Fig. 4: Characterizations of regenerated Ni55.

a SEM image and b XRD pattern of the regenerated Ni55. c Voltage-capacity profiles for the first cycle at 0.1 C, d rate performance at various current densities of 0.1, 0.3, 0.5, 1.0 and 2.0 C and e cycling performance at 0.3 C for the degraded and regenerated Ni55.