Silicon Anode Core-Shell Structure for Volume Expansion Control
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Solution Overview
Problem
Silicon-based anode materials in lithium-ion batteries face issues with unstable electrochemical properties and structural destruction due to rapid volume expansion during charging and discharging, limiting their long-term life and energy density.
Innovation Solution
An anode active material is developed with a core of silicon particles surrounded by a shell layer containing silicon carbide particles and a carbon-based material, which suppresses volume expansion and enhances mechanical strength, ensuring stable charge/discharge behavior and improved life characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If silicon-based anode materials are used to achieve high theoretical capacity, then energy density is improved, but structural stability deteriorates due to volume expansion and SEI layer formation
Solution Approach 1:
The patent applies the nested doll principle by placing silicon particles inside a protective shell layer structure. The core silicon particles provide high capacity while being nested within the stabilizing shell that prevents structural degradation during volume expansion cycles.
Solution Approach 2:
The patent uses composite materials by combining silicon-based core particles with a shell layer containing metal carbide particles and carbon-based material. This composite structure integrates the high capacity of silicon with the structural stability of the shell materials to resolve the contradiction between energy density and reliability.
2Reliability
If surface coating or compounding with carbon materials is performed to improve life characteristics, then durability is improved, but manufacturing complexity increases and cost increases
Solution Approach 1:
The patent merges multiple protective functions into a single integrated shell layer structure that combines metal carbide particles and carbon-based material. This unified approach provides both mechanical strength and electrochemical stability while simplifying the manufacturing process compared to multiple separate coating steps.
Solution Approach 2:
The patent applies local quality by creating a shell layer with specific metal carbide particles distributed at controlled number density (50-100 particles/μm²) within the carbon-based matrix. This localized optimization provides enhanced mechanical strength exactly where needed to suppress volume expansion, while maintaining overall structural integrity.
3Strength
If the number density of metal carbide particles in the shell layer is increased to suppress volume expansion, then mechanical strength is improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent applies parameter changes by specifying a controlled number density range (50-100 metal carbide particles per μm²) in the shell layer. This quantitative parameter optimization balances mechanical strength enhancement with manufacturability, providing sufficient reinforcement to suppress volume expansion while remaining achievable through conventional manufacturing processes.
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 core-shell structure effectively prevents structural destruction and improves the anode's life and output characteristics by stabilizing electrochemical reactions and mechanical strength, leading to enhanced energy density and prolonged battery life.
Implementation Method 1
a shell layer formed on an outer portion of the core. The shell layer includes metal carbide particles and a carbon-based material... suppressing the volume expansion of the silicon-based anode active material
Implementation Method 2
step S4 of performing a heat treatment at 1100° C. to 1400° C. for 3 to 8 hours
Data Source
AI summary
Provided are an anode active material including a core including metal particles, and a shell layer formed on an outer portion of the core, in which the shell layer includes metal carbide particles and a carbon-based material, and a number density (number/μm2) of the metal carbide particles in the shell layer is 50 or more to 100 or less, a method of preparing the same, and a lithium secondary battery including the same.