Continuous Graphene Fibers via Chemical Bonding and Shear Alignment
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Solution Overview
Problem
Current methods for producing continuous graphene fibers are tedious, energy-intensive, and expensive, resulting in fibers with low tensile strength and modulus due to porous and non-oriented structures, making them unsuitable for scalable production.
Innovation Solution
A process involving chemically functionalized graphene sheets that are aligned and chemically bonded using mechanical shear stress and heat or radiation, forming continuous fibers with inter-planar spacing of 0.36 nm to 1.5 nm and a non-carbon element content of 0.1% to 47% by weight, ensuring the sheets are parallel and densely packed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional pyrolysis methods are used to produce carbon fibers from PAN or pitch, then continuous carbon fibers can be obtained, but the process is energy-intensive, tedious, and expensive requiring temperatures up to 3000°C
Solution Approach 1:
The invention changes the fundamental parameters of fiber production by using chemically functionalized graphene sheets instead of organic precursors like PAN or pitch. This allows fiber formation at much lower temperatures through direct alignment and bonding of pre-synthesized graphene sheets, eliminating the need for high-temperature pyrolysis processes while maintaining fiber continuity and mechanical properties
Solution Approach 2:
The invention performs preliminary actions by pre-synthesizing and chemically functionalizing graphene sheets before fiber formation. The graphene sheets are prepared with functional groups that enable direct bonding, eliminating the need for subsequent high-temperature carbonization steps. This preliminary functionalization allows the fiber to be formed in a single low-temperature process
2Strength
If conventional carbonization processes are used, then carbon fibers with tensile strength of 1-6 GPa can be achieved, but the fibers exhibit porous and non-oriented structures limiting their mechanical properties
Solution Approach 1:
The invention segments the fiber structure into individual graphene sheets that are aligned parallel to each other along the fiber axis. Each sheet maintains its two-dimensional crystalline structure while being oriented in a specific direction, creating a segmented yet cohesive structure that provides both strength and structural precision without the porous defects of conventional carbonization
Solution Approach 2:
The invention applies local quality by ensuring that each graphene sheet within the fiber exhibits high crystallinity and specific orientation parallel to the fiber axis. This local structural quality is maintained throughout the entire fiber, creating regions of high mechanical performance that collectively provide superior tensile strength and structural precision
3Strength
If high temperature graphitization (2500-3000°C) is applied to increase Young's modulus, then modulus can reach 531 GPa, but the process requires extreme temperature control and ultra-high temperature conditions
Solution Approach 1:
The invention replaces the thermal field (high-temperature graphitization) with a chemical field approach. By using chemically functionalized graphene sheets with pre-formed covalent bonds and π-π stacking interactions, the fiber achieves high Young's modulus through chemical bonding rather than thermal graphitization, eliminating the need for complex ultra-high temperature control systems
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 resulting graphene fibers exhibit exceptional thermal conductivity, electrical conductivity, tensile strength, and Young's modulus, surpassing previous records with thermal conductivity from 200 to 1,600 W/mK and electrical conductivity from 600 to 15,000 S/cm, and tensile strength and Young's modulus ranging from 1.0 to 5.0 GPa and 20 to 300 GPa, respectively.
Implementation Method 1
A process involving chemically functionalized graphene sheets that are aligned and chemically bonded using mechanical shear stress and heat or radiation
Implementation Method 2
A process involving chemically functionalized graphene sheets that are aligned and chemically bonded using mechanical shear stress and heat or radiation
Implementation Method 3
A process involving chemically functionalized graphene sheets that are aligned and chemically bonded using mechanical shear stress and heat or radiation
Data Source
AI summary
Provided is a graphene-based long fiber comprising chemically functionalized graphene sheets that are chemically bonded with one another having an inter-planar spacing d002 from 0.36 nm to 1.5 nm as determined by X-ray diffraction and a non-carbon element content of 0.1% to 40% by weight, wherein the functionalized graphene sheets are substantially parallel to one another and parallel to the fiber axis direction and the fiber contains no core-shell structure, have no helically arranged graphene domains, and have a length no less than 0.5 cm and a physical density from 1.5 to 2.2 g/cm3. The graphene fiber typically has a thermal conductivity from 300 to 1,600 W/mK, an electrical conductivity from 600 to 15,000 S/cm, or a tensile strength higher than 1.0 GPa.