Preparation method of composite positive electrode material

Abstract

The invention provides a composite positive electrode material and application thereof, the composite positive electrode material comprises an inner core and an outer layer coating the inner core, the main body active substance of the inner core is lithium nickel manganese cobalt oxide, and the coating layer of the shell is zirconium phosphate doped with rare earth element (yttrium or lanthanum). The composite positive electrode material has relatively high structural stability, can reduce electrode / electrolyte interface side reactions, improve the electrode / electrolyte interface stability, promote lithium ion transmission, reduce material structure damage and capacity fading, optimize the cycle performance and high rate performance of the material, and significantly prolong the cycle life of the battery.

Description

Technical Field

[0001] This invention focuses on the field of battery materials technology, and particularly relates to a novel composite cathode material with unique properties. This material aims to provide an innovative solution to the challenges currently facing battery technology, in order to meet the growing market demand. Background Technology

[0002] Against the backdrop of widespread adoption of electronic devices and the rapid development of the electric vehicle industry, improving battery performance has become a key focus of the industry. Traditional cathode materials, such as lithium cobalt oxide and lithium iron phosphate, have revealed significant limitations in terms of energy density, cycle life, and safety. While lithium cobalt oxide boasts high operating voltage and energy density, its reliance on cobalt resources is hampered by scarcity and high cost, and its stability at high temperatures is poor. Lithium iron phosphate, while offering good safety performance and long cycle life, struggles to meet the energy density demands of emerging applications. Therefore, developing a novel cathode material that combines high energy density, long cycle life, high safety, and low cost has become a crucial task in advancing battery technology. Summary of the Invention

[0003] This invention aims to develop a novel composite cathode material, which effectively overcomes the shortcomings of existing cathode materials in terms of energy density, cycle life, and safety, comprehensively improves the overall performance of batteries, and provides strong support for the innovation of battery technology.

[0004] The novel composite cathode material consists of a host active material and a coating layer. The host active material is lithium nickel manganese cobalt oxide (LiNi). x Mn y Co n O2, where x+y+n=1, 0.3≤x≤0.8, 0.1≤y≤0.5, 0.1≤n≤0.5). By precisely controlling the ratio of nickel, manganese, and cobalt, the material achieves high capacity and a suitable voltage platform. The coating layer uses zirconium phosphate (Zr) doped with rare earth elements M (yttrium (Y) and / or lanthanum (La)). 1-a M a Yttrium phosphate (YP), with a concentration of 0 ≤ a ≤ 0.2, is uniformly coated onto the surface of the main active material with a thickness of 5-20 nanometers. The doping of YP significantly optimizes the electronic structure of zirconium phosphate, effectively improving the ionic conductivity and chemical stability of the coating layer.

[0005] Preparation method Preparation of the main active material: First, a lithium nickel manganese cobalt oxide precursor was prepared using a co-precipitation method. Nickel, manganese, and cobalt salts were mixed in a specific ratio to form a solution. A precipitant was slowly added dropwise under continuous stirring, while strictly controlling the reaction temperature and pH to promote hydroxide precipitation. After filtration, washing, and drying, the precursor was obtained. Subsequently, the precursor was thoroughly mixed with a lithium source and calcined at high temperature to finally obtain the lithium nickel manganese cobalt oxide main active material.

[0006] Coating layer preparation: Yttrium-doped zirconium phosphate coating layers were prepared using the sol-gel method. Zirconium salt, phosphate source, yttrium salt, and / or lanthanum salt were dissolved in an organic solvent, and an appropriate complexing agent (such as 1,3,5-triazine-2,4,6-triamine, benzyl N,N,N',N'-tetraisopropylphosphonic diamine, N,N,N',N'',N''-pentamethyldivinyltriamine, N,N,5-trimethylfurfural) was added to form a homogeneous and stable sol. The complexing agents described above can achieve complexation of metal ions in yttrium salt and / or lanthanum salt, and when lithium nickel manganese cobalt oxide is added, surface gelation is formed, promoting the composite effect of the product. Finally, through drying and low-temperature calcination processes, a novel composite cathode material with doped zirconium yttrium phosphate was successfully prepared.

[0007] The amount of the complexing agent added is 0.1-0.8 wt%, preferably 0.5 wt%.

[0008] In some preferred cases, the molar ratio of Zr:P:Y and / or La is controlled to be 0.95:1:0.01-0.1.

[0009] More preferably, the molar ratio of Zr:P:Y and / or La is controlled to be 0.95:1:0.05.

[0010] Material properties High energy density: By optimizing the ratio of nickel, manganese and cobalt in lithium nickel manganese cobalt oxide, the specific capacity of the material is significantly improved. Combined with a suitable voltage platform, the energy density is further enhanced, meeting the needs of high-energy application scenarios.

[0011] Long cycle life: High-nickel materials (x>0.6) suffer from severe side reactions on the surface. By optimizing the ratio of nickel, manganese and cobalt in lithium nickel manganese cobalt oxide and coating the surface with a zirconium phosphate layer doped with yttrium and / or lanthanum, the side reactions between the main active material and the electrolyte are effectively suppressed, greatly reducing material structure damage and capacity decay, and significantly extending the battery cycle life.

[0012] High safety: The coating layer enhances the chemical stability of the material and significantly reduces the impact of harsh conditions such as high temperatures. This significantly reduces the risk of thermal runaway under certain conditions and improves battery safety.

[0013] Cost advantage: While ensuring high performance, the material production cost is effectively reduced by rationally selecting raw materials and optimizing the preparation process, and it has good market application prospects. Attached Figure Description

[0014] The accompanying drawings are used to provide a further understanding of the present disclosure and constitute a part of the specification. Together with the following detailed description, they are used to explain the present disclosure but do not constitute a limitation of the present disclosure. In the accompanying drawings: Figure 1 This is an electron microscope image of the morphology of Embodiment 1 of the present invention.

[0015] Figure 2 This is an electron microscope image of the comparative example 1 of the present invention. Detailed Implementation

[0016] The present invention will be described in detail below through specific embodiments, but the scope of protection of the present invention is not limited to these embodiments.

[0017] The endpoints and any values ​​of the ranges disclosed in this invention are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this invention.

[0018] To better understand the present invention, the following description, in conjunction with embodiments and related drawings, further illustrates the content of the present invention, but the content of the present invention is not limited to the following embodiments.

[0019] Example 1 Preparation of the main active material: Nickel sulfate (NiSO4·6H2O), manganese sulfate (MnSO4·H2O), and cobalt sulfate (CoSO4·7H2O) were prepared into a 1 mol / L mixed solution with a nickel:manganese:cobalt molar ratio of 0.5:0.3:0.2. A 2 mol / L sodium hydroxide solution was slowly added dropwise as a precipitant while stirring at 500 r / min, under nitrogen protection. The reaction temperature was controlled at 60 °C and the pH at 10. After the reaction, the precipitate was filtered, washed repeatedly with deionized water, and dried at 80 °C for 12 hours to obtain the precursor. The precursor was mixed with lithium carbonate (Li2CO3) at a lithium:metal ion molar ratio of 1.05:1 and calcined at 900 °C for 10 hours to obtain lithium nickel manganese cobalt oxide (LiNi). 0.5 Mn 0.3 Co0.2 O2.

[0020] Coating preparation: Zirconium oxychloride (ZrOCl2·8H2O), ammonium dihydrogen phosphate (NH4H2PO4), and yttrium nitrate (Y(NO3)3·6H2O) were dissolved in ethylene glycol at a molar ratio of Zr:P:Y = 0.95:1:0.05. 0.5 wt% N,N,5-trimethylfurfural ammonium was added as a complexing agent, and the mixture was stirred until homogeneous to form a sol. The prepared lithium nickel manganese cobalt oxide was added to the sol and ultrasonically dispersed for 30 minutes, followed by stirring at 60 °C to promote gelation. The gel was dried at 100 °C for 8 hours and finally calcined at 500 °C for 4 hours to obtain a Zr-coated surface. 0.95 Y 0.05 A novel composite cathode material for PO4.

[0021] Example 2: The preparation of the main active material is the same as in Example 1, yielding lithium nickel manganese cobalt oxide (LiNi). 0.5 Mn 0.3 Co 0.2 O2. Coating preparation: The rare earth element source yttrium nitrate (Y(NO3)3·6H2O) was replaced with lanthanum nitrate (La(NO3)3·6H2O), and the remaining steps were the same as in Example 1, to prepare a Zr-coated surface layer. 0.9 La 0.05 A novel composite cathode material for PO4. The composite material was annealed at 500°C for 3 hours under a nitrogen atmosphere to obtain the final product.

[0022] Example 3: The preparation of the main active material is the same as in Example 1, yielding lithium nickel manganese cobalt oxide (LiNi). 0.5 Mn 0.3 Co 0.2 O2. Coating preparation: The complexing agent N,N,5-trimethylfurfural was replaced with 1,3,5-triazine-2,4,6-triamine, and the remaining steps were the same as in Example 1 to prepare a Zr-coated surface layer. 0.95 Y 0.05 A novel composite cathode material for PO4. The composite material was annealed at 500°C for 3 hours under a nitrogen atmosphere to obtain the final product.

[0023] Example 4: The preparation of the main active material is the same as in Example 1, yielding lithium nickel manganese cobalt oxide (LiNi). 0.5 Mn 0.3 Co 0.2 O2. Coating preparation: The complexing agent N,N,5-trimethylfurfural was replaced with benzyl N,N,N',N'-tetraisopropylphosphonic diamine, and the remaining steps were the same as in Example 1, to prepare a Zr-coated surface layer.0.95 Y 0.05 A novel composite cathode material for PO4. The composite material was annealed at 500°C for 3 hours under a nitrogen atmosphere to obtain the final product.

[0024] Example 5: The preparation of the main active material is the same as in Example 1, yielding lithium nickel manganese cobalt oxide (LiNi). 0.5 Mn 0.3 Co 0.2 O2. Coating preparation: The complexing agent N,N,5-trimethylfurfuralamine was replaced with N,N,N',N'',N''-pentamethyldivinyltriamine, and the remaining steps were the same as in Example 1, to prepare a Zr-coated surface layer. 0.95 Y 0.05 A novel composite cathode material for PO4. The composite material was annealed at 500°C for 3 hours under a nitrogen atmosphere to obtain the final product.

[0025] Example 6: The preparation of the main active material is the same as in Example 1, yielding lithium nickel manganese cobalt oxide (LiNi). 0.5 Mn 0.3 Co 0.2 O2. Coating preparation: The remaining steps are the same as in Example 1, to prepare a Zr surface-coated Zr with a Zr:P:Y:La ratio of 0.9:1:0.05:0.05. 0.9 Y 0.05 La 0.05 A novel composite cathode material for PO4. The composite material was annealed at 500°C for 3 hours under a nitrogen atmosphere to obtain the final product.

[0026] Comparative Example 1 The preparation of the main active material is the same as in Example 1, yielding lithium nickel manganese cobalt oxide (LiNi). 0.5 Mn 0.3 Co 0.2 O2. Coating preparation: The complexing agent N,N,5-trimethylfurfural was replaced with citric acid, and the remaining steps were the same as in Example 1, to prepare a Zr-coated surface layer. 0.95 Y 0.05 A novel composite cathode material for PO4. The composite material was annealed at 500°C for 3 hours under a nitrogen atmosphere to obtain the final product.

[0027] Comparative Example 2 The preparation of the main active material is the same as in Example 1, yielding lithium nickel manganese cobalt oxide (LiNi). 0.5 Mn 0.3 Co 0.2 O2.

[0028] Coating preparation: The Zr:P:Y molar ratio was changed to Zr:P:Y = 0.9:1:1, and the remaining steps were the same as in Example 1, to prepare a Zr-coated surface layer. 0.9 Y 0.1 A novel composite cathode material for PO4. The composite material was annealed at 500°C for 3 hours under a nitrogen atmosphere to obtain the final product.

[0029] Performance testing The materials prepared in Examples 1, 2, 3, 4, 5, 6, and Comparative Examples 1 and 2 were respectively fabricated into coin cells for performance testing. Specific data are shown in the table below: Table 1 Comparison of properties of different materials

[0030] Test results show that the La / Y co-doped novel composite cathode material prepared in Example 6 is significantly superior to the materials prepared in other examples in terms of initial discharge specific capacity, cycle life, and high-temperature stability. Meanwhile, Comparative Example 2 shows that the electrical performance of the over-doped material is significantly reduced, indicating that excessive doping of rare earth elements in this invention is actually detrimental to improving the material's electrical performance.

[0031] Depend on Figure 1 and Figure 2 It can be seen that when rare earth elements are appropriately doped into the coating layer, the prepared material particles are uniform. However, when rare earth elements are excessively doped into the coating layer, the material cannot form uniform particles and becomes a distinct blocky structure.

[0032] The above embodiments are merely illustrative examples and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations; therefore, any obvious variations or modifications derived therefrom remain within the scope of protection of this invention.

[0033] As can be seen from the above data, the novel composite cathode material prepared by this invention exhibits excellent comprehensive performance, which can effectively improve battery performance and service life, and provides a highly promising solution for the development of battery technology.

Claims

1. A composite cathode material, characterized in that, It consists of a main active material and a coating layer. The main active material is lithium nickel manganese cobalt oxide (LiNi). x Mn y Co n O2, where x+y+n=1, 0.3≤x≤0.8, 0.1≤y≤0.5, 0.1≤n≤0.5; The coating layer is zirconium phosphate (Zr) doped with rare earth element M. 1-a M a PO4, where 0 ≤ a ≤ 0.

2.

2. The composite cathode material according to claim 1, characterized in that, The coating layer is uniformly coated on the surface of the main active substance, with a thickness of 5-20 nanometers.

3. The composite cathode material according to claim 1, characterized in that, The rare earth element M is yttrium and / or lanthanum; Zirconium phosphate with rare earth elements yttrium and / or lanthanum doped in the coating layer is prepared by the sol-gel method and forms a coating structure on the surface of the host active material.

4. A method for preparing the composite cathode material according to any one of claims 1-3, characterized in that, Includes the following steps: A novel composite cathode material with yttrium-doped zirconium phosphate coating was prepared by a sol-gel method: zirconium salt, phosphate source, yttrium salt and / or lanthanum salt were dissolved in an organic solvent, and an appropriate amount of complexing agent was added to form a homogeneous sol. The lithium nickel manganese cobalt oxide host active material was dispersed in the sol. By controlling the sol concentration and reaction time, the sol was gelled on the surface of the host active material. Finally, after drying and low-temperature calcination, a novel composite cathode material with yttrium-doped and / or lanthanum-doped zirconium phosphate was obtained.

5. The preparation method according to claim 4, characterized in that, The complexing agent is selected from any one of 1,3,5-triazine-2,4,6-triamine, benzyl N,N,N',N'-tetraisopropylphosphodiamine, or N,N,N',N'',N''-pentamethyldivinyltriamine, and N,N,5-trimethylfurfural.

6. The preparation method according to claim 4, characterized in that, Lithium nickel manganese cobalt oxides are prepared by a co-precipitation method: nickel salt, manganese salt and cobalt salt are prepared into a mixed solution, and a precipitant is slowly added dropwise under stirring conditions. The reaction temperature and pH value are controlled to generate hydroxide precipitate, which is then filtered, washed and dried to obtain the precursor. The precursor and lithium source were mixed evenly and calcined at high temperature to obtain the main active material of lithium nickel manganese cobalt oxide.

7. The preparation method according to claim 6, characterized in that, Nickel salts include nickel sulfate (NiSO4·6H2O); manganese salts include manganese sulfate (MnSO4·H2O); cobalt salts include cobalt sulfate (CoSO4·7H2O); precipitants include sodium hydroxide solution; and lithium sources include lithium carbonate (Li2CO). 3。 8. The preparation method according to claim 4, characterized in that, The calcination temperature is 800-1000 ℃, and the calcination time is 8-12 hours.

9. The preparation method according to claim 4, characterized in that, Zirconium salts include zirconium oxychloride ZrOCl2·8H2O, phosphoric acid sources include ammonium dihydrogen phosphate (NH4H2PO4), yttrium salts include yttrium nitrate Y(NO3)3·6H2O, lanthanum salts include lanthanum nitrate La(NO3)3·6H2O, and the organic solvent is ethylene glycol.

10. The preparation method according to claim 4, characterized in that, The drying temperature is 80-120℃, the drying time is 6-10 hours, the low-temperature calcination temperature is 400-600℃, and the calcination time is 3-5 hours.

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