Lithiummetal is a desired material for anodes of lithiumion batteries because of its large theoretical specific capacity of 3,860 mAh/g, the highest known so far. Unfortunately, there are several problems that restrict the practical application of lithiummetal anodes, like the formation of dendrites among others. Li-metal batteries based on solid electrolyte materials are expected to be the next-generation battery with high energy density and enhanced cycle life, however, one of the key limitations is the poor knowledge about the solid electrolyte-electrode interfaces. In this work, first-principles calculations are performed to investigate the electrochemical stability of the interface between a lithium-metal anode and sulfide solid electrolytes. Ab initio molecular dynamics simulations reveal the formation of solid electrolyte interphase. Sulfide-based materials mixed with halogens are candidates for solid state electrolytes in advanced lithium batteries. They are expected to have high ionic conductivity and electrochemical stability against Li-metal. Analyzing the interface with Li-metal through ab initio molecular dynamics simulations, it is found that the sulfide is unstable, forming Li2S but it may passivate the surface of the anode. This decomposition of groups against Li-metal form Li-S bonds, despite the higher P-S bond energy. We include here a study of lithium dendrite formation on a Limetal anode covered by a cracked solid electrolyte interface of LiF with a typical liquid electrolyte using classical molecular dynamics on a model nanobattery. We tested a few protocols of charge the nanobattery. We found that the mere presence of a crack in the SEI boosts and guides dendrite formation.