Positive electrode material and preparation method therefor, lithium-ion battery, and electrical device

Abstract

The present disclosure relates to the technical field of batteries, and specifically discloses a positive electrode material and a preparation method therefor, a lithium-ion battery, and an electrical device. The positive electrode material satisfies: 1.5 < Kn90 = (Ln90 - Ln10) / Ln50 < 4.5; 0 < Ln10 < 2000 Å; Ln10 < Ln50 < 3000 Å; and Ln50 < Ln90 < 15000 Å.

Description

Cathode materials and their preparation methods, lithium-ion batteries and electrical devices

[0001] Priority information

[0002] This disclosure requests priority and benefits from the patent publication No. 202411586363.8 filed with the China National Intellectual Property Administration on November 7, 2024, the entire contents of which are incorporated herein by reference. Technical Field

[0003] This disclosure belongs to the field of battery technology, specifically relating to a cathode material and its preparation method, a lithium-ion battery, and an electrical device. Background Technology

[0004] In recent years, lithium iron phosphate (LFP) materials have dominated the domestic battery industry due to their absolute cost advantage and good safety, showing broad development prospects. However, LFP materials still have shortcomings: the phosphate group is too polar, resulting in excessive binding capacity of lithium and a low diffusion coefficient, which affects its charge-discharge performance in low-temperature environments, making its low-temperature performance, especially at low state of charge (SOC), poor. To meet the special application scenarios such as low temperatures, some companies still choose the more expensive ternary materials for battery manufacturing. Although ternary materials have better low-temperature performance than LFP materials, with increasingly stringent market demands, further improvements to the low-temperature performance of materials are still needed.

[0005] At low temperatures, the diffusion coefficient of lithium ions within ternary materials decreases, increasing the energy required for charge transfer. This results in high low-temperature impedance and poor low-temperature discharge capability. Related technologies aim to improve low-temperature performance by increasing cobalt content or introducing solid-state electrolyte coatings; however, both methods significantly increase material costs, thereby reducing market competitiveness. Therefore, the low-temperature performance of cathode materials still requires further improvement. Summary of the Invention

[0006] This disclosure aims to at least partially address one of the technical problems in the related art. To this end, this disclosure proposes a cathode material with high capacity, good cycle retention, excellent low-temperature performance, simple operation, or low cost, as well as its preparation method, a lithium-ion battery, and an electrical device thereof.

[0007] The first aspect of this disclosure proposes a cathode material that satisfies: 1.5 < Kn 90 =(Ln 90 -Ln 10 ) / Ln 50 <4.5;

[0008] Among them, Ln 10 、Ln50 、Ln 90 These are the subgrain sizes Ln and Kn corresponding to the cumulative percentage of subgrain sizes Ln in the cathode material reaching 10%, 50%, and 90%, respectively. 90 It refers to the subgrain size distribution of the cathode material.

[0009] In this cathode material, the subgrain size distribution is within the above range, which can effectively improve the kinetic and low-temperature performance of the cathode material.

[0010] In some implementations... Subgrain size within the above range is beneficial for further improving the kinetic performance of cathode materials.

[0011] In some implementations, 2.5 < Kn 90 <4.0. This is beneficial for further improving the low-temperature performance and kinetic performance of the cathode material.

[0012] In some embodiments, the particle size P satisfies 1.0 μm < P < 2.0 μm; in other embodiments, 1.3 μm < P < 1.7 μm. Within the above particle size range, complete particle sintering is beneficial, thereby improving the conductivity and low-temperature performance of the cathode material.

[0013] In some embodiments, the median particle size of the positive electrode material in terms of volume distribution is D'50, where 1 μm < D'50 < 4 μm.

[0014] In some embodiments, the positive electrode material comprises the composition shown in Formula I: Li 1+a (Ni x Co y Mn z G b M c O2 Formula I

[0015] Where, 0≤a≤0.2, 0≤b≤0.05, 0≤c≤0.05, 0.4≤x<1, 0 <y<0.15,0≤z<0.5,

[0016] Element G includes at least one of Zr, Ti, Y, W, Al, Nb, and Sr;

[0017] Element M includes at least one of La, Zr, B, Nb, Ti, W, Si, Mg, and Al.

[0018] With the above chemical formula, this cathode material has a low cobalt content, low cost, and excellent low-temperature performance.

[0019] In some embodiments, the cathode material includes a substrate and a coating layer, the coating layer being disposed on at least a portion of the surface of the substrate; element M is mainly located in the coating layer. This further improves the stability of the cathode material, reducing side reactions with the electrolyte when used in lithium-ion batteries, thereby improving the cycle performance of the lithium-ion battery.

[0020] In some embodiments, the cobalt concentration on the surface of the cathode material particles is higher than the cobalt concentration inside the particles. By controlling the cobalt concentration of the cathode material to form particles with high cobalt on the surface and low cobalt inside, it is possible to maintain good low-temperature performance while keeping the overall cobalt content in the cathode material relatively low, thereby reducing costs.

[0021] In some implementations, the molar percentage of cobalt among all metal elements except lithium is greater than 0 and less than or equal to 15%, specifically greater than 0 and less than or equal to 10%. This reduces the cobalt content and further lowers costs.

[0022] The second aspect of this disclosure discloses a method for preparing a cathode material, comprising:

[0023] Nickel-cobalt-manganese precursor and lithium salt are mixed, and the resulting raw material mixture is subjected to a first sintering at 700℃~1000℃ for 6h~12h in an oxygen-containing atmosphere to obtain an intermediate product.

[0024] The intermediate product, lithium source, and cobalt source are mixed, and the resulting intermediate product mixture is subjected to a second sintering at 300°C to 800°C for 6 to 12 hours in an oxygen-containing atmosphere to obtain the cathode material.

[0025] Wherein, the molar ratio of lithium in the lithium source to cobalt in the cobalt source is Y, where 0.5 < Y < 1.4.

[0026] This preparation method is simple to operate and has low cost. When the prepared cathode material is used in a battery, it can improve the battery's low-temperature performance, kinetic performance and cycle performance.

[0027] According to embodiments of this disclosure, the molar ratio of lithium in the lithium source to cobalt in the cobalt source is Y, where 0.8 < Y < 1.2. Within this ratio range, a lithium cobalt oxide layer can be formed on the surface of the cathode material particles, increasing the cobalt content on the cathode material surface, thereby improving lithium-ion transport performance and low-temperature performance.

[0028] According to embodiments of this disclosure, the lithium salt includes at least one of lithium carbonate and lithium hydroxide; in some embodiments, the lithium salt includes a mixed lithium salt of lithium carbonate and lithium hydroxide; in some specific embodiments, the lithium salt includes a mixed lithium salt of lithium carbonate and lithium hydroxide with a lithium element molar ratio of 3:7 to 8:2. Using a mixed lithium salt can combine the advantages of both types of lithium salts, enabling rapid growth of single crystal particles while maintaining good independence.

[0029] According to embodiments of this disclosure, the molar ratio of cobalt in the cobalt source to the sum of nickel, cobalt, and manganese in the cathode material is less than 5%. This increases the cobalt content on the surface of the cathode material, improves lithium-ion transport performance, and enhances low-temperature performance.

[0030] In some embodiments, the median particle size of the nickel-cobalt-manganese precursor in its volume distribution is D50, where 1 μm < D50 < 3.5 μm.

[0031] When the median particle size D50 of the volume distribution of the nickel-cobalt-manganese precursor is within the above range, the adhesion between particles can be reduced, resulting in higher capacity and better low-temperature performance of the cathode material. When used in batteries, it can improve the cycle performance of the battery.

[0032] In some embodiments, the raw material mixture also includes a compound containing element G.

[0033] In some embodiments, the intermediate mixture also includes a compound containing element M.

[0034] In some embodiments, the nickel-cobalt-manganese precursor comprises at least one of nickel-cobalt-manganese oxide and nickel-cobalt-manganese hydroxide. Therefore, the material is widely available and readily accessible.

[0035] In some embodiments, the compound containing element G includes at least one of oxides, hydroxides, and carbonates of element G, and element G includes at least one of Zr, Ti, Y, W, Al, Nb, and Sr. Therefore, the material is widely available, which is beneficial for improving the electrochemical performance of the cathode material.

[0036] In some embodiments, the cobalt source includes at least one of cobalt oxide, cobalt tetroxide, cobalt hydroxyl oxide, and cobalt hydroxide. This provides a wide range of material sources, which is beneficial for improving the low-temperature performance of the cathode material.

[0037] In some embodiments, the lithium source includes at least one of lithium carbonate, lithium hydroxide, lithium phosphate, and lithium dihydrogen phosphate. Therefore, the material is widely available and the cost is low.

[0038] In some embodiments, the compound containing element M includes at least one of oxides, hydroxides, and carbonates of element M, and the coating element M includes at least one of La, Zr, B, Nb, Ti, W, Si, Mg, and Al. Therefore, the material is widely available, which is beneficial for improving the low-temperature performance of the cathode material.

[0039] This disclosure provides a third aspect of a lithium-ion battery, comprising the cathode material described in the first aspect of the disclosure or the cathode material prepared by the method of the second aspect. Therefore, this lithium-ion battery has low cost and excellent low-temperature performance.

[0040] This disclosure provides a fourth aspect of an electrical device comprising the lithium-ion battery described in the third aspect of this disclosure. This electrical device possesses all the features and advantages of the lithium-ion battery described above, which will not be repeated here. Attached Figure Description

[0041] Figure 1 is an electron microscope image of the finished positive electrode material of Embodiment 1 of this disclosure.

[0042] Figure 2 is an electron microscope image of the finished positive electrode material of Embodiment 5 of this disclosure.

[0043] Figure 3 is an electron microscope image of the finished positive electrode material of Embodiment 6 of this disclosure.

[0044] Figure 4 is an electron microscope image of the cathode material product of Comparative Example 1 of this disclosure.

[0045] Figure 5 is a subgrain size distribution diagram of the cathode material products of Embodiment 1, Embodiment 9 and Comparative Example 1 of this disclosure. Detailed Implementation

[0046] Embodiments of this disclosure are described in detail below, with examples of these embodiments illustrated in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this disclosure, and should not be construed as limiting it.

[0047] The first aspect of this disclosure proposes a cathode material that satisfies: 1.5 < Kn 90 =(Ln 90 -Ln 10 ) / Ln 50 <4.5;

[0048] Among them, Ln 10 、Ln 50 、Ln 90 These are the subgrain sizes Ln and Kn corresponding to the cumulative percentage of subgrain sizes Ln in the cathode material reaching 10%, 50%, and 90%, respectively. 90 It refers to the subgrain size distribution of the cathode material.

[0049] It should be noted that the subgrain size Ln of the cathode material was obtained by statistical analysis of the powder X-ray diffraction pattern obtained using CuKα rays and fitted with a Fundamental Parameter method. Wherein, Ln 50 As a physical quantity representing the median of the quantity distribution, Kn can represent the size of the subgrain size. The smaller the subgrain size, the shorter the migration path of lithium ions in the cathode material and the relatively higher the diffusion rate, that is, the better the material kinetic performance. 90 This can reflect the uniformity of grain distribution. When Kn 90 If the size is too large or too small, the conductivity of the material will decrease, the charge transfer resistance will increase, and the polarization will intensify, resulting in poorer electrochemical performance at low temperatures. Subgrain size Ln 10 、Ln 50 、Ln 90 Out of range or Kn 90 If the requirements are not met, the low-temperature performance will deteriorate to some extent.

[0050] In summary, the subgrain size Ln 10 、Ln 50 、Ln 90 and Kn 90 Within the aforementioned range, the cathode material exhibits excellent kinetic and low-temperature performance.

[0051] In some implementations... In some specific examples, Ln 10 It can be or Wait, Ln 50 It can be or Wait, Ln 90 It can be or Subgrain sizes within the aforementioned range are beneficial for further improving the kinetic performance of cathode materials.

[0052] In some implementations, 2.5 < Kn 90 <4.0, specifically, Kn 90 The possible values ​​are 2.51, 2.6, 2.7, 2.8, 2.9, 3.0, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 3.9, etc. This is beneficial for further improving the low-temperature performance and kinetic properties of the cathode material.

[0053] In some implementations, the particle size P satisfies 1.0 μm < P < 2.0 μm; in other implementations, 1.3 μm < P < 1.7 μm. In some specific examples, the particle size P can be 1.1 μm, 1.2 μm, 1.3 μm, 1.4 μm, 1.5 μm, 1.6 μm, or 1.7 μm, etc.

[0054] It should be noted that the particle size P refers to the average diameter calculated by converting the projected area of ​​500 randomly selected particles obtained through electron microscopy into a standard circle of equal area. If the particle size is too large, the lithium-ion transport path increases, leading to a relative deterioration in electrical performance and consequently, a decline in the particle's low-temperature performance. Conversely, if the particle size is too small, incomplete sintering may occur, resulting in significant particle adhesion and hindering the formation of independent single-crystal particles. Therefore, to achieve optimal performance, the particle size should be controlled within a suitable range. Particle sizes within this range promote complete sintering, improving the conductivity and low-temperature performance of the cathode material.

[0055] In some embodiments, the cathode material can be a single-crystal nickel-cobalt-manganese ternary cathode material.

[0056] In some embodiments, the positive electrode material comprises the composition shown in Formula I: Li 1+a (Ni x Co y Mn z G b M c O2 Formula I

[0057] Where, 0≤a≤0.2, 0≤b≤0.05, 0≤c≤0.05, 0.4≤x<1, 0 <y<0.15,0≤z<0.5,

[0058] Element G includes at least one of Zr, Ti, Y, W, Al, Nb, and Sr;

[0059] Element M includes at least one of La, Zr, B, Nb, Ti, W, Si, Mg, and Al.

[0060] With the above chemical formula, this cathode material has a low cobalt content, low cost, and excellent low-temperature performance.

[0061] In some embodiments, the cathode material includes a substrate and a coating layer, the coating layer being disposed on at least a portion of the surface of the substrate; element M is mainly located in the coating layer. This further improves the stability of the cathode material, reducing side reactions with the electrolyte when used in lithium-ion batteries, thereby improving the cycle performance of the lithium-ion battery.

[0062] In some implementations, element G refers to an element with a deep doping depth that can penetrate into the interior of the particle, i.e., a bulk doping element; while element M is mainly located in the coating layer, meaning that element M is usually difficult to penetrate into the lattice of the cathode material, but is coated on the surface of the cathode material particles, or a small portion diffuses into the interior of the cathode material particles near the surface.

[0063] In some embodiments, the cobalt concentration on the surface of the cathode material particles is higher than the cobalt concentration inside the particles. By controlling the cobalt concentration of the cathode material to form particles with high cobalt on the surface and low cobalt inside, it is possible to maintain good low-temperature performance while keeping the overall cobalt content in the cathode material relatively low, thereby reducing costs.

[0064] In some implementations, the molar percentage of cobalt among all metal elements except lithium is greater than 0 and less than or equal to 15%, specifically greater than 0 and less than or equal to 10%; for example, it can be 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, or 10%, etc. This allows for reducing the cobalt content while maintaining a high low-temperature discharge capacity retention rate and low low-temperature impedance, further reducing production costs.

[0065] In this article, the term "particle surface" refers to the portion of the outer surface of the cathode material particle that faces inward and accounts for 10% of the particle diameter, while "particle interior" refers to the portion outside the aforementioned particle surface.

[0066] In some implementations, EDS can be used to randomly select 10 detection points on the particle surface and inside the particle to test the cobalt content. Then, the average cobalt content at the detection points on the particle surface (1) and the average cobalt content at the detection points inside the particle (2) can be calculated. Average value 1 and average value 2 represent the cobalt content on the particle surface and inside the particle, respectively.

[0067] The second aspect of this disclosure discloses a method for preparing a cathode material, comprising:

[0068] S1: Mix the nickel-cobalt-manganese precursor and lithium salt, and subject the resulting raw material mixture to a first sintering at an oxygen-containing atmosphere at 700℃~1000℃ (e.g., 700℃, 800℃, 900℃ or 1000℃, etc.) for 6h~12h (e.g., 6h, 7h, 8h, 9h, 10h, 11h or 12h, etc.) to obtain an intermediate product.

[0069] In some embodiments, the nickel-cobalt-manganese precursor includes at least one of nickel-cobalt-manganese oxide and nickel-cobalt-manganese hydroxide. The nickel-cobalt-manganese precursor used in this disclosure has an extremely low cobalt content; although a cobalt source is added in subsequent steps, the cobalt content in the finished cathode material remains low. This is beneficial for improving the low-temperature performance of the cathode material while reducing costs.

[0070] In some embodiments, the lithium salt comprises at least one of lithium carbonate and lithium hydroxide. In some embodiments, the lithium salt comprises a mixed lithium salt of lithium carbonate and lithium hydroxide. In other embodiments, the lithium salt comprises a mixed lithium salt of lithium carbonate and lithium hydroxide with a lithium element molar ratio of 3:7 to 8:2; in some specific examples, the lithium element molar ratio in lithium carbonate and lithium hydroxide can be 3:7, 4:6, 5:5, 6:4, 7:3, or 8:2, etc.

[0071] It is understandable that during the sintering process of cathode materials, under the influence of lithium salt and temperature, the primary fibers of the nickel-cobalt-manganese precursor gradually grow and fuse to form multiple spherical aggregated particles. As the sintering time progresses, the aggregated particles gradually grow larger, and the boundaries between the particles gradually become more distinct, eventually separating to form multiple single-crystal particles. Single-crystal particles obtained by sintering pure lithium carbonate are easier to grow and easier to separate, but the particle morphology is relatively irregular and the impedance is relatively high. Single-crystal particles obtained by sintering pure lithium hydroxide have regular morphology and lower impedance, but are relatively difficult to grow and are also relatively difficult to separate, which may affect high-temperature cycling performance. Using mixed lithium salts can combine the advantages of both lithium salts, allowing single-crystal particles to grow rapidly while maintaining good independence.

[0072] In some implementations, the compound containing element G may or may not be added in this step, depending on the needs of use. That is, when no doping element is required, the raw material mixture in this step may only include nickel-cobalt-manganese precursor and lithium salt; when doping element is required, the raw material mixture in this step includes nickel-cobalt-manganese precursor, lithium salt and compound containing element G.

[0073] In some embodiments, the compound containing element G includes at least one of oxides, hydroxides, and carbonates of element G, and element G includes at least one of Zr, Ti, Y, W, Al, Nb, and Sr. As specific examples, the compound containing element G can be ZrO2, Y2O3, or Al2O3, etc. This can achieve the effect of bulk doping, thereby improving the electrochemical performance of the cathode material.

[0074] In some implementations, the oxygen-containing atmosphere can be either air or oxygen, and the choice can be made flexibly according to actual needs.

[0075] In some embodiments, a crushing step is included after the first sintering. Specifically, the crushing equipment is one or more of the following: a soybean milk maker, a jaw crusher, a double roller mill, a colloid mill, a mechanical mill, and an air jet mill. This reduces the particle size of the intermediate product, which is beneficial for subsequent operations.

[0076] In some embodiments, the median particle size of the nickel-cobalt-manganese precursor in its volume distribution is D50, where 1 μm < D50 < 3.5 μm. In some specific examples, D50 can be 1.5 μm, 2 μm, 2.5 μm, or 3 μm, etc. Within the above range, particle adhesion can be reduced, resulting in higher capacity and better low-temperature performance of the cathode material, which can improve the cycle performance of the battery when used in a battery.

[0077] S2: The intermediate product, lithium source and cobalt source are mixed, and the resulting intermediate product mixture is subjected to a second sintering at an oxygen-containing atmosphere and at 300℃~800℃ (e.g. 300℃, 400℃, 500℃, 600℃, 700℃ or 800℃, etc.) for 6h~12h (e.g. 6h, 7h, 8h, 9h, 10h, 11h or 12h, etc.) to obtain the cathode material.

[0078] In some embodiments, the lithium source includes at least one of lithium carbonate, lithium hydroxide, lithium phosphate, and lithium dihydrogen phosphate. Therefore, the material is widely available and the cost is low.

[0079] In some embodiments, the cobalt source includes at least one of cobalt oxide, cobalt tetroxide, cobalt hydroxyl oxide, and cobalt hydroxide. This provides a wide range of material sources, which is beneficial for improving the low-temperature performance of the cathode material.

[0080] In some embodiments, the molar ratio of cobalt in the cobalt source to the sum of nickel, cobalt, and manganese in the cathode material is <5%, i.e., n(cobalt in the cobalt source):n(the sum of nickel, cobalt, and manganese in the finished product) <5%, for example, it can be 1%, 2%, 3%, or 4%, etc. This can reduce the cobalt content in the cathode material and reduce costs.

[0081] In some embodiments, the molar ratio of lithium in the lithium source to cobalt in the cobalt source is Y, where 0.5 < Y < 1.4, and in some specific embodiments, 0.8 < Y < 1.2. Specifically, the value of Y can be 0.6, 0.7, 0.8, 0.9, 1, 1.1, 1.2, 1.3, etc.

[0082] The addition of cobalt and lithium sources involves using trace amounts of cobalt to form a lithium cobalt oxide layer on the material surface, increasing the cobalt content on the cathode material surface, thereby improving lithium-ion transport performance and low-temperature performance. If the Y value is too low, the added cobalt source may not react sufficiently with lithium, resulting in an unsatisfactory improvement effect, and may even compete with the bulk lithium, leading to increased lithium-nickel mixing in the material. If the Y value is too high, there may be excessive residual lithium on the surface, resulting in unsatisfactory processing performance and battery cycle performance. When the Y value is within the above range, the low-temperature performance of the cathode material can be effectively improved without significantly affecting other properties.

[0083] In some embodiments, the compound containing element M includes at least one of oxides, hydroxides, and carbonates of element M, wherein element M includes at least one of La, Zr, B, Nb, Ti, W, Si, Mg, and Al. As specific examples, the compound containing element M can be Al₂O₃, TiO₂, or WO₃, etc. Therefore, the material is widely available, which is beneficial for improving the low-temperature performance of the cathode material.

[0084] It should be noted that in this step, the compound containing element M can be added or omitted depending on actual needs. That is, when a compound containing element M is required, the intermediate, lithium source, cobalt source, and compound containing element M are mixed and subjected to a second sintering in this step; when a compound containing element M is not required, the intermediate, lithium source, and cobalt source are mixed and subjected to a second sintering in this step. It can be understood that the cathode material may include a substrate and a coating layer disposed on at least a portion of the surface of the substrate, with element M mainly located in the coating layer.

[0085] In some embodiments, the median particle size of the positive electrode material in its volume distribution is D'50, where 1 μm < D'50 < 4 μm. In some specific examples, D'50 can be 1.5 μm, 2 μm, 2.5 μm, 3 μm, or 3.5 μm, etc. Within the above range, particle adhesion can be reduced, resulting in a positive electrode material with higher capacity and better low-temperature performance, which can improve the cycle performance of the battery when used in a battery.

[0086] In some embodiments, the particle size increase rate X = (D'50 - D50) / D50, and X < 0.25. Specifically, the particle size increase rate X can be 0.01, 0.05, 0.1, 0.15, or 0.2, etc. When the particle size increase rate is within the above range, particle adhesion is slight or even non-existent, which is beneficial to improving the electrical performance of the cathode material.

[0087] In some implementations, (D'50-D50) / P < 0.7. Specifically, (D'50-D50) / P can be 0.65, 0.6, 0.55, 0.5, 0.45, 0.4, 0.35, 0.3, 0.25, 0.2, 0.15, 0.1, etc. This reduces particle adhesion and yields a cathode material with good low-temperature performance.

[0088] The median particle sizes D50 and D'50 of the volume distribution of the nickel-cobalt-manganese precursor and cathode material were obtained by Malvern particle size analyzer. Single-crystal particles prepared using smaller nickel-cobalt-manganese precursors exhibit better independence and roundness, resulting in superior electrical performance (especially capacity and low-temperature performance). Furthermore, when particle sizes P are comparable, ensuring that the difference between the D50 of the nickel-cobalt-manganese precursor and the D'50 of the single-crystal nickel-cobalt-manganese ternary cathode material is within a suitable range avoids severe particle adhesion, thus improving the cycle performance of batteries using this cathode material.

[0089] The method for preparing cathode materials disclosed herein involves mixing a nickel-cobalt-manganese precursor with low cobalt content with lithium salt and additives, followed by a high-temperature solid-state reaction to obtain an intermediate product. The crushed intermediate product is then uniformly mixed with a lithium source, a cobalt source, and a compound, and subjected to another high-temperature solid-state reaction to obtain a low-cobalt cathode material. Furthermore, during the preparation process, the distribution of subgrain size in the cathode material is regulated by controlling the type of lithium salt, the molar ratio Y of the lithium source and cobalt source, the particle size P of the single crystal particles, the particle size increase rate X, and the reaction conditions, thereby effectively improving the low-temperature performance of the low-cobalt content cathode material.

[0090] This disclosure provides a third aspect of a lithium-ion battery, comprising the cathode material described in the first aspect of the disclosure or the cathode material prepared by the method of the second aspect. Therefore, this lithium-ion battery has low cost and excellent low-temperature performance.

[0091] It is understandable that there are no particular restrictions on the specific type of lithium-ion battery; it can be a primary battery or a secondary battery. The shape of the lithium-ion battery can be cylindrical, square, or any other shape. According to the outer packaging, lithium-ion batteries can be hard-shell batteries, soft-pack batteries, etc.

[0092] Typically, a lithium-ion battery includes a positive electrode, a negative electrode, an electrolyte, and a separator. The positive electrode, negative electrode, and separator are fabricated into electrode assemblies using winding or stacking processes. The electrode assemblies and electrolyte are housed in an outer package. During the charging and discharging process of a lithium-ion battery, active ions repeatedly insert and extract between the positive and negative electrodes. The electrolyte acts as a conductor of ions between the positive and negative electrodes. The separator, positioned between the positive and negative electrodes, primarily prevents short circuits while allowing ions to pass through.

[0093] In some embodiments, the positive electrode sheet may include a positive current collector and a positive active material layer disposed on at least one surface of the positive current collector. The positive active material layer includes a positive active material, a conductive agent, and a binder. The positive current collector may include a metal foil, for example, aluminum foil. The positive active material may include the positive electrode material of the first aspect of this disclosure or the positive electrode material prepared by the method described in the second aspect of this disclosure. The conductive agent may include acetylene black, single-walled carbon nanotubes, and conventional materials in the art. The binder may be polyvinylidene fluoride (PVDF) and conventional materials in the art.

[0094] In some embodiments, the negative electrode sheet may include a negative electrode current collector and a layer of negative electrode active material disposed on at least one side surface of the negative electrode current collector. The negative electrode active material layer may include a negative electrode active material, a thickener, a conductive agent, and a binder. The negative electrode current collector may be a metal foil, for example, copper foil. The negative electrode active material may include artificial graphite, natural graphite, silicon-carbon based composite materials, lithium metal composite materials, lithium metal materials, and other commonly used negative electrode active materials in the art. The thickener may be sodium carboxymethyl cellulose (CMC-Na) and other conventional materials in the art. The conductive agent may be acetylene black and other conventional materials in the art. The binder may be styrene-butadiene rubber and other conventional materials in the art.

[0095] In some embodiments, the separator may be a separator known in the art that can be used in lithium-ion batteries and is stable to the electrolyte used, such as a polyethylene separator, a polypropylene separator, a polyethylene / polypropylene composite separator, etc.

[0096] This disclosure provides a fourth aspect of an electrical device comprising the lithium-ion battery described in the third aspect of this disclosure. This electrical device possesses all the features and advantages of the lithium-ion battery described above, which will not be repeated here.

[0097] In some embodiments, the electrical device may include mobile devices (e.g., mobile phones, laptops, etc.), electric vehicles (e.g., pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc., but is not limited thereto.

[0098] The embodiments of this disclosure are described in detail below.

[0099] Example 1

[0100] (1) Preparation of intermediate products for single-crystal nickel-cobalt-manganese ternary cathode materials: A mixed lithium salt of lithium carbonate and lithium hydroxide (molar ratio of Li in lithium carbonate to Li in lithium hydroxide = 7:3), a nickel-cobalt-manganese hydroxide precursor (Ni 0.6 Co0.05 Mn 0.35 (OH)2 (D50 = 2.72 μm) and additive ZrO2 were mixed uniformly in a molar ratio of 1.04:1:0.003 using a high-speed mixer; the mixture was then subjected to a first sintering in an oxygen atmosphere at a sintering temperature of 970℃ for 10 hours; after sintering, the sintered material was crushed by an air jet mill to obtain a single-crystal nickel-cobalt-manganese ternary cathode material intermediate.

[0101] (2) Preparation of single-crystal nickel-cobalt-manganese ternary cathode material: The cathode material intermediate obtained in the above steps is mixed with additive Al2O3, lithium source lithium carbonate, and cobalt source Co(OH)2 in a ratio of [n(Ni in the precursor) + n(Co in the precursor) + n(Mn in the precursor)] (which can be simplified as [n(Ni) + n(Co) + n(Mn)]): n(Al2O3): n(Li in the lithium source): n(Co in the cobalt source) = 1:0.001:0.01:0.01 using a high-speed mixer; the mixture is then subjected to a second sintering in an oxygen atmosphere at a sintering temperature of 700℃ for 8 hours; after sintering, the sintered material is crushed by a colloid mill to obtain the single-crystal nickel-cobalt-manganese ternary cathode material with D'50 = 3.08 μm; specific indicators are shown in Table 1, and electron micrographs are shown in Figure 1.

[0102] Example 2

[0103] The difference from Example 1 is that the first sintering temperature in step (1) is adjusted to 987℃, while the other parameters remain unchanged, resulting in a finished product D'50 = 3.14, as shown in Table 1.

[0104] Example 3

[0105] The difference from Example 1 is that the composition of the nickel-cobalt-manganese precursor in step (1) is adjusted to Ni:Co:Mn = 60:10:30 (molar ratio), and a precursor with D50 = 2.94 μm is used. The finished product with D'50 = 3.44 μm is prepared by adjusting the crushing intensity of the colloid mill. The other parameters remain unchanged, as shown in Table 1.

[0106] Example 4

[0107] The difference from Example 1 is that the lithium salt ratio in step (1) is adjusted to: the molar ratio of Li in lithium carbonate to the molar ratio of Li in lithium hydroxide = 9:1, while the other parameters remain unchanged, resulting in a finished product D'50 = 3.11 μm, as shown in Table 1.

[0108] Example 5

[0109] The difference from Example 1 is that in step (1), the lithium salt is adjusted to pure lithium carbonate, while the other parameters remain unchanged, and the finished product D'50 = 3.04 μm is obtained. See Table 1 for details and Figure 2 for electron microscope image.

[0110] Example 6

[0111] The difference from Example 1 is that in step (1), the lithium salt is adjusted to pure lithium hydroxide, while the other parameters remain unchanged, and the finished product D'50 = 3.08 μm is obtained. See Table 1 for details and Figure 3 for electron micrograph.

[0112] Example 7

[0113] The difference from Example 1 is that: in step (1), the composition of the nickel-cobalt-manganese precursor is adjusted to Ni:Co:Mn=86:6:8 (molar ratio), D50=2.18μm; Y2O3 is added to the additive based on ZrO2, and the addition ratio of lithium salt, nickel-cobalt-manganese precursor to ZrO2 and Y2O3 is adjusted to 1.03:1:0.002:0.001; the first sintering temperature is adjusted to 880℃, and the first sintering time is 8h;

[0114] In step (2), the additive was adjusted to TiO2, the lithium source was adjusted to lithium hydroxide, and the cobalt source was adjusted to Co3O4. The ratio of [n(Ni in the precursor) + n(Co in the precursor) + n(Mn in the precursor)]: n(TiO2): n(Li in the lithium source): n(Co in the cobalt source) = 1:0.001:0.011:0.01 was adjusted. The second sintering temperature was adjusted to 650℃. The finished product D'50 = 2.74μm. The other parameters remained unchanged. See Table 1 for details.

[0115] Example 8

[0116] The difference from Example 1 is that in step (1), Al2O3 is added to ZrO2 as the additive and the ratio of lithium salt, precursor and ZrO2 and Al2O3 is adjusted to 1.05:1:0.002:0.001; the first sintering temperature is adjusted to 955℃ and the first sintering time is 12h; the finished product D'50 = 3.19μm, and the other parameters remain unchanged, as shown in Table 1.

[0117] Example 9

[0118] The difference from Example 1 is that the additive in step (2) is adjusted to WO3, [n(Ni)+n(Co)+n(Mn)]:n(WO3):n(Li in lithium source):n(Co in cobalt source)=1:0.001:0.01:0.01, and the other parameters remain unchanged, resulting in a finished product D'50=3.12μm, as shown in Table 1.

[0119] Example 10

[0120] The difference from Example 1 is that in step (2), the cobalt source is adjusted to CoOOH, [n(Ni)+n(Co)+n(Mn)]:n(Al2O3):n(Li in the lithium source):n(Co in the cobalt source)=1:0.001:0.007:0.01, and the other parameters remain unchanged, resulting in a finished product D'50=3.11μm, as shown in Table 1.

[0121] Example 11

[0122] The difference from Example 1 is that in step (2), the lithium source is adjusted to lithium phosphate, while the other parameters remain unchanged, as shown in Table 1.

[0123] Example 12

[0124] The difference from Example 1 is that the first sintering temperature in step (1) is 965°C and the first sintering time is 11h.

[0125] In step (2), the additive M is adjusted to WO3, and the ratio of [n(Ni)+n(Co)+n(Mn)]:n(WO3):n(Li in lithium source):n(Co in cobalt source) is 1:0.001:0.013:0.01. The second sintering temperature is adjusted to 620℃ and the second sintering time is adjusted to 7h. By adjusting the crushing conditions, D'50 = 3.21μm is obtained. The other parameters remain unchanged, as shown in Table 1.

[0126] Comparative Example 1

[0127] The difference from Example 1 is that the amount of lithium source added in step (2) is adjusted so that [n(Ni)+n(Co)+n(Mn)]:n(Al2O3):n(Li in lithium source):n(Co in cobalt source)=1:0.001:0.003:0.01, and the other parameters remain unchanged, resulting in D'50=3.18μm, as shown in Table 1 and the electron microscope image in Figure 4.

[0128] Comparative Example 2

[0129] The difference from Example 1 is that the amount of lithium source added in step (2) is adjusted so that [n(Ni)+n(Co)+n(Mn)]:n(Al2O3):n(Li in lithium source):n(Co in cobalt source) = 1:0.001:0.01:0.005, while the other parameters remain unchanged, resulting in D'50 = 3.07 μm, as shown in Table 1.

[0130] Comparative Example 3

[0131] The difference from Example 1 is that no lithium source is added in step (2), and the other parameters remain unchanged, resulting in D'50 = 3.16 μm, as shown in Table 1.

[0132] Comparative Example 4

[0133] The difference from Example 1 is that no cobalt source is added in step (2), and the other parameters remain unchanged, resulting in D'50 = 3.10 μm, as shown in Table 1.

[0134] Testing and Equipment:

[0135] (1) Particle size D50, D'50: obtained by testing with a Marvern Mastersizer 3000 laser particle size analyzer;

[0136] (2) Electron microscopy test: The results were obtained using a Hitachi S-4800 scanning electron microscope from Japan.

[0137] The projected area of ​​each single crystal particle in the electron microscope is statistically analyzed, and then its particle size is calculated. The specific method is as follows: the average diameter is calculated by converting the projected area of ​​500 random particles in the scanning electron microscope image into a standard circle with equal area, which is the particle size P of the single crystal nickel-cobalt-manganese ternary cathode material.

[0138] (3)Ln 10 、Ln 50 、Ln 90 and Ni 2+ Molar content: Tested using a Rigaku Smartlab 9KW rotating target diffractometer, range 10-80°, voltage 40kV, current 200mA, step 0.02°, scan time 2° / min. The test results were obtained by statistical calculation of microcrystal size using the WPPF grain size distribution function of SmartLab Studio II software according to the Fundamental Parameter method (FP method). The subgrain size distribution diagrams of the cathode materials of Examples 1, 9, and Comparative Example 1 are shown in Figure 5.

[0139] (4) Battery fabrication and electrical performance testing:

[0140] In the above examples and comparative examples, the electrochemical performance of the single-crystal nickel-cobalt-manganese ternary cathode material was tested using a CR2025 coin cell, and its preparation process is as follows:

[0141] Electrode preparation: Positive electrode material, conductive carbon black, and polyvinylidene fluoride (PVDF) were thoroughly mixed with an appropriate amount of N-methylpyrrolidone (NMP) at a mass ratio of 95:3:2 to form a uniform electrode slurry (with a solid content of 60% at 25°C). This slurry was coated onto aluminum foil and dried at 120°C for 12 hours. It was then pressed into a positive electrode sheet with a diameter of 15.8 mm and a thickness of 3.2 mm using a pressure of 100 MPa. The loading of the positive electrode material was 15.5 mg / cm³. 2In an argon-filled glove box with both water and oxygen content less than 5 ppm, the positive electrode, separator, negative electrode, and electrolyte were assembled into a CR2025 coin cell and then left to stand for 6 hours. The negative electrode used a 15.8 mm diameter, 1 mm thick lithium metal sheet; the separator used a 25 μm thick polypropylene microporous membrane (Celgard 2325); and the electrolyte was a 1 mol / L mixture of equal parts LiPF6, ethylene carbonate (EC), and diethyl carbonate (DEC).

[0142] Capacity Testing: The electrochemical performance of CR2025 coin cells was tested using the Shenzhen Xinwei Battery Testing System. The charge / discharge current density at 0.1C was 100 mA / g. The charge / discharge voltage range was controlled between 3.0 and 4.4V. At room temperature, the coin cells were charged and discharged at 0.1C to evaluate the charge / discharge specific capacity of the monocrystalline nickel-cobalt-manganese ternary cathode material. Example 7 used a high-nickel material, and its test voltage range was 3.0-4.35V.

[0143] High-temperature cycling performance testing: In both the examples and comparative examples, the charge / discharge voltage range was controlled to be 3.0-4.4V. At a constant temperature of 60℃, the coin cells were cycled twice at 0.1C, and then 80 times at 1C to evaluate the high-temperature cycling capacity retention of the single-crystal nickel-cobalt-manganese ternary cathode material. Example 7 uses a high-nickel material, and its cycling test voltage range is 3.0-4.35V.

[0144] Low-temperature performance testing (test voltage range for all lithium-ion batteries: 3.0-4.4V):

[0145] The -10℃ low-temperature capacity retention test involves activating the coin cell by charging and discharging it at 25℃ for one week at 1C. The discharge capacity A1 of the 1C charge-discharge cycle in the second week is recorded. After being fully charged at 1C, the battery is transferred to a -10℃ constant temperature chamber for 3 hours and then discharged at 1C. The discharge capacity is recorded as A2. The -10℃ low-temperature capacity retention rate is then calculated as A2 / A1 × 100%.

[0146] The -10℃ 10% SOC-DCR test involves activating the coin cell by charging and discharging it at 25℃ for one week at 1C, then charging it to 10% SOC at 1C, transferring it to a -10℃ constant temperature chamber for 2 hours, and then discharging it at 1C for 20 seconds. The -10℃ 10% SOC-DCR is calculated as (voltage at the last second of the resting step - voltage at 20 seconds of discharge) / discharge current.

[0147] The -10℃ 20% SOC-DCR test involves activating the coin cell by charging and discharging it at 1C for one week at 25℃, then charging it to 20% SOC at 1C, transferring it to a -10℃ constant temperature chamber for 2 hours, and then discharging it at 1C for 20 seconds. The -10℃ 20% SOC-DCR is calculated as (voltage at the last second of the resting step - voltage at 20 seconds of discharge) / discharge current.

[0148] The low-temperature discharge capability test involves activating the device at 0.1C for one cycle (4.45V cutoff) at room temperature (25℃), then charging it to 10% SOC at 0.5C. The device is then transferred to a -10℃ low-temperature chamber and left to stand for 1.5 hours. It is then discharged at 0.5C to 3.0V, and the time taken to discharge to 3.0V is recorded. The longer the discharge time, the stronger the low-temperature discharge capability.

[0149] Table 1. Preparation processes of examples and comparative examples

[0150] Table 1 (Continued) shows the preparation processes of the examples and comparative examples.

[0151] Table 2. Examples and Comparative Data

[0152] As shown in Table 2, Examples 1-12 all involved adjustments to process parameters within the permissible range of the scheme, including the composition of the precursor nickel-cobalt-manganese, the type and amount of lithium salt added during the first sintering, the types of cobalt and lithium sources, and the types of additives. All of these adjustments met the scheme's objective of improving low-temperature performance (low-temperature capacity retention, low-temperature low SOC-DCR, and low-temperature discharge capability). However, in Example 2, the increased sintering temperature resulted in larger particle sizes, increasing the lithium-ion transport path and thus reducing capacity and increasing low-temperature impedance. Compared to Examples 1 and 3, the cobalt content of the nickel-cobalt-manganese precursor in Example 3 was doubled compared to that in Example 1, but Ln... 50The smaller size resulted in low-temperature performance levels similar to or even slightly worse than Example 1, indicating that this scheme has a more significant effect on improving the performance (especially low-temperature performance) of low-cobalt materials. Compared with Examples 1, 5, and 6, the electrical performance of the finished products prepared using pure lithium carbonate or pure lithium hydroxide was slightly worse than that of the product prepared by mixing the two. Example 5 used pure lithium carbonate with a higher melting temperature, which made it easier for the reaction to occur on the surface, resulting in larger particle sizes (as shown in Figure 2). The poor lithium-ion transport capability led to higher impedance and poor low-temperature capacity retention. Example 6 used pure lithium hydroxide with a lower melting temperature, which allowed sufficient time for it to penetrate into the precursor, allowing the cathode material particles to grow from the inside to the outside. Therefore, the sintered particle size was smaller, and some particles were still in a near-single-crystal state (as shown in Figure 3). Although the low-temperature performance was better, the high-temperature cycle life was worse. Examples 8 and 9 were adjustments made in terms of doping and coating additives, respectively. The adjusted additive types and sintering conditions in Example 8 resulted in Ln 50 While the overall performance of Example 9 is relatively good, it still lags behind Example 1 due to its smaller size. Example 9 only changes the coating elements, thus its performance is closer to that of Example 1, exhibiting excellent low-temperature performance. Example 10 adjusts the type of cobalt source and the lithium-cobalt source ratio within the allowable range of the scheme. The performance of the prepared product is basically unaffected, but relatively speaking, the low-temperature performance is better when the lithium-cobalt ratio Y satisfies 0.8 < Y < 1.2. Example 11 changes the lithium source from lithium carbonate to lithium phosphate. Although the introduction of phosphate stabilizes the structure to some extent and has similar high-temperature cycling performance to Example 1, the lithium-ion transport capacity is limited, the capacity is slightly reduced, and the low-temperature DCR is increased.

[0153] As shown in Comparative Examples 1 and 2, both a lithium-cobalt ratio below and above the allowable range of this scheme will affect product performance such as capacity, cycle life, and low-temperature performance: If the lithium-cobalt ratio is too low, excessive cobalt will consume lithium within the cathode material particles, leading to a decrease in material capacity. Simultaneously, lithium extraction will increase the degree of lithium-nickel mixing, worsen low-temperature retention, and increase low-temperature impedance. If the lithium-cobalt ratio is too high, it will result in excessive lithium, with a large amount of lithium accumulating on the surface of the cathode particles. This will cause problems such as a surge in slurry viscosity and gelling during the material homogenization process, and its high-temperature cycle performance will also be greatly affected. Comparative Examples 3 and 4 involve no lithium source or cobalt source added during the coating process, respectively. The principle is the same as the limiting conditions for the lithium-cobalt ratio in Comparative Examples 1 and 2.

[0154] Both low-temperature capacity retention and low-temperature SOC-DCR reflect the low-temperature performance of a material. A higher low-temperature capacity retention and lower low-temperature impedance indicate better low-temperature performance. The quality of low-temperature performance can also be demonstrated by low-temperature discharge capability. In excessively low-temperature environments, the battery's energy is difficult to utilize, resulting in a shorter discharge time. Therefore, discharge time can be used to evaluate the battery's low-temperature performance. The low-temperature discharge capability patterns in the examples and comparative cases are consistent with those of low-temperature low SOC-DCR.

[0155] The subgrain size obtained by XRD refinement reflects the grain size of the material and can, to some extent, reflect the low-temperature variation law. In the above comparative examples and embodiments, batches with high low-temperature discharge capacity retention and low-temperature impedance all meet the requirements. And Kn 90 =(Ln 90 -Ln 10 ) / Ln 50 >1.5.

[0156] In the description of this disclosure, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this disclosure, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0157] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this disclosure. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0158] Although embodiments of the present disclosure have been shown and described above, it is to be understood that the above embodiments are exemplary and should not be construed as limiting the present disclosure. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present disclosure.

Claims

1. A cathode material, wherein, satisfy: 1.5<Kn 90 =(Ln 90 - Ln 10 ) / Ln 50 <4.5; Among them, Ln 10 、Ln 50 、Ln 90 These are the subgrain sizes Ln and Kn corresponding to the cumulative percentage of subgrain sizes Ln in the cathode material reaching 10%, 50%, and 90%, respectively. 90 It refers to the subgrain size distribution of the cathode material.

2. The cathode material according to claim 1, wherein, 3. The cathode material according to claim 1 or 2, wherein, 2.5<Kn 90 <4.0。 4. The cathode material according to any one of claims 1 to 3, wherein, The particle size P satisfies 1.0 μm < P < 2.0 μm.

5. The cathode material according to claim 4, wherein, 1.3μm < P < 1.7μm.

6. The cathode material according to any one of claims 1 to 5, wherein, The median particle size of the positive electrode material in terms of volume distribution is D'50, where 1 μm < D'50 < 4 μm.

7. The cathode material according to any one of claims 1 to 6, wherein, Including the components shown in Formula I: Li 1+a (Ni x Co y Mn z G b M c O2 Formula I Where, 0≤a≤0.2, 0≤b≤0.05, 0≤c≤0.05, 0.4≤x<1, 0 <y<0.15,0≤z<0.5, Element G includes at least one of Zr, Ti, Y, W, Al, Nb, and Sr; Element M includes at least one of La, Zr, B, Nb, Ti, W, Si, Mg, and Al.

8. The cathode material according to claim 7, wherein, It includes a substrate and a coating layer, wherein the coating layer is disposed on at least a portion of the surface of the substrate; The element M is mainly located in the coating layer.

9. The cathode material according to any one of claims 1 to 8, wherein, The cobalt concentration on the surface of the cathode material particles is greater than the cobalt concentration inside the particles.

10. The cathode material according to claim 9, wherein, Of all metallic elements except lithium, cobalt has a molar percentage greater than 0 and less than or equal to 15%.

11. The cathode material according to claim 9 or 10, wherein, Of all metallic elements except lithium, cobalt has a molar percentage greater than 0 and less than or equal to 10%.

12. A method for preparing the cathode material according to any one of claims 1 to 11, wherein, include: Nickel-cobalt-manganese precursor and lithium salt are mixed, and the resulting raw material mixture is subjected to a first sintering at 700℃~1000℃ for 6h~12h in an oxygen-containing atmosphere to obtain an intermediate product. The intermediate product, lithium source, and cobalt source are mixed, and the resulting intermediate product mixture is subjected to a second sintering at 300°C to 800°C for 6 to 12 hours in an oxygen-containing atmosphere to obtain the cathode material. Wherein, the molar ratio of lithium in the lithium source to cobalt in the cobalt source is Y, where 0.5 < Y < 1.

4.

13. The method according to claim 12, wherein, 0.8＜Y＜1.2。 14. The method according to claim 12 or 13, wherein, The lithium salt includes at least one of lithium carbonate and lithium hydroxide.

15. The method according to claim 14, wherein, The lithium salt includes a mixed lithium salt of lithium carbonate and lithium hydroxide.

16. The method according to claim 15, wherein, The lithium salt includes a mixed lithium salt of lithium carbonate and lithium hydroxide with a lithium element molar ratio of 3:7 to 8:

2.

17. The method according to any one of claims 12 to 16, wherein, The molar ratio of cobalt in the cobalt source to the sum of nickel, cobalt, and manganese in the cathode material is less than 5%.

18. The method according to any one of claims 12 to 17, wherein, The median particle size of the volume distribution of the nickel-cobalt-manganese precursor is D50, where 1 μm < D50 < 3.5 μm.

19. The method according to any one of claims 12 to 18, wherein, At least one of the following conditions must be met: The raw material mixture also includes compounds containing element G; The intermediate mixture also includes compounds containing element M.

20. The method according to claim 19, wherein, At least one of the following conditions must be met: The nickel-cobalt-manganese precursor includes at least one of nickel-cobalt-manganese oxide and nickel-cobalt-manganese hydroxide; The compound containing element G includes at least one of oxides, hydroxides, and carbonates of element G, and element G includes at least one of Zr, Ti, Y, W, Al, Nb, and Sr. The cobalt source includes at least one of cobalt oxide, cobalt tetroxide, cobalt hydroxyl oxide, and cobalt hydroxide; The lithium source includes at least one of lithium carbonate, lithium hydroxide, lithium phosphate, and lithium dihydrogen phosphate. The compound containing element M includes at least one of oxides, hydroxides, and carbonates of element M, and element M includes at least one of La, Zr, B, Nb, Ti, W, Si, Mg, and Al.

21. A lithium-ion battery, wherein, The cathode material includes any one of claims 1 to 11 or the cathode material prepared by any one of claims 12 to 20.

22. An electrical appliance, wherein, Including the lithium-ion battery as described in claim 21.

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