Effect of carbon additives on the positive active mass of AGM lead acid battery

With the ever-increasing global population and the socio-economic development of many countries, the demand for diverse and efficient energy resources has become critical. Furthermore, concerns regarding environmental sustainability have propelled significant attention toward green energy technologies. Among these, electrochemical energy storage devices, such as lead-acid batteries (LABs), play a crucial role in addressing the intermittency of renewable energy sources and enabling environmentally friendly applications, such as electric vehicles. LABs, the first generation of rechargeable batteries invented in the 19th century, have undergone continuous technological advancements and are projected to remain a significant part of the battery market at least until 2030. However, side electrochemical reactions in LABs limit their lifespan and capacity. To address these challenges, the development of advanced electrodes incorporating carbon additives, such as carbon black, carbon nanotubes, and graphite, has emerged as a promising solution. In this study, various carbonaceous additives, included Carbon black, Carbon nanotubes and Graphite, each in 3 chemical concentrations 0.4, 1.2 and 1.6 weight percentages, were introduced into the positive active mass (PAM) of LABs, and their effects on water electrolysis, charge/discharge capacity, and mechanical stability were investigated. Interfacial studies revealed the formation of a more uniform and crack-free corrosion layer at the interface between the current collector and PAM upon the introduction of carbon additives. The results demonstrated that the incorporation of carbon additives significantly improved battery performance. Water electrolysis and corrosion reactions occurred at lower currents and more positive overvoltages, with the maximum oxygen evolution current reduced by 50% and the onset potential of corrosion shifted from 0.08 V to 0.16 V. The recombination ratio increased from approximately 80% to 95%, while the extent of sulfation decreased from 5% to 1%. Regarding the life-cycle tests, the results were mixed: with low amounts of carbon additive, similar or faster self-discharge of batteries was observed. However, increasing the additive concentration led to a 20% improvement in discharge capacity in some cases. These findings highlight the potential of carbonaceous additives in enhancing the efficiency and durability of LABs, paving the way for their broader application in sustainable energy systems.