Graphene-interconnected Bi@Bi₂O₂CO₃ heterostructures with enhanced electrochemical kinetics and stability for supercapacitors

Despite their high theoretical capacity, Bi-based anodes are plagued by sluggish charge-transfer kinetics and severe structural degradation originating from poor electrical conductivity and repeated volume variation during alloying/dealloying. Herein, a graphene nanoribbon-interconnected Bi@Bi₂O₂CO₃ (B/BOC-GR_0.1) heterostructure is designed to simultaneously establish a continuous conductive network and reinforce the heterointerface. The Bi₂O₂CO₃ shell effectively accommodates cyclic strain and stabilizes the electrode architecture, while graphene nanoribbons strengthen interfacial electronic coupling and accelerate electron transport, thereby synergistically promoting reaction kinetics and structural robustness. As a result, B/BOC-GR_0.1 delivers 1560 C·g⁻¹ at 1 A·g⁻¹ and retains 795 C·g⁻¹ at 50 A·g⁻¹, greatly surpassing those of Bi anodes (623 C·g⁻¹ at 1 A·g⁻¹, 281 C·g⁻¹ at 50 A·g⁻¹). Moreover, after 5000 cycles at 10 A·g⁻¹, B/BOC-GR_0.1 maintains approximately 90% of its initial capacity. The constructed asymmetric supercapacitor achieves an energy density of 70 Wh·kg⁻¹ at a power density of 752 W·kg⁻¹, highlighting the potential of the designed heterostructure for advanced electrochemical energy-storage applications.