Transition metal-containing composite hydroxide and production method thereof, and production method of positive electrode active material for nonaqueous electrolyte secondary battery

Patent metadata

Field	Value
Publication number	US-11024839-B2
Application number	US-201716461072-A
Country	US
Kind code	B2
Filing date	Nov 21, 2017
Priority date	Nov 22, 2016
Publication date	Jun 1, 2021
Grant date	Jun 1, 2021

Abstract

A transition metal-containing composite hydroxide comprises secondary particles having: a center portion of fine primary particles; and an outer-shell portion having a high-density layer of plate-shaped primary particles formed outside the center portion, a low-density layer of the fine primary particles formed outside the high-density layer, and an outer-shell layer of the plate-shaped primary particles formed outside the low-density layer. The composite hydroxide is obtained by a method comprising a nucleation step in an oxidizing atmosphere and a particle growth step, the particle growth step comprising: a first stage of maintaining the oxidizing atmosphere; a second stage of switching to and maintaining a non-oxidizing atmosphere; a third stage of switching again to and maintaining the oxidizing atmosphere; and a fourth stage of switching again to and maintaining the non-oxidizing atmosphere.

First claim

The invention claimed is:

1. A transition metal-containing composite hydroxide comprising secondary particles respectively formed by aggregates of plate-shaped primary particles and fine primary particles having a smaller particle size than the plate-shaped primary particles;
the secondary particles comprising: a center portion constructed by the fine primary particles; and an outer-shell portion having a high-density layer formed on the outside of the center portion and constructed by the plate-shaped primary particles, a low-density layer formed on the outside of the high-density layer and constructed by the fine primary particles, and an outer-shell layer formed on the outside of the low-density layer and constructed by the plate-shaped primary particles.

2. The transition metal-containing composite hydroxide according to claim 1 , wherein the average ratio of the outer diameter of the center portion with respect to the particle size of the secondary particles is within a range of 35% to 85%; the average ratio of the sum of the thicknesses of the high-density layer and the outer shell layer with respect to the particle size of the secondary particles is within a range of 5% to 30%; the average ratio of the thickness of the low-density layer with respect to the particle size of the secondary particles is within a range of 2% to 20%; and the ratio of respective thicknesses of the high-density layer and the outer-shell layer with respect to the particle size of the secondary particles is within a range of 2.5% to 15%.

3. The transition metal-containing composite hydroxide according to claim 1 , wherein the outer-shell portion further comprises between the low-density layer and the outer-shell layer: a second high-density layer formed on the outside of the low-density layer and constructed by the plate-shaped primary particles; and a second low-density layer formed on the outside of the second high-density layer and constructed by the fine primary particles.

4. The transition metal-containing composite hydroxide according to claim 3 , wherein the average ratio of the outer diameter of the center portion with respect to the particle size of the secondary particles is within a range of 35% to 80%; the average ratio of the sum of the thicknesses of the high-density layer, the second high-density layer, and the outer-shell layer with respect to the particle size of the secondary particles is within a range of 8% to 30%; the average ratio of the sum of the thicknesses of the low-density layer and the second low-density layer with respect to the particle size of the secondary particles is within a range of 2% to 20%; the ratio of the respective thicknesses of the high-density layer, the second high-density layer, and the outer-shell layer with respect to the particle size of the secondary particles is 2.5% to 15%; and the ratio of the respective thicknesses of the low-density layer and the second low-density layer with respect to the particle size of the secondary particles is 1% to 10%.

5. The transition metal-containing composite hydroxide according to claim 1 , wherein the average particle size of the plate-shaped primary particles is within a range of 0.3 μm to 3 μm, and the average primary particle size of the fine primary particles is smaller than the average particle size of the plate-shaped primary particles and is within a range of 0.01 μm to 0.3 μm.

6. The transition metal-containing composite hydroxide according to claim 1 , wherein the average particle size of the secondary particles is within a range of 1 μm to 15 μm, and the value of [(d90−d10)/average particle size] as an index indicating the spread of the particle size distribution of the secondary particles is 0.65 or less.

7. The transition metal-containing composite hydroxide according to claim 1 , having a composition represented by a general formula (A): Ni x Mn y Co z M t (OH) 2+a (where x+y+z+t=1, 0.3≤x≤0.95, 0.05≤y≤0.55, 0≤z≤0.4, 0≤t≤0.1, 0≤a≤0.5, and M is one or more additional element selected from the group consisting of Mg, Ca, Al, Ti, V, Cr, Zr, Nb, Mo, Hf, Ta, and W).

8. The transition metal-containing composite hydroxide according to claim 7 , wherein the additional element M is uniformly distributed inside the secondary particles of the transition metal composite hydroxide, and/or a surface of the secondary particles of the transition metal composite hydroxide is coated by a compound that includes the additional element M.

9. A method for producing a transition metal-containing composite hydroxide as a precursor of a positive electrode active material for a secondary battery, by mixing a raw material aqueous solution including at least a transition metal element and an aqueous solution including a complexing agent to form a reaction aqueous solution, and performing a crystallization reaction, the method comprising:
a nucleation step in which nucleation is performed in an oxidizing atmosphere in which the pH value at a standard liquid temperature of 25° C. of the reaction aqueous solution is adjusted to be within a range of 12.0 to 14.0, and the oxygen concentration exceeds 5% by volume; and
a particle growth step in which the pH value at a standard liquid temperature 25° C. of the reaction aqueous solution including the nuclei obtained in the nucleation step is adjusted to lower than the pH value of the nucleation step and to be within a range of 10.5 to 12.0 to cause to growth of the nuclei; and
the particle growth step comprising:
a first stage of maintaining the oxidizing atmosphere from the start of the particle growth step;
a second stage after the first stage of switching from the oxidizing atmosphere to a non-oxidizing atmosphere in which the oxygen concentration is 5% by volume or less, and maintaining the non-oxidizing atmosphere;
a third stage after the second stage of switching from the non-oxidizing atmosphere to the oxidizing atmosphere, and maintaining the oxidizing atmosphere; and
a fourth stage after the third stage of switching from the oxidizing atmosphere to the non-oxidizing atmosphere, and maintaining the non-oxidizing atmosphere.

10. The method for producing a transition metal-containing composite hydroxide according to claim 9 , wherein the time of the first stage is within a range of 0.5% to 20% with respect to the total time of the particle growth step; the time of the second stage is within a range of 10% to 80% with respect to the total time of the particle growth step; the time of the third stage is within a range of 2% to 30% with respect to the total time of the particle growth step; and the time of the fourth stage is within a range of 10% to 80% with respect to the total time of the particle growth step.

11. The method for producing a transition metal-containing composite hydroxide according to claim 9 further comprising:
a fifth stage after the fourth stage of switching from the non-oxidizing atmosphere to the oxidizing atmosphere, and maintaining the oxidizing atmosphere; and
a sixth stage after the fifth stage of switching from the oxidizing atmosphere to the non-oxidizing atmosphere, and maintaining the non-oxidizing atmosphere.

12. The method for producing a transition metal-containing composite hydroxide according to claim 11 , wherein the time of the first stage is within a range of 0.5% to 20% with respect to the total time of the particle growth step; the time of the second stage is within a range of 10% to 75% with respect to the total time of the particle growth step; the time of the third stage is within a range of 2% to 30% with respect to the total time of the particle growth step; the time of the fourth stage is within a range of 10% to 75% with respect to the tot

Assignees

• Sumitomo Metal Mining Co

Inventors

• Toma Takahiro
• Senba Hiroko
• Aida Taira
• Komukai Tetsufumi

Classifications

• C01G53/82 Primary

  Compounds containing nickel, with or without oxygen or hydrogen, and containing two or more other elements · CPC title

• H01M10/0525

  Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries · CPC title

• C01P2004/61

  Micrometer sized, i.e. from 1-100 micrometer · CPC title

• H01M4/366

  as layered products · CPC title

• C01P2004/03

  obtained by SEM · CPC title