Conductive material, electrode comprising the conductive material, secondary battery comprising the electrode, and method for preparing the conductive material
A conductive material, and a method for preparing the same are provided. The conductive material has a structure where a plurality of graphene sheets are interconnected, wherein an oxygen content is 1 wt % or higher based on the total weight of the conductive material, and a D/G peak ratio is 2.0 or less when the Raman spectrum is measured.
1. A conductive material comprising:
a structure where a plurality of graphene sheets are interconnected; and
a connecting part connected to at least a part of the plurality of graphene sheets,
wherein the connecting part is a carbon compound having a non-graphene form,
wherein an oxygen content is 1 wt % or higher based on a total weight of the conductive material; and
a D/G peak ratio is 2.0 or less as measured by the Raman spectrum,
wherein a longest length of the graphene sheet is 200 nm or less.
2. The conductive material of claim 1 , wherein a value calculated by the following Equation 1 is equal to 0.2 or less:
b
-
a
a
[
Equation
1
]
wherein, in the Equation 1 above, a is a specific surface area (m 2 /g) measured by the nitrogen adsorption BET method and b is an iodine adsorption value (mg/g) of the conductive material.
3. The conductive material of claim 1 , wherein at least a part of each of the plurality of graphene sheets is connected to the connecting part.
4. The conductive material of claim 1 , wherein an average thickness of the graphene sheet is 10 nm or less.
5. The conductive material of claim 1 , wherein a specific surface area (m 2 /g) of the conductive material measured by the nitrogen adsorption BET method is 200 m 2 /g or higher.
6. An electrode comprising at least one conductive material of claim 1 .
7. A secondary battery, comprising:
a positive electrode;
a negative electrode;
a separator interposed between the positive electrode and the negative electrode; and
an electrolyte, wherein at least one of the positive electrode and the negative electrode is an electrode of claim 6 .
8. A method for preparing the conductive material of claim 1 , the method comprising:
preparing a preliminary conductive material; and
transforming the preliminary conductive material by oxidation treatment, wherein the transforming the preliminary conductive material by oxidation treatment comprises at least one of the followings:
a) subjecting the preliminary conductive material to a first heat treatment in an oxygen atmosphere or air atmosphere at a temperature of 200° C. to 800° C.; or
b) reacting the preliminary conductive material with acidic vapor at 120° C. to 300° C.
9. (withdrawn — currently amended) The method of claim 8 , wherein preparing the preliminary conductive material comprises pyrolyzing acetylene gas at a temperature of 1,500° C. or higher.
10. The method of claim 8 , wherein the preliminary conductive material is at least any one selected from the group consisting of acetylene black, furnace black, thermal black, channel black, and lamp black.
11. The method of claim 10 , wherein the preliminary conductive material is acetylene black.
12. The method of claim 8 , further comprising, after the transforming the preliminary conductive material by oxidation treatment, subjecting the preliminary conductive material transformed by oxidation treatment to a second heat treatment at a temperature of 500° C. or higher in an inert atmosphere.