Formation of slurry for high loading sulfur cathodes

Patent metadata

Field	Value
Publication number	US-2017194636-A1
Application number	US-201614988917-A
Country	US
Kind code	A1
Filing date	Jan 6, 2016
Priority date	Jan 6, 2016
Publication date	Jul 6, 2017
Grant date	—

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

1 . A slurry, comprising:
encapsulated chalcogen particles; carbon nanofibers; carbon black; carboxymethyl cellulose; styrene butadiene rubber; and water; wherein 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 a sulfur content of the encapsulated chalcogen particles is greater than 90 wt % relative to a total weight of the encapsulated chalcogen particles.

7 . The slurry of claim 1 , wherein the encapsulated chalcogen particles comprise:
a chalcogen core; and a polymer coating disposed on a surface of the chalcogen core; wherein the chalcogen core comprises at least one element selected from the group consisting of sulfur, selenium and tellurium.

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

9 . The slurry of claim 7 , 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.

10 . The slurry of claim 7 , wherein the encapsulated chalcogen particles further comprise carbon black particles, functionalized carbon black particles or both homogeneously dispersed in the chalcogen core.

11 . 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.

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

13 . The method of claim 11 , wherein the mixing is performed by planetary centrifugation for up to 15 minutes at a speed of greater than 1000 rpm.

14 . The method of claim 11 , 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.

15 . 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.

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

17 . The electrode of claim 15 , wherein the current collector comprises aluminum.

18 . A method for forming the electrode of claim 15 , 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.

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

20 . The method of claim 18 , wherein the dried green electrode is calendered such that the electrode has less than 50% of the thickness of the dried green electrode.

21 . A battery, comprising:
the electrode of claim 15 as a cathode; an anode; and an electrolyte in a solvent.

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

23 . The battery of claim 21 , wherein the anode is lithium and the electrolyte comprises LiTFSI and LiNO 3 in a molar ratio of 5:1.

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

25 . The battery of claim 21 , wherein the anode is lithium and the anode is pretreated with a lithium polysulfide.

26 . A vehicle comprising the battery of claim 21 .

Assignees

• Toyota Motor Eng & Mfg North America Inc

Inventors

• Osada Naoki
• Bucur Claudiu B
• Muldoon John

Classifications

• H01M4/661

  Metal or alloys, e.g. alloy coatings (H01M4/669 take precedence) · CPC title

• H01M4/622

  being polymers · CPC title

• H01M4/38

  of elements or alloys · CPC title

• H01M4/366

  as layered products · CPC title

• H01M4/13

  Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof · CPC title