Silicon-Graphite Anode Particle Distribution for Calendering Stability
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Solution Overview
Problem
Silicon anode materials in lithium-ion batteries face issues such as mechanical destruction during the calendering process, leading to reduced volumetric capacity and lifespan due to high expansion and contraction, and low initial efficiency.
Innovation Solution
A silicon composite anode material with controlled particle size distribution is developed, comprising a graphite mixture, a silicon nanolayer coated on the graphite, and a carbon coating layer. This material has a multi-size distribution, with specific particle size ranges and distributions that prevent mechanical destruction under high pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon anode materials are used to achieve high theoretical capacity, then energy density is improved, but mechanical destruction occurs due to high expansion and contraction
Solution Approach 1:
The silicon anode material is divided into particles with controlled size distribution (D10: 1-7 μm, D50: 10-20 μm, D90: 25-35 μm). This segmentation allows smaller particles to experience less stress during expansion/contraction while maintaining high theoretical capacity, resolving the contradiction between energy density and mechanical stability
Solution Approach 2:
The patent changes the particle size parameter distribution to optimize performance. By controlling the D10, D50, and D90 values within specific ranges, the material achieves both high capacity utilization and reduced mechanical stress, preventing particle breakage while maintaining high theoretical capacity
2Volume of stationary object
If silicon particles are made larger to increase volumetric capacity, then tap density is improved, but breakage phenomenon accelerates due to expansion and contraction
Solution Approach 1:
The patent optimizes the particle size distribution parameters (D10: 1-7 μm, D50: 10-20 μm, D90: 25-35 μm) to achieve the optimal balance. This parameter control ensures particles are large enough for high volumetric capacity but small enough to withstand expansion/contraction stresses, preventing accelerated breakage and extending battery lifespan
3Volume of stationary object
If high pressure is applied during calendering process to increase density, then tap density is improved, but mechanical destruction of particles occurs
Solution Approach 1:
The controlled particle size distribution (D10: 1-7 μm, D50: 10-20 μm, D90: 25-35 μm) enables the material to withstand calendering pressure. The size distribution allows smaller particles to fill voids between larger particles, achieving high density while the controlled sizes prevent excessive stress concentration that would cause particle destruction
4Quantity of substance
If initial efficiency of silicon materials is low compared to graphite, then energy density is reduced, but this limits the overall efficiency improvement
Solution Approach 1:
The patent optimizes particle size distribution parameters (D10: 1-7 μm, D50: 10-20 μm, D90: 25-35 μm) to improve initial efficiency. The controlled distribution ensures better electrolyte penetration and lithium ion transport, achieving initial efficiency above 86% while maintaining high energy density, thus resolving the contradiction between efficiency and energy density
Data Source
AI summary
The present invention relates to a silicon composite anode material with controlled particle size distribution, a manufacturing method thereof, and a lithium-ion battery containing the same. More specifically, the present invention relates to a silicon composite anode material with controlled particle size distribution, which exhibits stress relaxation of each particle through distribution of various particle sizes and thus prevents mechanical destruction even under a high-pressure condition during a calendering process, a manufacturing method thereof, and a lithium-ion battery containing the same. The silicon composite anode material comprises a graphite mixture; a silicon nanolayer coated on the graphite mixture; and a carbon coating layer coated on the silicon nanolayer.