Polycrystalline cobalt-nickel-manganese ternary positive material, preparation method thereof and lithium ion secondary battery

摘要

A polycrystalline cobalt-nickel-manganese ternary positive material is provided. The polycrystalline cobalt-nickel-manganese ternary positive material comprises more than two basic crystalline structures of Li_z—CoO₂, Li_zNiO₂, Li_zMnO₂, Li_zCo_1-(x+y)Ni_xMn_yO₂, Li_zNi_xMn_1-xO₂, Li_zCo_xNi_1-xO₂ and Li₂MnO₃. Further, a method for preparing the positive material by high-temperature fusion is provided. The positive material has the compacted density of 3.9-4.3 g/cm³, the capacity of 145 mAh/g or more when the discharging rate is 0.5-1C and the capacity retention rate of more than 90% after 300 cycles. The positive material prepared by high-temperature fusion has high volume energy density, excellent electrochemical performance, and improved safety and is manufactured economically. Further, a lithium ion secondary battery comprising the positive material is provided.