Electrode potential and activation energy of sodium transition-metal oxides as cathode materials for sodium batteries: A first-principles investigation

Recently, researches on sodium (Na) batteries get resurrected for large-scale applications under the background of limited lithium (Li) resource. Four layered sodium transition-metal (TM) oxides, NaMO2 (M = V, Cr, Co and Ni) with alpha-NaFeO2 type as potential cathode materials for sodium batteries, are systematically investigated by first-principles calculations. As two key properties for a successful cathode material, the electrode potential and activation energy (EA) of Na+ in their parent NaMO2 crystals (M = V, Cr, Co and Ni) are reported. Our results suggest that NaCrO2, NaCoO2 and NaNiO2 possess satisfying average electrode potential (AEP) and their potential platforms are close to that of LiCoO2 to a large extent. Meanwhile, EA of these materials are all acceptable for batteries. These first-principles results suggest that layered NaCrO2, NaCoO2 and NaNiO2 are viable candidates for large-scale applications. (C) 2015 Elsevier B.V. All rights reserved.