent, preferably selected from oxygen, metal nitrates and nitric acid, or a combination thereof, and optionally seed-mixed metal hydroxide particles, and the metal is oxidized under alkaline conditions. The overall oxidation reaction is represented by the following equation: xMe + yMe'(NO ３ ) ｎ + ]HNO ３ + (0.258m-2yn-2z)O ２ + (0.58m+2yn+z)H ２ O → Me ｘ Me’ ｙ (OH) （ｘｍ＋ｙｎ） + (yn+z)NH ３ (Here, Me represents at least one metal selected from the group consisting of nickel, manganese, cobalt, aluminum, and magnesium. Me' represents an ion of at least one metal selected from the group consisting of nickel, manganese, cobalt, aluminum, magnesium, zirconium, yttrium, titanium, vanadium, and molybdenum. Me ｘ Me' ｙ (OH) （ｘｍ＋ｙｎ） represents a precursor, x and y are the mole fractions of Me and Me', respectively; m is the molar-weighted average valency of Me in the precursor; n is the molar-weighted average valency of Me' in the reactant; and z is the HNO introduced into the reaction system. ３ This is the mole fraction, xm ≥ 8yn + 8z, x + y = 1, 1 ≥ x > 0, y ≥ 0, z ≥ 0. Represented by, The synthesis slurry from the oxidation reaction is removed from the reactor, unreacted metals are removed from the slurry and recycled back into the reaction system, then solid-liquid separation is performed, the recovered solid is used as a recovered precursor, and the liquid is preferably recycled back into the reaction system directly without any further treatment, and B) In the lithiumization step, the recovered precursor is mixed with a lithium-containing compound and, if necessary, other dopants to produce a final mixture, and then the final mixture is calcined to obtain a cathode active material.

2. A method for producing a cathode material according to claim 1, wherein the reaction conditions in the precursor preparation step include setting the pH of the slurry to 7.5 to 13 during the reaction and the temperature to 20°C to the boiling point of the slurry.

3. A method for producing a cathode material according to claim 2, comprising adding an acid selected from sulfuric acid, nitric acid, or acetic acid to the solution, and / or adjusting the pH of the solution by adding an alkaline substance selected from lithium hydroxide or lithium oxide, sodium hydroxide or sodium oxide, potassium hydroxide or potassium oxide, or ammonia.

4. A method for producing a cathode material according to claim 1, wherein the aqueous solution also contains a dissolved salt to increase conductivity.

5. A method for producing a cathode material according to claim 4, wherein the dissolved salt is selected from sulfates, acetates, nitrates, and chlorates with a cation selected from sodium, lithium, potassium, and ammonium.

6. A method for producing a cathode material according to claim 1, wherein the aqueous solution also contains a complexing agent that forms a chelate with the metal ions in the aqueous solution.

7. A method for producing a cathode material according to claim 6, wherein the complexing agent comprises a mixture of ammonia and ammonium.

8. The method for producing a cathode material according to claim 1, wherein the oxidizing agent is air, oxygen, a metal nitrate or nitric acid, or a combination of two or more oxidizing agents used simultaneously.

9. The method for producing a cathode material according to claim 1, wherein the oxidizing agent is oxygen.

10. A method for producing the cathode material according to claim 9, wherein the oxygen is contained in another gas.

11. A method for producing a cathode material according to claim 1, wherein the reaction system in the precursor preparation step includes at least one stirring tank.

12. A method for producing a cathode material according to claim 1, comprising reactivating the unreacted metal by milling and / or washing using the liquid from the solid-liquid separation step.

13. A method for producing a cathode material according to any one of claims 1 to 12, wherein the reaction in the precursor preparation step is operated in a continuous operation mode under steady-state conditions.

14. A method for producing a cathode material according to claim 13, comprising continuously adding the metal at the same ratio at all times to produce a precursor having a uniform elemental distribution in each particle, or continuously adding the metal at different ratios over time to produce a precursor having a non-uniform elemental distribution in each particle.

15. A method for producing a cathode material according to claim 1, wherein at least 90% of the liquid recovered after the solid-liquid separation is directly recirculated into the reaction system.

16. A method for producing a cathode material according to claim 1, comprising introducing solid particles having the same or similar composition as the precursor but with a smaller particle size than the precursor into the reaction system at the beginning of the reaction and / or during the reaction.

17. A method for producing a cathode material according to claim 1, comprising preparing an artificial solution having the same or similar composition as the aforementioned liquid, using it to initiate the reaction until a suitable filtrate is generated from the filtration system, and then recirculating it to the reaction system.

18. A method for producing a cathode material according to claim 1, further comprising drying the solid to obtain the precursor, mixing the precursor with a lithium-containing compound, calcining the mixture, and thereby obtaining a cathode active material.

19. A method for producing a cathode material according to claim 18, wherein the obtained cathode active material is subjected to a size reduction operation.

20. A method for producing a cathode material according to claim 1, wherein the lithium-containing compound is lithium hydroxide with or without crystal water, and lithium carbonate.

21. A method for producing the cathode material according to claim 1, comprising firing the final mixture at 600°C to 1100°C.

22. A method for producing a cathode material according to claim 1, wherein the cathode material is subjected to further processing after firing, the further processing includes washing to remove excess lithium and impurities, and coating the cathode material to improve the performance of the cathode material during battery production and / or battery use.

23. A lithium mixed metal oxide for use as a cathode active material for lithium-ion secondary batteries, manufactured according to the process described in any one of claims 1 to 22.

24. A lithium secondary battery comprising a lithium metal oxide as a cathode material, wherein the cathode material is a mixed metal oxide manufactured according to the process described in any one of claims 1 to 22.

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