Anode Electrodeposition of Fe/Fe3O4 composite on Carbon Fabric as a Negative Electrode for Flexible Ni−Fe Batteries

Abstract The nickel‐iron (Ni−Fe) battery is a competitive alternative for electrochemical energy storage, owning to its low cost, high safety, and strong auto‐adaptive ability. However, the self‐discharge and passivation of the negative electrode are the two main issues. In this work, a rock‐like Fe/Fe 3 O 4 composite is synthesized and deposited on carbon fabric (Fe/Fe 3 O 4 @CF) by facile electrodeposition and annealing technologies to serve as a binder‐free anode, which exhibits a large areal capacity of 0.466 mAh cm −2 and long‐term cycling durability. Moreover, the flexible device is assembled by employing Fe/Fe 3 O 4 @CF‐750 as anode and Ni(OH) 2 @CF as cathode. The above battery displays an enhanced operating voltage up to 1.7 V, impressive mechanical flexibility, outstanding cycling stability (86.2 % retention of initial value over 6000 charge‐discharge cycles), and satisfactory voluminal capacity of 1.33 mAh cm −3 , indicating its potential application for energy supply systems of modern wearable electronics.