Si Composite Particle Structure for Battery Cycle Stability
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Solution Overview
Problem
Active materials comprising Si face challenges in maintaining cycle characteristics due to volume changes during charging and discharging, leading to potential cracking and gaps in the material structure.
Innovation Solution
An active material composite particle is developed with a center portion comprising a solid electrolyte and Si particles, and a surface layer portion with a higher polymer content and carrier ion conductivity, where the polymer ratio in the surface layer is greater than in the center portion, acting as a cushion to moderate volume changes and maintain the composite particle's shape.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If Si particles are used as active material, then capacity is improved, but volume changes during charging and discharging cause cracking and gaps leading to poor cycle characteristics
Solution Approach 1:
The active material particle is segmented into a center portion containing Si particles and a surface layer portion containing polymer, creating a composite structure that separates the high-capacity Si core from the protective polymer shell, allowing each component to fulfill its specific function
Solution Approach 2:
The surface layer portion with higher polymer content acts as a cushion that absorbs and moderates volume changes before they propagate to the Si particles in the center, preventing cracking and maintaining structural integrity during charging and discharging cycles
2Reliability
If polymer content is increased to moderate volume changes, then cycle characteristics are improved, but carrier ion conductivity may be reduced
Solution Approach 1:
The composite particle exhibits local quality variation with higher polymer content in the surface layer portion for mechanical cushioning and lower polymer content (higher Si content) in the center portion for optimal carrier ion conductivity, allowing each region to be optimized for its specific function
Solution Approach 2:
The invention uses a composite material structure combining polymer and Si particles in specific ratios, where the polymer provides mechanical stability and volume change moderation while the Si particles provide high capacity and carrier ion conductivity, achieving a balance between reliability and performance
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration enhances the cycle characteristics of the active material composite particle by reducing cracking and maintaining the particle's shape, leading to improved performance in secondary batteries.
Implementation Method 1
the surface layer portion comprises a polymer and has a carrier ion-conductivity, where a ratio of polymer in the surface layer portion is higher than a ratio of polymer in the center portion
Implementation Method 2
the center portion comprises a solid electrolyte and a plurality of Si particles
Data Source
AI summary
Disclosed is an active material composite particle comprising Si and having excellent cycle characteristics. The active material composite particle of the present disclosure comprises a center portion and a surface layer portion, wherein the center portion comprises a solid electrolyte and a plurality of Si particles, the surface layer portion comprises a polymer and has a carrier ion-conductivity, and a ratio of polymer in the surface layer portion is higher than a ratio of polymer in the center portion.