Titanium-Substituted Na0.44MnO2 Nanorods as Cathode Materials for High Performance Sodium-Ion Batteries

A series of titanium-substituted manganese oxides, Na0.44TixMn1-xO2 (x = 0.11, 0.22, 0.33, and 0.44) with the Na0.44MnO2 were prepared by sol-gel methods. The electrochemical characteristics of these compounds, which are different from Na0.44MnO2, were examined in coin-type cells with NaPF6 electrolyte. While the Na0.44Ti0.11Mn0.89O2 and Na0.44Ti0.44Mn0.56O2 delivered lower capacities, the Na0.44Ti0.22Mn0.78O2 showed higher capacities, about 120 mAh g(-1). The Ti-substituted materials exhibited excellent capacity retention over one hundred or more cycles, with 71.8% capacity retention over 450 cycles. Titanium substitution eliminates Mn dissolution. (C) 2015 The Electrochemical Society.