Composite negative active material and method of preparing the same, negative electrode including composite negative active material, and lithium secondary battery including negative electrode

1. A composite negative active material comprising:

a piezoelectric material;

a non-carbonaceous negative active material; and

a carbonaceous negative active material,

wherein the non-carbonaceous negative active material has a maximum volume expansion of about 10% or more during an electrochemical reaction,

wherein the non-carbonaceous negative active material comprises at least one selected from silicon, germanium, aluminum, tin, and a titanium oxide, and

wherein the carbonaceous negative active material is contained in an amount of 4 weight percent to about 75 weight percent, based on a total weight of the composite negative active material.

2. The composite negative active material of claim 1 , wherein

the piezoelectric material comprises at least one selected from BaTiO 3 , PbTiO 3 , Pb[Zr x T 1-x ]O 3 wherein 0≤x≤1, KNbO 3 , LiNbO 3 , LiTaO 3 , Na 2 WO 3 , and ZnO.

3. The composite negative active material of claim 1 , wherein

an amount of the piezoelectric material is in a range of about 1 weight percent to about 90 weight percent, based on a total weight of the composite negative active material.

4. The composite negative active material of claim 1 , wherein

the non-carbonaceous negative active material has a maximum volume expansion of about 50% or more during an electrochemical reaction.

5. The composite negative active material of claim 4 wherein

the non-carbonaceous negative active material has a maximum volume expansion of about 300% or more during an electrochemical reaction.

6. The composite negative active material of claim 1 , wherein

an amount of the non-carbonaceous negative active material is in a range of about 1 weight percent to about 90 weight percent, based on a total weight of the composite negative active material.

7. The composite negative active material of claim 1 , wherein

the piezoelectric material is contained in an amount of about 4 weight percent to about 70 weight percent,

the non-carbonaceous negative active material is contained in an amount of about 4 weight percent to about 70 weight percent, and

the carbonaceous negative active material is contained in an amount of about 1 weight percent to about 75 weight percent, each based on a total weight of the composite negative active material.

8. The composite negative active material of claim 1 , wherein each of the piezoelectric material, the non-carbonaceous negative active material, and the carbonaceous negative active material are a distinct phase.

9. The composite negative active material of claim 1 , wherein the carbonaceous negative active material comprises at least one selected from a carbon nanotube, graphite, graphene, carbon black, and a carbonized polymer.

10. A composite negative active material comprising:

a first phase comprising a piezoelectric material;

a second phase comprising a non-carbonaceous negative active material; and

a third phase comprising a carbonaceous negative active material,

wherein the non-carbonaceous negative active material has a maximum volume expansion of about 10% or more during an electrochemical reaction,

wherein the non-carbonaceous negative active material comprises at least one selected from silicon, germanium, aluminum, tin, and a titanium oxide, and

wherein the carbonaceous negative active material is contained in an amount of 4 weight percent to about 75 weight percent, based on a total weight of the composite negative active material.

11. The composite negative active material of claim 10 , wherein the first phase is contained in an amount of about 4 weight percent to about 70 weight percent,

the second phase is contained in an amount of about 4 weight percent to about 70 weight percent, and

the third phase is contained in an amount of weight percent to about 75 weight percent, each based on a total weight of the composite negative active material.

12. A negative electrode comprising a composite negative active material according to claim 1 .

13. A lithium secondary battery comprising the negative electrode according to claim 12 .

14. A method of preparing a composite negative active material, the method comprising:

contacting a piezoelectric material, a carbonaceous negative active material, and a non-carbonaceous negative active material to form the composite negative active material,

wherein the non-carbonaceous negative active material has a maximum volume expansion of about 10% or more during an electrochemical reaction,

wherein the non-carbonaceous negative active material comprises at least one selected from silicon, germanium, aluminum, tin, and a titanium oxide, and

wherein the carbonaceous negative active material is contained in an amount of 4 weight percent to about 75 weight percent, based on a total weight of the composite negative active material.

15. The method of claim 14 , further comprising including a conductive agent in the contacting.