High-Nickel Cathode Active Material with Cobalt-Recovered Layered Structure
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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 primary particles of specific size ranges and composition, including a lithium transition metal composite oxide with high nickel content, is developed, featuring a method to recover the rock salt structure into a layered structure through cobalt coating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If heat treatment temperature is increased to manufacture secondary particles with micron-level primary particles, then rolling density and specific surface area are improved, but 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 (800-900°C for submicron, 900-1000°C for micron-level particles) and particle size parameters (primary particles 0.5-1 μm for submicron, 1-5 μm for micron-level) to achieve the desired balance between particle morphology and structural stability. This resolves the contradiction by finding optimal parameter windows that satisfy both requirements.
Solution Approach 2:
The patent applies local quality by creating secondary particles with specific internal structures where primary particles are aggregated in controlled configurations. The secondary particles have average diameters of 5-20 μm with controlled primary particle distributions, providing local structural optimization that maintains layered structure while achieving good rolling density and surface area characteristics.
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 are exacerbated
Solution Approach 1:
The patent applies composite materials by combining nickel-based lithium transition metal oxide with other transition metals (coefficient a: 0.6-0.95 for Ni, b: 0.05-0.30 for Co, c: 0.05-0.30 for Mn) to create a composite structure that maintains high nickel content (60-95 mol%) while improving structural stability. The composite composition prevents excessive rock salt structure formation while preserving high capacity characteristics.
Solution Approach 2:
The patent applies parameter changes by precisely controlling nickel content within specific ranges (60-95 mol%) and adjusting heat treatment temperatures (900-1000°C for micron-level particles) to achieve the optimal balance between high capacity and structural stability. This resolves the contradiction by finding the parameter window where high nickel content does not lead to excessive degradation.
3Productivity
If secondary particle structure is used to improve rolling density and specific surface area, then cell characteristics are improved, but particle diameter distribution becomes non-uniform leading to cracks and reduced conductivity
Solution Approach 1:
The patent applies parameter changes by controlling secondary particle average diameter within 5-20 μm and primary particle diameter within 1-5 μm, with specific heat treatment temperatures (900-1000°C) to achieve uniform particle size distribution. This resolves the contradiction by optimizing parameters that simultaneously improve rolling density and maintain particle uniformity.
Solution Approach 2:
The patent applies local quality by creating a hierarchical structure where uniform primary particles (1-5 μm) are aggregated into secondary particles (5-20 μm) with controlled morphology. This local structural control ensures uniform particle diameter distribution while maintaining good rolling density and specific surface area characteristics.
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 size and structure, suitable for high-nickel positive electrodes.
Implementation Method 1
a method to recover the rock salt structure into a layered structure through cobalt coating
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
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.