Improving the rate capacity and cycle stability of FeP anodes for lithium-ion batteries via in situ carbon encapsulation and copper doping

Xiaochun Lin; Yanfei Ke; Xi Peng; Cheng He; Xiaoyang Zhao; Xin Xiao; Xiaoming Lin; Junmin Nan

doi:10.1016/j.jcis.2022.12.054

Improving the rate capacity and cycle stability of FeP anodes for lithium-ion batteries via in situ carbon encapsulation and copper doping

J Colloid Interface Sci. 2023 Mar 15:634:346-356. doi: 10.1016/j.jcis.2022.12.054. Epub 2022 Dec 13.

Authors

Xiaochun Lin¹, Yanfei Ke¹, Xi Peng¹, Cheng He¹, Xiaoyang Zhao², Xin Xiao³, Xiaoming Lin⁴, Junmin Nan⁵

Affiliations

¹ School of Chemistry, MOE Key Laboratory of Theoretical Chemistry of Environment, South China Normal University, Guangzhou 510006, PR China.
² Department of Environmental Engineering, Henan Polytechnic Institute, Nanyang 473009, PR China.
³ School of Chemistry, MOE Key Laboratory of Theoretical Chemistry of Environment, South China Normal University, Guangzhou 510006, PR China. Electronic address: xiaox@scnu.edu.cn.
⁴ School of Chemistry, MOE Key Laboratory of Theoretical Chemistry of Environment, South China Normal University, Guangzhou 510006, PR China. Electronic address: linxm@scnu.edu.cn.
⁵ School of Chemistry, MOE Key Laboratory of Theoretical Chemistry of Environment, South China Normal University, Guangzhou 510006, PR China. Electronic address: jmnan@scnu.edu.cn.

PMID: 36535170
DOI: 10.1016/j.jcis.2022.12.054

Abstract

FeP has emerged as an appealing anode material for lithium-ion batteries (LIBs) thanks to its high theoretical capacity, safe voltage platform and rich resources. Nevertheless, sluggish charge transfer kinetics, inevitable volume expansion and easy agglomeration of active materials limit its practical applications. Here, novel Cu-doped FeP@C was synthesized by a synergistic strategy of metal doping and in situ carbon encapsulation. The optimized Cu-doped FeP@C anode demonstrates a highly reversible specific capacity (920 mAh g^-1 at 0.05 A g^-1), superb rate performance (345 mAh g^-1 at 5 A g^-1) and long-term cycle stability (340 mAh g^-1 at 2 A g^-1 after 600 cycles). The electrochemical mechanism was investigated by cyclic voltammetry, kinetic analysis and DFT calculations. The results reveal that carbon frameworks can improve the conductivity and slow down the volume expansion, with highly dispersed FeP facilitating Li-ion migration during the charge and discharge processes. Additionally, Cu doping leads to rearrangement of the charge density and an additional lattice distortion in FeP, which boosts the electron mobility and enriches the surface-active sites, promoting electrochemical reaction and charge storage. This study presents a feasible and effective design for developing transition metal phosphate (TMP) anodes for high-performance LIBs.

Keywords: Conversion-type anode; In situ carbon encapsulation; Iron phosphide; Lithium-ion batteries; Metal doping.