Nickel manganese composite hydroxide particles and manufacturing method thereof, cathode active material for a non-aqueous electrolyte secondary battery and manufacturing method thereof, and a non-aqueous electrolyte secondary battery
To obtain a non-aqueous electrolyte secondary battery having high capacity, high output and good cyclability, nickel manganese composite hydroxide particles are a precursor for a cathode active material having lithium nickel manganese composite oxide with a hollow structure and a small and uniform particle size. An aqueous solution for nucleation includes a metallic compounds that contains nickel and a metallic compound that contains manganese, but does not include a complex ion formation agent that forms complex ions with nickel, manganese and cobalt. After nucleation is performed, an aqueous solution for particle growth is controlled so that the temperature of the solution is 60° C. or greater, and so that the pH value that is measured at a standard solution temperature of 25° C. is 9.5 to 11.5, and is less than the pH value in the nucleation step.
1. A method for manufacturing nickel manganese composite hydroxide particles by a crystallization reaction such that the nickel manganese composite hydroxide particles can be expressed by a general formula Ni x Mn y Co z M t (OH) 2+a
wherein x+y+z+t=1, 0.3≦x≦0.7, 0.1≦y≦0.55, 0≦z≦0.4, 0≦t≦0.1, 0≦a≦0.5, and M is one or more added element that is selected from among Mg, Ca, Al, Ti, V, Cr, Zr, Nb, Mo and W,
the manufacturing method comprising:
a nucleation step of controlling an aqueous solution for nucleation, which includes at least a metallic compound that contains nickel and a metallic compound that contains manganese, and does not include a complex ion formation agent that forms complex ions with nickel, manganese and cobalt, so that the temperature of the solution is 60° C. or greater, and so that the pH value that is measured at a standard solution temperature of 25° C. is 11.5 to 13.5, and generating nuclei as center sections comprising fine primary particles; and
a particle growth step of controlling an aqueous solution for particle growth, which includes the nuclei that were formed in the nucleation step and does not substantially include a complex ion formation agent that forms complex ions with nickel, manganese and cobalt, so that the temperature of the solution is 60° C. or greater, and so that the pH value that is measured at a standard solution temperature of 25° C. is 9.5 to 11.5, and is less than the pH value in the nucleation step, and growing an outer shell section comprising primary particles having a plate shape or needle shape that is larger than the fine primary particles on an outer surface of the nuclei.
2. The manufacturing method for manufacturing nickel manganese composite hydroxide particles according claim 1 , wherein
in the nucleation step and particle growth step, an oxygen concentration inside the reaction tank is controlled to be 10% by volume or less.
3. The manufacturing method for manufacturing nickel manganese composite hydroxide particles according to claim 1 , wherein
the pH value of the aqueous solution for nucleation after the nucleation step has finished is adjusted and the resulting aqueous solution is used as the aqueous solution for particle growth.
4. The manufacturing method for manufacturing nickel manganese composite hydroxide particles according to claim 1 , wherein
a solution that is obtained by adding an aqueous solution, which contains the nuclei formed in the nucleation step, to a component adjustment aqueous solution, which is separate from the aqueous solution for nucleation in which the nuclei were formed, does not substantially include a complex ion formation agent that forms complex ions with nickel, manganese and cobalt, and is controlled so that the solution temperature is 60° C. or greater, and so that the pH value that is measured at a standard solution temperature of 25° C. is 9.5 to 11.5 and is lower than the pH value in the nucleation step, is used as the aqueous solution for particle growth.
5. The manufacturing method for manufacturing nickel manganese composite hydroxide particles according to claim 4 , wherein
the particle growth step starts after part of the liquid component of the aqueous solution for particle growth has been removed.
6. The manufacturing method for manufacturing nickel manganese composite hydroxide particles according to claim 1 , wherein
the nickel composite hydroxide that was obtained in the particle growth step is covered with a compound containing the one or more added elements.
7. Nickel manganese composite hydroxide particles that are expressed by a general formula Ni x Mn y Co z M t (OH) 2+a wherein x+y+z+t=1, 0.3≦x≦0.7, 0.1≦y≦0.55, 0≦z≦0.4, 0≦t≦0.1, 0≦a≦0.5, and M is one or more added element that is selected from among Mg, Ca, Al, Ti, V, Cr, Zr, Nb, Mo and W, and that are spherical shaped secondary particles that are formed by a plurality of aggregate primary particles, wherein the secondary particles have an average particle size of 3 to 7 μm, a value of (d90−d10)/average particle size, which is an index indicating the extent of the particle size distribution, of 0.55 or less, the particles having a center section comprising fine primary particles, and an outer shell section on the outside of the center section comprising plate shaped or needle shaped primary particles that are larger than the fine primary particles, with the thickness of the outer shell section being 0.3 to 3 μm.
8. The nickel manganese composite hydroxide particles according to claim 7 , wherein
the fine primary particles have an average particle size of 0.01 to 0.3 μm, and
the plate shaped or needle shaped primary particles that are larger than the fine primary particles have an average particle size of 0.3 to 3 μm.
9. The nickel manganese composite hydroxide particles according to claim 7 , wherein
the ratio of the thickness of the outer shell section with respect to the particle size of the secondary particles is 10 to 45%.
10. The nickel manganese composite hydroxide particles according to claim 7 , wherein
the one or more added elements are uniformly distributed inside the secondary particles and/or uniformly cover the surface of the secondary particles.