Method of manufacturing lithium nickel complex oxide, lithium nickel complex oxide manufactured thereby, and cathode active material including the same
View Patent ↗Provided are a method of manufacturing a lithium nickel complex oxide including mixing a nickel-containing mixed transition metal precursor, a lithium compound, and a polyvinylidene fluoride-hexafluoropropylene (PVdF-HFP) copolymer, and heat treating the mixture, a lithium nickel complex oxide manufactured thereby, and a cathode active material including the lithium nickel complex oxide. The method of manufacturing a lithium nickel complex oxide according to an embodiment of the present invention may adjust a ratio of divalent nickel (Ni II ) to trivalent nickel (Ni III ) by using a polyvinylidene fluoride-hexafluoropropylene (PVdF-HFP) copolymer, and thus, the method may improve capacity of a secondary battery.
1. A method of manufacturing a lithium nickel complex oxide comprising:
preparing a mixture of a lithium nickel oxide and a polyvinylidene fluoride-hexafluoropropylene (PVdF-HFP) copolymer; and
heat treating the mixture in a temperature range of 250° C. to 500° C.,
wherein a melt flow index of the polyvinylidene fluoride-hexafluoropropylene copolymer is in a range of 3 g/10 min to 20 g/10 min when measured under a load of 2.16 kg in accordance with the ISO 1133 standard.
2. The method of claim 1 , wherein an amount of hexafluoropropylene (HFP) in the polyvinylidene fluoride-hexafluoropropylene copolymer is in a range of 1 wt % to 30 wt %.
3. The method of claim 2 , wherein the amount of HFP in the polyvinylidene fluoride-hexafluoropropylene copolymer is in a range of 5 wt % to 20 wt %.
4. The method of claim 1 , wherein the polyvinylidene fluoride-hexafluoropropylene copolymer is used in an amount of 0.2 wt % to 0.5 wt % based on 100 wt % of the lithium nickel oxide.
5. The method of claim 1 , wherein the lithium nickel oxide is doped with some fluorine (F) atoms of the polyvinylidene fluoride-hexafluoropropylene copolymer by the heat treatment.
6. The method of claim 5 , wherein a doping amount of the F atoms is in a range of 1,000 ppm to 5,000 ppm.
7. The method of claim 1 , wherein the lithium nickel oxide is Li w Ni x Mn y Co z O 2 (where x+y+z=1, 0.4≤x≤0.9, 0≤y≤0.6, 0≤z≤0.6, and 0.9≤w≤1.3).