Method for preparing ternary precursor based on extraction system and application thereof

Abstract

The invention discloses a method for preparing a ternary precursor based on an extraction system and application thereof. The preparation method comprises the following steps: mixing a ternary mixed salt solution with an extraction phase, dropwise adding a precipitant solution, reacting, and separating to obtain an organic phase and a water phase loaded with a ternary precursor; carrying out reverse extraction on the organic phase loaded with the ternary precursor to obtain the ternary precursor; wherein the extraction phase comprises a composite extraction agent and a solvent, and the extraction agent comprises organic phosphonic acid and crown ether. The method provided by the invention is a ternary co-extraction one-step method, enrichment and co-precipitation of metal ions can be synchronously completed in the extraction process, the product performance is improved, the ternary precursor is uniform in component, regular in particle morphology, good in consistency and controllable in particle size, and the method remarkably simplifies the technological process and complexity and is easy to operate.

Description

Technical Field

[0001] This invention relates to the field of battery material preparation, and specifically to a method for preparing ternary precursors based on an extraction system and its application. Background Technology

[0002] Ternary precursors (such as NixCo) y Mn z (OH)2, x+y+z=1) is a core raw material for lithium-ion battery cathode materials, and its performance directly affects the battery's energy density, cycle life, and safety. Currently, the mainstream preparation method is co-precipitation. Taking nickel-cobalt-manganese ternary precursors as an example, a mixed salt solution is generally obtained by dissolving nickel, cobalt, and manganese sulfates or chlorides. Then, the pH is adjusted to allow nickel, cobalt, and manganese metal ions to simultaneously precipitate hydroxides. After washing and drying, the precursor is obtained. However, the traditional co-precipitation method has the following drawbacks: First, it is cumbersome to operate: a metal salt solution must be prepared first, and then the pH must be adjusted to the precipitation range (e.g., pH 10-12) using ammonia / sodium hydroxide. Strict control of stirring speed, temperature, and feed rate is required during the process, resulting in high process complexity. Second, the metal distribution is uneven: due to the differences in the solubility product (Ksp) of Ni²⁺, Co²⁺, and Mn²⁺ hydroxides (e.g., Ksp ≈ 5.48 × 10⁻⁶ for Ni(OH)2), the process is complex. - ¹ 6 The Ksp of Co(OH)2 is approximately 5.92 × 10⁻⁶. - ¹ 5 The Ksp of Mn(OH)2 is approximately 1.9 × 10⁻⁶. - ¹³), during the precipitation process, the phenomenon of "edge preferential deposition" is prone to occur, resulting in irregular particle morphology and component segregation; third, the risk of impurity introduction: in order to prevent local supersaturation, it is often necessary to add complexing agents (such as ammonia) to stabilize the metal ion concentration, but excessive ammonia will remain in the precursor, affecting the lithiation reaction in the subsequent sintering process; fourth, high water consumption and high energy consumption: after precipitation, multiple washing is required to remove impurity ions (such as SO4²⁻, Cl⁻), which consumes a lot of water and has high drying energy consumption.

[0003] To address the aforementioned issues, existing patents (such as CN112300735A "A method for co-precipitation preparation of a ternary precursor" and CN113214307B "A method for preparing a high-nickel ternary precursor") have improved particle morphology by optimizing pH curves and adding surfactants (such as polyethylene glycol), but they still have not solved the core problems of "cumbersome operation" and "uneven metal distribution".

[0004] Therefore, it is necessary to provide a method for preparing ternary precursors that is simple and easy to operate, has uniform metal distribution, reduces the risk of impurity introduction, and avoids the problem of high water consumption caused by multiple washing to remove impurities. This is a technical problem that urgently needs to be solved. Summary of the Invention

[0005] To address the aforementioned technical problems in the existing technology, the purpose of this invention is to propose a method for preparing ternary precursors based on an extraction system and its application.

[0006] In a first aspect, the present invention provides a method for preparing a ternary precursor based on an extraction system, the preparation method comprising the following steps:

[0007] After mixing the ternary mixed salt solution with the extraction phase, a precipitant solution was added dropwise. After the reaction, the mixture was separated to obtain an organic phase and an aqueous phase loaded with the ternary precursor.

[0008] The organic phase of the supported ternary precursor was back-extracted to obtain the ternary precursor.

[0009] The extraction phase comprises a composite extractant and a solvent, wherein the extractant comprises organophosphonic acid and crown ether.

[0010] The method provided by this invention is a one-step ternary co-extraction method, which can simultaneously enrich and co-precipitate metal ions during the extraction process, improving product performance. The ternary precursor has uniform composition, regular and consistent particle morphology, and controllable particle size. Moreover, this method significantly simplifies the process flow and reduces complexity, making it easy to operate. In this method, the extractant in the extraction phase is a composite extractant, wherein organophosphonic acid can form stable chelates with ternary metal ions (such as [Ni(PW)]). 12 )]³ - 、[Co(PW 12 )]³ - 、[Mn(PW 12 )]³ - Crown ethers achieve efficient complexation of metal ions. Through the "cavitation ether effect", crown ethers selectively recognize counterions (such as K⁺, Na⁺, etc.), destroy the structure of hydrated ions, and promote the formation of hydrophobic extraction phase.

[0011] In the method of this invention, no complexing agents such as ammonia are added, thus preventing ammonia residue in the precursor and reducing the risk of impurity introduction. Furthermore, since the method of this invention forms an organic phase loaded with a ternary precursor by complexing and co-precipitating nickel, cobalt, and manganese, followed by back-extraction to obtain the ternary precursor, this process achieves the separation of nickel, cobalt, and manganese from other impurity ions (such as SO4²⁻ and Cl⁻), thereby avoiding the problem of high water consumption caused by repeated washing to remove impurities.

[0012] The following are preferred technical solutions of the present invention, but are not intended to limit the technical solutions provided by the present invention. The technical objectives and beneficial effects of the present invention can be better achieved and realized through the following preferred technical solutions.

[0013] Preferably, the organophosphonic acid includes PW12 (chemical formula H3PW). 12 O 40 PW12 has good water solubility and can be reacted or treated in the aqueous phase, reducing the amount of organic solvents used.

[0014] Preferably, the crown ether comprises 18-crown-6.

[0015] Preferably, in the composite extractant, the mass ratio of the organophosphonic acid to the crown ether is (2~4):1, for example, it can be 2:1, 2.2:1, 2.4:1, 2.6:1, 2.8:1, 3:1, 3.3:1, 3.5:1, 3.7:1, or 4:1, etc. If there is too much organophosphonic acid and too little crown ether in the composite extractant, the selectivity will decrease, the synergistic effect will weaken, phase separation will be difficult, and the cost-effectiveness will be low. If there is too little organophosphonic acid and too much crown ether in the composite extractant, the synergistic pathway will be blocked, the extraction capacity will decrease, the cost will increase sharply, and crown ether residue may also reduce the extraction efficiency.

[0016] Preferably, the solvent includes kerosene and / or sulfonated kerosene.

[0017] Preferably, the volume concentration of the extractant in the extraction phase is 10% to 20%, for example, it can be 10%, 12%, 13%, 14%, 15%, 16%, 18%, or 20%. If the volume concentration is too low, the recovery rate will be low; if the volume concentration is too high, although more absolute mass of the target analyte may be extracted, the concentration of the target analyte in the extraction phase will be diluted.

[0018] Preferably, the precipitant in the precipitant solution includes carbonates and / or hydroxides.

[0019] Preferably, the concentration of the precipitant solution is 0.5 mol / L to 1 mol / L, for example, it can be 0.5 mol / L, 0.6 mol / L, 0.7 mol / L, 0.8 mol / L, 0.9 mol / L or 1 mol / L, etc.

[0020] Preferably, the volume ratio of the ternary mixed salt solution to the extractant phase is 1:(1~3), for example, it can be 1:1, 1:1.2, 1:1.4, 1:1.5, 1:1.6, 1:1.8, 1:2, 1:2.3, 1:2.5, 1:2.6, 1:2.8, or 1:3, etc. If the amount of extractant phase is too small, the extraction effect will be poor; if the amount of extractant phase is too large, it will lead to waste of extractant and increased costs.

[0021] Preferably, the precipitant solution is added dropwise to control the pH value of the reaction system between 9.0 and 11.5. Exemplarily, the pH value can be 9.0, 9.2, 9.5, 9.7, 9.8, 10, 10.2, 10.5, 10.6, 10.8, 10.9, 11, 11.2, 11.3, 11.4, or 11.5, etc.

[0022] Preferably, the mixing process is carried out at 25°C to 50°C. For example, the temperature can be 25°C, 26°C, 28°C, 30°C, 32°C, 35°C, 38°C, 40°C, 42°C, 45°C, 46°C, 48°C, or 50°C.

[0023] Preferably, the mixture is stirred at a speed of 200 rpm to 500 rpm (e.g., 200 rpm, 220 rpm, 240 rpm, 260 rpm, 280 rpm, 300 rpm, 325 rpm, 350 rpm, 360 rpm, 380 rpm, 400 rpm, 425 rpm, 450 rpm, 465 rpm, 480 rpm, or 500 rpm, etc.) and the dripping process is carried out under stirring conditions. A suitable stirring speed is beneficial for obtaining well-shaped spherical particles.

[0024] Preferably, the reaction time is 10 min to 30 min, for example, it can be 10 min, 12 min, 15 min, 17 min, 20 min, 22 min, 25 min, 27 min or 30 min.

[0025] Preferably, the concentration of the ternary mixed salt solution is 0.4 mol / L to 4 mol / L, for example, it can be 0.4 mol / L, 0.8 mol / L, 1 mol / L, 1.5 mol / L, 1.8 mol / L, 2 mol / L, 2.2 mol / L, 2.3 mol / L, 2.5 mol / L, 2.7 mol / L, 3 mol / L, 3.3 mol / L, 3.5 mol / L, 3.8 mol / L, or 4 mol / L, etc.

[0026] Preferably, the ternary mixed salt solution is a mixed salt solution of nickel, cobalt, and manganese, wherein the molar ratio of nickel, cobalt, and manganese is 8:1:1;

[0027] Preferably, the ternary mixed salt solution is obtained by adjusting the concentration of metal ions in the leachate to a preset value. The method of this invention is applicable to ternary mixed salt solutions obtained through recycling. Although the leachate may contain impurity ions other than ternary metal ions (e.g., nickel, cobalt, manganese), the application of the one-step ternary co-extraction method effectively prevents these impurity ions from entering the ternary precursor.

[0028] Preferably, the reagent used for back-extraction is water.

[0029] Preferably, the back-extraction is followed by secondary separation, washing, and drying to obtain a powder of the ternary precursor.

[0030] In one embodiment, water is used for washing until the conductivity is <100 μS / cm.

[0031] In one embodiment, the drying method is vacuum drying, and the vacuum drying temperature is 80℃~100℃, for example, it can be 80℃, 85℃, 90℃, 95℃ or 100℃.

[0032] In a second aspect, the present invention provides a ternary precursor, which is prepared by the method described in the first aspect.

[0033] Thirdly, the present invention provides a ternary cathode material, which is prepared using the ternary precursor described in the second aspect.

[0034] Fourthly, the present invention provides a battery comprising the ternary cathode material described in the third aspect.

[0035] The numerical range described in this invention includes not only the point values ​​listed above, but also any point values ​​within the numerical ranges not listed above. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific point values ​​included in the range.

[0036] Compared with existing technologies, the present invention has the following beneficial effects:

[0037] (1) The method provided by this invention is a one-step ternary co-extraction method, which can simultaneously complete the enrichment and co-precipitation of metal ions during the extraction process, thereby improving product performance. The ternary precursor has uniform composition, regular and consistent particle morphology, and controllable particle size. Moreover, this method significantly simplifies the process flow and complexity, and is easy to operate. In this method, the extractant in the extraction phase is a composite extractant, wherein the organophosphonic acid can form a stable chelate with the ternary metal ions (such as [Ni(PW)]). 12 )]³ - 、[Co(PW 12 )]³ - 、[Mn(PW 12 )]³ - Crown ethers achieve efficient complexation of metal ions. Through the "cavitation ether effect", crown ethers selectively recognize counterions (such as K⁺, Na⁺, etc.), destroy the structure of hydrated ions, and promote the formation of hydrophobic extraction phase.

[0038] (2) In the method of the present invention, no complexing agents such as ammonia are added, so ammonia will not remain in the precursor, reducing the risk of impurity introduction. At the same time, since the method of the present invention forms an organic phase loaded with a ternary precursor by complexing and co-precipitating nickel, cobalt, and manganese, and then back-extracting to obtain the ternary precursor, the process achieves the separation of nickel, cobalt, and manganese from other impurity ions (such as SO4²⁻, Cl⁻), thus avoiding the problem of high water consumption caused by multiple washing to remove impurities.

[0039] (3) The precursor prepared by the method of the present invention has a high tap density of 1.94 g / cm³. 3 The above is preferably 2.05 g / cm³. 3 Furthermore, the precursor prepared by the method of the present invention has a low metal molar ratio deviation from the theoretical molecular formula of the precursor, which is less than 2.9%, preferably less than 2.3%. Detailed Implementation

[0040] The technical solution of the present invention will be further illustrated below through specific embodiments.

[0041] The specific embodiments described herein are for illustrative purposes only and are not intended to limit the scope of the invention.

[0042] Example 1

[0043] This embodiment provides a method for preparing ternary precursors based on an extraction system, including the following steps:

[0044] (1) Raw material preparation: The ternary mixed leachate containing Ni, Co and Mn was prepared into a mixed salt solution A with a total metal ion concentration of 0.4 mol / L by adjusting the molar ratio of Ni:Co:Mn to 8:1:1 using NiSO4·6H2O, CoSO4·7H2O and MnSO4·H2O.

[0045] (2) Preparation of the extractant phase: PW12 (chemical formula C) 12 H5O 43 PW 12 20 g of 18-crown-6 (molecular weight 3333.9) and 6.6 g of 18-crown-6 (molecular weight 264.3) were dissolved in 100 mL of sulfonated kerosene to prepare an extractive phase with a volume concentration of 20%.

[0046] (3) Extraction-precipitation reaction: Add the mixed salt solution A and the extract phase to the separatory funnel at a volume ratio of 1:1, heat to 40℃, stir at 300 rpm, and add 1 mol / L NaOH solution (250 mL) dropwise. Control the pH value of the reaction system after adding NaOH solution to be 9.0.

[0047] (4) After reacting for 15 minutes, the system separates into layers. The upper organic phase is dark green (supported by ternary hydroxide), and the lower aqueous phase is clear.

[0048] (5) Collect the organic phase and back-extract the organic phase with deionized water. The volume ratio of organic phase to deionized water is 1:2, and a white precipitate is obtained. After filtration, wash with deionized water until the conductivity is 80 μS / cm, and dry under vacuum at 100℃ for 12 hours to obtain ternary precursor powder (nickel cobalt manganese hydroxide).

[0049] Example 2

[0050] This embodiment provides a method for preparing ternary precursors based on an extraction system, including the following steps:

[0051] (1) Raw material preparation: The ternary mixed leachate containing Ni, Co and Mn was prepared into a 500 mL mixed salt solution A with a total metal ion concentration of 1 mol / L by adjusting the molar ratio of Ni:Co:Mn = 8:1:1;

[0052] (2) Preparation of extractant phase: PW12 and 18-crown-6 were dissolved in 100 mL of sulfonated kerosene at a mass ratio of 2:1 to prepare an extractant phase with a volume concentration of 10%;

[0053] (3) Extraction-precipitation reaction: Add the mixed salt solution A and the extract phase to the separatory funnel at a volume ratio of 1:1, heat to 30°C, stir at 500 rpm, and add 0.5 mol / L NaOH solution dropwise at the same time, and control the pH value of the reaction system after adding NaOH solution to be 10.5;

[0054] (4) After reacting for 30 minutes, the system separates into layers. The upper organic phase is dark green (supported by ternary hydroxide), and the lower aqueous phase is clear.

[0055] (5) Collect the organic phase and back-extract the organic phase with deionized water. The volume ratio of organic phase to deionized water is 1:2, and a white precipitate is obtained. After filtration, wash with deionized water until the conductivity is 85 μS / cm, and dry under vacuum at 80°C for 18 hours to obtain ternary precursor powder (nickel-cobalt-manganese hydroxide).

[0056] Example 3

[0057] This embodiment provides a method for preparing ternary precursors based on an extraction system, including the following steps:

[0058] (1) Raw material preparation: The ternary mixed leachate containing Ni, Co and Mn was prepared into a 500 mL mixed salt solution A with a total metal ion concentration of 3 mol / L by adjusting the molar ratio of Ni:Co:Mn = 8:1:1;

[0059] (2) Preparation of extractant phase: PW1220 g and 18-crown-6 were dissolved in 100 mL of sulfonated kerosene at a mass ratio of 4:1 to prepare an extractant phase with a volume concentration of 15%;

[0060] (3) Extraction-precipitation reaction: Add the mixed salt solution A and the extract phase to the separatory funnel at a volume ratio of 1:1, heat to 50℃, stir at 200 rpm, and add 1 mol / L NaOH solution dropwise at the same time, and control the pH value of the reaction system after adding NaOH to be 11.5;

[0061] (4) After reacting for 25 minutes, the system separates into layers. The upper organic phase is dark green (supported by ternary hydroxide), and the lower aqueous phase is clear.

[0062] (5) Collect the organic phase and back-extract it with deionized water. The volume ratio of organic phase to deionized water is 1:2, and a white precipitate is obtained. After filtration, wash with deionized water until the conductivity is 80 μS / cm, and dry under vacuum at 90℃ for 15 hours to obtain ternary precursor powder.

[0063] Example 4

[0064] The difference between this embodiment and Embodiment 1 is that the mass ratio of PW12 to 18-crown-6 is 1:1.

[0065] Example 5

[0066] The difference between this embodiment and Embodiment 1 is that the mass ratio of PW12 to 18-crown-6 is 5:1.

[0067] Example 6

[0068] The difference between this embodiment and embodiment 1 is that in step (2), the volume concentration of the extract phase is 8%.

[0069] Example 7

[0070] The difference between this embodiment and embodiment 1 is that in step (2), the volume concentration of the extract phase is 22%.

[0071] Example 8

[0072] The difference between this embodiment and embodiment 1 is that in step (3), the volume ratio of the mixed salt solution A to the extraction phase is 2:1.

[0073] Example 9

[0074] The difference between this embodiment and embodiment 1 is that in step (3), the volume ratio of the mixed salt solution A to the extraction phase is 1:4.

[0075] Example 10

[0076] The difference between this embodiment and Embodiment 1 is that the molar ratio of Ni:Co:Mn is adjusted to 6:2:2.

[0077] Comparative Example 1

[0078] In this comparative example, a traditional co-precipitation method was used to prepare the ternary precursor. The specific method was as follows: a mixed solution with a Ni:Co:Mn molar ratio of 8:1:1 (total metal ion concentration of 0.4 mol / L) was prepared, the pH was adjusted to 11 with ammonia, the reaction was stirred for 2 hours, and the solution was filtered, washed, and dried to obtain the ternary precursor.

[0079] The ternary precursor particles obtained in this comparative example are irregularly shaped flakes with a sphericity of 0.75, a D50 of 4.2 μm, and a wide particle size distribution, indicating poor particle uniformity. The tap density is 1.8 g / cm³, and the metal molar ratio deviation is ±4%.

[0080] Comparative Example 2

[0081] The difference between this comparative example and Example 1 is that the combination of PW12 and 18-crown-6 is replaced with PW12.

[0082] Comparative Example 3

[0083] The difference between this comparative example and Example 1 is that the combination of PW12 and 18-crown-6 is replaced with 18-crown-6.

[0084] Detection:

[0085] (1) Test the tap density of the ternary precursor, the method is as follows: GB / T 5162.

[0086] (2) Test the metal molar ratio deviation of the ternary precursor. The method is as follows: use atomic absorption fluorescence spectroscopy to test the total molar amount of nickel, cobalt and manganese in the prepared precursor (denoted as a), the theoretical total molar amount of nickel, cobalt and manganese is b, and the metal molar ratio deviation = (ba) / b×100%.

[0087] The results are shown in Table 1.

[0088]

[0089] The precursor prepared by the method of this invention has a high tap density of 1.94 g / cm³. 3 The above is preferably 2.05 g / cm³. 3In addition, the precursor prepared by the method of the present invention has a low metal molar ratio deviation from the theoretical molecular formula of the precursor, which is less than 2.9%, preferably less than 2.3%. Compared with the conventional co-precipitation method (Comparative Example 1), although the metal molar ratio deviation is slightly higher, the tap density is significantly better, and the method of the present invention is simpler to prepare, showing obvious advantages.

[0090] The comparison between Example 1 and Examples 4-5 and Comparative Examples 2-3 shows that both organophosphonic acid and crown ether are indispensable, and the mass ratio of organophosphonic acid to crown ether is controlled within the range of (2~4):1, which is beneficial to improve the tap density of the precursor and reduce the metal molar ratio deviation.

[0091] The applicant declares that the detailed method of the present invention is illustrated by the above embodiments, but the present invention is not limited to the above detailed method, that is, it does not mean that the present invention must rely on the above detailed method to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions of the raw materials of the product of the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for preparing ternary precursors based on an extraction system, characterized in that, The preparation method includes the following steps: After mixing the ternary mixed salt solution with the extraction phase, a precipitant solution was added dropwise. After the reaction, the mixture was separated to obtain an organic phase and an aqueous phase loaded with the ternary precursor. The organic phase of the supported ternary precursor was back-extracted to obtain the ternary precursor. The extraction phase comprises a composite extractant and a solvent, wherein the extractant comprises organophosphonic acid and crown ether.

2. The method for preparing ternary precursors based on an extraction system according to claim 1, characterized in that, The organophosphonic acid includes PW12; Preferably, the crown ether comprises 18-crown-6; Preferably, in the composite extractant, the mass ratio of the organophosphonic acid to the crown ether is (2~4):1; Preferably, the solvent includes kerosene and / or sulfonated kerosene; Preferably, the volume concentration of the extractant in the extract phase is 10% to 20%.

3. The method for preparing ternary precursors based on an extraction system according to claim 1 or 2, characterized in that, The precipitant in the precipitant solution includes carbonates and / or hydroxides; Preferably, the concentration of the precipitant solution is 0.5 mol / L to 1 mol / L.

4. The method for preparing ternary precursors based on an extraction system according to any one of claims 1-3, characterized in that, The volume ratio of the ternary mixed salt solution to the extraction phase is 1:(1~3); Preferably, the precipitant solution is added dropwise to control the pH value of the reaction system between 9.0 and 11.5 after the addition. Preferably, the mixing process is carried out at 25°C to 50°C; Preferably, the mixture is stirred at a speed of 200 rpm to 500 rpm after mixing, and the dripping process is carried out under stirring conditions.

5. The method for preparing ternary precursors based on an extraction system according to any one of claims 1-4, characterized in that, The reaction time is 10 min to 30 min.

6. The method for preparing ternary precursors based on an extraction system according to any one of claims 1-5, characterized in that, The concentration of the ternary mixed salt solution is 0.4 mol / L to 4 mol / L; Preferably, the ternary mixed salt solution is a mixed salt solution of nickel, cobalt, and manganese, wherein the molar ratio of nickel, cobalt, and manganese is (5-8):(1-5):(1-5). Preferably, the ternary mixed salt solution is obtained by adjusting the concentration of metal ions in the leachate to a preset value to obtain the ternary mixed salt solution.

7. The method for preparing ternary precursors based on an extraction system according to any one of claims 1-6, characterized in that, The reagent used in the back-extraction is water; Preferably, the back-extraction is followed by secondary separation, washing, and drying to obtain a powder of the ternary precursor.

8. A ternary precursor, characterized in that, The ternary precursor is prepared by the method described in any one of claims 1-7.

9. A ternary cathode material, characterized in that, The ternary cathode material is prepared using the ternary precursor described in claim 8.

10. A battery, characterized in that, The battery includes the ternary cathode material as described in claim 9.

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