Preparation of Hollow Fe2O3 Nanorods and Nanospheres by Nanoscale Kirkendall Diffusion, and Their Electrochemical Properties for Use in Lithium-Ion Batteries

Abstract

A novel process for the preparation of aggregate-free metal oxide nanopowders with spherical (0D) and non-spherical (1D) hollow nanostructures was introduced. Carbon nanofibers embedded with iron selenide (FeSe) nanopowders with various nanostructures are prepared via the selenization of electrospun nanofibers. Ostwald ripening occurs during the selenization process, resulting in the formation of a FeSe-C composite nanofiber exhibiting a hierarchical structure. These nanofibers transform into aggregate-free hollow Fe2O3 powders via the complete oxidation of FeSe and combustion of carbon. Indeed, the zero- (0D) and one-dimensional (1D) FeSe nanocrystals transform into the hollow-structured Fe2O3 nanopowders via a nanoscale Kirkendall diffusion process, thus conserving their overall morphology. The discharge capacities for the 1000th cycle of the hollow-structured Fe2O3 nanopowders obtained from the FeSe-C composite nanofibers prepared at selenization temperatures of 500, 800, and 1000 °C at a current density of 1 A g−1 are 932, 767, and 544 mA h g−1, respectively; and their capacity retentions from the second cycle are 88, 92, and 78%, respectively. The high structural stabilities of these hollow Fe2O3 nanopowders during repeated lithium insertion/desertion processes result in superior lithium-ion storage performances.

A Review of Recent Advancements in Electrospun Anode Materials to Improve Rechargeable Lithium Battery Performance

“…Hollow nanostructured transition metal oxide anode materials and their corresponding electrochemical performances are presented in Figure 9 . Hollow Fe 2 O 3 nanorods and nanospheres in Figure 9 a were synthesized via selenization of a precursor nanofiber and a subsequent oxidation reaction [ 125 ]. The hollow nanorod exhibited typical CVs of Fe 2 O 3 and the following electrochemical reactions: (i) lithium insertion at around 1.6 and 1V to form Li 2 Fe 2 O 3 (cubic), the complete reduction of iron to Fe 0 , and Li 2 O formation/SEI formation at around 0.7 V during the first cathodic scan; (ii) the oxidation of iron from Fe 0 to Fe 2+ at 1.7 V and Fe 3+ at 1.85 V during anodic scans; and (iii) the reduction of iron from Fe 3+ to Fe 0 at around 0.8 V during the following cathodic scans [ 120 , 126 ].…”

“… Schematic illustrations of hollow nanostructured transition metal oxide anode materials and corresponding electrochemical performances. ( a ) Fe 2 O 3 nanostructures (reprinted with permission from [ 125 ]; copyright 2016 Springer Nature), ( b ) hollow Co 3 O 4 nanostructure (reprinted with permission from [ 127 ]; copyright 2019 Royal Society of Chemistry), and ( c ) hollow NiO nanofiber (reprinted with permission from [ 130 ]; copyright 2019 Elsevier). …”

Double-walled iron oxide nanotubes via selective chemical etching and Kirkendall process

“…Various α-Fe 2 O 3 nanostructures with different morphologies such as nanoparticles 8,12 , nanowires (NWs) 13,14 and nanotubes (NTs) 15,16 have already been successfully synthesized. Additionally, several works reported, recently, the synthesis of hollow iron oxide nanoparticles through the Kirkendall effect 13–17 .…”

“…Given that fundamental properties of materials can be tuned through morphology and size, precise structure control is of utmost importance 18,19 . For example, nanostructured α-Fe 2 O 3 has been studied as an anode material for lithium ion batteries for its high capacitance and it was demonstrated that higher porosity is advantageous over repetitive cycling 15 ; this way a nanotube would provide better results than a nanorod, for example. Also, quantum confinement in very thin nanostructures, such as nanotubes with extremely thin walls, can be used to tune the band edges and band gap of a semiconductor for photoelectrochemical applications 19 .…”

Processing Iron Oxide Nanoparticle-Loaded Composite Carbon Fiber and the Photosensitivity Characterization

“…The lithium ion battery anode made from the fibers showed improved cycling performance and rate capability. There are many other researchers who reported their work on this application [2][3][4][5][6][7]. For example, in the work performed by Xu et al [4], iron oxide/carbon nanofibers (FeOx/CNFs) were prepared by electrospinning the FeCl 3 •6H 2 O-polyacrylonitrile (PAN) precursors and heat treating at different temperatures.…”