title: Superionic conductivity in the Li4C60 fulleride polymer.
abstract: We report on the extraordinary superionic conductivity in the fulleride polymer Li4C60, a crystalline material with no disorder. 7Li, NMR, and dc frequency dependent conductivity show uncorrelated ionic hopping across small energy barriers (DeltaE_{a} approximately 200 meV) and an ionic conductivity of 10;{-2} S/cm at room temperature, higher than in "standard" ionic conductors. Ab initio calculations of the molecular structure find intrinsic unoccupied interstitial sites that can be filled by Li+ cations in stoichiometric Li4C60 even at low temperatures. The low energy required for the occupation of these sites allows a sizable Li+ diffusion above 130 K. The results suggest novel application of lithium intercalated fullerides as electrodes in Li ions batteries.
authors.affiliation: Dipartimento di Fisica and Consorzio Nazionale Interuniversitario per le Scienze Fisiche della Materia, Università di Parma, Via G.Usberti 7/a, 43100 Parma, Italy. Mauro.Ricco@fis.unipr.it
authors.forename: M
authors.initials: M
authors.lastname: Riccò
authors.forename: M
authors.initials: M
authors.lastname: Belli
authors.forename: M
authors.initials: M
authors.lastname: Mazzani
authors.forename: D
authors.initials: D
authors.lastname: Pontiroli
authors.forename: D
authors.initials: D
authors.lastname: Quintavalle
authors.forename: A
authors.initials: A
authors.lastname: Jánossy
authors.forename: G
authors.initials: G
authors.lastname: Csányi