Negative electrode for metal battery, metal battery comprising the same, and method of preparing the negative electrode for metal battery

1. A negative electrode for a metal battery, the negative electrode comprising:

a metal substrate; and

a protective layer disposed directly on at least a portion of the metal substrate,

wherein the protective layer comprises an ion-conductive oligomer,

wherein the ion-conductive oligomer comprises an ion-conductive structural unit in at least one of a main chain and a side chain of the ion-conductive oligomer, and at least two hydrogen-bond-forming functional groups at different ends of the ion-conductive oligomer,

wherein the ion-conductive oligomer is represented by Formula 1 below and has a weight average molecular weight of about 100 grams per mole to about 5000 grams per mole:

wherein in Formula 1,

CY1 and CY2 are each independently a substituted or unsubstituted pyrimidinone, a substituted or unsubstituted pyrimidinol, a substituted or unsubstituted pyrimidine, a substituted or unsubstituted purinone, or a combination thereof,

A is a C1-C30 alkylene oxide group, —{Si(R)(R 1 )—O-} b —, or —(CH 2 CH 2 O) a -{Si(R)(R 1 )—O-} b —, wherein R and R 1 are each independently a hydrogen atom or a C1-C10 alkyl group and a and b are each independently an integer from 1 to 10,

L 1 and L 2 are each independently a single bond, —CO—, —C(O)O—, —CO—(R′)—CO—, —C(O)O—(R′ 1 )—C(O)O—, —CO—(R′ 2 )—C(O)O—, —C(O)O—(R′ 3 )—CO—, —(R′ 4 )—NHCO—, —(R′ 5 )—NHC(O)O—, —(R′ 6 )—NHC(O)O—(R′ 7 ), —NCO—(R′ 8 )—NCO—, —NCO—(R′ 9 )—CO—, —NCO—(R′ 10 )—C(O)O—, —CO—(R′ 11 )—NCO—, —C(O)O—(R′ 12 )—NCO—, or a combination thereof, wherein R′, R′ 1 , R′ 2 , R′ 3 , R′ 4 , R′ 5 , R′ 6 , R′ 7 , R′ 8 , R′ 9 , R′ 10 , R′ 11 , and R′ 12 are each independently a C1-C10 alkylene group, an amino group, or a C1-C10 aminoalkylene group,

L 1 is linked to a substituent of CY1,

L 2 is linked to a substituent of CY2, and

wherein the protective layer has a thickness of 5 micrometers or less.

2. The negative electrode of claim 1 , wherein the protective layer is a solid protective layer.

3. The negative electrode of claim 1 , wherein a Young's modulus of the protective layer is 50 megapascals or greater.

4. The negative electrode of claim 1 , wherein a melting point of the protective layer is greater than 60° C.

5. The negative electrode of claim 1 , wherein the main chain or the side chain of the ion-conductive oligomer is a C1-C30 alkylene oxide group, —{Si(R)(R 1 )—O-}—, —(CH 2 CH 2 O)—{Si(R)(R 1 )—O—}—, or —{CH(R 2 )C(R 3 )C(O)O(R 4 )}—,

wherein R, R 1 , R 2 , R 3 , and R 4 are each independently a hydrogen atom or a C1-C10 alkyl group.

6. The negative electrode of claim 1 , wherein the ion-conductive structural unit is a C1-C20 alkylene oxide group, —{Si(R)(R 1 )—O-}—, or —(CH 2 CH 2 O)—{Si(R)(R 1 )—O-}—,

wherein R and R 1 are each independently a hydrogen atom or a C1-C10 alkyl group.

7. The negative electrode of claim 1 , wherein the hydrogen-bond-forming functional group is a substituted or unsubstituted pyrimidinone, a substituted or unsubstituted pyrimidinol, a substituted or unsubstituted pyrimidine, a substituted or unsubstituted triazine, a substituted or unsubstituted pyridyl, a substituted or unsubstituted benzimidazole, a substituted or unsubstituted naphthyridine, a substituted or unsubstituted purinone, or a combination thereof.

8. The negative electrode of claim 1 ,

wherein CY1 and CY2 are each substituted with a —NH 2 group,

wherein L 1 and L 2 are each independently linked to an —NH 2 substituent of CY1 and CY2.

9. The negative electrode of claim 1 , wherein CY1 and CY2 are each independently represented by Formula 2, Formula 3, or Formula 4:

wherein, in Formula 2,

R a , R b , R c , and R d are each independently a hydrogen atom, a halogen atom, a cyano group, a hydroxyl group, —NH 2 , —C(O)R″, —C(O)OR″, —OCO(OR″), —C═N(R″), a substituted or unsubstituted C1-C10 alkyl group, a substituted or unsubstituted C1-C10 alkoxy group, a substituted or unsubstituted C2-C10 alkenyl group, a substituted or unsubstituted C2-C10 alkynyl group, a C2-C10 alkylene oxide group, a substituted or unsubstituted C3-C20 cycloalkyl group, a substituted or unsubstituted C6-C20 aryl group, a substituted or unsubstituted C6-C20 aryloxy group, a substituted or unsubstituted C6-C20 heteroaryl group, or a combination thereof, wherein R″ is a hydrogen atom, a C1-C10 alkyl group, or a C6-C20 aryl group, and

at least one of R a , R b , R c , and R d is —NH 2 ,

wherein, Formula 3,

R e , R f , R g , and R i are each independently a hydrogen atom, a halogen atom, a cyano group, a hydroxyl group, —NH 2 , —C(O)R″, —C(O)OR″, —OCO(OR″), —C═N(R″), a substituted or unsubstituted C1-C10 alkyl group, a substituted or unsubstituted C1-C10 alkoxy group, a substituted or unsubstituted C2-C10 alkenyl group, a substituted or unsubstituted C2-C10 alkynyl group, a C2-C10 alkylene oxide group, a substituted or unsubstituted C3-C20 cycloalkyl group, a substituted or unsubstituted C6-C20 aryl group, a substituted or unsubstituted C6-C20 aryloxy group, a substituted or unsubstituted C6-C20 heteroaryl group, or a combination thereof, wherein R″ is a hydrogen atom, a C1-C10 alkyl group, or a C6-C20 aryl group, and

at least one of R e , R f , R g , and R i is —NH 2 ,

wherein, in Formula 4,

R j , R k , R l , R m , R n , R o , R p , and R q are each independently a hydrogen atom, a halogen atom, a cyano group, a hydroxyl group, —NH 2 , —C(O)R″, —C(O)OR″, —OCO(OR″), —C═N(R″), a substituted or unsubstituted C1-C10 alkyl group, a substituted or unsubstituted C1-C10 alkoxy group, a substituted or unsubstituted C2-C10 alkenyl group, a substituted or unsubstituted C2-C10 alkynyl group, a C2-C10 alkylene oxide group, a substituted or unsubstituted C3-C20 cycloalkyl group, a substituted or unsubstituted C6-C20 aryl group, a substituted or unsubstituted C6-C20 aryloxy group, a substituted or unsubstituted C6-C20 heteroaryl group, or a combination thereof, wherein R″ is a hydrogen atom, a C1-C10 alkyl group, or a C6-C20 aryl group, and

at least one of R j , R k , R l , R m , R n , R o , R p , and R q is —NH 2 .

10. The negative electrode of claim 1 , wherein a radius of gyration of the ion-conductive oligomer is 3 nanometers or less.

11. The negative electrode of claim 1 , wherein the protective layer further comprises a lithium salt.

12. The negative electrode of claim 11 , wherein the lithium salt comprises LiSCN, LiN(CN) 2 , LiClO 4 , LiI, LiBF 4 , LiAsF 6 , LiPF 6 , LiCF 3 SO 3 , LiC(CF 3 SO 2 ) 3 , LiN(SO 2 C 2 F 5 ) 2 , LiN(SO 2 CF 3 ) 2 , LiN(SO 2 F) 2 , LiSbF 6 , LiPF 3 (CF 2 CF 3 ) 3 , LiPF 3 (CF 3 ) 3 , LiB(C 2 O 4 ) 2 , or a combination thereof.

13. The negative electrode of claim 1 , wherein the protective layer further comprises an organic particle, an inorganic particle, an organic-inorganic particle, or combination thereof, each having a particle diameter greater than 1 micrometer and equal to or less than 100 micrometers.

14. The negative electrode of claim 13 , wherein the particle comprises polystyrene, a copolymer comprising a styrene repeating unit, a copolymer comprising a repeating unit having a crosslinkable functional group, a crosslinked polymer, or a combination thereof.

15. A metal battery comprising:

a positive electrode;

the negative electrode according to claim 1 ; and

an electrolyte disposed between the positive electrode and the negative electrode.

16. The metal battery of claim 15 , wherein the electrolyte comprises a liquid electrolyte, a solid electrolyte, a gel electrolyte, a polymeric ionic liquid, or a combination thereof.

17. The metal battery of claim 16 , wherein the liquid electrolyte comprises a lithium salt and an organic solvent.

18. The metal battery of claim 17 , wherein the lithium salt has a concentration of about 0.1 molar to about 4 molar.

19. The metal battery of claim 17 , wherein the organic solvent comprises ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, ethylmethyl carbonate, fluoroethylene carbonate, gamma-butyro lactone, dimethoxyethane, diethoxyethane, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, polyethylene glycol dimethyl ether, succinonitrile, sulforane, dimethyl sulfone, ethylmethyl sulfone, diethyl sulfone, adiponitrile, tetraethylene glycol dimethyl ether, 1,1,2,2-tetrafluoroethyl 2,2,3,3-tetrafluoropropyl ether, or a combination thereof.

20. The metal battery of claim 15 , wherein an electrodeposition density of lithium in the metal battery is from about 0.5 grams per cubic centimeter to about 0.53 grams per cubic centimeter.

21. The metal battery of claim 15 , wherein the protective layer of the negative electrode has an average thickness deviation of about 0.1 micrometer to about 2 micrometers.

22. The metal battery of claim 15 , further comprising a separator.

23. A method of preparing a negative electrode for a metal battery, the method comprising:

providing a protective layer forming composition comprising an ion-conductive oligomer;

applying, on at least a portion of a metal substrate, the protective layer forming composition to form a coating; and

drying the coating to prepare the negative electrode of claim 1 .