Cathode material precursor, preparation method thereof, cathode material and battery

Abstract

This invention provides a cathode material precursor, its preparation method, a cathode material, and a battery. The cathode material precursor includes one or more of Ni, Co, and M elements, where M is selected from one or more of Al, Mn, Fe, Ti, and V. In the XRD pattern of the cathode material precursor, the cathode material has (003) peaks and (006) peaks. The 2θ value of the (003) peak is 1°–14°, the 2θ value of the (006) peak is twice that of the (003) peak, and the 2θ value of the (006) peak is 2°–28°. The XRD pattern of the cathode material precursor of this application has a hexagonal crystal system microstructure. Therefore, the conversion process from the cathode material precursor to the cathode material is a topological transformation. This topological transformation has lower ion migration resistance and faster reaction kinetics, thus effectively reducing the difficulty of converting the precursor into the cathode material.

Description

Technical Field

[0001] This invention relates to the field of battery cathode material technology, and more specifically, to a cathode material precursor and its preparation method, a cathode material, and a battery. Background Technology

[0002] In recent years, the rapid development of lithium-ion battery (LIB) technology has led to the continuous expansion of its application fields: from the traditional 3C consumer electronics sector, it has penetrated into core areas such as power tools, electric vehicles, and large-scale energy storage systems, and is further exploring cutting-edge applications such as electric ships and electric aircraft. Currently, the preparation of precursors for NCM ternary cathode materials mainly focuses on nickel-cobalt-manganese ternary composite hydroxides (Ni...). 1-x-y Co x M y Synthesis of (OH)₂. In this system, Ni, Co, and Mn all exist in the +2 oxidation state; however, Co... 2+ With Mn 2+ The high oxidation sensitivity of ions poses a technical challenge. To maintain their valence stability, it is necessary to avoid contact with air (including dissolved oxygen). Nitrogen is often used as an inert protective gas throughout the entire preparation process. While effective, this significantly increases production costs.

[0003] Ni is currently widely used 1-x-y Co x M y The (OH)₂ precursor, with its P21 / c monoclinic crystal structure, undergoes a complex phase transformation process during the subsequent synthesis of ternary materials. The asynchronous nature of this series of phase transformations not only exacerbates the resistance to ion migration and slows down reaction kinetics at the microscopic level, but also leads to higher calcination temperatures and longer reaction times at the macroscopic level. This presents numerous challenges, including increased production costs, safety risks, and the complexity of phase transformations, necessitating innovative solutions to overcome these technological bottlenecks. Summary of the Invention

[0004] The main objective of this invention is to provide a cathode material precursor and its preparation method, a cathode material, and a battery, in order to solve the problems of poor stability and easy quality defects when the precursor of the ternary cathode material is prepared into a cathode material in the prior art.

[0005] To achieve the above objectives, according to one aspect of the present invention, a cathode material precursor is provided, comprising one or more of Ni, Co, and M elements, wherein the M element is selected from one or more of Al, Mn, Fe, Ti, and V; in the XRD pattern of the cathode material precursor, the cathode material has a (003) peak and a (006) peak, wherein the 2θ value of the (003) peak is 1° to 14°, the 2θ value of the (006) peak is twice the 2θ value of the (003) peak, and the 2θ value of the (006) peak is 2° to 28°.

[0006] Furthermore, the cathode material precursor satisfies at least one of the following characteristics:

[0007] (1) The unit cell parameters a and c satisfy the following:

[0008] (2) The unit cell parameters a and c satisfy: c / a ≥ 2.1;

[0009] (3) The cathode material precursor was characterized by synchrotron radiation fine structure absorption spectroscopy. The obtained E-space spectrum was Fourier transformed to obtain its R-space test spectrum. The R-space test spectrum includes a first characteristic peak and a second characteristic peak, which can be attributed to the first coordination shell and the second coordination shell of the cathode material precursor, respectively. The first characteristic peak is located on the x-axis of the R-space test spectrum. Between, the second characteristic peak is located on the x-axis of the R-space test spectrum. between;

[0010] (4) The cathode material precursor includes metal-oxygen bonds and metal-oxygen-metal bridging bonds. The coordination number of the metal-oxygen bond is N1 and the bond length is R1. The coordination number of the metal-oxygen-metal bridging bond is N2 and the bond length is R2. 2≤N1≤6. 2≤N²≤6,

[0011] (5) The interlayer spacing of the cathode material precursor is d, 0.30nm≤d≤2.85nm;

[0012] (6) The cathode material precursor also includes at least one element selected from Mg, Cr, Ca, Cu, and Zn;

[0013] (7) The cathode material precursor also includes at least one element selected from Mg, Cr, Ca, Cu and Zn. The sum of the mass of Mg, Cr, Ca, Cu and Zn elements in the cathode material precursor is 0 to 50% of the sum of the molar amounts of Ni, Co and M elements in the cathode material precursor.

[0014] (8) The cathode material precursor also includes at least one element selected from Mg, Cr, Ca, Cu and Zn. The sum of the masses of Mg, Cr, Ca, Cu and Zn elements in the cathode material precursor is 0 to 10% of the sum of the molar masses of Ni, Co and M elements in the cathode material precursor.

[0015] Furthermore, the general chemical formula of the cathode material precursor is [Ni x Co y M z (OH)2] e+ ·(A f- ) (e / f) ·mH₂O, where M is one or more of Al, Mn, Fe, Ti, and V, 0≤x≤1, 0≤y≤1, 0≤z≤1, x+y+z=1, 0<e≤3, 1≤f≤5, 0.1≤m≤2, and A is CO₃²⁻. 2- NO3 - SO4 2- F - Cl - ,Br - I - C4~C 16 At least one of the organic acid radicals and porphyrins.

[0016] Furthermore, the cathode material precursor satisfies at least one of the following characteristics:

[0017] (1) When M is one or more of Al and Fe, the valence state of Ni is +2.7 to +3.3, the valence state of Co is +2.8 to +3.2, and the valence state of M is +2.7 to +3.3;

[0018] (2) When M is one or more of Mn, Ti and V, the valence state of Ni is +2 to +3, the valence state of Co is +2.8 to +3.2, and the valence state of M is +3.8 to +4.2;

[0019] (3) y = 0, element M is Mn;

[0020] (4) 0.1 < e ≤ 2;

[0021] (5) 1 ≤ f ≤ 3;

[0022] (6) The M element is selected from one or both of Mn and Al.

[0023] Furthermore, the cathode material precursor satisfies at least one of the following characteristics:

[0024] (1) The specific surface area of ​​the cathode material precursor is 8-12 m². 2 / g;

[0025] (2) The compaction density of the cathode material precursor is 0.5–4.2 g / cm³. 3 ;

[0026] (3) The tap density of the cathode material precursor is 1-3 g / cm³. 3 ;

[0027] (4) The grain size of the cathode material precursor is 4-8 μm.

[0028] According to another aspect of the present invention, a method for preparing a cathode material precursor is provided, the method comprising the following steps: passing a salt solution and an alkaline solution separately into water containing oxygen molecules, and carrying out a nucleation reaction under a first stirring condition to obtain a mixed slurry, wherein the cations in the salt solution include one or more of Ni, Co and M elements, and the M element is selected from any one or more of Al, Mn, Fe, Ti and V; crystallizing the mixed slurry under oxygen conditions to obtain a crystallized slurry; and washing, dehydrating, pulverizing and demagnetizing the crystallized slurry to obtain the cathode material precursor.

[0029] Furthermore, the preparation method satisfies at least one of the following characteristics:

[0030] (1) The types of anions in salt solutions include CO32-. 2- NO3 - SO4 2- F - Cl - ,Br - I - C4-C 16 At least one of organic acid radicals and porphyrins;

[0031] (2) The alkaline solution is a solution formed by mixing at least one of NaOH, Na2CO3, NaHCO3, KOH, KHCO3, K2CO3, urea, ammonium chloride and ammonia water with water;

[0032] (3) The rate of introduction of salt solution is 1 mL / min to 1000 mL / min, and the rate of introduction of alkali solution is 1 mL / min to 1000 mL / min;

[0033] (4) Pass the salt solution and the alkaline solution into water with a dissolved oxygen saturation of 20% or more, respectively;

[0034] (5) Under the first stirring condition, the stirring speed is 200 to 4000 rpm / min;

[0035] (6) The nucleation reaction temperature is 0–100℃;

[0036] (7) During the nucleation reaction, the pH value of the mixed slurry is 9.7 to 10.3;

[0037] (8) During the crystallization process, the dissolved oxygen saturation in the mixed slurry is 20% to 100%;

[0038] (9) The crystallization treatment time is 0 to 48 hours;

[0039] (10) The temperature for crystallization treatment is 0–120℃;

[0040] (11) The crystallization treatment is carried out under the second stirring condition, in which the stirring speed is 200 to 2000 rpm / min.

[0041] Furthermore, interlayer ion exchange is performed on the product after water washing.

[0042] According to another aspect of this application, a cathode material is provided, which is prepared from any of the cathode material precursors described above, or prepared from a cathode material precursor prepared by any of the cathode material precursor preparation methods described above.

[0043] According to another aspect of this application, a battery is provided that contains the above-described positive electrode material.

[0044] Applying the technical solution of this invention, the XRD pattern of the cathode material precursor of this application has (003) peaks and (006) peaks. The 2θ value of the (003) peak is 1° to 14°, the 2θ value of the (006) peak is twice that of the (003) peak, and the 2θ value of the (006) peak is 2° to 28°. Extensive research by the inventors has shown that when the cathode material precursor meets the above characteristics, the conversion process from the cathode material precursor to the cathode material is a topological transformation. This topological transformation process has lower ion migration resistance and faster reaction kinetics, thus effectively reducing the difficulty of conversion from the precursor to the cathode material. Simultaneously, the cathode material prepared through topological transformation has superior overall performance, especially in terms of cycle life and rate performance.

[0045] The preparation method provided in this application involves nucleation and crystallization under oxygen-containing conditions, which fully oxidizes the metal ions to form the cathode material precursor as described above. The conversion of the cathode material precursor into the cathode material is a topological transformation, which exhibits lower ion migration resistance and faster reaction kinetics, thus effectively reducing the difficulty of conversion on a macroscopic level. Specifically, it can lower the calcination temperature and reaction time of the precursor. Simultaneously, this topological transformation process can effectively reduce the content of impurities such as M2O3, M3O4, and spinel (M being Fe, Co, or Ni) in the cathode material product, thereby preventing oxides or spinel impurities from occupying the space originally belonging to the active material, leading to a reduction in the amount of active material and consequently a decrease in the battery's reversible capacity. Furthermore, the cathode material prepared through topological transformation has a more complete crystal structure, fewer crystal gaps and cracks, and superior overall performance, especially in cycle and rate performance. Moreover, this preparation method does not require the addition of a complexing agent or inert gas protection, is simple to operate, and is suitable for large-scale production applications. Attached Figure Description

[0046] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0047] Figure 1 A schematic diagram of the structure of a secondary battery according to an embodiment of the present invention is shown;

[0048] Figure 2 The XRD pattern of the cathode material precursor according to Embodiment 1 of the present invention is shown;

[0049] Figure 3 The XRD pattern of the cathode material precursor according to Comparative Example 1 of the present invention is shown.

[0050] The above-mentioned figures include the following reference numerals: 001, positive electrode sheet; 002, separator; 003, negative electrode sheet. Detailed Implementation

[0051] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0052] As analyzed in the background section of this application, existing technologies suffer from poor stability and susceptibility to quality defects when preparing ternary cathode material precursors into cathode materials. To address this issue, this application provides a cathode material precursor, its preparation method, a cathode material, and a battery.

[0053] According to a typical embodiment of this application, a cathode material precursor is provided, which includes one or more of Ni, Co and M elements, wherein the M element is selected from one or more of Al, Mn, Fe, Ti and V; the XRD pattern of the cathode material precursor has a (003) peak and a (006) peak, wherein the 2θ value of the (003) peak is 1° to 14°, the 2θ value of the (006) peak is twice the 2θ value of the (003) peak, and the 2θ value corresponding to the (006) peak is 2° to 28°.

[0054] The XRD pattern of the cathode material precursor of this application has (003) peaks and (006) peaks, and the 2θ value of the (006) peak is twice that of the (003) peak. Extensive research by the inventors has shown that when the cathode material precursor meets the above characteristics, the conversion process from the precursor to the cathode material is a topological transformation. This topological transformation process has lower ion migration resistance and faster reaction kinetics, thus effectively reducing the difficulty of conversion from the precursor to the cathode material. Furthermore, the cathode material prepared through topological transformation exhibits superior overall performance, especially in cycle life and rate performance.

[0055] In the XRD pattern of the aforementioned cathode material precursor, the 2θ value corresponding to the (003) peak ranges from 1° to 14°, specifically 1°, 2°, 3°, 4°, 5°, 6°, 7°, 8°, 9°, 10°, 11°, 12°, 13°, 14°, etc., but is not limited to these values; preferably, the 2θ value corresponding to the (003) peak ranges from 8.5° to 12.5°. The 2θ value of the (006) peak is twice that of the (003) peak, and its range is from 2° to 28°, specifically 2°, 4°, 6°, 8°, 10°, 12°, 14°, 16°, 18°, 20°, 22°, 24°, 26°, 28°, etc. Preferably, the 2θ value corresponding to the (006) peak ranges from 17° to 25°.

[0056] In some embodiments of this application, the X-ray diffraction (XRD) pattern of the above-mentioned cathode material precursor has two diffraction peaks at low angles (0-40°), corresponding to the (003) crystal plane and the (006) crystal plane, respectively; and two characteristic diffraction peaks at high angles (55°-65°), corresponding to the (110) crystal plane and the (113) crystal plane, respectively.

[0057] In some embodiments of this application, the hexagonal crystal system formed by the cathode material precursor of this application satisfies the following cell parameters: In the process of synthesizing cathode materials from precursors, this application controls the unit cell parameter a of the precursor at... to Within this range, it is beneficial to promote lithium-ion intercalation during the process of precursor formation of cathode material.

[0058] Specifically, the value of axis unit 'a' can be... Of course, it can also be other values ​​within the above range. For the hexagonal crystal system, the cell parameter a = b, therefore the value of the axial unit b can also be the point value mentioned above or other values ​​within the above range. Preferably, the value of the axial unit a is...

[0059] Specifically, the value of the axis unit c can be And so on, but not limited to this. The value of axis unit c is...

[0060] In some embodiments of this application, the values ​​of the axis units a and c satisfy: c / a ≥ 2.1. Specifically, the value of c / a can be 2.2, 2.5, 3, 4, 5, 8, 10, 15, 20, etc., or other values ​​within the above range, without specific limitation. Preferably, 2.9 ≤ c / a ≤ 10.

[0061] In some embodiments of this application, the interlayer spacing of the cathode material precursor is d, where 0.30nm ≤ d ≤ 2.85nm. Specifically, the interlayer spacing d of the hexagonal crystal system of the cathode material precursor in this application can be 0.3nm, 0.4nm, 0.5nm, 0.6nm, 0.7nm, 0.8nm, 0.9nm, 1nm, 1.1nm, 1.2nm, 1.3nm, 1.4nm, 1.5nm, 1.6nm, 1.7nm, 1.8nm, 1.9nm, 2nm, 2.1nm, 2.2nm, 2.3nm, 2.4nm, 2.5nm, 2.6nm, 2.7nm, 2.8nm, etc., or other values ​​within the above range. It should be noted that the interlayer spacing d in this application is the interplanar spacing of the (003) crystal planes of the cathode material minus the layer thickness. The interplanar spacing of the (003) crystal planes is obtained by XRD characterization of the cathode material precursor and then applying the Scherrer equation. The layer thickness is a constant, and the layer thickness is 0.48 nm.

[0062] In some embodiments of this application, the cathode material precursor is characterized by synchrotron radiation fine structure absorption spectroscopy. The obtained E-space spectrum is then Fourier transformed to obtain its R-space test spectrum. The R-space test spectrum includes a first characteristic peak and a second characteristic peak, with the first characteristic peak located on the x-axis of the R-space test spectrum. Between, the second characteristic peak is located on the x-axis of the R-space test spectrum. The first characteristic peak corresponds to the first coordination shell, and the second characteristic peak corresponds to the second coordination shell. The first coordination shell includes metal-oxygen bonds, and the second coordination shell includes metal-oxygen-metal bridging bonds. By fitting the R-space test spectrum, the coordination number N1 and bond length R1 of the metal-oxygen bonds in the cathode material precursor, and the coordination number N2 and bond length R2 of the metal-oxygen-metal bridging bonds, can be obtained. These parameters satisfy: 2 ≤ N1 ≤ 6. 2≤N²≤6, When the coordination number and bond length of the metal-oxygen bonds in the first coordination shell of the cathode material precursor are within the aforementioned range, the shell structure achieves high order and stability, ensuring a close and uniform coordination relationship between metal ions and oxygen ions. This close and uniform coordination not only improves the crystal integrity of the material and reduces lattice defects but also effectively promotes the transport efficiency of electrons and ions within the crystal lattice. Similarly, when the coordination number and bond length of the metal-oxygen-metal bridging bonds in the second coordination shell are within the aforementioned range, the second coordination shell forms a more stable and ordered structural arrangement, enhancing interatomic interactions and electron conduction efficiency. This order and stability help optimize the ion channels of the material and reduce structural distortion and stress accumulation during high-temperature synthesis. Therefore, when the coordination number and bond length of the first and second coordination shells are within the aforementioned range, they can synergistically improve the electrochemical performance of the cathode material prepared from this cathode material precursor, increasing energy density and extending cycle life. Specifically, the coordination number N1 of the metal-oxygen bond in the first coordination shell can be 2, 3, 4, 5, or 6; the bond length R1 can be... And so on, but not limited to this. Specifically, the coordination number N2 of the metal-oxygen-metal bridging bond in the second shell can be... or Bond length R2 can be And so on, but not limited to these.

[0063] In some typical embodiments of this application, the general chemical formula of the cathode material precursor is [Ni x Co y M z (OH)2] e+ ·(A f- ) (e / f)·mH₂O, where M is one or more of Al, Mn, Fe, Ti, and V, 0≤x≤1 (e.g., 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, etc.), 0≤y≤1 (e.g., 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, etc.), 0≤z≤1 (e.g., 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, etc.), x+y+z=1, 0<e≤3, 1≤f≤5, and A is CO₃²⁻. 2- NO3 - SO4 2- F - Cl - ,Br - I - C4~C 16 It contains at least one of the following: organic acid radicals (such as succinate, glutarate, adipic acid, pimelic acid, octanoic acid, azelaic acid, sebacic acid, undecanoic acid, dodecanoic acid, etc.) and porphyrin, where m is the amount of water of crystallization, and 0.1≤m≤2.

[0064] The cathode material precursor conforming to the above general chemical formula contains the above-mentioned anions. The presence of anions can effectively change the interlayer spacing of the precursor, further reducing the hydrogen bonds or van der Waals forces between the intercalated anions and the main layers, thereby effectively reducing the Li during calcination. + The interlayer ion resistance can effectively reduce the calcination temperature and time when it is prepared into a cathode material, thereby reducing the preparation cost of the cathode material.

[0065] Furthermore, the anions in the aforementioned cathode material precursor have a large ionic radius, which can effectively increase the interlayer spacing of the precursor, thereby reducing the van der Waals interactions between the layers and between the plates. This significantly reduces the Li-induced degradation during the subsequent high-temperature calcination process to prepare the cathode material. + The energy barrier between ion insertion layers reduces the resistance to ion migration, directly promoting the Li... + The efficient migration and uniform distribution between layers are achieved. Therefore, compared with traditional cathode material precursors, the cathode material precursor conforming to the above general chemical formula in this application has a lower conversion difficulty in preparing cathode materials.

[0066] Specifically, the value of 'e' in the above general chemical formula can be 0.1, 0.3, 0.5, 1, 1.5, 2, 2.5, 3, etc., preferably 0.1 < e ≤ 2. Specifically, the value of 'f' in the above general chemical formula can be 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, etc., preferably 1 ≤ f ≤ 3. Specifically, the value of the amount of water of crystallization 'm' can be 0.1, 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, 9.5, etc., or other values ​​within this range.

[0067] In some typical embodiments of this application, when M is one or more of Mn, Ti, and V, the valence state of Ni is +2 to +3.3, the valence state of Co is +2.8 to +3.2, and the valence state of M is +3.8 to +4.2, which is exactly the same as the valence states of the corresponding elements in the NCM ternary cathode material. This eliminates the need for an additional oxidation step in the preparation of the cathode material precursor, effectively reducing the required concentration of compressed air or oxygen during the calcination process when using it as a raw material to prepare the ternary material, thereby further reducing the preparation cost of the cathode material. Conventional Ni... 1-x-y Co x M y In the (OH)2 precursor, Ni, Co, and Mn are all in the +2 valence state. In order to ensure that Co and Mn are not oxidized, it is often necessary to use a strict inert gas to protect Co and Mn from oxidation during the synthesis process. However, in the process of preparing ternary materials, a large amount of compressed air or oxygen needs to be introduced to ensure oxygen concentration so that Co and Mn can be fully oxidized, which leads to a huge waste of cost and quality risk.

[0068] In some embodiments of this application, the valence state of Ni in the cathode material precursor is +2 to +3.3, the valence state of Co is +2.8 to +3.2, and M is Mn, with a valence state of +3.8 to 4.2, which is exactly the same as the valence states of Ni, Co, and Mn in the NCM ternary cathode material. This eliminates the need for an additional oxidation step in the preparation of the cathode material from this precursor, effectively reducing the required concentration of compressed air or oxygen during the calcination process when using it as a raw material to prepare the ternary material, thereby further reducing the preparation cost of the cathode material.

[0069] In some typical embodiments of this application, when M is one or more of Al and Fe, the valence state of Ni is +2.7 to +3.3, the valence state of Co is +2.8 to +3.2, and the valence state of M is +2.7 to +3.3; the elements in the cathode material precursor have the same valence state as the relevant elements in the ternary cathode material, which facilitates its preparation as a cathode material.

[0070] In some typical embodiments of this application, y = 0, and element M is Mn, that is, the chemical formula of the cathode material precursor is [Ni x Mn z (OH)2] e+ ·(A f- ) (e / f) The precursor of cathode material with the chemical composition ·mH2O is particularly suitable as a precursor of lithium-rich cathode material, showing potential application value in high-performance battery systems.

[0071] In some preferred embodiments of this application, the M element is selected from one or both of Mn and Al, which is beneficial for further optimizing the electrochemical activity and stability of the cathode material precursor material.

[0072] In some embodiments of this application, the aforementioned cathode material precursor further includes at least one element selected from Mg, Cr, Ca, Cu, and Zn. These elements have similar ionic radii to Ni, Co, or M, and exhibit good dispersibility when doped into the aforementioned cathode material precursor. In some embodiments, the sum of the masses of Mg, Cr, Ca, Cu, and Zn elements in the cathode material precursor is 0–50% of the sum of the molar masses of Ni, Co, and M elements in the cathode material precursor, preferably 0–10%.

[0073] In some embodiments of this application, the specific surface area of ​​the cathode material precursor is 8–12 m². 2 / g, specifically 8m 2 / g, 8.5m 2 / g、9m 2 / g, 9.5m 2 / g, 10m 2 / g, 10.5m 2 / g、11m 2 / g, 11.5m 2 / g、12m 2 / g, etc., but not limited to this. A specific surface area of ​​the cathode material precursor within the above range is beneficial for preparing cathode materials with suitable specific surface areas and improving their lithium intercalation capability.

[0074] In some embodiments of this application, the compaction density of the cathode material precursor is 0.5–4.2 g / cm³. 3 Specifically, it can be 0.5g / cm 3 1g / cm 3 1.5g / cm 3 2g / cm 3 2.5g / cm 3 3g / cm 3 3.5g / cm 3 4g / cm3 Of course, it can also be other values ​​within the above range, which will help to further improve its overall performance.

[0075] In some embodiments of this application, the tap density of the above-mentioned cathode material precursor is 1-3 g / cm³. 3 Specifically, it can be 1g / cm 3 1.3g / cm 3 1.5g / cm 3 1.7g / cm 3 2g / cm 3 2.2g / cm 3 2.5g / cm 3 2.8g / cm 3 And so on, but not limited to these.

[0076] In some embodiments of this application, the grain size of the above-mentioned cathode material precursor is 4 to 8 μm, specifically 4 μm, 4.5 μm, 5 μm, 5.5 μm, 6 μm, 6.5 μm, 7 μm, 7.5 μm, 8 μm, etc., or other values ​​within the above range. This application does not limit this value.

[0077] According to another typical embodiment of this application, a method for preparing a cathode material precursor is provided. The preparation method includes the following steps: passing a salt solution and an alkaline solution separately into water containing oxygen molecules, and carrying out a nucleation reaction under a first stirring condition to obtain a mixed slurry. The cations in the salt solution include one or more of Ni, Co, and M elements, and the M element is selected from any one or more of Al, Mn, Fe, Ti, and V. The mixed slurry is crystallized in the presence of oxygen to obtain a crystallized slurry. The crystallized slurry is washed with water, dehydrated, pulverized, and demagnetized.

[0078] The preparation method provided in this application involves nucleation and crystallization under oxygen-containing conditions, which fully oxidizes the metal ions, forming a cathode material precursor with (003) and (006) characteristic peaks as described above. Through extensive research, the inventors discovered that the conversion of the cathode material precursor with the above characteristics into the cathode material involves a topological transformation. This topological transformation process exhibits lower ion migration resistance and faster reaction kinetics, thus effectively reducing the difficulty of conversion on a macroscopic level. Specifically, it can reduce the calcination temperature and reaction time of the precursor. Simultaneously, this topological transformation process can effectively reduce the content of impurity phases such as M2O3, M3O4, and spinel (M being Fe, Co, or Ni) in the cathode material product, thereby preventing oxides or spinel impurities from occupying the space originally belonging to the active material, leading to a reduction in the amount of active material and consequently reducing the reversible capacity of the battery. Furthermore, the cathode material prepared through topological transformation has a more complete crystal structure, fewer crystal gaps and cracks, and superior overall performance, especially in cycle and rate performance. Moreover, this preparation method does not require the addition of complexing agents or the protection of inert gases, making it simple to operate and easy to apply in large-scale production.

[0079] The solvent for the aforementioned salt solution can be selected from existing technologies, such as water, specifically distilled water, deionized water, etc. The specific salt is a compound capable of providing Ni, Co, or M elements. In some embodiments of this application, the anions in the salt solution include CO3. 2- NO3 - SO4 2- F - Cl - ,Br - I - At least one of organic acid radicals and porphyrins; the above anions have a large ionic radius, which can effectively increase the interlayer spacing of the precursor in the preparation of cathode material containing them, thereby reducing the van der Waals interaction forces between the interlayers and between the layers, thus significantly reducing the Li-induced degradation during the subsequent high-temperature calcination process for preparing the cathode material. + The energy barrier between ion insertion layers reduces the resistance to ion migration, directly promoting the Li... + Efficient migration and uniform distribution between layers. Preferably, the salt concentration in the above salt solution is 0.1–10 mol / L.

[0080] In some embodiments of this application, the alkaline solution is a solution formed by mixing at least one of NaOH, Na2CO3, NaHCO3, KOH, KHCO3, K2CO3, urea, ammonium chloride, and ammonia with water, which facilitates the formation of the aforementioned cathode material precursor. Preferably, the concentration of the alkaline solution is 0.1 mol / L to 20 mol / L.

[0081] This method effectively promotes crystal nucleation by controlling the cation concentration in the precursor solution. Furthermore, by lowering the synthesis / crystallization temperature and shortening the crystallization time, it limits excessive grain growth and ensures precise control of the precursor particle size. This process not only optimizes the morphology and particle size distribution of the precursor but also, due to the corresponding decrease in coordination numbers N1 and N2 caused by incomplete growth, may endow the precursor with unique physicochemical properties, providing more favorable conditions for optimizing the electrochemical performance of the subsequently prepared cathode material.

[0082] In some embodiments of this application, the rate of introduction of the salt solution is 1 mL / min to 1000 mL / min, and the rate of introduction of the alkali solution is 1 mL / min to 1000 mL / min. By controlling the introduction rates of the salt solution and alkali solution, the pH value in the mixed slurry can be adjusted to ensure product uniformity during the nucleation process.

[0083] In some embodiments of this application, a salt solution and an alkaline solution are respectively passed into water with a dissolved oxygen saturation of ≥20%, so that Co 2+ / 3+ With M 3 / 4+ It can be fully exposed to a high concentration of oxygen, thereby achieving a more thorough and uniform oxidation process. This oxidation state is conducive to precise control over the chemical composition, crystal structure and final electrochemical performance of the precursor.

[0084] Preferably, the salt solution and alkaline solution are separately passed into oxygen-saturated water. The method of oxygen dissolution can be chosen from existing technologies, such as continuously introducing oxygen into the water or compressed air. To improve the purity of the cathode material precursor and reduce impurities, the water containing oxygen molecules is high-purity water such as distilled water or deionized water.

[0085] In some embodiments of this application, in order to make the oxygen in the water come into more uniform contact with the salt solution and the alkaline solution, the stirring speed under the first stirring condition is 200 to 4000 rpm / min, which is beneficial to control the size of the grains and improve the structural uniformity and consistency of the cathode material precursor.

[0086] In some embodiments of this application, the rate of alkaline solution introduction during the nucleation reaction is controlled so that the pH value of the mixed slurry is 10.0±0.3, which is beneficial to improve the purity of the product obtained during the nucleation process and obtain precursor crystals with good crystal structure; the pH of the mixed slurry can be dynamically and accurately monitored by using a high-precision pH meter.

[0087] In some embodiments of this application, when the salt anion in the salt solution does not contain CO3... 2- Or HCO3 - At that time, in order to prevent dissolved carbon dioxide in the water from being converted into CO3 during the nucleation process, 2-Or HCO3 - To remove dissolved carbon dioxide from the solids in the mixed slurry, the prepared salt and alkali solutions are heated to boiling and maintained for a period of time, such as 1 hour, 2 hours, or more, to avoid CO3. 2- The formation of non-target products due to its high intercalation preference. Preferably, compressed air (PSA) or oxygen is simultaneously introduced into the solution to ensure oxygen saturation in the mixed solution. Simultaneously, the anions of the salt in the salt solution do not contain CO3. 2- Or HCO3 - To avoid introducing unnecessary impurities, it is specifically pointed out that Na2CO3 should not be used as an alkali source to ensure the purity and controllability of the precursor structure.

[0088] In some embodiments of this application, the nucleation reaction temperature is 0–100°C.

[0089] After the salt solution and alkali solution have been introduced, the crystallization treatment stage begins. During the crystallization stage, in order to further oxidize the cations in the slurry, it must still be carried out under oxygen-containing conditions. Preferably, the dissolved oxygen saturation in the mixed slurry is controlled at 20% to 100% during crystallization, which can be obtained by continuously introducing oxygen or compressed air.

[0090] In some embodiments of this application, the crystallization treatment is carried out under a second stirring condition. Preferably, under the second stirring condition, the stirring speed is 200 to 2000 rpm / min, which is beneficial to the sufficiency of grain growth.

[0091] In some embodiments of this application, the crystallization temperature is 0 to 120°C, specifically 0°C, 5°C, 10°C, 20°C, 30°C, 40°C, 50°C, 60°C, 70°C, 80°C, 90°C, 100°C, 110°C, 115°C, 120°C, etc., but is not limited thereto.

[0092] In some embodiments of this application, the crystallization treatment time is 0 to 48 hours (excluding 0 hours), specifically 1 hour, 3 hours, 5 hours, 10 hours, 15 hours, 2 hours, 25 hours, 30 hours, 35 hours, 40 hours, 45 hours, 48 ​​hours, etc., but is not limited to these. The crystallization time can affect the coordination numbers N1 and N2 of the first and second coordination shells in the layered structure. By using different crystallization times, cathode material precursors with different coordination numbers can be obtained.

[0093] In some embodiments of this application, the crystallization process is carried out under a second stirring condition, wherein the stirring speed under the second stirring condition is 200 to 2000 rpm / min, so as to provide sufficient shear force, ensure uniform mixing, and be more conducive to the formation of precursor grains.

[0094] The crystallized slurry obtained after crystallization treatment is washed with water, dehydrated, crushed and demagnetized to obtain the cathode material precursor.

[0095] In some embodiments of this application, the crystallized slurry is repeatedly washed with water and filtered by pressure until the pH of the supernatant is 7, to ensure that Na + K + Mg 2+ Removal of cationic impurities.

[0096] In some embodiments of this application, after washing with water, the crystallized slurry undergoes interlayer ion exchange to obtain a cathode material precursor with corresponding anion intercalation. Specific methods for interlayer ion exchange can be selected from existing technologies, and will not be described in detail here.

[0097] Through interlayer ion exchange, the method for preparing the cathode material precursor of this application endows the interlayer anions with high selectivity and tunability.

[0098] According to another typical embodiment of this application, a positive electrode material is provided, which is prepared from any of the above-mentioned positive electrode material precursors, or prepared from a positive electrode material precursor prepared by any of the above-mentioned methods for preparing positive electrode material precursors.

[0099] Since the XRD patterns of the aforementioned cathode material precursors exhibit (003) and (006) peaks, and the 2θ value of the (006) peak is twice that of the (003) peak, the inventors, through extensive research, have demonstrated that when the cathode material precursor meets these characteristics, the conversion process from the precursor to the cathode material is a topological transformation. This topological transformation process exhibits lower ion migration resistance and faster reaction kinetics, thereby effectively reducing the difficulty of converting the precursor into the cathode material. Furthermore, the cathode material prepared through topological transformation possesses superior overall performance, especially in terms of cycle life and rate capability.

[0100] According to another typical embodiment of this application, a battery is provided, such as Figure 1 As shown, the battery includes a positive electrode 001, a negative electrode 003, and a separator 002, wherein the positive electrode 001 contains the aforementioned positive electrode material. Due to the use of the aforementioned positive electrode material, the battery of this application has advantages such as high capacity, high initial efficiency, long cycle life, excellent rate performance, and low expansion. The battery can be a lithium-ion battery, a sodium-ion battery, a solid-state battery, or a semi-solid-state battery, etc., and is not limited thereto.

[0101] In some embodiments of this application, the battery may be a stacked structure, formed by alternating layers of a positive electrode 001, a separator 002, and a negative electrode 003. In other embodiments, the battery may also be a wound structure, formed by winding a positive electrode 001, a separator 002, and a negative electrode 003 after they have been stacked in sequence.

[0102] In some embodiments of this application, the positive electrode sheet 001 includes a positive current collector and a positive active layer disposed on at least one surface of the positive current collector, wherein the positive active layer contains the positive active material as described above.

[0103] In some embodiments of this application, the positive current collector can be aluminum foil or nickel foil, or any composite current collector disclosed in the prior art, such as, but not limited to, the current collector formed by combining the aforementioned conductive foil (aluminum foil or nickel foil, etc.) and the polymer substrate.

[0104] The separator 002 includes a membrane layer with a porous structure, and its material includes, but is not limited to, at least one of polyethylene, polypropylene, polyvinylidene fluoride, polyethylene terephthalate, polyimide, or aramid. For example, the separator 002 may be a polypropylene porous membrane, a polyethylene porous membrane, a polypropylene nonwoven fabric, a polyethylene nonwoven fabric, or a polypropylene-polyethylene-polypropylene porous composite membrane, etc.

[0105] In some embodiments of this application, the negative electrode sheet 003 includes a negative electrode current collector and a negative electrode active material layer disposed on at least one surface of the negative electrode current collector. In some embodiments of this application, the negative electrode current collector can be at least one of copper foil, nickel foil, stainless steel foil, titanium foil, or carbon-based current collector, or any composite current collector disclosed in the prior art, such as, but not limited to, current collectors formed by combining the aforementioned conductive foil and polymer substrate. The negative electrode active material layer includes a negative electrode material, which may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, and lithium titanate, etc. Silicon-based materials may be selected from at least one of elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. Tin-based materials may be selected from at least one of elemental tin, tin oxide compounds, and tin alloys. However, this application is not limited to these materials, and other conventional materials that can be used as battery negative electrode active materials may also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0106] The beneficial effects that this application can achieve will be further illustrated below with reference to embodiments and comparative examples.

[0107] Example 1

[0108] 1) Ni(NO3)2, Co(NO3)2, and Mn(NO3)2 are dissolved in deionized water in a molar ratio of 0.8:0.1:0.1 to obtain solution I. Solution I is dispersed using a vibrating ultrasonic device, and the total concentration of cations in solution I is 1 mol / L. NaOH is dissolved in deionized water to form solution II with a concentration of 1 mol / L.

[0109] 2) Heat solution I and solution II to boiling and maintain for 2 hours, while simultaneously introducing oxygen into solution I and solution II to ensure that the oxygen content in the mixed solution is saturated.

[0110] 3) Solution I and Solution II were simultaneously added to 100 mL of oxygen-saturated deionized water in an oxygen-rich environment to obtain mixed slurry III. During the addition of solutions I and II, the stirring speed was 600 rpm / min, the synthesis temperature was 80℃, the flow rate of solution I was 30 mL / min, and the pH of mixed slurry III was dynamically and accurately monitored using a high-precision pH meter. The flow rate of solution II was dynamically adjusted according to the pH value of the solution to maintain the pH range of the mixed slurry at 10.0 ± 0.3.

[0111] 4) Crystallize the mixed slurry III at a stirring speed of 50 mL / min and a crystallization temperature of 80℃ for 12 hours, while simultaneously adjusting the oxygen flow rate to 100 mL / min and monitoring the oxygen concentration in the reaction vessel in real time to ensure that the oxygen concentration in the solution is greater than 50%, thus ensuring the presence of Co. 2+ With Mn 2+ Complete oxidation; during the crystallization process, the viscosity of the mixed slurry gradually increases, and the stirring speed needs to be adjusted step by step to 800 rpm / min (increase by 50 rpm / min every half hour for the first 2 hours, and keep it at 800 rpm / min) to ensure that the stirring device can provide sufficient shear force and ensure uniform mixing.

[0112] 5) After crystallization, the resulting mixed slurry is washed with water and filtered under pressure until the pH of the supernatant is 7, to ensure Na + K + Mg 2+ After removing soluble cationic impurities, the product is dried to obtain semi-finished product IV;

[0113] 6) The semi-finished product IV is crushed, sieved, batch-mixed, and demagnetized to obtain the positive electrode material precursor.

[0114] The XRD pattern of the cathode material precursor is as follows: Figure 2 As shown, from Figure 2As can be seen from the XRD pattern, the cathode material precursor prepared in this embodiment has two diffraction peaks at low angles (0°-40°), corresponding to the (003) and (006) crystal planes respectively, and two characteristic diffraction peaks (110) and (113) at high angles (55°-65°).

[0115] Example 2

[0116] The difference from Example 1 is that the crystallization time in step 4) is 24 hours.

[0117] Example 3

[0118] The difference from Example 1 is that the crystallization time in step 4) is 36 hours.

[0119] Example 4

[0120] The difference from Example 1 is that the crystallization time in step 4) is 48 hours.

[0121] Example 5

[0122] The difference from Example 1 is that the crystallization temperature in step 4) is 40°C.

[0123] Example 6

[0124] The difference from Example 1 is that the crystallization temperature in step 4) is 60°C.

[0125] Example 7

[0126] The difference from Example 1 is that the crystallization temperature in step 4) is 100°C.

[0127] Example 8

[0128] The difference from Example 1 is that the following treatment is added between steps 5) and 6): 100g of the semi-finished product is placed in a 1mol / L Na2CO3 aqueous solution and stirred for 12h to perform interlayer ion exchange.

[0129] Example 9

[0130] The difference from Example 1 is that the following treatment is added between step 5) and step 6): 100g of the semi-finished product is placed in a 1mol / L H3PO4 aqueous solution and stirred for 12h to perform interlayer ion exchange.

[0131] Example 10

[0132] The difference from Example 1 is that the following treatment is added between step 5) and step 6): 100g of the semi-finished product is placed in a 1mol / L HBr aqueous solution and stirred for 12h to perform interlayer ion exchange.

[0133] Example 11

[0134] The difference from Example 1 is that, in steps 3) and 4), compressed air is introduced into the deionized water, and the dissolved oxygen saturation of the deionized water is 30%.

[0135] Example 12

[0136] The difference from Example 1 is that, in steps 3) and 4), the dissolved oxygen saturation in the deionized water is 60%.

[0137] Example 13

[0138] The difference from Example 1 is that, in steps 3) and 4), the dissolved oxygen saturation in the deionized water is 80%.

[0139] Example 14

[0140] The difference from Example 1 is that in step 1), Mn(NO3)2 is replaced with the same molar amount of Fe2(SO4)3.

[0141] Example 15

[0142] The difference from Example 1 is that in step 1), Mn(NO3)2 is replaced with the same molar amount of AlCl3.

[0143] Example 16

[0144] The difference from Example 1 is that in step 1), Mn(NO3)2 is replaced with the same molar amount of TiCl4.

[0145] Example 17

[0146] The difference from Example 1 is that in step 1), Co(NO3)2 was not added to solution I, and the molar ratio and concentration of Ni(NO3)2 and Mn(NO3)2 remained unchanged.

[0147] Example 18

[0148] The difference from Example 1 is that in step 1), the molar ratio of Ni(NO3)2, Co(NO3)2, and Mn(NO3)2 is 0.6:0.2:0.2.

[0149] Example 19

[0150] The difference from Example 1 is that, in step 1), the molar ratio of Ni(NO3)2, Co(NO3)2, and Mn(NO3)2 is 0.5:0.2:0.3.

[0151] Comparative Example 1

[0152] Ni(NO3)2, Co(NO3)2, and Mn(NO3)2 were dissolved in deionized water with a complexing agent (tartaric acid) in a molar ratio of 0.8:0.1:0.1 to obtain a mixed solution of metal salts, wherein the concentration of the complexing agent was 10% of the concentration of Ni.

[0153] A precipitate was obtained by adding a mixed solution of metal salts and NaOH precipitant into a reaction vessel. The reaction atmosphere was nitrogen, the temperature was 80℃, the pH value was 10, the stirring speed was 600 rpm / min, and the reaction time was 12 h.

[0154] The precipitate was washed, dried, crushed, and sieved to obtain the cathode material precursor Ni. 0.80 Co 0.1 Mn 0.1 (OH)2.

[0155] XRD tests were performed on the cathode material precursor, and the test results are as follows: Figure 3 As shown in the figure, it can be seen that the precursor of the cathode material does not have (003) and (006) crystal plane diffraction, but only (001) crystal plane diffraction at about 20°, indicating that it is a monoclinic crystal structure.

[0156] The cathode material precursors of the above embodiments and comparative examples were tested according to the following methods, and the test results are listed in Tables 1 and 2.

[0157] Crystal form determination: Take a certain mass of cathode material precursor and perform XRD characterization. The XRD pattern of cathode material precursor shows significant (003) and (006) characteristic peaks. Among them, the 2θ value corresponding to the (003) peak ranges from 1° to 14°, and the 2θ value of the (006) peak is twice the 2θ value of the (003) peak, ranging from 2° to 28°.

[0158] Characterization of water of crystallization: A certain mass of cathode material precursor was taken and thermogravimetric-differential thermal analysis (TG-DTA) was performed under a nitrogen atmosphere. The weight loss m1 in the first weight loss stage (30 to 200℃) was the release of water molecules adsorbed on the LDH plates and between the layers. The amount of water of crystallization m was obtained by calculating m1 / 18.

[0159] Metal molar mass characterization: A certain mass of positive electrode material precursor was dissolved in aqua regia (concentrated nitric acid: concentrated hydrochloric acid = 3:1) and ultrasonically treated for 10 min. After the sample was completely dissolved, the solution was characterized by inductively coupled plasma atomic emission spectrometry (ICP) to obtain the mass of each metal. The molar mass and relative content x, y, z of each metal were obtained by dividing them by their respective relative atomic masses.

[0160] Characterization of valence states of metallic elements and charge on the plates: A certain mass of cathode material precursor was taken for XPS analysis. After the sample powder was pressed into a pellet, it was fixed to the sample stage with double-sided tape or conductive adhesive. After sample preparation, it was placed in the sample injection chamber and evacuated until the vacuum degree reached 1×10⁻⁶. -2 Below Pa, the sample was introduced into the analysis chamber to begin detection. XPS testing was performed using an X-ray photoelectron spectroscopy (ThermoFischer, ESCALAB 250Xi) instrument. The vacuum level in the analysis chamber was 8 × 10⁻⁶. -10The excitation source was Al ka rays (hv = 1486.6 eV), the operating voltage was 12.5 kV, the filament current was 16 mA, and the signal was accumulated in approximately 3 to 10 cycles. The work function of the XPS test instrument was selected as 4.85 eV, the passing energy was 30 eV, and the step size was 0.1 eV. Peak splitting method: Using Origin 8.5 software, select XPS test data → Line mode plotting → Baseline removal (Analysis window Peaks and baseline → Peak Analyzer → Opening Dialog → Recalculate, select Manual option, Goal option, select Fit Peaks (Pro) → Click Next → Baseline Mode option, select Constant, Constant = Minimum → Click Next) → Peak splitting (Click Next → Uncheck Enable AutoFind, check Smoothing Window Size option in Peak Finding Settings, select Positive in Direction option, select 2nd Derivative (Search Hidden peaks) in Method, select None in Smooth Derivative Method, select By Number in Peak Filtration Method, uncheck the Auto option for Number of Peaks, and change the number of peaks to 3 → Click Find → Click Next) → Fit correction (Select No Weighting in Weight Method, select Max. Number of in Fit Control) Set Iterations to 20 and Tolerance to 1E-6 → Click Fit → Click Finish. Once completed, the peak subdivision report will display the relevant results for each peak: peak positions P1, P2, P3; full width at half maximum (FWHM1, FWHM2, FWHM3); and peak areas Area1, Area2, Area3, thus revealing the valence state of the metal element and the charge on the plates.

[0161] Characterization of metal element coordination numbers: A certain mass of cathode material precursor was subjected to synchrotron radiation fine structure absorption spectroscopy (XAFS). The obtained spectrum was Fourier transformed to obtain its R-space test spectrum. The structural parameters of the model were corrected using the Monte Carlo method. During this process, the least squares method was used as the evaluation criterion, and the parameters were continuously iterated to optimize them until the agreement between the theoretical spectrum and the experimental spectrum was sufficiently high. When this standard was reached, the obtained structural model could be considered to match the actual situation. Finally, the metal-oxygen bond coordination number (N1) and its bond length (R1), and the metal-metal bond coordination number (N2) and its bond length (R2) of the sample were obtained.

[0162] Specific surface area characterization: A certain mass of the cathode material precursor is placed in a degassing station and subjected to high-temperature degassing under a vacuum or inert gas atmosphere to remove impurities and moisture adsorbed on the sample surface. The degassed sample is then transferred to a gas adsorption analyzer, and an inert gas (such as nitrogen) is introduced at a set temperature (usually liquid nitrogen temperature). The amount of gas adsorbed by the sample under different pressures is measured. The adsorption data at different pressures are recorded, adsorption isotherms are plotted, and fitted according to the BET equation to finally obtain the specific surface area of ​​the sample.

[0163] Compacted density characterization: A certain mass m of the positive electrode material precursor is placed in a tablet press, a certain pressure is applied, and after holding the pressure for a period of time, it is taken out to obtain a compacted sample sheet. The thickness L of the compacted sample sheet and the thickness L1 of the current collector are measured using a thickness gauge. The surface density ρ is calculated using the surface density calculation formula ρ=m / S (where S is the area of ​​the sample sheet). The compacted density (PD) of the sample is then calculated using the compacted density calculation formula D=ρ / (L–L1).

[0164] Tap density characterization: Take a certain mass m of the cathode material precursor and record its mass m. Carefully load the weighed powder sample into the container of the tap density tester, taking care to avoid excessive pressure or impact during the loading process to prevent affecting the accuracy of the test results. Following the operating procedures of the test instrument, start the vibration device to vibrate the powder sample in the container for a certain time and frequency. During vibration, the powder particles will gradually fill the gaps in the container, forming a denser packing. After vibration, use the measuring device of the tap density tester to measure the volume V of the powder sample in the container. Calculate the tap density (TD) of the sample according to the tap density calculation formula ρ = m / V (where ρ is the tap density, m is the sample mass, and V is the volume of the sample after tapping).

[0165] Cell parameter testing method: The measured XRD pattern is refined by XRD. The specific refinement method is as follows: 1. Import the test data, instrument parameters and standard CIF model into the refinement software (such as Fullproof, GSASⅠ / Ⅱ, EXPGUI), limit the refinement range to 15°-89°, and perform background correction. Set the number of coefficients to 8-16; 2. Correct the instrument parameters such as zero point, Gaussian function, Lorentz function and peak shape function to ensure the convergence of function curves; 3. Adjust the cell parameters, surface roughness, particle size, micro-stress and polarization orientation of the sample to obtain reasonable cell parameters; 4. Set the limiting conditions for element content and thermal vibration. The number of atoms participating in the mixing of Li layer and Ni layer is consistent, and the thermal vibration coefficients of transition metal layer and Li layer are consistent. After correction, the accurate elemental content, Li / Ni mixing quantity, and thermal vibration are obtained; 5. Select all parameters for fine-tuning until the parameters are stable, the Rwp value is less than 3%, and the test curve and the fitted curve fit well; 6. Export all parameters, test curves, fitted curves, differences, and CIF models.

[0166] Table 1

[0167]

[0168]

[0169] Table 2

[0170]

[0171]

[0172] The cathode material precursors of the above embodiments and comparative examples were prepared into cathode materials, and their electrochemical performance was tested. The specific methods are as follows.

[0173] The cathode material precursor was mixed uniformly with a lithium source (molar ratio of 1:1.02) and an additive ZrO2 accounting for 0.1 wt% of the total amount to obtain mixture I; the mixing conditions were: mixing speed 300 rpm / min, mixing time 30 min. Mixture I was calcined at 950℃ for 10 h in an oxygen atmosphere to obtain sintered sample II. Sintered sample II was pulverized, sieved, and demagnetized to obtain the cathode material.

[0174] The cathode materials prepared in the above embodiments and comparative examples were subjected to XRD tests. The Li / Ni mixing values ​​were obtained by XRD refinement of the measured XRD patterns. The refinement method was the same as that described in the cell parameter testing method.

[0175] Preparation of positive electrode sheet

[0176] The positive electrode material, conductive agent acetylene black, and binder polyvinylidene fluoride (PVDF) prepared in the examples or comparative examples were dissolved in the solvent N-methylpyrrolidone (NMP) at a weight ratio of 93:5:2. After thorough stirring, a positive electrode slurry was obtained. The positive electrode slurry was coated on aluminum foil, and then dried and pressed to obtain a positive electrode sheet. A lithium metal sheet was used as the negative electrode sheet, a polyethylene film was used as the separator, and a solution of lithium hexafluorophosphate with a concentration of 1 mol / L and a volume ratio of diethyl carbonate and ethylene carbonate of 1:1 was used as the electrolyte to assemble a 2032 coin cell.

[0177] The charge and discharge tests were conducted using the Blue Electric CT2001A test system, with capacity, first efficiency, and rate performance tested within a voltage range of 2.5V to 4.3V.

[0178] The coin cells prepared in the above examples and comparative examples were subjected to cyclic charging and discharging at room temperature (25°C) at a charge-discharge rate of 0.1C and within a charge-discharge range of 2.5V to 4.3V. The initial discharge capacity and initial coulombic efficiency were measured. The ratio of the capacity after 50 cycles to the initial discharge capacity was recorded as the room temperature cycling performance.

[0179] The assembled coin cells were subjected to two cycles of charge-discharge at room temperature (25°C) at a charge-discharge rate of 0.1C and within a charge-discharge range of 2.5V to 4.3V, and then recharged to a full charge of 4.3V. Electrochemical impedance spectroscopy (EIS) was performed using a Shanghai Chenhua CHI600E electrochemical workstation with a test frequency of 100kHz to 10mHz and an amplitude of 5mV to obtain the electrochemical impedance performance.

[0180] Table 3

[0181]

[0182] Based on the data in Tables 1-3, it can be seen that the XRD patterns of the cathode material precursors prepared in Examples 1-19 of this application have (003) peaks and (006) peaks, and the 2θ value of the (006) peak is twice that of the (003) peak. Ni, Co, and M (M specifically refers to Mn, Fe, Al, and Ti) all have high valence states. Compared with the cathode material prepared by the ternary hydroxide (NiCoMn(OH)2) in Comparative Example 1, there are significant improvements in capacity, rate performance, cycle performance, swelling rate, and battery impedance.

[0183] Specifically, the test data from Examples 1-4 show that with the extension of crystallization time, the grain size of the cathode material precursor increases, the specific surface area (BET) decreases, the true density of the material increases, and consequently the compaction density increases. Simultaneously, the lattice defects in the cathode material precursor decrease, and the coordination number increases. Combined with the electrochemical performance tests of the cathode material in Table 3, it can be seen that during the preparation of the cathode material precursor, with the increase of crystallization time, the Li / Ni mixing value of the cathode material prepared from the generated cathode material precursor first decreases and then increases, while the specific capacity first increases and then decreases. Furthermore, combined with the cycle retention rate and expansion rate data, it can be seen that both excessively short and excessively long crystallization times are detrimental to improving the subsequent applications of the prepared cathode material precursor.

[0184] The test data from Examples 1, 5-7 show that, at the macroscopic level, the crystallization temperature mainly affects the specific surface area and compaction density of the cathode material precursor, while at the microscopic level, it mainly affects the coordination number of the cathode material precursor. Combined with the electrochemical performance tests of the cathode materials in Table 3, it can be seen that during the preparation of the cathode material precursor, the overall performance of the corresponding cathode material changes significantly with increasing crystallization temperature; both excessively high and excessively low crystallization temperatures are detrimental to the performance improvement of the subsequently prepared cathode material.

[0185] The test data from Examples 1 and 11-13 show that the oxygen concentration in the solution during the nucleation and crystallization processes has a significant impact on the valence state and cell parameters of each component in the cathode material precursor. With the increase of oxygen concentration during nucleation and crystallization, the valence state of each component in the cathode material precursor increases, the interlayer spacing increases, and the Li... + The intercalation resistance is smaller, and the Li / Ni mixing of the prepared cathode material is reduced. As can be seen from the electrochemical performance test results in Table 3, when the valence state in the cathode material precursor is higher (e.g., in Examples 1 and 13), the prepared cathode material has higher specific capacity and higher capacity retention.

[0186] The test data from Examples 1 and 8-10 show that when different interlayer anions are selected, the cathode materials prepared using the cathode material precursor of this application all have excellent electrochemical performance.

[0187] The test data from Examples 1 and 14-19 show that when different M elements are used or the proportion of ternary materials is changed, the XRD patterns of the cathode material precursors prepared using this application all have (003) peaks and (006) peaks, and the 2θ value of the (006) peak is twice that of the (003) peak. The cathode materials prepared can all achieve relatively excellent electrochemical performance.

[0188] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A cathode material precursor, characterized in that, It includes one or more of the elements Ni, Co, and M, wherein the element M is selected from one or more of the elements Al, Mn, Fe, Ti, and V; In the XRD pattern of the cathode material precursor, the cathode material precursor has a (003) peak and a (006) peak. The 2θ value of the (003) peak is 1° to 14°, the 2θ value of the (006) peak is twice that of the (003) peak, and the 2θ value of the (006) peak is 2° to 28°.

2. The cathode material precursor according to claim 1, characterized in that, The cathode material precursor satisfies at least one of the following characteristics: (1) The unit cell parameters a and c satisfy the following: (2) The unit cell parameters a and c satisfy: c / a ≥ 2.1; (3) The precursor of the cathode material is characterized by synchrotron radiation fine structure absorption spectroscopy to obtain an R-space test spectrum, which includes a first characteristic peak and a second characteristic peak. The first characteristic peak is located on the x-axis of the R-space test spectrum. Between, the second characteristic peak is located on the x-axis of the R-space test spectrum. between; (4) The cathode material precursor includes metal-oxygen bonds and metal-oxygen-metal bridging bonds. The coordination number of the metal-oxygen bonds is N1 and the bond length is R1. The coordination number of the metal-oxygen-metal bridging bonds is N2 and the bond length is R2. 2≤N1≤6. 2≤N²≤6, (5) The interlayer spacing of the cathode material precursor is d, 0.30nm≤d≤2.85nm; (6) The cathode material precursor also includes at least one element selected from Mg, Cr, Ca, Cu, and Zn; (7) The cathode material precursor further includes at least one element selected from Mg, Cr, Ca, Cu and Zn, and the sum of the masses of Mg, Cr, Ca, Cu and Zn elements in the cathode material precursor is 0 to 50% of the sum of the molar amounts of Ni, Co and M elements in the cathode material precursor. (8) The cathode material precursor further includes at least one element selected from Mg, Cr, Ca, Cu and Zn, and the sum of the masses of Mg, Cr, Ca, Cu and Zn elements in the cathode material precursor is 0 to 10% of the sum of the molar amounts of Ni, Co and M elements in the cathode material precursor.

3. The cathode material precursor according to claim 1, characterized in that, The general chemical formula of the cathode material precursor is [Ni x Co y M z (OH)2] e+ ·(A f- ) (e / f) ·mH₂O, where M is one or more of Al, Mn, Fe, Ti, and V, 0≤x≤1, 0≤y≤1, 0≤z≤1, x+y+z=1, 0<e≤3, 1≤f≤5, 0.1≤m≤2, A f- CO3 2- NO3 - SO4 2- F - Cl - ,Br - I - C4~C 16 At least one of the organic acid radicals and porphyrins.

4. The cathode material precursor according to claim 3, characterized in that, The cathode material precursor satisfies at least one of the following characteristics: (1) When M is one or more of Al and Fe, the valence state of Ni is +2.7 to +3.3, the valence state of Co is +2.8 to +3.2, and the valence state of M is +2.7 to +3.3; (2) When M is one or more of Mn, Ti and V, the valence state of Ni is +2 to +3, the valence state of Co is +2.8 to +3.2, and the valence state of M is +3.8 to +4.2; (3) y = 0, element M is Mn; (4)0.1＜e≤2； (5)1≤f≤3； (6) The M element is selected from one or both of Mn and Al.

5. The cathode material precursor according to any one of claims 1 to 4, characterized in that, The cathode material precursor satisfies at least one of the following characteristics: (1) The specific surface area of ​​the cathode material precursor is 8-12 m². 2 / g; (2) The compaction density of the cathode material precursor is 0.5–4.2 g / cm³. 3 ; (3) The tap density of the cathode material precursor is 1-3 g / cm³. 3 ; (4) The grain size of the cathode material precursor is 4 to 8 μm.

6. A method for preparing a cathode material precursor, characterized in that, The steps include the following: The salt solution and the alkaline solution are respectively passed into water containing oxygen molecules, and a nucleation reaction is carried out under the first stirring condition to obtain a mixed slurry. The cations in the salt solution include one or more of Ni, Co and M elements, and the M element is selected from any one or more of Al, Mn, Fe, Ti and V. The mixed slurry is subjected to crystallization treatment under oxygen conditions to obtain crystallized slurry; The crystallized slurry is washed, dehydrated, pulverized, and demagnetized to obtain a cathode material precursor.

7. The method for preparing the cathode material precursor according to claim 6, characterized in that, The preparation method satisfies at least one of the following characteristics: (1) The types of anions in the salt solution include CO32-. 2- NO3 - SO4 2- F - Cl - ,Br - I - C4-C 16 At least one of organic acid radicals and porphyrins; (2) The alkaline solution is a solution formed by mixing at least one of NaOH, Na2CO3, NaHCO3, KOH, KHCO3, K2CO3, urea, ammonium chloride and ammonia water with water; (3) The rate of introduction of the salt solution is 1 mL / min to 1000 mL / min, and the rate of introduction of the alkali solution is 1 mL / min to 1000 mL / min; (4) Pass the salt solution and the alkaline solution into water with a dissolved oxygen saturation of 20% or more, respectively; (5) In the first stirring condition, the stirring speed is 200 to 4000 rpm / min; (6) The temperature of the nucleation reaction is 0 to 100°C; (7) In the nucleation reaction, the pH value of the mixed slurry is 9.7 to 10.3; (8) In the crystallization treatment, the dissolved oxygen saturation in the mixed slurry is 20% to 100%; (9) The crystallization treatment time is 0 to 48 hours; (10) The temperature of the crystallization treatment is 0 to 120°C; (11) The crystallization treatment is carried out under the second stirring condition, wherein the stirring speed is 200 to 2000 rpm / min.

8. The method for preparing the cathode material precursor according to claim 6 or 7, characterized in that, Interlayer ion exchange is performed on the product after water washing.

9. A positive electrode material, characterized in that, It is prepared by the cathode material precursor according to any one of claims 1 to 5, or by the cathode material precursor prepared by the method of preparing cathode material precursor according to any one of claims 6 to 8.

10. A battery, characterized in that, Including the cathode material as described in claim 9.

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