Fe2P nanoparticles-doped carbon nanofibers with enhanced electrons transfer capability as a self-supporting anode for potassium-ion battery

Carbonaceous materials with various structures and morphologies have been widely investigated as anode for potassium-ion batteries (PIBs), owing to their low cost, non-toxicity, environmental-benignity, etc. Among them, carbon nanofibers (CNFs) synthesized by electrospinning technique usually exhibit higher flexibility, thus they can be directly used as a self-supporting electrode. Accordingly, the overall electrochemical performance is obviously improved, and the batteries assembly procedure is also greatly simplified. However, intrinsic electronic conductivity of CNFs cannot sufficiently meet fast charging/discharging requirements at high current densities. Herein, iron phosphide nanoparticles-doped CNFs (Fe2P-CNFs) are well fabricated by electrospinning, phosphorylation, and carbonization route. The resulting Fe2P-CNFs, their internal Fe2P nanoparticles with high electronic conductivity (3.3 x 10(-1) S cm(-1), Fe2P single crystal) can accelerate electrons transfer, and simultaneously create numerous defects for K-ions storage. Besides, amorphous features of CNFs can provide adequate sites/voids to accommodate more K-ions. Based on this, when Fe2P-CNFs are used as a self-supporting anode for PIBs, they deliver excellent reversible capacity (379.2 mAh g(-1) ), high-rate capability, and ultra-long cycle lifespan (179.6 mAh g(-1) over 2000 cycles at 2000 mA g(-1)). Therefore, this work demonstrates the unique merits of Fe2P doping for improving conductivity, which may help exploit other carbon materials with high performance. (c) 2021 Elsevier Ltd. All rights reserved.

Automated summary

This study demonstrates the synthesis of iron phosphide nanoparticles-doped carbon nanofibers, which exhibit high conductivity and amorphous features, leading to improved electrochemical performance and cycle lifespan of potassium-ion batteries.