Method for monitoring dry state of electrode substrate

1. A method for monitoring a dry state of an electrode substrate in which electrode slurry having a solid content is applied to a collector, comprising:

emitting light onto a surface of the electrode substrate;

receiving light reflected by the surface of the electrode substrate; and

analyzing a luminous intensity or a spectrum of the received light to estimate a drying rate of the electrode substrate based on the solid content of the electrode substrate,

wherein the light emitted onto the surface of the electrode substrate is light having a visible ray band wherein the electrode slurry comprises a reference material that is changed in a reflection characteristic according to the dry state.

2. The method of claim 1 , wherein,

when the electrode slurry reaches a drying rate within a specific range,

the reflection characteristic of the reference material has a section in which the electrode slurry is more sharply changed than that when the electrode slurry is in a drying rate within a different range.

3. The method of claim 1 , wherein the reference material is graphite.

4. The method of claim 1 , wherein,

the reflection characteristic of the received light is compared with reference data to estimate the drying rate,

wherein the reference data is previously written data exhibiting characteristics of the reflected light according to the drying rate of the electrode substrate.

5. The method of claim 1 , further comprising drying the electrode substrate in a drying device by passing the electrode substrate through a drying chamber of the drying device to which heat is applied, and

controlling a temperature of the drying chamber based on data of the estimated drying rate of the electrode substrate.