Lithium manganate particles for non-aqueous electrolyte secondary battery, process for producing the same, and non-aqueous electrolyte secondary battery
The present invention relates to lithium manganate particles having a primary particle diameter of not less than 1 μm and an average particle diameter (D 50 ) of not less than 2 μm and not more than 10 μm as measured by a particle size distribution meter, and forming particles having substantially a single phase, which have a composition represented by the following chemical formula: Li 1+x Mn 2−x−y Y1 y O 4 +Y2 where Y1 is at least one element selected from the group consisting of Ni, Co, Mg, Fe, Al, Cr and Ti; Y2 is at least one element constituting a sintering aid having a melting point of not higher than 800° C., x and y satisfy 0.03≦x≦0.15 and 0.05≦y≦0.20, respectively, and Y2 is present in an amount of 0.1 to 2.5 mol % based on Mn; the Y1 element being dispersed within the respective particles, and an X-ray diffraction intensity ratio of I(400)/I(111) of the particles being not less than 38% and an X-ray diffraction intensity ratio of I(440)/I(111) thereof being not less than 18%.
1. A process for producing lithium manganate particles having a primary particle diameter of not less than 1 μm, an average particle diameter (D 50 ) of 1 to 15 μm and forming particles having substantially a single phase, which have a composition represented by the following chemical formula:
Li 1+x Mn 2−x−y Y1 y O 4 +Y2
where Y1 is Al; Y2 is at least one other element constituting a sintering aid having a melting point of not higher than 800° C., x and y satisfy 0.03≦x≦0.15 and 0.05≦y≦0.20, respectively, and Y2 is present in an amount of 0.1 to 2.5 mol % based on Mn;
the Y1 element being dispersed within the respective particles, and
an X-ray diffraction intensity ratio of I(400)/I (111) of the particles being not less than 38% and an X-ray diffraction intensity ratio of I(440)/I(111) thereof being not less than 18%, wherein the lithium manganate particles have a lattice constant of 0.818 to 0.821 nm,
the process comprising the steps of:
mixing lithium carbonate, trimanganese tetraoxide (Mn 3 O 4 ) coated with an Al compound, and the sintering aid having a melting point of not higher than 800° C. with each other; and then
calcining the resulting mixture at a temperature of 800 to 1050° C. to produce the lithium manganate particles.
2. The process according to claim 1 , wherein the lithium manganate particles have a specific surface area of 0.3 to 1.25 m 2 /g as measured by BET method.
3. The process according to claim 1 , wherein the lithium manganate particles have an average particle diameter (D 50 ) of 1 to 9.2 μm.
4. A process for producing the lithium manganate particles according to claim 1 , wherein the trimanganese tetraoxide coated with the Al compound is obtained by adding an aqueous solution comprising a salt of Al to a water suspension comprising trimanganese tetraoxide to adjust a pH value of the water suspension and thereby form a coat of Al compound on a surface of respective particles of the trimanganese tetraoxide.
5. A process for producing the lithium manganate particles according to claim 4 , wherein the coat of Al compound which is formed on the surface of the respective particles of the trimanganese tetraoxide is amorphous as analyzed by X-ray diffraction.
6. A process for producing the lithium manganate particles according to claim 1 , wherein the trimanganese tetraoxide is substantially in the form of a single crystal.
7. A process for producing the lithium manganate particles according to claim 1 , wherein the trimanganese tetraoxide has an average particle diameter of not less than 1 μm.
8. A process for producing the lithium manganate particles according to claim 1 , wherein the sintering aid has a melting point of not higher than 800° C., is a boron compound and Y2 is B (boron).
9. A process for producing the lithium manganate particles according to claim 1 , wherein Y2 is B (boron).