Nickel-Based Cathode Particles Balancing Output and Slurry Stability
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Solution Overview
Problem
Lithium nickel-based oxides used as positive electrode active materials in lithium secondary batteries face challenges with particle cracking during charging and discharging due to limited lithium ion passage and high resistance, necessitating small particle sizes that compromise phase stability and output performance.
Innovation Solution
A positive electrode active material composed of single particles or quasi-single particles with optimized particle size distribution, characterized by specific D90 and NSF values, enhances phase stability and electrochemical properties, reducing particle breakage and resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the average particle diameter is reduced to 5.0 μm or less to minimize resistance increase and maintain output, then output performance is improved, but a large amount of fine powder is generated during pulverization, causing rapid deterioration of slurry phase stability
Solution Approach 1:
The patent changes the particle size distribution parameters by controlling D90 within 7.0-12.0 μm and NSF within 0.15-0.30, rather than simply reducing average particle diameter. This parameter optimization allows achieving low resistance while minimizing fine powder generation and maintaining slurry phase stability during electrode manufacturing.
2Manufacturing precision
If strong pulverization is applied to achieve small particle diameter, then resistance is minimized, but particle breakage increases and fine powder generation deteriorates slurry phase stability
Solution Approach 1:
The patent optimizes particle size distribution parameters (D90: 7.0-12.0 μm, NSF: 0.15-0.30) to achieve appropriate particle diameter control without requiring excessive pulverization strength, thereby minimizing fine powder generation and maintaining slurry phase stability.
3Reliability
If single particles are used instead of secondary particles to reduce cracks, then structural stability is improved, but interface area for lithium ion movement decreases and diffusion path increases, raising resistance and reducing output
Solution Approach 1:
The patent optimizes particle size distribution parameters (D90: 7.0-12.0 μm, NSF: 0.15-0.30) for single particles to achieve the right balance between structural stability and lithium ion transport efficiency, maintaining low resistance while ensuring crack resistance.
Data Source
AI summary
A positive electrode active material includes a lithium nickel-based oxide which is a single particle composed of one single nodule, a quasi-single particle which is a composite of at most 30 nodules, or a combination thereof. The positive electrode active material has a D90 ranging from 8.0 μm to 11.5 μm, and a negative skewness factor (NSF) represented by Equation 1 below ranges from 0.20 to 0.35:NSF=(D50 - D10)/Imax[Equation 1]D50 is a particle diameter at a cumulative volume of 50% in a volume cumulative particle size distribution graph of the positive electrode active material. D10 is a particle diameter at a cumulative volume of 10% in a volume cumulative particle size distribution graph of the positive electrode active material. Imax is a maximum volume fraction in the volume cumulative particle size distribution graph of the positive electrode active material.