Composite solid electrolyte, protected anode and lithium battery including the same, and method of preparing the composite solid electrolyte

1. A composite solid electrolyte comprising:

a lithium ion conductive solid electrolyte; and

a polymer-containing electrolyte coating layer on a surface of the lithium ion conductive solid electrolyte,

wherein the polymer-containing electrolyte coating layer comprises an ion conductive polymer having an alkylene oxide segment, wherein the polymer-containing electrolyte coating layer has a thickness of about 40 micrometers or less,

wherein the lithium ion conductive solid electrolyte is porous,

wherein the lithium ion conductive solid electrolyte comprises a ceramic composite represented by Formula 1:

Li 1+x Al y Ge z (M2) w P 3+s O 12+t   Formula 1

wherein M2 is at least one selected from titanium, tantalum, and zirconium, and

0≤x≤1, 0≤y≤1, 0<z≤1, 0≤w≤2, 0≤s≤1, and 0≤t≤1, and

wherein the polymer-containing electrolyte coating layer further comprises at least one selected from inorganic particles, and a solvate ionic liquid comprising a lithium salt and a glyme.

2. The composite solid electrolyte of claim 1 , wherein the ion conductive polymer is at least one selected from polyethylene oxide, polypropylene oxide, polybutylene oxide, a polyethylene oxide-polypropylene oxide blend, a polyethylene oxide-polybutylene oxide blend, a polyethylene oxide-polypropylene oxide-polybutylene oxide blend, a polyethylene oxide-polypropylene oxide block copolymer, a polyethylene oxide-polybutylene oxide block copolymer, a polyethylene oxide-polypropylene oxide-polybutylene oxide block copolymer, a polybutylene oxide-polyethylene oxide-polybutylene oxide block copolymer, a polyethylene oxide-polybutylene oxide-polyethylene oxide block copolymer, polyethylene oxide-grafted polymethyl methacrylate, polypropylene oxide-grafted polymethyl methacrylate, and polybutylene oxide-grafted polymethyl methacrylate.

3. The composite solid electrolyte of claim 1 , wherein the ion conductive polymer is at least one selected from polyethylene oxide, polypropylene oxide, a polyethylene oxide-polypropylene oxide blend, a polyethylene oxide-polypropylene oxide block copolymer, and a polyethylene oxide-polypropylene oxide-polyethylene oxide block copolymer.

4. The composite solid electrolyte of claim 1 , wherein the ion conductive polymer has a weight average molecular weight of about 100,000 Daltons to about 1,000,000 Daltons.

5. The composite solid electrolyte of claim 1 , wherein the inorganic particles comprise at least one selected from BaTiO 3 , Al 2 O 3 , ZnO, SiO 2 , TiO 2 , ZrO 2 , a zeolite, a metal-organic framework, and a polyhedral oligomeric silsesquioxane.

6. The composite solid electrolyte of claim 1 , wherein the inorganic particles have a particle diameter of about 500 nanometers or less.

7. The composite solid electrolyte of claim 1 , wherein an amount of the inorganic particles is from about 5 weight percent to about 15 weight percent, based on a total weight of the ion conductive polymer.

8. The composite solid electrolyte of claim 1 , wherein the lithium salt is at least one selected from LiSCN, LiN(CN) 2 , LiClO 4 , LiBF 4 , LiAsF 6 , LiPF 6 , LiCF 3 SO 3 , Li(FSO 2 ) 2 N, Li(CF 3 SO 2 ) 3 C, LiN(SO 2 CF 3 ) 2 , LiN(SO 2 CF 2 CF 3 ) 2 , LiSbF 6 , LiPF 3 (CF 2 CF 3 ) 3 , LiPF 3 (C 2 F 5 ) 3 , LiPF 3 (CF 3 ) 3 , and LiB(C 2 O 4 ) 2 .

9. The composite solid electrolyte of claim 1 , wherein the glyme is at least one selected from a monoglyme, a diglyme, a triglyme, and a tetraglyme.

10. The composite solid electrolyte of claim 1 , wherein a molar ratio of the lithium salt and the glyme in the solvate ionic liquid is from about 1:1 to about 1:4.

11. The composite solid electrolyte of claim 1 , wherein the lithium ion conductive solid electrolyte further comprises a ceramic composite represented by Formula 2:

Li 7−a La 3−a (M3) a Zr 2+b C 12+c   Formula 2

wherein M3 is at least one selected from aluminum and cerium, and

0≤a≤1, 0≤b≤1, and 0≤c≤1.

12. The composite solid electrolyte of claim 1 , wherein the lithium ion conductive solid electrolyte further comprises a cross-linkable polymer, and

wherein the cross-linkable polymer is disposed in a pore of the lithium ion conductive solid electrolyte.

13. The composite solid electrolyte of claim 1 , wherein the composite solid electrolyte has an ionic conductivity of 1×10 −4 Siemens per centimeter or more at 25° C.

14. A protected anode comprising:

an anode comprising lithium metal or a lithium alloy; and

the composite solid electrolyte according to claim 1 ,

wherein the polymer-containing electrolyte coating layer of the composite solid electrolyte contacts the anode.

15. The protected anode of claim 14 , wherein, when determined in a Nyquist plot obtained from impedance measurement, an interfacial resistance at 25° C. between the anode and the composite solid electrolyte is one-fourth or less of an interfacial resistance at 25° C. between the anode and the lithium ion conductive solid electrolyte.

16. The protected anode of claim 14 , wherein a dendrite is not present at a surface of the protected anode after treatment at 25° C. and a current density of 1.0 mA/cm 2 for 40 hours.

17. A lithium battery comprising the protected anode according to claim 14 and a cathode.

18. The lithium battery of claim 17 , further comprising, between the protected anode and the cathode, at least one intermediate layer selected from a separator and a liquid electrolyte.

19. The lithium battery of claim 17 , wherein the lithium battery is a lithium metal battery or a lithium air battery.

20. The lithium battery of claim 17 , wherein the lithium battery is a solid state lithium battery and does not comprise a solvent.

21. A method of preparing the composite solid electrolyte according to claim 1 , the method comprising:

coating a surface of a lithium ion conductive solid electrolyte with a composition for forming a polymer-containing electrolyte coating layer to form a polymer-containing electrolyte coating layer on the surface of the lithium ion conductive solid electrolyte;

drying the coated lithium ion conductive solid electrolyte to prepare the composite solid electrolyte; and

resulting in the composite solid electrolyte according to claim 1 .

22. The method of claim 21 , wherein the coating is performed by solution casting, spray coating, bar coating, dip coating, or spin coating.