Anamolously High Lithium Storage in Mesoporous Nanoparticulate Aggregation of Fe3+ Doped Anatase Titania

Implications of iron (Fe3+) doping on lithium insertion/de-insertion capacity of anatase TiO2 is discussed here. Iron doped anatase TiO2 mesoporous nanoparticulate aggregated at various Fe3+ doping concentrations was synthesized by an optimized sol-gel method. The electrochemistry and lithium storage capacities of anatase TiO2 exhibited strong function of dopant iron (Fe3+) concentration. A very high first discharge cycle capacity of 704 mAhg(-1) corresponding to approximately 2.1 mol of Li was observed for 5% iron (Fe3+) doped TiO2 at a current density of 75 mAg(-1). At the 30th discharge cycle, the capacity was remarkably high at 272 mAhg(-1) (0.81 mol of Li) with coulombic efficiency greater than 96%. Increase in the iron (Fe3+) concentration beyond 5% resulted in deterioration of lithium storage in TiO2. An improvement in lithium storage of more than 50% is noticed for 5% iron (Fe3+) doped TiO2 compared to pure anatase TiO2 which shows an initial discharge capacity of 279 mAhg(-1). The anomalous lithium storage behavior in all the iron (Fe3+) doped TiO2 samples has been accounted, in addition to homogeneous Li insertion in the octahedral sites, via local conversion reaction and heterogeneous interfacial storage at Fe and Li2O. (C) 2011 The Electrochemical Society. [DOI: 10.1149/2.029112jes] All rights reserved.