KR-102962309-B1 - POSITIVE ELECTRODE ACTIVE MATERIAL AND MANUFACTURING METHOD OF THE SAME

Abstract

The present invention relates to a method for manufacturing a positive electrode active material capable of minimizing the content of residual lithium and Ni²⁺ to improve the capacity, efficiency, and lifespan performance of a lithium secondary battery. Specifically, the present invention relates to a method for manufacturing a positive electrode active material comprising the step of mixing a transition metal precursor containing 70 mol% or more of nickel with respect to the total molar amount of transition metals with a lithium-containing raw material, and then calcining the mixture under positive pressure conditions of 1.5 kPa or more and less than 10 kPa to produce a lithium transition metal oxide. Furthermore, the present invention relates to a positive electrode active material comprising a lithium transition metal oxide containing 70 mol% or more of nickel with respect to the total molar amount of transition metals excluding lithium, and satisfying Formula 1 described in this specification.

Inventors

• 김동환
• 남재근
• 노태민
• 오명환
• 정상훈

Assignees

• 주식회사 엘지화학

Dates

Publication Date

20260508

Application Date

20200924

Claims (11)

1. A method for manufacturing a positive electrode active material comprising the step of mixing a transition metal precursor containing 70 mol% or more of nickel relative to the total molar amount of the transition metal with a lithium-containing raw material, and then calcining under positive pressure conditions of 1.5 kPa or more and less than 10 kPa to produce a lithium transition metal oxide.
2. In claim 1, A method for manufacturing an anode active material in which the above transition metal precursor is a compound represented by the following chemical formula 1 or chemical formula 2: [Chemical Formula 1] [Ni a Co b M 1 c M 2 d ](OH) 2 [Chemical Formula 2] [Ni a Co b M 1 c M 2 d ]O·OH In the above Chemical Formulas 1 and 2, The above M1 is one or more selected from Mn and Al, and The above M2 is one or more selected from B, Mg, Ca, Ti, V, Cr, Fe, Zn, Ga, Y, Zr, Nb, Mo, Ta, and W, and 0.7≤a<1, 0<b<0.3, 0<c<0.3, 0≤d≤0.1, a+b+c+d=1.
3. In claim 1, A method for manufacturing a positive electrode active material in which the above transition metal precursor and the above lithium-containing raw material are mixed in a molar ratio of 1:0.9 to 1:1.2.
4. In claim 1, A method for manufacturing a positive active material, wherein the above calcination is performed under positive pressure conditions of 1.5 kPa to 5 kPa.
5. In claim 1, A method for manufacturing a positive electrode active material in which the above calcination is performed under an oxygen atmosphere.
6. In claim 1, A method for manufacturing a positive electrode active material, wherein the above calcination is performed under an oxygen atmosphere with an oxygen concentration of 90 volume% to 99.99 volume%.
7. In claim 1, A method for manufacturing a positive electrode active material, wherein the above calcination is performed at 700°C to 900°C.
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Description

Positive electrode active material and manufacturing method of the same The present invention relates to a positive electrode active material and a method for manufacturing a positive electrode active material. With the recent increase in technological development and demand for mobile devices and electric vehicles, the demand for rechargeable batteries as an energy source is rapidly rising. Among these rechargeable batteries, lithium-ion batteries, which possess high energy density and voltage, long cycle life, and low self-discharge rate, have been commercialized and are widely used. Lithium transition metal composite oxides are used as cathode active materials for lithium secondary batteries, and among them, lithium cobalt composite metal oxides such as LiCoO2, which have high operating voltage and excellent capacity characteristics, are mainly used. However, LiCoO2 has poor thermal properties due to the descaling of its crystal structure caused by lithium removal. In addition, since the above LiCoO2 is expensive, there are limitations to its mass use as a power source in fields such as electric vehicles. As materials to replace the above LiCoO2 , lithium manganese composite metal oxides ( LiMnO2 or LiMn2O4 , etc. ), lithium iron phosphate compounds ( LiFePO4 , etc.), or lithium nickel composite metal oxides ( LiNiO2, etc.) have been developed. Among these, research and development on lithium nickel composite metal oxides is being conducted more actively because they have a high reversible capacity of about 200 mAh/g, making it easy to implement large-capacity batteries. However, the above LiNiO2 has inferior thermal stability compared to LiCoO2 , and there was a problem in that if an internal short circuit occurs due to external pressure or the like while charged, the cathode active material itself decomposes, causing rupture and ignition of the battery. Accordingly, as a method to improve the low thermal stability while maintaining the excellent reversible capacity of the above LiNiO2 , lithium transition metal oxides in which a portion of Ni is substituted with Mn, Co, or Al have been developed. These lithium transition metal oxides are generally manufactured by mixing a transition metal precursor with a lithium-containing raw material (e.g., lithium hydroxide, lithium carbonate, etc.) and then heat-treating it; however, residual lithium remains in the lithium-containing raw material that did not participate in the reaction. This residual lithium causes a problem by increasing the pH of the slurry during the preparation of the slurry for forming the cathode active material layer, thereby inducing solidification of the slurry. Furthermore, residual lithium causes problems with the stability of the battery, such as inducing swelling of the lithium secondary battery, and also causes problems with the electrochemical characteristics of the battery. On the other hand, in the case of lithium transition metal oxides with high nickel content, cation mixing is prone to occur, and locally electrochemically inactive rock salt structures are formed, which consequently causes a problem of reduced battery discharge capacity. Therefore, there is a need to develop a method for manufacturing a lithium transition metal oxide with a high nickel content, that is, a cathode active material with a high nickel content, which can minimize the amount of residual lithium and minimize cation mixing phenomena. Terms and words used in this specification and claims shall not be interpreted as being limited to their ordinary or dictionary meanings, but shall be interpreted in a meaning and concept consistent with the technical spirit of the invention, based on the principle that the inventor can appropriately define the concept of the terms to best describe his invention. In this specification, terms such as “comprising,” “comprising,” or “having” are intended to specify the existence of the implemented features, numbers, steps, components, or combinations thereof, and should be understood as not excluding in advance the existence or addition of one or more other features, numbers, steps, components, or combinations thereof. The present invention will be described in more detail below. Method for manufacturing positive electrode active material The method for manufacturing a positive electrode active material according to the present invention includes the step of mixing a transition metal precursor containing 70 mol% or more of nickel with respect to the total molar amount of transition metal with a lithium-containing raw material, and then calcining under positive pressure conditions of 1.5 kPa or more and less than 10 kPa to produce a lithium transition metal oxide. In conventional methods for manufacturing cathode active materials, the calcination is performed under atmospheric pressure, resulting in the presence of lithium byproducts such as LiOH and Li₂CO₃ that did not react during the calcination process. Additionally, due t