Li doped carbons (activated microporous carbons and graphite): Characterisation by resonance spectroscopies (ESR and 7Li NMR) and their potentiality for hydrogen adsorption

LiCx (x=6, 12, 18) graphite intercalation compounds (GICs) and LiCy (y=6, 18) doped activated carbons have been obtained by vapour phase reaction in a vacuum sealed stainless steel reactor. The absence of hydrogen adsorption in the intercalated galleries is observed in all the lithiated Graphite Intercalation Compounds whatever the temperature. 7Li Nuclear Magnetic Resonance and Electron Spin Resonance (ESR) measurements in the range [10–300 K] have brought out the electron charge transfer from Li to the surface of the microporous carbons. At 77 K, the Li doped activated carbons adsorb less hydrogen than raw materials due to the decrease of the accessible porosity filled by Li ions. The H2 adsorption capacity at room temperature of the Li-doped activated carbon (0.20 wt%) is higher than for the raw material (0.16 wt%). Hence, the adsorption energy is enhanced after doping through the electron charge transfer from Li to microporous carbon.