High-rate and stable iron phosphide nanorods anode for sodium-ion battery

This study reports iron phosphide (FeP) nanorod arrays on Ti substrates (FeP NRs/Ti) as anode for full sodium-ion batteries. The FeP nanorod arrays electrodes exhibit a high-rate capability of 414.7 mAh g(-1) at 100 mA g(-1) in the semi-battery tests (sodium foil as the counterpart) and 196.2 mAh g(-1) at 2000 mA g(-1). The high reversible capacity can be ascribed to an augmented sodium-ion diffusion coefficient (similar to 10(-12) cm(2) s(-1)) originated from the nanorod arrays. Besides, the binder-free and highly oriented-1D FeP electrode helped to alleviate the volume change during (dis)charging processes thereby ensuring a long cycling life (207.7 mAh g(-1) over 1000 cycles at 500 mAg(-1) ). Electrochemical and ex-situ studies confirmed the significant contribution of pseudocapacitance to the highly electrochemical performance of FeP nanorod arrays. Most importantly, the sodium-ion full battery based on FeP NRs/Ti as anode and Na3V2(PO4)(3) as cathode materials showed stable cycling performance over 200 cycles at a current rate of 1 C (1 C=100 mA g(-1), voltage range of 2.0-3.6 V), simultaneously possessing a high energy density of 185 Wh kg(-1) at the power density of 200 W kg(-1). We further successfully demonstrated an energy pack by combining four CH3NH3PbI3-xClx-based perovskite solar cells in series and a Na3V2(PO4)(3)-FeP NRs/Ti full sodium-ion battery, achieving a photoelectric conversion and storage efficiency of 5.2% under 1 sun light illumination. (C) 2019 Elsevier Ltd. All rights reserved.