Home – Home – Jornals – Journal of Structural Chemistry 2011 number 5

Lithium absorption in silicon is studied at the DFT level. By means of the developed method of modeling the structure of amorphous silicon, including with impurities, it is shown that with an increase in the lithium concentration intermediate amorphous Li_xSi_y phases, up to the crystalline Li₁₅Si₄ phase, form in crystalline silicon. An increase in the silicon cell volume, as it is filled with lithium, is calculated. A nonlinear dependence of silicon voltage on lithium intercalation is found. The lithium diffusion coefficient in crystalline silicon at a low lithium concentration is calculated and it is demonstrated for amorphous silicon that lithium diffusion is substantially accelerated by the lattice deformation inherent in amorphous silicon. The calculated values can be used in the production of high-capacity lithium ion batteries with a silicon anode.