Vacancy and architecture engineering of porous FeP nanorods for achieving superior Li plus storage

With high theoretical capacity (926 mAh g1) and safer voltage platform, Iron phosphide (FeP) as an anode material for lithium ion batteries has attracted a lot of attention. However, FeP also suffers serious capacity fading and unsatisfied rate capability, which are triggered by inferior intrinsic conductivity and large volume expansion. Herein, oriented by density functional theory (DFT) calculations, MOF-derived porous FeP nanorods modified by abundant P vacancies (denoted as V-FeP) were ingeniously designed via a simplified approach to alleviate the above obstacles. As a result, the V-FeP nanorods electrode delivered extraordinary specific capacity (1228.3 mAh g1 at 0.1 A g1 after 120 cycles) and long-cyclic performance (590.7 mAh g1 at 2.0 A g1 after 1000 cycles). Transmission electron microscopy, X-ray absorption fine structure, electron paramagnetic reso-nance and so on were used to character the V-FeP nanorods. The results indicated the supernormal electro-chemical performances of V-FeP nanorods were originated from abundant P vacancies and good distribution of FeP nanoparticles in conductive carbon network, which enhanced electrical conductivity, provided more active sites, shortened the diffusion distances of Li ions and relieved the volume variations. The strategy demonstrates a further direction to effectively improve the lithium storage performance of transition metal phosphides.

Automated summary

Iron phosphide (FeP) as an anode material for lithium ion batteries has high theoretical capacity and safer voltage platform, but suffers from capacity fading and unsatisfied rate capability. A novel approach using MOF-derived porous FeP nanorods modified by abundant P vacancies (V-FeP) greatly improved the electrochemical performance by enhancing electrical conductivity, providing more active sites, and relieving volume variations. Transmission electron microscopy, X-ray absorption fine structure, electron paramagnetic resonance were used to characterize the V-FeP nanorods.