Superior cyclability of Ce-doped P2–Na0.67Co0.20Mn0.80O2 cathode for sodium storage

P2–Na0.67Co0.20Mn0.79Ce0.01O2 (NCMC) was synthesized through Mn-site Ce-doping by solid-state method. The X-ray diffraction displays that P2-type structure of the pristine oxide with the space group of P63/mmc has not been changed by Ce-doping. XRD refinements and X-ray photoelectron spectroscopy analysis shows that cerium ions enter the lattice of the pristine oxide. The capacity retention rates of NCMC cathode are 92.3% at 0.1C after 100 cycles and 91.7% at 1C after 400 cycles, respectively. NCMC cathode exhibits superior cyclability. This is mainly attributed to the improved structural stability and the widened layer spacing of the pristine oxide and the relieved Jahn-Teller effect and highly reversible P2–P3–P2 phase transition during charge and discharge. This study is of great significance for the practical application of P2-type oxide. •Ce ions have successfully doped into the Mn-sites in the pristine lattice.•Structure stability is significantly improved by the Ce-doping.•The doped P2 oxide cathode presents superior cyclability.•Ex-situ XRD patterns reveal highly reversible P2–P3–P2 phase transition.