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Considerations for Nanomaterials in Lithium Rechargeable Batteries
Commercialization
While many people speak glowingly of the potential
in nanomaterials, battery applications to this
point are scarce, akin to having a cure for which
there is no known disease. The sticking point
is low production volume, which means high material
costs, a feature definitely not compatible with
consumer batteries. This includes cells for mobile
devices and automotive usage. Looking outward,
this fledgling industry would greatly benefit
from an engineering breakthrough boosting process
capacity an order of magnitude, to 20-50 kg/hour
per unit. Scaling up hardware such as plasma sprayers
or spray pyrolyzers is extremely difficult, however.
Considering the market dynamics of battery nanomaterials,
there are niches amenable to high value-added,
low volume products. Dr. Ben Chaloner-Gill, a
California nanomaterials veteran, argues that
new technologies must provide a needed performance
enhancement to be successful. Such advances are
application-dependent: economies of scale follow
proven results. Three niche battery markets that
meet these criteria are medical appliances, aerospace,
and printed circuit boards.
In the first two instances, the cost of reliability
is so high that the impact of expensive materials
is negligible. This attribute has not escaped
Wilson Greatbatch Technologies, a leading manufacturer
of implantable medical devices. Earlier this year,
Greatbatch made the astute acquisition of Nanogram
Devices, for the express purpose of developing
new battery products. This merger of complementary
technologies may well be a precursor to similar
partnerships of nanotechnology with medical and
aerospace companies.
Batteries for microelectronics may also benefit
from nanomaterials, which would compete with thin
film batteries (pioneered by John Bates and co-workers
at Oak Ridge). Micron-sized particles are too
large for electrodes in these cells, but nanopowders
are compatible. Millions of such batteries may
be required annually, but with micrograms of materials
per electrode, total powder production would still
be small by today’s industry standards.
US Nanocorp, led by Dr. David Reisner and featured
in a 21 June Forbes article, typifies small, research-oriented
nanomaterial companies. US Nanocorp derives most
of its income from government research contracts,
and is actively pursuing industrial clients for
their technology. Still, it is a challenge for
US Nanocorp to meet its payroll on time, and clearly,
the best is yet to come.
Conclusions
Nanotechnology, like an infant, requires much
care and attention (read: development), and has
unlimited potential. Intercalation materials for
lithium rechargeable batteries are certainly on
the hot list for nanotech research groups. Nano-particulate
cathode species such as LiCoO2 (and analogs) may
provide near-theoretical capacities, while olivines
and new layered LiMnNi oxides may benefit by enhanced
rate capabilities. Anode nanomaterials could offer
relief from the crushing capacity hysteresis that
plagues micron-sized metal oxides and cermets,
by reducing or eliminating irreversible Li+ retention.
The greatest challenge for battery nanomaterials
likely will be in electrode processing. High surface
area powders create elevated, hard-to-control
coating slurry viscosities, just the opposite
of what’s needed. Further, low density nanoparticles
will prevent packing sufficient active ingredients
into a fixed-volume cell to meet present energy
specifications. These limitations, plus the relatively
high cost of nanopowders, strongly suggest that
the near future for battery nanomaterials lies
in niche markets such as aerospace, micro-electronics,
and medical applications.
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