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

Graphical Flexibility approach : A facile two-step process for fabricating a distinctive Fe/Fe 3 O 4 composite deposited on carbon fabric as a negative electrode for a flexible nickel-iron battery is reported. The assembled battery exhibited a high voluminal capacity with a stable operating voltage up to 1.7 V, long-term cyclic stability as well as good mechanical stability and flexibility. 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.