Enhancing reversible sulfation of PbO₂ nanoparticles for extended lifetime in lead-acid batteries

The cycle life of commercial lead-acid batteries could potentially be improved by suppression of the battery aging mechanism. In this context, one of the main challenges is the irreversible phase transformation from PbSO₄ to PbO₂ at the positive electrode upon charging. We herein report a nanoparticle strategy at tens of nanometers length scale that can enhance the reversible phase transformation from PbSO₄ to PbO₂ upon charging, thus potentially extending the lifetime of these batteries. Our combined theoretical and experimental studies suggest that control over the initial size of the PbO₂ nanoparticles at the positive electrode is critical to the aging mechanism, with PbO₂ nanoparticles of ~100 nm in diameter suppressing sulfation, which leads to a reversible phase transformation from PbSO₄ to PbO₂. In addition, PbO₂ nanoparticles (100 nm in diameter) can provide a greater robustness in the context of shedding of the active materials from the positive grid. These results suggest that lead-acid batteries can be operated with an extended lifetime partly by addressing the intrinsic aging issues associated with irreversible sulfation.