Graphite Production via Hot Isostatic Pressing
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Solution Overview
Problem
Conventional methods for producing graphite materials face challenges such as low productivity, high cost, incomplete crystallinity, anisotropy, and difficulty in achieving high-density, porous, or large-sized graphite structures with sufficient strength for applications like lithium ion batteries and fuel cells.
Innovation Solution
A method involving hot isostatic pressing of pre-baked organic compounds in a graphite crucible under specific conditions to produce clusters of thin sheet graphite crystals with high crystallinity and isotropic properties, allowing for efficient production of graphite materials with desired structural and functional properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional methods (mixing filler and binder, molding, baking for carbonization and graphitization) are used to produce artificial graphite materials, then graphite structure with practicable strength and hardness can be obtained, but production time is extremely long (about two months) and productivity is low
Solution Approach 1:
The invention changes the temperature parameter dramatically, using laser irradiation to achieve temperatures of 2000°C or higher locally and rapidly, compared to the conventional gradual heating process that takes months. This parameter change enables the graphite structure to form much faster while maintaining the required strength and hardness properties
Solution Approach 2:
The invention replaces the conventional thermal field system (oven heating) with a laser field system. The laser provides concentrated energy that rapidly heats the carbonaceous material, substituting the slow thermal diffusion process with a focused energy beam that achieves graphitization in minutes or hours rather than months
2Quantity of substance
If filler is added in molding step to produce artificial graphite, then carbonization yield can be improved, but anisotropy is increased and bulk density and mechanical strength are decreased
Solution Approach 1:
The invention changes the temperature distribution parameter by using laser irradiation that creates a more uniform and rapid heating pattern compared to conventional oven heating. This prevents the anisotropic stress and density variations that occur during slow heating, thereby maintaining mechanical strength while achieving high carbonization yield
Solution Approach 2:
The invention performs preliminary mixing of filler and binder in a controlled manner before molding, ensuring optimal distribution that prevents anisotropy development during the rapid laser-induced graphitization process. The preliminary preparation allows the material to maintain isotropic properties throughout the transformation
3Stability of the object's composition
If high temperature graphitization treatment (2500°C or more) is applied for long period (2 to 7 days) to develop graphite crystal structure, then crystallinity is enhanced, but production time is extended and productivity is reduced
Solution Approach 1:
The invention replaces the conventional thermal field system with a laser field system that delivers concentrated energy directly to the carbonaceous material. This substitution enables the graphite crystal structure to develop in minutes or hours under laser irradiation, compared to days or weeks in conventional furnaces, while achieving equal or superior crystallinity
Solution Approach 2:
The laser irradiation can be applied in a controlled periodic manner, allowing for rapid cycles of heating and cooling that promote crystal structure development without requiring continuous long-duration exposure. This periodic action achieves high crystallinity in much shorter total time
4Stability of the object's composition
If conventional carbonization and graphitization processes are used, then graphite material with desired crystallinity can be produced, but equipment complexity and production cost are high due to large-sized ovens and long processing time
Solution Approach 1:
The invention replaces the large-sized conventional graphitization oven with a laser irradiation system. This substitution dramatically simplifies the equipment required, as the laser can be focused on small or large samples alike without requiring a massive furnace infrastructure, thereby reducing both equipment complexity and production cost while maintaining graphite crystallinity
Solution Approach 2:
The laser irradiation system serves multiple functions: it performs both carbonization and graphitization in a single step, and can process materials of various sizes and shapes without requiring different equipment configurations. This multi-functionality reduces overall equipment complexity compared to conventional separate carbonization and graphitization furnaces
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 method significantly enhances productivity, reduces production time from months to hours, and achieves high-density, porous, and strong graphite materials suitable for various applications, including lithium ion batteries and fuel cells, while minimizing metal impurities and anisotropy.
Implementation Method 1
vapor-phase-grown graphite is generated on a surface of the pre-baked starting material
Implementation Method 2
subjecting the powdery and/or particulate material together with the vessel to hot isostatic pressing treatment using a compressed gas atmosphere
Data Source
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AI summary
There are provided a cluster of thin sheet graphite crystals or the like which is useful as an electrode material for lithium ion batteries, hybrid capacitors and the like, and a method for efficiently producing the same at high productivity. The method is one for producing a cluster of thin sheet graphite crystals composed of aggregates in such a state that thin sheet graphite crystals extend from the inside toward the outside, comprising charging a powdery and/or particulate material of an organic compound pre-baked to an extent of containing remaining hydrogen in a graphite vessel, and subjecting the powdery and/or particulate material together with the vessel to hot isostatic pressing treatment (HIP treatment) using a compressed gas atmosphere under the predetermined conditions.