Ternary positive electrode material with hamburger-shaped structure and preparation method of ternary positive electrode material

Abstract

The invention provides a ternary positive electrode material with a hamburger-shaped structure and a preparation method of the ternary positive electrode material. Belongs to the technical field of lithium ion battery materials. The component of the ternary positive electrode material with the hamburger type structure is LiNi < x > Co < y > Mn < 1-x-y > O < 2 >, xlt; 1, 0lt; yt; Yt; 1, and x + y < lt >; 1. The hamburger-shaped structure is specifically characterized in that two spherical shell-like structures are tightly attached to each other in morphology, a middle transition area is thick and solid, and the whole hamburger-shaped structure is in a double-hemisphere-like overlapping state. Compared with a spherical structure and an olive-type structure, the ternary positive electrode material has the advantages that the ion transmission path is shortened, the structural stability is better, the side reaction can be reduced, and the rate capability and the cycle life of the ternary positive electrode material can be remarkably improved and prolonged compared with the spherical structure and the olive-type structure.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of lithium ion battery materials, and particularly relates to a hamburger structure ternary positive electrode material and a preparation method thereof. BACKGROUND

[0002] Lithium ion batteries are widely used in various portable electronic devices and electric vehicles due to their high energy density, high working voltage, long cycle life, no memory effect and environmental friendliness. However, the energy density of existing lithium ion batteries cannot meet the requirements of consumers for the endurance mileage of electric vehicles. For a long time, the positive electrode material has always been the key factor limiting the capacity and cost of lithium ion batteries. Due to the advantages of high specific capacity and low cost, high-nickel ternary positive electrode materials have great application potential in the fields of high-capacity demand such as electric vehicles and energy storage, and are considered to be one of the most promising positive electrode materials for developing high-energy-density lithium batteries in the future. However, high-nickel ternary materials face many problems such as surface side reactions, cation mixing, micro-cracks, transition metal dissolution during the cycle process, and have poor cycle stability and thermal stability, which limits the practical application.

[0003] In view of the many problems occurring in the cycle process of high-nickel ternary materials, people have proposed many strategies such as surface coating, ion doping, core-shell structure, concentration gradient, microstructure engineering to improve the cycle life of the material. By regulating the original morphology structure of the precursor (such as grain orientation, particle shape, layered arrangement, etc.), and inheriting the positive electrode layered oxide structure, the structural degradation mechanism of high-nickel ternary materials can be fundamentally reduced: reducing cation mixing, inhibiting micro-cracks and phase transformation, reducing surface side reactions and TM dissolution, thereby greatly improving the cycle stability and thermal safety. This morphology engineering starting from the precursor lays a solid and reliable foundation for the practical application of high-nickel ternary positive electrodes.

[0004] For example, CN112635751A discloses an olive-shaped ternary cathode material, its preparation method and application. The steps of the preparation method are as follows: First, dissolve nickel acetate, cobalt acetate and manganese acetate in 80 mL of aqueous solution according to the molar ratio n(Ni):n(Co):n(Mn) = 3:1:1, and the concentration of transition metals is 0.2 mol / L. Subsequently, add urea with a concentration of 0.3 mol / L, stir evenly, then transfer it to a forced-air drying oven for hydrothermal reaction at 180 °C for 12 h. After the reaction, filter and wash the product, and dry it at 80 °C for 12 h to obtain a carbonate precursor. Secondly, transfer the carbonate precursor to a muffle furnace for pre-calcination at 600 °C for 6 h to obtain a precursor oxide. Finally, mix the precursor oxide and lithium salt (lithium carbonate) evenly according to the molar ratio n(Ni,Co,Mn):n(Li) = 1:1.1, then transfer it to a muffle furnace and heat-treat it at a heating rate of 5 °C / min to 850 °C for 12 h, cool it, and grind it to obtain an olive-shaped ternary cathode material, labeled as LiNi

[0009] Co 0.2 Mn 0.2 O2. The synthesized precursor and cathode particles of this technology are olive-shaped. Compared with the secondary spherical shape prepared by the traditional method, the olive-shaped structure shortens the ion diffusion channel, increases the lithium ion diffusion kinetics, greatly improves the rate performance of the electrode material, and has excellent cycle performance. However, the olive-shaped structure is formed by stacking of lamellae. Although it can shorten the diffusion channel and improve lithium kinetics, there are still defects in the lack of internal structural uniformity. Summary of the Invention

[0005] The present invention aims to at least solve one of the above technical problems existing in the prior art. For this reason, the present invention provides a hamburger-shaped ternary cathode material, which shortens the ion transport path, has good structural stability, can reduce side reactions, and can significantly improve the rate performance and cycle life of the ternary cathode material compared with the spherical structure.

[0006] The present invention also provides a preparation method of the hamburger-shaped ternary cathode material.

[0007] In the first aspect of the present invention, a hamburger-shaped ternary cathode material is provided, and its components are LiNi x Co y Mn 1-x- y O2, where 0 < x < 1, 0 < y < 1, and x + y < <1.

[0008] One technical solution in the technical solution of the present invention regarding the hamburger-shaped ternary cathode material has at least the following

[0009] Beneficial effects:

[0010] The ternary cathode material of this invention exhibits a hamburger-like structure, characterized by two closely fitted spherical shell structures connected by a thick transition region, presenting an overall "double hemisphere" sandwich morphology. Unlike traditional spherical secondary particle aggregates or olive-shaped structures, the hamburger-like structure is formed through the synergistic orientation aggregation and radially oriented stacking of two-dimensional sheet-like crystal planes. Compared to existing technologies such as olive-shaped structures, current cathode materials fail to effectively induce synergistic growth of sheets, resulting in disordered stacking of primary nanosheets and the formation of olive-shaped structures during aggregation. These structures have rough surfaces, uneven morphology, and disordered crystal orientations. Therefore, this invention achieves breakthroughs in reaction system construction, nucleation rate control, and growth mechanism induction, which is crucial for obtaining the hamburger-like structure.

[0011] Compared to traditional single-particle aggregated spherical and olive-shaped structures, hamburger-shaped ternary cathode materials offer superior ion transport pathways, higher structural stability, and stronger interface control. Their multi-layered sandwich design helps shorten lithium-ion diffusion distances, mitigates volume changes during charge and discharge, and effectively suppresses side reactions with the electrolyte, thereby significantly improving the material's rate performance, cycle life, and initial coulombic efficiency. This results in superior overall performance for high-energy-density battery applications.

[0012] This invention presents a hamburger-shaped ternary cathode material, which shortens the ion transport path, exhibits better structural stability, and reduces side reactions. Compared to spherical and olive-shaped structures, it significantly improves the rate performance and cycle life of ternary cathode materials. The hamburger-shaped ternary cathode material achieves an initial charge-discharge performance of 220.40 mAh / g under 0.1C and 2.8-4.6V conditions, far exceeding the 199.32 mAh / g of the spherical ternary cathode material and the 186.39 mAh / g of the olive-shaped ternary cathode material.

[0013] According to some embodiments of the present invention, 0.05 <x<0.9,0.05<y<0.9。

[0014] A second aspect of the present invention provides a method for preparing a hamburger-shaped ternary cathode material according to the first aspect of the present invention, comprising the following steps:

[0015] S1: Dissolve nickel salt, cobalt salt, manganese salt and urea in water, add ethanol dropwise under stirring to obtain a mixed solution, transfer the mixed solution to a reaction vessel for hydrothermal reaction, cool to room temperature after reaction, separate solid and liquid to obtain carbonate precursor powder with hamburger-shaped structure;

[0016] S2: The carbonate precursor powder is mixed with lithium salt and then heat-treated to obtain the hamburger-shaped ternary cathode material.

[0017] This invention focuses on morphological control, synthesizing a unique hamburger-shaped carbonate precursor via a hydrothermal reaction. Subsequent heat treatment yields a hamburger-shaped ternary cathode material. By controlling reaction conditions and the sizing system, this invention enables the precursor to exhibit coordinated orientation and aggregation of two-dimensional lamellar crystal planes during nucleation and crystal growth, and further radially oriented stacking during subsequent growth, ultimately forming a smooth, naturally transitioning lamellar structure with enhanced overall integrity.

[0018] According to some embodiments of the present invention, in step S1, the stoichiometric ratio of the nickel salt, cobalt salt and manganese salt is (3-10):(1-3):(1-3).

[0019] According to some embodiments of the present invention, in step S1, the stoichiometric ratio of the nickel salt, cobalt salt and manganese salt is (6-8):(1-3):(1-3).

[0020] According to some embodiments of the present invention, in step S1, the stoichiometric ratio of the nickel salt, cobalt salt and manganese salt is 8:1:1 or 6:2:2.

[0021] According to some embodiments of the present invention, in step S1, the nickel salt, cobalt salt and manganese salt are each selected from at least one of sulfate, nitrate and chloride.

[0022] According to some embodiments of the present invention, the nickel salt is selected from at least one of nickel sulfate, nickel nitrate, nickel chloride, nickel acetate, or nickel oxalate.

[0023] According to some embodiments of the present invention, the cobalt salt is selected from at least one of cobalt sulfate, cobalt nitrate, cobalt chloride, or cobalt acetate.

[0024] According to some embodiments of the present invention, the manganese salt is selected from at least one of manganese sulfate, manganese nitrate, manganese chloride, or manganese acetate.

[0025] According to some embodiments of the present invention, in step S1, the molar ratio of the sum of the molar amounts of nickel salt, cobalt salt and manganese salt to urea is 1:(2-4).

[0026] According to some embodiments of the present invention, in step S1, the volume ratio of water to ethanol is 1:(1.5 to 5).

[0027] According to some embodiments of the present invention, in step S1, the volume ratio of water to ethanol is any one of 1:1.5, 1:2, 1:2.5, 1:3, 1:3.5, 1:4, 1:4.5, 1:5, such as 1:3, or any range of the two, such as 1:2.5 to 1:3.5.

[0028] According to some embodiments of the present invention, the temperature of the hydrothermal reaction is 160°C to 200°C.

[0029] According to some embodiments of the present invention, the temperature of the hydrothermal reaction is any value among 160°C, 170°C, 180°C, 190°C, and 200°C, such as 180°C, or a range of any two, such as 170°C to 180°C.

[0030] According to some embodiments of the present invention, the hydrothermal reaction time is 12h to 24h.

[0031] According to some embodiments of the present invention, the hydrothermal reaction time is any value among 12h, 14h, 16h, 18h, 20h, 22h, and 24h, such as 20h, or a range of any two, such as 16h to 18h.

[0032] According to some embodiments of the present invention, in step S1, after the hydrothermal reaction, the product can be filtered, washed and dried to obtain a carbonate precursor powder with a hamburger-shaped structure.

[0033] According to some embodiments of the present invention, in step S1, after the hydrothermal reaction, the temperature at which the product is washed and dried is 60°C to 80°C.

[0034] According to some embodiments of the present invention, in step S1, after the hydrothermal reaction, the temperature at which the product is washed and dried is any value among 60°C, 65°C, 70°C, 75°C, and 80°C, such as 70°C, or any range formed by both, such as 65°C to 70°C.

[0035] According to some embodiments of the present invention, in step S1, after the hydrothermal reaction, the product is washed and dried for 12h to 24h.

[0036] According to some embodiments of the present invention, in step S1, after the hydrothermal reaction, the drying time of the product after washing is any value among 12h, 14h, 16h, 18h, 20h, 22h, and 24h, such as 20h, or any range formed by both, such as 16h to 18h.

[0037] According to some embodiments of the present invention, in step S1, during the hydrothermal reaction, the packing ratio of the reactor is 60% to 80%.

[0038] According to some embodiments of the present invention, in step S1, during the hydrothermal reaction, the packing ratio of the reactor is any value among 60%, 65%, 70%, 75%, and 80%, such as 70%, or any range formed by both, such as 70% to 75%.

[0039] According to some embodiments of the present invention, in step S2, the molar ratio of the carbonate precursor powder to the lithium salt is 1:(1.03 to 1.2).

[0040] According to some embodiments of the present invention, in step S2, the molar ratio of the carbonate precursor powder to the lithium salt is any value among 1:1.03, 1:1.05, 1:1.07, 1:1.09, 1:1.11, 1:1.13, 1:1.15, 1:1.17, 1:1.19, and 1:1.2, such as 1:1.15, or any range formed by both, such as 1:1.13 to 1:1.17.

[0041] According to some embodiments of the present invention, in step S2, the lithium salt includes at least one of lithium hydroxide, lithium carbonate, lithium acetate, lithium nitrate, lithium acetate, lithium oxalate, and lithium chloride.

[0042] According to some embodiments of the present invention, in step S2, the heat treatment is carried out in an oxygen atmosphere and includes two heat treatment processes: the first stage is heat treatment at a temperature of 400℃ to 600℃ for 4h to 6h, and the second stage is heat treatment at a temperature of 650℃ to 900℃ for 8h to 24h.

[0043] According to some embodiments of the present invention, in step S2, the temperature of the first heat treatment is any value among 400°C, 450°C, 500°C, 550°C, and 600°C, such as 500°C, or a range of any two, such as 500°C to 550°C.

[0044] According to some embodiments of the present invention, in step S2, the time of the first heat treatment is any value among 4h, 4.5h, 5h, 5.5h, and 6h, such as 5h, or a range of any two, such as 4.5h to 5h.

[0045] According to some embodiments of the present invention, in step S2, the temperature of the second heat treatment is any value among 650°C, 700°C, 750°C, 800°C, 850°C, and 900°C, such as 700°C, or a range of any two, such as 700°C to 750°C.

[0046] According to some embodiments of the present invention, in step S2, the time of the second heat treatment is any value among 8h, 12h, 14h, 16h, 18h, 20h, 22h, and 24h, such as 16h, or any range formed by both, such as 16h to 20h. Attached Figure Description

[0047] Figure 1 This is the XRD spectrum of the carbonate precursor prepared in Example 1.

[0048] Figure 2 This is a SEM image of the carbonate precursor prepared in Example 1.

[0049] Figure 3This is a SEM image of the carbonate precursor prepared in Example 2.

[0050] Figure 4 This is a SEM image of the carbonate precursor prepared in Example 3.

[0051] Figure 5 This is a SEM image of the carbonate precursor prepared in Example 4.

[0052] Figure 6 This is a SEM image of the carbonate precursor prepared in Example 5.

[0053] Figure 7 This is a SEM image of the carbonate precursor prepared in Example 6.

[0054] Figure 8 This is a SEM image of the carbonate precursor prepared in Example 7.

[0055] Figure 9 This is the XRD spectrum of the hamburger-shaped ternary cathode material prepared in Example 8.

[0056] Figure 10 This is a SEM image of the hamburger-shaped ternary cathode material prepared in Example 8.

[0057] Figure 11 This is the XRD spectrum of the hamburger-shaped ternary cathode material prepared in Example 9.

[0058] Figure 12 This is a SEM image of the hamburger-shaped ternary cathode material prepared in Example 9.

[0059] Figure 13 This is a SEM image of the spherical precursor prepared in Comparative Example 1.

[0060] Figure 14 This is a SEM image of the spherical ternary cathode material prepared in Comparative Example 1.

[0061] Figure 15 This is a SEM image of the olive-shaped precursor prepared in Comparative Example 2.

[0062] Figure 16 This is a SEM image of the olive-shaped ternary cathode material prepared in Comparative Example 2.

[0063] Figure 17 These are the initial charge-discharge curves of three cathode materials under conditions of 0.1C and 2.8-4.4V.

[0064] Figure 18 These are the initial charge-discharge curves of three cathode materials under conditions of 0.1C and 2.8-4.6V.

[0065] Figure 19The graph shows the cycling performance of three cathode materials at a 2C current density and a voltage range of 2.8–4.4V.

[0066] Figure 20 The graph shows the cycling performance of three cathode materials at a 2C current density and a voltage range of 2.8–4.6V.

[0067] Figure 21 The graph shows the rate performance of three cathode materials at different current densities and voltage ranges of 3–4.5V. Detailed Implementation

[0068] The following are specific embodiments of the present invention, and the technical solutions of the present invention will be further described in conjunction with the embodiments, but the present invention is not limited to these embodiments.

[0069] The following will describe the concept and technical effects of the present invention clearly and completely with reference to embodiments, so as to fully understand the purpose, features and effects of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are all within the scope of protection of the present invention.

[0070] In the description of this invention, the terms "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0071] Unless otherwise specified, "room temperature" in this invention means 25℃±5℃.

[0072] Unless otherwise specified, "about" in this invention means that the allowable error is within ±2%.

[0073] Unless otherwise specified in the examples, the procedures should be performed under standard conditions or conditions recommended by the manufacturer. Reagents or instruments whose manufacturers are not specified are all commercially available products.

[0074] Example 1

[0075] A carbonate precursor with a hamburger-shaped structure was prepared by the following method:

[0076] Nickel sulfate hexahydrate, cobalt sulfate heptahydrate, and manganese sulfate monohydrate were weighed and dissolved in 10 mL of aqueous solution according to a molar ratio of n(Ni):n(Co):n(Mn) = 8:1:1. The amount of transition metal was 0.025 mol (the sum of the three solutions), and the transition metal concentration was 2.5 mol / L. Then, 0.075 mol of urea was added and stirred until homogeneous, with a molar ratio of metal salt to urea of ​​1:3. 20 mL of anhydrous ethanol was measured, with a water-to-ethanol volume ratio of 1:2. While continuously stirring the solution, ethanol was added dropwise at a uniform rate, and stirring was continued until homogeneous. The solution was transferred to a 50 mL polytetrafluoroethylene (PTFE) reactor and subjected to a hydrothermal reaction at 180 °C for 12 h in a forced-air drying oven. After the reaction, the solution was cooled to room temperature, filtered, washed, and dried at 60 °C for 12 h to obtain the carbonate precursor.

[0077] The XRD spectrum of the carbonate precursor prepared in this embodiment is as follows: Figure 1 As shown, observe Figure 1 It can be seen that the precursor material is composed of nickel, cobalt, and manganese carbonate.

[0078] SEM images of the carbonate precursor prepared in this embodiment are shown below. Figure 2 As shown, observe Figure 2 It can be seen that the precursor material is a hamburger-shaped structure with a length of about 3μm and a width of about 2μm.

[0079] Example 2

[0080] A carbonate precursor with a hamburger-shaped structure was prepared, which differs from Example 1 in that n(Ni):n(Co):n(Mn) = 6:2:2.

[0081] The SEM image of the hamburger-shaped ternary cathode material precursor prepared in this embodiment is shown below. Figure 3 As shown, observe Figure 3 It can be seen that the precursor material is a hamburger-shaped structure with a length of about 2 μm and a width of about 1.5 μm. Compared with Example 1, the surface of the precursor prepared in this example is rougher.

[0082] Example 3

[0083] A carbonate precursor with a hamburger-shaped structure was prepared, which differs from Example 1 in that the molar ratio of metal salt to urea is 1:2.

[0084] The SEM image of the hamburger-shaped ternary cathode material precursor prepared in this embodiment is shown below. Figure 4 As shown.

[0085] Example 4

[0086] A carbonate precursor with a hamburger-shaped structure was prepared, which differs from Example 1 in that the molar ratio of metal salt to urea is 1:4.

[0087] The SEM image of the hamburger-shaped ternary cathode material precursor prepared in this embodiment is shown below. Figure 5 As shown.

[0088] Example 5

[0089] A carbonate precursor with a hamburger-shaped structure was prepared. The difference from Example 1 is that the volume ratio of water to ethanol is 1:1.5, i.e., 12 mL of water and 18 mL of ethanol.

[0090] The SEM image of the hamburger-shaped ternary cathode material precursor prepared in this embodiment is shown below. Figure 6 As shown.

[0091] Example 6

[0092] A carbonate precursor with a hamburger-shaped structure was prepared. The difference from Example 1 is that the volume ratio of water to ethanol is 1:5, i.e., 5 mL of water and 25 mL of ethanol.

[0093] The SEM image of the hamburger-shaped ternary cathode material precursor prepared in this embodiment is shown below. Figure 7 As shown.

[0094] Example 7

[0095] A carbonate precursor with a hamburger-shaped structure was prepared, which differs from Example 1 in that the hydrothermal reaction temperature was 160°C.

[0096] The SEM image of the hamburger-shaped ternary cathode material precursor prepared in this embodiment is shown below. Figure 8 As shown.

[0097] Example 8

[0098] This embodiment prepares a hamburger-shaped ternary cathode material with the molecular formula LiNi. 0.8 Co 0.1 Mn 0.1 O2, the steps are as follows:

[0099] The hamburger-shaped ternary cathode material precursor prepared in Example 1 was mixed with lithium salt (lithium hydroxide) at a molar ratio of n(Ni,Co,Mn):n(Li) = 1:1.03 until homogeneous. The mixture was then transferred to a tube furnace and pre-calcined at 480°C for 5 hours at a heating rate of 3°C / min. The temperature was then further increased to 750°C for 12 hours. After cooling and grinding, the hamburger-shaped ternary cathode material was obtained and labeled as LiNi. 0.8 Co 0.1 Mn 0.1 O2.

[0100] The LiNi prepared in this embodiment 0.8 Co 0.1 Mn 0.1 O2 hamburger-shaped ternary cathode material was used in lithium-ion battery testing, specifically:

[0101] The obtained LiNi 0.8 Co 0.1 Mn 0.1 O2 powder, conductive agent acetylene black, and binder PVDF were weighed in a mass ratio of 8:1:1, and an appropriate amount of N-methylpyrrolidone was added and stirred and ground evenly to obtain a uniformly mixed slurry.

[0102] The slurry was coated onto the aluminum foil using a 200μm thick scraper. The coated aluminum foil was then dried in a forced-air drying oven at 60℃ for 8 hours and in a vacuum oven at 100℃ for 12 hours. The foil was then removed and cut into circular electrode sheets with a diameter of 12mm for use in assembling button batteries.

[0103] Subsequently, in an argon-protected glove box, lithium metal was used as the negative electrode, and the electrolyte was 1.3M LiPF6 dissolved in a mixed solvent with EC and DEC in a 1:1 mass ratio and 5% FEC added. Whatman glass fiber with a diameter of 16mm was used as the separator to assemble the button cell. Charge-discharge cycle tests and rate performance tests were then conducted on the LAND battery testing system.

[0104] The charge / discharge cutoff voltages are -2.8 to 4.4V and 2.8 to 4.6V, and the charge / discharge rates are 0.1C and 2C. Rate performance testing is conducted under the following conditions: charge / discharge cutoff voltage is 3 to 4.5V, and test currents are 0.1C, 0.2C, 0.5C, 1C, 2C, 5C, and 0.1C.

[0105] The XRD spectrum of the hamburger-shaped ternary cathode material prepared in this embodiment is as follows: Figure 9 As shown. Observation Figure 9 It can be seen that all XRD diffraction peaks belong to the α-NaFeO2 layered structure, space group R-3m, and there are no other impurities.

[0106] The SEM image of the hamburger-shaped ternary cathode material prepared in this embodiment is shown below. Figure 10 As shown, observe Figure 10 It can be seen that the cathode material inherits the hamburger-shaped structure of the precursor.

[0107] Example 9

[0108] This embodiment prepares a hamburger-shaped ternary cathode material. The difference from Example 8 is that the molar ratio of the precursor to lithium salt (lithium hydroxide) n(Ni,Co,Mn):n(Li) = 1:1.2.

[0109] The XRD spectrum of the hamburger-shaped ternary cathode material prepared in this embodiment is as follows: Figure 11 As shown. Observation Figure 11 It can be seen that all XRD diffraction peaks belong to the α-NaFeO2 layered structure, space group R-3m, and there are no other impurities.

[0110] The SEM image of the hamburger-shaped ternary cathode material prepared in this embodiment is shown below. Figure 12 As shown, observe Figure 12 It can be seen that the cathode material inherits the hamburger-shaped structure of the precursor.

[0111] Comparative Example 1

[0112] A spherical carbonate precursor was prepared, which differed from Example 1 in that the volume ratio of water to ethanol was 1:1, specifically 15 mL of water and 15 mL of ethanol.

[0113] The SEM image of the spherical ternary cathode precursor prepared in this embodiment is shown below. Figure 13 As shown, observe Figure 13 It can be seen that the precursor particles are standard spherical structures with a size of 30-40 μm, exhibiting morphological characteristics that are completely different from those in Example 1.

[0114] The spherical precursor and lithium salt (lithium hydroxide) were mixed uniformly at a molar ratio of n(Ni,Co,Mn):n(Li) = 1:1.03. The mixture was then transferred to a tube furnace and pre-calcined at 480℃ for 5 hours at a heating rate of 3℃ / min. The temperature was then further increased to 750℃ for 12 hours of heat treatment. After cooling and grinding, spherical ternary cathode materials were obtained, labeled LiNi. 0.8 Co 0.1 Mn 0.1 O2.

[0115] The LiNi prepared in this comparative example 0.8 Co 0.1 Mn 0.1 O2 spherical ternary cathode material is used in lithium-ion batteries, specifically as follows:

[0116] The obtained LiNi 0.8 Co 0.1 Mn 0.1 O2 powder, conductive agent acetylene black, and binder PVDF were weighed in a mass ratio of 8:1:1. An appropriate amount of N-methylpyrrolidone was added, and the mixture was stirred and ground with NMP to obtain a uniform slurry. The slurry was coated onto aluminum foil using a 200μm thick scraper. The coated aluminum foil was then dried in a forced-air drying oven at 60℃ for 8 hours and in a vacuum oven at 100℃ for 12 hours. The foil was then removed and cut into circular electrode sheets with a diameter of 12mm for use in assembling button batteries.

[0117] Then, in an argon-protected glove box, lithium metal was used as the negative electrode, and the electrolyte was a 1.3M LiPF6 dissolved in a mixed solvent with EC and DEC in a 1:1 mass ratio and 5% FEC added. Whatman glass fiber with a diameter of 16mm was used as the separator. The button cell was then assembled and subjected to charge-discharge cycle tests and rate performance tests on the LAND battery testing system.

[0118] The charge / discharge cutoff voltages are 2.8–4.4V and 2.8–4.6V, and the charge / discharge rates are 0.1C and 2C. Rate performance testing is conducted under the following conditions: charge / discharge cutoff voltage is 3–4.5V, and test currents are 0.1C, 0.2C, 0.5C, 1C, 2C, 5C, and 0.1C.

[0119] The SEM image of the spherical ternary cathode material prepared in this comparative example is shown below. Figure 14 As shown. Observation Figure 14 It can be seen that some particles break during the lithiation process, while most particles retain their spherical shape.

[0120] Comparative Example 2

[0121] An olive-shaped carbonate precursor was prepared, which differed from Example 1 in that the solvent was 30 mL of pure water and no ethanol was added.

[0122] SEM images of the olive-shaped carbonate precursor prepared in this comparative example are shown below. Figure 15 As shown. Observation Figure 15 It can be seen that the precursor particles have an olive-shaped structure with a size of 2 to 5 μm.

[0123] The olive-shaped precursor and lithium salt (lithium hydroxide) were mixed uniformly at a molar ratio of n(Ni,Co,Mn):n(Li) = 1:1.03. The mixture was then transferred to a tube furnace and pre-calcined at 480℃ for 5 hours at a heating rate of 3℃ / min. The temperature was then further increased to 750℃ for 12 hours of heat treatment. After cooling and grinding, spherical ternary cathode materials were obtained, labeled LiNi. 0.8 Co 0.1 Mn 0.1 O2.

[0124] The LiNi prepared in this comparative example 0.8 Co 0.1 Mn 0.1 O2 olive-shaped ternary cathode material is used in lithium-ion batteries, specifically as follows:

[0125] The obtained LiNi 0.8 Co 0.1 Mn 0.1O2 powder, conductive agent acetylene black, and binder PVDF were weighed in a mass ratio of 8:1:1. An appropriate amount of N-methylpyrrolidone was added, and the mixture was stirred and ground with NMP to obtain a uniform slurry. The slurry was coated onto aluminum foil using a 200μm thick scraper. The coated aluminum foil was then dried in a forced-air drying oven at 60℃ for 8 hours and in a vacuum oven at 100℃ for 12 hours. The foil was then removed and cut into circular electrode sheets with a diameter of 12mm for use in assembling button batteries.

[0126] Subsequently, within an argon-protected glove box, lithium metal was used as the negative electrode, and the electrolyte was a 1.3M LiPF6 solution dissolved in a mixed solvent with an EC / DEC mass ratio of 1:1 and 5% FEC added. Whatman glass fiber with a diameter of 16mm was used as the separator. The assembled button cells were then subjected to charge-discharge cycle testing and rate performance testing on the LAND battery testing system. The test conditions were: charge-discharge cutoff voltages of 2.8–4.4V and 2.8–4.6V, and test currents of 0.1C and 2C.

[0127] Rate performance testing was conducted under the following conditions: charge / discharge cutoff voltage of 3–4.5V, and test currents of 0.1C, 0.2C, 0.5C, 1C, 2C, 5C, and 0.1C.

[0128] The SEM image of the olive-shaped ternary cathode material prepared in this comparative example is shown below. Figure 16 As shown. Observation Figure 16 It can be seen that the cathode material inherits the olive-shaped structure of the precursor.

[0129] The hamburger-shaped ternary cathode material prepared in Example 8, the spherical ternary cathode material prepared in Comparative Example 1, and the olive-shaped ternary cathode material prepared in Comparative Example 2 were used in lithium-ion batteries. The initial charge-discharge curves under 0.1C and 2.8-4.4V conditions are shown below. Figure 17 As shown. By Figure 17 It can be seen that the initial discharge capacities of the hamburger-shaped, spherical, and olive-shaped ternary cathode materials are 224.85 mAh / g, 154.93 mAh / g, and 174.35 mAh / g, respectively, and the initial coulombic efficiencies are 90.34%, 77.83%, and 82.75%, respectively. A simple comparison shows that the hamburger-shaped ternary cathode material prepared in Example 8 has significantly better performance than the spherical ternary cathode material prepared in Comparative Example 1 and the olive-shaped ternary cathode material prepared in Comparative Example 2.

[0130] The hamburger-shaped ternary cathode material prepared in Example 8, the spherical ternary cathode material prepared in Comparative Example 1, and the olive-shaped ternary cathode material prepared in Comparative Example 2 were used in lithium-ion batteries. The initial charge-discharge curves under 0.1C and 2.8-4.6V conditions are shown below. Figure 18 As shown. By Figure 18It can be seen that the initial discharge capacities of the hamburger-shaped, spherical, and olive-shaped ternary cathode materials are 220.40 mAh / g, 199.32 mAh / g, and 186.39 mAh / g, respectively, and the initial coulombic efficiencies are 76.81%, 71.65%, and 77.51%, respectively. The hamburger-shaped ternary cathode material prepared in Example 8 exhibits a higher capacity release compared to the spherical ternary cathode material prepared in Comparative Example 1 and the olive-shaped ternary cathode material prepared in Comparative Example 2.

[0131] The hamburger-shaped ternary cathode material prepared in Example 8, the spherical ternary cathode material prepared in Comparative Example 1, and the olive-shaped ternary cathode material prepared in Comparative Example 2 were used in lithium-ion batteries. Their long-cycle curves under conditions of 2.8–4.4V and 2C are shown below. Figure 19 As shown. By Figure 19 The initial discharge capacities of the hamburger-shaped, spherical, and olive-shaped ternary cathode materials were 176.58 mAh / g, 147.27 mAh / g, and 142.86 mAh / g, respectively, with initial coulombic efficiencies of 84.68%, 74.45%, and 76.73%. After 100 cycles, the capacity retention rates were 90.93%, 72.37%, and 84.48%, respectively. Thanks to its structural advantages, the hamburger-shaped structure exhibits superior electrochemical performance compared to the traditional spherical and olive-shaped structures.

[0132] The hamburger-shaped ternary cathode material prepared in Example 8, the spherical ternary cathode material prepared in Comparative Example 1, and the olive-shaped ternary cathode material prepared in Comparative Example 2 were used in lithium-ion batteries. Their long-cycle curves under conditions of 2.8–4.6V and 2C are shown below. Figure 20 As shown. By Figure 20 It can be seen that the initial discharge capacities of the hamburger-shaped, spherical, and olive-shaped ternary cathode materials are 187.14 mAh / g, 172.18 mAh / g, and 153.21 mAh / g, respectively, with initial coulombic efficiencies of 83.61%, 72.44%, and 76.26%, respectively. After 100 cycles, the capacity retention rates are 79.01%, 61.73%, and 68.91%, respectively.

[0133] These cycling data indicate that while the olive-shaped structure shortens the lithium-ion diffusion path and improves ion dynamics compared to the traditional spherical structure, thus enhancing cycling performance, it, like the spherical structure, is still a single-stage particle stack, lacking internal stress buffer space and structural protection mechanisms. Furthermore, the gaps between particles inevitably lead to side reactions with the electrolyte, limiting the actual performance improvement. In contrast, the hamburger-shaped structure, with its dense surface and controllable reactivity, reduces first-cycle lithium consumption and improves first-cycle coulombic efficiency. Its unique structure effectively reduces the number of primary particles, significantly mitigating intergranular stress caused by volume changes during cycling, and reducing direct contact with the electrolyte. This significantly suppresses secondary particle fragmentation and side reactions with the electrolyte, improving cycling stability.

[0134] The hamburger-shaped ternary cathode material prepared in Example 8, the spherical ternary cathode material prepared in Comparative Example 1, and the olive-shaped ternary cathode material prepared in Comparative Example 2 were used in lithium-ion batteries. The rate performance at 3–4.5V and different current densities is shown in the graphs. Figure 21 As shown. By Figure 21 It can be seen that, compared with the traditional spherical and olive-shaped structures, the flat layered structure of the hamburger-shaped structure has a shorter and more direct lithium-ion diffusion path, exhibiting better high-voltage rate performance, which is far superior to the traditional spherical and olive-shaped structures.

[0135] The hamburger-shaped ternary cathode material prepared in Example 8, the spherical ternary cathode material prepared in Comparative Example 1, and the olive-shaped ternary cathode material prepared in Comparative Example 2 were used in lithium-ion batteries. The rate performance at 3–4.5V and different current densities is shown in the graphs. Figure 21 As shown. By Figure 21 It can be seen that, compared with the traditional spherical and olive-shaped structures, the flat layered structure of the hamburger-shaped structure has a shorter and more direct lithium-ion diffusion path, exhibiting better high-voltage rate performance, which is far superior to the traditional spherical and olive-shaped structures.

[0136] In summary, compared to traditional single-particle aggregated spherical and olive-shaped structures, ternary cathode materials with a hamburger-shaped structure exhibit superior ion transport pathways, higher structural stability, and stronger interface control. Their multi-layered sandwich design helps shorten lithium-ion diffusion distances, mitigates volume changes during charge and discharge, and effectively suppresses side reactions with the electrolyte, thereby significantly improving the material's rate performance, cycle life, and initial coulombic efficiency. This results in superior overall performance for high-energy-density battery applications.

[0137] The present invention has been described in detail above with reference to the embodiments. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.

Claims

1. A hamburger-shaped ternary cathode material, characterized in that, The component is LiNi x Co y Mn 1-x-y O2, where 0 < x < 1, 0 < y < 1, and x + y < 1.

2. The hamburger-shaped ternary cathode material according to claim 1, characterized in that, 0.05 <x<0.9,0.05<y<0.9。 3. A method for preparing a hamburger-shaped ternary cathode material as described in claim 1 or 2, characterized in that, Includes the following steps: S1: Dissolve nickel salt, cobalt salt, manganese salt and urea in water, add ethanol dropwise under stirring to obtain a mixed solution, transfer the mixed solution to a reaction vessel for hydrothermal reaction, cool to room temperature after reaction, separate solid and liquid to obtain carbonate precursor powder with hamburger-shaped structure; S2: The carbonate precursor powder is mixed with lithium salt and then heat-treated to obtain the hamburger-shaped ternary cathode material.

4. The method according to claim 3, characterized in that, In step S1, the nickel salt, cobalt salt, and manganese salt are each selected from at least one of sulfate, nitrate, and chloride.

5. The method according to claim 3, characterized in that, In step S1, the molar ratio of the sum of the molar amounts of nickel salt, cobalt salt, and manganese salt to urea is 1:(2-4).

6. The method according to claim 3, characterized in that, In step S1, the volume ratio of water to ethanol is 1:(1.5~5).

7. The method according to claim 3, characterized in that, The temperature of the hydrothermal reaction is 160℃~200℃.

8. The method according to claim 3, characterized in that, The hydrothermal reaction time is 12h to 24h.

9. The method according to claim 3, characterized in that, In step S2, the molar ratio of the carbonate precursor powder to the lithium salt is 1:(1.03~1.2).

10. The method according to claim 3, characterized in that, In step S2, the heat treatment is carried out in an oxygen atmosphere and includes two heat treatment processes: the first stage is heat treatment at 400℃~600℃ for 4h~6h, and the second stage is heat treatment at 650℃~900℃ for 8h~24h.

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