Carbon Nanotube Bundle Dispersion for Stable Conductive Battery Films
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Solution Overview
Problem
Existing carbon nanotube dispersions are difficult to stabilize, leading to reduced conductivity and cycle characteristics in batteries, particularly when using silicon as a negative electrode active material.
Innovation Solution
A carbon nanotube dispersion containing bundle-type carbon nanotubes with specific diameter and length ratios, along with a solvent and dispersant, to enhance stability and conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If carbon nanotubes are dispersed in a solvent to form a dispersion, then the conductive material can be applied to electrodes, but the dispersion leads to decreased conductivity and reduced characteristics
Solution Approach 1:
The patent changes the physical parameters of carbon nanotubes by controlling their diameter (3-30 nm) and creating bundle structures with specific aspect ratios. These parameter changes enable the carbon nanotubes to maintain high conductivity even in dispersion form, resolving the contradiction between ease of application and conductivity maintenance.
Solution Approach 2:
The patent creates composite structures by forming bundles of carbon nanotubes with specific dimensional ratios. This composite approach allows the material to maintain structural integrity and conductivity while being dispersible in solvents for easy application to electrodes.
2Reliability
If conventional carbon nanotubes are used in battery electrodes, then conductivity is improved, but cycle characteristics are reduced due to instability
Solution Approach 1:
The patent specifies precise parameter ranges for carbon nanotube diameter (3-30 nm) and bundle aspect ratio (0.2% or more of bundles with length 1-100 μm and diameter 50 nm-5 μm). These controlled parameters ensure both high conductivity and excellent cycle characteristics by optimizing the balance between conductive network formation and structural stability during battery cycling.
3Reliability
If carbon nanotubes with larger diameter are used, then conductivity is improved, but stability and cycle characteristics are reduced
Solution Approach 1:
The patent optimizes the diameter parameter to a specific range (3-30 nm) that balances conductivity and stability. Within this range, the carbon nanotubes maintain sufficient conductive performance while their smaller dimensions enable better dispersion stability and cycle characteristics compared to larger diameter carbon nanotubes.
Solution Approach 2:
The patent creates bundle structures composed of multiple carbon nanotubes with controlled dimensions. This composite structure provides both the conductivity needed for electrode performance and the structural stability required for long-term battery operation and dispersion maintenance.
Data Source
AI summary
A carbon nanotube dispersion contains a solvent and bundle-type carbon nanotubes formed from carbon nanotubes having an average diameter of 3 nm to 30 nm, a proportion of the number of bundle-type carbon nanotubes each in a shape having an outer diameter of 50 nm to 5 μm and a fiber length of 1 μm to 100 μm being 0.2% or more based on the number of carbon nanotubes each having an outer diameter of 10 nm or more in the carbon nanotube dispersion.