High areal capacity liquid bismuth-air batteries with Bi-Bi2O3 mixed conductor enhanced anode charge transfer

Liquid metal electrodes are attractive in the field of energy storage due to their remarkable attributes such as high safety, cost effectiveness, extended lifespan, and high energy density. In this study, we develop a liquid bismuth–air battery owing to the advantageous oxygen ion conductivity offered by bismuth trioxide (Bi 2 O 3 ). Meanwhile, a Sb 2 O 3 –CuO–SnO 2 ceramic with corrosion resistance and stable conductivity in both reductive Bi and oxidizing Bi 2 O 3 are employed as the anode current collector. Impedance spectrum analysis and cross-sectional microscopic characterization are consistent with the formation of a heterogeneous Bi–Bi 2 O 3 architecture, which may provide mixed ionic–electronic conduction within the anode during discharge. This behavior, as inferred from morphological and electrochemical data, correlates with a volumetric specific capacity of 3580 mAh/cm 3 (94.6 % of the theoretical capacity) and an areal capacity of 2326 mAh/cm 2 under the tested conditions. The high areal and volumetric capacities, together with stable operation observed for >200 h in our tests, indicate the potential of liquid Bi–air batteries for high-density, high-temperature energy storage.