Ultra-long nanorods of single-crystalline Na_0.44MnO₂ as cathode materials for sodium-ion batteries

Rechargeable batteries composed of low-cost and abundant materials operating at room temperature are attractive for grid-scale energy storage application Sodium-ion battery is thought of as an ideal candidate for secondary battery. Hence, ultra-long nanorods of single-crystalline Na_0.44MnO₂ have been synthesized by co-precipitation method followed by high-temperature calcination. The obtained powder is pure phase with an orthorhombic lattice structure and the morphology is regular. Their electrochemical properties were thoroughly investigated in assembled Sodium-ion cells using cyclic voltammetry, galvanostatic testing, and electrochemical impedance spectroscopy. With applying the as-prepared Na_0.44MnO₂ as a cathode material for sodium-ion batteries, it exhibits a high reversible initial capacity of 94.1 mAh g^-1 in a voltage range of 2.0-4.0 V vs. Na⁺/Na at a current density of 50 mA g^-1, and a satisfactory cyclability of 93.3% capacity rentention after 200 cycles is performed in our work. The single-crystalline Na_0.44MnO₂ with an excellent electrochemical performance proves that it is a potential cathode material for sodium-ion battery.