Composite cathode active material, method for preparing the same, cathode, and lithium secondary battery
By coating the surface of nickel-based active materials with lanthanide composite materials, composite positive electrode active materials are prepared, solving the problems of particle aggregation and performance degradation in lithium secondary batteries, and achieving high safety and long lifespan of lithium secondary batteries.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- SAMSUNG SDI CO LTD
- Filing Date
- 2022-06-02
- Publication Date
- 2026-06-12
AI Technical Summary
Existing lithium secondary batteries suffer from problems such as particle aggregation, reduced yield, increased residual lithium, and/or reduced capacity, lifespan, and/or rate performance during the preparation of single-crystal positive electrode active materials, which affect their safety and performance.
A composite positive electrode active material is prepared by coating the surface of nickel-based active material with a lanthanide composite material. Single crystal particles are formed by mechanical grinding and heat treatment. The amount of lanthanide composite material is controlled within a specific range to improve the safety and lifespan of lithium secondary batteries.
By using composite positive electrode active materials with coatings, particle aggregation is suppressed, processing performance and safety are improved, the rate performance and lifespan characteristics of lithium secondary batteries are enhanced, lithium-ion diffusion paths are ensured to be short, surface reactions are reduced, and a stable crystal structure is maintained.
Smart Images
Figure CN115440948B_ABST
Abstract
Claims
1. A composite cathode active material, comprising: A nickel-based active material comprising 60 mol% or more of nickel; And A coating on the surface of the nickel-based active material, the coating comprising a lanthanide composite material, Wherein the composite cathode active material comprises single crystal particles having an average particle size in the range of 2 μm to 8 μm, and Wherein based on 100 parts by weight of the nickel-based active material, the amount of the lanthanide composite material is 0.001 part by weight or more and less than 0.01 part by weight, and Wherein the nickel-based active material is a compound represented by Formula 2: Formula 2 Li a (Ni 1-x-y-z Co x Mn y M z )O 2±α1 ,and Wherein, in Formula 2, M is an element selected from the group consisting of: boron, magnesium, calcium, strontium, barium, titanium, vanadium, chromium, iron, copper, zirconium, aluminum, and cerium, and 0.9 ≤ a ≤ 1.1, 0.6 ≤ (1 - x - y - z) < 1, 0 < x < 0.4, 0 ≤ y < 0.4, 0 ≤ z < 0.4, and 0 ≤ α1 ≤ 0.
1.
2. The composite cathode active material according to claim 1, wherein the lanthanide element in the lanthanide composite material is La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, or a combination thereof.
3. The composite cathode active material according to claim 1, wherein the lanthanide composite material is: i) An oxide comprising La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, or any combination thereof, or ii) An oxide comprising lithium and La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, or any combination thereof.
4. The composite cathode active material according to claim 1, wherein the lanthanide composite material is a compound represented by Formula 1: Formula 1 Li x Ce y O2, and in, In Formula 1, 0 ≤ x ≤ 1.05 and 0.95 ≤ y ≤ 1.
05.
5. The composite cathode active material according to claim 1, wherein the lanthanide composite material is CeO2, LiCeO2, or a combination thereof.
6. The composite cathode active material according to claim 1, wherein the coating is in the form of discontinuous islands.
7. The composite cathode active material according to claim 1, wherein the composite cathode active material has X-ray diffraction peaks in regions where the diffraction angle 2θ is in the ranges of 30.50° to 32.49° and 32.50° to 34.50°.
8. A method for preparing the composite cathode active material according to any one of claims 1 to 7, the method comprising: Mixing a first lithium precursor and a nickel-based active material precursor for a lithium secondary battery to obtain a first mixture, the nickel-based active material precursor comprising 60 mol% or more of nickel, wherein the mixing molar ratio of lithium to the total metal other than lithium in the first mixture is in the range of 0.2 to 0.4; Performing a first heat treatment on the first mixture in an oxidizing gas atmosphere to obtain a nickel-based metal oxide; Obtain a second mixture comprising the nickel-based metal oxide and a second lithium precursor, wherein the mixing molar ratio of lithium to the total metal other than lithium in the second mixture is in the range of 0.8 to 1.2; Perform a second heat treatment on the second mixture in an oxidizing gas atmosphere to obtain a lithium-containing nickel-based active material, wherein the lithium-containing nickel-based active material comprises 60 mol% or more of nickel based on the total metal elements other than lithium of 100 mol% of the nickel-based active material; Mechanically grind a mixture comprising a lanthanide precursor and the lithium-containing nickel-based active material to obtain a grinding product; And Perform a third heat treatment on the grinding product at a temperature in the range of higher than 600 °C to lower than 1000 °C to prepare the composite cathode active material, wherein based on 100 parts by weight of the lithium-containing nickel-based active material, the amount of the lanthanide precursor is 0.001 part by weight to less than 0.01 part by weight.
9. The method according to claim 8, wherein the first heat treatment is performed at a temperature in the range of 600 °C to 1200 °C.
10. The method according to claim 8, wherein the second heat treatment is performed at a temperature in the range of 700 °C to 900 °C.
11. The method according to claim 8, wherein the third heat treatment is performed in an oxidizing gas atmosphere at a temperature in the range of 650 °C to 900 °C.
12. The method according to claim 8, wherein the nickel-based active material precursor is a compound represented by Formula 5, a compound represented by Formula 6, or any combination thereof: Formula 5 Ni 1-x-y-z What x Mn y M z (OH)2, Formula 6 Ni 1-x-y-z Co x Mn y M z O, and in, In Formula 5 and Formula 6, M is at least one element selected from the group consisting of boron, magnesium, calcium, strontium, barium, titanium, vanadium, chromium, iron, copper, zirconium, aluminum, and cerium, and 0.6 ≤ (1 - x - y - z) < 1, 0 < x < 0.4, 0 ≤ y < 0.4, and 0 ≤ z < 0.
4.
13. A method for preparing the composite cathode active material according to any one of claims 1 to 7, the method comprising: Mix a first lithium precursor and a nickel-based active material precursor for a lithium secondary battery to obtain a first mixture, wherein the nickel-based active material precursor comprises 60 mol% or more of nickel, and wherein the mixing molar ratio of lithium to the total metal other than lithium in the first mixture is in the range of 0.2 to 0.4; Perform a first heat treatment on the first mixture in an oxidizing gas atmosphere to obtain a nickel-based lithium metal oxide; Obtain a second mixture comprising the nickel-based lithium metal oxide, a second lithium precursor, and a lanthanide precursor, wherein the mixing molar ratio of lithium to the total metal other than lithium in the second mixture is in the range of 0.9 to 1.2; Perform a second heat treatment on the second mixture in an oxidizing gas atmosphere; and Mechanically grind the heat-treated second mixture to prepare the composite cathode active material, wherein based on 100 parts by weight of the nickel-based lithium metal oxide, the amount of the lanthanide precursor is 0.001 part by weight to 0.01 part by weight.
14. The method according to claim 13, wherein the first heat treatment is performed at a temperature in the range of 600 °C to 1200 °C.
15. The method according to claim 13, wherein the second heat treatment is carried out at a temperature in the range of 700 °C to 900 °C.
16. The method according to claim 13, wherein the nickel-based active material precursor is a compound represented by Formula 5, a compound represented by Formula 6, or any combination thereof: Formula 5 Ni 1-x-y-z What x Mn y M z (OH)2, Formula 6 Ni 1-x-y-z Co x Mn y M z O, and in, In Formula 5 and Formula 6, M is at least one element selected from the group consisting of boron, magnesium, calcium, strontium, barium, titanium, vanadium, chromium, iron, copper, zirconium, aluminum, and cerium, and 0.6 ≤ (1 - x - y - z) < 1, 0 < x < 0.4, 0 ≤ y < 0.4, and 0 ≤ z < 0.
4.
17. A positive electrode for a lithium secondary battery, the positive electrode comprising the composite positive electrode active material according to any one of claims 1 to 7 or the composite positive electrode active material prepared by the method according to any one of claims 8 to 16.
18. A lithium secondary battery, comprising: a positive electrode comprising the composite positive electrode active material according to any one of claims 1 to 7 or the composite positive electrode active material prepared by the method according to any one of claims 8 to 16; a negative electrode; and an electrolyte between the positive electrode and the negative electrode.