Modified positive electrode active material, method for preparing the same and electrochemical energy storage device

Patent metadata

Field	Value
Publication number	US-2019044135-A1
Application number	US-201715577290-A
Country	US
Kind code	A1
Filing date	Aug 24, 2017
Priority date	May 15, 2017
Publication date	Feb 7, 2019
Grant date	—

Abstract

The disclosure provides a modified positive electrode active material, a preparation method thereof, and an electrochemical energy storage device. The modified positive electrode active material comprises positive electrode active material substrate; first oxide layer, coated on the surface of the positive electrode active material substrate and selected from one or more of oxides of element M being selected from the group of one or more of Li, Al, Zr, Mg, Ti, Y, Si, Ca, Cr, Fe, Zn, Nb, Sn, Ba, and Cd; and second oxide layer having a continuous layered structure, coated on the surface of the first oxide layer and selected from one or more of oxides of element M′ being selected from one or more of Li, B, P, As, Pb, V, Mo, and Sn. High temperature storage performance and cycling performance of electrochemical energy storage device are improved by the modified positive electrode active material.

First claim

1 . A modified positive electrode active material, comprising:
a positive electrode active material substrate; a first oxide layer, coated on the surface of the positive electrode active material substrate and selected from one or more of oxides of element M, wherein the element M is selected from the group of one or more of Li, Al, Zr, Mg, Ti, Y, Si, Ca, Cr, Fe, Zn, Nb, Sn, Ba, and Cd; and a second oxide layer having a continuous layered structure, coated on the surface of the first oxide layer and selected from one or more of oxides of element M′, wherein the element M′ is selected from one or more of Li, B, P, As, Pb, V, Mo, and Sn; said first oxide layer is different from said second oxide layer in terms of composition.

2 . The modified positive electrode active material according to claim 1 , wherein based on the mass of the positive electrode active material substrate, the element M is present in an amount of 0.01% to 2% in the first oxide layer and the element M′ is present in an amount of 0.01% to 1% in the second oxide layer.

3 . The modified positive electrode active material according to claim 1 , wherein the first oxide layer coated on the surface of the positive electrode active material substrate has an island-like or continuous island shape.

4 . The modified positive electrode active material according to claim 1 , wherein the positive electrode active material substrate is selected from the group consisting of one or more of lithium cobalt oxide, lithium iron phosphate, lithium manganese oxide, lithium-nickel-manganese-cobalt-based oxide ternary material, lithium-nickel-cobalt-aluminum-based oxide ternary material.

5 . The modified positive electrode active material according to claim 1 , wherein the positive electrode active material substrate comprises primary particles and secondary particles formed by agglomeration of primary particles; and wherein the primary particles have a particle diameter of 0.2 μm to 1 μm and the secondary particles have a particle diameter of 5 μm to 18 μm.

6 . A method for preparing the modified positive electrode active material according to claim 1 , comprising the steps of:
(i) mixing homogeneously a positive electrode active material substrate with first oxide layer substance itself or the precursor thereof, followed by sintering, to coat the surface of the positive electrode active material substrate with the first oxide layer selected from one or more of the oxides of element M, wherein the element M is selected from the group consisting of one or more of Li, Al, Zr, Mg, Ti, Y, Si, Ca, Cr, Fe, Zn, Nb, Sn, Ba, and Cd; (ii) mixing homogeneously the substance obtained in step (i) with second oxide layer substance itself or the precursor thereof, followed by sintering, so that the formed second oxide layer is coated on the surface of the first oxide layer and has a continuous layered structure, wherein the second oxide layer is selected from one or more of the oxides of element M′ and the element M′ is selected from one or more of Li, B, P, As, Pb, V, Mo, and Sn, thus yielding the modified positive electrode active material; wherein said first oxide layer is different from said second oxide layer in terms of composition.

7 . The method for preparing the modified positive electrode active material according to claim 6 , wherein melting point of the first oxide layer substance is higher than melting point of the precursor of the second oxide layer substance, so that the second oxide layer after sintering is uniformly coated on the surface of the first oxide layer; and wherein the formed second oxide layer has a continuous layered structure.

8 . The method for preparing the modified positive electrode active material according to claim 6 , wherein melting point of the first oxide layer substance is higher than melting point of the second oxide layer substance itself, so that the second oxide layer after sintering is uniformly coated on the surface of the first oxide layer; and wherein the formed second oxide layer has a continuous layered structure.

9 . The method for preparing the modified positive electrode active material according to claim 7 , wherein
the temperature of sintering in step (ii) is lower than that in step (i) and is equal to or greater than the melting point of the precursor of the second oxide layer substance; the temperature of sintering in step (i) is 600° C. to 750° C.; the temperature of sintering in step (ii) is 400° C. to 600° C.

10 . The method for preparing the modified positive electrode active material according to claim 8 , wherein
the temperature of sintering in step (ii) is lower than that in step (i) and is equal to or greater than the melting point of the second oxide layer substance itself; the temperature of sintering in step (i) is 600° C. to 750° C.; the temperature of sintering in step (ii) is 400° C. to 600° C.

11 . An electrochemical energy storage device, comprising the modified positive electrode active material according to claim 1 .

Assignees

• Contemporary Amperex Technology Co Ltd

Inventors

• Du Rui
• Liu Na
• Liu Yongchao
• Wang Sihui
• Xu Zhongling
• Yang Chao

Classifications

• H01M4/5825

  Oxygenated metallic salts or polyanionic structures, e.g. borates, phosphates, silicates, olivines · CPC title

• H01M4/505 Primary

  of mixed oxides or hydroxides containing manganese for inserting or intercalating light metals, e.g. LiMn2O4 or LiMn2OxFy · CPC title

• H01M4/0471

  involving thermal treatment, e.g. firing, sintering, backing particulate active material, thermal decomposition, pyrolysis · CPC title

• H01M2004/028

  Positive electrodes · CPC title

• H01M4/485

  of mixed oxides or hydroxides for inserting or intercalating light metals, e.g. LiTi2O4 or LiTi2OxFy (H01M4/505, H01M4/525 take precedence) · CPC title