Heterogeneous Fe-Ni-P nanosheet arrays as a potential anode for sodium ion batteries

Transition metal phosphates (TMPs) are considered as promising anode materials for sodium-ion batteries (SIBs) due to their high theoretical capacity (up to 1000 mAh g −1 ) and low cost. However, the poor electrochemical reaction kinetics and large volume expansion of TMPs are not conducive to practical applications in SIBs. In view of this, a kind of self-supported iron nickel phosphide (Fe-Ni-P) composite nanosheet arrays are obtained by reasonable hydrothermal reaction and phosphidation process. The nanosheet arrays construction can significantly release the mechanical strain and promote electrochemical reaction kinetics. Furthermore, the volume expansion can be largely alleviated by the synergistic effect of Fe 2 P and Ni 2 P. Benefiting from the unique design, the robust Fe-Ni-P arrays manifest remarkable Na + storage capability. The Fe-Ni-P nanosheet arrays exhibit a large discharge capacity of 300.9 mAh g −1 after 100 cycles at 0.1 A g −1 . And there is a reversible capacity of 201.7 mAh g −1 can be maintained without obvious capacity loss after 200 cycles at 0.5 A g −1 in SIBs.