Fluorinated electrolytes with nitrile groups

Patent metadata

Field	Value
Publication number	US-9917329-B2
Application number	US-201615164662-A
Country	US
Kind code	B2
Filing date	May 25, 2016
Priority date	May 10, 2016
Publication date	Mar 13, 2018
Grant date	Mar 13, 2018

Abstract

Perfluoropolyether electrolytes have either one or two terminal nitrile groups and an alkali metal salt. The alkali metal salt can be a lithium salt, a sodium salt, a potassium salt, or a cesium salt. The salt can make up between 5 and 30 wt % of the electrolyte composition. Such electrolytes have shown high ionic conductivities, making them useful as lithium cell electrolytes.

First claim

We claim:

1. An electrolyte, comprising:
a mixture of
perfluoropolyethers, each having either one or two terminal nitrile groups covalently coupled thereto; and
an alkali metal salt;
wherein the perfluoropolyethers are selected from the group consisting of:

and combinations thereof, and
wherein x is the mole fraction of difluoromethyleneoxy groups in the perfluoropolyether, and x ranges between 0 and 1;
y is the mole fraction of tetrafluoroethyleneoxy groups in the perfluoropolyether, y is equal to (1−x) and y ranges between 0 and 1;
n is the average total number of randomly co-distibuted difluoromethyleneoxy and tetrafluoroethyleneoxy groups in the perfluoropolyether, and n ranges between 1 and 50;
Rf is a perfluorinated C1-C8 straight alkyl group or a perfluorinated C1-C8 branched alkyl group; and
R 1 is selected from the group consisting of C1-C8 straight alkyl groups, C1-C8 branched alkyl groups, polyethers, cyanoethyls, pyrrolidine, piperidine, morpholine, 4-methylpiperazine, and C5-C8 heterocycloalkyl groups that contain nitrogen.

2. The electrolyteof claim 1 , wherein the alkali metal salt is a lithium salt.

3. The electrolyte of claim 1 , wherein the alkali metal salt is a sodium salt.

4. The electrolyte of claim 1 , wherein the alkali metal salt comprises between 5 to 30 wt % of the electrolyte.

5. The electrolyte of claim 1 wherein the polyethers are selected from the group consisting of 2-methoxyethyl and 2-(2-ethoxy)ethoxyethyl.

6. An electrolyte composing:
a mixture of:
perfluoropolyethers, each having one or two terminal nitrile groups covalently coupled thereto; and
an alkali metal salt;
wherein the perfluoropolyethers are selected from the group consisting of:

and combinations thereof, and
wherein x is the mole fraction of difluoromethyleneoxy groups in the perfluoropolyether, and x ranges between 0 and 1;
y is the mole fraction of tetrafluoroethyleneoxy groups in the perfluoropolyether, y is equal to (1−x) and y ranges between 0 and 1;
n is the average total number of randomly co-distributed difluoromethyleneoxy and tetrafluoroethyleneoxy groups in the perfluoropolyether and n ranges between 1 and 50; and
Rf is a perfluorinated C1-C8 straight alkyl group or a perfluorinated C1-C8 branched alkyl group; and
R 2 and R 3 are each selected independently from the group consisting of —CN, C1-C8 straight alkyl groups, C1-C8 branched alkyl groups, polyethers, cyanoethyls, hydrogen, pyrrolidine, piperidine, morpholine, 4-methylpiperazine, and C5-C8 heterocycloalkyl groups that contain nitrogen.

7. An electrochemical cell, comprising:
an anode;
a cathode; and
an electrolyte between the anode and the cathode, the electrolyte in ionic communication with both the anode and the cathode;
wherein the electrolyte comprises:
the electrolyte of claim 1 or the electrolyte of claim 6 .

8. The cell of claim 7 , wherein the anode comprises a material selected from the group consisting of lithium metal and alloys, graphite, lithium titanante, silicon, silicon alloys, and combinations thereof.

9. The cell of claim 7 , wherein the cathode comprises a material selected from the group consisting of nickel cobalt aluminum oxide (NCA), nickel cobalt manganese oxide (NCM), LiCoO 2 , LiFePO 4 , LiMnPO4, LiNiPO 4 , LiCoPO 4 , LiNi 0.5 Mn 1.5 O 4 , Li 2 MnSiO 4 , Li 2 FeSiO 4 and LiMn 2 O 4 particles, and combination thereof.

10. An electrochemical cell, comprising:
an anode configured to absorb and release lithium ions;
a cathode comprising cathode active material particles, an electronically-conductive additive, a catholyte, and an optional binder material;
a current collector adjacent to an outside surface of the cathode; and
a separator region between the anode and the cathode, the separator region comprising a separator electrolyte configured to facilitate movement of lithium ions back and forth between the anode and the cathode;
wherein the catholyte comprises:
the electrolyte of claim 1 or the electrolyte of claim 6 .

11. The electrolyte of claim 6 , wherein the alkali metal salt is a lithium salt.

12. The electrolyte of claim 6 , wherein the alkali metal salt is a sodium salt.

13. The electrolyte of claim 6 , wherein the alkali metal salt comprises between 5 to 30 wt % of the electrolyte.

Assignees

• Seeo Inc

Inventors

• Yang Jin
• Sivanandan Kulandaivelu
• WANG Xiao-liang
• Eitouni Hany Basam
• Lam Steven

Classifications

• H01M4/134

  Electrodes based on metals, Si or alloys · CPC title

• H01M2004/028

  Positive electrodes · CPC title

• H01M10/0525

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

• H01M10/0569 Primary

  characterised by the solvents · CPC title

• H01M2300/0034

  Fluorinated solvents · CPC title