15 JUNE 2015 - LMGP SEMINAR - Dr. Ana Karina Cuentas-Gallegos - Surface Modification of Carbon Materials for Improved Capacitance

Dr. Ana Karina Cuentas-Gallegos
Instituto de Energías Renovables- Universidad Nacional Autónoma de México,
Representative of the energy field in the Academic Committee of Engineering graduate studies.

 Abstract

Supercapacitors (SC) are energy storage devices with higher power but lower energy density than Li batteries. SC stores energy based on two mechanisms: double layer capacitance (non-Faradaic) and pseudocapacitance (faradaic). Porous carbon materials have been extensively used as electrodes in SC, where their great surface area and pore size distribution have been the main properties for capacitance improvement. Nevertheless, these properties show limitations since they cannot be highly increase without losing electric conductivity, which is detrimental for the power requirements of SC. An alternative approach to increase capacitance has been the modification of the surface of carbon materials by introducing pseudocapacitive contributions. In this work, the effect of grafted functional groups and electroactive nanoparticles has been studied to improve the intrinsic capacitance values of different carbon materials, such as: graphene oxide (GO), carbon aerogels (CA), and activated carbon (AC). Different characterization techniques were used to monitor the surface modifications made on the different carbons, such as: N2 and CO2 isotherms to determine BET surface area and pore size distribution attenuated Total Reflectance (ATR) to identify the formed chemical bonds, and cyclic voltammetry to evaluate the electrochemical performance for their use as electrodes in supercapacitor cells. The results show that these surface modifications made on the different carbon matrices show the same trend on capacitance improvement.