Micron-sized iron oxide functionalized with hydrophobic mesoporous sheets for the Ni–Fe battery

Abstract

Micron-sized Fe₃O₄ is a practical anode material that is used in industrial Ni–Fe batteries, and its ability to simultaneously achieve high capacity and excellent rate capability is very practical and is urgently needed. In this work, through etching industrial Fe₃O₄ particles, hydrophobic mesoporous Fe₃O₄ sheets can be regenerated, and can be dispersed around micron-sized Fe₃O₄ particles when the slurry dries to form a coating on the current collector. These hydrophobic mesoporous sheets in the electrode can improve the electrochemical reaction kinetics and alleviate the volume expansion of micron-sized Fe₃O₄ particles, which is a new and effective way to simultaneously achieve high capacity and excellent rate capability. Our results show that when this electrode is coupled with the NiS cathode, the battery exhibits the capacity of 221.17 mA h g⁻¹ at 0.2 A g⁻¹, and excellent cycling stability of 92% of the initial capacity after 50 cycles, revealing significant performance improvement. Compared with the common strategy of carbon-coating Fe₃O₄ particles to improve the battery performance, this strategy of functionalizing Fe₃O₄ particles with hydrophobic mesoporous sheets is more favorable for performance improvement and large-scale application.