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 lithium secondary battery for an automobile, comprising a positive electrode comprising a plurality of the secondary particles, a negative electrode and a non-aqueous electrolyte, each of said secondary particles comprising:
a plurality of primary particles composed of planar crystals having a structure of a composite oxide represented by Li a Mn x Ni y Co z O 2 where 1≦a≦1.2, 0≦x≦0.65, 0.33≦y<0.5, 0≦z≦0.65 and x+y+z=1, the primary particles being flocculated and linked to form the secondary particle,
wherein a length in which the plurality of primary particles are linked on a section of the secondary particle through a substantial center of the secondary particle is equivalent to 50 to 70% of the length of the whole periphery of plurality of primary particles on the section of the secondary particle; and
wherein a voidage of the secondary particle is 2.5 to 35%.
2. The lithium secondary battery for automobile according to claim 1 , wherein the mean diameter of the primary particle is 0.2 to 10 μm.
3. The lithium secondary battery for automobile according to claim 1 , wherein a voidage of the secondary particle is 2.5 to 10%.