Positive electrode active material for lithium secondary battery, method for preparing the same, and secondary battery including the same

Patent metadata

Field	Value
Publication number	US-2018090782-A1
Application number	US-201615567228-A
Country	US
Kind code	A1
Filing date	Apr 27, 2016
Priority date	Apr 30, 2015
Publication date	Mar 29, 2018
Grant date	—

Abstract

The present invention relates to a positive electrode active material for a secondary battery, a method for preparing the same, and a secondary battery including the same, and more particularly to a positive electrode active material for a secondary battery, which includes lithium transition metal oxide particles represented by Formula 1; and lithium metal phosphate nanoparticles disposed on the surface of the lithium transition metal oxide particles and represented by Formula 2, a method for preparing the same, and a lithium secondary battery including the same.
Li (1+a) (Ni 1-b-c M b Co c )O 2   [Formula 1]

In which, M is at least one metal selected from the group consisting of Mn, Al, Cu, Fe, Mg, Cr, Sr, V, Sc and Y, 0≦a≦0.2, 0≦b≦1, and 0≦c≦1.
Li 1+x M′ x M″ 2-x (PO 4 ) 3   [Formula 2]

In which, M′ is Al, Y, Cr, or Ca, M″ is Ge, Ti, Sn, Hf, Zn, or Zr, and 0≦x≦0.5.

First claim

1 . A positive electrode active material for a secondary battery, the positive electrode active material comprising:
lithium transition metal oxide particles represented by the following Formula 1; and lithium metal phosphate nanoparticles disposed on a surface of the lithium transition metal oxide particles, the lithium metal phosphate nanoparticles being represented by the following Formula 2:
Li (1+a) (Ni 1-b-c M b Co c )O 2   [Formula 1]

where M is at least one metal selected from the group consisting of Mn, Al, Cu, Fe, Mg, Cr, Sr, V, Sc and Y, 0≦a≦0.2, 0≦b≦1, and 0≦c≦1,
Li 1+x M′ x M″ 2-x (PO 4 ) 3   [Formula 2]

where M′ is Al, Y, Cr, or Ca, M″ is Ge, Ti, Sn, Hf, Zn, or Zr, and 0≦x≦0.5.

2 . (canceled)

3 . The positive electrode active material for a secondary battery of claim 1 , wherein the lithium metal phosphate nanoparticles represented by Formula 2 has a NASICON structure.

4 . The positive electrode active material for a secondary battery of claim 1 , wherein the lithium metal phosphate nanoparticles represented by Formula 2 comprise at least one selected from the group consisting of LiTi 2 (PO 4 ) 3 , LiZr 2 (PO 4 ) 3 , Li 1+x Al x Ti 2-x (PO 4 ) 3 (0≦x≦0.5), Li 1+x Al x Zr 2-x (PO 4 ) 3 (0≦x≦0.5), and Li 1+x Y x Zr 2-x (PO 4 ) 3 (0≦x≦0.5).

5 . (canceled)

6 . The positive electrode active material for a secondary battery of claim 1 , wherein a lithium ion conductivity of the lithium metal phosphate nanoparticles at room temperature is from 1×10 −3 S/cm to 1×10 −5 S/cm.

7 . The positive electrode active material for a secondary battery of claim 1 , wherein an average particle diameter (D50) of the lithium metal phosphate nanoparticles is 200 nm or less.

8 . The positive electrode active material for a secondary battery of claim 7 , wherein an average particle diameter (D50) of the lithium metal phosphate nanoparticles is from 10 nm to 200 nm.

9 . The positive electrode active material for a secondary battery of claim 1 , wherein the lithium metal phosphate nanoparticles are comprised in an amount of 0.1 wt % to 2 wt % based on a total amount of the positive electrode active material.

10 . The positive electrode active material for a secondary battery of claim 9 , wherein the lithium metal phosphate nanoparticles are comprised in an amount of 0.3 wt % to 1 wt % based on a total amount of the positive electrode active material.

11 . (canceled)

12 . A method for preparing the positive electrode active material for a secondary battery according to claim 1 , the method comprising:
(a) synthesizing lithium metal phosphate nanoparticles represented by the following Formula 2; (b) dispersing the lithium metal phosphate nanoparticles in a dispersion solvent to prepare a coating solution; and (c) mixing the coating solution with lithium transition metal oxide particles to coat a surface of the lithium transition metal oxide particles with the lithium metal phosphate nanoparticles:
Li 1+x M′ x M″ 2-x (PO 4 ) 3   [Formula 2]

where M′ is Al, Y, Cr, or Ca, M″ is Ge, Ti, Sn, Hf, Zn, or Zr, and 0≦x≦0.5.

13 . The method for preparing the positive electrode active material for a secondary battery of claim 12 , further comprising a step of heat treating after coating.

14 . The method for preparing the positive electrode active material for a secondary battery of claim 12 , wherein step (a) for synthesizing the lithium metal phosphate nanoparticles comprises:
preparing a mixture solution by injecting a reaction solvent, a lithium precursor, a phosphor precursor, and at least two kinds of metal precursors into a reactor at an atmospheric pressure; stirring the mixture solution while elevating a temperature to 200° C.; and cooling the mixture solution after finishing a reaction to obtain the lithium metal phosphate nanoparticles.

15 . The method for preparing the positive electrode active material for a secondary battery of claim 14 , wherein the reaction solvent comprises a diol, a polyol, or a glycol solvent which contains at least two hydroxyl groups in a molecule.

16 . The method for preparing the positive electrode active material for a secondary battery of claim 15 , wherein the reaction solvent comprises any one selected from the group consisting of ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, glycerin, glycerol, diethyl glycol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, and 2,3-butanediol, or a mixture of at least two thereof.

17 . The method for preparing the positive electrode active material for a secondary battery of claim 14 , wherein the lithium precursor comprises any one selected from the group consisting of lithium acetate dihydrate, lithium hydroxide monohydrate, lithium hydroxide, lithium carbonate, lithium phosphate, lithium phosphate dodecahydrate, and lithium oxalate (Li 2 C 2 O 4 ), or a mixture of at least two thereof.

18 . The method for preparing the positive electrode active material for a secondary battery of claim 14 , wherein the phosphor precursor comprises any one selected from the group consisting of ammonium phosphate, phosphoric acid, tri-ammonium phosphate trihydrate, and ammonium dihydrogen phosphate, or a mixture of at least two thereof.

19 . The method for preparing the positive electrode active material for a secondary battery of claim 14 , wherein the at least two metal precursors comprise a mixture of at least two selected from the group consisting of an aluminum precursor, a titanium precursor, an yttrium precursor, and a zirconium precursor.

20 . The method for preparing the positive electrode active material for a secondary battery of claim 14 , wherein a molar ratio of the lithium precursor:the phosphor precursor:the at least two metal precursors is 1.1 to 1.5:3:0.6 to 2.5.

21 . The method for preparing the positive electrode active material for a secondary battery of claim 20 , wherein a molar ratio of the lithium precursor:the phosphor precursor:a first metal precursor:a second metal precursor is 1.1 to 1.5:3:0.1 to 0.55:0.5 to 1.95.

22 . (canceled)

23 . A positive electrode for a secondary battery, the positive electrode comprising the positive electrode active material for a secondary battery of claim 1 .

24 . A lithium secondary battery comprising:
a positive electrode comprising a positive electrode active material; a negative electrode comprising a negative electrode active material; a separator disposed between the positive electrode and the negative electrode; and a non-aqueous electrolyte, wherein the positive electrode comprises the positive electrode for a secondary battery of claim 23 .

Assignees

• Lg Chemical Ltd

Inventors

• Choi Ji Hoon
• Jun In Kook
• Cho Seung Beom

Classifications

• H01M4/58

  of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates · CPC title

• H01M4/525

  of mixed oxides or hydroxides containing iron, cobalt or nickel for inserting or intercalating light metals, e.g. LiNiO2, LiCoO2 or LiCoOxFy · CPC title

• H01M4/1391

  of electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx · CPC title

• H01M10/052 Primary

  Li-accumulators · CPC title

• G01N23/20075

  by measuring interferences of X-rays, e.g. Borrmann effect · CPC title