High-nickel cobalt-free positive electrode material, precursor and preparation method thereof, and lithium ion battery

Abstract

The invention belongs to the technical field of lithium ion battery materials, and discloses a high-nickel cobalt-free positive electrode material, a precursor thereof, a preparation method and a lithium ion battery. The chemical formula of the precursor is Ni < 1-x > Mn < x > (OH) < 2 >, and the precursor is a secondary particle formed by stacking nano-sheet primary particles. A mixed solution of Ni salt and Mn salt, a precipitant solution and a complexing agent solution are introduced into the reaction kettle base solution, the pH value is controlled to fluctuate within a certain range of + / -0.1 in the reaction process, and the pH value of the reaction system is within a range of 9.0-12.0; when the D50 of the reaction slurry reaches a target value, stopping the reaction to obtain a precursor; and mixing lithium and sintering to obtain the high-nickel cobalt-free positive electrode material. The preparation method disclosed by the invention is low in cost, and by adjusting the manganese content and lithiation sintering temperature of the spherical hydroxide precursor, the high-nickel material is promoted to inherit the nanosheet morphology of primary crystal grains of the precursor, the structural stability is enhanced, and the cycle stability is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of lithium-ion battery materials, and relates to a precursor of a high-nickel cobalt-free positive electrode material and a preparation method thereof, a high-nickel cobalt-free positive electrode material and a preparation method and application thereof. Background Art

[0002] The energy density of lithium-ion batteries is primarily limited by the cathode material. To meet the long-range demands of electric vehicles, the development of high-energy-density cathode materials is urgent. Layered high-nickel cathode materials offer higher capacity and lower cost than traditional LiCoO2. They also boast significantly higher energy density than cheaper LiFePO4 and superior overall electrochemical performance. Therefore, layered high-nickel materials are considered the optimal cathode material for long-range lithium-ion batteries.

[0003] There is a major defect in layered high-nickel positive electrode materials: the ionic radius of nickel ions is close to that of lithium ions. During the charge and discharge process, nickel ions easily occupy the position of lithium ions, resulting in cation dislocation. The grain volume changes greatly, causing the local interlayer structure of the material to collapse, resulting in a decrease in the capacity of the material, thereby accelerating the decline in cycle capacity.

[0004] Studies have found that nanosheet grains are conducive to dispersing stress and can effectively inhibit particle cracking. Currently, the common method of obtaining nanosheets is through doping high-valent metal elements, such as W, Ta, Mo, Nb, etc. To achieve the doping of these metal elements, the hydroxide precursor and the metal oxide (W2O3, TaO2, Mo2O5, Nb2O5, etc.) must be ball-milled uniformly and then sintered. This process has the following problems: (1) The high-valent metals used are expensive in themselves, and after doping with W and Nb, the sintering temperature is increased. The normal lithiation sintering temperature is no higher than 700℃, while the sintering temperature after doping is above 800℃, and the energy consumption cost is also increased. This doping method will greatly increase the preparation cost; (2) The metal doping amount must be precisely controlled at 1wt.%. In large-scale preparation, it is difficult to ensure the uniformity of doping and the consistency of the product due to the limitations of the ball milling process. Summary of the Invention

[0005] In view of the above problems existing in the prior art, one of the objectives of the present invention is to provide a precursor of a high-nickel cobalt-free positive electrode material with a nano-sheet structure.

[0006] A second object of the present invention is to provide a method for preparing a precursor of a high-nickel cobalt-free positive electrode material.

[0007] The third object of the present invention is to provide a high-nickel cobalt-free positive electrode material with a nano-sheet structure.

[0008] A fourth object of the present invention is to provide a method for preparing a high-nickel and cobalt-free cathode material with low cost and improved product consistency.

[0009] A fifth object of the present invention is to provide a lithium-ion battery.

[0010] To achieve the above object, the present invention provides the following specific technical solutions.

[0011] A precursor of a high-nickel and cobalt-free cathode material, the chemical formula of the precursor is Ni 1-x Mn x (OH)2, where 0 < x < 0.05; the precursor is a secondary particle formed by stacking nano-sheet primary particles.

[0012] A method for preparing a precursor of a high-nickel and cobalt-free cathode material, comprising the following steps: (1) Under a protective atmosphere, a mixed solution of Ni salt and Mn salt, a precipitant solution, and a complexing agent solution are introduced into the bottom liquid of the reaction kettle for coprecipitation reaction; the pH value of the reaction system is within the range of 9.0 to 12.0, and the pH value is controlled within the range of a certain value ±0.1 during the reaction process; (2) When the D50 of the reaction slurry reaches the target value, stop the reaction, filter the reaction slurry, wash, and dry the solid phase to obtain the precursor.

[0013] In the present invention, during the coprecipitation reaction process, by controlling the pH value and the feeding rate, the growth rate of the precursor is regulated, and a secondary spherical hydroxide precursor composed of uniform nano-sheets can be generated.

[0014] Further, in step (1), in the mixed solution of Ni salt and Mn salt, the molar ratio of Ni:Mn = 1 - x:x, 0 < x < 0.05.

[0015] Further, in step (1), the total metal ion concentration in the mixed solution of Ni salt and Mn salt is 1 to 2 mol / L.

[0016] Further, in step (1), the concentration of the precipitant solution is 1 to 8 mol / L.

[0017] The precipitant is further preferably a NaOH solution.

[0018] Further, in step (1), the concentration of the complexing agent solution is 0.1 to 2 mol / L.

[0019] The complexing agent is further preferably an NH3·H2O solution.

[0020] Further, in step (1), the bottom liquid of the reaction kettle is 0.05 to 0.5 mol / L ammonia water.

[0021] Further, during the reaction process of step (1), the feeding rate of the mixed solution of Ni salt and Mn salt is 50 - 500 mL / h.

[0022] Further, in step (1), according to the concentration of (Ni 2+ +Mn 2+ ) in the reaction system: the concentration of OH - = 1:2, the feeding rate of the precipitating agent solution is determined.

[0023] Further, in step (1), the feeding rate of the complexing agent solution is equal to the feeding rate of the mixed solution of Ni salt and Mn salt.

[0024] Further, in step (1), the temperature of the reaction system is 50 - 60 °C.

[0025] Further, in step (1), the stirring speed is 300 - 800 rpm.

[0026] Further, in step (2): when D50 of the reaction slurry > 6 μm, the reaction is stopped.

[0027] Further, in step (2), the drying method is vacuum drying or drying by heating in air (<120 °C).

[0028] A high-nickel cobalt-free cathode material, the chemical formula of the cathode material is LiNi 1-x Mn x O2, where 0 < x < 0.05; the cathode material has a nano-sheet structure, and the thickness of the nano-sheet is less than 100 nm.

[0029] A preparation method of a high-nickel cobalt-free cathode material, using the above-mentioned precursor or the precursor prepared by the above-mentioned preparation method, further includes the following steps: Mix the precursor and the lithium source evenly and then carry out two-stage sintering in an oxygen atmosphere to obtain a high-nickel cobalt-free cathode material; wherein: the first-stage sintering temperature is 450 - 500 °C, and the second-stage sintering temperature is 630 - 700 °C.

[0030] After obtaining the precursor in the present invention, two-stage lithium sintering within a limited temperature range can ensure the acquisition of a high-nickel material composed of nano-sheets.

[0031] Further, the lithium source is LiOH.

[0032] Further, the sintering duration of the first-stage sintering is 2 - 10 h, and the sintering duration of the second-stage sintering is 10 - 30 h.

[0033] Furthermore, the amount of lithium source is added in a molar ratio of Li:(Ni+Mn)=1.0~1.05:1.0.

[0034] Furthermore, during the second-stage sintering process, the oxygen flow rate is 50-200 sccm; and the heating and cooling rate is 1-3°C / min.

[0035] The present invention also discloses a lithium-ion battery, which comprises the high-nickel cobalt-free positive electrode material described above.

[0036] Compared with the prior art, the present invention has the following beneficial effects: (1) The high-nickel, cobalt-free cathode material and its precursor of the present invention have a nanosheet structure. The nanosheet structure is conducive to increasing the diffusion rate of lithium ions and dissipating internal stress, thereby improving structural stability. The high-nickel, cobalt-free cathode material can withstand large volume changes during charging and discharging, maintain the integrity of spherical or quasi-spherical particles, and ensure cycle stability. At the same time, the present invention creatively discovered that the addition of a small amount of Mn element is conducive to obtaining nanosheet primary grains, which is conducive to improving cycle stability. When the doping amount of Mn element is 0<5%, it has excellent cycle performance while ensuring capacity utilization.

[0037] (2) The preparation method of the high-nickel, cobalt-free cathode material of the present invention contains only inexpensive transition metal elements, Ni and Mn, and is low-cost. Uniform Mn doping is achieved through co-precipitation, without the need for an additional ball milling step. The sintering temperature of the present method is below 700°C, resulting in low energy consumption. The co-precipitation technology of the present method has high reproducibility and high stability in batch production, ensuring the consistency of the precursor elements and structure.

[0038] (3) The method for preparing the precursor of the high-nickel cobalt-free positive electrode material of the present invention controls the fluctuation range of the pH value within ±0.1 during the coprecipitation reaction to avoid the influence of the pH fluctuation on the nucleation and growth of the hydroxide precursor, thereby ensuring the growth of the spherical particles of the precursor. By controlling the feed rate and regulating the growth rate of the precursor, a secondary spherical hydroxide precursor composed of uniform nanosheets can be generated.

[0039] (4) The preparation method of the high-nickel cobalt-free cathode material of the present invention adjusts the manganese content of the spherical hydroxide precursor and the lithiation sintering temperature, so that the high-nickel material inherits the nanosheet morphology of the primary grains of the precursor, thereby obtaining a layered high-nickel cobalt-free cathode material. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings: Figure 1 The precursor Ni obtained in step (4) of Example 10.99 Mn 0.01 Morphology of (OH)2; Figure 2 The high nickel cathode material LiNi obtained in step (5) of Example 1 0.99 Mn 0.01 Topography of O2; Figure 3 The high nickel cathode material LiNi prepared in Example 1 0.99 Mn 0.01 O2 cycle performance curve; Figure 4 The high nickel cathode material LiNi obtained in step (5) of Example 2 0.98 Mn 0.02 Topography of O2; Figure 5 The high nickel cathode material LiNi prepared in Example 2 0.98 Mn 0.02 O2 cycle performance curve; Figure 6 The high nickel cathode material LiNi obtained in step (5) of Example 3 0.96 Mn 0.04 Topography of O2; Figure 7 The high nickel cathode material LiNi prepared in Example 3 0.96 Mn 0.04 O2 cycle performance curve; Figure 8 This is the morphology of the precursor Ni(OH)2 obtained in step (4) of comparative example 1; Figure 9 This is a morphology of the high-nickel cathode material LiNiO2 obtained in step (5) of Comparative Example 1; Figure 10 This is a cycle performance curve of the high-nickel positive electrode material LiNiO2 prepared in Comparative Example 1. DETAILED DESCRIPTION

[0041] To facilitate understanding of the present invention, the present invention will be described in more comprehensive and detailed form below in conjunction with the accompanying drawings and preferred embodiments. However, the protection scope of the present invention is not limited to the following specific embodiments.

[0042] Unless otherwise defined, all technical terms used hereinafter have the same meanings as those generally understood by those skilled in the art. The technical terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present invention.

[0043] Example 1 This embodiment provides a method for preparing a spinel lithium nickel manganese oxide positive electrode material, comprising the following steps: (1) Prepare 1 L of a 2 mol / L mixed solution A of NiSO4·6H2O and MnSO4·4H2O with a molar ratio of Ni:Mn = 99:1, 1 L of a 4 mol / L NaOH solution B, and 1 L of a 2 mol / L ammonia solution C. Mix solutions B and C to form solution D.

[0044] (2) Add 5 L of 0.5 mol / L dilute ammonia solution to a 50 L reactor, raise the temperature to 55 °C and maintain the temperature, introduce nitrogen gas below the liquid surface to remove the air in the reactor, and maintain the nitrogen flow rate at 500 sccm.

[0045] (3) Start stirring the reactor, maintain the reactor speed at 700 rpm, control the feed rate of solution A at 250 mL / h, and the initial feed rate of solution D at 500 mL / h; fine-tune the feed rate of solution D, and control the pH value to fluctuate within the range of 11±0.1 during the reaction.

[0046] (4) After 4 hours of reaction, when the D50 of the spherical particles in the kettle is greater than 10 μm and evenly distributed, the solution in the kettle is discharged, filtered, and washed with deionized water until the pH of the filtrate is less than 8. Then, the filtrate is dried at 80 ° C in vacuum for 12 hours to obtain Ni 0.99 Mn 0.01 (OH)2 precursor.

[0047] (5) Manually grind the precursor and LiOH to obtain a molar ratio of Li: (Ni + Mn) of 1.05:1.0; sinter the mixed material in two steps under an oxygen atmosphere: The first step is low-temperature sintering at 500°C for 5h; The second step is high temperature sintering at 650℃ for 20h; During the sintering process, the oxygen flow rate was 100 sccm, and the heating and cooling rate was controlled at 2°C / min. After the temperature dropped to 300°C, the temperature control was no longer required and the sample was allowed to cool naturally in the furnace. The sample was taken out and stored in a vacuum for later use.

[0048] In this embodiment, the precursor Ni prepared in step (4) 0.99 Mn 0.01 The morphology of (OH)2 is as follows Figure 1 As shown, the spherical particles are composed of plate-like nanosheet grains; Step (5) Prepared high nickel cathode material LiNi 0.99 Mn 0.01 O2 as Figure 2 As shown, the spherical particles are also composed of nanosheet grains, and the thickness of the nanosheets is estimated to be less than 100 nm.

[0049] According to the mass ratio of active material: carbon black: PVDF = 8:1:1, 1.2 g of the prepared sample, 0.15 g of carbon black, and 3.75 g of a 4 wt.% PVDF solution in NMP were manually ground evenly, passed through a 200# sieve, and coated on aluminum foil. The pieces were dried, weighed, and assembled into button half-cells. The cycle performance obtained was as follows: Figure 3 As shown, the capacity retention rate after 100 cycles of 1C charge and discharge is 91%.

[0050] Example 2 This embodiment is basically the same as embodiment 1, except that: Step (1) is: Prepare 1 L of a 2 mol / L mixed solution A of NiSO4·6H2O and MnSO4·4H2O with a molar ratio of Ni:Mn = 98:2, 1 L of a 4 mol / L NaOH solution B, and 1 L of a 2 mol / L ammonia solution C. Mix solutions B and C to form solution D.

[0051] (5) Manually grind the precursor and LiOH to obtain a molar ratio of Li: (Ni + Mn) of 1.05:1.0; sinter the mixed material in two steps under an oxygen atmosphere: The first step is low-temperature sintering at 500°C for 5h; The second step is high temperature sintering at 660℃ for 20h; During the sintering process, the oxygen flow rate was 100 sccm, the heating and cooling rate was controlled at 2°C / min, and after cooling to 300°C, the sample was naturally cooled in the furnace, and then taken out and stored in vacuum for later use.

[0052] Same as in Example 1, the precursor Ni prepared in step (4) 0.98 Mn 0.02 The spherical particles of (OH)2 are composed of flaky nanosheets. Step (5) Prepared high nickel cathode material LiNi 0.98 Mn 0.02 O2 as Figure 4 As shown, the spherical particles also inherit the nanosheet morphology of the precursor, and the thickness of the nanosheet is estimated to be less than 100 nm.

[0053] According to the mass ratio of active material: carbon black: PVDF = 8:1:1, 1.2 g of the prepared sample, 0.15 g of carbon black, and 3.75 g of 4 wt.% PVDF solution in NMP were manually ground evenly, passed through a 200# sieve, and coated on aluminum foil. The pieces were dried, weighed, and assembled into button half-cells. The cycle performance obtained was as follows: Figure 5 As shown, the capacity retention rate after 100 cycles at 1C is 90%.

[0054] Example 3 This embodiment is basically the same as embodiment 1, except that: Step (1) is: Prepare 1 L of a 2 mol / L mixed solution A of NiSO4·6H2O and MnSO4·4H2O with a molar ratio of Ni:Mn=96:4, 1 L of a 4 mol / L NaOH solution B, and 1 L of a 2 mol / L ammonia solution C. Mix solutions B and C to form solution D.

[0055] (5) Manually grind the precursor and LiOH to obtain a molar ratio of Li: (Ni + Mn) of 1.05:1.0; sinter the mixed material in two steps under an oxygen atmosphere: The first step is low-temperature sintering at 500°C for 5h; The second step is high temperature sintering at 680℃ for 20h; During the sintering process, the oxygen flow rate was 100 sccm, the heating and cooling rate was controlled at 2°C / min, and after cooling to 300°C, the sample was naturally cooled in the furnace, and then taken out and stored in vacuum for later use.

[0056] Same as in Example 1, the precursor Ni prepared in step (4) 0.96 Mn 0.04 The spherical particles of (OH)2 are composed of flaky nanosheets. Step (5) Prepared high nickel cathode material LiNi 0.96 Mn 0.04 O2 as Figure 6 As shown, the spherical particles also inherit the primary nanosheets of the precursor, and the thickness of the nanosheets is estimated to be less than 100 nm.

[0057] According to the mass ratio of active material: carbon black: PVDF = 8:1:1, 1.2 g of the prepared sample, 0.15 g of carbon black, and 3.75 g of 4 wt.% PVDF solution in NMP were manually ground evenly, passed through a 200# sieve, and coated on aluminum foil. The pieces were dried, weighed, and assembled into button half-cells. The cycle performance obtained was as follows: Figure 7 As shown, the capacity retention rate after 100 cycles at 1C is 93%.

[0058] Comparative Example 1 This comparative example is basically the same as Example 1, except that: Step (1) is: Prepare 1 L of 2 mol / L NiSO4·6H2O solution A, 1 L of 4 mol / L NaOH solution B, and 1 L of 2 mol / L ammonia solution C. Mix solutions B and C to form solution D.

[0059] Correspondingly, the precursor prepared through step (2) and step (3) is Ni(OH)2 not doped with Mn.

[0060] In this comparative example, the morphology of the precursor Ni(OH)2 prepared in step (4) is as follows Figure 8 As shown, the spherical particles are composed of plate-like nanosheet grains.

[0061] Step (5) prepares the high nickel cathode material LiNiO2 Figure 9 As shown, the spherical particles are composed of block-like grains and do not have nanosheet morphology.

[0062] According to the mass ratio of active material: carbon black: PVDF = 8:1:1, 1.2 g of the prepared sample, 0.15 g of carbon black, and 3.75 g of 4 wt.% PVDF solution in NMP were manually ground evenly, passed through a 200# sieve, and coated on aluminum foil. The pieces were dried, weighed, and assembled into button half-cells. The cycle performance obtained was as follows: Figure 5 The capacity retention rate after 100 cycles at 1C is 86%, which is lower than that of Examples 1, 2 and 3. It can be seen that the addition of a small amount of Mn element is beneficial to obtaining primary grains of nanosheets and improving the cycle stability.

[0063] In addition, by Figure 3 、 5 From the comparison of Examples 1, 2, and 3, it can be seen that the doping amounts of the Mn element increase successively, while the discharge capacity of the corresponding batteries decreases slightly. This may be because the increase in the doping amount of the Mn element will hinder the H2-H3 phase transition and affect the capacity. Therefore, in the present invention, it is preferred to limit the doping amount of the Mn element to <5%, so as to ensure the capacity while having excellent cycle performance.

[0064] Comparative Example 2 This comparative example is basically the same as Example 1, except that: Step (1) is: (1) Prepare 1 L of a 2 mol / L mixed solution of NiSO4·6H2O and MnSO4·4H2O with a molar ratio of Ni:Mn = 95:5, 1 L of a 4 mol / L NaOH solution B, and 1 L of a 2 mol / L ammonia solution C. Mix solutions B and C to form solution D.

[0065] In this comparative example, the precursor Ni prepared in step (4) 0.95 Mn 0.05 (OH)2 and the high nickel positive electrode material LiNi prepared in step (5) 0.95 Mn 0.05 O2 has a nanosheet morphology, and the thickness of the nanosheet is estimated to be less than 100 nm.

[0066] According to the mass ratio of active material: carbon black: PVDF = 8:1:1, 1.2 g of the prepared sample, 0.15 g of carbon black, and 3.75 g of a 4 wt.% PVDF solution in NMP were manually ground evenly, passed through a 200# sieve, and coated on aluminum foil. The pieces were dried, weighed, and assembled into button half-cells.

[0067] Comparative Example 3 This comparative example is basically the same as Example 1, except that: Step (1) is: (1) Prepare 1 L of a 2 mol / L mixed solution of NiSO4·6H2O and MnSO4·4H2O with a molar ratio of Ni:Mn=94:6, 1 L of a 4 mol / L NaOH solution B, and 1 L of a 2 mol / L ammonia solution C. Mix solutions B and C to form solution D.

[0068] In this comparative example, the precursor Ni prepared in step (4) 0.94 Mn 0.06 (OH)2 and the high nickel cathode material LiNi prepared in step (5) 0.94 Mn 0.06 O2 has a nanosheet morphology, and the thickness of the nanosheet is estimated to be less than 100 nm.

[0069] According to the mass ratio of active material: carbon black: PVDF = 8:1:1, 1.2 g of the prepared sample, 0.15 g of carbon black, and 3.75 g of a 4 wt.% PVDF solution in NMP were manually ground evenly, passed through a 200# sieve, and coated on aluminum foil. The pieces were dried, weighed, and assembled into button half-cells.

[0070] After performance testing of the button-type batteries prepared in Comparative Examples 2 and 3, the results showed that when the doping amount of the Mn element was further increased, the prepared precursor and high-nickel positive electrode material still had a nanosheet morphology and the capacity retention rate after 100 cycles at 1C was still relatively high, about 90%, but its capacity performance further decreased. When the Mn doping amount was greater than 5%, the initial discharge capacity basically dropped to below 150 mAh / g, seriously affecting the battery performance.

[0071] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Those skilled in the art will readily appreciate that the present invention is susceptible to various modifications and variations. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of the present invention.

Claims

1. A precursor of a high-nickel and cobalt-free cathode material, characterized in that, The chemical formula of the precursor is Ni 1-x Mn x (OH) 2 , where 0 < x < 0.05; the precursor is a secondary particle formed by the accumulation of nano-sheet primary particles.

2. A method for preparing the precursor of the high-nickel and cobalt-free cathode material according to claim 1, characterized in that, comprises the following steps: (1) Under a protective atmosphere, a mixed solution of Ni salt and Mn salt, a precipitant solution, and a complexing agent solution are introduced into the bottom liquid of the reaction kettle for coprecipitation reaction; the pH value of the reaction system is in the range of 9.0 to 12.0, and the pH value is controlled to fluctuate within the range of a certain value ±0.1 during the reaction process; (2) When the D50 of the reaction slurry reaches the target value, the reaction is stopped, the reaction slurry is filtered, washed, and the solid phase is dried to obtain the precursor.

3. The preparation method according to claim 2, characterized in that, in step (1): in the mixed solution of Ni salt and Mn salt, the molar ratio of Ni:Mn = 1 - x: x, 0 < x < 0.05; Preferably, in the mixed solution of Ni salt and Mn salt, the total concentration of metal ions is 1 to 2 mol / L; Preferably, the concentration of the precipitant solution is 1 to 8 mol / L; Preferably, the concentration of the complexing agent solution is 0.1 to 2 mol / L; Preferably, the bottom liquid of the reaction kettle is 0.05 to 0.5 mol / L ammonia water.

4. The preparation method according to claim 2, characterized in that, in step (1): the feeding rate of the mixed solution of Ni salt and Mn salt is 50 to 500 mL / h; Preferably, according to the concentration in the reaction system (Ni 2+ +Mn 2+ ): the concentration of OH - = 1: 2 to determine the feeding rate of the precipitant solution; Preferably, the feeding rate of the complexing agent solution is equal to the feeding rate of the mixed solution of Ni salt and Mn salt.

5. The preparation method according to claim 2, characterized in that, in step (1): the temperature of the reaction system is 50 to 60 °C; Preferably, the stirring speed is 300 to 800 rpm.

6. The preparation method according to claim 2, characterized in that, in step (2): When the D50 of the reaction slurry > 6 μm, the reaction is stopped.

7. A high-nickel and cobalt-free cathode material, characterized in that, The chemical formula of the positive electrode material is LiNi 1-x Mn x O 2 , where 0 < x < 0.05; the positive electrode material has a nano-sheet structure, and the thickness of the nano-sheet is less than 100 nm.

8. A method for preparing a high-nickel and cobalt-free cathode material, characterized in that, using the precursor according to claim 1 or the precursor prepared by the preparation method according to any one of claims 2 to 6, further comprises the following steps: The precursor is mixed uniformly with a lithium source and then subjected to two-stage sintering in an oxygen atmosphere to obtain a high-nickel and cobalt-free cathode material; wherein: the first-stage sintering temperature is 450 to 550 °C, and the second-stage sintering temperature is 630 to 700 °C.

9. The preparation method according to claim 8, characterized in that: the amount of the lithium source is added in a molar ratio of Li: (Ni + Mn) = 1.0 to 1.05: 1.0; Preferably, the sintering duration of the first-stage sintering is 2 to 10 h; the sintering duration of the second-stage sintering is 10 to 30 h; Preferably, during the first-stage sintering and the second-stage sintering, the oxygen flow rate is 50 to 200 sccm; the heating and cooling rate is 1 to 3 °C / min.

10. A lithium-ion battery, characterized in that, The high-nickel and cobalt-free cathode material described in claim 7 or the high-nickel and cobalt-free cathode material prepared by the preparation method described in claim 8 or 9.

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