Method for directly preparing high-nickel positive electrode material for lithium battery from salt lake brine

Abstract

The application discloses a method for directly preparing a high-nickel positive electrode material of a lithium battery by using salt lake brine, and comprises the following steps: (1) oxidizing a transition metal precursor at a certain temperature to obtain a hydroxyl transition metal oxide; after the reaction is completed, the product is washed and dried to obtain the hydroxyl transition metal oxide; (2) granulating the obtained hydroxyl transition metal oxide to serve as a lithium extraction medium, and assembling the lithium extraction medium into an ion exchange device in cooperation with a heating device; (3) adding the salt lake brine into the ion exchange device and heating the obtained hydroxyl transition metal oxide, and standing to perform a Li + / H + exchange reaction to extract lithium, so that the high-nickel positive electrode material of the lithium battery is obtained. The application reduces the elution step required in a traditional lithium extraction process of the salt lake brine. The application can complete lithium intercalation under low-temperature conditions, and combines with short-time high-temperature sintering to rapidly prepare the positive electrode material, so that the energy consumption in the positive electrode preparation process is greatly reduced, and the cost is saved.

Description

Technical Field

[0001] This invention relates to a method for extracting lithium from salt lake brine, and more particularly to a method for directly preparing high-nickel cathode materials for lithium batteries using salt lake brine, belonging to the technical field of lithium extraction from salt lake brine and preparation of cathode materials for lithium-ion batteries. Background Technology

[0002] In recent years, lithium-ion batteries, as an environmentally friendly energy storage method, have been widely used in automobiles, energy storage, and other fields. Lithium, the raw material for lithium-ion batteries, mainly exists in the form of salt lake brines and hard-rock lithium deposits. Of the world's proven lithium resources, over 60% are found in salt lake brines (primarily in the "Lithium Triangle" of South America and the Qinghai-Tibet Plateau in China), while hard-rock lithium deposits (such as spodumene in Australia) account for only about 30%. The situation is even more pronounced in China, where over 80% of lithium resources are stored in salt lake brines. Therefore, developing lithium extraction technology from salt lake brines is an essential path to effectively utilize domestic resources and reduce dependence on imports.

[0003] Currently, methods for extracting lithium from salt lake brine mainly include evaporation crystallization, co-precipitation, solvent extraction, and adsorption, with solvent extraction and adsorption being the mainstream research directions. Adsorption primarily utilizes the selective adsorption characteristics of lithium ions by adsorbents such as aluminum-based, manganese-based, and titanium-based adsorbents to extract lithium ions from salt lake brine. CN 117821775 A discloses a method using titanium-based adsorbents to perform multiple adsorption treatments on salt lake brine, achieving a lithium adsorption capacity of over 95%. This process avoids the problem of poor adsorption effect caused by the mismatch between the lithium ion adsorption capacity of the adsorption resin column and the lithium ion concentration of the salt lake brine. However, it still requires elution with acidic reagents such as hydrochloric acid, followed by the use of sodium carbonate to convert the lithium in the solution into lithium carbonate precipitate for subsequent use. In addition, the literature "New Insights into the Application of Lithium-Ion Battery Materials: Selective Extraction of Lithium from Brines via a Rocking-Chair Lithium-Ion Battery" further explores this approach. The "System" proposes using a lithium-rich phase LiFePO4 and a lithium-poor phase FePO4 as the anode and cathode, respectively. Sodium chloride solution and brine from a salt lake are injected into the anode and cathode chambers, respectively, and separated by an anion exchange membrane. When electricity is applied, lithium insertion at the cathode and delithiation at the anode are achieved. After the lithium ion insertion at the cathode reaches its upper limit, the electrode is exchanged, and lithium insertion continues until the lithium in the brine is almost completely adsorbed. In contrast, solvent extraction often involves mixing brine with an immiscible organic phase. The lithium ions in the brine react with the extractant in the organic phase through physical processes or chemical reactions, such as forming complexes or chelates with the lithium ions, thereby transferring the lithium-containing phase into the organic phase to achieve the effect of lithium extraction. Chinese patent CN102001692B uses the extractant TBP and the co-extractant BA to combine with lithium in the form of LiFeCl4, thereby allowing lithium to enter the organic phase and achieving effective separation of lithium from other components in the aqueous phase. After extraction, hydrochloric acid elution is still required. Both lithium extraction methods have low energy consumption and low cost. However, they both require elution after lithium extraction to prepare lithium carbonate, which is then used to prepare lithium-ion battery cathode materials, making the overall process lengthy.

[0004] In addition, CN119976975 A proposed a method for first preparing γ-MnOOH and then using the prepared γ-MnOOH to treat Li in salt lake brine. + The process of directly preparing LiMnO2 by adsorption followed by high-temperature sintering. Although this method skips the elution step to prepare Li2CO3, it has the following two problems: 1. The Mn element in γ-MnOOH has a +3 valence state. Referring to the standard electrode potential table, E...θ (Mn) 3+ / Mn 2+ ) = 1.51V, E θ (MnO2 / Mn 3+ Mn = 0.95V. Based on the relationship between the standard electrode potential and the standard Gibbs free energy change, Mn... 3+ A disproportionation reaction occurs to generate Mn. 2+ And MnO2, the ΔG of this reaction θ =-nF(E θ (Mn) 3+ / Mn 2+ )-E θ (MnO2 / Mn 3+ ))=-54.031kJ / mol<0, exhibiting a strong tendency for disproportionation and poor stability; 2. Mn 3+ A strong Jhan-Teller effect exists. The paper "Interface-Mediated Jahn-Teller Effect in Structure-Reinforced LiMnO2Cathode" mentions that due to Mn... 3+ The ions possess a high spin electron configuration (t²g³eg¹), which undergoes Jahn-Teller distortion in an octahedral crystal field. This causes the MnO₆ octahedrons to elongate along a certain direction, disrupting the crystal structure. This leads to the loss of Li₂ in LiMnO₂. + Difficult insertion / extraction, resulting in low actual capacity and cycling efficiency. In contrast, LiNi... x Co y Mn 1-x-y In the condition (0.8≤x≤1, 0≤y≤0.2), Mn has a +4 valence and the Jahn-Teller effect does not exist, while Ni is the dominant valence. 3+ Having a low spin electron configuration (t2g) 6 eg¹) There is only a weak Jahn-Teller effect, the distortion is weak, the impact on actual capacity is not significant, and the actual utilization value is better.

[0005] In recent years, with the increasing demand for lithium-ion power batteries, more than 85% of the lithium extracted from salt lake brines globally is used to prepare lithium-ion batteries, and it is also mainly used to prepare cathode materials in lithium-ion batteries. However, current research mainly focuses on converting lithium extracted from salt lakes into lithium carbonate, which increases the cost and complexity of the process. Therefore, there is a need to develop a process that can directly utilize lithium from salt lake brines to prepare cathode materials. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide a method for directly preparing high-nickel cathode materials for lithium batteries using salt lake brine with low cost and simple method.

[0007] The technical solution adopted by the present invention to solve its technical problem is as follows:

[0008] A method for directly preparing high-nickel cathode materials for lithium batteries using salt lake brine includes the following steps:

[0009] (1) At a certain temperature, the transition metal precursor is oxidized to obtain hydroxyl transition metal oxide; after the reaction is complete, the product is washed and dried to obtain hydroxyl transition metal oxide.

[0010] (2) The hydroxyl transition metal oxide obtained in step (1) is granulated and used as a lithium extraction medium, and then assembled into an ion exchange device with heating equipment.

[0011] (3) Add brine from the salt lake to the ion exchange apparatus and heat the obtained hydroxyl transition metal oxides, then let it stand for Li... + / H + Lithium is extracted through an exchange reaction, thus obtaining a high-nickel cathode material for lithium batteries.

[0012] Further, in step (1), the transition metal precursor is oxidized to obtain hydroxyl transition metal oxides by liquid-phase chemical oxidation, gas-phase oxidation, or electrochemical oxidation at a certain temperature. If liquid-phase chemical oxidation is used, an alkaline reagent is needed to adjust the pH to >9, and the concentration of the alkaline reagent in the reaction mixture is controlled at 1-10 mol / L. The amount of oxidant used is 1-5 times the theoretically required mass of oxidant. The alkaline reagent used is at least one of soluble bases such as LiOH, NaOH, KOH, and ammonia. The oxidant used is at least one of strong oxidants such as O3, NaClO, Na2S2O8, KMnO4, K2S2O8, H2O2, and (NH4)2S2O8. If gas-phase oxidation is used, the oxidant used includes one or more of strong gaseous oxidants such as Cl2, F2, and O3. If electrochemical oxidation is used, the electrolyte should include soluble alkalis such as LiOH, NaOH, KOH, and ammonia, or at least one of AMCl, AM2SO4, and AMNO3 (AM = at least one of Li, Na, K, Rb, and Cs); the electrolysis current should be between 0.01 and 10 A, and the pH of the electrolyte should be greater than 9. Sufficient contact between the transition metal precursor and the anode must be ensured during the reaction.

[0013] Further, in step (1), the transition metal precursor is at least one of TMSO4, TM(NO3)2, TMCl2, TM(OH)2, TMCO3, and (CH3COO)2TM; TM = at least one of Ni, Co, and Mn, wherein the mole fraction of Ni is ≥0.8. TM is Ni x Co y Mn 1-x-y 0.8≤x≤1, 0≤y≤0.2. The general formula for hydroxyl transition metal oxides is TMOOH.

[0014] Furthermore, in step (1), the reaction temperature is 10~100℃ and the reaction time is 0.25-24h.

[0015] Furthermore, in step (1), drying is performed by placing the product in a vacuum oven.

[0016] Furthermore, in step (2), the instruments and methods used for granulation include at least one of the following: stirring granulation, fluidized bed granulation, spray drying granulation, pressure molding granulation, spray and dispersion misting, and hot melt molding.

[0017] Furthermore, in step (2), the qualified particle size of the lithium extraction medium is 1-50 μm. The shape of spherical particles is optimal.

[0018] Furthermore, in step (2), a particle size analyzer and a scanning electron microscope are used to detect whether the particle size and morphology of the prepared lithium extraction medium meet the requirements, and the particles that meet the requirements are used as the lithium extraction medium.

[0019] Furthermore, in step (3), the brine used has a Li+ concentration of 0.01 g / L to 2 g / L, and a Li... + / Mg 2+ In 0.001-2000, Na + The concentration ranges from 0.3 g / L to 100 g / L.

[0020] Furthermore, in step (3), the exchange host of the ion exchange device is a hydroxyl transition metal oxide, and the form of the exchange host includes at least one of the following: chromatography column, fixed bed ion exchanger, moving bed ion exchanger, fluidized bed ion exchanger, hydrothermal reactor, etc.

[0021] Furthermore, in step (3), the heating temperature of the hydroxyl transition metal oxide is 20-350℃, and the exchange time is 0.1-480h.

[0022] Furthermore, in step (3), the exchanged salt lake brine is released and new salt lake brine is added. After repeating the above process multiple times, the lithium-intercalated fixed phase particles are taken out and the lithium intercalation amount is tested. Particles with the required lithium intercalation amount are subjected to short-time high-temperature annealing to obtain high-nickel cathode material for lithium batteries.

[0023] Furthermore, in step (3), the number of repeated exchanges is more than 1.

[0024] Furthermore, in step (3), the short-time high-temperature annealing temperature is 350-1050℃ and the annealing time is 0.5-2h.

[0025] This invention utilizes the characteristic that hydroxyl transition metal oxides are easy to insert lithium into, and directly prepares battery cathode materials through multiple chromatography ion exchange reactions, which significantly reduces the cost and complexity of lithium extraction processes from salt lakes.

[0026] This invention utilizes chemical oxidation or electrochemical oxidation to first convert TMSO4, TM(NO3)2, TMCl2, TM(OH)2, TMCO3, and (CH3COO)2TM (TM = one or more of Ni, Co, and Mn, wherein the mole fraction of Ni is ≥0.8) into TMOOH (TM = one or more of Ni, Co, and Mn), while simultaneously removing half of the H from the interlayer. + This makes Li + Easier to embed, the resulting TMOOH was finally granulated and used as a lithium extraction medium, and Li was generated under conditions of 20-350℃. + / H + The exchange reaction simultaneously achieves lithium intercalation and the preparation of a lithium-ion battery cathode. By eliminating the need for elution and Li2CO3 preparation after lithium extraction from brine in salt lakes, this invention significantly reduces process steps and material costs. Furthermore, the lower reaction temperature greatly reduces power consumption during cathode material preparation, resulting in high economic and environmental value. The principle of this invention: This invention utilizes chemical oxidation to oxidize TMSO4, TM(NO3)2, TMCl2, TM(OH)2, TMCO3, and (CH3COO)2TM (TM = one or more of Ni, Co, and Mn) to TMOOH. In particular, for transition metal hydroxide precursors containing Ni, due to Ni... 3+ / Ni 2+ The standard potential is 1.5V, and Ni 3+ It is difficult for nickel to exist in aqueous solution, and the only common trivalent nickel compound is NiOOH. Therefore, the preparation of hydroxyl oxide precursors with high trivalent nickel content requires an oxidant with strong oxidizing properties under alkaline conditions. The reaction equation for this process is as follows (using S2O8 as the oxidant). 2- For example, taking TM(OH)2 as a precursor):

[0027] ①

[0028] From the perspective of chemical reaction equations, the forward reaction tends to increase as the pH of the solution increases. However, excessive alkali dissolved in the solution will lead to a decrease in the concentration of the oxidant, which will reduce the oxidation effect. Therefore, the appropriate concentration of alkali in the reaction mixture is 1-10 mol / L.

[0029] After oxidation, TMOOH has half the H content in the interlayer compared to TM(OH)2. + This increases the electrostatic repulsion between transition metal layers and weakens the hydrogen bond strength between layers, thus increasing the interlayer spacing; in addition, due to H + The reduction of H between transition metal layers + The occupied tetrahedral positions are released. Considering the above two factors, TMOOH is more suitable for lithium intercalation reactions. Figure 1 This refers to the experimentally measured values ​​of the interlayer spacing and crystal structure of β-Ni(OH)2 and β-NiOOH mentioned in the paper "Structural and Electronic Features of β-Ni(OH)2 and β-NiOOH from First Principles" (taking high-nickel materials as an example).

[0030] This invention granulates the prepared TMOOH, and by controlling parameters such as temperature and pressure, the particle size can be changed to obtain smaller particles, thereby increasing the contact area with the brine and improving the lithium intercalation efficiency. When used as a stationary phase in a chromatography column for ion exchange lithium extraction, since the lithium in the brine mainly exists in the form of LiCl, the lithium intercalation process... + / H + The main reactions that occur during the exchange are:

[0031] ②

[0032] The HCl byproduct of lithium extraction dissolves in water, which lowers the pH of brine in salt lakes. Therefore, a small amount of soluble alkali is usually added to the brine to adjust the pH. Additionally, to minimize the loss of soluble alkali, the chromatography column needs to be heated, which not only provides Li... + / H + The exchange-driven force ensures the timely dissipation of generated HCl, preventing localized acidity in the chromatography column and reducing TMOOH decomposition. Furthermore, after lithium intercalation for a period, the brine needs to be replaced with fresh brine for repeated washing to prevent the degradation of Li in the old brine. + When the concentration is reduced too much, TMOOH reacts with water in the following side reaction:

[0033] ③

[0034] This invention first converts the transition metal precursor into a hydroxyl transition metal oxide. Because the hydroxyl transition metal oxide has a larger interlayer spacing and the H atoms in the interlayer... + Occupying only half of the tetrahedral vacancies, it can effectively reduce Li + The repulsive forces between the interlayers make the interlayer structure more conducive to lithium ion insertion. The obtained hydroxyl transition metal oxide was prepared into particles with a size of 1-50 μm and used as a medium for extracting lithium ions from salt lake brine in a lithium extraction device. This utilizes the fact that it facilitates lithium ion insertion while being less conducive to Mg... 2+ Ca 2+ K + The plasma intercalation characteristic allows for the direct preparation of layered oxide cathode materials by heating hydroxyl metal oxides to 20-350℃ and performing multiple ion exchanges with brine from salt lakes. This method directly converts lithium in brine into lithium-ion battery cathode materials in one step, simplifying the traditional brine lithium extraction process which involves using lithium adsorbents to extract lithium, preparing lithium carbonate, and then using lithium carbonate to prepare battery cathodes. This method is simple, has mild reaction conditions, low equipment requirements, and high lithium intercalation rates, offering significant cost and environmental advantages, and providing a reliable route for the low-cost synthesis of layered oxide cathode materials.

[0035] Compared with existing lithium extraction processes from salt lake brine, the technical concept and process principle of this invention have significant characteristics and technical advantages, specifically:

[0036] (1) The washing steps required for the traditional lithium extraction process from salt lake brine are reduced, and the three-step process of lithium-Li2CO3-lithium-ion battery cathode from salt lake brine is shortened to a two-step process of lithium-lithium-ion battery cathode from salt lake brine. This scheme can also be used for the direct preparation of cathodes from lithium ore.

[0037] (2) Compared with the traditional battery cathode preparation process, which requires long-term (>10h) sintering at high temperature (>500℃), this process can complete lithium intercalation at low temperature and combine short-time (0.5-2h) high-temperature sintering to quickly prepare cathode materials, which greatly reduces energy consumption in the cathode preparation process and saves costs. Attached Figure Description

[0038] Figure 1 Experimental measured values ​​of interlayer spacing and crystal structure diagrams for β-Ni(OH)2 and β-NiOOH;

[0039] Figure 2 The above are XRD patterns of the cathode materials obtained after lithium extraction from salt lake brine in Examples 1-3.

[0040] Figure 3This is the first charge-discharge curve of the cathode material obtained after lithium extraction from salt lake brine in Example 1;

[0041] Figure 4 This is the first charge-discharge curve of the cathode material obtained after lithium extraction from salt lake brine in Example 2;

[0042] Figure 5 This is the first charge-discharge curve of the cathode material obtained after lithium extraction from salt lake brine in Example 3;

[0043] Figure 6 SEM images and particle size measurements of the cathode material obtained after lithium extraction from salt lake brine in Example 1;

[0044] Figure 7 SEM images and particle size measurement results of the cathode material obtained after lithium extraction from salt lake brine in Example 2;

[0045] Figure 8 The image shows the SEM image and particle size measurement results of the cathode material obtained after lithium extraction from salt lake brine in Example 3. Detailed Implementation

[0046] The present invention will be further described below with reference to embodiments and accompanying drawings.

[0047] Example 1

[0048] Dissolve 29.2g of K₂S₂O₈ in 200mL of water with constant stirring at 40℃. Then dissolve 16.83g of KOH in 100mL of water. As the solution gradually cools, slowly add the dissolved KOH to the K₂S₂O₈ solution and mix thoroughly. Finally, add 10g of Ni. 0.83 Co 0.11 Mn 0.06 In a mixed solution of (OH)₂, the molar ratio of the three substances is KOH:K₂S₂O₈:Ni. 0.83 Co 0.11 Mn 0.06 The (OH)₂ ratio was 3:1:1. After heating at 40℃ for 18 hours, the material turned black. The material was washed and dried to remove the oxidant and alkali. The material was then prepared into a suspension and placed in a spray dryer with the inlet air temperature controlled at 150℃, the outlet air temperature at 80℃, and the atomization pressure at 2MPa, yielding spherical particles with a diameter of approximately 12μm. These particles were then placed in a heated glass chromatography column. Subsequently, 1L of salt lake brine (Li₂) was added. + The concentration is 0.3 g / L, Mg 2+ The concentration is 3 g / L, Na +The concentration was 10 g / L. The temperature of the heated chromatography column was raised to 90 °C, and the pH was adjusted to 11 with KOH before lithium extraction. After 10 hours of lithium extraction, the next batch of brine from the salt lake was replaced. This process was repeated 5 times to obtain lithium-intercalated LiNi. 0.83 Co 0.11 Mn 0.06 After the reaction was complete, the lithium intercalation content of the material was tested by ICP, and then annealed at 750℃ for 2 hours at a heating rate of 5℃ / min to obtain the cathode material.

[0049] The obtained LiNi 0.83 Co 0.11 Mn 0.06 O2 was used for charge and discharge performance testing. After standing for 10 hours, it was charged at a constant current of 0.1C to 4.3V under a voltage of 2.7-4.3V, and then charged at a constant voltage until the current was less than 0.05C. The charging specific capacity was recorded. Then it was discharged at a constant current of 0.1C to 2.7V, and the discharge specific capacity was recorded.

[0050] Example 2

[0051] Take 10g Ni 0.96 Co 0.02 Mn 0.02 (OH)₂ was reacted in a tube furnace with ozone generated by an ozone generator at a rate of 150 mg / L. The reaction was carried out at room temperature for 10 hours. The exhaust gas was absorbed using a saturated Na₂S₂O₃ solution, and the material gradually turned black. The material was then prepared into a suspension and placed in a spray dryer with the inlet air temperature controlled at 150°C, the outlet air temperature at 80°C, and the atomization pressure at 2 MPa, yielding spherical particles with a diameter of approximately 12 μm. These particles were then placed in a hydrothermal reactor, and 1 L of salt lake brine (Li₂) was added. + The concentration is 0.5 g / L, Mg 2+ The concentration is 3 g / L, Na + The concentration was 12 g / L, and the filling degree was adjusted to 60%. The reaction temperature was controlled at 95℃, and the pH was adjusted to 11 with KOH before lithium extraction. After 10 hours of lithium extraction, the next batch of brine from the salt lake was replaced, and this process was repeated 5 times to obtain lithium-intercalated LiNi. 0.96 Co 0.02 Mn 0.02 After the reaction is complete, the lithium intercalation content of the material is tested by ICP. Then, the material is annealed at 700℃ for 2 hours at a heating rate of 5℃ / min to obtain the cathode material.

[0052] The obtained LiNi 0.96 Co 0.02 Mn 0.02O2 was used for charge and discharge performance testing. After standing for 10 hours, it was charged at a constant current of 0.1C to 4.3V under a voltage of 2.7-4.3V, and then charged at a constant voltage until the current was less than 0.05C. The charging specific capacity was recorded. Then it was discharged at a constant current of 0.1C to 2.7V, and the discharge specific capacity was recorded.

[0053] Example 3

[0054] Prepare 100 ml of 2 mol / L KOH solution as the electrolyte, place it in the electrolytic cell, and weigh 10 g of Ni. 0.96 Co 0.02 Mn 0.02 (OH)₂ was dispersed in an electrolytic cell using a nonwoven vinylon membrane. Both positive and negative electrodes were nickel foam. The electrolytic cell was placed in a water bath at 50°C, with an applied electrolytic current of 0.2A and a stirring speed of 500 r / min. After 5 hours of electrolysis, the product changed from dark green to black. The material was then washed, dried, and the oxidant and alkali were removed. The material was then prepared into a suspension and placed in a spray dryer with an inlet air temperature of 150°C, an outlet air temperature of 80°C, and an atomization pressure of 2 MPa to obtain spherical particles with a diameter of approximately 12 μm. These particles were then placed in a fixed-bed ion exchanger, and 1 L of brine (Li₂) was added. + The concentration is 0.7 g / L, Mg 2+ The concentration is 7 g / L, Na + The concentration was 13 g / L. The reaction temperature was controlled at 90℃, and the pH was adjusted to 11 with KOH before lithium extraction. After 9 hours of lithium extraction, the brine was replaced with a new batch, and this process was repeated 5 times to obtain lithium-intercalated LiNi. 0.96 Co 0.02 Mn 0.02 After the reaction is complete, the lithium intercalation content of the material is tested by ICP. Then, the material is annealed at 650℃ for 2 hours at a heating rate of 5℃ / min to obtain the cathode material.

[0055] The obtained LiNi 0.96 Co 0.02 Mn 0.02 O2 was used for charge and discharge performance testing. After standing for 10 hours, it was charged at a constant current of 0.1C to 4.3V under a voltage of 2.7-4.3V, and then charged at a constant voltage until the current was less than 0.05C. The charging specific capacity was recorded. Then it was discharged at a constant current of 0.1C to 2.7V, and the discharge specific capacity was recorded.

[0056] Table 1. ICP test results of cathode materials obtained after lithium extraction from salt lake brine in Examples 1-3

[0057]

[0058] Table 1 shows the ICP test results of the cathode materials obtained after lithium extraction from salt lake brine in Examples 1-3, indicating that the Li extraction amount is relatively high.

[0059] Figure 2 The images show the XRD patterns of the cathode materials obtained after lithium extraction from salt lake brine in Examples 1-3, demonstrating that the method of the present invention can successfully synthesize high-nickel ternary cathode materials.

[0060] Figure 3 This is the first charge-discharge curve of the cathode material obtained after lithium extraction from salt lake brine in Example 1; Figure 4 This is the first charge-discharge curve of the cathode material obtained after lithium extraction from salt lake brine in Example 2; Figure 5 The first charge-discharge curve of the cathode material obtained after lithium extraction from salt lake brine in Example 3 is shown, illustrating that the cathode material synthesized by the method of the present invention has excellent electrochemical performance.

[0061] Figure 6 SEM images and particle size measurements of the cathode material obtained after lithium extraction from salt lake brine in Example 1;

[0062] Figure 7 SEM images and particle size measurement results of the cathode material obtained after lithium extraction from salt lake brine in Example 2;

[0063] Figure 8 The image shows the SEM image and particle size measurement results of the cathode material obtained after lithium extraction from salt lake brine in Example 3.

[0064] Figure 6 , 7 8 indicates that the cathode material obtained after lithium extraction from salt lake brine consists of spherical particles with a particle size of 1-50 μm.

Claims

1. A method for directly preparing high-nickel cathode materials for lithium batteries using salt lake brine, characterized in that, Includes the following steps: (1) At a certain temperature, the transition metal precursor is oxidized to obtain hydroxyl transition metal oxide; after the reaction is complete, the product is washed and dried to obtain hydroxyl transition metal oxide. (2) The hydroxyl transition metal oxide obtained in step (1) is granulated and used as a lithium extraction medium, and then assembled into an ion exchange device with heating equipment. (3) Add brine from the salt lake to the ion exchange apparatus and heat the obtained hydroxyl transition metal oxides, then let it stand for Li... + / H + Lithium is extracted through an exchange reaction, thus obtaining a high-nickel cathode material for lithium batteries.

2. The method for directly preparing high-nickel cathode materials for lithium batteries using salt lake brine according to claim 1, characterized in that, In step (1), the transition metal precursor is oxidized to obtain hydroxyl transition metal oxide by liquid-phase chemical oxidation, gas-phase oxidation or electrochemical oxidation at a certain temperature.

3. The method for directly preparing high-nickel cathode materials for lithium batteries using salt lake brine according to claim 1 or 2, characterized in that, In step (1), the reaction temperature is 10~100℃ and the reaction time is 0.25-24h.

4. The method for directly preparing high-nickel cathode materials for lithium batteries using salt lake brine according to claim 2, characterized in that, In step (1), if liquid-phase chemical oxidation is used, an alkaline reagent is required to adjust the pH to >9 and the concentration of the alkaline reagent in the reaction mixture is controlled at 1-10 mol / L. The amount of oxidant used is 1-5 times the theoretically required mass of oxidant; and / or, the alkaline reagent used is at least one of LiOH, NaOH, KOH, and ammonia water; and / or, the oxidant used is at least one of O3, NaClO, Na2S2O8, KMnO4, K2S2O8, H2O2, and (NH4)2S2O8.

5. The method for directly preparing high-nickel cathode materials for lithium batteries using salt lake brine according to claim 2, characterized in that, In step (1), if gas phase oxidation is used, the oxidant used includes one or more of Cl2, F2, and O3.

6. The method for directly preparing high-nickel cathode materials for lithium batteries using salt lake brine according to claim 2, characterized in that, In step (1), if electrochemical oxidation is used, the electrolyte used includes at least one of LiOH, NaOH, KOH, ammonia, AMCl, AM2SO4, and AMNO3, where AM = at least one of Li, Na, K, Rb, and Cs, the electrolysis current is between 0.01 and 10 A, and the pH of the electrolyte is >9.

7. The method for directly preparing high-nickel cathode materials for lithium batteries using salt lake brine according to claim 1 or 2, characterized in that, In step (1), the transition metal precursor is at least one of TMSO4, TM(NO3)2, TMCl2, TM(OH)2, TMCO3, and (CH3COO)2TM; TM = at least one of Ni, Co, and Mn, wherein the mole fraction of Ni is ≥0.8; TM is Ni x Co y Mn 1-x-y , 0.8≤x≤1, 0≤y≤0.

2.

8. The method for directly preparing high-nickel cathode materials for lithium batteries using salt lake brine according to claim 1 or 2, characterized in that, In step (2), the qualified lithium extraction medium has a particle size of 1-50 μm; and / or, the shape is spherical particles.

9. The method for directly preparing high-nickel cathode materials for lithium batteries using salt lake brine according to claim 1 or 2, characterized in that, In step (3), the brine used has a Li+ concentration of 0.01 g / L to 2 g / L, and a Li... + / Mg 2+ In 0.001-2000, Na + The concentration ranges from 0.3 g / L to 100 g / L.

10. The method for directly preparing high-nickel cathode materials for lithium batteries using salt lake brine according to claim 1 or 2, characterized in that, In step (3), the exchange host of the ion exchange device is a hydroxyl transition metal oxide, and the form of the exchange host is at least one of the following: chromatography column, fixed bed ion exchanger, moving bed ion exchanger, fluidized bed ion exchanger, and hydrothermal reactor; in step (3), the heating temperature of the hydroxyl transition metal oxide is 20-350℃, and the exchange time is 0.1-480h; and / or, in step (3), the exchanged brine is released and new brine is added. After repeating the above process multiple times, the lithium-intercalated stationary phase particles are taken out and the lithium intercalation amount is tested. Particles with the required lithium intercalation amount are subjected to short-time high-temperature annealing to obtain the high-nickel cathode material for lithium batteries; and / or, in step (3), the number of repeated exchanges is more than 1; and / or, in step (3), the short-time high-temperature annealing temperature is 350-1050℃, and the annealing time is 0.5-2h.

Images