Facile Galvanic Replacement Construction of Bi@C Nanosheets Array As Binder‐Free Anodes for Superior Sodium‐Ion Batteries

Bismuth (Bi) possesses an ultrahigh theoretical volume capacity (3800 mAh cm-3) and low embedding potential stimulated considerable attention as anodes for sodium-ion batteries (SIBs). However, its practical application is still hampered by the huge volume variation during the charge/discharge process. To settle this issue, Bi@C nanosheet arrays (Bi@C-NSA) are fabricated on copper foam via a facile galvanic replacement followed by in situ polymerization of dopamine and an annealing procedure. The carbon-coated nanosheet array structure not only accommodates the volume expansion during cycling and maintains electrode stability, but also facilitates rapid electron/ion transport. Due to the unique structural design, this Bi@C-NSA exhibits an impressive capacity of 315.72 mAh g-1 after 1500 cycles under 1 A g-1. Furthermore, a series of in situ/ex situ techniques reveal that this Bi@C-NSA possesses superior reaction kinetics and undergoes a typical alloying/dealloying storage mechanism. Furthermore, Bi@C-NSA also achieves commendable reversible capacity and cycling stability in a wide temperature range (0 degrees C-60 degrees C). Notably, the assembled Na3V2(PO4)3//Bi@C-NSA full cell demonstrates a capacity of 325 mAh g-1 after 50 cycles at 0.05 A g-1, which promises for practical applications. This galvanic replacement strategy spearheads a way to prepare nanoarray electrodes and will accelerate the development of sodium-ion batteries. Bismuth@C (Bi@C) nanosheet arrays are fabricated via a facile galvanic replacement strategy coupled with an in situ dopamine coating and annealing route. Due to the unique nanosheet array design, this Bi@C anode could effectually ameliorate the volume fluctuation, shorten the diffusion distance of Na+ ions, and thus facilitate the electrochemical reaction kinetics, thereby earning excellent rate capability and ultralong cycling stability. image