A positive electrode additive, a composite positive electrode material, a preparation method and a lithium ion battery

Abstract

The application relates to a positive electrode additive, a composite positive electrode material, a preparation method and a lithium ion battery. The composition of the positive electrode additive comprises Li x M1 a M2 b Al c O ((x+y) / 2) , wherein M1 comprises V, Cr, Mn, Fe, Co, Ni or Cu, M2 comprises La, Zr, Nb, Ti, Y, Ta or W, y represents the average valence of M1, M2 and Al, 2.8<=y<=4.5, 0.1<=x<=0.9, 0.2<=a<=0.4, 0.2<=b<=0.4, 0.2<=c<=0.4, and a+b+c=1. The application constructs a composite component oxide by introducing Li, M1 elements, M2 elements and Al in the positive electrode additive. When the positive electrode additive is used as a positive electrode additive, the positive electrode material is doped and / or coated with good consistency, and the electronic conductivity, ionic conductivity and structural stability can be improved at the same time.

Description

Technical Field

[0001] This invention relates to the field of lithium-ion battery technology, specifically to cathode materials, and more particularly to a cathode additive, a composite cathode material, a preparation method, and a lithium-ion battery. Background Technology

[0002] Cathode materials are a core component of lithium-ion batteries, and their electrochemical performance directly determines the energy density, cycle life, and safety performance of lithium-ion batteries. Therefore, modifying and optimizing cathode materials has become a key approach to improving the overall performance of lithium-ion batteries. Currently, the industry commonly uses metal oxide doping or surface coating to modify cathode materials in order to improve their structural stability, ionic conductivity, and electronic conductivity, thereby enhancing their overall electrochemical performance and meeting the ever-increasing performance demands of lithium-ion batteries.

[0003] However, existing doping and coating processes for metal oxide additives still have significant drawbacks. On the one hand, the content of some functional additive elements is extremely low, which can easily lead to local segregation and uneven dispersion during doping and coating, making it difficult to achieve uniform distribution in cathode materials and resulting in unstable modification effects. On the other hand, when additives are doped or coated in different cathode material systems, they will undergo side reactions with the matrix to varying degrees, causing changes in interface structure and crystal phase. The impact of these changes on material performance is difficult to control precisely, limiting further improvement in modification effects.

[0004] CN115911393A discloses a method for preparing co-doped cathode materials. This method employs an acidic organic acid complexing agent and a reducing organic reducing complexing agent to sequentially crosslink nickel, cobalt, manganese, and M source compounds. A sol-gel method is used, and nitrogen (N) is introduced for co-doping. Both dopant elements enter the layered structure framework from the initial formation process, resulting in a uniform distribution of the co-doped elements in the bulk phase of the cathode material. This ensures a uniform distribution of at least two dopant elements, stabilizes the material structure, and ultimately yields a co-doped cathode material with good single-crystal morphology and high rate performance.

[0005] CN121506875A discloses a positive electrode sheet, a battery including the positive electrode sheet, and an electrical device. By doping and / or surface-coating element M in lithium nickel cobalt manganese oxide particles, and controlling the bond energy between element M and O to be greater than that between Ni and O, and ensuring that after 200 cycles, the percentage of Fd3m phase thickness to the diameter of lithium nickel cobalt manganese oxide particles (a%) and the ratio of the mass percentage of M to the relative mass percentage of Ni in the positive electrode material (b) satisfy a specific relationship, the structural stability of lithium nickel cobalt manganese oxide is significantly improved, resulting in higher lithium-ion transport efficiency, better fast-charging performance, and higher capacity performance.

[0006] CN121451273A discloses a method for preparing a high-efficiency small-particle single-crystal ultra-high nickel ternary cathode material. Specifically, a Li2WO4 layer is coated on the surface of lithium nickel cobalt manganese oxide material to suppress interfacial side reactions between small-particle single crystals and the electrolyte. At the same time, some W elements are incorporated into the bulk phase of the material. The high-valence W atoms enhance structural stability and prevent the collapse of the transition metal layer, thereby improving the first coulombic efficiency. The introduction of W elements can also increase the crystal growth energy barrier, effectively inhibiting the growth of single crystal particles and enhancing cycle performance by relying on the small-sized single crystal structure. In addition, the use of mechanical pressing to compact the precursor can reduce the interfacial fusion resistance of material growth, reduce the high-temperature calcination time to alleviate lithium-nickel mixing, and the four-segment programmed temperature control calcination can eliminate oxygen vacancies and lattice distortion, further improving the orderliness of the layered structure.

[0007] In existing technologies, the doping coating effect is usually improved by controlling the doping method and selecting the doping element, while there are few technical solutions that control the doping source and / or coating source itself.

[0008] Therefore, it is of great significance to provide a cathode additive for doping and / or coating cathode materials and a method for preparing the same. Summary of the Invention

[0009] To address the shortcomings of existing technologies, the present invention aims to provide a cathode additive, a composite cathode material, a preparation method, and a lithium-ion battery. The present invention constructs a composite oxide component by introducing Li, M1, M2, and Al elements into the cathode additive. M1 is a key element for improving electronic conductivity, M2 is a core element for enhancing ionic conductivity, and Al is an important element for ensuring structural stability. Therefore, when this cathode additive is used as a doping and / or coating additive, it can simultaneously improve electronic conductivity, ionic conductivity, and structural stability without the need for multiple additives, resulting in uniform doping and / or coating effects.

[0010] To achieve this objective, the present invention adopts the following technical solution:

[0011] In a first aspect, the present invention provides a positive electrode additive, the composition of which includes Li x M1 a M2 b Al c O ((x+y) / 2) M1 includes any one or at least two of V, Cr, Mn, Fe, Co, Ni or Cu, M2 includes at least two of La, Zr, Nb, Ti, Y, Ta or W, y represents the average valence of M1, M2 and Al, 2.8≤y≤4.5, 0.1≤x≤0.9, 0.2≤a≤0.4, 0.2≤b≤0.4, 0.2≤c≤0.4, a+b+c=1.

[0012] This invention introduces element M1 to enhance electronic conductivity, element M2 to enhance ionic conductivity, and element Al to enhance structural stability. These elements, along with Li, form a composite oxide as a cathode additive. When doping and / or coating cathode materials, this improves the uniformity of doping and / or coating, enabling simultaneous enhancement of electronic and ionic conductivity. Furthermore, the synergistic pinning effect of M1 and M2 anchors the structural components of the material, thereby improving structural stability.

[0013] Preferably, the electronic conductivity of the positive electrode additive is ≥1×10⁻⁶. -6 S / cm, ionic conductivity ≥5×10 -6 S / cm.

[0014] Preferably, the primary particles of the positive electrode additive have a D50 particle size of 30nm to 600nm.

[0015] In a second aspect, the present invention provides a method for preparing the positive electrode additive as described in the first aspect, the method comprising:

[0016] In an oxygen-containing atmosphere, lithium source, M1 source, M2 source and aluminum source are mixed in stoichiometric ratio and sintered to obtain the cathode additive.

[0017] This invention prepares a composite oxide as a cathode additive by sintering a lithium source, M1 source, M2 source and an aluminum source. Compared with a simple mixture of lithium source, M1 source, M2 source and aluminum source, the cathode additive obtained by sintering has better compositional consistency, better doping and / or coating uniformity, and better ionic conductivity and electronic conductivity.

[0018] Preferably, the sintering temperature is 300℃~600℃.

[0019] Preferably, the sintering time is 5h to 20h.

[0020] Preferably, the oxygen-containing atmosphere includes air and / or oxygen.

[0021] Preferably, the lithium source includes any one or a combination of at least two of lithium oxide, lithium hydroxide, lithium carbonate, or lithium acetate.

[0022] Preferably, the M1 source includes any one or a combination of at least two of the oxides, hydroxides or carbonates of M1.

[0023] Preferably, the M2 source includes any one or a combination of at least two of the oxides, hydroxides or carbonates of M2.

[0024] Preferably, the aluminum source includes aluminum oxide and / or aluminum hydroxide.

[0025] Thirdly, the present invention provides a method for preparing a composite cathode material, the method comprising:

[0026] The composite cathode material is obtained by mixing the cathode material with the cathode additives described in the first aspect and then heat-treating it.

[0027] In this invention, composite component oxides are used as cathode additives to dope and / or coat cathode materials without the need for other additives. This achieves improvements in the electronic conductivity, ionic conductivity, and structural stability of the cathode materials. The doping and / or coating uniformity is good, and the pre-prepared cathode additives avoid side reactions between raw materials and between raw materials and the cathode, thus improving the consistency of the composite cathode material's performance.

[0028] Preferably, the amount of the positive electrode additive is 0.1wt% to 1.5wt% of the mass of the positive electrode material.

[0029] Preferably, the temperature of the heat treatment is 300℃~1000℃.

[0030] Preferably, when the positive electrode additive is used to coat the positive electrode material, the temperature of the heat treatment is 300℃~800℃.

[0031] Preferably, when the positive electrode additive is used to dope the positive electrode material, the temperature of the heat treatment is 600℃~1000℃.

[0032] Preferably, the heat treatment time is 3h to 20h.

[0033] Preferably, when the positive electrode additive is used to coat the positive electrode material, the heat treatment time is 3h to 15h.

[0034] Preferably, when the positive electrode additive is used to dope the positive electrode material, the heat treatment time is 5h to 20h.

[0035] Fourthly, the present invention provides a composite cathode material, which is prepared by the preparation method described in the third aspect.

[0036] Fifthly, the present invention provides a lithium-ion battery comprising the composite cathode material as described in the fourth aspect.

[0037] Compared with the prior art, the present invention has the following beneficial effects:

[0038] (1) This invention introduces element M1 to improve electronic conductivity, element M2 to improve ionic conductivity, and element Al to improve structural stability, and constructs a composite component oxide with Li as a positive electrode additive. When the positive electrode material is doped and / or coated, the uniformity of doping and / or coating is improved, and the electronic conductivity and ionic conductivity can be improved simultaneously. At the same time, through the synergistic pinning effect of M1 and M2, the structural components of the material are anchored, and the structural stability is improved.

[0039] (2) The present invention prepares composite component oxides as cathode additives by sintering lithium source, M1 source, M2 source and aluminum source. Compared with a simple mixture of lithium source, M1 source, M2 source and aluminum source, the cathode additives obtained by sintering have better composition consistency, better doping and / or coating uniformity, and better ionic conductivity and electronic conductivity, thus improving the consistency of composite cathode material performance. Attached Figure Description

[0040] Figure 1 This is a backscattered image of the composite cathode material provided in Example 1, obtained from EPMA testing.

[0041] Figure 2 This is the EPMA spectrum of the Co element distribution in the composite cathode material provided in Example 1.

[0042] Figure 3 This is the EPMA spectrum of the Zr element distribution in the composite cathode material provided in Example 1.

[0043] Figure 4 This is the EPMA spectrum of the W element distribution in the composite cathode material provided in Example 1.

[0044] Figure 5 This is the EPMA spectrum of the Al element distribution in the composite cathode material provided in Example 1.

[0045] Figure 6 This is the first charge-discharge curve of the lithium-ion battery prepared from the composite cathode material provided in Example 1. Detailed Implementation

[0046] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0047] The scope of this invention can be defined by lower and upper limits. The selected lower and upper limits define the boundaries of a specific range. The range defined in this way can be defined by the inclusion or exclusion of endpoints. Any endpoint can be independently selected for inclusion or exclusion, and all lower and upper limits can be arbitrarily combined to form new ranges. That is, any lower limit can be combined with any upper limit to form an effective range. For example, if the ranges of 60~120 and 80~110 are listed for specific parameters, it should be understood that the ranges of 60~110 and 80~120 also fall within the scope of this invention. In addition, if the minimum range values ​​1 and 2 are listed, and the maximum range values ​​3, 4 and 5 are also listed, then all ranges of 1~3, 1~4, 1~5, 2~3, 2~4 and 2~5 fall within the scope of this invention. In this invention, the numerical range "a~b" represents a shortened representation of any combination of real numbers between a and b, where a and b are both real numbers. For example, the numerical range "0~5" means that all real numbers between 0 and 5 have been fully listed in this document, and "0~5" is only a shortened representation of this set of numerical combinations. When a parameter is expressed as an integer ≥2, it is equivalent to listing positive integers that meet the requirements, such as 2, 3, 4, 5, 6, 7, 8, 9, 10, etc. When a parameter is expressed as an integer selected from "2~10", it is equivalent to listing any integer among 2, 3, 4, 5, 6, 7, 8, 9, and 10.

[0048] In this invention, "a combination of at least two" refers to a quantity greater than or equal to 2 unless otherwise specified. For example, "any one or a combination of at least two" means that any one of the listed items can be selected, or a combination of at least two of the listed items formed in a manner that does not conflict and enables the implementation of this invention. In this invention, unless otherwise specified, the features or solutions corresponding to "and / or" cover any one of two or more related listed items, as well as any and all combinations of the related listed items. The arbitrary and all combinations include any two related listed items, any more related listed items, or a combination of all related listed items. For example, "A and / or B" means a set consisting of A, B, and combinations of A and B, where "containing A and / or B" can be understood, depending on the context of the statement, as containing A, containing B, or simultaneously containing both A and B. In this invention, "optional" means that the corresponding feature, component, step or solution is not necessary, that is, it is selected from either "with" or "without". If there are multiple "optional" limitations in a technical solution, unless otherwise specified and there is no technical conflict or mutual constraint, each "optional" limitation is independent and does not affect the others.

[0049] In this invention, technical features or solutions described using open-ended terms such as "comprising" or "including" do not exclude additional non-conflicting elements beyond the listed elements unless otherwise specified. They are considered to disclose both closed-ended features or solutions consisting solely of the listed elements and open-ended features or solutions that may include additional non-conflicting elements beyond the listed elements. For example, if A includes a1, a2, and a3, unless otherwise specified, this means that A can consist only of a1, a2, and a3, or it can include other non-conflicting elements based on a1, a2, and a3. This corresponds to the disclosure of technical solutions such as "A consists of a1, a2, and a3," "A is selected from a1, a2, and a3," and "A not only includes a1, a2, and a3, but may also include other non-conflicting elements." All embodiments and optional embodiments of this invention, unless otherwise specified and without technical conflict, can be combined to form new technical solutions, and such combinations fall within the scope of this invention. The term "embodiment" as used in this invention means that a specific feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment or implementation of the invention. The appearance of this phrase in various locations throughout the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments. Those skilled in the art will understand, explicitly and implicitly, that the embodiments described in this invention can be combined with other embodiments that do not conflict with the technology. The ordinal numbers "first," "second," "third," and "fourth," etc., used in the expressions "first aspect," "second aspect," "third aspect," and "fourth aspect" in this invention are for descriptive purposes only and should not be construed as indicating or implying relative importance or quantity, nor should they be construed as implicitly specifying the importance or quantity of the indicated technical features. They serve only as a non-exhaustive enumeration and do not constitute a closed limitation on quantity.

[0050] In this invention, the order in which the steps are written in the methods described in each embodiment does not imply a strict execution order. The actual execution order of each step should be determined based on its function and possible internal logic. Unless otherwise specified, all steps of this invention can be executed in the order they are written, or in any order without technical conflict. For example, if the method includes steps (a) and (b), it means that the method may include steps (a) and (b) executed sequentially, or it may include steps (b) and (a) executed sequentially. If the method also includes step (c), then step (c) can be added to the method in any order without conflict, including but not limited to the execution order of steps (a), (b), and (c), steps (a), (c), and (b), steps (c), (a), and (b), etc.

[0051] In a first specific embodiment, the present invention provides a positive electrode additive, the composition of which includes Li x M1 a M2b Al c O ((x+y) / 2) M1 includes any one or at least two of V, Cr, Mn, Fe, Co, Ni or Cu, and M2 includes at least two of La, Zr, Nb, Ti, Y, Ta or W. y represents the average valence of M1, M2 and Al, and 2.8 ≤ y ≤ 4.5. For example, it can be 2.8, 2.9, 3, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4, 4.1, 4.2, 4.3, 4.4 or 4. 5. 0.1≤x≤0.9, for example, it can be 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8 or 0.9; 0.2≤a≤0.4, for example, it can be 0.2, 0.25, 0.3, 0.35 or 0.4; 0.2≤b≤0.4, for example, it can be 0.2, 0.25, 0.3, 0.35 or 0.4; 0.2≤c≤0.4, for example, it can be 0.2, 0.25, 0.3, 0.35 or 0.4; a+b+c=1.

[0052] For example, the positive electrode additive provided by the present invention includes: Li 0.1 V 0.2 La 0.1 Ta 0.3 Al 0.4 O 2.05 Li 0.3 Cr 0.4 Zr 0.15 W 0.2 Al 0.25 O 2.03 Li 0.5 Mn 0.25 Nb 0.2 La 0.2 Al 0.35 O 1.98 Li 0.9 Cr 0.3 Y 0.1 La 0.2 Ta 0.1 Al 0. 3O 2.15 Li 0.7 Fe 0.4 Ti 0.25 Zr 0.05 Al 0.3 O 1.88 Li 0.9 Co 0.3 Y 0.1 La 0.2 Ta 0.1 Al 0.3 O 2.15 Li0.3 Co 0.4 Zr 0.15 W 0.2 Al 0.25 O 2.0 Li 0.1 Ni 0.4 Nb 0.1 Ti 0.15 Al 0.35 O 1.45 Li 0.3 Cu 0.35 Ta 0.2 Nb 0.2 Al 0.25 O 1.78 Li 0.5 V 0.4 W 0.1 Ti 0.1 Al 0.4 O 2.30 Li 0.7 Cr 0.25 La 0.15 Y 0.2 Al 0.4 O 2.05 Or Li 0.9 Mn 0.35 W 0.35 Nb 0.05 Al 0.25 O 2.70 Any one or at least two of them.

[0053] This invention introduces element M1 to improve electronic conductivity, element M2 to improve ionic conductivity, and element Al to improve structural stability, and constructs a composite oxide with Li as a positive electrode additive. When the positive electrode material is doped and / or coated, the electronic conductivity, ionic conductivity and structural stability can be improved simultaneously, and the doping and / or coating effect is uniform.

[0054] In some embodiments, the electronic conductivity of the positive electrode additive is ≥1×10⁻⁶. -6 S / cm, for example, could be 1×10 -6 S / cm, 2×10 -6 S / cm, 3×10 -6 S / cm, 4×10 -6 S / cm, 5×10 -6 S / cm, 6×10 -6 S / cm, 7×10 -6 S / cm, 8×10 -6 S / cm, 9×10 -6 S / cm, 1×10 -5 S / cm, 3×10-5 S / cm, 5×10 -5 S / cm, 7×10 -5 S / cm, 9×10 -5 S / cm, 1×10 -4 S / cm; Ionic conductivity ≥5×10 -6 S / cm, for example, could be 5×10 -6 S / cm, 6×10 -6 S / cm, 7×10 - 6 S / cm, 8×10 -6 S / cm, 9×10 -6 S / cm, 1×10 -5 S / cm, 3×10 -5 S / cm, 5×10 -5 S / cm, 7×10 -5 S / cm, 1×10 -4 S / cm, 2×10 -4 S / cm, 5×10 -4 S / cm, 7×10 -4 S / cm or 9×10 -4 S / cm.

[0055] In some embodiments, the D50 particle size of the primary particles of the positive electrode additive is 30nm~600nm, for example, it can be 30nm, 50nm, 100nm, 200nm, 300nm, 400nm, 500nm, or 600nm.

[0056] In another specific embodiment, the present invention provides a method for preparing the positive electrode additive as described in the first specific embodiment above, the preparation method comprising:

[0057] In an oxygen-containing atmosphere, lithium source, M1 source, M2 source and aluminum source are mixed in stoichiometric ratio and sintered to obtain the cathode additive.

[0058] This invention prepares a composite oxide as a cathode additive by sintering lithium source, M1 source, M2 source and aluminum source. Compared with a simple mixture of lithium source, M1 source, M2 source and aluminum source, it has better composition consistency, better doping and / or coating uniformity, and better ionic conductivity and electronic conductivity.

[0059] In some embodiments, the sintering temperature is 300°C to 600°C, for example, it can be 300°C, 350°C, 400°C, 450°C, 500°C, 550°C or 600°C.

[0060] In some embodiments, the sintering time is 5h to 20h, for example, it can be 5h, 7h, 9h, 10h, 12h, 14h, 16h, 18h or 20h.

[0061] In some embodiments, the oxygen-containing atmosphere includes air and / or oxygen.

[0062] In some embodiments, the lithium source includes any one or a combination of at least two of lithium oxide, lithium hydroxide, lithium carbonate, or lithium acetate.

[0063] In some embodiments, the M1 source includes any one or a combination of at least two of the oxides, hydroxides, or carbonates of M1. Exemplarily, the M1 source includes any one or a combination of at least two of V2O5, Cr2O3, Cr(OH)3, MnO2, Mn3O4, Mn(OH)2, MnCO3, Fe2O3, Fe3O4, Fe(OH)3, FeCO3, Co2O3, Co3O4, Co(OH)2, Co(OH)3, CoCO3, NiO, Ni(OH)2, NiCO3, CuO, Cu(OH)2, or Cu2(OH)2CO3.

[0064] In some embodiments, the M2 source includes any one or a combination of at least two of the oxides, hydroxides, or carbonates of M2. Exemplarily, the M2 source includes a combination of at least two of La2O3, La(OH)3, La2(CO3)3, ZrO2, Zr(OH)4, Nb2O5, TiO2, Ti(OH)4, Y2O3, Y(OH)3, Y2(CO3)3, Ta2O5, or WO3.

[0065] In some embodiments, the aluminum source includes aluminum oxide and / or aluminum hydroxide.

[0066] In some embodiments, the mixing method includes any one or a combination of at least two of ball milling, sand milling, or air jet milling.

[0067] In some embodiments, the crushing includes mechanical crushing or air jet crushing.

[0068] In a third specific embodiment, the present invention provides a method for preparing a composite cathode material, the method comprising:

[0069] The composite cathode material is obtained by mixing the cathode material with the cathode additive described in the first specific embodiment and then heat-treating it.

[0070] In this invention, composite component oxides are used as cathode additives to dope and / or coat cathode materials without the need for other additives. This can improve the electronic conductivity, ionic conductivity and structural stability of cathode materials, and the doping and / or coating uniformity is good. Furthermore, the cathode additives are prepared in advance, avoiding side reactions between raw materials and between raw materials and cathode materials, thus improving the consistency of the performance of composite cathode materials.

[0071] In this invention, the type of cathode material doped and / or coated by the cathode additive is not specifically limited. For example, the cathode material includes any one or a combination of at least two of lithium nickel oxide, lithium cobalt oxide, lithium manganese oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, lithium nickel manganese aluminum oxide, lithium nickel cobalt manganese aluminum oxide, lithium iron phosphate, lithium manganese iron phosphate, or lithium-rich manganese-based cathode materials.

[0072] In some embodiments, the amount of the positive electrode additive is 0.1wt% to 1.5wt% of the mass of the positive electrode material, for example, it can be 0.1wt%, 0.3wt%, 0.5wt%, 0.7wt%, 0.9wt%, 1wt%, 1.1wt%, 1.3wt% or 1.5wt%.

[0073] In some embodiments, the heat treatment temperature is 300°C to 1000°C, for example, it can be 300°C, 400°C, 500°C, 600°C, 700°C, 800°C, 900°C or 1000°C.

[0074] In some embodiments, when the positive electrode additive is used to coat the positive electrode material, the heat treatment temperature is 300°C to 800°C.

[0075] In some embodiments, when the cathode additive is used to dope the cathode material, the temperature of the heat treatment is 600°C to 1000°C.

[0076] In some embodiments, the heat treatment time is 3h to 20h, for example, it can be 3h, 4h, 5h, 6h, 7h, 8h, 9h, 10h, 11h, 12h, 13h, 14h, 15h, 16h, 17h, 18h, 19h or 20h.

[0077] In some embodiments, when the positive electrode additive is used to coat the positive electrode material, the heat treatment time is 3h to 15h.

[0078] In some embodiments, when the cathode additive is used to dope the cathode material, the heat treatment time is 5h to 20h.

[0079] In a fourth embodiment, the present invention provides a composite cathode material, which is prepared by the preparation method described in the third embodiment.

[0080] In a fifth embodiment, the present invention provides a lithium-ion battery comprising a composite cathode material as described in the fourth embodiment.

[0081] The numerical range described in this invention includes not only the point values ​​listed above, but also any point values ​​within the numerical ranges not listed above. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific point values ​​included in the range.

[0082] Preparation Example 1

[0083] This preparation example provides a positive electrode additive, the composition of which includes Li 0.3 Co 0.4 Zr 0.15 W 0.2 Al 0.25 O 2.0 The electronic conductivity of the positive electrode additive is 3×10⁻⁶. -5 S / cm, ionic conductivity 3×10 -5 S / cm, the primary particle size of the positive electrode additive is 300nm.

[0084] This preparation example also provides a method for preparing the positive electrode additive, comprising:

[0085] Lithium hydroxide, Co3O4, ZrO2, WO3 and Al2O3 were ball-milled according to stoichiometric ratio, sintered at 450℃ for 10h in air atmosphere, and mechanically crushed to a particle size of 300nm (D50).

[0086] Preparation Example 2

[0087] This preparation example provides a positive electrode additive, the composition of which includes Li 0.1 V 0.2 La 0.1 Ta 0.3 Al 0.4 O 2.05 The electronic conductivity of the positive electrode additive is 7 × 10⁻⁶. -6 S / cm, ionic conductivity 1×10 -5 S / cm, the D50 particle size of the primary particles of the positive electrode additive is 100nm.

[0088] This preparation example also provides a method for preparing the positive electrode additive, comprising:

[0089] Lithium carbonate, V2O5, La2O3, Ta2O5 and Al2O3 were ball-milled according to stoichiometric ratio, sintered at 300℃ for 20h in air atmosphere, and mechanically crushed to a primary particle size of 100nm.

[0090] Preparation Example 3

[0091] This preparation example provides a positive electrode additive, the composition of which includes Li 0.9 Cr 0.3 Y 0.1 La 0.2 Ta 0.1 Al 0.3 O 2.15 The electronic conductivity of the positive electrode additive is 2×10⁻⁶. -5 S / cm, ionic conductivity 4×10 -5 S / cm, the primary particle size of the positive electrode additive is 600nm.

[0092] This preparation example also provides a method for preparing the positive electrode additive, comprising:

[0093] According to the stoichiometric ratio, lithium hydroxide, Co3O4, Y2O3, La2O3, Ta2O5 and Al2O3 were ball-milled and sintered at 600℃ for 5 hours in air atmosphere. The D50 particle size of the mechanically crushed primary particles was 600nm.

[0094] Preparation Example 4

[0095] This preparation example provides a positive electrode additive, wherein the composition of the positive electrode additive includes Li 0.05 Co 0.4 Zr 0.15 W 0.2 Al 0.25 O 1.9 The electronic conductivity of the positive electrode additive is 2×10⁻⁶. -5 S / cm and ionic conductivity are 5×10 -7 S / cm, the rest are the same as in Example 1.

[0096] Preparation Example 5

[0097] This preparation example provides a positive electrode additive, wherein the composition of the positive electrode additive includes Li 1.05 Co 0.4 Zr 0.15 W 0.2 Al 0.25 O 2.4 The electronic conductivity of the positive electrode additive is 2×10⁻⁶. -5 S / cm and ionic conductivity are 2×10 -7S / cm, the rest are the same as in Example 1.

[0098] Preparation Example 6

[0099] This preparation example provides a positive electrode additive, wherein the composition of the positive electrode additive includes Li 0.3 Co 0.6 Zr 0.1 W 0.05 Al 0.25 O 1.78 The electronic conductivity of the positive electrode additive is 3×10⁻⁶. -5 S / cm, ionic conductivity 3×10 -7 Except for S / cm, everything else is the same as in Example 1.

[0100] Preparation Example 7

[0101] This preparation example provides a positive electrode additive, wherein the composition of the positive electrode additive includes Li 0.3 Co 0.15 Zr 0.3 W 0.3 Al 0.25 O 2.25 The electronic conductivity of the positive electrode additive is 2×10⁻⁶. -7 S / cm, ionic conductivity 3×10 -5 Except for S / cm, everything else is the same as in Example 1.

[0102] Preparation Example 8

[0103] This preparation example provides a positive electrode additive, wherein the composition of the positive electrode additive includes Li 0.3 Co 0.6 Zr 0.1 W 0.05 Al 0.05 O 2.03 The electronic conductivity of the positive electrode additive is 4 × 10⁻⁶. -5 S / cm, ionic conductivity 3×10 -8 Except for S / cm, everything else is the same as in Example 1.

[0104] Preparation Example 9

[0105] This preparation example provides a positive electrode additive, wherein the composition of the positive electrode additive includes Li 0.3 Co 0.15 Zr 0.1 W 0.05 Al 0.5 O 2.03 The electronic conductivity of the positive electrode additive is 3×10⁻⁶. -7 S / cm, ionic conductivity 4×10 -7Except for S / cm, everything else is the same as in Example 1.

[0106] Preparation Example 10

[0107] This preparation example provides a positive electrode additive, wherein the sintering temperature during the preparation of the positive electrode additive is 250°C, and the electronic conductivity of the positive electrode additive is 4 × 10⁻⁶. -6 S / cm, ionic conductivity 7×10 -8 Except for S / cm, everything else is the same as in Example 1.

[0108] Preparation Example 11

[0109] This preparation example provides a positive electrode additive, wherein the sintering temperature during the preparation of the positive electrode additive is 650°C, and the electronic conductivity of the positive electrode additive is 7×10⁻⁶. -7 S / cm and ionic conductivity are 6×10 -7 Except for S / cm, everything else is the same as in Example 1.

[0110] This invention uses the cathode additives provided in all the above preparation examples as doping and / or coating agents to improve the NCM613 cathode material (LiNi). 0.6 Co 0.1 Mn 0.3 O2 is used to dope and / or coat composite cathode materials, and their electrical properties are tested using the following methods:

[0111] (1) Preparation of button half-cell: The composite cathode material provided in all examples and comparative examples was mixed with acetylene black and polyvinylidene fluoride at a mass ratio of 95:3:2 to prepare a cathode sheet, which was then rolled to a compaction density of 3.5 g / cm³. 3 Using lithium foil as the negative electrode, they are assembled into coin cell half-cells.

[0112] (2) Set the charging and discharging voltage range to 2.8V~4.45V, the test temperature to 25℃, and the charging and discharging rate to 0.1C / 0.1C to test the 0.1C discharge specific capacity of the coin cell.

[0113] (3) Set the charging and discharging voltage to 2.8V~4.45V, the test temperature to 25℃, the charging and discharging rate to 0.1C / 1C, test the 1C discharge specific capacity, and the 1C discharge capacity retention rate = 1C discharge specific capacity / 0.1C discharge specific capacity.

[0114] (4) Set the charge and discharge voltage to 3.0V~4.45V, the test temperature to 25℃, the charge and discharge rate to 1C / 1C, and cycle the charge and discharge 100 times. The cycle capacity retention rate = the specific capacity of the 100th discharge / the specific capacity of the first discharge.

[0115] Example 1

[0116] This embodiment provides a composite cathode material, the preparation method of which includes:

[0117] The cathode additive provided in Example 1 was mixed with NCM613 cathode material, wherein the amount of cathode additive added was 1 wt% of the cathode material mass; the mixture was heated to 650°C in air and heat-treated for 10 h to obtain Co, Zr, W and Al doping, while Li... 0.3 Co 0.4 Zr 0.15 W 0.2 Al 0.25 O 2.0 Coated composite cathode material.

[0118] The backscattered image of the composite cathode material prepared in this example, as measured by EPMA, is shown below. Figure 1 As shown, the EPMA spectra of Co, Zr, W, and Al on the surface of the composite cathode material are as follows: Figures 2 to 5 As shown.

[0119] Example 2

[0120] This embodiment provides a composite cathode material, the preparation method of which includes:

[0121] The cathode additive provided in Example 2 was mixed with NCM613 cathode material, wherein the amount of cathode additive added was 1.5 wt% of the cathode material mass; the mixture was heated to 350°C in air and heat-treated for 15 h to obtain Li. 0.1 V 0.2 La 0.1 Ta 0.3 Al 0.4 O 2.05 Coated composite cathode material.

[0122] Example 3

[0123] This embodiment provides a composite cathode material, the preparation method of which includes:

[0124] The cathode additive provided in Example 3 was mixed with NCM613 cathode material, wherein the amount of cathode additive added was 0.3 wt% of the cathode material mass; the mixture was heated to 1000 °C in air and heat-treated for 6 h to obtain a composite cathode material doped with Cr, Y, La, Ta and Al.

[0125] In Examples 1 to 3, the doping depth of the elements in the cathode additive is controlled by adjusting the temperature of the heat treatment. Depending on the performance requirements, the transition metal elements in the cathode additive can be doped into the cathode material, and the cathode material can be doped and coated at the same time, or only the cathode material can be doped or only the cathode material can be coated, thus broadening the application scenarios of the cathode additive.

[0126] The electrical performance of lithium-ion batteries prepared from the composite cathode materials provided in Examples 1 to 3 is shown in Table 1. The first charge-discharge curve of the lithium-ion battery prepared from the composite cathode material provided in Example 1 is shown in Table 1. Figure 6 As shown.

[0127] Table 1

[0128]

[0129] Examples 4 to 9

[0130] Examples 4 to 9 were identical to Example 1, except that the cathode additives provided in Examples 4 to 9 were mixed with NCM613 cathode material. The electrical performance test results of the lithium-ion batteries prepared from the composite cathode materials provided in Examples 4 to 9 are shown in Table 2.

[0131] Table 2

[0132]

[0133] Comparing Example 1 with Example 4 and Example 5, when the lithium content is too low (Example 4), lithium-containing composite additives cannot be effectively formed, resulting in poor ionic conductivity. When the lithium content is too high (Example 5), the residual lithium in the additives will increase, which will also affect the ionic conductivity of the cathode material, resulting in a significantly lower capacity of the cathode material compared to Example 1.

[0134] Comparing Examples 1 and 6 to 9, a low M1 content will lead to a decrease in the electronic conductivity of the cathode additive, and a low M2 content will lead to a decrease in the ionic conductivity of the cathode additive, thereby affecting the capacity improvement effect on the doped and coated cathode material; a low Al content will affect the improvement effect on the cycle stability of the doped and coated cathode material, as well as the uniformity of the additive's doping and coating of the cathode material.

[0135] Therefore, based on the test results of Examples 4 to 9, it can be confirmed that maintaining the molar ratio of Li, M1, M2 and Al in the cathode additive within a suitable range is beneficial for each functional element in the cathode additive to fully exert its role in improving the performance of the cathode material, and simultaneously improve the capacity, rate performance and cycle stability of the cathode material.

[0136] Examples 10-11

[0137] Examples 10 and 11 were identical to Example 1, except that the cathode additives provided in Examples 10 and 11 were mixed with NCM613 cathode material, respectively. The electrical performance test results of the lithium-ion batteries prepared from the composite cathode materials provided in Examples 10 and 11 are shown in Table 3.

[0138] Table 3

[0139]

[0140] Based on the test results of Examples 10 and 11, the sintering temperature has a crucial impact on the distribution and crystal structure of Li, M1, M2, and Al components in the cathode additive. If the sintering temperature is too low, sufficient melting and sintering between the raw material components cannot be achieved, thus failing to construct a composite oxide structure and fully leverage the synergistic effect between the elements. If the sintering temperature is too high, the cathode additive particles become too large, resulting in poor contact between particles, reduced ionic conductivity, and poor coating effect on the cathode material. Therefore, ensuring the sintering temperature is within a suitable range is more conducive to maximizing the performance enhancement effect of the cathode additive on the cathode material.

[0141] Comparative Example 1

[0142] This comparative example provides a composite cathode material, the preparation method of which includes:

[0143] The composite cathode material is obtained by mixing lithium hydroxide, Co3O4, ZrO2, WO3 and Al2O3 with NCM613 cathode material, wherein the total amount of lithium hydroxide, Cr2O3, ZrO2, WO3 and Al2O3 added is 1 wt% of the cathode material mass; the mixture is heated to 650℃ in air and heat-treated for 10 h.

[0144] Comparative Example 2

[0145] This comparative example provides a composite cathode material, the preparation method of which includes:

[0146] The composite cathode material is obtained by mixing lithium carbonate, V2O5, La2O3, Ta2O5 and Al2O3 with NCM613 cathode material, wherein the total amount of lithium carbonate, V2O5, La2O3, Ta2O5 and Al2O3 added is 1 wt% of the cathode material mass; the mixture is heated to 350°C in air and heat-treated for 6 h.

[0147] Comparative Example 3

[0148] This comparative example provides a composite cathode material, the preparation method of which includes:

[0149] The composite cathode material is obtained by mixing lithium hydroxide, Cr2O3, Y2O3, La2O3, Ta2O5, and Al2O3 with NCM613 cathode material, wherein the total amount of lithium hydroxide, Co3O4, Y2O3, La2O3, Ta2O5, and Al2O3 added is 1 wt% of the cathode material mass; the mixture is heated to 1100℃ in air and heat-treated for 15 h.

[0150] The electrical performance test results of the lithium-ion batteries prepared from the composite cathode materials provided in Comparative Examples 1 to 3 are shown in Table 4.

[0151] Table 4

[0152]

[0153] Based on the test results of Examples 1 to 3 and Comparative Examples 1 to 3, compared with a simple mixture of lithium source, M1 source, M2 source and aluminum source, the present invention prepares a composite component oxide as a cathode additive by sintering lithium source, M1 source, M2 source and aluminum source. The composite component oxide has better composition consistency, better doping and / or coating uniformity, and better ionic conductivity and electronic conductivity. It has a better performance improvement effect on the composite cathode material after doping and / or coating.

[0154] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A positive electrode additive, characterized in that, The composition of the positive electrode additive includes Li x M1 a M2 b Al c O ((x+y) / 2) M1 includes any one or at least two of V, Cr, Mn, Fe, Co, Ni or Cu, M2 includes at least two of La, Zr, Nb, Ti, Y, Ta or W, y represents the average valence of M1, M2 and Al, 2.8≤y≤4.5, 0.1≤x≤0.9, 0.2≤a≤0.4, 0.2≤b≤0.4, 0.2≤c≤0.4, a+b+c=1; The primary particles of the positive electrode additive have a D50 particle size of 30nm~600nm.

2. The positive electrode additive as described in claim 1, characterized in that, The electronic conductivity of the positive electrode additive is ≥1×10⁻⁶. -6 S / cm, ionic conductivity ≥5×10 -6 S / cm.

3. A method for preparing the positive electrode additive as described in claim 1 or 2, characterized in that, The preparation method includes: In an oxygen-containing atmosphere, lithium source, M1 source, M2 source and aluminum source are mixed in stoichiometric ratio and sintered to obtain the cathode additive.

4. The preparation method according to claim 3, characterized in that, The sintering temperature is 300℃~600℃; And / or, the sintering time is 5h~20h.

5. The preparation method according to claim 3, characterized in that, The lithium source includes any one or a combination of at least two of lithium oxide, lithium hydroxide, lithium carbonate, or lithium acetate. And / or, the M1 source includes any one or a combination of at least two of the oxides, hydroxides or carbonates of M1; And / or, the M2 source includes any one or a combination of at least two of the oxides, hydroxides or carbonates of M2; And / or, the aluminum source includes aluminum oxide and / or aluminum hydroxide.

6. A method for preparing a composite cathode material, characterized in that, The preparation method includes: The composite cathode material is obtained by mixing the cathode material with the cathode additive described in claim 1 or 2 and then heat-treating it.

7. The preparation method according to claim 6, characterized in that, The amount of the positive electrode additive added is 0.1wt% to 1.5wt% of the mass of the positive electrode material.

8. The preparation method according to claim 6, characterized in that, The temperature of the heat treatment is 300℃~1000℃; And / or, the heat treatment time is 3h to 20h.

9. A composite cathode material, characterized in that, The composite cathode material is prepared by the preparation method according to any one of claims 6 to 8.

10. A lithium-ion battery, characterized in that, The lithium-ion battery includes the composite cathode material as described in claim 9.

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