Negative electrode, secondary battery including the same, and method of preparing the negative electrode
TA negative electrode, a secondary battery including the same, and a method of preparing the negative electrode are provided. The negative electrode, which includes a current collector; a negative electrode active material layer disposed on the current collector; a first layer disposed on the negative electrode active material layer and including Li; and a second layer disposed on the first layer and including an inorganic material is provided. A loading amount of the first layer may satisfy Equation 1: 0.65×( x 1 −y 1 )<loading amount of the first layer<0.95×( x 1 −y 1 ). [Equation 1]
1. A negative electrode, comprising:
a current collector;
a negative electrode active material layer disposed on the current collector;
a first layer disposed on the negative electrode active material layer and containing Li; and
a second layer disposed on the first layer and containing an inorganic material, wherein the inorganic material is Al 2 O 3 ,
wherein the negative electrode active material layer contains a negative electrode active material, and the negative electrode active material consists of graphite and SiO x (0<x<2),
wherein a loading amount of the first layer satisfies Equation 1 below:
0.65×( x 1 −y 1 )<loading amount of the first layer<0.95×( x 1 −y 1 ), [Equation 1]
in Equation 1, x 1 is a charge loading amount of the negative electrode active material layer, y 1 is a discharge loading amount of the negative electrode active material layer,
units of the loading amount of the first layer, the charge loading amount and the discharge loading amount are mAh/cm 2 , and
the charge loading amount and the discharge loading amount are capacities per unit area measured in a half-cell which includes a lithium metal electrode and an electrode including the negative electrode active material layer,
wherein the charge loading amount is a capacity per unit area of the half-cell when a charging current decreases to 0.005C after the half-cell is charged at a constant current (CC) until a potential difference of the electrode including the negative electrode active material layer with respect to the lithium metal electrode becomes 0.005V, and then charged at a constant voltage (CV), and
the discharge loading amount is a difference between the capacity per unit area of the half-cell and the charge loading amount when a potential difference of the electrode including the negative electrode active material with respect to the lithium metal electrode while the half-cell is discharged at a constant current becomes 1.5V.
2. The negative electrode according to claim 1 , wherein the first layer consists of Li.
3. The negative electrode according to claim 1 , wherein the second layer has a thickness of 50 nm to 500 nm.
4. A secondary battery, comprising:
the negative electrode of claim 1 ;
a positive electrode;
a separator interposed between the positive electrode and the negative electrode; and
an electrolyte.
5. The secondary battery according to claim 4 , wherein the first layer consists of Li.
6. The secondary battery according to claim 4 , wherein the second layer has a thickness of 50 nm to 500 nm.
7. The negative electrode according to claim 1 , wherein the second layer consists of the inorganic material.