Synthesis and reversible lithium storage of Cr2O5 as a new high energy density cathode material for rechargeable lithium batteries

► Pure Cr2O5 is prepared by the thermal decomposition of CrO3 under ambient atmosphere at 350-400 °C. ► Reversible lithiation/de-lithiation of Cr2O5 proceeds via a single phase process. ► Cr2O5 electrode can reach a high energy density of 819 Wh kg−1 with good cyclability and high energy efficiency (83%).