Silicon Anode Composite With CNT Coating for Stable Cycling
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Solution Overview
Problem
Silicon-based materials for negative electrodes in electrochemical apparatuses face issues with volume swelling and unstable solid electrolyte interface films, leading to poor performance, and existing carbon nanotube coatings lack sufficient bonding and uniformity.
Innovation Solution
A composite of silicon-based material, carbon nanotubes, and a polymer with specific functional groups chemically bonded to both, enhancing bonding and forming a uniform coating layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If carbon nanotubes are used to coat silicon-based materials to improve conductive performance, then conductive performance is improved, but bonding between silicon-based material and carbon nanotubes is insufficient and coating uniformity is poor
Solution Approach 1:
The patent introduces a polymer containing carboxyl groups as an intermediary substance between the silicon-based material and carbon nanotubes. The carboxyl groups chemically bond to both the silicon-based material surface and the carbon nanotube surface, creating a strong interfacial connection. This mediator resolves the contradiction by providing both strong bonding (solving the strength problem) and uniform distribution (solving the coating uniformity problem) while maintaining conductive performance.
2Stability of the object's composition
If carbon nanotubes are used to coat silicon-based materials, then volume swelling is alleviated, but bonding between silicon-based material and carbon nanotubes is insufficient
Solution Approach 1:
The patent creates a composite structure consisting of silicon-based material particles, polymer binder with carboxyl groups, and carbon nanotubes. This composite material approach allows the system to simultaneously achieve volume stability (from the carbon nanotube network), strong bonding (from the chemically-active polymer interface), and improved conductive performance. The composite structure resolves the contradiction between volume stability and bonding strength.
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
Improves conductive performance, cycling stability, and rate performance of electrochemical apparatuses by strengthening the bonding between silicon-based materials and carbon nanotubes, forming a uniform coating layer.
Implementation Method 1
the polymer contains a first group and a second group, the first group is chemically bonded to the carbon nanotubes, and the second group is chemically bonded to the silicon-based material
Implementation Method 2
carbon nanotubes can be used to coat the silicon-based materials... significantly improve conductive performance of the silicon-based material
Implementation Method 3
during charging and discharging, the silicon-based material experiences a volume swelling of about 300%
Data Source
AI summary
A negative electrode material includes a composite of a silicon-based material (1), a polymer (2), and carbon nanotubes (3), where the polymer (2) contains a first group and a second group, the first group is chemically bonded to the carbon nanotubes (3), and the second group is chemically bonded to the silicon-based material (1). Both the carbon nanotubes (3) and the polymer (2) containing two groups are applied to surfaces of particles of the silicon-based material (1). The two groups of the polymer (2) are chemically bonded to the silicon-based material (1) and the carbon nanotubes (3) respectively, so that bonding force between the silicon-based material (1) and the carbon nanotubes (3) is enhanced and a uniform carbon nanotube (3) coating layer is formed. This can significantly improve conductive performance of the silicon-based material (1), thereby improving cycling performance and rate performance of an electrochemical apparatus.