Core-Shell Cathode Precursor for High-Ni Stability and Low Resistance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing high-Ni NCM-based positive electrode active materials face challenges with reduced structural and thermal stability, poor resistance characteristics, and non-uniform particle sizes, which affect the performance and longevity of lithium secondary batteries.
Innovation Solution
A positive electrode active material precursor with a composite transition metal hydroxide structure, featuring a core-shell configuration of primary particles, where the ratio of the second primary particles' cross-sectional area to the first primary particles' area ranges from 3.00 to 10.0, ensuring uniform particle size and sphericity, and a method of preparation using a reaction apparatus with a continuous grinder and controlled pH adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If high-nickel NCM-based positive electrode active material is used to increase capacity, then capacity characteristics are improved, but structural stability and thermal stability are reduced
Solution Approach 1:
The patent applies local quality by creating a core-shell structure where the shell portion has different compositional characteristics from the core portion. Specifically, the shell contains a higher proportion of stabilizing elements (Co, Mn, Al) compared to the core, which is rich in Ni for high capacity. This local compositional variation allows the high-Ni core to provide capacity while the stabilizing shell maintains structural integrity and thermal stability.
Solution Approach 2:
The patent employs composite materials by combining multiple transition metal elements (Ni, Co, Mn, Al) in a core-shell structured composite. The core-shell composite structure integrates the high-capacity Ni-rich region with the stability-providing Co/Mn/Al-rich shell, achieving a synergistic effect that resolves the contradiction between capacity and stability.
2Quantity of substance
If high-nickel NCM-based positive electrode active material is used to increase capacity, then capacity characteristics are improved, but thermal stability is reduced
Solution Approach 1:
The shell portion is designed with local quality that specifically addresses thermal stability by incorporating a higher concentration of thermally stable elements (Co, Mn, Al) on the outer surface. This creates a protective layer that is directly exposed to thermal environments and provides the necessary thermal stability while the inner core maintains high capacity through Ni richness.
Solution Approach 2:
The stabilizing shell acts as a beforehand cushioning layer that protects the high-Ni core from thermal degradation before thermal runaway can occur. The shell portion serves as a protective barrier that mitigates the harmful thermal effects on the capacity-providing core material.
3Duration of action of stationary object
If small particle size positive electrode active material is used to improve cycle characteristics, then cycle characteristics are improved, but resistance characteristics are poor
Solution Approach 1:
The core-shell structure applies local quality by optimizing different regions for different functions: the core is designed for efficient Li-ion diffusion (supporting good cycle characteristics in small particles), while the shell provides enhanced surface properties that reduce resistance. The shell's compositional gradient creates favorable surface conditions for charge transfer without compromising the bulk diffusion pathways.
4Manufacturing precision
If uniform particle size and sphericity are achieved through core-shell structure, then manufacturing precision is improved, but device complexity is increased
Solution Approach 1:
The patent applies segmentation by dividing the positive electrode active material into core and shell portions with distinct compositional characteristics. This segmentation is achieved through controlled co-precipitation where different metal hydroxides form in distinct regions, creating the core-shell structure that ensures uniform particle size and sphericity while managing the complexity through a systematic formation process.
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 precursor enables the formation of high-density positive electrode active materials with improved lithium diffusion, leading to enhanced capacity and life characteristics, and reduces resistance, resulting in better battery performance.
Implementation Method 1
a positive electrode active material precursor including a composite transition metal hydroxide which includes a core portion including first primary particles; and a shell portion formed on the core portion and including second primary particles
Data Source
Figure 1
Figure 2(A)~2(B)
Figure 3(A)~3(E)
AI summary
The present invention relates to a positive electrode active material precursor with a novel structure and a method of preparing the same, wherein the present invention relates to a positive electrode active material precursor including a composite transition metal hydroxide which includes a core portion including first primary particles; and a shell portion formed on the core portion and including second primary particles, wherein, in a cross section of the positive electrode active material precursor, a ratio (A2/A1) of an average cross-sectional area (A2) of the second primary particles to an average cross-sectional area (A1) of the first primary particles is in a range of 3.00 to 10.0, and a method of preparing the same.