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

Abstract

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. Inertatmosphere 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 @chi-tosan (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.

Calcination Temperature Effect on Citrate‐Capped Iron Oxide Nanoparticles as Lithium‐Storage Anode Materials

“…The TEM image (Figure e) of C‐Fe 2 O 3 (700 °C) shows the larger particle size (≈100–200 nm), mainly attributed to the significant sintering of iron oxide particles at high calcination temperature. The corresponding selected area electron diffraction (SAED) pattern (inset of Figure e) shows the distinct diffraction spots which indicate a perfect single crystalline diffraction . In the HR‐TEM image of Figure f, there exist clearly lattice fringes confirming that the C‐Fe 2 O 3 (700 °C) is highly crystalline structure.…”

“…In the second cycle, the reduction peak at 0.6 V shifts to 0.8 V because of the electrode polarization in the first cycle. The intensity of peak drops significantly in the subsequent, indicative of some irreversible reactions with the formation of solid electrolyte interphase (SEI) film…”

GeTe-TiC-C Composite Anodes for Li-Ion Storage

“…Despite these advantages, Ge anodes face a major disadvantage pertaining to poor cycling because of the 300% volume variation during repeated electrochemical process [ 23 , 24 ]. In this regard, effectual strategies are needed to provide structural stability for the composites by generating effective buffer phases and preventing nanoparticle agglomerations [ 8 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 ]. Among these, titanium carbide (TiC) could be used to fabricate an outstanding structural barrier, with its high conductivity and hardness [ 31 , 32 ].…”

“…Due to the specific properties of TiC, various studies on the electrodes with TiC and/or C have been explored, where the addition of TiC to the composite electrodes made it possible to show stable cyclic performances [ 23 , 33 , 34 , 35 , 36 , 37 ]. In addition, conductive carbon can enhance nanoparticle separation and the conductivity of composites, and it can also stabilize electrochemical performances for LIBs [ 24 , 28 , 38 ]. Meanwhile, for reducing the large volume expansion of the metallic Ge, intermetallic components that act as a buffering step could be incorporated into composite electrodes.…”

Tailoring carboxyl tubular carbon nanofibers/MnO2 composites for high‐performance lithium‐ion battery anodes

“…Some reports on improving the performance of alloy anodes are Si@C@PC, 9 Si/C 10 and SnS 2 /B 11 . Transition metal oxides (TMOs) and mixed metal oxides based on conversion reaction mechanism, including MoS 2 , 12 Fe 2 O 3 , 13 and Cu‐Ni oxide 14 have become expected alternative anode materials due to their environment‐friendliness and abundant reserves. Among all the TMOs, MnO 2 has shown its great potential as an energy storage and conversion material 15,16 .…”