Resumen de Síntesis de xerogeles de carbono inducida por microondas para su uso como electrodos en supercondensadores
Esther Gómez Calvo
[EN] The present memory has been divided into two different sections, the first devoted to the production, by means of microwave technology, of carbon xerogels with tuneable properties, while the second is focused on the evaluation of these laboratory-synthesized carbon xerogels as active materials in supercapacitors. This work presents a novel method for the synthesis of carbon xerogels based on microwave heating. By means of this synthesis method, carbon xerogels with analogous properties to those obtained by conventional routes have been produced in a quicker and more efficient way. Microwave radiation has been also used as heating source in activation processes allowing the development of xerogels microporosity with much shorter operating times. The activated carbon xerogels obtained have displayed surface areas above 2000 m2 g-1 and certain presence of mesopores, textural properties highly suitable for the application proposed in this work. In the second section, the energy storage capacitance of several in-lab synthesized carbon xerogels has been evaluated. Various strategies have been carried out in order to improve the energy stored by the supercapacitor, such as: the use of electrode materials with different pore texture; the addition of highconductivity materials; the preparation of asymmetric cells (a carbon xerogel as negative electrode and MnO2 as the positive electrode) and, finally; the use of diverse electrolytes (aqueous solutions with different pH values and protic ionic liquids composed of different cations/anions). Thus, the use of unequal electrodes or ionic liquids as electrolyte produces supercapacitors that are able to operate effectively within a voltage window of 1.6 V, in the first case, and higher than 2.0 V in the second, which has a positive effect on their energy density. The properties optimization of carbon xerogel electrodes results in high values of specific capacitance (~ 200 F g-1) and, in addition, they are able to maintain such energy stored during a large number of charge-discharge cycles.
