Core-shell structured Bi@graphdiyne nanospheres enable high rate capacity and outstanding stability for sodium-ion batteries

Bismuth is a promising anode material for sodium-ion batteries (SIBs) due to its ultrahigh theoretical volumetric capacity. However, its practical application is hindered by volume expansion during cycling, which leads to rapid capacity degradation. In this study, we reported an in-situ catalytic growth approach to synthesize Bi@GDY, a nanocomposite material comprising bismuth nanospheres encapsulated within a graphdiyne (GDY) core-shell structure. This unique architecture effectively mitigated volume expansion while enhancing the sodium storage performance, resulting in remarkable electrochemical properties, including high capacity, superior cycling stability, and reliable performance over a wide temperature range. The Bi@GDY anode demonstrated an outstanding capacity of 361.6 mAh g⁻¹ with a retention rate of 96.9 % after 3000 cycles. In-situ and ex-situ characterizations revealed improved reaction kinetics and confirmed the characteristic alloying/dealloying mechanism. Furthermore, a Bi@GDY//NVP full cell delivered a high capacity of 183.2 mAh g⁻¹ after 700 cycles with a retention rate of 86.9 %, underscoring its potential for practical SIB applications. These findings position Bi@GDY as a highly promising anode material for next-generation SIBs.