Effect of carbon aerogel activation on electrode lithium insertion performance

Abstract

Carbon aerogels have received much recent attention as high-capacity insertion anodes for rechargeable lithium ion batteries. Carbon aerogels were synthesized from resorcinol-formaldehyde with a sodium carbonate catalyst via a sol-gel process, ambient drying, carbonization, and activation. Gaseous CO2-activated carbon aerogels combined the advantages of amorphous and nanoporous structures, with richer porous structures and more lithium insertion points than conventional carbon aerogels. Microporosity analysis indicated a high surface area, and the pore volume effectively retained lithium and its compounds. The mesoporosity allowed the mass transport of Li+ and conferred high ionic conductivity to the electrode. These improvements led to a higher lithium insertion capacity, and the activated carbon aerogel exhibited a specific surface area of 2032 m2·g-1. X-ray diffraction (XRD) and scanning electron microscopy (SEM) revealed an amorphous structure and nanoparticle network skeleton, respectively. Lithium insertion capacities of 3870 and 352 mAh·g-1 were exhibited in the 1st and 50th galvanostatic discharge-charge (50 mA·g-1) cycles, respectively. This corresponded to irreversible capacities of 658 and 333 mAh·g-1, respectively. This work demonstrates the feasibility of CO2 activation for improving lithium insertion performance in carbon aerogels, and provides preparation and optimization procedures for other porous electrode materials. © Editorial office of Acta Physico-Chimica Sinica.