Fig. 8 shows the discharge curves of the single 205 Ah cells. At the 0.2C rate (=41 A) discharge, the voltage and discharge capacity were almost equivalent to each other. At the 2C rate (=410 A) discharge, the Co-free cell maintained a 1.25 V voltage and 97% Ah-efficiency. On the other hand, the cell containing the MmNi3.7Co0.7Mn0.3Al0.3 alloy (dashed line) exhibited a 1.15 V discharge and 90% Ahefficiency. The voltage of the former one is higher by 100 mV than that of the latter one. The combination of the Co-free materials and GIGACELL structure would be suitable for industrial use as a high-power, large-sized battery with a long cycle-life