Cathode material precursor, single-crystal cathode material and manufacturing method, lithium-ion battery

Abstract

The present application relates to a cathode material precursor, a single-crystal cathode material, a method for manufacturing, and a lithium-ion battery. The general chemical formula of the single-crystal cathode material is LixNiaCobMncNdO2, wherein 0.98≤x≤1.1, 0.50≤a≤0.98, 0<b≤0.20, 0<c≤0.30, 0≤d≤0.10, and a+b+c+d=1; N comprises at least one of Al, Ti, Zr, Mg, Sr, Ba, Ca, Nb, W, Sb, Ta, Sn, and Y; the standard deviation of the mass content of each of the Ni, Co, and Mn elements in the single-crystal cathode material is ≤0.03; and the lattice strain ε<0.2%. The single-crystal cathode material provided by the present application has a low lattice strain and can reduce the diffusion energy barrier of lithium ions between microcrystals, thereby the material exhibiting a low DCR and excellent rate capability performance; It can also suppress the occurrence of microcracks, thereby improving the material's cycle performance.

Description

Technology Field

[0001] The present application claims priority to a Chinese patent application filed with the National Intellectual Property Administration of China on October 13, 2023, with application number “202311331910.3” and application title “Cathode material precursor, single crystal cathode material and method of manufacturing, lithium-ion battery”, all of which are incorporated herein by reference.

[0002] The present application relates to the field of cathode material technology, and in particular to cathode material precursors, single-crystal cathode materials, manufacturing methods, and lithium-ion batteries. Background Technology

[0003] Lithium-ion cathode materials are primarily classified into lithium iron phosphate and ternary materials. Lithium iron phosphate is suitable for commercial vehicles, low-to-mid-range passenger cars, and energy storage applications due to its superior cost, cycle life, and thermal stability compared to ternary materials. Ternary materials are suitable for mid-to-high-end passenger cars due to their high energy density and excellent low-temperature performance.

[0004] Conventional polycrystalline ternary cathode materials are composed of primary particles (hundreds of nanometers) tightly aggregated into spherical secondary particles (generally with a diameter of >10 μm). During the charge-discharge process, localized stress is prone to occur along grain boundaries along with lattice shrinkage, leading to structural collapse and the formation of microcracks, which in turn causes a rapid decrease in cathode capacity. Single crystallization is a method to improve the cycle performance of ternary materials. Single-crystal ternary materials consist of dispersed primary particles (generally with a diameter of a few microns, and most particles are single-crystal grains with the same orientation), and secondary spherical particles are absent. Since grain boundaries are eliminated, cracking of the cathode material can be suppressed during the charge-discharge process, resulting in excellent stability. However, single-crystal ternary materials also face the following additional problems. Due to the long diffusion path of Li in single-crystal ternary materials, the power transfer of Li is slowed, and in terms of performance, they exhibit high DC internal resistance (DCR) and low rate capability. In addition, while single-crystal grains can suppress grain cracking, phenomena such as crystal plane slip and positional misalignment still occur during the cycling process, leading to the additional generation of microcracks.

[0005] Ternary single-crystal cathode materials are generally manufactured by high-temperature sintering a lithium salt with a precursor compound containing Ni / Co / Mn. During the sintering process, the formation of the cathode material is generally very slow and the growth rate is non-uniform, leading to stress concentration within the formed cathode material; furthermore, due to the limitations of ion diffusion, there are concentration differences in the distribution of elements within the ternary material, resulting in mismatched internal lattice parameters. These factors hinder the transport of lithium ions, increasing the impedance of the cathode material and degrading its rate capability; on the other hand, internal lattice microstress causes the cathode material to crack and pulverize during the cycling process, thereby degrading its cycling performance.

[0006] Therefore, methods to improve the rate capability performance of single-crystal cathode materials, reduce impedance, and further improve cycle performance are still technical challenges that need to be addressed. The problem to be solved

[0007] The purpose of the present application is to provide a cathode material precursor, a single-crystal cathode material, a method for manufacturing, and a lithium-ion battery. The single-crystal cathode material provided by the present application has a low lattice strain, reduces the diffusion energy barrier of lithium ions between fine crystals, and can improve the Li-ion diffusion coefficient, so that the single-crystal cathode material exhibits a low DCR and has excellent rate capability performance; furthermore, it can reduce the occurrence of phenomena such as crystal plane slip and positional misalignment, thereby suppressing the occurrence of microcracks and improving the structural stability of the single-crystal cathode material, thereby further improving the cycle performance of the single-crystal cathode material. means of solving the problem

[0008] In a first aspect, an embodiment of the present application provides a single-crystal cathode material, said single-crystal cathode material having a general chemical formula of Li x Ni a Co b Mn c N d O2, wherein 0.98≤x≤1.1, 0.50≤a≤0.98, 0<b≤0.20, 0<c≤0.30, 0≤d≤0.10, a+b+c+d=1, and N comprises at least one of Al, Ti, Zr, Mg, Sr, Ba, Ca, Nb, W, Sb, Ta, Sn, and Y;

[0009] When observing the single-crystal cathode material with a scanning electron microscope, at 3K magnification, 10 points were randomly selected from the single-crystal cathode material to perform EDS point scanning and test the content of Ni, Co, and Mn; as a result, in the EDS spectrum results of the single-crystal cathode material, the standard deviation of the mass content of each of the Ni, Co, and Mn elements within the single-crystal cathode material is all ≤0.03;

[0010] The lattice strain of the above single-crystal cathode material is ε, and ε < 0.2%.

[0011] In some embodiments, the single-crystal cathode material is SO4 2- Includes, and SO4 2- The content of is δ, where 0 ppm ≤ δ ≤ 800 ppm.

[0012] In some embodiments, the single crystal cathode material contains at least one single crystal grain having the same orientation, and the average grain size of the single crystal grain is 1 μm to 5 μm.

[0013] In some embodiments, the grain size of the single-crystal cathode material is D, and 150 nm < D < 250 nm.

[0014] In some embodiments, the average particle size D of the single-crystal anode material 50 It is 1.5μm to 5μm.

[0015] In some embodiments, the Baxter tap density of the single-crystal cathode material is >1.5 g / cm³ 3 am.

[0016] In some embodiments, the mass content of each of the Ni, Co, and Mn elements in the single-crystal cathode material is ≤0.08.

[0017] In a second aspect, embodiments of the present application provide an anode material precursor, said anode material precursor having the general chemical formula Ni a Co b Mn c N d O e The above, wherein 0.50≤a≤0.98, 0<b≤0.20, 0<c≤0.30, 0≤d≤0.10, a+b+c+d=1, 1≤e≤1.15, and N comprises at least one of Al, Ti, Zr, Mg, Sr, Ba, Ca, Nb, W, Sb, Ta, Sn, and Y;

[0018] The surface area-weighted average particle size D[3,2] of the above-mentioned cathode material precursor is <2.0 μm, and the standard deviation of the mass content of each of the Ni, Co, and Mn elements in the above-mentioned cathode material precursor is ≤0.05.

[0019] In some embodiments, the mass content of each of the Ni, Co, and Mn elements in the cathode material precursor is ≤0.12.

[0020] In some embodiments, the cathode material precursor comprises secondary particles, and the secondary particles comprise a plurality of aggregated primary particles.

[0021] In some embodiments, the cathode material precursor comprises secondary particles, the secondary particles comprise aggregated primary particles, and the primary particles are spherical.

[0022] In some embodiments, the cathode material precursor comprises secondary particles, and the secondary particles comprise aggregated primary particles, and the particle size of the primary particles is 20 nm to 1000 nm.

[0023] In some embodiments, the average particle size D of the anode material precursor 50 It is <3.5μm.

[0024] In some embodiments, the specific surface area of ​​the cathode material precursor is >5m 2 / g is.

[0025] In some embodiments, the Baxter tab density of the cathode material precursor is >1 g / cm³ 3 am.

[0026] In a third aspect, embodiments of the present application provide a method for manufacturing a single-crystal cathode material, which,

[0027] A step of obtaining a cathode material precursor by pyrolyzing a mixed solution containing nickel salt, cobalt salt, and manganese salt after atomizing, wherein the surface area-weighted average particle size D[3,2] of the cathode material precursor is <2.0 μm and the standard deviation of the mass content of each of the Ni, Co, and Mn elements in the cathode material precursor is ≤0.05; and a step of obtaining a single-crystal cathode material by mixing the cathode material precursor with a lithium source and sintering in an oxygen-containing atmosphere, wherein the standard deviation of the mass content of each of the Ni, Co, and Mn elements in the single-crystal cathode material is ≤0.03 and the lattice strain of the single-crystal cathode material is ε and ε < 0.2%.

[0028] In some embodiments, the cathode material precursor is SO4 2- Includes, and the SO4 2- The content of is η, where 0 ppm ≤ η ≤ 1800 ppm.

[0029] In some embodiments, the nickel salt comprises at least one of nickel chloride, nickel sulfate, nickel nitrate, nickel carbonate, nickel oxalate, and nickel acetate.

[0030] In some embodiments, the cobalt salt comprises at least one of cobalt chloride, cobalt oxalate, cobalt carbonate, cobalt sulfate, cobalt nitrate, and cobalt acetate.

[0031] In some embodiments, the manganese salt comprises at least one of manganese chloride, manganese carbonate, manganese sulfate, manganese oxalate, manganese nitrate, and manganese acetate.

[0032] In some embodiments, the molar ratio of Ni, Co, and Mn in the mixed solution is (50 to 98):(0 to 20):(0 to 30), and the content of Co and Mn in the mixed solution is not 0.

[0033] In some embodiments, the total metal concentration in the mixed solution is 200 g / L to 500 g / L.

[0034] In some embodiments, the mixed solution further comprises a dopant containing the element N, wherein N comprises at least one of Al, Ti, Zr, Mg, Sr, Ba, Ca, Nb, W, Sb, Ta, Sn, and Y.

[0035] In some embodiments, the general chemical formula of the cathode material precursor is Ni a Co b Mn c N d O e 0.50≤a≤0.98, 0<b≤0.20, 0<c≤0.30, 0≤d≤0.10, a+b+c+d=1, 1≤e≤1.15, and N includes at least one of Al, Ti, Zr, Mg, Sr, Ba, Ca, Nb, W, Sb, Ta, Sn, and Y.

[0036] In some embodiments, the mass content of each of the Ni, Co, and Mn elements in the cathode material precursor is ≤0.12.

[0037] In some embodiments, the flow rate of the mixed solution is 100 L / h to 900 L / h.

[0038] In some embodiments, the pressure of the atomization treatment is 0.4 MPa to 0.8 MPa.

[0039] In some embodiments, the primary sintering temperature is 500℃ to 850℃.

[0040] In some embodiments, the lithium source comprises at least one of lithium carbonate, lithium hydroxide, lithium acetate, lithium sulfate, lithium chloride, lithium nitrate, and lithium oxalate.

[0041] In some embodiments, the molar ratio of the total of nickel, cobalt, and manganese in the cathode material precursor to the lithium in the lithium source is 0.98 to 1.10.

[0042] In some embodiments, the sintering temperature is 750℃ to 950℃.

[0043] In some embodiments, the sintering time is 10h to 30h.

[0044] In a fourth aspect, an embodiment of the present application provides a lithium-ion battery, said lithium-ion battery comprising a single-crystal cathode material according to the first aspect or a single-crystal cathode material manufactured by a method for manufacturing a single-crystal cathode material according to the third aspect. Effects of the invention

[0045] Compared to prior art, the technical solution of the present application has at least the following beneficial effects.

[0046] In the case of the single-crystal cathode material provided by the present application, when 10 points were randomly selected in the single-crystal cathode material and EDS point scanning was performed to test the content of Ni, Co, and Mn, the standard deviation of the mass content of each of the Ni, Co, and Mn elements in the EDS spectrum results of the single-crystal cathode material was ≤0.03, which means that the distribution uniformity of Ni, Co, and Mn elements within the single-crystal cathode material is excellent, which is advantageous for reducing crystal structure defects in the single-crystal cathode material; the lattice strain ε of the single-crystal cathode material is <0.2%, which can reduce the diffusion energy barrier of lithium ions between fine crystals and improve the Li ion diffusion coefficient, so that the single-crystal cathode material exhibits excellent rate capability performance and low DCR; at the same time, the low lattice strain can suppress the occurrence of microcracks within the single-crystal cathode material, thereby improving the cycle performance of the single-crystal cathode material.

[0047] In the case of the cathode material precursor provided by the present application, the surface area-weighted average particle size D[3,2] of the cathode material precursor is <2.0 μm, which is advantageous for improving the reaction efficiency and mass transfer efficiency of the cathode material precursor during the subsequent cathode material manufacturing process; at the same time, the standard deviation of the mass content of each of the Ni, Co, and Mn elements in the cathode material precursor obtained by the above manufacturing method is ≤0.05, which means that the uniformity of the distribution of Ni, Co, and Mn elements in the cathode material precursor is excellent, and when a cathode material is manufactured using the above cathode material precursor, the uniformity of the distribution of Ni, Co, and Mn elements in the cathode material can be improved, so the cathode material manufactured by the above cathode material precursor has fewer crystal structure defects and lower lattice stress.

[0048] The method for manufacturing a single-crystal cathode material provided by the present application obtains a cathode material precursor by pyrolyzing a mixed solution containing a nickel salt, a cobalt salt, and a manganese salt after atomizing the solution. The surface area-weighted average particle size D[3,2] of the cathode material precursor is <2.0 μm, indicating high reactive activity, which is advantageous for improving the reaction efficiency and mass transfer efficiency between the cathode material precursor and the lithium source during the subsequent high-temperature sintering process; at the same time, the standard deviation of the mass content of each of the Ni, Co, and Mn elements in the cathode material precursor obtained by the above manufacturing method is ≤0.05, which means that the uniformity of the distribution of Ni, Co, and Mn within the cathode material precursor is excellent; furthermore, the standard deviation of the mass content of each of the Ni, Co, and Mn elements in the single-crystal cathode material produced by subsequently sintering the cathode material precursor with a lithium source is ≤0.03, indicating excellent uniformity of the distribution of Ni, Co, and Mn elements within the single-crystal cathode material, which is advantageous for reducing crystal structure defects in the single-crystal cathode material; The lattice strain ε of the single-crystal cathode material is low at <0.2%, which reduces the diffusion energy barrier of lithium ions between fine crystals and improves the Li ion diffusion coefficient, so the single-crystal cathode material exhibits excellent rate capability and low DCR; at the same time, the low lattice strain can suppress the occurrence of microcracks within the single-crystal cathode material, thereby improving the cycle performance of the single-crystal cathode material. Brief explanation of the drawing

[0049] The present application will be described in more detail below with reference to drawings and examples. Figure 1 is an SEM morphology of the cathode material precursor prepared in Example 1 of the present application. Figure 2 is another SEM morphology of the cathode material precursor prepared in Example 1 of the present application. Figure 3 is the EDS spectrum result of the cathode material precursor prepared in Example 1 of the present application. Figure 4 is a Williamsone-Hall analysis fitting graph of the single-crystal cathode material prepared in Example 1 of the present application. Specific details for implementing the invention

[0050] To better understand the technical solution of the present application, embodiments of the present application are described in detail below with reference to the drawings.

[0051] It should be made clear that the described embodiments are only some of the embodiments of this application, not all. All other embodiments obtained by a person skilled in the art without creative effort based on the embodiments of this application are all within the scope of protection of this application.

[0052] The terms used in the embodiments of this application are used solely for the purpose of describing specific embodiments and are not intended to limit this application. The singular forms "a kind," "above," and "corresponding" used in the embodiments of this application and the appended claims are intended to include the plural forms unless the context specifies a different meaning.

[0053] Furthermore, the term “and / or” as used herein is intended merely to describe the association of associated objects and implies that three relationships may exist; for example, “A and / or B” may mean the case where A exists alone, the case where A and B exist simultaneously, or the case where B exists alone. Additionally, in this specification, the symbol “ / ” generally indicates that the preceding and succeeding associated objects are in an “or” relationship.

[0054] In a first aspect, an embodiment of the present application provides a single-crystal cathode material, said single-crystal cathode material having a general chemical formula of Li x Ni a Co b Mn c N dO2, wherein 0.98≤x≤1.1, 0.50≤a≤0.98, 0<b≤0.20, 0<c≤0.30, 0≤d≤0.10, a+b+c+d=1, and N comprises at least one of Al, Ti, Zr, Mg, Sr, Ba, Ca, Nb, W, Sb, Ta, Sn, and Y;

[0055] When observing the single-crystal cathode material with a scanning electron microscope, at 3K magnification, 10 points were randomly selected from the single-crystal cathode material to perform EDS point scanning and test the content of Ni, Co, and Mn; as a result, in the EDS spectrum results of the single-crystal cathode material, the standard deviation of the mass content of each of the Ni, Co, and Mn elements within the single-crystal cathode material is all ≤0.03;

[0056] The lattice strain of the above single-crystal cathode material is ε, and ε < 0.2%.

[0057] In the case of the single-crystal cathode material provided by the present application, when 10 points were randomly selected in the single-crystal cathode material and EDS point scanning was performed to test the content of Ni, Co, and Mn, the standard deviation of the mass content of each of the Ni, Co, and Mn elements in the EDS spectrum results of the single-crystal cathode material was ≤0.03, which means that the distribution uniformity of Ni, Co, and Mn elements within the single-crystal cathode material is excellent, which is advantageous for reducing crystal structure defects in the single-crystal cathode material; the lattice strain ε of the single-crystal cathode material is <0.2%, which can reduce the diffusion energy barrier of lithium ions between fine crystals and improve the Li ion diffusion coefficient, so that the single-crystal cathode material exhibits excellent rate capability performance and low DCR; at the same time, the low lattice strain can suppress the occurrence of microcracks within the single-crystal cathode material, thereby improving the cycle performance of the single-crystal cathode material.

[0058] Specifically, the value of x may be 0.98, 0.99, 1.0, 1.01, 1.03, 1.05, 1.08, 1.09, or 1.1, etc., but is not limited thereto.

[0059] Specifically, the value of a may be 0.50, 0.55, 0.60, 0.63, 0.70, 0.75, 0.80, 0.85, 0.88, 0.90, 0.95, or 0.98, etc.; the value of b may be 0.01, 0.05, 0.08, 0.10, 0.11, 0.13, 0.15, 0.18, or 0.20, etc.; the value of c may be 0.01, 0.05, 0.10, 0.15, 0.18, 0.20, 0.23, 0.27, or 0.30, etc.; The value of d can be 0, 0.01, 0.03, 0.05, 0.06, 0.07, 0.08, 0.09, or 0.10, etc., but is not limited thereto.

[0060] Specifically, the standard deviation of the mass content of each of the Ni, Co, and Mn elements in the single-crystal cathode material may be 0.01, 0.015, 0.02, 0.025, 0.026, 0.028, or 0.03, etc., but is not limited thereto.

[0061] In some embodiments, the mass content range of each of the Ni, Co, and Mn elements in the single crystal cathode material is ≤0.08, specifically 0.01, 0.02, 0.028, 0.03, 0.05, 0.057, 0.06, 0.07, 0.075, or 0.08, etc., and may also be other values ​​within the above range, but are not limited thereto.

[0062] To be understood, the lower the standard deviation and range of the mass content of each of the Ni, Co, and Mn elements in the single-crystal cathode material, the higher the degree of uniformity of the distribution of the Ni, Co, and Mn elements in the single-crystal cathode material. The standard deviation and range of the mass content of each of the Ni, Co, and Mn elements in the single-crystal cathode material of the present application are within the above range, which means that the distribution of the Ni, Co, and Mn elements in the single-crystal cathode material of the present application is uniform, and thus it is advantageous to reduce lattice defects in the single-crystal cathode material, reduce lattice stress, and improve the cycle performance and rate capability performance of the single-crystal cathode material.

[0063] Specifically, the lattice strain of the single-crystal cathode material may be 0.01%, 0.03%, 0.05%, 0.08%, 0.10%, 0.11%, 0.12%, 0.15%, 0.18%, or 0.19%, etc., but is not limited thereto.

[0064] In some embodiments, the single-crystal cathode material further comprises a coating layer, wherein the coating layer comprises a metal oxide or a lithium-ion conductor, and the metal in the metal oxide comprises at least one of Al, Ti, Zr, Y, Nb, Mg, W, B, Ce, Co, and Mn. The coating layer can reduce direct contact between the single-crystal cathode material and the electrolyte, reduce the occurrence of side reactions between the material and the electrolyte, and further improve the electrochemical performance of the single-crystal cathode material.

[0065] In some embodiments, glass SO4 on the surface of the single-crystal anode material 2- The content is 1000 ppm or less, preferably ≤800 ppm. SO4 of single-crystal cathode material 2- The content may specifically be 0 ppm, 5 ppm, 10 ppm, 50 ppm, 100 ppm, 200 ppm, 300 ppm, 400 ppm, 500 ppm, 600 ppm, 700 ppm, 800 ppm, 900 ppm, or 1000 ppm, etc. Free SO4 2-When the content is within the above range, the cathode material exhibits superior rate capability and cycle performance. Since conventional ternary precursor materials use NiSO4, CoSO4, and MnSO4 as raw materials during the manufacturing process, a high content of sulfate radical ions remains in the co-precipitated precursor. Because sulfate radical ions are difficult to decompose, the corresponding cathode material formed by subsequent sintering has a high surface content of sulfate radical ions (generally >1000 ppm). Free sulfate radical ions have a negative impact on the electrochemical performance of the cathode material. Free SO4 on the surface 2- In cases of high content, SO4 2- It combines with Li ions and binds a portion of the Li ions, so the material capacity and rate capability are reduced; furthermore, the glassy SO4 on the surface 2- This also affects the stability of the SEI film.

[0066] Glass SO4 on the surface of single-crystal cathode material 2- Content and glass SO4 on the surface of the cathode material precursor 2- Since the content has very strong dielectric properties, SO4 in the cathode material precursor 2- The higher the content, the more glassy SO4 on the surface of the single-crystal cathode material 2- The content increases. Glassy SO4 on the surface of the cathode material precursor provided by the present application 2- The content is ≤1000 ppm, which is the glassy SO4 on the surface. 2- It is more advantageous for manufacturing cathode materials with a content of ≤800 ppm.

[0067] SO4 in single-crystal cathode material precursor 2- To reduce the content, in some embodiments, the Ni salt, Mn salt, Co salt, and N salt each independently comprise at least one of a chloride salt, nitrate, oxalate, and acetate. Since the nitrates, chlorides, oxalates, and acetates of nickel, cobalt, and manganese decompose very easily under high temperatures and no apparent residues exist, they do not fundamentally affect the performance of the cathode material. SO4 in the metal salt mixed solution2- By controlling the content, even SO4 2- It is also possible to manufacture cathode material precursors with a content close to zero. However, this requires high-purity raw materials, which leads to increased raw material costs. On the other hand, SO4 2- Using Ni, Co, Mn, and N sources in a ternary recycled material containing impurities as metal sources, and SO4 in the metal sources 2- It is more economical to manufacture cathode material precursors by controlling the content.

[0068] In some embodiments, based on the total mass of the Ni, Co, and Mn elements in the metal salt mixed solution, SO4 2- Since the content is ≤800 ppm, the glass SO4 on the surface 2- It is more advantageous for manufacturing single-crystal cathode materials with low content, and further improves the capacity and rate capability performance of single-crystal cathode materials.

[0069] In some embodiments, the single crystal cathode material contains at least one single crystal grain having the same orientation, wherein the average grain size of the single crystal grain is 1 μm to 5 μm, for example, 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, etc.

[0070] The single-crystal particles of the cathode material of the present application contain at least one single crystal grain having the same orientation, and the average particle size of the single particle satisfying the above conditions, as read in an EBSD test, is measured to be 1 to 5 μm. This allows for stable self-high filling while preventing the occurrence of cracks caused by particle extrusion, etc., after the particles reach the densest accumulation. Since the particles have the same orientation, the stress strain of the cathode particles is relieved during the charge-discharge cycle, and cracking of the particles during the cycle can be significantly reduced, thereby greatly improving the structural stability of the cathode particles.

[0071] It should be noted that the grain orientation of the cathode material can be tested at least by electron backscatter diffraction (EBSD), and that 100 single grains having the same orientation are randomly selected, the grain size of each grain is measured, and the arithmetic mean value is taken as the average grain size of the single grains. In the EBSD test, it is possible to determine whether the grain orientation is the same by observing whether the color within a single grain is the same.

[0072] The difference between single-crystal cathode materials and polycrystalline ternary cathode materials (i.e., polycrystalline secondary particles) is that the smallest particles among polycrystalline secondary particles are secondary particles formed by the aggregation of primary particles. On the other hand, in the case of single-crystal cathode materials, the smallest particles are generally micron-grade monomer primary particles. Generally, in addition to EBSD testing methods, it is possible to determine whether the obtained cathode product is a single-crystal material through characterization methods such as scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray diffraction (XRD). For conventional single-crystal cathode materials, SEM is also an important and reliable characterization method, as the appearance of single-crystal particles generally appears as regular or irregular polyhedral shapes with no significant particle aggregation. TEM is an auxiliary secondary characterization method that observes whether the crystal plane orientation of the obtained product is consistent and further characterizes it in combination with Selected Area Electron Diffraction (SAED); all of these methods can be used to determine whether it is a single-crystal cathode material. For convenience of understanding, the single-crystal cathode material of the present application may be understood as a cathode material particle containing at least one single crystal grain having the same orientation, and said single crystal grain having an average particle size of 1 μm to 5 μm.

[0073] To be understood, the single crystal grain of the present application may be a single particle composed of a single primary particle. The single crystal cathode material may also contain a small amount of “secondary pseudo-particles” formed by the adhesion of multiple single particles. “Primary particles” refer to the smallest particle unit recognized when observing the cathode active material with a scanning electron microscope, and “secondary particles” refer to a secondary structure formed by the aggregation of multiple primary particles, exhibiting a relatively round spherical shape. “Secondary pseudo-particles” refer to those formed by the adhesion of multiple single particles, and generally, the particle size of the single particles within the secondary pseudo-particles is generally between 1 µm and 5 µm, and generally, the degree of roundness of the “secondary pseudo-particles” is lower than that of the existing “secondary particles.”

[0074] It should be specifically noted that the "single-crystal cathode material" known to those skilled in the art is not a "single crystal" in the strict sense. Crystallographically, an ideal single crystal refers to a crystal that has a completely identical arrangement and orientation. However, due to limitations in impurities, strain, and crystal defects, ideal single crystals are very rare and very difficult to produce in a laboratory. Therefore, single-crystal cathode materials known in the art are actually more often cathode materials of a "single-crystal-like form," which, unlike polycrystalline materials composed of many primary grains, exhibits large grain sizes similar to single crystals only in terms of size.

[0075] In some embodiments, the grain size of the single-crystal cathode material is D, and 150 nm < D < 250 nm. Specifically, the grain size of the single-crystal cathode material may be 151 nm, 155 nm, 160 nm, 170 nm, 185 nm, 190 nm, 200 nm, 205 nm, 230 nm, or 245 nm, etc., but is not limited thereto. If the grain size of the single-crystal cathode material is less than 150 nm, the cycle stability of the single-crystal cathode material is reduced; if the grain size of the single-crystal cathode material exceeds 250 nm, the capacity and rate capability performance of the single-crystal cathode material are reduced. Controlling the grain size of the single-crystal cathode material within the above range is advantageous for improving the electrochemical performance of the single-crystal cathode material.

[0076] It should be noted that the method for calculating grain size is generally based on the Scherrer formula using half-peak widths. This method is based on the assumption that lattice stress is zero and that diffraction peak broadening is caused entirely by the grain size. However, in reality, lattice stress within a single-crystal cathode material cannot be completely ignored, and since many factors induce stress concentration within the single-crystal cathode material, the grain size calculated using the Scherrer formula has inherent limitations. Since this application separates diffraction peak broadening due to fine crystal size from diffraction peak broadening due to lattice stress through the Williamsone-Hall method, the calculated grain size can better reflect the electrochemical performance of the material.

[0077] In some embodiments, the average particle size D of the single-crystal anode material 50The particle size is 1.5μm to 5μm, and specifically, it may be 1.5μm, 1.8μm, 2μm, 2.5μm, 3μm, 3.5μm, 4μm, 4.5μm, or 5μm, etc., and may also be other values ​​within the above range, but is not limited thereto. Controlling the particle size of the single-crystal cathode material to within the above range is advantageous for improving the structural stability, thermal stability, and long-term cycle stability of the single-crystal cathode material.

[0078] In some embodiments, the Baxter tap density of the single-crystal cathode material is >1.5 g / cm³ 3 is, specifically 1.55 g / cm³ 3 , 1.58g / cm 3 , 1.62g / cm 3 , 1.63g / cm 3 , 1.65g / cm 3 , 1.70g / cm 3 or 1.75 g / cm³ 3 It may be, of course, other values ​​within the above range, and is not limited thereto. When the tap density of the single-crystal cathode material is controlled within the above range, it is advantageous to increase the energy density of the battery manufactured with the single-crystal cathode material.

[0079] In some embodiments, the compressive density of the single-crystal cathode material is >3.0 g / cm³ 3 ..., specifically 3.1 g / cm³ 3 , 3.2g / cm 3 , 3.3g / cm 3 , 3.5g / cm 3 , 3.7g / cm 3 , 3.9g / cm 3 or 4.1 g / cm³ 3 It may be, of course, other values ​​within the above range, and is not limited thereto.

[0080] In a second aspect, embodiments of the present application provide an anode material precursor, said anode material precursor having the general chemical formula Ni a Co b Mnc N d O e The above, wherein 0.50≤a≤0.98, 0<b≤0.20, 0<c≤0.30, 0≤d≤0.10, a+b+c+d=1, 1≤e≤1.15, and N comprises at least one of Al, Ti, Zr, Mg, Sr, Ba, Ca, Nb, W, Sb, Ta, Sn, and Y;

[0081] The surface area-weighted average particle size D[3,2] of the above-mentioned cathode material precursor is <2.0 μm, and the standard deviation of the mass content of each of the Ni, Co, and Mn elements in the above-mentioned cathode material precursor is ≤0.05.

[0082] In the prior art, during the reaction process between a cathode material precursor and a lithium salt, due to limitations in ion diffusion rates and temperature gradients, the crystal growth rates of each micro-region within the material differ, and unit cell parameters differ, leading to the accumulation of lattice stress within the material; this lattice stress increases the diffusion energy barrier of Li ions between each crystal plane / grain boundary, decreases the Li ion diffusion coefficient, and ultimately increases the DCR of the material. Since the cathode material possesses excellent dielectric properties regarding the morphology and structural characteristics of the cathode material precursor, the composition and structure of the cathode material precursor directly influence the performance of the final cathode material. In the case of the cathode material precursor provided by the present application, the surface area-weighted average particle size D[3,2] of the cathode material precursor is <2.0 μm, and since the reaction activity is high, it is advantageous for improving the reaction efficiency and mass transfer efficiency of the cathode material precursor during the subsequent cathode material manufacturing process; At the same time, the standard deviation of the mass content of each of the Ni, Co, and Mn elements in the cathode material precursor obtained by the above manufacturing method is ≤0.05, which means that the uniformity of the distribution of Ni, Co, and Mn elements in the cathode material precursor is excellent. When a cathode material is manufactured using the above cathode material precursor, the uniformity of the distribution of Ni, Co, and Mn elements in the cathode material can be improved, and the cathode material manufactured by the above cathode material precursor has fewer crystal structure defects and lower lattice stress.

[0083] In some embodiments, the cathode material precursor is SO4 2- Includes, and the SO4 2- The content of is η, where 0 ppm ≤ η ≤ 1800 ppm.

[0084] To make it understandable, SO4 on the precursor surface 2- Since it is very difficult to decompose and very difficult to penetrate into the cathode material and dope, the glass SO4 on the surface of the cathode material 2- Content and free SO4 in the precursor 2- Since there may be a certain dielectric constant between the contents, SO4 in the precursor2- The higher the content, the more glassy SO4 on the surface of the ternary cathode material 2- The content increases. Glassy SO4 on the surface of the cathode material precursor provided by the present application 2- Since the content is ≤1800 ppm, the glass SO4 on the surface 2- It is more advantageous for manufacturing cathode materials with a content of ≤800 ppm. SO4 in cathode material precursor 2- To reduce the content, in some embodiments, the Ni salt, Mn salt, Co salt, and N salt each independently contain at least one of a chloride salt, nitrate, oxalate, and acetate, and the use of nickel sulfate, cobalt sulfate, and manganese sulfate is avoided. Since the nitrates, chlorides, oxalates, and acetates of nickel, cobalt, and manganese decompose very easily under high temperatures and no apparent residues exist, they do not fundamentally affect the performance of the cathode material. SO4 in the metal salt mixed solution 2- By controlling the content, even SO4 2- It is also possible to manufacture cathode material precursors with a content close to zero. However, this requires high-purity raw materials, which leads to increased raw material costs. 2- Using Ni, Co, Mn, and N sources in a ternary recycled material containing impurities as metal sources, and SO4 in the metal sources 2- It is more economical to manufacture cathode material precursors by controlling the content.

[0085] In some embodiments, based on the total mass of the Ni, Co, and Mn elements in the metal salt mixed solution, SO4 2- The content is ≤1800 ppm. Specifically, it may be 500 ppm, 800 ppm, 1200 ppm, 1600 ppm, 1700 ppm, or 1800 ppm, etc., but is not limited thereto.

[0086] In industry, the average particle size D is generally used. 50The particle size of the cathode material precursor is characterized using [3,2]. However, since the reaction between the cathode material precursor and the lithium salt is a process related to the contact area, the Sauter average particle size, i.e., the surface area-weighted average particle size D[3,2], is actually more suitable for characterizing the particle size of the cathode material precursor. The larger D[3,2] is, the lower the surface activity of the cathode material precursor and the slower the reaction rate with the lithium salt.

[0087] It should be noted that the surface area-weighted average particle size D[3,2] of the cathode material precursor of the present application can be directly measured by a Malvern 3000 laser particle size analyzer. Specifically, the formula: Calculate as, where y is the particle size; and N d is the number of particles with particle size y.

[0088] Specifically, the surface area-weighted average particle size D[3,2] of the cathode material precursor may be 1.98 μm, 1.95 μm, 1.8 μm, 1.75 μm, 1.64 μm, 1.5 μm, 1.3 μm, 1.2 μm, 1.1 μm, 0.8 μm, 0.9 μm, or 0.5 μm, etc., but is not limited thereto. Since the surface area-weighted average particle size D[3,2] of the cathode material precursor is controlled within the above range, the reaction activity of the cathode material precursor is high, which is advantageous for improving the reaction efficiency and mass transfer efficiency of the cathode material precursor during the subsequent sintering process with a lithium source.

[0089] The standard deviation of the mass content of each of the Ni, Co, and Mn elements in the cathode material precursor may specifically be 0.001, 0.005, 0.009, 0.01, 0.013, 0.02, 0.025, 0.03, 0.036, 0.04, 0.044, 0.045, 0.047, or 0.049, etc., but is not limited thereto.

[0090] In some embodiments, the mass content range of each of the Ni, Co, and Mn elements in the cathode material precursor is ≤0.12, specifically 0.01, 0.015, 0.018, 0.02, 0.029, 0.03, 0.035, 0.048, 0.059, 0.06, 0.08, 0.097, 0.10, 0.105, 0.11, 0.112, 0.115, or 0.119, etc., and of course, other values ​​within the above range may also be used, but are not limited thereto.

[0091] To be understood, the standard deviation and range of the mass content of each of the Ni, Co, and Mn elements in the cathode material can reflect the degree of uniformity of the distribution of Ni, Co, and Mn elements within the cathode material precursor; thus, the lower the standard deviation and range of the mass content of each of the Ni, Co, and Mn elements, the more uniform the distribution of Ni, Co, and Mn elements within the cathode material precursor. At the same time, there is excellent dielectric property between the uniformity of the distribution of Ni, Co, and Mn elements within the cathode material precursor and the uniformity of the distribution of Ni, Co, and Mn elements within the single-crystal cathode material; therefore, the more uniform the distribution of Ni, Co, and Mn elements within the cathode material precursor, the more uniform the distribution of Ni, Co, and Mn elements within the single-crystal cathode material produced from said cathode material precursor becomes.

[0092] Therefore, when the standard deviation and range of the mass content of each of the Ni, Co, and Mn elements in the cathode material precursor are controlled within the above range, it is advantageous to improve the distribution uniformity of Ni, Co, and Mn elements in the single-crystal cathode material, resulting in excellent distribution uniformity of Ni, Co, and Mn elements in the single-crystal cathode material, fewer crystal structure defects in the single-crystal cathode material, and small lattice strain.

[0093] In some embodiments, the cathode material precursor comprises secondary particles, and the secondary particles comprise a plurality of aggregated primary particles.

[0094] In some embodiments, the cathode material precursor comprises secondary particles, the secondary particles comprise aggregated primary particles, and the primary particles are spherical.

[0095] In some embodiments, the cathode material precursor comprises secondary particles, and the secondary particles comprise a plurality of aggregated primary particles, and the particle size of the primary particles is 20 nm to 1000 nm, specifically, may be 20 nm, 50 nm, 80 nm, 100 nm, 150 nm, 200 nm, 500 nm, 800 nm, or 1000 nm, but is not limited to the listed values, and other unlisted values ​​within the value range are also applied. If the particle size of the primary particles exceeds 1000 nm, the reaction activity of the surface of the cathode material precursor is low, the lattice strain of the manufactured single-crystal cathode material is high, and the cycle performance and rate capability performance of the single-crystal cathode material are degraded. If the primary particles are less than 20 nm, the tap density of the cathode material precursor is low, and the tap density of the manufactured single-crystal cathode material is low. When the particle size of the primary particles is controlled within the above range, it is advantageous to improve the cycle performance and rate capability performance of the single-crystal cathode material manufactured from the cathode material precursor.

[0096] In some embodiments, the average particle size D of the anode material precursor 50 ...is <3.5μm, and specifically, it may be 0.5μm, 0.8μm, 1.2μm, 1.5μm, 2μm, 2.5μm, 3μm, 3.2μm, or 3.5μm, etc., and of course, it may be other values ​​within the above range, but is not limited thereto. Particle size D of the cathode material precursor 50 When controlled within the above range, it is advantageous for improving the reaction activity of the cathode material precursor.

[0097] In some embodiments, the specific surface area of ​​the cathode material precursor is ≥5m 2 It is / g, and specifically 5m 2 / g, 6m 2 / g, 8m 2 / g, 10m 2 / g, 12m 2 / g, 15m 2 / g, 20m 2 / g, 25m 2 / g, 50m 2 / g or 100m 2 It may be / g, etc., and of course, other values ​​within the above range, but are not limited thereto. The larger the specific surface area of ​​the cathode material precursor, the higher the reaction activity of the cathode material precursor, which is advantageous for the reaction between the lithium source and the cathode material precursor, and can reduce lattice defects in the single-crystal cathode material manufactured from the cathode material precursor.

[0098] In some embodiments, the Baxter tab density of the cathode material precursor is >1 g / cm³ 3 ..., specifically 1.1 g / cm³ 3 , 1.2g / cm 3 , 1.3g / cm 3 , 1.8g / cm 3 , 2.3g / cm 3 , 2.5g / cm 3 or 3g / cm³ 3 It may be, of course, other values ​​within the above range, and are not limited thereto. When the tap density of the cathode material precursor is controlled within the above range, it is advantageous to improve the tap density of the manufactured single-crystal cathode material to improve the energy density of the battery.

[0099] In a third aspect, an embodiment of the present application provides a method for manufacturing a single-crystal cathode material, comprising the following steps.

[0100] In step S100, a mixed solution containing nickel salt, cobalt salt, and manganese salt is atomized and then pyrolyzed to obtain an anode material precursor, wherein the surface area-weighted average particle size D[3,2] of the anode material precursor is <2.0 μm, and the standard deviation of the mass content of each of the Ni, Co, and Mn elements in the anode material precursor is ≤0.05;

[0101] In step S200, the cathode material precursor is mixed with a lithium source and then sintered in an oxygen-containing atmosphere to obtain a cathode material, wherein the standard deviation of the mass content of each of the Ni, Co, and Mn elements in the single-crystal cathode material is ≤0.03; and the lattice strain of the single-crystal cathode material is ε and ε < 0.2%.

[0102] The method for manufacturing a single-crystal cathode material provided by the present application obtains a cathode material precursor by pyrolyzing a mixed solution containing a nickel salt, a cobalt salt, and a manganese salt after atomizing the solution. The surface area-weighted average particle size D[3,2] of the cathode material precursor is <2.0 μm, indicating high reactive activity, which is advantageous for improving the reaction efficiency and mass transfer efficiency between the cathode material precursor and the lithium source during the subsequent high-temperature sintering process; at the same time, the standard deviation of the mass content of each of the Ni, Co, and Mn elements in the cathode material precursor obtained by the above manufacturing method is ≤0.05, which means that the uniformity of the distribution of Ni, Co, and Mn within the cathode material precursor is excellent; furthermore, the standard deviation of the mass content of each of the Ni, Co, and Mn elements in the single-crystal cathode material produced by subsequently sintering the cathode material precursor with a lithium source is ≤0.03, indicating excellent uniformity of the distribution of Ni, Co, and Mn elements within the single-crystal cathode material, which is advantageous for reducing crystal structure defects in the single-crystal cathode material; The lattice strain ε of the single-crystal cathode material is low at <0.2%, which reduces the diffusion energy barrier of lithium ions between fine crystals and improves the Li ion diffusion coefficient, so the single-crystal cathode material exhibits excellent rate capability and low DCR; at the same time, the low lattice strain can suppress the occurrence of microcracks within the single-crystal cathode material, thereby improving the cycle performance of the single-crystal cathode material.

[0103] In step S100, a mixed solution containing nickel salt, cobalt salt, and manganese salt is atomized and then pyrolyzed to obtain a cathode material precursor, wherein the surface area-weighted average particle size D[3,2] of the cathode material precursor is <2.0 μm, and the standard deviation of the mass content of each of the Ni, Co, and Mn elements in the cathode material precursor is ≤0.05.

[0104] Specifically, the surface area-weighted average particle size D[3,2] of the cathode material precursor may be 1.98 μm, 1.95 μm, 1.8 μm, 1.75 μm, 1.64 μm, 1.5 μm, 1.3 μm, 1.2 μm, 1.1 μm, 0.8 μm, 0.9 μm, or 0.5 μm, etc., but is not limited thereto. Since the surface area-weighted average particle size D[3,2] of the cathode material precursor is controlled within the above range, the reaction activity of the cathode material precursor is high, which is advantageous for improving the reaction efficiency and mass transfer efficiency of the cathode material precursor during the subsequent sintering process with a lithium source. The surface area-weighted average particle size D[3,2] of the precursor is mainly related to the pyrolysis temperature; as the pyrolysis temperature increases, the surface area-weighted average particle size D[3,2] increases and the reaction activity of the precursor decreases.

[0105] The standard deviation of the mass content of each of the Ni, Co, and Mn elements in the cathode material precursor may specifically be 0.001, 0.005, 0.009, 0.01, 0.013, 0.02, 0.025, 0.03, 0.036, 0.01, 0.044, 0.045, 0.047, or 0.049, etc., but is not limited thereto.

[0106] In some embodiments, the nickel salt comprises at least one of nickel chloride, nickel sulfate, nickel nitrate, nickel carbonate, nickel oxalate, and nickel acetate.

[0107] In some embodiments, the cobalt salt comprises at least one of cobalt chloride, cobalt oxalate, cobalt carbonate, cobalt sulfate, cobalt nitrate, and cobalt acetate.

[0108] In some embodiments, the manganese salt comprises at least one of manganese chloride, manganese carbonate, manganese sulfate, manganese oxalate, manganese nitrate, and manganese acetate.

[0109] In some embodiments, the molar ratio of Ni, Co, and Mn in the mixed solution is (50 to 98):(0 to 20):(0 to 30), and the content of Co and Mn in the mixed solution is not 0. Specifically, the molar ratio of Ni, Co, and Mn in the mixed solution may be 50:0.1:0.1, 60:10:30, 65:15:20, 65:5:30, 70:5:25, 70:10:20, 80:5:15, 85:10:5, or 98:1:1, but is not limited thereto.

[0110] In some embodiments, the total metal concentration in the mixed solution is 200 g / L to 500 g / L, specifically 200 g / L, 220 g / L, 260 g / L, 300 g / L, 350 g / L, 400 g / L, 450 g / L, 480 g / L, or 500 g / L, and of course, other values ​​within the above range, but are not limited thereto. The applicant has discovered that the metal concentration in the mixed solution can affect the manufacturing efficiency of the precursor and the degree of the pyrolysis reaction. If the metal concentration in the mixed solution is too high, the precursor reaction may be incomplete, leading to structural instability, and the uniformity of the particle element distribution may not be ideal. Conversely, if the metal concentration in the mixed solution is too low, not only is the manufacturing efficiency low, but when the mixed solution evaporates rapidly at high temperatures, a large number of hollow spherical particles are generated and become brittle, resulting in an imperfect particle size distribution and even the generation of a large amount of fine powder particles that affect material performance, while a relatively small amount of large particles are generated. Large particles are more likely to cause non-uniform elemental distribution and affect the surface area-weighted average particle size D[3,2] of the single-crystal cathode material precursor.

[0111] In some embodiments, the mixed solution further comprises a dopant containing the element N, wherein N comprises at least one of Al, Ti, Zr, Mg, Sr, Ba, Ca, Nb, W, Sb, Ta, Sn, and Y.

[0112] In some embodiments, the ultrasonic stirring step before atomizing the mixed solution is further included, and the ultrasonic stirring step includes the step of placing the mixed solution into a reaction kettle having an ultrasonic stirring function and performing heating and ultrasonic stirring.

[0113] In some embodiments, the ultrasonic stirring temperature is 50°C to 70°C.

[0114] In some embodiments, the ultrasonic frequency of the ultrasonic stirring is 30KHz to 50KHz, and the ultrasonic stirring time is 0.5h to 2h.

[0115] By performing heating and ultrasonic stirring prior to atomization, chemical elements within the mixed solution can be more thoroughly mixed and homogenized, and more uniform spray droplets can be obtained quickly. Consequently, the distribution of elements on the surface of precursor particles during pyrolysis becomes more uniform, and the standard deviation value of the mass content is smaller.

[0116] In some embodiments, a surfactant is added before the atomization treatment of the mixed solution, and the surfactant comprises polyethylene glycol.

[0117] To be understood, when polyethylene glycol is dissolved in water and reaches a certain concentration, the surface tension of the system decreases, the total particle size of the cathode material precursor particles decreases, and at the same time, the elemental distribution becomes more uniform, and the surface area-weighted average particle size D[3,2] of the single-crystal cathode material precursor decreases.

[0118] In some embodiments, the surfactant accounts for 0.5% to 5% of the total mass of the mixed solution. When the surfactant content is within the above range, precursor particles with a smooth shape, uniformity, and excellent dispersibility can be stably obtained. If the concentration is too low, the role of the surfactant is negligible, and if it is too high, not only does it affect the overall concentration of the mixture, but Ni, Co, and Mn metal ions may also precipitate.

[0119] In some embodiments, the following ultrasonic stirring step is further included prior to the atomization treatment of the mixed solution. The mixed solution is placed in a reaction kettle equipped with an ultrasonic stirring function and heated to 50°C to 70°C while simultaneously adjusting the ultrasonic frequency of the ultrasonic stirring to 30 to 50 kHz. After ultrasonic stirring in the reaction kettle for 0.5 to 2 hours, the heating function is turned off, polyethylene glycol corresponding to 0.5% to 5% of the total mass of the mixed solution is added, and ultrasonic stirring is performed for 0.5 to 1 hour. In some embodiments, the general chemical formula of the cathode material precursor is Ni a Co b Mn c N d O e 0.50≤a≤0.98, 0<b≤0.20, 0<c≤0.30, 0≤d≤0.10, a+b+c+d=1, 1≤e≤1.15, and N includes at least one of Al, Ti, Zr, Mg, Sr, Ba, Ca, Nb, W, Sb, Ta, Sn, and Y.

[0120] In some embodiments, the mass content range of each of the Ni, Co, and Mn elements in the cathode material precursor is ≤0.12, specifically 0.01, 0.015, 0.018, 0.02, 0.029, 0.03, 0.035, 0.048, 0.059, 0.06, 0.08, 0.097, 0.10, 0.105, 0.11, 0.112, 0.115, or 0.119, etc., and of course, other values ​​within the above range may also be used, but are not limited thereto.

[0121] To be understood, the standard deviation and range of the mass content of each of the Ni, Co, and Mn elements in the cathode material can reflect the degree of uniformity of the distribution of Ni, Co, and Mn elements within the cathode material precursor; thus, the lower the standard deviation and range of the mass content of each of the Ni, Co, and Mn elements, the more uniform the distribution of Ni, Co, and Mn elements within the cathode material precursor. At the same time, there is excellent dielectric property between the distribution uniformity of Ni, Co, and Mn elements within the cathode material precursor and the distribution uniformity of Ni, Co, and Mn elements within the single-crystal cathode material; therefore, the more uniform the distribution of Ni, Co, and Mn elements within the cathode material precursor, the more uniform the distribution of Ni, Co, and Mn elements within the single-crystal cathode material produced from said cathode material precursor becomes.

[0122] When the standard deviation and range of the mass content of each of the Ni, Co, and Mn elements in the cathode material precursor are controlled within the above range, it is advantageous to improve the distribution uniformity of Ni, Co, and Mn elements in the single-crystal cathode material, resulting in excellent distribution uniformity of Ni, Co, and Mn elements in the single-crystal cathode material, fewer crystal structure defects in the single-crystal cathode material, and small lattice strain.

[0123] In some embodiments, the flow rate of the mixed solution is 100 L / h to 900 L / h, and specifically, it may be 100 L / h, 200 L / h, 300 L / h, 400 L / h, 500 L / h, 600 L / h, 700 L / h, 800 L / h, or 900 L / h, etc., but is not limited thereto. As the flow rate of the mixed solution increases, the synthesis rate of the precursor increases, but the uniformity of the Ni / Co / Mn distribution decreases. If the flow rate is less than 100 L / h, the synthesis efficiency of the precursor is low and the manufacturing cost is high; if the flow rate of the mixed solution is higher than 900 L / h, the standard deviation and range of the mass content of each of the Ni, Co, and Mn elements in the precursor increase significantly, the distribution uniformity of Ni, Co, and Mn elements in the manufactured single-crystal cathode material decreases and the lattice strain increases.

[0124] In some embodiments, the pressure of the atomization treatment is 0.4 MPa to 0.8 MPa, and specifically, it may be 0.4 MPa, 0.5 MPa, 0.6 MPa, 0.7 MPa, 0.75 MPa, or 0.8 MPa, etc., and of course, it may be other values ​​within the above range, but is not limited thereto.

[0125] In some embodiments, the pyrolysis temperature is 500°C to 850°C, specifically 500°C, 550°C, 600°C, 650°C, 700°C, 750°C, or 800°C, but is not limited to the listed values, and other unlisted values ​​within the above value range may also be applied. As the pyrolysis temperature increases, the surface area-weighted average particle size D[3,2] of the cathode material precursor decreases, and the activity of the precursor decreases. When the pyrolysis temperature exceeds 850°C, the surface area-weighted average particle size D[3,2] of the cathode material precursor exceeds 2.0 μm; at this time, the reaction activity of the cathode material precursor is low, so the subsequently manufactured single-crystal cathode material has many defects and the lattice strain ε exceeds 0.2%, so the single-crystal cathode material exhibits low rate capability, high DCR, and low cycle performance. Therefore, appropriately lowering the thermal decomposition temperature of the precursor is advantageous for enhancing the reaction activity of the precursor and improving the rate capability and DCR of the cathode material. However, if the thermal decomposition temperature is below 500℃, the decomposition of metal salts of Ni, Co, and Mn is incomplete, resulting in Cl in the precursor - , NO3 - , CO3 2- The content of iso-anions becomes too high, and in the subsequent manufacturing process of the cathode material, these residual anions inhibit single crystal formation and corrode the sintering furnace.

[0126] In step S200, the cathode material precursor is mixed with a lithium source and then sintered in an oxygen-containing atmosphere to obtain a cathode material, wherein the standard deviation of the mass content of each of the Ni, Co, and Mn elements in the single-crystal cathode material is ≤0.03; and the lattice strain of the single-crystal cathode material is ε and ε < 0.2%.

[0127] In some embodiments, the lithium source comprises at least one of lithium carbonate, lithium hydroxide, lithium acetate, lithium sulfate, lithium chloride, lithium nitrate, and lithium oxalate.

[0128] In some embodiments, the molar ratio of the total of nickel, cobalt, and manganese in the cathode material precursor to the lithium in the lithium source is 0.98 to 1.10, specifically 0.98, 0.99, 1.01, 1.03, 1.05, 1.06, 1.08, 1.09, or 1.10, and of course, other values ​​within the above range may also be used, but are not limited thereto.

[0129] In some embodiments, the sintering reaction temperature is 750°C to 950°C, specifically 750°C, 760°C, 780°C, 800°C, 850°C, 900°C, 920°C, or 950°C, and of course, other values ​​within the above range, but are not limited thereto. The sintering temperature is closely related to the Ni content, so the higher the Ni content, the lower the sintering temperature; furthermore, an appropriate sintering temperature is advantageous for improving the electrochemical performance of the single-crystal cathode material by reducing crystal structure defects and decreasing lattice strain.

[0130] In some embodiments, the sintering reaction time is 10h to 30h, specifically 10h, 12h, 15h, 16h, 18h, 20h, 24h, 28h, or 30h, and of course, other values ​​within the above range, but are not limited thereto.

[0131] In a fourth aspect, an embodiment of the present application provides a lithium-ion battery, said lithium-ion battery comprising a single-crystal cathode material according to the first aspect or a cathode material manufactured by a method for manufacturing a single-crystal cathode material according to the third aspect.

[0132] The beneficial effects of the present invention will be explained in more detail below based on examples and comparative examples.

[0133] Example 1

[0134] (1) Molar ratio (n Ni :n Co :n MnNickel chloride, cobalt chloride, and manganese chloride are weighed according to =0.67:0.05:0.28 and added to water to prepare a mixed solution; after controlling the total metal concentration in the mixed solution to 300 g / L, the mixed solution is placed in a reaction kettle equipped with an ultrasonic stirring function and heated to 60°C while simultaneously adjusting the ultrasonic frequency of the stirring to 33 kHz; after ultrasonic stirring in the reaction kettle for 1 hour, the heating function is turned off, polyethylene glycol equivalent to 1% of the total mass of the mixed solution is added, and ultrasonic stirring is performed for 0.5 hours; based on the total mass of Ni, Co, and Mn elements, SO4 2- The content is 900 ppm.

[0135] (2) After atomizing the above mixed solution into droplets, it was pyrolyzed in a 650°C roasting furnace in an air atmosphere; the flow rate of the mixed solution was controlled to 200 L / h and the atomization pressure was controlled to 0.6 MPa.

[0136] (3) The pyrolysis product is ground by airflow to produce a cathode material precursor (Ni 0.67 Co 0.05 Mn 0.28 O) obtained.

[0137] (4) Molar ratio (n Ni+Co+Mn :n Li A cathode material precursor was weighed according to the ratio =1:1 and uniformly mixed with lithium carbonate, then heated to 920°C in an oxygen atmosphere and sintered for 20 hours to obtain a single-crystal cathode material.

[0138] The general chemical formula of the single-crystal cathode material prepared in this embodiment is LiNi 0.67 Co 0.05 Mn 0.28 It is O2, and the average particle size D of the single-crystal cathode material. 50 The value is 3.8 μm, and the Baxter tab density is 1.95 g / cm³. 3 am.

[0139] FIG. 1 is an SEM morphology of the cathode material precursor prepared in Example 1 of the present application, and FIG. 2 is another SEM morphology of the cathode material precursor prepared in Example 1 of the present application. As shown in FIG. 1 and FIG. 2, the cathode material precursor includes secondary particles, and the secondary particles include a plurality of aggregated primary particles.

[0140] When observing the cathode material precursor prepared in Example 1 of the present application using a scanning electron microscope, EDS point scanning was performed on 10 randomly selected points within the cathode material precursor at 3K magnification to test the content of Ni, Co, and Mn. As a result, in the EDS spectrum results of the cathode material precursor, as shown in Fig. 3, the range of Ni content in the cathode material precursor was 0.095 with a standard deviation of 0.036; the range of Co content was 0.029 with a standard deviation of 0.009; and the range of Mn content was 0.081 with a standard deviation of 0.030. This indicates that the uniformity of the distribution of Ni, Co, and Mn within the cathode material precursor prepared in Example 1 is excellent. In addition, as a result of detection via ion chromatography, the glass SO4 on the surface of the precursor 2- The content was 504 ppm.

[0141] Figure 4 is a Williamsone-Hall analysis fitting graph of the single-crystal cathode material prepared in Example 1 of the present application, and as shown in Figure 4, a lattice strain of 0.11% of the single-crystal cathode material can be obtained through analysis and calculation of the data in Figure 4. Other performance parameters of the cathode material precursor and the single-crystal cathode material are shown in detail in Tables 1 and 2.

[0142] Example 2

[0143] The difference from Example 1 is that (2) the mixed solution is atomized into droplets and then pyrolyzed in a 750°C roasting furnace in an air atmosphere; the flow rate of the mixed solution is controlled to 200 L / h and the atomization pressure is controlled to 0.6 MPa.

[0144] The general chemical formula of the single-crystal cathode material prepared in this embodiment is LiNi 0.67 Co 0.05 Mn 0.28 It is O2, and the average particle size D of the single-crystal cathode material. 50 The value is 3.7 μm, and the Baxter tab density is 1.85 g / cm³. 3 am.

[0145] Other performance parameters of the cathode material precursor and single-crystal cathode material are shown in detail in Tables 1 and 2.

[0146] Example 3

[0147] The difference from Example 1 is that (2) the mixed solution is atomized into droplets and then pyrolyzed in a 650°C roasting furnace in an air atmosphere; the flow rate of the mixed solution is controlled to 100 L / h and the atomization pressure is controlled to 0.6 MPa.

[0148] The general chemical formula of the single-crystal cathode material prepared in this embodiment is LiNi 0.67 Co 0.05 Mn 0.28 It is O2, and the average particle size D of the single-crystal cathode material. 50 The value is 4.0 μm, and the Baxter tab density is 2.12 g / cm³. 3 am.

[0149] Other performance parameters of the cathode material precursor and single-crystal cathode material are shown in detail in Tables 1 and 2.

[0150] Example 4

[0151] The difference from Example 1 is that (2) the mixed solution is atomized into droplets and then pyrolyzed in a 500°C roasting furnace in an air atmosphere; the flow rate of the mixed solution is controlled to 500 L / h and the atomization pressure is controlled to 0.6 MPa.

[0152] The general chemical formula of the single-crystal cathode material prepared in this embodiment is LiNi 0.67 Co 0.05 Mn 0.28 It is O2, and the average particle size D of the single-crystal cathode material. 50The value is 3.8 μm, and the Baxter tab density is 1.90 g / cm³. 3 am.

[0153] Other performance parameters of the cathode material precursor and single-crystal cathode material are shown in detail in Tables 1 and 2.

[0154] Example 5

[0155] The difference from Example 1 is that (4) the molar ratio (n Ni+Co+Mn :n Li A single-crystal cathode material is obtained by weighing a cathode material precursor according to the ratio of =1:1 and mixing it uniformly with lithium carbonate, then raising the temperature to 950°C in an oxygen atmosphere and sintering it for 20 hours.

[0156] The general chemical formula of the single-crystal cathode material prepared in this embodiment is LiNi 0.67 Co 0.05 Mn 0.28 It is O2, and the average particle size D of the single-crystal cathode material. 50 The value is 4.5 μm, and the Baxter tab density is 2.2 g / cm³. 3 am.

[0157] Other performance parameters of the cathode material precursor and single-crystal cathode material are shown in detail in Tables 1 and 2.

[0158] Example 6

[0159] The difference from Example 1 is that (4) the molar ratio (n Ni+Co+Mn :n Li A single-crystal cathode material is obtained by weighing a cathode material precursor according to the ratio of =1:1 and uniformly mixing it with lithium carbonate, then raising the temperature to 900°C in an oxygen atmosphere and sintering it for 20 hours.

[0160] The general chemical formula of the single-crystal cathode material prepared in this embodiment is LiNi 0.67 Co 0.05 Mn 0.28 It is O2, and the average particle size D of the single-crystal cathode material. 50 The value is 3.0 μm, and the Baxter tab density is 1.68 g / cm³. 3 am.

[0161] Other performance parameters of the cathode material precursor and single-crystal cathode material are shown in detail in Tables 1 and 2.

[0162] Example 7

[0163] (1) Molar ratio (n Ni :n Co :n Mn Nickel chloride, cobalt chloride, and manganese chloride are weighed according to =0.88:0.06:0.04) and added to water to prepare a mixed solution, and the total metal concentration in the mixed solution is controlled to 300 g / L, based on the total mass of Ni, Co, and Mn elements, SO4 2- The content is ≤1780 ppm.

[0164] (2) After atomizing the above mixed solution into droplets, it was pyrolyzed in a 600°C roasting furnace in an air atmosphere; the flow rate of the mixed solution was controlled to 200 L / h and the atomization pressure was controlled to 0.6 MPa.

[0165] (3) The pyrolysis product is ground by airflow to produce a cathode material precursor (Ni 0.88 Co 0.06 Mn 0.04 O) obtained.

[0166] (4) Molar ratio (n Ni+Co+Mn :n Li A cathode material precursor was weighed according to the ratio of 1:1 and uniformly mixed with lithium carbonate, then heated to 850°C in an oxygen atmosphere and sintered for 15 hours to obtain a single-crystal cathode material.

[0167] The general chemical formula of the single-crystal cathode material prepared in this embodiment is LiNi 0.88 Co 0.06 Mn 0.04 It is O2, and the average particle size D of the single-crystal cathode material. 50 The value is 3.2 μm, and the Baxter tab density is 1.77 g / cm³. 3 am.

[0168] Other performance parameters of the cathode material precursor and single-crystal cathode material are shown in detail in Tables 1 and 2.

[0169] Example 8

[0170] (1) Molar ratio (n Ni :n Co :n Mn :n Al Nickel chloride, cobalt chloride, manganese chloride, and aluminum chloride were weighed and added to water to prepare a mixed solution according to =0.88:0.06:0.03:0.03, and the total metal concentration in the mixed solution was controlled to 300 g / L.

[0171] (2) After atomizing the above mixed solution into droplets, it was pyrolyzed in a 600°C roasting furnace in an air atmosphere; the flow rate of the mixed solution was controlled to 200 L / h and the atomization pressure was controlled to 0.6 MPa.

[0172] (3) The pyrolysis product is ground by airflow to produce a cathode material precursor (Ni 0.88 Co 0.06 Mn 0.03 Al 0.03 O) obtained.

[0173] (4) Molar ratio (n Ni+Co+Mn+Al :n Li A cathode material precursor was weighed according to the ratio =1:1 and uniformly mixed with lithium hydroxide, then heated to 850°C in an oxygen atmosphere and sintered for 15 hours to obtain a cathode material.

[0174] The general chemical formula of the single-crystal cathode material prepared in this embodiment is LiNi 0.88 Co 0.06 Mn 0.03 Al 0.03 It is O2, and the average particle size D of the single-crystal cathode material. 50 The value is 3.2 μm, and the Baxter tab density is 1.78 g / cm³. 3 am.

[0175] Other performance parameters of the cathode material precursor and single-crystal cathode material are shown in detail in Tables 1 and 2.

[0176] Example 9

[0177] The difference from Example 1 is that (1) based on the total mass of the elements Ni, Co, and Mn, SO4 2-The content is 200 ppm, and as a result of detection via ion chromatography, the free SO4 on the surface of the precursor prepared in this example 2- The content is 100 ppm. The general chemical formula of the single-crystal cathode material prepared in this example is LiNi 0.67 Co 0.05 Mn 0.28 It is O2, and the average particle size D of the single-crystal cathode material. 50 The value is 3.8 μm, and the Baxter tab density is 1.95 g / cm³. 3 Other performance parameters of the cathode material precursor and single-crystal cathode material are shown in detail in Tables 1 and 2.

[0178] Example 10

[0179] The difference from Example 1 is that (1) molar ratio (n Ni :n Co :n Mn Nickel chloride, cobalt chloride, and manganese chloride are weighed according to =0.67:0.05:0.28 and added to water to prepare a mixed solution, the total metal concentration in the mixed solution is controlled to 500 g / L, and polyethylene glycol equivalent to 5% of the total mass of the mixed solution is added; based on the total mass of the elements Ni, Co, and Mn, SO4 2- The content is 900 ppm.

[0180] The general chemical formula of the single-crystal cathode material prepared in this embodiment is LiNi 0.67 Co 0.05 Mn 0.28 It is O2, and the average particle size D of the single-crystal cathode material. 50 The value is 3.8 μm, and the Baxter tab density is 1.83 g / cm³. 3 Other performance parameters of the cathode material precursor and single-crystal cathode material are shown in detail in Tables 1 and 2.

[0181] Example 11

[0182] The difference from Example 1 is that (1) molar ratio (n Ni :n Co :n MnNickel chloride, cobalt chloride, and manganese chloride were weighed according to =0.67:0.05:0.28 and added to water to prepare a mixed solution; after controlling the total metal concentration in the mixed solution to 200 g / L, the mixed solution was placed in a reaction kettle equipped with an ultrasonic stirring function and heated to 60°C while simultaneously adjusting the ultrasonic stirring frequency to 33 kHz, and ultrasonic stirring was performed in the reaction kettle for 1 hour; based on the total mass of the elements Ni, Co, and Mn, SO4 2- The content is 900 ppm.

[0183] The general chemical formula of the single-crystal cathode material prepared in this embodiment is LiNi 0.67 Co 0.05 Mn 0.28 It is O2, and the average particle size D of the single-crystal cathode material. 50 The value is 4.1 μm, and the Baxter tab density is 1.82 g / cm³. 3 Other performance parameters of the cathode material precursor and single-crystal cathode material are shown in detail in Tables 1 and 2.

[0184] Comparative Example 1

[0185] The difference from Example 1 is that (2) the mixed solution is atomized into droplets and then pyrolyzed in an 880°C roasting furnace in an air atmosphere; the flow rate of the mixed solution is controlled to 200 L / h and the atomization pressure is controlled to 0.6 MPa.

[0186] The general chemical formula of the single-crystal cathode material prepared in this comparative example is LiNi 0.67 Co 0.05 Mn 0.28 It is O2, and the average particle size D of the cathode material 50 The value is 3.82 μm, and the Baxter tab density is 1.86 g / cm³. 3 am.

[0187] Other performance parameters of the cathode material precursor and single-crystal cathode material are shown in detail in Tables 1 and 2.

[0188] Comparative Example 2

[0189] The difference from Example 1 is that (2) the mixed solution is atomized into droplets and then pyrolyzed in a 650°C roasting furnace in an air atmosphere; the flow rate of the mixed solution is controlled to 1000 L / h and the atomization pressure is controlled to 0.6 MPa.

[0190] The general chemical formula of the single-crystal cathode material prepared in this comparative example is LiNi 0.67 Co 0.05 Mn 0.28 It is O2, and the average particle size D of the single-crystal cathode material. 50 The value is 3.72 μm, and the Baxter tab density is 1.90 g / cm³. 3 am.

[0191] Other performance parameters of the cathode material precursor and single-crystal cathode material are shown in detail in Tables 1 and 2.

[0192] Comparative Example 3

[0193] The difference from Example 1 is that (4) the molar ratio (n Ni+Co+Mn :n Li A cathode material precursor was weighed according to the ratio of =1:1 and uniformly mixed with lithium carbonate, then heated to 700°C in an oxygen atmosphere and sintered for 20 hours to obtain a cathode material.

[0194] The cathode material prepared in this comparative example is a polycrystalline cathode material, and its general chemical formula is LiNi 0.67 Co 0.05 Mn 0.28 It is O2, and the average particle size D of the polycrystalline cathode material. 50 The value is 3.2 μm, and the Baxter tab density is 1.8 g / cm³. 3 am.

[0195] Other performance parameters of the cathode material precursor and single-crystal cathode material are shown in detail in Tables 1 and 2.

[0196] Comparative Example 4

[0197] Ni prepared in Example 2 of CN113488642A 0.88 Co 0.06 Mn 0.03 Al 0.03(OH)24 precursor and the corresponding cathode material were referenced.

[0198] (1) Preparation of the first solution: nickel sulfate hexahydrate, manganese sulfate monohydrate, and cobalt sulfate heptahydrate were weighed according to the molar ratio of nickel:cobalt:manganese = 0.88:0.06:0.03, dissolved in deionized water, and a transition metal salt solution with a mass concentration of 2 mol / L was prepared and referred to as the first solution;

[0199] (2) Preparation of the second solution: Weigh aluminum nitrate hydrate and dissolve it in deionized water, then add concentrated ammonia water with a mass concentration of 25% dropwise to the aluminum salt solution and continue stirring, stop adding the concentrated ammonia water when pH = 8 to 9, and finally adjust the volume to a constant level so that the aluminum hydroxide concentration is 0.11 mol / L and refer to this as the second solution;

[0200] (3) Preparation of quaternary transition metal hydroxide precursor: Ammonia water bottom solution was added to the reaction kettle in advance, the temperature of the reaction system was controlled to 55°C, and the stirring paddle speed was adjusted to 1000 rpm. The first solution was added to the reaction kettle at a rate of 35 L / h using the No. 1 metering pump, the second solution was added to the reaction kettle at a rate of 20 L / h using the No. 2 metering pump, and an ammonia water solution was added using the No. 3 metering pump to maintain the ammonia water concentration in the system at 0.5 mol / L. After adding a 4 mol / L sodium hydroxide solution using the No. 4 metering pump, the pH of the reaction system was controlled to 10.0 ± 0.5. The feed reaction was continued for 17 hours, and after aging for 10 hours, the final precipitated product was filtered and washed, dried in an oven at 110°C for 12 hours, and then ground and sieved to Ni 0.88 Co 0.06 Mn 0.03 Al 0.03 (OH)2 hydroxide precursor was obtained.

[0201] (4) A hydroxide precursor and lithium hydroxide were uniformly mixed in a molar ratio of 1:1.05, sintered at 500°C for 3 hours under an oxygen atmosphere, then sintered at 850°C for 15 hours, and after cooling, the product was D 50 LiNi, a single-crystal cathode material, is ground and sieved until it reaches 12μm. 0.88 Co 0.06 Mn 0.03 Al 0.03 I got O2.

[0202] Other performance parameters of the cathode material precursor and single-crystal cathode material are shown in detail in Tables 1 and 2.

[0203] Comparative Example 5

[0204] Referring to CN116230922A, Ni 0.8 Co 0.1 Mn 0.1 (OH)2 precursors and corresponding cathode materials were manufactured.

[0205] (1) NiSO4, CoSO4, and MnSO4 were mixed according to a molar ratio of 0.8:0.1:0.1 of Ni / Co / Mn to prepare a solution.

[0206] (2) Add the above solution to a reactor at 55°C, and NaOH and NH 3· Ni 0.8 Co 0.1 A Mn0.1(OH)2 precursor was obtained.

[0207] (3) The above precursor was dried at 80°C for 12 hours, and then dried again at 110°C for 12 hours.

[0208] (4) The above precursor and lithium hydroxide were added to a dry high-speed mixer in a molar ratio of 1:1.05 and mixed for 5 minutes.

[0209] (5) The temperature was raised to 950°C at a heating rate of 2°C / min and maintained at 950°C for 5 hours, then naturally cooled to 900°C and maintained for 5 hours. During the heating and holding period, oxygen was continuously passed through at a flow rate of 10 mL / min. After calcination was completed, the sample was naturally cooled to room temperature, ground, and classified to obtain the single-crystal cathode material LiNi 0.8 Co 0.1 Mn 0.1 O2 was manufactured.

[0210] Other performance parameters of the cathode material precursor and single-crystal cathode material are shown in detail in Tables 1 and 2.

[0211] Comparative Example 6

[0212] The difference from Example 1 is that (1) based on the total mass of the elements Ni, Co, and Mn, SO4 2- The content is 2000 ppm.

[0213] Glass SO4 on the surface of the precursor prepared in this example 2- The content is 1200 ppm. The general chemical formula of the single-crystal cathode material prepared in this example is LiNi 0.67 Co 0.05 Mn 0.28 It is O2, and the average particle size D of the single-crystal cathode material. 50 The value is 3.8 μm, and the Baxter tab density is 1.95 g / cm³. 3 Other performance parameters of the cathode material precursor and single-crystal cathode material are shown in detail in Tables 1 and 2.

[0214] Test method:

[0215] (1) Under 3K magnification, an energy dispersive X-ray spectrometer (EDS) attached to a scanning electron microscope is used to randomly select 10 points on the surface of an untreated cathode material precursor or a single-crystal cathode material to scan and test the Ni, Co, and Mn content of the cathode material precursor or the single-crystal cathode material, and the standard deviation and range of the mass content of each of the Ni, Co, and Mn elements are statistically analyzed to characterize the uniformity of the distribution of Ni, Co, and Mn elements.

[0216] (2) The surface area-weighted average particle size D[3,2] of the cathode material precursor is tested using a 3000 laser particle size analyzer.

[0217] (3) The lattice strain and grain size of the single-crystal cathode material are calculated from XRD data through Williamsone-Hall analysis.

[0218] The specific method is as follows. Measurements are taken using a Japanese Rigaku X-ray diffractometer under specific conditions of 0.75 degrees / min, a step length of 0.02, and continuous scanning between 10 and 90 degrees within the 2θ range. 4sinθ hkl Let be the horizontal coordinate, and β hkl cosθ hkl A graph is plotted using as the vertical coordinate and fitted linearly, and the strain ε and grain size D can be calculated through the slope and intercept. In particular, the half-peak width β used in the fitting hkl The influence of the device must be eliminated, that is, β hkl =β 총 -β 기기 However, here β 총 is the actual tested half-peak width value, and β 기기 ε is the half-peak width expansion caused by the device, and this value can be calculated by testing the XRD of a standard silicon wafer. β of the test device used in this application 기기is 0.000103. In addition, by selecting and fitting data from 7 strong diffraction peaks (003), (101), (102), (104), (015), (107), and (113), the linear fitting accuracy is improved and actual test error is reduced.

[0219]

[0220] Here, β is the half-peak width, θ is the diffraction angle, and all units are in radians; k is a constant 0.89; λ is the X-ray wavelength 0.154 nm, and D is the grain size, and the unit is nm. ε is the dimensionless lattice strain.

[0221] (4) After weighing a certain amount of sample using Baxter tapping, test the tap density by vibrating it 3000 times at 300 times / min.

[0222] (5) Electrochemical performance test:

[0223] The electrochemical performance of the material is evaluated using a button-type half cell, and the specific method is as follows. A single-crystal cathode material, conductive carbon black, and PVDF are weighed in a mass ratio of 93:5:2, and N-methyl-2-pyrrolidone (NMP) is added according to a solid content of 50%. A viscous slurry is prepared using a high-speed disperser, uniformly applied onto aluminum foil with a scraper, dried in an oven at 80°C, and then rolled and cut into a 14mm diameter cathode plate. A 16mm lithium plate is used as the anode plate, Celgard polypropylene film is used as the separator, and a LiPF6 carbonate solution with a concentration of 1 mol / L is used as the electrolyte. The components are assembled in a glove box filled with argon to obtain a button-type half cell. Capacity and cycle performance tests are performed at 25°C and 3.0–4.3V using a LAND cell test system, wherein the nominal capacity 1C is set to 200mAh / g. Specifically, in the capacity test, electrical performance tests (charge / discharge voltage 3.0–4.3V, temperature condition 25℃) were conducted using a Blue Battery Test System. With 0.1C charging and 0.1C discharging, the constant voltage cutoff current was measured at 0.005C, and the 0.1C capacity was obtained. With 0.5C charging and 1C discharging performed for one week, the constant voltage cutoff current was measured at 0.05C, and the resulting capacity was the 1C capacity. Cycling test: Under conditions of 25℃ and charge / discharge voltages of 3.0–4.3V, charging and discharging at 0.5C / 1C was performed for 50 weeks, and the final capacity retention rate over 50 weeks represents the cycling performance. Additionally, the voltage UA at the beginning of the weekly discharge, the voltage data UB at 60 seconds, and the discharge current IDis were recorded. The formula for calculating the DC internal resistance is DCR=(U A -U B ) / I Dis am.

[0224] (6) SO4 2- Content Test:

[0225] 0.5 g was taken and dissolved in 50 ml of water, filtered using ultrasound for 5 minutes, and then the SO4 of the filtrate was analyzed using ion chromatography (Thermo Fisher Ion Chromatography ICS6000 HPIC). 2- Measures the ion content.

[0226] (7) Electron Backscatter Diffraction (EBSD) Test:

[0227] First, the cathode material sample is embedded in a carbon paint (PELCO) graphite block, and then the cross-section of the block is polished with an argon ion beam. Electron backscatter diffraction (EBSD) imaging is performed using a JEOL JSM-7000F scanning electron microscope. The step length of the EBSD map is set to 250 nm (each pixel is 250 nm × 250 nm).

[0228] Refer to Tables 1 to 3 for the above test results.

[0229] Results of performance parameters of the cathode material precursors prepared in each example and comparative example Cathode material precursor SO4 2- Content / ppm D[3,2] / μm Range of mass contents of each of the Ni, Co, and Mn elements Standard deviation of the mass content of each of the elements Ni, Co, and Mn Ni Co Mn Ni Co Mn Example 1 504 1.5 0.095 0.029 0.081 0.036 0.009 0.030 Example 2 505 1.9 0.095 0.029 0.081 0.036 0.009 0.030 Example 3 500 1.9 0.078 0.025 0.062 0.018 0.007 0.016 Example 4 502 1.5 0.115 0.052 0.102 0.049 0.020 0.042 Example 5 504 1.5 0.095 0.029 0.081 0.036 0.009 0.030 Example 6 504 1.5 0.095 0.029 0.081 0.036 0.009 0.030 Example 7 950 1.5 0.095 0.030 0.090 0.036 0.010 0.029 Example 8 950 1.5 0.090 0.029 0.080 0.035 0.009 0.028 Example 9 100 1.5 0.095 0.029 0.081 0.036 0.009 0.030 Example 10 503 1.6 0.115 0.066 0.163 0.049 0.027 0.047 Example 11 502 1.9 0.105 0.067 0.087 0.041 0.028 0.033 Comparative Example 1 504 2.5 0.095 0.029 0.081 0.036 0.009 0.030 Comparative Example 2 510 1.5 0.150 0.085 0.120 0.060 0.042 0.050 Comparative Example 3 504 1.5 0.095 0.029 0.081 0.036 0.009 0.030 Comparative Example 4 3000 9.2 0.160 0.010 0.120 0.080 0.062 0.075 Comparative Example 5 5000 3.5 0.130 0.090 0.150 0.072 0.060 0.085 Comparative Example 6 1200 1.5 0.095 0.029 0.081 0.036 0.009 0.030

[0230] Results of performance parameters of single-crystal cathode materials prepared in each example and comparative example cathode material SO4 2- Content / ppm Lattice strain ε Grain size / nm Range of mass contents of each of the Ni, Co, and Mn elements Standard deviation of the mass content of each of the elements Ni, Co, and Mn Whether or not it contains single grains with the same orientation Average grain size of a single crystal grain / μm Ni Co Mn Ni Co Mn Example 1 495 0.11% 196 0.050 0.023 0.053 0.015 0.007 0.015 yes 2.1 Example 2 495 0.17% 192 0.050 0.023 0.053 0.015 0.007 0.015 yes 2.0 Example 3 490 0.15% 192 0.042 0.020 0.032 0.012 0.006 0.013 yes 2.0 Example 4 494 0.18% 192 0.078 0.048 0.069 0.028 0.012 0.024 yes 2.2 Example 5 475 0.09% 249 0.040 0.018 0.035 0.010 0.005 0.011 yes 4.0 Example 6 500 0.19% 151 0.068 0.030 0.062 0.025 0.010 0.020 yes 1.2 Example 7 935 0.17% 198 0.066 0.026 0.076 0.024 0.011 0.021 yes 3.0 Example 8 940 0.16% 196 0.065 0.025 0.070 0.022 0.010 0.020 yes 1.8 Example 9 85 0.11% 205 0.050 0.023 0.053 0.015 0.007 0.015 yes 2.1 Example 10 494 0.19% 197 0.078 0.034 0.073 0.029 0.015 0.027 yes 2.1 Example 11 492 0.19% 197 0.069 0.036 0.077 0.028 0.018 0.023 yes 3.2 Comparative Example 1 500 0.25% 185 0.050 0.023 0.053 0.015 0.007 0.015 yes 1.9 Comparative Example 2 502 0.30% 196 0.090 0.062 0.082 0.036 0.020 0.032 yes 2.1 Comparative Example 3 503 0.23% 120 0.075 0.025 0.065 0.029 0.008 0.026 no / Comparative Example 4 2700 0.42% 185 0.105 0.080 0.090 0.050 0.032 0.043 yes 2.1 Comparative Example 5 4500 0.35% 196 0.090 0.060 0.100 0.035 0.020 0.042 yes 2.1 Comparative Example 6 1100 0.11% 196 0.050 0.023 0.053 0.015 0.007 0.015 yes 2.0

[0231] Electrochemical performance test results of the single-crystal cathode materials prepared in each example and comparative example 0.1C Capacity (mAh / g) 1C Capacity (mAh / g) Ratio of 1C capacity to 0.1C capacity Dose reduction rate after 50 1C cycles DCR(mΩ) Example 1 185.5 165.2 89.1% 4.5% 20.5 Example 2 185.5 162.0 87.5% 7.5% 27.0 Example 3 185.1 163.2 88.2% 6.0% 25.2 Example 4 185.2 161.2 87.0% 7.8% 28.2 Example 5 185.5 163.7 88.2% 4.2% 25.5 Example 6 185.3 164.0 88.5% 6.5% 21.9 Example 7 219.2 194.9 88.9% 6.0% 21.8 Example 8 217.8 194.0 89.1% 5.2% 21.2 Example 9 185.6 166.1 89.5% 4.2% 18.5 Example 10 185.2 163.8 88.4% 6.6% 26.8 Example 11 185.8 163.7 88.1% 6.5% 27.0 Comparative Example 1 185.5 161.0 86.8% 8.0% 29.4 Comparative Example 2 185.5 160.2 86.4% 8.5% 30.1 Comparative Example 3 186.9 167.2 89.2% 20.1% 18.5 Comparative Example 4 217.6 186.0 85.5% 10.0% 32.2 Comparative Example 5 210.8 185.0 86.1% 9.0% 31.9 Comparative Example 6 185.0 164.0 88.6% 5.5% 25.2

[0232] According to the test data in Tables 1 to 3, for the single-crystal cathode materials prepared in Examples 1 to 8, the standard deviation of the mass content of each of the Ni, Co, and Mn elements in the single-crystal cathode material is ≤0.03, and the range of the mass content of each of the Ni, Co, and Mn elements is ≤0.08, which means that the uniformity of the distribution of Ni, Co, and Mn elements within the single-crystal cathode material is excellent, which is advantageous for reducing crystal structure defects in the single-crystal cathode material; the lattice strain ε of the single-crystal cathode material is <0.2%, which can reduce the diffusion energy barrier of lithium ions between fine crystals and improve the Li ion diffusion coefficient, so that the single-crystal cathode material exhibits excellent rate capability performance and low DCR; at the same time, the low lattice strain can suppress the occurrence of microcracks within the single-crystal cathode material, thereby improving the cycle performance of the single-crystal cathode material.

[0233] According to the data in Tables 1 and 2, there is excellent dielectric strength between the uniformity of distribution of Ni, Co, and Mn elements in the cathode material precursor and the uniformity of distribution of Ni, Co, and Mn elements in the single crystal cathode material. As the range and standard deviation of the mass content of each of Ni, Co, and Mn elements in the cathode material precursor become smaller, the range and standard deviation of the mass content of each of Ni, Co, and Mn elements in the single crystal cathode material become smaller; furthermore, it can be seen that the range and standard deviation of the Ni, Co, and Mn content in the single crystal cathode material are always smaller than those of the precursor. This is because high-temperature sintering is required during the manufacturing process of the single crystal cathode material, and additional diffusion of metal ions improves the uniformity of distribution of Ni, Co, and Mn elements.

[0234] According to the test data in Tables 1 to 3, it can be seen that the overall performance of the single-crystal cathode material manufactured in Example 1 is the best.

[0235] Comparing Example 1 and Example 2, the single-crystal cathode material of Example 1 exhibits superior rate capability, low impedance, and high cycle performance. This is because the thermal decomposition temperature of the atomized mixed solution is appropriate when preparing the cathode material precursor in Example 1, resulting in a low surface area-weighted average particle size D[3,2] of the cathode material precursor and high reaction activity of the cathode material precursor, which reduces crystal structure defects in the single-crystal cathode material and lowers the lattice strain of the single-crystal cathode material. Therefore, the single-crystal cathode material prepared in Example 1 exhibits superior rate capability, lower impedance, and superior cycle performance.

[0236] Compared to Example 1, in Example 5, the sintering temperature increases to some extent during the process of sintering the cathode material precursor and the lithium source, the range and standard deviation of the mass content of each of the Ni, Co, and Mn elements in the single-crystal cathode material are lower, and the lattice strain ε of the single-crystal cathode material decreases to some extent, so the cycle performance is improved to some extent. However, since the grain size of the single-crystal cathode material is significantly larger and the Li ion diffusion path becomes longer, the rate capability performance of the single-crystal cathode material prepared in Example 5 is lower to some extent compared to Example 1.

[0237] Compared to Example 1, in Example 6, during the process of sintering the cathode material precursor and the lithium source, the sintering temperature is reduced to some extent, so the grain size of the single-crystal cathode material becomes smaller and the lattice strain ε increases to some extent, so the cycle stability of the single-crystal cathode material of Example 6 is lower to some extent compared to the single-crystal cathode material of Example 1.

[0238] Compared to Example 1, the precursor and cathode material of Example 9 are glass SO4 2- The reduced content exhibits superior rate capability and cycle performance.

[0239] Compared to Example 1, in Example 10, ultrasonic stirring is not performed before atomizing the single-crystal cathode precursor mixture solution, and the range and standard deviation of the mass content of each of the Ni, Co, and Mn elements in the single-crystal cathode precursor are higher, which affects the cycle and internal resistance.

[0240] Compared to Example 1, in Example 11, polyethylene glycol is added before atomizing the single-crystal cathode precursor mixture solution and ultrasonic stirring is not performed, and the surface area-weighted average particle size D[3,2] of the single-crystal cathode material is large, and there is a possibility that large aggregated particles will appear, and the range and standard deviation of the mass content of each of the Ni, Co, and Mn elements in the single-crystal cathode precursor are higher, which affects the cycle and internal resistance.

[0241] Compared to Example 1, the cathode material of Comparative Example 6 is glass SO4 2- It exceeds 1000 ppm. Excess SO4 2- This results in a decrease in material capacity, rate limit, and cycle performance.

[0242] Compared to Example 1, in Comparative Example 1, the thermal decomposition temperature was increased during the manufacturing process of the cathode material precursor, so the surface area-weighted average particle size D[3,2] of the cathode material precursor exceeded 2.0 μm; and the reaction activity of the cathode material precursor was low, so the subsequently manufactured single-crystal cathode material had many defects and the lattice strain ε exceeded 0.2%, so the single-crystal cathode material exhibited low rate capability performance, high DCR, and low cycle performance.

[0243] Compared to Example 1, in Comparative Example 2, the atomization flow rate is increased during the manufacturing process of the cathode material precursor, and the standard deviation and range of the mass content of each of the Ni, Co, and Mn elements in the manufactured cathode material precursor are significantly increased, which reduces the uniformity of the distribution of Ni, Co, and Mn elements in the manufactured single-crystal cathode material, increases the lattice strain, and the lattice strain ε exceeds 0.2%, so the single-crystal cathode material manufactured in Comparative Example 2 has reduced rate capability and cycle performance.

[0244] Compared to Example 1, in Comparative Example 3, the sintering temperature is too low during the process of sintering the cathode material precursor and the lithium source, and the obtained cathode material has a polycrystalline structure. The grain size of the cathode material is less than 150 nm and has excellent rate capability performance; however, the lattice strain exceeds 0.2%, making it prone to cracking and pulverization during the cycling process, and the structural stability of the cathode material is reduced, resulting in a significant reduction in the cycle capacity of the cathode material.

[0245] Compared to Example 1, the standard deviation and range of the mass content of each of the Ni, Co, and Mn elements in the cathode material precursor of Comparative Example 4 are significantly larger than those of Example 1, so the lattice strain of the manufactured single-crystal cathode material increases significantly, and the rate capability and cycle performance of the single-crystal cathode material are significantly reduced as the lattice strain exceeds 0.2%.

[0246] Likewise, in the case of the single-crystal cathode material prepared in Comparative Example 5, the surface area-weighted average particle size D[3,2] of the cathode material precursor is too large, and the standard deviation and range of the mass content of each of the Ni, Co, and Mn elements in the cathode material precursor are significantly larger than those of Example 1, so the lattice strain of the prepared single-crystal cathode material increases significantly, and the rate capability and cycle performance of the cathode material are significantly reduced as the lattice strain exceeds 0.2%.

[0247] The above description is merely a preferred embodiment of the present application and is not intended to limit the present application. All modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present application should be included within the scope of protection of the present application.

Claims

Claim 1 As a single-crystal cathode material, the general chemical formula of the single-crystal cathode material is Li x Ni a Co b Mn c N d O2, wherein 0.98≤x≤1.1, 0.50≤a≤0.98, 0<b≤0.20, 0<c≤0.30, 0≤d≤0.10, a+b+c+d=1, and N comprises at least one of Al, Ti, Zr, Mg, Sr, Ba, Ca, Nb, W, Sb, Ta, Sn, and Y; when observing the single-crystal cathode material with a scanning electron microscope, at 3K magnification, 10 points are randomly selected from the single-crystal cathode material to perform EDS point scanning to test the content of Ni, Co, and Mn, and as a result, in the EDS spectrum results of the single-crystal cathode material, the standard deviation of the mass content of each of the Ni, Co, and Mn elements in the single-crystal cathode material is ≤0.03; and the lattice strain of the single-crystal cathode material is ε, and 0.11% ≤ε<0.2%, characterized as a single-crystal cathode material. Claim 2 In claim 1, the single crystal anode material comprises: (1) the grain size of the single crystal anode material is D, 150 nm < D < 250 nm; and (2) the average particle size D of the single crystal anode material. 50 The thickness is 1.5μm to 5μm; (3) the Baxter tap density of the single crystal cathode material is >1.5g / cm³ 3 A single crystal cathode material characterized by satisfying at least one of the following features: (4) the mass content range of each of the Ni, Co and Mn elements in the single crystal cathode material is ≤0.

08. Claim 3 As an anode material precursor for manufacturing the single-crystal anode material of claim 1 or 2, the general chemical formula of the anode material precursor is Ni a Co b Mn c N d O e A cathode material precursor characterized in that 0.50≤a≤0.98, 0<b≤0.20, 0<c≤0.30, 0≤d≤0.10, a+b+c+d=1, 1≤e≤1.15, and N includes at least one of Al, Ti, Zr, Mg, Sr, Ba, Ca, Nb, W, Sb, Ta, Sn, and Y; the surface area-weighted average particle size D[3,2] of the cathode material precursor is <2.0μm, and the standard deviation of the mass content of each of the Ni, Co, and Mn elements in the cathode material precursor is ≤0.

05. Claim 4 In paragraph 3, the cathode material precursor comprises: (1) the mass content range of each of the Ni, Co, and Mn elements in the cathode material precursor is ≤0.12; (2) the cathode material precursor includes secondary particles, and the secondary particles include agglomerated primary particles; (3) the cathode material precursor includes secondary particles, and the secondary particles include agglomerated primary particles, and the primary particles are spherical; (4) the cathode material precursor includes secondary particles, and the secondary particles include agglomerated primary particles, and the particle size of the primary particles is 20 nm to 1000 nm; and (5) the average particle size D of the cathode material precursor 50 is <3.5 μm; (6) the specific surface area of ​​the cathode material precursor is >5 m 2 / g; (7) The Baxter tab density of the above cathode material precursor is >1g / cm³ 3 A cathode material precursor characterized by satisfying at least one of the technical features. Claim 5 A method for manufacturing a single-crystal cathode material according to claim 1 or 2, comprising the steps of: obtaining a cathode material precursor by pyrolyzing a mixed solution containing a nickel salt, a cobalt salt, and a manganese salt after atomizing the solution, wherein the surface area-weighted average particle size D[3,2] of the cathode material precursor is <2.0 μm and the standard deviation of the mass content of each of the Ni, Co, and Mn elements in the cathode material precursor is ≤0.05; and obtaining a single-crystal cathode material by mixing the cathode material precursor with a lithium source and sintering it in an oxygen-containing atmosphere, wherein the standard deviation of the mass content of each of the Ni, Co, and Mn elements in the single-crystal cathode material is ≤0.03; and wherein the lattice strain of the single-crystal cathode material is ε and ε < 0.2%. Claim 6 In claim 5, the manufacturing method comprises: (1) the nickel salt comprises at least one of nickel chloride, nickel sulfate, nickel nitrate, nickel carbonate, nickel oxalate, and nickel acetate; (2) the cobalt salt comprises at least one of cobalt chloride, cobalt oxalate, cobalt carbonate, cobalt sulfate, cobalt nitrate, and cobalt acetate; (3) the manganese salt comprises at least one of manganese chloride, manganese carbonate, manganese sulfate, manganese oxalate, manganese nitrate, and manganese acetate; (4) the molar ratio of Ni, Co, and Mn in the mixed solution is (50~98):(0~20):(0~30), and the content of Co and Mn in the mixed solution is not 0; (5) the total metal concentration in the mixed solution is 200 g / L~500 g / L; and (6) the mixed solution further comprises a dopant containing the element N, wherein N is Al, A manufacturing method characterized by satisfying at least one of the following features: including at least one of Ti, Zr, Mg, Sr, Ba, Ca, Nb, W, Sb, Ta, Sn, and Y. Claim 7 In claim 6, the above-mentioned cathode material precursor is, (1) the general chemical formula of the above-mentioned cathode material precursor is Ni a Co b Mn c N d O e (1) wherein 0.50≤a≤0.98, 0<b≤0.20, 0<c≤0.30, 0≤d≤0.10, a+b+c+d=1, 1≤e≤1.15, and N comprises at least one of Al, Ti, Zr, Mg, Sr, Ba, Ca, Nb, W, Sb, Ta, Sn, and Y; (2) the range of the mass content of each of the Ni, Co, and Mn elements in the cathode material precursor is ≤0.12; (3) the surface area-weighted average particle size D[3,2] of the cathode material precursor is <2.0 μm, and the standard deviation of the mass content of each of the Ni, Co, and Mn elements in the cathode material precursor is ≤0.05; (4) the average particle size D of the cathode material precursor 50 The thickness is <3.5 μm; (5) the specific surface area of ​​the cathode material precursor is >5 m 2 / g and; (6) the Baxter tab density of the above cathode material precursor is >1g / cm³ 3 A manufacturing method characterized by satisfying at least one of the following features. Claim 8 In claim 5, the manufacturing method is characterized by comprising at least one of the following features: (1) the flow rate of the mixed solution is 100 L / h to 900 L / h; (2) the pressure of the atomization treatment is 0.4 MPa to 0.8 MPa; and (3) the thermal decomposition temperature is 500℃ to 850℃. Claim 9 In claim 5, the manufacturing method comprises at least one of the following features: (1) the lithium source comprises at least one of lithium carbonate, lithium hydroxide, lithium acetate, lithium sulfate, lithium chloride, lithium nitrate, and lithium oxalate; (2) the molar ratio of the total of nickel, cobalt, and manganese in the lithium source to the total molar ratio of nickel, cobalt, and manganese in the cathode material precursor is 0.98 to 1.10; (3) the sintering temperature is 750℃ to 950℃; and (4) the sintering time is 10h to 30h. Claim 10 A lithium-ion battery, wherein the lithium-ion battery comprises a single-crystal cathode material according to claim 1 or 2. Claim 11 delete Claim 12 delete Claim 13 delete Claim 14 delete Claim 15 delete

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