α-Fe₂O₃ Nanostructures: Inorganic Salt-Controlled Synthesis and Their Electrochemical Performance toward Lithium Storage

Abstract

By applying the concept of an inorganic structure-directing agent, uniform R-Fe 2 O 3 nanospheres of about 300 nm in diameter and well-defined nanorhombohedra of about 50-80 nm in size have been successfully synthesized using the simple inorganic sodium salt of NaAc and NaCl as the only structure-directing agent in the hydrothermal system, respectively. In comparison, only micrometer sphere-like aggregates composed of irregular nanoparticles of about 80-120 nm were obtained without the presence of any inorganic salt additives. All three nanostructures are investigated with XRD, SEM, TEM, and electrochemical tests toward lithium storage. It is found that the particle size and shape has a remarkable effect on the lithium insertion/ extraction behavior. Among the three R-Fe 2 O 3 nanostructures, nanospheres show a very high specific capacity of >600 mA h g -1 in the initial 10 cycles and >414 mA h g -1 after 60 cycles as well as good cycling performance, exhibiting great potential as anode materials in lithium-ion batteries. It benefits from the proper submicrometer size with the right surface area and the spherical shape.

MgFe2O4/reduced graphene oxide composites as high-performance anode materials for sodium ion batteries

“…In the first cathodic scan, an irreversible peak is observed at around 0.75 V, which is ascribed to the formation of SEI film on the surface of electrode [40,41]. In the subsequence cycles, the cathodic peak at 0.55 V can be attributed to the reduction of Fe 3+ to Fe 0 and the formation of amorphous Na 2 O and MgO, which is similar to the processes reported in LIBs [16,19,42,43]. In addition, the sharp cathodic peaks appearing in low potential region from 0.01 to 0.2 V can be attributed to the insertion of Na ions in RGO [11,44].…”

Fe3O4C open hollow sphere assembled by nanocrystals and its application in lithium ion battery

“…As reported in Refs. [28,29], the initial discharge capacity calculated on the basis of the whole mass of both samples exceed the theoretical capacity of Fe 3 O 4 (928 mAh g −1 ), which is usually ascribed to the formation of a polymeric gel-like film and possibly interfacial lithium storage.…”

Electrospun Hierarchical CaCo2O4 Nanofibers with Excellent Lithium Storage Properties

“…The broad peak centered at about 1.36 V may be attributed www.chemeurj.org to a small amount of Li + inserted into the structure of CaCo 2 O 4 before the subsequent destruction of the crystal structure, which is very common in other metal oxides. [35,42] The intense reduction peak located at about 0.84 V can be assigned to the reaction of CaCo 2 O 4 with lithium to yield a composite of Co, Li 2 O, and CaO. In addition, two broad oxidation peaks are observed at 1.41 and 1.92 V in the following anodic scan, corresponding to the formation of CoO and the regeneration of Co 3 O 4 , respectively.…”