In English

Abstract

A comparative quantum chemical (РМ3 method) examination has been carried out of lithiation/delithiation processes in Si n nanoclusters and С m Si n nanocomposites. These processes in the nanocomposites (25 and ~30% С, respectively) have been shown to effect slightly on the volumes and structures of initial (С m Si n ), lithiated (Li k=0-52 С m Si n ), and delithiated (Li k=52-0 С m Si n ) silicon-carbon matrices Si/С. Electrodes from such materials should not undergo destructive effect of periodic deformations in charge/discharge cycles. On the contrary, at lesser carbon concentrations (С 6 Si 13 nanocomposite, ~16% С) lithiation results in the 1.8 times hopping expansion of V(С 6 Si 13 ), and delithiation – in the change in structure of initial silicon-carbon matrix Si/С. For Si/С electrodes with greater (more than 37%) carbon concentration (С m>18 Si n composites), lithiation results in a monotonous increase in the volume (1.3 times for С 18 Si 13 and 1.5 times for С 26 Si 13 ) whereas delithiatin leads to a considerable change in the initial structure of silicon-carbon matrix.