Carbon-coated active particles and processes for their preparation

Patent metadata

Field	Value
Publication number	US-2018006299-A1
Application number	US-201615199313-A
Country	US
Kind code	A1
Filing date	Jun 30, 2016
Priority date	Jun 30, 2016
Publication date	Jan 4, 2018
Grant date	—

Abstract

A process for the preparation of carbon-coated particles, where the particles include an electrochemically active material. The process includes the steps of emulsion polymerization, drying and thermally treating the polymer to obtain a nano-layer of carbon on the particles, where the carbon layer includes fibers and nitrogen-containing polyaromatics have a graphene-like structure. Also, the particles produced by the method as well as to electrode materials, electrodes and electrochemical cells including the particles.

First claim

1 . A process for producing carbon-coated particles, the process comprising the steps of:
a. forming an emulsion by mixing particles, acrylonitrile monomers, and an aqueous solvent, said particles comprising an electrochemically active material; b. polymerizing the acrylonitrile monomers in the mixture of step (a) by emulsion polymerization; c. drying the particles from step (b) to form a nano-layer of poly(acrylonitrile) at the surface of the particles; and d. thermally treating the dried particles of step (c) to form the carbon-coated particles, said carbon consisting in a nano-layer of carbon comprising fibers on the surface of the particles.

2 . The process of claim 1 , wherein step (a) further comprises the addition of a polymerization initiator.

3 . The process of claim 1 , wherein step (b) further comprises:
degassing the emulsion; and heating the emulsion under inert atmosphere at a temperature of 50° C. to 90° C. and for a time period within the range of from 5 to 15 hours.

4 . The process of claim 1 , wherein the emulsion is formed using sonication, high power stirring, or any high shear agitation technique.

5 . The process of claim 1 , wherein the drying step (c) comprises spray-drying the particles.

6 . The process of claim 5 , wherein the spray-drying is carried out at a temperature in the chamber above the boiling point of the solvent.

7 . The process of claim 5 , wherein the spray-drying is carried out at an applied temperature of between 120° C. and 250° C.

8 . The process of claim 1 , wherein the drying step (c) is carried out without any previous purification step.

9 . The process of claim 1 , wherein the thermal treatment step (d) is a carbonization step comprising heating the particle at a temperature of at least 500° C.

10 . (canceled)

11 . The process of claim 9 , wherein the carbonization step comprises at least one temperature ramp.

12 . The process of claim 9 , wherein the carbonization step comprises:
progressively heating the particles having a nano-layer of poly(acrylonitrile) at the surface using a ramp of temperature from a temperature close to room temperature up to at least 200° C., with an increase rate of between 3° C.min −1 and 10° C.min −1 ; keeping the temperature to at least 200° C. for a period of 30 minutes to 2 hours; and further heating the particles under inert atmosphere with an increase rate of between 3° C.min −1 and 10° C.min −1 up to a final temperature of at least 500° C.

13 . The process of claim 12 , wherein the increase rate is of 5° C.min −1 .

14 . The process of claim 12 , wherein the final temperature is of at least 600° C.

15 . The process ofclaim 12 , wherein the inert atmosphere is selected from argon, nitrogen, carbon dioxide or a mixture thereof.

16 . The process of claim 15 , wherein the inert gas is a mixture of argon and carbon dioxide having a ratio Ar/CO 2 of between about 60:40 to about 90:10.

17 . The process of claim 1 , wherein the electrochemically active material comprises a material selected from the group consisting of titanates, lithium titanates, lithium metal phosphates, vanadium oxides, lithium metal oxides, and combinations thereof.

18 . A process for producing carbon-coated LTO particles, the process comprising the steps of:
a. forming a Pickering emulsion comprising particles, acrylonitrile monomers, a polymerization initiator and an aqueous solvent, said particles comprising LTO as an electrochemically active material; b. polymerizing the acrylonitrile monomers by emulsion polymerization to form poly(acrylonitrile) on a surface and inside pores of the particles; c. spray drying the polymerized particles of step (b) to obtain dried particles having a nano-layer of poly(acrylonitrile) at their surface; and d. carbonizing the dried particles of step (c) to form a carbon coating comprising carbon fibers on the surface of the particles.

19 . Carbon-coated particles produced by the process of claim 1 , wherein the particles are coated with a nano-layer of carbon comprising carbon fibers and polyaromatics consisting of carbon and nitrogen atoms.

20 . (canceled)

21 . Carbon-coated particles, wherein the particles comprise an electrochemically active material and are coated with a nano-layer of carbon comprising carbon fibers and polyaromatics consisting of carbon and nitrogen atoms.

22 . The carbon-coated particles of claim 21 , wherein the electrochemically active material comprises a material selected from the group consisting of titanates, lithium titanates, lithium metal phosphates, vanadium oxides, lithium metal oxides, and combinations thereof.

23 . The carbon-coated particles of claim 22 , wherein the electrochemically active material is selected from TiO 2 , Li 2 TiO 3 , Li 4 Ti 5 O 12 , H 2 Ti 5 O 11 and H 2 Ti 4 O 9 , or a combination thereof, LiM′PO 4 wherein M′ is Fe, Ni, Mn, Co, or a combination thereof, LiV 3 O 8 , V 2 O 5 , LiMn 2 O 4 , LiM″O 2 , wherein M″ is Mn, Co, Ni, or a combination thereof, Li(NiM″′)O 2 , wherein M″′ is Mn, Co, Al, Fe, Cr, Ti, or Zr, and combinations thereof.

24 . An electrode material comprising the carbon-coated particles of claim 21 together with a binder.

25 . The electrode material of claim 24 , wherein the binder is selected from SBR (styrene butadiene rubber), PAA (poly(acrylic acid)), PMAA (poly(methacrylic acid)), polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), NBR (butadiene acrylonitrile rubber), HNBR (hydrogenated NBR), CHR (epichlorohydrin rubber), ACM (acrylate rubber), and combination thereof, optionally comprising a thicknening agent.

26 . (canceled)

27 . An electrode comprising the electrode material as defined in claim 24 on a current collector.

28 . An electrochemical cell comprising an electrode as defined in claim 27 , an electrolyte and a counter-electrode.

Assignees

• HYDRO-QUéBEC
• Sony Corp

Inventors

• Daigle Jean-Christophe
• Asakawa Yuichiro
• Uesaka Shinichi
• Zaghib Karim

Classifications

• H01M4/131

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

• H01M4/366 Primary

  as layered products · CPC title

• H01M10/0525

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

• C01B32/15

  Nano-sized carbon materials · CPC title

• H01M4/625

  Carbon or graphite · CPC title