Environmental Engineering Reference
In-Depth Information
NiMH batteries, made by SAFT of France its Electric Powered Interurban
Commuter (EPIC) vans, adding 30 miles to their range.
Other battery technologies include sodium-sulfur which was used
in early Ford EVs, and zinc-air. Zinc appeared in GM's failed Electrovette
EV in the late 1970s. Zinc-air batteries have been promoted by a number
of companies, including Israel's Electric Fuel, Ltd. Zinc is inexpensive and
these batteries have six times the energy density of lead-acid. A car with
zinc-air batteries could deliver a 400 mile range, but the German postal
service found that these batteries cannot be conventionally recharged.
The EFTC zinc-air battery system for electric vehicles uses a dis-
charge-only zinc-air module with the exchange of batteries and zinc an-
ode regeneration for battery recycling. A Zinc-Air Module is built from
cells with replaceable zinc anode cassettes. There are 47 cells with an open
circuit voltage of 67V and an operating voltage of 57-40V. The system has
a battery capacity of 325 amp-hours and an energy capacity of 17.4-kWh
with a peak power of 8-kW. The weight is 88-kg with an energy density of
200-Wh/kg and dimensions of 726x350x310 mm.
The cell uses a replaceable anode cassette made up of a slurry of elec-
trochemically generated zinc particles in a potassium hydroxide solution
with a collection frame and a separator envelope with two sides of oxygen
reduction cathodes that extract oxygen from the air for the zinc-oxidation
reaction. The discharged zinc-air module is refueled or mechanically re-
charged by exchanging spent cassettes with fresh cassettes.
Other battery types include lithium-ion, which is used in a variety
of consumer products. Lithium batteries could offer high energy den-
sity, long cycle life, and the ability to work in different temperatures.
However, like the sodium-sulfur batteries in the Ford Ecostar, lithium-
ion presents a fire hazard since lithium itself is reactive. Plastic lithium
batteries could prove to be very versatile. Bellcore is working on a lithi-
um battery that is thin and bendable like a credit card for laptop comput-
ers and cell phones. Each cell is only a millimeter thick. The plastic bat-
teries are lightweight and have been tested for automotive applications.
Canadian utility Hydro-Quebec has been working with 3M on a lithium-
polymer unit which may be the first dry electric vehicle battery. Like the
Bellcore product, this dry battery uses a sheet of polymer plastic in place
of a liquid electrolyte. Also working on this technology is a team at John
Hopkins University. This is also a plastic battery that can be formed into
thin, bendable sheets. These batteries also contain no dangerous heavy
metals and are easily recycled.
Search WWH ::
Custom Search