We designed a new green and simple process to synthesize spherical pyrite FeS₂ with the help of 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).

Calculation for Li⁺ diffusion coefficient of the pyrite FeS₂ in different potential window showed that smaller potential window is benefit for cyclability.