Positive electrode active substance for lithium ion batteries, positive electrode for lithium ion batteries, and lithium ion battery
View Patent ↗The present invention provides a positive electrode active material for a lithium ion battery which has high capacity and good rate characteristics. The positive electrode active material has a layer structure represented by the compositional formula: Li α (Ni β Me 1-β )O γ , wherein Me represents at least one type selected from the group consisting of Mn, Co, Al, Mg, Cr, Ti, Fe, Nb, Cu and Zr, x denotes a number from 0.9 to 1.2, y denotes a number from 0.5 to 0.65, and z denotes a number of 1.9 or more. The positive electrode active material is selected by measuring the coordinates of the lattice constant a and compositional ratio (Li/M) and selecting materials within the region enclosed by three lines given by the equations: y=−20.186x+59.079, y=35x−99.393, and y=−32.946x+95.78, wherein the x-axis represents a lattice constant a and the y-axis represents a compositional ratio (Li/M) of Li to M.
1. A positive electrode active material for a lithium ion battery which has a layer structure represented by the compositional formula:
Li α (Ni β Me 1-β )O γ ,
wherein Me represents at least one type selected from the group consisting of Mn, Co, Al, Mg, Cr, Ti, Fe, Nb, Cu and Zr,
α denotes a number from 0.9 to 1.2,
β denotes a number from 0.5 to 0.65, and
γ denotes a number of 1.9 or more,
wherein the measured coordinates of the lattice constant a and compositional ratio (Li/M), wherein M is the sum of all metals excluding Li in the above compositional formula, are within the region enclosed by three lines given by the equations: y=−20.186x +59.079, y=35x −99.393, and y=−32.946x +95.78 on a graph in which the x-axis represents a lattice constant a and the y-axis represents a compositional ratio (Li/M) of Li to M, and the lattice constant c is 14.2 to 14.25.
2. The positive electrode active material for a lithium ion battery according to claim 1 , wherein the coordinates of the lattice constant a and compositional ratio (Li/M) are within the region enclosed by three lines given by the equations: y=−15x+44.18, y=33.33x−94.665, and y=−200x+575.92.
3. The positive electrode active material for a lithium ion battery according to claim 1 , wherein Me represents one metal selected from the group consisting of Mn and Co.
4. A positive electrode for lithium ion battery comprising the positive electrode active material of claim 1 .
5. A lithium ion battery comprising the positive electrode for lithium ion battery of claim 4 .
6. A positive electrode for lithium ion battery comprising the positive electrode active material of claim 2 .
7. A positive electrode for lithium ion battery comprising the positive electrode active material of claim 3 .
8. A lithium ion battery comprising the positive electrode for lithium ion battery of claim 6 .
9. A lithium ion battery comprising the positive electrode for lithium ion battery of claim 7 .