Porous Carbon Production via Precursor Foaming
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Solution Overview
Problem
Current methods for producing porous carbon with hierarchical porosity face challenges in achieving high mesopore volumes and cost-effectiveness, as they require multiple infiltration and carbonization processes, leading to inhomogeneities and increased production costs due to the limitations of carbon precursors' solubility and shrinkage during carbonization.
Innovation Solution
A method involving the use of template particles with macropores, where the precursor substance is treated at a foaming temperature to form a fine-pored foam before carbonization, ensuring at least 70% of pores are in the range of 10 to 150 nm, utilizing a precursor like sucrose and a SiO2 template with a hierarchical structure, and optimizing the temperature and holding time for uniform foam formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If multiple infiltration and carbonization processes are used to produce porous carbon with hierarchical porosity, then the pore structure can be formed, but production costs increase and inhomogeneities occur
Solution Approach 1:
The patent applies preliminary action by treating the carbon precursor substance at a foaming temperature before carbonization to form a foam structure. This pre-foaming step ensures uniform pore formation throughout the carbon layer, eliminating the need for multiple infiltration and carbonization processes. The foam formation creates a consistent hierarchical pore structure in a single cycle, reducing production costs and avoiding inhomogeneities that would otherwise require repeated processing steps.
2Quantity of substance
If carbon precursors with high solubility are used, then pore filling is improved, but mass loss during carbonization increases
Solution Approach 1:
The patent applies parameter changes by treating the carbon precursor at a specific foaming temperature range (100-200°C) before carbonization. This temperature treatment transforms the precursor into a foam structure with controlled cell density and wall thickness. By optimizing the foaming temperature and holding time, the process achieves maximum pore filling while minimizing mass loss during subsequent carbonization, as the foam structure provides a stable framework that retains carbon material more effectively.
Solution Approach 2:
The patent utilizes phase transitions by heating the carbon precursor from its initial state through melting and foaming phases before final carbonization. The foaming process involves phase change where gas bubbles form and expand within the molten precursor, creating a cellular structure. This phase transition approach allows the precursor to fill pores effectively while the形成的 foam structure minimizes material loss during the exothermic carbonization reaction.
3Strength
If the carbon layer thickness is increased, then the porous structure is more robust, but the precursor substance requires higher infiltration capacity
Solution Approach 1:
The patent applies preliminary action by forming a foam structure in the carbon precursor before carbonization. This pre-foaming creates a three-dimensional cellular network that provides structural robustness throughout the carbon layer thickness. The foam walls act as reinforcing elements that strengthen the porous structure, eliminating the need for multiple infiltration cycles to build up sufficient mechanical strength, thus simplifying the overall process while achieving robust thick carbon layers.
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 approach results in a cost-effective production of mesoporous carbon foam with a high proportion of pores in the desired size range, enhancing the specific surface area and porosity, suitable for applications such as electrochemical cells, while maintaining mechanical stability.
Implementation Method 1
the precursor substance is subjected to a treatment at a foaming temperature Tb within the macropores of the template after infiltration according to method step (c) and before carbonization according to method step (d), which foams the precursor substance under polycondensation
Implementation Method 2
foams the precursor substance under polycondensation and thereby fills the macropores as a fine-pored foam
Implementation Method 3
removing the template to form the porous carbon product
Implementation Method 4
carbonizing the precursor at a temperature Tc
Data Source
Figure 1~2
Figure 3~4
AI summary
In a known method for producing a porous carbon product, template material in the form of template particles, which contain macropores, and a polymerizable precursor substance for carbon are provided. The macropores of the template are infiltrated with the precursor substance in dissolved or melted form. After the carbonization of the infiltrated precursor substance, the template is removed in order to form the porous carbon product. According to the invention, in order to modify the method in such a way that a carbon structure having hierarchical porosity having a high fraction of mesopores having pore sizes in the range of 2 to 50 nm is obtained, after the infiltration according to step (c) and before the carbonization according to step (d), the precursor substance is subjected within the macropores of the template to a treatment at a foaming temperature at which the precursor substance foams under polycondensation and fills the macropores as substantially mesoporous foam, in which at least 70% of the pores have pore sizes in the range of 10 to 150 nm.