Biomedical Engineering Reference
In-Depth Information
microspheres,
as shown in Fig. 6.3a,b [63]. The self-assembled
V
hollow microspheres with uniform hedgehog-like morphology
have desirable electrochemical properties such as high capacity
and remarkable cycle reversibility. It should be noted that V
O
5
2
is
not a cathode material for traditional lithium-ion batteries but a
promising cathode material for lithium-based batteries with lithium-
containing anodes.
O
2
5
Figure 6.3
hollow microspheres.
Inset gives a high magnification transmission electron microscopy (TEM)
image of a V
(a) TEM image of the as-prepared V
O
2
5
microsphere and a HRTEM picture taken from the edge of
a nanorod surface. (b) Sketch of V
O
2
5
hollow microspheres (all reproduced
with permission from [63],
copyright 2005, Wiley-VCH Verlag GmbH &
Co. KGaA).
O
2
5
Another example in this context is the tin nanoparticles
encapsulated hollow carbon spheres (TNHCs), with a uniform
size (ca. 500 nm), in which several tin nanoparticles (diameter
ca. 100 nm) are encapsulated in one hollow carbon sphere
(thickness ca. 20 nm), as shown in Fig. 6.5a,b [30]. With SiO
2
spheres (ca. 400 nm) and Na
SnO
as the starting materials, SnO
2
2
3
coated SiO
spheres can be synthesized; then after a etching step
by NaOH, followed by the treatment with glucose at 190°C, SnO
2
/C
double shell sphere is obtained, and the final products can be
prepared after the heat treatment in the Nitrogen atmosphere at
700°C. In the composite microspheres, the content of Sn is up to
74 wt%, which provides a high theoretical specific capacity (up to
831 mAh g
2
), and the volume ratio of the Sn nanoparticles and the
void space encapsulated is about 1:3, which can accommodate the
volume expansion during the lithiation process (it can be seen in
-
1
Search WWH ::
Custom Search