Achieving high-capacity and durable sodium storage by constructing a binder-free nanotube array architecture of iron phosphide/carbon.

ABSTRACT

The conversion-type anode material of iron phosphide (FeP) promises enormous prospects for Na-ion battery technology due to its high theoretical capacity and cost-effectiveness. However, the poor reaction kinetics and large volume expansion of FeP significantly degrade the sodium storage, which remains a daunting challenge. Herein, we demonstrate a binder-free nanotube array architecture constructed by FeP@C hybrid on carbon cloth as advanced anodes to achieve fast and stable sodium storage. The nanotubular structure functions in multiple roles of providing short electron/ion transport distances, smooth electrolyte diffusion channels, and abundant active sites. The carbon layer could not only pave high-speed pathways for electron conductance but also cushion the volume change of FeP. Benefiting from these structural virtues, the FeP@C anode receives a high reversible capacity of 881.7 mAh/g at 0.1 A/g, along with a high initial Coulombic efficiency of 90% and excellent rate capability and cyclability in half and full cells. Moreover, the sodium energy reaction kinetics and mechanism of FeP@C are systematically studied. The present work offers a rational design and construction of high-capacity anode materials for high-energy-density Na-ion batteries.