Page 285 - Handbook of Battery Materials

9.3 Metal Hydride–Nickel Batteries 255

P-C isotherms for La 1-x Ce x Ni 3.55 Co .75 Mn .4 Al .3 -H system
40

35 x = 0, 323 K
x = 0.2, 323 K
30
x = 0.35, 313 K
x = 0.5, 313 K
25
x = 0.75, 303 K
P eq ,atm 20 x = 1.0, 303 K
15

10
5
0
-5
0 1 2 3 4 5 6 7
H/FORMULA UNIT

Figure 9.10 P-C isotherms for La 1−x Ce x Ni 3.55 Co .75 Mn .4 Al .3 – H system [43].

350

300
Capacity, mAh/g 200 La 1-x Ce x Ni 3.55 Co .75 Mn .4 Al .3
250

x = 0.0
150
x = 0.35
100 x = 0.2
x = 0.5
x = 0.75
50
x = 1.0
0
0 50 100 150 200 250 300
cycles
Figure 9.11 Charge capacity, Q, vs charge–discharge cycles
for La 1−x Ce x Ni 3.55 Co .75 Mn .4 Al .3 electrodes [43].
corrosion rate, and H content (n) vs Ce content. The plot clearly shows the
anomalous correlation of lattice expansion with corrosion; thus one concludes that
the corrosion inhibition stemming from the presence of Ce is due to a surface
effect. This conclusion is supported by previous work reporting that a film of CeO 2
on metal surfaces inhibits corrosion [45]. XAS (X-ray absorption spectroscopy)
studies discussed in Section 9.3 confirm the corrosion inhibition effect of Ce [46].