Positive electrode active material for non-aqueous electrolyte secondary batteries and non-aqueous electrolyte secondary battery
An exemplary embodiment of the present disclosure resides in a positive electrode active material for non-aqueous electrolyte secondary batteries including a Li 2 MnO 3 —LiMO 2 solid solution {M is at least one metal element} which shows two peaks in an X-ray diffraction pattern each having a peak top at a diffraction angle of 18° to 19° and satisfying 0.001<R (B/A) <0.03, the R (B/A) is the ratio of the intensity B of one of the peaks on the higher angle side to the intensity A of the other peak on the lower angle side.
1. A positive electrode active material for non-aqueous electrolyte secondary batteries, comprising a Li 2 MnO 3 —LiMO 2 solid solution, wherein the Li 2 MnO 3 —LiMO 2 solid solution is represented by the general formula: Li x Na y [Li z1 Mn z2 M* (1-z1-z2) ]O (2±γ) {0.67<x<1.1, 0<y<0.1, 0<z1<0.33, 0.5<z2<0.95, 0≤γ<0.1, and M* indicates two or more transition metal elements including at least nickel and cobalt}, the solid solution showing two peaks in an X-ray diffraction pattern each having a peak top at a diffraction angle of 18° to 19° and satisfying 0.007<R (B/A) <0.0231, the R (B/A) is the ratio of the intensity B of one of the peaks on the higher angle side to the intensity A of the other peak on the lower angle side.
2. The positive electrode active material for non-aqueous electrolyte secondary batteries according to claim 1 , wherein the positive electrode active material is in a volume ratio of 50 vol % or more relative to the total volume of the positive electrode active material.
3. A non-aqueous electrolyte secondary battery comprising:
a positive electrode including the positive electrode active material;
a negative electrode; and
an electrolyte,
wherein the positive electrode active material comprises a Li 2 MnO 3 —LiMO 2 solid solution, wherein the Li 2 MnO 3 —LiMO 2 solid solution is represented by the general formula: Li x Na y [Li z1 Mn z2 M* (1-z1-z2) ]O (2±γ) {0.67<x<1.1, 0<y<0.1, 0<z1<0.33, 0.5<z2<0.95, 0≤γ<0.1, and M* indicates two or more transition metal elements including at least nickel and cobalt}, the solid solution showing two peaks in an X-ray diffraction pattern each having a peak top at a diffraction angle of 18° to 19° and satisfying 0.007<R (B/A) <0.0231, the R (B/A) is the ratio of the intensity B of one of the peaks on the higher angle side to the intensity A of the other peak on the lower angle side.
4. A method for manufacturing the positive electrode active material of claim 1 , comprising:
reacting sodium composite oxide represented by the general formula: Na α [Li β1 Mn β2 M (1-β1-β2) ]O (2±γ) {0.67<α<1.1, 0<β1<0.33, 0.5<β2<0.95, 0≤γ<0.1, and M is at least one transition metal element including at least nickel and cobalt} with a lithium compound to exchange sodium ions in the sodium composite oxide with lithium ions.
5. The positive electrode active material for non-aqueous electrolyte secondary batteries according to claim 1 , wherein the solid solution shows a peak in an X-ray diffraction pattern having a peak top at a diffraction angle of 20° to 25° assigned to a superlattice structure.
6. The non-aqueous electrolyte secondary battery according to claim 3 , wherein the solid solution shows a peak in an X-ray diffraction pattern having a peak top at a diffraction angle of 20° to 25° assigned to a superlattice structure.
7. The positive electrode active material for non-aqueous electrolyte secondary batteries according to claim 1 , wherein M* indicates nickel and cobalt.
8. The non-aqueous electrolyte secondary battery according to claim 3 , wherein M* indicates nickel and cobalt.