Tri-Modal Positive Electrode Composition for Battery Cycle-Life
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Rechargeable lithium batteries face challenges in maintaining long cycle-life characteristics due to the deterioration of positive electrode active materials, particularly large particles, during charging and discharging.
Innovation Solution
A positive electrode active material composition is designed, comprising a mixture of first, second, and third lithium nickel-cobalt-based composite oxides with varying particle sizes (10 µm to 30 µm, 5 µm to 9 µm, and 0.5 µm to 4 µm) and cobalt content ratios, which are optimized to achieve kinetic balance and reduce particle deterioration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If large particle size positive electrode active material (10 µm to 30 µm) is used to achieve high capacity and energy density, then the energy density is improved, but the particle deterioration accelerates and cycle-life decreases
Solution Approach 1:
The positive electrode active material is segmented into three distinct particle size ranges: large particles (10-30 µm) for high energy density, medium particles (5-9 µm) for structural stability, and small particles (0.5-4 µm) for kinetic performance. This segmentation allows each particle size to fulfill specific functional roles, resolving the contradiction between energy density and cycle-life by distributing the functional demands across different particle sizes rather than relying on a single particle size
Solution Approach 2:
Different regions of the particle size distribution are assigned different functional qualities: large particles provide the energy density foundation, medium particles provide structural stability and crack resistance, and small particles provide rapid lithium ion transport. This local quality assignment allows the electrode material as a whole to achieve both high energy density and long cycle-life by optimizing the specific function of each particle size region
2Manufacturing precision
If uniform particle size distribution is used to simplify manufacturing, then the manufacturing precision is improved, but the kinetic balance is insufficient and performance is suboptimal
Solution Approach 1:
The patent deliberately changes the particle size parameter from a uniform distribution to a tri-modal distribution with three distinct ranges (10-30 µm, 5-9 µm, 0.5-4 µm). This parameter change optimizes both manufacturing (by maintaining clear size boundaries) and performance (by achieving kinetic balance through the size distribution), resolving the contradiction between manufacturing simplicity and performance optimization
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A positive electrode active material includes a first positive electrode active material including a first lithium nickel-cobalt-based composite oxide, in a form of secondary particles composed of a plurality of primary particles, and having an average particle diameter (D50) of the secondary particles of about 10 µm to about 30 µm; a second positive electrode active material including a second lithium nickel-cobalt-based composite oxide, in a form of secondary particles composed of a plurality of primary particles, and having an average particle diameter (D50) of the secondary particles of about 5 µm to about 9 µm; and a third positive electrode active material including a third lithium nickel-cobalt-based composite oxide, in a form of single particles, and having an average particle diameter (D50) of the single particles of about 0.5 µm to about 4 µm; wherein the positive electrode active material satisfies Relationship Equation 1. Relationship Equation 1 Co2>Co1>Co3.