Battery Electrode Conductive Network Using Graphene-CNT Composite
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Solution Overview
Problem
Existing lithium secondary batteries face challenges in maintaining low electrode resistance and improving battery life characteristics due to the degradation of conductive networks during charge and discharge cycles.
Innovation Solution
The use of an electrode active material layer that includes a conductive agent comprising a secondary particle with interconnected graphene sheets and a carbon nanotube structure, where the carbon nanotube structure is formed by bonding 2 to 5,000 single-walled carbon nanotube units, and is included in an amount of 0.01 wt % to 0.5 wt % in the electrode active material layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If single-walled carbon nanotube units are used as conductive agent, then electrical conductivity of electrode is improved, but conductive network is damaged during charge and discharge cycles
Solution Approach 1:
The patent combines single-walled carbon nanotube units with graphene sheets to form a composite conductive agent. The carbon nanotube structure provides excellent electrical conductivity, while the graphene sheets act as a protective matrix that prevents the nanotube units from breaking during battery cycling. This composite structure resolves the contradiction by maintaining both high conductivity and structural stability over extended battery life.
Solution Approach 2:
The graphene sheets are incorporated beforehand to cushion and protect the carbon nanotube units from mechanical damage during subsequent charge and discharge cycles. This preventive approach ensures that the conductive network remains intact throughout the battery's operational life, addressing the durability issue before it occurs.
2Reliability
If multi-walled carbon nanotubes are used to ensure conductivity, then conductivity is maintained when surface is damaged, but electrode conductivity improvement is limited due to short length
Solution Approach 1:
The patent creates a composite where long single-walled carbon nanotube units (providing high conductivity) are protected by graphene sheets (providing durability). This avoids the length limitation of multi-walled nanotubes while maintaining both conductivity and durability through the protective graphene matrix.
Solution Approach 2:
The patent changes the structural parameters of the conductive agent by using intact, long single-walled carbon nanotube units rather than short multi-walled nanotubes. The graphene coating allows these long nanotubes to maintain their length and conductivity while gaining protection, thus improving electrode productivity without sacrificing reliability.
3Reliability
If graphene is used as conductive agent, then electrical conductivity is excellent, but electrolyte solution mobility is limited due to wide planar contact
Solution Approach 1:
The patent creates a composite conductive agent where graphene sheets are combined with carbon nanotube units. The graphene provides excellent electrical conductivity, while the carbon nanotube structure creates a more open, three-dimensional network that allows better electrolyte penetration and mobility, thus resolving the contradiction between conductivity and ion transport.
Solution Approach 2:
The patent applies different structural characteristics to different parts of the conductive network: graphene sheets provide localized conductivity enhancement at contact points, while the carbon nanotube framework provides open channels for electrolyte mobility. This local differentiation of functions resolves the contradiction between conductivity and ion transport speed.
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 configuration maintains a stable conductive network, reduces electrode resistance, and enhances battery life characteristics by preventing damage to the carbon nanotube structure during repeated charge and discharge cycles.
Implementation Method 1
the second conductive agent includes a carbon nanotube structure in which 2 to 5,000 single-walled carbon nanotube units are bonded to each other
Implementation Method 2
the first conductive agent includes a secondary particle in which a plurality of graphene sheets are arranged in different directions and a portion of one graphene sheet is connected to a portion of adjacent another graphene sheet
Data Source
AI summary
The present invention relates to an electrode including an electrode active material layer, wherein the electrode active material layer includes an electrode active material and a conductive agent, wherein the conductive agent includes a first conductive agent and a second conductive agent, wherein the first conductive agent includes a secondary particle in which a portion of one graphene sheet is connected to a portion of adjacent another graphene sheet, the secondary particle includes a plurality of graphene sheets arranged in different directions, the second 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, and a secondary battery including the same.