A lithium-rich manganese-based precursor and its preparation method and application

Abstract

The present invention provides a lithium-rich manganese-based precursor and a preparation method and application thereof. The lithium-rich manganese-based precursor comprises a first precursor and a second precursor, wherein one of the first precursor and the second precursor has a particle size of 1 to 3 μm and a specific surface area of ​​3 to 6 m 2 / g; the particle size of the first precursor and the other of the second precursor is 7 to 10 μm, and the specific surface area is 0.8 to 2 m 2 / g. In the lithium-rich manganese-based precursor provided by the present invention, the particle size of the first precursor is different from that of the second precursor, and the specific surface area of ​​the first precursor is different from that of the second precursor, so that after the first precursor and the second precursor with different particle sizes are mixed with each other, the precursor particles with a smaller particle size can be filled into the gaps between the precursor particles with a larger particle size, and the particles are more densely stacked. After sintering, the lithium-rich manganese-based positive electrode material obtained has better particle morphology and particle size distribution, and the particles have better structural stability.

Description

Technical Field

[0001] The present invention relates to the field of battery technology, and in particular to a lithium-rich manganese-based precursor and a preparation method and application thereof. Background Art

[0002] In recent years, the application areas of lithium-ion batteries have been continuously expanding, from traditional 3C products to current power batteries. The new energy industry has an increasingly urgent demand for lithium-ion batteries, especially high-energy-density lithium batteries. To meet this demand, a large amount of research work has been devoted to finding and developing positive electrode materials with high specific capacity. Lithium-rich manganese-based positive electrode materials have attracted in-depth research from many experts and scholars in the industry due to their high specific capacity, good thermal stability, good cycle performance, wide charge and discharge voltage range, low price, and environmental friendliness. They have great development potential.

[0003] Lithium-rich manganese-based precursors have a great influence on the properties of lithium-rich manganese-based positive electrode materials. At present, lithium-rich manganese-based precursors are mostly produced industrially by co-precipitation. The co-precipitation method can be divided into hydroxide system and carbonate system according to the different precipitants. However, the manganese element in the precipitate obtained by the hydroxide system is easily oxidized by air, resulting in phase separation of the precursor, and local stress is easily generated when high voltage is activated, thereby deteriorating the performance; while when the carbonate system precipitate is mixed with lithium salt and sintered, carbon dioxide will be generated from the inside of the precursor, resulting in a high porosity of the material, which greatly reduces the tap density, compaction density and strength of the material itself, and thus cannot meet the high energy density pursued by power batteries, restricting its practical application and development.

[0004] Therefore, there is an urgent need in the art to develop a new lithium-rich manganese-based precursor and a preparation method thereof, so that the lithium-rich manganese-based positive electrode material using the lithium-rich manganese-based precursor has excellent performance, thereby meeting the high energy density requirements of lithium-ion batteries. Summary of the invention

[0005] The embodiments of the present invention provide a lithium-rich manganese-based precursor and a preparation method and application thereof, which can improve the poor electrochemical performance, low tap density, compaction density and strength of the lithium-rich manganese-based positive electrode material using the lithium-rich manganese-based precursor in the related technology, and meet the high energy density requirements of lithium-ion batteries.

[0006] In a first aspect, an embodiment of the present invention provides a lithium-rich manganese-based precursor, wherein the lithium-rich manganese-based precursor comprises a first precursor and a second precursor, wherein one of the first precursor and the second precursor has a particle size of 1 to 3 μm and a specific surface area of ​​3 to 6 m 2 / g; the particle size of the other of the first precursor and the second precursor is 7 to 10 um, and the specific surface area is 0.8 to 2 m 2 / g.

[0007] In one embodiment, the lithium-rich manganese-based precursor includes the first precursor and the second precursor mixed in a first weight ratio, wherein the first weight ratio is 20:80 to 80:20.

[0008] In one embodiment, the chemical formula of the first precursor is Mn x Co y M 1-x-y CO3, wherein 0.4<x<1, 0<y<0.2, x+y≤1; wherein the M element includes one or two of Ni, Mg, Cu, Fe, Zn, Zr, Y, Al, Sr, W, Na, Nb, Si, B, La, and Ru;

[0009] The chemical formula of the second precursor is Mn a Co b N 1-a-b (OH)2, wherein a=0.4~1, b=0~0.2, 1-ab≤1, wherein the N element includes one or two of Ni, Mg, Cu, Fe, Zn, Zr, Y, Al, Sr, W, Na, Nb, Si, B, La, and Ru elements.

[0010] In a second aspect, an embodiment of the present invention provides a method for preparing a lithium-rich manganese-based precursor, which is used to prepare the lithium-rich manganese-based precursor described in any of the above items, wherein the method for preparing the lithium-rich manganese-based precursor comprises the following steps: preparing a first precursor; preparing a second precursor; mixing the first precursor and the second precursor in a first weight ratio to obtain the lithium-rich manganese-based precursor; wherein the first weight ratio is 20:80 to 80:20; one of the first precursor and the second precursor has a particle size of 1 to 3 um and a specific surface area of ​​3 to 6 m 2 / g; the particle size of the other of the first precursor and the second precursor is 7 to 10 um, and the specific surface area is 0.8 to 2 m 2 / g.

[0011] In one embodiment, the step of preparing the first precursor includes: preparing an organic buffer solution, wherein the pH value of the organic buffer solution is 7.0-8.3; dissolving nickel salt, manganese salt, and cobalt salt in a solvent to obtain a first metal salt solution; under the protection of an inert gas, injecting the first metal salt solution and a carbonate solution into a reactor containing the organic buffer solution, stirring the reaction, and obtaining a first product after aging; post-treating the first product to obtain the first precursor;

[0012] In one embodiment, the steps of preparing the second precursor include: preparing an ammonia-alkali solution, wherein the ammonia-alkali solution is formed by mixing sodium hydroxide and ammonia water; dissolving nickel salt, manganese salt, and cobalt salt in deionized water, adding a reducing agent and stirring to obtain a second metal salt solution; filtering the ammonia-alkali solution and the second metal salt solution to remove impurities, transferring them to a reactor, and introducing a protective gas, stirring and heating at the same time, and obtaining a second product under alkaline conditions; extracting the second product, filtering and drying it to obtain the second precursor.

[0013] In a third aspect, an embodiment of the present invention provides a lithium-rich manganese-based positive electrode material, and a method for preparing the lithium-rich manganese-based positive electrode material comprises the following steps: mixing the lithium-rich manganese-based precursor described in any one of the above items and a lithium source to form a mixture, and sintering the mixture to obtain a lithium-rich manganese-based positive electrode material; wherein the sintering temperature is 400 to 900°C.

[0014] In a fourth aspect, an embodiment of the present invention provides a lithium-rich manganese-based positive electrode material, and the lithium-rich manganese-based positive electrode material is prepared by the preparation method of the lithium-rich manganese-based positive electrode material described above.

[0015] In one embodiment, the chemical formula of the lithium-rich manganese-based positive electrode material is Li c Mn e Co f M j N (1-e-f-j) O d , wherein c=1.1-1.4, d=2.0-2.5, e=0.4-1, f=0-0.2, j=0-0.2; 1-efj≤1, wherein the M element includes one or two of the following elements: Ni, Mg, Cu, Fe, Zn, Zr, Y, Al, Sr, W, Na, Nb, Si, B, La, and Ru; the N element includes one or two of the following elements: Ni, Mg, Cu, Fe, Zn, Zr, Y, Al, Sr, W, Na, Nb, Si, B, La, and Ru; the median particle size of the lithium-rich manganese-based positive electrode material is 4-7 um, the particle size distribution width is 0.7-1.4, and the surface area is 1-5 m 2 / g.

[0016] In a fifth aspect, an embodiment of the present invention provides a method for preparing a lithium-ion battery, the method for preparing a lithium-ion battery comprising the following steps: mixing the lithium-rich manganese-based positive electrode material described in any one of the above items with a first conductive agent and a first binder to form a first slurry, and applying the first slurry on an aluminum foil, and obtaining a positive electrode sheet after drying, cold pressing, slicing or striping; mixing a negative electrode material with a second conductive agent and a second binder to form a second slurry, and applying the second slurry on a copper foil, and obtaining a negative electrode sheet after drying, cold pressing, slicing or striping; assembling the positive electrode sheet and the negative electrode sheet into a battery cell; baking, injecting, forming and dividing the battery cell to obtain a lithium-ion battery.

[0017] In a sixth aspect, an embodiment of the present invention provides a lithium-ion battery, wherein the lithium-ion battery is prepared by the lithium-ion battery preparation method described above.

[0018] Beneficial effects of the embodiments of the present invention:

[0019] The embodiment of the present invention provides a lithium-rich manganese-based precursor and a preparation method thereof, a lithium-rich manganese-based positive electrode material and a preparation method thereof, a lithium-ion battery and a preparation method thereof, wherein the lithium-rich manganese-based precursor comprises a first precursor and a second precursor, wherein one of the first precursor and the second precursor has a particle size of 1 to 3 μm and a specific surface area of ​​3 to 6 m 2 / g; the particle size of the other of the first precursor and the second precursor is 7 to 10 um, and the specific surface area is 0.8 to 2 m 2 / g. In the lithium-rich manganese-based precursor provided by the present invention, the particle size of the first precursor is different from that of the second precursor, and the specific surface area of ​​the first precursor is different from that of the second precursor, so that after the first precursor and the second precursor with different particle sizes are mixed with each other, the precursor particles with a smaller particle size can be filled into the gaps between the precursor particles with a larger particle size, and the particles are more densely stacked. After sintering, the lithium-rich manganese-based positive electrode material obtained has better particle morphology and particle size distribution, and the particles have better structural stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0021] Figure 1 XRD spectrum of the lithium-rich manganese-based positive electrode material provided in an embodiment of the present invention;

[0022] Figure 2This is a SEM electron microscope morphology analysis diagram of the lithium-rich manganese-based positive electrode material provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0023] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention. In addition, it should be understood that the specific implementation methods described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention. In the present invention, unless otherwise specified, the directional words used, such as "upper" and "lower", generally refer to the upper and lower parts of the device in actual use or working state, specifically the drawing direction in the drawings; while "inside" and "outside" refer to the outline of the device.

[0024] In a first aspect, the present invention provides a lithium-rich manganese-based precursor, which is applied to a lithium-rich manganese-based positive electrode material.

[0025] Specifically, the lithium-rich manganese-based precursor includes a first precursor and a second precursor, the first weight ratio is 20:80-80:20, wherein the particle size of one of the first precursor and the second precursor is 1-3 μm, and the specific surface area is 3-6 m 2 / g; the particle size of the other of the first precursor and the second precursor is 7 to 10 um, and the specific surface area is 0.8 to 2 m 2 / g.

[0026] In the lithium-rich manganese-based precursor provided by the present invention, since the particle size of the first precursor is different from that of the second precursor, and the difference between the particle sizes is controlled within 4 to 9 μm, the specific surface area of ​​the first precursor is different from that of the second precursor, and the difference between the specific surface areas is controlled within 1 to 5.2, so that after the first precursor and the second precursor of different particle sizes are mixed with each other, the precursor particles with a smaller particle size can be filled into the gaps between the precursor particles with a larger particle size, making the stacking between the particles denser, and the lithium-rich manganese-based positive electrode material obtained after sintering has better particle morphology and particle size distribution, and the particles have better structural stability.

[0027] In some embodiments of the present application, the particle size of the first precursor is larger than that of the second precursor, and the specific surface area of ​​the first precursor is smaller than that of the second precursor. The particle size of the first precursor is 7 to 10 μm, and the specific surface area of ​​the first precursor is 0.8 to 2 μm. 2 / g; the particle size of the second precursor is 1 to 3 um, and the specific surface area of ​​the second precursor is 3 to 6 m 2 / g.

[0028] For example, the particle size of the first precursor may be 7um, 7.5um, 8um, 8.5um, 9um, 9.5um, 10um, etc., and the specific surface area of ​​the first precursor may be 0.8m 2 / g, 0.9m 2 / g, 1.0m 2 / g, 1.1m 2 / g, 1.2m 2 / g, 1.3m 2 / g, 1.4m 2 / g, 1.5m 2 / g, 1.6m 2 / g, 1.7m 2 / g, 1.8m 2 / g, 1.9m 2 / g, 2.0m 2 / g; the particle size of the second precursor can be 1um, 1.5um, 2um, 2.5um, 3um, etc., and the specific surface area of ​​the second precursor can be 3um, 3.5um, 4um, 4.5um, 5um, 5.5um, 6um, etc.

[0029] In some embodiments of the present application, the particle size of the second precursor is larger than that of the first precursor, and the specific surface area of ​​the second precursor is smaller than that of the first precursor. The particle size of the second precursor is 7 to 10 μm, and the specific surface area of ​​the second precursor is 0.8 to 2 μm. 2 / g; the particle size of the first precursor is 1 to 3 um, and the specific surface area of ​​the first precursor is 3 to 6 m 2 / g.

[0030] For example, the particle size of the second precursor may be 7um, 7.5um, 8um, 8.5um, 9um, 9.5um, 10um, etc., and the specific surface area of ​​the second precursor may be 0.8m 2 / g, 0.9m 2 / g, 1.0m 2 / g, 1.1m 2 / g, 1.2m 2 / g, 1.3m 2 / g, 1.4m 2 / g, 1.5m 2 / g, 1.6m 2 / g, 1.7m 2 / g, 1.8m 2 / g, 1.9m 2 / g, 2.0m 2 / g; the particle size of the first precursor can be 1um, 1.5um, 2um, 2.5um, 3um, etc., and the specific surface area of ​​the first precursor can be 3um, 3.5um, 4um, 4.5um, 5um, 5.5um, 6um, etc.

[0031] Furthermore, the lithium-rich manganese-based precursor includes a first precursor and a second precursor mixed in a first weight ratio, wherein the first weight ratio is 20:80 to 80:20.

[0032] In the lithium-rich manganese-based precursor provided by the present invention, since the weight proportion of the precursor particles with larger particle size and smaller specific surface area is more than 20%, and the weight proportion of the precursor particles with smaller particle size and larger specific surface area is more than 80%, the mixing effect between the first precursor and the second precursor of different particle sizes can be better, so that the precursor particles with smaller particle size can be better filled into the gaps between the precursor particles with larger particle size, and the stacking between the particles is denser. The lithium-rich manganese-based positive electrode material obtained after sintering has better particle morphology and particle size distribution, and the particles have better structural stability.

[0033] In some embodiments of the present application, the chemical formula of the first precursor is Mn x Co y M 1-x-y CO3, wherein 0.4<x<1, 0<y<0.2, x+y≤1; the M element includes one or two of the elements Ni, Mg, Cu, Fe, Zn, Zr, Y, Al, Sr, W, Na, Nb, Si, B, La, Ru, etc.; the chemical formula of the second precursor is Mn a Co b N 1-a-b (OH)2, wherein a=0.4-0.1, b=0-0.2, 1-ab≤1, and the N element includes one or two of the elements Ni, Mg, Cu, Fe, Zn, Zr, Y, Al, Sr, W, Na, Nb, Si, B, La, and Ru.

[0034] That is, the first precursor is a carbonate precursor, and the second precursor is a hydroxide precursor.

[0035] Specifically, the lithium-rich manganese-based positive electrode sheets prepared using carbonate precursors alone have problems such as low compaction density, easy crushing of particles, and severe gas production; the lithium-rich manganese-based positive electrode sheets prepared using hydroxide precursors alone have problems such as unstable crystal form, large local stress in the lattice, and obvious lattice oxygen release when used under high voltage (4.4-4.6V).

[0036] The lithium-rich manganese-based precursor provided by the present invention includes both a carbonate precursor and a hydroxide precursor, and the carbonate precursor and the hydroxide precursor in the lithium-rich manganese-based precursor have different particle sizes and different specific surface areas. Therefore, after the carbonate precursors and hydroxide precursors of different particle sizes are mixed with each other, the precursor particles with smaller particle sizes can be filled into the gaps between the precursor particles with larger particle sizes, so that the particles are stacked more densely, so that the lithium-rich manganese-based positive electrode material formed by sintering the lithium-rich manganese-based precursor has better particle morphology and particle size distribution, and the particles have better structural stability, which greatly improves the tap density, compaction density and mechanical strength of the lithium-rich manganese-based positive electrode material, and makes the internal stress distribution of the lithium-rich manganese-based positive electrode material uniform during the charge and discharge process, and the crystal structure is more stable, and the internal resistance of the material is reduced, thereby improving the rate performance, high capacity and cycle stability.

[0037]

[0038] Table 1

[0039] As can be seen from Table 1, the lithium-rich manganese-based precursor provided by the present invention controls the particle size of one of the first precursor and the second precursor to be within 1-3um, the particle size of the other of the first precursor and the second precursor to be within 7-10um, and the first precursor and the second precursor are mixed in a weight ratio of 20:80 to 80:20, so that the particles are stacked more densely, so that the lithium-rich manganese-based positive electrode material formed by sintering the lithium-rich manganese-based precursor has better particle morphology and particle size distribution, and the particles have better structural stability, thereby greatly improving the compaction density of the lithium-rich manganese-based positive electrode material.

[0040] In a second aspect, the present invention provides a method for preparing a lithium-rich manganese-based precursor, which is used to prepare the lithium-rich manganese-based precursor described in any of the above items, wherein the method for preparing the lithium-rich manganese-based precursor comprises the following steps:

[0041] preparing a first precursor;

[0042] preparing a second precursor;

[0043] The first precursor and the second precursor are mixed according to a first weight ratio to obtain a lithium-rich manganese-based precursor.

[0044] The first weight ratio is 20:80 to 80:20; the particle size of one of the first precursor and the second precursor is 1 to 3 μm, and the specific surface area is 3 to 6 m 2 / g; the particle size of the other of the first precursor and the second precursor is 7 to 10 um, and the specific surface area is 0.8 to 2 m 2 / g.

[0045] In some embodiments of the present application, the step of preparing the first precursor includes:

[0046] An organic buffer solution is prepared, wherein the organic buffer solution includes an organic buffer, and the organic buffer may be at least one of ammonium sulfate, sodium salicylate, and sodium citrate, and the pH value of the organic buffer solution is 7.0 to 8.3;

[0047] Dissolving nickel salt, manganese salt and cobalt salt in a solvent to obtain a first metal salt solution;

[0048] Under the protection of an inert gas, the first metal salt solution and the carbonate solution are respectively injected into a reaction kettle containing the organic buffer solution, stirred for reaction, and aged to obtain a first product, wherein the inert gas is, for example, nitrogen;

[0049] The first product is post-processed to obtain the first precursor, and the post-processing process includes: filtering and drying, and the drying temperature is, for example, 100-150°C.

[0050] In some embodiments of the present application, the step of preparing the second precursor includes:

[0051] Prepare an ammonia-alkali solution, optionally, the ammonia-alkali solution NH 4+ The ion concentration is between 0.01mol / L and 0.5mol / L, the pH is controlled between 10.3 and 11.5, and the ammonia-alkali solution is formed by mixing sodium hydroxide and ammonia water;

[0052] Nickel salt, manganese salt and cobalt salt are mixed in a molar ratio of (1-ab): a: b, with Mn a Co b Ni 1-a-b (OH)2 in the form of, dissolved in deionized water, and adding an appropriate amount of 0.001-0.1 mol / L reducing agent and stirring, wherein a=0.4-0.1, b=0-0.2, 1-ab≤1, the reducing agent is sodium borohydride, hydrazine hydrate, etc., to obtain a second metal salt solution;

[0053] After filtering and removing impurities from the ammonia-alkali solution and the second metal salt solution, the solution is transferred into a reaction kettle, and a protective gas is introduced while stirring and heating to obtain a second product under alkaline conditions, wherein the protective gas is nitrogen, argon, etc.;

[0054] The second product is extracted, filtered and dried to obtain the second precursor.

[0055] In a third aspect, the present invention provides a method for preparing a lithium-rich manganese-based positive electrode material, the method for preparing a lithium-rich manganese-based positive electrode material comprising the following steps: mixing the lithium-rich manganese-based precursor described in any one of the above items and a lithium source to form a mixture, and sintering the mixture to obtain a lithium-rich manganese-based positive electrode material, wherein the sintering temperature is 400-900°C.

[0056] In some embodiments of the present invention, the lithium source includes lithium carbonate and / or lithium hydroxide. In the mixture, the weight ratio of the lithium-rich manganese-based precursor to the lithium source is .

[0057] In a fourth aspect, the present invention provides a lithium-rich manganese-based positive electrode material, wherein the lithium-rich manganese-based positive electrode material is prepared by the above-mentioned method for preparing the lithium-rich manganese-based positive electrode material.

[0058] In some embodiments of the present invention, the chemical formula of the lithium-rich manganese-based positive electrode material is Li c Mn e Co f M j N (1-e-f-j) O d , wherein c=1.1-1.4, d=2.0-2.5, e=0.4-1, f=0-0.2, j=0-0.2; 1-efj≤1, wherein the M element includes one or two of the elements Ni, Mg, Cu, Fe, Zn, Zr, Y, Al, Sr, W, Na, Nb, Si, B, La, Ru, etc.; the N element includes one or two of the elements Ni, Mg, Cu, Fe, Zn, Zr, Y, Al, Sr, W, Na, Nb, Si, B, La, Ru, etc.; the upper limit voltage use range of the lithium-rich manganese-based positive electrode material is 4.35-4.6V, the median particle size of the lithium-rich manganese-based positive electrode material is 4-7um, the particle size distribution width is 0.7-1.4, and the surface area is 1-5m 2 The oil absorption value OA of the lithium-rich manganese-based positive electrode material is 1% to 65%, wherein the oil absorption value OA=oil absorption / 100g lithium-rich manganese-based powder or ternary powder, and the oil absorption is the minimum amount of oil required to completely wet 100g lithium-rich manganese-based powder.

[0059] Table 2 is a performance comparison table of the lithium-rich manganese-based positive electrode material (code-named A) prepared from a lithium-rich manganese-based precursor, the lithium-rich manganese-based positive electrode material (code-named B) prepared from a carbonate precursor, and the lithium-rich manganese-based positive electrode material (code-named C) prepared from a hydroxide precursor provided in an embodiment of the present invention.

[0060]

[0061] Table 2

[0062] Referring to Table 2, it can be seen that the tap density of the lithium-rich manganese-based positive electrode material prepared by the carbonate precursor in the related art is 1.5-1.7 g / cc, the compaction density is 2.5-2.7 g / cc, the specific capacity is 200-210 mAh / g at room temperature (25°C) 2.5-4.5V, the rate performance is 94% at room temperature (25°C) 2.5-4.5V, 0.5C, and the capacity retention rate of 8 after 500 cycles at room temperature (25°C) is 1.5-2.7 g / cc. 4%; the tap density of the lithium-rich manganese-based positive electrode material prepared by the hydroxide precursor in the related art is 1.6-1.9 g / cc, the compaction density is 2.8-3.0 g / cc, the specific capacity is 210-220 mAh / g under the conditions of 2.5-4.5 V at room temperature (25°C), the rate performance is 96% under the conditions of 2.5-4.5 V at room temperature (25°C), and the capacity retention rate after 500 cycles at room temperature (25°C) is 88%.

[0063] The tap density of the lithium-rich manganese-based positive electrode material provided in the embodiment of the present invention is 1.8-2.2 g / cc, the compacted density is 2.9-3.2 g / cc, the specific capacity is 215-225 mAh / g under normal temperature (25°C) 2.5-4.5 V conditions, the rate performance is 98% under normal temperature (25°C) 2.5-4.5 V, 0.5C conditions, and the capacity retention rate after 500 cycles at normal temperature (25°C) is 93%.

[0064] Figure 1 The XRD spectrum of the lithium-rich manganese-based positive electrode material provided in the embodiment of the present invention. Figure 1 As shown, the lithium-rich manganese-based positive electrode material has an α-NaFeO2 crystal layered structure, and a clear and obvious characteristic peak appears at about 2θ=20°C in the XRD spectrum. The splitting degree of the I006 / I102 and I108 / I110 characteristic peaks is obviously 0.1-10, and the value of I003 / I104 is 1.0-15.

[0065] Figure 2 This is a SEM electron microscope morphology analysis diagram of the lithium-rich manganese-based positive electrode material provided in an embodiment of the present invention. Figure 2 As shown, after SEM electron microscope morphology analysis of the lithium-rich manganese-based material of the mixed precursor, it can be seen that the primary particles on the surface of the sintered finished particles are densely packed, there are few voids inside the particles, and they are in a solid state. The internal porosity is less than 5%, and the sample has good crystallinity, accounting for 50% to 90%.

[0066] In a fifth aspect, an embodiment of the present invention provides a method for preparing a lithium ion battery, the method for preparing a lithium ion battery comprising the following steps:

[0067] The lithium-rich manganese-based positive electrode material described in any one of the above items is mixed with a first conductive agent and a first binder to form a first slurry, and the first slurry is coated on an aluminum foil, and then dried, cold pressed, sliced ​​or striped to obtain a positive electrode sheet;

[0068] A negative electrode material is mixed with a second conductive agent and a second binder to form a second slurry, and the second slurry is coated on a copper foil, and then dried, cold pressed, sliced ​​or striped to obtain a negative electrode sheet;

[0069] Assembling the positive electrode sheet and the negative electrode sheet into a battery cell;

[0070] The battery core is baked, liquid injected, formed and capacity divided to obtain a lithium ion battery.

[0071] In some embodiments of the present invention, the first conductive agent includes conductive carbon black (SP) and carbon nanotubes, and the first binder includes polyvinylidene fluoride (PVDF).

[0072] In some embodiments of the present invention, in the first slurry, the weight ratio of the lithium-rich manganese-based positive electrode material, the first conductive agent, and the first binder is 90:5:5.

[0073] In some embodiments of the present invention, the negative electrode material is graphite, the second conductive agent includes conductive carbon black, and the second binder includes sodium carboxymethyl cellulose (CMC) and styrene-butadiene rubber (SBR).

[0074] In some embodiments of the present invention, in the second slurry, the weight ratio of the negative electrode material, the second conductive agent, and the second binder is 90:5:5.

[0075] In some embodiments of the present invention, the battery cell is a laminated soft-pack battery cell or a cylindrical battery cell.

[0076] In a sixth aspect, the present invention provides a lithium ion battery, wherein the lithium ion battery is prepared by the above-mentioned method for preparing a lithium ion battery.

[0077] In summary, the present invention provides a lithium-rich manganese-based precursor and a preparation method thereof, a lithium-rich manganese-based positive electrode material and a preparation method thereof, a lithium-ion battery and a preparation method thereof, wherein the lithium-rich manganese-based precursor comprises a first precursor and a second precursor, wherein one of the first precursor and the second precursor has a particle size of 1 to 3 μm and a specific surface area of ​​3 to 6 m 2 / g; the particle size of the other of the first precursor and the second precursor is 7 to 10 um, and the specific surface area is 0.8 to 2 m 2 / g. In the lithium-rich manganese-based precursor provided by the present invention, since the particle size of the first precursor is different from that of the second precursor, and the difference between the particle sizes is controlled within 4 to 9 μm, the specific surface area of ​​the first precursor is different from that of the second precursor, and the difference between the specific surface areas is controlled within 1 to 5.2, so that after the first precursor and the second precursor of different particle sizes are mixed with each other, the precursor particles with a smaller particle size can be filled into the gaps between the precursor particles with a larger particle size, so that the particles are more densely stacked, and the lithium-rich manganese-based positive electrode material obtained after sintering has better particle morphology and particle size distribution, and the particles have better structural stability.

[0078] The embodiments of the present invention are described in detail above. Specific examples are used herein to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as a limitation on the present invention.

Claims

1. A lithium-rich manganese-based precursor, characterized in that: The lithium-rich manganese-based precursor includes a first precursor and a second precursor mixed in a first weight ratio, wherein the first weight ratio is 20:80-80:20; The particle size of one of the first precursor and the second precursor is 1-3 μm, and the specific surface area is 3-6 m 2 / g; The particle size of the other of the first precursor and the second precursor is 7-10 μm, and the specific surface area is 0.8-2 m 2 / g; The chemical formula of the first precursor is Mn x Co y M 1-x-y CO3, wherein 0.4<x<1, 0<y<0.2, x+y≤1, wherein the M element includes one or two of Ni, Mg, Cu, Fe, Zn, Zr, Y, Al, Sr, W, Na, Nb, Si, B, La, and Ru elements; The chemical formula of the second precursor is Mn a Co b N 1-a-b (OH)2, wherein a=0.4~1, b=0~0.2, 1-ab≤1, and the N element includes one or two of Ni, Mg, Cu, Fe, Zn, Zr, Y, Al, Sr, W, Na, Nb, Si, B, La, and Ru elements.

2. The lithium-rich manganese-based precursor according to claim 1, characterized in that: The weight ratio of the first precursor to the second precursor is 20:80 or 30:

70.

3. The lithium-rich manganese-based precursor according to claim 1 or 2, characterized in that: The difference between the particle size of the first precursor and the particle size of the second precursor is 4um~9um, and the difference between the specific surface area of ​​the first precursor and the specific surface area of ​​the second precursor is 1m 2 / g ~5.2m 2 / g.

4. A method for preparing a lithium-rich manganese-based precursor, for preparing the lithium-rich manganese-based precursor according to any one of claims 1 to 3, characterized in that: The method for preparing the lithium-rich manganese-based precursor comprises the following steps: preparing a first precursor; preparing a second precursor; Mixing the first precursor and the second precursor in a first weight ratio to obtain the lithium-rich manganese-based precursor; The first weight ratio is 20:80-80:20; the particle size of one of the first precursor and the second precursor is 1-3 μm, and the specific surface area is 3-6 m 2 / g; the particle size of the other of the first precursor and the second precursor is 7~10um, and the specific surface area is 0.8~2m 2 / g.

5. The method for preparing a lithium-rich manganese-based precursor according to claim 4, characterized in that: The steps of preparing the first precursor include: Prepare an organic buffer solution, wherein the pH value of the organic buffer solution is 7.0-8.3; Dissolving nickel salt, manganese salt and cobalt salt in a solvent to obtain a first metal salt solution; Under the protection of an inert gas, the first metal salt solution and the carbonate solution are respectively injected into a reaction kettle containing the organic buffer solution, stirred for reaction, and aged to obtain a first product; Post-processing the first product to obtain the first precursor; The steps of preparing the second precursor include: preparing an ammonia-alkali solution, wherein the ammonia-alkali solution is formed by mixing sodium hydroxide and aqueous ammonia; Dissolving nickel salt, manganese salt and cobalt salt in deionized water, adding a reducing agent and stirring to obtain a second metal salt solution; After filtering and removing impurities from the ammonia-alkali solution and the second metal salt solution, the solution is transferred into a reaction kettle, and a protective gas is introduced while stirring and heating the solution to obtain a second product under alkaline conditions; The second product is extracted, filtered and dried to obtain the second precursor.

6. A method for preparing a lithium-rich manganese-based positive electrode material, characterized in that: The method for preparing the lithium-rich manganese-based positive electrode material comprises the following steps: Mixing the lithium-rich manganese-based precursor according to any one of claims 1 to 3 with a lithium source to form a mixture, and sintering the mixture to obtain a lithium-rich manganese-based positive electrode material; Wherein, the sintering temperature is 400~900℃.

7. A lithium-rich manganese-based positive electrode material, characterized in that: The lithium-rich manganese-based positive electrode material is prepared by the preparation method of the lithium-rich manganese-based positive electrode material according to claim 6.

8. The lithium-rich manganese-based positive electrode material according to claim 7, characterized in that: The chemical formula of the lithium-rich manganese-based positive electrode material is Li c Mn e Co f M j N （1-e-f-j） O d , wherein c=1.1~1.4, d=2.0~2.5, e=0.4~1, f=0~0.2, j=0~0.2; 1-efj≤1, wherein the M element includes one or two of the following elements: Ni, Mg, Cu, Fe, Zn, Zr, Y, Al, Sr, W, Na, Nb, Si, B, La, and Ru; the N element includes one or two of the following elements: Ni, Mg, Cu, Fe, Zn, Zr, Y, Al, Sr, W, Na, Nb, Si, B, La, and Ru; the median particle size of the lithium-rich manganese-based positive electrode material is 4~7 um, the particle size distribution width is 0.7~1.4, and the specific surface area is 1~5 m 2 / g.

9. A method for preparing a lithium ion battery, characterized in that: The preparation method of the lithium ion battery comprises the following steps: The lithium-rich manganese-based positive electrode material according to any one of claims 7 to 8 is mixed with a first conductive agent and a first binder to form a first slurry, and the first slurry is coated on an aluminum foil, and then dried, cold pressed, sliced ​​or striped to obtain a positive electrode sheet; A negative electrode material is mixed with a second conductive agent and a second binder to form a second slurry, and the second slurry is coated on a copper foil, and then dried, cold pressed, sliced ​​or striped to obtain a negative electrode sheet; Assembling the positive electrode sheet and the negative electrode sheet into a battery cell; The battery core is baked, liquid injected, formed and capacity divided to obtain a lithium ion battery.

10. A lithium ion battery, characterized in that: The lithium ion battery is prepared by the method for preparing a lithium ion battery according to claim 9.

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