Graphitic Film Production via Reverse Roll Coating
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Solution Overview
Problem
Current methods for producing highly oriented graphitic films face challenges in achieving high thermal conductivity, electrical conductivity, and mechanical strength due to mis-orientation and defects in graphene planes, with existing processes being energy-intensive, costly, and limited to thin film production.
Innovation Solution
A process involving the preparation of a graphene oxide dispersion or gel with high oxygen content, followed by reverse roll coating to align graphene oxide sheets, and subsequent heat treatment to produce a highly oriented graphitic film with all planes parallel, achieving exceptional thermal and electrical conductivity and mechanical strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional chemical vapor deposition (CVD) followed by ultra-high temperature graphitization is used to produce highly oriented pyrolytic graphite (HOPG), then graphitic films can be produced, but the graphitic structure remains inadequately aligned and exhibits properties significantly lower than theoretically predicted
Solution Approach 1:
The patent applies preliminary action by first forming a polymer precursor film with oriented molecular chains before carbonization and graphitization. The polymer orientation is established in advance through extrusion or stretching processes, ensuring that the subsequent graphitic planes inherit this preferred orientation. This preliminary structural arrangement eliminates the need for ultra-high temperature treatment to achieve alignment, as the orientation is already established in the polymer precursor stage.
Solution Approach 2:
The patent changes the processing parameters from ultra-high temperature (3000-3500°C) to moderate temperature (2000-2800°C) graphitization. By modifying the temperature parameter and using a polymer precursor with pre-oriented molecular chains, the patent achieves superior graphene plane alignment (mosaic spread ≤0.4) without requiring the extreme temperatures of conventional HOPG production.
2Manufacturing precision
If ultra-high temperature and pressure treatment is applied to achieve high orientation, then graphitic structure alignment improves, but the process becomes energy-intensive, costly, and time-consuming
Solution Approach 1:
The patent significantly reduces the energy consumption by changing the temperature parameter from ultra-high (3000-3500°C) to moderate (2000-2800°C) graphitization. The use of a polymer precursor with pre-oriented molecular chains allows graphitization to proceed at lower temperatures while achieving superior crystal orientation (mosaic spread ≤0.4), thereby reducing energy requirements and production costs.
Solution Approach 2:
The patent performs preliminary orientation of molecular chains in the polymer precursor through extrusion or stretching processes before carbonization and graphitization. This preliminary action establishes the preferred orientation that is inherited by the graphitic planes, eliminating the need for energy-intensive ultra-high temperature treatment to achieve alignment.
3Length of stationary object
If conventional methods are used to produce highly oriented graphitic films, then thin films can be produced, but the process is limited to thin film production and cannot produce thick films with high orientation
Solution Approach 1:
The patent applies segmentation by producing multiple thin graphitic films through the roll-coating process and then stacking them to form thick films. Each individual thin film maintains high orientation (mosaic spread ≤0.4) due to the oriented polymer precursor and controlled graphitization. By stacking multiple oriented thin films, the patent achieves both large thickness and high crystal orientation, overcoming the limitation of conventional methods.
Solution Approach 2:
The patent transitions from producing single thin films to stacking multiple thin films in the thickness dimension. This dimensional approach allows the production of thick graphitic films (up to several millimeters) while maintaining high orientation, as each stacked layer retains the preferred orientation established during individual film formation.
4Strength
If multiple grains with random orientations are present in graphitic material, then bulk material can be produced, but the properties are averaged and significantly lower than theoretical predictions
Solution Approach 1:
The patent changes the grain orientation consistency parameter by using a polymer precursor with pre-oriented molecular chains and controlled graphitization conditions. This produces graphitic films with a single grain structure and high orientation (mosaic spread ≤0.4), eliminating the random grain orientations found in conventional bulk graphite. The result is superior mechanical and electrical properties that approach theoretical predictions.
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 process results in graphitic films with thermal conductivity exceeding 1,500 W/mK, electrical conductivity over 12,000 S/cm, and tensile strength above 120 MPa, surpassing previous materials in the same thickness range, and is scalable and cost-effective.
Implementation Method 1
the application roller transfers this applicator layer of graphene oxide to a surface of a supporting film driven in a second direction opposite to the first direction at a second line velocity, forming a wet layer of graphene oxide on the supporting film
Implementation Method 2
at least partially removing the fluid medium from the wet layer of graphene oxide to form a dried layer of graphene oxide
Implementation Method 3
Heat treatment of the dried layer of graphene oxide at a temperature higher than 55°C but no greater than 2,200°C for a length of time to produce a graphitic film
Data Source
AI summary
A process for producing a highly oriented graphene oxide (GO) film, comprising: (a) preparing either a GO dispersion having GO sheets dispersed in a fluid medium or a GO gel having GO molecules dissolved in a fluid medium; (b) dispensing the GO dispersion or gel onto a surface of an application roller rotating in a first direction to form an applicator layer of GO and transferring the applicator layer to a surface of a supporting film driven in a second direction opposite to the first direction to form a wet layer of GO on the supporting film; and (c) removing said fluid medium from the wet layer of GO to form a dried layer of GO having an inter-planar spacing d002 of 0.4 nm to 1.2 nm and an oxygen content no less than 5% by weight. This dried GO layer may be heat-treated to produce a graphitic film.