Employment of Chitosan-linked Iron Oxides as Mesoporous Anode Materials for Improved Lithium-ion Batteries

This study investigates the concentration effect of chitosan on the formation of iron oxide composites and their electrochemical performance as anode materials in Li-ion batteries. The molecular bridging effect of chitosan chains induces the clustered aggregation of citrate-capped Fe3O4 (C-Fe3O4) through the electrostatic interactions between carboxylate groups of C-Fe3O4 and amine groups of chitosan. The thermal calcination of chitosan-linked Fe3O4 leads to carbon-coated Fe2O3 (Fe2O3@carbon) with the mesopore range of porosity (20-30 nm). The mesoporous Fe2O3@carbon exhibits an improved electrochemical performance as anode materials in Li-ion batteries. The capacity retention of Fe2O3@carbon is twice that of bare Fe2O3 after the 50th cycle at 0.1 C. During the charge-discharge process, the Fe2O3@carbon (3 ml of chitosan) exhibits the highest retention capacity among as-prepared samples, whereas Fe2O3@carbon (1 ml of chitosan) exhibits the lowest retention capacity owing to the weakly cross-linked iron oxides. The improved performance of Fe2O3@carbon as anode materials is mainly attributed to the optimal cross-linking effect and structural integrity of mesoporous composite which is beneficial for the effective transport of electrolytes and/or Li-ons, suggesting a useful guideline for preparing porous electrode materials using metal oxide particles. (C) 2015 Elsevier Ltd. All rights reserved.