Ionic conductivity in the Mg intercalated fullerene polymer Mg2C60

We report the identification of the new intercalated fullerene polymer Mg2C60. Mg intercalation was obtained either by solid state reaction between C-60 and Mg, or by thermal decomposition of the metallorganic precursor Mg-Anthracene-(THF)(3). High resolution powder synchrotron and neutron diffraction data have clearly shown that Mg2C60 is isostructural to the superionic conductor Li4C60, where fullerenes form a two-dimensional network connected either by four-membered carbon rings, or single C-C bonds. Because of its peculiar structural arrangement Mg2C60 behaves as a good ionic conductor by means of uncorrelated ionic hopping across very small energy barriers (Delta E less than 100 meV), as found from DC and AC conductivity measurements, thus suggesting its possible use in future Mg-ion batteries. (C) 2012 Elsevier Ltd. All rights reserved.