Dendrite-intercepting layer for alkali metal secondary battery

Patent metadata

Field	Value
Publication number	US-9755236-B2
Application number	US-201514545203-A
Country	US
Kind code	B2
Filing date	Apr 8, 2015
Priority date	Apr 8, 2015
Publication date	Sep 5, 2017
Grant date	Sep 5, 2017

Abstract

A dendrite penetration-resistant layer for a rechargeable alkali metal battery, comprising multiple graphene sheets or platelets or exfoliated graphite flakes that are chemically bonded by a lithium- or sodium-containing species to form an integral layer that prevents dendrite penetration through the integral layer, wherein the lithium-containing species is selected from Li 2 CO 3 , Li 2 O, Li 2 C 2 O 4 , LiOH, LiX, ROCO 2 Li, HCOLi, ROLi, (ROCO 2 Li) 2 , (CH 2 OCO 2 Li) 2 , Li 2 S, Li x SO y , Na 2 CO 3 , Na 2 O, Na 2 C 2 O 4 , NaOH, NaX, ROCO 2 Na, HCONa, RONa, (ROCO 2 Na) 2 , (CH 2 OCO 2 Na) 2 , Na 2 S, Na x SO y , or a combination thereof, wherein X=F, Cl, I, or Br, R=a hydrocarbon group, x=0-1, y=1-4. Also provided is a process for producing a dendrite penetration-resistant layer based on the principle of electrochemical decomposition of an electrolyte in the presence of multiple graphene sheets.

First claim

The invention claimed is:

1. A dendrite penetration-resistant layer for a rechargeable alkali metal battery, said layer comprising multiple graphene sheets or platelets or exfoliated graphite flakes that are chemically bonded by a lithium- or sodium-containing species to form an integral layer that prevents dendrite penetration through said integral layer in said alkali metal battery, wherein said lithium- or sodium-containing species is selected from Li 2 CO 3 , Li 2 O, Li 2 C 2 O 4 , LiOH, LiX, ROCO 2 Li, HCOLi, ROLi, (ROCO 2 Li) 2 , (CH 2 OCO 2 Li) 2 , Li 2 S, Li x SO y , Na 2 CO 3 , Na 2 O, Na 2 C 2 O 4 , NaOH, NaiX, ROCO 2 Na, HCONa, RONa, (ROCO 2 Na) 2 , (CH 2 OCO 2 Na) 2 , Na 2 S, Na x SO y , or a combination thereof, wherein X=F, Cl, I, or Br, R=a hydrocarbon group, 0<x≦1 and 1≦y≦4; and wherein said lithium- or sodium-containing species is derived from an electrochemical decomposition reaction.

2. The dendrite penetration-resistant layer of claim 1 , wherein said graphene sheets or platelets include single-layer sheets or multi-layer platelets of a graphene material selected from pristine graphene, graphene oxide having 2% to 46% by weight of oxygen, reduced graphene oxide having 0.01% to 2% by weight of oxygen, chemically functionalized graphene, nitrogen-doped graphene, boron-doped graphene, fluorinated graphene, or a combination thereof.

3. The dendrite penetration-resistant layer of claim 1 , wherein said graphene sheets or platelets or exfoliated graphite flakes are bonded by said lithium- or sodium-containing species in an edge-to-edge, edge-to-face, or face-to-face manner.

4. The dendrite penetration-resistant layer of claim 1 , wherein said graphene sheets or platelets or exfoliated graphite flakes have a length or width smaller than 0.5 μm measured prior to being bonded by said lithium- or sodium-containing species.

5. The dendrite penetration-resistant layer of claim 1 , wherein said graphene sheets or platelets or exfoliated graphite flakes have a length or width smaller than 100 nm measured prior to being bonded by said lithium- or sodium-containing species.

6. The dendrite penetration-resistant layer of claim 1 , wherein said dendrite penetration-resistant layer has a thickness from 2 nm to 20 μm.

7. The dendrite penetration-resistant layer of claim 1 , wherein said dendrite penetration-resistant layer has a thickness from 10 nm to 10 μm.

8. The dendrite penetration-resistant layer of claim 1 , wherein said dendrite penetration-resistant layer is a lithium ion conductor or sodium ion conductor having an ion conductivity no less than 10 −4 S/cm.

9. The dendrite penetration-resistant layer of claim 1 , wherein said dendrite penetration-resistant layer is a lithium ion conductor or sodium ion conductor having an ion conductivity no less than 10 −3 S/cm.

10. The dendrite penetration-resistant layer of claim 1 , wherein said graphene sheets contain point defects to promote migration of lithium or sodium ions, wherein said point defects are produced by removing non-carbon elements or chemical functional groups from graphene surfaces.

11. The dendrite penetration-resistant layer of claim 1 wherein said graphene sheets or platelets contain single-layer or few-layer graphene, wherein few-layer is defined as 10 planes of hexagonal carbon atoms or less.

12. The dendrite penetration-resistant layer of claim 1 wherein said lithium- or sodium-containing species contain at least two species selected from Li 2 CO 3 , Li 2 O, Li 2 C 2 O 4 , LiOH, LiX, ROCO 2 Li, HCOLi, ROLi, (ROCO 2 Li) 2 , (CH 2 OCO 2 Li) 2 , Li 2 S, Li x SO y , Na 2 CO 3 , Na 2 O, Na 2 C 2 O 4 , NaOH, NaiX, ROCO 2 Na, HCONa, RONa, (ROCO 2 Na) 2 , (CH 2 OCO 2 Na) 2 , Na 2 S, Na x SO y , or a combination thereof, wherein X=F, Cl, I, or Br, R=a hydrocarbon group, 0<x≦1 and 1≦y≦4.

13. A process for producing a dendrite penetration-resistant layer for a rechargeable alkali metal battery layer, said process comprising (a) preparing a working electrode containing a porous structure of multiple graphene sheets or platelets or exfoliated graphite flakes; (b) preparing a counter electrode containing lithium or sodium metal or alloy; (c) bringing said working electrode and said counter electrode in contact with an electrolyte containing a solvent and a lithium salt or sodium salt dissolved in said solvent; and (d) applying a current or voltage to said working electrode and said counter electrode to induce an electrochemical oxidative decomposition and/or a reductive decomposition of said electrolyte for forming one or more lithium- or sodium-containing species that are chemically bonded to said multiple graphene sheets or platelets or exfoliated graphite flakes to produce said dendrite penetration-resistant layer.

14. The process of claim 13 , wherein said lithium salt or sodium salt is selected from lithium perchlorate, LiClO 4 , lithium hexafluorophosphate, LiPF 6 , lithium borofluoride, LiBF 4 , lithium hexafluoroarsenide, LiAsF 6 , lithium trifluoro-metasulfonate, LiCF 3 SO 3 , bis-trifluoromethyl sulfonylimide lithium, LiN(CF 3 SO 2 ) 2 , lithium bis(oxalato)borate, LiBOB, lithium oxalyldifluoroborate, LiBF 2 C 2 O 4 , lithium oxalyldifluoroborate, LiBF 2 C 2 O 4 , lithium nitrate, LiNO 3 , Li-Fluoroalkyl-Phosphates, LiPF 3 (CF 2 CF 3 ) 3 , lithium bisperfluoro-ethysulfonylimide, LiBETI, lithium bis(trifluoromethanesulphonyl)imide, lithium bis(fluorosulphonyl)imide, lithium trifluoromethanesulfonimide, LiTFSI, an ionic liquid-based lithium salt, sodium perchlorate, NaClO 4 , sodium hexafluorophosphate, NaPF 6 , sodium borofluoride, NaBF 4 , sodium hexafluoroarsenide, sodium trifluoro-metasulfonate, NaCF 3 SO 3 , bis-trifluoromethyl sulfonylimide sodium, NaN(CF 3 SO 2 ) 2 , sodium trifluoromethanesulfonimide, NaTFSI, bis-trifluoromethyl sulfonylimide sodium, NaN(CF 3 SO 2 ) 2 , or a combination thereof.

15. The process of claim 13 , wherein said solvent is selected from 1,3-dioxolane (DOL), 1,2-dimethoxyethane (DME), tetraethylene glycol dimethylether (TEGDME), poly(ethylene glycol) dimethyl ether (PEGDME), diethylene glycol dibutyl ether (DEGDBE), 2-ethoxyethyl ether (EEE), sulfone, sulfolane, ethylene carbonate (EC), dimethyl carbonate (DMC), methylethyl carbonate (MEC), diethyl carbonate (DEC), ethyl propionate, methyl propionate, propylene carbonate (PC), gamma-butyrolactone (γ-BL), acetonitrile (AN), ethyl acetate (EA), propyl formate (PF), methyl formate (MF), toluene, xylene, methyl acetate (MA), fluoroethylene carbonate (FEC), vinylene carbonate (VC), allyl ethyl carbonate (AEC), a hydrofluoroether, an ionic liquid solvent, or a combination thereof.

16. The process of claim 13 , which is a roll-to-roll process that includes preparing said working electrode in a roll form supported by a roller, and said step of bringing said working electrode and said counter electrode in contact with said electrolyte contains unwinding said working electrode from said roller, and feeding said working electrode into said electrolyte.

17. A process for producing a dendrite penetration-resistant layer for a rechargeable alkali metal, said process comprising (a) preparing a working electrode containing a porous structure of said multiple graphene sheets or exfoliated graphite flakes; (b) preparing a counter electrode containing lithium or sodium metal or alloy; and (c) bringing said working electrode and said counter electrode in physical contact with each other and in contact with an electrolyte containing a solvent and a lithium salt or sodium salt dissolved in said solvent; wherein said working electrode and said counter electrode are brought to b

Assignees

• Nanotek Instruments Inc
• Nonotek Instr Inc

Inventors

• Zhamu Aruna
• Jang Bor Z

Classifications

• H01M2004/027

  Negative electrodes · CPC title

• H01M4/382

  Lithium (H01M4/405 takes precedence) · CPC title

• H01M2/1646

  Electricity · mapped topic

• H01M10/054

  Accumulators with insertion or intercalation of metals other than lithium, e.g. with magnesium or aluminium · CPC title

• H01M4/1395

  of electrodes based on metals, Si or alloys · CPC title