Double Restriction of Bismuth Nanoparticles by Carbon Matrixes for Ultralong−lifespan Sodium Storage

Alloying-type bismuth (Bi) anodes show a high theoretical capacity for sodium-ion batteries (SIB), yet their huge volume expansion and electrode pulverization resulted in poor electrochemical stability. Herein, we proposed a feasible strategy for the preparation of carbon/Bi composite material in which the Bi nanoparticles are uniformly dispersed in the double-layered carbon matrix. Benefiting from the synergistic confinement of the external coating of graphene and the internal layer of MOF-derived carbon, the volumetric expansion and large chemo-mechanical stress of Bi nanoparticles are effectively buffered. Therefore, the GAB@GO-800 anode exhibits a dramatically reversible capacity of 328 mA h g−1 at 0.1 A g−1, exceptional rate capability (299 mA h g−1 at 5 A g−1), and ultrahigh stability of 255 mA h g−1 at 2 A g−1 over 2000 cycles. Such hybrid carbon confinemental strategy via a combination of graphene coating and MOF-derived carbon is expected to be a promising method for the alloying-type anodes of SIBs.