Method for producing precursor for lithium secondary battery
By using a colloidal coagulant to control the zeta potential during the manufacturing process of lithium secondary battery precursors, a uniformly grown precursor is formed, which solves the problem of difficult orientation in traditional methods, improves the output and life characteristics of the battery, and reduces production costs.
Patent Information
- Application Number
- CN202480012192.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Priority Date
- 2023-02-22
- Filing Date
- 2024-02-21
- Publication Date
- 2025-09-19
AI Technical Summary
Existing lithium secondary battery positive electrode active materials are expensive due to their high cobalt content, and traditional manufacturing methods make it difficult to achieve complete orientation from the interior to the surface of the particles, resulting in poor economic efficiency and difficulties in quality management.
A colloidal coagulant is used to coprecipitate a metal hydroxide precursor in a reaction solution. The particle aggregation is regulated by controlling the ζ potential to form a uniformly grown precursor, so that the lithium migration path from the center of the particle to the outside is radial, thereby manufacturing an oriented positive electrode active material.
A highly oriented positive electrode active material is achieved, which improves the output and life characteristics of lithium secondary batteries, reduces production costs and improves battery performance.
Smart Images
Figure CN120677129A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to a method for manufacturing a precursor for a lithium secondary battery. Background Art
[0002] With the technological development and increasing demand for electric vehicles, the demand for secondary batteries as energy sources has increased dramatically. Among these secondary batteries, lithium secondary batteries with high energy density, high voltage, long cycle life and low self-discharge rate have been commercialized and widely used.
[0003] Lithium nickel cobalt manganese composite oxide is used as a positive electrode active material for lithium secondary batteries, in which cobalt has a high operating voltage and affects rate characteristics.
[0004] However, cathode active materials with high cobalt content are expensive, so their large-scale use as power sources in fields such as electric vehicles is limited. In addition, due to the recent sharp rise in cobalt prices, the cobalt content is also showing a trend of decreasing.
[0005] Therefore, a solution that can compensate for the rate characteristics and lifespan is needed. As one of these methods, an oriented positive electrode active material has been proposed as an alternative.
[0006] Traditionally, in order to manufacture positive electrode active materials with an oriented structure, concentration gradient precursors are mainly used. However, the positive electrode active materials manufactured in this way cannot have complete orientation from the interior of the particles to the surface.
[0007] Furthermore, to achieve this, a complex process is required, resulting in poor economic efficiency and difficulty in quality control. Summary of the Invention
[0008] Technical problems to be solved
[0009] The present invention can provide a uniform growth type precursor using a colloidal coagulant, which can produce an oriented positive electrode active material with high orientation while ensuring economic efficiency.
[0010] Technical Solution
[0011] In one embodiment of the present invention, a method for manufacturing a precursor for a lithium secondary battery is provided, which comprises: a step of preparing a metal raw material; and a step of co-precipitating a metal hydroxide precursor by forming a reaction solution containing the metal raw material, wherein the reaction solution contains additional additives, and the additives include a colloidal coagulant.
[0012] According to the precursor obtained by the manufacturing method, the lithium migration path of the precursor is formed radially from the center of the particle, so that the precursor can have orientation.
[0013] In the step of preparing the metal raw material, the reaction can be carried out using a single metal raw material without separately preparing a core metal raw material and a shell metal raw material.
[0014] After the step of co-precipitating the metal hydroxide precursor by forming a reaction solution containing the metal raw material, the method may further include a step of separating the obtained precursor and waste liquid, and replacing the additive with the separated waste liquid.
[0015] After the step of co-precipitating the metal hydroxide precursor by forming a reaction solution containing the metal raw material, the method may include separating the obtained precursor and waste liquid, and adding the separated waste liquid and the additional additive to the co-precipitation reaction.
[0016] The waste liquid may contain Na2SO4.
[0017] The colloidal coagulant may include a monovalent to trivalent inorganic salt.
[0018] The colloidal coagulant may comprise sodium nitrate, potassium nitrate, ammonium nitrate, sodium sulfate, sodium pyrosulfate, potassium pyrosulfate, ammonium pyrosulfate, potassium sulfate, ammonium sulfate, sodium phosphate, potassium phosphate, ammonium phosphate, sodium pyrophosphate, potassium pyrophosphate, ammonium pyrophosphate, or a combination thereof.
[0019] The colloidal coagulant reduces the surface charge of the generated cores during the coprecipitation reaction, thereby causing the particles to aggregate.
[0020] The manufactured precursor may be a layered precursor containing nickel, manganese and cobalt.
[0021] Beneficial effects
[0022] The present invention relates to a precursor for a lithium secondary battery having an oriented structure and a positive electrode active material made using the precursor. More specifically, the present invention relates to a method for making an oriented precursor for a lithium secondary battery, wherein the precursor has an oriented structure and thus has high lifespan and high capacity characteristics.
[0023] The lithium secondary battery precursor according to the present invention is a particle having an oriented structure from the inside to the outside of the particle, thereby reducing the migration resistance of lithium ions and making it possible to manufacture a secondary battery having high output and long life characteristics. BRIEF DESCRIPTION OF THE DRAWINGS
[0024] Figure 1 It is a schematic diagram for explaining the principle of controlling the degree of aggregation by controlling the zeta potential in the Examples and Comparative Examples of the present application.
[0025] Figure 2Schematic diagram of a reactor structure for manufacturing a traditional core-shell structure precursor and a reactor structure according to an embodiment of the present application.
[0026] Figure 3 are SEM images of the positive electrode active material precursors manufactured according to Comparative Example, Examples 1 and 2.
[0027] Figures 4 to 7 These are the electrochemical characteristics evaluation results of the positive electrode active materials prepared according to Comparative Example, Examples 1 and 2. DETAILED DESCRIPTION
[0028] Hereinafter, embodiments of the present invention will be described in detail. However, the following embodiments are given as examples only, and the present invention is not limited to the following embodiments, but is defined only by the scope of the claims.
[0029] Generally, the synthesis of precursors is carried out in the high alkalinity region. Due to the property of transition metals to easily form coordination bonds, the additives that can be used are very limited and unknown.
[0030] In this invention, an additive that can regulate particle aggregation by controlling the zeta potential has been developed and applied to the precursor production method. This allows the production of oriented precursors and active materials using methods that have not been attempted before.
[0031] Generally, in aqueous solution, the surface of the precursor has a negative charge due to OH-, which is called the zeta potential.
[0032] The compressed Stern layer of the precursor moves with the precursor, while the diffused layer moves with the aqueous solution. In the dispersion of aqueous solutions, the zeta potential plays a decisive role.
[0033] In a specific example, a larger surface charge increases the repulsive force between particles, causing them to disperse. On the other hand, a smaller surface charge weakens the repulsive force between particles, causing them to agglomerate.
[0034] Figure 1 It is a schematic diagram for explaining the principle of controlling the degree of aggregation by controlling the zeta potential in the Examples and Comparative Examples of the present application.
[0035] That is, the present invention can obtain a uniform growth type precursor in which crystal planes uniformly grow from the inside of secondary particles formed of primary particle aggregates to the outside of the particles, and this is attributed to the effect of the additive used in the coprecipitation step.
[0036] In one embodiment of the present invention, a method for manufacturing a precursor for a lithium secondary battery is provided, which comprises: a step of preparing a metal raw material; and a step of co-precipitating a metal hydroxide precursor by forming a reaction solution containing the metal raw material, wherein the reaction solution contains additional additives, and the additives include a colloidal coagulant.
[0037] More specifically, one embodiment of the present invention can provide a method for manufacturing a precursor for a lithium secondary battery, which includes: a step of preparing a reaction mother liquor; a step of preparing a metal raw material; and a step of co-precipitating a metal hydroxide precursor by adding the metal raw material to the reaction mother liquor to form a reaction solution, wherein the reaction solution contains additional additives, and the additives include a colloidal coagulant.
[0038] At this time, the additive may be added to the reaction mother solution during the step of preparing the reaction mother solution.
[0039] As described above, in the method for producing a precursor according to one embodiment of the present application, an additive including a colloidal coagulant for reducing the zeta potential on the particle surface may be used in the coprecipitation reaction. Specifically, the additive may be an ion-binding inorganic salt.
[0040] Therefore, in the early stage of the co-precipitation reaction, uniform seeds can be formed through nuclear condensation, and a uniform growth type precursor can be produced based on the formed seeds.
[0041] The precursor obtained by the manufacturing method has a lithium migration path that is radially formed from the center of the particle, thus having orientation. This can be explained by the lithium migration path (i.e., the c-axis) being oriented from the center to the outer edge. Therefore, by reducing the lithium migration resistance, the output and life characteristics of the battery can be improved.
[0042] Furthermore, the precursor obtained according to the manufacturing method may be secondary particles formed by agglomeration of a plurality of primary particles. The primary particles may have a plate-like, needle-like, or amorphous particle shape, but are not limited thereto.
[0043] In the step of preparing the metal raw material, the reaction can be carried out using a single metal raw material without separately preparing a core metal raw material and a shell metal raw material.
[0044] This is different from traditional technology and can make the precursor in bulk form also have orientation.
[0045] Figure 2 Schematic diagram of a reactor structure for manufacturing a traditional core-shell structure precursor and a reactor structure according to an embodiment of the present application.
[0046] Conventionally, achieving orientation requires varying the metal composition of the core and shell to produce precursor particles. However, the present method for producing a precursor using additives achieves orientation without forming a metal concentration gradient, enabling the precursor to be produced in bulk form, thereby ensuring price competitiveness.
[0047] After the step of co-precipitating the metal hydroxide precursor by forming a reaction solution containing the metal raw material, the method may further include a step of separating the obtained precursor and waste liquid, and replacing the additive with the separated waste liquid.
[0048] Alternatively, after the step of co-precipitating the metal hydroxide precursor by forming a reaction solution containing the metal raw material, the step of separating the obtained precursor and waste liquid may be included, and the separated waste liquid is added to the co-precipitation reaction together with the additional additive.
[0049] The waste liquid may contain Na2SO4. The colloidal coagulant may contain a monovalent to trivalent inorganic salt.
[0050] More specifically, about 10% by weight of sodium sulfate may also be present in the wastewater after the reaction as a by-product.
[0051] Even if this wastewater is recycled, similar effects to those obtained by applying inorganic salt additives can be achieved, thus offering advantages in terms of price competitiveness.
[0052] More specifically, the colloidal coagulant can be an inorganic salt, for example, it can include sodium nitrate, potassium nitrate, ammonium nitrate, sodium sulfate, sodium pyrosulfate, potassium pyrosulfate, ammonium pyrosulfate, potassium sulfate, ammonium sulfate, sodium phosphate, potassium phosphate, ammonium phosphate, sodium pyrophosphate, potassium pyrophosphate, ammonium pyrophosphate or a combination thereof.
[0053] On the other hand, as described above, the colloidal coagulant may be added to the reaction mother solution in the step of preparing the reaction mother solution before the coprecipitation reaction.
[0054] At this time, the reaction mother liquid may include water, distilled water, deionized water or a combination thereof, but is not necessarily limited thereto.
[0055] Furthermore, the colloidal coagulant can be added in an amount of 3% to 15% by weight, more specifically 4% to 12% by weight, based on the weight of the reaction mother liquor. When the amount of the colloidal coagulant added falls within this range, the aforementioned improvement in precursor orientation and the resulting improvement in battery performance can be more effectively achieved.
[0056] Hereinafter, preferred embodiments of the present invention will be described. However, the following embodiment is only a preferred embodiment of the present invention, and the present invention is not limited to the following embodiment.
[0057] Examples and Comparative Examples
[0058] Example 1: Using 5% sodium sulfate additive
[0059] (Preparation of Reaction Mother Liquor) A 100 L batch reactor was charged with 15% water, and 5 parts by weight of sodium sulfate was added to 100 parts by weight of water. The mixture was stirred at 400 rpm, the internal temperature was set at 30-50°C, and nitrogen was introduced into the reactor to create an inert atmosphere.
[0060] (Preparation of Raw Materials) Next, a 2.5 M metal sulfate aqueous solution containing nickel sulfate, cobalt sulfate, and manganese sulfate mixed in a molar ratio of 0.88:0.05:0.07, 25% sodium hydroxide, and 28% ammonia water was prepared.
[0061] (Reaction Solution Formation and Coprecipitation Reaction) The flow rate of the metal sulfate aqueous solution was 3 L / h, and the flow rate of the ammonia solution was adjusted to a ratio of 0.04 of the metal sulfate aqueous solution flow rate. The amount of sodium hydroxide (NaOH) solution added was adjusted to maintain the hydrogen ion concentration (pH) in the reactor at approximately 10.5 to 11.5, thereby forming a reaction solution for the coprecipitation reaction. The stirring speed was 400 rpm, and the reactants were added so that the average residence time of the entire solution reached 20 hours. The reaction temperature was maintained at 30°C to 50°C, and nitrogen was introduced to maintain an inert atmosphere.
[0062] (Water washing and drying) After the reaction is completed, the resulting solution is washed with water and solid-liquid separation is performed using a filter press, and residual moisture is removed using high-pressure clean air (Fresh Air). The active material after solid-liquid separation is dried in a fluidized bed dryer at 100 to 200°C.
[0063] (Calcination) The hydroxide particles obtained above were mixed with lithium hydroxide in an equivalent ratio of 1.05 to the hydroxide, and then heated at a heating rate of 2.5°C / min in an oxygen atmosphere, and then calcined at 780°C for 9 hours to obtain a lithium composite metal oxide with a uniform oriented structure.
[0064] Example 2: Using 10% sodium sulfate additive
[0065] A positive electrode active material precursor and a positive electrode active material were manufactured in the same manner as in Example 1, except that 10 parts by weight of sodium sulfate was added to 100 parts by weight of water in the reaction mother solution preparation step.
[0066] Comparative Example: No sodium sulfate additive
[0067] A cathode active material precursor and a cathode active material were manufactured in the same manner as in Example 1 except that sodium sulfate was not added in the reaction mother solution preparation step.
[0068] Experimental Example 1: Evaluation of SEM images
[0069] Figure 3 is a cross-sectional SEM photograph of the precursor produced according to the above method.
[0070] The SEM analysis results show that the particles of the comparative example without the additive are not aggregated but are in a dispersed state at the initial stage of the reaction.
[0071] In the later stage of the reaction, the growing particles merged, resulting in a deterioration of sphericity. Cross-sectional analysis results confirmed that no orientation was formed.
[0072] In the example using the additive, agglomerated unit seeds are formed in the early stage of the reaction, so that the sphericity of the final product is greatly improved. The particle cross-section analysis results can confirm the formation of good orientation.
[0073] Experimental Example 2: Evaluation of Battery Electrochemical Characteristics
[0074] (Manufacturing of a Lithium Secondary Battery) The positive electrode active materials prepared according to Examples 1 and 2 and the Comparative Example were mixed with SuperC as a conductive material and PVDF as a binder in a weight ratio of 96.5:1.5:2 to prepare a positive electrode active material slurry. The slurry was evenly coated on a 20 μm thick aluminum foil and vacuum dried at 130°C to produce a positive electrode.
[0075] A coin cell was fabricated using the prepared positive electrode as the working electrode, lithium foil as the counter electrode, and a polypropylene film as the separator, using an electrolyte consisting of 1.0 M LiPF6 lithium salt dissolved in an EC / EMC / DMC solvent.
[0076] The charge and discharge efficiency, initial discharge capacity, and initial discharge capacity at 0.1C, 0.33C, 0.5C, 1C, and 2C of the lithium secondary battery manufactured according to the method were evaluated and are shown in FIG. Figures 4 to 7 middle.
[0077] Reference Figures 4 to 7 For Examples 1 and 2, which were manufactured by adding an appropriate amount of a colloidal coagulant, it was confirmed that the charge-discharge efficiency, initial discharge capacity, and high-rate characteristics during cycling were significantly improved compared to the comparative example without the addition of a colloidal coagulant. This can be explained by the improved cohesion and orientation of the active material, which in turn improved battery performance.
[0078] The present invention can be implemented in various ways and is not limited to the above-described embodiments. A person skilled in the art will appreciate that the present invention can be implemented in other specific ways without changing the technical concept or essential features of the present invention. Therefore, it should be understood that the above-described embodiments are illustrative in all respects and are not restrictive.
Claims
1. A method for producing a precursor for a lithium secondary battery, the method comprising: The step of preparing the metal feedstock substance; as well as a step of co-precipitating a metal hydroxide precursor by forming a reaction solution containing the metal raw material, The reaction solution contains additional additives, The additive comprises a colloid coagulant.
2. The method for producing a lithium secondary battery precursor according to claim 1, wherein: According to the precursor obtained by the manufacturing method, the lithium migration path of the precursor is formed radially from the center of the particle, so that the precursor has orientation.
3. The method for producing a precursor for a lithium secondary battery according to claim 1, wherein: In the step of preparing the metal raw material, The reaction is carried out using a single metal raw material without separately preparing a core metal raw material and a shell metal raw material.
4. The method for producing a precursor for a lithium secondary battery according to claim 1, wherein: After the step of co-precipitating a metal hydroxide precursor by forming a reaction solution containing the metal raw material, comprising the steps of separating the obtained precursor and waste liquid, The additive is replaced by the separated waste liquid.
5. The method for producing a precursor for a lithium secondary battery according to claim 1, wherein: After the step of co-precipitating a metal hydroxide precursor by forming a reaction solution containing the metal raw material, comprising the steps of separating the obtained precursor and waste liquid, The separated waste liquid is added to the co-precipitation reaction together with the additional additives.
6. The method for producing a precursor for a lithium secondary battery according to claim 4 or 5, wherein: The waste liquid contains Na2SO4.
7. The method for producing a precursor for a lithium secondary battery according to claim 1, wherein: The colloidal coagulant comprises a monovalent to trivalent inorganic salt.
8. The method for producing a precursor for a lithium secondary battery according to claim 7, wherein: The colloidal coagulant comprises sodium nitrate, potassium nitrate, ammonium nitrate, sodium sulfate, sodium pyrosulfate, potassium pyrosulfate, ammonium pyrosulfate, potassium sulfate, ammonium sulfate, sodium phosphate, potassium phosphate, ammonium phosphate, sodium pyrophosphate, potassium pyrophosphate, ammonium pyrophosphate or a combination thereof.
9. The method for producing a precursor for a lithium secondary battery according to claim 1, wherein: The colloidal coagulant reduces the surface charge of the generated cores during the coprecipitation reaction, thereby causing the particles to aggregate.
10. The method for producing a precursor for a lithium secondary battery according to claim 1, wherein: The prepared precursor is a layered precursor containing nickel, manganese and cobalt.