Preparation of a Ni3Sn2 alloy-type anode embedded in carbon nanofibers by electrospinning for lithium-ion batteries

Abstract

A pure-phase Ni₃Sn₂ intermetallic alloy encapsulated in a carbon nanofiber matrix (Ni₃Sn₂@CNF) was successfully prepared by electrospinning and applied as anode for lithium-ion batteries. The physical and electrochemical properties of the Ni₃Sn₂@CNF were compared to that of pure CNF. The resultant Ni₃Sn₂@CNF anode produced a high initial discharge capacity of ∼1300 mA h g⁻¹, later stabilizing and retaining ∼350 mA h g⁻¹ (vs. 133 mA h g⁻¹ for CNF) after 100 cycles at 0.1C. Furthermore, even at a high current density of 1C, it delivered a high initial discharge capacity of ∼1000 mA h g⁻¹, retaining ∼313 mA h g⁻¹ (vs. 66 mA h g⁻¹ for CNF) at the 200th cycle. The superior electrochemical properties of the Ni₃Sn₂@CNF over CNF were attributed to the presence of electrochemically active Sn and decreased charge-transfer resistance with the alloy encapsulation, as confirmed from cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) results. Finally, post-mortem field-emission scanning electron microscopy (FE-SEM) images proved the preservation of the carbon nanofibers and the alloy after cycling, confirming the successful accommodation of the volume changes during the alloying/dealloying reactions of Sn in the Ni₃Sn₂@CNF.