Cathode material and lithium secondary battery using same as cathode

Patent metadata

Field	Value
Publication number	US-10505189-B2
Application number	US-201615574222-A
Country	US
Kind code	B2
Filing date	May 20, 2016
Priority date	May 22, 2015
Publication date	Dec 10, 2019
Grant date	Dec 10, 2019

Abstract

A composite oxide which includes lithium, at least one of calcium and magnesium, and nickel and manganese, and has a lithium-excess layered rock-salt structure, and a cathode active material and a lithium secondary battery which contain the composite oxide.

First claim

The invention claimed is:

1. A composite oxide comprising lithium, calcium, nickel and manganese, and having a lithium-excess layered rock-salt structure, wherein the calcium is substituted into only a lithium layer.

2. The composite oxide according to claim 1 , wherein when lithium is extracted electrochemically at a potential of at least 4.6 V but not more than 5.0 V, an arrangement of oxygen atoms is maintained.

3. The composite oxide according to claim 1 , having a layered rock-salt structure belonging to a monoclinic system.

4. The composite oxide according to claim 1 , represented by a chemical formula (Li 1+x−2y M y )(Co z Ni m Ti n Mn 1−m−n ) 1−x O 2 , wherein M represents Ca, or Ca and Mg, and x, y, z, m and n are numbers that satisfy 0<x≤0.33, 0<y<0.13, 0≤z<0.2, 0<m<0.5 and 0≤n≤0.25 respectively.

5. The composite oxide according to claim 1 , represented by a chemical formula (Li 1+x−2y M y )(Co z Ni m Ti n Mn 1−m−n ) 1−x O 2 , wherein M represents Ca, or Ca and Mg, and x, y, z, m and n are numbers that satisfy 0.20≤x≤0.28, 0<y<0.03, 0≤z<0.2, 0.1<m<0.3 and 0≤n≤0.2 respectively.

6. The composite oxide according to claim 1 , represented by a chemical formula (Li 1+x−2y M y )(Co z Ni m Mn 1−m ) 1−x O 2 , wherein M represents Ca, or Ca and Mg, and x, y, z and m are numbers that satisfy 0.20≤x≤0.28, 0<y<0.03, 0≤z<0.2 and 0.1<m<0.2 respectively.

7. The composite oxide according to claim 1 , represented by a chemical formula (Li 1+x−2y M y )(Ni m Mn 1−m ) 1−x O 2 , wherein M represents Ca, or Ca and Mg, and x, y and m are numbers that satisfy 0.20≤x≤0.28, 0<y<0.03 and 0.2<m<0.3 respectively.

8. The composite oxide according to claim 1 , represented by a chemical formula (Li 1+x−2y M y )(Ni m Ti n Mn 1−m−n ) 1−x O 2 , wherein M represents Ca, or Ca and Mg, and x, y, m and n are numbers that satisfy 0.20≤x≤0.28, 0<y<0.03, 0.1<m<0.3 and 0≤n≤0.2 respectively.

9. The composite oxide according to claim 1 , further comprising magnesium.

10. The composite oxide according to claim 9 , wherein when lithium is extracted electrochemically at a potential of at least 4.6 V but not more than 5.0 V, an arrangement of oxygen atoms is maintained.

11. The composite oxide according to claim 9 , having a layered rock-salt structure belonging to a monoclinic system.

12. A cathode active material for a lithium secondary battery, the active material comprising the composite oxide according to claim 1 .

13. The cathode active material for a lithium secondary battery according to claim 12 , wherein when an initial charging reaction is performed within a voltage range from at least 4.4 V to not more than 4.7 V, an arrangement of oxygen atoms is maintained, and a charge curve exhibits a monotonous increase in potential.

14. The cathode active material for a lithium secondary battery according to claim 12 , wherein the cathode active material has a high capacity, and maintains an arrangement of transition metal atoms upon charge/discharge cycling.

15. A cathode active material for a lithium secondary battery, the active material comprising the composite oxide according to claim 9 .

16. The cathode active material for a lithium secondary battery according to claim 15 , wherein when an initial charging reaction is performed within a voltage range from at least 4.4 V to not more than 4.7 V, an arrangement of oxygen atoms is maintained, and a charge curve exhibits a monotonous increase in potential.

17. A lithium secondary battery comprising a cathode, an anode, a separator and an electrolyte, wherein the cathode comprises the cathode active material for a lithium secondary battery according to claim 12 .

18. The lithium secondary battery according to claim 17 , wherein a charge/discharge capacity of the lithium secondary battery per unit of weight of composite oxide in the cathode active material is at least 250 mAh/g but not more than 300 mAh/g.

19. A lithium secondary battery comprising a cathode, an anode, a separator and an electrolyte, wherein the cathode comprises the cathode active material for a lithium secondary battery according to claim 15 .

20. The lithium secondary battery according to claim 19 , wherein a charge/discharge capacity of the lithium secondary battery per unit of weight of composite oxide in the cathode active material is at least 250 mAh/g but not more than 300 mAh/g.

Assignees

• Aist

Inventors

• Akimoto Junji
• Hayakawa Hiroshi

Classifications

• C01P2002/77

  by unit-cell parameters, atom positions or structure diagrams · CPC title

• C01P2002/72

  by d-values or two theta-values, e.g. as X-ray diagram · CPC title

• H01M10/052

  Li-accumulators · CPC title

• C01P2002/85

  by XPS, EDX or EDAX data · CPC title

• C01P2002/76

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