Positive active material comprising a continuous concentration gradient of a metal composition for lithium battery, method of preparing the same, and lithium battery including the same
First Claim
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1. A positive active material for a lithium battery, comprising:
- an internal bulk part and an external bulk part surrounding the internal bulk part,whereina metal composition is distributed in a continuous concentration gradient from the interface between the internal bulk part and the external bulk part to a surface of the active materialthe internal bulk part comprises a first compound including Ni, Co, and Mn, wherein the Ni in the first compound ranges from 60 mole % to 95 mole %, andthe external bulk part comprises a second compound including Ni, and Mn, wherein the Ni in the second compound ranges from 5 mole % to 60 mole %,whereinthe positive active material is spherical in shape;
at least one of the internal bulk part and the external bulk part has a layered crystalline structure;
metal composition of the external bulk part is distributed in a continuous concentration gradient; and
prepared by;
(i) mixing a metal salt aqueous solution comprising nickel, cobalt, manganese, and optionally a metal, wherein the metal is at least one element selected from the group consisting of Mg, Al, Cr, V, Ti, Cr, Fe, Zr, Zn, Si, Y, Nb, Ga, Sn, Mo, W, and combinations thereof, a chelating agent, and a basic aqueous solution in a reactor to provide a first metal hydroxide precipitate, wherein the chelating agent and the metal salt aqueous solution are mixed in a mole ratio of 0.2 to 0.5;
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(ii) introducing metal mixture solutions with different concentrations to the reactor, and simultaneously introducing an ammonia aqueous solution and a basic aqueous solution into the reactor to provide a second metal hydroxide precipitate on a surface of the first metal hydroxide precipitate with a concentration gradient;
(iii) drying or heating at least one of first metal hydroxide precipitates and the second metal hydroxide precipitates to provide an active material precursor; and
(iv) creating a positive active material by mixing the active material precursor and a lithium salt.
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Abstract
A positive active material according to one embodiment of the present invention includes an internal bulk part and an external bulk part surrounding the internal bulk part and has a continuous concentration gradient of the metal composition from an interface between the internal bulk part and the external bulk part to the surface of the active material. The provided positive active material in which the metal composition is distributed in a continuous concentration gradient has excellent electrochemical characteristics such as a cycle life, capacity, and thermal stability.
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Citations
17 Claims
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1. A positive active material for a lithium battery, comprising:
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an internal bulk part and an external bulk part surrounding the internal bulk part, wherein a metal composition is distributed in a continuous concentration gradient from the interface between the internal bulk part and the external bulk part to a surface of the active material the internal bulk part comprises a first compound including Ni, Co, and Mn, wherein the Ni in the first compound ranges from 60 mole % to 95 mole %, and the external bulk part comprises a second compound including Ni, and Mn, wherein the Ni in the second compound ranges from 5 mole % to 60 mole %, wherein the positive active material is spherical in shape; at least one of the internal bulk part and the external bulk part has a layered crystalline structure; metal composition of the external bulk part is distributed in a continuous concentration gradient; and
prepared by;(i) mixing a metal salt aqueous solution comprising nickel, cobalt, manganese, and optionally a metal, wherein the metal is at least one element selected from the group consisting of Mg, Al, Cr, V, Ti, Cr, Fe, Zr, Zn, Si, Y, Nb, Ga, Sn, Mo, W, and combinations thereof, a chelating agent, and a basic aqueous solution in a reactor to provide a first metal hydroxide precipitate, wherein the chelating agent and the metal salt aqueous solution are mixed in a mole ratio of 0.2 to 0.5;
1;(ii) introducing metal mixture solutions with different concentrations to the reactor, and simultaneously introducing an ammonia aqueous solution and a basic aqueous solution into the reactor to provide a second metal hydroxide precipitate on a surface of the first metal hydroxide precipitate with a concentration gradient; (iii) drying or heating at least one of first metal hydroxide precipitates and the second metal hydroxide precipitates to provide an active material precursor; and (iv) creating a positive active material by mixing the active material precursor and a lithium salt. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
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Specification