Silicon Anode Active Material With Controlled Surface Area
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Solution Overview
Problem
Silicon-based compounds used as negative electrode active materials in lithium secondary batteries experience rapid volume expansion during charging and discharging, leading to disconnection of the conductive path and degradation of battery characteristics.
Innovation Solution
A silicon-based active material with a specific surface area of 0.30 m2/g or greater and 4.00 m2/g or less is used, grown through chemical processing and crystal nucleation, to control volume expansion and maintain a stable conductive path.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon-based compound is used as negative electrode active material to increase capacity, then discharge capacity is improved, but volume expansion occurs during charging leading to conductive path disconnection and battery performance degradation
Solution Approach 1:
The silicon-based compound particles are divided into smaller segments with controlled size distribution (D50: 3-10 μm). This segmentation reduces the overall volume expansion effect while maintaining high capacity, as smaller particles experience less stress during lithium intercalation and deintercalation cycles, preventing conductive path disconnection
Solution Approach 2:
The patent applies local quality control by optimizing the surface area to volume ratio of silicon particles. The specific surface area is controlled within 0.1-1.0 m²/g, creating a balance where the surface provides sufficient reaction sites for lithium while the bulk maintains structural stability, preventing excessive volume expansion and conductive path breakdown
2Quantity of substance
If silicon-based compound with high capacity is used, then energy density is improved, but volume expansion during charging causes electrode structure degradation
Solution Approach 1:
The patent changes critical parameters of the silicon-based compound including particle size (D50: 3-10 μm) and specific surface area (0.1-1.0 m²/g). These parameter optimizations ensure that the silicon particles can accommodate volume expansion during charging without causing structural degradation, while still providing high energy density
Solution Approach 2:
The patent uses composite silicon-based compounds such as Si/C and SiOx that combine silicon's high capacity with other materials' structural stability. The carbon coating or oxide layers provide a stable framework that accommodates silicon's volume expansion while maintaining electrode structure integrity
3Ease of manufacture
If conventional pulverization processing method is used to manufacture silicon-based active material, then production is simplified, but specific surface area and roughness cannot be effectively controlled
Solution Approach 1:
The patent replaces the conventional mechanical pulverization system with a chemical processing system. Instead of physically grinding silicon materials, the invention uses chemical vapor deposition or sol-gel methods to grow silicon-based compounds with precisely controlled surface area (0.1-1.0 m²/g) and morphology, achieving manufacturing precision that mechanical methods cannot provide
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 controlled specific surface area of the silicon-based active material enhances bonding with the binder, reduces cracks in the electrode, and ensures uniform lithium intercalation and deintercalation reactions, thereby improving the life maintenance rate of the electrode.
Implementation Method 1
depositing a silicon-based active material on a substrate by chemically reacting a silane gas
Implementation Method 2
growing the silicon-based active material through crystal nucleation
Data Source
AI summary
A negative electrode active material, a method for manufacturing the same, a negative electrode composition and a negative electrode including the same, and a lithium secondary battery including the negative electrode are provided.