Graphite Powder Processing via Liquid Shear Delamination
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Solution Overview
Problem
Existing graphite materials produced by conventional grinding processes, such as ball milling, fail to create highly oriented grain aggregates (HOGA) with superior electrical and thermal conductivity, high density, and shiny appearance, due to unspecific particle shape and low energy input.
Innovation Solution
A mechanical treatment in an attrition mill or agitator mill using a liquid medium applies high shear forces parallel to the platelet plane, delaminating graphite crystals along van-der-Waals layers without breaking them, resulting in stable, highly oriented graphite aggregates with enhanced conductivity and surface chemistry.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If conventional grinding processes (ball milling) are used to reduce graphite particle size, then particle size decreases to micron or nano dimensions, but the graphite fails to form highly oriented grain aggregates and shows low electrical resistivity
Solution Approach 1:
The graphite particles are segmented into individual crystallites through controlled delamination in liquid medium, separating the stacked graphene layers while maintaining crystal integrity. This segmentation allows subsequent formation of highly oriented grain aggregates where crystallites are arranged with preferred orientation, resolving the contradiction between size reduction and orientation control.
Solution Approach 2:
The invention changes the processing parameters by using liquid medium instead of dry environment, and applies controlled shear forces through attrition or agitation. These parameter changes enable delamination without random fragmentation, allowing formation of anisometric particles with high aspect ratio and highly oriented grain structures, thus achieving both size reduction and orientation control.
2Volume of moving object
If dry attrition milling is used to reduce particle size, then particles are broken down to nanometer dimensions, but the process causes unspecific reduction and delamination without forming anisometric HOGA graphite
Solution Approach 1:
A liquid medium is introduced as an intermediary between the graphite particles and the mechanical energy input. This liquid medium allows controlled delamination through shear forces while preventing random impact fragmentation. The liquid facilitates the formation of anisometric particles with high aspect ratio by enabling layer separation without complete particle disintegration, thus achieving specific morphology control.
Solution Approach 2:
The invention replaces the high-impact mechanical system of dry attrition milling with a shear-dominated mechanical system operating in liquid medium. This substitution changes the dominant force from impact to shear, enabling controlled delamination and formation of anisometric particles with highly oriented grains, rather than unspecific size reduction.
3Shape
If graphite layers are peeled off to produce flaky graphite powders, then exfoliated graphite is obtained, but the surface properties and density are shifted to decreased values
Solution Approach 1:
Instead of complete exfoliation of graphite layers, the invention applies partial delamination to separate individual crystallites while maintaining the stacked structure within grain aggregates. This partial action preserves the density and surface properties by keeping crystallites associated in highly oriented arrangements, rather than complete separation which would reduce density and alter surface characteristics.
4Ease of operation
If ball mill grinding is used to produce graphite dispersions, then colloidal dispersions are obtained, but the process is not suitable to produce anisometric HOGA-like graphite
Solution Approach 1:
The invention uses dynamic agitation or attrition in liquid medium to achieve both dispersion and anisometric particle formation. The continuous motion and shear forces dynamically delaminate graphite layers and orient crystallites during the process, forming anisometric particles with high aspect ratio and highly oriented grains, while maintaining good dispersion capability for subsequent applications.
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 produces graphite powders with increased electrical and thermal conductivity, higher density, and a shiny appearance, achieving lower electrical resistivity and improved mechanical stability, suitable for use in electrodes and coatings.
Implementation Method 1
A mechanical treatment in an attrition mill or agitator mill using a liquid medium applies high shear forces parallel to the platelet plane, delaminating graphite crystals along van-der-Waals layers without breaking them
Implementation Method 2
delaminating graphite crystals along van-der-Waals layers
Implementation Method 3
the delamination, which is carried out in liquid medium, is mainly generating delamination. An extremely anisometric form of graphite like the HOGA graphite in the micrometer dimension has not been described by Byoung et. al.
Data Source
AI summary
The present invention provides a novel non-exfoliated graphite powder containing highly oriented grain aggregates (HOGA) having a new morphology and surface chemistry, methods for the production of such graphite powders as well as products containing such novel graphite particles.