Lead‒acid battery performance has steadily improved during the last century through incremental developments that have accelerated in the last two decades due to the important technological evolutions in the automotive sector and, more recently, the increasing demand for energy storage. After the invention of starved electrolyte/valve regulated lead‒acid (VRLA) batteries, initially through acid (GEL) and later by glass mat absorption (AGM), internal gas-recombination allowed full maintenance free operation. It was, however, in this century that VRLA batteries became a mass market product ideally suited for both automotive and energy storage applications. To cope with new requirements such as improved charge-acceptance to recuperate the energy during short charging periods (automotive) or the ability to maintain battery performance at low state-of-charge over many years of use (energy storage), new versions of the lead‒acid battery have been developed. Among these technological evolutions, the following advanced designs have been introduced.
- Thin-Plate VRLA batteries (with sealed inter-cell connectors) that allow precise internal gas pressure control with individual valves, thereby improving gas-recombination efficiency and state-of-charge balance in every cell.
- Lead‒Carbon electrodes developed by carbon suppliers that enable the battery industry to improve charge-acceptance with new additives or innovative current-collectors.
- Hybrid capacitors that were originally developed as a capacitor electrode directly connected to the negative plate, but more recently have evolved to a double layer electrode where the external surface of the lead plate is covered with a carbon dispersion.
- Bipolar plates, a technology still in development but with significantly improved designs that by using new materials (polymer‒lead composites or silicon‒metal coatings) have the potential to eliminate the top lead connectors, thus reducing weight and improving specific energy.
Nevertheless, despite the recent improvements, lead‒acid batteries are facing strong competition from Li-ion technologies in the new booming markets of e-mobility and energy storage. The traditional markets (automotive and industrial) are still mostly served by lead‒acid, but Li-ion is becoming a strong challenger due to the cost reduction achieved with high volume production for EV applications. The key to the long-term survival of lead‒acid batteries is the ability of the industry to adapt to the new market requirements with incremental future innovations. Enhanced Flooded Batteries (EFB) with carbon nanomaterials, either inside the active mass or attached to the separator, are probably the next step to keep lead-acid as the preferred technology in the automotive 12V market which includes the auxiliary batteries for hybrid and electric vehicles. On the other hand, significant performance improvements (and cost reductions) should be achieved to resist the increasing challenge of Li-ion technologies in the industrial markets. For lead‒acid, focusing on its well-known advantages (safety and sustainability) and with improvement in both recharge ability and cycle-life are the key to retaining some important markets (e.g., Backup systems, Telecoms, Motive Power) that are now at risk. The presentation will discuss innovations that may help lead‒acid batteries to face these challenges and compete with other advanced technologies.
Dr Francisco Trinidad
Francisco Trinidad holds a PhD from the University of Madrid. In 1977, he joined Tudor R&D group and was promoted as the Industrial Development Director in 1992. Following Exide’s acquisition of the company, he became its Research Director in Paris, then the Development Director of Transportation Europe, and more recently the Director of Battery Technology in Exide Europe.
During more than 43 years of experience with several electrochemical systems, he has co- written 25 papers, delivered over 70 presentations at battery conferences, and has 14 international patents.