Sodium catalytic effect in the NaxLi6-xC60 hydrogen storage process

TL;DR

This study investigates how sodium influences hydrogen storage in NaxLi6-xC60 compounds, revealing improved absorption rates, lower operating temperatures, and enhanced kinetics compared to lithium-only systems.

Contribution

It demonstrates the catalytic effect of sodium in enhancing hydrogen storage performance in fulleride compounds, with optimal stoichiometry identified for improved kinetics and lower dehydrogenation temperature.

Findings

Na1Li5C60 absorbs up to 4.3 wt% H2 at 280°C

Kinetics improved by 67% compared to Li6C60

Dehydrogenation enthalpy reduced by 13 kJ/mol H2

Abstract

We report on the hydrogen sorption investigation of the mixed alkali cluster intercalated fulleride series NaxLi6-xC60. These compounds are isostructural to Na6C60 and Li6C60 while the cubic lattice parameter is linearly dependent on x. The H2 absorption/desorption was studied by means of charge/discharge kinetic and coupled calorimetric - manometric measurements. By varying the stoichiometry, we found the best compromise between absorption rate, temperature and amount of hydrogen in Na1Li5C60. This system is able to reversibly absorb up to 4.3 wt% H2 at 280 {\deg}C, which is 70 {\deg}C lower in temperature than its parent compound Li6C60. Furthermore, the kinetics is improved of 67% with respect Li6C60 and the dehydrogenation enthalpy is 13 kJ/mol H2 lower.