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EP-4741349-A1 - METHOD FOR PRODUCING POSITIVE ELECTRODE ACTIVE MATERIAL

EP4741349A1EP 4741349 A1EP4741349 A1EP 4741349A1EP-4741349-A1

Abstract

The present invention relates to a method for preparing a positive electrode active material, including (A) mixing a transition metal hydroxide and a lithium raw material to prepare a mixture, and (B) firing the mixture to prepare a lithium transition metal oxide in the form of a single particle, wherein the firing includes a temperature-raising phase in which firing is performed at a temperature raised to 700 °C to 1,000 °C from room temperature and a temperature-maintaining phase in which firing is performed at a constant temperature of 700 °C to 1,000 °C, and in the temperature-raising phase, the temperature-raising from room temperature to a temperature of 400 °C to 500 °C is performed in an atmosphere containing water vapor.

Inventors

  • KIM, SUN TAI
  • JEON, HYE JI
  • NAM, DAE HYEON
  • LEE, JU HO
  • SHIN, HO GEUN
  • YOON, Jin Seul
  • KIM, YOUNG JUN

Assignees

  • LG Chem, Ltd.

Dates

Publication Date
20260513
Application Date
20240820

Claims (9)

  1. A method for preparing a positive electrode active material, the method comprising: (A) mixing a transition metal hydroxide and a lithium raw material to prepare a mixture; and (B) firing the mixture to prepare a lithium transition metal oxide in the form of a single particle, wherein the firing comprises a temperature-raising phase in which firing is performed at a temperature raised to 700 °C to 1,000 °C from room temperature and a temperature-maintaining phase in which firing is performed at a constant temperature of 700 °C to 1,000 °C, and in the temperature-raising phase, the temperature-raising from room temperature to a temperature of 400 °C to 500 °C is performed in an atmosphere containing water vapor.
  2. The method of claim 1, wherein the transition metal hydroxide contains at least 80 mol% of nickel among total transition metals.
  3. The method of claim 1, wherein the transition metal hydroxide has a composition represented by Formula 1 below: [Formula 1] Ni a1 Co b1 Mn c1 M 1 d1 (OH) 2 wherein, in Formula 1 above, M 1 is at least one selected from the group consisting of Al, Zr, B, W, Mg, Hf, Ta, Ti, Sr, Ba, Ce, F, P, S, and La, and 0.8≤a1<1.0, 0<b1<0.2, 0<c1<0.2, and 0≤d1≤0.1.
  4. The method of claim 1, wherein the transition metal hydroxide and the lithium raw material are mixed such that a molar ratio (M:Li) of transition metal (M) contained in the transition metal hydroxide and lithium (Li) contained in the lithium raw material is 1:0.95 to 1:1.10.
  5. The method of claim 1, wherein the firing comprises a temperature-raising phase in which firing is performed at a temperature raised to 800 °C to 900 °C from room temperature and a temperature-maintaining phase in which firing is performed at a constant temperature of 800 °C to 900 °C.
  6. The method of claim 1, wherein in the temperature-raising phase, the temperature-raising from room temperature to a temperature of 400 °C to 450 °C is performed in an atmosphere containing water vapor.
  7. The method of claim 1, wherein a temperature-raising rate during the temperature-raising from room temperature to a temperature of 700 °C to 1000 °C is 1.0 °C/min to 5.0 °C/min.
  8. The method of claim 1, wherein the atmosphere containing water vapor is an oxidizing atmosphere containing water vapor.
  9. The method of claim 1, wherein the temperature-maintaining phase is performed for 1 hour to 7 hours.

Description

TECHNICAL FIELD Cross-reference to Related Applications The present application claims the benefit of the priority of Korean Patent Application No. 10-2023-0109810, filed on August 22, 2023, which is hereby incorporated by reference in its entirety. Technical Field The present invention relates to a method for preparing a positive electrode active material for a lithium secondary battery. BACKGROUND ART The recent technological development of electric vehicles has resulted in a rising demand for high-capacity secondary batteries, and accordingly, extensive research efforts are directed towards a positive electrode using a high nickel (high Ni) positive electrode active material having excellent capacity properties. The high-Ni positive electrode active material is prepared through a co-precipitation method, and thus the prepared high-Ni positive electrode active material takes the form of a secondary particle in which primary particles are aggregated. However, the active material having the form of a secondary particle exhibits fine cracks in the secondary particle during a prolonged charging and discharging process, causing a side reaction, and the secondary particle also undergoes structural degradation when increasing electrode density for enhancing energy density, thereby causing degradation in energy density and lifespan characteristics due to reduced active material and electrolyte. To overcome the limitations of the high-nickel positive electrode active material in the form of a secondary particle, efforts are being made to develop a single particle-type nickel-based positive electrode active material. The single particle-type nickel-based positive electrode active material hardly exhibits particle breakage even when the electrode density is increased for a high energy density. Meanwhile, in typical methods for preparing single particle-type lithium transition metal oxide, additives to promote crystallization were added, excess lithium raw materials were used, or firing was performed at high temperatures for a long duration. However, the addition of additives left behind impurities, the use of excess lithium raw materials reduced capacity or left unreacted residual lithium due to the introduction of excess lithium into a positive electrode material, and the high-temperature firing for a long duration resulted in low productivity. Consequently, there is a need to develop a method for preparing single particle-type positive electrode active materials exhibiting excellent monodispersity and leaving no residual lithium. DISCLOSURE OF THE INVENTION TECHNICAL PROBLEM The present invention is intended to provide a method for preparing a positive electrode active material capable of improving the monodispersity and quality of a positive electrode active material. However, tasks of the present invention are not limited to the aforesaid, but other tasks not described herein will be clearly understood by those skilled in the art from descriptions below. TECHNICAL SOLUTION To address the above-described tasks, the present invention provides a method for preparing a positive electrode active material. (1) The present invention provides a method for preparing a positive electrode active material, including (A) mixing a transition metal hydroxide and a lithium raw material to prepare a mixture, and (B) firing the mixture to prepare a lithium transition metal oxide in the form of a single particle, wherein the firing includes a temperature-raising phase in which firing is performed at a temperature raised to 700 °C to 1,000 °C from room temperature and a temperature-maintaining phase in which firing is performed at a constant temperature of 700 °C to 1,000 °C, and in the temperature-raising phase, the temperature-raising from room temperature to a temperature of 400 °C to 500 °C is performed in an atmosphere containing water vapor.(2) The present invention provides the method according to (1) above, wherein the transition metal hydroxide contains at least 80 mol% of nickel among total transition metals.(3) The present invention provides the method according to (1) or (2) above, wherein the transition metal hydroxide has a composition represented by Formula 1 below.         [Formula 1]     Nia1Cob1Mnc1M1d1(OH)2 In Formula 1 above, M1 is at least one selected from the group consisting of Al, Zr, B, W, Mg, Hf, Ta, Ti, Sr, Ba, Ce, F, P, S, and La, and0.8≤a1<1.0, 0<b1<0.2, 0<c1<0.2, and 0≤d1≤0.1.(4) The present invention provides the method according to any one of (1) to (3) above, wherein the transition metal hydroxide and the lithium raw material are mixed such that a molar ratio (M:Li) of transition metal (M) contained in the transition metal hydroxide and lithium (Li) contained in the lithium raw material is 1:0.95 to 1:1.10.(5) The present invention provides the method according to any one of (1) to (4) above, wherein the firing includes a temperature-raising phase in which firing is performed at a temperature rai