Nickel-manganese lithium high-voltage single-platform positive electrode material based on ordered phase regulation and preparation method thereof

Abstract

This invention discloses a high-voltage single-platform cathode material of lithium nickel manganese oxide based on ordered phase modulation and its preparation method. The preparation method of the lithium nickel manganese oxide cathode material of this invention includes the following steps: S1, mixing a lithium source, a manganese source, and a nickel source according to Li… + :Mn 3+ :Ni 2+ The precursor powder was mixed in a molar ratio of (1-1.2):1.5:0.5 and then subjected to high-energy ball milling to obtain nanoscale precursor powder; S2, the nanoscale precursor powder was calcined at 650-750℃ to form P4 3 32 The space group ordered phase structure yields the lithium nickel manganese oxide cathode material LiNi. 0.5 Mn 1.5 O4. This invention achieves material structure optimization in one step, improves raw material utilization, reduces energy consumption, and constructs nanoscale particles in situ through high-energy ball milling. Combined with a precise sintering process, it repairs the disordered phase defects of traditional lithium nickel manganese oxide materials into ordered phases, achieving stable output from a single 4.7 V high-voltage platform.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of preparation of lithium ion battery active positive electrode materials, and particularly relates to a high-voltage single-platform positive electrode material of lithium nickel-manganese oxide (LiNi 0.5 Mn 1.5 O4) based on ordered phase regulation and a preparation method thereof. BACKGROUND

[0002] The lithium nickel-manganese oxide (LiNi 0.5 Mn 1.5 O4, LNMO) is used as a high-voltage lithium ion battery positive electrode material, and is highly concerned in the fields of power batteries and energy storage due to its high energy density (≥600 Wh / kg) and low cost advantage. However, the traditional LNMO material is prone to double-voltage platform phenomenon (4.0 V and 4.7 V) due to the Jahn-Teller distortion effect of Mn 3+ ions in the crystal structure, resulting in unbalanced lithium ion deintercalation dynamics, capacity attenuation and cycle stability degradation.

[0003] The prior art adopts surface coating (such as Al2O3, Li3PO4) or bulk doping (such as Fe, Cr) means to inhibit the generation of Mn 3+ However, the surface coating layer can significantly hinder the lithium ion transmission channel, resulting in a decrease of ion conductivity by ≥30% (compared with the uncoated material), and the bulk doping process needs to introduce a heterogeneous metal element in the calcination process at a high temperature (≥900℃), which not only induces the formation of impurity phases (such as NiO and Li x Ni y O), but also increases the production cost by more than 40%. In addition, in the conventional preparation process, the conventional ball milling is difficult to realize the uniform dispersion of nanoscale particles (≤100 nm) due to the speed limitation and insufficient shear force, and the deviation of the precursor particle size distribution leads to local component segregation in the sintering process; at the same time, the low control precision of the sintering temperature is easy to promote the formation of disordered phase structures (space group Fd-3m ), aggravate the lattice oxygen vacancy concentration, and finally cause the splitting of the double-voltage platform (4.0 V platform accounts for ≥30%) and the significant capacity attenuation in the first cycle.

[0004] In recent years, through precise structure regulation, the Mn 3+The elimination of disordered phase and the construction of ordered phase are widely considered as the key way to break the performance bottleneck of LNMO. However, current researches mostly rely on complex templates or expensive noble metal additives (such as platinum, gold), which not only have poor process compatibility, but also significantly increase the cost (at least 50% increase in material cost), making it difficult to meet the actual needs of large-scale production. Therefore, developing an efficient preparation method for LNMO ordered phase reconstruction through precise process regulation without doping or coating has become a core technical challenge in the field of lithium battery materials. SUMMARY

[0005] The purpose of the present application is to provide a nickel-manganese lithium oxide high-voltage single-platform positive electrode material based on ordered phase regulation and a preparation method thereof. The preparation method is based on the synergistic regulation of high-energy ball milling and high-temperature sintering. By in-situ constructing a nanoscale precursor through high-energy ball milling, and combining a precise sintering process, the ordered phase structure of the nickel-manganese lithium oxide positive electrode material is reconstructed, and the material structure is optimized. P4 3 32 The space group ordered phase is reconstructed, and the Mn 3+ Ion-induced Jahn-Teller distortion and double-voltage platform (4.0 V and 4.7 V) interference are completely eliminated. The method of the present application does not require doping or coating process, and the material structure optimization is completed in one step. The raw material utilization rate is improved, the production cost is reduced compared with the traditional process, and the obtained positive electrode material has a first circle discharge energy density of more than 600.66 Wh / kg, which is suitable for large-scale industrialized preparation in the field of power batteries and energy storage.

[0006] To achieve the above purpose, the technical scheme adopted by the present application is as follows:

[0007] In a first aspect, the present application provides a preparation method of a nickel-manganese lithium oxide positive electrode material, comprising the following steps:

[0008] S1, mixing a lithium source, a manganese source and a nickel source in a molar ratio of Li + :Mn 3+ :Ni 2+ = (1-1.2):1.5:0.5, and then performing high-energy ball milling treatment to obtain a nanoscale precursor powder;

[0009] S2, high-temperature calcining the nanoscale precursor powder at 650-750 DEG C to form an ordered phase structure with a space group, thereby obtaining the nickel-manganese lithium oxide positive electrode material LiNi P4 3 32 Mn 0.5 O4. 1.5

[0010] The powder average particle size of the nickel-manganese lithium oxide positive electrode material is 30-900 nm.

[0011] ​Based on the above scheme, the present application will take lithium source, manganese source and nickel source as raw materials, mix according to accurate molar ratio, obtain nano-sized precursor powder through high-energy ball milling; then through high-temperature sintering of muffle furnace, induce Ni 2+ / Mn 4+ Order occupation at lattice 4b / 12d site, form P4 3 32 Space group ordered phase structure, completely eliminate Mn 3+ Ion-induced double-voltage platform (4.0 V and 4.7 V) interference, realize single 4.7 V high-voltage platform stable output, show excellent electrochemical performance in test, provide a low-cost, high-performance positive electrode solution for high-energy density lithium ion battery.

[0012] In the preparation method of the above lithium nickel manganese oxide positive electrode material, the molar ratio of the lithium source, the nickel source and the manganese source is calculated according to the stoichiometric ratio of LiNi 0.5 Mn 1.5 O4, research finds that, using Li + :Mn 3+ :Ni 2+ = (0.9-1.2):1.5:0.5, excess lithium source may occupy non-ideal lattice site, cause spinel structure distortion, form heterogeneous phase (such as rock salt phase), lithium source deficiency, part of Mn 4+ Be reduced to Mn 3+ , induce Jahn-Teller distortion, cause lattice expansion and structure collapse. Alternatively, the mixing of the lithium source, the manganese source and the nickel source is carried out according to the molar ratio of Li + :Mn 3+ :Ni 2+ = (1-1.2):1.5:0.5, the lithium nickel manganese oxide positive electrode material prepared in this range can form P4 3 32 Space group ordered phase structure, realize single 4.7 V high-voltage platform stable output, preferably (1-1.05):1.5:0.5, more preferably 1.05:1.5:0.5. When the lithium source, the nickel source and the manganese source are mixed according to the molar ratio of Li + :Mn 3+ :Ni 2+ =1.05:1.5:0.5, the charge and discharge performance is best. Alternatively, the lithium source is one or more of lithium carbonate, lithium hydroxide, lithium nitrate, lithium acetate and lithium oxalate; the manganese source is one or more of manganese sesquioxide, manganese trioxide, manganese dioxide, manganese acetate and manganese nitrate; the nickel source is one or more of nickel oxide, nickel hydroxide, nickel nitrate, nickel acetate and nickel oxalate. As an example, the lithium source in the precursor powder is lithium carbonate, the manganese source is manganese sesquioxide, and the nickel source is nickel oxide.

[0013] In the preparation method of the lithium nickel manganese oxide cathode material, further, the lithium source is battery grade, purity ≥ 99.9%; the manganese source is sub-micron particles, purity ≥ 98%, particle size ≤ 500 nm; the nickel source is nano particles, purity ≥ 99.95%, particle size ≤ 100 nm; the mixing step is carried out in an argon glove box with water and oxygen content < 0.01 ppm, which means that the water content and oxygen content are both less than 0.01 ppm.

[0014] In the preparation method of the lithium nickel manganese oxide cathode material, the term "high-energy ball milling" is a material preparation technology (dry milling) that uses the high-speed rotation or vibration of a ball mill to make hard balls collide, grind, and stir the raw materials, and crush the powder into nano / sub-micron particles, induce mechanical alloying or amorphous material. As an example, the high-energy ball milling uses a SPEX8000D high-energy ball mill (brand SPEX SamplePrep) or a JX-2G high-energy planetary ball mill (brand Jingxin).

[0015] Further, in the high-energy ball milling step, a SPEX 8000D high-energy ball mill is used, the ball-to-material ratio is (8-12):1, such as 10:1, the ball milling speed is 1200-1725 r / min, and the ball milling time is 1-2 hours, preferably 60 min at 1725 rpm; the high-energy ball milling is carried out in an inert atmosphere. Unlike micron-sized particles, the present application refines the particle size through high-energy ball milling technology, improves the uniformity and reactivity of the material, and controls the particle size of the precursor powder to the nano level after high-energy ball milling, ensuring high reactivity and ion diffusion capacity of the material. The control of the ball milling time and speed ensures the uniform distribution of lithium, nickel, and manganese ions, obtains nano particles, shortens the lithium ion diffusion path, and reduces the Mn 3+ (Jahn-Teller distortion source), but too long ball milling time will cause particle agglomeration, composition segregation, and energy waste, and the efficiency and performance need to be balanced by optimizing the time-speed combination (such as high-energy ball milling for 1-2 hours).

[0016] In the above-mentioned method for preparing lithium nickel manganese oxide cathode material, the method further includes a step of grinding and sieving the nanoscale precursor powder before high-temperature calcination; preferably, in the grinding and sieving step, grinding is performed for 0.5 to 1 hour (e.g., 0.5 hours), sieving through an 80 to 120 mesh (e.g., 100 mesh) sieve, and the proportion of residue on the sieve is ≤0.5%. Grinding can improve the uniformity of the sample, which helps to obtain a uniform heating effect and chemical reaction in the subsequent calcination process, promotes solid-phase reaction and eliminates agglomeration, thereby improving calcination efficiency; finer particles are heated more uniformly during calcination, which can reduce the time and temperature required for calcination, thereby improving calcination efficiency and shortening the lithium-ion diffusion path.

[0017] In the above-mentioned preparation method of lithium nickel manganese oxide cathode material, the LNMO material obtained after calcination has uniform grains, low impurity content, and good working performance. It can remain stable in a high-voltage range above 4.7 V and exhibits good cycle stability and rate performance. The holding temperature directly affects the degree of lattice ordering. Studies have found that when calcined at high temperatures of 650–750℃, lithium nickel manganese oxide o-LNMO exhibits the best performance. P4 3 32 The space group has an ordered phase structure, but at excessively high temperatures it becomes... Fd-3m The disordered phase structure makes it impossible to eliminate the dual plateau. High-temperature calcination temperatures include, but are not limited to, 650℃, 700℃, and 750℃, with 700℃ being preferred.

[0018] In the high-temperature calcination step, the heating rate is 5 °C / min. The heating rate directly determines the structure and performance of the lithium nickel manganese oxide cathode material by influencing crystal growth kinetics, component diffusion, and defect formation. Slow heating can reduce thermal stress, avoid lattice distortion caused by excessive temperature gradients, and promote Ni… 2+ / Mn 4+ Ordered occupancy within the crystal lattice forms a uniform spinel structure. P4 3 32 Space group), suppressing Mn 3+ The generation of Jahn-Teller distortion sources is possible; however, excessively rapid heating may exacerbate the volatilization of lithium sources (such as Li2CO3). A rapid heating rate will exacerbate the volatilization loss of lithium sources (such as Li2CO3), causing the lithium content to deviate from the stoichiometric ratio and triggering the formation of additional defects. A slow heating rate will lead to increased energy consumption.

[0019] In the high-temperature calcination step, the holding time is 10–24 h, preferably 12–16 h, and more preferably 16 h. Insufficient holding time will lead to insufficient Mn production. 3+ Residual material can cause structural distortions, and excessive length may trigger other side reactions.

[0020] In the high-temperature calcination process, the spinel structure is optimized by precisely regulating the heating rate and holding parameters. By optimizing the temperature and holding time, the generation of Mn 3+ is effectively inhibited, forming a stable P4 3 32 ordered phase structure, reducing the double-voltage platform phenomenon in the material, thereby improving the high-voltage stability and cycle life of LNMO. As an example, the high-temperature calcination is carried out in an air muffle furnace.

[0021] In the preparation method of the above-mentioned lithium nickel manganese oxide positive electrode material, further, the method further comprises a step of grinding the powder after high-temperature calcination. As an example, the grinding time is 30 min. By grinding, the uniformity of the sample can be improved, which is more conducive to improving the electrochemical performance of the lithium ion battery.

[0022] In the preparation method of the above-mentioned lithium nickel manganese oxide positive electrode material, the powder average particle size of the lithium nickel manganese oxide positive electrode material LiNi 0.5 Mn 1.5 O4 includes but is not limited to 50 nm, 198 nm, 32 nm, 213 nm, 346 nm, 869 nm, and preferably 50 nm. As an example, the powder average particle size is measured by a laser particle size analyzer.

[0023] In a second aspect, the present application provides a lithium nickel manganese oxide positive electrode material prepared by the method described in any one of the above. The lithium nickel manganese oxide (LiNi 0.5 Mn 1.5 O4) positive electrode material completely eliminates the Jahn-Teller distortion and double-voltage platform (4.0 V and 4.7 V) interference caused by Mn 3+ ions, and realizes stable output of a single 4.7 V high-voltage platform.

[0024] In a third aspect, the present application provides a lithium ion battery comprising the above-mentioned lithium nickel manganese oxide positive electrode material.

[0025] The present application has the following beneficial effects:

[0026] (1) Breakthrough in green preparation technology: innovatively using one-step high-energy ball milling process without the need for template agent and surfactant assistance, in-situ constructing nano-sized particles (~50 nm), effectively shortening the lithium ion diffusion path, and significantly improving the material rate performance.

[0027] (2) Precise structure regulation mechanism: through high-temperature sintering process, the ordered occupation of Ni 2+ / Mn 4+ at 4b / 12d sites is induced, and the Jahn-Teller distortion and double-voltage platform interference caused by Mn 3+Caused 4.0 V abnormal voltage platform, realized single 4.7 V high voltage platform stable output.

[0028] (3) The cycle performance is obviously improved: after the assembled lithium metal battery is cycled for 200 times under the condition of 1C, the ordered phase structure lithium nickel manganese oxide material still maintains 96.1 mAh / g of single voltage platform reversible capacity, and the capacity retention rate is increased by 11.5% compared with the disordered phase material (86.2 mAh / g).

[0029] (4) Energy density breakthrough: the first circle discharge energy density breaks through 600.66 Wh / kg, which is increased by 9.2% compared with the traditional LNMO material system (≤550 Wh / kg), and reaches the advanced level of lithium-rich manganese-based positive electrode material.

[0030] (5) Low-cost material innovation: a cobalt-free high-voltage positive electrode material system is successfully developed, and the comprehensive cost of the material is reduced by 30% compared with the cobalt-based system, which provides a new low-cost positive electrode material solution for high-energy-density lithium ion batteries.

[0031] In summary, the method of the application does not need doping or coating process, realizes material structure optimization in one step, improves raw material utilization rate, reduces energy consumption, realizes green and efficient preparation, reduces comprehensive cost by 30% compared with the cobalt-based system, is suitable for large-scale application in the field of power batteries and energy storage, and through in-situ construction of nanoscale particles by high-energy ball milling combined with precise sintering process, the disordered phase defects of the traditional lithium nickel manganese oxide material are repaired to ordered phase, and single 4.7 V high voltage platform stable output is realized. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 A flow chart of a high-voltage single-platform lithium nickel manganese oxide (LiNi 0.5 Mn 1.5 O4) positive electrode material preparation method based on high-energy ball milling and high-temperature sintering synergistic regulation.

[0033] Figure 2 The XRD spectrum of the lithium nickel manganese oxide (LiNi 0.5 Mn 1.5 O4) sample prepared in Example 1 of the application.

[0034] Figure 3 The SEM graph of the lithium nickel manganese oxide (LiNi 0.5 Mn 1.5 O4) sample prepared in Example 1 of the application.

[0035] Figure 4 The lithium nickel manganese oxide (LiNi 0.5 Mn 1.5O4) X-ray photoelectron spectroscopy of the sample.

[0036] Figure 5 LiNi0.5Mn1.5O4 was prepared for Example 1 (a) and Comparative Example 5 (b) of the present application. 0.5 Mn 1.5 O4) sample multi-cycle charge-discharge curve comparison chart. DETAILED DESCRIPTION

[0037] The present application will be further described in conjunction with the specific embodiments. The examples provided below are only for the purpose of illustrating the present application, and are not intended to limit the scope of the present application. The examples provided below can serve as a guide for further improvement by those of ordinary skill in the art, and do not in any way constitute a limitation on the present application.

[0038] In the following examples, the methods used are conventional methods, and are performed according to the techniques or conditions described in the literature in the art or according to the product instructions, unless otherwise specified. In the following examples, the materials, reagents, etc. used are commercially available, unless otherwise specified.

[0039] In the following examples, Li2CO3 is battery grade, with a purity of ≥ 99.9%; Mn2O3 is sub-micron grade particles, with a purity of ≥ 98% and a particle size of ≤ 500 nm; and NiO is nano-grade particles, with a purity of ≥ 99.95% and a particle size of ≤ 100 nm.

[0040] In the following examples, the high-energy ball mill is a SPEX8000D high-energy ball mill, brand SPEX SamplePrep.

[0041] In the following examples, the powder particle size is measured by an LS-609 laser particle size analyzer.

[0042] Example 1

[0043] LiNi0.5Mn1.5O4 high-voltage single-platform positive electrode material based on ordered phase regulation was prepared according to the flowchart shown in Figure 1, and the specific steps are as follows: 0.5 Mn 1.5 O4) high-voltage single-platform positive electrode material, according to the following steps:

[0044] (1) LiNi0.5Mn1.5O4 was used as the target product, and the raw material mass of Li2CO3 (battery grade, 99.9%), NiO (nano-grade, 99.95%) and Mn2O3 (sub-micron grade, 98%) was accurately calculated according to the stoichiometric ratio of Li:Mn:Ni = 1.05:1.5:0.5 (lithium excess of 5% to compensate for high-temperature calcination loss). 0.5 Mn 1.5 O4 as the target product, and the raw material mass of Li2CO3 (battery grade, 99.9%), NiO (nano-grade, 99.95%) and Mn2O3 (sub-micron grade, 98%) was accurately calculated according to the stoichiometric ratio of Li:Mn:Ni = 1.05:1.5:0.5 (lithium excess of 5% to compensate for high-temperature calcination loss). + :Mn 3+ :Ni 2+ =1.05:1.5:0.5 (lithium excess of 5% to compensate for high-temperature calcination loss), and the raw material mass of Li2CO3 (battery grade, 99.9%), NiO (nano-grade, 99.95%) and Mn2O3 (sub-micron grade, 98%) was accurately calculated.

[0045] (2) 0.3879 mg of lithium carbonate, 0.3735 mg of nickel oxide, and 1.2083 mg of manganese sesquioxide were weighed and loaded into a 50 mL ball mill jar. The mixed powder and zirconia balls were mixed at a mass ratio of 1:10. The mixing process was carried out in an argon glove box with a water and oxygen content of less than 0.01 ppm. After sealing with high-purity argon, the ball mill jar was removed.

[0046] (3) A SPEX8000D high-energy ball milling system was used for ball milling treatment. The main shaft speed was set to 1725 rpm. After 60 minutes of continuous ball milling, the precursor powder was obtained.

[0047] (4) The obtained precursor powder was ground in a mortar for 30 minutes and sieved through a 100 mesh sieve. The residue ratio was less than or equal to 0.5%. The uniform corundum crucible was loaded into a muffle furnace for high-temperature calcination. The temperature was set to 700°C, the holding time was 16 hours, and the heating rate was 5°C / min.

[0048] (5) The powder obtained after high-temperature calcination was ground in a mortar for 30 minutes. The average particle size of the powder was 50 nm. A high-voltage single-platform lithium nickel manganese oxide (LiNi 0.5 Mn 1.5 O4) positive electrode material was obtained.

[0049] Example 2

[0050] A high-voltage single-platform lithium nickel manganese oxide (LiNi 0.5 Mn 1.5 O4) positive electrode material based on ordered phase regulation was prepared according to the flowchart shown in Figure 1. The specific steps are as follows:

[0051] (1) LiNi 0.5 Mn 1.5 O4 was used as the target product. According to the stoichiometric ratio of Li + :Mn 3+ :Ni 2+ =1.05:1.5:0.5 (lithium excess of 5% to compensate for high-temperature calcination loss), the required raw material mass of Li2CO3 (battery grade, 99.9%), NiO (nanoscale, 99.95%), and Mn2O3 (submicron grade, 98%) was accurately calculated.

[0052] (2) 0.3879 mg of lithium carbonate, 0.3735 mg of nickel oxide, and 1.2083 mg of manganese sesquioxide were weighed and loaded into a 50 mL ball mill jar. The mixed powder and zirconia balls were mixed at a mass ratio of 1:10. The mixing process was carried out in an argon glove box with a water and oxygen content of less than 0.01 ppm. After sealing with high-purity argon, the ball mill jar was removed.

[0053] (3) The SPEX8000D high-energy ball milling system was used for ball milling treatment, the main shaft rotation speed was set to 1725 rpm, and the precursor powder was obtained after 60 min of continuous ball milling.

[0054] (4) The obtained precursor powder was ground in a mortar for 30 min, sieved through a 100-mesh screen, the sieve residue ratio was ≤0.5%, and then uniformly loaded into a corundum crucible and placed in a muffle furnace for high-temperature calcination, the temperature was set to 750°C, the holding time was 16 h, and the heating rate was 5°C / min.

[0055] (5) The powder obtained after high-temperature calcination was ground in a mortar for 30 min, the average particle size of the powder was 198 nm, and a lithium nickel manganese oxide (LiNi 0.5 Mn 1.5 O4) positive electrode material was obtained.

[0056] Example 3

[0057] A lithium nickel manganese oxide (LiNi 0.5 Mn 1.5 O4) high-voltage single-platform positive electrode material based on ordered phase regulation was prepared according to the flowchart shown in 1, and the specific steps were as follows:

[0058] (1) LiNi 0.5 Mn 1.5 O4 was used as the target product, and the stoichiometric ratio of Li + :Mn 3+ :Ni 2+ was 1.05:1.5:0.5 (lithium excess of 5% to compensate for high-temperature calcination loss), and the required raw material mass of Li2CO3 (battery grade, 99.9%), NiO (nanoscale, 99.95%) and Mn2O3 (submicron grade, 98%) was accurately calculated.

[0059] (2) 0.3879 mg of lithium carbonate, 0.3735 mg of nickel oxide and 1.2083 mg of manganese sesquioxide were weighed and loaded into a 50 mL ball mill jar, the mixed powder and zirconia balls were mixed at a mass ratio of 1:10, the mixing process was carried out in an argon glove box with water and oxygen content <0.01 ppm, and then the ball mill jar was sealed with high-purity argon and removed.

[0060] (3) The SPEX8000D high-energy ball milling system was used for ball milling treatment, the main shaft rotation speed was set to 1725 rpm, and the precursor powder was obtained after 60 min of continuous ball milling.

[0061] (4) The obtained precursor powder is ground in a mortar for 30 min, sieved through a 100 mesh screen, the proportion of the residue is ≤0.5%, and then uniformly loaded into a corundum crucible and placed in a muffle furnace for high-temperature calcination, the temperature is set to 650 DEG C, the holding time is 16 h, and the heating rate is 5 DEG C / min.

[0062] (5) The powder obtained after high-temperature calcination is ground in a mortar for 30 min, and the average particle size of the powder is 32 nm to obtain a lithium nickel manganese oxide (LiNi 0.5 Mn 1.5 O4) positive electrode material.

[0063] Example 4

[0064] A high-voltage single-platform lithium nickel manganese oxide (LiNi 0.5 Mn 1.5 O4) positive electrode material process based on ordered phase regulation is prepared according to the flowchart shown in 1, and compared with example 1, only Li + :Mn 3+ :Ni 2+ =1:1.5:0.5 is adjusted, and the specific steps are as follows:

[0065] (1) LiNi 0.5 Mn 1.5 O4 is taken as the target product, the stoichiometric ratio of Li + :Mn 3+ :Ni 2+ =1:1.5:0.5 (lithium excess 5% to compensate for high-temperature calcination loss) is used to accurately calculate the required raw material mass of Li2CO3 (battery grade, 99.9%), NiO (nanoscale, 99.95%) and Mn2O3 (submicron grade, 98%).

[0066] (2) 0.3879 mg of lithium carbonate, 0.3735 mg of nickel oxide and 1.2083 mg of manganese sesquioxide are weighed and loaded into a 50 mL ball mill jar, the mixed powder and zirconium dioxide balls are mixed at a mass ratio of 1:10, the mixing process is carried out in an argon glove box with water and oxygen content <0.01 ppm, and then the sealed high-purity argon is removed.

[0067] (3) A SPEX8000D high-energy ball milling system is used for ball milling treatment, the main shaft rotation speed is set to 1725 rpm, and the precursor powder is obtained after continuous ball milling for 60 min.

[0068] (4) The obtained precursor powder is ground in a mortar for 30 min, sieved through a 100 mesh screen, the proportion of the residue is ≤0.5%, and then uniformly loaded into a corundum crucible and placed in a muffle furnace for high-temperature calcination, the temperature is set to 650 DEG C, the holding time is 16 h, and the heating rate is 5 DEG C / min.

[0069] (5) The powder obtained after high-temperature calcination was ground in a mortar for 30 min, and the average particle size of the powder was 213 nm, obtaining a lithium nickel manganese oxide (LiNi 0.5 Mn 1.5 O4) positive electrode material.

[0070] Example 5

[0071] A high-voltage single-platform lithium nickel manganese oxide (LiNi 0.5 Mn 1.5 O4) positive electrode material based on ordered phase regulation was prepared according to the flowchart shown in 1, and only Li + :Mn 3+ :Ni 2+ =1.2:1.5:0.5 was adjusted compared with Example 1, and the specific steps were as follows:

[0072] (1) LiNi 0.5 Mn 1.5 O4 was taken as the target product, and the raw material mass of Li2CO3 (battery grade, 99.9%), NiO (nanometer grade, 99.95%) and Mn2O3 (submicron grade, 98%) was accurately calculated according to the stoichiometric ratio of Li + :Mn 3+ :Ni 2+ =1.2:1.5:0.5 (lithium excess 5% to compensate for high-temperature calcination loss).

[0073] (2) 0.3879 mg of lithium carbonate, 0.3735 mg of nickel oxide and 1.2083 mg of manganese sesquioxide were weighed and loaded into a 50 mL ball mill jar. The mixed powder and zirconium dioxide balls were mixed at a mass ratio of 1:10. The mixing process was carried out in an argon glove box with water and oxygen content <0.01 ppm, and the high-purity argon was filled to seal and then removed.

[0074] (3) SPEX8000D high-energy ball milling system was used for ball milling treatment, and the main shaft rotation speed was set to 1725 rpm. After continuous ball milling for 60 min, the precursor powder was obtained.

[0075] (4) The obtained precursor powder was ground in a mortar for 30 min, sieved through a 100 mesh sieve, and the residue ratio was ≤0.5%. The uniform corundum crucible was placed in a muffle furnace for high-temperature calcination, the temperature was set to 700℃, the holding time was 16 h, and the heating rate was 5 ℃ / min.

[0076] (5) The powder obtained after high-temperature calcination was ground in a mortar for 30 min, and the average particle size of the powder was 213 nm, obtaining a lithium nickel manganese oxide (LiNi 0.5 Mn 1.5 O4) positive electrode material.

[0077] Example 6

[0078] Example 6 0.5 Mn 1.5 O4)high-voltage single-platform positive electrode material based on the ordered phase regulation process shown in Figure 1, the difference compared with Example 1 is that JX-2G is used to adjust the powder particle size, the specific steps are as follows:

[0079] (1) LiNi 0.5 Mn 1.5 O4 is used as the target product, according to the stoichiometric ratio of Li + :Mn 3+ :Ni 2+ =1.05:1.5:0.5 (5% excess of lithium to compensate for high-temperature calcination loss), the required Li2CO3 (battery grade, 99.9%), NiO (nanoscale, 99.95%) and Mn2O3 (submicron grade, 98%) raw material mass is accurately calculated.

[0080] (2) 0.3879 mg of lithium carbonate, 0.3735 mg of nickel oxide, and 1.2083 mg of manganese sesquioxide are weighed and placed in a 50 mL ball mill jar. The mixed powder and zirconia balls are mixed at a mass ratio of 1:10. The mixing process is carried out in an argon glove box with water and oxygen content <0.01 ppm. After sealing with high-purity argon, it is removed.

[0081] (3) Ball milling system JX-2G is used for ball milling treatment, the main shaft speed is set to 800 rpm, and the precursor powder is obtained after 8 h of continuous ball milling.

[0082] (4) The obtained precursor powder is ground in a mortar for 30 min and uniformly loaded into a corundum crucible and placed in a muffle furnace for high-temperature calcination. The temperature is set to 700℃, the holding time is 16 h, and the heating rate is 5℃ / min.

[0083] (5) The powder obtained after high-temperature calcination is ground in a mortar for 30 min, and the average particle size of the powder is 869 nm. The lithium nickel manganese oxide (LiNi 0.5 Mn 1.5 O4) positive electrode material is obtained.

[0084] Comparative Example 1

[0085] The preparation steps are the same as Example 1, except that JX-2G ball milling system is used and the ball milling speed and time are adjusted, the specific steps are as follows:

[0086] (1) LiNi 0.5 Mn 1.5 O4 is used as the target product, according to the stoichiometric ratio of Li + :Mn3+ Ni 2+ = 1.05:1.5:0.5 stoichiometric ratio (5% excess of lithium to compensate for high temperature calcination loss), accurately calculate the required raw material mass of Li2CO3 (battery grade, 99.9%), NiO (nanometer grade, 99.95%) and Mn2O3 (submicron grade, 98%).

[0087] (2) 0.3879 mg of lithium carbonate, 0.3735 mg of nickel oxide, and 1.2083 mg of manganese sesquioxide were weighed and loaded into a 50 mL ball mill jar. The mixed powder was mixed with zirconia beads at a mass ratio of 1:10. The mixing process was carried out in an argon glove box with water and oxygen content <0.01 ppm. After sealing with high-purity argon, it was removed.

[0088] (3) Ball milling was performed using a ball milling system JX-2G, with a spindle speed of 450 rpm. After 4 hours of continuous ball milling, the precursor powder was obtained.

[0089] (4) The obtained precursor powder was ground in a mortar for 30 minutes and uniformly loaded into a corundum crucible, which was placed in a muffle furnace for high temperature calcination. The temperature was set to 700°C, the holding time was 16 hours, and the heating rate was 5°C / min.

[0090] (5) The powder obtained after high temperature calcination was ground in a mortar for 30 minutes. The average particle size of the powder was 3.267 μm, and the lithium nickel manganese oxide (LiNi 0.5 Mn 1.5 O4) positive electrode material was obtained.

[0091] Comparative Example 2

[0092] The preparation steps were the same as in Example 1, except that the JX-2G ball milling system was used and the ball milling speed and time were adjusted. The specific steps are as follows:

[0093] (1) LiNi 0.5 Mn 1.5 O4 was used as the target product. According to the stoichiometric ratio of Li + :Mn 3+ :Ni 2+ = 1.05:1.5:0.5 (5% excess of lithium to compensate for high temperature calcination loss), the raw material mass of Li2CO3 (battery grade, 99.9%), NiO (nanometer grade, 99.95%) and Mn2O3 (submicron grade, 98%) was accurately calculated.

[0094] (2) 0.3879 mg of lithium carbonate, 0.3735 mg of nickel oxide, and 1.2083 mg of manganese sesquioxide were weighed into a 50 mL ball mill jar, and the mixed powder was mixed with zirconia balls at a mass ratio of 1:10. The mixing process was performed in an argon glove box with a water and oxygen content of less than 0.01 ppm, and the ball mill jar was sealed with high-purity argon and removed.

[0095] (3) Ball milling was performed using a ball milling system JX-2G, and the main shaft rotation speed was set to 500 rpm. After 10 h of continuous ball milling, a precursor powder was obtained.

[0096] (4) The obtained precursor powder was ground in a mortar for 30 min, uniformly loaded into a corundum crucible, and placed in a muffle furnace for high-temperature calcination. The temperature was set to 700°C, the holding time was 16 h, and the heating rate was 5°C / min.

[0097] (5) The powder obtained after high-temperature calcination was ground in a mortar for 30 min, and the average particle size of the powder was 1.753 μm. A lithium nickel manganese oxide (LiNi 0.5 Mn 1.5 O4) positive electrode material was obtained.

[0098] Comparative Example 3

[0099] Compared with Example 1, only the high-temperature sintering temperature was adjusted to 800°C, and the specific steps were as follows:

[0100] (1) LiNi 0.5 Mn 1.5 O4 was used as the target product. According to the stoichiometric ratio of Li + :Mn 3+ :Ni 2+ =1.05:1.5:0.5 (lithium excess of 5% to compensate for high-temperature calcination loss), the required raw material mass of Li2CO3 (battery grade, 99.9%), NiO (nanoscale, 99.95%), and Mn2O3 (submicron grade, 98%) was accurately calculated.

[0101] (2) 0.3879 mg of lithium carbonate, 0.3735 mg of nickel oxide, and 1.2083 mg of manganese sesquioxide were weighed into a 50 mL ball mill jar, and the mixed powder was mixed with zirconia balls at a mass ratio of 1:10. The mixing process was performed in an argon glove box with a water and oxygen content of less than 0.01 ppm, and the ball mill jar was sealed with high-purity argon and removed.

[0102] (3) Ball milling was performed using a SPEX8000D high-energy ball milling system, and the main shaft rotation speed was set to 1725 rpm. After 60 min of continuous ball milling, a precursor powder was obtained.

[0103] (4) The obtained precursor powder was ground in a mortar for 30 min, sieved through a 100 mesh screen, the proportion of the residue was ≤0.5%, and then uniformly loaded into a corundum crucible and placed in a muffle furnace for high-temperature calcination, the temperature was set to 800 DEG C, the holding time was 16 h, and the heating rate was 5 DEG C / min.

[0104] (5) The powder obtained after high-temperature calcination was ground in a mortar for 30 min, the average particle size of the powder was 410 nm, and a lithium nickel manganese oxide (LiNi 0.5 Mn 1.5 O4) positive electrode material was obtained.

[0105] Comparative Example 4

[0106] Compared with Example 1, only the high-temperature sintering temperature was adjusted to 900 DEG C, and the specific steps were as follows:

[0107] (1) LiNi 0.5 Mn 1.5 O4 was taken as the target product, and the stoichiometric ratio of Li + :Mn 3+ :Ni 2+ was 1.05:1.5:0.5 (lithium excess 5% to compensate for high-temperature calcination loss), and the required raw material mass of Li2CO3 (battery grade, 99.9%), NiO (nanometer grade, 99.95%) and Mn2O3 (submicron grade, 98%) was accurately calculated.

[0108] (2) 0.3879 mg of lithium carbonate, 0.3735 mg of nickel oxide and 1.2083 mg of manganese sesquioxide were weighed and loaded into a 50 mL ball mill jar, the mixed powder and zirconium dioxide balls were mixed at a mass ratio of 1:10, the mixing process was carried out in an argon glove box with water and oxygen content <0.01 ppm, and then the sealed high-purity argon was removed.

[0109] (3) A SPEX8000D high-energy ball milling system was used for ball milling treatment, the main shaft rotation speed was set to 1725 rpm, and the precursor powder was obtained after continuous ball milling for 60 min.

[0110] (4) The obtained precursor powder was ground in a mortar for 30 min, sieved through a 100 mesh screen, the proportion of the residue was ≤0.5%, and then uniformly loaded into a corundum crucible and placed in a muffle furnace for high-temperature calcination, the temperature was set to 900 DEG C, the holding time was 16 h, and the heating rate was 5 DEG C / min.

[0111] (5) The powder obtained after high-temperature calcination was ground in a mortar for 30 min, the average particle size of the powder was 989 nm, and a lithium nickel manganese oxide (LiNi 0.5 Mn 1.5 O4) positive electrode material was obtained.

[0112] Comparative Example 5

[0113] Compared with Example 1, only the high-temperature sintering temperature is adjusted to 1000℃, and the specific steps are as follows:

[0114] (1) 0.3879 mg of lithium carbonate, 0.3735 mg of nickel oxide and 1.2083 mg of manganese sesquioxide were weighed and put into a 50 mL ball mill jar, and the mixed powder was mixed with zirconia balls at a mass ratio of 1:10. The mixing process was carried out in an argon glove box with water and oxygen content <0.01 ppm, and the high-purity argon was filled to seal and then removed. 0.5 Mn 1.5 O4 as the target product, according to the stoichiometric ratio of Li + :Mn 3+ :Ni 2+ =1.05:1.5:0.5 (5% excess of lithium to compensate for high-temperature calcination loss), the required raw material mass of Li2CO3 (battery grade, 99.9%), NiO (nanometer grade, 99.95%) and Mn2O3 (submicron grade, 98%) was accurately calculated.

[0115] (2) 0.3879 mg of lithium carbonate, 0.3735 mg of nickel oxide and 1.2083 mg of manganese sesquioxide were weighed and put into a 50 mL ball mill jar, and the mixed powder was mixed with zirconia balls at a mass ratio of 1:10. The mixing process was carried out in an argon glove box with water and oxygen content <0.01 ppm, and the high-purity argon was filled to seal and then removed.

[0116] (3) A SPEX8000D high-energy ball milling system was used for ball milling treatment, and the main shaft speed was set to 1725 rpm. After 60 min of continuous ball milling, the precursor powder was obtained.

[0117] (4) The obtained precursor powder was ground in a mortar for 30 min, sieved through a 100 mesh sieve, and the residue ratio was ≤0.5%. The uniform corundum crucible was placed in a muffle furnace for high-temperature calcination, the temperature was set to 1000℃, the holding time was 16 h, and the heating rate was 5 ℃ / min.

[0118] (5) The powder obtained after high-temperature calcination was ground in a mortar for 30 min, and the average particle size of the powder was 4.358 μm. The lithium nickel manganese oxide (LiNi 0.5 Mn 1.5 O4) positive electrode material was obtained.

[0119] Comparative Example 6

[0120] Compared with Example 1, only the stoichiometric ratio of Li + :Mn 3+ :Ni 2+ =0.9:1.5:0.5 was adjusted, and the specific steps were as follows:

[0121] (1) LiNi 0.5 Mn 1.5 O4 was used as the target product, and according to the stoichiometric ratio of Li + :Mn 3+ :Ni2+ With a stoichiometric ratio of 0.9:1.5:0.5 (5% lithium excess to compensate for high-temperature calcination loss), the required raw material masses of Li2CO3 (battery grade, 99.9%), NiO (nanoscale, 99.95%), and Mn2O3 (submicron scale, 98%) are accurately calculated.

[0122] (2) Weigh 0.3879 mg of lithium carbonate, 0.3735 mg of nickel oxide and 1.2083 mg of manganese trioxide, put them into a 50 mL ball mill jar, mix the powder with zirconium dioxide balls at a mass ratio of 1:10, and carry out the mixing process in an argon glove box with a water oxygen content of <0.01 ppm. After filling with high-purity argon and sealing, remove the jar.

[0123] (3) The precursor powder was obtained by ball milling using a SPEX8000D high-energy ball milling system, with the spindle speed set at 1725 rpm and the ball milling continued for 60 min.

[0124] (4) Grind the obtained precursor powder in a mortar for 30 min, sieve it through a 100-mesh sieve, and the residue ratio is ≤0.5%. Place it evenly into a corundum crucible and calcine it in a muffle furnace at high temperature. The temperature is set to 700℃, the holding time is 16 h, and the heating rate is 5℃ / min.

[0125] (5) The powder obtained after high-temperature calcination was ground in a mortar for 30 min, and the average particle size of the powder was 289 nm, thus obtaining lithium nickel manganese oxide (LiNi). 0.5 Mn 1.5 O4) positive electrode material.

[0126] Test Implementation Examples

[0127] Lithium nickel manganese oxide (LiNi) prepared in Example 1 0.5 Mn 1.5 XRD pattern of O4 cathode material is shown below. Figure 2 ,from Figure 2 As can be seen, the crystal structure of this material was characterized by X-ray diffraction (XRD) spectroscopy. After calcination at 700℃, its diffraction peaks showed high uniformity, which is very consistent with the characteristics of spinel structure. Comparison with the PDF card indicates that lithium nickel manganese oxide (LiNi) exhibits high crystallinity. 0.5 Mn 1.5 O4 cathode material has been successfully prepared.

[0128] Lithium nickel manganese oxide (LiNi) prepared in Example 1 0.5 Mn 1.5 SEM images of O4) cathode materials, such as Figure 3 As shown, lithium nickel manganese oxide (LiNi) 0.5 Mn 1.5The O4) cathode material exhibits an octahedral morphology. X-ray photoelectron spectroscopy (XPS) was used to analyze the lithium nickel manganese oxide samples of Example 1 and Comparative Example 4, and the corresponding results are as follows: Figure 4 As shown, in Example 1, lithium nickel manganese oxide o-LNMO is P4 3 32 Space group ordered phase structure, comparative example 4 lithium nickel manganese oxide d-LNMO is Fd-3m Disordered phase structure. P4 3 32 Mn in ordered phase lithium nickel manganese oxide samples 3 + / Mn 4+ The relative content ratio of Mn was 0.48. 3+ The content is negligible to almost negligible; while Fd-3m Mn in disordered phase lithium nickel manganese oxide samples 3+ With Mn 4+ The comparison is 1.11, where Mn 3+ The significant increase indicates that a change occurred due to Mn 4+ To Mn 3+ The transformation of Mn 3+ The increased content exacerbates the structural distortion caused by the Jahn-Teller effect, leading to the dissolution of manganese (Mn) and irreversible degradation of the spinel structure, affecting the reversible insertion and extraction of lithium ions, and causing fluctuations in the voltage plateau.

[0129] Electrochemical performance

[0130] Lithium nickel manganese oxide (LiNi) was prepared using Examples 1-6 and Comparative Examples 1-6 above. 0.5 Mn 1.5 O4) A coin cell (CR2032) with positive electrode material (positive electrode material: lithium nickel manganese oxide, negative electrode material: lithium metal, lithium electrolyte: 1.0 M LiPF6 in EC:DMC:DEC=1:1:1, separator: PE separator. The composition of the positive electrode slurry is as follows: lithium nickel manganese oxide positive electrode material: PVDF: carbon black = 8:1:1. The discharge specific capacity and capacity retention of this coin cell were tested at 25 degrees Celsius and 1 C.

[0131] The experimental results are shown in Table 1.

[0132] Lithium nickel manganese oxide (LiNi) prepared in Examples 1-6 and Comparative Examples 1-6 0.5 Mn 1.5 Table 1 shows the single-voltage plateau discharge specific capacity and capacity retention of the coin cells assembled with the cathode materials in Example 1 and Comparative Example 5. The charge-discharge curves of the coin cells assembled with the cathode materials prepared in Example 1 and Comparative Example 5 are shown in Table 1. Figure 5 .

[0133] Table 1, battery material performance of each example and comparative example

[0134]

[0135] As can be seen from Table 1, the button cells assembled by the lithium nickel manganese oxide positive electrode materials prepared in Examples 1-6 all have a 4.7V single voltage platform, the discharge specific capacity of Example 1 is 96.1 mAh / g after long cycle of 200 cycles, the capacity retention rate is 75.4%, the discharge specific capacity of Example 2 is 91.7 mAh / g after long cycle of 200 cycles, the capacity retention rate is 73.2%, the discharge specific capacity of Example 3 is 90.2 mAh / g after long cycle of 200 cycles, the capacity retention rate is 72.5%, the discharge specific capacity of Example 4 is 91.3 mAh / g after long cycle of 200 cycles, the capacity retention rate is 71.5%, the discharge specific capacity of Example 5 is 87.9 mAh / g after long cycle of 200 cycles, the capacity retention rate is 69.7%, and the discharge specific capacity of Example 6 is 90.2 mAh / g after long cycle of 200 cycles, the capacity retention rate is 72.4%; it can be seen that the high-voltage single-platform lithium nickel manganese oxide positive electrode material of the application has P4 3 32 The space group ordered phase, the button cell assembled under the condition of 1 C can be stably cycled, has a single voltage discharge specific capacity of 96.1 mAh / g at most, and has a capacity retention rate of 75.4%, and has good charge-discharge performance. Among them, Example 1 combines high-energy ball milling (1725 rpm, 1 h) with a calcination process of 700°C, and is prepared by nano-sized precursor and ordered phase reconstruction, which effectively inhibits the generation of Mn 3+ and structural defects, and is the optimal path for realizing single-voltage platform high capacity and long cycle stability of lithium nickel manganese oxide positive electrode material.

[0136] As can be seen from the comparison results of Example 1 and Example 6, the realization of double-platform elimination requires that the average particle size of the powder reaches the nanometer level and is uniformly distributed, although the JX-2G system refines the particles by high-speed, but due to the insufficient energy density, the particle size distribution is wide, and the local lattice distortion after sintering causes the degree of cation mixing to increase, and the cycle performance is significantly lower than that of the SPEX8000D high-energy ball milling system.

[0137] The coin cells assembled from the lithium nickel manganese oxide cathode materials prepared in Comparative Examples 1-6 all exhibited dual voltage plateaus of 4.0 V and 4.7 V. Comparative Example 1 showed a discharge specific capacity of 87.4 mAh / g after 200 cycles, with a capacity retention of 69.4%; Comparative Example 2 showed 80.3 mAh / g, with a capacity retention of 63.6%; Comparative Example 3 showed 90.4 mAh / g, with a capacity retention of 74.0%; Comparative Example 4 showed 86.2 mAh / g, with a capacity retention of 69.1%; Comparative Example 5 showed 76.5 mAh / g, with a capacity retention of 81.1%; and Comparative Example 6 showed 81.7 mAh / g, with a capacity retention of 65.2%. Therefore, the coin cells assembled from the lithium nickel manganese oxide cathode materials prepared in Comparative Examples 1-6... Fd-3m Disordered lithium nickel manganese oxide cathode materials cannot eliminate the double plateau, resulting in poor charge-discharge performance. Comparative Example 3, with its high-temperature calcination combined with an oxygen atmosphere, suppressed the Mn content. 3+ The content of Mn is reduced, and the volume change is buffered by the flexible lattice with disordered structure, reducing particle cracks and thus improving cycle stability. Therefore, its performance is better than other comparative examples, but it still cannot completely eliminate trace amounts of Mn. 3+ The Jahn-Teller distortion effect leads to the coexistence of two voltage plateaus (4.7 V and 4.0 V), causing local lattice stress accumulation and limiting further improvement in cycling performance. However, Example 1, with its low-temperature calcination combined with a nanoscale precursor, constructs a highly ordered spinel phase, completely eliminating Mn. 3+ Only Ni is retained 2+ / Ni 4+ The single-platform reaction (4.7 V) significantly reduces the risk of structural distortion.

[0138] The comparison between Example 1 and Comparative Example 1 shows a significant difference in particle refinement efficiency between the SPEX8000D high-energy ball milling system and the JX-2G ball milling system. In Example 1, the precursor prepared by the SPEX8000D high-energy ball mill had a particle size ≤50nm, which, after sintering, formed… P4 3 32 Ordered phase, Mn 3+ The content is ≤2%; however, the ball milling particles in the JX-2G ball milling system are coarsened, leading to a decrease in capacity retention. The ball milling performance of the JX-2G ball milling system is significantly degraded due to particle coarsening and impurity contamination.

[0139] The comparison results between Example 1 and Comparative Example 2 show that prolonged ball milling in the JX-2G system may disrupt the stoichiometry and form impurity phases.

[0140] The comparison results between Example 1 and Comparative Examples 3-5 show that higher calcination temperatures induce the formation of lithium nickel manganese oxide cathode materials.Fd-3m Disordered phase structure, its Mn 3+ The existence of Mn 3+ / Mn 4+ The redox reaction results in the coexistence of two voltage plateaus (4.7 V + 4.0 V), making it impossible to eliminate the two plateaus.

[0141] Figure 5 Example 1 P4 3 32 Comparative Example 5 Fd-3m The constant current charge-discharge curves of lithium nickel manganese oxide (NMO) cathode materials were obtained. The ordered phase NMO exhibited superior electrochemical properties, showing a higher average discharge voltage and stronger capacity retention compared to the disordered phase. The charge-discharge curves of the ordered NMO sample did not show a significant plateau near 4.0 V, indicating that the Mn content in the spinel structure... 3+ The content of Mn is very low and can be ignored, consistent with the XPS results. Conversely, at 4.0 V and 4.65 V, the electrochemical spectra of the disordered phase lithium nickel manganese oxide sample exhibit two distinct activities (pseudo-plateau and plateau), corresponding to Mn 3+ / Mn 4+ Redox pairs and Ni 2+ / Ni 3+ Solid solution reaction coupling.

[0142] The comparison results between Example 1 and Comparative Example 6 show that the lithium source was insufficient, and some Mn... 4+ Reduced to Mn 3+ This causes Jahn-Teller distortion, leading to lattice expansion and structural collapse, and also makes it impossible to achieve stable output from a single 4.7 V high-voltage platform.

[0143] In summary, this invention constructs lithium nickel manganese oxide (LiNi) through an ordered phase modulation strategy. 0.5 Mn 1.5 O4) high-voltage single-platform cathode materials exhibit significant performance advantages compared to traditional disordered phase structure materials. This preparation method overcomes the limitations of traditional doping / coating processes, constructing nanoscale precursors in situ through high-energy ball milling, combined with precise high-temperature sintering control, achieving… P4 3 32 Directional construction of ordered phase structures in space groups completely eliminates Mn 3+Ion and dual-voltage plateau interference ensure that the material exhibits a stable single high-voltage plateau output of 4.7 V. The process of this invention has significant green manufacturing characteristics: improved raw material utilization, lower energy consumption compared to traditional solid-state methods, lower overall cost compared to cobalt-based cathode systems, and no toxic reagents involved throughout the process, meeting the requirements of sustainable development. This technology provides a new pathway for the large-scale preparation of high-energy-density lithium-ion batteries, especially suitable for power batteries and large-scale energy storage, and has broad prospects for industrial application.

[0144] The present invention has been described in detail above. Those skilled in the art will recognize that the invention can be practiced in a wide range of ways with equivalent parameters, concentrations, and conditions without departing from its spirit and scope. While specific embodiments have been provided, it should be understood that further modifications can be made to the invention. In summary, according to the principles of the invention, this application is intended to include any changes, uses, or improvements to the invention, including modifications made using conventional techniques known in the art that depart from the scope disclosed herein.

Claims

1. A method for preparing a lithium nickel manganese oxide cathode material, characterized in that, The method comprises the following steps: S1, the lithium source, manganese source and nickel source are mixed in a molar ratio of Li + :Mn 3+ :Ni 2+ = (1-1.2):1.5:0.5, and then high-energy ball milling is performed to obtain a nano-sized precursor powder; In the high-energy ball milling step, a SPEX 8000D high-energy ball mill is used, the ball-to-material ratio is (8-12):1, the ball milling speed is 1200-1725 r / min, and the ball milling time is 1-2 hours. The high-energy ball milling is performed in an inert atmosphere. S2, high-temperature calcining the nanoscale precursor powder at 650-750°C to form P4 3 32 a space group ordered phase structure, to obtain the lithium nickel manganese oxide cathode material LiNi 0.5 Mn 1.5 O4; In the high-temperature calcination step, the heating rate is 5 ℃ / min. In the high-temperature calcination step, the holding time is 10-24 hours. The average particle size of the powder of the lithium nickel manganese oxide positive electrode material is 30-900 nm.

2. The method for preparing lithium nickel manganese oxide cathode material according to claim 1, characterized in that: The lithium source is one or more of lithium carbonate, lithium hydroxide, lithium nitrate, lithium acetate and lithium oxalate; The manganese source is one or more of manganese sesquioxide, manganese trioxide, manganese dioxide, manganese acetate and manganese nitrate; The nickel source is one or more of nickel oxide, nickel hydroxide, nickel nitrate, nickel acetate and nickel oxalate.

3. The method of claim 1 or 2, wherein the method further comprises: The lithium source is battery grade, with a purity of ≥99.9%; ​ The manganese source is sub-micron grade particles, with a purity of ≥98% and a particle size of ≤500 nm; The nickel source is nano-grade particles, with a purity of ≥99.95% and a particle size of ≤100 nm.

4. The method of claim 1-2, wherein the method is characterized by: The method further comprises a step of grinding and sieving the nano-grade precursor powder before high-temperature calcination, the grinding time is 0.5-1 hour, the sieving is performed through an 80-120 mesh sieve, and the proportion of sieve residue is ≤0.5%.

5. The method of claim 1-2, wherein the method is characterized by: The temperature of the high-temperature calcination is 700 ℃.

6. The method of claim 1-2, wherein the method is characterized by: The method further comprises a step of grinding the powder after high-temperature calcination.

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