US-12626903-B2 - Cathode active material for lithium secondary battery and method of manufacturing the same

US12626903B2US 12626903 B2US12626903 B2US 12626903B2US-12626903-B2

Abstract

In a method of manufacturing a cathode active material for a lithium secondary battery, a preliminary lithium metal oxide particle is prepared. The preliminary lithium metal oxide particle is cleaned using a boron compound cleaning solution. A cathode active material for a lithium secondary particle includes a lithium metal oxide particle where a ratio of a B+ peak intensity relative to a sum of peak intensities of Li+, B+ and LiB+ fragments by a TOF-SIMS analysis is in a range from 0.03% to 1.5%.

Inventors

Sang Bok Kim
Ji Hoon Choi
Jik Soo Kim
Mi jung Noh
Dong Il Jang
Dong Wook Ha

Assignees

SK ON CO., LTD.

Dates

Publication Date: 20260512
Application Date: 20231213
Priority Date: 20190909

Claims (5)

1 . A cathode active material for a lithium secondary battery, comprising: a lithium metal oxide particle; and a boron (B) element present on at least a portion of a surface of the lithium metal oxide particle, wherein a ratio of a B+ peak intensity relative to a sum of peak intensities of Li+, B+ and LiB+ fragments by a TOF-SIMS (Time of Flight Secondary Ion Mass Spectrometry) analysis is in a range from 0.03% to 1.5%, wherein the lithium metal oxide particle includes Ni, Mn, and Co and a molar ratio of Ni among Ni, Mn, and Co is greater than or equal to 0.5 and less than 1.
2 . The cathode active material for a lithium secondary battery according to claim 1 , wherein the ratio of the B+ peak intensity is in a range from 0.3% to 1.4%.
3 . The cathode active material for a lithium secondary battery according to claim 1 , wherein an amount of boron (B) based on a total weight of the lithium metal oxide particle is in a range from 100 ppm to 800 ppm.
4 . The cathode active material for a lithium secondary battery according to claim 1 , wherein the lithium metal oxide particle includes a doping or a coating which contains at least one of Al, Zr or Ti.
5 . A lithium secondary battery, comprising: a cathode including a cathode active material according to claim 1 ; an anode; and a separation layer interposed between the cathode and the anode.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application is a continuation of U.S. patent application Ser. No. 17/014,314, filed Sep. 8, 2020, which claims priority to Korean Patent Application No. 10-2019-0111483, filed Sep. 9, 2019, the disclosures of which are hereby incorporated by reference in their entireties. BACKGROUND 1. Field of the Invention The present invention relates to a cathode active material for a lithium secondary battery and a method of manufacturing the same. More particularly, the present invention relates to a lithium metal oxide-based cathode active material for a lithium secondary battery and a method of manufacturing the same. 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 a power source of an eco-friendly automobile such as a hybrid automobile. 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 (a 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. A lithium metal oxide may be used as a cathode active material of the lithium secondary battery. An example of the lithium metal oxide may include a nickel-based lithium metal oxide. As an application range of the lithium secondary battery is expanded, greater life-span, high capacity and operation stability are required. When a non-uniformity of a chemical structure occurs due to a lithium precipitation in the lithium metal oxide used as the cathode active material, the lithium secondary battery having desired capacity and life-span may not be obtained. Additionally, when the lithium metal oxide structure is deformed or damaged during repeated charging and discharging, life stability and capacity retention characteristics may be deteriorated. For example, Korean Registered Patent Publication No. 10-0821523 discloses a method of removing lithium salt impurities by washing a lithium composite metal oxide with water. However, a sufficient impurity removal may not be implemented even by the method and a particle surface may be damaged by the washing process. SUMMARY According to an aspect of the present invention, there is provided a cathode active material for a lithium secondary battery having improved operational stability and electrical property, and a method of manufacturing the cathode active material. According to an aspect of the present invention, there is provided a lithium secondary battery having improved operational stability and electrical property. According to exemplary embodiments, in a method of manufacturing a cathode active material for a lithium secondary battery, a preliminary lithium metal oxide particle may be prepared. The preliminary lithium metal oxide particle may be cleaned using a boron compound cleaning solution. In some embodiments, the boron compound cleaning solution may include boric acid (H3BO3). In some embodiments, an amount of boric acid based on a total weight of the boron compound cleaning solution is in a range from 0.5 wt % to 5 wt %. In some embodiments, the preliminary lithium metal oxide particle may be washed with water before the cleaning the preliminary lithium metal oxide particle. In some embodiments, an active material cake may be formed by the washing. In some embodiments, the cleaning the preliminary lithium metal oxide particle may include passing the boron compound cleaning solution through the active material cake without stirring. In some embodiments, a weight ratio of the boron compound cleaning solution relative to a weight of the active material cake may be from 0.3 to 1. In some embodiments, after the cleaning the preliminary lithium metal oxide particle, drying or thermally treating the preliminary lithium metal oxide particle may be further performed to convert the preliminary lithium metal oxide particle into a lithium metal oxide particle that contains a boron doping or a boron coating. According to exemplary embodiments, a cathode active material for a lithium secondary battery includes a lithium metal oxide particle and a boron (B) element present on at least a portion of a surface of the lithium metal oxide particle. A ratio of a B+ peak intensity relative to a sum of peak intensities of Li+, B+ and LiB+ frag