Lithium ion secondary battery

Patent metadata

Field	Value
Publication number	US-11201327-B2
Application number	US-201716306366-A
Country	US
Kind code	B2
Filing date	Jun 13, 2017
Priority date	Jun 13, 2016
Publication date	Dec 14, 2021
Grant date	Dec 14, 2021

Abstract

In order to provide a lithium ion secondary battery having both high energy density and an excellent charge-rate characteristic, there is provided a lithium ion secondary battery including a positive electrode containing a positive electrode active material made of a lithium composite oxide, and nano-carbon having a Li ion diffusion path as an additive, and an electrolyte solution containing 0.5 mol/l or more of Li[(FSO 2 ) 2 N] as an electrolyte, LiPO 2 F 2 as an additive, and a ternary-system of ethylene carbonate (EC), dimethyl carbonate (DMC) and ethyl methyl carbonate (EMC), as solvents.

First claim

The invention claimed is:

1. A lithium ion secondary battery comprising:
a positive electrode comprising a positive electrode active material made of a lithium composite oxide, and nano-carbon having a Li ion diffusion path as an additive, and
an electrolyte solution comprising 0.5 mol/1 or more of Li[(FSO 2 ) 2 N] as an electrolyte, LiPO2F2 as an additive, and a ternary-system of ethylene carbonate (EC), dimethyl carbonate (DMC) and ethyl methyl carbonate (EMC), as solvents;
wherein the nano-carbon comprises porous graphene and satisfies the following conditions:
(1) The porous graphene has 1 to 200 graphene layers,
(2) The sizes of pores in a graphene basal plane range from 70 nm to 200 nm,
(3) The number of pores in each graphene basal plane is 10 to 500 per μm 2 ,
(4) Oxygen content is 0.8 mass % or less,
(5) In Raman spectroscopy, the peak intensity-ratio I D /I G , which is the ratio of the peak in G band present within the range of 1596 to 1570 cm −1 to the peak in D band near 1360 cm −1 , is 0.6 to 1.35, and
(6) Pore volumes fall within the range of 1.35 to 3 cm 3 /g.

2. The lithium ion secondary battery according to claim 1 , wherein the nano-carbon coats a surface of the positive electrode active material in the positive electrode.

3. The lithium ion secondary battery according to claim 1 , wherein the electrolyte contains Li[(FSO 2 ) 2 N] and other electrolyte, and the molar ratio of Li[(FSO 2 ) 2 N] to the other electrolyte is 1 or more.

4. The lithium ion secondary battery according to claim 3 , wherein the other electrolyte is LiPF 6 .

5. The lithium ion secondary battery according to claim 3 , wherein a total concentration of the electrolytes in the electrolyte solution is 0.6 to 2 mol/L.

6. The lithium ion secondary battery according to claim 1 , wherein the LiPO 2 F 2 is contained in an amount of 0.005 to 7 mass % in the electrolyte solution.

7. The lithium ion secondary battery according to claim 1 , wherein the ternary-system of solvents are contained in a volume ratio represented by the following expression (1):
EC/DMC/EMC= x:y: 1− x−y   (1)

wherein x is 0.15 to 0.5; y is 0.2 to 0.6; and x+y<1.

8. The lithium ion secondary battery according to claim 1 , wherein the lithium composite oxide is a material having a layered structure.

9. The lithium ion secondary battery according to claim 8 , wherein the material having a layered structure is a lithium-cobalt-nickel-manganese composite oxide.

Assignees

• Nec Corp

Inventors

• Cheng Qian
• Maeda Katsumi
• Tamura Noriyuki

Classifications

• H01M10/0525

  Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries · CPC title

• H01M2004/028

  Positive electrodes · CPC title

• H01M10/0569

  characterised by the solvents · CPC title

• H01M4/62

  Selection of inactive substances as ingredients for active masses, e.g. binders, fillers · CPC title

• H01M2004/021

  Physical characteristics, e.g. porosity, surface area · CPC title