Electrode mixture, preparation method thereof, and secondary battery including the same
An electrode mixture of the present invention comprises: an electrode active material; a binder; and a conductive material. When a cross-section of the electrode mixture is imaged such that a pixel filled 100% with a conductive material among a plurality of divided pixels is considered to be a condensed pixel and a value obtained by counting condensed pixels is considered to be the degree of agglomeration, the degree of agglomeration of a conductive material in the electrode mixture in the depth direction of the electrode mixture has a standard deviation less than 3.0. The electrode mixture as described above includes a conductive material uniformly distributed therein and thus has low electrode resistance. Therefore, the electrode mixture can improve output and lifespan properties of a lithium secondary battery to which the electrode mixture has been applied.
1. A method of preparing an electrode mixture, comprising:
preparing a pre-dispersed slurry by mixing a binder and a conductive material with an organic solvent;
preparing an electrode slurry by adding an electrode active material to the pre-dispersed slurry;
applying the electrode slurry on a current collector; and
drying the electrode slurry applied on the current collector,
wherein, when a cross-section of the electrode mixture is imaged such that a pixel filled 100% with the conductive material among a plurality of divided pixels is considered to be a condensed pixel and a value obtained by counting condensed pixels is considered to be a degree of agglomeration, the degree of agglomeration of the conductive material in the electrode mixture in a depth direction of the electrode mixture has a standard deviation of less than 3.0, and a maximum degree of agglomeration of the conductive material is less than 10,
wherein the conductive material has a DBP absorption amount of 218 to 267 ml/100 g; a particle diameter of 25 to 35 nm; and a BET specific surface area of 50 to 135 m 2 /g.
2. The method of claim 1 , wherein the pre-dispersed slurry has a solid content of 5 to 15 wt %.
3. The method of claim 1 , wherein the electrode slurry has a solid content of 50 to 70 wt %.
4. The method of claim 1 , wherein the drying is performed at 110 to 150° C.
5. The method of claim 1 , wherein the drying is performed at 120 to 140° C.