Alkali metal-sulfur secondary battery containing a polymer-encapsulated sulfur cathode and manufacturing method

1. A rechargeable alkali metal-sulfur cell selected from lithium-sulfur cell, sodium-sulfur cell, or potassium-sulfur cell, said alkali metal-sulfur cell comprising:

(a) an anode active material layer and an optional anode current collector supporting said anode active material layer;

(b) a cathode active material layer and an optional cathode current collector supporting said cathode active material layer; and

(c) an electrolyte with an optional porous separator layer in ionic contact with said anode active material layer and said cathode active material layer;

wherein said cathode active material layer contains multiple particulates of a sulfur-containing material selected from a sulfur-carbon hybrid, sulfur-graphite hybrid, sulfur-graphene hybrid, conducting polymer-sulfur hybrid, metal sulfide, sulfur compound, or a combination thereof and wherein at least one of said particulates is composed of a plurality of sulfur-containing material particles being embraced or encapsulated by a thin layer of elastic polymer which elastically expands and contracts as the particulates expand and contract, said layer of an elastic polymer having a recoverable tensile strain from 2% to 200%, a lithium ion conductivity no less than 10 −6 S/cm at room temperature, and a thickness of the thin layer is from 0.5 nm to 10 μm, wherein said elastic polymer contains an ultrahigh molecular weight polymer having a molecular weight from 0.5×10 6 to 9×10 6 g/mole,

wherein said layer of elastic polymer is a composite of dispersed materials.

2. The rechargeable alkali metal-sulfur cell of claim 1 , wherein said ultrahigh molecular weight polymer is selected from polyacrylonitrile, polyethylene oxide, polypropylene oxide, polyethylene glycol, polyvinyl alcohol, polyacrylamide, poly(methyl methacrylate), poly(methyl ether acrylate), a copolymer thereof, a sulfonated derivative thereof, a chemical derivative thereof, and combinations thereof.

3. The rechargeable alkali metal-sulfur cell of claim 1 , wherein said ultrahigh molecular weight polymer contains from 0.1% to 50% by weight of a lithium ion-conducting additive or sodium-conducting additive dispersed therein, or contains therein from 0.1% by weight to 10% by weight of a reinforcement nano filament selected from carbon nanotube, carbon nano-fiber, graphene, and combinations thereof.

4. The rechargeable alkali metal-sulfur cell of claim 1 , wherein said ultrahigh molecular weight polymer is mixed with a lithium ion-conducting additive to form a composite wherein said lithium ion-conducting additive is dispersed in said ultrahigh molecular weight polymer and 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 , and combinations thereof, wherein X=F, Cl, I, or Br, R=a hydrocarbon group, and 1≤y≤4.

5. The rechargeable alkali metal-sulfur cell of claim 1 , wherein said ultrahigh molecular weight polymer is mixed with a lithium ion-conducting additive to form said composite wherein said lithium ion-conducting additive is dispersed in said ultrahigh molecular weight polymer and is selected from lithium perchlorate, lithium hexafluorophosphate, lithium borofluoride, lithium hexafluoroarsenide, lithium trifluoro-metasulfonate, bis-trifluoromethyl sulfonylimide lithium, lithium bis(oxalato)borate, lithium oxalyldifluoroborate, lithium nitrate, Li-fluoroalkyl-phosphates, lithium bisperfluoro-ethysulfonylimide, lithium bis(trifluoromethanesulfonyl)imide, lithium bis(fluorosulphonyl)imide, lithium trifluoromethanesulfonimide, an ionic liquid-based lithium salt, and combinations thereof.

6. The rechargeable alkali metal-sulfur cell of claim 1 , wherein said ultrahigh molecular weight polymer is mixed with an electron-conducting polymer selected from polyaniline, polypyrrole, polythiophene, polyfuran, a bi-cyclic polymer, a sulfonated derivative thereof, and combinations thereof.

7. The rechargeable alkali metal-sulfur cell of claim 1 , wherein the ultrahigh molecular weight polymer forms a mixture or blend with a lithium ion-conducting polymer selected from a lower molecular version of poly(ethylene oxide) (PEO), polypropylene oxide (PPO), poly(acrylonitrile) (PAN), poly(methyl methacrylate) (PMMA), poly(vinylidene fluoride) (PVdF), poly bis-methoxy ethoxyethoxide-phosphazene, polyvinyl chloride, polydimethylsiloxane, poly(vinylidene fluoride)-hexafluoropropylene (PVDF-HFP), a sulfonated derivative thereof, or a combination thereof, wherein said lower molecular version is defined as having a molecular weight less than 500,000 g/mole.

8. The rechargeable alkali metal-sulfur cell of claim 1 , wherein the lithium ion conductivity of said elastic polymer is in a range from 10 −5 S/cm to 5×10 −2 S/cm at room temperature.

9. The rechargeable alkali metal-sulfur cell of claim 1 , wherein said anode active material layer contains an anode active material selected from lithium metal, sodium metal, potassium metal, a lithium metal alloy, sodium metal alloy, potassium metal alloy, a lithium intercalation compound, a sodium intercalation compound, a potassium intercalation compound, a lithiated compound, a sodiated compound, a potassium-doped compound, lithiated titanium dioxide, lithium titanate, lithium manganate, a lithium transition metal oxide, Li 4 Ti 5 O 12 , and combinations thereof.

10. The rechargeable alkali metal-sulfur cell of claim 1 , wherein said cell is a lithium ion-sulfur cell and said anode active material layer contains an anode active material selected from the group consisting of:

(a) silicon (Si), germanium (Ge), tin (Sn), lead (Pb), antimony (Sb), bismuth (Bi), zinc (Zn), aluminum (Al), nickel (Ni), cobalt (Co), manganese (Mn), titanium (Ti), iron (Fe), and cadmium (Cd), and lithiated versions thereof;

(b) alloys or intermetallic compounds of Si, Ge, Sn, Pb, Sb, Bi, Zn, Al, or Cd with other elements, and lithiated versions thereof, wherein said alloys or compounds are stoichiometric or non-stoichiometric;

(c) oxides, carbides, nitrides, sulfides, phosphides, selenides, and tellurides of Si, Ge, Sn, Pb, Sb, Bi, Zn, Al, Fe, Ni, Co, Ti, Mn, or Cd, and their mixtures or composites, and lithiated versions thereof;

(d) salts and hydroxides of Sn and lithiated versions thereof;

(e) carbon or graphite materials and prelithiated versions thereof; and

combinations thereof.

11. The rechargeable alkali metal-sulfur cell of claim 1 , wherein said cell is a sodium ion-sulfur cell or potassium ion-sulfur cell and said anode active material layer contains an anode active material selected from the group consisting of:

(a) silicon (Si), germanium (Ge), tin (Sn), lead (Pb), antimony (Sb), bismuth (Bi), zinc (Zn), aluminum (Al), titanium (Ti), cobalt (Co), nickel (Ni), manganese (Mn), cadmium (Cd), and mixtures thereof, each of which is sodium- or potassium-doped;

(b) sodium- or potassium-containing alloys or intermetallic compounds of Si, Ge, Sn, Pb, Sb, Bi, Zn, Al, Ti, Co, Ni, Mn, Cd, and their mixtures;

(c) oxides, carbides, nitrides, sulfides, phosphides, selenides, tellurides, or antimonides of Si, Ge, Sn, Pb, Sb, Bi, Zn, Al, Fe, Ti, Co, Ni, Mn, Cd, and mixtures or composites thereof, each of which contains sodium or potassium,

(d) sodium or potassium salts;

(e) particles of graphite, hard carbon, soft carbon or carbon particles and pre-sodiated versions thereof; and

combinations thereof.

12. The rechargeable alkali metal-sulfur cell of claim 1 ,

wherein said particulates contain from 80% to 99% by weight of sulfur, metal sulfide, or metal compound based on the total weight of said elastic polymer and said sulfur, metal sulfide, or metal compound combined.

13. The rechargeable alkali metal-sulfur cell of claim 1 , wherein said cell has a sulfur utilization efficiency from 85% to 99%.

14. The rechargeable alkali metal-sulfur cell of claim 1 , wherein said sulfur-carbon hybrid, sulfur-graphite hybrid, sulfur-graphene hybrid, or conducting polymer-sulfur hybrid is a mixture, blend, composite, chemically or physically bonded entity of sulfur or sulfide with a carbon, graphite, graphene, or conducting polymer material.

15. The rechargeable alkali metal-sulfur cell of claim 1 , wherein said metal sulfide contains Li 2 S 1 , Li 2 S 2 , Li 2 S 3 , Li 2 S 4 , Li 2 S 5 , Li 2 S 6 , Li 2 S 7 , Li 2 S 8 , Li 2 S 9 , Li 2 S 10 , Na 2 S 1 , Na 2 S 2 , Na 2 S 3 , Na 2 S 4 , Na 2 S 5 , Na 2 S 6 , Na 2 S 7 , Na 2 S 8 , Na 2 S 9 , Na 2 S 10 , K 2 S 1 , K 2 S 2 , K 2 S 3 , K 2 S 4 , K 2 S 5 , K 2 S 6 , K 2 S 7 , K 2 S 8 , K 2 S 9 , or K 2 S 10 .

16. The rechargeable alkali metal-sulfur cell of claim 1 ,

wherein said carbon or graphite in said sulfur-containing material in said cathode active material layer is selected from meso-phase pitch, meso-phase carbon, meso carbon micro-bead (MCMB), coke particle, expanded graphite flake, artificial graphite particle, natural graphite particle, pyrolytic graphite, soft carbon particle, hard carbon particle, carbon nanotube, carbon nanofiber, carbon fiber, graphite nano-fiber, graphite fiber, carbonized polymer fiber, activated carbon, carbon black, and combinations thereof.

17. The rechargeable alkali metal-sulfur cell of claim 1 , wherein said graphene is selected from pristine graphene, graphene oxide, reduced graphene oxide (RGO), graphene fluoride, nitrogenated graphene, hydrogenated graphene, doped graphene, functionalized graphene, and combinations thereof.

18. The rechargeable alkali metal-sulfur cell of claim 1 , wherein said conducting polymer-sulfur hybrid contains an intrinsically conductive polymer selected from polyaniline, polypyrrole, polythiophene, polyfuran, a bi-cyclic polymer, a sulfonated derivative thereof, and combinations thereof.

19. The rechargeable alkali metal-sulfur cell of claim 1 , wherein said metal sulfide contains 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, and combinations thereof.

20. The rechargeable alkali metal-sulfur cell of claim 19 , wherein said metal element M is selected from Li, Na, K, Mg, Zn, Cu, Ti, Ni, Co, Fe, or Al.

21. The rechargeable alkali metal-sulfur cell of claim 1 , wherein said electrolyte is selected from polymer electrolyte, polymer gel electrolyte, composite electrolyte, ionic liquid electrolyte, organic liquid electrolyte, solid-state electrolyte, and combinations thereof.

22. The rechargeable alkali metal-sulfur cell of claim 1 , wherein said electrolyte contains a 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 nitrate (LiNO 3 ), LiPF 3 (CF 2 CF 3 ) 3 , lithium bisperfluoroethysulfonylimide (LiBETI), an ionic liquid 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 ), and combinations thereof.

23. The rechargeable alkali metal-sulfur cell of claim 22 , wherein a solvent used for said electrolyte is selected from ethylene carbonate (EC), dimethyl carbonate (DMC), methylethyl carbonate (MEC), diethyl carbonate (DEC), ethyl propionate, methyl propionate, propylene carbonate (PC), γ-butyrolactone (γ-BL), acetonitrile (AN), ethyl acetate (EA), propyl formate (PF), methyl formate (MF), toluene, xylene or methyl acetate (MA), fluoroethylene carbonate (FEC), vinylene carbonate (VC), allyl ethyl carbonate (AEC), 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, room temperature ionic liquid, and combinations thereof.