Positive electrode material, its manufacturing method and lithium secondary battery
View Patent ↗The object of the invention is to provide positive electrode material in which a discharge rate characteristic and battery capacity are hardly deteriorated in the environment of low temperature of −30° C., its manufacturing method and a lithium secondary battery using the positive electrode material. The invention is characterized by the positive electrode material in which plural primary particles are flocculated and a secondary particle is formed, and the touch length of the primary particles is equivalent to 10 to 70% of the length of the whole periphery on the section of the touched primary particles.
1. A method of manufacturing positive electrode material, wherein:
material powder including Li, Ni, Mn and Co is ground after it is burned at 950 to 1100° C.;
plural primary particles are flocculated and a secondary particle is formed;
length in which the primary particles are linked on a section of the secondary particle is equivalent to 50 to 70% of the length of the whole periphery on a section of the primary particles;
the secondary particle is represented as Li a Mn x Ni y Co z O 2 ; and
the secondary particle is composed of crystals having layer structure of composite oxide meeting 1≦a≦1.2, 0≦x≦0.65, 0.33≦y<0.5, 0≦z≦0.65 and x+y+z=1.
2. A method of manufacturing positive electrode material according to claim 1 , wherein:
the material powder includes lithium carbonate, nickel oxide, manganese dioxide and cobalt oxide.
3. A method of manufacturing positive electrode material according to claim 2 , wherein:
the material powder is burned after it is granulated and dried by a spray dryer.
4. A method of manufacturing positive electrode material according to claim 1 , wherein:
the mean diameter of the primary particle is 0.2 to 10 μm.
5. A method of manufacturing positive electrode material according to claim 4 , wherein:
the mean diameter of the secondary particle is 5 to 30 μm.
6. A method of manufacturing positive electrode material, wherein
plural primary particles flocculated and a secondary particle is formed; and
length in which the primary particles are linked on a section of the secondary particle is equivalent to 50 to 70% of the length of the whole periphery on a section of the primary particles;
the secondary particle is represented as Li a Mn x Ni y Co z O 2 ; and
the secondary particle is composed of crystals having layer structure of composite oxide meeting 1≦a≦1.2, 0≦x≦0.65, 0.33≦y<0.5, 0≦z≦0.65 and x+y+z=1, wherein:
the material powder including lithium carbonate, nickel oxide, manganese dioxide and cobalt oxide is granulated and dried by a spray dryer, and is burned at 950 to 1100° C., and then is ground so that the mean diameter of the primary particle is 0.2 to 10 μm.