Method of producing positive electrode active material for nonaqueous electrolyte secondary battery
A method of producing a positive electrode active material for a nonaqueous electrolyte secondary battery, the method includes preparing nickel-containing composite oxide particles having a ratio 1 D 90 / 1 D 10 of a 90% particle size 1 D 90 to a 10% particle size 1 D 10 in volume-based cumulative particle size distribution is 3 or less; mixing the composite oxide particles and a lithium compound to obtain a first mixture; subjecting the first mixture to a first heat treatment at a first temperature and a second heat treatment at a second temperature higher than the first temperature to obtain a first heat-treated product; and subjecting the first heat-treated material to a dispersion treatment.
1. A method of producing a positive electrode active material for a nonaqueous electrolyte secondary battery, comprising:
providing nickel-containing composite oxide particles having a ratio 1 D 90 / 1 D 10 of a 90% particle size 1 D 90 to a 10% particle size 1 D 10 in volume-based cumulative particle size distribution of 3 or less;
mixing the composite oxide particles and a lithium compound to obtain a first mixture;
subjecting the first mixture to a first heat treatment at a first temperature and a second heat treatment at a second temperature higher than the first temperature to obtain a first heat-treated material; and
dissociating from the first heat-treated material the positive electrode active material,
wherein the positive electrode active material comprises lithium-transition metal composite oxide particles having a ratio 2 D 50 / 2 D SEM of a 50% particle size 2 D 50 in volume-based cumulative particle size distribution to an average particle size 2 D SEM based on electron microscopic observation in a range of 1 to 4,
wherein the lithium-transition metal composite oxide particles have a ratio 2 D 90 / 2 D 10 of a 90% particle size 2 D 90 to a 10% particle size 2 D 10 in volume-based cumulative particle size distribution is 4 or less, and
wherein a molar ratio of nickel in a composition of the lithium-transition metal composite oxide to a total molar number of metals other than lithium is 0.3 to 0.6.
2. The method according to claim 1 , wherein the lithium-transition metal composite oxide further contains cobalt and a molar ratio of cobalt in the composition to a total molar number of metals other than lithium is 0.4 or less.
3. The method according to claim 1 , wherein the lithium-transition metal composite oxide further contains at least one of Mn or Al and a molar ratio of total molar number of Mn and Al in the composition to a total molar number of metals other than lithium is 0.5 or less.
4. The method according to claim 1 , wherein a molar ratio of lithium in the composition to a total molar number of metals other than lithium is 1.0 to 1.3.
5. The method according to claim 1 , wherein a molar ratio of oxygen in the composition to a total molar number of metals other than lithium is 1.9 to 2.1.
6. The method according to claim 1 , wherein the first temperature is in a range of 850° C. to 950° C., and the second temperature is in a range of 980° C. to 1,100° C.
7. The method according to claim 6 , further comprising:
mixing the positive electrode active material dissociated from the first heat-treated material and a lithium compound to obtain a second mixture; and
subjecting the second mixture to a heat treatment to obtain a second heat-treated material.
8. The method according to claim 7 , wherein
the composite oxide particles have a 50% particle size 1 D 50 in volume-based cumulative particle size distribution is in a range of 1 μm to 4 μm, and
the lithium-transition metal composite oxide particles are configured such that the 50% particle size 2 D 50 in volume-based cumulative particle size distribution is in a range of 1 μm to 3 μm.
9. The method according to claim 6 , wherein
the composite oxide particles have a 50% particle size 1 D 50 in volume-based cumulative particle size distribution is in a range of 1 μm to 4 μm, and
the lithium-transition metal composite oxide particles are configured such that the 50% particle size 2 D 50 in volume-based cumulative particle size distribution is in a range of 1 μm to 3 μm.
10. The method according to claim 1 , further comprising:
mixing the positive electrode active material dissociated from the first heat-treated material and a lithium compound to obtain a second mixture; and
subjecting the second mixture to a heat treatment to obtain a second heat-treated material.
11. The method according to claim 10 , wherein
the composite oxide particles have a 50% particle size 1 D 50 in volume-based cumulative particle size distribution is in a range 1 μm to 4 μm, and
the lithium-transition metal composite oxide particles are configured such that the 50% particle size 2 D 50 in volume-based cumulative particle size distribution is in a range of 1 μm to 3 μm.
12. The method according to claim 1 , wherein
the composite oxide particles have a 50% particle size 1 D 50 in volume-based cumulative particle size distribution is in a range of 1 μm to 4 μm, and
the lithium-transition metal composite oxide particles are configured such that the 50% particle size 2 D 50 in volume-based cumulative particle size distribution is in a range of 1 μm to 3 μm.
13. The method according to claim 1 , wherein the ratio 2 D 50 / 2 D SEM of the 2 D 50 to the 2 D SEM is in a range of 1 to 3.