Parametric study of hydrothermal soft chemical synthesis and application of Na0.44MnO2 nanorods for Li-ion battery cathode materials: Synthesis conditions and electrochemical performance

摘要

In this paper, synthesis parameters were thoroughly investigated to understand and optimize the hydrothermal soft chemical synthesis of Na0.44MnO2 nanorods. Structural characterization reveals that a layered Na-birnessite precursor, a high NaOH concentration (15.0 mol/L) and a high hydrothermal reaction temperature (180 degrees C) are required for rapid formation of the tunnel Na0.44MnO2 phase. Additionally, the hydrothermal reaction time is greatly reduced to 8 h. More significantly, from electrochemical testing it is observed that the cycling stability and rate capability of Na0.44MnO2 electrode materials are enhanced after the addition of carbon nanotubes. The capacity retention increases from 70% to 82% at 0.1 A/g after 50 cycles, and the Li storage capacity at a high rate of 2.0 A/g increases from 45 mAh/g to 99 mAh/g. The parameters are optimized for fast, high-yield and large-scale production of high performance Na0.44MnO2 nanorod cathode materials used in lithium-ion batteries. (C) 2015 Elsevier B.V. All rights reserved.