Bimetallic Sulfates A2M(SO4)2.nH2O (A = Li, Na and M = Transition Metal): as New Attractive Electrode Materials for Li- and Na-Ion Batteries

Abstract

Developing the next generations of Li- and Na-ion batteries relies on designing new sustainable, low-cost and safe electrode materials. In such an attempt, we investigated several series of bimetallic sulfates, among them we identified Na2Fe(SO4)2·4H2O, Na2Fe(SO4)2 and Li2Fe(SO4)2, which present attractive electrochemical properties against both lithium and sodium. With a potential of 3.83 V vs. Li+/Li0, the new lithium iron sulfate Li2Fe(SO4)2 displays indeed the highest potential ever obtained for the Fe3+/Fe2+ redox couple in an iron-based fluorine-free compound.