High-Nickel Cathode Secondary Particles for Crack-Resistant Density
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Solution Overview
Problem
Conventional high nickel positive electrode active materials face issues with structural degradation due to volume changes during charging and discharging, leading to cracks and reduced conductivity, and particle diameter distribution problems in single particles, which affect battery performance.
Innovation Solution
A high nickel positive electrode active material is developed in the form of secondary particles, where primary particles with a micron-level diameter are aggregated, with specific size and composition ranges, including lithium transition metal composite oxides, to enhance density and conductivity, and a method to recover the layered structure from a rock salt structure formed by high heat treatment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If high nickel content is used to improve capacity characteristics, then energy density is improved, but structural degradation and crack formation occur due to volume changes during charge and discharge
Solution Approach 1:
The positive electrode active material is divided into multiple primary particles (1-5 μm) that aggregate to form secondary particles (10-20 μm). This segmentation allows the high nickel content material to be divided into smaller units that experience reduced volume change stress, preventing crack formation while maintaining high capacity characteristics.
Solution Approach 2:
The patent creates a composite structure where multiple primary particles aggregate to form secondary particles. This composite approach combines the high capacity benefits of high nickel content with the structural stability of aggregated particles, where the aggregate structure accommodates volume changes without cracking.
2Reliability
If secondary particle structure is used to improve density and reduce cracks, then structural stability is improved, but particle diameter distribution widens due to aggregation variability
Solution Approach 1:
The patent specifies precise parameter ranges: primary particles of 1-5 μm and secondary particles of 10-20 μm. By controlling these size parameters and the aggregation process, the patent achieves narrow particle diameter distribution while maintaining the structural stability benefits of secondary particle formation.
3Quantity of substance
If heat treatment temperature is increased to prepare micron-level primary particles, then rolling density is improved, but layered structure degenerates into rock salt structure causing decreased crystallinity
Solution Approach 1:
The patent optimizes the heat treatment temperature parameter to achieve the desired primary particle size (1-5 μm) and rolling density while preventing excessive temperature that would cause layered structure degradation. This precise parameter control maintains crystallinity and structural stability.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution improves energy density, lifetime, and reduces gas generation in lithium secondary batteries by stabilizing the structure and maintaining high nickel content while addressing both secondary and single particle issues.
Implementation Method 1
a secondary particle in which a plurality of primary particles are aggregated
Implementation Method 2
a method to recover the layered structure from a rock salt structure formed by high heat treatment
Data Source
Figure 1(A)~1(B)
Figure 2(A)~2(B)
Figure 3(A)~3(B)
AI summary
The present invention relates to a positive electrode active material, and to a positive electrode active material which may simultaneously solve a problem of a conventional secondary particle and a problem of a single particle, wherein the positive electrode active material may improve energy density through excellent density characteristics as well as cell characteristics, such as improved lifetime and reduced gas generation amount of a lithium secondary battery, by including a particle, such as a conventional single particles, as a primary particle and including a secondary particle that is formed by aggregation of a plurality of primary particles, and a positive electrode and a lithium secondary battery which include the same.