Innovative carbon-based materials for solid-state hydrogen storage and energy storageAuthor(s): Milanese Chiara
Alkali cluster-intercalated fullerides (ACIF) consist in crystalline nanostructures in which positively charged metal clusters are ionically bond to negatively charged C60 molecules, forming charge-transfer salts. These compounds have been recently investigated with renewed interest, appearing as a novel class of materials for hydrogen storage, thanks to their proved capability to uptake reversibly high amounts of hydrogen via a complex chemisorption mechanism. In this presentation, after a short summary on the hydrogen storage topic, the synthesis, the structural investigation and the hydrogen storage properties of Li, Na and mixed Li-Na clusters intercalated fullerides belonging to the families NaxLi12-xC60 (0 ≤ x ≤ 12) and NaxLi6-xC60 (0 ≤ x ≤ 6) will be presented. By manometric and thermal analyses it has been proved that C60 covalently binds up to 5.5 wt% H2 at moderate temperature and pressure, thanks to the catalytic effect of the intercalated alkali clusters. Moreover, the destabilizing effect of Na in the co-intercalated NaxLi6-xC60 compounds leads to an improvement of the hydrogen-sorption kinetics by about 70%, linked to a decrease in the desorption enthalpy from 62 to 44 kJ/mol H2. The addition of Pt and Pd nanoparticles to Li fullerides increases up to 5.9 wt% H2 the absorption performances and of about 35 % the absorption rate. The ammonia storage properties of Li6C60 have also been investigated, resulting quite appealing. Being the price of C60 quite high for large scale practical applications, new cheaper C based materials are under examination. In particular, porous biochar from agricultural waste are giving quite interesting results as electrode materials for high-performance supercapacitor.