Cationically Substituted BiFeOCl Nanosheets as Li Ion Battery Anodes.

Cation substitution of Bi with Fe in BiOCl leads to the formation of ionically layered BiFeOCl nanosheets. The synthesis follows a hydrolysis route using bismuth(III) nitrate and iron(III) chloride, followed by postannealing at 500 °C. Room temperature electrical conductivity improves from 6.11 × 10 S/m for BiOCl to 6.80 × 10 S/m for BiFeOCl. Correspondingly, the activation energy for electrical conduction reduces from 862 meV for pure BiOCl to 310 meV for BiFeOCl. These data suggest improved charge mobility in BiFeOCl nanosheets. Density functional theory calculations confirm this behavior by predicting a high density of states near the Fermi level for BiFeOCl. The improvement in electrical conductivity is exploited in the electrochemical performance of BiFeOCl nanosheets. The insertion capacity of Li ions shows an increase of 2.5×, from 215 mAh·.g for undoped BiOCl to 542 mAh·g for BiFeOCl after 50 cycles at a current density of 50 mA·g. Thus, the direct substitution of Bi sites with Fe in BiOCl results in nanosheets of an ionically layered ternary semiconductor compound which is attractive for Li ion battery anode applications.