Reactions of lithium with small graphene fragments: semi-empirical quantum chemical calculations

摘要

Semi-empirical and ab initio calculations [1], as well as inelastic neutron spectroscopy [2], deomstrate that Li can bind to protnated "edge carbons" to create a moiety analogous to the organolithium monomer C_2H_2Li_2. This porivides 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 polyaromatic 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 sp~2 hybridization, whereas Li added to PAH'es creates sp~3 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.