The spherical pyrite FeS2 was synthesized through a green and simple method with the addition of the polyvinylpyrrolidone (PVP) dispersant. The as-prepared FeS2 displays a good electrochemical performance with an initial specific capacity over 80% of the theoretical value and a very low decay rate of 0.33% per cycle (calculated from 2nd to 50th at 0.1 C). Rate capability testing exhibits discharge capacities of around 371.6 mAh/g (0.1 C), 343 mAh/g (0.2 C), 294.9 mAh/g (0.5 C), 239 mAh/g (1 C) and 161.8 mAh/g (2 C) respectively. Besides, coulombic efficiency close to 100% at various rates can also be obtained. We calculate Li+ diffusion coefficient and multi electron feature of the pyrite FeS2 during charge/discharge process. It shows that smaller potential window is beneficial for cyclability, which was in good agreement with experimental results. (C) 2016 Elsevier B.V. All rights reserved.