A positive electrode precursor and its preparation method and application

Abstract

The present invention provides a positive electrode precursor, a preparation method thereof, and an application thereof. The preparation method comprises the following steps: adding a mixed metal salt solution, a precipitant solution, and a complexing agent solution in parallel, and sequentially carrying out co-precipitation reactions in the nucleation stage, the particle growth stage, and the morphology adjustment stage to obtain the positive electrode precursor; wherein the mixed metal salt comprises nickel salt, cobalt salt, and M metal salt; in the nucleation stage, the mixed metal salt solution further comprises a dispersant, and an oxidant solution is added in parallel; in the particle growth stage, an oxidant solution is added in parallel; in the morphology adjustment stage, the mixed metal salt solution further comprises a morphology regulator and a dispersant; the flow rate of the oxidant solution in the particle growth stage is greater than the flow rate of the oxidant solution in the nucleation stage. The present invention prepares a positive electrode precursor material with controllable morphology and physicochemical indicators through staged coordination, so that the positive electrode precursor material has high sphericity, stable structure, and is not easy to crack.

Description

Technical Field

[0001] The present invention belongs to the field of battery technology and relates to a positive electrode precursor and a preparation method and application thereof, and in particular to a positive electrode precursor that can be used in both lithium batteries and sodium batteries and a preparation method and application thereof. Background Art

[0002] Conventional ternary precursor reactions need to be carried out in an N2 protected atmosphere, otherwise it will be difficult to nucleate or the particles will be abnormally loose and easily broken. For example, CN108585065A discloses a high nickel ternary positive electrode material precursor, which has the general formula Ni x Co y Mn z (OH)2, wherein x+y+z=1, 0.5≤x<1, 0<y<0.5, 0<z<0.5; its preparation method comprises: preparing sodium hydroxide and ammonia water into a reaction base liquid; preparing inorganic salts of nickel, cobalt and manganese into a stable inorganic salt mixed solution; preparing sodium hydroxide into a sodium hydroxide solution; preparing sodium hydroxide into an ammonia aqueous solution; injecting the reaction base liquid into a reactor, stirring and nitrogen protection, and heating to raise the temperature; placing the inorganic salt mixed solution, sodium hydroxide solution and ammonia aqueous solution into separate reactors; continuing nitrogen protection and stirring the reaction; standing and aging, filtering, washing, drying, grinding and screening. However, for certain products requiring a larger BET value or products with requirements for sphericity, appropriately increasing the degree of oxidation during the reaction process can effectively improve the physical and chemical indicators of the material.

[0003] During a general reaction, the degree of oxidation of the system is directly controlled simply by using a nitrogen / compressed air mixed gas combination. For example, CN114804232A discloses a hollow ternary cathode material precursor and a preparation method. The preparation method includes: 1. preparing a mixed salt solution of Ni, Co, and Mn; preparing a sodium hydroxide or potassium hydroxide solution as a precipitant; preparing an ammonia solution as a complexing agent; and preparing an additive solution; 2. introducing a mixture of air and nitrogen into a kettle, adding the mixed salt solution, complexing agent, precipitant, and additive solution into the kettle to form nuclei, overflowing to a concentration device when D501 reaches 50-60% of D50, and overflowing to a first aging tank when the solid content reaches 25-30%; entering the nucleus growth stage after 30-50 hours, closing the overflow to the first aging tank after 8-14 hours of growth, opening the overflow to the second aging tank, and opening the first aging tank to reflux into the reactor, and stopping after the reflux is completed; 3. Filter pressing, washing, and drying the slurry to obtain a hollow ternary cathode material precursor. However, for larger reactors, the required air flow rate is large, which may affect the nucleation situation. At a large air flow rate, it may even affect the flow field or cause the ammonia value of the reaction system to be uncontrollable.

[0004] Therefore, how to effectively control the morphology and physical and chemical indicators of the cathode precursor is a technical problem that needs to be solved urgently. Summary of the Invention

[0005] The present invention aims to provide a cathode precursor, its preparation method, and application. By coprecipitating the nucleation, particle growth, and morphology adjustment stages, the present invention produces a cathode precursor material with controllable morphology and physicochemical properties. This material exhibits high sphericity, a stable structure, and resistance to cracking.

[0006] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0007] In a first aspect, the present invention provides a method for preparing a positive electrode precursor, the preparation method comprising the following steps:

[0008] Adding a mixed metal salt solution, a precipitant solution, and a complexing agent solution in parallel, and sequentially performing a co-precipitation reaction of a nucleation stage, a particle growth stage, and a morphology adjustment stage to obtain the positive electrode precursor;

[0009] Wherein, the mixed metal salt includes nickel salt, cobalt salt and M metal salt; in the nucleation stage, the mixed metal salt solution also includes a dispersant, and an oxidant solution is added in parallel; in the particle growth stage, an oxidant solution is also added in parallel; in the morphology adjustment stage, the mixed metal salt solution also includes a morphology regulator and a dispersant; the flow rate of the oxidant solution in the particle growth stage is greater than the flow rate of the oxidant solution in the nucleation stage.

[0010] The preparation method of the precursor provided by the present invention can obtain crystal nuclei with an ideal particle size without causing particle agglomeration under the synergistic effect of a weakly oxidizing environment and a dispersant in the nucleation stage. If a dispersant is not added in the nucleation stage, uneven size or agglomeration is likely to occur; in the particle growth stage, in a strong oxidizing environment, the product can achieve rapid growth and improved sphericity, and no dispersant is needed in this stage; further, in the morphology adjustment stage, the oxidant is not added, but is replaced by a morphology regulator and a dispersant, thereby optimizing the surface morphology of the product and obtaining a positive electrode precursor material with a stable structure and controllable physical and chemical indicators.

[0011] During the coprecipitation reaction provided by the present invention, if the flow rate of the oxidant solution in the nucleation stage and the flow rate of the oxidant solution in the particle growth stage are kept consistent, that is, a strongly oxidizing environment is maintained consistently, it is difficult for the particles to nucleate; and if the final morphology adjustment stage is not performed, the surface will be too loose, resulting in fine powder or cracking; that is, the three stages in the present invention work synergistically to obtain a positive electrode precursor material with good sphericity, stable structure and not easy to crack, thereby improving the electrochemical performance of the positive electrode material.

[0012] Preferably, during the particle growth stage, a dispersant may be added to the mixed salt solution in addition to the oxidant.

[0013] Preferably, the concentration of metal ions in the mixed salt solution is 80-120 g / L, for example, 80 g / L, 90 g / L, 100 g / L, 110 g / L or 120 g / L.

[0014] Preferably, M in the M metal salt includes any one of Mn, Fe, Cu, Al or Mg, or a combination of at least two of them.

[0015] Preferably, the concentration of the precipitant solution is 200-400 g / L, for example, 200 g / L, 250 g / L, 300 g / L, 350 g / L or 400 g / L.

[0016] Preferably, the precipitant comprises any one of sodium hydroxide, sodium carbonate or ammonium bicarbonate, or a combination of at least two of them.

[0017] Preferably, the mass concentration of the complexing agent solution is 10-20%, for example, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19% or 20%.

[0018] Preferably, the complexing agent includes any one of ammonia water, oxalic acid or citric acid, or a combination of at least two of them.

[0019] Preferably, the oxidant comprises any one of hydrogen peroxide, potassium permanganate or sodium hypochlorite, or a combination of at least two thereof.

[0020] Preferably, the mass concentration of the oxidant solution is 0.5-5%, for example, 0.5%, 1%, 2%, 3%, 4% or 5%.

[0021] Preferably, the dispersant comprises cetyltrimethylammonium bromide and / or sodium citrate.

[0022] Preferably, the mass concentration of the morphology regulator is 0.1-0.5%, for example, 0.1%, 0.2%, 0.3%, 0.4% or 0.5%.

[0023] Preferably, the topography modifier comprises ethylene glycol and / or ethylenediaminetetraacetic acid.

[0024] Preferably, in the nucleation stage, the flow rate of the oxidant solution is 0.1 to 0.3 L / h, for example, 0.1 L / h, 0.13 L / h, 0.15 L / h, 0.18 L / h, 0.2 L / h, 0.23 L / h, 0.25 L / h, 0.28 L / h or 0.3 L / h.

[0025] Preferably, during the particle growth stage, the flow rate of the oxidant solution is 0.5 to 0.8 L / h, for example, 0.5 L / h, 0.53 L / h, 0.55 L / h, 0.58 L / h, 0.6 L / h, 0.63 L / h, 0.65 L / h, 0.68 L / h, 0.7 L / h, 0.73 L / h, 0.75 L / h, 0.78 L / h or 0.8 L / h, etc.

[0026] In the present invention, the flow rate of the oxidant solution in the nucleation stage and the particle growth stage is regulated, and the weak oxidizing environment in the nucleation stage is converted to a strong oxidizing environment, which is beneficial to modifying the surface sphericity, allowing the particles to grow rapidly without agglomeration; if the flow rate of the oxidant solution in the nucleation stage is too large, it will affect the nucleation situation; if the flow rate of the oxidant solution in the particle growth stage is too low, it will lead to too slow growth rate, poor sphericity, and easy occurrence of nuclear explosion.

[0027] Preferably, the difference between the particle size of the particles obtained by the co-precipitation reaction in the morphology adjustment stage and the particle size of the particles obtained by the co-precipitation reaction in the particle growth stage is 1 to 3 μm, for example, 1 μm, 1.3 μm, 1.5 μm, 1.8 μm, 2 μm, 2.3 μm, 2.5 μm, 2.8 μm or 3 μm, etc.

[0028] In the present invention, the surface morphology of the particles can be optimized by adjusting the difference in particle size (i.e., the morphology adjustment stage is performed 1 to 3 μm before stopping the reactor. If the difference in particle size is too large, not only will the surface morphology adjustment fail to be achieved, but the overall sphericity will be affected and small particles will appear.

[0029] Preferably, the coprecipitation reaction temperature is 40-60°C, such as 40°C, 50°C or 60°C.

[0030] Preferably, the pH value of the coprecipitation reaction is 8 to 12, for example, 8, 8.5, 9, 9.5, 10, 10.5, 11, 11.5 or 12.

[0031] Preferably, after the coprecipitation reaction is completed, aging, filtration, washing and drying are carried out in sequence.

[0032] As a preferred technical solution, the preparation method comprises the following steps:

[0033] Adding a mixed metal salt solution, a precipitant solution, and a complexing agent solution in parallel, sequentially performing co-precipitation reactions in a nucleation stage, a particle growth stage, and a morphology adjustment stage, followed by aging, filtering, washing, and drying to obtain the positive electrode precursor;

[0034] Wherein, the mixed metal salt includes nickel salt, cobalt salt and M metal salt; in the nucleation stage, the mixed metal salt solution also includes a dispersant, and the concurrent addition also includes an oxidant solution with a flow rate of 0.1 to 0.3 L / h; in the particle growth stage, the concurrent addition also includes an oxidant solution with a flow rate of 0.5 to 0.8 L / h; in the morphology adjustment stage, the mixed metal salt solution also includes a morphology regulator and a dispersant; the difference between the particle size of the particles obtained by the co-precipitation reaction in the morphology adjustment stage and the particle size of the particles obtained by the co-precipitation reaction in the particle growth stage is 1 to 3 μm.

[0035] In a second aspect, the present invention provides a positive electrode precursor, which is prepared by the method for preparing the positive electrode precursor as described in the first aspect.

[0036] In a third aspect, the present invention provides a positive electrode material, wherein the raw material of the positive electrode material includes the positive electrode precursor as described in the second aspect.

[0037] The precursor provided by the present invention can be used as a precursor material for lithium-ion batteries or as a precursor material for sodium-ion batteries. When preparing the corresponding positive electrode material, the precursor material is mixed with a lithium source / sodium source and sintered. The sintering process can be doped or coated, and adaptive adjustment can be made according to actual needs.

[0038] In a fourth aspect, the present invention further provides a battery, comprising the positive electrode material as described in the third aspect.

[0039] Preferably, the battery comprises a lithium-ion battery and / or a sodium-ion battery.

[0040] Compared with the prior art, the present invention has the following beneficial effects:

[0041] The preparation method of the precursor provided by the present invention can obtain crystal nuclei with an ideal particle size without causing particle agglomeration under the synergistic effect of a weakly oxidizing environment and a dispersant in the nucleation stage; in the particle growth stage, in a strong oxidizing environment, the product can achieve rapid growth and improve sphericity, and no dispersant needs to be added in this stage; further, in the morphology adjustment stage, the oxidant is replaced by a morphology regulator and a dispersant, thereby optimizing the surface morphology of the product and obtaining a positive electrode precursor material with a stable structure and controllable physical and chemical indicators. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 This is an SEM image of the positive electrode precursor material provided in Example 1.

[0043] Figure 2 This is the SEM image of the positive electrode precursor material provided in Example 3.

[0044] Figure 3This is the SEM image of the positive electrode precursor material provided in Example 4.

[0045] Figure 4 This is the SEM image of the positive electrode precursor material provided in Comparative Example 1.

[0046] Figure 5 This is the SEM image of the positive electrode precursor material provided in Comparative Example 2.

[0047] Figure 6 This is the SEM image of the positive electrode precursor material provided in Comparative Example 4. DETAILED DESCRIPTION

[0048] The technical solution of the present invention is further described below by way of specific embodiments. It should be understood by those skilled in the art that the embodiments are merely to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0049] Example 1

[0050] This embodiment provides a method for preparing a nickel-cobalt-manganese hydroxide precursor material, the preparation method comprising the following steps:

[0051] (1) preparing mixed metal salt (nickel:cobalt:manganese molar ratio of 8:1:1, total metal ion concentration of 90 g / L) solutions A1 (A1 also includes dispersant CTAB), A2 and A3 (A3 also includes morphology modifier ethylene glycol and dispersant CTAB added in an amount of 0.5% by weight of the total metal salt), precipitant solution B (32% by weight industrial liquid caustic soda), complexing agent solution C (15% by weight ammonia water), and oxidant solution D (0.5% by weight hydrogen peroxide);

[0052] (2) controlling the reactor at a certain temperature, and adding a precipitant solution and a complexing agent solution into the reactor as a base solution;

[0053] A mixed metal salt solution (flow rate of 10 L / h), a precipitant solution (5 L / h) and a complexing agent solution (flow rate of 0.5 L / h) were added in parallel to carry out the following stages of coprecipitation reaction (temperature of 60°C, pH value maintained in the range of 11.5 to 12):

[0054] Nucleation stage: During the nucleation stage, the oxidant solution with a flow rate of 0.1 L / h and the mixed metal salt solution A1 were added simultaneously and stirred continuously;

[0055] Particle growth stage: After nucleation, the flow rate of the oxidant solution was adjusted to 0.5 L / h, the mixed metal salt solution was A2, and stirring was continued;

[0056] Morphology adjustment stage: stop feeding the oxidant 1 μm before stopping the kettle, make the mixed metal salt solution A3, and continue stirring;

[0057] (3) After the reaction is completed, the reaction slurry is placed in an aging tank and aged for 5 hours, and then filtered, washed, dried, and sieved in sequence to obtain a nickel-cobalt-manganese hydroxide precursor material.

[0058] Example 2

[0059] This embodiment provides a method for preparing a nickel-cobalt-manganese hydroxide precursor material, the preparation method comprising the following steps:

[0060] (1) preparing mixed metal salt (nickel:cobalt:manganese molar ratio of 6:2:2, total metal ion concentration of 120 g / L) solutions A1 (A1 also includes dispersant CTAB), A2 and A3 (A3 also includes morphology modifier ethylenediaminetetraacetic acid and dispersant sodium citrate added in an amount of 0.5% by weight of the total metal salt), precipitant solution B (industrial liquid caustic soda with a mass fraction of 32%), complexing agent solution C (ammonia water with a mass fraction of 15%), and oxidant solution D (sodium hypochlorite with a mass percentage of 2%);

[0061] (2) controlling the reactor at a certain temperature, and adding a precipitant solution and a complexing agent solution into the reactor as a base solution;

[0062] A mixed metal salt solution (flow rate of 10 L / h), a precipitant solution (5 L / h) and a complexing agent solution (flow rate of 0.5 L / h) were added in parallel to carry out the following stages of coprecipitation reaction (temperature of 60°C, pH value maintained in the range of 11 to 11.5):

[0063] Nucleation stage: During the nucleation stage, the oxidant solution with a flow rate of 0.3 L / h and the mixed metal salt solution A1 were added simultaneously and stirred continuously;

[0064] Particle growth stage: After nucleation, the flow rate of the oxidant solution was adjusted to 0.8 L / h, the mixed metal salt solution was A2, and stirring was continued;

[0065] Morphology adjustment stage: stop feeding the oxidant before the reactor stops 3μm, and the mixed metal salt solution is A3, and continue stirring;

[0066] (3) After the reaction is completed, the reaction slurry is placed in an aging tank and aged for 5 hours, and then filtered, washed, dried, and sieved in sequence to obtain a nickel-cobalt-manganese hydroxide precursor material.

[0067] Example 3

[0068] The difference between this embodiment and embodiment 1 is that the flow rate of the oxidant solution in the nucleation stage in step (2) of this embodiment is 0.4 L / h.

[0069] The rest of the preparation methods and parameters were the same as those in Example 1.

[0070] Example 4

[0071] The difference between this embodiment and embodiment 2 is that in step (2) of this embodiment, the oxidant feeding is stopped 4 μm before the kettle is stopped.

[0072] The rest of the preparation methods and parameters were the same as those in Example 2.

[0073] Comparative Example 1

[0074] The difference between this comparative example and Example 1 is that in this comparative example, step (2) does not contain a morphology adjustment stage, that is, the particle growth stage is maintained until the reactor is stopped.

[0075] The rest of the preparation methods and parameters were the same as those in Example 1.

[0076] Comparative Example 2

[0077] The difference between this comparative example and Example 1 is that in the nucleation stage in step (2) of this comparative example, no dispersant is added to the mixed metal salt solution.

[0078] The rest of the preparation methods and parameters were the same as those in Example 1.

[0079] Comparative Example 3

[0080] The difference between this comparative example and Example 1 is that the flow rate of the oxidant solution in the nucleation stage in step (2) of this comparative example is 0.5 L / h.

[0081] The rest of the preparation methods and parameters were the same as those in Example 1.

[0082] Comparative Example 4

[0083] The difference between this comparative example and Example 1 is that in this comparative example, nitrogen / compressed air is used instead of the oxidant to control the degree of oxidation (i.e., the preparation process is not carried out in stages, and the above-mentioned mixed gas is used for reaction throughout the coprecipitation process).

[0084] The rest of the preparation methods and parameters were the same as those in Example 1.

[0085] Figure 1 The SEM image of the positive electrode precursor material provided in Example 1 is shown.

[0086] Figure 2 The SEM image of the positive electrode precursor material provided in Example 3 is shown.

[0087] Figure 3 The SEM image of the positive electrode precursor material provided in Example 4 is shown.

[0088] from Figure 1-Figure 3It can be seen that if the flow rate of the oxidant solution in the nucleation stage is too large, it will make nucleation difficult and the subsequent particles cannot grow; and if the difference in particle size (morphology adjustment stage and particle growth stage) is too large, it will affect the surface morphology and cause morphological abnormalities.

[0089] Figure 4 The SEM image of the positive electrode precursor material provided in Comparative Example 1 is shown.

[0090] Figure 5 The SEM image of the positive electrode precursor material provided in Comparative Example 2 is shown.

[0091] Figure 6 The SEM image of the positive electrode precursor material provided in Comparative Example 4 is shown.

[0092] from Figure 1 、 Figure 4-6 It can be seen from the comparison that if the morphology adjustment stage is not carried out, the surface will be too loose and the sphericity will be poor; if the dispersant is not added in the nucleation stage, the problem of uneven particles and easy agglomeration in the early stage cannot be solved; controlling the oxidation degree by gas will easily lead to local supersaturation imbalance, resulting in particle agglomeration.

[0093] From the comparison between Example 1 and Example 3, it can be seen that if the flow rate of the oxidant solution in the nucleation stage is too large, it will make nucleation difficult and the subsequent particles cannot grow.

[0094] From the comparison between Example 1 and Example 4, it can be seen that if the difference in particle size (the morphology adjustment stage and the particle growth stage) is too large, it will affect the surface morphology and cause morphological abnormalities.

[0095] From the comparison between Example 1 and Comparative Example 1, it can be seen that if the morphology adjustment stage is not performed, the surface is too loose and the sphericity is poor.

[0096] From the comparison between Example 1 and Comparative Example 2, it can be seen that if no dispersant is added in the nucleation stage, the problem of uneven particles and easy agglomeration in the early stage cannot be solved.

[0097] In summary, the preparation method of the precursor provided by the present invention can obtain crystal nuclei with an ideal particle size without causing particle agglomeration under the synergistic effect of a weakly oxidizing environment and a dispersant in the nucleation stage; in the particle growth stage, in a strong oxidizing environment, the product can achieve rapid growth and improve the sphericity, and no dispersant is needed in this stage; further, in the morphology adjustment stage, the oxidant is replaced by a morphology regulator and a dispersant to optimize the surface morphology of the product. That is, the three stages in the present invention work synergistically to obtain a positive electrode precursor material with good sphericity, stable structure and not easy to crack, thereby improving the electrochemical performance of the positive electrode material.

[0098] The applicant declares that the above is only a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention fall within the scope of protection and disclosure of the present invention.

Claims

1. A method for preparing a positive electrode precursor, characterized in that: The preparation method comprises the following steps: Adding a mixed metal salt solution, a precipitant solution, and a complexing agent solution in parallel, and sequentially performing a co-precipitation reaction of a nucleation stage, a particle growth stage, and a morphology adjustment stage to obtain the positive electrode precursor; Wherein, the mixed metal salt includes nickel salt, cobalt salt and M metal salt; in the nucleation stage, the mixed metal salt solution also includes a dispersant, and an oxidant solution is added in parallel; in the particle growth stage, an oxidant solution is also added in parallel; in the morphology adjustment stage, the mixed metal salt solution also includes a morphology regulator and a dispersant; the flow rate of the oxidant solution in the particle growth stage is greater than the flow rate of the oxidant solution in the nucleation stage; and no oxidant is added in the morphology adjustment stage.

2. The method for preparing a positive electrode precursor according to claim 1, wherein: The concentration of metal ions in the mixed metal salt solution is 80-120 g / L.

3. The method for preparing the positive electrode precursor according to claim 1, characterized in that: The M in the M metal salt includes any one of Mn, Fe, Cu, Al or Mg, or a combination of at least two of them.

4. The method for preparing a cathode precursor according to claim 1, wherein: The concentration of the precipitant solution is 200-400 g / L.

5. The method for preparing a cathode precursor according to claim 1, wherein: The precipitant includes any one of sodium hydroxide, sodium carbonate or ammonium bicarbonate, or a combination of at least two of them.

6. The method for preparing a cathode precursor according to claim 1, wherein: The mass concentration of the complexing agent solution is 10-20%.

7. The method for preparing a cathode precursor according to claim 1, wherein: The complexing agent includes any one of ammonia water, oxalic acid or citric acid, or a combination of at least two of them.

8. The method for preparing a cathode precursor according to claim 1, wherein: The oxidant includes any one of hydrogen peroxide, potassium permanganate or sodium hypochlorite, or a combination of at least two of them.

9. The method for preparing a cathode precursor according to claim 1, wherein: The mass concentration of the oxidant solution is 0.5-5%.

10. The method for preparing a cathode precursor according to claim 1, wherein: The dispersant includes cetyltrimethylammonium bromide and / or sodium citrate.

11. The method for preparing a cathode precursor according to claim 1, wherein: The mass concentration of the morphology regulator is 0.1-0.5%.

12. The method for preparing a cathode precursor according to claim 1, wherein: The topography regulator includes ethylene glycol and / or ethylenediaminetetraacetic acid.

13. The method for preparing a cathode precursor according to claim 1, wherein: During the nucleation stage, the flow rate of the oxidant solution is 0.1-0.3 L / h.

14. The method for preparing a cathode precursor according to claim 1, wherein: During the particle growth stage, the flow rate of the oxidant solution is 0.5-0.8 L / h.

15. The method for preparing a cathode precursor according to claim 1, wherein: The difference between the particle size of the particles obtained by the coprecipitation reaction in the morphology adjustment stage and the particle size of the particles obtained by the coprecipitation reaction in the particle growth stage is 1-3 μm.

16. The method for preparing a cathode precursor according to claim 1, wherein: The temperature of the coprecipitation reaction is 40-60°C.

17. The method for preparing a cathode precursor according to claim 1, wherein: The pH value of the coprecipitation reaction is 8-12.

18. The method for preparing a cathode precursor according to claim 1, wherein: After the coprecipitation reaction is completed, aging, filtering, washing and drying are carried out in sequence.

19. The method for preparing a cathode precursor according to claim 1, wherein: The preparation method comprises the following steps: Adding a mixed metal salt solution, a precipitant solution, and a complexing agent solution in parallel, sequentially performing co-precipitation reactions in a nucleation stage, a particle growth stage, and a morphology adjustment stage, followed by aging, filtering, washing, and drying to obtain the positive electrode precursor; Wherein, the mixed metal salt includes nickel salt, cobalt salt and M metal salt; in the nucleation stage, the mixed metal salt solution also includes a dispersant, and the concurrent addition also includes an oxidant solution with a flow rate of 0.1~0.3L / h; in the particle growth stage, the concurrent addition also includes an oxidant solution with a flow rate of 0.5~0.8L / h; in the morphology adjustment stage, the mixed metal salt solution also includes a morphology regulator and a dispersant; the difference between the particle size of the particles obtained by the co-precipitation reaction in the morphology adjustment stage and the particle size of the particles obtained by the co-precipitation reaction in the particle growth stage is 1~3μm.

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