ELECTROLYTES WITH IONIC LIQUID ADDITIVES FOR LITHIUM ION BATTERIES

• US 20170294681A1
• Filed: 03/02/2017
• Published: 10/12/2017
• Est. Priority Date: 04/07/2016
• Status: Active Grant

• Current Assignee: StoreDot Ltd.
• Original Assignee: StoreDot Ltd.
• Inventors: BURSHTAIN, Doron, KEDEM, Nir, ARONOV, Daniel
• Granted Patent: US 10,096,859 B2
• Time in Patent Office: Days
• CPC Class Codes: H01M 10/0525 Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
• CPC Class Codes: H01M 10/0567 characterised by the additives
• CPC Class Codes: H01M 2300/0025 Organic electrolyte
• CPC Class Codes: H01M 4/366 as layered products
• CPC Class Codes: H01M 4/38 of elements or alloys
• CPC Class Codes: H01M 4/58 of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
• CPC Class Codes: H01M 4/5815 Sulfides
• CPC Class Codes: H01M 4/587 for inserting or intercalating light metals
• CPC Class Codes: H01M 4/602 Polymers
• CPC Class Codes: H01M 4/628 Inhibitors, e.g. gassing inhibitors, corrosion inhibitors
• CPC Class Codes: Y02E 60/10 Energy storage using batteries

Abstract

Electrolytes, anodes, lithium ion cells and methods are provided for preventing lithium metallization in lithium ion batteries to enhance their safety. Electrolytes comprise up to 20% ionic liquid additives which form a mobile solid electrolyte interface during charging of the cell and prevent lithium metallization and electrolyte decomposition on the anode while maintaining the lithium ion mobility at a level which enables fast charging of the batteries. Anodes are typically metalloid-based, for example include silicon, germanium, tin and/or aluminum. A surface layer on the anode bonds, at least some of the ionic liquid additive to form an immobilized layer that provides further protection at the interface between the anode and the electrolyte, prevents metallization of lithium on the former and decomposition of the latter.

Claims

1. An electrolyte for a lithium ion battery having an anode and a cathode, said electrolyte comprising an ionic liquid additive present in an amount up to about 20 volume percent of the electrolyte, preventing or reducing lithium metallization at the anode.

2. The electrolyte of claim 1, wherein the ionic liquid additive is present in an amount up to about 5 volume percent of the electrolyte

3. The electrolyte of claim 1, wherein the ionic liquid additive is present in an amount of 0.1-2 volume percent of the electrolyte

4. The electrolyte of claim 1, wherein the electrolyte comprises a lithium salt in an organic solvent present in an amount of at least 80 percent by volume.

5. The electrolyte of claim 1, wherein the ionic liquid additive comprises a nitrogen atom having a charge.

6. The electrolyte of claim 1, wherein the ionic liquid additive comprises at least one sulfonylimide derivative or piperidinium derivative.

7. The electrolyte of claim 1, wherein the ionic liquid additive has a melting temperature below 10°

C.

8. The electrolyte of claim 1, wherein the ionic liquid additive has a melting temperature below 0°

C.

9. The electrolyte of claim 1, wherein the ionic liquid additive has a melting temperature below −

4°

C.

10. The electrolyte of claim 1, wherein the ionic liquid additive has a melting temperature below −

20°

C.

11. The electrolyte of claim 1, wherein said ionic liquid additive comprises a plurality of ionic liquid additives, together present in an amount up to about 20% of the electrolyte.

12. The electrolyte of claim 1, wherein ionic liquid additive comprises cations and/or anions at least 50% larger in volume than lithium ions, preventing metallization at the anode by steric hindrance.

13. The electrolyte of claim 1, wherein the ionic liquid additive forms a gradient of electric charge in the vicinity of the anode at least during charging of the lithium ion battery.

14. The electrolyte of claim 13, wherein the ionic liquid additive comprises at least one of:

1-butyl-1-methylpyrrolidinium;

bis(trifluoromethanesulfonyl)imide;

butyl-3-methylimidazolium;

bis(trifluoromethanesulfonyl)imide;

1-butyl-3-methylimidazolium;

bis(fluorosulfonyl)imide;

N,N-Diethyl-N-methyl-N-propylammonium;

bis(fluorosulfonyl)imide;

N-propyl-N-methylpiperidinium;

bis(trifluoromethanesulfonyl)imide, or any combination thereof, which species may be substituted or unsubstituted.

15. A lithium ion cell comprising

a. An anode comprising a metalloid selected from the group consisting of Si, Sn, Ge, Al, and combinations thereof;

b. a cathode, and

c. the electrolyte of claim 1.

16. The lithium ion cell of claim 15, wherein the anode comprises metalloid active material nanoparticles partly or completely coated with particles selected from the group consisting of B₄C, WC, VC and TiN.

17. The lithium ion cell of claim 15, wherein the anode comprises metalloid active material nanoparticles partly or completely coated with a polymer containing lithium.

18. The lithium ion cell of claim 15, wherein the anode comprises metalloid active material nanoparticles partly or completely coated with a borate salt, a phosphate salt, or a combination thereof.

19. A lithium ion cell comprising a graphite-based anode, a cathode, and the electrolyte of claim 1.