Lithium secondary battery
A lithium secondary battery including: a positive electrode, a negative electrode, and a sulfide solid electrolyte disposed between the positive electrode and the negative electrode, wherein the positive electrode includes a positive active material particle and a coating film including an oxide including lithium (Li) and zirconium (Zr) on a surface of the positive active material particle.
1. A lithium secondary battery comprising:
a positive electrode;
a negative electrode; and
a sulfide solid electrolyte disposed between the positive electrode and the negative electrode,
wherein the sulfide solid electrolyte comprises lithium sulfide and phosphorus pentasulfide,
wherein the positive electrode comprises a positive active material particle and a coating film on a surface of the positive active material particle,
wherein the coating film comprises a composite having a structure represented by Formula 1,
a Li 2 O—ZrO 2
wherein 0.1≤a≤2.0,
wherein an amount of the composite is in a range of 0.1 to 2.0 mole percent, based on a total amount of the positive active material particle and the composite,
wherein the positive active material particle has a layered rock salt structure, and
wherein the positive active material particle has
a D10 particle diameter of about 2 micrometers to about 3.5 micrometers,
a D50 particle diameter of about 3 micrometers to about 5 micrometers, and
a D90 particle diameter of about 3.5 micrometers to about 5 micrometers, and
wherein the positive active material particle is
LiNi x Co y Al z O 2 , wherein 0<x<1, 0<y<1, 0<z<1, and x+y+z=1,
LiNi x Co y Mn z O 2 wherein 0<x<1, 0<y<1, 0<z<1, and x+y+z=1, or
a combination thereof.
2. The lithium secondary battery of claim 1 , wherein the amount of the composite is in a range of 0.1 to 0.95 mole percent, based on th e total amount of the positive active material particle and the coating film.
3. The lithium secondary battery of claim 1 , wherein a ratio of the lithium sulfide to the phosphorus pentasulfide is in a range of about 50:50 to about 80:20.
4. The lithium secondary battery of claim 1 , wherein
a D10 particle diameter of the positive active material particle is about 2.5 micrometers,
a D50 particle diameter of the positive active material particle is about 3.3 micrometers, and
a D90 particle diameter of the positive active material particle is about 4.5 micrometers.
5. The lithium secondary battery of claim 1 , wherein the sulfide solid electrolyte comprises lithium sulfide and phosphorus pentasulfide, and an amount of the composite is in a range of 0.1 to 2.0 mole percent, based on the total amount of the positive active material particle and the coating film.
6. The lithium secondary battery of claim 1 , wherein an initial discharge capacity of the battery is increased as compared to a same battery comprising a positive electrode comprising the positive active material particle without the coating film by 4.55% to 18.18%.