Positive electrode composite material, preparation method thereof and lithium ion battery

A composite material and positive electrode technology, which is applied in the field of positive electrode composite materials and its preparation, can solve the problems of reducing the structural stability of LMFP, reducing battery cycle performance, and intensifying the dissolution of manganese element, so as to improve structural stability, high structural stability, The effect of good rate performance

Pending Publication Date: 2022-05-03
BYD CO LTD
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  • Application Information

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Problems solved by technology

However, in the actual preparation process of the battery, there will inevitably be a certain amount of water in the electrolyte, which will cause the hydrolysis of lithium salts such as lithium hexafluorophosphate in the electrolyte and generate HF in the electrolyte, which will aggravate the manganese in LMFP. The dissolution of elements (especially when the molar ratio of Mn to the sum of Mn and Fe is above 65%) will reduce the structural stability of LMFP and reduce the battery cycle performance

Method used

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  • Positive electrode composite material, preparation method thereof and lithium ion battery
  • Positive electrode composite material, preparation method thereof and lithium ion battery
  • Positive electrode composite material, preparation method thereof and lithium ion battery

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preparation example Construction

[0036] Correspondingly, the present application also provides a method for preparing a positive electrode composite material to prepare the above positive electrode composite material. Wherein, the preparation method comprises:

[0037] S01, dispersing the lithium manganese iron phosphate material, the high-nickel ternary material and the first conductive agent in a solvent to obtain a mixed material;

[0038] S02, performing fusion treatment on the mixed material in a mechanical fusion machine, and then drying treatment to obtain the positive electrode composite material.

[0039] Optionally, in step S01, the solvent can be N-methylpyrrolidone (NMP), dimethylformamide (DMF), dimethyl sulfoxide (DMSO), acetone, absolute ethanol, isopropanol, etc. One or more, but not limited to.

[0040] Optionally, in step S02, the rotational speed of the mechanical fusion machine is 4000-7000r / min, preferably 4500-6500r / min.

[0041] Optionally, the time for the fusion treatment is 10-30 ...

Embodiment 1

[0063] A kind of positive electrode composite material, comprises LMFP material and the covering layer that is coated on the surface of LMFP material, and wherein, covering layer comprises ternary material NCX, the half peak of (003) crystal plane diffraction peak in the XRD pattern of this ternary material Width≤0.09°; the cladding layer is also doped with a first conductive agent. Wherein, the parts by weight of LMFP, NCX and the first conductive agent are as shown in Table 1, the L of the first conductive agent 1 It is a times the D50 particle size of the LMFP material, and the value of a is shown in Table 1.

[0064] According to the parameters provided in Table 1, positive electrode composite materials of other embodiments were provided respectively.

[0065] Preparation of positive electrode sheet: Add a certain proportion of organic solvent NMP and binder PVDF into the mixer, stir for 1 hour, and then add conductive agent (specifically carbon tube, carbon black, carbon...

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Abstract

The invention provides a positive electrode composite material which comprises a lithium manganese iron phosphate material and a coating layer coating the surface of the lithium manganese iron phosphate material, the coating layer comprises a high-nickel ternary material, and the half-peak width of a (003) crystal face diffraction peak in an XRD spectrum of the high-nickel ternary material is smaller than or equal to 0.09 degree; the coating layer is further doped with a linear and / or planar first conductive agent, the linear first conductive agent comprises at least one of carbon fibers and carbon nanotubes, and the planar first conductive agent comprises at least one of graphene and graphite microchips. Through the arrangement of the high-nickel ternary material coating layer and the first conductive agent, the manganese dissolving phenomenon of the lithium manganese iron phosphate material is effectively improved, the structural stability is improved, and the conductivity is improved under the condition that the compaction density of a pole piece is not reduced. The invention also provides a preparation method of the positive electrode composite material, a positive plate and a lithium ion battery.

Description

technical field [0001] The present application relates to the technical field of lithium-ion batteries, in particular to a positive electrode composite material, a preparation method thereof, and a lithium-ion battery. Background technique [0002] As an important part of lithium-ion batteries, the choice of cathode materials directly affects the performance of lithium-ion batteries. Lithium manganese iron phosphate (LMFP for short) has become the mainstream cathode material for lithium-ion batteries due to its high potential, high safety, and high cycle performance stability. However, in the actual preparation process of the battery, there will inevitably be a certain amount of water in the electrolyte, which will cause the hydrolysis of lithium salts such as lithium hexafluorophosphate in the electrolyte and generate HF in the electrolyte, which will aggravate the manganese in LMFP. The dissolution of elements (especially when the molar ratio of Mn to the sum of Mn and Fe...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M4/36H01M4/485H01M4/505H01M4/525H01M4/58H01M4/62H01M4/04H01M4/131H01M10/0525
CPCH01M4/366H01M4/5825H01M4/625H01M4/505H01M4/525H01M4/485H01M4/04H01M4/0471H01M4/131H01M10/0525
Inventor 陈娜郝嵘潘仪
Owner BYD CO LTD
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