Negative electrode for secondary battery and secondary battery including the same

1. A negative electrode for a secondary battery comprising:

a current collector; and

a negative electrode active material layer comprising a negative electrode active material, formed on the current collector,

wherein the negative electrode satisfies the following Relation 1:

3.0 <τ*D P <7.2   [Relation 1]

wherein τ is a tortuosity of the negative electrode,

τ=( R ion ×A ×κ×ε)/ d

wherein R ion is an ionic diffusion resistance (Ohm) by impedance analysis, A is an area of a negative electrode (cm 2 ), κ is an ion conductivity (mS/cm) of an electrolyte solution, ε is a porosity of a negative electrode, and d is a thickness (μm) of a negative electrode, and

D P is a pellet density (g/cm 3 ) of the negative electrode active material, measured by pressing the negative electrode active material at 8 kN/cm 2 .

2. The negative electrode for a secondary battery of claim 1 , wherein the negative electrode has a tortuosity (τ) of 1 to 4.

3. The negative electrode for a secondary battery of claim 1 , wherein the negative electrode active material has a pellet density (D P ) of 1.0 to 2.0 g/cm 3 .

4. The negative electrode for a secondary battery of claim 3 ,

wherein the negative electrode active material has a pellet resistance (R P ) of 0.005 to 0.01 Ohm, and

the pellet resistance is a resistance value measured by pressing the negative electrode active material at 8 kN/cm 2 .

5. The negative electrode for a secondary battery of claim 1 , wherein the negative electrode further satisfies the following Relation 2:

4.3< τ*D P <6.4   [Relation 2]

wherein τ is a tortuosity of the negative electrode, and D P is a pellet density of the negative electrode active material, measured by pressing the negative electrode active material at 8 kN/cm 2 .

6. The negative electrode for a secondary battery of claim 1 , wherein the negative electrode active material is a carbonaceous active material.

7. The negative electrode for a secondary battery of claim 1 , wherein the negative electrode satisfies at least two of the following Relations 3 to 5:

0.2< V P <0.5   [Relation 3]

wherein V P is a pore volume (cc/g) of the negative electrode,

0.8 <D <20   [Relation 4]

wherein D is D50 (μm) of the negative electrode active material,

0.8 <D T <1.5   [Relation 5]

wherein D T is a tap density (g/cc) of the negative electrode active material.

8. The negative electrode for a secondary battery of claim 1 , wherein a pore size in the negative electrode active material layer is 500 to 800 nm.

9. The negative electrode for a secondary battery of claim 1 , wherein the negative electrode has a mix density of 1.65 g/cc to 1.85 g/cc.

10. A secondary battery comprising: the negative electrode of claim 1 ; a positive electrode; a separator; and an electrolyte solution.