Activated Carbon Production via Controlled Calcination and Activation
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Solution Overview
Problem
Existing methods for producing activated carbon for electric double layer capacitors face challenges in achieving a small particle diameter, uniform size, and large specific surface area while preventing particle fusion during the activation process, which affects the energy density and output characteristics required for modern applications.
Innovation Solution
The process involves calcining an easily graphitizable carbon material with a controlled reduction rate of the hydrogen/carbon atomic ratio and volatile components, followed by activation, to produce activated carbon with a specific surface area of 1500 to 3000 m²/g and an average particle diameter of 0.5 to 7 µm, eliminating the need for grinding and reducing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If activated carbon is ground with a ball mill to make particle size uniform, then particle size uniformity is improved, but fine pores are crushed resulting in decreased specific surface area
Solution Approach 1:
The invention performs preliminary size reduction of the carbonaceous raw material before the activation process. By controlling the particle size of the raw material to 0.5-7 μm before activation, the need for subsequent grinding is eliminated, thereby preserving the fine pores and maintaining high specific surface area in the final activated carbon product.
2Area of stationary object
If fine raw materials are activated to produce activated carbon, then specific surface area is improved, but particles fuse together resulting in larger particle diameter
Solution Approach 1:
The invention carefully controls the activation parameters including temperature (600-1200°C), time, and alkali metal compound concentration to achieve the desired balance. By optimizing these parameters, the activation process creates fine pores and increases specific surface area while preventing excessive particle fusion that would lead to oversized particles.
3Quantity of substance
If alkali metal compound and carbon material are heated at high temperature for activation, then fine pores are formed improving energy density, but particle size increases due to fusion
Solution Approach 1:
The invention performs preliminary size reduction of the carbonaceous raw material before the activation process. By controlling the particle size of the raw material to 0.5-7 μm before activation, the need for subsequent grinding is eliminated, thereby preserving the fine pores and maintaining high specific surface area in the final activated carbon product.
Solution Approach 2:
The invention carefully controls the activation parameters including temperature (600-1200°C), time, and alkali metal compound concentration to achieve the desired balance. By optimizing these parameters, the activation process creates fine pores and increases specific surface area while preventing excessive particle fusion that would lead to oversized particles.
4Manufacturing precision
If grinding is performed after activation to achieve uniform particle size, then particle size uniformity is improved, but production cost increases
Solution Approach 1:
The invention performs preliminary size reduction of the carbonaceous raw material before the activation process. By controlling the particle size of the raw material to 0.5-7 μm before activation, the need for subsequent grinding is eliminated, thereby preserving the fine pores and maintaining high specific surface area in the final activated carbon product.
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 enables the production of activated carbon with enhanced capacitance per unit volume and excellent output characteristics, suitable for high-performance electric double layer capacitors.
Implementation Method 1
calcining an easily graphitizable carbon material with a controlled reduction rate of the hydrogen/carbon atomic ratio and volatile components
Implementation Method 2
a carbon material such as petroleum coke and an alkali metal compound such as potassium hydroxide are heated at a temperature of 600 to 1200°C in an inert gas atmosphere to allow the alkali metal to ingress between and react with graphite crystal layers
Data Source
Figure 1~2
Figure 3~4
AI summary
The present invention provides a process of producing an activated carbon for an electric double layer capacitor, which can produce easily and inexpensively an activated carbon free from fusing of carbon particles during activation and having a small diameter, a uniform particle diameter, and a relatively large specific surface area on a commercial scale. The process comprises the steps of calcining an easily graphitizable carbon material so that the reduction rates of the hydrogen/carbon atomic ratio (H/C) and the volatile components in the carbon material are 4 percent or more and 5 percent or more, respectively after calcination and activating the carbon material thereby producing an activated carbon for an electric double layer capacitor, having an average particle diameter of 0.5 to 7 µm and a BET specific surface area of 1500 to 3000 m 2 /g.