High-Performing Mesoporous Iron Oxalate Anodes for Lithium-Ion Batteries

Mesoporous iron oxalate (FeC2O4) with two distinct morphologies, i.e., cocoon and rod, has been synthesized via a simple, scalable chimie douce precipitation method. The solvent plays a key role in determining the morphology and microstructure of iron oxalate, which are studied by field-emission scanning electron microscopy and high-resolution transmission electron microscopy. Crystallographic characterization of the materials has been carried out by X-ray diffraction and confirmed phase-pure FeC2O4 center dot 2H(2)O formation. The critical dehydration process of FeC2O4 center dot 2H(2)O resulted in anhydrous FeC2O4, and its thermal properties are studied by thermogravimetric analysis. The electrochemical properties of anhydrous FeC2O4 in Li/FeC2O4 cells are evaluated by cyclic voltammetry, galvanostatic charge-discharge cycling, and electrochemical impedance spectroscopy. The studies showed that the initial discharge capacities of anhydrous FeC2O4 cocoons and rods are 1288 and 1326 mA h g(-1), respectively, at 1C rate. Anhydrous FeC2O4 cocoons exhibited stable capacity even at high C rates (11C). The electrochemical performance of anhydrous FeC2O4 is found to be greatly influenced by the number of accessible reaction sites, morphology, and size effects.