R&D of supercapacitors in Skeleton NanoLab
At Tartu Tehnoloogiad, the Supercapacitor is the most developed application of SkeletonC carbon. Double layer Supercapacitors, having the symmetric electrode design (carbon-carbon), accumulate and deliver energy through the adsorption-desorption of electrolyte ions. Typically, the positive and negative ions have different size. For the best Supercapacitor performance, the ions sizes and pore sizes where the sorption process takes place, should be matched so that the pores in negative electrode are good recipients for cations and the pores in positive electrode are good recipients for anions. SkeletonC carbon synthesis technology significantly widens the possibility to find the optimum matching between pores and ions. The selection of carbons for the electrodes allows designing the balanced electrochemical systems that have the optimum (best) performance at requested application conditions.
- Progress in developing the carbon with high EDL capacitance over past five years
Electrochemical evaluation of SkeletonC
Adjusting the pore size of SkeletonC to provide superior SuperCap performance
The microporosity in electrodes is optimised by choosing appropriate reaction conditions for carbon making and the macroporosity is optimised by choosing the appropriate composition and densification methods for electrode making.
The electrochemical behavior of SkeletonC electrodes is very good in both aqueous and organic electrolytes. Due to the well-controlled synthesis process, the SkeletonC carbon has very low level of impurities and surface functional groups, therefore, the electrodes from this carbon have a rather wide region of ideal polarizability. In organic electrolytes it is more than 3V as shown in the following figure.
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| FIGURE. Cyclic voltammogram of typical nanoporous Skeleton C, measured in organic electrolyte (ν = 2 mV s-1). |
Based on selected examples of SkeletonC materials the following figures represent the responsibility of carbon pore size and it’s distribution on the energy and power performance of supercapacitor. The electrolyte is an AN-free organic in all examples. All parameters in the following examples are given per weight and volume of carbon.
| Example 1 | |
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| Example 2 | |
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| Example 3 | |
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| Example 4 | |
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The performance of Skeleton SuperCaps
Electric energy is conventionally stored in batteries or in capacitors. Batteries are able to store a lot of energy but they are not able to release the stored energy very fast. Therefore batteries are used in applications where power is needed for several minutes to several hours.
Electrolytic capacitors, on the contrary, can deliver a very high current but only for a very short time — for milli- and microseconds.
The gap between batteries and electrolytic capacitors, i.e. the range of applications, where the duration remains in seconds - is occupied with Supercapacitors.
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