Si-Resin Composite Particle Structure for Battery Cycle Stability
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Solution Overview
Problem
Conventional active materials comprising Si face challenges in maintaining cycle characteristics under both high and low constraint pressures due to volume changes during charging, leading to potential cracks and gaps in secondary batteries.
Innovation Solution
The development of an active material composite particle comprising Si and a resin, where the area ratio of resin is higher in the surface layer than in the center, with higher porosity in the center portion, effectively moderating volume changes and maintaining the composite particle's shape, thereby enhancing cycle characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If Si is used as active material to increase capacity, then battery capacity is improved, but volume expansion during charging causes cracks and gaps leading to poor cycle characteristics
Solution Approach 1:
The patent applies local quality by creating a composite particle structure where Si particles are concentrated in the center portion and resin is concentrated in the surface layer portion. This spatial differentiation allows the center to accommodate volume expansion while the surface provides structural stability, resolving the contradiction between high capacity (Si content) and cycle characteristics (structural integrity).
Solution Approach 2:
The patent uses composite materials by combining Si particles with resin in a specific configuration. The composite structure leverages the high capacity of Si while the resin provides mechanical stability, preventing cracks and gaps during charging cycles. This directly addresses the contradiction by integrating two materials with complementary properties in a functional arrangement.
2Reliability
If resin content is increased to maintain particle shape, then cycle characteristics are improved, but active material content decreases reducing capacity
Solution Approach 1:
By concentrating resin specifically in the surface layer portion rather than uniformly distributing it, the patent achieves structural stability with minimal resin content. This localized approach allows the center portion to be rich in Si active material, maintaining high capacity while the surface resin layer provides the necessary shape retention and crack prevention.
Solution Approach 2:
The patent transitions from uniform composition to layered composition, adding a dimensional aspect to the material structure. The surface layer portion and center portion are differentiated in composition, allowing simultaneous optimization of both resin function (shape maintenance) and Si content (capacity) without compromise.
3Quantity of substance
If Si particles are densely packed to increase capacity, then battery capacity is improved, but volume expansion causes internal stress and cracks
Solution Approach 1:
The patent applies local quality by creating a heterogeneous structure where Si particles are densely packed in the center portion for high capacity, while the surface layer portion contains resin that provides stress relief. This spatial differentiation allows internal stress from Si expansion to be managed locally by the resin layer, preventing crack propagation throughout the particle.
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
The described composite particle structure ensures improved cycle characteristics under both high and low constraint pressures by moderating volume changes and reducing the likelihood of cracks and gaps, leading to enhanced performance in secondary batteries.
Implementation Method 1
flash-drying the slurry droplets in a heating gas to obtain an active material composite comprising the Si particles and the resin
Data Source
AI summary
Disclosed is an active material composite particle comprising Si and having cycle characteristics under low constraint. The active material composite particle of the present disclosure comprises Si and a resin, wherein an area ratio of the resin in a surface layer portion of the composite particle is higher than an area ratio of the resin in a center portion of the composite particle when a cross-section of the composite particle is observed.