Performance evaluation of a 2 V Flooded lead–acid battery prototype cell with carbon–ceria hybrid additives in the negative electrode

Among the various electrochemical storage systems, lead–acid batteries (LABs) stand out due to their low material and manufacturing costs, good safety profile, and high recyclability. Nevertheless, the performance of LABs remains limited in demanding applications, primarily due to sulfation at the negative electrode, which is closely related to water loss. To address these challenges, several studies have explored the incorporation of carbon-based materials into the negative electrode, reporting notable improvements in conductivity, charge acceptance, and cycling stability. In parallel, metal oxides have been employed to enhance properties such as surface area, mechanical strength, and overall electrode durability. This work investigates the synergistic effect of a carbon–ceria (CeO₂) hybrid compound, with different ceria loading, as an additive incorporated in the negative electrode to improve the performance and lifetime of LABs. The synthesized additives were characterized by elemental analysis to quantify the elemental composition; surface area and pore distribution were determined using the Brunauer–Emmett–Teller (BET) method; X-ray Diffraction (XRD) was employed to identify the crystalline phases present; surface morphology and the spatial distribution of ceria within the carbon structure were examined by Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM), respectively; and finally, electrochemical tests in a three-electrode system were conducted to evaluate the hydrogen evolution reaction (HER) of the different additives. The additives were introduced into the negative electrode during the preparation stage. A 2 V flooded lead–acid battery with a 2P1N configuration was assembled and formed to generate the active materials. Subsequently, electrochemical tests were carried out. In particular, linear Sweep Cyclic voltammetry (LSC) measurements were used to identify the potential range in which the hydrogen evolution reaction (HER) becomes most significant, complemented by chronopotentiometry with constant current steps to quantify the percentage of hydrogen evolved under overcharging conditions. The tests were conducted again following charge–discharge cycling to assess the electrode performance under stressed conditions. Finally, post-mortem analyses of the negative electrodes were performed to provide further insight into the electrochemical results. SEM, Energy-Dispersive X-ray Spectroscopy (EDX), XRD, and Raman spectroscopy were employed to determine surface phase composition, structure and to monitor sulfation progression.