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

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°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°C to 700°C, the size of primary particles increases from ca. 40 nm to ca. 100 nm, and the surface area decreases from 57.8 m2/g to 10.9 m2/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°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°C), respectively. The high performance of Fe2O3@chitosan (400°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.