Positive Electrode Active Material for High-Density Fast-Charging Batteries
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Solution Overview
Problem
Existing secondary batteries fail to meet the energy density and rate capability requirements, particularly in electric vehicles, due to limitations in compaction density and lithium-ion migration distance.
Innovation Solution
A positive electrode active material with controlled particle size distribution and particle size of primary particles, specifically LiaNixCoyM1-x-yO2-b, where 0.6≤a≤1.2, 0.6≤x≤1, 0≤y≤0.4, and −0.1≤b≤0.1, and M includes Mn, Al, B, Zr, Sr, Y, Sb, W, Ti, Mg, Nb, and Mo, with primary particles of 100 to 600 nm, and a particle size distribution of (Dv90−Dv10)/Dv50≥1.6, enhancing compaction density and lithium-ion migration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the particle size of positive electrode active material is reduced to increase specific capacity, then the lithium-ion migration distance is shortened and specific capacity is enhanced, but the compaction density of electrode plates decreases
Solution Approach 1:
The positive electrode active material is divided into primary particles (100-600 nm) that aggregate into secondary particles with controlled size distribution. This segmentation allows small primary particles to provide short lithium-ion migration paths and high specific capacity, while the aggregated secondary particles maintain adequate compaction density in the electrode plate.
Solution Approach 2:
Different regions of the particle size distribution are optimized for different functions: the Dv10-Dv30 range (smaller particles) provides high surface area and short ion migration paths for high specific capacity, while the Dv70-Dv90 range (larger particles) provides structural stability and maintains compaction density. This local quality optimization resolves the contradiction between specific capacity and compaction density.
2Manufacturing precision
If the particle size distribution is narrowed to improve manufacturing consistency, then the electrode plate structure is more uniform, but the compaction density and energy density are reduced
Solution Approach 1:
Instead of maintaining a narrow particle size distribution, the invention deliberately broadens the distribution range (Dv10: 3-10 μm, Dv90: 15-30 μm) while controlling the mean particle size (Dv50: 10-20 μm). This parameter change allows smaller particles to fill voids between larger particles, increasing compaction density and energy density while maintaining manufacturing consistency through controlled broad distribution.
3Productivity
If the lithium-ion migration distance is reduced to enhance rate capability, then the specific capacity is improved, but the particle size must be reduced which affects compaction density
Solution Approach 1:
The material is segmented into very small primary particles (100-600 nm) within aggregates. These small primary particles provide short lithium-ion migration paths (enhancing rate capability) while the aggregate structure maintains adequate compaction density. The segmentation occurs at the primary particle level rather than the aggregate level.
Solution Approach 2:
The invention separates the particle size control into two dimensions: primary particle size (100-600 nm) controlling lithium-ion migration distance and rate capability, and aggregate size (Dv10-Dv90 distribution) controlling compaction density. This dimensional separation allows optimization of both rate capability and compaction density independently.
Data Source
AI summary
A positive electrode active material comprises: an aggregate material, the chemical formula of the aggregate material being LiaNixCoyM1-x-yO2-b, wherein 0.6≤a≤1.2, 0.6≤x≤1, 0≤y≤0.4, and −0.1≤b≤0.1, and M comprises one or more of Mn, Al, B, Zr, Sr, Y, Sb, W, Ti, Mg, Nb, and Mo; primary particles of the aggregate material have a particles size of 100-600 nm, and the particle size distribution of the aggregate material satisfies (Dv90-Dv10)/Dv50≥1.6.