Silicon-Graphite Anode Material With CNT Network for Capacity Retention
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Solution Overview
Problem
Existing secondary batteries face challenges with high production costs due to the use of large amounts of expensive carbon nanotubes, which increase viscosity and make homogeneous application difficult, leading to current collecting defects and reduced capacity retention.
Innovation Solution
A negative electrode material for secondary batteries incorporating graphite and a silicon element, with carbon nanotubes having an average fiber diameter of 0.5 nm to 6 nm and an average fiber length of 1.2 μm to 8 μm, which suppresses current collecting defects and maintains high capacity retention by forming a line conductive path between active materials and the current collector.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a large amount of carbon nanotube is included in the negative electrode, then current collecting performance is improved, but production cost increases and slurry viscosity increases making homogeneous application difficult
Solution Approach 1:
The patent changes the physical parameters of carbon nanotubes by specifying a particular diameter range (1 nm to 6 nm) and length range (5 μm to 20 μm). This parameter optimization allows the carbon nanotubes to form effective conductive networks at lower concentrations, improving current collecting performance while maintaining slurry processability and avoiding excessive viscosity increases during application.
Solution Approach 2:
The patent creates a composite structure where carbon nanotubes are combined with specific binding agents and conductive materials in optimized ratios. This composite approach enhances the current collecting network efficiency, allowing reduced carbon nanotube content while maintaining or improving electrical conductivity and adhesion properties.
2Reliability
If a large amount of carbon nanotube is included in the negative electrode, then current collecting performance is improved, but production cost increases
Solution Approach 1:
The patent optimizes the dimensional parameters of carbon nanotubes (diameter: 1-6 nm, length: 5-20 μm) to maximize their conductive efficiency per unit mass. These parameter changes enable effective current collecting with reduced carbon nanotube quantities, directly addressing the cost issue while maintaining performance.
Solution Approach 2:
The patent creates an efficient conductive network structure where carbon nanotubes are strategically distributed to form continuous pathways. This network copying approach ensures that fewer carbon nanotubes can achieve the same current collecting effect as larger amounts would provide in less optimized configurations.
3Reliability
If carbon nanotube is used to form conductive path, then capacity retention is improved, but slurry viscosity increases making homogeneous application difficult
Solution Approach 1:
The patent specifies optimized carbon nanotube dimensions (diameter: 1-6 nm, length: 5-20 μm) that balance conductive network formation with slurry processability. These parameter changes ensure sufficient capacity retention through effective electron transport while keeping slurry viscosity at manageable levels for homogeneous application.
Solution Approach 2:
The patent introduces binding agents and dispersants as intermediary substances that facilitate the uniform distribution of carbon nanotubes in the slurry. These intermediaries prevent agglomeration and reduce viscosity increases, enabling homogeneous application while maintaining the capacity retention benefits of carbon nanotube conductive networks.
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 solution results in a secondary battery with low production costs and excellent characteristics, including improved capacity retention and reduced degradation rates, while minimizing the use of carbon nanotubes to avoid increased viscosity and coagulation issues.
Implementation Method 1
the carbon nanotube has an average fiber diameter of 0.5 nm to 6 nm and an average fiber length of 1.2 μm to 8 μm... forming a line conductive path between active materials and the current collector
Data Source
AI summary
A negative electrode material for a secondary battery includes a negative electrode active material and a carbon nanotube, wherein the negative electrode active material includes graphite and a material including a silicon element, and the carbon nanotube has an average fiber diameter of 0.5 nm to 6 nm and an average fiber length of 1.2 μm to 8 μm. A secondary battery includes a negative electrode including the negative electrode material for a secondary battery, a positive electrode, a separator interposed between the positive electrode and the negative electrode, and an electrolyte.