Preparation method and application of gradient temperature calcination modified high-voltage spinel lithium nickel manganese oxide positive electrode material

Abstract

The invention discloses a preparation method and application of a gradient temperature calcination modified high-voltage spinel lithium nickel manganese oxide positive electrode material, and the preparation method comprises the following steps: (1) pre-calcining a precursor with a nickel-manganese molar ratio of 1: 3 to obtain an oxide of the precursor; (2) fully mixing the oxide of the precursor with a lithium source to obtain a mixed lithium material; and (3) calcining the mixed lithium material by adopting a gradient temperature calcining strategy to finally obtain the high-voltage spinel lithium nickel manganese oxide positive electrode material. The method has the characteristics of simple process flow, low average calcination temperature, short time, low energy consumption, excellent product performance and suitability for large-scale production.

Description

Technical Field

[0001] This invention relates to the field of lithium-ion battery technology, specifically to a method for preparing and applying a high-voltage spinel lithium nickel manganese oxide cathode material modified by gradient temperature calcination. Background Technology

[0002] Lithium-ion batteries are characterized by high energy density and long cycle life, and are widely used in portable electronic devices, electric vehicles, and energy storage systems. With the explosive growth of the electric vehicle market and the surge in demand in the energy storage sector, the future of lithium-ion batteries focuses on increasing energy density and reducing costs.

[0003] High-voltage spinel lithium nickel manganese oxide (LiNi) 0.5 Mn 1.5 O4(LNMO) has a discharge voltage plateau of 4.7V and a capacity of 147mAh g. -1 The theoretical capacity provides 650Wh / kg. -1 With its high energy density and the fact that it eliminates the dependence on cobalt and makes extensive use of inexpensive manganese resources, it has become one of the next generation of high-energy-density, low-cost cathode material candidates.

[0004] However, in commercial applications, lithium nickel manganese oxide cathodes exhibit significant structural failure with increasing charge-discharge cycles. One major reason is the generation of trivalent manganese during prolonged high-temperature calcination in the synthesis process. This trivalent manganese causes localized distortion of the cathode structure due to the Jan Taylor effect and also undergoes a disproportionation reaction to produce divalent manganese dissolved in the electrolyte, leading to material dissolution. Many studies have focused on eliminating trivalent manganese. Among these efforts, secondary calcination of the cathode material below 700°C has been proven to effectively reduce the trivalent manganese content. However, low-temperature calcination generates ordered spinel with even worse cycle performance.

[0005] Conventional synthesis processes exhibit a coupling effect between cation order and trivalent manganese content, resulting in two types of lithium nickel manganese oxide cathodes: disordered high trivalent manganese and ordered low trivalent manganese, both of which exhibit poor performance.

[0006] Therefore, finding a suitable preparation process to achieve dual regulation of cation order and trivalent manganese content in order to improve the capacity, cycle stability and rate performance of lithium nickel manganese oxide is an urgent problem to be solved. Summary of the Invention

[0007] To overcome the shortcomings of the existing technology, the present invention provides a method for preparing and applying a high-voltage spinel lithium nickel manganese oxide cathode material modified by gradient temperature calcination. This method has the advantages of simple process flow, low average calcination temperature, short time, low energy consumption, superior product performance, and suitability for large-scale production.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0009] A high-voltage spinel lithium nickel manganese oxide cathode material modified by gradient temperature calcination is disclosed. The lithium nickel manganese oxide cathode material is composed of spherical secondary particles formed by the agglomeration of rod-shaped primary particles, which have a spherical morphology and a particle size range of 2-3 micrometers. These spherical cathode particles are more likely to adhere to the current collector and can maintain structural stability during cycling, making them less prone to breakage and ensuring the cycling stability of the material. The rod-shaped primary particles can shorten the diffusion distance of lithium ions, which helps to improve rate performance and discharge capacity.

[0010] The lithium nickel manganese oxide cathode material is a spinel phase lithium nickel manganese oxide with low trivalent manganese content (trivalent manganese mass fraction less than 5 wt%).

[0011] The lithium nickel manganese oxide cathode material is a 5V high-voltage spinel structure with the chemical formula Li. 1+x Ni 0.5 Mn 1.5 O4, where x is 0 to 0.1;

[0012] The trivalent manganese content of the lithium nickel manganese oxide cathode material is 1-3 wt%.

[0013] The cations in the lithium nickel manganese oxide cathode material are highly disordered, with the disordered phase accounting for 95.0% to 99.9% of the total spinel phase.

[0014] A method for preparing a high-voltage spinel lithium nickel manganese oxide cathode material modified by gradient temperature calcination includes the following steps:

[0015] Step (1): The precursor with a nickel-manganese molar ratio of 1:3 is pre-calcined to obtain the precursor oxide; wherein the precursor with a nickel-manganese molar ratio of 1:3 can form a spinel structure with a high voltage platform of 4.7V, improve the phase purity of the product, and avoid the generation of non-spinel phase due to the ratio deviation of transition metal cations, which would affect the performance of the product.

[0016] Step (2): The oxide of the precursor is thoroughly mixed with the lithium source to obtain a mixed lithium material;

[0017] Step (3): The mixed lithium material is calcined at a gradient temperature to finally obtain a high-voltage spinel lithium nickel manganese oxide cathode material.

[0018] Preferably, in step (1), the precursor is Ni. 0.25 Mn 0.75 (OH)2, Ni 0.25 Mn 0.75 CO3, Ni 0.25 Mn 0.75One or more of C2O4, preferably, the precursor is Ni. 0.25 Mn 0.75 (OH)2;

[0019] Preferably, in step (1), the pre-calcination temperature is 300-600℃; and in step (1), the pre-calcination time is 2-5h.

[0020] Preferably, in step (2), the molar ratio of nickel in the precursor oxide to lithium in the lithium source is 0.5:(1~1.1); the proportion of the lithium source taken is slightly higher than the theoretical lithium content of the product. On the one hand, it makes up for the lithium loss during the high-temperature synthesis process, and on the other hand, the extra lithium can play the role of lithium replenishment agent, which can effectively compensate for the lithium loss in the first charge and subsequent cycles, and extend the life of the positive electrode.

[0021] Preferably, in step (2), the lithium source is one or more of lithium hydroxide, lithium acetate, lithium nitrate, and lithium carbonate. More preferably, the lithium source is lithium carbonate.

[0022] Preferably, step (3) is as follows: the first calcination temperature is a, the temperature gradient is b, the calcination time is c, and the calcination is carried out continuously for three stages with temperatures of a, a+b, and a+2b, and calcination times of c, c, and 2c. This process is called gradient temperature calcination.

[0023] in:

[0024] The temperature range of a is 300–450℃;

[0025] The range of b is 150–200℃;

[0026] The range of c is 1.5 to 2.5h.

[0027] A better gradient temperature calcination strategy is:

[0028] The temperature range of a is 390–420℃;

[0029] The range of b is 180–200℃;

[0030] The range of c is 1.8 to 2.2h.

[0031] In detail, the first stage of calcination temperature is a, and the calcination time is c. The range of a is 300-450℃, and c is 1.5-2.5h. The calcination temperature in this stage is the lowest. During this process, the lithium source in the mixed lithium material first transforms into a molten state and fully contacts and fuses with the oxide of the precursor, which is conducive to the uniform and rapid progress of the next reaction.

[0032] After the first stage of calcination is completed, the temperature is gradually increased for the next stage of calcination. The calcination temperature is a+b, the calcination time is c, which is 1.5 to 2.5 hours, and the temperature gradient b is 150 to 200℃. The calcination temperature in this stage is higher than 450℃ but lower than 700℃, allowing the mixed lithium material to react fully and form spinel-structured crystals. Because the calcination temperature is lower than 700℃, high-voltage spinel nickel-manganese oxide with ordered cations is formed.

[0033] After the second stage of calcination, a final calcination is performed with a gradient temperature increase. The calcination temperature is a+2b, the calcination time is 2–6 hours (2c), and the temperature gradient (b) is 150–200℃. This stage of calcination has the highest temperature, which on the one hand promotes the continuous growth of lithium nickel manganese oxide crystals formed in the second stage of calcination and improves the surface structure, thereby increasing crystallinity. On the other hand, the higher calcination temperature rapidly disrupts the ordered cation arrangement, resulting in a disordered spinel structure. After calcination, the final product is obtained: a high-voltage spinel lithium nickel manganese oxide cathode material modified by gradient temperature calcination.

[0034] By employing a gradient temperature calcination strategy, the structure and composition of the high-voltage spinel lithium nickel manganese oxide product were optimized. A three-stage continuous gradient temperature calcination process was used, overcoming the coupling between cation order and trivalent manganese content inherent in existing synthesis processes. The resulting lithium nickel manganese oxide cathode material is a spherical spinel-phase lithium nickel manganese oxide with a highly disordered cation arrangement and low trivalent manganese content. This material exhibits high lithium-ion diffusion capability, mitigating adverse phase transitions, reducing transition metal dissolution and the Jan Taylor effect, enhancing structural stability, and significantly improving the cycle stability and rate performance of the lithium nickel manganese oxide cathode.

[0035] Preferably, the heating rate during the pre-calcination and calcination processes is 3-10℃ / min; more preferably, the heating rate is 5℃ / min.

[0036] Preferably, the atmosphere during the pre-calcination and calcination processes is air;

[0037] Preferably, during the pre-calcination and calcination processes, the material is naturally cooled to room temperature.

[0038] The present invention also provides a lithium-ion battery, comprising the lithium nickel manganese oxide cathode material described in any one of the above technical solutions or the lithium nickel manganese oxide cathode material prepared by the preparation method described in any one of the above technical solutions.

[0039] The beneficial effects of this invention are:

[0040] This invention innovatively develops a gradient temperature calcination strategy. Instead of prolonged high-temperature calcination, a three-stage continuous gradient temperature increase is employed, allowing for the preparation of modified lithium nickel manganese oxide with disordered cations and low trivalent manganese content in a single calcination step. The disordered structure endows this lithium nickel manganese oxide with high lithium-ion diffusion capability and smaller volumetric strain during delithiation and lithium insertion processes. The low trivalent manganese content reduces the Jan Taylor effect and the dissolution of transition metals, especially manganese, at the source, stabilizing the spinel structure and significantly improving the cycle stability and rate performance of the lithium nickel manganese oxide cathode.

[0041] This invention provides a high-voltage spinel lithium nickel manganese oxide cathode material modified by gradient temperature calcination. This cathode can operate stably for a long time in a voltage range of 3.5-5.0V, and at 25℃ and 0.2C (1C = 147mAh g / g). -1 At current density, it has 135.9 mAh g. -1 Discharge capacity. Capacity retention is greater than 80% after 1100 cycles at a 1C current density.

[0042] Compared to common synthesis strategies, this invention innovatively proposes a gradient temperature calcination strategy. This strategy overcomes the coupling between cation order and trivalent manganese content caused by existing synthesis processes. Lithium nickel manganese oxide prepared by gradient temperature calcination exhibits beneficial electrochemical performance characteristics such as spherical morphology, disordered structure, and low trivalent manganese content. It can improve lithium-ion diffusion capacity, mitigate unfavorable phase transitions, reduce transition metal dissolution and the Jan Taylor effect, and enhance structural stability.

[0043] This invention uses only inexpensive transition metals such as nickel and manganese, eliminating dependence on cobalt and resulting in low cost. Furthermore, the gradient temperature calcination process achieves an average calcination temperature below 900°C and a shorter calcination time, leading to lower energy consumption. This invention is simple to operate, inexpensive, and produces products with stable cycle performance, making it suitable for large-scale industrial production. Attached Figure Description

[0044] Figure 1 The images show the XRD patterns of the cathode materials prepared in Example 1 and Comparative Examples 1 and 2 of this invention.

[0045] Figure 2 The images shown are SEM images of the cathode materials prepared in Example 1 and Comparative Examples 1 and 2 of this invention.

[0046] Figure 3 The graph shows the charge-discharge curves of the coin cells assembled in Embodiment 1 and Comparative Examples 1 and 2 of the present invention at a room temperature and a current density of 0.2C.

[0047] Figure 4 The graph shows the cycle performance of the button cells assembled in Embodiment 1 and Comparative Examples 1 and 2 of the present invention at a 1C rate.

[0048] Figure 5 The diagram shows the rate performance of the button cells assembled in Embodiment 1 and Comparative Examples 1 and 2 of this invention. Detailed Implementation

[0049] The present invention will now be described in further detail with reference to the accompanying drawings.

[0050] Example 1

[0051] This embodiment provides a high-voltage spinel lithium nickel manganese oxide cathode material modified by gradient temperature calcination, including the following steps:

[0052] Weigh the precursor Ni 0.25 Mn 0.75 (OH)2 and lithium carbonate, wherein the molar ratio of nickel in the precursor to lithium in the lithium source is 0.5:1.05;

[0053] The weighed precursor was calcined at 500℃ for 2 hours to obtain the precursor oxide. The calcination atmosphere was air, the heating rate was 5℃ / min, and after calcination, the sample was allowed to cool naturally to room temperature and then removed for later use.

[0054] The precursor oxide obtained in the previous step and the prepared lithium carbonate are manually ground and mixed evenly to obtain a mixed lithium material.

[0055] The mixed lithium material was calcined using a gradient temperature method, with an initial calcination temperature of 400℃ and a temperature gradient of 200℃, as detailed below:

[0056] The first stage of calcination was carried out at 400℃ for 2 hours.

[0057] The second stage of calcination was carried out at 600℃ for 2 hours.

[0058] The third stage of calcination was carried out at 800℃ for 4 hours.

[0059] In this process, the atmosphere during each calcination stage is air, and the three stages are carried out continuously with a heating rate of 5℃ / min. After calcination, the samples are naturally cooled to room temperature and then removed to obtain high-voltage spinel lithium nickel manganese oxide cathode material modified by gradient temperature calcination.

[0060] In this embodiment, the XRD pattern and SEM morphology image of the cathode material are as follows: Figure 1 , Figure 2 As shown, the cathode material is formed by the agglomeration of rod-shaped primary particles into spherical secondary particles with a particle size of 2-3 micrometers. These spherical cathode particles are more easily attached to the current collector and maintain structural stability during cycling, making them less prone to breakage and ensuring the cycling stability of the material. The rod-shaped primary particles shorten the diffusion distance of lithium ions, contributing to improved rate performance and discharge capacity. XRD patterns indicate that its phase is spinel lithium nickel manganese oxide, without any impurities.

[0061] Weigh the corresponding positive electrode active material, conductive agent, and binder into a mixer at a mass ratio of 8:1:1, and add an appropriate amount of N-methylpyrrolidone solvent (NMP) to mix evenly, forming a uniform, viscous slurry. Then, use a scraper to evenly coat the slurry onto aluminum foil. Dry the aluminum foil in an 80℃ forced-air oven, and then bake it in an 80℃ vacuum oven for 12 hours. Roll-press the dried electrode sheet to obtain an electrode sheet of uniform thickness. After removing the weight of the aluminum foil itself, the area loading of the positive electrode active material on one side is 3-5 mg / cm². 2 .

[0062] The above-mentioned cathode material was cut into pieces, weighed, and assembled into CR2025 batteries. Electrochemical performance tests were then conducted. The test results are as follows: Figure 3 , Figure 4 , Figure 5 As shown. This positive electrode can operate stably in a voltage range of 3.5-5.0V, at 25℃ and 0.2C (1C = 147mAh g). -1 It exhibits a discharge capacity of 135.9 mAh g⁻¹ at the specified current density. After 1100 cycles at 1C, the capacity retention is greater than 80%.

[0063] Example 2

[0064] This embodiment provides a high-voltage spinel lithium nickel manganese oxide cathode material modified by gradient temperature calcination, which is basically the same as that in Embodiment 1, except that:

[0065] The lithium source is lithium hydroxide, not lithium carbonate.

[0066] Example 3

[0067] This embodiment is basically the same as embodiment 1, except that:

[0068] In step (1), the molar ratio of nickel in the precursor to lithium in the lithium source is 0.5:1.1.

[0069] Example 4

[0070] This embodiment is basically the same as embodiment 1, except that:

[0071] In steps (2) and (4), the heating rate for all calcination processes is 10 °C / min.

[0072] Comparative Example 1

[0073] This comparative example provides a high-voltage spinel lithium nickel manganese oxide cathode material without gradient temperature calcination modification. The specific steps are as follows:

[0074] Weigh the precursor Ni 0.25 Mn 0.75(OH)2 and lithium carbonate, wherein the molar ratio of nickel in the precursor to lithium in the lithium source is 0.5:1.05;

[0075] The precursor and lithium carbonate weighed in the previous step are manually ground and mixed evenly to obtain a lithium mixture.

[0076] The high-temperature sintering of the mixed lithium material is carried out in two stages: pre-calcination and calcination.

[0077] The mixed lithium material underwent the first stage of pre-calcination: calcination at 500℃ for 6 hours; then natural cooling to room temperature to obtain the pre-calcined material;

[0078] The pre-calcined material undergoes a second stage of calcination: calcination at 900℃ for 12 hours;

[0079] The atmosphere during both pre-calcination and calcination was air, and the heating rate was 5℃ / min. After calcination, the sample was allowed to cool naturally to room temperature and then removed. A lithium nickel manganese oxide cathode material without gradient temperature calcination modification was obtained.

[0080] In this comparative example, the XRD pattern and SEM morphology of the prepared cathode material are as follows: Figure 1 , Figure 2 As shown, the cathode material still exhibits a spherical morphology, but the primary particles grow larger during high-temperature calcination, resulting in a decrease in the cathode's specific surface area. XRD patterns indicate that its phase is spinel lithium nickel manganese oxide, without any impurity phases.

[0081] The battery assembly technique is the same as in Example 1, and the electrochemical performance test results are as follows: Figure 3 , Figure 4 , Figure 5 As shown.

[0082] Comparative Example 2

[0083] This comparative example provides a high-voltage spinel lithium nickel manganese oxide cathode material without gradient temperature calcination modification. The specific steps are as follows:

[0084] Weigh the precursor Ni 0.25 Mn 0.75 (OH)2 and lithium carbonate, wherein the molar ratio of nickel in the precursor to lithium in the lithium source is 0.5:1.05;

[0085] The precursor and lithium carbonate weighed in the previous step are manually ground and mixed evenly to obtain a mixed lithium material.

[0086] The mixed lithium material is sintered at high temperature. The sintering process is carried out in two stages: pre-calcination and calcination.

[0087] The mixed lithium material underwent a first-stage pre-calcination: calcination at 500℃ for 6 hours; then it was naturally cooled to room temperature to obtain the pre-calcined material; the pre-calcined material underwent a second-stage calcination: calcination at 900℃ for 12 hours;

[0088] The atmosphere during both pre-calcination and calcination was air, and the heating rate was 5℃ / min. After calcination, the samples were allowed to cool naturally to room temperature before being removed.

[0089] Annealing treatment. The material obtained in step 3 was kept at 650℃ for 4 hours, with a heating rate of 5℃ / min and a cooling rate of 3℃ / min. The material was then removed at room temperature to obtain a lithium nickel manganese oxide cathode material that had undergone low-temperature annealing treatment.

[0090] In this comparative example, the XRD pattern and SEM morphology of the prepared cathode material are as follows: Figure 1 , Figure 2 As shown, the cathode material still exhibits a spherical morphology, and the XRD spectrum indicates that its phase is spinel lithium nickel manganese oxide, without any impurities.

[0091] The battery assembly technique is the same as in Example 1, and the electrochemical performance test results are as follows: Figure 3 , Figure 4 , Figure 5 As shown. The following are the test results:

[0092] The high-voltage lithium nickel manganese oxide cathode materials prepared in the embodiments and comparative examples of the present invention were characterized and tested. Figure 1 The XRD patterns of gradient-temperature calcined modified lithium nickel manganese oxide and unmodified materials are shown. All materials are pure spinel lithium nickel manganese oxide, and no impurity phases unrelated to the target product were found. The composition of ordered and disordered phases was identified by Rietveld refinement. The disordered phase accounted for 99.53% in Example 1, which is a highly disordered spinel lithium nickel manganese oxide structure. Comparative Example 2 has a higher proportion of ordered phase (14.51%).

[0093] Figure 2 The images show SEM images of the cathode materials prepared in Example 1 and Comparative Examples 1 and 2 of this invention. The cathode material modified by gradient temperature calcination is formed by the agglomeration of rod-shaped primary particles into spherical secondary particles with a particle size of 2 to 3 micrometers. Although the materials in Comparative Examples 1 and 2 are also spherical, the primary particles are significantly larger, which is not conducive to the diffusion of lithium ions.

[0094] Figure 3 This is a charge-discharge curve of the coin cells assembled in Example 1 and Comparative Examples 1 and 2 at a room temperature and a current density of 0.2C. All materials exhibit a high voltage plateau of 4.7V and a low voltage plateau of 4V. By comparing the size of the 4V plateau in Example 1 and Comparative Example 1, the gradient temperature calcined modified lithium nickel manganese oxide cathode has a lower Mn content. 3+ content.

[0095] Table 1. Discharge specific capacity and coulombic efficiency of the examples and comparative examples.

[0096]

[0097] As shown in Table 1, compared to Comparative Example 1, the lithium-ion battery provided by this invention exhibits higher capacity in 1C cycling and higher coulombic efficiency in the first cycle. This is attributed to the synergistic regulation of cation order and M by gradient temperature calcination modification. n3+ It has two major advantages: disordered structure and low trivalent manganese content.

[0098] Table 2. Rate performance and long-cycle performance of the examples and comparative examples.

[0099]

[0100] Table 2 shows that by comparing several examples and comparative examples, the gradient temperature calcination modified material has a higher discharge capacity at a higher current density. The resulting disordered cation and low trivalent manganese structure can suppress unfavorable phase transitions and reduce the dissolution of transition metals, thus exhibiting better capacity retention. After 1100 cycles, the capacity retention rate is 85.2%.

Claims

1. A high-voltage spinel lithium nickel manganese oxide cathode material modified by gradient temperature calcination, characterized in that, The lithium nickel manganese oxide cathode material is formed by the agglomeration of primary rod-shaped particles into spherical secondary particles with a spherical morphology and a particle size range of 2 to 3 micrometers. The lithium nickel manganese oxide cathode material is spinel-phase lithium nickel manganese oxide with a trivalent manganese mass fraction of less than 5 wt%.

2. The high-voltage spinel lithium nickel manganese oxide cathode material modified by gradient temperature calcination according to claim 1, characterized in that, The lithium nickel manganese oxide cathode material is a 5V high-voltage spinel structure with the chemical formula Li. 1+x Ni 0.5 Mn 1.5 O4, where x is 0 to 0.1; The trivalent manganese mass fraction of the lithium nickel manganese oxide cathode material is 1-3% wt%.

3. The high-voltage spinel lithium nickel manganese oxide cathode material modified by gradient temperature calcination according to claim 1, characterized in that, The cations in the lithium nickel manganese oxide cathode material are highly disordered, with the disordered phase accounting for 95.0% to 99.9% of the total spinel phase.

4. A method for preparing a gradient temperature calcined modified high-voltage spinel lithium nickel manganese oxide cathode material according to any one of claims 1-3, characterized in that, Includes the following steps: Step (1): The precursor with a nickel-manganese molar ratio of 1:3 is pre-calcined to obtain the precursor oxide; Step (2): The oxide of the precursor is thoroughly mixed with the lithium source to obtain a mixed lithium material; Step (3): The mixed lithium material is calcined at a gradient temperature to finally obtain a high-voltage spinel lithium nickel manganese oxide cathode material.

5. The method for preparing a high-voltage spinel lithium nickel manganese oxide cathode material modified by gradient temperature calcination according to claim 4, characterized in that, In step (1), the precursor is Ni. 0.25 Mn 0.75 (OH)2, Ni 0.25 Mn 0.75 CO3, Ni 0.25 Mn 0.75 One or more of C2O4.

6. The method for preparing a high-voltage spinel lithium nickel manganese oxide cathode material modified by gradient temperature calcination according to claim 4, characterized in that, In step (1), the pre-calcination temperature is 300-600℃; the pre-calcination time is 2-5h.

7. The method for preparing a high-voltage spinel lithium nickel manganese oxide cathode material modified by gradient temperature calcination according to claim 4, characterized in that, In step (2), the molar ratio of nickel in the precursor oxide to lithium in the lithium source is 0.5:(1~1.1); In step (2), the lithium source is one or more of lithium hydroxide, lithium acetate, lithium nitrate, and lithium carbonate.

8. The method for preparing a high-voltage spinel lithium nickel manganese oxide cathode material modified by gradient temperature calcination according to claim 4, characterized in that, Step (3) is as follows: the first calcination temperature is a, the temperature gradient is b, and the calcination time is c. The three calcination stages are continuously heated and calcined, with temperatures of a, a+b, and a+2b, and calcination times of c, c, and 2c, respectively. This process is called gradient temperature calcination. in: The temperature range of a is 300–450℃; The range of b is 150–200℃; The range of c is 1.5 to 2.5h.

9. The method for preparing a high-voltage spinel lithium nickel manganese oxide cathode material modified by gradient temperature calcination according to claim 8, characterized in that, During the pre-calcination and calcination processes, the heating rate is 3-10℃ / min; The atmosphere during the pre-calcination and calcination processes is air; During the pre-calcination and calcination processes, the material is naturally cooled to room temperature.

10. A lithium-ion battery, characterized in that, The lithium nickel manganese oxide cathode material includes any one of the lithium nickel manganese oxide cathode materials described in claims 1-3 or any one of the lithium nickel manganese oxide cathode materials prepared by the preparation method described in claims 4-9.

Images