The b-tagging performance expected for ATLAS Run-II will be presented hereafter. These studies are based on Monte-Carlo simulations of tt¯ events. These results enable to quantify the impact of both the installation of a new pixel layer and the repairs of several electronics components of the actual pixel detector on the b-tagging performance. Beforehand, a brief description of the ATLAS experiment at LHC and of the b-tagging algorithms will be developed.