Electrode active material and preparation method therefor, positive electrode sheet, battery, and vehicle

Abstract

An electrode active material, comprising a compound represented by general formula (1): LiaNibCocMndLpDqO2 (1), wherein b+c+d+p+q=1, 1<a<1.1, 0≤b<1, 0<c≤1, 0≤d≤0.5, 0<p≤0.1, and 0<q≤0.1; L and D are each independently selected from one or a combination of several elements among Ti, Al, Zr, Y, Sr, Nb, W, Sb, Ce, Mg, Co, Mo and V; and the L element and the D element are different elements.

Description

Electrode active materials and their preparation methods, positive electrode sheets, batteries and vehicles

[0001] Cross-reference to related applications

[0002] This application is based on and claims priority to Chinese Patent Application No. 202510008421.7, filed on January 2, 2025, the entire contents of which are incorporated herein by reference. Technical Field

[0003] This disclosure belongs to the field of battery cathode material technology, and particularly relates to an electrode active material and its preparation method, a cathode sheet, a battery, and a vehicle. Background Technology

[0004] Currently, the electric vehicle industry is rapidly developing towards longer driving range and higher safety, leading to a significant increase in demand for power batteries. Cathode materials, as one of the four main materials for power batteries, play a crucial role in their electrical performance. For ternary cathode materials used in fast charging, a balance needs to be struck between the material's kinetic and thermodynamic stability. However, their poor high-temperature stability results in poor cycle performance and thermal stability during fast charging. Summary of the Invention

[0005] This disclosure provides an electrode active material that possesses both kinetic and thermodynamic properties, and exhibits excellent high-temperature stability.

[0006] In a first aspect, this disclosure provides an electrode active material comprising a compound of general formula (1): Li a Ni b Co c Mn d L p D q O2(1), where b+c+d+p+q=1, 1<a<1.1, 0≤b<1, 0<c≤1, 0≤d≤0.5, 0<p≤0.1, 0<q≤0.1; L and D are independently selected from one or more elements among Ti, Al, Zr, Y, Sr, Nb, W, Sb, Ce, Mg, Co, Mo, and V, and L and D are different elements.

[0007] According to an embodiment of the first aspect of this disclosure, the material thermal stability factor R of the electrode active material is greater than 30.

[0008] According to an embodiment of the first aspect of this disclosure, the particle size of the electrode active material is 2 μm to 15 μm.

[0009] Secondly, this disclosure provides a method for preparing an electrode active material, comprising: preparing a nickel-cobalt-manganese precursor Ni b Co c Mn d (OH)2, lithium source material and L source are mixed and subjected to a first sintering treatment under an atmosphere to obtain a first sintered product; wherein, 0≤b<1, 0<c≤1, 0≤d≤0.5; the first sintered product is cooled and crushed to obtain an L-doped primary cathode sintered material; the primary cathode sintered material is mixed with L source and D source and subjected to a second sintering treatment under an atmosphere to obtain a second sintered product; the second sintered product is cooled and crushed to obtain a secondary cathode sintered material co-coated with L and D elements; wherein, L and D elements are different elements; the secondary cathode sintered material is mixed with D source and subjected to a third sintering treatment under an atmosphere to obtain a D-coated electrode active material.

[0010] According to an embodiment of the second aspect of this disclosure, the method for preparing electrode active material further includes, before mixing the positive electrode secondary sintering material with the D source and performing a third sintering treatment under an atmosphere, washing the positive electrode secondary sintering material with pure water and drying it to obtain a positive electrode secondary sintering material with residual alkali removed.

[0011] According to an embodiment of the second aspect of this disclosure, the lithium source material is a combination of at least one of lithium carbonate, lithium hydroxide, lithium nitrate, and lithium oxide.

[0012] According to an embodiment of the second aspect of this disclosure, the nickel-cobalt-manganese precursor Ni b Co c Mn d (OH)₂ and lithium source material are mixed in a molar ratio of 1:(1.03 to 1.05), and the nickel-cobalt-manganese precursor Ni b Co c Mn d (OH)2 and L element in L source are mixed in a molar ratio of 1:(0.0001 to 0.03); the sintering temperature of the first sintering treatment is 700℃ to 950℃, and the sintering time is 6 hours to 12 hours.

[0013] According to an embodiment of the second aspect of this disclosure, the first sintered product is cooled to below 60°C, and the particle size of the first sintered product is crushed to a size of 2 μm to 15 μm.

[0014] According to an embodiment of the second aspect of this disclosure, the primary sintering material of the positive electrode is mixed with the L source and the D source in a molar ratio of 1:(0.0001 to 0.02):(0.0001 to 0.02), and the sintering temperature of the second sintering treatment is 400°C to 800°C, and the sintering time is 6 hours to 12 hours.

[0015] According to an embodiment of the second aspect of this disclosure, the second sintered product is cooled to below 60°C, and the particle size of the second sintered product is crushed to a size of 2 μm to 15 μm.

[0016] According to an embodiment of the second aspect of this disclosure, the positive electrode secondary sintering material is mixed with pure water at a mass ratio of (0.5 to 3):1 and then subjected to water washing treatment.

[0017] According to an embodiment of the second aspect of this disclosure, the temperature for drying the secondary sintering material of the positive electrode after removing residual alkali is 100°C to 180°C, and the drying time is 3 hours to 10 hours.

[0018] According to an embodiment of the second aspect of this disclosure, the positive electrode secondary sintering material and the D source are mixed at a mass ratio of 1:(0.0001 to 0.01), and the temperature of the third sintering treatment is 200°C to 600°C, and the sintering time is 4 hours to 12 hours.

[0019] According to an embodiment of the second aspect of this disclosure, the method for preparing the electrode active material further includes:

[0020] The electrode active material is cooled and crushed.

[0021] According to an embodiment of the second aspect of this disclosure, the electrode active material is cooled to a temperature below 60°C, and then crushed to obtain an electrode active material with a particle size of 2 μm to 15 μm.

[0022] According to an embodiment of the second aspect of this disclosure, the atmospheric conditions use an atmosphere selected from air, oxygen, or a mixture of air and oxygen.

[0023] Thirdly, this disclosure provides a positive electrode sheet, comprising: a current collector, and a positive electrode active layer containing the aforementioned electrode active material covering at least one side surface of the current collector.

[0024] According to an embodiment of the third aspect of this disclosure, the areal loading of the positive electrode is 2.0 mAh / cm². 2 Up to 5.5mAh / cm 2 .

[0025] According to an embodiment of the third aspect of this disclosure, the thickness of the positive electrode active layer is from 80 μm to 250 μm.

[0026] According to an embodiment of the third aspect of this disclosure, the positive electrode active layer comprises the electrode active material, a conductive agent, and a binder in a mass ratio of (90 to 95):(3 to 5):(0 to 7).

[0027] According to an embodiment of the third aspect of this disclosure, the conductive agent is optionally selected from conductive carbon black, Ketjen black, or a combination thereof, and the binder is optionally selected from PVDF, styrene-butadiene rubber, or a combination thereof.

[0028] Fourthly, this disclosure provides a battery including the aforementioned positive electrode.

[0029] Fifthly, this disclosure provides a vehicle including the aforementioned battery.

[0030] The method for preparing electrode active material according to the embodiments of this disclosure uses nickel-cobalt-manganese precursor Ni b Co c Mn d (OH)2, lithium source material and L source are mixed and subjected to a first sintering treatment to obtain a first sintered product; the first sintered product is then cooled and crushed to obtain an L-doped primary cathode sintered material. The primary cathode sintered material is mixed with L source and D source and subjected to a second sintering treatment, followed by cooling and crushing treatment to obtain a secondary cathode sintered material co-coated with L and D elements; the secondary cathode sintered material is mixed with D source and subjected to a third sintering treatment to obtain an electrode active material with D element coated on the surface. Finally, an electrode active material with two or more elements co-coated on the surface is obtained. The electrode active material has both kinetic and thermodynamic properties and excellent high-temperature stability. Attached Figure Description

[0031] To more clearly illustrate the technical solutions of the embodiments of this disclosure, the accompanying drawings used in the embodiments of this disclosure will be briefly introduced below. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0032] Figure 1 is a schematic flowchart of the preparation method of electrode active material according to an embodiment of the present disclosure.

[0033] Figure 2 is a schematic diagram of the test of the material thermal stability factor R provided in the embodiments of this disclosure. Detailed Implementation

[0034] The features and exemplary embodiments of various aspects of this disclosure will now be described in detail. To make the objectives, technical solutions, and advantages of this disclosure clearer, the following detailed description, in conjunction with the accompanying drawings and specific embodiments, will provide a further detailed description. It should be understood that the specific embodiments described herein are intended only to explain this disclosure and not to limit it. For those skilled in the art, this disclosure can be implemented without some of these specific details. The following description of the embodiments is merely to provide a better understanding of this disclosure by illustrating examples.

[0035] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising..." does not exclude the presence of additional identical elements in the process, method, article, or apparatus that includes said element.

[0036] Currently, the electric vehicle industry is rapidly developing towards longer driving range and higher safety, leading to a significant increase in demand for power batteries. As one of the four main materials for power batteries, cathode materials play a crucial role in their electrical performance. Improving the energy density of power batteries, extending their lifespan, and enhancing the safety and stability of materials are pressing issues that need to be addressed for cathode materials. For ternary cathode materials used in fast charging, a balance needs to be struck between the material's kinetic and thermodynamic stability; however, their poor high-temperature stability results in poor cycle performance and thermal stability during fast charging.

[0037] Hexagonal layered high-nickel ternary material LiNi x Co y Mn z O2 has attracted widespread attention due to its high energy density. The applicant of this disclosure discovered that doping ternary cathode materials can alter their crystal structure and improve their stability. Coating the ternary material provides a channel for Li ion diffusion while simultaneously blocking the active material from the electrolyte, thus protecting the material from electrolyte corrosion. This is particularly important for enhancing the material's stability and safety.

[0038] To address the problems of the prior art, this disclosure provides an electrode active material and its preparation method, a positive electrode sheet, a battery, and a vehicle. The electrode active material provided in this disclosure is described below.

[0039] In a first aspect, this disclosure provides an electrode active material comprising a compound of general formula (1): Li a Ni b Co c Mn d L p D qO2(1), where b+c+d+p+q=1, 1<a<1.1, 0≤b<1, 0<c≤1, 0≤d≤0.5, 0<p≤0.1, 0<q≤0.1; L and R are independently selected from one or more elements among Ti, Al, Zr, Y, Sr, Nb, W, Sb, Ce, Mg, Co, Mo, and V, and L and D are different elements.

[0040] The electrode active material of this disclosure is coated with two or more elements selected from L and D, which have both kinetic and thermodynamic properties, so that the electrode active material has excellent high-temperature stability even under rapid charging.

[0041] In the embodiments of this disclosure, "L element" and "D element" refer to different elements: L element is selected from one of Ti, Al, Zr, Y, Sr, Nb, W, Sb, Ce, Mg, Co, Mo, and V, or a combination of several elements; D element corresponds to an element other than L element, or a combination of elements other than L element combinations. For example, when L element is Ti, D element can be selected from one of Al, Zr, Y, Sr, Nb, W, Sb, Ce, Mg, Co, Mo, and V, or a combination of several of these elements, such as D element being Zr element, or a combination of Al and Y elements, or a combination of two or more of the remaining elements excluding Ti. As another example, if L element is Ti or Al element, D element corresponds to one selected from Zr, Y, Sr, Nb, W, Sb, Ce, Mg, Co, Mo, and V, or a combination of several of these elements, such as D element being Sr element, D element being Nb element, or D element being a combination of Zr, W, and Ce elements. That is, L element and D element are not the same type of element.

[0042] In some embodiments of this disclosure, the thermal stability factor R of the electrode active material is greater than 30. When R > 30, the electrode active material exhibits good high-temperature stability. R is the thermal stability factor of the electrode active material, defined as:

[0043] Among them, I (003) I (104)The peak intensities of the 003 and 104 peaks in the full spectrum of the electrode active material were measured using XRD. I, t1, and t2 are parameters used in the coin cell float charge test, as shown in Figure 2. I represents the value of the leakage current after it stabilizes during float charging. t1 is a time constant, representing the time from the start of constant voltage charging to the current decreasing to 10 μA. t2 is also a time constant, representing the time from the start of constant voltage charging when the leakage current decreases to a stable value to the time when the leakage current returns to 10 μA. (t2-t1) represents the time during the float charge test when the material remains stable below 10 μA. 10 μA is the preferred value, but any value between 10 μA and 20 μA can be selected to test the material's thermal stability factor.

[0044] In the embodiments of this disclosure, 003 and 104 are characteristic peaks of the electrode active material, namely the first two strong peaks among the three strong peaks in the XRD full spectrum of the electrode active material. The ratio of their characteristic peak intensities indicates the stability of the electrode active material structure; a higher value indicates a better and more stable layered structure. Using the material thermal stability factor can quickly evaluate the stability of the electrode active material and has a significant effect on shortening the material development cycle.

[0045] XRD testing methods for electrode active materials

[0046] For XRD testing of electrode active materials, the test angle ranged from 10° to 80°, and the test was performed at a scan rate of 3° / min. The I in the full spectrum of the test results was read. (003) and I (104) The value.

[0047] Button Float Charging Test Method

[0048] Prepare the coin cell battery and activate it for 2 cycles at 0.2C from 4.3 to 3.0V. Place the coin cell battery in a 60℃ oven and charge it at a constant current and constant voltage of 0.1C to 4.4V. Continue charging with CV until the leakage current returns to above 10μA from a stable value, then stop charging.

[0049] In some embodiments of this disclosure, the particle size of the electrode active material is from 2 μm to 15 μm. The particle size of the active material can be determined by laser particle size analysis, optical microscopy, or other known methods, which will not be elaborated here.

[0050] Secondly, this disclosure provides a method for preparing an electrode active material, as shown in Figure 1. The method for preparing the electrode active material includes:

[0051] S1, Ni cobalt manganese precursor b Co c Mn d(OH)2, lithium source material and L source are mixed and subjected to a first sintering treatment under atmospheric conditions to obtain the first sintered product; nickel-cobalt-manganese precursor Ni b Co c Mn d In (OH)2, 0≤b<1, 0<c≤1, 0≤d≤0.5; the first sintered product is cooled and crushed to obtain L-doped cathode primary sintered material;

[0052] S2. The primary sintering material of the positive electrode is mixed with L source and D source and subjected to a second sintering treatment under atmospheric conditions to obtain a second sintering product; the second sintering product is cooled and crushed to obtain a secondary sintering material of the positive electrode co-coated with L element and D element; wherein, L element and D element are different elements.

[0053] S4. The positive electrode secondary sintering material is mixed with the D source and subjected to a third sintering treatment under atmospheric conditions to obtain the electrode active material coated with D element.

[0054] The method for preparing electrode active material according to the embodiments of this disclosure uses nickel-cobalt-manganese precursor Ni b Co c Mn d (OH)2, lithium source material and L source are mixed and subjected to a first sintering treatment to obtain a first sintered product; the first sintered product is cooled and crushed to obtain an L-doped cathode primary sintered material; the cathode primary sintered material is mixed with L source and D source and subjected to a second sintering treatment to obtain a second sintered product; the second sintered product is cooled and crushed to obtain an L- and D-coated cathode secondary sintered material; the cathode secondary sintered material is mixed with D source and subjected to a third sintering treatment to obtain an electrode active material with D-coated surface, and thus an electrode active material with two or more elements co-coated on the surface. The electrode active material has both kinetic and thermodynamic properties and excellent high-temperature stability.

[0055] In the embodiments of this disclosure, the nickel-cobalt-manganese precursor Ni is first used. b Co c Mn d The process involves mixing (OH)₂ with an L-source and sintering it, followed by cooling and crushing to obtain a primary cathode sintered material. Then, the L-source and D-source are mixed with the primary cathode sintered material and sintered, followed by cooling and crushing to obtain a secondary cathode sintered material. Finally, the D-source is sintered with the secondary cathode sintered material to obtain the electrode active material. This disclosure utilizes different additives in successive sintering processes, which provides multiple protective effects to the electrode active material and enhances the synergistic effect of the elements in the L-source and D-source, thereby obtaining an electrode active material with excellent high-temperature stability.

[0056] In some embodiments of this disclosure, the method for preparing the electrode active material further includes, before performing a third sintering treatment on the positive electrode secondary sintering material and the D source:

[0057] S3. Use pure water to wash and dry the secondary sintering material of the positive electrode to obtain a secondary sintering material of the positive electrode with residual alkali removed.

[0058] Then, the secondary sintering material of the positive electrode after removing residual alkali is mixed with the D source and subjected to a third sintering treatment to obtain the electrode active material.

[0059] In the embodiments of this disclosure, the secondary sintering material of the positive electrode is washed with water to remove residual alkali from the surface of the secondary sintering material of the positive electrode, so as to obtain a secondary sintering material of the positive electrode with the residual alkali removed, so as to prevent the residual alkali on the surface of the secondary sintering material of the positive electrode from affecting the cycle performance and electrochemical performance of the electrode active material after it is applied to an electrochemical device (such as a battery or energy storage device).

[0060] In some embodiments of this disclosure, the lithium source material is a combination of at least one of lithium carbonate, lithium hydroxide, lithium nitrate, and lithium oxide.

[0061] In some embodiments of this disclosure, the nickel-cobalt-manganese precursor Ni b Co c Mn d (OH)₂ and lithium source material are mixed in a molar ratio of 1:(1.03 to 1.05), and the nickel-cobalt-manganese precursor Ni b Co c Mn d (OH)2 and L element in L source are mixed in a molar ratio of 1:(0.0001 to 0.03); the sintering temperature of the first sintering treatment is 700℃ to 950℃, and the sintering time is 6 hours to 12 hours.

[0062] In embodiments of this disclosure, the nickel-cobalt-manganese precursor Ni b Co c Mn d The particle size of (OH)2 is 2μm to 15μm. By giving the nickel-cobalt-manganese precursor a corresponding particle size, the sintered material obtained after corresponding sintering treatment with the L source, the subsequent L source and D source, and the D source will have a suitable particle size, as well as the final electrode active material material.

[0063] In embodiments of this disclosure, the L source is an oxide, hydroxide, carbonate, or combination thereof selected from one or more metal combinations selected from Ti, Al, Zr, Y, Sr, Nb, W, Sb, Ce, Mg, Co, Mo, and V.

[0064] In some embodiments, the L source is selected from TiO2, Ti(OH)4, Al2O3, Al(OH)3, ZrO2, Zr(OH)4, ZrCO3, Y2O3, Y(OH)3, Y2(CO3)3·X(H2O), SrO, Sr(OH)2, SrCO3, Nb2O5, Nb(OH)5, WO3, W2O3, Sb2O3, Sb(OH)3, CeO2, Ce2O3, Ce(OH)4, Ce2(CO3)3, MgO, Mg(OH)2, MgCO3, Mg2(OH)2CO3, CoO, Co3O4, Co(OH)2, Co(OH)3, CoCO3, V2O4, V2O5, V(OH)2, V(OH)3, or combinations thereof.

[0065] In embodiments of this disclosure, the nickel-cobalt-manganese precursor Ni is produced by using an L-atom selected from oxides, hydroxides, carbonates, or combinations thereof comprising one or more metal combinations selected from Ti, Al, Zr, Y, Sr, Nb, W, Sb, Ce, Mg, Co, Mo, and V. b Co c Mn d After mixing (OH)2 and lithium source material with L source and performing a first sintering treatment, at least one L-doped first sintered product is obtained. After subsequent cooling and crushing treatment, L-doped cathode primary sintered material can be obtained.

[0066] In some embodiments of this disclosure, the first sintered product is cooled to below 60°C, and the particle size of the first sintered product is crushed to a size of 2 μm to 15 μm.

[0067] In some embodiments of this disclosure, the primary sintering material of the positive electrode is mixed with the L source and the D source in a molar ratio of 1:(0.0001 to 0.02):(0.0001 to 0.02), and the sintering temperature of the second sintering treatment is 400°C to 800°C, and the sintering time is 6 hours to 12 hours.

[0068] In some embodiments of this disclosure, the secondary sintering material of the positive electrode is mixed with pure water at a mass ratio of (0.5 to 3):1 and then washed.

[0069] In some embodiments of this disclosure, the drying temperature for washing the secondary sintering material of the positive electrode with pure water and then drying it is 100°C to 180°C, and the drying time is 3 hours to 10 hours.

[0070] In some embodiments of this disclosure, the positive electrode secondary sintering material is mixed with the D source at a mass ratio of 1:(0.0001 to 0.01), the temperature of the third sintering treatment is 200°C to 600°C, and the sintering time is 4 hours to 12 hours.

[0071] In some embodiments of this disclosure, the D source is an oxide, hydroxide, carbonate, or combination thereof selected from one or more combinations of metals selected from Ti, Al, Zr, Y, Sr, Nb, W, Sb, Ce, Mg, Co, Mo, and V, wherein the D source contains different elements than the L source. For example, the L source is selected from oxides, hydroxides, carbonates, or combinations of oxides and hydroxides, or combinations of hydroxides and carbonates, or combinations of oxides and carbonates, or combinations of oxides, hydroxides, and carbonates containing Al; the D source is correspondingly selected from oxides, hydroxides, carbonates, or combinations of oxides and hydroxides, or combinations of oxides and carbonates, or combinations of oxides, hydroxides, and carbonates containing metals other than Al. In some embodiments, the L source is selected from oxides, hydroxides, carbonates, or combinations thereof of several combinations of metals selected from Ti, Al, Zr, Y, Sr, Nb, W, Sb, Ce, Mg, Co, Mo, and V, and the D source is selected from oxides, hydroxides, carbonates, or combinations thereof of one or more metals other than the L source. This allows the surface of the electrode active material to be coated with two or more elements.

[0072] In some embodiments, the D source is selected from TiO2, Ti(OH)4, Al2O3, Al(OH)3, ZrO2, Zr(OH)4, ZrCO3, Y2O3, Y(OH)3, Y2(CO3)3·X(H2O), SrO, Sr(OH)2, SrCO3, Nb2O5, Nb(OH)5, WO3, W2O3, Sb2O3, Sb(OH)3, CeO2, Ce2O3, Ce(OH)4, Ce2(CO3)3, MgO, Mg(OH)2, MgCO3, Mg2(OH)2CO3, CoO, Co3O4, Co(OH)2, Co(OH)3, CoCO3, V2O4, V2O5, V(OH)2, V(OH)3, or combinations thereof.

[0073] In some embodiments of this disclosure, the atmosphere conditions are selected from air, oxygen, or a mixture of air and oxygen. That is, the atmosphere conditions of this disclosure can be selected individually from air or oxygen, or a mixture of air and oxygen, for sintering. The first sintering process, the second sintering process, and the third sintering process of this disclosure can all adopt the above-mentioned atmosphere conditions, and the material to be sintered is subjected to the corresponding sintering treatment in an atmosphere furnace to obtain the primary positive electrode sintering material, the secondary positive electrode sintering material, and the electrode active material.

[0074] In some embodiments of this disclosure, the preparation method of the electrode active material further includes: cooling and crushing the electrode active material so that the electrode active material obtained after the third sintering treatment is cooled and crushed to refine it, and then used as an electrode active material that can be directly applied in secondary batteries or energy storage devices.

[0075] In some embodiments of this disclosure, the electrode active material can be used as the positive electrode active material in the positive electrode of a lithium battery.

[0076] The method for preparing electrode active material in this embodiment involves doping the nickel-cobalt-manganese precursor Ni with an L-source. b Co c Mn d The first sintering treatment with (OH)2 can form a uniform doping on the surface of the primary cathode sintered material, ensuring that the L element contained in the L source is uniformly doped on the core surface of the electrode active material. By adding L and D sources to the primary cathode sintered material and performing a second sintering treatment, a nano-layer of two or more elements can be formed on the surface of the secondary cathode sintered material. This results in a gradient distribution of L element from the inside out in the sintered secondary cathode sintered material, with a higher L element content in the outer layer than in the core. Adding D sources to the secondary cathode sintered material and performing a third sintering treatment further increases the D element content on the outer surface of the electrode active material. Compared to adding the D source all at once during the second sintering treatment, this results in a more uniform coating of D element on the surface of the cathode active material, avoiding the interaction between excessive D and L elements that could affect the coating effect. The electrode active material preparation method of this disclosure can be used to prepare electrode active material with a thermal stability factor R > 30, which has excellent high-temperature stability.

[0077] Thirdly, this disclosure provides a positive electrode sheet, comprising: a current collector, and a positive electrode active layer containing the aforementioned electrode active material covering at least one side surface of the current collector.

[0078] In some embodiments of this disclosure, the positive electrode active layer comprises the aforementioned electrode active material, a conductive agent, and a binder in a mass ratio of (90 to 95):(3 to 5):(0 to 7). The three materials can be dispersed into a slurry using a dispersant and then coated onto at least one side of the current collector to form the positive electrode active layer. The current collector can be aluminum foil, the conductive agent can be conductive carbon black, Ketjen black, or a combination thereof, and the binder can be PVDF, styrene-butadiene rubber, or a combination thereof. The dispersant can be N-methylpyrrolidone.

[0079] In some embodiments of this disclosure, the thickness of the positive electrode active layer is from 80 μm to 250 μm.

[0080] In some embodiments of this disclosure, the areal loading of the positive electrode is 2.0 mAh / cm². 2 Up to 5.5mAh / cm 2 .

[0081] Fourthly, this disclosure provides a battery including the aforementioned positive electrode.

[0082] In embodiments of this disclosure, the battery is a secondary battery. The secondary battery further includes a negative electrode, an electrolyte, and a separator that separates the positive electrode from the negative electrode.

[0083] Fifthly, this disclosure provides a vehicle including the aforementioned battery for powering the vehicle.

[0084] In embodiments of this disclosure, the vehicle is a pure electric vehicle, a hybrid electric vehicle, or a range-extended electric vehicle. Alternatively, the vehicle may be a two-wheeled or three-wheeled electric vehicle. For example, a hybrid electric vehicle may be a plug-in hybrid electric vehicle that includes the aforementioned battery.

[0085] Example Section

[0086] Example 1: A method for preparing an electrode active material, comprising:

[0087] S1. The polycrystalline oxide precursor, namely the nickel-cobalt-manganese precursor Ni... 0.92 Co 0.05 Mn 0.03 (OH)₂ and lithium hydroxide were mixed at a molar ratio of 1:1.05, and then Al₂O₃, accounting for 1% mol of the polycrystalline oxide precursor, was added as the L source. The mixture was sintered at 750°C for 8 hours under a pure oxygen atmosphere to obtain the first sintered product. After cooling, the first sintered product was crushed and sieved to obtain the polycrystalline primary material Li. 1.05 Ni 0.91 Co 0.05 Mn 0.03 Al 0.01 O2, which is the primary sintering material for the positive electrode doped with Al;

[0088] S2. The primary sintering material of the positive electrode is mixed with 0.2% mol TiO2 (as the D source) and 0.1% mol Al2O3 (as the L source), and sintered at 600℃ for 8 hours under a pure oxygen atmosphere to obtain the second sintered product. After cooling, the second sintered product is crushed and sieved to obtain polycrystalline Li. 1.05 Ni 0.907 Co 0.05 Mn 0.03 Al 0.011 Ti 0.002O2 refers to the secondary sintering material of the positive electrode co-coated with Al and Ti;

[0089] S3. Mix the secondary sintering material of the positive electrode and pure water at a mass ratio of 2:1 and wash them, including stirring at 300 rpm for 3 minutes and then filtering. Dry the filter cake of the secondary sintering material of the positive electrode in a vacuum oven at 150°C for 6 hours to obtain the secondary sintering material of the positive electrode with the residual alkali removed.

[0090] S4. The secondary sintering material of the positive electrode after removing residual alkali is mixed with 0.1% mol of TiO2, and sintered at 500℃ for 6 hours under a pure oxygen atmosphere to obtain the electrode active material; after cooling, the electrode active material is crushed and sieved to obtain polycrystalline Li. 1.05 Ni 0.906 Co 0.05 Mn 0.03 Al 0.011 Ti 0.003 O2 refers to Ti-coated electrode active material.

[0091] Example 2

[0092] The difference from Example 1 is that the polycrystalline oxide precursor in S1 is replaced with Ni. 0.88 Co 0.09 Mn 0.05 (OH)2.

[0093] Example 3

[0094] The difference from Example 1 is that TiO2 in S2 and S4 is replaced with W2O3.

[0095] Example 4

[0096] The difference from Example 1 is that Al2O3 in S1 and S2 is replaced with Nb2O5.

[0097] Example 5

[0098] The difference from Example 1 is that the amount of TiO2 added in S2 is 0.5% mol of the primary sintering material of the positive electrode, and the amount of TiO2 added in S4 is 0.2% mol of the secondary sintering material of the positive electrode after removing residual alkali.

[0099] Example 6

[0100] The difference from Example 1 is that the amount of TiO2 added in S2 is 0.7% mol of the primary sintering material of the positive electrode, and the amount of TiO2 added in S4 is 0.3% mol of the secondary sintering material of the positive electrode after removing residual alkali.

[0101] Example 7

[0102] The difference from Example 1 is that the amount of Al2O3 added in S1 is 1.5% mol of the polycrystalline oxide precursor, and the amount of Al2O3 added in S2 is 0.2% mol of the primary sintering material of the positive electrode.

[0103] Comparative Example 1

[0104] The difference from Example 1 is that TiO2 is not added in steps S2 and S3.

[0105] Comparative Example 2

[0106] The difference from Example 1 is that Al2O3 is not added in steps S1 and S2.

[0107] Performance testing

[0108] Preparation of coin cell

[0109] Electrode active materials provided in Examples 1 to 7 and modified positive electrode active materials, conductive carbon black, and PVDF (polyvinylidene fluoride) provided in Comparative Examples 1 to 2, in a mass ratio of 92:5:3, were respectively mixed with a certain amount of N-methylpyrrolidone (NMP), coated onto aluminum foil, and dried to form a positive electrode sheet with a positive active layer thickness of 100 μm and an areal loading of 3.8 mAh / cm². 2 Up to 4.2mAh / cm 2 Then, the positive electrode, a PP separator with a thickness of 24 μm, an electrolyte (EC:EMC:DEC mass ratio = 1:1:1, 12.5 wt.% LiPF6), and a lithium sheet were assembled into a button half-cell in a glove box, left to stand for 12 hours, and the performance of the battery was tested.

[0110] Button half-cell float charge test

[0111] Prepare the coin cell battery and activate it for 2 cycles at 0.2C from 4.3 to 3.0V. Place the coin cell battery in a 60℃ oven and charge it at a constant current and constant voltage of 0.1C to 4.4V. Continue charging with CV until the leakage current returns to above 10μA from a stable value, then stop charging.

[0112] The electrode active materials of Examples 1 to 7 and the modified positive electrode active materials of Comparative Examples 1 to 2 were applied to coin cells, and some parameters and test results were recorded in Table 1 below:

[0113] Table 1. Performance Comparison of Electrode Active Materials in Examples 1 to 7 and Modified Positive Electrode Active Materials in Comparative Examples 1 to 2

[0114] Table 1 shows that the electrode active materials prepared in Examples 1 to 7 of this disclosure have an initial discharge specific capacity of 218 mAh / g to 225 mAh / g when applied to coin cells, which is similar to the initial discharge specific capacity of 223 mAh / g to 225 mAh / g of the modified positive electrode active materials in Comparative Examples 1 and 2 when applied to coin cells. The electrode active materials prepared in Examples 1 to 7 retain a capacity of 97.8% to 99.1% after 80 cycles in coin cells. Except for the ternary positive electrode active material in Example 4, which retains a capacity of 97.8% after 80 cycles in coin cells, the capacity retention rates of the other examples are also relatively high. The electrode active materials 1 to 3 and 5 to 7, when applied to coin cells, all exhibited a capacity retention rate of over 98% after 80 cycles, significantly higher than the 96.1% to 96.8% capacity retention rate of the modified positive electrode active materials of Comparative Examples 1 and 2 after 80 cycles. This indicates that the electrode active materials co-coated with two elements prepared in Examples 1 to 7 of this disclosure have better cycle stability when the initial discharge specific capacity is similar, with a capacity retention rate still exceeding 98% after 80 cycles. It also indicates that the cycle stability of coin cells prepared using modified positive electrode active materials doped with a single metal element is relatively poor.

[0115] The electrode active materials prepared in Comparative Examples 1 to 7, when applied to coin cells, all had a thermal stability factor R greater than 30, and the corresponding coin cells retained a capacity of 96.9% to 98.8% after storage at 60°C for 15 days. The modified cathode active materials in Comparative Examples 1 and 2, when applied to coin cells, had thermal stability factors R of 15 and 8 respectively, both less than 30, and the corresponding coin cells retained a capacity of 95.3% to 94.5% after storage at 60°C for 15 days. From the comparison of the material thermal stability factors and the corresponding cathode materials' capacity retention rates after storage at 60°C for 15 days, it can be concluded that: The electrode active materials with a thermal stability factor R > 30 prepared in Examples 1 to 7, after being applied to coin cells and stored at 60°C for 15 days, exhibited significantly higher capacity retention than the modified positive electrode active materials with a thermal stability factor R < 30 prepared in Comparative Examples 1 to 2, after being applied to coin cells and stored at 60°C for 15 days. This indicates that the preparation methods of Examples 1 to 7 of this disclosure can prepare electrode active materials co-coated with two elements, and possess excellent high-temperature stability, maintaining a capacity retention of at least 96.9% to 98.8% after storage at 60°C for 15 days.

[0116] Comparing Examples 1 and 2, the R-value of the electrode active material prepared in Example 2 is 179, which is greater than the R-value of 73 of the electrode active material prepared in Example 1. This indicates that the high-temperature stability of the electrode active material prepared using the nickel-cobalt-manganese precursor of Example 2 is higher than that of the electrode active material prepared using the nickel-cobalt-manganese precursor of Example 1. Comparing Examples 1 and 3, it can be seen that when W2O3 is used as the D source, the high-temperature stability of the prepared electrode active material is relatively weakened, but still higher than that of the modified positive electrode active materials prepared in Comparative Examples 1 and 2. Comparing Examples 1 and 4, it can be seen that the R-value of the electrode active material prepared using Nb2O5 as the L source is 38, indicating that its high-temperature stability is relatively weak, but still higher than that of the modified positive electrode active materials prepared in Comparative Examples 1 and 2. Comparing Examples 1, 5, 6, and 7, increasing the amount of L source and D source respectively significantly increases the R-value of the prepared electrode active material, indicating that appropriately increasing the content of L and D elements in the electrode active material can improve the high-temperature stability of the electrode active material.

[0117] The above description is merely a specific embodiment of this disclosure. Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working process described above can be referred to the corresponding process in the foregoing method embodiments, and will not be repeated here. It should be understood that the protection scope of this disclosure is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in this disclosure, and these modifications or substitutions should all be covered within the protection scope of this disclosure.

Claims

1. An electrode active material comprising a compound of general formula (1): Li a Ni b Co c Mn d L p D q O2(1), in, b+c+d+p+q=1, 1<a<1.1, 0≤b<1, 0<c≤1, 0≤d≤0.5, 0<p≤0.1, 0<q≤0.1; L and D are independently selected from one or more elements selected from Ti, Al, Zr, Y, Sr, Nb, W, Sb, Ce, Mg, Co, Mo, V, and L and D are different elements.

2. The electrode active material according to claim 1, wherein, The material thermal stability factor R of the electrode active material is greater than 30.

3. The electrode active material according to claim 1 or 2, wherein, The particle size of the electrode active material is 2 μm to 15 μm.

4. A method for preparing an electrode active material as described in any one of claims 1 to 3, comprising: Ni, a nickel-cobalt-manganese precursor b Co c Mn d (OH)2, lithium source material and L source are mixed and subjected to a first sintering treatment under atmospheric conditions to obtain a first sintered product; the nickel-cobalt-manganese precursor Ni b Co c Mn d In (OH)2, 0≤b<1, 0<c≤1, 0≤d≤0.5; the first sintered product is cooled and crushed to obtain L-doped cathode primary sintered material; The primary sintering material of the positive electrode is mixed with L source and D source and subjected to a second sintering treatment under atmospheric conditions to obtain a second sintering product; the second sintering product is subjected to cooling and crushing treatment to obtain a secondary sintering material of the positive electrode co-coated with L element and D element; wherein, L element and D element are different elements; The positive electrode secondary sintering material is mixed with the D source and subjected to a third sintering treatment under atmospheric conditions to obtain an electrode active material coated with D element.

5. The preparation method according to claim 4, wherein, Before mixing the positive electrode secondary sintering material with the D source and performing the third sintering treatment under the atmosphere conditions, the process further includes: The positive electrode secondary sintering material was washed with pure water and dried to obtain a positive electrode secondary sintering material with residual alkali removed.

6. The preparation method according to claim 4 or 5, wherein, The lithium source material is a combination of at least one of lithium carbonate, lithium hydroxide, lithium nitrate, and lithium oxide; and / or The nickel-cobalt-manganese precursor Ni b Co c Mn d (OH)₂ and the lithium source material are mixed in a molar ratio of 1:(1.03 to 1.05), and the nickel-cobalt-manganese precursor Ni b Co c Mn d (OH)₂ and the L element in the L source are mixed in a molar ratio of 1:(0.0001 to 0.03); the sintering temperature of the first sintering treatment is 700°C to 950°C, and the sintering time is 6 hours to 12 hours; and / or The L source is an oxide, hydroxide, carbonate, or combination thereof selected from one or more metal combinations comprising Ti, Al, Zr, Y, Sr, Nb, W, Sb, Ce, Mg, Co, Mo, and V; and / or The first sintered product is cooled to below 60°C and then crushed to a particle size of 2μm to 15μm.

7. The preparation method according to any one of claims 4 to 6, wherein, The primary sintering material of the positive electrode is mixed with the L source and the D source at a molar ratio of 1:(0.0001 to 0.02):(0.0001 to 0.02). The sintering temperature of the second sintering treatment is 400°C to 800°C, and the sintering time is 6 hours to 12 hours; and / or The positive electrode secondary sintering material is mixed with the D source at a mass ratio of 1:(0.0001 to 0.01), and the third sintering treatment is performed at a temperature of 200°C to 600°C for a sintering time of 4 hours to 12 hours; and / or The D source is an oxide, hydroxide, carbonate, or combination thereof selected from one or more of the metals selected from Ti, Al, Zr, Y, Sr, Nb, W, Sb, Ce, Mg, Co, Mo, and V.

8. The preparation method according to claim 5, wherein, The drying temperature is 100°C to 180°C, and the drying time is 3 to 10 hours.

9. The preparation method according to any one of claims 4 to 8, wherein, The L source and the D source are independently selected from TiO2, Ti(OH)4, Al2O3, Al(OH)3, ZrO2, Zr(OH)4, ZrCO3, Y2O3, Y(OH)3, Y2(CO3)3·X(H2O), SrO, Sr(OH)2, SrCO3, Nb2O5, Nb(OH)5, WO3, W2O3, Sb2O3, Sb(OH)3, CeO2, Ce2O3, Ce(OH)4, Ce2(CO3)3, MgO, Mg(OH)2, MgCO3, Mg2(OH)2CO3, CoO, Co3O4, Co(OH)2, Co(OH)3, CoCO3, V2O4, V2O5, V(OH)2, V(OH)3, or combinations thereof.

10. The preparation method according to any one of claims 4 to 9, wherein, It also includes: cooling and crushing the electrode active material.

11. The preparation method according to claim 10, wherein, The electrode active material is cooled to below 60°C and then crushed to obtain an electrode active material with a particle size of 2μm to 15μm.

12. A positive electrode plate, comprising: Current collector, and A positive electrode active layer comprising the electrode active material as described in any one of claims 1 to 3, covering at least one side surface of the current collector.

13. The positive electrode sheet according to claim 12, wherein, The positive electrode sheet satisfies at least one of the following conditions: The areal loading of the positive electrode is 2.0 mAh / cm². 2 Up to 5.5mAh / cm 2 ; and / or The thickness of the positive electrode active layer is 80 μm to 250 μm; and / or The positive electrode active layer comprises the electrode active material, a conductive agent, and a binder in a mass ratio of (90 to 95):(3 to 5):(0 to 7); and / or The current collector may be aluminum foil, the conductive agent may be selected from conductive carbon black, Ketjen black or a combination thereof, and the binder may be selected from PVDF, styrene-butadiene rubber or a combination thereof.

14. A battery comprising a positive electrode as described in claim 12 or 13.

15. A vehicle comprising the battery as claimed in claim 14.

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