CNT Electrode Composition for Durable Lithium Battery Conductivity
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Solution Overview
Problem
Lithium secondary batteries face challenges in maintaining conductivity and durability due to the damage of single-walled carbon nanotubes during charge and discharge cycles, leading to increased resistance and reduced life characteristics.
Innovation Solution
Incorporating multi-walled carbon nanotube units and carbon nanotube structures where 2 to 5,000 single-walled carbon nanotube units are bonded side by side and bonded to each other, forming a robust conductive network that maintains conductivity even under repeated charging and discharging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If single-walled carbon nanotubes are used as conductive agent, then conductivity of electrode active material layer is improved, but the carbon nanotubes are damaged or broken during charge and discharge cycles, leading to degradation of conductive network and reduced battery life
Solution Approach 1:
The patent uses multi-walled carbon nanotubes instead of single-walled carbon nanotubes. The multi-walled structure provides enhanced mechanical strength and structural integrity, allowing the conductive network to withstand repeated charge and discharge cycles without breaking or degrading, thus resolving the contradiction between maintaining conductivity and ensuring structural durability
Solution Approach 2:
The patent adds a specific amount (0.01-0.5 wt%) of multi-walled carbon nanotubes as a protective reinforcement before the electrode undergoes cycling. This pre-reinforcement creates a more robust conductive network that can absorb mechanical stress and prevent damage during subsequent charge and discharge operations
2Strength
If multi-walled carbon nanotubes are used to maintain conductivity, then structural integrity is improved, but the nanotubes are cut into excessively short length during dispersion preparation, limiting conductivity improvement
Solution Approach 1:
The patent optimizes the dispersion preparation parameters (sonication time, intensity, and duration) to achieve complete dispersion of multi-walled carbon nanotubes without excessive cutting. By carefully controlling these parameters, the patent maintains the structural integrity and adequate length of the nanotubes while ensuring they are sufficiently dispersed to form an effective conductive network
Solution Approach 2:
The patent applies a moderate amount of mechanical energy during dispersion (not excessive sonication) to achieve sufficient dispersion without causing excessive cutting of the nanotubes. This partial action approach balances the need for dispersion with the need to maintain nanotube length and structural integrity
3Ease of manufacture
If conventional conductive agents are used, then manufacturing is simple, but resistance of the battery is excessively high and input/output characteristics are poor
Solution Approach 1:
The patent changes the type of conductive agent from conventional point-type (carbon black) to linear-type (multi-walled carbon nanotubes) and optimizes the content to 0.01-0.5 wt%. This parameter change significantly improves electrical conductivity and input/output characteristics while maintaining relatively simple manufacturing processes through standard dispersion techniques
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
This approach enhances the battery's input/output characteristics and high-temperature life characteristics by maintaining a low resistance and forming a uniform conductive network, thereby improving the battery's overall performance and durability.
Implementation Method 1
the carbon nanotube structures are contained in the electrode active material layer in an amount of 0.01 wt% to 0.5 wt%... conductivity in an electrode active material layer is improved... maintains a low resistance and forming a uniform conductive network
Data Source
Figure 1(A)~1(C)
Figure 2(A)~2(B)
Figure 3
AI summary
The present invention relates to an electrode and a secondary battery including the same, the electrode including an electrode active material layer, the electrode active material layer including an electrode active material and a conductive agent, the conductive agent including: a multi-walled carbon nanotube unit; and a carbon nanotube structure in which 2 to 5,000 single-walled carbon nanotube units are bonded to each other, wherein the carbon nanotube structure is contained in the electrode active material layer in an amount of 0.01 wt% to 0.5 wt%.