2 research outputs found
Silicon/Hollow γ‑Fe<sub>2</sub>O<sub>3</sub> Nanoparticles as Efficient Anodes for Li-Ion Batteries
Nanomaterials
have triggered a lot of attention as potential triggers
for a technological breakthrough in Energy Storage Devices and specifically
Li-ion batteries. Herein, we report the original synthesis of well-defined
silicon/iron oxide nanoparticles and its application as anode materials
for Li-ion batteries. This model compound is based on earth abundant
elements and allows for a full investigation of the electrochemical
reactions through its iron oxide magnetic phase. The elaboration of
silicon with iron oxide grown on its surface has been achieved by
reacting an organometallic precursor FeÂ(CO)<sub>5</sub> with Si nanopowder
and subsequent slow oxidation step in air yields hollow γ-Fe<sub>2</sub>O<sub>3</sub> on the Si surface. This specific morphology
results in an enhancement of the specific capacity from 2000 mAh/g<sub>Si</sub> up to 2600 mAh/g<sub>Si</sub>. Such a high specific capacity
is achieved only for hollow γ-Fe<sub>2</sub>O<sub>3</sub> and
demonstrates a novel approach toward the modification of electrode
materials with an earth abundant transition metal like iron. This
result further emphasizes the need for precisely designed nanoparticles
in achieving significant progress in energy storage
Synthesis of Carbon Nanotubes Networks Grown on Silicon Nanoparticles as Li-Ion Anodes
Using
chemical vapor deposition, we grew carbon nanotubes (CNTs)
on the surface of Si nanoparticles (NPs) that were coated with a thin
iron shell. We studied the CNT growth mechanisms and analyzed the
influence of (1) varying annealing times and (2) varying growth times.
We show that an initial annealing is necessary to reduce the iron
oxide shell and to start the formation of Fe NPs and their consequent
coarsening. We characterize the evolution of the catalyst morphology
and its influence of the morphology and structure of the CNTs grown.
We studied this nanocomposite of Si NPs interconnected by CNTs grown
on them as anode material for Li-ion batteries. Compared to the pristine
Si NPs, the Si-CNT nanocomposite brings an increase of 40% in specific
capacity after 100 cycles at 1800 mA/g<sub>Si</sub> with a high stability
and a very low capacity loss per cycle of 0.06%. The electrochemical
performance demonstrates how efficient the CNT shell on the Si NP
is to mitigate the usual failure mechanism of Si NPs. Thus, the in
situ growth of CNTs on Si anode materials can be an efficient route
toward the synthesis of more stable Si anode composites for a Li-ion
battery