Nickel composite hydroxide and manufacturing method thereof, cathode active material for nonaqueos-electrolyte secondary battery and manufacturing method thereof, and nonaqueous-electrolyte secondary battery
Provided are a cathode active material having a suitable particle size and high uniformity, and a nickel composite hydroxide as a precursor of the cathode active material. When obtaining nickel composite hydroxide by a crystallization reaction, nucleation is performed by controlling a nucleation aqueous solution that includes a metal compound, which includes nickel, and an ammonium ion donor so that the pH value at a standard solution temperature of 25° C. becomes 12.0 to 14.0, after which, particles are grown by controlling a particle growth aqueous solution that includes the formed nuclei so that the pH value at a standard solution temperature of 25° C. becomes 10.5 to 12.0, and so that the pH value is lower than the pH value during nucleation. The crystallization reaction is performed in a non-oxidizing atmosphere at least in a range after the processing time exceeds at least 40% of the total time of the particle growth process from the start of the particle growth process where the oxygen concentration is 1 volume % or less, and with controlling an agitation power requirement per unit volume into a range of 0.5 kW/m 3 to 4 kW/m 3 at least during the nucleation process.
1. A manufacturing method for a cathode active material for a nonaqueous-electrolyte secondary battery that is essentially composed of a lithium nickel composite oxide that is expressed by the general expression:
Li 1+u Ni x Mn y Co z M t O 2 , where
−0.05≤u≤0.50, x+y+z+t=1, 0.3≤x, 0≤y≤0.55, 0≤z≤0.4, 0≤t≤0.1, and M is one or more kind of additional element that is selected from among Al, Ti, V, Cr, Zr, Nb, Mo, Hf, Ta and W,
and has a hexagonal crystal structure having a layered structure;
comprising:
a mixing process wherein a nickel composite hydroxide and/or heat-treated particles thereof is mixed with a lithium compound to form a mixture of the nickel composite hydroxide and/or heat-treated particles thereof and the lithium compound; and
a calcination process that calcines the mixture that was formed in the mixing process in an oxidizing atmosphere at 650° C. to 1000° C.
wherein
the nickel composite hydroxide that is expressed by the general expression:
Ni x Mn y Co z M t (OH) 2+a , where
x+y+z+t=1, 0.3≤x, 0≤y≤0.55, 0≤z≤0.4, 0≤t≤0.1, 0≤a≤0.5, and M is one or more kind of additional element that is selected from among Al, Ti, V, Cr, Zr, Nb, Mo, Hf, Ta and W,
wherein the nickel composite hydroxide comprises nearly spherical secondary particles that are formed by plural primary particles clumping together; the secondary particles having an average particle size that is greater than 7 μm and less than or equal to 15 μm, and a value [(d90−d10)/average particle size], which is an index that indicates the extent of the particle size distribution, is 0.55 or less, and the average particle size of the primary particles that constitute the secondary particles is in the range 0.3 μm to 3 μm,
wherein the nickel composite hydroxide comprises secondary particles that can either (a) have a dense structure that is dense from the particle's outside to its inside; or (b) have a center section composed of minute primary particles having an average particle size of 0.01 μm to 3 μm and an outer-shell section surrounding the center section, the outer-shell section composed of primary particles that are larger than the minute primary particles, and the nickel content and the manganese content of the nickel composite hydroxide in the general expression being 0.3≤x≤0.7, and 0.1≤y≤0.55.
2. The manufacturing method for the cathode active material for a nonaqueous-electrolyte secondary battery according to claim 1 further comprising a heat treatment process before the mixing process that heats the nickel composite hydroxide at a temperature of 105° C. to 750° C., to afford heat-treated nickel composite hydroxide particles.
3. The manufacturing method for the cathode active material for a nonaqueous-electrolyte secondary battery according to claim 1 , wherein the mixture is adjusted so that the ratio of the sum of the atoms of metals other than lithium that are included in the mixture and the number of atoms of lithium is 1:0.95 to 1.5.
4. The manufacturing method for the cathode active material for a nonaqueous-electrolyte secondary battery according to claim 1 , wherein the lithium compound is lithium hydroxide, lithium carbonate, or a mixture of these.
5. The manufacturing method for the cathode active material for a nonaqueous-electrolyte secondary battery according to claim 1 wherein, during the calcination process, pre-calcination is performed beforehand at a temperature of 350° C. to 800° C.
6. A manufacturing method for a cathode active material for a nonaqueous-electrolyte secondary battery that is essentially composed of a lithium nickel composite oxide that is expressed by the general expression:
Li 1+u Ni x Mn y Co z M t O 2 , where
−0.05≤u≤0.50, x+y+z+t=1, 0.3≤x, 0≤y≤0.55, 0≤z≤0.4, 0≤t≤0.1, and M is one or more kind of additional element that is selected from among Al, Ti, V, Cr, Zr, Nb, Mo, Hf, Ta and W,
and has a hexagonal crystal structure having a layered structure; comprising:
a process obtaining a nickel composite hydroxide by a crystallization reaction, the nickel composite hydroxide expressed by a general expression:
Ni x Mn y Co z M t (OH) 2+a ,
where x+y+z+t=1, 0.3≤x, 0≤y≤0.55, 0≤z≤0.4, 0≤t≤0.1, 0≤a≤0.5, and
M is one or more kind of additional element that is selected from among Al, Ti, V, Cr, Zr, Nb, Mo, Hf, Ta and W,
the process obtaining the nickel composite hydroxide comprising:
a nucleation process that performs nucleation by controlling a nucleation aqueous solution that includes a metal compound that contains at least nickel and an ammonium ion donor so that a pH value at a standard solution temperature of 25° C. becomes 12.0 to 14.0; and
a particle growth process causes nuclei that were formed in the nucleation process to grow by controlling a particle growth aqueous solution that contains the nuclei so that the pH value at a standard solution temperature of 25° C. becomes 10.5 to 12.0, and so that the pH value during the particle growth process is lower than the pH value during the nucleation process; and
the crystallization reaction being performed in a non-oxidizing atmosphere at least in a range after the processing time exceeds at least 40% of the total time of the particle growth process from the start of the particle growth process where the oxygen concentration is 1 volume % or less, and with controlling an agitation power requirement per unit volume into a range of 0.5 kW/m 3 to 4 kW/m 3 at least during the nucleation process,
a mixing process wherein a nickel composite hydroxide and/or a heat-treated particles thereof is mixed with a lithium compound to form a mixture of the nickel composite hydroxide and/or the heat-treated particles and the lithium compound, the heat-treated particles including a heat-treated nickel composite hydroxide obtained by heat-treating the nickel composite hydroxide, a nickel composite oxide obtained by heat-treating the nickel composite hydroxide, or a mixture of these; and
a calcination process that calcines the mixture that was formed in the mixing process in an oxidizing atmosphere at 650° C. to 1000° C.
7. The manufacturing method for the cathode active material for a nonaqueous-electrolyte secondary battery according to claim 6 ,
the nickel composite hydroxide obtained by the crystallization reaction is nearly spherical secondary particles that are formed by plural primary particles clumping together; the secondary particles having an average particle size that is greater than 7 μm and less than or equal to 15 μm, and a value [(d90−d10)/average particle size], which is an index that indicates the extent of the particle size distribution, is 0.55 or less.
8. The manufacturing method for the cathode active material for a nonaqueous-electrolyte secondary battery according to claim 6 , wherein, during the whole process of the nucleation process and the particle growth process, the crystallization reaction is performed in a non-oxidizing atmosphere where the oxygen concentration is 1 volume % or less.
9. The manufacturing method for the cathode active material for a nonaqueous-electrolyte secondary battery according to claim 6 , wherein the nickel content and the manganese content of the nickel composite hydroxide are regulated in the general expression so as to be 0.3≤x≤0.7 and 0.1≤y≤0.55, respectively, and the nucleation is performed in the nucleation process in an oxidizing atmosphere where the oxygen concentration is greater than 1 volume %, after which the atmosphere is switched from the oxidizing atmosphere to the non-oxidizing atmosphere in which the oxygen concentration is 1 volume % or less in a range of from 0% to 40% of the total time of the particle growth process from the start of the particle growth process.
10. The manufacturing method for the cathode active material for a nonaqueous-electrolyte secondary battery according to claim 6 further comprising a heat treatment process before the mixing process that heats the nickel composite hydroxide at a temperature of 105° C. to 750° C., to afford heat-treated nickel composite hydroxide particles.
11. The manufacturing method for the cathode active material for a nonaqueous-electrolyte secondary battery according to claim 6 , wherein the mixture is adjusted so that the ratio of the sum of the atoms of metals other than lithium that are included in the mixture and the number of atoms of lithium is 1:0.95 to 1.5.
12. The manufacturing method for the cathode active material for a nonaqueous-electrolyte secondary battery according to claim 6 , wherein the lithium compound is lithium hydroxide, lithium carbonate, or a mixture of these.
13. The manufacturing method for the cathode active material for a nonaqueous-electrolyte secondary battery according to claim 6 wherein, during the calcination process, pre-calcination is performed beforehand at a temperature of 350° C. to 800° C.