Lithium-nickel-cobalt-maganese containing composite oxide, material for positive electrode active material for lithium secondary battery, and methods for producing these
Coagulated particles of nickel-cobalt-manganese hydroxide wherein primary particles are coagulated to form secondary particles are synthesized by allowing an aqueous solution of a nickel-cobalt-manganese salt, an aqueous solution of an alkali-metal hydroxide, and an ammonium-ion donor to react under specific conditions; and a lithium-nickel-cobalt-manganese-containing composite oxide represented by a general formula, Li p Ni x Mn 1-x-y Co y O 2-q F q (where 0.98≦p≦1.07, 0.3≦x≦0.5, 0.1≦y≦0.38, and 0≦q≦0.05), which is a positive electrode active material for a lithium secondary cell having a wide usable voltage range, a charge-discharge cycle durability, a high capacity and high safety, is obtained by dry-blending coagulated particles of nickel-cobalt-manganese composite oxyhydroxide formed by making an oxidant to act on the coagulated particles with a lithium salt, and firing the mixture in an oxygen-containing atmosphere.
1. A method for manufacturing a lithium-nickel-cobalt-manganese-containing composite oxide represented by a general formula, Li p Ni x Mn 1−x−y Co y O 2−q F q (where 0.98≦p≦1.07, 0.3≦x≦0.5, 0.1≦y≦0.38, and 0≦q≦0.05), comprising:
a step for synthesizing coagulated particles of a nickel-cobalt-manganese composite hydroxide wherein primary particles obtained by precipitating the nickel-cobalt-manganese composite hydroxide are coagulated to form secondary particles, by supplying an aqueous solution of a nickel-cobalt-manganese salt, an aqueous solution of an alkali-metal hydroxide and an ammonium-ion donor continuously or intermittently to a reaction system, and making the reaction proceed in a state wherein the temperature of said reaction system is substantially constant within a range between 30 and 70° C., and pH is maintained at a substantially constant value within a range between 10and 13;
a step for synthesizing coagulated particles of a nickel-cobalt-manganese composite oxyhydroxide by making an oxidant act on said coagulated composite hydroxide particles; and
a step for dry-blending at least said coagulated composite oxyhydroxide particles and a lithium salt, and firing the mixture in an oxygen-containing atmosphere.
2. The method for manufacturing a lithium-nickel-cobalt-manganese-containing composite oxide according to claim 1 , wherein the lithium salt is lithium carbonate.
3. A material for a positive electrode active material for a lithium secondary cell consisting of coagulated particles of a nickel-cobalt-manganese composite oxyhydroxide represented by a general formula, Ni x Mn 1−x−y Co y OOH (where 0.3≦x≦0.5, and 0.1≦y≦0.38), formed by synthesizing coagulated particles of a nickel-cobalt-manganese composite hydroxide wherein primary particles obtained by precipitating the nickel-cobalt-manganese composite hydroxide are coagulated to form secondary particles, by supplying an aqueous solution of a nickel-cobalt-manganese salt, an aqueous solution of an alkali-metal hydroxide and an ammonium-ion donor continuously or intermittently to a reaction system, and making the reaction proceed in a state wherein the temperature of said reaction system is substantially constant within a range between 30and 70° C., and pH is maintained at a substantially constant value within a range between 10and 13; and making an oxidant act on said coagulated composite hydroxide particles.
4. The material for a positive electrode active material for a lithium secondary cell according to claim 3 , wherein a specific surface area is 4to 30 m 2 /g.
5. The material for a positive electrode active material for a lithium secondary cell according to claim 3 , wherein a density of a compressed powder is 2.0 g/cm 3 or more.
6. The material for a positive electrode active material for a lithium secondary cell according to claim 3 , wherein a half-value width of a diffraction peak when 2θ is 19±1° in X-ray diffraction using Cu-Kα lines is 0.3 to 0.5.
7. A method for manufacturing the material for a positive electrode active material for a lithium secondary cell represented by a general formula, Ni x Mn 1−x−y C y OOH (where 0.3≦x≦0.5, and 0.1≦y≦0.38), according to claim 3 , comprising:
a step for synthesizing the coagulated particles of the nickel-cobalt-manganese composite hydroxide wherein the primary particles obtained by precipitating the nickel-cobalt-manganese composite hydroxide are coagulated to form the secondary particles, by supplying the aqueous solution of the nickel-cobalt-manganese salt, the aqueous solution of the alkali-metal hydroxide and the ammonium-ion donor continuously or intermittently to the reaction system, and making the reaction proceed in the state wherein the temperature of said reaction system is substantially constant within the range between 30 and 70° C., and pH is maintained at the substantially constant value within the range between 10 and 13; and
a step for synthesizing coagulated particles of a nickel-cobalt-manganese composite oxyhydroxide by making the oxidant act on said coagulated composite hydroxide particles.