Reactions of Lithium with Small Graphene Fragments: Semi-Empirical Quantum Chemical Calculations
AbstractSemi-empirical and ab initio calculations [1], as well as inelastic neutron spec-troscopy [2], demonstrate that Li can bind to protonated “edge carbons” to create a moiety analogous to the organolithium monomer C2H2Li2. This provides a possible additional channel for Li uptake in high capacity Li-ion battery anodes based on low-T pyrolyzed soft carbons. Here we show that similar reactivity is exhibited by polyaro-matic hydrocarbons with the protons removed (taken as surrogates for the structural units in hard carbons). In the deprotonated PAH'es the Li serves to saturate dangling bonds, maintaining sp2 hybridization, whereas Li added to PAH'es creates sp3 carbons at the edges. In both cases this extra reactivity occurs in parallel with the usual intercalation. These findings have implications for further development in Li-ion rechargeable battery technology.