Alkali metal-sulfur secondary battery containing a pre-sulfurized cathode and production process

Patent metadata

Field	Value
Publication number	US-2016240840-A1
Application number	US-201514544760-A
Country	US
Kind code	A1
Filing date	Feb 18, 2015
Priority date	Feb 18, 2015
Publication date	Aug 18, 2016
Grant date	—

Abstract

A method of producing a pre-sulfurized active cathode layer for a rechargeable alkali metal-sulfur cell; the method comprising: (a) Preparing an integral layer of meso-porous structure of a carbon, graphite, metal, or conductive polymer having a specific surface area greater than 100 m 2 /g; (b) Preparing an electrolyte comprising a solvent and a sulfur source; (c) Preparing an anode; and (d) Bringing the integral layer and the anode in ionic contact with the electrolyte and imposing an electric current between the anode and the integral layer (serving as a cathode) to electrochemically deposit nano-scaled sulfur particles or coating on the graphene surfaces. The sulfur particles or coating have a thickness or diameter smaller than 20 nm (preferably <10 nm, more preferably <5 nm or even <3 nm) and occupy a weight fraction of at least 70% (preferably >90% or even >95%).

First claim

1 . An electrochemical method of producing a pre-sulfurized active cathode layer for a rechargeable alkali metal-sulfur cell, said method comprising:
(a) Preparing an integral layer of a meso-porous structure of a carbon, graphite, metal, or conductive polymer, wherein said meso-porous structure has meso-scaled pores of 2-50 nm and a specific surface area greater than 100 m 2 /g and wherein said carbon, graphite, metal, or conductive polymer is selected from chemically etched or expanded soft carbon, chemically etched or expanded hard carbon, exfoliated activated carbon, chemically etched or expanded carbon black, chemically etched multi-walled carbon nanotube, nitrogen-doped carbon nanotube, boron-doped carbon nanotube, chemically doped carbon nanotube, ion-implanted carbon nanotube, chemically treated multi-walled carbon nanotube with an inter-planar separation no less than 0.4 nm, chemically expanded carbon nano-fiber, chemically activated carbon nano-tube, chemically treated carbon fiber, chemically activated graphite fiber, chemically activated carbonized polymer fiber, chemically treated coke, activated meso-phase carbon, meso-porous carbon, electro-spun conductive nano fiber, highly separated vapor-grown carbon or graphite nano fiber, highly separated carbon nano-tube, carbon nanowire, metal nano wire, metal-coated nanowire or nano-fiber, conductive polymer-coated nanowire or nano-fiber, or a combination thereof, and wherein said meso-porous structure contains 0-49% by weight of sulfur or sulfur-containing compound pre-loaded therein and an optional binder material of 0-10% by weight; (b) Preparing an electrolyte comprising a non-aqueous solvent and a sulfur source dissolved or dispersed in said solvent; (c) Preparing an anode; and (d) Bringing said integral layer of meso-porous structure and said anode in ionic contact with said electrolyte and imposing an electric current between said anode and said integral layer of meso-porous structure, serving as a cathode, with a sufficient current density for a sufficient period of time to electrochemically deposit nano-scaled sulfur particles or coating in said meso-pores to form said pre-sulfurized active cathode layer, wherein said particles or coating have a thickness or diameter smaller than 20 nm.

2 . The method of claim 1 , wherein said sulfur source is selected from M x S y , wherein x is an integer from 1 to 3 and y is an integer from 1 to 10, and M is a metal element selected from an alkali metal, an alkaline metal selected from Mg or Ca, a transition metal, a metal from groups 13 to 17 of the periodic table, or a combination thereof.

3 . The method of claim 1 , wherein said anode comprises an anode active material selected from an alkali metal, an alkaline metal, a transition metal, a metal from groups 13 to 17 of the periodic table, or a combination thereof.

4 . The method of claim 2 , wherein said metal element M is selected from Li, Na, K, Mg, Zn, Cu, Ti, Ni, Co, Fe, or Al.

5 . The method of claim 2 , wherein said M x S y is selected from Li 2 S 6 , Li 2 S 7 , Li 2 S 8 , Li 2 S 9 , Li 2 S 10 , Na 2 S 6 , Na 2 S 7 , Na 2 S 8 , Na 2 S 9 , Na 2 S 10 , K 2 S 6 , K 2 S 7 , K 2 S 8 , K 2 S 9 , or K 2 S 10 .

6 . The method of claim 1 , further comprising a procedure of depositing an element Z to said meso-porous structure wherein said element Z is mixed with sulfur or formed as discrete Z coating or particles having a dimension less than 100 nm and said Z element is selected from Sn, Sb, Bi, Se, and/or Te, and the weight of Z is less than the weight of sulfur.

7 . The method of claim 6 , wherein said procedure of depositing element Z includes electrochemical deposition, chemical deposition, or solution deposition.

8 . The method of claim 1 , wherein said nano-scaled sulfur particles or coating occupy a weight fraction of at least 70% based on the total weights of said sulfur particles or coating and said carbon, graphite, metal or polymer material combined.

9 . The method of claim 1 , wherein said electrolyte further comprises a metal salt 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 ), potassium perchlorate (KClO 4 ), sodium hexafluorophosphate (NaPF 6 ), potassium hexafluorophosphate (KPF 6 ), sodium borofluoride (NaBF 4 ), potassium borofluoride (KBF 4 ), sodium hexafluoroarsenide, potassium hexafluoroarsenide, sodium trifluoro-metasulfonate (NaCF 3 SO 3 ), potassium trifluoro-metasulfonate (KCF 3 SO 3 ), bis-trifluoromethyl sulfonylimide sodium (NaN(CF 3 SO 2 ) 2 ), sodium trifluoromethanesulfonimide (NaTFSI), bis-trifluoromethyl sulfonylimide potassium (KN(CF 3 SO 2 ) 2 ), or a combination thereof.

10 . The method of claim 1 , 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, a room temperature ionic liquid solvent, or a combination thereof.

11 . The method of claim 1 , wherein said anode, said electrolyte, and said integral layer of meso-porous structure are disposed in an external container outside of an alkali metal-sulfur cell and said step of electrochemically depositing nano-scaled sulfur particles or coating in said meso-scaled pores is conducted outside said alkali metal-sulfur cell.

12 . The method of claim 1 , wherein said anode, said electrolyte, and said integral layer of meso-porous structure are disposed inside an alkali metal-sulfur cell and said step of electrochemically depositing nano-scaled sulfur particles or coating in said meso-scaled pores is conducted after said alkali metal-sulfur cell is fabricated.

13 . The method of claim 1 , wherein said anode, said electrolyte, and said integral layer of meso-porous structure are part of an alkali metal-sulfur cell and said step of electrochemically depositing nano-scaled sulfur particles or coating in said meso-scaled pores occurs after said alkali metal-sulfur cell is fabricated and is conducted during a first charge cycle of said cell.

14 . The method of claim 1 , wherein said nano-scaled sulfur particles or coating occupy a weight fraction of at least 80%.

15 . The method of claim 1 , wherein said nano-scaled sulfur particles or coating occupy a weight fraction of at least 90%.

16 . The method of claim 1 , wherein said nano-scaled sulfur particles or coating have a thickness or diameter smaller than 10 nm.

17 . The method of claim 1 , wherein said nano-scaled sulfur

Assignees

• He Hui
• Zhamu Aruna
• Jang Bor Z

Inventors

• He Hui
• Zhamu Aruna
• Jang Bor Z

Classifications

• H01M4/13

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

• H01M10/052

  Li-accumulators · CPC title

• H01M10/0568

  characterised by the solutes · CPC title

• H01M4/5815

  Sulfides · CPC title

• H01M2300/0025

  Organic electrolyte · CPC title