Polymer based carbons as potential materials for energy storage in Lithium /Oxygen batteries

Porous carbon aerogels are prepared by polycondensation of resorcinol (R) and formaldehyde (F) catalyzed by sodium carbonate (C) followed by carbonization of the resultant aerogels at 800 ̊C in an inert atmosphere. The porous texture of the carbons has been adjusted by the change of the molar ratio of resorcinol to catalyst (R/C) in the gel precursors in the range of 100 to 500. The porous structure of the aerogels and carbon aerogels are characterized by N2 adsorption-desorption measurements at 77 K. It is found that total pore volume and average pore diameter of the carbons increase with increase in the R/C ratio of the gel precursors. The prepared carbon aerogels are used as active materials in fabrication of composite carbon electrodes. The electrochemical performance of the electrodes has been tested by using them as cathodes in a Li/O2 cell. Through the galvanostatic charge/discharge measurements, it is found that with an increase of R/C ratio, the specific capacity of the Li/O2 cell fabricated from the carbon aerogels increases from 716 to 2077 mA h g. The resulting voltage profiles for the first ten charge/discharge cycles indicate that the carbon samples possess excellent stability on cycling.