Sodium reactivity with carbons

We report in this paper some results on the reactivity of different carbon materials, and in particular a set of pitch-coke samples heat treated between 800 and 2400 degrees C, with sodium. An experimental cell has been designed, which allows carbon to react with sodium vapor at relative pressure close to 0.9 up to 800 degrees C. The different carbon-sodium samples were examined using X-ray diffraction. The sodium uptake has been related both to intercalation and adsorption or capillary condensation. It is shown that the amount of intercalated sodium cannot be related to one of the structural parameters deduced from the X-ray diffraction patterns or from the Raman spectra of the pristine samples. We then discuss the uncertainty of our results as a function of the crystallite size (L(a) and L(c)) of the carbon samples, assuming an in-plane ratio C:Na of 8. Finally, some preliminary results concerning the electrochemical intercalation of sodium in pitch-coke samples heat-treated at different temperatures in a solid state sodium-carbon battery using a polymer electrolyte will be presented in order to assess the amount of intercalated sodium.