CATHODE ACTIVE MATERIAL, ITS MANUFACTURING METHOD, AND NON-AQUEOUS ELECTROLYTE SECONDARY BATTERY
A cathode active material is provided. The cathode active material includes: a composite oxide particle including at least lithium and cobalt; a coating layer which is provided in at least a part of the composite oxide particle and includes an oxide including lithium and a coating element of at least one of nickel and manganese; and a surface layer which is provided in at least a part of the coating layer and includes at least one element selected from the group consisting of silicon, tin, phosphorus, magnesium, boron, zinc, tungsten, aluminum, titanium, and zirconium.
1 . A cathode active material comprising:
a composite oxide particle comprising at least lithium and cobalt;
a coating layer which is provided in at least a part of said composite oxide particle and includes an oxide including lithium and a coating element of at least one of nickel and manganese; and
a surface layer which is provided in at least a part of the coating layer and includes phosphorus.
2 . The cathode active material according to claim 1 , wherein mean compositions of the composite oxide particle are expressed by Formula 1,
Li (1+x) Co (1−y) M y O (2−z) (Formula 1)
in Formula 1, M denotes an element of at least one kind selected from the group consisting of magnesium, aluminum, boron, titanium, vanadium, chromium, manganese, iron, nickel, copper, zinc, molybdenum, tin, and tungsten; x indicates a value within a range of −0.10≦x≦0.10; y indicates a value within a range of 0≦y<0.50; and z indicates a value within a range of −0.10≦z≦0.20.
3 . The cathode active material according to claim 1 , wherein a construction ratio of said nickel and said manganese in said coating layer ranges from 100:0 to 30:70 as a mole ratio.
4 . The cathode active material according to claim 1 , wherein the oxide in said coating layer is an oxide obtained by replacing 40 mol % or less of a total amount of said nickel and said manganese with a metal element of at least one kind selected from the group consisting of magnesium, aluminum, boron, titanium, vanadium, chromium, iron, cobalt, copper, zinc, molybdenum, tin, and tungsten.
5 . The cathode active material according to claim 1 , wherein an amount of said coating ranges from 0.5 weight % to 50 weight % of said composite oxide particle.
6 . The cathode active material according to claim 1 , wherein a mean diameter ranges from 2.0 μm to 50 μm.
7 . A method of manufacturing a cathode active material, comprising:
forming a layer made of a hydroxide containing nickel and/or manganese into at least a part of a composite oxide particle including at least lithium and cobalt and, thereafter, coating at least a part of said composite oxide particle with a phosphoric acid; and
executing a heating process after coating with the phosphoric acid, thereby forming a coating layer made of an oxide containing lithium and a coating element of at least one of nickel and manganese and a surface layer containing phosphorus into at least a part of said composite oxide particle.
8 . The method of manufacturing the cathode active material according to claim 7 , wherein mean compositions of said composite oxide particle are expressed by Formula 1,
Li (1+x) Co (1−y) M y O (2−z) (Formula 1)
in Formula 1, M denotes an element of at least one kind selected from a group containing magnesium, aluminum, boron, titanium, vanadium, chromium, manganese, iron, nickel, copper, zinc, molybdenum, tin, and tungsten; x indicates a value within a range of −0.10≦x≦0.10; y indicates a value within a range of 0≦y<0.50; and z indicates a value within a range of −0.10≦z≦0.20.
9 . The method of manufacturing the cathode active material according to claim 7 , wherein said hydroxide including nickel and/or manganese is formed by
dispersing said composite oxide particle into a solvent constructed mainly by water whose pH is equal to 12 or more and, thereafter, adding a compound of nickel and/or a compound of manganese.
10 . The method of manufacturing the cathode active material according to claim 9 , wherein said solvent constructed mainly by the water contains lithium hydroxide.
11 . The method of manufacturing the cathode active material according to claim 7 , wherein a construction ratio of the nickel and the manganese in the coating layer ranges from 100:0 to 30:70 as a mole ratio.
12 . The method of manufacturing the cathode active material according to claim 7 , wherein the oxide in said coating layer is an oxide obtained by replacing 40 mol % or less of a total amount of said nickel and said manganese with a metal element of at least one kind selected from the group consisting of magnesium, aluminum, boron, titanium, vanadium, chromium, iron, cobalt, copper, zinc, molybdenum, tin, and tungsten.
13 . The method of manufacturing the cathode active material according to claim 7 , wherein an amount of the coating layer ranges from 0.5 weight % to 50 weight % of the composite oxide particle.
14 . The method of manufacturing the cathode active material according to claim 7 , wherein a mean diameter of the particle in said cathode active material ranges from 2.0 μm to 50 μm.
15 . A non-aqueous electrolyte secondary battery comprising:
a cathode having a cathode active material;
an anode; and
an electrolyte, wherein
the cathode active material includes:
a composite oxide particle including at least lithium and cobalt;
a coating layer which is provided in at least a part of the composite oxide particle and includes an oxide containing lithium and a coating element of at least one of nickel and manganese; and
a surface layer which is provided in at least a part of the coating layer and includes phosphorus.