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Three-Dimensional Hierarchical Flower-like FeP Wrapped with N-Doped Carbon Possessing Improved Li + Diffusion Kinetics and Cyclability for Lithium-Ion Batteries.

Research paper by Xueying X Li, Xia X Wang, Wenhua W Yang, Zengquan Z Zhu, Ruijie R Zhao, Qiang Q Li, Hongsen H Li, Jie J Xu, Guoxia G Zhao, Hongliang H Li, Shandong S Li

Indexed on: 19 Jan '21Published on: 04 Oct '19Published in: ACS Applied Materials & Interfaces



Abstract

Transition metal phosphides (TMPs) have potential application in lithium-ion batteries (LIBs) because of high theoretical capacities and low cost, nevertheless, they possess dramatic volumetric variation during cycling associated with poor conductivity, limiting their practical applications. Here, a three-dimensional (3D) hierarchical flower-like FeP coated with nitrogen-doped carbon layer (FeP@N, C hybrid) was constructed through a solvothermal method, then a phosphating approach under low temperature. N-doped carbon not only suppresses the volume fluctuation of FeP, but also promotes electron transfer, accompanied by catalyzing the decomposition of LiP to improve reversibility of the FeP@N, C hybrid during cycling processes. Additionally, 3D flower-like architecture assembled from porous nanosheets is also beneficial for shortening the migration path of ions as well as improving contact area of electrode with electrolyte, which enhance the reaction kinetics, proved by both experimental measurement of Li diffusion coefficient and resistivity, along with calculation of density functional theory (DFT). Consequently, the 3D hierarchical flower-like FeP@N, C hybrid performs excellent cyclic stability (569 mAh g at a current density of 500 mA g for the 300 cycle) and rate performance (331.94 mAh g at a high current density of 5 A g) for LIBs. Based on above results, the fabrication strategy in this work could offer a thought to design other high-performance metal phosphides hybrids.