Anode, lithium battery including anode, and method of preparing anode

1. A lithium battery comprising:

a cathode;

an anode comprising

a current collector,

a first anode layer disposed on the current collector,

a second anode layer disposed on the first anode layer, and

an inorganic protection layer disposed on the second anode layer,

wherein the first anode layer is between the current collector and the second anode layer,

wherein the second anode layer comprises lithium metal or a lithium metal alloy and is between the first anode layer and the inorganic protection layer,

wherein an oxidation/reduction potential of the first anode layer and an oxidation/reduction potential of the second anode layer are different from each other,

wherein a thickness of the first anode layer is less than a thickness of the second anode layer; and

an electrolyte between the cathode and the anode,

wherein the thickness of the first anode layer is about 100 nanometers to about 2 micrometers, and the thickness of the second anode layer is about 1 micron to about 100 microns; and

wherein the first anode layer comprises a lithium titanium oxide represented by Formula 1:

Li 4+a Ti 5−b M c O 12−d   Formula 1

wherein, in Formula 1, −0.2<a<0.2, −0.3<b<0.3, 0<c<0.3, and −0.3<d<0.3; and M is at least one metal of Group 1 to 6, 8, and 12 to 15.

2. The lithium battery of claim 1 , wherein the first anode layer is a non-consumable anode layer having an oxidation/reduction potential greater than that of the second anode layer, wherein a thickness of the first anode layer is independent of the number of charge/discharge cycles.

3. The lithium battery of claim 1 , wherein the first anode layer comprises a compound having a spinel crystal structure.

4. The lithium battery of claim 1 , wherein the second anode layer is a consumable anode layer, wherein a thickness of the second anode layer is dependent on the number of charge/discharge cycles.

5. The lithium battery of claim 1 , wherein a density of the lithium metal or the lithium alloy is about 0.5 grams per cubic centimeter or less.

6. The lithium battery of claim 1 , wherein the inorganic protection layer is a solvent-impermeable layer substantially free of a pin-hole or a grain boundary.

7. The lithium battery of claim 1 , wherein the inorganic protection layer comprises a metal oxide, a metal nitride, a metal nitrate, a metal carbide, a lithiated compound thereof, or a combination thereof; or a ceramic electrolyte.

8. The lithium battery of claim 1 , wherein the inorganic protection layer comprises

alumina, silica, titania, HfO 2 , SrTiO 3 , SnO 2 , CeO 2 , Na 2 O, MgO, NiO, CaO, BaO, ZnO, ZrO 2 , Y 2 O 3 , BaTiO 3 , Li 2 O, RaO, CaO, SrO, Sc 2 O 3 , Ce 2 O 3 , or silsesquioxane having a cage structure;

ZrN, TaN, HfN, VN, NbN, Cr 2 N, TaN, CrN, GeN, TLi 3 N, Mg 3 N 2 , Ca 3 N 2 , Sr 3 N 2 , Ba 3 N 2 , BN, AlN, or TiN;

tantalum oxynitride, a zirconium oxynitride, or lithium phosphorus oxynitride;

TiC, ZrC, HfC, NbC, TaC, Cr 3 C 2 , Mo 2 C, WC, or SiC;

a metal-organic framework;

a lithiated compound of any of the above; or

Li 1+x+y Al x Ti 2−x Si y P 3−y O 12 , where 0<x<2 and 0≤y<3, BaTiO 3 , Pb(Zr x Ti 1−x )O 3 wherein 0≤x<1, Pb 1−x La x Zr 1−y Ti y O 3 (where 0≤x<1 and 0≤y<1), Pb(Mg 3 Nb 2/3 )O 3 —PbTiO 3 , lithium phosphate, a lithium titanium phosphate, a lithium aluminum titanium phosphate, Li 1+x+y (Al a Ga 1−a ) x (Ti b Ge 1−b ) 2−x Si y P 3−y O 12 , where in 0≤x≤1, 0≤y≤1, 0≤a<1, and 0≤b<1, a lithium lanthanum titanate, a lithium germanium thiophosphate, a lithium nitride, a silicon sulfur glass, a phosphorus sulfur glass, a Li 2 O—Al 2 O 3 —SiO 2 —P 2 O 5 —TiO 2 —GeO 2 ceramic, or a Garnet ceramic.

9. The lithium battery of claim 1 , wherein a thickness of the inorganic protection layer is about 100 nanometers or less.

10. The lithium battery of claim 1 , wherein the inorganic protection layer is a flexible layer that is bendable.

11. The lithium battery of claim 1 , wherein the second anode layer is a lithium metal layer, and the inorganic protection layer is an alumina layer free of a pin-hole.

12. The lithium battery of claim 1 , wherein the electrolyte comprises:

a single layer structure comprising a first liquid electrolyte layer in contact with an inorganic protection layer of the anode and comprising a first liquid electrolyte;

a single layer structure comprising a first liquid electrolyte layer in contact with the inorganic protection layer of the anode and comprising a separator and a first liquid electrolyte impregnated in the separator;

a single layer structure comprising a first solid electrolyte layer in contact with the inorganic protection layer of the anode and comprising a polymer electrolyte;

a multi-layer structure comprising a first liquid electrolyte layer in contact with the inorganic protection layer of the anode and comprising a separator and a first liquid electrolyte impregnated in the separator, a second solid electrolyte layer in contact with the first liquid electrolyte layer and comprising a ceramic conductor, and a second liquid electrolyte layer in contact with the second solid electrolyte layer and comprising a second liquid electrolyte;

a multi-layer structure comprising a first solid electrolyte layer in contact with the inorganic protection layer of the anode and comprising a polymer electrolyte, a second solid electrolyte layer in contact with the first solid electrolyte layer and comprising a ceramic conductor, and a second liquid electrolyte layer in contact with the second solid electrolyte layer and comprising a second liquid electrolyte;

a multi-layer structure comprising a first solid electrolyte layer in contact with the inorganic protection layer of the anode and comprising a polymer electrolyte, a first liquid electrolyte layer in contact with the first solid electrolyte layer and comprising a separator and a first liquid electrolyte impregnated in the separator, a second solid electrolyte layer in contact with the first liquid electrolyte layer and comprising a ceramic conductor, and a second liquid electrolyte layer in contact with the second solid electrolyte layer and comprising a second liquid electrolyte; or

a multi-layer structure comprising a second solid electrolyte layer in contact with the inorganic protection layer of the anode and comprising a ceramic conductor, and further comprising a second liquid electrolyte layer in contact with the second solid electrolyte layer.

13. A method of preparing an anode, the method comprising:

disposing a first anode layer on a current collector;

disposing, on the first anode layer, a second anode layer having an oxidation/reduction potential different from that of the first anode layer; and

disposing an inorganic protection layer on the second anode layer,

wherein the inorganic protection layer is disposed by atomic layer deposition to a thickness of about 100 nanometers or less,

wherein the first anode layer is between the current collector and the second anode layer,

wherein the second anode layer is between the first anode layer and the inorganic protection layer,

wherein a thickness of the first anode layer is less than a thickness of the second anode layer,

wherein the thickness of the first anode layer is about 100 nanometers to about 2 micrometers, and the thickness of the second anode layer is about 1 micron to about 100 microns; and

wherein the first anode layer comprises a lithium titanium oxide represented by

Li 4+a Ti 5−b M c O 12−d   Formula 1

wherein, in Formula 1, −0.2<a<0.2, −0.3<b<0.3, 0<c<0.3, and −0.3<d<0.3; and M is at least one metal of Group 1 to 6, 8, and 12 to 15.

14. The method of claim 13 , wherein the first anode layer is disposed by coating, sputtering, chemical vapor deposition, physical vapor deposition, or atomic layer deposition, and the second anode layer comprises lithium metal and is disposed by plating such that the second anode layer has a density of about 5 grams per cubic centimeter or less.

15. The lithium battery of claim 1 , wherein the second anode layer has a thickness of about 2 microns to about 18 microns.