Synthesis of a novel tunnel Na0.5K0.1MnO2 composite as a cathode for sodium ion batteries

Abstract

A novel tunnel Na_0.5K_0.1MnO₂ composite assembled by two different tunnel structures of Na_0.44MnO₂ and KMn₈O₁₆ is synthesized by a co-precipitation method. Bundles of microrods and small nanorods could be observed in the Na_0.5K_0.1MnO₂ composite. The composite possesses high crystallinity and large stacking faults. When used as a cathode for sodium ion batteries, the composite exhibits a high specific capacity, excellent cyclability and superior rate capability. A high reversible discharge capacity of 142.3 mA h g⁻¹ could be delivered at 0.1C, with 94.7 mA h g⁻¹ retained after 100 cycles. Also 82.2 mA h g⁻¹ could be maintained after 300 cycles at 1.0C. More than 70 mA h g⁻¹ could be obtained at a high rate of 4.0C. The outstanding electrochemical performances may be attributed to the combined tunnel structures, one-dimensional rod-like morphology and massive structural stacking faults.