CN-122025624-A - Polycrystalline positive electrode material, preparation method thereof, lithium battery and power utilization device

CN122025624ACN 122025624 ACN122025624 ACN 122025624ACN-122025624-A

Abstract

The application relates to the technical field of batteries, and discloses a polycrystalline positive electrode material, a preparation method thereof, a lithium battery and an electric device. The polycrystalline positive electrode material comprises polycrystalline particles, wherein the polycrystalline particles comprise an inner core and a coating layer coated on at least part of the surface of the inner core, the polycrystalline particles comprise a compound shown as a formula LiM b Ni c Mn d X e O 4‑e , the polycrystalline positive electrode material is tested in a half battery taking a metal lithium sheet as a counter electrode, three groups of redox peaks exist in a capacity/voltage differential curve under the conditions of 3.8-4.9V and 0.1C, the equilibrium potential of the redox peaks in the first group is 3.9-4.1V, the equilibrium potential of the redox peaks in the second group is 4.4-4.9V, and the equilibrium potential of the redox peaks in the third group is 4.5-4.98V. The positive electrode material has excellent electrochemical properties.

Inventors

YANG NINGNING
ZHANG LIPING
ZHANG WEINING
SONG SHUNLIN
LIU YAFEI
CHEN YANBIN

Assignees

北京当升材料科技股份有限公司

Dates

Publication Date: 20260512
Application Date: 20260212

Claims (13)

1. A polycrystalline positive electrode material comprising polycrystalline particles, the polycrystalline particles comprising a compound of the formula: LiM b Ni c Mn d X e O 4-e m comprises at least one of Al, mg, ti, sb; X comprises at least one of F, P, S, B; Wherein, the b is more than or equal to 0 and less than or equal to 0.1, and 0 is more than or equal to 0 c is less than or equal to 1.5, d is less than or equal to 0 and less than or equal to 1 c is less than or equal to 1.5,0 d is less than or equal to; testing the polycrystalline positive electrode material in a half battery taking a metal lithium sheet as a counter electrode, wherein three groups of redox peaks exist in a capacity/voltage differential curve under the conditions of 3.8V-4.9V and 0.1C/0.1V, and the three groups of redox peaks are respectively defined as a first group of redox peaks, a second group of redox peaks and a third group of redox peaks according to the balance potential of the redox peaks from low to high, wherein the balance potential of the first group of redox peaks is 3.9V-4.1V, the balance potential of the second group of redox peaks is 4.4V-4.9V, and the balance potential of the third group of redox peaks is 4.5V-4.98V; The first set of redox peaks includes a first oxidation peak and a first reduction peak; the second set of redox peaks includes a second oxidation peak and a second reduction peak; The third set of redox peaks includes a third oxidation peak and a third reduction peak.
2. The polycrystalline positive electrode material according to claim 1, wherein at least one of the following is satisfied: 0.6< S0 50 /S0 <1, preferably 0.8< S0 50 /S0 <1; 0.6< S1 50 /S1 <1, preferably 0.8< S1 50 /S1 <1; 0.6< S2 50 /S2 <1, preferably 0.8< S2 50 /S2 <1; 0.5< S1/S2<1.5, preferably 0.9< S1/S2<1.1; 0≤S0/(S1+S2) <0.1, preferably 0.03≤S0/(S1+S2) <0.08; Wherein, S0, S1 and S2 are respectively the peak areas of the first oxidation peak, the second oxidation peak and the third oxidation peak in the capacity/voltage differential curve of the half cell under the conditions of 3.8V-4.9V and 0.1C/0.1C of first charge and discharge; S0 50、 S1 50、 S2 50 is respectively the peak areas of the first oxidation peak, the second oxidation peak and the third oxidation peak in the capacity/voltage differential curve of the half cell after 50 weeks of charge-discharge circulation under the conditions of 3.8V-4.9V and 0.1C/0.1C.
3. The polycrystalline positive electrode material according to claim 1, wherein at least one of the following is satisfied: K0-K0 '0≤0.02, preferably K0-K0' 0≤0.01; K1-K1 'is more than or equal to 0 and less than or equal to 0.05, preferably K1-K1' is more than or equal to 0.01 and less than or equal to 0.03; K2-K2' is less than or equal to 0 and less than or equal to 0.04, preferably 0 is less than or equal to 0 and less than or equal to 0.02; The method comprises the steps of obtaining a capacity/voltage differential curve of a half battery, wherein under the conditions of K0 being 3.8V-4.9V and 0.1C/0.1C, the balance potential of a first oxidation peak in the capacity/voltage differential curve of the half battery, K0' is the balance potential of a first reduction peak, K1 is the balance potential corresponding to a second oxidation peak, K1' is the balance potential corresponding to the second reduction peak, K2 is the balance potential corresponding to a third oxidation peak, and K2' is the voltage corresponding to the third reduction peak.
4. The polycrystalline positive electrode material according to claim 3, wherein at least one of: k0 is less than or equal to 3.9V and less than or equal to 4.1V, and K0 is less than or equal to 3.95V and less than or equal to 4.05V; K0 'or less than or equal to 3.9V or less than or equal to 4.1V, preferably 3.95V or less than or equal to K0' or less than or equal to 4.05V; k1 is more than or equal to 4.4V and less than or equal to 4.9V, and K1 is more than or equal to 4.6V and less than or equal to 4.8V; K1 'or less than or equal to 4.4V or less than or equal to 4.8V, preferably K1' or less than or equal to 4.8V; k2 is more than or equal to 4.5V and less than or equal to 4.98V, and K2 is more than or equal to 4.6V and less than or equal to 4.8V; k2 'is less than or equal to 4.5V and less than or equal to 4.98V, preferably 4.6V is less than or equal to K2' and less than or equal to 4.8V.
5. The polycrystalline positive electrode material according to claim 1, characterized in that the polycrystalline positive electrode material satisfies: D 1 with an angle of 0.13 DEG or less less than or equal to 0.16 degrees, preferably, d 1 is more than or equal to 0.14 degrees and less than or equal to 0.16 degrees; D 2 is less than or equal to 0.18 DEG less than or equal to 0.21 degrees, preferably, d 2 is more than or equal to 0.19 degrees and less than or equal to 0.21 degrees; D 3 is less than or equal to 0.20 DEG less than or equal to 0.25 degrees, preferably, d 3 is more than or equal to 0.21 degrees and less than or equal to 0.23 degrees; Wherein d 1 is half-width of an X-ray diffraction peak corresponding to a crystal face of the polycrystalline positive electrode material (111), d 2 is half-width of an X-ray diffraction peak corresponding to a crystal face of the polycrystalline positive electrode material (311), and d 3 is half-width of an X-ray diffraction peak corresponding to a crystal face of the polycrystalline positive electrode material (400).
6. The polycrystalline positive electrode material according to claim 1, characterized in that the polycrystalline positive electrode material satisfies: 0≤I 1 /（I 2 +I 1 ). Ltoreq.1, preferably 0.5≤I 1 /（I 2 +I 1 ). Ltoreq.1; 0≤I 2 /（I 3 +I 2 ). Ltoreq.1, preferably 0.3≤I 2 /（I 3 +I 2 ). Ltoreq.0.7; Wherein, I 1 is the peak intensity of the X-ray diffraction peak corresponding to the crystal face of the polycrystalline positive electrode material (111), I 2 is the peak intensity of the X-ray diffraction peak corresponding to the crystal face of the polycrystalline positive electrode material (311), and I 3 is the peak intensity of the X-ray diffraction peak corresponding to the crystal face of the polycrystalline positive electrode material (400).
7. The polycrystalline positive electrode material according to claim 1, wherein the polycrystalline particles comprise a core and a coating layer coating at least part of the surface of the core, the concentration of X decreases in a gradient along the direction from the center to the surface of the polycrystalline particles, and the polycrystalline particles satisfy: a is more than or equal to 0.1 and less than or equal to 10, preferably, A is more than or equal to 1 and less than or equal to 3; Wherein a= (D 90 -D 50 ）/（D 50 -D 10 ).
8. The polycrystalline positive electrode material according to claim 7, wherein at least one of the following conditions is satisfied: D 10 of the polycrystalline particles satisfies that D 10 is less than or equal to 1 mu m and less than or equal to 10 mu m, preferably D 10 is less than or equal to 3 mu m and less than or equal to 8 mu m; The D 50 of the polycrystalline particles is that D 50 is less than or equal to 5 mu m and less than or equal to 15 mu m, preferably D 50 is less than or equal to 6 mu m and less than or equal to 10 mu m; D 90 of the polycrystalline particles satisfies that D 90 is less than or equal to 6 mu m and less than or equal to 20 mu m, preferably D 90 is less than or equal to 7 mu m and less than or equal to 16 mu m; The specific surface area of the polycrystalline particles is 0.3m 2 /g-2.0m 2 /g, preferably 0.4m 2 /g-1.5m 2 /g; the compacted density of the polycrystalline positive electrode material is 2.3g/cm 3 -3.1g/cm 3 , preferably 2.5g/cm 3 -2.9g/cm 3 .
9. A method of preparing the polycrystalline cathode material of any one of claims 1 to 8, comprising: Mixing nickel manganese hydroxide, lithium salt and a lithium compound containing X to obtain a first mixture; sequentially performing first sintering, first crushing and first sieving on the first mixture to obtain a first sintered product; mixing the primary combustion product with an oxide containing M to obtain a second mixture; sequentially performing second sintering, second crushing and second sieving on the second mixture to obtain a polycrystalline anode material; The first sintering includes: Raising the temperature of the first mixture from normal temperature to 500-700 ℃ at a speed of 1.0-6.0 ℃ per minute; Heating from 500-700 ℃ to 750-900 ℃ at a speed of 1.0-6.0 ℃ per minute, and keeping the temperature for 5-10 h at constant temperature; cooling from 750-900 ℃ to 500-700 ℃ at a speed of 1.0-6.0 ℃ per minute, and keeping the temperature for 1-12 h at constant temperature; cooled to room temperature.
10. The method of claim 9, wherein at least one of the following conditions is satisfied: The D50 of the nickel-manganese hydroxide is 6-12 mu m; The lithium salt comprises at least one of lithium carbonate and lithium hydroxide; the X-containing lithium compound comprises at least one of lithium phosphate, ammonium dihydrogen phosphate, lithium fluoride, lithium borate and lithium sulfate; The M-containing oxide comprises at least one of aluminum oxide, magnesium oxide, titanium oxide, silicon oxide, aluminum fluoride and magnesium sulfide.
11. The method of preparing according to claim 9, wherein the second sintering comprises: Raising the temperature of the second mixture from normal temperature to 500-900 ℃ at a speed of 1.0-6.0 ℃ per minute, and keeping the temperature for 6-12 hours at constant temperature; cooled to room temperature.
12. A lithium battery comprising the polycrystalline positive electrode material according to any one of claims 1 to 8.
13. An electrical device comprising the polycrystalline positive electrode material according to any one of claims 1 to 8 or the lithium battery according to claim 12.

Description

Polycrystalline positive electrode material, preparation method thereof, lithium battery and power utilization device Technical Field The application relates to the technical field of batteries, in particular to a polycrystalline positive electrode material, a preparation method thereof, a lithium battery and an electric device. Background Lithium Nickel Manganese Oxide (LNMO) has significant advantages in solid state battery systems as a high voltage positive electrode material. The three-dimensional spinel structure can be compatible with the high interface stability requirement of the solid electrolyte, the theoretical capacity reaches 147 mAh/g, and the energy density is far higher than that of the traditional layered oxide (such as NCM). For example, in a solid state battery, the high voltage characteristics of the LNMO can be matched to the lithium metal negative electrode, significantly increasing the overall energy density of the battery while avoiding the flammability risk of the liquid electrolyte. However, LNMO has some drawbacks in practical application, such as the disproportionation reaction of Mn 3＋ to Mn 2＋ and Mn 4＋ in the high-voltage charge-discharge process of conventional lithium nickel manganese oxide materials. Meanwhile, mn 3+ can lead to lattice distortion (Jahn-Teller distortion) so as to cause microcracks of LNMO materials, and structural stress accumulation generated by Mn 3+ can lead to particle breakage during repeated charge and discharge cycles so as to lead to failure of electrical contact between electrode active materials and a current collector. Thus, solving the above-mentioned problems of LNMO is one of the current challenges. Disclosure of Invention The present application aims to solve at least one of the technical problems in the related art to some extent. Therefore, the application provides a polycrystalline positive electrode material, a preparation method thereof, a lithium battery and an electric device. In a first aspect of the present application, a polycrystalline positive electrode material is presented, comprising polycrystalline particles comprising a compound of the formula: LiMbNicMndXeO4-e m comprises at least one of Al, mg, ti, sb; X comprises at least one of F, P, S, B; Wherein, the b is more than or equal to 0 and less than or equal to 0.1, and 0 is more than or equal to 0 c is less than or equal to 1.5, d is less than or equal to 0 and less than or equal to 1 c is less than or equal to 1.5,0 d is less than or equal to; Testing the polycrystalline positive electrode material in a half battery taking a metal lithium sheet as a counter electrode, wherein three groups of redox peaks exist in a capacity/voltage differential curve under the conditions of 3.8V-4.9V and 0.1C/0.1V, and the 3 groups of redox peaks are respectively defined as a first group of redox peaks, a second group of redox peaks and a third group of redox peaks according to the balance potential of the redox peaks from low to high, wherein the balance potential of the first group of redox peaks is 3.9V-4.1V, the balance potential of the second group of redox peaks is 4.4V-4.9V, and the balance potential of the third group of redox peaks is 4.5V-4.98V; The first set of redox peaks includes a first oxidation peak and a first reduction peak; the second set of redox peaks includes a second oxidation peak and a second reduction peak; The third set of redox peaks includes a third oxidation peak and a third reduction peak. According to the polycrystalline positive electrode material, under the conditions of 3.8V-4.9V and 0.1C/0.1C, three groups of redox peaks exist in a capacity/voltage differential curve at 3.8V-4.9V, and the intensity of different redox reactions of the lithium nickel manganese oxide material in the high-voltage charge and discharge process is controlled by limiting the balance potential of each group of redox peaks, so that the electrochemical performance of the lithium nickel manganese oxide material is optimized. In some embodiments, the polycrystalline positive electrode material meets at least one of: 0.6< S0 50/S0 <1, preferably 0.8< S0 50/S0 <1; 0.6< S1 50/S1 <1, preferably 0.8< S1 50/S1 <1; 0.6< S2 50/S2 <1, preferably 0.8< S2 50/S2 <1; 0.5< S1/S2<1.5, preferably 0.9< S1/S2<1.1; 0≤S0/(S1+S2) <0.1, preferably 0.03≤S0/(S1+S2) <0.08; Wherein, S0, S1 and S2 are respectively the peak areas of the first oxidation peak, the second oxidation peak and the third oxidation peak in the capacity/voltage differential curve of the half cell under the conditions of 3.8V-4.9V and 0.1C/0.1C of first charge and discharge; S0 50、S150、S250 is respectively the peak areas of the first oxidation peak, the second oxidation peak and the third oxidation peak in the capacity/voltage differential curve of the half cell after 50 weeks of charge-discharge circulation under the conditions of 3.8V-4.9V and 0.1C/0.1C. Thus, the capacity retention of the polycrystalline positive electrode material dur