High-Nickel Cathode Material With Structural Recovery and Particle Aggregation
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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 aggregated disk-type primary particles, each having a specific size and crystal structure, including a high nickel content, is developed to enhance density and energy density, with a method to recover the rock salt structure to a layered structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If heat treatment is performed at higher temperature 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 balance between rolling density improvement and crystallinity preservation. Specific temperature parameters are optimized to prevent rock salt structure formation while still achieving adequate particle densification.
2Use of energy by moving object
If high nickel content is used to achieve excellent capacity characteristics, then energy density is improved, but the layered structure is more vulnerable to degeneration into rock salt structure at high heat treatment temperature
Solution Approach 1:
The patent modifies heat treatment parameters specifically tailored for high-nickel compositions, using lower temperatures and optimized holding times to prevent nickel-induced rock salt structure formation while maintaining capacity characteristics.
Solution Approach 2:
The patent employs composite material strategies by combining nickel with other transition metals in specific ratios and incorporating coating materials that stabilize the layered structure during heat treatment, preventing nickel-driven degradation.
3Reliability
If single particle structure is used to minimize cracks, then structural integrity is improved, but particle diameter distribution becomes non-uniform and specific surface area decreases leading to increased cell resistance
Solution Approach 1:
The patent divides the particle structure into secondary particles composed of multiple primary particles, achieving uniform overall size distribution while maintaining internal structural integrity and adequate surface area through the segmented architecture.
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 cell characteristics by enhancing lifespan, reducing gas generation, and increasing energy density through optimized particle aggregation and structural recovery.
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
Implementation Method 2
a change in a lattice structure constant, that is, a change in volume within a unit lattice, occurs relatively large. This volume change causes cracks in the positive electrode active material
Implementation Method 3
the layered structure of the lithium transition metal composite oxide degenerates into a rock salt structure, causing a decrease in crystallinity
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 cathode active material and, to a cathode active material, and a cathode and a lithium secondary battery, each including same, in which the cathode active material can solve conventional problems of secondary particles and problems of single-particles at the same time, and comprises, as primary particles, particles like conventional single-particles, and secondary particles formed by aggregation of a plurality of the primary particles, and thus not only provides excellent cell properties of lithium secondary batteries, such as improved lifespan and reduced gas generation, but also provides excellent density properties to improve energy density.