Amorphous FePx nanoparticles embedded in N, P-codoped carbon nanofibers for high capacity and long cycle Li-ion batteries

Transition metal phosphides (TMPs) are ideal anodes for lithium-ion batteries (LIBs) due to their high theoretical specific capacity and suitable lithiation potential. However, transition metal phosphides suffer from the shortcomings of large volume change and low electrical conductivity, resulting in poor rate performance and short cycle life. In this paper, nanofibers consisting of amorphous FeP x nanoparticles and N, P-codoped carbon substrate are synthesized by electrospinning and in-situ phosphidation to address these challenges. The amorphous structure with no grain boundary and isotropy can provide more Li + transport channels and Li + storage sites. Moreover, the N, P-codoped carbon substrate can effectively improve the electronic conductivity of the electrodes and the structural robustness of the nanofibers. Due to the unique structure and composition, the FeP x /C nanofibers exhibit excellent electrochemical performance when used as anodes for LIBs (stable cycling over 2200 cycles at 1 A g −1 ). It is suggested that the large pseudo-capacitance and fast Li + diffusion resulting from the amorphous structure are important reasons for the excellent electrochemical performance of FeP x /C nanofibers. This work provides a new idea to optimize the electrochemical performance of TMPs, which is expected to be used in other conversion anode materials.