Positive electrode active material for lithium ion secondary battery, manufacturing method thereof, and lithium ion secondary battery

Patent metadata

Field	Value
Publication number	US-2016118648-A1
Application number	US-201514873773-A
Country	US
Kind code	A1
Filing date	Oct 2, 2015
Priority date	Oct 20, 2014
Publication date	Apr 28, 2016
Grant date	—

Abstract

A compound having a layered structure that is used for a positive electrode active material for a lithium ion secondary battery achieves both a high energy density and a high cyclability. The positive electrode active material for a lithium ion secondary battery contains a compound having a layered structure belonging to a space group R-3m, in which the compound having a layered structure is represented by a compositional formula: Li 1+a M1O 2+α wherein M1 represents a metal element or metal elements other than Li, and contains at least Ni, −0.03≦a≦0.10, and −0.1<α<0.1, a proportion of Ni in M1 is larger than 70 atom %, and a site occupancy of a transition metal or transition metals at a 3a site obtained by structural analysis by a Rietveld method is less than 2%, and a content of residual lithium hydroxide in the positive electrode active material is 1 mass % or less.

First claim

What is claimed is:

1 . A positive electrode active material for a lithium ion secondary battery, comprising a compound having a layered structure belonging to a space group R-3m,
wherein the compound having a layered structure is represented by a compositional formula:
Li 1+a M1O 2+α

wherein M1 represents a metal element or metal elements other than Li, and comprises at least Ni, −0.03≦a≦0.10, and −0.1<α<0.1, a proportion of Ni in M1 is larger than 70 atom %, and a site occupancy of a transition metal or transition metals at a 3a site obtained by structural analysis by a Rietveld method is less than 2%, and
a content of residual lithium hydroxide in the positive electrode active material is 1 mass % or less.

2 . The positive electrode active material for a lithium ion secondary battery according to claim 1 , wherein the compound having a layered structure is represented by a compositional formula:
Li 1+a M1O 2+α
wherein M1 represents a metal element or metal elements other than Li, and comprises at least Ni, 0≦a≦0.10, and −0.1<α<0.1.

3 . The positive electrode active material for a lithium ion secondary battery according to claim 1 , wherein the compound having a layered structure is represented by a compositional formula:
Li 1+a Ni b Mn c Co d M2 e O 2+α
wherein M2 represents a metal element other than Li, Ni, Mn, and Co, −0.03≦a≦0.10, 0.7<b<1.0, 0<c0.3, 0<d<0.3, 0≦e<0.1, b+c+d+e=1, and −0.1<α<0.1.

4 . The positive electrode active material for a lithium ion secondary battery according to claim 3 , wherein the compound having a layered structure is represented by a compositional formula:
Li 1+a Ni b Mn c Co d M2 c O 2+α
wherein M2 represents a metal element other than Li, Ni, Mn, and Co, 0≦a≦0.10, 0.7<b<1.0, 0<c<0.3, 0<d<0.3, 0≦e<0.1, b+c+d+e=1, and −0.1<α<0.1.

5 . The positive electrode active material for a lithium ion secondary battery according to claim 1 , comprising a secondary particle formed by aggregation and bonding of a plurality of primary particles, wherein the primary particles have an average particle diameter of less than 1 μm, and the secondary particle has an average particle diameter of larger than 1 μm.

6 . The positive electrode active material for a lithium ion secondary battery according to claim 4 , comprising a secondary particle formed by aggregation and bonding of a plurality of primary particles, wherein the primary particles have an average particle diameter of less than 1 μm, and the secondary particle has an average particle diameter of larger than 1 μm.

7 . A manufacturing method of the positive electrode active material for a lithium ion secondary battery according to claim 1 , the method comprising:
a pulverizing and mixing step of pulverizing and mixing a raw material comprising a metal element other than Li with a lithium raw material comprising 80 mass % or more of lithium carbonate so as to make an average particle diameter of the raw material and the lithium raw material 0.3 μm or less; a heat treatment step of heat-treating, at 650° C. or lower, a pulverized and mixed powder obtained through the pulverizing and mixing step; and a firing step of firing, at 740° C. or higher and lower than 850° C., the heat-treated pulverized and mixed powder.

8 . The manufacturing method of the positive electrode active material for a lithium ion secondary battery according to claim 7 , the method further comprising, between the pulverizing and mixing step and the heat treatment step, a granulating step of granulating the pulverized and mixed powder obtained through the pulverizing and mixing step to make aggregated particles having an average particle diameter of 1 μm or more.

9 . The manufacturing method of the positive electrode active material for a lithium ion secondary battery according to claim 8 , wherein the granulating step is performed using a spray drying method.

10 . A lithium ion secondary battery, comprising:
a positive electrode comprising a positive electrode active material; a negative electrode; and a separator, wherein the positive electrode active material comprises a compound having a layered structure belonging to a space group R-3m, wherein the compound having a layered structure is represented by a compositional formula:
Li 1+a M1O 2+α

wherein M1 represents a metal element or metal elements other than Li, and comprises at least Ni, −0.03≦a≦0.10, and −0.1<α<0.1, a proportion of Ni in M1 is larger than 70 atom %, and a site occupancy of a transition metal or transition metals at a 3a site obtained by structural analysis by a Rietveld method is less than 2%, and
a content of residual lithium hydroxide in the positive electrode active material is 1 mass % or less.

11 . The lithium ion secondary battery according to claim 10 , wherein the compound having a layered structure is represented by a compositional formula:
Li 1+a M1O 2+α
wherein M1 represents a metal element or metal elements other than Li, and comprises at least Ni, 0≦a≦0.10, and −0.1<α<0.1.

12 . The lithium ion secondary battery according to claim 10 , wherein the compound having a layered structure is represented by a compositional formula:
Li 1+a Ni b Mn c Co d M2 e O 2+α
wherein M2 represents a metal element other than Li, Ni, Mn, and Co, −0.03≦a≦0.10, 0.7<b<1.0, 0<c<0.3, 0<d<0.3, 0≦e<0.1, b+c+d+e=1, and −0.1<α<0.1.

13 . The lithium ion secondary battery according to claim 10 , wherein the compound having a layered structure is represented by a compositional formula:
Li 1+a Ni b Mn c Co d M2 e O 2+α
wherein M2 represents a metal element other than Li, Ni, Mn, and Co, 0≦a≦0.10, 0.7<b<1.0, 0<c<0.3, 0<d<0.3, 0≦e<0.1, b+c+d+e=1, and −0.1<α<0.1.

14 . The lithium ion secondary battery according to claim 10 , wherein the positive electrode active material comprises a secondary particle formed by aggregation and bonding of a plurality of primary particles, wherein the primary particles have an average particle diameter of less than 1 μm, and the secondary particle has an average particle diameter of larger than 1 μm.

15 . The lithium ion secondary battery according to claim 13 , wherein the positive electrode active material comprises a secondary particle formed by aggregation and bonding of a plurality of primary particles, wherein the primary particles have an average particle diameter of less than 1 μm, and the secondary particle has an average particle diameter of larger than 1 μm.

Assignees

• Hitachi Metals Ltd

Inventors

• Gunji Akira
• Toyama Tatsuya
• Takahashi Shin
• Nakabayashi Takashi
• Takano Shuichi
• Feng Xiaoliang
• Furutsuki Sho
• Tokoro Hisato

Classifications

• C01P2002/76

  by a space-group or by other symmetry indications · CPC title

• C01P2006/40

  Electric properties · CPC title

• H01M4/525 Primary

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

• H01M2004/028

  Positive electrodes · CPC title

• C01G53/50

  of the type (MnO2)n-, e.g. Li(NixMn1-x)O2 or Li(MyNixMn1-x-y)O2 · CPC title