Lithium manganese iron phosphate positive electrode active material and preparation method, positive electrode plate, secondary battery and electrical apparatus thereof

Patent metadata

Field	Value
Publication number	US-12589999-B2
Application number	US-202318474567-A
Country	US
Kind code	B2
Filing date	Sep 26, 2023
Priority date	Jul 15, 2022
Publication date	Mar 31, 2026
Grant date	Mar 31, 2026

Abstract

A lithium manganese iron phosphate positive electrode active material, preparation method, a positive electrode plate, a secondary battery and an electrical apparatus are disclosed. The method comprises: mixing and grinding an iron source, a solid base and optionally a source of doping element M After grinding, impurities are removed to obtain a nanoscale iron-containing oxide; mixing the obtained nanoscale iron-containing oxide with a solvent, a lithium source, a manganese source, a phosphorus source, optionally a source of doping element N, optionally a source of doping element Q and optionally a source of doping element R in a predetermined ratio and then grinding. After grinding, granulating to obtain a powder; and sintering the powder to obtain the lithium manganese iron phosphate positive electrode active material. A lithium manganese iron phosphate positive electrode active material having both good electrochemical performance and high tap density can be obtained.

First claim

The invention claimed is:

1 . A preparation method for a manganese iron lithium phosphate cathode active material comprises the following steps:
S 1 , preparing a nano-sized iron oxide by low-temperature solid-phase reaction: mix an iron source, a solid base and a doping element M source (if any) for 20 min to 60 min to cause a low-temperature solid phase reaction among the components; after a mixing and grinding, let it stand to ensure the complete low-temperature solid-phase reaction; wash and remove impurities from the obtained product and dry it at a temperature below 100° C. to obtain nano-sized iron oxide, where the doping element M represents the doping element at the manganese and iron sites; S 2 , spray drying granulation: mix the nano-sized iron oxide in S 1 with a solvent, a lithium source, a manganese source, a phosphorus source, a doping element N source (if any), a doping element Q source (if any), and a doping element R source (if any) in a predetermined portion and grind them; after the grinding is completed, spray dry and granulate to obtain powder, wherein the doping element N represents the doping element at the lithium site, the doping element Q represents the doping element at the phosphorus site, and the doping element R represents the doping element at the oxygen site; S 3 , sintering, which includes the steps: S 31 , pre-sintering the powder obtained in S 2 at 350° C. to 550° C. in an air atmosphere or a protective gas atmosphere, and after the reaction, obtain the pre-sintered material; S 32 , grinding the pre-sintered material obtained in S 31 and spray dry granulate to obtain pre-sintered material powder; S 33 , sintering the pre-sintered material powder obtained in S 32 at 650° C. to 750° C. in a protective gas atmosphere to obtain the phosphorus manganese iron lithium phosphate cathode active material, where the molar ratio of the iron source to the solid base is 1:(1-3), the washing and impurity removal process includes water washing and alcohol washing, the solvent includes ethanol, water or their mixed solvents.

2 . The preparation method as claimed in claim 1 , wherein in S 1 ,
the drying is vacuum drying; the drying time is 2 h to 15 h.

3 . The preparation method as claimed in claim 1 , wherein in S 1 , the mixing and grinding is carried out in a mortar or ball mill container,
the grinding speed of the mortar is 100 r/min; the rotation speed of the ball mill is 300 r/min to 800 r/min.

4 . The preparation method as claimed in claim 1 , wherein in S 1 , the standing time is 30 min to 120 min.

5 . The preparation method as claimed in claim 1 , wherein in S 1 , a surface active agent is added together with the iron source, the solid base and the doping element M source for mixing and grinding,
the surface active agent includes polyethylene glycol; the addition amount of the surface active agent is less than 5% by weight based on the total weight of the iron source, the solid base and the doping element M source.

6 . The preparation method as claimed in claim 1 , wherein in S 1 , before the mixing and grinding of the iron source, the solid base and the doping element M source to cause the components to undergo a low-temperature solid-phase reaction, there is a step: grinding the iron source, the solid base and the doping element M source separately,
the grinding time of the iron source is 30 min to 90 min; the grinding time of the solid base is 30 min to 90 min; the grinding time of the doping element M source is 30 min to 90 min.

7 . The preparation method as claimed in claim 1 , wherein in S 1 ,
the iron source is a trivalent iron salt; the solid base includes sodium hydroxide, potassium hydroxide, sodium carbonate and potassium carbonate among other; the source of the dopant element M includes at least one of the hydrochlorate, nitrate, sulfate and acetate of the dopant element M.

8 . The preparation method as claimed in claim 1 , wherein in S 2 ,
the grinding is carried out in a ball mill container, the ball mill speed is 300 r/min to 800 r/min, and the grinding time is 3 h to 24 h; the spray drying temperature is 200° C. to 250° C.

9 . The preparation method as claimed in claim 1 , wherein in S 2 ,
the lithium source includes at least one of Li2CO3, LiOH, Li3PO4 and LiH2PO4; the manganese source includes at least one of MnCO3, Mn(CH3COO)2 and MnC2O4; the phosphorus source includes at least one of (NH4)2HPO4, NH4H2PO4, (NH4)3PO4 and H3PO4; the dopant element N's source includes at least one of the hydrochlorate, nitrate, sulfate and acetate of the dopant element N; the dopant element Q's source includes at least one of the sulfate, borate, nitrate and silicate of the dopant element Q; the dopant element R's source includes at least one of the elemental form and ammonium salt of the dopant element R.

10 . The preparation method as claimed in claim 1 , wherein in S 2 , a carbon source is also added for mixed grinding, and the carbon source includes at least one of organic carbon source and inorganic carbon source.

11 . The preparation method as claimed in claim 1 , wherein,
in S 31 , the low-temperature pre-sintering time is 2 h to 10 h; in S 33 , the high-temperature sintering time is 2 h to 10 h.

12 . The preparation method as claimed in claim 1 , in step S 32 , the grinding is carried out in a ball mill, with the ball mill rotation speed ranging from 300 r/min to 800 r/min, and the grinding time being from 3 h to 24 h.

13 . The preparation method as claimed in claim 1 , the following step in also included:
the obtained manganese iron lithium phosphate positive electrode active material in step S 3 is crushed to the desired particle size, and the crushing is carried out by air jet crushing.

14 . The preparation method as claimed in claim 1 , the positive electrode active material of the lithium manganese iron phosphate has the chemical formula LiaNbFexMnyM1-x-yP1-mQmO4-nRn; the doping element M represents the doping element at the manganese and iron sites, the doping element N represents the doping element at the lithium site, the doping element Q represents the doping element at the phosphorus site, and the doping element R represents the doping element at the oxygen site; the value of a is from 0.9 to 1.1, the value of b is from 0 to 0.1, the value of x is from 0.001 to 0,999, the value of y is from 0.001 to 0.999, the value of 1-x-y is from 0 to 0.1, the value of m is from 0 to 0.1, and the value of n is from 0 to 0.1; the positive electrode active material of the lithium manganese iron phosphate is electrically neutral and the bulk density of the positive electrode active material of the lithium manganese iron phosphate is above 1.4 g/cm 3 .

15 . The preparation method as claimed in claim 14 , wherein,
the volume average particle size Dv50 of the positive electrode active material of the lithium manganese iron phosphate is 300 nm to 500 nm; the positive electrode active material of the lithium manganese iron phosphate has a spherical or quasi-spherical single crystal morphology.

Assignees

• Contemporary Amperex Technology Hong Kong Ltd
• Contemporary Amperex Technology Co Ltd

Inventors

• Liu Shaojun
• Zhan Wenwei
• Zhang Xinxin
• Ouyang Chuying
• Li Qingzheng

Classifications

• C01P2006/40

  Electric properties · CPC title

• C01P2004/62

  Submicrometer sized, i.e. from 0.1-1 micrometer · CPC title

• C01P2006/11

  Powder tap density · CPC title

• C01P2004/03

  obtained by SEM · CPC title

• H01M10/052 Primary

  Li-accumulators · CPC title