Structure analyses of Fe-substituted Li2S-based positive electrode materials for Li-S batteries

The structure of Fe-substituted Li2S-based positive electrode material Li8FeS5 was analyzed using high-energy Xray total scattering measurements. Pair distribution function (PDF) analyses indicated that the mechanically milled Li8FeS5 sample could best be described as having an anti-fluorite structure in which Fe ions partially occupy Li sites in the Fm (3) over barm unit cell. The electrochemical properties of a cell utilizing Li8FeS5 as the positive electrode were also consistent with this structural model.