Separator for lithium metal based batteries

1. A modified separator for an electrochemical cell that cycles lithium ions, the modified separator comprising:

a polymeric separator comprising a doped substrate and a coating layer disposed thereon, wherein

the substrate is doped with a dopant selected from the group consisting of: aluminum oxide (Al 2 O 3 ), titanium dioxide (TiO 2 ), zirconium dioxide (ZrO 2 ), zinc oxide (ZnO), iron oxide (Fe 2 O 3 ), tin oxide (SnO), silicon oxide (SiO 2 ), tantalum oxide (Ta 2 O 5 ), lanthanum oxide (La 2 O 3 ), hydrofluoroolefin (HfO), cerium oxide (CeO 2 ), and combinations thereof and the dopant is mixed with one or more polymers of the polymeric separator, and

the coating layer is one of a polymeric-type coating layer and a ceramic-type metal oxide coating layer, wherein the ceramic-type metal oxide coating comprises at least one of the dopants; and

an electrolyte system having a viscosity ranging from about 50 mPa·s to about 500 mPa·s.

2. The modified separator of claim 1 , wherein the coating layer has a thickness ranging from about 1 nm to about 50 nm.

3. The modified separator of claim 2 , wherein the polymeric-type coating layer comprising one of an aluminum oxide composite (alucone) film, a zirconium alkoxide composite (zircone) film, a titanium alkoxide composite (titanicone) film, and a polyimide film.

4. The modified separator of claim 3 , wherein the polymeric-type coating layer is the aluminum oxide composite (alucone) film including a precursor material selected from the group consisting of: trimethylaluminum (TMA), ethylene glycol (EG), terephthaloyl chloride (TC), glycidol (GLY), hydroquinone (HQ), and combinations thereof.

5. The modified separator of claim 4 , wherein the modified separator has a melting point ranging from about 120° C. to about 200° C. and the precursor material includes a combination of trimethylaluminum (TMA) and ethylene glycol (EG).

6. The modified separator of claim 4 , wherein electrolyte system is one of an ether-based electrolyte system and a carbonate-based electrolyte system.

7. The modified separator of claim 3 , wherein the polymeric-type coating is a molecular layer deposition (MLD) coating layer.

8. The modified separator of claim 7 , wherein the ceramic-type metal oxide coating layer comprises a ceramic material selected from the group consisting of: aluminum oxide (Al 2 O 3 ), titanium dioxide (TiO 2 ), zirconium dioxide (ZrO 2 ), zinc oxide (ZnO), silicon oxide (SiO 2 ), and combinations thereof.

9. The modified separator of claim 8 , wherein the ceramic-type metal oxide coating is an atomic layer deposition (ALD) coating layer.

10. The modified separator of claim 1 , wherein the substrate comprises an amount of dopant ranging from about 1 g/m 2 to about 10 g/m 2 .

11. The modified separator of claim 10 , wherein the substrate comprises a polyolefin.

12. The modified separator of claim 1 , wherein the electrolyte system comprises:

a lithium salt selected from the group consisting of: lithium hexafluorophosphate (LiPF 6 ), lithium bis(fluorosulfonyl)imide (LiN(FSO 2 ) 2 ) (LiSFI), lithium bis(oxalato)borate (LiB(C 2 O 4 ) 2 ) (LiBOB), lithium difluorooxalatoborate (LiBF 2 (C 2 O 4 )), lithium perchlorate (LiClO 4 ), lithium tetrachloroaluminate (LiAlCl 4 ), lithium iodide (LiI), lithium bromide (LiBr), lithium thiocyanate (LiSCN), lithium tetrafluoroborate (LiBF 4 ), lithium tetraphenylborate (LiB(C 6 H 5 ) 4 ), lithium hexafluoroarsenate (LiAsF 6 ), lithium trifluoromethanesulfonate (LiCF 3 SO 3 ), bis(trifluoromethane)sulfonimide lithium salt (LiN(CF 3 SO 2 ) 2 ), and combinations; and

a solvent selected from the group consisting of: ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), fluoroethylene carbonate (FEC), dimethyl carbonate (DMC), diethyl carbonate (DEC), ethylmethylcarbonate (EMC), methyl formate, methyl acetate, methyl propionate, γ-butyrolactone, γ-valerolactone, 1,2-dimethoxyethane, 1,2-diethoxyethane, ethoxymethoxyethane, tetrahydrofuran, 2-methyltetrahydrofuran, 1,3-dioxolane, and combinations thereof.

13. A high-energy lithium metal based electrochemical cell comprising:

a polymeric separator comprising a substrate including a dopant and a polymeric-type coating layer disposed on the doped substrate,

wherein the dopant is selected from the group consisting of: aluminum oxide (Al 2 O 3 ), titanium dioxide (TiO 2 ), zirconium dioxide (ZrO 2 ), zinc oxide (ZnO), iron oxide (Fe 2 O 3 ), tin oxide (SnO), silicon oxide (SiO 2 ), tantalum oxide (Ta 2 O 5 ), lanthanum oxide (La 2 O 3 ), hydrofluoroolefin (HfO), cerium oxide (CeO 2 ), and combinations thereof,

the polymeric-type coating layer is an aluminum oxide composite (alucone) film including a precursor material comprising trimethylaluminum (TMA) and ethylene glycol (EG),

the polymeric-type coating layer has a thickness ranging from about 1 nm to about 50 nm,

the polymeric separator has a melting point ranging from about 120° C. to about 200° C., and

an electrode comprising a lithium metal-based electroactive material and having surfaces substantially free of dendrite formations.

14. The electrochemical cell of claim 13 , further comprising:

an electrolyte system having a viscosity ranging from about 50 mPa·s to about 500 mPa·s and comprising a lithium salt dissolved in an organic solvent, wherein the lithium salt has a concentration in the electrolyte system ranging from about 2 M to about 5 M.

15. The electrochemical cell of claim 13 , wherein the substrate comprises a polyolefin selected from the group consisting of: polyethylene (PE), polypropylene (PP), and combinations thereof, and

wherein the substrate includes from about 2 g/m 2 to about 5 g/m 2 of the dopant.

16. A method of making a coated separator, the method comprising:

disposing one of a polymeric-type coating layer and a ceramic-type metal oxide coating layer onto a doped polymeric separator having a sheet form, wherein the doped separator comprises a dopant selected from the group consisting of: aluminum oxide (Al 2 O 3 ); titanium dioxide (TiO 2 ); zirconium dioxide (ZrO 2 ); zinc oxide (ZnO); iron oxide (Fe 2 O 3 ); tin oxide (SnO); silicon oxide (SiO 2 ); tantalum oxide (Ta 2 O 5 ); lanthanum oxide (La 2 O 3 ); hydrofluoroolefin (HfO); cerium oxide (CeO 2 ); and combinations thereof, the dopant is mixed with one or more polymers of the polymeric separator, and the ceramic-type metal oxide coating comprises at least one dopant.

17. The method of claim 16 , wherein the coating layer has a thickness ranging from about 1 nm to about 50 nm, and

the coated separator further includes an electrolyte system having a viscosity ranging from about 50 mPa·s to about 500 mPa·s.

18. The method of claim 17 , wherein the ceramic-type metal oxide coating layer comprises a ceramic material selected from the group consisting of: aluminum oxide (Al 2 O 3 ); titanium dioxide (TiO 2 ); zirconium dioxide (ZrO 2 ); zinc oxide (ZnO); silicon oxide (SiO 2 ); and combinations thereof and is disposed onto the doped separator using atomic layer deposition (ALD).

19. The method of claim 17 , wherein the polymeric-type coating layer comprises one of an aluminum oxide composite (alucone) film, a zirconium alkoxide composite (zircone) film, a titanium alkoxide composite (titanicone) film, and a polyimide film and is disposed onto the doped separator using molecular layer deposition (MLD).

20. The method of claim 19 , wherein the polymeric-type coating layer is an alucone film and precursor material is selected from the group consisting of: trimethylaluminum (TMA), ethylene glycol (EG), terephthaloyl chloride (TC), glycidol (GLY), hydroquinone (HQ), and combinations thereof.