Z. Naturforsch. 2012,
67b, 1212 – 1220
doi:10.5560/ZNB.2012-0223
LiBC – Synthesis, Electrochemical and Solid-state NMR Investigations
Thorsten
Langer1,2,
Sven
Dupke2,
Christian
Dippel2,
Martin
Winter2,
Hellmut
Eckert2, and
Rainer
Pöttgen1
1 Institut für Anorganische und Analytische Chemie, Universität Münster, Corrensstraße 30, D-48149 Münster, Germany
2 Institut für Physikalische Chemie, Universität Münster, Corrensstraße 30, D-48149 Münster, Germany
Received August 20, 2012 / published online November 12, 2012
LiBC was synthesized from the elements in a sealed niobium ampoule. It represents a totally intercalated heterographite with a structural relationship to graphite, the most commonly used anode material for lithium ion batteries. Since LiBC could accommodate three times as much lithium as graphite, its electrochemical properties in the anode and the cathode voltage range were investigated. However, LiBC did show poor performance both as an anode and as a cathode material. The unfavorable characteristics of LiBC with respect to electrochemical de-lithiation and re-insertion can be rationalized on the basis of nuclear magnetic resonance results. 7Li and 6Li isotropic chemical shifts are consistent with complete ionization of the lithium species. Variable-temperature static 7Li NMR lineshapes indicate that the mobility of the lithium ions is rather
restricted, even at temperatures up to 500 K. The 11B and 13C NMR parameters are consistent with those measured in sp2-hybridized boron/carbon networks and also support the ionic bonding model.
Key words: Lithium, Heterographite, Solid-state NMR, Electrochemical Properties