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US-12620588-B2 - Cathode active material precursor for lithium secondary battery, cathode active material for lithium secondary battery and lithium secondary battery

US12620588B2US 12620588 B2US12620588 B2US 12620588B2US-12620588-B2

Abstract

A cathode active material precursor for a lithium secondary battery has a structure of a nickel composite hydroxide. A first peak intensity ratio represented by Equation 1 is 0.5 or more, and a second peak intensity ratio represented by Equation 2 is 0.7 or more. A cathode active material and a lithium secondary battery having a stabilized crystal structure are provided using the cathode active material precursor.

Inventors

  • Mi jung Noh
  • Jeong Bae YOON
  • Je Nam CHOI
  • Sang Bok Kim
  • Jae Ho Choi
  • Dong Wook Ha

Assignees

  • SK INNOVATION CO., LTD.
  • SK ON CO., LTD.

Dates

Publication Date
20260505
Application Date
20221202
Priority Date
20211207

Claims (4)

  1. 1 . A cathode active material precursor for a lithium secondary battery having a structure of a nickel composite hydroxide, wherein the nickel composite hydroxide includes Ni, Co and Mn, and further includes at least one of Mg, Sr, Ba, B, Al, Si, Ti, Zr and W, wherein a first peak intensity ratio represented by Equation 1 is 0.7 or more, and a second peak intensity ratio represented by Equation 2 is in a range from 0.7 to 1.4: First peak intensity ratio= I (101)/ I (001) [Equation 1] Second peak intensity ratio= I (101)/ I (100) [Equation 2] wherein, in Equations 1 and 2, I(101), I(001) and I(100) are peak intensities or maximum peak heights of (101), (001) and (100) planes, respectively, by an X-ray diffraction analysis.
  2. 2 . The cathode active material precursor for a lithium secondary battery of claim 1 , wherein the structure of the nickel composite hydroxide is represented by Chemical Formula 1: Ni 1-x-y-z CO x Mn y M z (OH) 2+a [Chemical Formula 1] wherein, in Chemical Formula 1, M includes at least one selected from the group consisting of Mg, Sr, Ba, B, Al, Si, Ti, Zr and W, 0.02≤x≤0.15, 0≤y≤0.15, 0≤z≤0.1, and −0.5≤a≤0.1.
  3. 3 . The cathode active material precursor for a lithium secondary battery of claim 1 , wherein a molar ratio of nickel among elements other than a hydroxyl group is 0.8 or more.
  4. 4 . The cathode active material precursor for a lithium secondary battery of claim 1 , wherein the first peak intensity ratio is in a range from 0.75 to 1.3.

Description

CROSS-REFERENCE TO RELATED APPLICATION This application claims priority to Korean Patent Application No. 10-2021-0173738 filed on Dec. 7, 2021 in the Korean Intellectual Property Office (KIPO), the entire disclosure of which is incorporated by reference herein. BACKGROUND 1. Field The present invention relates to a cathode active material precursor for a lithium secondary battery, a cathode active material for a lithium secondary battery and a lithium secondary battery. More particularly, the present invention relates to a cathode active material precursor for a lithium secondary battery containing nickel, a cathode active material for a lithium secondary battery containing lithium and nickel and a lithium secondary battery including the cathode active material. 2. Description of the Related Art A secondary battery which can be charged and discharged repeatedly has been widely employed as a power source of a mobile electronic device such as a camcorder, a mobile phone, a laptop computer, etc., according to developments of information and display technologies. Recently, a battery pack including the secondary battery is being developed and applied as an eco-friendly power source of an electric automobile, a hybrid vehicle, etc. The secondary battery includes, e.g., a lithium secondary battery, a nickel-cadmium battery, a nickel-hydrogen battery, etc. The lithium secondary battery is highlighted due to high operational voltage and energy density per unit weight, a high charging rate, a compact dimension, etc. For example, the lithium secondary battery may include an electrode assembly including a cathode, an anode and a separation layer (separator), and an electrolyte immersing the electrode assembly. The lithium secondary battery may further include an outer case having, e.g., a pouch shape for accommodating the electrode assembly and the electrolyte. As an application range of the lithium secondary batteries is extended to large devices such as the electric vehicle, a high-nickel (High-Ni)-based lithium oxide having an increased nickel content is used as a cathode active material for obtaining high capacity of the lithium secondary battery. The cathode active material may be prepared by reacting a nickel-containing precursor and a lithium source. However, a side reaction with the electrolyte and an instability of a chemical structure may be easily caused in the high-nickel-based lithium oxide to degrade a life-span and an operational stability of the lithium secondary battery. Thus, a structural stability of the nickel-containing precursor may be needed to enhance a stability of the cathode active material. For example, Korean Registered Patent Publication No. 10-0821523 discloses a cathode active material including a high nickel-based lithium composite oxide, but fails to consider the structural stability of the nickel-containing precursor. SUMMARY According to an aspect of the present invention, there is provided a cathode active material precursor for a lithium secondary battery having improved structural and chemical stability. According to an aspect of the present invention, there is provided a cathode active material for a lithium secondary battery having improved structural and chemical stability. According to an aspect of the present invention, there is provided a lithium secondary battery including the cathode active material. A cathode active material precursor for a lithium secondary battery has a structure of a nickel composite hydroxide. A first peak intensity ratio represented by Equation 1 is 0.5 or more, and a second peak intensity ratio represented by Equation 2 is 0.7 or more. first peak intensity ratio=I(101)/I(001)  Equation 1 second peak intensity ratio=I(101)/I(100)  Equation 2 In Equations 1 and 2, I(101) and I(100) are peak intensities or maximum peak heights of (101), (001) and (100) planes, respectively, by an X-ray diffraction analysis. In some embodiments, the structure of the nickel composite hydroxide may be represented by Chemical Formula 1. Ni1−x−y−zCoxMnyMz(OH)2+a  Chemical Formula 1 In Chemical Formula 1, M may include at least one selected from the group consisting of Mg, Sr, Ba, B, Al, Si, Ti, Zr and W, 0.02≤x≤0.15, 0≤y≤0.15, 0≤z≤0.1, and −0.5≤a≤0.1. In some embodiments, a molar ratio of nickel among elements other than a hydroxyl group may be 0.8 or more. In some embodiments, the first peak intensity ratio may be in a range from 0.5 to 1.3. In some embodiments, the second peak intensity ratio may be in a range from 0.7 to 1.4. A cathode active material for a lithium secondary battery has a structure of a lithium-nickel-based composite oxide and has an interlayer distance ratio of 0.80 or more defined by Equation 3. interlayer distance ratio=TM slab/Li slab  Equation 3 In Equation 3, TM slab is a thickness of an O-TM-O layer in an octahedral structure (TMO6) containing a transition metal (TM) obtained by a Rietveld method using an X-ray diffraction analysis. Li slab is