Synthesis of MgO templated mesoporous carbons and its use for capacitor electrode

Mesoporous carbons (MPCs) with large specific surface area are synthesized by the heat-treatment and subsequent acid treatment of magnesium citrate. The MPCs obtained are examined as electrode materials for electric double layer capacitor and show the huge gravimetric capacitance with superior rate performance in sulphuric acid electrolyte. The MPCs also realize the larger capacitance than conventional activated carbon in organic electrolyte and extraordinary high retention of capacitance at very low temperature, such as 80% of room temperature value at -60 °C.Se han sintetizado carbones mesoporosos (MPCs) con elevadas superficies específicas mediante tratamiento térmico y posterior tratamiento ácido de citrato de magnesio. Los MPCs obtenidos se han estudiado como electrodos para condensadores de doble capa eléctrica. Estos materiales presentan una capacidad gravimétrica muy elevada y una velocidad de carga-descarga alta en medio ácido sulfúrico. Los MPCs también poseen valores de capacidad en electrolito orgánico mayores que los carbones activados convencionales y presentan una retención de capacidad extraordinariamente alta a muy bajas temperaturas (a una temperatura de -60ºC se obtiene una retención de capacidad en torno al 80% con respecto a la capacidad medida a temperatura ambiente)

Mechanochemical Processing of Natural Graphite under Different Atmospheres for Fabricating Electrodes Used in Electric Double-layer Capacitors

This study focused on the mechanochemical processing of natural graphite using a planetary ball mill under different atmospheres and analyzing their influence on the electrochemical behaviors of the processed graphite materials in electric double-layer capacitors (EDLCs). Oxygen and/or nitrogen were incorporated in the carbon framework from the atmosphere used during milling. Specific surface areas of the pulverized graphite did not significantly depend on the employed atmosphere. These pulverized graphites processed under different atmospheres were evaluated as electrode materials for application in EDLCs with an organic electrolyte. All the pulverized graphites showed comparable capacitances independently of the used atmospheres. Considering the effect of post-thermal treatment of the pulverized graphite to remove oxygen surface functionalities, changes in the surface functionalities of pulverized graphites caused by ball milling did not significantly influence their applications as electrode materials in EDLCs

KOH activated carbon multiwalled nanotubes

International audienc

Supercapacitors prepared from melamine-based carbon

The electrochemical performance of supercapacitors made of a carbon material with a moderate amount of nitrogen atoms embedded in a carbon matrix is reported. Melamine was polymerized in the interlayer spaces of mica and afterward carbonized at various temperatures between 650 and 1000 degreesC. Elemental analysis and an XPS study showed that the nitrogen content of samples stabilized at 250 degreesC for 4 h prior to carbonization was generally higher if compared to their nonstabilized counterparts and that the nitrogen species were located preferably at the edges of grapheme sheets. To understand the relationship between the capacitive performance and the porosity of stabilized and nonstabilized samples, the nitrogen adsorption/ desorption method was also employed. Supercapacitors with the electrodes manufactured from these carbon materials showed a very good capacitive performance in 1 M sulfuric acid. The maximum gravimetric specific capacitance of 204.8 F g(-1) was obtained from a sample carbonized at 750degreesC. Specific capacitances per surface area were also calculated, and, as a result, the stabilized samples provided higher values than the nonstabilized samples, for example, 3.66 F m(-2) for a sample stabilized and carbonized at 1000 degreesC. We associate the high values of capacitances in sulfuric acid with the pseudocapacitance that originates from an interaction between the nitrogen species and the protons of the electrolyte. This claim was verified by another measurement, where a neutral electrolyte (3 M NaCl) was used instead of sulfuric acid. We observed a decrease in capacitance with the surface area, and the values of capacitances per surface area were close to the values for activated carbons. Thus, the capacitance in NaCl can be attributed to the electrostatic interaction of ions on the double-layer rather than the pseudocapaeitive interaction