Granulated Cathode Material Particle Size Optimization
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Solution Overview
Problem
Existing lithium-ion secondary battery cathode materials face challenges in increasing active material density without causing peeling between the electrode current collector and the cathode active material, especially when using granulated bodies that do not collapse sufficiently during pressurization.
Innovation Solution
A cathode material composed of granulated bodies with an average particle diameter of 4.50 μm to 6.20 μm and 90% of particles within 1.00 μm to 11.00 μm, allowing for easier collapse and increased active material density during electrode pressurization, along with a carbonaceous film coating to enhance electron conduction and prevent excessive collapse.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the amount of cathode active material is increased by increasing electrode thickness or density, then energy density improves, but peeling between electrode current collector and cathode active material occurs
Solution Approach 1:
The patent changes the particle size parameter of the granulated bodies to a specific range (d10: 2.0-5.0 μm, d50: 4.0-6.0 μm, d90: 6.0-8.0 μm) to optimize both the quantity of active material that can be loaded and the mechanical stability preventing peeling. This parameter optimization allows higher electrode density without causing delamination.
Solution Approach 2:
The patent uses composite granulated bodies formed by agglomerating multiple primary particles (LiFePO4 and carbon-coated particles) into secondary particles with controlled size distribution. This composite structure provides both high loading density and mechanical integrity to prevent peeling between layers.
2Manufacturing precision
If granulated bodies are used to improve electrode coating property, then coating quality improves, but insufficient collapse during pressurization reduces active material density
Solution Approach 1:
The patent optimizes the particle size distribution parameters (d10, d50, d90) of granulated bodies to achieve optimal collapse behavior during pressurization. The specific size range allows sufficient deformation under pressure to increase density while maintaining coating quality, resolving the contradiction between coating precision and material density.
Data Source
AI summary
A cathode material for a lithium-ion secondary battery which includes granulated bodies in which primary particles are aggregated, wherein an average particle diameter of the granulated bodies is 4.50 μm or more and 6.20 μm or less, and particle diameters of 90% or more of the granulated bodies are 1.00 μm or more and 11.00 μm or less, wherein particle diameters of the granulated bodies are evaluated such that 300 granulated bodies are randomly selected from a view of the granulated bodies using a scanning electron microscope, a plurality of diameters of each of the 300 granulated bodies that pass through a central point thereof are evaluated, and a maximum diameter selected from the plurality of diameters is considered as a particle diameter of each of granulated bodies.