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

Chitosan‐linked Fe 3 O 4 ( CL ‐Fe 3 O 4 ) is facilely prepared by electrostatic interactions between citrate‐capped Fe 3 O 4 (C‐Fe 3 O 4 ) (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 ‐Fe 3 O 4 at 400°C leads to the formation of chitosan‐tethered iron oxide composites (Fe 2 O 3 @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 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, Fe 2 O 3 @chitosan (400°C) exhibits a higher retention capacity of 732 mAh/g than those (544 and 634 mAh/g) of chitosan‐free Fe 2 O 3 and Fe 2 O 3 @chitosan (700°C), respectively. The high performance of Fe 2 O 3 @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.