First principles studies of silicon as a negative electrode material for lithium-ion batteries

An investigation of Li-Si alloys using density functional theory is presented. Various calculation methods and pseudopotentials are analyzed to best reproduce the potential versus composition curve of a Li/LixSi electrochemical cell at high temperature using the experimentally observed Li-Si phases. Total energy calculations, structural optimizations, and bulk modulus estimations were completed for the Si, Li12Si7, Li7Si3, Li13Si4, Li15Si4, Li22Si5, and Li phases. The potential plateaus of the co-existing phase regions, obtained using the projector augmented wave (PAW) method, have an average absolute error of 31 mV with respect to experiment. The Li7Si3 and Li15Si4 compositions are discussed and the Li15Si4 phase is found