Long-Lifespan Fibrous Aqueous Ni//Bi Battery Enabled by Bi₂O₃-Bi₂S₃ Hierarchical Heterostructures

Bismuth oxide (Bi₂O₃) materials are considered as great promising anodes for aqueous batteries on account of the high capacity as well as wide potential plateau. Nevertheless, the low conductivity and severe volumetric change of Bi₂O₃ in the course of cycling are the main limiting factors for their application in energy-storage systems. Herein, we propose and design unique hierarchical heterostructures constructed by Bi₂O₃ and Bi₂S₃ nanosheets (NSs) manufactured immediately on the surface of carbon nanotube fibers (CNTFs). The Bi₂O₃-Bi₂S₃ (BO-BS) exhibits enhanced conductivity and increased stability in comparison with pure Bi₂O₃ and Bi₂S₃. The BO-BS NSs/CNTF electrode indicates exceptional rate capability and cycling stability, while creating a high reversible capacity of 0.68 mAh cm^-2 at 4 mA cm^-2, as anticipated. Additionally, the quasi-solid-state fibrous aqueous Ni//Bi battery that was built with the BO-BS NSs/CNTF anode delivers an exceptional cycling stability of 52.7% capacity retention after 4000 cycles at 80 mA cm^-2, an ultrahigh capacity of 0.35 mAh cm^-2 at 4 mA cm^-2, and a high energy density of 340.1 mWh cm^-3 at 880 mW cm^-3. This work demonstrates the potential of constructing hierarchical heterostructures of bismuth-based materials for high-performance aqueous Ni//Bi batteries and other energy-storage devices.