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

Abstract 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 °C–60 °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.