Quantum-chemical modeling of lithiation of a silicon-silicon carbide composite

With the aim of searching for promising anode materials for lithium-ion batteries, quantum-chemical modeling of the introduction of lithium into a silicon layer supported by nitrogen-doped silicon carbide at Li: Si ratios of 1: 1, 2: 1, and 3: 1 has been performed by the density functional theory method with inclusion of gradient correction and periodic boundary conditions. It has been demonstrated that the absorption of lithium by silicon is energetically more favorable than the formation of a metal layer on the silicon surface. As the lithium concentration increases, the energy difference decreases; i.e., the introduction of lithium into silicon becomes increasingly less favorable, the network of silicon atoms is broken down into smaller and smaller pieces, while the layer thickness increases threefold.