Lithium secondary battery
Provided is a lithium secondary battery containing a cathode active material capable of preventing decreases in power and cycle life occurring at the time of adding a sulfur based additive used in order to improve high-temperature storage characteristics to an electrolyte.
1. A lithium secondary battery comprising a cathode, an anode, and a non-aqueous electrolyte,
wherein the non-aqueous electrolyte contains a sulfur based additive, and
the cathode contains a cathode active material containing a lithium-metal oxide particle,
the lithium-metal oxide particle including a core part represented by Chemical Formula 5 and a surface part represented by Chemical Formula 6, having a concentration gradient layer of Ni in which a concentration of Ni is decreased in a surface direction between the surface part and the core part, containing a constant concentration of Co between the surface part and the core part, and having a concentration gradient layer of Mn in which a concentration of Mn is increased in the surface direction between the surface part and the core part:
Li x4 Ni a4 Co b4 Mn c4 O y4 [Chemical Formula 5]
Li x5 Ni a5 Co b5 Mn c5 O y5 [Chemical Formula 6]
(in Chemical Formulas 5 and 6, x4, x5, y4, y5, a4, a5, b4, b5, c4, and c5 satisfy 0<x4≤1.1, 0<x5≤1.1, 2≤y4≤2.02, 2≤y5≤2.02, 0.800≤a4≤1.000, 0≤a5≤0.770, 0<b4≤0.11, 0<b5≤0.11, 0≤c4≤0.090, 0.120≤c5≤1.000, 0<a4+b4+c4≤1, and 0<a5+b5+c5≤1),
wherein the core part has a radius of equal to or greater than 0.6 μm from the center of the lithium-metal oxide particle, and the concentration gradient layer has a width of equal to or greater than 0.2 μm,
and wherein the lithium-metal oxide particle is doped with at least one metal ingredient selected from the group consisting of Al, Ti, Ba, Zr, Si, B, Mg, P, V, and a combination thereof.
2. A lithium secondary battery comprising a cathode, an anode, and a non-aqueous electrolyte,
wherein the non-aqueous electrolyte contains a sulfur based additive,
and the cathode contains a cathode active material containing a lithium-metal oxide particle,
the lithium-metal oxide particle including a core part represented by Chemical Formula 5 and a surface part represented by Chemical Formula 6, having a concentration gradient layer of Ni in which a concentration of Ni is decreased in a surface direction between the surface part and the core part, containing a constant concentration of Co between the surface part and the core part, and having a concentration gradient layer of Mn in which a concentration of Mn is increased in the surface direction between the surface part and the core part:
Li x4 Ni a4 Co b4 Mn c4 O y4 [Chemical Formula 5]
Li x5 Ni a5 Co b5 Mn c5 O y5 [Chemical Formula 6]
(in Chemical Formulas 5 and 6, x4, x5, y4, y5, a4, a5, b4, b5, c4, and c5 satisfy 0<x4≤1.1, 0<x5≤1.1, 2≤y4≤2.02, 2≤y5≤2.02, 0.800≤a4≤1.000, 0≤a5≤0.770, 0<b4≤0.11, 0<b5≤0.11, 0≤c4≤0.090, 0.120≤c5≤1.000, 0<a4+b4+c4≤1, and 0<a5+b5+c5≤1),
wherein the core part has a radius of equal to or greater than 0.6 μm from the center of the lithium-metal oxide particle, and the concentration gradient layer has a width of equal to or greater than 0.2 μm,
and wherein the lithium-metal oxide particle further includes a coating layer formed of Al, Ti, Ba, Zr, Si, B, Mg, P, an alloy thereof, or an oxide thereof.
3. A lithium secondary battery comprising a cathode, an anode, and a non-aqueous electrolyte,
wherein the non-aqueous electrolyte contains a sulfur based additive,
wherein the sulfur based additive is a sultone based additive,
and the cathode contains a cathode active material containing a lithium-metal oxide particle,
the lithium-metal oxide particle including a core part represented by Chemical Formula 5 and a surface part represented by Chemical Formula 6, having a concentration gradient layer of Ni in which a concentration of Ni is decreased in a surface direction between the surface part and the core part, containing a constant concentration of Co between the surface part and the core part, and having a concentration gradient layer of Mn in which a concentration of Mn is increased in the surface direction between the surface part and the core part:
Li x4 Ni a4 Co b4 Mn c4 O y4 [Chemical Formula 5]
Li x5 Ni a5 Co b5 Mn c5 O y5 [Chemical Formula 6]
(in Chemical Formulas 5 and 6, x4, x5, y4, y5, a4, a5, b4, b5, c4, and c5 satisfy 0<x4≤1.1, 0<x5≤1.1, 2≤y4≤2.02, 2≤y5≤2.02, 0.800≤a4≤1.000, 0≤a5≤0.770, 0<b4≤0.11, 0<b5≤0.11, 0≤c4≤0.090, 0.120≤c5≤1.000, 0<a4+b4+c4≤1, and 0<a5+b5+c5≤1),
wherein the core part has a radius of equal to or greater than 0.6 μm from the center of the lithium-metal oxide particle, and the concentration gradient layer has a width of equal to or greater than 0.2 μm.
4. The lithium secondary battery of claim 3 , wherein the lithium-metal oxide particle is doped with at least one metal ingredient selected from the group consisting of Al, Ti, Ba, Zr, Si, B, Mg, P, V, and a combination thereof.
5. The lithium secondary battery of claim 3 , wherein the lithium-metal oxide particle further includes a coating layer formed of Al, Ti, Ba, Zr, Si, B, Mg, P, an alloy thereof, or an oxide thereof.