Positive active material for non-aqueous electrolyte secondary battery and non-aqueous electrolyte secondary battery comprising same
View Patent ↗A positive active material for non-aqueous electrolyte secondary battery is provided comprising lithium manganese oxide having such a spinel structure that the half-width (2θ) of the reflection peak corresponding to 440 plane as determined by X-ray diffractometry using CuKα ray is not greater than 0.145°. The use of this positive active material makes it possible to obtain a secondary battery which exhibits a good cycle life performance at room temperature and high temperatures and a reduced capacity drop when stored at high temperatures.
1. A positive active material for non-aqueous electrolyte secondary battery, comprising lithium manganese oxide having a spinel structure and being represented by the following general formula:
Li 1+x M y Mn 2−x−y O 4
wherein x represents a number of from not smaller than 0 to not greater than 0.2; y represents a number of from greater than 0 to not greater than 0.15; and M represents a metal element other than Mn, and
the half-width (2θ) of the reflection peak corresponding to 440 plane as determined by X-ray diffractometry using CuKα ray is not greater than 0.145°.
2. The positive active material for non-aqueous electrolyte secondary battery according to claim 1 , wherein the intensities of reflection peaks corresponding to 311, 400 and 111 planes of said lithium manganese oxide as determined by the X-ray diffractometry using the CuKα ray, I (311) , I (400) and I (111) , satisfy I (311) /I (111) ≧0.45, I (400) /I (111) ≧0.55, and I (400) /I (311) ≧1.10.
3. The positive active material for non-aqueous electrolyte secondary battery according to claim 2 , wherein the average particle diameter of said positive active material in powder form is from 5 μm to 30 μm.
4. The positive active material for non-aqueous electrolyte secondary battery according to claim 1 , wherein the average particle diameter of said positive active material in powder form is from 5 μm to 30 μm.
5. A positive active material for non-aqueous electrolyte secondary battery, comprising lithium manganese oxide having a spinel structure and being represented by the following general formula:
Li 1+x M y Mn 2−x−y O 4
wherein x represents a number of from not smaller than 0 to not greater than 0.2; y represents a number satisfying that the amount of M is from 1 to 10% based on manganese ion; and M represents a metal element other than Mn, and
the half-width (2θ) of the reflection peak corresponding to 440 plane as determined by X-ray diffractometry using CuKα ray is not greater than 0.145°.
6. The positive active material for non-aqueous electrolyte secondary battery according to claim 5 , wherein the intensities of reflection peaks corresponding to 311,400 and 111 planes of said lithium manganese oxide as determined by the X-ray diffractometry using the CuKα ray, I (311) , I (400) and I (111) , satisfy I (311) /I (111) ≧0.45, I (400) /I (111) ≧0.55, and I (400) /I (311) ≧1.10.
7. The positive active material for non-aqueous electrolyte secondary battery according to claim 6 , wherein the average particle diameter of said positive active material in powder form is from 5 μm to 30 μm.
8. The positive active material for non-aqueous electrolyte secondary battery according to claim 5 , wherein the average particle diameter of said positive active material in powder form is from 5 μm to 30 μm.
9. A non-aqueous electrolyte secondary battery comprising a positive electrode containing said positive active material as defined in any one of claims 1 , 2 , 4 , 3 , 5 , 6 , 8 , and 7 , a negative electrode containing a carbon-based material, and a non-aqueous electrolyte.