Thermal In Situ Synthesis of Bi₂O₃/Porous Corn Cob Biochar Composites as an Anode Additive for Lead–Carbon Batteries and Their Properties

Abstract

Lead−carbon batteries (LCBs) and conventional lead−acid batteries (LABs) exhibit similar advantages in terms of safety, cost, and stability. The addition of carbon material to the negative plate can considerably alleviate the irreversible sulfation of the negative plate of the battery and significantly extend its cycle life. However, due to the low hydrogen evolution potential of carbon materials, when added to the negative plate, it will cause serious hydrogen evolution. In this paper, porous corn cob biochar (CCB) composites (Bi 2 O 3 @C-4) with high hydrogen evolution potential were prepared by in situ thermal synthesis method on CCB substrate. A large amount of Bi and Bi 2 O 3 adhere to the surface of Bi 2 O 3 @C-4 and occupy the adsorption site of H + , which slows down the hydrogen evolution rate and increases the hydrogen evolution potential. Furthermore, Bi 2 O 3 @C-4 has mesoporous and macroporous structures, which not only enable the storage of electrolytes but also provide channels for ion transport to accelerate the conversion of Pb/PbSO 4 , effectively inhibiting the formation of large PbSO 4 crystals. In addition, the interior of the macropores also offers nucleation sites for the deposition of Pb 2+ . Finally, the effect of Bi 2 O 3 @C-4 as an additive on the performance of LCBs was elaborated. At a discharge rate of 0.1 C, the initial discharge-specific capacity of LCBs with added Bi 2 O 3 @C-4 (167.7 mAh g −1 ) was 47% higher than that of the blank batteries (114.1 mAh g −1 ). The high-rate partial state of charge (HRPSoC) cycle life test with a discharge rate of 1 C results in a cycle life of Bi 2 O 3 @C-4 (36,524 cycles) that is 5.1 times longer than that of a blank battery (7,169 cycles). In conclusion, Bi 2 O 3 @C-4 exhibits a dual synergistic effect of high hydrogen evolution potential and porous structure, which not only reduces the hydrogen evolution rate of the negative plate, but also inhibits the irreversible sulfation of the negative plate, providing valuable insights for enhancing the performance of LCBs.