V a (V) porting information. In this work, the Hubbard correction is applied to all Fe-containing phases including the sulphides (similar to that in the Open Quantum Material Database 51 ). Although applying the U calibrated for oxide to sulphides may also introduce systematic errors, as the distance to hull are computed using the same set of competing phases, phases that are predicted to be close/on the convex hull should have stabilities similar to that of the Li 2 FeSO, which has been synthesised experimentally .