Li-Ni composite oxide particles for non-aqueous electrolyte secondary cell, process for producing the same, and non-aqueous electrolyte secondary cell
The present invention relates to Li—Ni composite oxide particles for a non-aqueous electrolyte secondary cell which have a large charge/discharge capacity, an excellent packing density and excellent storage performance. The Li—Ni composite oxide particles for a non-aqueous electrolyte secondary cell which have a composition represented by the formula: Li x Ni 1-y-z Co y Al z 0 2 in which 0.9<x<1.3; 0.1<y<0.3; and 0<z<0.3, wherein the composite oxide particles have a rate of change in specific surface area of not more than 10% as measured between before and after applying a pressure of 1 t/cm 2 thereto, and a sulfate ion content of not more than 1.0%, can be produced by mixing Ni—Co hydroxide particles having a sulfate ion content of not more than 1.0% whose surface is coated with an Al compound having a primary particle diameter of not more than 1 μm, with a lithium compound; and calcining the resulting mixture.
1. Li—Ni composite oxide particles for a non-aqueous electrolyte secondary cell, having a composition represented by the formula:
Li x Ni 1-y-z Co y Al z O 2
in which 0.9<x<1.3; 0.1<y<0.3; and 0<z<0.3,
wherein the composite oxide particles have a rate of change in specific surface area of not more than 10% as measured between before and after applying a pressure of 1 t/cm 2 thereto, and a sulfate ion content of not more than 1.0%.
2. Li—Ni composite oxide particles for a non-aqueous electrolyte secondary cell according to claim 1 , wherein the composite oxide particles have a density of not less than 2.85 g/mL as measured upon applying a pressure of 1 t/cm 2 thereto, and a sulfate ion content of not more than 1.0%.
3. A process for producing the Li—Ni composite oxide particles as defined in claim 1 , comprising the steps of;
mixing Ni—Co hydroxide particles having a sulfate ion content of not more than 1.0% whose surface is coated with an Al compound having a primary particle diameter of not more than 1 μm or a mixture of Ni—Co hydroxide particles having a sulfate ion content of not more than 1.0% and aluminum hydroxide having a sulfate ion content of not more than 0.1% and a primary particle diameter of not more than 1 μm, with a lithium compound; and
calcining the resulting mixture.
4. A process for producing the Li—Ni composite oxide particles, wherein the lithium compound is lithium hydroxide, and a content of lithium carbonate in the lithium hydroxide is less than 5%.
5. A non-aqueous electrolyte secondary cell using a positive electrode comprising a cathode material comprising the Li—Ni composite oxide particles for a non-aqueous electrolyte secondary cell as defined in claim 1 .