Examining the Role of Anisotropic Morphology: Comparison of Free-Standing Magnetite Nanorods versus Spherical Magnetite Nanoparticles for Electrochemical Lithium-Ion Storage

Abstract

As a matter of synthetic novelty, Fe3O4 (magnetite) nanorods (NRs) have been successfully generated by using a reproducible four-step protocol, wherein goethite is initially produced, morphologically tuned, chemically treated with a passivating agent to reduce aggregation, and ultimately converted to magnetite by thermal annealing within a reductive atmosphere. Our equally important objective was in correlating electrochemical behavior with the unique morphology of these Fe3O4 anode materials. As such, both conventionally coated and binder-free electrodes were tested using as-prepared magnetite NRs and nanoparticles (NPs) with controlled crystallite size as the active materials. Our study revealed that both the NR and NP Fe3O4 materials were amenable to effective binder-free electrode design. For the conventionally coated electrodes, the NR electrodes demonstrated an improved rate capability using a sequential discharge/charge current density profile as compared with that for corresponding NP electrodes. Most significantly, within the cycling stability test, the NR electrode delivered a high and stable capacity with a superior capacity retention relative to that of the NP for more than 50 cycles in half cells and 100 cycles in full cells. These data in particular showcase the undeniable benefits of the anisotropic structure of the material.

Synthesis of Magnetite Nanorods from the Reduction of Iron Oxy-Hydroxide with Hydrazine

“…Iron oxide nanoparticles have been widely explored for numerous applications from magnetic storage devices − to gas sensors, , in water treatment, and broadly in biomedical applications. − Among the various shapes of magnetite (Fe 3 O 4 ) nanoparticles, anisotropic nanostructures such as wires and rods have drawn remarkable attention due to the considerable influence of the one-dimensional (1D) structure on their physicochemical properties. − For instance, the elongated Fe 3 O 4 nanostructures (nanowires and nanorods) have shown to be efficient as magnetic resonance imaging contrast agents, ,, exhibit enhanced heating efficiency, , have prolonged retention time at the tumor site, better performance in Li-ion batteries as an anode by accommodating the volume expansion of active materials, , and increased specific attachment to their target during drug delivery as compared to spherical nanoparticles . However, 1D Fe 3 O 4 nanoparticles are more challenging to synthesize because the surface energy favors the formation of isotropic spherical structures .…”

Mechanistic Investigations of Growth of Anisotropic Nanostructures in Reverse Micelles

“…Anisotropic nanoparticles synthesized through the RM method have been shown to exhibit numerous applications including in catalysis, energy storage, antibacterial agents, and biomedical applications like drug delivery and bioimaging. For example, anisotropic Fe 3 O 4 nanorods were developed for Li-ion storage, 114 Pd nanocubes nanoparticles were evaluated for their catalytic activity toward Suzuki coupling reactions, 115 rare earth-doped Gd 2 O 3 nanorods were synthesized and applied for magnetic resonance imaging, 116 PHEMA-g-(PAA-b-PEG) molecular bottlebrush (MBB) nanoparticles with different anisotropic morphologies were developed and applied for bioimaging and photothermal cancer therapy, 117 and anisotropic PNSAAc [poly(nisopropylacylamide-co-stearyl acrylateco-acrylic acid) (poly(NIPAM-co-SA-co-AAc))] and PNSAAm [poly(nisopropylacylamide-co-stearyl acrylate-co-allylamine) (poly(NIPAM-co-SA-co-AAm))] were nanostructures synthesized for drug delivery studies. 118 Although there are numerous literature reports on the synthesis and the application of 1D anisotropic nanostructures, there are just a handful among them that carry out mechanistic studies on the growth of these nanostructures and the most important of these were reviewed.…”

Scalable Fabrication of Carbon-Networked Size-Tunable V2O3 for Lithium Storage

“…Vanadium sesquioxide (V 2 O 3 ) has been investigated as a promising anode material candidate for lithium ion batteries, thanks to its high theoretical capacity (1070 mAh g –1 ), natural abundance, low cost, and low toxicity due to its low valence state of vanadium. − It is known that the V 2 O 3 stores lithium ions through an intercalation reaction followed by a conversion reaction, which accompanies 90% volume expansion . Although this volume change can be smaller in comparison with alloy-type electrode materials such as silicon (up to 300%), it generally causes interfacial stress inside the material particle, thereby resulting in pulverization, electrical disconnection, and capacity fading. − …”