Chitosan-Tethered Iron Oxide Composites as an Antisintering Porous Structure for High-Performance Li-Ion Battery Anodes

Abstract

Chitosan-linked Fe3O4 (CL-Fe3O4) is facilely prepared by electrostatic interactions between citrate-capped Fe3O4 (C-Fe3O4) (with negatively charged carboxylate groups) and chitosan oligosaccharide lactate (with positively charged amine groups), and utilized as anodes for lithium-ion batteries. Inert-atmosphere calcination of CL-Fe3O4 at 400 degrees C leads to the formation of chitosan-tethered iron oxide composites (Fe2O3@chitosan) with an antisintering porous structure. As the calcination temperature changes from 400 degrees C to 700 degrees C, the size of primary particles increases from ca. 40 nm to ca. 100 nm, and the surface area decreases from 57.8 m(2)/g to 10.9 m(2)/g. The iron oxide composites exhibit a high discharge capacity and good rate performance. At a current density of 0.1 C after 50 cycles, Fe2O3@chitosan (400 degrees C) exhibits a higher retention capacity of 732 mAh/g than those (544 and 634 mAh/g) of chitosan-free Fe2O3 and Fe2O3@ chitosan (700 degrees C), respectively. The high performance of Fe2O3@ chitosan (400 degrees C) is attributed to the antisintering porous structure with high surface area that is beneficial for facilitating ion transport, demonstrating a useful chemical strategy for the direct formation of porous electrode materials at low calcination temperature.