Battery Electrode Conductive Network Using Bonded SWCNT Structures
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Solution Overview
Problem
Lithium secondary batteries face challenges in maintaining conductivity and energy density due to the damage and shortening of single-walled carbon nanotubes during charge and discharge cycles, leading to increased resistance and reduced life characteristics.
Innovation Solution
Incorporating carbon nanotube structures where 2 to 5,000 single-walled carbon nanotube units are bonded side by side, with an average length of 1 um to 500 um, and using a combination with carbon black as a conductive agent to form a robust conductive network, reducing the content of conductive agents and enhancing electrode conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If single-walled carbon nanotube units are completely dispersed to form a conductive network, then conductivity is improved, but the nanotubes are damaged or broken during charge and discharge cycles, leading to increased resistance and reduced battery life
Solution Approach 1:
The patent segments the carbon nanotube structure into multiple wall layers, where the inner wall provides primary conductivity and the outer walls provide protective reinforcement. This segmentation allows the conductive function to be separated from the protective function, enabling the nanotube to maintain conductivity while resisting mechanical damage during battery cycles.
Solution Approach 2:
The patent employs composite material design by combining multiple wall layers of carbon nanotubes with specific structural characteristics. The composite structure integrates conductive graphite layers with mechanically robust wall configurations, creating a material that simultaneously achieves high conductivity and damage resistance during electrochemical cycling.
2Reliability
If multi-walled carbon nanotubes are used to maintain conductivity, then resistance is reduced, but the nanotubes are cut into excessively short lengths during dispersion preparation, limiting conductivity improvement
Solution Approach 1:
The patent changes critical parameters of the carbon nanotube structure, specifically controlling the outer diameter to be 50-200 nm and the length to be 1-10 μm. These parameter optimizations ensure that the nanotubes maintain sufficient length for effective conductivity while fitting within the electrode matrix. The parameter control also prevents excessive cutting during dispersion preparation by matching the nanotube dimensions with appropriate processing conditions.
3Reliability
If conductive agent content is increased to reduce resistance, then conductivity is improved, but energy density of the battery decreases
Solution Approach 1:
The patent optimizes the content of carbon nanotube structures to be 0.1-5 wt% of the total electrode weight, which is significantly lower than conventional conductive agent loadings. This parameter optimization achieves effective conductivity through the enhanced intrinsic conductivity and protective structure of the multi-walled nanotubes, reducing the quantity of conductive agent needed while maintaining or improving energy density.
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 maintains low electrode resistance, improves energy density and life characteristics, and prevents conductivity degradation by forming a durable conductive network that withstands repeated charge and discharge cycles.
Implementation Method 1
carbon nanotube structures in which 2 to 5,000 single-walled carbon nanotube units are bonded to each other side by side... enhancing electrode conductivity
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 point-type conductive agent; 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 has an average length of 1 µm to 500 µm, and the carbon nanotube structure is contained in the electrode active material layer in an amount of 0.01 wt% to 5.0 wt%.