High-Nickel Cathode Aggregates for Density Without Crystallinity Loss
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Solution Overview
Problem
High-nickel positive electrode active materials face issues with structural degradation and non-uniform particle diameter distribution, leading to reduced conductivity and lifespan, while conventional secondary particles suffer from decreased crystallinity at high heat treatment temperatures.
Innovation Solution
A positive electrode active material comprising secondary particles with primary particles of 1.5 µm to 5.0 µm, high nickel content, and single crystallinity, manufactured through a process that recovers the rock salt structure to a layered structure, enhancing density and crystallinity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If heat treatment temperature is increased to manufacture secondary particles with micron-level primary particles, then rolling density is improved and cracks are minimized, but the layered structure degenerates into rock salt structure causing decreased crystallinity and performance
Solution Approach 1:
The patent applies parameter changes by precisely controlling heat treatment temperature ranges and timing to achieve the desired particle morphology while preserving crystalline structure. Specific temperature parameters are optimized to prevent rock salt structure formation during the heat treatment process.
2Quantity of substance
If nickel content is increased to achieve high-capacity characteristics, then capacity characteristics are improved, but structural degradation and rock salt structure formation become more severe
Solution Approach 1:
The patent employs composite materials by combining high-nickel content with other transition metals in specific ratios to create a composite oxide structure. This composite approach maintains high capacity characteristics while the other metal components help stabilize the structure and prevent excessive rock salt structure formation.
3Strength
If primary particle size is increased to improve rolling density, then cracks caused by rolling are minimized, but particle diameter distribution becomes non-uniform and specific surface area decreases
Solution Approach 1:
The patent applies segmentation by forming secondary particles that are aggregates of multiple primary particles. This segmentation allows the primary particles to maintain uniform size and shape while the secondary particle structure provides the necessary rolling density and crack resistance.
4Ease of manufacture
If heat treatment temperature is increased to form secondary particles, then particle aggregation is improved, but cell resistance characteristics worsen due to reduced specific surface area
Solution Approach 1:
The patent applies parameter changes by optimizing heat treatment temperature and duration to achieve appropriate particle aggregation while maintaining sufficient specific surface area. The temperature and time parameters are carefully controlled to balance aggregation benefits with surface area preservation.
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
Improves cell characteristics such as lifespan, reduces gas generation, and increases energy density by stabilizing the structure and maintaining high nickel content without compromising crystallinity.
Implementation Method 1
heat treatment needs to be performed at a higher temperature than that of a secondary particle having a primary particle size of submicron level less than 1 μm. However, as the heat treatment temperature increases, the layered structure of the lithium transition metal composite oxide degenerates into a rock salt structure
Implementation Method 2
heat treatment needs to be performed at a higher temperature than that of a secondary particle having a primary particle size of submicron level less than 1 μm
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 capable of simultaneously solving the problems of conventional secondary particles and single particles, and a positive electrode and a lithium secondary battery comprising the same, wherein the positive electrode active material includes a secondary particle containing the same particles as the conventional single particles as primary particles and formed by aggregating a plurality of primary particles, whereby it is possible to improve not only cell characteristics such as improved lifespan of the lithium secondary battery and reduced gas generation but also energy density due to excellent density characteristics.