Lithium secondary battery including phosphite additive

Patent metadata

Field	Value
Publication number	US-10665897-B2
Application number	US-201715796752-A
Country	US
Kind code	B2
Filing date	Oct 28, 2017
Priority date	May 26, 2017
Publication date	May 26, 2020
Grant date	May 26, 2020

Abstract

A lithium secondary battery includes a positive electrode; a negative electrode; and an electrolyte disposed between the positive electrode and the negative electrode, wherein the positive electrode includes a positive active material represented by Formula 1, and the electrolyte includes a lithium salt; a non-aqueous solvent; and a phosphite compound represented by Formula 2, wherein the phosphite compound is present in amount of about 0.1 wt % to about 5 wt % based on a total weight of the electrolyte:

Li x Ni y M 1-y O 2-z A z   Formula 1

wherein, in Formula 1,
0.9≤x≤1.2, 0.7≤y≤0.98, and 0≤z<0.2;
M comprises Al, Mg, Mn, Co, Fe, Cr, V, Ti, Cu, B, Ca, Zn, Zr, Nb, Mo, Sr, Sb, W, Bi, or a combination thereof; and
A is an element having an oxidation number of −1 or −2;
wherein in Formula 2,
R 1 to R 3 are independently an unsubstituted C 1 -C 30 alkyl group or an unsubstituted C 6 -C 60 aryl group.

First claim

What is claimed is:

1. A lithium secondary battery, comprising:
a positive electrode;
a negative electrode; and
an electrolyte disposed between the positive electrode and the negative electrode,
wherein the positive electrode comprises a positive active material represented by Formula 1, and
wherein the electrolyte comprises:
a lithium salt;
a non-aqueous solvent; and
a phosphite compound represented by Formula 2,

wherein the phosphite compound is present in an amount in a range of about 0.1 weight percent to about 5 weight percent based on a total weight of the electrolyte:
Li x Ni y M 1-y O 2-z A z   Formula 1

wherein, in Formula 1,
0.9<x<1.2, 0.7<y<0.98, and 0<z<0.2;
M comprises Al, Mg, Mn, Co, Fe, Cr, V, Ti, Cu, B, Ca, Zn, Zr, Nb, Mo, Sr, Sb, W, Bi, or a combination thereof; and
A is an element having an oxidation number of −1 or −2; and
wherein in Formula 2,
R1 to R3 are each independently an unsubstituted linear or branched C 1 -C 30 alkyl group or an unsubstituted C 6 -C 60 aryl group.

2. The lithium secondary battery of claim 1 , wherein the phosphite compound is present in an amount in a range of about 0.1 weight percent to about 3 weight percent based on the total weight of the electrolyte.

3. The lithium secondary battery of claim 1 , wherein the phosphite compound comprises tributyl phosphite, triphenyl phosphite, tris(o-tolyl)phosphite, or a combination thereof.

4. The lithium secondary battery of claim 1 , wherein the lithium salt comprises lithium difluoro(oxalate)borate, lithium bis(oxalate)borate, lithium difluorobis(oxalate)borate, LiBF 4 , LiPF 6 , LiCF 3 SO 3 , (CF 3 SO 2 ) 2 NLi, (FSO 2 ) 2 NLi, or a combination thereof.

5. The lithium secondary battery of claim 1 , wherein the non-aqueous solvent comprises dimethyl carbonate, diethyl carbonate, ethylmethyl carbonate, dipropyl carbonate, methylpropyl carbonate, ethylpropyl carbonate, methylethyl carbonate, ethylene carbonate, propylene carbonate, butylene carbonate, tetraethyleneglycoldimethylether, or a combination thereof.

6. The lithium secondary battery of claim 1 , wherein the non-aqueous solvent comprises fluoroethylene carbonate.

7. The lithium secondary battery of claim 6 , wherein the fluoroethylene carbonate is present in an amount in a range of about 0.1 volume percent to about 10 volume percent based on a total volume of the non-aqueous solvent.

8. The lithium secondary battery of claim 1 , wherein the electrolyte comprises a cyclic carbonate comprising a carbon-carbon double bond, a cyclic carboxylic acid anhydride comprising a carbon-carbon double bond, or a combination thereof.

9. The lithium secondary battery of claim 1 , wherein the electrolyte further comprises vinylene carbonate, vinylethylene carbonate, maleic anhydride, succinic anhydride, or a combination thereof.

10. The lithium secondary battery of claim 9 , wherein vinylene carbonate, maleic anhydride, or the combination thereof is present in an amount in a range of about 0.1 weight percent to about 2 weight percent based on the total weight of the electrolyte.

11. The lithium secondary battery of claim 1 , wherein the electrolyte further comprises a sulfone compound, a sulfonate compound, a disulfonate compound, or a combination thereof in an amount in a range of about 0.1 weight percent to about 2 weight percent based on the total weight of the electrolyte.

12. The lithium secondary battery of claim 11 , wherein the disulfonate compound is methylene methane disulfonate.

13. The lithium secondary battery of claim 1 , wherein, in Formula 1, 0.8≤y≤0.98.

14. The lithium secondary battery of claim 1 , wherein the positive active material is represented by Formula 3 or Formula 4:
Li x′ Ni y′ Co 1-y′-z′ Al z′ O 2   Formula 3

Li x′ Ni y′ Co 1-y′-z′ Mn z′ O 2   Formula 4

wherein, in Formula 3 and Formula 4, 0.9≤x′≤1.2, 0.8≤y′≤0.98, 0<z′<0.1, and 0<1-y′-z′<0.2.

15. The lithium secondary battery of claim 1 , wherein the positive active material comprises Li 1.02 Ni 0.80 Co 0.15 Mn 0.05 O 2 , Li 1.02 Ni 0.85 Co 0.10 Mn 0.05 O 2 , Li 1.02 Ni 0.88 Co 0.08 Mn 0.04 O 2 , or Li 1.02 Ni 0.88 Co 0.08 Al 0.04 O 2 .

16. The lithium secondary battery of claim 1 , wherein the negative electrode comprises a negative active material comprising a metal alloyable with lithium, a carbonaceous negative active material, or a combination thereof.

17. The lithium secondary battery of claim 16 , wherein the negative active material comprising a metal alloyable with lithium comprises silicon (Si), a silicon-carbon composite material comprising a Si particle, SiO a′ (0<a′<2), or a combination thereof.

18. The lithium secondary battery of claim 16 , wherein the carbonaceous negative active material comprises graphite.

19. The lithium secondary battery of claim 1 , wherein a direct current internal resistance (DCIR) increase ratio of the lithium secondary battery is 150% or less before and after 200 charge/discharge cycles at 45° C.

20. The lithium secondary battery of claim 1 , wherein a cell energy density of the lithium secondary battery is about 500 watt-hours per liter or greater.

Assignees

• Samsung Electronics Co Ltd
• Samsung Sdi Co Ltd

Inventors

• Koh Myongchun
• Kang Yoonsok
• Park Eunha
• Park Insun
• Jang Jihyun

Classifications

• H01M4/131

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

• H01M4/386

  Silicon or alloys based on silicon · CPC title

• H01M10/0525

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

• H01M2004/027

  Negative electrodes · CPC title

• H01M4/587

  for inserting or intercalating light metals · CPC title