Superionic conductivity in the Li4C60 fulleride polymer.
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.
Riccò
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M
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
Belli
M
M
Mazzani
M
M
Pontiroli
D
D
Quintavalle
D
D
Jánossy
A
A
Csányi
G
G