KR-20260063726-A - POLYCRYSTALLINE CATHODE ACTIVE MATERIAL AND LITHIUM SECONDARY BATTERY CONTAINING THE SAME

Abstract

The present invention relates to a novel polycrystalline cathode active material, and more specifically, provides a novel polycrystalline cathode active material that improves lifespan characteristics while securing excellent output and capacity characteristics by determining the optimal size and number of primary particles and the size of secondary particles using the peak intensity of the H2 phase and H3 phase.

Inventors

• 남유진
• 선영회
• 김선화
• 허승우
• 박성윤
• 이재민
• 권오현
• 이재균
• 곽환욱
• 조민수

Assignees

• 주식회사 에코프로비엠

Dates

Publication Date

20260507

Application Date

20241031

Claims (11)

1. Primary particles containing nickel and having an average particle size (D50) of 500 nm to 5 μm; and It includes secondary particles formed by the aggregation of the primary particles above, A polycrystalline cathode active material in which a portion of the primary particle is exposed on the outer surface of the secondary particle.
2. In claim 1, Polycrystalline cathode active material, wherein the average particle size (D50) of the above primary and secondary particles is determined by the H2 intensity ratio calculated by the following Equation 1: [Equation 1] (In Equation 1 above, H2 intensity and H3 intensity are the peak intensities of the H2 phase and H3 phase obtained through X-ray diffraction (XRD) analysis.)
3. In claim 1, A polycrystalline cathode active material in which the number of primary particles forming the secondary particles is determined by the H2 intensity ratio calculated by the following Equation 1: [Equation 1] (In Equation 1 above, H2 intensity and H3 intensity are the peak intensities of the H2 phase and H3 phase obtained through X-ray diffraction (XRD) analysis.)
4. In claim 2, When the nickel content of the above primary particles is 50 mol% or more to less than 80 mol%, A polycrystalline cathode active material in which the average particle size (D50) of the primary and secondary particles is measured when the H2 intensity ratio is 5% or more to 16% or less.
5. In claim 3, When the nickel content of the above primary particles is 50 mol% or more to less than 80 mol%, A polycrystalline cathode active material in which the number of primary particles forming the secondary particles is measured when the H2 intensity ratio is 5% or more to 16% or less.
6. In claim 2, When the nickel content of the above primary particles is 80 mol% or more, A polycrystalline cathode active material in which the average particle size (D50) of the primary and secondary particles is measured when the H2 intensity ratio is 10% or more to 25% or less.
7. In claim 3, When the nickel content of the above primary particles is 80 mol% or more, A polycrystalline cathode active material in which the number of primary particles forming the secondary particles is measured when the H2 intensity ratio is 10% or more to 25% or less.
8. In claim 1, A polycrystalline cathode active material in which the average particle size (D50) of the secondary particles is 1.5 to 5.0 times the average particle size (D50) of the primary particles.
9. In claim 1, The above-mentioned secondary particles are formed by the aggregation of 2 to 5 primary particles, in a polycrystalline cathode active material
10. A positive electrode slurry composition comprising a polycrystalline positive electrode active material, a conductive material, and a binder of any one of claims 1 to 9.
11. A lithium secondary battery comprising a positive electrode formed by coating the positive electrode slurry composition of claim 10 onto a current collector.

Description

Polycrystalline cathode active material and lithium secondary battery containing the same The present invention relates to a polycrystalline cathode active material and a lithium secondary battery containing the same. More specifically, the invention relates to a novel polycrystalline cathode active material exhibiting lifespan, capacity, and output characteristics that differ from those of conventional polycrystalline cathode active materials, and a lithium secondary battery containing the same. Lithium-ion batteries are batteries that store and release energy by moving lithium ions between electrodes. Due to their rechargeable and discharge capabilities, they are widely used in various fields, including electronic devices, electric vehicles, and energy storage systems. In particular, lithium ions play a crucial role in the development of high-efficiency batteries because they are lighter and have a higher energy density compared to other metal ions. One of the key factors determining the performance of a lithium-ion battery is the cathode active material, which maintains stability during the insertion and extraction of lithium ions and directly affects the battery's capacity and lifespan. The energy density, output, lifespan, and stability of a battery vary significantly depending on the type of cathode active material. Cathode active materials are generally composed of lithium metal oxides, and representative examples include lithium cobalt oxide (LCO), lithium manganese oxide (LMO), lithium nickel cobalt manganese oxide (NCM), and lithium nickel cobalt aluminum oxide (NCA). Recently, mid-nickel and high-nickel cathode active materials have been attracting attention to meet the high energy density and capacity requirements of electric vehicles. Since the energy density and capacity of nickel cathode materials increase as the nickel ratio rises, they are gaining popularity in markets demanding higher-performance batteries. Representative examples include NCM (nickel, cobalt, manganese) and NCA (nickel, cobalt, aluminum) materials with high nickel ratios, which contribute to extending the driving range of electric vehicles and improving battery energy efficiency. Cathode active materials can be divided into polycrystalline and single-crystal types depending on their crystal structure. Polycrystalline cathode active materials have a structure in which numerous small crystal particles aggregate to form a single particle. Polycrystalline structures offer relatively easy and low-cost manufacturing processes, as well as excellent performance at specific charge and discharge rates. However, polycrystalline particles are prone to inter-particle cracking during charging and discharging, and gas generation issues make them disadvantageous in terms of long-term lifespan. In particular, high-nickel polycrystalline cathode active materials face a significant need to address expansion and stability issues caused by gas generation. Single-crystal cathode active materials have a particle structure composed of a single crystal. The single-crystal structure has the advantage of a long lifespan due to high stability and minimal cracking between particles during charging and discharging. However, single crystals have disadvantages, such as being difficult and costly to manufacture, and exhibiting lower output characteristics compared to polycrystalline materials. Additionally, for materials with the same nickel composition, the capacity tends to be lower compared to polycrystalline materials, which can lead to performance degradation. Accordingly, in order to improve the performance of lithium-ion batteries, it is necessary to develop a new type of cathode active material that resolves the problems arising from nickel-based cathode active materials and compensates for the shortcomings of polycrystalline and single-crystal cathode active materials. FIG. 1 is a schematic diagram of a polycrystalline cathode active material according to one embodiment of the present invention. FIG. 2 is a scanning electron microscope (SEM) image of the anode plates of Examples 1 to 3 and Comparative Examples 1 to 5. Figure 3 is a graph showing the correlation between the lifespan and H2 strength ratio of Examples 1 to 3 and Comparative Examples 1 to 5. Expressions such as "comprising" as used in this specification should be understood as open-ended terms implying the possibility of including other technical features. As used herein, "as an example," "as an embodiment," and "preferably" refer to embodiments of the invention that may provide certain advantages under certain conditions, and are not intended to exclude other embodiments from the scope of the invention. FIG. 1 is a schematic diagram of the shape of a polycrystalline positive electrode active material (1) according to one embodiment of the present invention. Referring to FIG. 1, a polycrystalline positive electrode active material (1) according to one embodiment of the present invent