Bismuth nanoparticles@carbon composite as a stable and high capacity anode for high-voltage bismuth-manganese batteries

Abstract Bismuth (Bi) electrochemistry holds great potential for aqueous energy storage in terms of its highly-reversible redox capability in alkaline solution, low-cost, and safety. However, Bi-based batteries still suffer from limited performance of Bi anodes and unsatisfying output voltage. Herein, to address these issues, we develop an advanced Bi electrode consisting of oxygen-functionalized Bi nanoparticles embedded in porous carbon frameworks (Bi@C), which was paired with a high potential MnO2 cathode via an electrolyte-decoupling configuration to achieve a high voltage bismuth-based battery. The presence of the subtly-designed oxygen interface favors efficient adsorption of OH− ions while its unique 3D carbon matrix provides an interconnected pathway for electron charge transport. As a result, the Bi@C anode exhibits a remarkable capacity (347.2 mAh g−1 at 3 A g−1) close to its theoretical value, an excellent rate capability (60% capacity retention at a high current density of 20 A g−1) and outstanding long-term cyclability (96% capacity retention over 9500 cycles). Furthermore, this new Bi//MnO2 hybrid battery possesses merits of high energy density (213 Wh kg−1) and output voltage (1.62 V). This work is expected to shed some lights on properly elevating the energy density of aqueous Bi batteries via electrode design.