Positive electrode and secondary battery including the same
The present invention relates to a positive electrode and a secondary battery including the same, and particularly, to a positive electrode which includes a current collector; a first active material layer including first active material particles and disposed on the current collector; and a first pattern and a second pattern alternately disposed separately from each other on the first active material layer, wherein the first pattern includes first pattern active material particles, the second pattern includes second pattern active material particles, the first pattern has a thickness greater than that of the second pattern, and the second pattern has a volume expansion rate greater than that of the first pattern, and a secondary battery including the same.
1. A positive electrode comprising:
a current collector;
a first active material layer including first active material particles and disposed on the current collector; and
a first pattern and a second pattern alternately disposed separately from each other on the first active material layer, wherein:
the first pattern includes first pattern active material particles;
the second pattern includes second pattern active material particles;
the first pattern has a thickness greater than that of the second pattern; and
the second pattern has a volume expansion rate greater than that of the first pattern.
2. The positive electrode of claim 1 , wherein:
the first active material particle and the first pattern active material particle are LiCoO 2 ; and
the second pattern active material particle is any one of LiNi 1-x1-y1 Co x1 Mn y1 O 2 (0<x1<1 and 0<y1<1) and LiNi 1-x2-y2 Co x2 Al y2 O 2 (0<x2<1 and 0<y2<1).
3. The positive electrode of claim 1 , wherein:
the first active material particle is any one of LiNi 1-x1-y1 Co x1 Mn y1 O 2 (0<x1<1 and 0<y1<1) and LiNi 1-x2-y2 Co x2 Al y2 O 2 (0<x2<1 and 0<y2<1);
the first pattern active material particle and the second pattern active material particle are LiCoO 2 ; and
the second pattern has a porosity lower than that of the first pattern.
4. The positive electrode of claim 3 , wherein a difference between the porosity of the first pattern and the porosity of the second pattern is 5 percentage points or more.
5. The positive electrode of claim 1 , wherein:
the first active material particle is LiCoO 2 ;
the first pattern active material particle is at least one of LiNi 1-x1-y1 Co x1 Mn y1 O 2 (0<x1<1 and 0<y1<1) and LiNi 1-x2-y2 Co x2 Al y2 O 2 (0<x2<1 and 0<y2<l);
the second pattern active material particle is at least one of LiFePO 4 and LiMn 2 O 4 ; and
the second pattern has a porosity lower than that of the first pattern.
6. The positive electrode of claim 5 , wherein a difference between the porosity of the first pattern and the porosity of the second pattern is 5 percentage points or more.
7. The positive electrode of claim 1 , wherein the first pattern has a thickness 1.1 to 2 times greater than that of the second pattern.
8. A secondary battery comprising:
the positive electrode according to claim 1 ;
a negative electrode;
a separator interposed between the positive electrode and the negative electrode; and
an electrolyte.