Lithium metal composite oxide and preparation method thereof, positive electrode, lithium secondary battery and composite material

The invention relates to a lithium metal composite oxide and a preparation method thereof, a positive electrode, a lithium secondary battery and a composite material. A nickel-based lithium metal composite oxide includes: secondary particles including aggregates of primary particles, where the secondary particles include i) large secondary particles having a particle size of at least about 14 [mu] m and including aluminum, and ii) small secondary particles having a particle size of not greater than about 5 [mu] m and including manganese, and the manganese content in molar percentage of each large secondary particle is less than the manganese content in molar percentage of each small secondary particle, and manganese is included on a surface of each large secondary particle, and aluminum is included on a surface of each small secondary particle. 本发明涉及锂金属复合氧化物及制法、正极、锂二次电池和复合材料。镍类锂金属复合氧化物，包括：包括初级颗粒的聚集体的次级颗粒，其中次级颗粒包括i)颗粒尺寸为至少约14μm并且包括铝的大的次级颗粒，和ii)颗粒尺寸不大于约5μm并且包括锰的小的次级颗粒，并且每个大的次级颗粒的按摩尔百分数计的锰含量小于每个小的次级颗粒的按摩尔百分数计的锰含