High peak strength ratio positive electrode material and preparation method and application thereof

Abstract

The present invention belongs to the technical field of lithium ion batteries and discloses a positive electrode material with a high peak strength ratio and a preparation method and application thereof. The general formula of the positive electrode material is LiNi 1‑x‑y Co x Mn y M a N b O2, wherein 0≤x≤0.5, 0≤y≤0.6, a>0, b>0, and 0.002≤a+b≤0.04; M is at least two of Ni, Co, Mn, Zr, Nb, Sb, Y, Mo, P, S, or B; and N is at least one of Al, Mg, Ti, Si, La, Ga, Sr, Co, and Mn. The peak intensity ratio of the positive electrode material of the present invention is greater than 1.8, the Li / Ni mixing is less than 3%, and the high (003) / (104) peak intensity ratio (peak intensity ratio greater than 1.8) means a sharp decrease in cation mixing, thereby significantly improving the specific capacity and kinetic performance of the positive electrode material.

Description

Technical Field

[0001] The present invention belongs to the technical field of lithium-ion batteries, and in particular relates to a positive electrode material with a high peak strength ratio, a preparation method thereof, and an application thereof. Background Art

[0002] In the layered R-3m cathode material LiMO2, transition metal ions usually occupy the 3a position of the octahedron, and Li ions occupy the 3b position of the octahedron. 2+ With Li + The ionic radius of Ni 2+ With Li + When lithium and nickel occupy each other's sites, this is called lithium-nickel intercalation. Excessive lithium-nickel intercalation in the positive electrode material will block the channels for lithium ion intercalation and deintercalation, resulting in a significant reduction in the material's specific capacity.

[0003] Generally, the peak intensity ratio of (003) to (104) of a layered cathode material can qualitatively determine the degree of lithium-nickel mixing in the layered cathode material. When the I(003) / I(104) peak intensity ratio is greater than 1.2, it indicates that the layered cathode material has a good layered structure and a low degree of cation mixing; when the I(003) / I(104) peak intensity ratio is less than 1.2, it indicates that the cation mixing in the layered cathode material is high, the lithium ion intercalation and deintercalation of the material is hindered, and the specific capacity will be significantly reduced, thereby reducing the energy density of the battery material. Therefore, the preparation of a cathode material with low cation mixing has always been the goal of high-performance lithium-ion batteries. Summary of the Invention

[0004] The present invention aims to solve at least one of the technical problems existing in the above-mentioned prior art. To this end, the present invention provides a high peak strength ratio cathode material, a preparation method, and an application thereof. The high peak strength ratio improves the cation mixing in the cathode material, thereby improving the specific capacity and kinetic performance.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] A positive electrode material with the general formula LiNi 1-x-y Co x Mn y M a N b O2, wherein 0≤x≤0.5, 0≤y≤0.6, a>0, b>0, and 0.002≤a+b≤0.04, the M is at least two of Ni, Co, Mn, Zr, Nb, Sb, Y, Mo, P, S or B; the N is at least one of Al, Mg, Ti, Si, La, Ga, Sr, Co, and Mn.

[0007] Preferably, the value range of x is 0≤x≤0.3, and the value range of y is 0≤y≤0.5.

[0008] Preferably, the M is at least two of Ni, Zr, Nb, Sb, Y, Mo, P or B; and the N is at least one of Al, Mg, Ti, Si, Ga, Sr and Co.

[0009] Preferably, the LiNi 1-x-y Co x Mn y M a N b The intensity ratio of the (003) diffraction peak to the (104) diffraction peak of O2 is greater than 1.8.

[0010] Further preferably, the LiNi 1-x-y Co x Mn y M a N b The intensity ratio of the (003) diffraction peak to the (104) diffraction peak of O2 is greater than 2 and less than 10.

[0011] Preferably, the positive electrode material is LiNi 0.5457 Co 0.12 Mn 0.33 (ZrTi) 0.0028 Al 0.0015 O2、LiNi 0.5965 Co 0.05 Mn 0.35 Nb 0.0015 Mg 0.002 O2、LiNi 0.695 Co 0.05 Mn 0.25 (SbYB) 0.0035 Sr 0.0015 O2、LiNi 0.7931 Co 0.1 Mn 0.1 (ZrMoP) 0.0044 (GaTi) 0.0025 One of O2.

[0012] The present invention utilizes the different growth rates of different crystal faces in the crystal and uses additives to induce the growth of layered (003) crystal faces, thereby increasing the proportion of (003) crystal faces and preparing a positive electrode material with an ultra-high (003) / (104) peak intensity ratio. The ultra-high (003) / (104) peak intensity ratio means a sharp decrease in cation mixing, which can effectively improve Li + The deintercalation and intercalation ability, electrochemical properties and kinetic properties of the cathode materials.

[0013] According to the Bravais law of crystal growth, the relative growth rate of different crystal planes in a crystal is inversely proportional to the density of nodes on the facet network, and a high facet network density usually corresponds to a large facet network spacing. The larger the facet network spacing, the greater the facet network density, and generally, the smaller the facet index, the larger the facet network spacing. Therefore, in the R-3m layered cathode material, the (003) facet theoretically has the lowest facet growth rate, and the most direct way to obtain a high I(003) / I(104) peak intensity ratio is undoubtedly to increase the proportion of the (003) facet. According to the law of crystal growth, the faster the facet grows in the crystal, the easier it is to disappear, and the slower the facet grows, the easier it is to remain. Therefore, increasing the growth rate of high facet index facets, such as the (104) facet, accelerates their disappearance process, thereby increasing the proportion of the (003) facet with the slowest growth rate, thereby obtaining a cathode material with a high I(003) / I(104) peak intensity ratio.

[0014] A method for preparing a positive electrode material, wherein the method is used to prepare the positive electrode material.

[0015] Specifically, a method for preparing a positive electrode material includes the following steps:

[0016] Mixing a nickel-cobalt-manganese hydroxide precursor, a lithium source and an M-containing additive, and performing a first sintering to obtain a first-fired material;

[0017] The first-fired material is crushed, a N-containing additive is added and mixed, and then sintered for a second time to obtain the positive electrode material; the M-containing additive is at least two of Ni, Co, Mn, Zr, Nb, Sb, Y, Mo, P, S or B oxides or hydroxides; the N-containing additive is at least one of Al, Mg, Ti, Si, La, Ga, Sr, Co, and Mn oxides or hydroxides.

[0018] Preferably, the nickel-cobalt-manganese hydroxide precursor is prepared by a controlled crystallization method.

[0019] More preferably, the chemical formula of the nickel-cobalt-manganese hydroxide is Ni 1-d-e Co d Mn e (OH)2, where 0.01≤d≤0.5; 0.01≤e≤0.5.

[0020] Further preferably, the specific steps of the controlled crystallization method are: mixing a nickel salt solution, a cobalt salt solution, and a manganese salt solution, then adding a precipitant and a complexing agent, reacting, adjusting the pH to 9.5-11, solid-liquid separation, washing the solid phase, and drying to obtain nickel cobalt manganese hydroxide.

[0021] More preferably, the nickel salt solution is at least one of nickel sulfate and nickel chloride.

[0022] More preferably, the cobalt salt solution is at least one of cobalt sulfate and cobalt chloride.

[0023] More preferably, the manganese salt solution is at least one of manganese sulfate and manganese chloride.

[0024] More preferably, the complexing agent is an aqueous ammonia solution.

[0025] More preferably, the concentration of the aqueous ammonia solution is 0.3-0.6 mol / L.

[0026] More preferably, the precipitant is sodium hydroxide solution.

[0027] More preferably, the reaction temperature is 40-70° C., and the reaction time is 10-100 h.

[0028] More preferably, the washing is performed 3-5 times.

[0029] More preferably, the drying temperature is 100-120° C., and the drying time is 20-30 h.

[0030] More preferably, the drying gas is one of nitrogen and argon.

[0031] Preferably, the lithium source is at least one of LiOH and Li2CO3.

[0032] More preferably, the LiOH is at least one of fine powder LiOH and coarse particle LiOH.

[0033] Further preferably, the Li2CO3 is at least one of battery-grade Li2CO3, quasi-battery-grade Li2CO3, and industrial Li2CO3.

[0034] Preferably, the molar ratio of transition metal ions in the nickel-cobalt-manganese hydroxide precursor to lithium ions in the lithium source is 1:(1.02-1.07), that is, the lithium ratio (Li / Me) is 1.02-1.07.

[0035] Preferably, the M-containing additive is at least two of Ni, Co, Mn, Zr, Nb, Sb, Y, Mo, P, S or B oxides or hydroxides.

[0036] Preferably, the amount of the M-containing additive added is 800 to 4000 ppm (based on the mass of the precursor).

[0037] Preferably, the additive N is at least one of oxides or hydroxides of Al, Mg, Ti, Si, La, Ga, Sr, Co, and Mn.

[0038] Preferably, the temperature of the first sintering is 900-1100° C., and the time of the first sintering is 10-16 hours.

[0039] Preferably, the atmosphere of the first sintering and the second sintering is one of air and oxygen.

[0040] Preferably, the temperature of the second sintering is 400-600° C., and the time of the second sintering is 4-10 hours.

[0041] The present invention also provides a battery comprising the positive electrode material.

[0042] Compared with the prior art, the present invention has the following beneficial effects:

[0043] 1. LiNi, the positive electrode material of the present invention 1-x-y Co x Mn y M a N b The peak intensity ratio of O2 is greater than 1.8, the Li / Ni mixing is less than 3%, and the half-cell gram capacity exceeds 186mAh / g and can even reach 208mAh / g when discharged at a rate of 0.1C at 2.8-4.25V. The present invention utilizes the growth habits of different crystal faces in the crystal, promotes the growth rate of high crystal face index crystal faces through additives, accelerates their disappearance during the sintering process, and allows the (003) crystal face with a low crystal face growth rate to be retained, thereby increasing the proportion of (003) crystal faces in the material and preparing a positive electrode material with an ultra-high (003) / (104) peak intensity ratio; and the high (003) / (104) peak intensity ratio (peak intensity ratio greater than 1.8) means a sharp decrease in cation mixing, thereby significantly improving the gram capacity and kinetic performance of the positive electrode material. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 The X-ray diffraction pattern of the positive electrode material prepared in Example 1 of the present invention;

[0045] Figure 2 The X-ray diffraction pattern of the positive electrode material prepared in Example 2 of the present invention;

[0046] Figure 3 This is the X-ray diffraction pattern of the positive electrode material prepared in Example 3 of the present invention;

[0047] Figure 4 The X-ray diffraction pattern of the positive electrode material prepared in Example 4 of the present invention;

[0048] Figure 5 The X-ray diffraction pattern of the positive electrode material prepared in Comparative Example 1 of the present invention;

[0049] Figure 6The X-ray diffraction pattern of the positive electrode material prepared in Comparative Example 2 of the present invention;

[0050] Figure 7 This is the X-ray diffraction pattern of the positive electrode material prepared in Comparative Example 3 of the present invention;

[0051] Figure 8 This is a SEM image of the positive electrode material prepared in Example 3 of the present invention;

[0052] Figure 9 This is a graph showing the cycle capacity retention rate of the positive electrode materials prepared in Example 3 of the present invention and Comparative Example 2. DETAILED DESCRIPTION

[0053] The following will clearly and completely describe the concept and technical effects of the present invention in conjunction with the embodiments to fully understand the purpose, features and effects of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, other embodiments obtained by those skilled in the art without creative work are all within the scope of protection of the present invention.

[0054] Example 1

[0055] The positive electrode material of this embodiment has the chemical formula LiNi 0.5457 Co 0.12 Mn 0.33 (ZrTi) 0.0028 Al 0.0015 O2.

[0056] The preparation method of the positive electrode material of this embodiment has the following specific steps:

[0057] (1) Ni prepared by controlled crystallization 0.55 Co 0.12 Mn 0.33 The (OH)2 precursor was mixed with battery grade Li2CO3 (lithium ratio was 1.07) and additives ZrO2 and TiO2, wherein the addition amount of Zr and Ti was 2000ppm and 800ppm respectively (the precursor Ni 0.55 Co 0.12 Mn 0.33 After being loaded into a bowl, it enters a roller kiln and is sintered for the first time in an oxygen atmosphere at 935°C to obtain a first-fired material;

[0058] (2) The calcined material obtained in step (1) is coarsely crushed and finely crushed, and then uniformly mixed with Al2O3, with the amount of Al added being 1500ppm based on the weight of the crushed material. A secondary sintering is performed at 550°C in an oxygen atmosphere to obtain a positive electrode material.

[0059] Figure 1 This is the X-ray diffraction pattern of the positive electrode material prepared in Example 1. X-ray diffraction analysis of the positive electrode material prepared above revealed a (003) / (104) peak intensity ratio of 1.97. Further refinement using Fullprof revealed a Li / Ni mix of 1.5%. The positive electrode material prepared in Example 1 was fabricated into a battery and subjected to half-cell testing. Discharge was performed at a rate of 0.1C at 2.8-4.35V, and the gram capacity of the half-cell was 186mAh / g.

[0060] Example 2

[0061] The positive electrode material of this embodiment has the chemical formula LiNi 0.5965 Co 0.05 Mn 0.35 Nb 0.0015 Mg 0.002 O2.

[0062] The preparation method of the positive electrode material of this embodiment has the following specific steps:

[0063] (1) Ni prepared by controlled crystallization 0.6 Co 0.05 Mn 0.35 The (OH)2 precursor was mixed with battery grade Li2CO3 (lithium ratio was 1.06) and additives NiOOH and Nb2O5, wherein the addition amount of Ni and Nb was 1500ppm and 1500ppm respectively (precursor Ni 0.6 Co 0.05 Mn 0.35 After being loaded into a bowl, it enters a roller kiln and is sintered for the first time in an oxygen atmosphere at 927°C to obtain a first-fired material;

[0064] (2) The calcined material obtained in step (1) is coarsely crushed and finely crushed, and then uniformly mixed with Mg(OH)2, with the amount of Mg added being 2000 ppm based on the weight of the crushed material. A secondary sintering is performed at 500°C in an oxygen atmosphere to obtain a positive electrode material.

[0065] The positive electrode material prepared above was subjected to X-ray diffraction analysis (eg Figure 2 ), with a (003) / (104) peak intensity ratio of 1.93. Further refinement using Fullprof revealed a Li / Ni mix of 1.8%. The cathode material prepared in Example 2 was fabricated into a battery for half-cell testing. Discharge was performed at a rate of 0.1C at 2.8-4.35V, yielding a gram capacity of 195mAh / g.

[0066] Example 3

[0067] The positive electrode material of this embodiment has the chemical formula LiNi0.695 Co 0.05 Mn 0.25 (SbYB) 0.0035 Sr 0.0015 O2.

[0068] The preparation method of the positive electrode material of this embodiment has the following specific steps:

[0069] (1) Ni prepared by controlled crystallization 0.7 Co 0.05 Mn 0.25 The (OH)2 precursor and the powdered LiOH (according to the lithium ratio of 1.04) were mixed evenly with the additives Sb2O5, Y2O3, and B2O3, wherein the addition amounts of Sb, Y, and B were 2000ppm, 1000ppm, and 500ppm respectively (the precursor Ni 0.7 Co 0.05 Mn 0.25 After being loaded into a bowl, it enters a roller kiln and is sintered for the first time in an oxygen atmosphere at 915°C to obtain a first-fired material;

[0070] (2) The calcined material obtained in step (1) is coarsely crushed and finely crushed, and then uniformly mixed with SrCO3. The amount of Sr added is 1500 ppm based on the weight of the crushed material. Secondary sintering is performed at 450°C in an oxygen atmosphere to obtain a positive electrode material.

[0071] The positive electrode material prepared above was subjected to X-ray diffraction analysis (eg Figure 3 ), with a (003) / (104) peak intensity ratio of 2.03. Further refinement using Fullprof revealed a Li / Ni mix of 2.2%. The cathode material prepared in Example 3 was fabricated into a battery for half-cell testing. Discharge was performed at a rate of 0.1C at 2.8-4.35V, yielding a gram capacity of 201mAh / g.

[0072] Figure 8 This is the SEM image of the positive electrode material prepared in Example 3 of the present invention.

[0073] Example 4

[0074] The positive electrode material of this embodiment has the chemical formula LiNi 0.7931 Co 0.1 Mn 0.1 (ZrMoP) 0.0044 (GaTi) 0.0025 O2.

[0075] The preparation method of the positive electrode material of this embodiment has the following specific steps:

[0076] (1) Ni prepared by controlled crystallization0.8 Co 0.1 Mn 0.1 The (OH)2 precursor and the fine powder LiOH (according to the lithium ratio of 1.02) are mixed evenly with the additives ZrO2, MoO3, and Li3PO4, wherein the addition amounts of Sb, Y, and B are 2000ppm, 1000ppm, and 500ppm respectively (the precursor Ni 0.8 Co 0.1 Mn 0.1 After being loaded into a bowl, it enters a roller kiln and is sintered for the first time in an oxygen atmosphere at 870°C to obtain a first-fired material;

[0077] (2) The calcined material obtained in step (1) is coarsely crushed and finely crushed, and then uniformly mixed with Ga2O3 and TiO2. The amount of Ga and Ti added is 1500ppm and 1000ppm respectively based on the weight of the crushed material. Secondary sintering is performed at 370°C in an oxygen atmosphere to obtain a positive electrode material.

[0078] The positive electrode material prepared above was subjected to X-ray diffraction analysis (eg Figure 4 ), with a (003) / (104) peak intensity ratio of 2.08. Further refinement using Fullprof revealed a Li / Ni mix of 2.9%. The cathode material prepared in Example 4 was fabricated into a battery for half-cell testing. Discharge was performed at a rate of 0.1C at 2.8-4.35V, yielding a gram capacity of 208mAh / g.

[0079] Comparative Example 1

[0080] The positive electrode material of this comparative example has the chemical formula LiNi 0.5467 Co 0.12 Mn 0.33 Al 0.0015 (ZrTi) 0.0028 O2.

[0081] The preparation method of the positive electrode material of this comparative example has the following specific steps:

[0082] (1) Ni prepared by controlled crystallization 0.55 Co 0.12 Mn 0.33 The (OH)2 precursor is mixed with battery grade Li2CO3 (according to the lithium ratio of 1.07) and the additives ZrO2 and TiO2, wherein the addition amount of Zr and Ti is 2000ppm and 800ppm respectively (the precursor Ni 0.55 Co 0.12 Mn 0.33 After being loaded into a bowl, it enters a roller kiln and is sintered for the first time in an oxygen atmosphere at 935°C to obtain a first-fired material;

[0083] (2) The calcined material obtained in step (1) is coarsely crushed and finely crushed, and then uniformly mixed with Al2O3, with the amount of Al added being 1500ppm based on the weight of the crushed material. A secondary sintering is performed at 550°C in an oxygen atmosphere to obtain a positive electrode material.

[0084] Figure 5 This is the X-ray diffraction pattern of the positive electrode material prepared in Comparative Example 1 of the present invention. X-ray diffraction analysis of the positive electrode material prepared above revealed a (003) / (104) peak intensity ratio of 1.34. Further refinement using Fullprof revealed a Li / Ni mix of 3.6%. A half-cell test was conducted on a battery fabricated from the positive electrode material prepared in Comparative Example 1, with a discharge rate of 0.1C at 2.8-4.35V. The gram capacity of the half-cell was 175mAh / g.

[0085] Comparative Example 2

[0086] The positive electrode material of this comparative example has the chemical formula LiNi 0.695 Co 0.05 Mn 0.25 Sr 0.0015 (SbYB) 0.0035 O2.

[0087] The preparation method of the positive electrode material of this comparative example has the following specific steps:

[0088] (1) Ni prepared by controlled crystallization 0.7 Co 0.1 Mn 0.2 The (OH)2 precursor was mixed with powdered LiOH (with a lithium ratio of 1.02) and additive SrCO3, wherein the amount of Sr added was 15000ppm (precursor Ni 0.7 Co 0.1 Mn 0.2 After being loaded into a bowl, it enters a roller kiln and is sintered for the first time in an oxygen atmosphere at 915°C to obtain a first-fired material;

[0089] (2) The calcined material obtained in step (1) is coarsely crushed and finely crushed, and then mixed evenly with Sb2O5, Y2O3, and B2O3. The added amounts of Sb, Y, and B are 2000ppm, 1000ppm, and 500ppm, respectively, based on the weight of the crushed material. Secondary sintering is performed at 450°C in an oxygen atmosphere to obtain a positive electrode material.

[0090] The positive electrode material prepared above was subjected to X-ray diffraction analysis (eg Figure 6), and its (003) / (104) peak intensity ratio is 1.44. Further refinement using Fullprof yields a Li / Ni mixed arrangement of 4.9% in the material. The cathode materials prepared in Example 3 and Comparative Example 2 were prepared into batteries for half-cell testing. The capacity after 100 cycles at a rate of 2.8 to 4.35 V / 1C was the corresponding cycle capacity retention rate. Figure 9 ( Figure 9 The cycle capacity retention rate of the positive electrode material prepared in Example 3 of the present invention and Comparative Example 2 is shown in FIG. LiNi with an ultra-high (003) / (104) peak intensity ratio 0.695 Co 0.05 Mn 0.25 (SbYB) 0.0035 Sr 0.0015 The capacity retention rate of the O2 positive electrode material assembled into a half-cell after 100 cycles is still as high as 98.3%, while the capacity retention rate of the positive electrode material prepared in Comparative Example 2 corresponding to 100 cycles of the half-cell is only 85%.

[0091] Comparative Example 3

[0092] The positive electrode material of this comparative example has the chemical formula LiNi 0.7931 Co 0.1 Mn 0.1 (GaTi) 0.0025 (ZrMoP) 0.0044 O2.

[0093] The preparation method of the positive electrode material of this comparative example has the following specific steps:

[0094] (1) Ni prepared by controlled crystallization 0.8 Co 0.1 Mn 0.1 The (OH)2 precursor is mixed with fine powder LiOH (according to the lithium ratio of 1.04), additives Ga2O3, and TiO2, and the addition amount of Ga and Ti is 1500ppm and 1000ppm (based on the precursor Ni 0.8 Co 0.1 Mn 0.1 After being loaded into a bowl, it enters a roller kiln and is sintered for the first time in an oxygen atmosphere at 870°C to obtain a first-fired material;

[0095] (2) The calcined material obtained in step (1) is coarsely crushed and finely crushed, and then uniformly mixed with ZrO2, MoO3, and Li3PO4. The amount of Sb, Y, and B added is 2000ppm, 1000ppm, and 500ppm, respectively, based on the weight of the crushed material. Secondary sintering is performed at 370°C in an oxygen atmosphere to obtain a positive electrode material.

[0096] The prepared cathode material was subjected to X-ray diffraction analysis (e.g. Figure 7 ), and its (003) / (104) peak intensity ratio is 1.49. Further refinement using Fullprof yields a Li / Ni mixed arrangement of 5.7% in the material, which is close to the value reported in the literature. The cathode material of Comparative Example 3 was prepared into a finished product for half-cell testing, and the discharge rate was 0.1C at 2.8-4.35V, and the gram capacity of the half-cell was 197mAh / g. The cathode materials prepared in Example 4 and Comparative Example 3 were respectively assembled into half-cells, and the corresponding capacities at different rates of 2.8-4.35V are shown in Table 1. As can be seen from Table 1, LiNi with an ultra-high (003) / (104) peak intensity ratio 0.7931 Co 0.1 Mn 0.1 (ZrMoP) 0.0044 (GaTi) 0.0025 O2 has significantly better rate performance.

[0097] Analysis of Examples 1-4 and Comparative Examples 1-3:

[0098] The sodium ion positive electrode material, carbon black conductive agent, and PVDF in Examples 1-4 and Comparative Examples 1-3 were mixed into a slurry at a mass ratio of 80:15:5, and then coated on copper foil to prepare a pole piece. The pole piece was placed in an oven and dried at 80°C. The sodium flakes were used as the counter electrode. The electrolyte was 1.5M sodium hexafluorophosphate in propylene carbonate, Celgard 2400 was used as the diaphragm, and the battery was assembled in a vacuum glove box under an argon atmosphere. The cycling performance was tested using an electrochemical workstation with a current density of 250 mAh g -1 , the charge and discharge range is 2.5~3.5V, and the test temperature is 25℃.

[0099] Table 1 Battery test data obtained from positive electrode materials prepared in Examples and Comparative Examples

[0100]

[0101]

[0102] As shown in Table 1, the peak intensity ratios of the positive electrode materials prepared in Examples 1-4 of the present invention are significantly greater than those of the positive electrode materials prepared in Comparative Examples 1-3, with the peak intensity ratios of the positive electrode materials prepared in the present invention exceeding 1.8. Furthermore, the positive electrode materials prepared in the present invention were fabricated into batteries and subjected to half-cell testing. Discharge at a rate of 0.1C at 2.8-4.35V resulted in a gram capacity of 208 mAh / g. The positive electrode material prepared in Example 3, assembled into a half-cell, maintained a high capacity retention of 98.3% after 100 cycles, while the positive electrode material prepared in Comparative Example 2 maintained a capacity retention of only 86% after 100 cycles.

[0103] While the embodiments of the present invention have been described in detail above with reference to the accompanying drawings, the present invention is not limited to the embodiments described above. Various modifications may be made within the scope of knowledge possessed by a person skilled in the art without departing from the spirit of the present invention. Furthermore, the embodiments of the present invention and the features thereof may be combined with one another unless there is a conflict.

Claims

1. A positive electrode material, characterized in that The chemical formula of the positive electrode material is LiNi 1-x-y Co x Mn y M a N b O2, wherein 0≤x≤0.3, 0≤y≤0.5, a>0, b>0, and 0.002≤a+b≤0.04; the M is at least three of Zr, Sb, Y, Mo, P, S or B; the N is at least one of Ti, Si, Ga, Sr, Co; the LiNi 1-x-y Co x Mn y M a N b The intensity ratio of the (003) diffraction peak to the (104) diffraction peak of O2 is greater than 1.8; The preparation method of the positive electrode material comprises the following steps: Mixing a nickel-cobalt-manganese hydroxide precursor, a lithium source, and an M-containing additive, and performing a first sintering to obtain a first-fired material; The first-fired material is crushed, and then a nitrogen-containing additive is added and mixed, and then sintered for a second time to obtain the positive electrode material.

2. The positive electrode material according to claim 1, characterized in that The LiNi 1-x-y Co x Mn y M a N b The intensity ratio of the (003) diffraction peak to the (104) diffraction peak of O2 is greater than 2 and less than 10.

3. A method for preparing a positive electrode material, characterized in that: The preparation method is used to prepare the positive electrode material according to any one of claims 1 to 2.

4. The method for preparing the positive electrode material according to claim 3, wherein: The following steps are involved: Mixing a nickel-cobalt-manganese hydroxide precursor, a lithium source, and an M-containing additive, and performing a first sintering to obtain a first-fired material; The first-fired material is crushed, and then a N-containing additive is added and mixed, and then sintered for a second time to obtain the positive electrode material; the M-containing additive is at least three of the oxides or hydroxides of Zr, Sb, Y, Mo, P, S or B; and the N-containing additive is at least one of the oxides or hydroxides of Ti, Si, Ga, Sr, and Co.

5. The method for preparing the positive electrode material according to claim 4, wherein: The lithium source is at least one of LiOH and Li2CO3.

6. The method for preparing the positive electrode material according to claim 4, wherein: The nickel-cobalt-manganese hydroxide precursor is prepared by a controlled crystallization method; the specific steps of the controlled crystallization method are: mixing a nickel salt solution, a cobalt salt solution, and a manganese salt solution, then adding a precipitant and a complexing agent, reacting, adjusting the pH to 9.5-11, solid-liquid separation, washing the solid phase, and drying to obtain nickel-cobalt-manganese hydroxide.

7. A battery, characterized in that: The positive electrode material comprises the positive electrode material according to any one of claims 1 to 2.

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