Page 447 - Battery Reference Book

43/6 Electric vehicle secondary batteries
developing engineering-scale cells suitable for elec- are stable between 97 and loo%, while energy effi-
tric vehicle and utility load levelling applications. ciency remains in excess of 85%. Low maintenance,
These cells have yielded energy densities in excess of high charge rates and minimal thermal management
100Whkg and cycle life in excess of 1000 cycles. are characteristic of the system under a broad range of
Cells have been vibrated under road load condi- climatic conditions.
tions which simulate invehicle use with no problems Table 43.2 lists the program goals Eagle Picher have
encountered. defined for the lithium-metal sulphide system and the
In 1979 Eagle Picher used this type of battery to time frame for accomplishment.
power an electric van. A top speed of 45 milesh and Nearly all of the effort on the development of
a range of 80 miles were achieved. Figure 43.4 shows these batteries is now centred on traction applications
the single cell voltage profiles for typical FeS and FeSz for electric vehicles. Delivery vans, fork lift trucks
4 h rate discharges. and underground mining trucks are considered to be
Feasibility of the lithium-metal sulphide battery likely early uses - Westinghouse, Oceanic Division,
technology has been demonstrated by Eagle Picher Chardon, Ohio have had batteries tested at Argonne
in engineering-scale cells and modules. Figure 43.5 National Laboratory which have an estimated vehicle
shows a typical 10-cell module exhibiting a nominal range of 16Okm. SAFT America has been awarded
12 V e.m.f. curve and a capacity of 340 Ah. The com- a multi-million-dollar contract by the US Department
pact 12 V, 4k W h package has been cycled in the insu- of Energy to develop this type of battery. Other com-
lated battery container in excess of 250 deep discharge panies involved in programmes of work include Elec-
cycles as testing continues. Ampere hour efficiencies tro Fuel Co., Canada and Eagle Pitcher and Gould.

Table 43.2 Program goals: lithium-metal sulphide systems

1981 1983 1986 1988
Specific energy (W hkg)
Cell 95 120 150 200
Battery 70 100 130 160
Energy density (W NI)
Cell 320 400 525 650
Battery 100 200 300 375
Peak power (Wkg)
Cell 150 185 200 250
Battery 120 120 160 200
Battery heat loss (W) 300 150 125 120
Life
Deep discharges 250 500 1 000 1000
Equivalent miles 25 000 60 000 150000 200 000

1.5 -

1.0 - c -
0
>
0.5 - 0.5 -

I I I I
la) Capacity, state of charge (%I (b) Capacity, state of charge (%)
Figure 43.4 Lithium aluminium alloy-iron sulphide cells supplied by Eagle Picher. Typical single-cell voltage profiles for 4 h rate discharges
for (a) FeS and (b) FeSz cells (Courtesy of Eagle Picher)