CN-116230935-B - Positive electrode material, preparation method thereof and lithium ion battery

CN116230935BCN 116230935 BCN116230935 BCN 116230935BCN-116230935-B

Abstract

The application relates to a positive electrode material, a preparation method thereof and a lithium ion battery. The positive electrode material comprises a substrate and a coating layer at least coated on the surface of the substrate, wherein the chemical general formula of the substrate is shown as formula (I), li a Ni b Co c N d M 2 e O 2 (I) is shown as formula (I), N comprises Mn and/or Al, M 2 comprises at least one of Zr, sr, co, ba, Y, ce, al, mg and La, the chemical general formula of the coating layer is shown as formula (II), li g M 1 (2h‑g)/i O h (II) is shown as formula (II), M 1 comprises at least one of Mn, ti, W, mo and Nb, and in a diffraction pattern measured by adopting X-ray diffraction of the positive electrode material, the positive electrode material has diffraction peaks 2 theta 102 of a (102) surface, diffraction peaks 2 theta 006 of a (006) surface, diffraction peaks 2 theta 108 ,2θ 102 、2θ 006 、2θ 110 and 2 theta 108 of a (110) surface and diffraction peaks 2 theta 110 of a (108) surface, and the following relationship is that 2 theta 102 -2θ 006 ≥0.25、2θ 110 -2θ 108 is more than or equal to 0.33.

Inventors

LI XU
LUO LIANG
ZHENG YU
YANG SHUNYI
HUANG YOUYUAN

Assignees

深圳市贝特瑞纳米科技有限公司

Dates

Publication Date: 20260508
Application Date: 20221221

Claims (11)

1. The positive electrode material is characterized by comprising a matrix and a coating layer which is coated on at least part of the surface of the matrix, wherein the chemical general formula of the matrix is shown in the formula (I): Li a Ni b Co c N d M 2 e O 2 (I) In the formula (I), N comprises Mn and/or Al, M 2 comprises at least one of Zr, sr, co, ba, Y, ce, al, mg and La, a is more than or equal to 0.95 and less than or equal to 1.08,0.3 b is more than or equal to 1, c is more than or equal to 0 0.7,0< d is less than or equal to 0.5,0< e is less than or equal to 0.1, b+c+d+e=1; The coating layer comprises a compound shown as a chemical formula (II); Li g M 1 (2h-g)/i O h (II) In the formula (II), M 1 comprises at least one of Mn, ti, W, mo and Nb, i is a valence value of M 1 ion, and g, h, (2 h-g)/i are positive integers; In a diffraction pattern of the positive electrode material measured by using X-ray diffraction, the positive electrode material has a diffraction peak 2θ 102 of a (102) plane, a diffraction peak 2θ 006 of a (006) plane, a diffraction peak 2θ 110 of a (110) plane and a diffraction peak 2θ 108 of a (108) plane, and the 2θ 102 、2θ 006 、2θ 110 and 2θ 108 satisfy the following relationship: 2θ 102 -2θ 006 ≥0.25 (III) 2θ 110 -2θ 108 ≥0.33 (IV) (2θ 102 -2θ 006 )/(2θ 110 -2θ 108 )≥0.7 (VII); the positive electrode material comprises primary particles, and further comprises lithium boron oxide coated on the primary particles.
2. The positive electrode material according to claim 1, wherein the chemical formula of the matrix is represented by formula (V): Li a Ni b Co c N d M 2 e M 3 f O 2 (V) In the formula (V), M 3 comprises at least one of Mn, ti, W, mo, nb, zr, co, Y, ce, al and La, 0<f is less than or equal to 0.1, and b+c+d+e+f=1; The coating layer comprises a compound shown in a chemical formula (VI); Li g M 1 (2h-g)/i O h ·NiO·LiMn 2 O 4 (VI) the positive electrode material comprises primary particles, and further comprises lithium boron oxide coated on the primary particles.
3. The positive electrode material according to claim 1 or 2, characterized in that the positive electrode material comprises at least one of the following features (1) to (8): (1) The median particle diameter of the primary particles is 2.0-6.0 mu m; (2) The positive electrode material includes secondary particles including a plurality of primary particles; (3) The ratio of the mass of Ni 2+ in the surface layer of the positive electrode material to the total mass of Ni 2+ and Ni 3+ in the positive electrode material is more than or equal to 0.6, wherein the surface layer of the positive electrode material refers to a part of the surface of the positive electrode material extending to the interior of the positive electrode material by 0-20 nm in thickness; (4) In the XRD spectrum of the positive electrode material, the diffraction peak intensity ratio I 003 /Ⅰ 104 between the (003) plane and the (104) plane is more than or equal to 1.3; (5) When the positive electrode material is charged to 4.3V, the lattice parameter change rate of the positive electrode material is less than or equal to 5 percent; (6) When the positive electrode material is charged to 4.3V, the unit cell volume change rate of the positive electrode material is less than or equal to 6%; (7) When the positive electrode material is charged to 4.3V, the particle strength of the positive electrode material is more than or equal to 200MPa; (8) The mass ratio of Li g M 1 (2h-g)/i O in the positive electrode material is 0% -1%, and 0 is not included.
4. The positive electrode material according to claim 2, wherein the mass ratio of NiO in the positive electrode material is 0% -10%.
5. The preparation method of the positive electrode material is characterized by comprising the following steps: Mixing Ni (1-c-d) Co c N d （OH） 2 precursor, lithium salt, metal boride and fluxing agent, and then carrying out sectional heating treatment to obtain a positive electrode material, wherein the metal element in the metal boride comprises at least one of Mn, ti, W, mo and Nb, the metal boride can react with the lithium salt, the ratio of the total amount of the metal element in the metal boride to the amount of the positive electrode material is 0.01% -1%, the fluxing agent comprises at least one of oxide, hydroxide or salt of at least one of Zr, sr, co, ba, Y, ce, al, mg and La, the ratio of the total amount of the metal element in the fluxing agent to the total amount of the positive electrode material is 0.02% -10%, wherein N comprises Al and/or Mn,0<c is less than or equal to 0.7, and d is less than or equal to 0.5.
6. The preparation method according to claim 5, wherein the preparation method comprises at least one of the following features (1) to (6): (1) The median particle diameter of the Ni (1-c-d) Co c N d (OH) 2 precursor is 2-6 mu m; (2) The metal boride comprises at least one of MoB, W 2 B 5 , nbB, mnB and TiB 2 ; (3) The median particle diameter of the metal boride is 10 nm-500 nm; (4) The fluxing agent comprises at least one of Y 2 O 3 、La 2 O 3 、ZrO 2 、Y(OH) 3 、Mg(OH) 2 、Al(OH) 3 and Cl 3 Y; (5) The median particle diameter of the fluxing agent is 10 nm-500 nm; (6) The lithium salt includes at least one of lithium carbonate, lithium hydroxide, lithium acetate, lithium nitrate, lithium phosphate, and lithium oxalate.
7. The preparation method according to claim 5, wherein the preparation method comprises at least one of the following features (1) to (4): (1) The sectional heating treatment is carried out in an oxygen or air atmosphere; (2) The sectional heating treatment comprises heating to 300-750 ℃, preserving heat for 2-24 hours, heating to 750-1000 ℃ and preserving heat for 5-24 hours; (3) The step of crushing the materials obtained by the sectional heating treatment is further included after the sectional heating treatment; (4) The step of pulverizing the material obtained by the step of heating the material in a stepwise manner is further included after the step of heating the material in a stepwise manner, and the step of pulverizing includes at least one of grinding and crushing.
8. The method according to claim 5, wherein the positive electrode material is obtained by mixing the positive electrode material with a mixture containing lithium permanganate and a metal compound having a valence of +3 or more and then performing heat treatment.
9. The preparation method according to claim 8, wherein the preparation method comprises at least one of the following features (1) to (6): (1) The metal compound with the valence of +3 or more comprises at least one of oxides, borides, hydroxides or salts of at least one element of Mn, ti, W, mo, nb, zr, co, Y, ce, al and La; (2) The ratio of the total mass of the metal elements in the metal compound with the valence of more than or equal to +3 to the total mass of the transition metal elements in the heat-treated positive electrode material is 0.02% -10%; (3) The median particle diameter of the metal compound with the valence of +3 or more is 10 nm-500 nm; (4) The concentration of the lithium permanganate in the mixture containing the lithium permanganate and the metal compound with the valence of more than or equal to +3 is 0.02 g/L-10 g/L; (5) The ratio of the total substance amount of the lithium permanganate to the total substance amount of the transition metal element in the heat-treated positive electrode material is 0.01% -2%; (6) The method further comprises the step of drying the mixture containing lithium permanganate and the metal compound with the valence of +3 or more with the positive electrode material after the mixture is mixed with the mixture containing lithium permanganate and the metal compound with the valence of +3 or more and before the heat treatment.
10. The preparation method according to claim 8, wherein the preparation method comprises at least one of the following features (1) - (3): (1) The heat treatment is performed under an oxygen or air atmosphere; (2) The temperature of the heat treatment is 200-800 ℃; (3) The heat preservation time of the heat treatment is 5-24 hours.
11. A lithium ion battery, characterized in that the lithium ion battery comprises the positive electrode material according to any one of claims 1 to 4 or the positive electrode material prepared by the preparation method according to any one of claims 5 to 10.

Description

Positive electrode material, preparation method thereof and lithium ion battery Technical Field The invention belongs to the technical field of positive electrode materials, and particularly relates to a positive electrode material, a preparation method thereof and a lithium ion battery. Background Environmental pollution and energy crisis become two major problems of development in the world today, and it is urgent to solve the excessive consumption of traditional fossil energy and the environmental problems caused by the excessive consumption of the traditional fossil energy, and development and utilization of new energy are more and more highly valued in countries around the world. The development of new energy electric vehicles is an important way for improving the competitiveness of the automobile industry in China, guaranteeing the energy safety and developing low-carbon economy, and the key of the development of electric vehicles is the development of power batteries. However, new energy electric vehicles are not widely accepted by people, and compared with traditional fuel oil vehicles, the electric vehicles have larger differences in price, endurance mileage, safety and the like. The lithium ion power battery plays a decisive role as a core component and a development bottleneck of the electric automobile. And the positive electrode material is a key factor affecting the cost, energy density and safety of the lithium ion battery. The energy density of lithium cobaltate, lithium iron phosphate and lithium manganate is lower than 180mAh/g, the increasing demand of the application field of lithium ion batteries on the energy density can not be met, and the high-nickel ternary material is used as a novel positive electrode material, has the comprehensive advantages of high energy density, high working voltage and high tap density, and is widely applied to the fields of 3C and power batteries. Along with the continuous improvement of the nickel content in the high-nickel ternary material, the high-rate performance and the impedance of the material are extremely challenged, and the current method for improving the rate performance and the thermal stability of the material mainly comprises doping and cladding. The conventional coating material subjected to coating modification treatment is a unitary material, and coating is performed simultaneously when preparing a precursor end, so that the nickel content of an inner substrate of the material is greatly different from that of an outer coating layer, thereby resulting in lower capacity of the material and poorer operability. Therefore, there is a need to develop a positive electrode material that is simple in process and compatible with high capacity. Disclosure of Invention The application aims to provide a positive electrode material, a preparation method thereof and a lithium ion battery. In a first aspect, an embodiment of the present application provides a positive electrode material, where the positive electrode material includes a substrate and a coating layer at least covering a surface of the substrate, and a chemical general formula of the substrate is shown in formula (I): LiaNibCocNdM2eO2(I) In the formula (I), N comprises Mn and/or Al, M 2 comprises at least one of Zr, sr, co, ba, Y, ce, al, mg and La, a is more than or equal to 0.95 and less than or equal to 1.08,0.3 and b is more than or equal to 0.95C is more than or equal to 1 and less than or equal to 0 and less than or equal to 0.7,0 not less than 1, not less than 0 and not more than c 0.7,0 or less; the chemical general formula of the coating layer is shown as a formula (II): LigM1(2h-g)/iOh(II) In the formula (II), M 1 comprises at least one of Mn, ti, W, mo and Nb, i is a valence value of M 1 ion, and g, h, (2 h-g)/i are integers; in a diffraction pattern of the positive electrode material measured by X-ray diffraction, the positive electrode material has (102) Diffraction peak 2 theta 102 of plane, diffraction peak 2 theta 006 of (006) plane, diffraction peak 2 theta 110 of (110) plane, and (108) Diffraction peaks 2 theta 108 of the plane, wherein the 2 theta 102、2θ006、2θ110 and 2 theta 108 meet the following relation: 2θ102-2θ006≥0.25(III) 2 theta 110-2θ108 is more than or equal to 0.33 (IV). In some embodiments, the substrate has a chemical formula of formula (V): LiaNibCocNdM2eM3fO2(V) In the formula (V), M 3 comprises at least one of Mn, ti, W, mo, nb, zr, co, Y, ce, al and La, f is more than or equal to 0 and less than or equal to 0.1, and b+c+d+e+f=1; The chemical general formula of the coating layer is shown in a formula (VI): LigM1(2h-g)/iOh·NiO·LiMn2O4(VI)。 In some embodiments, the positive electrode material includes at least one of the following features (1) - (10): (1) The positive electrode material comprises primary particles, wherein the median particle diameter of the primary particles is 2.0-6.0 mu m; (2) The positive electrode material includes secondary particles