  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.
