Investigation of O3-type Na0.9Ni0.45MnxTi0.55-xO2 (0 ≤ x ≤ 0.55) as positive electrode materials for sodium-ion batteries

The Na0.9Ni0.45MnxTi0.55-xO2 (0 ≤ x ≤ 0.55) series of layered oxides was synthesized using a solid-state method and the materials in this series were studied as positive electrode materials in sodium cells. All compositions resided in a phase pure O3 solid solution. Compared to the Ti-free composition, Na0.9Ni0.45Mn0.4Ti0.15O2 has improved capacity retention without sacrificing reversible capacity and average voltage. Na0.9Ni0.45Mn0.4Ti0.15O2...