Method of preparing positive electrode material for lithium secondary battery, positive electrode material for lithium secondary battery, and lithium secondary battery including the positive electrode material

Patent metadata

Field	Value
Publication number	US-2016254546-A1
Application number	US-201514907990-A
Country	US
Kind code	A1
Filing date	Sep 10, 2015
Priority date	Sep 12, 2014
Publication date	Sep 1, 2016
Grant date	—

Abstract

The present invention relates to a method of preparing a positive electrode material for a lithium secondary battery including a first step of synthesizing a lithium transition metal oxide represented by Chemical Formula 1, a second step of preparing lithium transition metal oxide powder by grinding the lithium transition metal oxide, a third step of preparing a positive electrode material including an alumina coating layer by mixing as well as dispersing the lithium transition metal oxide powder in an alumina nanosol, and a fourth step of drying the positive electrode material, a positive electrode material for a lithium secondary battery prepared by the above method, and a lithium secondary battery including the positive electrode material,
Li (1+a) (Ni (1−a−b−c) Mn b Co c )O n   [Chemical Formula 1]
where 0≦a≦0.1, 0≦b≦1, 0<c≦1, and n is an integer of 2 or 4.

First claim

1 . A method of preparing a positive electrode material for a lithium secondary battery, the method comprising steps of:
a first step of synthesizing a lithium transition metal oxide represented by Chemical Formula 1; a second step of preparing lithium transition metal oxide powder by grinding the lithium transition metal oxide; a third step of preparing a positive electrode material including an alumina coating layer by mixing as well as dispersing the lithium transition metal oxide powder in an alumina nanosol; and a fourth step of drying the positive electrode material,
Li (1+a) (Ni (1−a−b−c) Mn b Co c )O n   [Chemical Formula 1]

where 0≦a≦0.1, 0≦b≦1, 0<c≦1, and n is an integer of 2 or 4.

2 . The method of claim 1 , wherein the alumina coating layer comprises a γ-alumina phase in an amount of 95 wt % or more based on a total weight of the alumina coating layer.

3 . The method of claim 1 , wherein the lithium transition metal oxide is Li(Ni 0.6 Mn 0.2 Co 0.2 O 2 ), Li(Ni 0.8 Mn 0.1 Co 0.1 O 2 ), Li(Ni 0.5 Mn 0.3 Co 0.2 O 2 ), Li(Ni 1/3 Mn 1/3 Co 1/3 O 2 ), or LiCoO 2 .

4 . The method of claim 1 , wherein a particle diameter of the lithium transition metal oxide powder ground in the second step is in a range of 10 μm to 30 μm.

5 . The method of claim 1 , wherein, in the third step, the lithium transition metal oxide powder and the alumina nanosol are mixed at a weight ratio of 1:80 to 1:100.

6 . The method of claim 1 , wherein, in the third step, the lithium transition metal oxide powder is directly dispersed in the alumina nanosol, or
is dispersed after a lithium transition metal oxide powder solution is prepared by spaying the lithium transition metal oxide powder in an organic solvent.

7 . The method of claim 6 , wherein the organic solvent is 1-methoxy-2-propanol, ethyl alcohol, methyl alcohol, or isopropyl alcohol.

8 . The method of claim 6 , wherein the organic solvent is used in an amount of 70 wt % to 99 wt % based on a total weight of the positive electrode material.

9 . The method of claim 1 , wherein the drying of the fourth step is performed in a temperature range of 100° C. to 350° C.

10 . The method of claim 1 , further comprising a fifth step of sintering the dried positive electrode material after the fourth step.

11 . The method of claim 10 , wherein the sintering of the fifth step is performed in a temperature range of 400° C. to 1200° C.

12 . A positive electrode material for a secondary battery, the positive electrode material comprising:
lithium transition metal oxide particles represented by Chemical Formula 1; and an alumina coating layer formed on surfaces of the lithium transition metal oxide particles and including a γ-alumina phase in an amount of 95% or more, wherein a coverage of the alumina coating layer is in a range of 30% to 50% based on a total surface area of the lithium transition metal oxide particles,
Li (1+a) (Ni (1−a−b−c) Mn b Co c )O n   [Chemical Formula 1]

where 0≦a≦0.1, 0≦b≦1, 0<c≦1, and n is an integer of 2 or 4.

13 . The positive electrode material for a secondary battery of claim 12 , wherein a thickness of the alumina coating layer is 30 nm or less.

14 . The positive electrode material for a secondary battery of claim 12 , wherein the alumina coating layer has a surface roughness (Ra) of 10 nm over an entire surface.

15 . The positive electrode material for a secondary battery of claim 12 , wherein an amount of aluminum in the alumina coating layer is in a range of 5 ppm to 100 ppm based on a total weight of the positive electrode material.

16 . A positive electrode for a secondary battery, the positive electrode comprising:
a positive electrode material; and selectively a conductive agent, a binder, and a filler in addition to the positive electrode material, wherein the positive electrode material comprises lithium transition metal oxide particles represented by Chemical Formula 1; and an alumina coating layer formed on surfaces of the lithium transition metal oxide particles and including a γ-alumina phase in an amount of 95% or more, wherein a coverage of the alumina coating layer is in a range of 30% to 50% based on a total surface area of the lithium transition metal oxide particles,
Li (1+a) (Ni (1−a−b−c) Mn b Co c )O n   [Chemical Formula 1]

where 0≦a≦0.1, 0≦b≦1, 0<c≦1, and n is an integer of 2 or 4.

17 . A lithium secondary battery comprising:
a positive electrode; a negative electrode; a separator disposed between the positive electrode and the negative electrode; and an electrolyte solution, wherein the positive electrode comprises a positive electrode material represented by Chemical Formula 2,
Li (1+a) (Ni (1−a−b−c) Mn b Co c M′ x )O n   [Chemical Formula 2]

where 0≦a≦0.1, 0≦b≦1, 0<c≦1, 0<x≦1, n is an integer of 2 or 4, and M′ is Al 2 O 3 having a gamma phase.

18 . The lithium secondary battery of claim 17 , wherein the lithium secondary battery has an HF content of 900 ppm or less based on a total weight of the electrolyte solution after an activation process and initial charge and discharge.

19 . The lithium secondary battery of claim 17 , wherein the lithium secondary battery has an HF content of 100 ppm or less based on a total weight of the electrolyte solution after 50 charge cycles.

20 . The lithium secondary battery of claim 17 , wherein the positive electrode comprises:
lithium transition metal oxide particles represented by Chemical Formula 1; and an alumina coating layer formed on surfaces of the lithium transition metal oxide particles and including a γ-alumina phase in an amount of 95% or more, wherein a coverage of the alumina coating layer is in a range of 30% to 50% based on a total surface area of the lithium transition metal oxide particles,
Li (1+a) (Ni (1−a−b−c) Mn b Co c )O n   [Chemical Formula 1]

where 0≦a≦0.1, 0≦b≦1, 0<c≦1, and n is an integer of 2 or 4.

21 . A method of preparing an alumina nanosol, the method comprising:
mixing alumina nanopowder and a solvent to prepare an alumina nanopowder suspension; and dispersing the suspension with a bead mill to prepare an alumina nanosol, wherein the alumina nanosol comprises a γ-alumina phase in an amount of 99% of more.

22 . The method of claim 21 , wherein the dispersion of the suspension with the bead mill is performed at a rotation speed of a center of 3,000 rpm.

23 . The method of claim 21 , wherein a diameter of beads in the bead mill is in a range of 0.05 mm to 0.1 mm.

24 . The method of claim 21 , wherein the solvent is 1-methoxy-2-propanol, ethyl alcohol, methyl alcohol, or isopropyl alcohol.

25 . The method of claim 21 , wherein the solvent is used in an amount of 70 wt % to 99 wt % based on a total amount of the alumina nanosol.

26 . The method of claim 21 , wherein a particle diameter of the alumina nanopowder is in a range of 1 nm to 50 nm.

27 . The method of claim 21 , wherein the alumina nanopowder is γ-alumina nanopowder.

28 . The method of claim 21 , wherein the alumina nanosol comprises alumina nanopowder having a particle diameter of 1 nm to 20 nm.

Assignees

• Lg Chemical Ltd

Inventors

• Kwak Ick Soon
• Cho Seung Beom
• Yoon Yeo June
• Mhin Sung Wook

Classifications

• H01M10/0568

  characterised by the solutes · CPC title

• H01M10/0585

  of accumulators having only flat construction elements, i.e. flat positive electrodes, flat negative electrodes and flat separators · CPC title

• B01J13/0047

  containing a metal oxide · CPC title

• H01M4/382

  Lithium (H01M4/405 takes precedence) · CPC title

• H01M2004/028

  Positive electrodes · CPC title