Biomedical Engineering Reference
In-Depth Information
8.7
TGA plot of the thermal stability of uncoated and alumina-coated
Fe nanoparticles at elevated temperatures in the presence of air (Hakim
et al
., 2007). Reproduced by permission of IOP Publishing.
8.4
Enhanced lithium-ion batteries using ultra-thin
ceramic films
Lithium ion (Li-ion) batteries are believed to be quite promising to store
energy for vehicles because of their high energy-to-weight ratios (Sun et al.,
2005, 2009; Carpenter et al., 2008). In order to employ Li-ion battery
technologies in next-generation hybrid electric and/or plug-in hybrid electric
vehicles (HEVs and PHEVs), these batteries must satisfy many require-
ments. Examples of the near-term needs that will help bring Li-ion battery
technologies to market include electrodes fabricated from inexpensive
environmentally benign materials with long lifetimes (near-term targets are
5000 charge-depleting cycles, 15-year calendar life), stability over a wide
temperature range (from
C), a high energy density, and a
high rate capability (Jung et al., 2010b). Current efforts include the
development of low-cost electrode materials, better electrolytes, and low-
cost packaging for such batteries. One effective path to cost reduction is to
improve power capability and extend battery life, thereby reducing the
overbuilding of Li-ion batteries while maintaining an energy density suitable
for transportation applications (Chen et al., 2010). Thin film coatings on Li-
ion battery electrode powders have proven to be an effective way to improve
the capacity retention, rate capability, and even the thermal stability of
cathode materials. Different coating materials have been studied, including
carbon (Chen and Dahn, 2002; Belharouak et al., 2005; Cao et al., 2007),
metal oxides (e.g. Al
2
O
3
,ZrO
2
, ZnO, SiO
2
, and TiO
2
) (Cho et al., 2001; Li
et al., 2006) and metal phosphates (e.g. AlPO
4
) (Cho et al., 2003).
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8
C to +66
8
