Chemical reduction-induced defect-rich bismuth oxide-reduced graphene oxide anode for high-performance...

We prepare bismuth oxide-reduced graphene oxide (Bi₂O₃-rGO) composite anode using a one-step chemical precipitation/reduction method. Under a reducing atmosphere, oxygen atoms on the surface of Bi₂O₃ are gradually removed and neighboring oxygen atoms migrate to the surface, leaving oxygen vacancies. Defective Bi₂O₃ enhances the number of active sites, providing additional pseudocapacitive performance. The transition metal oxide-based Bi₂O₃ acts as an anode, providing capacitive performance that far exceeds that of conventional carbon materials. Moreover, the introduction of rGO forms a conductive network for Bi₂O₃, improving capacitive contribution and ion diffusion capabilities for the electrode. The Bi₂O₃-rGO-100 (GO added at 100 mg) exhibits a high specific capacitance of 1053F/g at 1 A/g, significantly higher than that of Bi₂O₃ (866F/g). The Bi₂O₃-rGO-100 anode and Ni₃Co₂-rGO cathode are assembled into a battery-type supercapacitor. The coin-cell device achieves an energy density of 88.2 Wh kg^-1 at a power density of 850 W kg^-1. The Ni₃Co₂-rGO//Bi₂O₃-rGO-100 pouch-cell device demonstrates an extremely low R_ct of 0.77 Ω. At a power density of 850 W kg^-1, the energy density reaches 118.5 Wh kg^-1, and remains 67.4 Wh kg^-1 at 8500 W kg^-1.