CNT Electrode Composition for Uniform Conductive Network Formation
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Solution Overview
Problem
Existing secondary batteries face limitations in achieving uniform distribution and high electrical conductivity of conductive agents, leading to poor electrode adhesion and reduced battery efficiency due to issues with dispersibility and surface reactions.
Innovation Solution
An electrode active material layer is developed using a carbon nanotube structure with 2 to 5,000 single-walled carbon nanotube units bonded together, dispersed with polyvinylidene fluoride, to form a network structure that enhances conductivity and adhesion, improving the distribution and performance of the conductive agent within the electrode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If line-type conductive agents (carbon nanotubes or carbon nanofibers) are used to improve electrical conductivity, then electrical conductivity is enhanced, but dispersibility in slurry is low due to bundle type or entangled type growth, resulting in poor coatability and non-uniform distribution in the electrode active material layer
Solution Approach 1:
The conductive agent is segmented into specific length ranges (1-10 μm for single-walled carbon nanotubes, 5-20 μm for multi-walled carbon nanotubes, 10-30 μm for carbon nanofibers) to balance conductivity and dispersibility. This segmentation prevents excessive bundling while maintaining sufficient length for effective conductive pathways, resolving the contradiction between electrical conductivity and uniform distribution
Solution Approach 2:
The invention changes physical parameters of the conductive agents including length, diameter, and aspect ratio to optimize both conductivity and dispersibility. By controlling these parameters within specific ranges and using appropriate aspect ratios (length/diameter), the patent achieves uniform distribution while maintaining high electrical conductivity
2Stability of the object's composition
If functional groups are introduced to improve dispersibility of line-type conductive agents, then dispersibility is enhanced, but surface side reactions occur due to the presence of functional groups, deteriorating electrochemical properties
Solution Approach 1:
The invention changes the chemical composition parameters by selecting conductive agents with minimal or no functional groups. By using high-purity carbon nanotubes and carbon nanofibers without excessive functionalization, the patent achieves good dispersibility through physical means (sonication, solvent selection) while avoiding surface side reactions that would deteriorate electrochemical properties
3Reliability
If plane-type conductive agent (graphene) is used to improve electrical conductivity, then electrical conductivity is enhanced, but it is difficult to prepare thin single layer graphene, and thick graphene reduces battery efficiency
Solution Approach 1:
The invention segments the conductive function across multiple thin layers rather than using thick single-layer graphene. By employing line-type conductive agents with controlled lengths, the patent achieves effective conductivity without the thickness issues that reduce battery efficiency, while maintaining good electrolyte penetration and ion transport
4Reliability
If plane-type conductive agent (graphene) is used to improve electrical conductivity, then electrical conductivity is enhanced, but electrolyte solution mobility is limited in the battery due to wide planar contact
Solution Approach 1:
The invention uses line-type conductive agents (carbon nanotubes and carbon nanofibers) with curved/cylindrical geometries instead of planar graphene sheets. This curvature allows electrolyte to flow more freely around the conductive agents while maintaining electrical conductivity through the nanotube structures themselves, thus improving electrolyte mobility without sacrificing conductivity
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 approach results in improved electrical conductivity, reduced electrode resistance, and enhanced electrochemical performance and life characteristics of the battery by forming a robust conductive path and maintaining the integrity of the carbon nanotube structure during battery operation.
Implementation Method 1
a carbon nanotube structure in which 2 to 5,000 single-walled carbon nanotube units are bonded to each other
Implementation Method 2
electrical conductivity is excellent, but, since dispersibility in the slurry is low due to the nature of the material itself growing in a bundle type or entangled type
Data Source
AI summary
An electrode includes an electrode active material, wherein the electrode active material layer includes an electrode active material, polyvinylidene fluoride, and a conductive agent, wherein the conductive agent includes a carbon nanotube structure in which 2 to 5,000 single-walled carbon nanotube units are bonded to each other, and the carbon nanotube structure is included in an amount of 0.01 wt % to 0.5 wt % in the electrode active material layer. A secondary battery including the same, and a method of preparing the electrode are also provided.