Search

EP-4071855-B1 - MIXED POSITIVE ELECTRODE MATERIAL, POSITIVE ELECTRODE PLATE AND PREPARATION METHOD THEREOF, BATTERY, AND APPARATUS

EP4071855B1EP 4071855 B1EP4071855 B1EP 4071855B1EP-4071855-B1

Inventors

  • BIE, Changfeng
  • HU, Xia
  • LIU, QIAN
  • LIU, Na
  • XU, Xiaofu
  • NI, Huan

Dates

Publication Date
20260506
Application Date
20200930

Claims (14)

  1. A mixed positive electrode material, comprising a mixed component consisting of a material of lithium iron phosphate chemical system and a material of ternary chemical system, the material of lithium iron phosphate chemical system being secondary particles with an average specific surface area between 3.5 and 6 m 2 /g, when determined as described in the application, wherein the material of ternary chemical system is a material of lithium nickel cobalt manganate chemical system and/or a material of lithium nickel cobalt aluminate chemical system, and a general formula of the material of lithium nickel cobalt manganate chemical system is LiNi x Mn y Co 1-x-y O 2 , wherein 1>x>0, 1>y>0, and x+y≤0.95; and a general formula of the material of lithium nickel cobalt aluminate chemical material system is LiNi x Co y Al 1-x-y O 2 , wherein 1>x>0.6 and 0.4>y>0.1.
  2. The mixed positive electrode material according to claim 1, wherein a particle size distribution of the secondary particles, when determined as described in the application, satisfies 0.1≤D v 50/(D v 90-D v 10)≤10; and/or the particle size distribution of the secondary particles, when determined as described in the application satisfies D v 10≥0.6 µm and D v 90≤30 µm.
  3. The mixed positive electrode material according to any one of claims 1 or 2, wherein a median particle size of the secondary particles satisfies 2 µm≤D v 50≤9 µm; and/or the median particle size of the secondary particles satisfies 3 µm≤D v 50≤6 µm.
  4. The mixed positive electrode material according to any one of claims 1 to 3, wherein an average particle size d of primary particles forming the secondary particles satisfies 20 nm≤d≤800 nm.
  5. The mixed positive electrode material according to any one of claims 1 to 4, wherein powder resistivity of the secondary particles of lithium iron phosphate chemical system, when determined as described in the application, is not more than 100 Ω·cm.
  6. The mixed positive electrode material according to any one of claims 1 to 5, wherein a percentage of the secondary particles of lithium iron phosphate chemical system is 20%-70% given that mass of the mixed component is 100%.
  7. The mixed positive electrode material according to claim 6, wherein the percentage of the secondary particles of lithium iron phosphate chemical system is 25%-45%.
  8. The mixed positive electrode material according to any one of claims 1 to 7, wherein in the mixed component: a general formula of the material of lithium iron phosphate chemical system is LiFe 1-x M x PO 4 , wherein 0<x≤0.1, and M is selected from one or more of Cu, Mn, Cr, Zn, Pb, Ca, Co, Ni, Sr, and Ti.
  9. A positive electrode plate, comprising a positive electrode material layer containing the mixed positive electrode material according to any one of claims 1 to 8.
  10. The positive electrode plate according to claim 9, wherein a mass per unit area of the positive electrode material layer is 150-250 g/m 2 , and/or a compacted density of the positive electrode material layer is 2.6-3.5 g/cm 3 .
  11. The positive electrode plate according to claim 9, wherein the positive electrode material layer further comprises a conductive agent and a binder, and a mass ratio of the mixed positive electrode material, the conductive agent, and the binder is (90-98):(1-5):(1-5).
  12. A preparation method of the positive electrode plate according to any one of claims 9 to 10, comprising the following steps: mixing the mixed positive electrode material according to any one of claims 1 to 8; filtering and collecting a slurry; applying the slurry onto a current collector; and removing a solvent and then performing rolling and cutting, to obtain a positive electrode plate.
  13. A battery, comprising the positive electrode plate according to any one of claims 9 to 11.
  14. An apparatus, comprising the battery according to claim 13, wherein the battery is configured to provide power for the apparatus and/or serve as an energy storage unit for the apparatus, and the apparatus is selected from one or more of an electric vehicle, an electric boat, an electric tool, an electronic device, or an energy storage system.

Description

TECHNICAL FIELD This application relates to the technical field of lithium-ion batteries, and in particular, to a mixed positive electrode material, a positive electrode plate and a preparation method thereof, a battery, and an apparatus. BACKGROUND Lithium-ion batteries are highly competitive in the field of secondary batteries due to their advantages such as high energy density, long cycle life, no memory effect, and environmental friendliness, widely used in terminal electronic products such as mobile phones and notebook computers with increasing application in fields such as electric vehicles and large-scale energy storage devices. As positive electrode materials for lithium-ion batteries, the more mature and commonly used materials are the lithium iron phosphate material system (such as lithium iron phosphate or doped lithium iron phosphate materials) and the ternary material system (such as lithium nickel cobalt manganate and lithium nickel cobalt aluminate system materials). Lithium-ion batteries with materials of the ternary system as their positive electrode active materials received attention of the industry and became a direction of research over a specific development period due to their higher energy density and better power performance. However, materials of both systems have their own strengths and weaknesses. As perception and research deepens, how to make use of their respective advantages has begun to attract attention. US 10 243 196 B2 discloses electrolyte secondary battery including a positive electrode mixture layer consisting of a first layer, the first layer contains lithium iron phosphate and lithium nickel cobalt manganese composite oxide. ETIEMBLE A ET AL: "Multiscale 1-15 morphological characterization of process induced heterogeneities in blended positive electrodes for lithium-ion batteries", JOURNAL OF MATERIAL SCIENCE, KLUWER ACADEMIC PUBLISHERS, DORDRECHT, vol. 52, no. 7, 14 September 2016 describes the morphological characterization of blended positive electrodes containing lithium iron phosphate and nickel cobalt manganese composite oxide. CN 109 411 716 A suggest a positive active material including a first active material and a second active material. The first active material comprises at least one of lithium manganate, lithium cobaltate, lithium iron phosphate and the second active material may be selected from NCM622 or NCM 811. However, how performance of lithium-ion batteries can be improved and stabilized to ensure their electrical performance and guarantee good processing during preparation has become one of the technical problems to be solved urgently. SUMMARY This application provides a mixed positive electrode material, by screening and reasonably matching types and microscopic morphologies of used materials, the problem that different types of materials are easy to agglomerate at mixing is resolved, so that the mixed positive electrode material has good miscibility and ease of processing, helping ensure improved safety performance and cycle life of lithium-ion batteries. This application further provides a positive electrode plate, which is prepared by using the mixed positive electrode material of this application, and able to improve uniform distribution of the positive electrode material on the positive electrode plate, and better satisfy electrochemical performance of lithium-ion batteries. This application further provides a preparation method of a positive electrode plate. The preparation method of this application uses the mixed positive electrode material of this application, which is able to improve uniform distribution of the positive electrode material on the positive electrode plate, improve performance of the electrode plate, and better satisfy electrochemical performance of lithium-ion batteries. This application further provides a battery using the positive electrode plate of this application, which has good electrochemical performance with increased energy density. This application further provides an apparatus including the battery of this application, where the battery is configured to provide power for the apparatus and/or serve as an energy storage unit of the apparatus. The following technical solutions are proposed in this application. This application provides a mixed positive electrode material, including a mixed component consisting of a material of lithium iron phosphate chemical system and a material of ternary chemical system, where the material of lithium iron phosphate chemical system is secondary particles of low specific surface area with an average specific surface area between 3.5 m2/g and 6 m2/g. The secondary particles of the lithium iron phosphate material used in this application should also be understood as material particles agglomerated due to processing. In a specific embodiment, the secondary particles may be secondary particles resulting from hard agglomeration of nanoscale primary particles of lithium iron phosphate