Formation of slurry for high loading sulfur cathodes

Patent metadata

Field	Value
Publication number	US-10312500-B2
Application number	US-201614988917-A
Country	US
Kind code	B2
Filing date	Jan 6, 2016
Priority date	Jan 6, 2016
Publication date	Jun 4, 2019
Grant date	Jun 4, 2019

Abstract

A high density slurry comprising encapsulated sulfur particles, carbon nanofibers and activated carbon black suitable for use in forming the active material of an electrode. A method for forming the high density sulfur slurry is also provided. A cathode containing the particles and a battery constructed with the cathode as well as methods for their formation are also provided.

First claim

The invention claimed is:

1. A slurry, comprising:
encapsulated chalcogen particles, comprising a chalcogen core and an encapsulate coating disposed on the chalcogen core surface consisting of at least one polymer having both hydrophobic regions and hydrophilic regions;
carbon nanofibers;
carbon black;
carboxymethyl cellulose;
styrene butadiene rubber; and
water;
wherein
a sulfur content of the encapsulated chalcogen particles is greater than 90 wt % relative to the total dry weight of the encapsulated chalcogen particles,
a content of sulfur is greater than 85 wt % relative to a total dry weight of the slurry; and
a ratio of carbon nanofibers to carbon black is 3:1.

2. The slurry of claim 1 , wherein a total content of the carbon nanofiber and carbon black is less than 10 wt % relative to the total dry weight of the slurry.

3. The slurry of claim 1 , wherein a total content of the carboxymethyl cellulose and styrene butadiene rubber is less than 5 wt % relative to the total dry weight of the slurry.

4. The slurry of claim 1 , wherein a ratio of carboxymethyl cellulose to styrene butadiene rubber is 3:1.

5. The slurry of claim 1 , wherein water is present in an amount equal to 0.25-1.25 times the total dry weight of the slurry.

6. The slurry of claim 1 , wherein the chalcogen core further comprises at least one of selenium and tellurium.

7. The slurry of claim 1 , wherein the polymer coating consists of at least one polymer selected from the group consisting of poly (3,4-ethylenedioxythiophene) polystyrene sulfonate, polyvinylpyrrolidone, polyaniline, poly(ethylene oxide), carboxymethyl cellulose, sodium carboxymethyl cellulose, polymethacrylic acid, poly(2-acrylamido-2-methyl-1-propanesulfonic acid), branched polyethylenimine, and poly(diallyl dimethylammonium chloride).

8. The slurry of claim 6 , wherein a selenium content or a tellurium content of the encapsulated chalcogen particles is less than 50 wt % relative to a total weight of the encapsulated chalcogen particles.

9. The slurry of claim 6 , wherein the encapsulated chalcogen core further comprises carbon black particles, functionalized carbon black particles or both which are homogeneously dispersed in the chalcogen core.

10. A method for forming the slurry of claim 1 , comprising:
forming a powder mixture comprising 90 wt % of the encapsulated chalcogen particles relative to the total dry weight of the slurry and 8 wt % of carbon nanofibers and carbon black together relative to the total dry weight of the slurry;
grinding the powder mixture to form a powder of carbon and active material;
adding a weight corresponding to 2 wt % of carboxymethyl cellulose and styrene butadiene rubber together relative to the total dry weight of the slurry to the powder of carbon and active material to form a thick slurry;
adding water to the thick slurry;
mixing the thick slurry to form the slurry.

11. The method of claim 10 , wherein water is added in an amount of 0.4-1.2 mL per g of the thick slurry.

12. The method of claim 10 , wherein the mixing is performed by planetary centrifugation for up to 15 minutes at a speed of greater than 1000 rpm.

13. The method of claim 10 , further comprising ball milling the fine powder of carbon and active material for up to 2 hours at a speed of less than 200 rpm.

14. An electrode, comprising:
the dried slurry of claim 1 as active material; and
a current collector;
wherein the dried slurry is on a surface of the current collector.

15. The electrode of claim 14 , wherein a sulfur weight per current collector area is in the range of 3-8 mg/cm 2 .

16. The electrode of claim 14 , wherein the current collector comprises aluminum.

17. A method for forming the electrode of claim 14 , comprising:
pouring the slurry onto the current collector
forming a wet gap of less than 200 μm to obtain a green electrode;
drying the green electrode; and
calendering the dried green electrode to form the electrode.

18. The method of claim 17 , wherein the drying is performed in an oven at a temperature of up to 100° C. for up to 12 hours.

19. The method of claim 17 , wherein the dried green electrode is calendered such that the electrode has less than 50% of the thickness of the dried green electrode.

20. A battery, comprising:
the electrode of claim 14 as a cathode;
an anode; and
an electrolyte in a solvent.

21. The battery of claim 20 , wherein the anode comprises a metal selected from the group consisting of an alkali metal and an alkaline earth metal.

22. The battery of claim 20 , wherein the anode is lithium and the electrolyte comprises LiTFSI and LiNO 3 in a molar ratio of 5:1.

23. The battery of claim 22 , wherein the solvent comprises glyme and dioxolane in a weight ratio of 1:1.

24. The battery of claim 20 , wherein the anode is lithium and the anode is pretreated with a lithium polysulfide.

25. A vehicle comprising the battery of claim 20 .

Assignees

• Toyota Eng & Mfg North America

Inventors

• Osada Naoki
• Bucur Claudiu B
• Muldoon John

Classifications

• H01M4/366

  as layered products · CPC title

• H01M10/0568

  characterised by the solutes · CPC title

• H01M4/0435 Primary

  Rolling or calendering · CPC title

• H01M4/581

  Chalcogenides or intercalation compounds thereof · CPC title

• H01M4/625

  Carbon or graphite · CPC title