Binder-Free Iron Nanosheet Arrays by an Electrodeposition Method for Flexible

Abstract

Aqueous iron-iodine batteries (IIBs) are considered as a promising for portable and wearable electronics by virtue of the high theoretical specific capacity (~960 mA h g-1) and rich natural abundance of Fe. However, the low actives utilization ratio of Fe foil and poor flexibility limits their practical usage. Here, we fabricate binder-free Fe nanosheet arrays electrode as anodes by a simple and controllable electrochemical technique for flexible Fe//I2 batteries, which dramatically improve actives utilization ratio, avoid electrode damage/fracture caused by chemical corrosion and enhance the reaction kinetics. As a result, our assembled aqueous FeCC//I2@AC/CNT battery exbibits a stable cycling of 400 cycles, superior to that of Fe foil and anode-free IIB. With the use of polyacrylamide-FeSO4 hydrogel electrolyte, a flexible quasi-solid-state Fe-CC//I2@AC/CNT battery is further designed. It has a high specific capacity of ~195.4 mAh g-1 at a high rate of 3A g-1, better than previous zinc ion batteries and IIBs. We also demonstrate the good ambient stability in terms of temperature and pressure and excellent flexibility of the quasi-solid-state FeCC//I2@AC/CNT battery. Our study promotes the development of low-cost and high safety flexible iron iodine batteries on portable and wearable electronics.

Keywords: flexible iron-iodine batteries, binder-free Fe nanosheet arrays, high actives utilization ratio, good rate performance