In-situ rooting biconical-nanorods-like Co-doped FeP @carbon architectures toward enhanced lithium storage performance

Abstract

With desirable high capacity, theoretical work voltage and abundant resources, iron phosphide (FeP) has been garnered much consideration as a hopeful anode material for lithium-ion batteries (LIBs). Nevertheless, structural stability and low electronic conductivity restrict its application. Herein, metal organic frameworks (MOFs)-derived biconical-nanorods-like Co-doped FeP confined by phosphorus-doped carbon (Co-doped FeP@P-C) is successfully prepared. The unique biconical-nanorods-like structure, MOFs in-situ derived carbon coating and Co-doping can accelerate the ion and electron transport efficiency, supply abundant reaction active sites and moderate the volume expansion of FeP material. Benefiting from these merits, the as-prepared Co-doped FeP@P-C anode manifests a high Li+ storage capacity (784 mAh/g at 0.2 A g−1) and long-term stability (555.6 mAh/g at 1 A g−1 after 700 cycles). The experimental studies coupled with density functional theory (DFT) theoretical calculations uncover the effect of Co-doping on boosting charge transfer and enriching the reaction active sites in FeP@P-C anode. Furthermore, the electrochemical kinetic analysis revealed the underlying mechanism of lithium storage in detail, ex-situ X-ray diffraction and X-ray photoelectron spectroscopy analysis. LiCoO2//Co-doped FeP@P-C full-cells are successfully assembled and exhibit relatively high reversible capacity. The present work can provide a rational design and promising cation doping strategy for other metal phosphide anode materials for LIBs.