Synthesis and electrochemical properties of P2-Na2/3[Ni1/3Mn2/3]O2 microspheres as cathode materials for sodium-ion batteries

Abstract P2–Na2/3 [Ni1/3Mn2/3]O2 microspheres with well-distributed particle size and high tapping density have been successfully prepared via a hydroxide co-precipitation route associated with the solid-state reaction. The as-prepared P2–Na2/3 [Ni1/3Mn2/3]O2 sample has a high tapping density of 2.23 g cm−3 and hexagonal morphology indexed to P63/mmc space group. At the same time, it consists of monodisperse microspheres with a diameter of 5–8 μm, which are closely assembled by many plate-like primary nanoparticles. As cathode material for sodium-ion batteries (abbreviated as SIBs), it exhibits a high initial capacity of 87.8 mAh g−1 at 0.1 C in the voltage window of 2.3–4.1 V and demonstrates excellent capacity retention of 97.5% after 100 cycles. Therefore, P2–Na2/3 [Ni1/3Mn2/3]O2 microspheres will be a hopeful cathode material for the application of sodium-ion batteries.