SiOx-SiFe Alloy Negative Material for Lithium Batteries
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Solution Overview
Problem
Rechargeable lithium batteries face challenges in achieving high capacity and cycle-life efficiency due to limitations in existing negative active materials, which often result in poor performance and rapid degradation during charge and discharge cycles.
Innovation Solution
A negative active material comprising silicon-based material with SiOx particles and a Si—Fe-containing alloy on its surface, prepared through mechanical alloying, which enhances mechanical strength, electrical conductivity, and prevents volume expansion, thereby improving cycle-life and efficiency characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon-based material is used as negative active material, then capacity is improved, but cycle-life and efficiency characteristics deteriorate due to volume expansion and crack formation
Solution Approach 1:
The patent uses a composite structure consisting of SiOx particles coated with Si-Fe-containing alloy. The SiOx core provides high capacity through lithium insertion/extraction, while the Si-Fe alloy coating layer prevents volume expansion and crack formation during charge-discharge cycles. This composite material approach resolves the contradiction by combining materials with complementary properties.
Solution Approach 2:
The patent changes the physical and chemical parameters of the silicon-based material by controlling the particle size of SiOx (0.1-10 μm) and the composition of the Si-Fe-containing alloy coating. By optimizing these parameters, the material achieves both high capacity and excellent cycle-life characteristics.
2Quantity of substance
If silicon-based material is used as negative active material, then capacity is improved, but efficiency characteristics deteriorate due to electrolyte decomposition
Solution Approach 1:
The Si-Fe-containing alloy coating acts as an intermediary layer between the SiOx particles and the electrolyte. This coating layer prevents direct contact between the electrolyte and SiOx surface, thereby minimizing electrolyte decomposition and improving charge-discharge efficiency while maintaining high capacity.
3Reliability
If conventional carbon-based materials are used as negative active material, then cycle-life is improved, but capacity is limited
Solution Approach 1:
The patent creates a composite material that combines the advantages of silicon-based materials (high capacity) with the stability of protected structures (excellent cycle-life). The SiOx-Si-Fe alloy composite achieves capacity exceeding conventional carbon materials while maintaining superior cycle-life through the protective coating mechanism.
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 silicon-based material with a Si—Fe-containing alloy on its surface provides high capacity, excellent cycle-life, and efficiency characteristics by minimizing electrolyte decomposition and crack formation, maintaining performance even after repeated charge and discharge cycles.
Implementation Method 1
A negative active material comprising silicon-based material with SiOx particles and a Si—Fe-containing alloy on its surface, prepared through mechanical alloying
Implementation Method 2
a negative electrode including a negative active material capable of intercalating/deintercalating lithium ions
Data Source
AI summary
Disclosed are a negative active material for a rechargeable lithium battery including a silicon-based material including SiOx particles, where 0<x<2, and a Si—Fe—containing alloy positioned on the surface of the SiOx(0<x<2) particles, a method of preparing the same, and a negative electrode and a rechargeable lithium battery including the same.