Nanostructurated carbon CMK-3: Synthesis and electrochemical characterization

M. DÁVILA; D. CUSCUETA; D. BARRERA ; K. SAPAG ; S. MORENO; A. GHILARDUCCI

Buenos Aires

Simposio; Simposio Internacional: Desafío en las Baterías Recargables de Litio Oxígeno; 2012

Universidad de Buenos Aires

Due to the energetic and environmental crisis, the development of novel devices for the energy storage has been required. The Li-air batteries have promise to reach several times higher energy density than lithium-ion batteries. In the first ones, during discharge, oxygen is reduced by lithium ions to form lithium (per)oxides via (i) 2Li+ + 2e- + O2 ⇄ (Li2O2)solid, and/or (ii) 4Li+ + 4e- + O2 ⇄ 2(Li2O)solid. The pores of air cathodes in Li-air batteries become increasingly blocked by Li2O2 precipitates as the discharge proceeds. The microstructure of carbon materials is thus a critical factor that affects the electrochemical performance of Li-air batteries [1, 2]. In this work the synthesis, and the surface and electrochemical characterization of nanostructured carbon CMK-3 [3] is presented. This material is a mesoporous carbon formed by interconnected parallel nanorods, with an hexagonal porous structure. The synthesis was carried out using the nanocasting technique, using SBA-15 silica as template and sucrose as organic precursor. Nitrogen adsorption measurement, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to characterize both the inorganic template and the CMK-3. The resulting carbon has the expected structure, a surface area of 1225 m2/g and a porous width of 4.4 nm. The electrochemical characterization was performed by means of galvanostatics measurements of charge-discharge and cyclic voltammetry. A three-electrode cell, using the CMK-3 carbon in the working electrode and a Ni mesh as counter electrode was set. The reference electrode was Hg/HgO and the electrolyte KOH 6M. The measured capacity was 134 mAh/g.