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US-12620591-B2 - Multi-element cathode material, preparation method thereof, positive electrode plate, and lithium-ion battery

US12620591B2US 12620591 B2US12620591 B2US 12620591B2US-12620591-B2

Abstract

The present disclosure relates to the technical field of lithium-ion batteries, and particularly, to a multi-element cathode material, a preparation method thereof, a positive electrode plate, and a lithium-ion battery. The multi-electrode material is composed of secondary particles agglomerated by primary particles. A ratio of a total cross-sectional area of the primary particles with more than 5 grain boundaries to a cross-sectional area of the secondary particles is greater than or equal to 3:4. A porosity on a cross-section of the secondary particles is less than or equal to 2%. A grain boundary is a contour line of an interface between the primary particles with the same structure but different orientations on the cross-section of the secondary particles and a length of the grain boundary is greater than or equal to 0.1 μm.

Inventors

  • Huawei JIANG
  • Shunlin SONG
  • Yafei Liu
  • Yanbin Chen

Assignees

  • BEIJING EASPRING MATERIAL TECHNOLOGY CO., LTD.

Dates

Publication Date
20260505
Application Date
20250613
Priority Date
20231025

Claims (19)

  1. 1 . A multi-element cathode material, wherein the multi-element cathode material is composed of secondary particles agglomerated by primary particles, wherein: a ratio of a total cross-sectional area of the primary particles with more than 5 grain boundaries to a cross-sectional area of the secondary particles is greater than or equal to 0.75 and less than 1; a porosity on a cross-section of the secondary particles is more than 0% and less than or equal to 2%; and the grain boundaries are each a contour line of an interface, on the cross-section of the secondary particles, between the primary particles with the same structure but different orientations, and the grain boundaries have each a length greater than or equal to 0.1 μm; the cross-section of the secondary particles refers to a cross-section of particles obtained by ion milling with a cross-sectional diameter equal to an average particle size DB 50 of the secondary particles.
  2. 2 . The multi-element cathode material according to claim 1 , wherein: the number of the grain boundaries having a length less than or equal to 1.5 μm accounts for more than 70% of the total number of the grain boundaries.
  3. 3 . The multi-electrode material according to claim 2 , wherein a grain boundary density of the secondary particles is greater than or equal to 1.8, wherein the grain boundary density is a ratio of the number of interfaces, on the cross-section of the secondary particles, between the primary particles to the number of the primary particles on the cross-section of the secondary particles.
  4. 4 . The multi-element cathode material according to claim 2 , wherein an average aspect ratio of the primary particles is less than or equal to 1.5.
  5. 5 . The multi-element cathode material according to claim 1 , wherein: an average particle size DB 50 of the secondary particles and an average particle size DA 50 of the primary particles satisfy: 10≤DB 50 /DA 50 ≤40.
  6. 6 . The multi-element cathode material according to claim 1 , wherein the multi-electrode cathode material has a composition represented by Formula I: where 1≤a≤1.2, 0<b≤0.05, 0≤c<0.05, 0.3≤x<1,0<y<0.5, 0<<<0.5, andx+y+z+b=1; and M and G are each independently selected from at least one element of Mg, Ti, W, V, Ta, Zr, La, Ce, Er, Sr, Si, B, Al, Co, and Y.
  7. 7 . The multi-element cathode material according to claim 1 , wherein: in an X-ray diffraction, XRD, pattern, the multi-element cathode material has a characteristic diffraction peak of a (104) crystal plane, a full width at half maximum FWHM (104) of the characteristic diffraction peak of the (104) crystal plane ranging from 0.2 to 0.24; and the multi-electrode cathode material has a single-layered α-NaFeO 2 type structure.
  8. 8 . The multi-element cathode material according to claim 1 , wherein: a total residual alkali content of the multi-element cathode material satisfies: 0 ppm<m(Li 2 CO 3 )+m(LiOH)<6000 ppm.
  9. 9 . A method for preparing a multi-element cathode material according to claim 1 , the method comprising: step 1 of mixing a precursor having a composition represented by Formula (II) with a lithium source to obtain a mixture I, the precursor being agglomerated by primary crystal grains, and the primary crystal grains on a cross-section of the precursor being non-radially distributed; step 2 of performing a primary sintering on the mixture I in an oxygen-containing atmosphere to obtain an intermediate product, conditions for the primary sintering comprising: heating to a temperature T1=400° C. to 760° C. at a heating rate V1=1° C./min to 6° C./min and holding at the temperature T1 for a thermostatic duration t1; and heating to a temperature T2=710° C. to 950° C. at a heating rate V2=1° C./min to 6° C./min and holding at the temperature T2 for a thermostatic duration t2; step 3 of mixing the intermediate product with a coating agent optionally containing G to obtain a mixture II; and step 4 of performing a secondary sintering on the intermediate product or the mixture II in an oxygen-containing atmosphere to obtain the multi-element cathode material, wherein: in terms of metallic elements, when a nickel content in the precursor is greater than or equal to 60 mol %, an oxygen concentration in the oxygen-containing atmosphere is greater than or equal to 92 vol %; (Ni α Co β Mn γ M δ )(OH) 2 (II), where: 0.3<α<1, 0<β<0.5, 0<γ<0.5, 0≤δ≤0.05, and α+β+γ+8=1; and M and G are each independently selected from at least one element of Mg, Ti, W, V, Ta, Zr, La, Ce, Er, Sr, Si, B, Al, Co, and Y.
  10. 10 . The method according to claim 9 , wherein: in step (1), a D 50 of the precursor ranges from 8 μm to 14 μm; a specific surface area of the precursor ranges from 3 m 2 /g to 7 m 2 /g; amounts of the precursor and the lithium source satisfy: n(Ni+Co+Mn+M):n(Li)=1:1 to 1.2; and the precursor is prepared by: contacting, in an inert atmosphere, a mixed metallic salt solution containing a nickel source, a cobalt source, a manganese source, and an optional dopant containing M with a precipitant, a complexing agent, and a dispersant for a coprecipitation reaction to obtain a coprecipitation reaction product, and sequentially performing washing and drying on the obtained coprecipitation reaction product to obtain the precursor.
  11. 11 . The method according to claim 10 , wherein conditions for the coprecipitation reaction comprise: a temperature ranging from 40° C. to 80° C., a pH value ranging from 10 to 13, and a stirring speed ranging from 200 rpm to 550 rpm.
  12. 12 . The method according to claim 10 , wherein in the mixed metallic salt solution, amounts of the nickel source, the cobalt source, the manganese source, and the dopant satisfy n(Ni):n(Co):n(Mn):n(M), where: 0.3≤n(Ni)<1, 0<n(Co)<0.5, 0<n(Mn)<0.5, and 0≤n(M)≤0.05.
  13. 13 . The method according to claim 9 , wherein in step (2), conditions for the primary sintering comprise: the heating rate V1 ranging from 1° C./min to 3° C./min; the temperature T1 ranging from 500° C. to 750° C.; and the thermostatic duration t1 ranging from 2 hours to 6 hours; and the heating rate V2 ranging from 1° C./min to 3° C./min; the temperature T2 ranging from 710° C. to 920° C.; and the thermostatic duration t2 ranging from 5 hours to 13 hours.
  14. 14 . The method according to claim 9 , wherein in step (3), amounts of the intermediate product and the coating agent satisfy n(Ni+Co+Mn+M):n(G)=1: n(G), where 0≤n(G)≤0.05.
  15. 15 . The method according to claim 14 , wherein the coating agent is selected from at least one of oxide, hydroxide, and carbonate that contain G.
  16. 16 . The method according to claim 14 , wherein in step (4), conditions for the secondary sintering comprise: a temperature T3 ranging from 300° C. to 800° C.; and a duration t3 ranging from 4 hours to 10 hours.
  17. 17 . The method according to claim 9 , wherein in step ( 4 ), the multi-element cathode material has a composition represented by Formula I: Li a (Ni x Co y Mn z M b )G c O 2 (I), where 1≤a≤1.2, 0<b≤0.05, 0≤c≤0.05, 0.3≤x<1, 0<y<0.5, 0<z<0.5, and x+y+z+b=1; and M and G are each independently selected from at least one element of Mg, Ti, W, V, Ta, Zr, La, Ce, Er, Sr, Si, B, Al, Co, and Y.
  18. 18 . A positive electrode plate, wherein an active material layer of the positive electrode plate comprises the multi-element cathode material according to claim 1 .
  19. 19 . A lithium-ion battery, comprising the positive electrode plate according to claim 18 .

Description

PRIORITY INFORMATION This application is a continuation of International Application No. PCT/CN2024/091055, filed on Apr. 30, 2024, which claims priority to and benefits of Chinese Patent Application No. 202311394203.9, filed with China National Intellectual Property Administration on Oct. 25, 2023. The disclosures of the aforementioned applications are hereby incorporated by reference in their entireties. FIELD The present disclosure relates to the technical field of lithium-ion batteries, and particularly, to a multi-element cathode material, a preparation method thereof, a positive electrode plate including the multi-element cathode material, and a lithium-ion battery including the positive electrode plate. BACKGROUND Lithium-ion batteries are mainly classified into cylindrical, prismatic, and pouch types. From small consumer products to power tools, and even in power batteries including energy storage, lithium-ion batteries have a wide range of application fields. Precisely due to strong demand, an output of the lithium-ion batteries has witnessed rapid growth, and manufacturing technologies thereof have advanced by leaps and bounds. The manufacturing process of the lithium-ion batteries is relatively complicated, typically including steps such as homogenizing of the cathode material, coating, rolling, cutting, electrolyte injecting, and winding. Therefore, it is very important whether the cathode material can maintain sufficient stability in each manufacturing step. In the actual production process of lithium battery, manufacturers tend to increase the amount of the cathode material or apply a greater pressure in the rolling step in order to pursue the energy density of the lithium-ion batteries. However, the excessive pressure is likely to cause a phenomenon of fracture of the positive electrode plate, resulting in scrapping of the plate, and ultimately leading to a relatively high defect rate of the batteries. From the perspective of performance of the cathode material, the occurrence of the fracture of the plate is largely related to the structure of the cathode material itself. Generally speaking, when designing the cathode material, the material is consciously designed to have a radial distribution in its cross-section in order to improve its cycle performance. However, during a process of manufacturing a battery plate, when a relatively large rolling pressure is applied to obtain a sufficient energy density, such cathode material will conduct the applied pressure along the radial direction to the aluminum foil plate coated with the cathode. The same direction of pressure, when amplified, is extremely easy to cause the fracture of the plate, which greatly increase a defect rate of the battery plate. This phenomenon will also affect electrical performance of the battery, especially the safety performance, high-temperature stability, and cycle performance of the battery, failing to meet the requirements of high safety for electric vehicle batteries. SUMMARY The object of the present disclosure is to overcome the problems that the existing battery plates are prone to fracture and cannot withstand a high rolling pressure, and the batteries assembled therefrom have low safety performance, low high-temperature stability, and low cycle performance, etc, and provide a multi-element cathode material, a preparation method thereof, a positive electrode plate, and a lithium-ion battery. The internal crystal grains of the multi-element cathode material are arranged in an irregular, non-radial, and disordered manner, endowing the multi-element cathode material with a higher powder pallet density and improved processability. Meanwhile, the positive electrode plate including the multi-element cathode material can easily withstand a higher rolling pressure and is less prone to fracture. In order to achieve the above object, a first aspect of the present disclosure provides a multi-element cathode material. The multi-element cathode material is composed of secondary particles agglomerated by primary particles. A ratio of a total cross-sectional area of the primary particles with more than 5 grain boundaries to a cross-sectional area of the secondary particles is greater than or equal to 3:4, and a porosity on a cross-section of the secondary particles is less than or equal to 2%. The grain boundaries are each a contour line of an interface, on the cross-section of the secondary particles, between the primary particles with the same structure but different orientations, and the grain boundaries have each a length greater than or equal to 0.1 μm. In the present disclosure, unless otherwise specified, the cross-section of the secondary particles refers to a cross-section obtained by ion milling, preferably a cross-section of particles obtained by ion milling with a cross-sectional diameter equal to an average particle size DB50 of the secondary particles. In the present disclosure, a method for obtaining the cross-sec