Humic Acid Graphitic Films for High Conductivity
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Solution Overview
Problem
Current methods for producing highly oriented graphitic films face challenges such as low thermal and electrical conductivity, mechanical weakness, and high production costs due to the need for energy-intensive and expensive processes, with existing materials like pyrolytic graphite and CVD graphene exhibiting defects and misorientations.
Innovation Solution
A process involving the use of humic acid or humic acid-graphene hybrid films, where humic acid is dispersed and deposited onto a substrate, subjected to orientation-inducing stress, and heat-treated to produce highly aligned graphene-like planes, resulting in a graphitic film with exceptional thermal, 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 the graphitic structure can be formed, but the production process becomes energy intensive, expensive, and time-consuming with insufficient alignment
Solution Approach 1:
The invention changes the processing parameters from ultra-high temperature (2000-3000°C) to moderate temperature (700-1500°C) heat treatment, fundamentally altering the energy input requirements while achieving superior graphene plane alignment through controlled thermal processing of humic acid films
Solution Approach 2:
The invention replaces expensive, energy-intensive CVD equipment and ultra-high temperature graphitization facilities with simpler, lower-cost heat treatment processes that achieve comparable or superior results, making the production more economically viable
2Reliability
If conventional CVD methods are used to produce graphitic films, then the films can be formed, but the thermal and electrical conductivity remain lower than theoretical predictions due to defects and misorientations
Solution Approach 1:
The invention performs preliminary alignment of graphene planes during the film formation stage by depositing humic acid under controlled conditions that promote self-organization, followed by heat treatment that consolidates this alignment, rather than attempting to correct misorientations after film formation
Solution Approach 2:
The invention uses humic acid as a precursor material that contains pre-organized aromatic structures which serve as building blocks for graphene planes, creating a composite approach that combines organic precursor advantages with inorganic graphitic product properties
3Manufacturing precision
If ultra-high temperature graphitization is applied to achieve highly oriented pyrolytic graphite, then the graphitic structure is formed, but the process becomes excessively time-consuming and costly
Solution Approach 1:
The invention fundamentally changes the temperature parameter from ultra-high (2000-3000°C) to moderate (700-1500°C), which dramatically reduces the time required for graphitic structure formation while maintaining or improving crystalline orientation through controlled thermal processing
Solution Approach 2:
The invention performs preliminary organization of carbon structures during the humic acid film formation and drying stages, so that the subsequent heat treatment only needs to consolidate existing alignment rather than create it from scratch, significantly reducing processing time
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 yields a highly oriented graphitic film with thermal conductivity exceeding 1,500 W/mK, electrical conductivity over 12,000 S/cm, and tensile strength above 120 MPa, surpassing conventional materials in terms of properties and production efficiency.
Implementation Method 1
The HA or CHA dispersion is deposited onto a surface of a supporting substrate to form a wet layer of HA or CHA, wherein the dispersing and depositing procedure includes subjecting the dispersion to an orientation-inducing stress
Implementation Method 2
heat-treating the dried HA or CHA layer at a first heat treatment temperature higher than 80° C. for a sufficient period of time to produce the highly oriented humic acid film containing interconnected/merged HA/CHA molecules or thermally reduced HA or CHA sheets that are substantially parallel to one another
Implementation Method 3
The first heat treatment temperature is for chemically linking and thermal reduction of HA/CHA and is conducted at the first temperature of >80° C. (can be up to 1,000° C., but preferably up to 700° C., and most preferably up to 300° C.)
Implementation Method 4
The first heat treatment temperature is for chemically linking and thermal reduction of HA/CHA and is conducted at the first temperature of >80° C. (can be up to 1,000° C., but preferably up to 700° C., and most preferably up to 300° C.)
Implementation Method 5
The process (with or without the step of compressing) can further comprise a step (e) of further heat-treating the humic acid film of reduced HA or CHA at a second heat treatment temperature higher than the first heat treatment temperature for a sufficient period of time to produce a graphitic film having an inter-planar spacing d002 less than 0.4 nm and an oxygen content or non-carbon element content less than 5% by weight; and (f) compressing said graphitic film to produce a highly conducting graphitic film
Implementation Method 6
dispensing and depositing the HA or CHA dispersion onto a surface of a supporting substrate to form a wet layer of HA or CHA
Implementation Method 7
partially or completely removing the liquid medium from the wet layer of HA or CHA to form a dried HA or CHA layer
Data Source
AI summary
A process for producing a highly oriented humic acid (HA) film, comprising: (a) preparing a dispersion of HA or chemically functionalized HA (CHA) sheets dispersed in a liquid medium, wherein HA sheets contain an oxygen content higher than 5% by weight or CHA sheets contain non-carbon element content higher than 5% by weight; (b) dispensing and depositing HA or CHA dispersion onto a surface of a supporting substrate to form a wet layer, under an orientation-inducing stress; (c) removing liquid medium from the wet layer to form a dried HA or CHA layer having hexagonal carbon planes and an inter-planar spacing d002 of 0.4 nm to 1.3 nm as determined by X-ray diffraction; and (d) thermally reducing the dried HA or CHA layer at a first heat treatment temperature higher than 80° C. for a sufficient period of time to produce the film containing reduced HA or CHA.